Marginal Bone Changes in Fixed All-on-Four Mandibular Prosthesis Using OT Bridge Attachment System

Group I (control) Edentulous mandible receiving all on four fixed mandibular prosthesis using conventionally screw retained multiunit abutments.

Group II (intervention) Edentulous mandible receiving all on four fixed prostheses using OT bridge attachments system.

For both groups, the implant sites will be prepared aided by the surgical template. 4 implants with length 11-13 mm will be placed, two anterior implants will be aligned in an axial orientation and two posterior implants will be distally aligned according to the all-on-four concept in the inter foraminal area. Implants will be ideally placed at bone level.

For both groups:

After implant placement and surgical guide removal, healing abutments ( will be connected during healing periods (eight to twelve weeks).

Group I ( control) After eight to twelve weeks from implant placement, multiunit abutments with appropriate heights and angulations will be connected to the implants.

Group II ( intervention) After eight to twelve weeks from implant placement, narrow- and low-profile OT Equator abutment will be screwed onto the implants according to the manufacturer.

marginal bone changes and prosthetic complications are the outcomes Radiographic follow up will be performed for marginal bone changes Serial of standardized digital periapical radiographs using will be taken at the time fixed prosthesis insertion (baseline), 3,6,9,12 months.

Type and incidence of prosthetic complications for the prothesis for each group will be evaluated in 3, 6,9 and 12 months, these complications included: loosening or fracture of the prosthetic screw, prosthesis mobility and fracture of the prosthesis.