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This position paper proposes a definition and naming standard for removable partial dentures (RPDs) using thermoplastic resin, and presents a guideline for clinical application. A panel of 14 experts having broad experience with clinical application of RPDs using thermoplastic resin was selected from members of the Japan Prosthodontic Society. At a meeting of the panel, “non-metal clasp denture” was referred as the generic name of RPDs with retentive elements (resin clasps) made of thermoplastic resin. The panel classified non-metal clasp dentures into two types: one with a flexible structure that lacks a metal framework and the other having a rigid structure that includes a metal framework. According to current prosthetic principles, flexible non-metal clasp dentures are not recommended as definitive dentures, except for limited cases such as patients with a metal allergy. Rigid non-metal clasp dentures are recommended in cases where patients will not accept metal clasps for esthetic reasons. Non-metal clasp dentures should follow the same design principles as conventional RPDs using metal clasps.

Background The aim of the present study was to evaluate the physical properties of “admixture paste”, which is a commercially available gel containing hinokitiol for use against severe stomatitis, and its characteristics as a moisturizing gel and denture adhesive. Methods The admixture paste, which contained dexamethasone (Dexaltin®), gel for oral care (Refrecare H®) and petrolatum, and its 3 components, either alone or in different combinations, were subjected to viscosity, adhesiveness and elution testing to compare their physical properties. Viscosity was measured with a stress-controlled rheometer. Adhesive force was measured by tension test. Elution under a simulated oral environment was evaluated by monitoring with a fixed-point camera and absorbance. Both adhesiveness and elution were evaluated every hour for 6 h. A linear mixed-effects model was used to assess differences in the time course of elution between samples. In 3 og-rank test was used to compare time to elution into saliva among samples. Results The results of viscosity testing demonstrated that the admixture paste had similar viscosity to cream-type denture adhesives and this was temperature independent. In the adhesiveness tests, the admixture paste showed stronger adhesiveness than that of cream-type denture adhesives. In the elution test, the admixture paste demonstrated gradual dissolution and apparent temporal changes for 6 h in a simulated oral environment. Conclusions The results of the present study demonstrated that the admixture paste has adhesive force similar to those of denture adhesives and good local retention in saliva, and that it might be suitable for therapeutic use in patients with severe stomatitis derived from radiotherapy and/or chemotherapy for cancer. Electronic supplementary material The online version of this article (10.1186/s12885-018-4017-2) contains supplementary material, which is available to authorized users.

This paper describes the computer simulation of irradiation growths induced by neutron irradiations in zirconium using a combination of Molecular Dynamics (MD) and Kinetic Monte Carlo (KMC) methods. First, we performed the MD simulation of the displacement cascade on a defect cluster to study the interaction between the defect cluster and the displacement cascade. The MD simulations provide a lot of information on the amount of the defect production and the subsequent morphological change in the defect cluster. The results are used to make simple models that describe the nature of the displacement cascade overlap on the defect clusters. The models are then implemented into the KMC simulation code to extend the length- and time-scale of the simulation, which allows us to evaluate directly the defect cluster accumulations during a long-term irradiation. The irradiation growth strain resulting from the defect cluster accumulations is simply evaluated, and compared to an available experimental data. The comparison suggests that the displacement cascade overlap plays an important role on the irradiation growth, and, consequently, the KMC method with the simple models must be appropriate for the simulations of the irradiation growth.

Patient: A 73-year-old male patient was introduced by his plastic surgeon to the Kyushu Dental College Hospital. Numerous surgical excisions resulted in a defect in the region of the right upper palate. He also had a skin defect on the right cheek due. Although he had worn a removable partial denture and a facial prosthese, he had been complaining of mastication, articulation, and esthetic problems. Seven inner crowns with keeper of magnetic attachment were fixed to the abutment teeth. Metal welding was done between the outer crowns and metal frame. Magnetic assemblies were fixed into the outer crowns. Four magnetic attachments were applied to connect the partial denture and the obtulator. Two magnetic attachments were also applied to connect the facial prosthese and the obtulator.Discussion: Although the new maxillofacial prosthese was heavier than the old one, the VAS score of the patient’s satisfaction was 100. An articulation, masticatory function, and mealtime were improved.Conclusion: This clinical report describes the fabrication method for a maxillofacial prosthese by applying dental magnetic attachments for retention and connection. The evaluation of mastication and articulation was done before and after wearing the new prosthese and his complaining improved.

