Comparison between Integrated and Parallel Interlock Designs of an Extracoronal Attachment-retained Distal Extension Removable Partial Dentures: A Clinical Trial

OBJECTIVE: Precision attachments may exert unfavorable stresses on abutments in distal extension bases. This study compared between two reciprocation designs in attachment removable partial dentures (RPDs). MATERIALS AND METHODS: Fourteen patients were allocated into two groups. Each patient received an attachment-retained RPD with one of the two types of attachments being studied. Group I received the integrated interlock type of reciprocation and group II received the parallel interlock type. Abutments were examined for modified plaque index, modified bleeding index, periodontal probing pocket depth, clinical attachment level, and modified papillary bleeding Index. RESULTS: Comparisons of periodontal parameters between mesial and distal abutments within each group revealed no statistically significant difference. Means of these parameters were used for the comparisons. There was a significant difference at P < 0.05 in all parameters between the two groups at time of insertion and at 3, 6, and 9 months of follow-up with values of group (II) higher than group (I). CONCLUSION: RPDs of both designs showed an increase in periodontal parameters. Integrated interlock design showed better scores. It is preferable to use the attachment-retained RPD with integrated interlock instead of parallel interlock design.