{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T13:54:48Z","timestamp":1773842088972,"version":"3.50.1"},"reference-count":30,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2019,2,3]],"date-time":"2019-02-03T00:00:00Z","timestamp":1549152000000},"content-version":"vor","delay-in-days":2,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Clinical Oral Implants Res"],"published-print":{"date-parts":[[2019,2]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To compare clinical and patient\u2010reported outcomes when providing maxillary overdentures on four bar\u2010 and six bar\u2010connected implants placed in the posterior region during a 5\u2010year follow\u2010up period.<\/jats:p><\/jats:sec><jats:sec><jats:title>Materials and methods<\/jats:title><jats:p>Sixty\u2010six fully edentulous patients with functional maxillary denture complaints and insufficient bone volume to allow implant placement were scheduled for a maxillary sinus floor elevation procedure with bone from the anterior iliac crest and randomized to receive either four or six implants in the posterior maxilla and four implants in the mandible. After 3\u00a0months of osseointegration, a bar\u2010supported overdenture was constructed. Maxillary implant survival, overdenture survival, clinical scores, peri\u2010implant bone height changes and patient satisfaction were assessed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Sixty patients completed the 5\u2010year follow\u2010up. Implant survival was 100% in the four\u2010implant group and 99.5% in the six\u2010implant group. No new overdentures had to be made in the four\u2010implant group, and three new overdentures were made in the six\u2010implant group due to excessive wear of the denture base and teeth (90.9% overdenture survival). Clinical parameters did not differ significantly between groups. Mean marginal bone loss compared to baseline was 0.58\u00a0\u00b1\u00a00.51\u00a0mm in the four\u2010implant group and 0.60\u00a0\u00b1\u00a00.58\u00a0mm in the six\u2010implant group, respectively. Overall, patient satisfaction improved significantly, but did not differ between groups.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Following a bilateral maxillary sinus floor elevation procedure, a bar\u2010supported overdenture on four implants in the posterior maxillary region is not inferior to an overdenture supported by six implants after a 5\u2010year evaluation period in patients with functional maxillary denture complaints and marked posterior resorption (Clinical trial registration number: NTR2969).<\/jats:p><\/jats:sec>","DOI":"10.1111\/clr.13403","type":"journal-article","created":{"date-parts":[[2019,1,12]],"date-time":"2019-01-12T16:39:13Z","timestamp":1547311153000},"page":"169-177","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["Four or six implants in the maxillary posterior region to support an overdenture: 5\u2010year results from a randomized controlled trial"],"prefix":"10.1111","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8318-4113","authenticated-orcid":false,"given":"Wim","family":"Slot","sequence":"first","affiliation":[{"name":"Department of Fixed and Removable Prosthodontics and Biomaterials, Dental School University of Groningen, University Medical Center Groningen Groningen the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gerry M.","family":"Raghoebar","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery University of Groningen, University Medical Center Groningen Groningen the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marco S.","family":"Cune","sequence":"additional","affiliation":[{"name":"Department of Fixed and Removable Prosthodontics and Biomaterials, Dental School University of Groningen, University Medical Center Groningen Groningen the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arjan","family":"Vissink","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery University of Groningen, University Medical Center Groningen Groningen the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1702-6031","authenticated-orcid":false,"given":"Henny J. 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