[Study on obturating efficiency of Gutta-percha point as a root canal filler. Difference in results among combinational usages of hand reamers and files].
The last treatment step followings extirpation of pulp from an infected root canal is root canal filling. Before root canal filling is done, however, the canal must be enlarged enough and the infected dentin and debris removed thoroughly from the canal. Furthermore, re-infection from the apical foramen at the apex of the root canal should be prevented. In this study, we examined the root apex sealing ability of gutta-percha points applied by the lateral condensation method and the vertical condensation method, as well as the difference in root canal sealing ability of gutta-percha points when either a hand reamer or file or their combination was used for root canal enlargement. Extracted human upper incisors were used for root canal enlargement. The condition of the root canal wall after enlargement was observed by scanning electron microscope. The fitness between the wall and gutta-percha was determined by observation of replicas filled with gutta-percha. Furthermore, to assess the degree of apex sealing after root canal filling, we immersed the extracted teeth in Indian ink for 1 day, 3 days, 1 week, 2 weeks, or 4 weeks (Indian ink permeation test). The results obtained were as follows: 1. Reamer and K-file could smooth the root canal wall more than H-file by the scratch-up method. And also the instruments used by the rotation method formed a sure apical seat, which resulted in film apex filling. 2. By the observation of gutta-percha point-filled replicas we noted a border line between the apical seat and apical foramen when the lateral condensation method was used, whereas the line was not observed with the vertical condensation method. 3. Between the 2 filling methods there was no difference in the ink permeation by Indian ink permeation test, but high sealing ability was observed in the root canal in which a sure apical seat had been formed.