Abstract
The purpose of this in vitro study was to investigate
the effect of hardness on the reduction of
stress transferred to tissues around implants
using a resilient material applied to the female
parts of the ball attachment in maxillary implant
overdentures. A cast chrome-cobalt framework
was mounted onto a maxillary acrylic edentulous
model, which contained two implants and four
strain gauges attached to the implant. Ball abutments
were screwed into the implant. One abutment
was connected to a dedicated metal cap
embedded in the housing, while the others were
connected to resilient test materials with four different
hardnesses. Loads were applied using a universal
testing machine with a magnitude of 50 N.
The sums of the absolute values recorded from the
four strain gauges were used for stress evaluation.
The measured strains were analyzed statistically
using two-way ANOVA and multiple comparisons. A
resilient material with hardness 90 exhibited
strains that did not differ significantly from the control.
In contrast, the other resilient materials
showed significantly reduced strains under all
conditions. In this limited study, application of
resilient silicone materials with approximate hardness
80 to the female parts of ball attachments significantly
reduced the stress on the tissues
around the implant.
