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Week of October 6, 2004

Title: Root canal treatment in a population-based adult sample: status of teeth after endodontic treatment

Author: K. R. Tilashalski, et al

Journal: Journal of Endodontics, Vol 30(8):577-581, 2004

Reviewer: Kevin Axx, DDS

Purpose: To identify treatment outcomes of endodontically treated teeth, as measured by: (a) ultimate extraction of the tooth; (b) time to definitive restoration; and (c) generalist/specialist status of the treating dentist.

Materials & Methods:

· Used patient population from the Florida Dental Care Study (FDCS) that fit the following criteria: at least 45 years old, not in an institutional residence, resided in one of 4 nearby counties, had at least one tooth, had access to a telephone and could engage in a coherent telephone conversation. 873 subjects qualified

· Baseline: in-person interview and clinical examination

· telephone interviews at 6, 12, 18, 30, 36 and 42 mos. after baseline interview to assess nature and details of any dental visits within the time period

· In-person interview and clinical exam at 24 and 48 mos. after baseline

· Relevant procedures: anterior RCT, premolar RCT, molar RCT, extractions, operative and prosthodontic procedures. Not included: apicoectomy, root amputation, retreatment)

Results:

· by 48 mos, 743 (85%) of the 873 remained in the study

· 77% of subject had at least 1 dental visit in first 2 years of FDCS

· 75 relevant endodontic procedures were done with mean duration of follow-up after RCT of 24.8 mos.

· 59 teeth were restored definitively; mean of 4.4 mos after RCT. 9 teeth had no further treatment after RCT

· 14 teeth extracted during follow-up, mean of 10.1 mos; 7 did not receive restoration

· 56 teeth treated by general dentist, 19 by endodontists; 10 EXOS from GPs, 4 from endodontists.

· Mean time to restoration: 3.5 mos GP; 6.9 mos endodontist.

· mean attachment loss in teeth receiving RCT was 3.3

Conclusions: The advantage of this study was that it assessed treatment effectiveness in a nonscientifically controlled, private practice setting evaluating procedures not performed in a highly controlled, sometimes atypical manner. The limitation is the small sample size. The study defined success as retention of the tooth, and failure as loss of the tooth. This study demonstrated 81% success and 19% failure. The mean time between finishing RCT and definitive restoration was 4.4 mos with 12% never receiving definitive treatment. It is implied that the lack of an adequate seal of the root canal system from bacteria may be a contributing factor to failure. However, the reason for each extraction (i.e. failure) was never obtained.

Title: In vitro antibacterial effect of calcium hydroxide combined with chlorhexidine (CHX) or iodine potassium iodide (IKI) on Enterococcus faecalis

Author: Siren et al

Journal: European Journal of Oral Sciences 2004. Vol:112 p.326-331

Reviewer: Alex Wang, DDS

Purpose: To measure the antibacterial effect of combinations of calcium hydroxide with IKI or CHX against E.faecalis and to evaluate the cytotoxicity of the combinations. As alkalinity is considered important to the antimicrobial effect of calcium hydroxide, the effect of IKI and CHX on the PH in combinations was also studied.

Materials & Methods:

Part A: Testing for antibacterial activity

· Fresh bovine incisors were used with apical 3-4mm and the crown removed to create a chamber.

· A clinical strain of E.faecalis which had been isolated from a persistent root canal infection was used as a test organism.

· The test samples were taken from the dentine inside the lumen with round burs ranging in size which allows for a sequential removal of 100um-thick zones of dentine in order to test of depth of activity for the drugs.

· The dentine powder were incubated and cultured in test tubes with TSB medium.

· Control: 1) Using non-medicated samples and 2) Not adding dentine in medium.

Part B: Cytotoxicity test

The neutral red assay was used. This uses mouse fibroblast as subjects and expose them to a series of diluted agents of each drug and see how much bacteria were able to

stay alive.

Part C: Testing the effect of CHX and IKI on the PH of calcium hydroxide

PH in combinations was measured using titration technique with HCL.

Results:

· Calcium Hydroxide was ineffective against E.faecalis.

· Pure IKI and CHX were very effective against E.faecalis.

· 24h experiments showed a somewhat slower disinfection by combination drugs, however, after 1 wk, the effect of the combination drugs were almost the same as pure IKI or CHX.

· Addition of CHX or IKI did not affect the alkalinity of the products.

· Pure CHX or IKI were considerably more toxic than calcium hydroxide, however, the cytotoxicity of the mixtures was closer to that of pure calcium hydroxide. This suggests that calcium hydroxide protects host cells against the cytotoxic effect of CHX and IKI in the mixtures.

