Fumio Takashima

The Influence of the Color of the Abutment Tooth on the Color of All Ceramic Crowns.

All-ceramic crowns are the most esthetic, because they transmit light similarly to natural teeth. However, because of the translucency of all-ceramic crowns, the color of the abutment tooth can affect the color of the final crowns.The aim of this study was to investigate the influences of the color of the abutment tooth on all-ceramic crowns.Ceramic disc specimens (In-Ceram, Hi-Ceram, Optec and G-cera II), metal disc abutment specimens (type IV gold and gold-silver-palladium alloy) and porcelain disc abutment specimens (A 1 and A 4) were used for the study. The color of ceramic specimens was measured with a small area colorimeter by translucent and reflectant methods and evaluated by the CIE L*a*b* color system.The results were as follows:1. All ceramic systems with an aluminous core have low translucency, so the color of the abutment tooth does not have to be considered.2. All ceramic systems with masking porcelain have high reflectance, so the light reflectance have to be considered.3. All ceramic systems with high translucency have to be considered due to the effect of the color of the abutment tooth.

Clinical Study on the Effect of the Single Crown on Segmental Chewing.

Chewing is closely related to occlusion, and occlusion of a specific tooth affects segmental chewing. Therefore, analysis of chewing is supposed to have diagnostic value for assessing occlusion. However, the difference in segmental chewing among various teeth is unclear. Comparison in segmental chewing between before restoration and after restoration was performed in 55 patients who were treated by a single premolar or molar restoration.The results are summarized as follows:1. Chewing pattern and chewing speed pattern1) Premolar restoration had little effect on chewing.2) First molar restoration revealed a tendency to improve chewing, and second molar restoration demonstrated a tendency to worsen it.2. Chewing rhythmMolar restoration showed a tendency to shorten the duration of the occlusal phase.

The Relationship between Signs and Symptoms of Craniomandibular Disorders and MRI Findings.

Abnormalities of soft tissue of TMJ components are common in craniomandibular disorders. For the diagnosis of these abnormalities, MR imaging technique is useful. However, the relationship between MRI findings and signs and symptoms of craniomandibular disorders remains unclear.In this study, MRI findings and signs and symptoms of craniomandibular disorders were compared for 150 patients (300 TMJs) with craniomandibular disorders.

A study on the relation between laterality of chewing and posture

咀嚼運動は顎口腔系諸器官と上位中枢との協 調のもとに営まれるリズム性のある反射的な機 能運動であ り、機能的咬合系の3要 素である、 咬合、顎関節、咀嚼筋の全ての情報が内在され ていると考えられる。われわれは、顎口腔機能 の診査、診断に際 し、咀嚼運動を一般臨床に応 用するとともに、一連の研究報告を行ってきた。 咀嚼運動を咀嚼側を指定 して記録分析すると、 正常者においても、左右側で経路、リズム等が 異なる場合があり、このような咀嚼における左 右側差についての報告はこれまでにも見られる ものの、主咀嚼側の偏 り、咀嚼筋活動の不均衡、 顎顔面形態の左右非対称、さらには頭位など様 々な要素が関与 しているものと考えられる。 顎口腔機能異常患者の中には、頸肩腕部の疼 痛や痺れ等の全身症状を有する者が少な くなく、 このような症例では姿勢 における左右のアンバ ランスが多く認められる。 しか しなが ら、適正 な下顎位を与え、咬合再構成を行うことで、症 状が消失するとともに、姿勢のアンバランスも 改善されるという報告もあ り、咬合と姿勢の関 連性については注目されてきている。 演者らは、第38回 本研究会にて、個性正常咬 合者 における咀嚼の左右側差と頭位との関連性 について、頭部の側屈側 と咀嚼 リズムあるいは 咀嚼筋活動の左右差 との間には明らかな関連性 は認められないものの、頭部の側屈側と主咀嚼 側が一致する者については、特に側頭筋におい て主咀嚼側の筋活動比率が高いことを報告 した。 今 回 は 、 主 咀 嚼 側 お よ び 咀 嚼 経 路 を も と に 分 析 した 咀 嚼 側 差 と 、 自 然 立 位 に お け る頭 部 お よ び 肩 を 基 準 と した 姿 勢 の 関 係 につ い て 明 ら か にす る こ と を 目 的 と し、 頭 部 正 面X線 規 格 写 真 の 計 測 を も と に した 顎 顔 面 形 態 の 特 徴 に つ い て も あ わ せ て 検 討 した 。

The Relationship of Cervical Vertebra Alignment and Dentofacial Morphology.

