Volume 30, Number 6, 2017 519 ©2017 by Quintessence Publishing Co Inc. Two-Implant–Supported Mandibular Overdentures: Do Clinical Denture Quality and Inter-Implant Distance Affect Patient Satisfaction? Sara A. Alfadda, BDS, MSc (Prosthodontics), PhD, FRCD (C) 1,2 / Mohammad D. Al Amri, BDS, MS (Prosthodontics), FRCD (C) 1 /Amal Al-Ohali, BDS 3 / Arwa Al-Hakami, BDS 4 /Noura Al-Madhi, BDS 5 Purpose: To investigate the following three null hypotheses in patients rehabilitated with a mandibular overdenture supported by two unsplinted implants: (1) patient satisfaction is not related to the clinical quality of the dentures; (2) inter-implant distance (IID) has no effect on the clinical quality of the dentures; and (3) IID does not influence patient satisfaction. Materials and Methods: Forty edentulous patients who were rehabilitated with a two-implant–supported mandibular overdenture participated in the study. Independent investigators evaluated the dentures on the basis of five clinical criteria using the validated Denture Quality Evaluation Form, and the patients completed the validated Denture Satisfaction Scale. Irreversible hydrocolloid impressions of the mandible were made and poured immediately in die stone. The IID was measured by adapting an orthodontic wire to the mandibular alveolar ridge crest, extending from the center of one implant to the center of the other. Spearman correlation analyses were used to identify possible correlations, with a significance level set at P < .05. Results: The clinicians’ overall mean rating of the clinical quality of the dentures was 91.5% (standard deviation 6.27%). The stability of the mandibular overdenture and of the maxillary conventional complete denture was significantly related to satisfaction (r = 0.389 and r = 0.44, respectively). Significant associations were found between the mandibular stability items and satisfaction with both maxillary and mandibular dentures. The stability of the maxillary denture was significantly associated with patient satisfaction with mandibular denture retention, stability, and comfort. None of the 12 denture satisfaction items were significantly associated with IID. Similarly, IID did not have an effect on the quality of either denture in terms of retention, stability, or occlusion. Conclusion: Denture stability was the feature that had the most influence on patient satisfaction with the mandibular overdenture and with the maxillary conventional denture. IID had no effect on the clinical quality of either denture and did not influence patient satisfaction. Int J Prosthodont 2017;30:519–525. doi: 10.11607/ijp.5295 E dentulism is a debilitating and irreversible pre- dicament that can lead to functional and social limitations. 1 In the pre-endosseous implant era, con- ventional complete dentures were the treatment of choice by edentulous patients for more than a cen- tury. However, this treatment modality has often been associated with insufficient stability and retention of the prosthesis. 2 Moreover, even if the dentures were fabricated to meet optimum clinical standards, many patients reported dissatisfaction with their prosthetic treatment. 3,4 Fortunately, the introduction of implant- supported overdentures has effectively addressed most of these patient concerns. 5–10 In vitro studies evaluating the effects of dental im- plant distribution on vertical and oblique dislodging forces on overdentures have reported inconsistent conclusions. 11–13 Clinicians can acknowledge that in a clinical setting, forces exerted on the denture are not perpetually purely vertical or horizontal. Muscle tonus, neuromuscular coordination, and the tongue, cheeks, lips, saliva, and arch relations are biomechan- ical factors that have a dualistic impact on the stability and retention of the denture. 14 In fact, these factors are usually identified during initial clinical examina- tions, and technical procedures are refined accord- ingly to minimize the adverse effects of an unfavorable situation. Accordingly, it seems prudent to account 1 Associate Professor, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. 2 Visiting Professor, Department of Prosthodontics, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada. 3 Professor, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. 4 Teaching Assistant, Department of Maxillofacial Surgery, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. 5 Resident, Department of Operative Dentistry, University of Iowa, Iowa City, Iowa, USA. Correspondence to: Dr Sara A. Alfadda, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, P.O. Box 1914, Riyadh, 11441 Saudi Arabia. Email: salfadda@gmail.com, s.alfadda@utoronto.ca © 2017 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. 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