Patient: This study reports on a female patient with cerebral palsy, who was 28 years old when she first visited our clinic. At the age of 18, a bridge was set in the maxilla with the treatment performed under general anesthesia at University Dental Hospital. After 10 years, the bridge came off because of abutment tooth fracture. After tooth extraction, the feasibility of removable prosthesis was verified by using a temporary denture without clasps and performing careful occlusal adjustment, to achieve denture stability in the presence of unconscious lateral movements of the mandible. It was judged that the removable prosthesis could be used in this case and it was decided to fabricate a telescopic prosthesis. As a countermeasure for the patient's unconscious mandibular movements, the occlusion of the temporary denture was transferred as precisely as possible to the final prosthesis, and the palatal denture plate was reinforced by a metal framework to prevent fracture.
Discussion: Due to the taper of the inner caps, the telescopic prosthesis could be easily inserted in and removed from the patient's mouth. Prosthesis retention was achieved only in the final stage of prosthesis insertion and it was continuously maintained at an appropriate level. Furthermore, with this type of prosthesis, abutment teeth can be easily accessed for cleaning. For all these reasons, the telescopic prosthesis is considered to have many advantages for handicapped patients with unconscious mandibular movements. Moreover, the rigid connection between denture base and abutment teeth ensured rigid support, avoiding stress concentration in specific areas and thus providing the basis for favorable long-term prognosis of the treatment.
Conclusions: Good results were achieved after 12 years in a patient with cerebral palsy, whose large edentulous space was treated with a telescopic denture. Thus, this case shows that it is possible to treat large edentulous spaces of handicapped patients by using a removable prosthesis.

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Purpose: In the gold electroforming system, metal frames are made in a rotating current of the electroplating solution. It is thought that the position of the die influences the thickness of the metal frame. This study evaluated the influence of the position of the die on the thickness of the metal frame.
Methods: This study used the GAMMAT system and GAMMAT easy (Gramm) for the electroforming system and unit. Gypsum dies were fabricated from a master epoxy model that was prepared for a full-baked type metal-ceramic restoration of a maxillary central incisor (Shofu). Metal frames with a thickness of 200μm were fabricated following the manufacturer's instructions. Dies were set up in three different positions in a glass beaker (∅56.0mm): 1. center of the beaker (P0), 2. 11.0 mm from the center of the beaker (P1), and 3. 22.0 mm from the center of the beaker (P 2). All specimens were embedded in acrylic resin, sectioned in a labiolingual plane, and the thickness of the metal frame was measured using a laser microscope (Laser microscope 1 LM 21 W, Lasertec). There were five measurement points (a: labial central area, b: incisal edge, c: lingual central area, d: top of cingulum, e: axio lingual central area). There were five specimens in each group. The data were analyzed by the Kruskal-Wallis test and Bonferroni Correction.
Results: The thickness of the metal frame was P0>P1>P2 at d and e, and P0>P1≥P2 at b. There were no significant differences at a and c. P 0 was the largest of all the measurement points, and was nearly 200μm.
Conclusions: This study indicates that the position of the die influences the thickness of the metal frame, and that the thickness might be less than the value (200μm) at which the die was set up.

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Purpose: In order to clarify the functional role of head movements associated with the jaw movement during stomatognathic functions, the relationship between the amount of head movement during chewing of raw rice and the abilities of chewing or biting was analyzed.
Methods: Twenty-eight adult volunteers (25 males, 3 females, mean age 21.2 years) participated in this study. The head movement was monitored by a head-tracking sensor positioned near the forehead of the subject. The masticatory performance (MP) was measured by using the sieving method of raw rice used in many studies. The maximum bite force (BF) produced by the incisors of both jaws was measured by a strain-gauge transducer attached to a U-shaped bite stick. To inhibit the anteroposterior flexion of the head during chewing or biting, the head of the subject was held by an experimenter.
Results: 1. The degrees of head flexion during chewing varied among subjects. The degree of head flexion divided the subjects into two groups, the Small group and the Large group. 2. In the Small group, the MP was not changed by holding the head, but the BF was increased by about 20% by it. 3. In the Large group, the BF was not changed by holding the head, but the MP was decreased by about 10% by it.
Conclusions: In the subjects who moved their heads largely during chewing, the dynamic control system of head position served to increase chewing ability. Furthermore, from the data observed in the subjects who did not move their heads at all during chewing, it was suggested that the BF was limited by the static control system of head position.

