Various different resin composite restorative materials are continuously being introduced to the market. Their composition and mechanical properties, largely, influence their clinical performance.Materials and methods : Three resin composite restorative materials (Tetric N -Ceram, ACTIVA, and the hybrid resin composite Te -Econom Plus ) were investigated regarding fracture toughness and micro-hardness. Thirty disk shaped samples (n = 10 / group), were prepared, light cured and finished and polished. The surface micro-hardness was assessed using a Digital Display Vickers Micro-hardness Tester. Both fracture toughness and micro-hardness were assessed using the indentation technique with heavy loading.Results : Regarding both fracture toughness and micro-hardness, the highest means plus or minus SD were recorded by Tetric N -Ceram, followed by Te -Econom Plus, while ACTIVA demonstrated the least.
In this study a comparison was set between the mean shear bond strength of resin composites to dentin related to maxillary teeth and that related to mandibular ones .Therefore the direction of application of an adhesive was being investigated .80 noncarious extracted human first molar (maxillary and mandibular ) were included in this study . They were divided into two groups of 40 to represent either the maxillary teeth or the mandibular ones. Each group was further subdivided into two subgroups of 20 to represent an immediate investigation or an investigation after one month. A universal bond adhesive ( BISCO -USA ), and the resin composite ( 3M FILTEK Z 250 XT ) were used in this study. The results showed that the mean shear bond strength of resin composite to dentin related to mandibular teeth was statistically significantly higher than that related to maxillary teeth. Also, the results showed that the incubation time ( one month ) had no significant effect on the mean shear bond strengths of all samples.
Diabetes mellitus is one of the serious diseases with more prevalence in middle East and North Africa. The poor metabolic control associated with diabetes mellitus results in reduced salivary flow rates with remarkable increase in the incidence of dental caries. The aim of this study was to provide a new clinical approach for diabetic patients, during the initial periods of poor metabolic control, in order to decrease the incidence of demineralization and establishment of carious lesions. One hundred diagnosed type 2 diabetic patients were included in this study. They were divided into two groups of 50.Group B was the control group while group A represented the group of patients that underwent the clinical management using Pilocarpine and an insitu gel of carbapol and chitosan that acted as a local drug delivery system. DMFT scores , salivary flow rates and salivary pH measurements were obtained. The results showed that group A patients were significantly superior to those of group B in terms of the DMFT scores , salivary flow rates and salivary pH measurements.
Resin composites are very successful and widely used esthetic restorative materials. However, their color stability is a challenging issue that has to be investigated and assessed. In this study we assessed the color stability of three different types of resin composites ; a nano-filled resin composite, a nano-hybrid one and a micro-hybrid one using Reflective Spectrophotometry. 90 specimens were used . They were divided into three groups of 30 to represent the three types of composites ; then each group were further subdivided into three subgroups to represent the three types of immersion solutions. The results showed the nanohybrid composite to undergo the least color changes in comparison to the other two resin composites with different immersion solutions.
There has always been a continuous search for an ideal esthetic restorative material that can restore and replace the natural tooth structure and maintain mechanical and esthetic properties. Materials and methods : in this study three recent esthetic restorative materials [a CAD -CAM resin nano ceramic (Lava Ultimate); a nano hybrid bulk fill resin composite (Aura) and a Universal nano hybrid ORMOCER]; were investigated in terms of surface roughness in relation to different pH incubation solutions.
Results :The CAD -CAM resin nano ceramic Lava Ultimate and the bulk fill nanohybrid resin composite, approximately, showed close values of average surface roughness and both materials were statistically significantly superior to the Universal nano hybrid ORMOCER regarding the resistance to surface roughness in respect to all incubation solutions. Except for the CAD -CAM resin nano ceramic and regarding the other two materials; the acidic immersion solution produced significant changes in surface roughness.
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