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Aim:This study aims to evaluate the color change in human enamel bleached with three different concentrations of hydrogen peroxide, containing pineapple extract as an additive in two different timings, using reflectance spectrophotometer.Background:The study aimed to investigate the bleaching efficacy on natural teeth using natural enzymes.Materials and Methods:Baseline color values of 10 randomly selected artificially stained incisors were obtained. The specimens were divided into three groups of 20 teeth each: Group 1 – 30% hydrogen peroxide, Group II – 20% hydrogen peroxide, and Group III – 10% hydrogen peroxide. One half of the tooth was bleached with hydrogen peroxide, and other was bleached with hydrogen peroxide and pineapple extract for 20 min (Subgroup A) and 10 min (Subgroup B).Statistical Analysis:The results were statistically analyzed using student's t-test.Results:The mean ΔE values of Group IA (31.62 ± 0.9), Group IIA (29.85 ± 1.2), and Group IIIA (28.65 ± 1.2) showed statistically significant higher values when compared to the mean Δ E values of Group 1A (25.02 ± 1.2), Group IIA (22.86 ± 1.1), and Group IIIA (16.56 ± 1.1). Identical results were obtained in Subgroup B.Conclusion:The addition of pineapple extract to hydrogen peroxide resulted in effective bleaching.

Aim: The aim of the study is to compare the maximum stress distribution on the rotary retreatment instruments within the root canal at cervical, middle, and the apical one-third during retreatment of gutta-percha. Materials and methods: A human mandibular premolar was scanned, and three-dimensional geometry of the root was reconstructed using finite element analysis (FEA) software package (ANSYS). The basic model was kept unchanged; tooth models were created using the same dimensions and divided into two groups as follows: Group I: ProTaper Universal retreatment system and group II: Mtwo rotary retreatment system. The stress distribution on the surface and within the retreatment files was analyzed numerically in the FEA package (ANSYS). Results: The FEA analysis revealed that the retreatment instruments received the greatest stress in the cervical third, followed by the apical third and the middle third. The stress generated on the ProTaper Universal retreatment system was less when compared with the Mtwo retreatment files. Conclusion: The study concludes that the retreatment instruments undergo higher stress in the cervical third region, and further in vivo and in vitro studies are necessary to evaluate the relationship between instrument designs, stress distribution, residual stresses after use, and the torsional fracture of the retreatment instrument. Clinical significance: The stress developed on the rotary retreatment instruments during retrieval of gutta-percha makes the instrument to get separated. There is no instrument system, i.e., suitable for all clinical situations and it is important to

The role of root canal sealers is to close cavities in the canal and open accessory canals and multiple holes, create a connection between the canal wall and the surface of the filling material, and act as plasticizers for core fillings. The sealers are grouped according to their main chemical components: seals based on zinc oxide eugenol, caoh,gic, silicone, resin and bioceramics bioactive materials such as glass and calcium phosphate combine with the surrounding tissue to stimulate the growth of more robust tissue. Bioinert materials like zirconia and alumina has no effects on the adjacent tissues.