Aim; this in vitro study was conducted to evaluate the effect of mechanical loading on different denture base materials on supporting structures
materials and methods: a total of four implant retained overdentures were used in this study divided into two groups , first group ; conventional acrylic overdenture (PMMA) and flexible acrylic overdenture on two polyetheretherketon"PEEK" implants)and second group conventional acrylic overdenture (PMMA) and flexible acrylic overdenture, supported by two implants each ( two Titanium implants) were placed in epoxy resin casts at the canine area using a surgical guide. Soft liner material was used at the distal extension area to mimic the soft tissues.
Two linear strain gauges were bonded buccal and lingual to each implant to measure the peri-implant strains during unilateral and bilateral loading.
Results: during bilateral loading the highest strain values were recorded with the flexible acrylic overdenture with PEEK implants, while the lowest strain values were recorded with the conventional acrylic overdenture with titanium implants. During unilateral loading, the highest strain values in the loading side were also demonstrated with the flexible overdenture with PEEK implants, and the lowest strain values were observed with the conventional acrylic overdenture with titanium implants.
Conclusion: within the limitations of this in vitro study, flexible overdenture retained by PEEK implants was found to transmit more occlusal stresses at the marginal bone area than the other materials.