Purpose: The purpose of this study was to investigate survival rates and periodontal indices of the implants used in implant assisted removable partial dentures (IARPDs). This study also aimed to analyze the factors that influence the survival rate and periodontal indices. In addition, complications related to IARPDs were investigated clinically.

Materials and methods: A retrospective clinical study was carried out for 21 patients (9 men, 12 women), mean age of 66.6, who were treated with IARPDs. The 58 implants used in the IARPDs were applied to two modalities; 41 implants were for clasp retained abutments, and 17 were for overdenture abutments. Survival rates and periodontal indices (plaque index, calculus index, mucositis index, bleeding index, probing depth, marginal bone loss) of total 58 implants were investigated clinically and radiographically. They were analyzed statistically with regard to the factors: treatment modality, implant’s location, Kennedy classification, opposing dentition, implant connection type, and implant’s diameter. Lastly, complications associated with the IARPDs were investigated and summarized.

Results: The average follow-up period of the 58 implants was 47.9 months (minimum 12 to maximum 185 months). The survival rate of total 58 implants was 93.1%; of these, the survival rate of 41 clasp retained implant abutments was 95.1%, while that of 17 overdenture implant abutments was 88.2%. Among the clasp retained implant abutments, the significant difference (p<.05) of the survival rate was observed when regular diameter implants (survival rate 100%) were used compared to when narrow (survival rate 88.9%) or wide (survival rate 87.5%) were used. Regarding the periodontal index, there were higher mucositis and bleeding indices of the overdenture implant abutments compared to clasp retained implant abutments (p<.05). Plaque index was higher for mandibular implants compared to maxillary implants (p<.05). The Kennedy class IV implants had higher plaque index compared to the implants in class I or II (p<.05). Plaque index was also higher for implants with opposing removable denture (complete denture or RPD) compared to natural teeth or fixed prosthesis as opposing teeth (p<.05). The marginal bone loss was severe for Kennedy class I implants than class III (p<.05). The most frequent complication was dislodgement of clasp retained crown due to cementation failure, while attachment replacement due to wear was most common for overdenture abutment.

Conclusion: The survival rate of the implants used in IARPDs was 93.1% (clasp retained implant: 95.1%, overdenture implant: 88.2%). IARPDs and their implants functioned without critical complications throughout the period.