Microbiological and clinical outcomes and patient satisfaction for two treatment options in the edentulous lower jaw after 10 years of function

Background: Long-term data on microbiological and clinical outcome as well as on patient satisfaction after implant therapy in the edentulous mandible are limited. Especially comparisons between fixed full prostheses (FFPs) and overdentures (ODs), or between anchoring systems for the latter are scarce. Aim: This study aimed to evaluate both of these parameters at the 10-year follow-up in a group of fully edentulous patients rehabilitated via an OD or a FFP (the latter to allow inter-group comparison). Material and methods: A total of 37 fully edentulous patients (25 ODs, 12 FFPs, age at implant installation ranged from 36 to 85 years) participated in this study. All subjects received their implants (Branemark System(®), Nobel Biocare AB, Gothenburg, Sweden) 10 years previously. For the ODs different attachment systems (bar, magnets, ball) had been applied that allowed a further intra-group comparison. At the follow-up visit, 10 years after the abutment insertion, a series of periodontal parameters were recorded, long-cone radiographs were taken and subgingival plaque samples were collected for analysis using checkerboard DNA-DNA hybridization. The clinical and radiographic data were recorded at abutment connection and after 1 and 10 years. Results: After 10 years of loading, mean plaque and bleeding indices and changes in attachment or marginal bone level were not significantly different, neither between the OD and FFP group, nor within the OD group. The marginal bone loss between abutment connection and year 10 was 0.86 and 0.73 mm for OD and FFP groups, respectively. The subgingival microbiota at implant sites from all (sub)-groups was comparable, with low numbers of DNA counts (± 10 x 10(5)) but high detection frequencies of Actinobacillus actinomycetemcomitans (> 90%), Porphyromonas gingivalis (> 85%) and Tannerella forsythensis (30%). The composition of the subgingival microbiota was influenced by probing depth and bleeding tendency. Patient satisfaction was very high for both types of prosthetic rehabilitation. The FFP group scored only slightly better for chewing comfort and general satisfaction. Conclusion: These data indicate that from the clinical and microbiological standpoint, as well as patient satisfaction, both an OD and a FFP offer a favourable long-term outcome.