Single-implant Versus Two-implant Mandibular Overdentures

Official title

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

Overview

This randomized controlled trial compares a mandibular overdenture retained by one implant placed in the parasymphyseal or canine region with a mandibular overdenture retained by two implants placed in the interforaminal region in completely edentulous adults. Primary outcomes are oral health-related quality of life, patient satisfaction, and masticatory performance measured by a two-color chewing gum mixing test, assessed at baseline before implant surgery and at 3, 6, and 12 months after overdenture insertion.

Detailed description

Eligible completely edentulous adults will be randomized to receive either one endosseous implant in the mandibular parasymphyseal or canine region on the preferred chewing side or two endosseous implants in the mandibular interforaminal region, followed by restoration with a locator-type attachment retained mandibular overdenture. Oral health-related quality of life, patient satisfaction, and masticatory performance assessed by a two-color chewing gum mixing test are collected at baseline before surgery and at 3, 6, and 12 months after overdenture insertion. Secondary outcomes include postoperative pain recorded during the early postoperative period, radiographic marginal bone level change, peri-implant clinical parameters, prosthetic maintenance events, and clinician chair time from implant surgery through overdenture insertion.

Interventions

• Procedure Single-implant mandibular overdenture (parasymphyseal/canine region)
  Placement of one endosseous implant in the mandibular parasymphyseal/canine region on the participant's preferred chewing side, followed by delivery of a mandibular overdenture retained with a standardized attachment protocol and follow-up schedule.
• Procedure Two-implant mandibular overdenture (interforaminal)
  Placement of two endosseous implants in the mandibular interforaminal region (bilateral lateral incisor-canine area), followed by delivery of a mandibular overdenture retained with the same standardized attachment protocol and follow-up schedule.

Primary outcome measures

• Change from baseline in Oral Health Impact Profile for Edentulous Adults (OHIP-EDENT) total score [Time frame: Baseline (pre-surgery), 3 months after overdenture insertion, 6 months after overdenture insertion, and 12 months after overdenture insertion]
• Change from baseline in McGill Denture Satisfaction Questionnaire (MDSQ) total score [Time frame: Baseline (pre-surgery), 3 months after overdenture insertion, 6 months after overdenture insertion, and 12 months after overdenture insertion.]
• Change from baseline in masticatory performance measured by two-color chewing gum mixing test (Variance of Hue [VoH]) [Time frame: Baseline (pre-surgery), 3 months after overdenture insertion, 6 months after overdenture insertion, and 12 months after overdenture insertion.]

Secondary outcome measures (9)

• Visual Analog Scale (VAS) for postoperative pain [Time frame: 24 hours after implant surgery, 7 days after implant surgery, and 21 days after implant surgery.]
• Expected and Perceived Treatment Burden Questionnaire Score (overall and stage-specific) [Time frame: Baseline (pre-surgery, expected burden); within 7 days after implant surgery (experienced surgical-stage burden); at overdenture insertion (experienced prosthodontic-stage burden).]
• Marginal bone level (MBL) change around implants (mm) [Time frame: Overdenture insertion (baseline), 3 months after overdenture insertion, and 12 months after overdenture insertion]
• Implant survival [Time frame: Up to 12 months after overdenture insertion.]
• Peri-implant probing depth (PPD), mean per implant (mm) [Time frame: Baseline (at overdenture insertion), 3 months after overdenture insertion, 12 months after overdenture insertion.]
• Modified plaque index (mPI) [Time frame: 3 months and 12 months after overdenture insertion.]
• Bleeding on probing (BOP) per implant (%) [Time frame: Baseline (at overdenture insertion), 3 months after overdenture insertion, 12 months after overdenture insertion.]
• Prosthetic maintenance events and complications of implant-retained overdenture [Time frame: Up to 12 months after overdenture insertion.]
• Treatment efficiency: total clinician chair time [Time frame: From implant surgery through overdenture insertion.]

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.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Treatment

Study locations

Palestinian Territories · 1 center

• Faculty of Dentistry/ Arab American University — Jenin

Identifiers

NCT: NCT07408778 · AAUP IRB Ref: J-2025A/46/N.

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