Dental Burs

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: Composition

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.

Composites: Properties

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:

1. Polymerisation shrinkage - should be low
2. Water sorption - should be low
3. Coefficient of thermal expansion - should be same as tooth
4. Fracture resistance - should be high
5. Wear resistance - should be high
6. Radiopacity- should be high
7. Bond strength to enamel & dentin - should be high
8. Colour match to tooth structure - should be excellent
9. Manipulation - should be easy
10. 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:

1. Composites
2. Compomers
3. Hybrid Ionomers
4. 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.

Polysulfide Impression Materials

Permlastic is a polysulfide, condensation-cured, elastomeric impression material in three viscosities

Polysulfide 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. 

Non-carious loss of tooth structure

 

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

1. Abrasion
2. Attrition
3. Erosion
4. Demastication
5. Abfraction