[Occlusal contact force and stress analysis of molars with vertical root split].

OBJECTIVE

To study the induction of vertical root split by occlusal force.

METHODS

1. The occlusal contact force was studied in 34 cases (39 teeth) by photocclusion. 2. The stress analysis for the first mandicular molar was studied by three-dimensional definite element.

RESULTS

1. The occlusal contact force didn't distribute balancedly in 26 cases (31 teeth) and the suffering teeth bore greater force. 2. The bucco-lingual central line of the mesial root canal wall underwent greater tensile stress when tooth bore load with 30 degrees angle to axis, or buccal-lingual lateral load or logitudinal occlusive load on the masial or distal cusp.

CONCLUSION

The vertical root split of molar is associated with greater occlusal force and the stress that concentrated on the buccolingual central line of the mesial root wall for a long time.