Abstract

In this presentation, we report a case in which two dentures with different designs of magnetic attachments were attached to intermediate missing mandibular molars.

The patient, a 59-year-old male, complained of masticatory dysfunction. After the initial preparation, the distal root of the mandibular right second molar was fitted with a coping magnetic attachment in consideration of its load-bearing capacity as an abutment tooth, and we decided to fabricate an extracoronal magnetic attachment using an EC Keeper Tray (GC, Japan) for the mandibular right first and second premolars.

The definitive denture had the first molar as a homemade metal tooth and the second molar as a hard resin tooth (SR-Orthosit-PE; Ivoclar-Vivadent AG, Liechtenstein). In addition, GIGAUSS (GC) was used for a magnetic attachment (the coping type was the D400), and the D600 was applied to the extracoronal type. One year after the installation of the right denture, in response to the patient's request to use the same magnetic attachment as the right side, the first and second premolars on the left side were equipped with similar extra-crown attachments, and the dentures were made of the same material.

Abstract

In this study, we report on the accuracy of matching of zirconia root plates fabricated using a high-precision laboratory scanner.

The abutment tooth was a preformed root plate-type epoxy artificial tooth (A50-359, NISSIN). The manufacturing procedure involves scanning the work model using a laboratory scanner (E3, 3Shape), modeling it using design software (Dental System, 3Shape), and then cutting it with a milling machine (CORiTEC 350i, Imes-Icore). Five specimens were tested, and the fitting accuracy of the zirconia root plates was evaluated using the cement replica method.

The measurement points are the labial margin at point a, the labial cervix at point b, the labial post at point c, the tip of the post at point d, the lingual post at point e, the lingual cervix at point f, and the lingual margin set as point g. The average gaps were 61.5±32.2 μm at point a, 73.5±32.4 μm at point b, 41.5±11.6 μm at point c, 148.5±19.1 μm at point d, 45.0±11.6 μm at point e, 81.5±27.8 μm at point f, and 46.0±13.3μm at point g.

It was suggested that the zirconia root plate manufactured using a high-precision laboratory scanner could be applied clinically.

Abstract

【Objective】

For clinical success with magnetic attachments, accurate positioning of the magnetic assembly on the keeper and its connection are very important. A hands-on seminar titled “Learning Magnetic Attachments—Laboratory and Clinical Procedures” was held at the 131st Annual Meeting of the Japanese Society of Prosthetic Dentistry, and we will report on this seminar.

【Methods】

In the seminar, a lecture on the characteristics of magnetic attachments and how to proceed with the treatment was given. Using a simulation model and overdenture, training in the clinical procedure of fixing the magnetic assembly to the denture base using auto-polymerized resin was given.

【Results and Discussion】

The seminar was held twice, with a total 40 participants (23 males and 17 females) divided into two groups of 20. Difficulties such as detachment of the magnetic assembly and lack of retentive force were observed during the fixing procedures. Not using metal primers and premature removal of the denture from the simulation model during the polymerization of the resin were considered as reasons for the detachment. The insufficient retentive force may be due to misalignment of the magnetic assembly, namely, an air gap was caused by the intrusion of the resin onto the keeper surface.

Abstract

【Introduction】

Overdenture with magnetic attachments is a prosthetic approach that can restore masticatory ability and provide a highly esthetic appearance, but it is difficult to apply to vital teeth. We will report a case of a partial denture with magnetic attachments applied to the proximal surfaces of the abutment teeth to minimize invasion of the tooth structure.

【Case report】

The patient is 80 years old, female, with remaining mandible teeth #48, #42〜#34, # 38. She was suffering from mastication difficulty and poor esthetics due to metal clasps on the anterior teeth, and she requested the least invasive prosthetic treatment. The mandible removable partial denture (RPD) with magnetic attachments on #42 and #34, cap clasp on #48, and ring clasp on #38 was fabricated. Keepers were fixed to the adjacent surfaces of the abutment teeth using composite resin, and magnetic assemblies were placed in the proximal plates of the RPD.

【Discussion/conclusion】

Magnetic attachments were applied to the proximal surfaces of the teeth, which improved the esthetic and was a minimally invasive treatment. The patient was fully satisfied with the esthetics and the assurance of adequate retentive force.

Abstract

Dental magnetic attachments are mostly paired combinations of magnetic assembly and keeper or two magnets. A combination of two magnetic assemblies is rare. In this study, we investigated retentive force characteristics of a set of two sandwich-type magnetic assemblies. Mating surfaces of two oval-shaped magnetic assemblies (Magfit EX600W) were placed in contact with different polarities facing each other. The pair was mounted on a measuring device and retentive force experiments conducted as specified in ISO 13017. The measurements were done with the two magnetic assemblies aligned and when one magnetic assembly was displaced along the long axis then short axis direction. The retentive force of a pair of magnetic assemblies was higher than that of magnetic assembly combined with keeper. There was a decline in retentive force measured upon separation of mating faces. It was more gradual in the case of two magnetic assemblies compared to assembly and keeper. Displacement along the minor axis, caused a decline in retentive force which was more in a pair of magnetic assembly compared to a magnetic assembly paired with keeper. Furthermore, a pair of combined magnetic assemblies generated a large restoring force against displacement. It was established advantageous to combine two magnetic assemblies.