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.

Photograph showing before and and after teeth whitening procedure.

Tooth whitening is done to correct the discoloration of a tooth. When we talk about discoloration of a tooth, we mean to say that the color of a tooth has changed from its normal white color to light yellow, yellow, light brown to dark brown or from light grey to dark grey or to complete black. The discolouration may be of one tooth or all the teeth may be discoloured. Discoloration of a tooth is caused by several factors. It may be due to deposition of external stains over the surfaces of a tooth or it may be because of the internal position of certain chemicals into the teeth structure at molecular level during the period when teeth were being formed in the mother’s womb.

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:

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

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.

Design of a Custom Tray for Final Impression for Complete Denture

The custom trays also known as special trays are fabricated so that the final impression of the patient’s edentulous mouth can be taken accurately with proper border extension. The selective pressure technique helps in making the impression in such a way that when the newly fabricated dentures are worn by a patient, they exert pressure only on those areas of the mouth that can withstand the masticatory load. The selective pressure technique of impression making spares the non-pressure bearing area of the edentulous jaw and thus eliminate the possibility of trauma resulting in pain and ulceration in the mucosa. The special tray for selective pressure technique is made on the primary cast that has been prepared by pouring the impression made in alginate or impression compound. The impression taken in impression compound records the mucosa in a compressed state whereas the impression taken with alginate records the mucosa in a non-compressed state. From these two opposite states of mucosa record, a dentist proceeds to prepare a special tray that is used to make an impression with selective pressure. We will learn here as to how to make a special tray on a cast that has been made from impression compound.

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

National Board of Examinations in Medical Sciences have declared the dates for NEET MDS, NEET PG & other exams. Candidates can check the exam dates below.

NEET-MDS 2023: January 8, 2023
DNB/DrNB Final Practical Examination – June 2022: October/November 2022
Foreign Medical Graduate Examination (FMGE) December 2022, Foreign Dental Screening Test (FDST) 2022: December 4, 2022
Formative Assessment Test (FAT) 2022: December 10, 2022
DNB/DrNB Final Theory Examination – December 2022: December 21, 22, 23 and 24, 2022
Fellowship Entrance Test (FET) 2022: January 20, 2023
FNB Exit Examination 2022: February/March 2023
DNB/DrNB Final Practical Examination – December 2022: Feb/March/April 2023
NEET-PG 2023: March 5, 2023

Distribution of subject wise questions in NEET MDS examination.

The candidates are being advised to check the details and the updated information at the NBE website - https://natboard.edu.in/ as the dates mentioned are tentative and subject to approval and confirmation.