Conclusion: Additive effect can be achieved by combining calcium hydroxide with either IKI or CHX without negatively affecting calcium hydroxide’s alkalinity. This combination product may be beneficial in the treatment of certain types of persistent infections especially when E.faecalis is present.  

Title: Current challenges and concepts in the preparation of root canal systems: a review

Author: Peters, Ove A.

Journal: JOE, vol. 30 (8): 559 August 2004

Reviewer: Daniel Bitner, DMD

Purpose: The purpose of this article was to review current strategies with identification, accessing of the main canals, establishment and maintenance of adequate working lengths, selection of preparation sizes, and subsequent obturation.

Review: The variability of root-canal anatomy adversely influences canal preparation. Most root canals are curved, which when instrumented results in uneven force distribution in certain areas of the canal. Previously, to visualize the curvature of the root canal system with three-dimensional views one relied on multiple conventional radiographs. Recently, micro-computed tomography has emerged as a powerful tool for evaluation of root-canal morphology. Another difficulty with anatomy is found from clinical radiographs in the apical region. Zip-and-elbow formation and other well-described preparation outcomes such as ledges, strip-perforations, or excessive thinning of canal walls have in common that they are possible results of canal transportation. Canal transportation could result in inadequately cleaned canals with the possible outcome of persistent apical lesions. At present no evidence links improved canals shapes through Nickel-titanium (NiTi) instrumentation to higher success rates. Actively cutting tips produce more apical zips and perforations than instruments with non-cutting tips. Comparisons with earlier experiments indicated that NiTi instruments are superior to stainless-steel ones in their ability to shape. Instruments used in rotary motion separate in two distinct modes: torsional and flexural. Steel develops fatal fatigue after a few cycles. NiTi instruments may withstand several hundred cycles without fracture. For rotary NiTi systems, absolute canal transportation scores do not exceed 150 µm and gross preparation errors are rare, therefore, these systems can be considered safe and effective.

Determination and Maintenance of Working Lengths: Lightspeed® and Profile Series© 29 both forced significantly less debris apically compared to step-back instrumentation with K-files. Patency files should be used with care, however, a recent report indicates little risk of inoculation microbes in the periapical region. A recent clinical study on the endodontic treatment with NiTi instruments failed to show any significant effect of overfilling on healing rates. Although, one study indicated that to decrease risks, preparations 2 to 3 mm short of the radiographic apex, was recommended for vital cases. For non-vital cases 0 to 1 mm coronally to the radiographic apex was indicated. The author suggests that a perfect determination and maintenance of the working length is required. Length control seems to be simplified, but a three-dimensional concept of the apical dental anatomy is required to adjust instrumentation lengths to a specific clinical case.

Apical Widths: Principles of a standardized root canal preparation are mainly based on concepts of apical canal geometry developed in the 1950’s. However, relying on a standardized root-canal preparation would be problematic due to potential differences with anatomy. Mechanical instrumentation alone results in a reduction of bacteria. NiTi instruments allow wider shapes without major preparation errors and without over reducing radicular walls. The clinician has to carefully decide with which instrument and how wide to shape a given canal to achieve antimicrobial efficiency. Antimicrobial efficacy of endodontic therapy is of prime importance and depends, partly, on preparation length and width.

Conclusion: Nickel-titanium rotary instruments have become an important adjunct in endodontic therapy. Despite the existence of risk factors associated with dental anatomy, shaping outcomes with these instruments has become mostly predictable. However, despite superior in vitro results, the author feels that randomized, clinical trials are required to evaluate clinical outcomes when using NiTi rotaries in endodontic therapy.

Title: Microbiological evaluation of one- and two- visit endodontic treatment of teeth with apical periodontitis: a randomized, clinical trial

Author: T. Kvist, A. Molander, G. Dahlen, and C. Reit

Journal: JOE, Vol. 30, No. 8 (p572-576), August 2004.

Reviewer: Brian S. Jeon, DMD

Purpose: To compare the microbiological outcome of a one-visit treatment regime, including an intra-appointment dressing w/ 5% IPI (iodine-potassium-iodide) with a two-visit procedure, including an inter-appointment dressing w/ Ca(OH)₂.

