shear bond strength of porcelain laminate to prepared and unprepared anterior teeth

Statement of the Problem: Porcelain laminate veneer is an esthetic restoration used as an alternative to full veneer crowns and requires minimal tooth preparation. In restoration with porcelain laminate veneers, both the longevity of the laminate and conservation of the sound tooth structure are imperative

Purpose: The present study aimed to investigate the shear bond strength of porcelain laminates to prepared- and unprepared- anterior teeth in order to compare their longevity and success rate

Materials and Method: Thirty extracted maxillary central incisors were randomly divided into 3 groups regarding their preparation methods. The preparation methods were full-preparation in group A, full-preparation and finishing with fine diamond bur in group B, and no-preparation, only grinding with diamond bur in group C. After conditioning the teeth, ceramic veneers [IP S e.max] were silanated and then cemented with DuoLink luting cement. The shear bond strength was measured for each group and failure mode was determined by stereomicroscopic examination

Results: Group C exhibited the highest shear bond strength. The shear bond strength was significantly different between groups C and B [p< 0.05]. However, the difference between group A and C was insignificant, as was the difference between group A and B [p> 0.05]. Adhesion failure mode was found to be more common than the cohesive mode

Conclusion: Regarding the shear bond strength of unprepared anterior teeth to porcelain laminate veneers yielded by this study, no-preparation veneers might be used when the enamel is affected by wearing, trauma, or abrasion. It can also be used in patients who refuse the treatments which involve tooth reduction and preparation

Flexural strength comparison of silorane- and methacrylate-based composites with pre-impregnated glass fiber

Statement of the Problem: Sufficient adhesion between silorane/methacrylate-based composites and methacrylate impregnated glass fiber increases the benefits of fibers and enhances the mechanical and clinical performance of both composites

Purpose: The aim of this study was to evaluate the compatibility of silorane and methacrylate-based composites with pre-impregnated glass fiber by using flexural strength [FS] test

Materials and Method: A total of 60 bar specimens were prepared in a split mold [25×2×2 mm] in 6 groups [n=10]. In groups 1 and 4 [control], silorane-based [Filtek P90] and nanohybrid [Filtek Z350] composites were placed into the mold and photopolymerized with a high-intensity curing unit. In groups 2 and 5, pre-impregnated glass fiber was first placed into the mold and after two minutes of curing, the mold was filled with respective composites. Prior to filling the mold in groups 3 and 6, an intermediate adhesive layer was applied to the glass fiber. The specimens were stored in distilled water for 24 hours and then their flexural strength was measured by 3 point bending test, using universal testing machine at the crosshead speed of 1 mm/min. Two-way ANOVA and post-hoc test were used for analyzing the data [p< 0.05]

Results: A significant difference was observed between the groups [p< 0.05]. The highest FS was registered for combination of Z350 composite, impregnated glass fiber, and application of intermediate adhesive layer .The lowest FS was obtained in Filtek P90 alone. Cohesive failure in composite was the predominant failure in all groups, except group 5 in which adhesive failure between the composite and fiber was exclusively observed

Conclusion: Significant improvement in FS was achieved for both composites with glass fiber. Additional application of intermediate adhesive layer before composite build up seems to increase FS. Nanohybrid composite showed higher FS than silorane-based composite

Povidone-iodine and bleomycin in the management of malignant pleural effusion

Malignant pleural effusion is a common complication in certain malignancies. Pleurodesis is the best option most of the time. The purpose of this study was to compare the choice of belomycin with povidone-iodine, which is not only determined by the efficacy of the agent but also by its cost, accessibility, safety, ease of administration and the number of administrations to achieve a complete response. We performed a randomized clinical trial on 39 patients presenting with symptomatic malignant pleural effusion. Patients were selected and randomly assigned to undergo chemical pleurodesis with either bleomycin or povidone-iodine. Primary characteristics of patients were assessed and graded before and after treatment concerning pain, dyspnea, and chest radiographs. A complete response was obtained in 79% of belomycin group and 75% of povidone-iodine group which was not statistically significant. Patients on belomycin treatment had a significantly lower score for dyspnea in one month follow up. This was significant after controlling for age, pain score and dyspnea score after drainage, using general linear model. Due to similar effect and significant cost advantage between bleomycin and povidone-iodine, we conclude that povidoneiodine is the agent of choice when utilizing pleurodesis for control of symptomatic malignant pleural effusions

