Evaluation of human enamel permeability exposed to bleaching agents

Aim: To evaluate the human enamel permeability after different external bleaching techniques.Methods: The coronal portions of 20 maxillary human incisors were covered with an acidresistant varnish, except the labial surface, to prevent dye penetration of silver nitrate. Thespecimens were divided randomly into four groups (n=5) according to the bleaching treatments:Group 1 (G1) - without bleaching agent (control group), Group 2 (G2) - 35% hydrogen peroxide(HP) – one session of three 10-min applications, Group 3 (G3) - 35% HP – 2 sessions of three10-min applications, and Group 4 (G4) - 6% HP – 14 days (1h/day). G1 was exposed to artificialsaliva only and in the other groups the bleaching agents were applied following the manufacturers’recommendations. After bleaching, teeth were immersed in a 50% silver nitrate solution for 2 hand photodeveloped for 16 h. Then, three longitudinal slices of each tooth were photographedby an optical microscope (100x). The degree of dye penetration was analyzed in the middle thirdof the dental crowns using a 0 to 4 score system (0= no dye penetration, 1= less than half theenamel thickness, 2= half of the enamel thickness, 3= full extent of enamel without reaching thedentin, and 4= tracer agent reaching dentin). The data were analyzed statistically by the Kruskal-Wallis and Dunn tests (α=0.05). Results: The median (1st/3rd interquartiles) ranges were: G1:0(0/0), G2: 2(2/3), G3: 3(3/3) and G4: 3(3/3). G2, G3 and G4 showed significantly higher dyepenetration compared with G1 (p=0.0017). Conclusions: The use of bleaching agents increaseddental enamel permeability, regardless of the bleaching technique.

Transformação de incisivos laterais conóides com resina composta: relato de caso / Transformation of conoid lateral incisors with resin composite: case report

A atual valorização da estética vai de encontro às discrepâncias de forma e tamanho dental comumente encontradas na clínica diária. Entre essas variações, os incisivos laterais conoides atingem 1,03% da população e podem refletir negativamente na saúde física e psicológica do indivíduo. Os resultados desse trabalho demonstram a possibilidade de resolução estética e funcional de forma simples e conservadora com o uso de resinas compostas

The current valuation of aesthetic aspects stumbles at discrepancies in tooth size and shape commonly found in everyday practice. Among these variations, conoid lateral incisors affect 1.03% of the population and may interfere negatively on the physical and psychological health of the individual. The results of the present study indicate the possibility of a simple and conservative solution with positive aesthetic and functional improvements using composite resins