Yoshiyuki Kakehashi

Bond Strength to Dentin Subjected to Temporary Cementation of Resin Based Luting Agents

目的: リン酸を表面処理剤とするレジン系装着材料の仮着した象牙質に対する接着強さの影響を明らかにするために, 比較検討を行った.方法: HY-Bond Temporary Cement Hard (以下HYB), Freegenol Temporary Pack (以下FTP) およびNeodyne T (以下NDT) の3種類の仮着材で, レジンプレートを牛歯象牙質に仮着した.Variolink II (以下V2) およびRely X ARC (以下RX) を用いて, IPS Empressを接着して勢断接着試験用試料を作製した.仮着を行っていないものをコントロール (以下CON) とした.仮着した象牙質およびIPS Empressに対する表面処理は, 製造者指示に従って行った.試料を37℃ で24時間精製水中保管後, 勇断接着強さを測定した.結果: V2の接着強さは, CON (11.4MPa, a, b), HYB (12.7MPa, a), FTP (7.6MPa, b, c) およびNDT (5.9MPa, c) であった.CONと比較してNDTが有意に (P<0.05) 低い値を示したが, HYBおよびFTPでは有意差が認められなかった.一方, RXの接着強さは, CON (21.7 MPa, d), HYB (11.3MPa, e), FTP (6.0MPa, f) およびNDT (11.2MPa, e) であった.CONと比較してすべての仮着材で有意に低い値を示した.最も低い値を示したFTPでは, CONの27.5%であった.同一文字は多重比較において危険率5%で有意差がないことを示す.結論: V2とRXは, 接着強さが低下した仮着材がそれぞれで異なったことから, リン酸処理を行うレジン系装着材料の接着強さは, 組合せによって影響が異なることが明らかとなった.

A Study on Repair Restoration with High Filler Containing Indirect Composites-Surface Treatment for Light Cured Type Resins-

目的: 光重合タイプの高フィラー型硬質レジンの補修時における有効な表面処理方法を知ることを目的とした.方法: ArtglassおよびGradia (エナメル色ペーストAEおよびGE, デンチン色ペーストADおよびGD) を用い, 製造者指示に従い重合した被着体 (2×2×12.5mm) に, 処理なし (NT), シラン処理 (S), ボンディング処理 (B), シラン処理とボンディング処理を併用 (SB) の4条件で表面処理を行った.追加築盛は, 直接法および間接法のそれぞれで, 製造者指示の補修用レジンを用いて曲げ接着試験用試験体 (2×2×25mm) を重合して作製した.試験体は, 37℃ で24時間水中保管後に3点曲げ試験を行い, 曲げ接着強さを得た.結果: 被着体AEは直接法ではSB>S>B>NT, 間接法ではSB≧S>B>NTの順で, 被着体ADは直接法および間接法の両者で, SB>S>B>NTの順で有意に大きな曲げ接着強さを示した.一方, 被着体GEは, 直接法ではSB>B≧S>NT, 間接法ではSB≧S≧B>NTの順で, 被着体GDは, 直接法ではSB≧B>S>NT, 間接法ではSB≧B≧S>NTの順で有意に大きな曲げ接着強さを示した.結論: 最適な表面処理は, AEが直接法でSB, 間接法でSBおよびS, ADが直接法および間接法の両者でSB, GEが直接法ではSB, GDがSBおよびB, GEおよびGDともに間接法ではS, BおよびSBであった.

Thickness of the Metal Frame by Electroforming-Influence of Positioning Die in the Electroplating Solution-

目的: ゴールドエレクトロフォーミング法は, メタルコーピングを回転する電解溶液中で製作するため, 電鋳歯型の位置づけがコーピングの厚さに影響を及ぼすと考えられる. そこで, 電解槽内での水平的位置づけを変化させ, その影響を検討した.方法: フルベークタイプの陶材焼付冠製作用に形成した上顎中切歯支台歯模型 (松風) を原型とし, 複製電鋳歯型を製作した. 電解槽装置 (GAMMATeasy, Gramm) のビーカー (内径56.0mm) 内で, 垂直的に電極上縁から切縁中央までを20.0mmとし, 水平的に1.ビーカー中心, 2.中心から11.0mm, 3.中心から22.0mm (以下, P0, P1, P2) の3条件に位置づけした. その後, 厚さ200μmに設定しエレクトロフォーミングを行い試料とした. 試料を包埋し, 唇舌的に切断し, 走査型レーザー顕微鏡 (Laser microscope 1 LM 21 W, Lasertec) にてコーピングの厚さを測定した. 測定部位は唇面中央部, 切端部, 舌面中央部, 基底結節上部, 舌側軸面中央部 (以下, a, b, c, d, e) の5点とした. 試料数は各条件5個とし, 統計にはKruskal-Wallis testとBonferroni Correctionを用い, 各測定部位での比較を行った.結果: コーピングの厚さは, P0では全測定部位で最大値を示し, 設定値に近似した値を示した.そのほかは設定値より小さな値を示した. d, eにおいてはP0>P1>P2の順に大きな値を示し, bではP0>P1≧P2の順に大きな値を示した.結論: ビーカー内での電鋳歯型の位置づけがコーピングの厚さに影響を及ぼし, 設定した厚さより薄くなることが判明した.

