Restorative Dentistry & Endodontics

Apical foramen morphology according to the length of merged canal at the apex: Hee-Ho Kim, Jeong-Bum Min, Ho-Keel Hwang; Restor Dent Endod 2013;38(1):26-30. Published online February 26, 2013; DOI: https://doi.org/10.5395/rde.2013.38.1.26

Abstract PDF PubReader ePub: Objectives
The aim of this study was to investigate the relationship between the apical foramen morphology and the length of merged canal at the apex in type II root canal system.
Materials and Methods
This study included intact extracted maxillary and mandibular human premolars (n = 20) with fully formed roots without any visible signs of external resorption. The root segments were obtained by removing the crown 1 mm beneath the cementum-enamel junction (CEJ) using a rotary diamond disk. The distance between the file tip and merged point of joining two canals was defined as Lj. The roots were carefully sectioned at 1 mm from the apex by a slow-speed water-cooled diamond saw. All cross sections were examined under the microscope at ×50 magnification and photographed to estimate the shape of the apical foramen. The longest and the shortest diameter of apical foramen was measured using ImageJ program (1.44p, National Institutes of Health). Correlation coefficient was calculated to identify the link between Lj and the apical foramen shape by Pearson's correlation.
Results
The average value of Lj was 3.74 mm. The average of proportion (P), estimated by dividing the longest diameter into the shortest diameter of the apical foramen, was 3.64. This study showed a significant negative correlation between P and Lj (p < 0.05).
Conclusions
As Lj gets longer, the apical foramen becomes more ovally shaped. Likewise, as it gets shorter, the apical foramen becomes more flat shaped.

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Coincidence between radiographs and clearing samples on the root canal systems of single rooted premolars: Ho-Keel Hwang, Ho-Min Kang, Kang Seo; J Korean Acad Conserv Dent 2005;30(6):461-469. Published online November 30, 2005; DOI: https://doi.org/10.5395/JKACD.2005.30.6.461

The aim of this study was to compare the root canal systems of maxillary and mandibular premolars that had a single root using radiographs and clearing samples. 142 single rooted premolars were selected and mesio-distal and bucco-lingual views were radiographed using intra-oral dental standard films. Four equally trained examiners classify the root canal types from the developed radiographs. After opening the tooth for access, it was stored in 5% NaOCl to dissolve the pulp tissue. Indian ink was then injected into the pulp cavity to stain the pulp tissue. It was cleared in methyl salicylate after being decalcified with 5% nitric acid for 48 hours, and the root canal type was evaluated at a magnification of × 20 using a stereomicroscope.

The results are as follows;

There were statistically significant differences between the radiographs and clearing samples of the root canal types among examiners (p < 0.05). There might be differences in the root canal types among examiners when the same radiograph is used. Therefore, considering the difficulty in estimating the root canal types, clinicians need to be careful when interpreting radiographs before root canal therapy.

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The canal system in the mesiobuccal root of the maxillary first molar: Dong-Hyun Cho, Ho-Young Choi, Sang-Hyuk Park, Gi-Woon Choi; J Korean Acad Conserv Dent 2003;28(3):232-240. Published online May 31, 2003; DOI: https://doi.org/10.5395/JKACD.2003.28.3.232

Abstract PDF PubReader ePub

This study is to investigate the canal system in the mesiobuccal root of the maxillry first molar.

61 maxillary first molars were randomly selected. Serial transverse sections were made perpendicular to the long axis of the mesiobuccal root. Each section was placed in 3% sodium hypochlorite for 24 hours and rinsed in water and dried. The resected surface was stained with 2% methylene blue dye and examined with stereomicroscope.

Canal configuration analysis showed that 36.1% of the specimen classified as type I, 16.4% as type II, 37.7% as type III and 9.8% as type IV.

Type II canal was merged in one canal within 1 to 4mm of the apex. 40% of type II canal converged at 2mm of the apex.

Type IV canal was divided into two canal within 2 to 4mm of the apex. 66.6% of type IV canal branched off at 2mm of the apex.

None of the sections had more than two main root canal.

48.4% of the sections in 3mm with two canals contained an isthmusand more than 70% with two canals has isthmus at 4 to 5mm sections.

63.9% of the mesiobuccal root of maxillary first molar had two canaland 76.5% of sections with two canals in 5 MM had an isthmus. Because of this complexity the clinician should always search for extra canal carefullyand root canal system, including an isthmus, should be cleaned and shaped completelyand obturated three dimensionally for successful endodontic treatment.

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