Statement of the problem: Endosseous implants are being increasingly used for the retention of mandibular restorations in recent years. It has been suggested that there is a risk of maxillary bone resorption under complete dentures in patients wearing mandibular implant-retained overdentures as well as mandibular all-on-four hybrid prosthesis. However, there was little evidence-based information about the effect of these 2 treatment modalities on the maxillary bone changes. Patients and methods: This is a prospective parallel randomized controlled clinical study, in which forty eight implants were placed in mandibles of 12 completely edentulous male patients. Patients were randomly allocated into one of the two groups: group A, where 6 patients received 4 parallel implants with implant retained overdenture and group B, where 6 patients received 4 implants in the anterior part of the mandible, 2 axial implants in the center and 2 tilted implants at the distal ends with all-on four hybrid prosthesis. All patients received maxillary removable complete dentures. Radiographic evaluation was made using the CBCT to asses bone height changes that occur in the anterior and posterior maxillary areas 6 months and 12 months following denture insertion and functional loading in comparison to time of loading. Collected data were tabulated and statistically analyzed. Results: Comparison of radiographic bone changes under complete maxillary denture at the anterior and posterior maxilla, between group A and group B, showed no significant differences between the two groups at any time interval. However, pair-wise comparison of bone height changes over time for each group showed significant difference between immediate time point and 12-month post-loading time point in group A, both in anterior and posterior maxilla, where the P value was <0.05. On the other hand there was no significant difference between the same time points in group B, both in anterior and posterior maxilla.

No abstract

Objective: The purpose of this RCL was to evaluate bone height changes around hybrid implants in three implant-retained mandibular overdenture with locator attachment. Materials & Methods: Ten completely edentulous male patients were enrolled in this study. Preoperative Cone beam computed tomography (CBCT) had been made to evaluate bone height & density in areas for implant installation. Patients had received three hybrid implants installed in midline & mandibular canine areas following flapless technique. Implants were early loaded; two weeks after implant installation. Overdentures were functionally fitted onto the locator attachment of the hybrid implants by direct pickup technique. Evaluation: Bone height changes were evaluated with the aid of CBCT at the time of implants' loading, six months and twelve months later. Mesial & distal crestal bone heights were calculated from reconstructed corrected sagittal views. Results: The results had revealed that there was no significant difference in peri-implant bone level throughout the follow-up periods on comparing the three implant sites. However, there was slightly higher bone resorption around the distal implants than the midline ones. Conclusions Three implant retained overdentures with locator attachments may preserve periimplant bone in the anterior mandibular area. Midline implant in three implant overdentures may not be subjected to more stresses than the two distal implants (356)

No abstract

No abstract