Partially-guided Protocol for Maxillary Overdentures Retained by Ti-Zr One-piece Mini Implants

This is a single-center, single-group, prospective clinical trial testing a partially-guided protocol for placement of mini implants overdentures in the edentulous maxilla. Eligible participants will be subjects with an edentulous maxilla, wearing a conventional complete denture. Participants will receive six mini implants (Straumann® Mini Implant System, Institut Straumann AG, Switzerland) for retention of a maxillary overdenture. The six mini implant protocol will be virtually planned for an even distribution of the implants bilaterally, with a minimum of 5 mm distance between contiguous implants. The available lengths of the mini implants are 10, 12, and 14 mm, and the appropriate length will be selected according to the bony anatomical situation. In addition, the distribution and axial position of the mini implants will be planned to achieve the best biomechanical distribution and the most parallel position between implants, perpendicular to the occlusal plane and path of insertion of the prosthesis. The primary outcome will be the accuracy of the implant position using the partially-guided protocol. Assessment of the accuracy of the methods will be based on the measure of the difference between the actual and the planned position of the mini implants, based on the measurement of (1) the global deviations at the coronal and apical regions of the mini implants, (2) the vertical deviation, and (3) the apical angle deviation. Overall impacts of treatment on oral health-related quality of life will be assessed using the Oral Health Impact Profile instrument for edentulous subjects (OHIP-EDENT). Additional outcomes will include implant survival and success rates, incidence of prosthodontic complications and peri-implant measurements.