Crestal Bone Response to Narrow vs. Regular Tie-Base in Subcrestal Implants

\*\*Inclusion Criteria Adults ≥18 years old. Single missing tooth in a posterior quadrant, bordered by adjacent natural teeth. Adequate bone volume to place implants 8.5-10 mm in length and 4 mm in diameter without the need for bone or soft tissue grafting. Presence of a natural tooth or an implant-supported fixed restoration as an antagonist. Good oral hygiene with a plaque index \<25%. Willing and able to comply with study procedures and follow-up schedule. Provided written informed consent. \*\*Exclusion Criteria Systemic conditions or medications affecting bone metabolism (e.g., bisphosphonates, corticosteroids). Untreated periodontitis, persistent oral infections, or poor oral hygiene. Metabolic bone diseases (e.g., osteoporosis, renal insufficiency, immunodeficiency, leukocyte dysfunction). History of head and neck radiotherapy. Physical or mental disability preventing adequate oral hygiene or compliance. Heavy smoking (\>10 cigarettes/day). Alcoholism or drug abuse. Pregnancy or breastfeeding. Bruxism or oral mucosal diseases. Need for bone regeneration procedures before implant placement. Inability or unwillingness to attend follow-up visits.