Kanji Ishibashi

Determination of daytime clenching events in subjects with and without self-reported clenching

To confirm the validity of self-awareness of daytime clenching, specific electromyogram (EMG) characteristics of clenching behaviour were determined using surface EMG recordings. Temporal muscle EMGs were recorded for 5 h in 13 subjects with self-reported clenching (clenching group: 27·5 ± 3·8 years old) and 12 subjects without self-reported clenching (control group: 28·6 ± 7·1 years old). All EMG data were recorded and stored on a portable EMG apparatus. The device was similar in size to a hearing aid, and suitable to record daytime EMG without restriction of daily activities. A clenching event was defined as muscle activity exceeding 10% of the maximum voluntary contraction. Furthermore, simultaneous voice recording was also performed to identify the corresponding EMG event as functional or parafunctional. The mean number of clenching events was 192·8 ± 228·8 and 24·8 ± 26·5 in the clenching and the control groups, respectively (P < 0·05, Mann-Whitney U-test); the number of functional events was not significantly different between the groups. Because there was a significant difference in the number of clenching events between the groups, self-reported daytime clenching is considered to be a reliable screening parameter for awake bruxism.

The effect on immunocytes of anodic oxide titanium after hydrothermal treatment.

All dental root implants come in contact with the oral epithelium, and many complex factors are found to arise in this region. In order to perform a successful dental root implantation, it is necessary to clarify the interaction of the dental root implant material with the host defense mechanisms involved in the specific and nonspecific immune responses to many antigens in oral bacteria and their components. Recently, focusing on developing the dental root implant, the Nikon Corporation improved the surface characteristics of pure titanium even further by developing a hydroxyapatite (HA) layer formed on an anodic titanium oxide film containing Ca and P via hydrothermal treatment (SA treatment). However, since little is known about the effect of SA-treated pure titanium (HA/Ti) on the defense mechanisms of the oral membrane epithelium, we investigated (1) the in vitro proliferation of murine splenic B lymphocytes on the surface of HA/Ti in the presence of three lipopolysaccharide (LPS) concentrations and (2) interleukin-1alpha (IL-1alpha) production by the reaction of human peripheral blood mononuclear cells (PBM cells) on the surface of HA/Ti under the same concentrations. After culture, murine splenic lymphocytes were measured by uptake of 3H-thymidine, and cytokine release (IL-1alpha) from PBM cells was measured by ELISA. Results showed that HA/Ti had hardly any effect on the LPS-induced proliferation of B lymphocytes and IL-1alpha production. In vitro investigations of the effects of HA/Ti on the LPS-induced proliferation of murine splenic B lymphocytes and IL-1alpha from PBM cells might be a useful way of elucidating the defense mechanism between implants and the oral epithelium.

Physicochemical state of the nanotopographic surface of commercially pure titanium following anodization-hydrothermal treatment reveals significantly improved hydrophilicity and surface energy profiles

A method of coating commercially pure titanium (cpTi) implants with a highly crystalline, thin hydroxyapatite (HA) layer using discharge anodic oxidation followed by hydrothermal treatment (Spark discharged Anodic oxidation treatment ; SA-treated cpTi) has been reported for use in clinical dentistry. We hypothesized that a thin HA layer with high crystallinity and nanostructured anodic titanium oxide film on such SA-treated cpTi implant surfaces might be a crucial function of their surface-specific potential energy. To test this, we analyzed anodic oxide (AO) cpTi and SA-treated cpTi disks by SEM and AFM. Contact angles and surface free energy of each disk surface was measured using FAMAS software. High-magnification SEM and AFM revealed the nanotopographic structure of the anodic titanium oxide film on SA-treated cpTi; however, this was not observed on the AO cpTi surface. The contact angle and surface free energy measurements were also significantly different between AO cpTi and SA-treated cpTi surfaces (Tukeys, P<0.05). These data indicated that the change of physicochemical properties of an anodic titanium oxide film with HA crystals on an SA-treated cpTi surface may play a key role in the phenomenon of osteoconduction during the process of osseointegration.

