Longitudinal Analysis of Alveolar Ridge Morphology After Dental Implant Placement

Objectives: Implant abutment design plays an important role in long-term implant stability and success. In this study, we examined the outcomes in three dental implant abutment designs using a geometric morphometric (GM) approach to analyzing shape. We also investigated the impact of hard and soft tissue grafting upon alveolar ridge morphology.
Methods: Patients (n=141) were randomly assigned to one of three implant abutment design types. A series of silicone dental impressions were taken for each patient: prior to implant placement, after grafting (if relevant), and at regular intervals post-implantation. Casts were poured, and these scanned using an optical scanner (3M Lava Scan ST) producing 3D surface renderings. 2D coordinate landmarks and sliding semi-landmarks were used to quantify shape around the tooth of interest using standard GM analyses. When possible, the contralateral tooth tooth was used as a control. Patterns of shape change through time were examined for each individual, and aggregate patterns of shape change were compared using the following grouping variables: tissue grafting (Y/N), bone grafting (Y/N), implant abutment design.
Results: A relative warps analysis (RWA) of the shape data yielded three significant relative warps. Presence or absence of soft tissue grafting corresponded with variation in shape change through time (p<0.001). There is weak evidence of variation in shape of the alveolar ridge between the patients who received the different implant designs, with implant design corresponding with variation along RW1 (p=0.02) and RW3 (p=0.033), though neither of these values maintain significance after Bonferroni correction.
Conclusions: Aspects of the implant process, such as soft tissue grafting, can have a significant impact upon alveolar ridge morphology. Shape differentiation related to the implant abutment design may indicate greater/lesser stability through time, or may be due to additional factors which correlate with implant design.