[In vitro comparison of the shear bond strength of "etch and rinse" vs "self-etch" bonding systems on dentin after "nonvital tooth bleaching"]

Since bleaching causes changes on dental tissue and affects adhesive bond strengths, it is useful to recognize bonding systems which provide higher bond strengths on the dentin after bleaching. Forty eight human sound premolars were selected and sectioned 5mm below the CEJ. In order to do the bleaching process, the access cavity preparation was done and after the excavation of pulp tissue, and placement of the hybrid glass ionomer base at the apex, the teeth were bleached using the 35% hydrogen peroxide for 4 times. The teeth were then embedded in a self-cured acrylic resin and polished to obtain a flat dentin surface. The teeth were assigned into 4 groups according to the adhesive system used [n=12]: group 1: Single Bond [SB], group 2: Prime and Bond NT [P and B], group 3: Clearfil SE Bond [CSE] and group 4: Opti Bond [All in one] [OB]. The adhesive systems were used according to the manufacturer's instructions and a cylinder of composite resin Z100 was overlied. The teeth were thermocycled and the shear bond strength tests were performed in a universal testing machine with cross head speed of 1mm/min. CSE had the highest bond strength [15.18 MPa] and SB had the lowest one [8.10 MPa]. One Way ANOVA and independent sample t-test showed that the difference in bond strength values among the different types or generations of bondings was statistically significant except for the SB and P and B systems [P<0.05]. Within the limitations of this study, it is concluded that two step "self-etch" adhesives [CSE] are preferred to use for the teeth undergoing "Non vital tooth bleaching" with 35% hydrogen peroxide than the one step "self-etch" adhesives [OB] or two step "etch and rinse" adhesives [SB, P and B]

prevalence of dental caries in 5-18-year-old insulin-dependent diabetics of Fars Province, southern Iran

The association of dental caries and diabetes mellitus has not received enough attention, in spite of the fact that both diseases are associated with the ingestion of dietary carbohydrates. This study was undertaken in Fars Province, southern Iran, to determine the prevalence rates of dental caries in a group of metabolically well-controlled patients with type I diabetes mellitus and in a control group. Fifty patients [22 boys and 28 girls] with type I diabetes mellitus under follow-up of the Endocrinology and Metabolism Research Center of Shiraz University of Medical Sciences, with a mean +/- SD age of 11.72 +/- 3.36 years and mean +/- SD fasting blood sugar of 235.74 +/- 103.61 mg/dL, entered this study. A similar study was conducted to determine the prevalence of dental caries in 12-year-old school children in Shiraz, Iran who served as the control group. After completing a questionnaire, the patients were examined separately by two dentists. Before the clinical examination, bitewing radiographies were performed. Student-s t- and Chi-square tests were used for statistical analysis in relation to sex, age of onset of diabetes mellitus, socioeconomic and nutritional status, family history of diabetes mellitus, and orohygiene status. The mean +/- SD DMFT for diabetic children was 9.64 +/- 4.64 [decayed = 8.12 +/- 3.90, missing = 0.62 +/- 1.34, and filling = 0.90 +/- 2.10]. The lower permanent first molars were the most frequency decayed and the incisors were the healthiest teeth. DMFT score and the frequency of decayed teeth were higher in boys than in girls. However, the rate of filling and missing teeth were higher in girls. DMFT and the number of decayed teeth were higher in patients with poor oral hygiene. The number of healthy first permanent molars was much higher in the mixed dentition groups than in those with permanent teeth. A direct correlation was found between the health status of the first permanent molar tooth and having type I diabetes mellitus. Oral hygiene was somewhat poorer in diabetic patients than in the control group. Regular dental check-ups for preventive measures such as fluoride therapy, fissure sealant, regular medical follow-ups for proper control of metabolic abnormalities to decrease occurrence of xerostomia, omission of cariogenic substances from dietary regimen, fluoridation of drinking water, and individual and group education of diabetic patients regarding proper dental hygiene are recommended