Comparative study of microleakage between nano and hybrid composite ( an in vitro study)

The aim : This study aims to evaluate and compare the microleakage between nano and hybrid composite. Materials and Methods : the sample consisted of forty extracted premolars for orthodontics purposes , class v cavities were prepared with a specific dimensions on the buccal surface. The sample divided into two groups ; group A restored by nanocomposite ( Z350) , group B restored by hybrid composite ( Z250) , after that, the samples were placed in the incubator with thermo cycling for a month ,The samples were then immersed in 0.5 % methelyne blue dye for 24 hours , each tooth was mesial-distal sectioned vertically , finally, of all samples was studied using stereomicroscope to evaluated the microleakage . Results : there was no statistical significant difference between the nano and hybrid composite according to microleakage.

Comparative study for mechanical properties (wear resistance) of direct posterior restorative composite (hybrid and nanoceramic composite)

Introduction :The demand for posterior aesthetic restorations has dramatically increased in recent years. Several new materials have been developed with improved aesthetic, adhesive and mechanical properties. Theoretically, nano-structured dental resin omposites are purported to have increased wear and hardness resistance compared with hybrid composites and may favor the achievement of restoratives with better long-term performance. Aim: The wear resistance of different types of resin composites were evaluated in the in vitro study. Material and methods :Two nanohybrid restorative composites -Tetric®EvoCeram (Ivoclar-Vivadent) and CeramXTM(Dentsply) - were compared with a microhybrid material - Tetric®Ceram (Ivoclar-Vivadent) and hybrid material Spectrom (Dentsply) . wear resistance : fifteen specimens (3x3 mm) of each material were subjected to wear tests . The data were analyzed by 1-way ANOVA(<=0.5). Results : The Tetric®EvoCeram composite resin exhibited significantly less wear than the CeramX and Tetric®Ceram material . Conclusions :In terms of wear resistance, nano-structured composites may perform either similarly or comparatively better than a microfilled and hyprid composite . nanohybrid restorative composites can thus be considered as a good restorative material.