Clinical application of dental implant with root of coated bioglass: Short-term results

During the last 4 years 73 dental implants with root-coated bioglass to replace one to three teeth in the premolar and molar sites of the mandible were inserted. The bonding ratio between implant and bone was observed clinically 1 year after implantation and installation of the superior structure. This ratio measured 52.4% to 63.3%. An acoustoelectric tester was developed that advanced our skills. The emphasis was placed on a tight fit between implant and surrounding bone.

Clinical evaluation of a dental color analysis system: The Crystaleye Spectrophotometer®

PURPOSE To evaluate the clinical performance of the Crystaleye Spectrophotometer(®), a dental color analysis system. METHODS Three color-measuring devices (Crystaleye Spectrophotometer(®), CAS-ID1, MSC-2000) were tested and the differences in color measurements among them were evaluated using Scheffes F-test. Color measurements with the Crystaleye Spectrophotometer(®) were repeated 10 times by the same operator. The color difference (ΔE) between the first and tenth measurements was calculated. The Crystaleye Spectrophotometer(®) was used to measure the color of the maxillary left central incisor under two conditions (light and dark) and the effect of exterior lighting was analyzed to assess the accuracy of measurements. Furthermore, five different operators performed color measurements, and ΔE among the three devices was calculated. The ΔE between the target tooth and the crown of a single maxillary central incisor crown fabricated using data from the Crystaleye Spectrophotmeter(®) was calculated. Color differences between prebleaching and postbleaching were also analyzed with the Crystaleye Spectrophotometer(®) using the parameters ΔE, ΔL*, Δa*, and Δb*. RESULTS The data from the three spectrophotometers were not significantly different. The ΔE during repeated color measurements by the same operator was 0.6. The ΔE between light and dark conditions was 0.9. The data from the five operators were not significantly different. The mean ΔE value between the target tooth and the fabricated crown was 1.2 ± 0.4, and the mean ΔE value between prebleaching and postbleaching was 3.7 ± 1.0. CONCLUSIONS The Crystaleye Spectrophotometer(®) is an easy-to-use color analysis system producing accurate color measurements under clinical conditions.

Hypoplastic-hypocalcified enamel of teeth and dysplastic nails: An undescribed ectodermal dysplasia syndrome

Hypoplastic-hypocalcified enamel of all permanent teeth and dysplasia of finger- and toe-nails were found in a 17-year-old Japanese male. Physical examination revealed no remarkable changes in skin, hair, sweat glands, bones, etc. Family history revealed the same abnormalities of teeth and nails in his mothers brother. A review of the literature concerning ectodermal dysplasia syndromes failed to reveal a combination of hypoplastic-hypocalcified enamel and dysplastic nails without changes in any other ectodermal tissues.

A Case Report of a Patient Complaining of an Esthetic Problem due to Enamel Hypoplasia

症例の概要: エナメル質形成不全により審美障害を訴えて来院した14歳女子の症例を報告する.患者の祖母と父親にもエナメル質形成不全が認められた.乳歯列期にはエナメル質形成不全はみられなかったが, すべての永久歯の表面は粗で, 茶褐色を呈していた.永久歯列完成に伴い, 審美障害を改善するために当科を紹介され, 1999年1月来院した.上顎前歯部の審美障害を改善するためにラミネートベニアを装着した.下顎前歯部には, 経済的理由によりコンポジットレジン充填を行った.17カ月後, 患者の希望により下顎前歯部にラミネートベニアを装着した.3年経過したが良好な状態を維持している.考察: 年齢を考えると歯肉退縮が予想されるものの, 患者が歯の色と形態を最も気にしていることに加え, 将来, 歯肉退縮した際には治療し直すことを理解してもらったうえで, 治療計画は審美性の回復を優先した.結論: ラミネートベニアによる治療は, 審美障害を改善しただけでなく歯の色の異常に起因する劣等感をなくし, QOLの向上もはかられた.エナメル質形成不全歯に対してラミネートベニアを装着した症例報告は少ないことから, 長期間にわたる経過観察が必要である.

