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Thin-walled roots that had the smear layer removed with lactic acid and that were then lined with composite resin had a higher fracture resistance.

Please cite this article as: S.A. Bahannan, Effects of different bleaching agent concentrations on surface roughness and microhardness of esthetic restorative materials, (2015), doi: http://dx. ABSTRACT Objectives:The study assessed the changes in surface roughness and microhardness of three esthetic restorative materials after bleaching with 10%, 20% and 35% carbamide peroxide (CP) .Methods: Standardized cylindrical specimens (n=210) of 3 esthetic materials (nano composite resin (NC), resin modified glass ionomer (GI), feldspathic porcelain (FP) were fabricated (n=70).They were divided into 3 groups (n=20) and a control group (n=10). Each group was bleached with different concentration of CP. The specimens of group 1 and 2 (10% CP and 20% CP) were immersed in the bleaching gels for 6 hours daily, while group 3 ( 35% CP) was immersed for 30 minutes weekly. The control group was stored in artificial saliva. After 21 days, the morphological changes of the specimens were investigated with surface texture analyzer, while the hardness was assessed by performing superficial microhardness analysis. The data was analyzed with one-way ANOVA, and Scheffe test at α=0.05.Results: No significant differences in roughness average (Ra) were recorded among the control group and 10% CP bleached groups of all tested restorative materials (NC (p=0.1495 ), GI (p=0.0761 ), FP (p=0.2848 ) . However, there were significant differences in Ra among control group, 20% CP, and 35% CP(p<0.05). There were no significant differences in the microhardness of feldspathic porcelain (10% (p=0.0786 ), 20% (p=0.1041 ),and 35% (p=0.2066). While nano composite resin and resin modified glass ionomer specimens were significantly affected by concentration of 20% and 35% CP (p<0.05). Conclusion:The effect of bleaching depends on the concentration of CP. The higher surface roughness was produced by 35% CP. Bleaching with different concentrations did not reduce the microhardness of the feldspathic porcelain. However, microhardness of nano composite resin and resin modified glass ionomer specimens were affected by 20% CP and 35% CP .

The purpose of this study was to assess the prevalence and associated factors of dental caries and periodontal diseases among 14–19-year-old schoolchildren with limited access to dental care services. A cross sectional study design was conducted during field visits to seven governmental schools in Al-Khomrah district, South Jeddah, over the period from September 2015 to May 2016. Clinical examinations and administered questionnaires were carried out in mobile dental clinics. The dentists carried out oral examinations using the dental caries index (DMFT), the simplified oral hygiene index (OHI-S), and the community periodontal index for treatment needs (CPITN). Statistical analyses were performed using SPSS 20. A total of 734 schoolchildren were examined. The prevalence of decayed teeth was 79.7% and was significantly higher among boys (88.9%) than girls (69.0%). About 11% of students had missing teeth, with a significantly higher figure among females than males (15.9% versus 7.3%); 19.8% of students had filled teeth. Moreover, a DMFT of seven or more was significantly more prevalent among males (43.3%) than females (26.8%), while the percentage of females with sound teeth was significantly higher than for males (20.4% and 9.6% respectively). The CPITN revealed 0, 1 and 2 scores among 14.6%, 78.2%, and 41.6% respectively. Males had a significantly higher percentage of healthy periodontal condition (23.8%) than females (3.8%). Dental caries prevalence was moderate to high, calculus and gingival bleeding were widespread among schoolchildren, and were more prevalent among students with low socioeconomic status.