The influence of resilient liner and clip attachments for bar-implant-retained mandibular overdentures on opposing maxillary ridge. A 5-year randomised clinical trial

This study aimed to compare the influence of resilient liner and clip attachments for bar-implant-retained mandibular overdentures on opposing maxillary ridge after 5years of denture wearing. Thirty edentulous male patients (mean age 625years) received two implants in the anterior mandible after being allocated into two equal groups using balanced randomisation. After 3months, implants were connected with resilient bars. New maxillary complete dentures were then constructed, and mandibular overdentures were retained to the bars with either clips (group I, GI) or silicone resilient liners (group II, GII). The prosthetic and soft tissue complications of the maxillary dentures were recorded 6months (T-6m), 1year (T1), 3years (T3) and 5years (T5) after overdenture insertion. Traced rotational tomograms were used for measurements of maxillary alveolar bone loss. The proportional value between bone areas and areas of reference not subject to resorption was expressed as a ratio (R). Change in R immediately before (T0) and after 5years (T5) of overdenture insertion was calculated. Maxillary denture relining times and frequency of flabby anterior maxillary ridge occurred significantly more often in GI compared with GII. The change of R in anterior part of maxilla was significantly higher than change of R in posterior part in both groups. GI showed significant resorption of anterior residual ridge compared with GII. Relining times and frequencies of flabby ridge were significantly correlated with change in R. Within the limitations of this study, resilient liner attachments for bar-implant-retained mandibular overdentures are associated with decreased resorption and flabbiness of maxillary anterior residual ridge and fewer maxillary denture relining times when compared with clip attachments.