Dental Restorative Materials Selection

Dental Restorative Materials Selection

Classify anterior restorative materials. Write in detail about step-by-step procedures for composite resins.
Answer:

Anterior restorative materials are:

• Composite resin
• Acrylic resin
• Glass ionomer cement
• Silicate cement
• Dental ceramic.

Step-by-Step Procedure for Composite Resin:

• Placement of rubber dam: Since composite resins are highly technique-sensitive contamination from blood, and saliva is avoided by the use of a rubber dam.
• Cavity preparation: Cavity is prepared and margins are beveled.
• Cleaning: The tooth is cleaned with mild abrasive
• Etching: Enamel at the cavity margin is acid-etched. Acid is rinsed and the area is dried thoroughly.
• Bonding agent: An enamel or dentin bonding agent is applied and polymerized. The cavity is now ready for the composite.
• Insertion of composite: Resins are manipulated with plastic or plastic-coated instruments.
• Metal instruments should be avoided as they may abrade and discolor the composite.
• Composites are tacky and stick to metal instruments. It is inserted into the cavity using a plastic instrument or a special syringe.
• Some manufacturers supply it in the form of a capsule which can be injected directly into the cavity with a special extruding gun.

Chemically Activated Composites:

The correct proportions of base and catalyst pastes are dispensed onto a mixing pad and combined by rapid speculation for 30 seconds. It is inserted while still plastic for better adaptation to cavity walls. Air inclusions can be avoided by swiping the material into one side of the cavity and filing the cavity from the bottom outward. The cavity is slightly overfilled. A matrix strip is used to apply pressure and avoid inhibition by air

Light Activated Composites:

The light-activated composites are single-component pastes and require no mixing. Since ambient light leads to the slow polymerization of composite resin it may lose its ability to flow. Therefore, some precautions to be observed when using light-activated materials are as follows:

• The paste is dispensed just before use.
• Avoid dispensing excessive quantities.
• The depth of cure is limited, so in deep cavities the restorations must be built up in increments, each increment being cured before inserting the next.
• Between cures, any excess material is protected by covering with a lightproof dark or orange-tinted cover
• The material hardens rapidly on exposure to the curing light. To ensure maximum polymerization a high-intensity
  light unit should be used.
• The light tip should be held as close as possible to the restoration.
• The exposure time should be not less than 40 to 60 seconds.
• The resin should be no greater than 2.0 to 2.5 mm thick. Darker shades require longer exposure times, as do resins that are cured through the enamel.
• Microfilmed resins also require a longer exposure.
• The high-intensity light can cause retinal damage if one looks at it directly. Avoiding looking at the light directly and use of protective eyeglasses is recommended.

Finishing and Polishing:

Finishing is best done after 24 hours during which time the polymerization is complete. However, if a subsequent appointment is not desired, finishing procedures can be started 15 minutes after curing. The initial contouring can be done with a knife or diamond stone. The final finishing is done with rubber-impregnated abrasives or a rubber cup with polishing pastes or aluminum oxide discs. The best fit is obtained when the composite is allowed to be set against a matrix or mylar strip.