Single-implant Versus Two-implant Mandibular Overdentures

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

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.

Study Overview

• Status: Recruiting
• Conditions: Edentulism
• Intervention / Treatment: Procedure: Single-implant mandibular overdenture (parasymphyseal/canine region); Procedure: Two-implant mandibular overdenture (interforaminal)

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.

• Study Type: Interventional
• Enrollment (Estimated): 32
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rola M Shadid, BDS, MSc; Phone Number: +970594494066; Email: rola.shadid@aaup.edu
• Study Contact Backup: Name: Jafar AbuAssba, BDS, MSc; Phone Number: 00970598595800; Email: jafar.abuassba@aaup.edu

Study Locations

• Palestinian Territories
  • Palestine
    • Jenin, Palestine, Palestinian Territories, 240 jenin
      • Recruiting
      • Faculty of Dentistry/ Arab American University
      • Contact: Rola shadid; Phone Number: 00970594494066; Email: rola.shadid@aaup.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Single-implant mandibular overdenture (parasymphyseal/canine, preferred chewing side); One bone-level implant will be placed in the mandibular parasymphyseal/canine region on the preferred chewing side using a single-stage approach. A locator-type attachment (Sonator S) will be connected according to the manufacturer's instructions, and intraoral pick-up will be performed with cold-curing resin.	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.
Active Comparator: Two-implant mandibular overdenture (interforaminal); Two bone-level implants will be placed bilaterally in the mandibular interforaminal region (bilateral lateral incisor-canine area) using a single-stage approach. Locator-type attachments (Sonator S) will be connected according to the manufacturer's instructions, and intraoral pick-up will be performed with cold-curing resin.	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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in Oral Health Impact Profile for Edentulous Adults (OHIP-EDENT) total score	Oral health-related quality of life (OHRQoL) will be assessed using the Oral Health Impact Profile for edentulous adults (OHIP-EDENT). OHIP-EDENT includes 19 items across 7 domains: functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap. Each item is rated on a 5-point Likert scale from 0 ("never") to 4 ("very often"). Total score range is 0-76; lower scores indicate better oral health-related quality of life (OHRQoL).	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	McGill Denture Satisfaction Questionnaire (MDSQ) includes 8 core questions. Each item is scored on a 100-mm VAS (0 = "no satisfaction at all"; 100 = "complete satisfaction"). Total score = sum of 8 items (range 0-800); higher scores indicate greater satisfaction.	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])	Masticatory performance will be assessed using the two-color chewing gum mixing test. Chewed specimens are imaged and analyzed using ViewGum® software to calculate the Variance of Hue (VoH; range 0-1). Lower VoH indicates better color mixing (better masticatory performance).	Baseline (pre-surgery), 3 months after overdenture insertion, 6 months after overdenture insertion, and 12 months after overdenture insertion.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visual Analog Scale (VAS) for postoperative pain	Postoperative pain/discomfort will be measured using a Visual Analog Scale (VAS). The VAS has an intensity range from 0 to 100, where 0 indicates "no pain" and 100 indicates "worst pain." Higher VAS scores indicate worse outcome (greater postoperative pain/discomfort).	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)	Patient-reported treatment burden will be assessed using the Expected and Perceived Treatment Burden Questionnaire (20 items rated on a 4-point Likert scale: 1 = not burdensome at all to 4 = extremely burdensome); overall and stage-specific burden scores will be calculated as the mean item score (range 1-4), where higher scores indicate greater burden (worse outcome), and an expectation-perception discrepancy will be calculated for each stage as perceived burden - expected burden (positive values indicate greater burden than expected).	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)	Marginal bone level (MBL) will be measured on standardized periapical radiographs as the vertical distance (mm) from the implant platform to the first bone-to-implant contact at the mesial and distal aspects; for each implant and timepoint, mean MBL will be calculated as the average of mesial and distal measurements, and mean MBL change (mm) will be computed as the follow-up mean MBL minus the baseline mean MBL.	Overdenture insertion (baseline), 3 months after overdenture insertion, and 12 months after overdenture insertion
Implant survival	Presence of implant in situ without removal.	Up to 12 months after overdenture insertion.
Peri-implant probing depth (PPD), mean per implant (mm)	PPD will be measured at 4 sites/implant (mesial, distal, buccal, lingual) with a periodontal probe as the distance (mm) from the peri-implant mucosal margin to the base of the peri-implant sulcus; the implant-level outcome will be the mean of the four site measurements at each timepoint.	Baseline (at overdenture insertion), 3 months after overdenture insertion, 12 months after overdenture insertion.
Modified plaque index (mPI)	Peri-implant plaque will be assessed at 4 sites/implant (mesial, distal, buccal, lingual) using a periodontal probe by visual inspection along abutment surfaces and scored using the Mombelli modified plaque index (0-3): 0 = no plaque; 1 = plaque detected on probing; 2 = plaque visible to the naked eye; 3 = abundance of soft matter; the implant-level outcome will be the mean of the four site scores per implant at each timepoint.	3 months and 12 months after overdenture insertion.
Bleeding on probing (BOP) per implant (%)	BOP will be recorded at 4 sites/implant (mesial, distal, buccal, lingual) as present/absent after gentle probing; the implant-level outcome is the percentage of bleeding sites per implant (0-100%) at each timepoint.	Baseline (at overdenture insertion), 3 months after overdenture insertion, 12 months after overdenture insertion.
Prosthetic maintenance events and complications of implant-retained overdenture	Number and type of prosthetic maintenance events and complications related to the mandibular implant-retained overdenture recorded from clinical charts through 12 months after overdenture insertion. Events will be summarized as (a) total number of events per participant and (b) number of participants with ≥1 event. Higher values indicate worse outcome (greater maintenance/complication burden).	Up to 12 months after overdenture insertion.
Treatment efficiency: total clinician chair time	Total clinician chair time (minutes) for surgical and prosthodontic procedures required to deliver the implant-retained mandibular overdenture. Lower values indicate greater treatment efficiency.	From implant surgery through overdenture insertion.

Collaborators and Investigators

• Sponsor: Rola Shadid
• Investigators: Principal Investigator: Rola M Shadid, BDS, MSc, Arab American University

Study record dates

Study Major Dates

• Study Start (Actual): February 16, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: January 26, 2026
• First Submitted That Met QC Criteria: February 6, 2026
• First Posted (Actual): February 13, 2026

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 16, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: mandibular denture instability; poor denture retention; implant-retained overdenture
• Other Study ID Numbers: AAUP IRB Ref: J-2025A/46/N.

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data (including data dictionary/codebook) underlying the primary and secondary outcomes will be shared.
• IPD Sharing Time Frame: Available beginning after publication of the primary 12-month results, for 3 years.
• IPD Sharing Access Criteria: Available to qualified researchers upon reasonable request, submission of a methodologically sound proposal, and execution of a data-use agreement; data will be shared via secure file transfer.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No