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A Guide to the Endodontic Literature
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Success & Failure:
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Authors |
Description |
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European Soc. Endodontology (1994 IEJ): |
Definition
of Success: Clinical symptoms originating from an
endodontically-induced apical periodontitis should neither persist nor
develop after RCT and the contours of the PDL space around the root should
radiographically be normal. |
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AAE Quality Assurance Guidelines |
Objectives
of NSRCT (= nonsurgical root canal treatment) ·
Prevent adverse signs or symptoms ·
Remove RC contents ·
Create radiographic appearance of well obturated RC
system ·
Promote healing and repair of periradicular tissues ·
Prevent further breakdown of periradicular tissues |
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The
Mantra: ·
Apical periodontitis (=AP; = periapical radiolucency
=PARL) is caused primarily by bacteria in RC systems (Sundqvist 1976;
Kakehashi 1965; Moller 1981) ·
If bacteria in canal systems are reduced to levels that
are not detected by culturing, then high success rates are observed (Bystrom
1987; Sjogren 1997) ·
Best documented results for canal disinfection are
chemomechanical debridement with Ca(OH)2 for at least 1week (Sjogren 1991) ·
Mechanical instrumentation alone (C&S) reduces
bacteria by 100-1,000 fold. But only
20-43% of cases show complete elimination (Bystrom 1981; Bystrom & Sundqvist
1985) ·
Do C&S and add 0.5% NaOCl produces complete
disinfection in 40-60% of cases (Bystrom 1983) ·
Do C&S with 0.5% NaOCl and add one week Ca(OH)2: get
complete disinfection in 90-100% of cases (Bystrom 1985; Sjogren 1991). |
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Problems with the Mantra·
Koch’s postulates cannot be applied to establishing a
bacterial origin of AP (since polymicrobial – Baumgartner) ·
Mantra misses host response contributions (eg;
Stashenko’s P/E selectin knockout mice actually showed increased AP
due to bacteria (thus, phagocytic leukocytes help to minimize AP via
protection against microganisms; implies host defenses regulate the
development of AP) ·
What is the clinical significance of a “non-cultivable”
RC sample when organisms can reproduce in <12h? ·
Implication: the “mantra” is focused on what the
clinician can accomplish with current methods (eg., reduction-disruption of a
bacterial ecosystem). It only
provides general guidance for developing better therapeutic methods, and it cannot
predict clinical success in cases where immunocompetence is altered. ·
Given a polymicrobial etiology and a disease-modifying
host capacity, it is (probably) overly simplistic to correlate one bug with
given signs or symptoms. [Recall
Sundqvist (1992) used odds ratio analysis & concluded that bacterial
pairings in infected RC systems are not random, but appear to be due to
forces such as ecological commensalism.
Since pairings can occur, correlational analysis between bugs and
signs-symptoms may be confounded if one bug is more easily cultivable than
another] |
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Penick, 1961 |
NSRCT with GP.
Still saw PARL at 14 months.
Sx biopsy revealed healing by scar (no inflammation). THL - consider
healing by scar when reviewing post-endo tx (and sx work-ups) |
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Brynolf 1967 |
This study was performed on human cadavers with X-rays
taken of 320 upper incisors. Even
though many radiographs appeared normal, complete histological healing after
NSRCT occurred in only 7% of cases.
Thus, radiographic success doesn't correlate with histological success |
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Green, Walton,
1997 |
Compared radiographic findings of NSRCT to histological
exam of human cadavers. 74% of the teeth with normal radiographic findings
showed NO inflammation. 26% with a
normal periapex radiographically showed histologic signs of inflammation. The
results of this study do not agree with those by Brynolf in 1967 who found
inflammation in the majority of the teeth that had received root canal
treatment. |
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Ingle, Beveridge, |
This study was done to evaluate treated endodontic cases
and determine their rate of success.
33.41% of 3,678 patients returned for recall. 94.45% rate of success. The greatest cause
of failure was interpreted to be obturation (but it may also be poor
C&S). |
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Kerekes, Tronstad 1979 |
Examined 333 patients treated by undergraduate
students. Hand instrumentation with
reamers and Hedstrom files was performed. EDTA and 5% chloramine-T was used
for irrigation. Lat condensation with
gutta percha points coated with Kloroperka N-O. Roots without periradicular
radiolucencies prior to treatment showed better results than those with
radiolucencies. No difference in success between vital and necrotic pulps, or
in teeth with flare-ups during tx . Adequate seal and the apical level of the
root filling were significant factors for the success of tx. |
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Bergenholtz 1974 |
Retrospective study of 84 teeth with trauma and intact
crowns and necrotic pulps. 64% had
microorganisms present (primarily polymicrobial anearobic). |
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Akerblom, Hasselgren 1988 |
Teeth with periapical radiolucencies had lower
healing rates than those without a lesion. In teeth lacking lesions, 97.9%
were judged successful. In the presence of a pre-operative lesion, only 62.5%
teeth were deemed a success. 2-12 yr
follow-up. |
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Ray & Trope
, 1995 |
Radiographic exam of 1010 endodontically treated teeth
restored with a permanent restoration.
The quality of the coronal restoration was significantly more
important than the quality of the endodontic treatment for the presence of apical
periodontitis. |
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Augsburger,
Peters 1990 |
Radiographic evaluation of resorption of ZOE
sealer/gutta-percha extruded into periradicular tissues. The rate of
disappearance of the material did not differ with the presence or absence of
radiolucent lesions, type of ZOE sealer used, or obturation technique. In no
case did an irreversible lesion develop where sealer was expressed. Extruded
material did not prevent radiographic repair of radiolucent lesions. |
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1-Step
vs Multi-Step: Short-term Comparison ·
Pekruhn (1981): Compared postoperative pain after
single-visit and multiple-visit NSRCT.
1 shot = multi-appt (both had 16% popln with pain at 1day) ·
Oliet (1983):
Compared 1 step to multi-appt NSRCT (n=380).
When pain occurred post-op, it typically presented within the first 24
hours; there was no difference between 1 shot vs multi-appt, or for vital vs necrotic cases. Also, no difference in healing at 18
months. A difference in healing was
observed when comparing the quality of the obturation in single visit treated
teeth. Teeth that were overfilled showed less healing than those filled to or
just short of the radiographic apex. ·
Roane, Dryden & Grimes (1983): Compared 1 step to mult-step NSRCT (n=300). No
differences in pain different anatomic groupings or pulp status (necrotic vs
vital). Pain after 1-step was about one-half of pain after multi-appt NSRCT ·
Mulhern and Patterson (1982): 1 step NSRCTs does not
increase post-op pain ·
Southard & Rooney (1984): The article strongly
supports the position that 1-step NSRCT is an acceptable method to treat an abscessed
tooth. 0 of 19 patients had
exacerbations of swelling or pain following treatment. 63% of pts with AAA
were contacted 24hrs post-NSRCT with IND, and all reported no or reduced
pain. Complete resolution of swelling
resolved in 3-7 days. 58% of pts returned at 1 year and all were asymptomatic
and showed radiographic signs of healing. ·
Eleazor & Eleazor (1998): Retrospective study:
Flare-ups: 1 step (3%) < 2-step (8%; p<.01). n=201 consecutive necrotic 1st & 2nd
molars tx with 1-step had 3% flare-up vs n=201 consecutive necrotic 1st
& 2nd molars tx with 2-visit (med= metacresylacetate) had 8%
flare-up (p<.01) |
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Long-term
Comparison Oliet 83 Pekruhn 86 Trope 99 Freidman 95 Sjogren 97 |
1-Step
vs Multi-Step: Long-term Comparison ·
Oliet (1983): Compared
1 step to multi-appt NSRCT (n=380).
When pain occurred post-op, it typically presented within the first 24
hours; there was no difference between 1 shot vs multi-appt, or for vital vs necrotic cases. Also, no difference in healing at 18 months. A difference in healing was observed when comparing the quality
of the obturation in single visit treated teeth. Teeth that were overfilled
showed less healing than those filled to or just short of the radiographic
apex. ·
Pekruhn (1986): Evaluated failure with 1steps (n=925 @ 1 yr). The overall failure rate was 5.2%. Most of the failures had
preexisting apical periodontitis. 18% of these had symptoms. Retreatment
cases had the highest rate of failure at 16.6%. The teeth tx with 1-step
showed 3 times the failure rate as
those previously opened for emergency treatment. The higher failure rates of
those teeth presenting with apical periodontitis may serve as
contraindication for 1-step NSRCT. ·
Bystrom & Sundqvist (1981): One steps do not remove
bacteria in necrotic cases. Ca(OH)2
is the best inter-appt medicament to kill residual bacteria. Simple mechanical debridement with saline
is insufficient to remove all bacteria (although it does reduce bugs by
100-1,000 fold). ·
Sjogren (1997): Teeth with negative bacterial cultures
prior to fill had 94% success rate whereas teeth with positive cultures had
68% success rate. Also demonstrated
that could not reliably obtain negative cultures after just one appt. Others have also reported a simliar
increase in prognosis when obturate canals with negative cultures: Engstrom
(1964) and Oliet (1969). ·
Friedman & Trope (1995 JOE p386): n=378 eval
Ketac-Endo for NSRCT. Multi-appt
NSRCTs with Ca(OH)2 medicament tended (86% vs 76%; p=NS) to have better
success and fewer failures than one-shots.
