하악대구치의 근관형태에 관한 연구

Abstract

The aim of this study was to compare the canal types between the mesial and distal roots of the mandibular molars that have a high frequency of endodontic failure. Eighty-six mandibular molars were selected after taking radiographs of the mesio-distal and bucco-lingual views using intra-oral dental standard films. After opening the pulp chamber for access, it was placed in 5％ NaOCl for 48 hours to dissolve the pulp tissue. Indian ink(Winsor and Newton: Black Indian Ink #951, England) was then injected into the pulp cavity in order to stain the pulp tissue using a vacuum system. It was cleared in methyl salicylate after being decalcified with 5％ nitric acid for 48 hours and dehydrated in ascending concentrations of alcohol (80, 90, and 100％). Five inspectors (Four undergraduate students, and one endodontist) evaluated the root canal types using a stereomicroscope (Olympus, Japan) at a magnification of x10, x20 according to Weine's classification, and the data was analyzed statistically. The results are as follows: 1. On the mesial root canal types of the mandibular molars, the frequency of type Ⅱ (47.91％) was higher than types Ⅰ (8.37％), Ⅲ (37.67％), and IV (6.05％) (p<0.05). 2. On the distal root canal types of the mandibular molars, the frequency of type Ⅰ (66.98％) was higher than types Ⅱ (16.74％), Ⅲ (10.23％), and IV (6.05％) (p<0.05). 3. In a comparison of the coincidence among the undergraduate students on the mesial root canal types of the mandibular molars, all coincided approximately 41.86％, three of them coincided approximately 37.21％, each two of them coincided approximately 15.12％, two of them coincided and remaining two disagreed approximately 5.81％ of the time, and none of them disagreed. 4. In a comparison of the coincidence among the undergraduate students on the distal root canal types of the mandibular molars, all coincided approximately 51.16％, three of them coincided approximately 23.26％, each two of them coincided approximately 13.95％, two of them coincided and remaining two disagreed approximately 11.63％ of the time, and none of them disagreed. 5. In a comparison of the coincidence between the undergraduate students and the endodontist, the agreement was 61.05％ on the mesial root canal systems, and was 66.86％ on the distal root canal systems of the mandibular molars (p<0.05). The mesial root canal types of the mandibular molars have higher frequency of a type Ⅱ canal configuration which are much more difficult to interpret, instrument and obturate than the distal roots. For this reasons, endodontic failures might occur in the mesial roots of the mandibular molars. Considering the difficulty in evaluating the root canal types, clinicians need to take care when interpreting the radiographs prior to root canal therapy.