This study aimed to compare the use of single implants in the symphyseal and parasymphyseal, and two implants were inserted in the canine area bilaterally to assist mandibular complete overdentures regarding clinical evaluation, marginal bone loss, and masticatory efficiency. The null hypothesis was that there was no statistically significant difference in clinical evaluation, marginal bone loss, and masticatory efficiency among single symphyseal implants, single parasymphyseal implants, and two-implant-assisted complete mandibular overdentures.

This randomized, controlled clinical trial compared the symphyseal and parasymphyseal single implants versus two implants in complete mandibular overdentures. Fifteen completely edentulous male patients (50-65 years) were chosen and randomly grouped into three equal groups (five patients in each) according to the position and number of the received implants to assist mandibular complete overdentures. Group I: single median implant. Group II: single parasymphyseal implant. Group III: two implants were inserted in the canine area bilaterally. After three months of osseointegration, the lower denture was transformed into an implant-assisted complete mandibular overdenture. Clinical observations were documented on the day of loading, three, six, and nine months later for each implant. Follow-up CBCT scans were performed to assess marginal bone loss on the day of loading, six and twelve months later. The masticatory efficiency evaluation was conducted one month and three months after loading.

Inclusion Criteria:

• patients with a class I Maxillo-mandibular jaw relationship
• patients with residual ridges had normal morphology, were free from severe bony undercuts or flabby tissue, and were covered by firm mucoperiosteum.
• A cone beam CT of the lower arch was made to detect the presence of pathological lesions, remaining roots, or impacted teeth in the arch and evaluate both bone quality and quantity, especially in the area of interest

Exclusion Criteria:

• patients with current chemotherapy or radiotherapy, bleeding disorders, uncontrolled diabetes
• patients with a history of drug therapy that interferes with bone resorption or deposition (e.g., the prolonged use of glucocorticoids, antiresorptive medications, selective serotonin reuptake inhibitors, and proton-pump inhibitors),
• Those with any physical reasons that could affect follow-up, psychiatric problems, heavy smokers, drug or alcohol addicts, immunocompromised patients, abnormal jaw relationship, inadequate inter arch space.
• patients with temporomandibular disorders and para-functional habits (e.g., bruxing and clenching).