6-18m follow-up ·
Trope & Orstavik (1999 JOE): Randomized clinical
trial evaluating 1 step vs 2step with or without Ca(OH)2 with 1yr
follow-up. Ca(OH)2 had 74% healing > 1-step (64%; NS
difference) > 2-step with no med (54% healing) ·
Katebzadeh & Trope (1999 JOE ): Dog study infected
teeth with AP with 6m follow-up: C&S to size 45: 1week Ca(OH)2 med gave
better PA healing after 6m than 1-step with LC Roths. 1-step was better than no NSRCT (= open
canals = positive control) ·
Weiger, Axman-Krcmar & Lost (1998 EDT): One-steps
tended (p=0.13) to produce poorer healing than multi-steps using Ca(OH)2 over
18 month period. Used Cox regssion
analysis of raw data from Lost et al (1995; n=76): analysis showed that that
one-steps tended (p=0.13) to produce poorer healing than multi-steps using
Ca(OH)2 over 18 month period |
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Studies
justifying 1 year Recall: ·
Reit (1987): Best recall is at one year. Also rec recalls annually for minimum of 4
years (esp in questionable cases) ·
Rud & Andreasen (1972): If PARL healed at 1 year,
then ok ·
Orstavik (1996): ~76% of apical periodontitis lesions
developing post-tx are seen within 1year.
Therefore, 1yr follow-up predicts long-term success |
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Friedman 1998 Chap in Essential Endodontology by Pitt
Ford & Orstavik |
Meta-analysis of prior success-failure studies. For NSRCT: Apical periodontitis success
rate is 10-25% lower than NSRCT performed in teeth with normal periradicular
tissue (=83-100%). NSRCT Re-tx of
teeth with AP = 56-84% healing. Reviewed 27 studies (from Strindberg 1956 to Ostravik
1996): 78% of studies demonstrated >10% reduction in success. |
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Orstavik 1986 |
Proposed use of PAI (periapical index) to evaluate
radiographic success by comparison to 5 standard images (healthy = 1;
bad=2-5). |
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Davis & Joseph 1971 |
Classic! Teeth
that were fully instrumented, but filled short of the radiographic apex had
best healing. ALSO: Seltzer &
Bender 1963 &67 (human and monkey study with healing eval at 3 months;
overfill = persistent inflammation) |
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Sjogren 1990 |
CRITICAL
STUDY. Necrotic teeth
without AP have 96% success, but necrotic with AP have only 86% success. Best success tx necrotic cases with apical
periodontitis are when the obturation ends within 0-2 mm of radiographic apex
= 94%); underfills are less successful (68% when filled > 2mm from apex)
and overfills are less successful (76%).
Also, re-tx of teeth with AP have low success (62%). Results are similar to Davis & Joseph
(1971). |
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Causes for failure of NSRCT:
(see also: "Differential Dx of PARLs") (If Dx is correct, bacterial infection is primary cause [Lin &
Pascon (1991); Cheung (1996)]. ·
“POOR PAST” (Crump 1979) P--perforation; O--obturation; O--overfill; R--root canal
missed; P--periodontal disease; A--another tooth; S--split; T--trauma ·
Persistant Intraradicular infection (Nair
1990) ·
Sjogren (1997) reduced success when bacteria are present
during obturation (94% vs 68%) ·
Pitt Ford (1982) infected dentinal tubules ·
Orstavik (1990): E. faecalis & Strep sanguis grew
300-400um into dentinal tublues after 14-21 days ·
Enterococcus faecalis in 33% failed NSRCTs (Molander 1998
IEJ) & in 60% failed cases reported by Siren (1997) ·
Actinomycosis israelii found in two case reports of
failed NSRCT. Had to be eliminated by
Sx (Sundqvist 1981 OOO) ·
Persisitent Extraradicular infection, see Simon's review on POP for general
info and nice figs ·
Nair (1984) Actinomyces isrealii . Also reported by Happonen (1986): 81%
samples contained actinomyces, 62% contained arachnica ·
Sjogren (1988) Proprionibacterium proprionicum (aka
Arachnia propionica) ·
Wayman (1992) evaluated 58 NSRCT failures in lesions with
NO oral communication, 83% had bugs in lesion! (93% had bugs in lesions with oral communication). Similar to Iwu (1990) report of 88%
lesions having cultivable bugs. ·
Kirye (1994): found infected cementum. Also Tronstad (1990) reported bacterial
plaque over apical foramen ·
Holland (1980): infected dentinal chips expressed into
periapex. Also reported by Yusuf
(1982) ·
Foreign body reaction (Nair 1990). Small particles of GP are extremely
inflammatory [Sjogren (1995)] ·
Cysts, esp true cysts (Nair 1993, 1996). |
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Grung 1990 |
Success of re-tx combined with endo sx is 24% higher than
endo sx alone |
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Specialist vs Generalist |
As defined ONLY by radiographs, success of NSRCTs is
83-94% (Grahnen 1961; Ingle 1985) in clinical trials and 61-77% (de Cleen
1993; Erckerborn 1989) in epidemiologic studies. The clinical trials represent optimal tx by specialists or
well-supervised students, whereas the epidemiologic studies represent general
practice. (From Ericksen in Essential
Endodontology 1998). |
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Lavstedt 1978 |
(in Norwegian) Teeth with greatest prevalence for apical
periodontitis are max laterals, max 1st premolars and mand first
molars.. |
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Weiger, Axman-Kcmar and Lost EDT 14:1, 1998 |
Reviewed predictors of success of NSRCT from statistical perspective. Based on metanalysis, probability of PARL
healing after NSRCT within 3yr is 0.87-0.89.
Used Cox regssion analysis of raw data from Lost et al (1995; n=76):
analysis showed that one-steps tended (p=0.13) to produce poorer healing than
multi-steps using Ca(OH)2 |
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Studies
showing reduced success of NSRCT with apical periodontitis: Success (%): No PARL PARL N
1. Molvern &
Halse (1988) 91% 68% 207 2. Akerblom, Hasselgren (1988) 98%
62% 64 3. Sjogren (1990) 96% 86%
471 4. Friedman
(1995) 93% 69% 142 |
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The
NSRCT success rate for necrotic teeth vs vital appears equivocal Smith (1993) reports reduced success with necrotic cases Kerekes & Tronstad (1979) reports same success Strindberg (1956) reports increased success with necrotic
cases |
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Success of Re-Tx: ·
No PARL: 89-100% ·
PARL: 56-71% Sources; Molvern & Halse 1988; Sjogren 1990 and
Frideman 1995 (N = 569). ·
Bergenholtz (1979 Scan JDR): Classic on re-tx. Group being re-tx for prosth indication
(ie, not failing) still had 6% failure rate ·
Allen (1989 JOE): Classic: Retrospective study of 1,300
cases. 65% success 16%
uncertain. NSRCT Re-tx better success
than sx (73% vs 57%). ·
Sjogren (1990): re-tx teeth with AP has 62% success rate ·
Briggs & Scott (1997): Re-tx is preferable over endo
sx (“evidence based” analysis).
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Moiseiwitsch & Trope
(1998) Re-tx is preferable over endo sx |
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Success of Surgical Endo: ·
Apical Sx:
59% ·
Re-Tx + Apical Sx: 80% ·
Source: Friedman’s analysis in Essential Endo. (nice initial meta-analysis approach). ·
Dorn & Gartner (1990 JOE): Retrospective study in two
endo offices (non-randomized, etc): Success Super EBA 95%; IRM 91% and
amalgam 75% ·
Rubenstein
& Kim (1999 JOE): CRITICAL:
Using scope, ultrasonics and Super EBA: n=94 cases (2/3 posterior & 1/3
anterior): 97% radiographic success at 3-12m follow-up with mean
healing of 7.2m (criteria = restoration of lamina dura). 85% granuloma and
15% cysts with no difference in time
to heal. Isthmuses were found in 25%
of the cases. ·
Testori
(OOO 1999): n=302 apices (181 teeth) with 5yr follow-up standardized
radiographs with 2 observers: 85% complete healing with ultrasonic
tips and super-EBA at 4.6yr versus 68% complete healing for rotary
microhandpiece with amalgam. Saw
reduced success when had poor or no prior NSRCT (see Danin below) ·
Danin (1999 OOO): Did endo sx in necrotic cases without
any NSRCT. 50% mod-complete success
at 1yr (but used bur and glass ionomer for endo sx). But- 90% of these cases
had cultivable bacteria in canals.
Important point: cases may show radiographic success after sx even
with bacteria in canals. ·
Bradford (1999 OOO): defines sx success as 1) absence of
symptoms; 2) absence of swelling, sinus tract, signs of infection; 3)
radiographic evidence of healing; 4) continued normal functioning of the
tooth. Summarized qualities of an
ideal root-end filling matieral: biocompatability, apical sealability and
handling characteristics ·
Briggs & Scott (1997): Re-tx is preferable over endo
sx (“evidence based” analysis).
Also, Moiseiwitsch & Trope
1998. ·
Lin (1996 IEJ): Discussed periradicular curretage. Remove for visibility. NEED NOT REMOVE ALL GRANULATION TISSUE FOR
HEALING TO TAKE PLACE! Moiseiwitsch & Trope
(1998 OOO): Sx should not be considered primary tx when non-surgical re-tx
(or even NSRCT for first time) can be done.
ALSO: Briggs & Scott (1997): meta-analysis |
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Success in Intentional Reimplantation: 1. Grossman (1982):
70% success at 5 yrs 2. Keller (1990): 91% success 3. Bender & Rossman (1993):
81% success ·
Koenig (1988): n=192
Keep out of socket<15min, do not touch root, keep it moist, minimal
splinting ·
Dumsha & Gutmann (Compendium 6/95): reviewed clinical
guidelines |
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Success with Separated instruments ·
Strindberg (1956): found 19% higher incidence of failure
with separated instruments ·
Crump & Natkin (1970): No difference in failure rates
with separated instruments. Location
of instrument is important ·
Tamse & Katz (1987 IEJ): Proposed using separated files
to obturate a canal. Consider this tx
only after all other techniques have been evaluated as impossible |
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Sjogren & Sundqvist 1997 IEJ |
Teeth with negative bacterial cultures prior to fill had
94% success rate whereas teeth with positive cultures had 68% success rate
(p<.05). Also demonstrated that
could not reliably obtain negative cultures after just one appt (only 40%
cases were non-cultivable for bugs).
