Background:Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide - Amorphous Calcium phosphate (CPP-ACP) brought about the reduction in stain absorption, which is assessed in this study.Aims:The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth with varied surface treatment. The stain absorption was evaluated at the end of one hour and 24 hours post bleaching.Materials and Methods:Forty extracted human permanent maxillary central incisors were subjected to bleaching with 10% carbamide peroxide for eight days. They were divided into four groups of 10 each. Group I was control group. Group II was immersed in tea solution without surface treatment, while Group III and IV were immersed in tea solution with surface treatment of topical Fluoride and CPP-ACP respectively. Spectrophotometer was used for color analysis.Results:Surface treatment with CPP-ACP and topical fluoride on freshly beached enamel surface, significantly reduced the stain absorption.Conclusion:Remineralizing agents reduce stain absorption after tooth bleaching.

Context:Desensitizers are used to reduce dentin hypersensitivity. They affect the surface texture of prepared dentin and may alter the retention of fixed restorations.Aims:The aim was to evaluate the effect of dentin desensitizers on the retention of complete cast metal crowns luted with glass ionomer cement.Subjects and Methods:Fifty freshly extracted human premolars were subjected to standardized tooth preparation (20° total convergence, 4 mm axial height) with a computer numerically controlled machine. Individual cast metal crowns were fabricated from a base metal alloy. Dentin desensitizers included none (control), a glutaraldehyde (GLU) based primer (Gluma desensitizer), casein phosphopeptide (CPP)-amorphous calcium phosphate (ACP) (GC Mousse), erbium, chromium: YSGG laser (Waterlase MD Turbo, Biolase) and Pro-Argin (Colgate Sensitive Pro-Relief desensitizing polishing paste). After desensitization, crowns were luted with glass ionomer cement and kept for 48 h at 37°C in 100% relative humidity. The samples were tested using a universal testing machine by applying a load at a crosshead speed of 0.5 mm/min.Statistical Analysis Used:Statistical analysis included One-way ANOVA, followed by the Scheffe post-hoc test with P < 0.05.Results:All dentin desensitizers showed significantly different values: Pro-Argin (4.10 Megapascals [Mpa]) < CPP-ACP (4.01 mpa) < GLU based primer (3.87 Mpa) < Virgin dentin (3.65 Mpa) < LASER (3.37 Mpa).Conclusions:On comparing the effect of prepared virgin dentin, GLU based primer, CPP-ACP, LASER and Pro-Argin on the retention of complete cast metal crowns luted with glass ionomer cement on prepared teeth, it can be concluded that Pro-Argin and CPP-ACP showed the best retention in this in vitro study.

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Aim: The aim of the study was to compare the assessment methods used to evaluate the fit of Ni-Cr metal copings. Settings and Design: Comparative- Invitro study design. Materials and Methods: A stainless steel die simulating a prepared first maxillary premolar was used as a master die. Wax pattern copings were fabricated by the conventional dipping wax technique ( n = 20) on the master die and were cast in Ni-Cr alloy. The finished copings were fitted on the master die and scanned by the micro-computed tomography (CT) scanner. Multiple projections of the sample were reconstructed to evaluate the marginal and internal fit at 5 predetermined locations. The same copings were used for the replica technique and were evaluated under a stereomicroscope in the same locations. Statistical Analysis Used: Shapiro–Wilk's test and Unpaired t -test Results: The marginal fit values observed were 127.71 and 95.06 μm, chamfer area fit values were 151.97 and 132.7 μm, axial area fit values were 62.36 and 46.14 μm, axio-occlusal area fit values were 139.52 and 123.6 μm, occlusal area fit values were slightly higher with 217.91 and 193.1 μm, respectively, in replica and micro-CT technique. There was no statistically significant difference observed in the fit between the two assessment methods (α > 0.05). Conclusions: There was no difference observed in the marginal and internal fit of Ni-Cr metal copings with the two methods of assessment. However, the micro-CT technique proved to be simpler, noninvasive, and time-saving assessment method.