Journal of Dental Medicine

Statement of Problem: Bleaching materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that bleaching is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments.

Purpose: The aim of this study was comparing the effect of two bleaching materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM.

Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control), without any bleaching. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications.

Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards.

Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

  Background and Aims : The aim of this study was to evaluate the effect of chlorhexidin 2%, sodium hypochlorite 2.5% and hydrogen peroxide 3% as three effective and regular disinfectants on the microleakage of 7th generation bonding agents in vitro.

  Materials and Methods: 45 extracted molar teeth without carries were collected and disinfected. On buccal and lingual aspects of these teeth conventional class V cavity preparation were done (90 cavities), then randomly divided to 4 groups, three of them had 10 teeth (20 cavities) and one of them had 5 teeth (10 cavities) as control group. Cavities in each experimental group prepared with one of the disinfectants and then 7th generation bonding (Optibond all in one, kerr) was used as noted by manufacturer, then cavities filled with composite and polished. Bonding agent was used without our previous disinfectants manipulation in control group. Specimens were thermocycled with 1000 thermal cycles between 5 and 55 ⁰ C each for 30 seconds and then immersed in the methylene blue 5%, then sectioned mesiodistally and investigated for microleakage under stereomicroscope (Olympus, Japan). Data were analyzed using Kruskal-Wallis and Wilcoxon mean rank tests.

  Results: Despite the lower mean rank values for the untreated group at both occlusal and gingival aspects, the Kruskal-Wallis procedure (α=0.05) showed that the treatment factor did not significantly affect the mean rank values neither in occlusal (P=0.12) nor in gingival (P=0.39) part of cavities.

  Conclusion: According to the results of this study, antimicrobial agents such as chlorhexidine 2%, sodium hypochloride 2.5% and hydrogen peroxide 3% can be used perior to 7th generation dentin bonding agent
(Optibond all in one, kerr) without much concern.