根尖切除術により生ずる切除面の露出象牙質に関する研究

―象牙質の色素浸透性と走査型電子顕微鏡観察―

抄録

Abstract : When the resected surface is examined after apicoectomy, openings of dentinal tubules, lateral canals and minute cracks are observed other than the smear layer. The failure of apicoectomy or the recurrence may be due to the method of surgery or the operator. However, the condition of resected surface may be one of the causes of unsatisfactory result of the operation. In order to examine the influence of the exposed dentin after apicoectomy, the dye penetration test and scanning electron microscopic observation were conducted to the resected surface.

 Seventy-five extracted human upper central incisors were kept in physiological saline solution. After the crowns were removed, the apex of each tooth was resected by 3 mm using a diamond slice disk through running water. Of the 75 teeth, 50 were vertical sectioned and 50 samples were obtained. They were divided into five groups as each group has 10 teeth. Group 1 : Resected surface was treated by 10% phosphoric acid solution for 30 seconds. Group 2 : The surface was treated with self-etching primer followed by application of resin adhesives (Cliarfil Liner Bond-2, Kuraray Japan) and then coated with a light-activated low viscosity composite resin (Protect Liner-F, Kuraray). Group 3 : Nd : YAG laser was applied to the surface. Group 4 : The surface was treated by 10% phosphoric acid solution and then Nd : YAG laser was applied. Group 5 : The surface was not treated. Dye penetration test was conducted to all samples of five groups. The remaining 25 teeth were divided into five groups and were also treated by the same manner employed in the 5 groups. Then the resected surfaces were observed by scanning electron microscope.

 The result shows that the samples in Group 2 and 4 have significantly low degree of dye penetration. The smear layer covered the resected surface of all the test samples before the surface treatment. The smear layer was removed after the treatment using 10% phosphoric acid solution, the application of self-etching primer and laser irradiation. Opened dentinal tubules were coated with the low-viscosity resin or sealed by the application of laser after removing smear layer.

 It is suggested from this study that the application of composite resin coating or laser irradiation after removing the smear layer were capable to seal the opened dentinal tubules on the resected surface, which might cause the dead space or connect the root canal to apical periodontal tissue.