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Studies have shown significant bacterial leakage following exposure of sealed root canals to artificial and natural saliva. The objective of this study was to determine contamination via bacterial migration in artificial saliva in endodontically treated teeth using different obturation techniques and sealers. A total of 144 extracted, human mandibular anterior teeth were cleaned and shaped to a #40 master apical file using hand and rotary instrumentation. One hundred and twenty teeth were divided into two experimental groups. The teeth in Group 1 were obturated with gutta-percha using lateral compaction and five different sealers, and the teeth in Group 2 were obturated with gutta-percha using thermomechanical compaction and five different sealers. The remaining 24 teeth were prepared as positive and negative controls. All specimens, except the negative controls, were inoculated every five days with Anaerobic streptococci (NCTC 9891) related to Peptostreptococcus micros and Prevotella intermedia (ATCC 25611). The contamination onset time was continuously recorded and turbid broths cultured for bacteria identification. The controls behaved as expected. Regardless of the combination between obturation techniques and different sealers, all broths became turbid during this experiment. The correlation between the obturation techniques and the sealers revealed statistical significance using ANOVA (p<0.0001), followed by the Duncan Multiple Range Test, which determined the ranking between these interactions. The combination of MicroSeal obturation technique with Ketac-Endo sealer allowed a slower rate of coronal-apical bacterial migration.

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STATEMENT OF PROBLEM: Given the complexity of tooth color, the variations of shade within each tooth, and translucency, it is difficult to view only one small area and select a shade match for restorations. PURPOSE: This study tested the effect of specimen design on porcelain shade matching, hypothesizing that flat disks would be matched to one another with more accuracy than tooth-shaped tabs to tabs. MATERIALS AND METHODS: All testing was conducted in a Macbeth SpectraLight booth with D65 illumination. Seventy-three senior dental students (25 women and 48 men; mean age, 27 years) were asked to match selected Vita porcelain disks and Vita shade tabs to like specimens. The design order, namely matching tabs or disks first, was alternated for each observer. The specimens were handed to the observer individually. No time limit for matching was imposed, although each observer was given explicit instructions related to the observation and handling of the specimens. Upon completion of the matching exercises, each student received his or her standardized test results and reviewed the matching results. The time for testing and review was approximately 20 minutes per observer. An analysis of variance, with gender and order as 2 factors that could affect matching scores, was performed (P <.05). RESULTS: The mean matching scores were 78.4% for disks and 73.6% for tabs (P=.119). Female observers matched 76.5% of the disks and 77.5% of the tabs, whereas male observers matched 79.4% of the disks and 71.6% of the tabs (P=.054). Matching disks before tabs yielded equivalent levels of shade matching (disks, 77.6%; tabs, 77.1%). When tabs were matched first, the scores were as follows: disks, 79.8%, and tabs, 67.3% (P=.010). CONCLUSIONS: Within the limitations of this study, there was no significant difference in shade-matching accuracy between the 2 shapes, although the order of design matching resulted in a difference in shade-matching ability. When tabs were matched first and disks second, improved matching was evident on the second test. The reverse was not true; no learning was demonstrated when the tabs were matched after the disks.

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