1992 Volume 5 Issue 2 Pages 256-262
A two-piece apatite implant (APACERAM® 2-Piece Implant Type-S) can be used as a free-standing implant. We investigated the position and direction of the implant root by the 2-dimensional finite element stress analysis.
Finite element models were three buccolingual section models of the left mandibular molars to which the implant root was inserted with different conditions. Loading condition was the vertical load of 100 N applied to a point on the occlusal table. And an equivalent stress distribution in the osseous supporting structure around the implant was analyzed in the models with the following conditions:
Model 1: The long axis of the implant root agreed with that of the implant crown.
Model 2: The long axis of the implant root was inclined lingually at an angle of 15° from that of the crown.
Model 3: The long axis of the implant root was shifted 1.5 mm buccally from that of the crown.
Results
1. When a vertical load was applied to the center of the implant crown in Model 1(i.e.,the long axis of the implant root ran in the direction of the loading vector), high stress concentrated in the cortical bone around the implant neck; and stress was distributed along the cortical bone. Accordingly as the loading point was shifted from the center to the lingual side, the stress was increased within the lingual bone around the implant, but decreased within the buccal bone around it.
2. In Model 2 (i.e., the long axis of the root was inclined lingually from the loading vector), high stress concentrated in the lingual cortical bone around the implant neck and in the buccal cortical bone contacting the implant base.
3. In Model 3, (i.e., the long axis of the root was shifted buccally from the loading vector), high stress concentrated in the lingual cortical bone around the implant neck and in the buccal cortical bone contacting the implant base.
