Abstract
The design of cavity preparation for primary teeth including depth, width etc. affects the falling out, breakage of material, break kown of the tooth and sensation of pain caused by the pulp. With this in mind, a study using the finite element method was made to analyze the change and stress of the restorative materials and the tooth itself.
For the two dimensional finite element model for the primary teeth, the bucco-lingual section of the crown of the lower second primary molar was used as a standard. The cavity preparation was class 1 on the occulusal surface, width.0.9 mm and 1.5 mm depth 1.0 mm,1.5 mm and 2.0 mm. The cavity was prepared with a 330 carbide rounded angle bur. Restorative materials used were composite resin, amalgam and metal inlay. The displacement and stress figures were made. The analysis was done for displacement of each point and the relative stress in the principal area.
The following conclusions were obtained.
1. The deeper and wider the cavity preparation was, the lower was the displacement around the restoration. The metal inlay was the lowest in displacement.
2. The deeper the level of composite resin and amalgam, the more was displacement noticeable on the pulp. Conversely, the metal inlay was found to have a lower displacement at deeper levels.
3. Stress in the restoration was higher than in the control and stress was concentrated in the restoration. However stress in the rest of tooth was lower.
4. Stress directly under the restoration with composite resin and amalgam material was higher, but with the metal inlay it was found to be lower.
5. Stress in the pulp was so low that pain would not normally occur.
