Purpose: The purpose of this study was to investigate the effects that the time of preparation within a range of four weeks had on the pull-out resistance strength after cementation.
Materials and Methods: Abutments milled from SUS steel were placed and cemented into the cavities of extracted bovine roots with resin-modified glass ionomer cement, and the pull-out resistance strength was measured up to 4 weeks. The examination periods were 0 minute, 30 minutes, 24 hours, 1 week, 2 weeks, 3 weeks, and 4 weeks. Preparation was conducted immediately after cementation as condition 1, and after each time period as condition 2. The pull-out resistance strength was measured after each time period following preparation as condition 1 (IP), immediately after preparation at each time period as condition 2 (BT), and after each time period following no preparation as a control (N). All the data obtained were subjected to statistical analysis.
Results: While the pull-out resistance strength increased up to 4 weeks, the mean value at one week reached 95% of that at 4 weeks. The mean value of Group IP did not show significant differences with Group NP by applying the conditions of various durations from cementation to preparation. There were significant differences between Group BT and IP at all periods except for immediately, 30 minutes, and 4 weeks.
Conclusion: To obtain satisfactory results for prosthodontic restorations with metal abutments, it is considered preferable that cementation and preparation be completed at the same visit, and that excessive stress on abutment teeth should be avoided as much as possible.

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Purpose: We focused on the application possibility of silicone rubber and acrylic resin, which aren't subject to thermal deformation compared to mouthguard material. The purpose of this study was to compare the transmitted impact force through supplied mouthguard material, silicone rubber material and acrylic resin material.
Methods: Six materials were selected, which were two mouthguard materials MG1, MG2, two silicone rubber materials SL1, SL2, and two acrylic resin materials RE1, RE2. The impact force was produced by a free-falling steel ball (13.8 gf, 15 mm diameter) from a height of 600 mm. The first peak intensity (P1) and the time to P1 from the onset of the transmitted force (P1-t) were statistically analyzed using ANOVA and Scheffe's multiple comparison test (p < 0.05).
Results: There were significant differences, which were RE1 ≈ RE2 > SL1 > MG1 ≈ MG2 > SL2 on comparison of P1, and RE1 ≈ RE2 < SL1 ≈ MG2 ≈ MG1 < SL2 on comparison of P1-t.
Conclusion: In comparison with supplied mouthguard materials, the shock absorption ability of SL1 might be slightly low, and that of SL2 might be high. Moreover, those of the acrylic resin materials were poor, which indicates that it is problematic to use them alone as a mouthguard material.

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Purpose: The aim of this study was to find an optimal post-and-core method for endodontically treated teeth with flared canals.
Materials and Methods: Four kinds of composite resin core methods (composite resin post and core, a prefabricated fiber post and composite resin core, three prefabricated fiber posts and composite resin core, a prefabricated fiber post with sleeve and composite resin core) with and without fiber posts combined with two kinds of composite resin core material were compared regarding the bending strength and elastic modulus by the three-point bending test. Furthermore, as for experimental abutment teeth, typical human central incisors were modeled using bovine incisor teeth. Totally five methods adding one more method of cast post-and-core were compared regarding failure strength and failure modes by a fracture resistance test.
Results: As indicated the by three-point bending test, both composite resin core methods with three fiber posts and a sleeve showed higher bending strength in both core materials than composite resin core material with only one fi ber post. With the fracture resistance test, the conventional cast post-and-core method revealed the highest failure strength, though its failure mode was absolutely un-restorable. On the contrary, the failure modes of the other four methods were mainly restorable.
Conclusion: Disposition of plural fiber posts and one fiber post with a sleeve can be recommended for restoration of endodontically treated teeth with flared root canals.

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Purpose: The aim of this study was to determine the optimal disposition of fiber posts in composite resin core materials for endodontically treated teeth.
Materials and Methods: Composite resin core material was filled in a glass tube that was 3 mm in caliber and 24 mm in length and one or four fiber posts were additionally inserted with the planned disposition into the core materials, followed by light irradiation. The composite resin core complex with fiber posts was removed from the glass tube, trimmed to a specimen of 20 mm in length and embedded at a depth of 10 mm in a ring filled with self-curing resin material. The initial and maximal failure strength, failure modes and the displacement of the loading point after static and cyclic loading were measured.
Results: The composite resin core complex with fiber posts of 1.0 mm and 1.6 mm in diameter, which were placed at the tensile side of the complex, showed a significantly higher value in the initial failure strength than the composite resin cylinder with no fiber post. The complex with a fiber post of 1.6 mm in diameter, which was placed at the tensile side, indicated signifi cantly the highest value in the maximal failure strength among all complexes. Both the complex with a 1.6 mm fiber post and the complex with four thinner fiber posts displayed the smallest displacement of the loading point after cyclic loading.
Conclusion: Disposition of fiber post in the composite resin core materials was a significant factor for the initial and maximal failure strength and also displacement of the loading point after cyclic loading. Especially, it is recommended to place the fiber posts at the tensile side of the complex.

