Résumé
Statement of the Problem: Exposure to patients' blood and body fluids would prone the dental students to the risk of blood borne infections. Several studies have shown a high prevalence of these exposures in dental settings particularly in developing countries. However, few studies have evaluated the epidemiology of these exposures in dental students in Iran
Purpose: To assess the epidemiology of occupational exposures among dental students and consequently designing the appropriate interventions in order to prevent these exposures
Materials and Method: In this cross-sectional study performed during March to June 2011, all 191 Shiraz clinical dental students were asked to complete a self-administered questionnaire. This questionnaire included demographic information and experience of sharp injuries and mucocutaneous contaminations. Chi square and t-test were employed to evaluate the risk factors of exposure
Results: 80%of the participants were exposed to the patients' blood or body fluids during their clinical course. No association was found between the exposure and demographic factors. Injection needle and recapping were the most common causes of these injuries. The most common sites that were injured and caused mucocutaneous contamination were finger and face, respectively. The most frequent activity causing contamination was using high-speed rotary instruments. Only 6.4% of the exposures had been reported to the related authorities and the remains were underreported
Conclusion: Blood and body fluid exposure in dental setting is common and a lot of them are not reported. To reduce the hazards of these exposures, infection control authorities should design interventions especially for mentioned high-risk conditions. They should change dental students' behavior especially regarding not recapping injection needles and using eyewear. Dental schools seem to need a management center and a standard protocol for following up the exposures
Résumé
Statement of the Problem: Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration
Purpose: The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated
Materials and Method: Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs [n=10]. The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student's t-test and paired t-test [alpha=0.05]
Results: There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing [p= 0.014 and p= 0.000, respectively]. The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration [p= 0.000], but there were no significant differences between the two marginal designs, after porcelain firing [p= 0.341]
Conclusion: Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy
Résumé
PURPOSE: This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS: Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (alpha=.05). RESULTS: Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group (63.06 microm) was higher than press-over (50.64 microm) and CAD-on (51.50 microm) veneered groups (P<.001). CONCLUSION: Three veneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CAD-on techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit.