This clinical study is being conducted at Cairo University to evaluate two different types of attachments used with implant-supported dentures in the mandible. Patients who have lost all their teeth in the lower jaw receive implants to help hold their dentures in place. This study compares two types of attachments for connecting the denture to the implants:

1. Bar attachment only, which is a traditional method.
2. Bar with OT Cap attachment, which is a newer design that includes a small sphere (cap) to help with retention and comfort.

The purpose of this study is to find out which attachment type works better in terms of:

1. How well the denture stays in place (retention)
2. How much bone is lost around the implants over time (crestal bone loss)
3. How much the attachment parts wear out (cap wear)
4. How satisfied the patients are with their dentures

The study is a randomized controlled trial. This means participants will be randomly assigned to one of the two groups (bar-only or bar with OT Cap). All participants will receive complete dentures and three dental implants in the lower jaw.

Follow-up will include measurements of denture retention and cap wear at the time the denture is inserted and again after 6 months. Bone loss will be checked with digital X-rays, and patient satisfaction will be assessed using a short questionnaire.

The study will include 22 participants (11 in each group), aged 30 to 65, who are healthy and have enough bone in the jaw to support implants.

This study is designed to help dentists and patients make better decisions about which type of implant attachment provides better long-term results and patient comfort.

This randomized controlled clinical trial is designed to evaluate and compare the clinical and radiographic outcomes of two mandibular implant-supported overdenture attachment systems: (1) conventional bar attachment, and (2) bar with OT Cap (sphere) attachment. The objective is to determine which system provides superior performance in terms of prosthesis retention, crestal bone preservation, attachment wear, and patient satisfaction.

A total of 22 completely edentulous participants, aged between 30 and 65 years and meeting strict inclusion criteria, will be enrolled. Each participant will receive three endosseous implants placed in the anterior mandibular region (midline and canine positions). Following a four-month osseointegration period, participants will be randomly allocated (1:1) to one of two intervention groups: Group A (bar attachment only) and Group B (bar with OT Cap sphere attachments).

The prosthetic protocol involves the fabrication and delivery of maxillary and mandibular complete dentures, followed by intraoral placement and pick-up of the attachment systems. The primary outcome is denture retention, assessed at baseline (T0) and after 6 months (T6) using a digital force gauge. Secondary outcomes include crestal bone loss (evaluated via standardized digital radiographs), cap wear (measured using electron microscopy), and patient satisfaction (assessed using a validated Visual Analog Scale questionnaire).

Randomization will be conducted using a computer-generated sequence with allocation concealment ensured via opaque sealed envelopes. Due to the nature of the intervention, blinding of participants and clinicians is not feasible; however, outcome assessment and statistical analysis will be performed by a blinded examiner.

This study addresses a critical gap in the comparative assessment of attachment systems for implant-retained mandibular overdentures. While bar attachments are widely used for their rigidity and implant splinting capacity, recent innovations such as the OT Cap aim to enhance retention and reduce maintenance through added resilience. By directly comparing these two configurations in a controlled setting, the study aims to contribute clinically relevant data to guide prosthodontic treatment planning for edentulous patients.

Inclusion Criteria:

• Completely edentulous healthy patients
• Age between 30 and 65 years
• Adequate bone volume in the anterior and premolar-molar region (minimum 11 mm)
• Adequate inter-arch space (12-14 mm)

Exclusion Criteria:

• Severe maxillomandibular skeletal discrepancy
• Parafunctional habits (e.g., clenching, bruxism)
• Temporomandibular joint disorders
• Heavy smokers (≥20 cigarettes/day)
• History of head and neck radiation
• History of chemotherapy
• Systemic conditions that may interfere with healing or bone quality (e.g., uncontrolled diabetes, osteoporosis, bisphosphonate therapy)
• Drug abuse or alcohol dependence

Individual participant data (IPD) will not be shared because this study is self-funded and conducted as part of a doctoral thesis project. No data-sharing mechanism or repository has been established, and participants were not consented for external data sharing. Additionally, confidentiality and ethical guidelines limit redistribution of participant-level data

Only the outcomes assessor (statistician) will be blinded to group allocation to reduce assessment bias. Neither the participant nor the care provider can be blinded due to the visible nature of the intervention.