Physiochemical Properties of Experimental Nano-hybrid MTA.

Introduction:The development of new pulp capping agents has paved the way towards the preservation of pulp vitality, which is an important goal in restorative dentistry. This study sought to assess the calcium ion release, pH and setting of mineral trioxide aggregate (MTA) Angelus, an experimental formulation of nano-hybrid MTA containing nano-SiO2, nano-Al2O3 and nano-TiO2 and MTA Angelus plus nano-oxides. Methods:In this experimental study, five specimens from each material were placed in polypropylene tubes and immersed in a flask containing deionized distilled water. The amount of calcium ions released into the solution from each material was measured at 15 minutes, one hour and 24 hours using atomic absorption spectroscopy. The pH of the solutions was measured using a pH meter at the respective time points. Setting time was also assessed using a Gilmore needle. Data were analyzed using the repeated measures ANOVA. Results:The amount of released calcium ions was not significantly different among the groups (P=0.060). All materials were alkaline and the pH at 24 hours was significantly higher than the other two time points in all groups (P<0.001). The experimental group had the shortest and MTA Angelus had the longest setting time. All materials were alkaline and capable of releasing calcium. Addition of nanoparticles to MTA Angelus significantly decreased the setting time but had no effect on the release of calcium ions or pH. Abbreviations: mineral trioxide aggregate (MTA), vital pulp therapy (VPT).

Bleaching effect of ozone on pigmented teeth.

BACKGROUND: There have been numerous researches on ozone application in dentistry; yet the data regarding its whitening effect is very limited. The present study compares the bleaching effect of ozone with office bleaching. MATERIALS AND METHODS: In this experimental study, 15 maxillary premolar teeth were selected and sectioned mesio-distally and bucco-lingually. The sections were then placed in tea for 1 week according to the Sulieman method and were divided into three groups each comprised of 15 sections. The samples were bleached as followed; Group I: Bleached with 35% hydrogen peroxide in three intervals of 8 min each, Group II: Underwent ozone treatment using Ozotop unite for 4 min and Group III: Bleached with a combination of both methods. The color indices of the samples, i.e., (a) green-red pigment, (b) blue-yellow pigment, (L) brightness, (ΔE) overall color change, were evaluated pre- and post-bleaching utilizing a digital camera, Photoshop software and CIE lab index. The color changes of specimens then were calculated and analyzed through randomized analysis of variance and Tukey tests. P < 0.001 was considered to be significant. RESULTS: The color change (ΔE) in Group II was significantly lower than those in the two other groups (P < 0.001). There was no significant difference between the color change of Groups I and III (P = 0.639). In addition, the results of L, a and b brought forth a similar pattern to the findings obtained from ΔE. CONCLUSION: The hydrogen peroxide gel has a more powerful whitening effect than ozone; in addition, ozone has no synergistic effect when is used simultaneously with hydrogen peroxide.