Shear bond strength of the repair composite resin to zirconia ceramic by different surface treatments

The purpose of this study is the evaluation of the amount of surface roughness [Ra] of Zirconia Ceramic following different surface treatments as well as the assessment of its shear bond strength to composite resin. 40 sintered zirconia ceramic block samples were randomly divided in 4 groups of 10 and underwent the following surface treatments: a] Control group without treatment b] Air abrasion with Al2O3 particles [50um] c] Er:YAG laser with 2W power for 10s d] Nd:YAG laser with 1.5W power for 2min Then the mean surface roughness [Ra] was evaluated by profilometer. In the next step, Alloy primer was used on a section of 9mm[2]on the samples following the manufacturer's instructions. After that Clearfil AP-X composite resin in cylinder shape with an internal diameter and height of 3mm were cured on the sections mentioned. At the end, all samples were tested to assess the shear bond strength by the Universal Testing Machine at a speed of 0.5mm/min until fracture occurred. The mean shear bond strengths were calculated and statistically analyzed by One Way ANOVA. ANOVA analysis showed that roughness [Ra] was significantly different between the groups [P

Comparison of polymerization shrinkage in methacrylate and silorane-based composites cured by different LEDs

Polymerization shrinkage in Methacrylate-based composite is one of the most important factors in composite restorations failure. Silorane-based composite is introduced to compensate this drawback and claimed to have low shrinkage. The aim of this study was to evaluate the polymerization shrinkage of these two composites. In this experimental study, 5 disk shape samples for each resin composites were placed in the centre of metallic ring bonded to microscopic glass slab. Top surface of ring was covered by a glass cover slip. Glass slab and sample were placed on a special LVDT holder in order to light cure from bottom surface and to measure the polymerization shrinkage. In this study, Deflecting Disk method and LVDT [linear variable differential transducer] was used for dimensional change measurement of resin composites. In this study, two LED curing units were used for composite polymerization. The mean of polymerization shrinkage in Z250 cured with LED and High Power LED was 11 15 +/- 0.08microm and 11.51 +/- 0.17microm, respectively [P=0.094], and in P90 cured with LED and High Power LED was 1.08 +/- 0.06microm and 1.16 +/- 0.12microm, respectively [P=0.019]. Silorane-based composite [P90] showed significantly less polymerization shrinkage than that of methacrylate-based composite [Z250]. For the two types of composite, there was no significant difference between the two curing units in polymerization shrinkage

[Effects of leached components from a hybrid resin composite on the reproductive system of male mice]

In the present animal study, twenty adult Syrian male mice were divided into two groups of 10 mice each. In the test group, components which leached from samples made from Filtek Z250 resin composite into 75% ethanol were daily administered to the mice for 28 days. In the control group, the procedure was repeated in the same way as the test group but without placing composite samples in the solution. Then, the body weight, weights of paired testes, Gonado Somatic Index, sperm viability, sperm motility, epididymal sperm reserve and daily sperm production were recorded. Four male mice in each group were mated with untreated female mice for 10 days. After that, the number of pregnant females and number of infants were recorded. The data were analyzed using repeated measures ANOVA, Chi-square test and t-test. There was a significant reduction in the sperm viability and sperm motility of male mice in the test group compared to the control group [P=0.001]. There was no any significant differences in other parameters between two groups [P>0.05]. This study showed that the leached components from resin composites cannot cause infertility but they could potentially cause some adverse effects on the reproductive system of male mice.