Study On Retentive Force And Deformation Of Acetal Resin Clasp

Compared to traditional metal clasp, resin clasp can ensure the functionality and greatly enhance the aesthetics of removable partial denture, which has broad application prospects in the dental clinic. However, in our country biomechanical research of resin clasp has just been begun, lacking comprehensive and systematic study on its mechanical properties variation in the clinical practical application. This study took acetal resin clasp as research object, by applying experimental mechanics, focused on the change trend of the retentive force and deformation of clasps with different cross-section diameters,undercuts and abutments of different materials in the cycle of repeated dislocations.By the comparative analysis between acetal resin clasps and cobalt chromium alloy clasps under the same experimental conditions, we recognized the mechanical differences between the two kinds of materials, revealed the selection basis for appropriate choice of the undercut when acetal resin clasp was applied in clinical.The major findings are as follows:With the increasing length of cross-sectional diameter and the increasing depth of abutment undercut, the value of acetal resin clasps'retentive force becomes larger. As acetal resin clasp has lower modulus of elasticity and good flexibility, whose rigidity is also smaller than Co-Cr alloy clasps, such characteristics allow the retentive arm of acetal resin clasps could enter deeper undercut than that of Co-Cr alloy with smaller torque and side force to abutments.It's suitable for acetal resin premolar clasps to be of 2.00mm diameter and 0.75mm undercut. When the abutments and periodontal conditions were in poor health, acetal resin premolar clasps of 2.00mm diameter and 0.50mm undercut were appropriate.The results also proved that, after 2880 times simulated clinical dislocation, Co-Cr alloy clasps showed a clear deformation while acetal resin clasps had no significant deformation(p>0.05)The retentive force of acetal resin clasps with deeper undercut has better flexibility and fatigue resistance than the Co-Cr alloy clasps, although the retentive force of the former was in general lower than the later. Although the retentive force of acetal resin clasps was in general lower than that of the Co-Cr alloy clasps, it has better flexibility and fatigue resistance with deeper undercut. So acetal resin clasps can be applied in clinical as the meaningful supplements of Co-Cr alloy clasps.