Chromatic Study of IPS Empress. The Effect of Various Adhesive Resin Cements on Layering Technique.

IPS Empress® is an all-ceramic crown system which provides a color tone and light transmittance resembling those of natural teeth. However, because of the translucency of all-ceramic crowns, the color of the adhesive resin cements and the abutment teeth can affect the color of the final crowns.This study examined the effects of IPS Empress® on the layering technique and color of the adhesive resin cements on various background color by comparison and examination.The color difference from the standard color was calculated, and it was judged to have color appearance when ΔE*ab≤2.0.The conclusions were as follows:1. For A 2 background, the color appearance to standard color were obtained using translucent type cements VW and VB (Variolink).2. For Au background, the color appearance to standard color were all of translucent type cements, while for Pd background, opaque type cements YO (Variolink) insertion with better color appearance.3. For H background, using translucent type cements Tr (LA cement) containing dentin color tone and opaque type cements VO (Variolink) with lower values of lightness yielded ΔE*ab≤2.0 with color appearance.The above results suggested that appropriate intermediate cements used in the layering techniqueof IPS Empress® decrease the influence of the background color, achieving a color tone approximating the target color.

A Study of Toothbrush Abrasion on Adhesive Resin Cement. Filler Contents of the Routing Cement.

Although there have been reports on the abrasion of resin cements, cement film thickness was hardly considered.Takamisawa evaluated the influence of the cement film thickness on the abrasion of non-filler type resin cement, and concluded that there was a close relationship between number of times and depth of abrasion. The rate of increase of the wear depth was affected by the cement film thickness.Since most resin cements contained microfiller, Variolink (Vivadent) was examined and it was IPSEmpress (Vivadent) cem kit.Newly-designed appliances to prescribe 3 cement film thicknesses were used, namely 50, 100, and 200 μm, and the abrasion for each thickness in toothbrush abrasion test was observed.Continuous measurements were made of the sectional profile, wear depth, and surface roughness by scanning laser microscope.In SEM observation, the abrasion surface showed different aspects between non-filler and microfiller types.While there was a close relationship between number of times and depth of abrasion as in the case of non-filler type, the amount of increase of the wear depth varied with the cement film thickness.Test results indicated that the cement film thickness had influence on the abrasion of resin cement, and resistance of abrasion was influenced by filler type and resin matrix.

Study on determination of the imaginary axis of the tooth crown. 1. Measuring procedure

The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw and lower jaw right and left first molar can be determined by the measuring apparatus and method of this study. 2. The measurement error of this method was not more than 0.1 degree. This value was sufficient for the purpose of this study.

[Study on determination of the imaginary axis of the tooth crown in anterior teeth: 1].

1. The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw anterior teeth can be determined by the image measuring system and method of this study. 2. The measurement error of this system was not more than 0.3 degree. This value was sufficient for the purpose of this study. 3. The imaginary axis of the tooth crown of anterior teeth was determined on the study cast with 1 to 3 degrees in mesiodistal direction and 2 to 4 degrees in labiopalatal direction as standard deviation. 4. The imaginary axis of the tooth crown of anterior teeth was determined toward labial in the random position and toward patients right and palatal in Standing Posture. 5. It was confirmed that the determination of the imaginary axis of tooth crown was effected by the position of the patient relative to the operator, limitation or direction of view, and approach direction.

The influence of the operating positions on the prepared abutment contour of full cast crowns. The maxillar left posterior fixed prosthodontics

Following are the results of a study made on the influence to the prepared tooth form, when the abutment tooth preparation with full cast crowns are done for the Maxillar Left Fixed Prosthodontics three-unit bridge in Random Position. The prepared teeth arethe Second Premolar and the Second Molar (The“Second Premolar”is abbreviated to “5” and the “Second Molar”is abbreviated to “7”).1. The reduced extent of occlusal surface was excessively large at 5 and 7 buccal cusps, while it was excessively small at Central grooves.2. The reduced extent of axial surface was excessively small at 5 and 7 all surfaces.3. The reduced extent of subgingiva tended to be shallower than the designated depth of 1.0mm at the all portions.4. As for the degree of axial taper, its made steeper toward the buccal and distal surface both 5 and 7.5. As for the relative degree of axial taper, it get the largest in degree on bothsides between5 medial surface and 7 distal surface.

[New porcelains furnace using an infra-red ray heating element. 1. Shear bond testing and surface roughness of dental porcelains].

Recently a new type dental porcelain furnace built in infra-red rays heating elements named “Technomat” was developed. It has many advantages because porcelain fusing begins from metal-ceramics interface not from the outer surface of porcelain. The purpose of this study is to compare the bond strength, surface roughness and edge form of porcelain between conventional type furnace and “Technomat”.And we obtained the following results.1. Push shear bond strength of Ni-Cr alloy named “Uni-metal” by using “Technomat” were 70% greater than that of conventional type. But by Pd alloy “Aurora” and Au alloy “Uni -gold” bond strength showed no significant difference.2. By measuring surface roughness and edge form of porcelain, “Technomat” showed underglazing tendency than the conventional type at the same firing temperature.3. Xray element analyses showed no significant difference between two furnaces. Additional tests must be made by using other Ni-Cr alloys.