Sixteen dental implants inserted in sixteen patients who were selected from the outpatient clinic of the Oral and Maxillofacial Surgery Department, Faculty of Dentistry, Mansoura University, for the rehabilitation of missed single maxillary posterior tooth by an immediately loaded dental implants

16 dental implants were inserted in 16 patients were divided into two groups: Group A: 8 dental implants were inserted using undersized drilling technique and Group B: 8 dental implants were inserted using single drilling technique. then the dental implants were assessed for 6 months regarding

Clinical Evalution: regarding these parameters after immediately dental implants loading,3 months and 6 months.

implant stability, implant probing depth, bleeding index.

Radiographic evaluation: immediately after implant loading and 6 months after loading regarding bone density and marginal bone loss.

Inclusion Criteria:

• Patients with missed one or more posterior maxillary tooth.
• Be older than 18 years and of residual bone height more than10 mm.
• Patients with good oral hygiene and willing to participate in the follow-up sessions.
• Patients with adequate mesio-distal width and inter-arch space.
• Patients without any para-functional habits such as clenching and bruxism.

Exclusion Criteria:

• Patients whose proposed surgical site had any pathological lesion or root tips.
• Drug or alcohol abuse.
• Patients with uncontrolled systemic diseases.
• Pregnant patients.
• Tobacco use more than fourteen cigarettes daily.