Comparison of Attachment Types in Maxillary Implant-assisted Obturators using Digital Image Correlation Analysis

The purpose of the study was to evaluate the stress on the implant and to assess the denture displacement for locator and bar and clip attachment types in implant-assisted obturators. A maxillary edentulous experimental model with a maxillectomy defect was made along with an opposing edentulous mandibular model with self-cure acrylic. Two endosseous implants were placed in the maxillary model. Corresponding obturator complete denture was fabricated for the maxillary model and a complete denture for the mandibular. The attachments were positioned on the implants in maxillary model, and their sleeve/clip was placed on intaglio surface of the dentures. The mounted articulator was placed on a loading apparatus, and force was incrementally applied to it. The strain and displacement for both the attachment types were measured and compared using Digital Image Correlation (DIC). Locator attachment showed the least stress and minimal displacement as compared to bar and clip attachment. The stresses around the implants and displacement of the obturator are affected by the attachment type used. It was found that bar and clip (splinted) showed the maximum stresses around the implant and maximum denture displacement. Locator attachment is the better choice over bar and clip because of its additional retentive features. The advantage of using DIC over the conventional strain gauge analysis is that a full-field data of displacement and strain can be obtained instead of getting a mean value on the small surface where the strain gauge is positioned.