Effect of Two Different Surface Treatments on Retention of Cosmopost with Two Different Core Materials.

OBJECTIVE: The objective of this study was to determine the effect of Cosmopost's two different surface treatments (sandblasting and silica coating) on persistence to various core materials using push-out test set-up. MATERIAL AND METHODS: A total of 30 Cosmoposts was used in this study. Cosmoposts were divided into three groups (10 samples each) according to the post-surface treatment received. Every category was additionally subdivided into two subgroups according to the type of core material (n = 5 samples). A specially designed copper mold was used for construction of different core materials with standardized dimensions around the posts, in such a way to ensure that the posts will be centralized. Surface roughness was estimated for all Cosmoposts, following different surface treatments using SEM. Cylindrical cores were fabricated of either composite resin or heat-pressed zirconia-containing glass-ceramic (IPS Empress Cosmo, Ivoclar Vivadent). Following the construction of different Core materials, samples were subjected to push-out test set-up to Evaluate the impact of various treatments on post/core bond strength. Data were collected, tabulated and statistically analyzed. SEM was performed on Cosmoposts following debonding of different post/core samples to determine their mode of failure. RESULTS: Results of push-out bond strength revealed that core material, surface treatment and the interaction between the two variables using Two-way ANOVA had a statistically significant effect on mean push-out bond strength. Regarding the effect of type of core material on Push-out bond strength, results showed that IPS Empress Cores showed statistically significant higher mean push-out bond strength to Cosmopost (36.4±9.7MPa) than composite cores (15.8±2.5 MPa). CONCLUSION: Within the limitations of this study, direct heat-pressed ceramic core was more beneficial for zirconia post buildups, than Composite Cores, since they provided higher bond strength. Thanks to a double improvement: increase in fracture resistance and retentive capacity to post. Also, Tribochemical Silicacoating technique was proved to be more effective in Cosmopost treatments than sandblasting technique.

Attitude and knowledge of isolation in operative field among undergraduate dental students.

OBJECTIVE: The purpose of this study was to evaluate the general attitude of undergraduate dental students toward rubber dam use, specifically focusing on operative procedures before starting to serve community. METHODS: Questionnaires were distributed to undergraduate clinical years' students of two private colleges; Al-Farabi Dental College, Riyadh, KSA and Buraidah Private Colleges, Qassim, KSA. Questions were asked about areas where the students used rubber dam in operative procedures, in which types of caries classes, and in which type of restoration they frequently used the rubber dam. RESULTS: We found that students of both private dental colleges agreed with the opinions that proper isolation cannot be achieved for the restoration of operative procedures without using rubber dam and restoration placed under rubber dam have a greater longevity than those placed without. CONCLUSIONS: Within the limitations of the present study, it can be concluded that the perceptions of dental students on rubber dam need to be improved and strategies should be developed so that this valuable adjunct will comprise one of the indispensable elements of dental care.