In 3 of the failing cases, Actinomyces was found in the RC
systems. Study was on 55 root canals
with 5 yr follow-up. Most important
point: The success rate of NSRCT is 26% higher if the RC system is free of
bacteria at time of obturation. |
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Eriksen 1991 |
Prevalence of apical periodontitis increases with age. |
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Sundqvist 1976 |
CLASSIC: Apical periodontitis can only be detected in
teeth with bacteria present in canal systems. Necrotic, but sterile traumatized teeth have no signs of
PARL. In contrast, necrotic and infected
teeth showed PARLs. Also, probability
of pain increased with # bacterial
species (esp when >6); suggests bacterial synergism is important virulence
factor. |
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History and Rationale |
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Hudson 1862 |
Credited with performing some of the first NSRCT
(obturated with gold) in the US (editorial in Dental Cosmos) |
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Price 1901 |
Discussed use of radiography in performing NSRCT and
evaluating success-failure |
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Callahan 1914 |
Introduced a technique of filling root canals with a
rosin-gutta-percha material as well as theorize on proper filling needs of a
root canal. |
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Hatton 1922 |
He advocated confinement of instrumentation to the inside
of canal. He also determined histologically, that repair was possible at the
root apex |
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Blayney 1930 |
After his findings, the author offered the final
conclusions: 1.) degenerative processes around root ends do not always
indicate extraction, 2.) in many cases, repair promptly takes place after
treatment and stays healthy for years and 3.) root canal treatment will only
succeed when the practitioner is willing to adopt methods in accord with the
biologic forces involved. |
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Milas in: POP 1980 |
·
Harry B. Johnston - first endodontic practice was begun
in 1928. ·
1943 the AAE was formed in Chicago ·
1963 the ADA recognized endodontics as a special area of
dentistry.. ·
Karl Koller introduced cocaine in 1884 ·
Alfred Einhorn
introduced Novocaine in 1905 ·
Wilhelm Roentgen discovered x-rays and in 1896 the first
dental apparatus was built by Rollins ·
Hall patented (1847) gutta-percha as canal filling
material (was named "Hall's Stopping"). ·
Elmer Jasper in 1930 discussed the use of silver points. ·
The rubber dam was first used in 1862 and 20 years later
the first set of retainers were born ·
Bowman and Allen in 1873 developed the the rubber dam
forceps ·
Coolidge 1919 Introduced NaOCl to endodontics ·
Nygard-Ostby 1957 Introduced EDTA to Endodontics ·
Hermann 1920 - introduced Ca(OH)2 as intracanal
medicament for necrotic teeth |
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Rickert & Dixon 1931 |
Implanted materials and hollow needle in rabbits. The authors believed that when the tissue
of the pulp has been destroyed, it must be filled to the very end in order to
prevent “diffusion”. Therefore the filling material must come in contact with
the surrounding vital tissue. This filling
material must be tolerated by the tissue (biocompatible). Th authors
also concluded that hollow tubes were not tolerated by the body and therfore, a root canal can not be filled short
of the apex. = "hollow tube" theory - the idea that the body cannot
tolerate an underfilled canal.
DISPROVED BY: Torneck (1967) CLASSIC:
Disproved the hollow tube theroy with implanting sterile hollow
needles and demonstrating minimal tissue response |
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Focal Infection & Systemic Responses to Oral Infection |
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Newman 1996 |
To re-present the
idea that the human mouth is a focus of infection (originally proposed by
W.D. Miller in 1890) |
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Fish 1939 |
Zones of
Fish = early attempt to disprove focal infection theory ·
Zone of infection (innermost zone which is necrotic and
contains bacteria; center of abscess) ·
Zone of
contamination (cell destruction is evident; abscess wall; exudative) ·
Zone of irritation
(contains osteoclasts and histiocytes; granulomatous zone) ·
Zone of stimulation (encapsulation) Conclusion - Cotton wool + bugs implanted into guinea pig
mandibles 4-40 days. Infection
remained localized regardless of the duration or virulence of the organism. |
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Kawashima & Stashenko (1998 Immunnology |
Used P/E selectin knockout mice (P/E ko's lack rolling adhesion of PMNs and macrophages to endothelium): Saw significantly more PA bone destruction in ko's. Thus, phagocytic leukocytes (PMNs and/or macrophages) protect against bacterial induced PA bone destruction in mouse model of AP. |
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Darveau Infect
Immun 63:1311, 1995 |
Possible mech for oral bacteria (P. gingivalis) to
influence distant sites of infection: LPS (only from oral bugs)
down-regulates E-selectin expression in vascular endothelium. Get reduction in leukocyte diapedesis at
distant sites of infection. “E
selectin inhibition by bacterial LPS could explain the relative lack of
inflammation and pain associated with periodontal pockets and root canals
that harbor large numbers of bacteria” (quote from Bergman, below). Proposed that this is a possible mechanism
of focal infection. |
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Bergman, Trope
& Offenbacher 1999 JOE p747 |
Mouse model: Implanted two chambers sc in the R & L
flanks: one contained E. coli (model of enteric infection) and the other
contained either P. gingivalis (oral infection model) or Sham/Sham. Chronic administration of Pg delayed the
time for 50% rejection (ie, sloughing) of Ec chambers (25 vs 19 days). Importantly, the reverse was not true (ie,
Ec did not delay time for Pg rejection).
Thus, oral microorganisms may alter infection at distant sites. Possibly due to Darveau mechanism of E
selectin suppression. |
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Grau 1997 Stroke
28:1724 |
Epidemiologic study which demonstrates positive
correlation between endodontic infections and the incidence of stroke. “Raises new concerns regarding the role of
untreated periapical infection” |
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Nair in: Essential Endodontology |
The concept of focal infection is built around the
pathological effects of bacteremia.
However, the significance of this proposal is weakened by the observation that bacteremia is
found in healthy patients undergoing routine toothbrushing or
flossing without adverse effects [see also: Baumgartner '77; Hockett '77 Arch Oral Biol ]. |
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Root Canal Anatomy |
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Vertucci 1984 Other anatomical studies: Bellizzi 1983 / 85) |
Examined 2400 teeth.
24-60% of teeth have lateral canals (highest in 2nd premolars
and MB canals of max molars) Sudden narrowing of RC system on radiographic exam is
good indication of canal bifurcation MAXILLARY TEETH: 1st Premolar 62% Type IV (2 canals), 18% Type II (2-1 canals),
), [69% have 2 canals at apex) 2nd Premolar 48% Type I (1 canal), 22% Type II (2-1 canals), 11%
Type IV (2 canals) 1st Molar: MB 45% Type I (1 canal), 37% Type II (2-1 canals), [18% have 2 canals at apex) MANDIBULAR TEETH: Central 70% Type I (1 canal), 22% Type III (1-2-1
canals) Lateral 75% Type I (1 canal), 18% Type III (1-2-1
canals) Canine 78% Type I (1 canal) 1st Premolar 70% Type I (1 canal) 2nd Premolar 98% Type I (1 canal), 1st Molar: M 12% Type I (1 canal), 22% Type III (1-2-1 canals),
43% Type IV (2 canals) 1st Molar: Distal 70% Type I (1 canal), 15% Type II (2-1 canals), 8% Type V
(1-2 canals) |
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Rationale
for Instrumenting 0.5-1mm short of
the radiographic apex: Morphological Studies: ·
Kuttler (1955):
Examined apices of extracted teeth distance from DCJ to radiographic
apex 0.5mm (young pts) to 0.65mm (older pts). ·
Burch & Hulen (1972): found apical foramen 0.59 mm short of radiographic apex ·
Tamse & Littner (1988): apical foramen was positioned
0.8mm from the tip of the root ·
Stein & Corcoran (1990): found apical foramen 0.72 mm short of radiographic apex
and width of CDJ = 0.19mm ·
BUT- Gani & Visvisian (1999 JOE): studied apical
canal diameter in max 1st molars.
At 2mm from apex, palatal systems are 60% circular and 30% ovoid
regardless of age. At 2mm from apex,
MB systems are 50-60% flat (ie, ribbon, tear-shaped) and 30% ovoid (no clear
cut age effect). . Interestingly, DB
systems 30-60 circular. Problem is that if C&S in flat canal system for
the long dimension, could perf in narrow dimension during instrumentation Pulp – PA Pathology Studies: ·
Malueg , Wilcox & Johnson (1996): SEM of teeth with varying external apical root
resorption (n= 40). Apical
resorption: pulpal necrosis > normal pulp, reversible pulpitis, or
irreversible pulpitis. Teeth with periapical lesions had significantly more
apical resorption than those without radiographically evident periapical
lesions. Therefore, the status of the
pulp and periapical tissues should be considered when determining length for
preparation and obturation. ·
Frank (1990) Also reported this finding (ie, necrotic
teeth tend show more apical resorption).
·
Trope &
Chivian (1994) propose that CDJ at foramen is very thin (in some cases,
absent) – exposing mineralized dentin to the resorptive clastic cells. Outcome Studies: ·
Sjogren (1990): Outcomes study: Best success for tx necrotic cases with apical periodontitis
are when the obturation ends within 0-2 mm of radiographic apex (= 94%);
underfills are less successful (68% when filled > 2mm from apex) and
overfills are less successful (76%). ·
Davis & Joseph (1971): Classic! Teeth that were fully instrumented, but filled short of
the radiographic apex had best healing.
ALSO: Seltzer & Bender 1963 &67 (human and monkey study with
healing eval at 3 months; overfill = persistent inflammation) ·
Ricucci (1998 IEJ): Review article and 100 case report
series. Conclude that best results is
to obturate at apical constriction which ranges 0.5-2mm short of radiographic
apex. |
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Mandibular
Incisors ·
Benjamin & Dowson (1974): This radiographic study
places the incidence of 2 canals in mandibular incisors at 41%, generally
merging in the apical area. This
value is higher than Vertucci's study (= 18-22%). ·
Vertuci (1984): 70-75% 1 canal and 18-22% 2 canals ·
Mauger, Schindler & Walker (1998): Determine the
prevalence of two canals and an isthmus in mandibular incisors. An isthmus
was present in 20% of the teeth at the 1mm level, 30% at 2mm, and 55% at 3mm.
The width measurements indicate that a final apical prep size should > #35
file to debride most mand incisors. An isthmus may make it difficult to
debride with rotary instruments alone without the risk of perforation proximally.
Note that Benjamin & Dowson
(1974) reported 41% incidence of 2 canals, but they used 2 files and
did not section to look for isthmuses. ·
Miyashita (1997) evaluated 1,085 mand incisors and
recommended #40 MAF. 85% single
canals with 99% foramina within 1mm. |
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Mandibular
Molars ·
Cooke & Cox (1979): Mandibular 2nd & 3rd
molars can have "C" shape 8% of the time. MB joins D canal; can be difficult to debride and shape. ·
Skidmore & Bjorndal (1971): When the mesial root of
mand 1st molars contain 2 canals, they are 40% Weine type II (2
canals, 1 foramina) and 60% Weine type III (2 canals 2 foramina). When the
distal root contains 2 canals (29% of the total) they can be classified as
Weine type II 60% and Weine type III 40% of the time. ·
Vertucci (1984): 1st Molar: M 12% Type I (1 canal), 22% Type
III (1-2-1 canals), 43% Type IV (2 canals) ·
Vertucci (1984): 1st Molar: Distal 70% Type I (1 canal), 15% Type II
(2-1 canals), 8% Type V (1-2 canals) ·
Reeh (1998 JOE): Reports 7 canal mand first molar
MB1&2, ML1&2, DB, D, DL. Used
Ca(OH)2 sealer for D canals due to large apical openings to reduce chance of
sealer extrusion due to rapid setting time…… |
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Maxillary
Premolars ·
Carns & Skidmore (1973): Most important point: 85%
max 1st premolars have 2 canals.
Max first premolars showed five different morphologic categories of
combinations of roots, canals, and foramina: (%); 2,2,2 (57%); 1,2,2 (15%); 1,2,1 (13%); 1,1,1 (9%); and 3,3,3 (6%). Remember to look for wider M-D width at
CEJ as a predictor of a 3 canal premolar. ·
Vertucci (1984): Max 1st Premolar: 69% have 2
canals at apex (Bellizzi (1985): 90%
have 2 canals ·
Vertucci (1984): Max 2nd Premolar: 82% have 1 canal at
apex (Bellizzi (1985): 59% have 2
canals! |
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Maxillary
Molars ·
Kulild & Peters (1990): Max Molars: the incidence of
2nd canals in MB roots of 1st and 2nd molars is ~ 95% and this 2nd
canal originates 1.82mm lingual to the MB canal. ·
Gilles , Reader (1990): Found 90% Max 1st
molars have MB2 and 70% max 2nd molars. ML canals exit the root an average of 2mm short of the
anatomic apex in first molars and 1.45mm in second molars. ·
Fogel and Peikoff
(1994): Examined 208 Max 1st molars MB root: 29% Type I (1 canal),
39% Type II (2-1 canals), 31% Type III (1-2-1 canals). THERFORE 71% OF MAX 1ST MOLARS
HAVE TREATABLE MB2! This value splits
the difference between Weine (50%
incidence of MB2; CLASSIC: 1969 study) and Kulid & Peters (95% when sectioned tooth; 1990 study) ·
Bone & Moule (1986): This study shows that the
palatal root of the maxillary molar should always be assumed to curve. 85% of
examined palatal roots displayed curvature > 10°. We need to bear this in mind when
performing root canal therapy and when creating post space. |
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Hartwell &
Bellizzi 1982 |
In vivo incidence of 4 canal cases (assessed by
post-obturation film) is much lower than in vitro anatomical studies. For example, max 1st molar,
only 18% had 4 canal systems obturated. |
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Stropko (1999 JOE) |
Confirmed Hartwell & Bellizzi in cases series report:
increasing #s MB2 was found with microscopic exam. Also: 1) make access more
rhomboid, infringed MMR to access mesially inclined MB2. To test for MB1-MB2
communication, place paper point in MB2 and watch fluid level in MB1. Usually found MB2 mesial to line
connecting MB1 to palatal canal |
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Pineda & Kuttler 1972 |
Examined 7,275 root canals; 85% of root canal curvatures
are found in the apical third of the root.
Foramina of the main root canal were located on one side of the apical
vertex 83% of the cases sometimes to a distance of 2-3 mm. Proves can't see curves on the radiograph. |
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Chohayeb 1983 |
This investigation demonstrates that the maxillary
lateral incisors have a high tendency to dilacerate distolabially (52%) , and
this could be related to the incidence of failure. |
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Wilcox & Walton 1989 |
When cutting access in crowned tooth, remember that pulp
chamber is in center of crown |
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Leeb 1983 |
Remove cervical ledges over canal orifice during access
prep to enhance straight-line access |
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Lowman, Burke, Pelleu 1973 |
The purpose of this study was to determine,
radiographically, the incidence of patent accessory canals in the coronal and
middle thirds of the roots of molars.
From this study, 59% of all the teeth had accessory canals (55% max
and 63% man), therefore, one should not assume all furcal lesions are of
periodontal etiology. Confirmed by
Burch (1974) who reported that 76% of all molars have accessory canals in the
furcation area |
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Trope &
Elfenbein 1986 |
Pts of African-American descent have 3X > incidence of
2 canals / 2 roots in mand premolars |
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Dental Anomalies |
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Sabala , Benenati , Neas 1994 |
This study determined the relative incidence of bilateral
morphological aberrations (bifurcation, C-shaped, fused roots). Of the 221
unusual or aberrant situations, 60.2% were bilateral. Aberrations occurring
less than 1% of the time were 90% bilateral.
If dental abberations are present, valuable information may be
acquired through the evaluation of the contralateral tooth. |
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De Smit , Jansen & Demaut 1984 |
The results support the hypothesis that morphogenesis of
invaginated teeth occurs as an active apically directed proliferation of
ameloblasts or as a local growth retardation of the inner enamel epithelium.
Although only one case was seen to have a possible connection between the
pulp and the invagination, after eruption this area of dens invagination may
become a “weak spot where bacterial invasion” could occur. |
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Hulsmann 1997 IEJ |
Review: Dens invaginitus due to infolding dental papilla
during development. MOA unknown, but
could include growth pressure of the arch buckling enamel organ, infection,
trauma, fusion of two tooth germs.
Clinically seen as deep infolding of enamel and dentin may extend deep
into the root. Hallet (1953) proposed
classification: Type I enamel-lined minor form; Type II enamel lined form
that invade root but is still blind sac; Type III invades root and has 2nd
foramen (opening). 1° max laterals;
often “peg-shaped” & bilateral.
Frequently results in pulp necrosis.
NSRCT difficult due to complex anatomy. First described by Ploquet 1794 in a whale’s tooth. Tx: Sealants applied to fissure, NSRCT
described by Hovland 1977; C&S difficult (consider Ca(OH)2, US files,
thermoplasticized GP). |
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Froner 1999 EDT |
Case report: Dens invaginitus (Dens in dente) Type III
max lateral. Combined NSRCT (of main
canal) and endo sx (retro-fill with GP-Roths) with good 3yr followup |
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Turell & Zmener 1999 |
Described NSRCT in fused mand molar |
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Rotstein, Stabholz, Heling, Freidman 1987 |
Two categories for case selection of dens invaginitus:
Category A – no pathosis, treated by prophylactic measures including sealing
with composite. Category B – pathosis present, requiring pulpal therapeutic
intervention. Clinical considerations include function and esthetics of
invaginated teeth and complications associated with root canal therapy.
