This study compared dimensional stability and adaptability of two resin composites [Filtek P90 and Filtek Supreme XT] after storage in different pH media.Methods: For dimensional stability, cylindrical specimens were prepared either from Filtek P90 or Filtek Supreme XT. Specimens' dimensions were measured before and after storage in neutral [pH7] or acidic saliva [pH 3.6] for 1 week, 1month or 3 months. Volumetric changes were calculated. For adaptability, 80 class V cavities were made in sound human teeth. The cavities were restored with Filtek P90 or Filtek supreme XT. The adaptation was evaluated using stereomicroscope; before and after storage in acidic or neutral saliva for 1 week,1 or 3 months. Results:Filtek P90 showed significantly higher contraction compared to Filtek Supreme XT only after 3 months storage. After 1 week or 1 month, the difference in volumetric changes between two material was statistically non-significant. The pH of storage media showed non-significant effect on volumetric changes of both composites. For adaptability to cavity walls in acidic saliva, no statistically significant difference was found between gap dimensions at tooth restoration interface for both Filtek P90 and Filtek Supreme XT. However, in neutral saliva, Filtek P90 showed statistically significantly higher mean gap dimensions than Filtek Supreme XT through all time storage. Conclusions:Silorane-based resin composite undergoes volumetric changes comparable to nanohybrid resin composite except on long term storage where it revealed contraction. The adaptation of silorane based composite was worse compared to that of nanohybrid composite in neutral pH media. KEYWORD; silorane based resin composite; volumetric changes; adaptation (1488)Rehab MA Hamed, et al.
Aim:The aim is to evaluate the influence of resin solvent on Vickers microhardness, flexural strength, and flexural modulus of a resin composite in order to test the ability of resin solvent to soften or weaken resin composite during replacement of failed restoration. Materials and methods: Fifty specimens were prepared from Tetric N-Ceram; forty used for flexural strength and elastic modulus tests and ten used for microhardness test. For flexural strength; they were divided into four groups of ten specimens each; in first group; specimens were not subjected to resin solvent (control), in second, third and fourth groups; specimens were subjected to resin solvent for 1, 3, and 5 minutes respectively. For microhardness, specimens were examined before after application of resin solvent for 1, 3, and 5 minutes with a total of forty readings. Collected data were statistically analyzed. Results: Resin solvent was found to reduce significantly the flexure strength of Tetric N-Ceram compared to the control group. Differences in flexure strength between 1, 3, and 5 minutes applications were statistically nonsignificant. For elastic modulus and microhardness, the influence of resin solvent on resin composite was statistically nonsignificant. Conclusion:Resin solvent weakens the flexural strength of resin composite but did not affect its microhardness or elastic modulus. Increasing the time of application from 1, 3, and 5 minutes did not further reduce the flexural strength. Clinical significance: Resin solvent had shown promising potentials to reduce the strength and hence facilitate removal of failed composite restoration during replacement.
Aim:The aim of the study was to ascertain the influence of a resin remover on color and surface roughness of two resin composites. Materials and methods: Disc-shaped specimens were fabricated from either a Te-Econom plus microhybrid or a Tetric EvoCeram nanocomposite. The color and surface roughness of the specimens were measured before and after treatment, with a resin remover for 3, 5, and 8 minutes. The color was measured using a reflective spectrophotometer according to the CIE L *a *b * color space measurements. Surface roughness was evaluated using optical profilometry. Results were statistically analyzed using Student's t test, ANOVA, Tukey's post hoc , and Pearson's correlation tests. Results: The resin remover induced a statistically significant color change of both resin composites, which increased with increasing the time of immersion to 8 minutes. The color change of Tetric EvoCeram was higher than that of the Te-Econom Plus. Surface roughness change was more pronounced with Tetric EvoCeram. No correlation was found between changes in color and surface roughness. Conclusion:Resin solvent changed the color of microhybrid and nanocomposite. Increasing the immersion time to 8 minutes increased the color change. The type of composite influenced the changes in color and surface roughness. Clinical significance: Resin solvent had potentials to stain resin composites, which could be helpful in its identification from tooth structure during removal of failed resin composite restorations.
Aim: This invitro study assessed the effect of resin remover used for removal of resin based endodontic fillings on the microtensile bond strength of resin composite to coronal dentin Materials and methods; Freshly extracted sound human molars, that were extracted for periodontal reasons not correlated with this study, were disinfected and prepared for microtensile bond strength testing. The occlusal surfaces were ground to expose coronal dentin. In half of the specimens, dentin was treated with resin remover for eight minutes. In the other half, dentin was not treated to serve as control. Tetric N ceram composite blocks were bonded to occlusal surfaces of all specimens using total etch adhesive system; Tetric N bond universal. After storage for 24 hours, specimens were sectioned into beams to provide a total of 40 beams; 20 beams for non-treated dentin group and the other 20 beam for dentin group treated with resin remover. Beam were tested for microtensile bond strength using universal testing machine and failure mode was recorded. The tooth/restoration interface was examined using scanning electron microscope.Results: resin composite bonded to dentin pretreated using resin remover revealed a statistically higher bond strength than that bonded to untreated dentin. Mixed adhesive cohesive failures and cohesive failure in composite was predominant in resin remover dentin pre-treated groups compared to control group that revealed mostly adhesive failure or cohesive failures in dentin. Scanning Electron microexamination showed more penetration of resin tags and more obturation of dentinal tubules in specimens treated with resin remover.Conclusion; usage of resin remover showed promising results considering bonding to coronal dentin which requires further research in this field.
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