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Purpose: The relationship between the composition of Ag-Pd-Au alloys and prevention of discoloration were evaluated both in vitro and in vivo.
Materials and Methods: Metal specimens of four types of Ag-Pd-Au alloy were incubated in THB (Todd Hewitt Broth) broth for four weeks at 37°C. Oral microorganisms such as Fusobacterium nucleatum or Streptococcus mutanswere incubated in the THB broth. After incubation, the luminance of metal specimens was measured and color differences (ΔE*ab) due to discoloration were evaluated according to the CIELab color system. In addition, six types of metal specimens (Ag-Pd-Au alloy, titanium and 14 K gold alloy) were embedded in dentures, and removed from the dentures after two months. The ΔE*ab of the metal specimens was then evaluated.
Results: For the Ag-Pd-Au alloy incubated with Fusobacterium nucleatum, the value of luminance decreased and the ΔE_*ab value increased due to corrosion which proceeded through metal sulfide formation in the presence of CH₃SH and H₂S produced by Fusobacterium nucleatum. Discoloration of 12 mass % Ag-Pd-Au alloy containing 20.0 mass % of Cu was marked, whereas ΔE*ab in Ti and 14 K were slight.ΔE*ab in the four types of Ag-Pd-Au alloys with different compositions was more than 10 both in vitro and in vivo.
Conclusions: The prevention of discoloration was influenced by the composition of Ag-Pd-Au alloys (Cu: 10.0-20.0 mass %, Au: 12.0 or 20.0 mass %). However, it was difficult to prevent the discoloration of commercially available Ag-Pd-Au alloys with the current compositions for patients having high corrosive influence on the mouth.

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Purpose: In this study, the authors histomorphologically investigated the usefulness of porous β-tricalcium phosphate (β-TCP) block with two different pore rates as a carrier of bone formation factor, recombinant human bone morphogenetic protein-2 (rhBMP-2), and bone formation.
Methods: Using 10-week-old female SD rats, the parietal region was incised, and the periosteum was exfoliated to expose the parietal bone. The following four conditions were established: 1.β-TCP alone with a pore rate of 60%(60 TCP); 2. rhBMP-2 was immersed in β-TCP with a pore rate of 60%(60 TCP+BMP); 3.β-TCP alone with a pore rate of 75%(75 TCP); and 4. rhBMP-2 was immersed in β-TCP with a pore rate of 75%(75 TCP+BMP). In the 60 TCP+BMP and 75 TCP+BMP groups, 0.2 mg/cm³ β-TCP was added to rhBMP-2. The follow-up period was established at 2 and 4 weeks. After the animals were sacrificed, nondecalcified polished specimens were prepared for histomorphological investigation.
Results: In the 60 TCP and 75 TCP groups, no neogenetic bone formation was detected. In the 60 TCP+BMP and 75 TCP+BMP groups, neogenetic bone formation was observed. Furthermore, β-TCP with a pore rate of 75% showed more rapid absorption.
Conclusions: In the 60 TCP and 75 TCP groups, neogenetic bone formation was observed, suggesting that a complex can be prepared and that β-TCP block facilitates maintaining and gradually releasing rhBMP-2, thus β-TCP block may be a useful carrier. Therefore, treatment with β-TCP block may improve bone defects.

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Purpose: In order to identify the region of crack initiation and to clarify the process of crack extension, three-dimensional expressions of crack surfaces in cracked teeth with cemented dowel were derived, and compared to the simulation of the crack generation model prepared by using the threedimensional finite element method.
Materials and Methods: The extracted maxillary central incisor was cemented with the post crown type dowel and was compressed in the 45° direction to the tooth axis from the lingual side by an extensometer. This specimen buried in resin was ground at sections of 50μm thickness and all the ground planes were photographed after dyeing them. From these photographed planes, three-dimensional expressions of the crack surfaces and the teeth were determined by computer, and compared with the process of crack generation simulated by using the three-dimensional finite element method.
Results: Vertical cracks were found in the directions of the medial and distal sides from the post hole, and two inclined cracks were observed at the labial side of teeth. On the simulation, when the specimen breaks down, the vertical crack occurs in the directions of the medial and distal sides from the post hole, and extends obliquely from the neck to the root apex. The other inclined crack was found below.
Conclusions: The process from crack generation to breaking was clarified, and it was shown that the number of cracks generated in a tooth is not limited to only one.

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