Direct access may be difficult and may result in perforations. If this is the
case, surgical therapy may be the treatment of choice. |
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Senia Regezi 1974 Also: Yip. 1974 |
Dens evaginatus is a coronal anomaly of premolar teeth
with a reported incidence of 1-2%. It is rare in this country and affects
mainly people of Mongoloid ancestry. It is composed of enamel and dentin,
with a pulpal extension into it that may be detected radiographically. In
this case a 32 year old Filipino woman was diagnosed with bilateral dens
evaginatus with associated periapical involvement secondary to pulpal
necrosis. Early recognition with
appropriate therapy can prevent loss of these otherwise normal teeth. Apexogenesis should be the initial
goal, followed by root canal therapy later if necessary |
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Mellor , Ripa 1970 |
A talon cusp is characterized by a cusp-like projection
arising from the cingulum area of a maxillary or mandibular incisor. Normal
radiographic tooth structure, enamel, dentin and pulp tissue. At the junction
of the cusp and the lingual surface of the incisor, there is a developmental
groove, which creates a large niche to harbor bacteria. Recommended that
prophylactic restorations be placed in these cases |
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Cooke , Cox 1979 |
C-shaped canal configuration. Radiograph showed two-roots
close together with one canal in each root. Upon access a normal pulp chamber
with two canals centered in the buccolingual direction was found. Cleaning
and shaping. A finding in all 3 cases was persistent hemorrhage and pain on
instrumentation. They believe that C-shapes are impossible to dx from
radiograph. Primarily mand 2nd
molars, although Bolger and Schindler 1988 have reported C-shape mand 1st
molar. Also: Yang & Yang (1988)
reported that Chinese have 4.9% incidence of "C" shaped canals in
max molars. |
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Canal Preparation: Access, Isolation, Instrumentation |
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Rationale
for Instrumenting 0.5-1mm short of
the radiographic apex: Morphological Studies: 1. Kuttler (1955): 0.50 mm (young) to 0.65mm (old) 2. Burch & Hulen (1972): 0.59 mm 3. Stein & Corcoran (1990): 0.72 mm width
of CDJ = 0.19mm 4. Tamse & Littner (1988): 0.80 mm ·
BUT- Gani & Visvisian (1999 JOE): studied apical
canal diameter in max 1st molars.
At 2mm from apex, palatal systems are 60% circular and 30% ovoid
regardless of age. At 2mm from apex,
MB systems are 50-60% flat (ie, ribbon, tear-shaped) and 30% ovoid (no clear
cut age effect). . Interestingly, DB
systems 30-60 circular. Problem is that if C&S in flat canal system for
the long dimension, could perf in narrow dimension. Pulp – PA Pathology Studies: ·
Malueg , Wilcox & Johnson (1996): SEM of teeth with varying external apical root
resorption (n= 40. Apical resorption:
pulpal necrosis > normal pulp, reversible pulpitis, or irreversible
pulpitis. Teeth with periapical lesions had significantly more apical
resorption than those without radiographically evident periapical
lesions. Therefore, the status of the
pulp and periapical tissues should be considered when determining length for
preparation and obturation. ·
Frank (1990) Also reported this finding (ie, necrotic
teeth tend show more apical resorption).
·
Trope & Chivian
(1994) propose that CDJ at foramen is very thin (in some cases, absent) –
exposing mineralized dentin to the resorptive clastic cells. Outcome Studies: ·
Sjogren (1990): Outcomes study: Best success for tx necrotic cases with apical periodontitis are
when the obturation ends within 0-2 mm of radiographic apex (= 94%);
underfills are less successful (68% when filled > 2mm from apex) and
overfills are less successful (76%). ·
Ricucci (1998 IEJ): Review article and 100 case report
series. Conclude that best result is
to obturate at apical constriction which ranges 0.5-2mm short of radiographic
apex. |
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Lovdahl & Gutmann 1980 |
Described gingivectomy (prefers scalpel over electrosurg)
with reverse bevel for isolation indication: Dentin margin needs to be 3mm
above crestal bone to give space for 1-2mm sulcus depth; want to preserve 4mm
zone of attached gingiva |
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Bramwell & Hicks 1986 |
Described use of oraseal or Cavit to seal leaky RD |
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Calcified
Canals Gutmann Stamos Leeb Schindler |
Calcified
Canals ·
Wilcox & Walton (1989): Pulp chamber is in center of
crown ·
Gutmann: Use long shanked #2 round; check orifices with
sharp DG-16 endo explored. Initial
stem-winding motion with #8 Pathfinder CS (Kerr) since it has a stiff shank
(MUCH better than NiTi) ·
Leeb (1983) Remove cervical ledge near orifice ·
RC Prep (Premier Dent Products) ·
Stamos (1985) Rec use of US files to gain access and file
calcified canals; and to remove alloy or particles packing RC system ·
Schindler (1988): If cannot bypass calcification, then
C&S & obturate to level of calcifiction; place on recall for
potential Sx ·
Glyoxide = 10% carbamide peroxide in glycerol; Marion
Labs ·
Flexofiles are available in 1/2 steps ("Flexofile
Golden Mediums"; LD Caulk) ·
Weine (1970): Rec customize files by cutting 1mm from #10
to make #12 (However- cutting end vs pilot tip, etc) ·
EndoZ bur - safe ended carbide bur to enlarge access (LD
Caulk) ·
Ngai (1986): Described use of US files to bypass
separated instruments in canals ·
Weine (1975): Described zipping = elliptication = transportation
of apical portion of the canal (eg., straightening a curved canal). The apical foramen becomes tear-dropped
shaped due to excessive cutting of the outer portion of curved canal at file
tip and inner portion of curved canal at more coronal portion of the
file. Consider obturation with warm
thermoplasticized GP to fill this unevenly prepared canal system. Use Sealapex in these cases (since
contains Ca(OH)2; Kerr). |
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Pliet & Sorm 1973 |
Triangular instruments cut more
efficiently than square files |
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Powell, Simon and Maze 1986 |
A comparison of the effect of modified and nonmodified
instrument tips on apical canal configuration, J
Endod , 1986;12:293-300 |
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Walia, Brantley, Gerstein 1988 |
1st description of NiTi (“nitinol”) files |
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Wildey , Senia 1989 |
1st description of Canal Master |
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Profile: .02, .04, .06 mm taper. ISO sizes or Series 29: (Constant 29%
increase in file size giving 13, 17, 22, 28, 36, 47, 60, 77, 100 sizes) |
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Ingle 1961 |
Ingle JI, A standardized endodontic technique utilizing
newly designed instruments and filling materials, Oral Surg Oral Med Oral
Pathol , 1961;14:83-91 |
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Short & Baumgartner 1997 |
Lightspeed and Profile were faster than hand filing and
kept files centered in canal better that ss hand files |
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Pruett, Clement, Carnes 1997 |
Cyclic fatigue testing of nickel-titanium endodontic
instruments. NiTi instruments
fracture within their elastic limit and without any signs of previous
permanent distortion. Rotation
subjects NiTi to both tensile and compressive forces in the area of the canal
curvature; this produces a very destructive form of loading. |
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Dederick & Zakarriasen 1986 |
Axial movement during
instrumentation may distribute stresses along the shaft and reduce risk of
fracture. (Cite this along with the
Pruett study on cyclic fatigue). |
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Love 1996 |
Bacteria can invade up to
150-250 um into dentinal tubules.
Confirmed by Sen (1995): bugs grow 150um into tubules. Thus, Yared & Bou Dagher
1994 advocate apical preparation to 0.3-0.5 mm larger than original size (and
width of CDJ is often 0.19mm (Stein & Corcoran 1990). |
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Klevant 1983 IEJ ** |
Chemomechanically debrided RC
systems of 86 human teeth and left un-obturated for 2 years. Radiographic exam showed significant
decrease in PARLs in C&S-unobturated and C&S-obturated teeth. Thus, reject “hollow tube” theory for
breakdown of tissue fluid inducing PA lesion. (Should point out that even though C&S produced significant
radiographic healing of AP, better healing was observed in C&S-obturated
group. Also reported by Donnely 199,
Weine, and others (see Klevant for refs) |
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Jahde & Himel 1987 |
A small amount of inflammation
and localized bone necrosis occurs with file overextension . |
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File cutting tips are
responsible for ledges, zips and perforations (ie, the tip is an effective
cutting region). This is consistent
with study by Powell & Simon (1988) who showed that Flex-R produced less
transportation regardless if used balanced-force or stepback |
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Roane & Sabala 1984 |
A CW rotation of a file has greater
chance of separation than a CCW rotation.
Confirmed by Seto &
Harrington 1988 |
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Apex Locators ·
Suzuki (1942) reported that PDL and oral mucosa have a
constant electrical resistance of ~6.5 kOhms ·
Sunada (1962): Classic! Applied Suzuki’s idea to develop
an apex locators ·
Old style = resistance (ex: NeoSono, Formatron) ·
Next generation = dual frequency (ex: Root ZX, Endex) ·
Pagavino (1998): Root ZX has 83% accuracy ± 0.5mm
(includes teeth with lateral foramina) ·
Dunlap & Rauschenberger (1997 JOE): Root ZX used in
teeth scheduled for extraction; cemented files and verified position. 82.3% accurate to 0.5mm of apical
constriction. Mean distance from
apical constriction was 0.21mm in vital cases and 0.49mm in necrotic cases
(NS difference). ·
Fouad (1993): Apex locaters ok on pts with a pacemaker
(even though Root ZX manual says not to use it on pts with pacemakers) ·
Beach & Hutter (1996): Case report of using apex
locator on a pt with a pacemaker ·
Fuss (1996): Describes use of Apex Locators to locate
perforations ·
Ibarrola (1999 JOE): Preflaring canals permits WL files
to reach apical foramen more consistantly with Root ZX. |
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Ahmad 1987 |
Most of the benefits of
ultrasonics are due to acoustic streaming rather than cavitation. |
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Huque & Iwaku 1998 IEJ |
Ultrasonics with 5.5% NaOCl is effective in eradicating
bacteria from infected dentin (artifical smear layer infected with
Actinomyces, Fusobacterium, Streptococcus) |
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Haikel 1998 JOE |
NiTi – 2 phases: Austenite (= manufactured state) and
Martensite. The ability to cycle between these two states is due to NiTi
having properties of superelasticity and shape memory. Phase transition occurs with rapid stress
on file (therefore, use at a constant speed). Files are weakest during phase transition and have highest probability
of fx at this time |
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Haikel 1999 JOE |
In vitro study with tempered steel canals: As radius of
curvature decreased, fracture time decreased. Taper of files was also significant in determining fracture
time (increased diameter = decreased time).
