Effect of Splinting and Stress Directors in Attachment-retained Removable Dentures

Objectives: Precision attachments impose relatively high stresses on supporting structures. Splinting teeth and/or implementing stress directors are the possible solutions. The aim of this study was to evaluate the effect of splinting and stress directors on radiographic, clinical and patient-centered outcomes.
Methods: This randomized prospective study included initially 48 patients. Participants were mandibular Kennedy class I cases randomized into 3 groups. In groups 1 (GP1) and 2 (GP2) the two last-standing teeth were prepared to receive a 2-unit fixed splint. In group 3 (GP3) only the last standing tooth received a single crown. Resilient extracoronal precision attachments were used to retain RPDs of GP2 and GP3, while the rigid variety was used in GP1. Participants were recalled annually for a follow up period of 5 years. Assessed parameters were: bone density and height around abutments and in the residual ridge area, probing depth, plaque and gingival indices, maintenance requirements and patient satisfaction. Kolmogorov–Simrnov, ANOVA, Duncan, Kruskal Wallis and Dunn statistical tests were used. Statistical significance was set at p<0.05.
Results: After 5-years follow-up, GP1 showed the most favorable results in all assessed parameters (p<0.01). None of the abutments were extracted. All periodontal parameters were better in GP1 in comparison to GP2 and GP3. Gingival recession, root caries, patrix activation and replacement and need for denture relines were more pronounced in GP2 and GP3. GP2 showed better radiographic outcomes around abutments in comparison to GP3 (p<0.05) but differences in residual ridge were insignificant. Differences in patient satisfaction were insignificantly different in the initial 2 years but then were significantly lower in GP2 and GP3 (p<0.01).
Conclusions: Splinting abutments is more important than the use of stress directors in improving treatment outcomes with attachments. Resilient attachments might compromise periodontal condition of abutments and increase residual ridge resorption.