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Patient: A 57-year-old woman came to our clinic complaining of mobility of the upper cantilever fi xed partial denture. Although we should select the removable partial denture treatment with the loss of posterior support following tooth extraction, this patient did not accept the design of palatogingival coverage. So we employed a cone crown telescopic denture without a major connector. This prosthetic treatment produced a longitudinally stable oral function.
Discussion: The denture, which was designed with comfort in mind, allowed the patient to wear a removable partial denture without discomfort. The cone crown telescopic denture produced occlusal support, improved oral hygiene, and prevented occlusal decay.
Conclusion: We report the importance of the denture design taking into consideration comfort to prevent occlusal decay.

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Patients: A 60-year-old male complained of aesthetic disturbance for detached facing crown of maxillary anterior teeth and dysmasesis. The patient was diagnosed as intraocclusion by analysis of occlusal vertical dimension. The occlusal vertical dimension was increased by provisional restoration and treatment denture. Finally, fixed prostheses and a removable partial denture were inserted.
Discussion: The vertical dimension decreased with loss of occlusal support and attrition of teeth were considered to detach fixed dental prosthesis by increasing load of maxillary anterior teeth.
Conclusion: In the present clinical case, aesthetic disturbance and dysmasesis were improved by changing to an appropriate occlusal vertical dimension and occlusal reconstruction.

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Patients: A 45-year-old male complained of aesthetic disturbance from an injury as well as masticatory dysfunction from missing mandibular molars at both sides. This case was caused by a poor interim prosthesis at the maxillary anterior teeth, which has a deficit of mandibular molars. After oral assessment, it was judged that treatment to improve the occlusal position was not necessary. After setting provisional restoration, a fixed prosthesis was made using individual tooth trays to the maxilla and a removable denture was inserted to the mandible.
Discussion: It was thought that the main complaints of aesthetic disturbance and occlusion were solved after setting the provisional restoration for the maxilla and dentures for the mandible.
Conclusion: Aesthetic disturbance and masticatory dysfunction were improved after inserting the provisional restoration, and taking impressions using individual tooth trays.

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Patient: We performed the prosthetic treatment to chronic periodontitis patient (age 46, female) whose periodontal tissue had already controlled by periodontal treatment including periodontal surgery and orthodontic therapy.
Discussion: This case was considered that periodontitis became severe condition due to modify with periodontal pathogens in plaque and trauma from occlusion. The patient has obtained good condition that treated with the prosthetic devices designed to facilitate easy plaque control after proper periodontal treatment and orthodontic therapy.
Conclusion: This case suggested that design of prosthetic devices were an important factor for chronic periodontitis patient. In addition, they have to contain the suitable function to deal with the recurrence periodontal pocket and to control the dental plaque simply.

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Patient: The patient was a 59-year-old female who visited a clinic with a chief complaint of a mastication disorder caused by the loss of a right mandibular molar. Misalignment of the occlusal plane was observed due to extrusion of right maxillary molars. Implant placement was performed on right mandibular molar. When replacing the crown restoration which had been placed, the patient chose an all-ceramic crown due to aesthetic concern. Stable progress was possible.
Discussion: Careful observation for any change of the occlusal plane of the prosthesis will be required.
Conclusion: The patient was satisfied that her mastication disorder was improved and the aesthetic appearance was restored by the all-ceramic crown, and stable progress was possible.

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Patient: A 58-year-old female patient diagnosed as right maxillary cancer was introduced to our prosthodontic clinic by oral surgeon before surgery. As 7—1| maxillary defect was expected after surgery, an early postoperative dento-maxillary prosthesis where patient's teeth, gum and palate were duplicated was fabricated from the pre-operative maxillary cast. The patient had used the prosthesis with obturator for functional and esthetic rehabilitation until final prosthesis was fabricated.
Discussion: In this case, a prosthodontic approach from preoperative stage could minimize functional disturbance and accelerate functional and esthetic recovery during early postoperative stage. It was supposed that collaboration between a prosthodontist and oral surgeon on the prosthesis was integral for such early-stage rehabilitation of maxillectomy patients.
Conclusion: Prosthetic rehabilitation from early postoperative stage of a maxillary cancer patient using dentomaxillary prosthesis fabricated before surgery was effective for preventing functional and esthetic disturbance, and thereby improved patient satisfaction.

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Patient: The patient was a 60-year-old female, with complaints of masticatory dysfunction and esthetic dissatisfaction. One of the causes was considered to be infraocclusion in the molar area of the lower partial denture. Since irregularity in the occlusal plane and deep bite were also observed, bite raising was carried out to solve these problems.
Discussion: The occlusal plane and the vertical dimension were restored using provisional restoration and a removable partial denture which had already been used. The required increase in vertical dimension was divided into several steps of bite-raising treatments. Because of these steps, the patient was satisfied with mastication and esthetics without jaw muscle pain or discomfort in the higher vertical dimension.
Conclusion: It is suggested that dividing the bite-raising treatment into several steps reduced the occurrence of discomfort symptoms in the masticatory system induced by the increase of occlusal vertical dimension.

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