ie, 06 taper will fracture sooner than 02 taper… |
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Walton 1976 |
Tapering preparation permits better debridement of apical
preparation, reduces over-instrumentation of the foramen and improves ability
to obturate |
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Abou-Rass, Frank & Glick |
Classic: describes
anticurvature filing. Defined danger
and safety zones |
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Gambi & DelRio 1995 |
NiTi files may fxn best when
used in reaming or rotary fashion (since less transportation and canal
deviation) |
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Weine & Kelly 1975 |
Termed "apical zip",
discussed elbow, teardrop apex and hourglass shape. Argued against reaming (before NiTi). |
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Mullaney DCNA 1979: |
Step-back (Telescopic Technique) ·
Determine WL & develop apical stop to #25 ·
Step-back by shortening 30, 35, 40 in 0.5 or 1 or 2mm
increments ·
Recapitulate with #25 ·
Coronal flare with #2 & 3 Gates-Glidden |
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Goerig JOE 1982 |
Step-Down technique. ·
Passively use #15, 20, 25 Hedstrom in coronal 2/3 of
canal system; irrigate ·
Coronal flare with #2 & 3 Gates-Glidden ·
Establish WL and prepare apical seat with stnd serial
filing ·
Step-back to blend apical and coronal segments ·
Recapitulate The crown-down pressureless technique (Morgan
& Montgomery JOE 1984) is similar to the Step Down: Rotate straight file
twice from larger to smaller sequence until reach 16mm. Coronal flare with
GG. Establish provisional WL 3mm
short of apex. Rotate straight file
twice at WL. Finish apical prep at WL
with file 2 sizes larger than first file to reach WL |
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Roane & Sabala 1985 JOE |
Balanced force technique (use FlexR files (Moyco Union Broach) or Flexofile for
non-cutting pilot tips of triangular file) ·
Use Crown-Down to establish radicular access ·
Rotate straight file CW from 90-180° with light apical
pressure to engage dentin ·
Shear dentin by 120° CCW rotation with apical force,
flexing it to conform to canal curvature ·
Continue until get adequate apical enlargement at WL ·
Inspect files frequently; do not go beyond #35 in curved
canals |
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Fava 1983 JOE |
Double-flared technique. ·
Passively use larger-smaller files in coronal 2/3 of
canal system; irrigate ·
Establish WL with small K file. Serial file to prepare apical stop and then step back to blend with coronal step-down
flare ·
Circumferentially file with master K file |
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Torabinejad 1994 OOO |
Passive step-back technique: ·
Establish canal patency with small K file at WL then
passively instrument with larger K files ·
Coronal flare with #2, 3 and possibly #4 GG in coronal
1/3 ·
Confirm WL (since coronal flare and removal of curvatures
often reduces WL) ·
Increase straight line access with careful re-work with
GG ·
Serial file to prepare apical stop and then step back to blend with coronal step-down
flare |
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Wilcox and Walton 1989 |
Studied access of molars: DB
orifice is slightly distal to buccal groove.
Rec start access prep centrally, and not at MMR. |
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Instrumentation
and Removal of Bugs Bystrom -Sundqvist '81 Dalton & Trope '98 Siquerra '99 |
Instrumentation
and Removal of Bacteria ·
Bystrom & Sundqvist (1981): One steps do not remove
bacteria in necrotic cases. Ca(OH)2
is the best inter-appt medicament to kill residual bacteria. Simple mechanical debridement with saline
is insufficient to remove all bacteria (although it does reduce bugs by
100-1,000 fold). ·
Dalton and Trope
(1998 JOE): n=48 MB canals of mand necrotic molars with apical periodontitis
(AP defined as PARL) were found to be uniformally infected [96% of teeth with
AP had CFUs in MB canals; similar to 95% of Sundqvist (1976) and 96% of
Orstavik (1991)]. NiTi rotary
(Profile) = SS files (step-back) for reducing CFU (saline irrigation). Saw progressive decrease in CFUs with
progressive sampling during filing with larger files, regardless of NiTi or
SS. Suggests that tx approach to
infected teeth with AP may require additional antimicrobial measures than
just instrumentation, irrigation and aseptic technique (ie, inter-appt
Ca(OH)2). ·
Siqueira (1999): Infected 35 mand premolars with E.
faecalis; NiTi rotary & saline irrigation: (Profile 06, GT) reduced
94-99% bugs; Larger file sizes had
greater reduction of bugs (but only looked up to #40) |
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Intracanal Irrigants and Medicaments
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Infected Dentinal Tubules Orstavik '90 Estrella '99 |
Infected Dentinal Tubules ·
Perez (1993): Strep sanguis grew 479um into dentinal
tubules by 28 days ·
Orstavik (1990 EDT): E. faecalis & Strep sanguis grew
300-400um into slabs of bovine dentinal tublues after 14-21 days. Presence of a smear layer delayed, but did
not prevent, antimicrobial effects of medications. ·
Sen (1995): bugs grow upto 150um into tubules ·
Love (1996): bugs grow 150-250um into dentinal tubules ·
Estrella (1999 JOE): Ca(OH)2 demonstrated NO
antimicrobial effect at 2, 3, & 7 days against E. faecalis, S. aureus in
infected dentinal tublues (suggests antimicrobial effectiveness is due to
concentration of [OH] and time of exposure) ·
Thus, Yared & Bou Dagher 1994 advocate apical
preparation to 0.3-0.5 mm larger than original size (and width of CDJ is
often 0.19mm (Stein & Corcoran 1990).
However, remember Gani (1999 JOE) report on canal shape (ribbon ) and
instrumentation |
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NaOCl Bystrom '85 D'Arcangelo '99 Cunningham '80 Ellerbruch '77 |
NaOCl ·
Hand & Smith (1978): 5.25% NaOCl has superior tissue
dissolving properties. ·
Harrison & Hand: diluting NaOCl can reduce
antimicrobial effectiveness ·
Bystrom & Sundqvist (1985): Antimicrobial
effectiveness of 0.5% NaOCl = 5% NaOCl.
15% EDTA enhanced the effectiveness. ·
D'Arcangelo (1999): 0.5% = 1% = 2.5% = 5% NaOCl for
antimicrobial effectiveness (11 strains inc E. faecalis; in fac
aerobes-anerobes, microaerophiles, obligate anerobes). IMPORTANT POINT: Best when use at least 10
min contact time ·
Ellerbruch & Murphy (1977 JOE): Vapors of 5.25% NaOCl
have strong antimicrobial activity ·
Cunningham &
Joseph (1980): 2.6% NaOCl is more effective in antimicrobial action at 37C. ·
Senia & Marraro (1975): GP cones sterilized at
chair-side by 1 min immersion in 5.25% NaOCl. Also reported by Frank & Pelleu 1983. ·
Siqueira (1998 EDT): 5% NaOCl destroyed Bacillus subtilis
spores from GP cones within 1 min of immersion |
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NaOCL Accidents Reeh & Messer ‘89 Gatot ’91 Becker & Cohen ‘74 |
NaOCL Accidents ·
Reeh & Messer (1989 EDT): long term paresthesia
(still present at 15months) after injection 1% NaOCL thru buccal perf of a
maxillary incisor ·
Gatot (1991 JOE):
long term paresthesia can occur with NaOCL injection ·
Becker & Cohen (1974 OOO ): NaOCl injected beyond
apex = PAIN! Tx with steroids iv and
continue for 3 days ·
Recommendations for tx (from Gluskin, POP): long acting
LA, Amox X 5 days, analgesic, Steroid, cold compresses, |
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EDTA & NaOCl Baumgartner '87 Yamada '83 Margelos '97 |
EDTA & NaOCl ·
EDTA removes smear layer, but does not remove organic
debris: Baumgartner 1987; Garbergolio 1994 ·
NaOCL is antibacterial and removes organic debris, but
does not remove smear layer: Shih 1970; Senia 1971; Baumgartner 1987 ·
Alternating EDTA and NaOCL effectively removes smear
layer, tissue, predentin and increases antimicrobial activity: Baumgartner
1987; Goldman 1982; Bystrom 1985; Tatsuta & Baumgartner 1999 ·
Yamada (1983 JOE): The most effective way to remove
organic and inorganic components of smear layer is 10ml 17% EDTA and then
10ml 5.25% NaOCl ·
Calt (1999 JOE): Use both EDTA & NaOCl to maximally
remove Ca(OH)2 dressing from canal system ·
Patterson (1963): EDTA is self-limiting in its action ·
Margelos (1997 JOE): Ca(OH)2 left in canals can accelerate
setting of Roths. FTIR spectroscropy
indicates that Ca evokes rapid sealer setting into a brittle and granular
material with free eugenol in the set product. EDTA was best agent to remove RC systems tx with Ca(OH)2
medicament |
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Smear
Layer: ElDeeb '83 Evans & Simon '86 Jeansonne '97 Glickman '95 |
Smear
Layer: ·
Ishley & ElDeeb (1983) Sealer was more important that
the type of obturation used (McSpadeen vs lateral condensation ) ·
Evans & Simon (1986): Presence or absence of smear
layer does not affect microleakage (dye leakage study eval both lateral
condensaton of GP and Obtura system).
The use of sealer is much more important in controlling leakage! ·
Madison & Krell (1984): Presence or absence of smear
layer does not make difference in leakage ·
Takeda (1998): Er-YAG laser can remove smear layer ·
Foster (1993) Removal of smear layers facilitates
diffusion of Ca(OH)2 to kill bacteria (Bystrom: OH moiety is bactercidal) ·
Gutmann (1993) Showed enchanced adaptation of
thermoplasticized GP into dentinal tubules without smear layer ·
Taylor & Jeansonne
(1997): Coronal leakage cumulatively reduced by removal of smear layer, use
of AH26 and vertical compaction.
