Aims:To compare the canal transportation, centering ability, and remaining dentin thickness of WaveOne and ProTaper systems using cone beam computed tomography.Subjects and Methods:Forty extracted human single-rooted premolars were used in the present study. Preinstrumentation scanning of all teeth was taken; canal curvatures were calculated, and the samples were randomly divided into two groups, with twenty samples in each group; one group was instrumented with WaveOne system and the other group with ProTaper rotary system. Postinstrumentation scans were performed, and the two scans were compared to determine canal transportation, centering ability, and remaining dentin thickness at 3 mm, 6 mm, and 9 mm from the root apex.Statistical Analysis Used:Student's unpaired t-test.Results:Using Student's unpaired t-test, results were as follows: for canal transportation, Group 1 showed significant difference at 3 mm and 6 mm and insignificant difference at 9 mm while Group 2 showed insignificant difference in all the three regions. For centering ability and remaining dentin thickness, Group 1 showed insignificant difference at 3 mm and 9 mm while significant difference at 6 mm was obtained. When comparison of remaining dentin thickness was done at three levels using two groups WaveOne and ProTaper, there was no significant difference between two groups.Conclusions:(1) WaveOne single reciprocation file system respected better canal anatomy better than ProTaper. (2) Individually, centering ability of WaveOne was better at 3 mm, 6 mm, and 9 mm levels. (3) However, ProTaper individually was better centered at 3 mm (apical third) and 9 mm (coronal 3rd) levels than 6 mm level (middle third).

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The objective of this work was to develop a short-term, clinically simulative, biofilm-based aging/storage model for lab testing of newer dental adhesives in order to predict their long-term performance. To do this we tested the hypothesis that 15 days of biofilm challenge with cariogenic bacterial species, Streptococcus mutans (SM) and Streptococcus sobrinus (SS), would produce similar or a greater reduction in microtensile bond strength (μTBS) of dental adhesives as compared to a standard 6 months of water storage (WS). Thirty-one molars were flattened to dentin, restored using Optibond-FL adhesive and Z-100 dental composite, sectioned and trimmed into four dumbbell-shaped specimens and randomly distributed according to aging conditions (n=31): A) Water storage for 6 months, B) Water storage for 5.5 months + S. mutans-biofilm challenge for 15 days, C) S. mutans-biofilm challenge for 15 days and D) S. sobrinus-biofilm challenge for 15 days. Specimens were gripped centrally with respect to the test axis with a nongluing passive gripping device. Microtensile bond strength testing was performed using a Zwick Material Testing Machine at a crosshead speed of 1 mm/min and failure modes were classified using light microscopy. Mixed model ANOVA and Weibull regression analysis revealed that the type of storage condition significantly affected the microtensile bond strength (p<0.0001). Mean microtensile bond strength observed within group A (49.69 ± 15.53MPa) was significantly higher than those in groups B (19.26 ± 6.26MPa), C (19.92 ± 5.86MPa) and D (23.58 ± 7.88MPa). Also, microtensile bond strength obtained with group D was significantly greater than that with groups B and C, while no difference was seen between vi the latter two groups. Chi-square statistical analysis indicated that specimens from groups B (74.2%), C (83.9%) and D (80.6%) were more likely to have cohesive failures in dentin than specimens from group A (54.8%). Within the limitations of the study, it can be concluded that 15 days of Streptococcus mutans-and Streptococcus sobrinus-based biofilm challenge produced more reduction in microtensile bond strength of dental adhesive than 6 months of water storage and appear to be a promising in vitro accelerated aging model.

To establish a ratio of variable bone height (Infrazygomatic alveolar crest height) to constant bone height (Infraorbital zygomatic height) and, to estimate the relative sinus floor position from alveolar crest of maxillary first molar region of dentulous Indian males and females, using Digital panoramic radiographs. Panoramic radiographs of 74 patients were included in the study (37 male, 37 female) to measure maxillary posterior vertical bone height and their ratio in dentulous patients. Measurements were made from reference lines drawn from anatomic landmarks on soft digital versions of standardized panoramic radiographs using Kodak dental imaging software. Later the data were analyzed using normal test (Z-score). When the posterior maxillary bone height and their ratio were evaluated in Indian population, the vertical bone height (x, y, z) of males was more than the females. Ratio of Infrazygomatic-alveolar crest distance (y)/Infraorbital-zygomatic distance (x)-was 0.74 for Indian males and females. The relative sinus floor for Indian males was found to be 8.1 mm and that of Indian females to be 7.8 mm. The results are of significant value as "baseline" data, in serial studies where alveolar bone height for a single patient is compared at different times before and after tooth loss. The relative sinus floor position from alveolar crest can help in implant length selection. This study can be used as a diagnostic and predictive tool in implant treatment planning but further long-term evaluation is still required to prove the efficacy of this study.