Retention force dynamics of two different soft liners over ball abutments for mandibular implant overdentures

There is a lack of clear evidence on the use of auto-polymerizing and temperature activated softliners as attachments for implant overdentures for the elderly patients. This study was conducted to comparatively evaluate the initial and reduced retention force of two different soft liners over ball abutments for mandibular implant overdentures. Two implants corresponding to 33 and 43 (mandibular left and right canine, FDI notation) placed in a mandibular edentulous heat cure master model with ball abutmIents of 3mm diameter and 0.5 mm collar height. Overdentures processed in the heat activated denture base resin and divided into three groups of group A (n=15), group B (n=15), and group C (n=15). Group A-lined with Ufi-gel P followed with group B lined with Molloplast B and group C polymerized with plastic caps. Each of 45 denture bases subjected to initial retention force and reduced retention force testing after 3,348 cycles using a servohydraulic testing machine. The dual recess areas and the soft liner bonded to the denture base observed with a stereomicroscope both before and after 3,348 cycles. Statistical analysis performed using ANOVA Kruskal Wallis test and Wilcoxon signed-rank test. There were insignificant differences (P>0.05) in the mean rank values of all the three groups for reduced retention force after 3,348 cycles and percentage reduction in force. There were significant differences in all the three groups between initial retention force and reduced retention force after 3,348 cycles (P<0.05). Both the liners could be used as attachments for mandibular implant overdentures over the three year simulation period.