The purpose of this study was to investigate the correlation between cervical vertebra alignment and factors of occlusion, dentofacial morphology, and head posture. The authors analyzed the relationship of cervical inclination and curve and dentofacial morphology using cephalometric photography. Subjects consisted of one hundred normal young adults without TMJ symptoms (an average age of 26 years old).The following results were obtained:1. The inclination of the dens showed a positive correlation to FH plane, palatal plane, occlusal plane and mandibular plane. In the case of forward flexion of dens, each inclination was high. But for backward flexion, each inclination was low.2. The curve from the second cervical vertebra to the fourth cervical vertebra showed a positive correlation to the inclination of the dens. In case of forward flexion of dens, the curve was small. But for backward flexion, the curve was large. And it did not correlate to each plane. It was shown that inclination of the dens correlated with dentofacial morphology and the curve of vertebra.

Psychosomatic Aspects of the Patients with Esthetic Dissatisfaction.

The purpose of this study was to clarify psychosomatic aspects of patients whose chief complaints were esthetic dissatisfaction with their teeth. Cornell Medical Index (CMI) test scores of three patient groups were compared. Three patient groups were the patients with esthetic dissatisfaction, the patients with stomatognathic dysfunction, and the patients who asked for prosthetic treatment without esthetic dissatisfaction and stomatognathic dysfunction.The results obtained were as aollows:1. In section Q (questions about Anger), the CMI score of the patients with esthetic dissatisfaction was significantly higher than that of the patients who asked for prosthetic treatment without esthetic dissatisfaction and stomatognathic dysfunction.2. In the sum of sections CIJ, M-R, and A-R, CMI scores of the patients with esthetic dissatisfaction were significantly lower than those of the patients with stomatognathic dysfunction.

Effect of Change in Occlusal Vertical Dimension on Chewing Movements. Part 1. Influences on the Rhythm of Chewing Movements.

Assessment of occlusal vertical dimension (OVD) is an essential in the dental treatment. However, physiolosical effects of the change in OVD remains unclear.The purpose of this study is to assess the effect of the change in OVD on the stomatognathic function by analyzing any chewing movements.Five subjects without any signs or symptoms of craniomandibular disorders and with normal occlusion (age: 24-28 years, 4 males and 1 female) were selected. Onlay-type appliance was fabricated to raise the OVD by about 2mm. The chewing movements were recorded and analyzed using the Sirognathograph Analyzing System III.As a result, no change was observed in cycle time of the chewing movements, however as for each duration, some changes was observed.

Bone Response to Resin-Hydroxyapatite Material.

Resin-hydroxyapatite material has been developed to overcome the disadvantages of hydroxyapatite. This material is composed of 75% hydroxyapatite, 15% Bis-GMA and 10% quartz reinforced filler. The purpose of this study was to examine the influence of the material and the constituents; hydroxyapatite, Bis-GMA on surrounding bone tissue histologically.Cylindrical piece (4mm diameter×10mm length) of each material was prepared, implanted in femurs of six adult mongrel dogs. At 2, 4, 12 weeks after implantation, decalcified histologic sections were examined microscopically.The results were as follows:1. The resin-hydroxyapatite or hydroxyapatite at 12 weeks postoperatively showed direct contact with the surrounding bone tissue in most interface region between either material and bone tissue, while in some interface region, fibrous connective tissue existed.2. Bis-GMA at 12 weeks postoperatively showed fibrous connective tissue free of inflammatory cells in most interface region between the material and adjacent bone tissue, while in some interface region, this material had direct contact with the bone tissue without intervening fibrous connective tissue.Above results indicated that the resin-hydroxyapatite material was as biocompatible as hydroxyapatite, and suggested that this material would be acceptable for clinical use.