This randomized clinical trial aims to assess periodontal health and patient satisfaction in mandibular distal extension removable partial dentures using CAD/CAM fiber-reinforced composite versus porcelain-fused-to-metal extracoronal attachments. Twelve participants with bilateral mandibular Kennedy Class I, retaining only the first premolars as the last standing abutments, will be randomly assigned to two groups. Group I will receive OT extracoronal attachments made from CAD/CAM fiber-reinforced composite, while Group II will receive OT extracoronal attachments made from porcelain-fused-to-metal. All participants will then receive a metallic removable partial denture. The null hypothesis states that no significant differences will be observed in periodontal health and patient satisfaction between the two attachment types.

Twelve participants with bilateral maxillary Kennedy Class I, with the first premolars as the last standing abutments, will be recruited based on strict inclusion criteria from the oral and maxillofacial prosthodontic outpatient clinic. The canines and first premolars will be prepared to receive OT extracoronal attachments made from either CAD/CAM fiber-reinforced composite (Group I) or porcelain-fused-to-metal (Group II), according to group allocation. All participants will then receive a metallic removable partial denture. Periodontal health will be assessed through bleeding index, probing depth, and gingival recession at denture insertion and after six months and twelve months. Patient satisfaction will also be evaluated at the twelve-month follow-up.

Inclusion Criteria:

1. Mandibular partially edentulous bilateral distal extension Kennedy Class I with first premolars as last abutments.
2. The opposing maxillary arch will be dentate.
3. Angle class I maxillomandibular skeletal relation.
4. The distal extension ridge will be well-formed and covered by healthy and firm mucosa.
5. As verified by periapical radiographs, Abutments have healthy periodontal ligaments and an appropriate crown/root ratio (CRR).
6. Crown/root ratio of the premolar abutment teeth is not less than 1:1. 5.
7. The vertical distance between the ridge tissue and the opposing teeth of the study cases is not less than 7 mm. 6.
8. The buccolingual dimension of the abutment teeth is not less than 6 mm.

Exclusion Criteria:

1. Patients with any systemic disease that could affect the rate of bone resorption, which was confirmed by obtaining a through medical history.
2. Patients with parafunctional habits (bruxism and clenching).
3. Patients with any septic foci or impacted teeth as proved by panoramic radiograph, as well as patients with tilted or rotated abutments or soft tissue undercuts in areas that will be involved in the RDP design.
4. Patients with any TMJ problems.
5. Patients with any neuromuscular diseases.