Clinical Outcomes of Posterior Implants with Surveyed Crowns for Implant-Assisted Removable Partial Dentures: A Retrospective Study.

Purpose: To evaluate the clinical outcomes of posterior implants with surveyed crowns in implant-assisted removable partial dentures (IARPDs). Materials and Methods: Internal-connection implants were inserted and restored with surveyed crowns at the most posterior molar regions of Kennedy class I or II in partially edentulous patients between 2007 and 2018. IARPDs were fabricated and functioned with or without clasps on the surveyed implant crowns. Clinical outcomes of biologic problems, mechanical problems, and marginal bone loss (MBL) through periapical and panoramic views were recorded and measured. The effects of sex, Kennedy classification, opposing dentition, and clasp existence on MBL were analyzed using Mann-Whitney test, and the implant length, crown-to-implant (C/I) ratio, and function period on MBL were analyzed using a multiple regression analysis at α = .05. Results: A total of 32 posterior implants were restored with a surveyed crown for IARPDs in 16 patients (7 men, 9 women; mean age: 69.3 ± 6.0 years). A total of 15 IARPDs were for the mandible (1 maxilla), and 13 were Kennedy class I (3 class II) before implant insertion. All internal-connection implants (15 bone-level and 17 tissue-level) with 7-mm (n = 12), 8.5-mm (n = 18), and 9-mm (n = 2) lengths were restored for 3 surveyed premolar crowns and 29 molar crowns (15 first molar and 14 second molar). The mean C/I ratio was 1.48. The mean function period of the implants was 60.9 ± 40.2 months (range: 14 to 155), and the mean MBL was 0.11 ± 0.36 mm. Only Kennedy class II showed significantly more MBL (P = .002). The implant survival and success rates were 96.9% and 90.6%, respectively. Conclusion: Within the limitations of this retrospective clinical study, mainly in mandibular IARPDs, implants with surveyed crowns showed high survival and success rates during short- to medium-term functions. Posterior implants with surveyed crowns appear to be a reliable alternative for free-end removable partial denture (RPD) patients.