R.Sathyanarayanan.

Esthetic dentistry

Esthetics in dentistry is most demanded nowadays, and there are various factors to be considered before starting an esthetic restoration. All clinical aspects of esthetics, the indications of the various procedures, the materials used and the limitations are discussed in detail in this section.

1. What is Metamerism?

It is the phenomenon that can cause two colour samples to appear as the same hue under one light source, but as unmatched hues under a different light source. It complicates the colour matching in restorations . So 3 light sources are preferred.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,29

2. What is Hue?

It is the name of the colour. In young teeth it is the same throughout the mouth and as age advances, it varies due to staining.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,28

3. What are the advantages of indirect veneering over direct veneering?

Indirect veneers are more esthetic and less operator sensitive and there is a possibility of veneering multiple teeth.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;615

4. What is a veneer?

A Veneer is a layer of tooth colored material that is applied to a tooth to restore localized or generalized defects and intrinsic discolorations. It is commonly indicated in malformed, discolored, abraded or eroded facial tooth surfaces. They can be partial or full veneers.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;615

5. What is the most common sequela of Internal bleaching?

External cervical resorption is the common sequela of internal bleaching techniques which is caused by hydrogen peroxide. The various reasons by which this occurs are: The hydrogen peroxide denatures the dentin and invokes a foreign body response in the gingival tissue. The dentinal tubules that are left patent may allow the passage of hydrogen peroxide to the periodontal membrane. Infiltration of the bleaching agents between the GP and the canal walls. Application of heat during treatment lowering of the PH in the periodontal membrane area by the mixture of hydrogen peroxide and sodium perborate.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;608. Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,259

6. What is Walking Bleach technique?

It is a non vital bleaching technique that uses a mixture of 30% hydrogen peroxide and sodium perborate which is placed in the pulp chamber for 3 -7 days and changed , till optimal tooth lightening is achieved.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;609

7. What is In office non- vital bleaching/ Thermocatalytic Non- vital bleaching?

35% hydrogen peroxide liquid is placed in the pulp chamber and the oxidation is accelerated by placement of a heating instrument into the pulp chamber or heated externally with a floodlight apparatus or a combination of the two. But when high heat is used, it may result in cervical resorption. So techniques like walking bleach technique which does not require heat are used.

8. What is Non-Vital bleaching?

Non- vital bleaching is done for teeth that have undergone root canal therapy. The discoloration may have occurred due to bleeding into the dentin from trauma, degradation of pulp tissue left in the chamber or staining from restorative materials and cements. It can be an in office non- vital bleaching technique or walking bleach technique.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;608

9. What is the procedure of home bleaching?

The bleaching agent is carried in a custom fabricated tray and held against the teeth . After insertion, excess material is wiped off from the soft tissue. The nightguard is not removed for drinking liquids or rinsing during treatment. It is removed only in the morning and rinsed under running water. Total treatment time may vary between 1-2 weeks. Only one arch is bleached at a time while the other arch serves as a comparison.

Ref:Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;611,612

10. What is urea peroxide?

10% carbamide peroxide is also known as urea peroxide which breaks down into 3% hydrogen peroxide and 7% urea. Thickeners like Carbopol are added to extend the oxidation. It is a safe and effective procedure for bleaching vital teeth.

Ref:Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,257.Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;611

11. What is home bleaching or Matrix bleaching?

Bleaching of vital teeth by patient self application of bleaching agents performed at home is called home bleaching or matrix bleaching,which uses 10% carbamide peroxide.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,257

12. What is Thermocatlytic technique in power bleaching?

35%hydrogen peroxide is used for the procedure either in the liquid form or in the gel form. In the Thermocatalytic technique, a heating element which is a spatula or a paddle shaped element, approximately of the size of a tooth, is placed on the tooth surface after applying 35% hydrogen peroxide. A lamp can heat the entire arch and the procedure is then called as Thermophotocatalytic technique. The application of heat accelerates the oxidizing reaction of hydrogen peroxide.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,256. Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;610

13. What is power bleaching?

It is an in-office bleaching procedure of the vital teeth which involves application of bleaching agents like 30-35% hydrogen peroxide in liquid or gel form. It is indicated for intrinsically discolored teeth from ageing, trauma or drug ingestion. The procedure is under the operator’s control, the soft tissues are protected and it allows a rapid bleaching.

14. What is bleaching?

The lightening of the colour of the tooth by applying a chemical agent to oxidize the organic pigmentation in the tooth is called as bleaching. They can be classified as vital and non vital bleaching and in- office and outside the office bleaching.

Ref: Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;608

15. What is the role of hydrochloric acid in the Microabrasion procedure?

Hydrochloric acid is a potent decalcification agent. It is used at a concentration of 18% and is easily available. It decalcifies both the tooth structure and the accompanying stains. Along with abrasives, it removes the stains and the affected enamel completely. It does not penetrate the pulpal tissue. It forms calcium and phosphorus salts which prevent its penetration and also there is a neutralization of the acid by these salts.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,254

16. What are the safety precautions taken when a Microabrasion procedure is done?

Protective glasses are worn by the patient, doctor and the assistant to prevent acid splash. Rubber gloves is worn by the patient and the auxillary personnel. Rubber dam application. Hydrochloric acid is never passed or held over the patient’s head. Application of sodium bicarbonate on the rubber dam to neutralize the acid, if splashed.

Ref: Kenneth W.Aschheim,Barry G.Dale,Esthetic Dentistry,Mosby publications,II edn,44

17. What is Microabrasion?

Microabrasion is a procedure by which superficial discolorations on the teeth are removed physically with the use of an acid and an abrasive. The acid causes surface dissolution of the enamel and the abrasive which is nothing but pumice removes the superficial stains and defects. It is mainly indicated for white spot lesions and mild brown fluorotic stains.

Ref: Theodore.M.Roberson,Harald.O.Heymann,Edward.J.SwiftJR.Sturdevant's Art and Science of Operative Dentistry.Mosby publications;2002;612,613

18. What is Mottling of enamel?

A very common surface stain in enamel is Mottling of enamel which causes the enamel to lose its transluscency and become opaque. The surface texture is soft and absorbs foreign material that discolors the enamel. It is caused by an excess of fluoride in drinking water during the early periods when the enamel was being formed.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 89

19. How is internal staining of teeth manifested clinically?

Internal staining is manifested in 2 forms.

• Dentinogenesis imperfecta, a congenital defect in tooth formation where the dentin is brown

• Tetracycline staining, where tetracycline is administered during tooth forming stages

The enamel and dentin formed in these conditions are sound and intact but the tooth acquires an unsightly dark grey shade.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 90