the study aims to investigate the clinical influence of different implant locations; lateral incisor, canine, and first premolar areas; supporting 2-implant retained mandibular over-dentures with locator attachment on prosthesis retention and peri-implant health.

the study aims to investigate the clinical influence of different implant locations; lateral incisor, canine, and first premolar areas; supporting 2-implant retained mandibular over-dentures with locator attachment on prosthesis retention and peri-implant health.

• Thirty-six edentulous patients will be recalled from the database set of the clinic of the removable prosthodontic department, Faculty of Dentistry, Mansoura University. Patients will be recruited from previous studies, having two-implant mandibular overdentures.
• All selected patients with the following criteria: mandibular two implants retained overdenture opposing complete edentulous maxillary arch, attended the previous follow-up recalls with previous CBCT examination. Patients who didn't attend previous follow-up recalls, didn't perform radiographic follow-up, or had para-functional habits will be excluded from the study.
• The patients will be grouped based on the implant position:

Group I (12 patients): patients having mandibular two implants in lateral incisor positions.

Group II (12 patients): patients having mandibular two implants in the canine positions.

Group III (12 patients): patients having mandibular two implants in the premolar positions.

• Implant-retained overdenture construction procedures:

  1. Primary maxillary and mandibular impressions were made, and custom trays were fabricated using auto-polymerizing acrylic resin. The mandibular tray was fabricated with holes above the implant sites and molded with green impression compound modeling plastic.

  2. Definitive impressions were made with non-eugenol zinc oxide paste, and the impression copings were threaded to the implants, and polyether material was injected around the copings through the opening of the tray. Auto-polymerizing acrylic resin was used to pick up the copings with the tray. Implant analogs were screwed to the copings and the impressions was poured with stone.

  3. Locator abutment (Dentium, Co. Ltd., Korea) screwed in the analogs. Jaw relations were recorded, and semi-anatomical acrylic teeth eeee arranged in balanced occlusion.

  4. The locator housing and retentive clips were incorporated into the fitting surface of the overdentures during denture processing.

     Method of evaluation

• Assessment of the peri-implant soft tissue health including Plaque index, Probing depth, and bleeding index. Also, evaluation of the peri-implant bone loss was done at one, two, and three years after insertion using a CBCT, following the methodology described by Elsyad et al.

• Measurements of retention values: using the device of measuring the clinical retentive forces.

• Assessment of patient satisfaction and Oral Health-Related Quality of Life: using a visual analog scale (VAS) questionnaire.

Inclusion Criteria:

• mandibular two implants retained overdenture opposing complete edentulous maxillary arch.
• patients who attended the previous follow-up recalls with previous CBCT examination

Exclusion Criteria:

• Patients who didn't attend previous follow-up recalls.
• patients who didn't perform radiographic follow-up.
• patients who had para-functional habits.