OBJECTIVETo investigate the changes of stress distribution in the normal maxillary complex under different conditions and explore the feature of biomechanical reaction.

METHODSA three-dimensional finite element stress analysis has been used to investigate the characters of stress distribution at open-mouth position and in centric occlusion.

RESULTSUnder the same load, the stresses of the same region in the normal maxillary complex were distributed unequally. The limits of stress at open-mouth position (8.969 N) were wider than that in centric occlusion (6.497 N).

CONCLUSIONSThe stress of the whole maxillary complex in centric occlusion was lower than that at open-mouth position because of the different state of masticatory muscle. This indicated that the effect of muscles needed to be considered in the study of maxillary complex biomechanics.