Comparison of different cleaning procedures of implant drills using TC99.

PURPOSE: This study was carried out to evaluate implant drills' cleaning protocols efficiency as tested by the use of nuclear medicine. METHODS: Eighty-one new drills of 2 different implant systems (Nobel Biocare and BioMet 3i) were selected as study samples. Six of these drills were used as positive control group, and the rest were contaminated with TC-labeled blood. The instruments were divided randomly into 5 groups (negative control group; group 1: immersion and brushing; group 2: immersion and brushing and then evaluation under magnifier; group 3: immersion and brushing and then ultrasonic cleaning for 15 minutes; and group 4: immersion and brushing and then ultrasonic cleaning for 30 minutes) so that every group contained equal number of each implant drills brand. Then the emitted γ rays were counted by means of a gamma counter. RESULTS: Statistically significant differences were observed between the full cleaning protocol and ultrasonication group (P < 0.009). Immersion and brushing, and ultrasonic cleaning for 30 minutes before sterilization, were the most effective methods to remove contamination. CONCLUSIONS: Complete removal of biologic debris was not attained with any of the cleaning techniques used. It is recommended to use ultrasonic cleaner for 30 minutes after immersion and brushing to achieve the best results.

Marginal adaptation of indirect composite, glass-ceramic inlays and direct composite: an in vitro evaluation.

OBJECTIVE: This experimental in vitro study compared marginal adaptation of indirect composite, glass-ceramic inlays and direct composite. MATERIALS AND METHODS: Seventy-five recently extracted human molars were randomly divided into three groups (n=25) and mesio-occluso-distal cavities with the same dimensions were prepared in the teeth. Indirect composite and glass-ceramic inlays were fabricated following manufacturer's instructions and the marginal gap was measured by a stereomicroscope at magnification 40× before cementation. After cementation of inlays and restoring the third group by direct composite, all the specimens were thermocycled and the marginal gaps were measured exactly as previously described. Repeated measure ANOVA and post-hoc Tukey test were used for pairwise comparison of occlusal, proximal, and gingival marginal gaps in each group. One-way ANOVA and post-hoc Tukey test were used for comparison of mean marginal gap in the three groups and for comparison of marginal gap before and after cementation in inlays, paired T-test was used. RESULTS: The marginal gap of direct composite (19.96 µm) was significantly lower than that of indirect composite inlay (48.47 µm), which in itself was significantly lower than that of glass-ceramic inlay (60.96 µm). In all the restorations, marginal gap in the gingival margin was significantly higher than occlusal and proximal margins. The marginal gap of inlays did not change after cementation and thermocycling. CONCLUSION: This study indicated that the marginal gaps of the evaluated restorations are less than 100 µm, which is clinically acceptable.