Single-implant versus two-implant mandibular overdenture

Patient-reported Outcomes and Masticatory Performance of Mandibular Overdentures Retained by One Parasymphyseal Implant or Two Implants: Randomized Clinical Trial

This study tests whether one implant or two implants better hold a lower denture for adults without teeth, looking at comfort, chewing ability, and satisfaction over one year.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 32 (estimated)
• Ages: 40 Years and up
• Sex: All
• Sponsor: Arab American University (Palestine) (Academic / other)
• Locations: 1 site (Jenin, Palestine)
• Trial ID: NCT07408778 on ClinicalTrials.gov

What this trial studies

This randomized controlled trial assigns completely edentulous adults to receive either a single endosseous implant in the mandibular parasymphyseal/canine region on the preferred chewing side or two implants in the interforaminal region, both restored with locator-type attachment mandibular overdentures. Eligible participants are adults (≥40 years) in generally good health with acceptable existing dentures and adequate anterior mandibular bone who agree to randomization and follow-up. Primary outcomes are oral health-related quality of life, patient satisfaction, and masticatory performance measured with a two-color chewing gum mixing test, collected at baseline and at 3, 6, and 12 months after overdenture insertion. Secondary outcomes include early postoperative pain, radiographic marginal bone level change, peri-implant clinical parameters, prosthetic maintenance events, and clinician chair time from implant surgery through overdenture insertion.

Who should consider this trial

Good fit: Ideal candidates are completely edentulous adults (≥40 years) with dissatisfaction limited to mandibular denture retention, adequate anterior mandibular bone for an implant, and overall good or controlled health (ASA I–II).

Not a fit: Patients who lack sufficient anterior mandibular bone, require bone augmentation, have uncontrolled systemic disease, are on certain bone-active medications, or have other exclusionary conditions are unlikely to benefit from this protocol.

Why it matters

Potential benefit: If successful, the single-implant approach could provide similar denture stability and chewing function with fewer implants, lower cost, and less invasive surgery.

How similar studies have performed: Two-implant mandibular overdentures are a well-established standard with good outcomes, and several prior trials have shown promising short-term results for single-implant overdentures though single-implant approaches are less widely adopted.

Eligibility criteria

Inclusion Criteria:

* Men and women ≥40 years.
* ASA I-II; favorable general health or adequately controlled systemic disease (e.g., hypertension, diabetes).
* Skeletal Class I relationship.
* Completely edentulous mandible and maxilla.
* Technically acceptable complete dentures in both jaws for ≥3 and ≤24 months; dissatisfaction limited to mandibular retention/stability.
* Adequate anterior mandibular bone for implant ≥3.5×10 mm confirmed on CBCT; no bone augmentation needed.
* Normal mucosal resilience (\~2 mm displacement).
* Implant sites healed ≥4 months since extraction.
* Willingness to be randomized and attend follow-ups; written informed consent.
* Primary stability target ≥25 N-cm.

Exclusion Criteria:

* Uncontrolled systemic disease; neurodegenerative disease; osteoporosis requiring antiresorptives.
* Chronic systemic antibiotics/steroids; bleeding disorders; active cancer therapy; metabolic bone disease; HIV.
* Investigational drug use within 30 days.
* Alcohol dependence/illicit drug use; xerostomia (stimulated flow \<0.7 mL/min).
* Heavy smoking \>20 cigarettes/day.
* TMD/orofacial pain; severe bruxism; moderate/severe cognitive impairment.
* Prior implant therapy.
* Non-adherence risk or inability to attend longitudinal visits.
* Insufficient prosthetic space for attachment housing: inter-arch vertical distance \<8.5 mm at parasymphyseal/canine region.
* Concurrent participation in another interventional study.
* Erosive lichen planus or other significant oral mucosal disease; head-and-neck irradiation history.
* Mandibular pathology on CBCT (e.g., cyst, tumor).
* Ridge dimensions \<6 mm width or \<10 mm height at planned sites.
* Active intraoral infection.

Where this trial is running

Jenin, Palestine

• Faculty of Dentistry/ Arab American University — Jenin, Palestine, Palestinian Territories (Recruiting)

Study contacts

• Principal investigator: Rola M Shadid, BDS, MSc — Arab American University
• Study coordinator: Rola M Shadid, BDS, MSc

Conditions Edentulism; mandibular denture instability; poor denture retention; implant-retained overdenture