Evaluation of volumetric wear of abutments on the retention loss of ball attachment systems in implant-retained overdentures: An in vitro study.

BACKGROUND: There is a lack of studies evaluating the wear of the male components of the ball attachment systems of implant-retained overdentures. PURPOSE: The purpose of this study was to compare the volumetric wear patterns four commercially used ball abutments. MATERIALS AND METHODS: Forty-eight identical polyethylene and acrylic blocks were fabricated and four groups consisting of 12 polyethylene blocks with two implants and 12 acrylic blocks, which were used as overdentures, were generated (two groups with plastic females, one group with gold and one group with titanium females). Every specimen underwent 5000 insertion and removal cycles (~4.5 years) and retention forces were measured. For the evaluation of volumetric wear, all the ball abutments were scanned before and after the 5000 cycles using a three-dimensional scanner and the data were analyzed using the software supplied by the manufacturer. RESULTS: Statistically significant retention force differences were observed between the groups at each cycle (P < .05). Among the four groups, retention force was lowest in the group with titanium females (5.59 ± 2.27) and highest in the group with gold females (43.0 ± 6.3) at the end of 5000 cycles. Statistically significant dimensional changes in the male components were observed between the groups (P < .05). Volumetric losses were 11%-13% in Group I and II, 1% in Group III, and 25% in Group IV. Group III showed significantly lower volumetric wear whereas Group IV showed significantly higher volumetric wear than all the other groups (P < .001). No significance was detected between Group I and II (P > .05). CONCLUSION: Within the limitations, it can be concluded that although clinical studies are needed to ensure the findings of the present study, due to severe retention loss and volumetric abutment wear, ball attachments with titanium female components should be used with caution.

Comparison of patient satisfaction, quality of life, and bite force between elderly edentulous patients wearing mandibular two implant-supported overdentures and conventional complete dentures after 4 years.

This study compared two groups of patients who were elderly and edentulous, one group included subjects who had mandibular overdentures supported by two implants (Group I); the other groups wore conventional complete dentures (Group II). This retrospective study included 100 edentulous patients (50 from each group) with an average age of 67.86 years, who had been followed for 4 years. The groups were compared in terms of patient satisfaction, quality of life (QOL), and bite force. The bite force and patient satisfaction scores of Group I were found to be statistically significantly higher than Group II (p < .05). However, no statistically significant difference was found between the two groups' QOL scores (p > .05) except on the physical pain subscale (p = .013). Based on these results, it can be concluded that after 4 years of function, subjects wearing mandibular overdentures supported by two implants had higher values for bite force and patient satisfaction scores, but similar QOL scores when compared to conventional complete denture-wearers.