Background/aims: Ozone is known to act as a strong antimicrobial agent against bacteria, fungi, and viruses. We examined the effect of ozonated water on Candida albicans on acrylic denture plate. Methods: The heat-cured acrylic resins were cultured with C. albicans. After treatment of flowing ozonated water, the number of attached C. albicans was counted. In some experiments, the test samples were treated with ozonated water in combination with ultrasonication. Results: After exposure to flowing ozonated water (2 or 4 mg/l) for 1 min, viable C. albicans cells were nearly nonexistent. The combination of ozonated water and ultrasonication had a strong effect on the viability of C. albicans adhering to the acrylic resin plates. There were no significant differences in antimicrobial activity against C. albicans between plates immersed in ozonated water with ultrasonication and those treated with commercially available denture cleaners. In addition, electron microscopic analysis revealed that small amounts of C. albicans remained on the plate after exposure to flowing ozonated water or immersion in ozonated water with ultrasonication. Conclusion: Our results suggest that application of ozonated water may be useful in reducing the number of C. albicans on denture plates.

Purpose: The purpose of this study was to evaluate the relationship between either craniofacial or systemic symptoms and the gravity fluctuation area.Materials and Methods: One hundred and five volunteers (72 males and 33 females; mean age 24.4±4.0) without symptoms of temporomandibular joint disorders (TMD) were examined for craniofacial and systemic symptoms (14 items); the subjects' gravity fluctuation areas were also measured. The volunteers were divided into six groups according to the range of their gravity fluctuation area. The relationship between the symptom score and gravity fluctuation area was thus evaluated.Results: The mean craniofacial and systemic symptom score was 0.8±1.5. The mean symmetrical conditions score was 3.3±1.0, and the mean TMD symptoms score was 1.6±1.3.Conclusion: No significant difference was observed between the craniofacial or systemic symptoms score and the gravity fluctuation area; however, the groups with a large gravity fluctuation area did tend to develop dizziness, headache, lumbago, masseter muscle pain, and malocclusion.

The General Dentistry Clinic of Kyushu Dental College Hospital is a newly established (July, 1999) dental clinic, designed for training residents to become competent general practitioners who can provide comprehensive, state-of-the-art dental care. Actually, General Dentistry Clinic started its training program with only two residents just last year. Starting in 2006, all the graduate students who pass the National Board of License Examination must undergo training at the teaching Hospitals for one year. The purpose of this study is to evaluate whether there are sufficient new-patients or not, thus providing residents opportunity to advance their knowledge and clinical skills focussing on conservative dentistry, prothetic dentistry and oral surgery.At this time there are enough cases for training small groups of residents. With the increase in numbers of residents in the near future, efforts should be made to increase the number of new-patients for training, expecially in oral surgery. Further studies should be done to predict the capacity of General Dentistry Clinic for Post-Graduate Clinical Traning Course.

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.

One hundred thirty-four dentures with reinforced polycarbonate resin (PC), utilizing a compression molding method called the Sumipuroi Denture System, were inserted into 82 partially or completely edentulous patients at the clinic of Kyushyu Dental College. Continuous clinical observation of the dentures was conducted from approximately four months to two yesrs after insertion.The results were as follows:1. No fractures or stress cracks were found in the denture bases except for one denture base which had been repaired with auto-polymerized acrylic resin at the first insertion.2. Artificial tooth loss was seen in 6 cases, which were all plastic anterior teeth with high wear resistance. Stain penetration into the interfaces between the plastic teeth and the PC denture base was also seen in some cases.3. Not a single tooth fell from the denture bases because the PC denture base had excellent adhesion to conventional acrylic resin teeth even without the creation of mechanical retentive shapes and/or the use of any chemical bonding agents on the teeth.4. No troubles due to shrinkage of denture base and dimensional change of artificial teeth caused by the molding of the PC denture was found during clinical observation.

Objectives: The condition of dry mouth is an influential factor in the incidence of caries, periodontal disease, fungal infections, masticatory dysfunctions and denture function. Bedridden elderly and disabled persons often suffer from oral dryness and the aim of this study was to evaluate the usefulness of measuring the amount of moisture in the oral mucosa for clinical diagnosis of dry mouth in this group. Subjects and methods: The subjects were 20 elderly bedridden individuals, age range 65–89 years old, living in a nursing home and six healthy laboratory researchers, aged 20–46 years old, used as controls. Tongue dorsum moisture measurements were performed using a newly developed wetness tester (L-SALIVO®), in which the wet portion was measured after 10 s. Further, clinical diagnosis of dry mouth was carried out using a clinical classification scale of the tongue mucosa (grade range, 0–3). Results: It was possible to measure tongue dorsum moisture in all subjects with the wetness tester. The average moisture value was 0.1 ± 0.2 mm in elderly subjects with a dry mouth grade of 2 (n = 8) or 3 (n = 12), while the average moisture value in the control subjects was 3.67 ± 1.75 mm with a dry mouth grade of 0 (n = 4) or 1 (n = 2). Tester values and clinical classification showed a positive co-relationship (r = 0.31, p

