Journal of Prosthetic Dentistry

Correlation of implant position and crestal bone loss in 2-implant mandibular overdentures with immediate loading protocols: A prospective clinical study

Published:November 18, 2022DOI:


      Statement of problem

      The 2-implant mandibular overdenture (2IMO) is a popular treatment for patients with an edentulous mandible, but information on the effect of the optimum implant position on the peri-implant crestal bone level with immediate loading protocols is lacking.


      The purpose of this prospective clinical study was to evaluate correlations between different implant positions and crestal bone loss and between interimplant distance and the crestal bone loss in patients with 2IMOs with immediate loading protocols at 1-year follow-up.

      Material and methods

      A total of 24 participants (13 men, 11 women, mean ±standard deviation age 63.25 ±10.76 years) were treated with 2IMOs (48 Ti-Zr implants) by a single operator between August 2015 and October 2020. The implant diameters (3.3 mm or 4.1 mm) and lengths (10 mm or 12 mm) were selected based on the crestal bone width, and the implants were placed, if possible, in the canine regions. Implant positions and interimplant distance (mm) were measured intraorally with dividers. Prefabricated mandibular dentures were immediately loaded with the LOCATOR-attachments by using a direct intraoral pickup procedure. Crestal bone-level changes were measured with a software program on the mesial and distal sides of each implant from periapical radiographs made with a paralleling technique (at baseline and 1-year follow-up). The measurement values were normalized. The Spearman rho correlation test and paired samples t tests were used for data analysis (α=.05).


      The mean ±standard deviation position of the implants from the midline was 8.78 ±2.25 mm (9.00 ±2.22 mm right side, 8.56 ±2.31 mm left side), and the mean interimplant distance was 16.94 ±4.03 mm. At 1-year follow-up, the mean ±standard deviation crestal bone loss was 0.50 ±0.47 mm (n=48) (0.57 ±0.65 mm mesial, 0.43 ±0.53 mm distal). The mean ±standard deviation crestal bone loss was 0.46 ±0.4 mm with Ø3.3-mm implants (n=42) and 0.9 ±0.8 mm with Ø4.1-mm implants (n=6) (P=.005). Implant positions were negatively correlated (rs=-0.37) with the crestal bone loss, and the correlation was significant (P=.009). Interimplant distances were also negatively correlated with crestal bone loss (rs=-0.60; P=.002). Bone loss on the mesial side was positively correlated with that on the distal side rs=0.20; however, the correlation was not significant (P=.16).


      A weak and negative correlation was found between the implant position from the midline and the crestal bone loss and also between the interimplant distance and crestal bone loss in patients provided with 2IMOs with immediate loading protocols.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Prosthetic Dentistry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Alfadda S.A.
        The relationship between various parameters of complete denture quality and patients' satisfaction.
        J Am Dent Assoc. 2014; 145: 941-948
        • Feine J.S.
        • Carlsson G.E.
        • Awad M.A.
        • et al.
        The McGill consensus statement on overdentures. Mandibular two-implant overdentures as first choice standard of care for edentulous patients.
        Int J Oral Maxillofac Implants. 2002; 17: 601-602
        • Patil P.G.
        • Seow L.L.
        Crestal bone-level changes and patient satisfaction with mandibular overdentures retained by one or two implants with immediate loading protocols: a randomized controlled clinical study.
        J Prosthet Dent. 2020; 123: 710-716
        • ELsyad M.A.
        • Maryod W.H.
        • Mostafa A.Z.
        Effect of implant position on clinical and radiographic outcomes of locator-retained mandibular overdentures: a 1-year prospective study.
        J Prosthodont. 2019; 28: e699-e704
        • Takagaki K.
        • Gonda T.
        • Maeda Y.
        Number and location of mini-implants retaining a mandibular overdenture to resist lateral forces: a preliminary in vitro study.
        Int J Prosthodont. 2017; 30: 248-250
        • Hong H.R.
        • Pae A.
        • Kim Y.
        • Paek J.
        • Kim H.S.
        • Kwon K.R.
        Effect of implant position, angulation, and attachment height on peri-implant bone stress associated with mandibular two-implant overdentures: a finite element analysis.
        Int J Oral Maxillofac Implants. 2012; 27: e69-76
        • Patil P.G.
        • Seow L.L.
        • Uddanwadikar R.
        • Pau A.
        • Ukey P.D.
        Stress and strain patterns of 2-implant mandibular overdentures with different positions and angulations of implants: a 3D finite element analysis study.
        J Prosthet Dent. 24 January 2022; ([Epub ahead of print])
        • Patil P.G.
        • Seow L.L.
        • Tagore M.
        Single versus two dental implant retained mandibular overdenture: study protocol for a randomized controlled trial.
        Dent Implants Dentures. 2016; 1: 104
        • Liddelow G.J.
        • Henry P.J.
        The immediately loaded single implant-retained mandibular overdenture: a 36-month prospective study.
        Int J Prosthodont. 2010; 23: 13-21
        • Kronstrom M.
        • Davis B.
        • Loney R.
        • Gerrow J.
        • Hollender L.
        A prospective randomized study on the immediate loading of mandibular overdentures supported by one or two implants: a 12-month follow-up report.
        Int J Oral Maxillofac Implants. 2010; 25: 181-188
        • Patil P.G.
        • Nimbalkar-Patil S.
        A radiographic measurement technique for crest bone changes related to dental implants.
        J Prosthet Dent. 2015; 113: 350-351
        • Elsyad M.A.
        • Setta F.A.
        • Khirallah A.S.
        Strains around distally inclined implants retaining mandibular overdentures with Locator attachments: an in vitro study.
        J Adv Prosthodont. 2016; 8: 116-124
        • Patil P.G.
        • Seow L.L.
        • Uddanwadikar R.
        • Pau A.
        • Ukey P.D.
        Different implant diameters and their effect on stress distribution pattern in 2-implant mandibular overdentures: a 3D finite element analysis study.
        J Prosthet Dent. 3 June 2022; ([Epub ahead of print])
        • Kutkut A.
        • Rezk M.
        • Zephyr D.
        • Dawson D.
        • Frazer R.
        • Al-Sabbagh M.
        Immediate loading of unsplinted implant retained mandibular overdenture: a randomized controlled clinical study.
        J Oral Implantol. 2019; 45: 378-389
        • Emami E.
        • Cerutti-Kopplin D.
        • Menassa M.
        • Audy N.
        • Kodama N.
        • Durand R.
        • et al.
        Does immediate loading affect clinical and patient-centered outcomes of mandibular 2-unsplinted-implant overdenture? A 2-year within-case analysis.
        J Dent. 2016; 50: 30-36
        • Borges G.A.
        • Costa R.C.
        • Nagay B.E.
        • Magno M.B.
        • Maia L.C.
        • Barão V.A.R.
        • et al.
        Long-term outcomes of different loading protocols for implant-supported mandibular overdentures: a systematic review and meta-analysis.
        J Prosthet Dent. 2021; 125: 732-745
        • Gholami H.
        • Mericske-Stern R.
        • Kessler-Liechti G.
        • Katsoulis J.
        Radiographic bone level changes of implant-supported restorations in edentulous and partially dentate patients: 5-year results.
        Int J Oral Maxillofac Implants. 2014; 29: 898-904
        • Medikeri R.S.
        • Pereira M.A.
        • Waingade M.
        • Navale S.
        Survival of surface-modified short versus long implants in complete or partially edentulous patients with a follow-up of 1 year or more: a systematic review and meta-analysis.
        J Periodontal Implant Sci. 2022; 52: 261-281