Confirmed by Economides (1999) who showed that microleakage in AH26
was reduced by removal of smear layer (but- that removal did not improve
sealing ability Roths 801). ALSO by Glickman (1995 IEJ): SEM AH26 &
LC ± smear layer ·
Craig & Harrison (1993): Citric acid (50% X 2 min;
pH=1) tx of resected root ends removes smear layer, exposes collagen and
enhances cementogenesis |
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Irrigation and Needle Size / Location ·
Ram (1977 OOO): Effective irrigation requires apical
preparation. Rec prep size of #40 to
get effective delivery of irrigants ·
Salzgeber & Brilliant (1977): Irrigant reaches apex
when canal systems are opened to file size 30 ·
Abou-Rass (1982): The closer the needle is to the apex,
the better the irrigation (ie, needle does not irrigate much past the bevel
tip) |
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Ca(OH)2 Bystrom '81-85 Sjogren '91 Safavi ‘93 Trope '97 Messer '93 Fava '99 |
Ca(OH)2 Properties: ·
Bystrom & Sundqvist (1981; 1985): is antimicrobial ·
Sjogren (1991): Ca(OH)2 applied for 7 days eliminated
bacteria in canal systems - even up to 5 weeks later (Bystrom 1985 looked at
one month of tx). 0.17% dissolves to
form Ca++ and OH, requires at least 1
day to exert full effect ·
Safavi & Nichols (1993): Ca(OH)2 inactivates LPS in
vitro Also reported by: Barthel
& Trope 1997 (IEJ) ·
McCormick (1983) Osteoclastic cells (osteoclasts &
PMNs) prefer acidity. The high pH of
Ca(OH)2 antagonizes their action ·
Foster (1993) Removal of smear layers facilitates
diffusion of Ca(OH)2 to kill bacteria (Bystrom: OH moiety is bactercidal) ·
Segura (1997) Ca(OH)2 inhibits macrophage adherance (may
contribute to Ca(OH)2 inhibition of resorption) ·
Estrela (1995): antimicrobial action due to OH- ·
Sigurdsson (1992) Lentulo spiral is most effective
technique of carrying Ca(OH)2 to working length ·
Nerwich & Messer (1993): Evaluated dentinal pH after
Ca(OH)2 dressing. Inner dentin pH
rapidly increases by OH diffusion (peaks 1 day), but takes 2-3 weeks to peak
in outer dentin. Peak pH ~9-10 with
cervical dentin peaking before apical dentin. ·
Hasselgren, Olsson & Cvek (1988): Ca(OH)2 completely
dissolves porcine muscle over time.
Ca(OH)2 plus NaOCl QUICKLY dissolves muscle. May be clinically significant when use Ca(OH)2 as intracanal
medicament and then rinse out with NaOCl.
(not seen over 30min period by Morgan and Carnes 1991). To confirm Morgan & Carnes, Yang,
Rivera, Walton (1996) showed that inter-appt NaOCl + Ca(OH)2 does not enhance
debridement. ·
Fava & Saunders (1999 IEJ): Reviewed Ca(OH)2 paste
formulations and indications. Vehicle
(aqeous, viscous, oily) plays important role in dissolution kinetics. Eg., Calisept is 56% Ca(OH)2 ·
Available in single dosage formations: Centrix syringe
tips (= SteriCal®) |
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Chlorhexidine Jeansonne '94 Torabinejad '93 Heline '98 Martin '87 Lindskog '98 Leonardo '99 |
Chlorhexidine ·
Jeansonne &
White (1994): Antimicrobial properties of 2.0% chlorhexidine gluconate = 5.25% NaOCl. ·
Ohara & Torabinejad (1993 EDT). Chlorhexidine effective antimicrobial
against 6 strains of anerobes. ·
Heline (1998 IEJ): Chlorhexidine is effective in dentin
infected with E. faecalis (ie chlorhex = NaOCl) ·
Martin & Nind (Br Dent J 1987): Chlorhexidine gluconate
can be irrigated into apicoectomy sites to reduce flora 94% immediately and
78% even after 10 days! ? Effect on
hemostasis & healing? If ok,
something to consider for immunocompromised pts? ·
White (1997 JOE): Intracanal chlorhexidine stills shows
substantivity. ·
Lindskog & Blomlof (1998 EDT): Monkey study: Infected
pulps, extract, scrape cementum.
Intracanal application of chlorhexidine (10% soln for 4w)
significantly reduced inflammatory resorption vs controls. ·
Leonardo &Ito (1999): 2% chlrohexidine has good
antimicrobial activity. Cultured RC
systems (n=22 necrotic with AP) with 2%C as irrigant. Saw immediate reduction of bugs in canals
with residual effects in RC system up to 48hr after tx. |
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Perez & Cardenas 1989 |
EDTA is self-limiting since its
efficiency is reduced during chelation.
Clinically, this means that should replace EDTA during chelation and
that inter-appt EDTA is efficient for only short period of time |
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Messer 1984 |
CMCP loses about 90% of its
effectiveness (active agent = parachlorophenol) in first 24hr. Moreover, CMCP
clears bacteria from only 67% of RC systems, compared to 97% clearance by 1
month tx with Ca(OH)2 (Bystrom
1985). Thus, CMCP is not useful as
intracanal medicament. |
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Hoshino 1996 |
Evaluated mixture of
ciprofloxacin, metronidazole and minocycline to kill bacteria in infected
human dentin, periapical lesions and infected pulps under strict anerobe
conditions. None of the agents killed
100% when given alone; but the combo was 100% effective. Proposed as possible intracanal
disinfectant. Also seen by Sato
(1992) in infected RC systems. |
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Max Goodson & Stashenko
1999 JOE p722 |
Evaluated clindamycin
impregnated fibers as intracanal medicament.
A 10mm fiber was effective in vitro against 12 organisms for 4
days. Zone of inhibition ranged from
10-100mm. |
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Obturation: |
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Over-Fill = 3D obturation with some GP beyond apex Over-extension: Excess GP beyond apical forman, BUT- no implication of a 3D obturation |
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Allard & Stromberg 1987 |
Dog study: In microbiologically-induced PA lesions, got 4
month healing even when obturate with bacteria remaining in canal
systems. Thus, can get healing even
when canals are still infected.
HOWEVER - Contrast with Sjogren 1997 who showed in humans that
prognosis is reduced if bacteria are present at time of obturation. |
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Spreaders ·
Allison & Walton (1981): Less leakage occurs if the
spreader reaches within 1mm of the apex.
Tugback of the master cone is NOT a good predictor ·
Hartwell &
Barbieri (1991): Found wide variations among finger spreaders and accessory
GP cones. If one doesn't fit - grab
another accessory cone. ·
Dang & Walton (1989): The hand spreader (D11) cased
more root distortion and vertical fx then the B finger spreaders. Root fx may be delayed after
obturation. Confirmed by
Lertchirakarn & Messer (1999). ·
Joyce & West (1998): NiTi spreaders produces less
stress during obturation than SS spreaders (NiTi distributed stress over
larger area). May imply less risk of
vertical root fracture during obturation. ·
Berry & Runyan: NiTi spreaders penetrate curved
canals to significantly greater depth than SS spreaders ·
Speier & Glickman
(1996): Rec use of NiTi finger spreaders in apical compaction and SS
spreaders for coronal 2/3 (to minimize buckling of NiTi spreaders) |
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If use hand spreaders: D11T = normal cases D11T2 = small apical prep (max
MAF = 25-35) GP3 = long canals (>23mm;
HuFriedy) |
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GP Properties: ·
Alpha phase is natural form (= 1,4-polyisoprene = dried
juice of the thebaine tree), introduced by Jose D’Almeida, phase transition
to beta phase at ~47C. Examples include Thermafil, Successfil, Alpha Phase,
Ultrafil ·
Crystalline forms are alpha (slow cooling, natural) and
beta (fast cooling) ·
Spangberg (1969): Gutta percha has low tissue
toxicity. But – REMEMBER that this is
due in part to particle size (small GP pieces are extremely inflammatory =
Sjogren 1995 Eur J Oral Sci). ·
Kolokruis (1992): Store GP in refrigerator and at low
humidity ·
GP in beta phase will shrink after warm compaction
technique, this is rationale for continued vertical compaction pressure ·
Moore & Genet (1982 OOO): GP cones display slow
acting (and weak) but significant antimicrobial action (may be due to ZnO) ·
Goldman & Schilder (1985): GP thermal study: beta to
alpha phase at 46-48C and GP in alpha phase to amorphous phase at
56-62C. A small volume reduction
occurs when cooling to 37C (so be
sure to vertically condense). ·
Constituents of GP Cone: 59-75% ZnO - filler; antimicrobial 19-22% GP - core material 1-17% Heavy metal sulfates –
radiopacity (eg., Barium sulfate) 1-4% Waxes & resins - make
more compactable; resins also antimicrobial 0.1-0.3% Pigments GP = trans isomer of isoprene
(= poly trans 1,4-isoprene) Alpha comes from tree ·
Beta made by heating alpha >65C and slowly cooling |
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Sunzel 1990 & 1995 |
Zinc oxide has effective antimicrobial activity. Note that GP cones contain ~70% ZnO, 20%
GP and rosins, waxes & metal sulfates.
