Fracture toughness of resin composites under different modes and media: review of articles

This article aims to review various modes of fracture toughness of resin composites. Also, this study intends to review the papers on the fracture mode, namely "fractography", under scanning electron microscopy finding fracture initiation site, and the effect of filler content on the fracture toughness of resin composites. It will also review the effect of aging on the fracture toughness of resin composites in different media, mainly distilled water, and acidic environment. In the review performed on fracture toughness of resin composites we used "fracture toughness [KIc]", aging AND fracture toughness, AND fractography" of resin composites as the search strategy. The outcome of the review revealed that most of the studies investigated fracture toughness of resin composites under Mode I and less under mode II. However, some others looked at the fracture toughness of dental resin composites under mixed-mode loading conditions. It was also found that fracture toughness studies performed on the same types of resin composites resulted in different values of KIc. The differences were related to the method of performance that requires different specimen geometries

Effect of a home bleaching agent on the fracture toughness of resin composites, using short rod design

Statement of Problem: Resin composites are brittle materials and their major shortcomings are manifested in their sensitivity to flaws and defects. Although various mechanical properties of resin composites have been described, few studies are available on assessing the effect of bleaching agents on resin composites using the short rod design

Purpose: To place various resin composites into distilled water at 37°C for 21 days and determine the effect of immersion time in distilled water, with and without exposure to 10% carbamide peroxide by employing short rod design fracture toughness test

Materials and Method: Specimens were prepared from three resin composites; Rok [SDI], Esthet [Dentsply], and Estelite [Tokuyama]. For each material, a total of 24 disc-shaped specimens were prepared using a custom-made mould. Specimens were randomly divided into 3 groups of 8 and conditioned in 37°C distilled water for either 24 hours, or 21 days. 21 day specimens were tested both with and without applying bleaching agent; Polanight [SDI]. Study group specimens were bleached for 21 days, 2 hours a day. The specimens were loaded using a universal testing machine with a crosshead speed of 0.5 mm per minute. The maximum load at specimen failure was recorded and the K[Ic] [MPa. M [0.5]] was calculated

Results: Statistical analysis using two-way ANOVA showed a significant relationship between material and time [p< 0.05].Tukey's test showed that after 24 h of immersion in distilled water, Rok revealed the highest K[Ic] followed by Esthet and Estelite. The bleaching agent significantly improved the fracture toughness values of Esthet while it decreased that of Estelite

Conclusion: The fracture toughness of the resin composites was affected by the bleaching agent and distilled water. In comparison with Rok and Estelite, fracture toughness of Esthet was increased due to aging and application of bleaching agent

Comparing the effect of phenytoin syrup and triamcinolone acetonide ointment on aphthous ulcers in patients with Behcet's syndrome

Recurrent aphthous stomatitis [RAS] appears to be the most common type of oral ulcers. The lesion is usually self limited but its painful presentation results in some difficulties. Therefore, an efficient therapeutic strategy is required and currently existing therapies seem to be inadequate because of its unclear etiology. Here the therapeutic effect of triamcinolone acetonide ointment as a relatively expensive medication has been compared with phenytoin syrup on aphthous ulcers in patients with Behcet's syndrome. Thirty out of 60 our patients with Behcet's syndrome were randomly treated by phenytoin syrup and the remaining were advised to use 0.1% triamcinolone acetonide ointment. After a week, they were visited again to determine the status of aphthous ulcers. Positive response in the triamcinolone acetonide group and phenytoin group was 86.7% and 53.3%, respectively. The effectiveness of triamcinolone acetonide ointment was more than phenytoin on aphthous ulcers in patients with Behcet's syndrome

investigation of Frenkel's exercises effection on ataxia, balance, activity of daily living and depression in patients with multiple sclerosis

Multiple sclerosis [MS] is the most common progressive neurological disorder in the young adults. One of the areas that are affected in MS is the cerebellum. Ddisorders in this structure leadss to ataxia, imbalance, and so on, that can decrease patient's quality of life. Exercise therapy is an effective method to decrease functional disorders in MS patients. This study shows the effectiveness of Frenkel's exercises in improvement of conditions in MS patients. This is was a double-blinded, perospective and quinsy-experimental study that was done in Isfahan, during 1385-786. In this experiment, 22 MS patients with cerebellar disorder. [mean age 33.36 years, mean height 64.14 cm, and mean weight 61.95 kg], was learned Frenkel's exercises alternatively in 10 sessions. Evaluation was done before and after the treatment. In order to study ataxia we used ataxia rating scale, Berg balance scale for to assess balance, Barthel index, for to study activity of daily living [ADL], and questionnaire of beck for to judge depression. We used SPSS soft ware. For statistic studying and analyzing of obtained results and for comparing the conditions of patients in different stages, paired-t-test was used. The findings of this current study showed a meaningful difference of ataxia [P<0.05] Balance [p<0.05] and depression [p<0.05] evaluation between before and after the treatment. The obtained result showed that doing Frenkel's exercises, Continuously leads to improve the ataxia, blance, ADL and depression in patients with MS.