[Stress analysis of different fixed prosthesis designs following molar hemisection therapy].

OBJECTIVE

To evaluate mechanical behavior of different fixed prosthesis following molar hemisection therapy for clinical reference.

METHODS

Finite element method and photoelastic method were employed to investigate the stress distribution around the reserved distal root of the first mandibular molar with various fixed prosthesis designs. The restorations of single crown of the first mandibular molar, combined crowns of the first and second mandibular molars, combined crowns of the second mandibular premolar and first mandibular molar, and combined crowns of the second mandibular premolar, the first and second mandibular molars were designed. The same load was simulated on the occlusal surfaces of the molars.

RESULTS

The results of two studies showed that the stress around the reserved root in the single crown model was over 3 times as much as that of the normal model, the first mandibular molar with normal roots and a crown. For the combined crowns of the first and second mandibular molars, the stress was almost twice of the normal stress. While in the models of the combined crowns of the second mandibular premolar and first mandibular molar, as well as the combined crowns of the second mandibular premolar, the first and second mandibular molars, the stress distributions were similar to that in normal conditions.

CONCLUSIONS

Both the results indicated that the restoration of two-unit dual-ended combined crowns has favorable stress distribution and is applicable for the reserved root following the hemisection therapy.