The rosins confer “stickiness” to dentin, reduce ZnO solubility and
exert antimicrobial effects. The
setting of ZOE forms ZnO crystals in a matrix of zinc eugenolate. Friedman 1977 described composition of GP
cones. The coloring agent in
commercial GP is erythrosin (Marciano 1993). |
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Jacobsen (1984) |
If cut GP cone with scissors, it leaves a flange that
interferes with placement. To remove
flange, cold roll GP between spatula and glass slab or use rolling cut with
scalpel blade |
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GP
Solvents: Tamse '86 Hicks '90 McDonald '92 Chutich '98 Wilcox ’87 & ’89 Rotstein ’99 Metzger ‘95 |
GP
Solvents: ·
Tamse (1986): GP Solvents: chloroform > xylene
>> Endosolv-E > orange turpene ·
Wourms & Hicks (1990): Reviews use of halothane as
alternative GP solvent ·
McDonald & Vire (1992): Measured
room air chloroform levels during endo.
Air samples well below OSHA limits (8hr limit = 2 ppm) ·
Chutich (1998): The amount of
chloroform, halothane or xylene exiting thru apical foramen during in vitro
re-tx is 1,000 -15,000 times below permissible toxic dose. ·
Metzger (1995): Use solvent to soften coronal 1/2 of
overextended GP, insert Hedstrom, let GP set hard then slow withdraw GP ·
Stamos (1988): Don't let solvent get past apex! Pain!! ·
Rotstein (1999 JOE): chloroform, halothane & xylene:
softened dentin & enamel (chloroform softened dentin by 29% after 15min) ·
Wong & Peters (1982 JOE): Chloroform dip technique
shows 1.4% shrinkage (in contrast, chloropercha shows 12.4% shrinkage) ·
Wilcox (1987 & 1989 JOE): Examined RC walls after
heat, files, chloroform, US for Roths 801 vs AH26. All techniques incompletely cleaned walls; AH26 more difficult
to remove than Roths |
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Grossman's Sealer 42% ZnO - filler, antimicrobial 27% Stabelite resin - gives
body, coherance, good setting time 15% Bismuth Subcarbonate -
accelerates setting time 15% Barium sulfate -
radiopacity 1% Borax- retards setting time EUGENOL – matrix
(ZnO-eugenolate), antimicrobial, anti-PLA2,
neuromodulator (capsaicin congener) Why use sealer? Binding agent for RC core
filling material Fills voids and discrepancies
in canal walls Prevents leakage Acts as lubricant for fill |
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Mickel '99 Shalhav '97 Brown '94 |
Roth's
Sealer ·
Brown Jackson & Skidmore (1994): Apical seal with
Roth's 801 sealer better than Ketac-Endo ·
Mickel & Wright (1999): Roths sealer has better
antimicrobial activity vs Sealapex & CRCS (Ca(OH)2 containing
sealers. Probably due to
eugenol. In vitro evaluation using
Streptococcus anginosus ·
Abdulkader & Saunders (1996): In vitro antibacteria
activity against anerobes: Roths > Sealapex ·
Shalhav (1997) Roths exhibited 7day antimicrobial
activity against E. faecalis (Ketac
Endo was not as long-lived) ·
Grossman (1976): Roths's 801 little shrinkage when sets |
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Sealapex Base: Ca(OH)2 25% ZnO 6.5% Catalyst: Barium sulfate 18.6% Titanium dioxide 5% Zinc stearate 1% |
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AH26 (NB:
AH26 PLUS - see Leyhausen JOE) Powder: Silver Powder: 10% Bismuth Oxide: 60% Hexamethylenentetramine 25% Titanium Oxide 5% Liquid: 100% Bisphenoldiglycidyl ether |
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Torabinejad & Bakland 1979 |
No Ab formation or delayed
hypersensitivy to Grossman's sealer |
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Parasthesia After Obturation NaOCl Irrigation·
Reeh & Messer (1989 EDT): long term paresthesia
(still present at 15months) after injection 1% NaOCL thru buccal perf of a
maxillary incisor ·
Gatot (1991 JOE):
long term paresthesia can occur with NaOCL injection ·
Recommendations for tx NaOCL induced paresthesia: (from
Gluskin, POP): long acting LA, Amox X 5 days, analgesic, Steroid, cold
compresses LA·
Haas (1995): LA induced paresthesia (esp, Prilocaine,
articaine) esp mand blocks Sealer & Core Material·
Kleirer (1988 EDT): Sargenti: painful dysethesia of the
IAN after use of paraformaldehyde paste ·
Allard (1986): case report of N2 induced paresthesia ·
Tamse (1982 JOE): Case report of paresthesia after AH26
overfill ·
Nitzan & Stabholz (1983 JOE): 5 cases of paresthesia
after AH26 overfill; 1 overfill with ZOE sealer but no paresthesia ·
Leyhausen (1999 JOE): AH26 cytotoxicity due to release of
formaldehyde from the epoxy resin. Not seen with AH26 Plus. ·
Curson & Kirk (1968 OOO): ZOE sealers well tolerated
by PA tissues ALSO: Augsberger &
Peters (1990) ·
Serper (1998): Model of post-obturation paresthesia:
Isolated rat sciatic recording of compound action potential. 50% inhibition occurred at CRCS (6.6 min:
Ca(OH)2 containing sealer), Sealapex (9.2 min: Ca(OH)2 containing sealer), N2
universal (4 min: contains paraformadehyde).
IMPORTANTLY: After rinsing, Sealapex recovered fastest (6 min) then
CRCS (55min) or N2 (60min). Similar
to Kozman 1977 who reported eugenol inhibited frog sciatic activity. ·
Morse (1997): 2 cases reports of paresthesia after
NSRCT. Case 1: chloropercha overfill;
tooth asymptomatic for 2.5yr; then PARL increased and swelling, pain and
paresthesia developed; resolved after Sx removal of lesion. Case 2: Formocresol pulpotomy; paresthesia
started at 1 day; resolved after 7 weeks of dexamethasone (0.75mg #4 stat
then taper) antibiotics and irrigation. CC #1 = burning, painful, numb-like
sensation. CC #2 = numb lip Non-Endodontic Causes of Paresthesia: ·
Cancer metastasis: Glaser (1997 Intl JOS): numb lip most
common feature of metastatic CA. .
Also reported by Selden 1998 who found metastatic carcinoma as PARL on
mand molar; later developed paresthesia. ·
Dumas (1999): trigeminal sensory neuropathy. Sensory disturbance is ominous sign. MOA = CNS metastatic neoplasia (esp
men>60), multiple sclerosis. Often
rapid onset, ~50% report pain, differential of symptoms includes post-endo
pain ·
Antrim (1978): Infection-related paresthesia: 2 case
reports of mand molars necrotic & PARL: paresthesia resolved by NSRCT |
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Seltzer & Green 1972 |
Silver points removed in failed cases have corrosion
products of sliver amide hydrate which is cytotoxic. Corrosion is increased by bending,
cracking or deforming the cones at obturation. However, this was challenged by Kerekes & Rowe (1982) who found corrosion products on
successful silver cone cases (which were lost due to periodontitis). |
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Senia & Marraro 1975 |
GP cones sterilized at chair-side by 1 min immersion in
5.25% NaOCl. Also reported by Frank
& Pelleu 1983. |
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Siqueira 1998 EDT |
5% NaOCl destroyed Bacillus subtilis spores from GP cones
within 1 min of immersion |
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Blum 1998 |
Measured "wedging" force (predictor of fracture
force) during obturation: Thermafill << warm vertical =
thermomechanical (McSpadden) < lateral condensation |
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Cooke & Grower 1976 |
GP gives better seal than silver points |
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Economides & Kotsaki-Kovati 1995 |
Inflammatory response with sealers was least with CRCS
< Sealapex < Roths, AH-26 (AH26 had greatest inflammation) |
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Leyhausen 1999 JOE |
AH26 cytotoxicity due to release of formaldehyde from the
epoxy resin. This is NOT released
from the new formulation (= AH26 Plus), which showed lower cytotoxicity, and
no genotoxicity (umu test) or mutagenicity (Ames test). |
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Grossman 1976 |
Sealers: Roths 801 (little shrinkage when sets &
flows well), AH26 (flows well), Tubliseal (sets fast - consider Tubliseal
when doing sx right after completing NSRCT). |
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Horsted 1978 |
Reported good results in vital cases where hemostasis
cannot be controlled by obturating 2-4 mm short of the wound area. Should not do this in necrotic cases due
to concerns of remaining bacteria.
Recall: Sjogren (1990) data about success in necrotic cases! |
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Brothman 1981 |
Vertical compaction demonstrated TWICE the number of
lateral and accessory canals and denser fill. Also: Gutmann (1993) Showed enhanced adaptation of
thermoplasticized GP into dentinal tubules without smear layer |
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Sargenti Newton Spandberg Allard Kleier |
Sargenti ·
Sargenti - no rubber dam needed, access not addressed,
RCT length somewhere near apex, objective is chemical (not C&S), opposes
irrigation, try to keep N2 in canals but it is "well tolerated" in
PA tissues. 4-7% paraformaldehyde,
lead oxides ·
Cohler & Newton (1980): demonstrated short-term
severe cytotoxicity of Sargenti paste in monkeys ·
Newton (1980): Demonstrated 6m and 1yr cytotoxicity of
Sargenti paste ·
Spangberg (1974): The formaldehyde containing N2
formulation produces extensive tissue necrosis. Since the paraformaldehyde in
N2 will not be resorbed, must sx remove Sargenti material expressed beyond
apex. ·
Allard (1986): case report of N2 induced paresthesia ·
Kleirer (1988 EDT): painful dysethesia of the IAN after
use of paraformaldehyde paste (Sargenti) · Serper (1998 JOE): Model of post-obturation paresthesia: Isolated rat sciatic recording of c |