A comparative evaluation of colour stability of different resin cements and its influence on the final shade of All-Ceramic Restorations: An in-vitro Study.

Introduction: Colour changes of the luting material can become clinically visible affecting the aesthetic appearance of thin ceramic veneers. Therefore, unfortunately, the long-term success of veneers is tied to the colour stability of the luting agent used to cement them. Aim: To compare the colour stability of different resin cements and its influence on the final shade of overlying ceramic using two different thicknesses of ceramic. Material and Methodology: Sixty disc-shaped specimens of high translucency (HT) A2 shade of two thicknesses (0.5 mm & 1 mm) were prepared from lithium disilicate glass-ceramic. The discs of each thickness were further divided into three groups randomly depending upon the resin cements used. Group A - light cure resin cement - Variolink N LC by Ivoclar Vivadent in clear shade, Group B - base paste of dual-cure resin cement - Variolink N by Ivoclar Vivadent in transparent shade and Group C dual-cure resin cement - Clearfil esthetic cement EX by Kuraray in clear shade were used to compare their colour stability. A spectrophotometer was used for the colour measurements of the specimens before and after accelerated ageing. The colour stability was determined by colour differences (ΔE) using the coordinates L*, a* and b* in the pre and post accelerated ageing. Results: On comparing the three resin cements, Group A showed the lowest ΔE, whereas the highest ΔE was observed in Group B. This finding was constant for discs of both thicknesses. Conclusion: Even though statistically significant results were observed between the groups, they were not visibly differentiable.

A novel, new generation drill coating for osteotomy site preparation.

BACKGROUND: Implant success and survival rate ranges from 93% to 97%; however, failures are not very uncommon. These failures can be caused due to a variety of reasons out of which increased heat during drilling of osteotomies is a major contributor. AIM: The aim of this study was to develop a new generation diamond-coated drill and compare the thermal changes between commercially available drills and the experimental diamond coated drill during implant site preparation in artificial bone. MATERIAL AND METHODS: Three types of drills were selected for the study; Group A (Carbide), Group B (Stainless Steel), and Group C (Experimental). A total of 60 implant site preparations were performed with all the drills in artificial bone using a surgical unit linked to a testing device, in order to standardize implant drilling procedures. Bone temperature variations were recorded when drilling at a depth of 10 mm. A constant irrigation of 50 ml/minute and drilling speed of 800 r.p.m. was maintained. RESULTS: The mean temperature of Group A, Group B, and Group C was 35.57°C, 36.83°C and 34.23°C, respectively. The results were assessed and statistically analyzed using ANOVA test and post hoc Bonferroni test. Statistically significant higher temperatures were obtained with stainless steel drill and carbide drill when compared with the experimental diamond coated drill. (P = 0.000). CONCLUSIONS: Diamond coated osteotomy drills have shown promising results in reducing heat generation at the osteotomy. Further studies need to be conducted to maximize the potential use of diamond as components of drills in implant dentistry.