Materials & Methods:

• 96 asymptomatic teeth w/ necrotic pulps and apical periodontitis were randomly assigned to one or two-visit group, using the “minimization method.” 52 teeth were assigned to one-visit and 44 teeth were assigned to two-visit group.
• In one-visit group, following instrumentation w/ 0.5% NaOCl irrigation, the smear layer was removed w/ Tublicid Plus, and subsequently, the canals were filled w/ 5% IPI solution for 10 minutes before final sampling and obturation.
• In two-visit group, following instrumentation w/ 0.5% NaOCl irrigation, Ca(OH)₂ was placed w/o the smear layer removal, and the canals were sampled and obturated 1 week later.
• Bacterial samples were obtained before instrumentation, immediately after instrumentation, and after medication, and all samples were incubated and cultured for the identification and semiquantification of bacterial species.
• Chi-square test was used for comparisons b/w groups at the 0.05 level of significance.

Results:

• Initial sampling demonstrated the presence of microorganisms in 98% of the teeth. The composition of the microbiota in the two groups was similar.
• Post-instrumentation sampling showed reduction of cultivable microbiota. However, bacteria were still found in 62% of teeth in the one-visit group and 64% in the two-visit group.
• Antibacterial dressing further reduced the number of teeth w/ surviving microbes. In the post-medication samples, residual microorganisms were recovered in 29% of the one-visit teeth and in 36% of the two-visit treated teeth. However, no statistically significant differences b/w two groups were found.

Conclusion: From a microbiological point of view, treatment of teeth w/ apical periodontitis performed in two appointments was not more effective than the investigated one-visit procedure (*note: smear layer was not removed in the two-visit group).

Title: The adhesion between fiber posts and root canal walls: comparison between micro-tensile and push-out bond strength measurements

Author: Goracci et al.

Journal: European Journal of Oral Sciences

Reviewer: Brian Chang, DDS

Purpose: The aim of this study was to compare the trimming and non-trimming variants of the micro-tensile technique with the ‘micro’ push-out test in the ability to measure accurately the bond strength of fiber posts luted inside root canals.

Materials and Methods:

1. 30 upper anterior teeth were extracted and endodontically treated and restored with a cylindrical 1.6mm diameter glass fiber post and a composite core.
2. Specimens were divided into two groups of 15 teeth each. Group A had the posts cemented and luted with Excite DSC variolink II dual cure resin cement and group B had posts cemented with Rely-X Unicem self adhesive resin cement.
3. 3 separate groups of preparations were made to test the bond strength:
1. Preparation of hourglass shaped specimens for micro-tensile bond strength testing: 6 roots each from groups A and B were sectioned perpendicular to the long axis in 1mm thick slices and trimmed to an hourglass profile. The specimens were loaded until failure occurred and the bond strength was measured.
2. Preparation of beam shaped specimens for micro-tensile bond strength testing: 3 roots each from groups A and B were sectioned longitudinally, parallel to the long axis of the tooth in 1mm thick sections, then serially sectioned again perpendicular to the long axis in 1mm increments. 2 sections from groups A and B were processed for the SEM, while the remaining sections were tested for bond strength.
3. Preparations of the specimens for the push-out bond strength test: 6 roots each from groups A and B were horizontally sectioned in 1mm increments. The post was then loaded in an apical coronal direction touching only the post. The load at bond failure was recorded.

Results:

1. With the trimming technique, there was 16.9% failure in group A, and 27.5% failure in group B. These failed at the debonding or cutting phases. Bond strength for group A was measured at 12.3(+/-) 11.1 Mpa (coefficient of variation of .90) and for group B it was 9.1(+/-) 10.3Mpa (coefficient of variation of 1.13).
2. Almost all specimens from the non trimming technique failed prematurely during the cutting phase. The # obtained was so low, no statistical parameter would be meaningful.
3. None of the prepared specimens failed prematurely for the push-out technique. The bond strength for group A was 6.89 (+/-) 3.77 Mpa and for group B it was 5.01(+/-) 2.63 Mpa.

Discussion:

1. The trimming and non trimming techniques had so many premature failures; the data obtained is not very statistically significant. The vibrations during the cutting most likely caused uncontrolled stress. These results may lead to a marginal hypothesis that the level of bond strength achievable in a clinical setting when a fiber post is adhesively luted to the root canal wall are in fact very low.
2. The push out form had no premature failures and was the most reliable technique. These results indicate a stronger bond with the Variolink II vs. the Rely-X.
3. This study shows that the push-out test is more efficient and dependable than micro-tensile testing.

Week of October 20, 2004

Title: Injection pain and post-injection pain of the anterior middle superior alveolar injection administered with the Wand^â or conventional syringe

Author: Nusstein et al

Journal: OOOOE Vol 98(1):124-131, 2004

Reviewer: Hung Do, DDS

Purpose: To compare the pain of injection and post-injection pain using the computer-assisted Wand Plus^â injection system versus a conventional syringe

Materials &Methods:

^· 40 adults in good health

^· subjects were blind-folded before receiving injections

^· each subject received 1 injection with the Wand^â (slow setting - 1drop every 2 seconds) at one appointment, and received another injection with a syringe at the other appointment

^· appointments were 1 week apart

^· injections were made into the hard palate (anterior middle superior alveolar -AMSA- injections)

^· both methods used a 27-gauge needle

^· both methods deposited a total of 1.4 ml of 2% lidocaine with 1:100K epi over 5 min. duration

^· both methods used topical

^· all injections were made by one person

^· subjects graded the level of pain using a Heft-Parker VAS scale (none-maximum intensity)

Results:

^· needle insertion- 38% had mod/severe pain with Wand^â and 34% had mod/severe pain with syringe. No significant difference

^· solution deposition- 25% had mod/severe pain with Wand^â and 42% had mod/severe pain with syringe. Significant difference

^· post-injection swelling- 8% with Wand^â and 10% w/syringe. No significant difference

Conclusion:

· The Wand^â causes less pain while depositing anesthetic solution. Otherwise, there's no difference between the Wand^â and conventional syringe

Title: Evaluation of different methods for the root-end cavity preparation

Author: Khabbaz et al.

Journal: O.O.O. and Endo., 98(2) 237-242, August 2004

Reviewer: Sahrip Kim, DDS

Purpose: The dentinal walls of root-end cavities were examined for the presence of cracks and debris in correlation with the area of the root surfaces that remained after the resection using different devices.

Materials &Methods:

• 100 extracted single rooted teeth were treated endodontically, mounted in acrylic resin blocks and the apical 2mm of the root apex was resected.
• The teeth were divided into 2 groups according to the size of resected root surface area (>2mm², <2mm²).
• 4 devices were used for retrograde cavity preparation: slow-speed handpiece, diamond coated stainless steel ultrasonic tips, smooth stainless steel ultrasonic tips, and sonic diamond-coated tips.
• Teeth were examined under a video microscope for the presence of fractures, dentin chips and gutta percha remnants on the cavity walls. Preparation time was also recorded.

Results:

• The area of the root-end dentin surfaces after resection does not influence the crack formation during the preparation of the root-end cavity with rotary, sonic, and ultrasonic instruments.
• Cracks were produced at the root-end face, mainly when the smooth stainless steel ultrasonic retrotips were used.
• Dentinal chips were found in all experimental groups with the highest rate in the rotary instrument group.
• Gutta percha remnants on the cavity walls were mainly detected in teeth prepared with ultrasonic retrotips.
• The time needed for the preparation of the root-end cavities with the sonic and ultrasonic devices was more than double compared to that of the rotary instrument group.

Conclusion:

• Sonic and ultrasonic devices produced cleaner, well-centered, and more conservative root-end cavities than the rotary instrumentation.
• Cracks do not correlate directly with the surface area of the root-end surfaces but rather with the type of retrotip used to prepare the root-end cavity.

Title: A comparison of survival of teeth following endodontic treatment performed by general dentists or by specialists

Author: Alley, B. S. et. al.

Journal: Oral Med Oral Pathol Oral Radiol Endod 2004;98:115-118

Reviewer: Vahid Atabakhsh, DDS

Objective: A chart review study at 3 different general practitioner offices in Alabama to compare success of endodontic treatment provided by specialists versus generalists

Methods and Materials: To qualify for the study the general dentists had to perform some endodontic treatment and to refer some to endodontists. Success was defined as the treated tooth being present at 5 years after the date of treatment initiation. This criterion was chosen because of its unequivocal categorization of results. Calibrated dentists reviewed over 3,000 charts.

Results: Three hundred fifty charts met the inclusion criteria.

• 195 teeth were treated by generalists, with an 89.7% success rate.
• 155 teeth were treated by endodontists, with a 98.1% success rate.
• Endodontists treated more molars, and generalists more anteriors and premolars, even some third molars.
• Generalists were more likely to treat teeth with periapical radiolucencies (PARL) than calcifications or curvature.
  
  Many observation categories were too small to draw statistically significant conclusions. One practice (#2) that referred twice as many than others showed only failure rate less than half its peers. This practice also placed much higher rate of crowns. Results were not statistically significant.

Conclusion: Endodontic treatment by specialists was significantly more successful. This might be due to additional training by endodontists. Endodontists also treat more difficult cases and more re-treatments. From these results, the long term survival of teeth treated by endodontists is equal or better than the long term outcome of implants seen in other studies.

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Created: September 20, 2000 Revised: URL:

Roy H. Stevens, DDS, MS; Wanda Gordon, D.M.D. - Comments to author:	wgordon@dental.temple.edu
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