Risk of contamination of different areas of dentist's face during dental practices

Dental practice presents opportunities for cross contamination. The dentist's face is at high-risk of infection transmission. The purpose of this study was to evaluate the risk of contamination in different areas of dentist's face during dental practices. The visible splashes of materials that accumulated on cellulose face shields during 144 prosthetics and periodontal procedures were evaluated. The splashes were detected on 14 areas [each 1 cm[2]] of the dentist's face including around nose, mouth, eyes, and zygoma by a magnifier [X2]. One way analysis of variance, Duncan and t-test were used for data analysis [alpha = 0.05]. Contamination of different areas of dentist's face was significantly different [P < 0.05]. The areas around nose and the inner corner of eyes were the most contaminated areas. Zygoma was the least contaminated area. The contaminated areas during periodontal treatments were significantly more than prosthetic treatments [P < 0.05]. There was no significant difference between contamination on left and right sides of the face. During dental practice, central areas of the face such as inner part of the eyes and around the nose were most contaminated areas. These parts are the important areas for transmission of infection. It is recommended to use protective means like glasses, mask, and protective shield, which have more protection field in these areas

Influence of surface modification techniques on shear bond strength between different zirconia cores and veneering ceramics

PURPOSE: Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS: Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 microm Al2O3 particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T-test were selected to analyzed the data (alpha=0.05). RESULTS: In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION: Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain.

Effect of occlusal splints on the electromyographic activities of masseter and temporal muscles during maximum clenching

Despite the broad use of occlusal splints their efficacy is a source of controversy. In this study the effectiveness of stabilization splint on the electromyographic activity of the masseter and temporal muscles in healthy individuals was investigated. The stabilization splint was made for twenty-five healthy individuals. Surface EMG recordings of masseter and temporal muscles were done during maximum clenching without the splint and immediately after application of splint. The relative level of activity in the masseter and temporal muscles was quantified by means of Activity Index. Paired t-test and Wilcoxan signed -rank test were used for data analysis. The mean EMG activities of masseter and temporal muscles were 0.7712 and 1.0488 without splint and 0.8396 and 0.9276 with splint. There was no significant difference between the EMG activities of both muscles before and after insertion of the splints. The activity index increased after application of the stabilization splint. [-17.15 VS -4.4]. This increase was also insignificant. Immediate application of stabilization splint has no significant effect on the activity of masseter and temporal muscles. It could decrease the relative activity of the temporal to the masseter muscle [increasing of activity index]