INVESTIGATION OF STRESS-STRAIN STATE OF "RESTORATION & TOOTH" SYSTEM IN WEDGE-SHAPED DEFECTS BY COMPUTED MODELING METHOD.

OBJECTIVE

The aim of this research is to study the influence of size and location of wedge-shaped defects of teeth on stress and strain state of restorative material on the basis of biomechanical analysis.

PATIENTS AND METHODS

Materials and methods: Biomechanical analysis of the stress-strain state was performed on a jaw bone fragment with canine and premolar inclusion.

RESULTS

Results: Tangential stress increase both in the adhesive layer and in restorative material with depth and width (medial-distal size) of restored wedge-shaped defects of teeth,.The most unfavorable loading on a tooth is a joint action of vertical and horizontal loading in lingual- vestibular or vestibular-lingual direction, depending on localization of the restored wedge-shaped defects of teeth. The formation of retention grooves in wedge-shaped defects of teeth reduces the value of the maximum tangential stress in the adhesive layer of restorative material to 25% and extends the longevity of restorations.

CONCLUSION

Conclusions: The difference in maximal values of tangential stress increases in adhesive layer of restorative material with or without retention grooves with increasing depth of defect. Thus, it is advisable to form retention grooves in cases of wedge-shaped teeth defects that exceed 1.5 mm. In case of restoration of subgingival wedge-shaped defects of teeth of small height it is recommended to create one retention groove on the gingival or incisal planes of a carious cavity due to significant inconveniences, and sometimes impossibility of formation of traditionally located retention grooves.