Abstract:

Objective　The aim of this studywas to analyse the stress distribution in the periodontium of the maxillary first molar and to search optimal loads patternwhen distal movementto provide biomechanical basis forthe clinical practice.Methods　 By spiral CT scanning, a three-dimensional finite element model of the maxillary first molarwas established, and then four differ- ent load patterns were added to the molar to obtain the optimal load partern for molar bodily distal movement.Results　Different loads lead to different stress distributions when distal movement.Conclusion　A distalizing force combined with a countertipping moment (Mt/F=10) and a counterrotationmoment(Mr/F=6) can lead to a lower and uniform stress on the distal side of the peri- odontal ligament,it implys a tendency of translation of the maxillary first molar.

Key words: maxillary first molar, periodontal tissue, stress distribution, finite element method