Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part II

Statement of problem. Insufficient buccal bone volume can be a significant problem when loading dental implants in the maxilla. Increased potential fo r buccal fenestration and dehiscence can result in an exposed implant surfa ce, mucosal irritation, decreased support, and potential implant failure. Purpose. The objective of this study was to model the stress distribution a round maxillary implants by comparing simulated occlusal loading of maxilla ry implants in a 2-dimensional photoelastic anatomic model and a dry skull model. Material and methods. Two model systems were used. First, a 2-dimensional p hotoelastic anatomic frontal skull sectional model was prepared in the firs t molar region. Left and right maxillary metal cylinder implant analogues i nclined at 0 and 25 degrees to the sagittal plane were loaded in simulated intercuspation. Second, a dry skull lined with a photoelastic coating on th e buccal aspect over an embedded cylinder implant was prepared in the first molar region. Principal stress concentration was photographed on axial and nonaxial implant loading. Results. On simulated intercuspal loading, maximum stress concentration occ urred at the buccal concavity in both the 2-dimensional anatomic photoelast ic and skull models. There was no stress concentration at the apices of the maxillary implants in the 2-dimensional model. On lateral loading of the s kull model, stress was distributed along the entire buccal aspect of bone a djacent to the implant, with a higher concentration at the buccal concavity . Conclusion. Preservation of buccal supporting bone volume is desirable to o btain a physiological modeling response and to enhance the facial plate. In sufficient bone volume may result in buccal fenestration or dehiscence, whi ch can precipitate mucosal irritation, decreased support, and potential imp lant failure.