Stress Distribution of Rigid Fixed Bridge in Abutments with Mandibular 56 Deletion-A three-dimensional Finite Element Analysis

Mandibular teeth and sustentacular tissues extracted from a healthy adult were treated using CT scanning to obtain two-dimensional image, and then a three-dimensional image was established using computer reconstruction technique. Simultaneously, a three-dimensional finite element model of rigid fixed bridge was established in abutments with mandibular 56 deletion. A fixing load of 100 N was vertically and horizontally loaded on the middle site of bridge, and the abutments were grouped according to the proportion of alveolar bone absorption of 5% sub-interval to analyze the effects of 0-50% alveolar bone absorption on stress distribution of rigid fixed bridge. When the alveolar bone absorption was zero or less than 10%, the stress of rigid fixed bridge was evenly distributed on abutments with the vertical load of 4-7 MPa and horizontal load of 6-9 MPa; when the alveolar bone absorption was greater than 10%, the stress of rigid fixed bridge was concentrated on the abutments with the vertical load of 9-16 MPa and horizontal load of 14-23 MPa. This suggested that alveolar bone absorption had great effect on stress distribution of rigid fixed bridge in abutments with mandibular 56 deletion, namely a little absorption would cause the changes of stress distribution.