Effects of repetitive insertion/removal cycles and simulated occlusal loads on retention of denture retainers

Abstract

The purpose of this study was to investigate the effects of repetitive insertion/removal cycle tests on denture retainers with simulated occlusal loads on the retentive force and deformation of clasp. Abutment teeth in the form of mandibular secondary premolars and clasp in the form of Akers clasps were prepared. The retentive force of the clasp on the abutment teeth were evaluated before and after undergoing repetitive insertion/removal cycle tests with or without cyclic loading. Changes in the clasp shape were monitored using a 3D scanner and scanning electron microscope. The initial retentive force was approximately 10 N and this value later decreased due to deformation of the clasp tips. In contrast to the non-load group, the load group exhibited a reduction in retentive force during earlier stages. Therefore, cyclic loading was related to a decrease in retentive forces, specifically in the early stages of repetitive insertion/removal cycles.

Comparison of the fatigue life of pure titanium and titanium alloy clasps manufactured by laser powder bed fusion and its prediction before manufacturing

“…The potential of AM has been reported in many papers [11][12][13] through comparison with casted clasps. However, they are mainly focused on Co-Cr clasps.…”

“…The casting of Co-Cr alloys has been widely used in the medical field [4][5][6]. Several studies have been conducted on the use of AM for the production of Co-Cr clasps, including the evaluation of static bending [7], geometrical accuracy [8,9], surface roughness [9,10], internal porosity [10], and fatigue behavior [11][12][13]. Kato et al [11] measured the retentive force under cyclic loading up to 10 4 cycles, which is a clinically relevant number of cycles.…”

“…Several studies have been conducted on the use of AM for the production of Co-Cr clasps, including the evaluation of static bending [7], geometrical accuracy [8,9], surface roughness [9,10], internal porosity [10], and fatigue behavior [11][12][13]. Kato et al [11] measured the retentive force under cyclic loading up to 10 4 cycles, which is a clinically relevant number of cycles. They found that after 10 3 cycles, the retentive force decreased from 10 N to approximately 6 N and remained approximately constant up to 10 4 cycles.…”

Probabilistic finite element analysis of fatigue life of additively manufactured clasp

“…Therefore, the applied stroke of about 0.25 mm was given in the experiment. The experiments in many studies on the fatigue behaviors are force controlled 18) . Marie et al 21) measured clasp tip distortions as well as the force, and 0.105 mm to 0.319 mm displacement was measured.…”

“…Needless to say, the fatigue behavior is important in the design and evaluation of clasp 17) and therefore experimental studies have been carried out 18) . Behr et al 19) investigated the 10-years survival rate of clasp-retained removal partial dentures and revealed that fracture was observed in clasps for 16.1% of patients, which was almost three times higher than other parts such as connectors.…”