A Case Report of the Anterior Disc Displacement Patient Utilizing Anterior Therapeutic Position as an Occlusal Position.

症例の概要: 患者は45歳女性で, 開口制限を主訴に1994年に岩手医科大学歯学部附属病院へ紹介され来院した. 1日に数回右側顎関節に間欠性のロックが生じるが自力でロック解除していたとのことであった. ロック時の開口量は, 上下中切歯切縁間距離で22mmであった. MR画像検査所見では, 右側顎関節の復位性関節円板前方転位が認められた. 1995年, 咬頭嵌合位から2mm前方となる前方治療位で咬合するパーシャルデンチャーにより咬合位を変更させたところ, 開口量は52mmまで増加した. 1996年に行ったMR検査結果および臨床所見から, 関節円板の位置異常もなく下顎の機能も問題ないものと診断した. 1997年にパーシャルデンチャーを紛失したため, 新しく作製したパーシャルデンチャーには, 本来の咬頭嵌合位を咬合位として付与した. ところが, 1998年に右側顎関節の関節円板が再転位し, しかも非復位性となっていることが判明した. パンピングマニピュレーションによる治療を受けた後に, 開口量は28mmから35mmへと増加したものの, 関節円板は整位せず非復位性転位のままであった.考察: 前方治療位から咬頭嵌合位に戻したことが円板再転位の原因と考えられたことから, 本症例では前方治療位を維持させるべきであったものと思われる.結論: 復位性関節円板前方転位により間欠性ロックが長期間に及ぶ場合は, 前方治療位を維持させる必要性が示唆された.

The Colorimetric Study of the Musking Porcelain. The Evaluation of the Opacity Using a Hiding Power Index.

Translucency is a very important factor for obtaining an esthetic porcelain laminate veneer crown. This translucency is greatly affected by the opacity of the masking porcelain layer, but there is no objective criterion to evaluate the opacity. In general, opacity is well evaluated by hiding power. Therefore, hiding power of masking porcelain was calculated in this study using the ASTM (American Society for Testing and Materials) method.The reflectance value of each masking porcelain sample containing 5, 10, 15, 20, 25, or 30% opacity of pink, white, yellow, and blue were measured with white and black backing, and hiding power was calculated using its scattering coefficients. Hiding power increased in proportion to the opacity and ranged from 100 to 1, 400 for any shade. Color difference dE between white and black backing increased rapidly under the 25% opacity.It was concluded that (1) the opacity could be analyzed as hiding power and (2) hiding power under 20% opacity is very effective on visibility.

Color Modification of Porcelain Laminate Veneer Crowns by CCM. Part 1. Color Reproducibility using the Musking Porcelain with Opaque as a Coloring Element.

Porcelain laminate veneer crown is an excellent system to improve the color of a discolored tooth in the anterior region having occlusal contact. Since masking porcelain of porcelain laminate veneer crown has opacity for hiding the discolored tooth, it was difficult to give a high translucency to the laminate crowns by conventional methods.The purpose of this study was to produce the natural color and excellent appearance of laminate crowns with adequate translucency using the Computer Color Matching (CCM) System to compensate opacity of masking porcelain.Construction of CCM sample, discolored layer, and procedure of CCM formulation are the same as part 1.In this study, 1 kind of opaque porcelain was used as the hiding element, and 3 kinds of dentin were used as the coloring element. According to the CCM formulation, masking porcelain was baked and the CCM samples were made.In comparison of the target color and CCM sample, both reflectance curves were very similar and color difference dE was under 3.0. Furtheremore, CCM samples showed the color to be indistinguishable from the target color by the naked eye.