Academy of Dental Knowledge

Diamond burs are generally used for reducing tooth structures to prepare cavities for restorations or place crowns or porcelain veneers. Diamonds may also be used to smooth, refine, and polish composite or porcelain material.

Composites are tooth coloured restorative materials that are usually recommended for class III, IV and class I cavities with less or no occlusal stress and esthetics are important. Specially designed composites are used in almost 50% of class II restorations, although less durable in comparison to dental amalgam. Composites can be classified as microfilled, nanofilled, flowable, packable, all purpose and laboratory. Composites are used for provisional restorations and core build-ups and in fibre-reinforced posts.

You have read about the composition of dental composites in earlier class notes This article will speak about the properties.  Properties of Composites The important properties of the composites are as follows: Polymerisation shrinkage - should be low Water sorption - should be low Coefficient of thermal expansion - should be same as tooth Fracture resistance - should be high Wear resistance - should be high Radiopacity- should be high Bond strength to enamel & dentin - should be high Colour match to tooth structure - should be excellent Manipulation - should be easy Finishing and polishing - should be easy Few of the above mentioned properties may be important for anterior than  posteriors restorations and vice versa. The properties  of  microfilled and nanofilled composites are same while the microhybrid's differ from both of them.

Direct Esthetic Restorative Materials There are four types of direct esthetic restorative materials currently in use. They are: Composites Compomers Hybrid Ionomers Glass Ionomers Composites are dominating the materials used for direct esthetic restorations. Glass ionomers are primarily used for restorations of cervical eroded areas. Hybrid ionomers provide better esthetics than glass ionomers. Compomers provide improved handling and fluoride release when compared with composites.

Permlastic is a polysulfide, condensation-cured, elastomeric impression material in three viscosities P o l ysulfide  impression materials  are  flexible but  do  not have the major changes in dimensions during storage  like  agar and alginate. Furthermore, the polysulfide impression  is  much stronger and more resistant to tearing than agar or alginate. It  can  be electroformed and therefore metal dies or models, in addition to gypsum models,  can  be prepared.  

  Types, clinical features, Causes prevention & treatment Non-carious loss of tooth structure is a problem that is often found in senior citizens and is a cause of many complaints. It is not a new entity but has acquired more attention in recent time. Types of tooth wear Abrasion Attrition Erosion Demastication Abfraction