Effects of repetitive insertion/removal and occlusal load on the retentive force of rest plate-I bar clasps made by selective laser melting.

The objective of this study was to investigate the effects of repetitive removal/insertion and a load equivalent to the occlusal force on the retentive force of rest plate-I bar (RPI) clasps fabricated by selective laser melting (SLM) on powder bed fusion. RPI clasp fabricated by SLM and casting were evaluated to the retentive force by repetitive removal/insertion (SLM-RI and Cast-RI), and the retentive force of RPI clasp by SLM was also evaluated by repetitive removal/insertion under load (SLM-L). SLM-RI group was kept superior retentive force during repetitive removal/insertion than Cast-RI group.

Comparison Between Interocclusal Registration Using Silicone Bite Registration Material and Intraoral Scanner on Clenching Strength.

Purpose: To clarify the influence of clenching strength on interocclusal registration using an intraoral scanner (IOS).

Materials And Methods: The study includes eight volunteers as subjects, and the two experimental conditions were light clenching (LC) and 40% maximum voluntary clenching (MVC). Conventional silicone bite registration and an IOS were used for comparison.

Effects of hollow structures added by selective laser sintering on the mechanical properties of Co-Cr alloy.

Purpose: This study investigates the effects of hollow structures, added by selective laser sintering (SLS), on the mechanical properties of a Co-Cr alloy for providing an optimal structural property to the framework components of removable partial dentures (RPDs).

Methods: The specimens produced using the 3D data of the dumbbell-shaped cylinders were divided into four groups based on the manufacturing method: Cast, Mill, SLS-solid, and SLS-hollow. Tensile tests were performed to measure the mechanical properties of the specimens.

A new proposal for improving the accuracy of intraoral scanning for partially edentulous residual ridge.

Purpose This study investigated the usefulness of a newly proposed intraoral scanning method, using markers that can be used directly in the oral cavity, in order to improve the accuracy of impression taking of the residual ridge for fabrication of removable partial dentures.Methods An intraoral scanner was used to scan a dental model of a partially edentulous mandibular arch (Kennedy Class I). As markers, pieces of dried pasta were used.

Digital technology for fabrication of removable dental prosthesis with double crowns combining fiber-reinforced composite and zirconia.

Patients: This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using digital technology. An 83-year-old woman presented with gingival swelling around the maxillary right premolar. The swollen tooth was the abutment tooth of a cross-arch fixed partial denture.

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

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.

Trueness and precision of digital impressions obtained using an intraoral scanner with different head size in the partially edentulous mandible.

Purpose: It remains unclear whether digital impressions obtained using an intraoral scanner are sufficiently accurate for use in fabrication of removable partial dentures. We therefore compared the trueness and precision between conventional and digital impressions in the partially edentulous mandible.

Methods: Mandibular Kennedy Class I and III models with soft silicone simulated-mucosa placed on the residual edentulous ridge were used.

Evaluation of the rigidity of dentures made of injection-molded materials.

Dentures made of 2 different types of injection-molded thermoplastic resins (polyamide resin and polyester resin) and a denture made of conventional heat-polymerized resin were used to create an experimental model of a mandibular molar region with a two-tooth gap. In the experimental model, a force of 100 N was applied onto the mesial fossa of the first molars of the dentures, and comparisons were performed by measuring the pressure applied under the denture base and the subsidence rate of the denture. The polyamide resin denture showed the highest subsidence, exerted the highest pressure on the underlying mucosa, and showed significant differences with the other types of dentures.

Reproducibility of probing depth measurement by an experimental periodontal probe incorporating optical fiber sensor.

Background: An experimental periodontal sensor probe (SP) equipped with an optical fiber for recording function was developed. The aim was to test the intraexaminer reproducibility of probing using the SP and to assess the consistency with the manual probe (MP).

Methods: The SP was assembled with an external sheath covering the probe tip of an MP.

Influence of removable partial dentures on the formation of dental plaque on abutment teeth.

Purpose: This study aimed to clarify the relation between the shape of the retainers and the plaque formation on abutment teeth to improve the denture design.

Methods: This study observed the buccal surface for the clasps and distoproximal surface for a guide plate of the mandibular first premolar which was the abutment tooth with a direct retainer of a distal extension RPD. The buccal surface was observed in 10 subjects and the distoproximal surface in 14 subjects.