The purpose of this study was to investigate the retentive force distribution of the upper overlay denture with magnetic attachments.The magnetic attachment used in this study consisted of a magnetic assembly and a magnetizable metal commonly refered to as a keeper.The keepers were attached to the bilateral canine and/or second molar regions on the upper edentulous model, while magnetic assemblys were attached to the upper denture which was made of an acrylic resin.The retentive force was measured by pulling at eight locations on the denture vertically with a tensile testing machine.The results were as follows:1.The retentive force was greater at locations near the magnetic attachments and decreased at locations further away from magnetic attachments.2.In the case with two magnetic attachments, the retentive force distribution was more influenced by the arrangement of attachments than other cases.3.The denture with three or four attachments showed stable retentive force distribution.4.The maximum retentive force was smaller than the total attractive force, which was 40-70%.

The excellent success through many implant systems such as the osseointegrated and others have been directed toward reducing the interest and research effort for removable prosthesis over the past few years.The need to improve the quality of removable partial dentures through research, however, will remain at a high level because the implant procedures will never eliminate removable prosthodontics at an early date.The research for the removable prosthesis, especially the movement of the abutment tooth, has been investigated in various ways such as by strain gauge, photoelastic and finite element methods, including a few experiment executedin vivo. All of them, however, have disadvantages respectively, so more effective methods for observation of the abutment tooth behaviors have been waiting for.Authors have undertaken some experiments on the abutment teeth behaviors under loading by a new analysing method that combined with MKG to the Frechette's method.This study was to analyse and evaluate the movements of the mesial abutment tooth in the tooth-supported segment on Kennedy Class II Modification 1 simulation model by the same method.The results were as follows;1. As the constructred factors were reduced from the original design of the RPD, the abutment tooth movements increased gradually.2. The greatest movements were recognized under the lingual load, and the minimum ones under the vertical load.3. Few movements toward the mesial direction were observed in every design.4. Movements toward the linguo-distal direction were remarkably noticed on almost designs.

The purpose of this study was to determine a baseline value of tongue pressure on the palatal region in normal subjects that could then be used to assist in fabrication of a palatal augmentation prosthesis (PAP).A tongue-pressure measurement system with 36 rubber pressure sensors was constructed for this study. This system was applied to 16 normal subjects, and the tongue pressure on the palatal region was measured when they were swallowing.The maximum tongue pressures seen during swallowing were 85.0 g/cm2 in the early stage, 95.0 g/cm2 in the middle stage, and 93.0 g/cm2 in the late stage. The average maximum tongue pressure throughout swallowing was 91.0 g/cm2. The tongue pressure in the early stage ranged from 3.37 g/cm2 to 8.74 g/cm2. A significant difference was found between the anterior and the posterior regions and between the central and the posterior regions. The value in the middle stage ranged from 5.32 g/cm2 to 10.22 g/cm2. Significant differences were found between the anterior and the posterior regions and between the central and the posterior regions. Values in the late stage ranged from 6.80 g/cm2 to 7.91 g/cm2.The average maximum tongue pressure against the palate of approximately 90 g/cm2 suggests that a PAP sufficient for swallowing should be strong enough to withstand this amount of pressure. The device is also useful to check for variations in the tongue contact area during trial of the prosthesis.

Summary The aim of this research was to examine the effects of metals used in dentistry upon magnetic resonance imaging (MRI). Ten disk-shaped samples of metals have been used in this study. Each sample has been set into a volunteer who had produced a normal MR image when tested. The subject was imaged in the sagittal, frontal and coronal plane with a 0.1T MRI device and results examined for MR defects. Au, Ag, Au-Ag-Pd and amalgam produced no defect. Ni-Cr, Co-Cr and SUS304 expressed small amounts of MR defects, but SUS405, Pd-Co-Ni and Sm-Co expressed large defects. Those metals which create MR image degradation must not be used for fixed prosthesis or orthodontic devices both of which could easily be made from other metals. If the MR image degrading metals are to be used in dentistry, their application should be restricted to removable prosthesis.