title: Mandibular overdentures supported by two or four endosseous implants. A 5-year prospective study.
abstract: OBJECTIVE
  The aim of this 5-year prospective comparative study was to evaluate treatment outcome (survival rate, condition of hard and soft peri-implant tissues, patient satisfaction, prosthetic and surgical aftercare) of mandibular overdentures supported by two or four implants.
  
  
  METHODS
  Sixty edentulous patients with a mandibular height between 12 and 18 mm participated. Thirty patients were treated with an overdenture supported by two IMZ implants (group A) and 30 patients were treated with an overdenture supported by four IMZ implants (group B). Standardised clinical and radiographic parameters were evaluated 6 weeks after completion of the prosthetic treatment and after 1, 2, 3, 4 and 5 years of functional loading. Prosthetic and surgical aftercare was scored during the evaluation period.
  
  
  RESULTS
  One implant was lost (group A) during the healing period. There were no significant differences with regard to any of the studied clinical or radiographic parameters of the peri-implant tissues between the groups. None of the patients reported sensory disturbances in the lip or chin region. No differences in satisfaction were observed between the groups. With regard to aftercare, there was a tendency of a greater need of prosthetic interventions in group A, while correction of soft-tissue problems was restricted to patients of group B.
  
  
  CONCLUSIONS
  There is no difference in clinical and radiographical state of patients treated with an overdenture on two or four implants during a 5-year evaluation period. Patients of both groups were as satisfied with their overdentures.
authors.affiliation: Department of Oral and Maxillofacial Surgery and Maxillofacial Prosthodontics, Groningen University Hospital, PO Box 30.001, NL-9700 RB Groningen, the Netherlands. a.visser@kchir.azg.nl
authors.forename: Anita
authors.initials: A
authors.lastname: Visser
authors.forename: Gerry M
authors.initials: GM
authors.lastname: Raghoebar
authors.forename: Henny J A
authors.initials: HJ
authors.lastname: Meijer
authors.forename: Rutger H K
authors.initials: RH
authors.lastname: Batenburg
authors.forename: Arjan
authors.initials: A
authors.lastname: Vissink
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000209:etiology; D003758:Dental Implantation, Endosseous; D015921:Dental Implants / Q000009:adverse effects; D003774:Dental Plaque Index; D019094:Dental Prosthesis, Implant-Supported / Q000523:psychology; D019232:Dental Restoration Failure; D003828:Denture, Overlay; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging / Q000534:rehabilitation; D008297:Male; D008334:Mandible; D008875:Middle Aged; D017060:Patient Satisfaction; D010512:Periodontal Index; D011182:Postoperative Care; D011446:Prospective Studies; D011859:Radiography; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires
chemical_list: D015921:Dental Implants