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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 1  »  Root and canal morphology of Thai mandibular molars
Root and canal morphology of Thai mandibular molars
Introduction - Materials and methods.

The study of root and canal anatomy has endodontic (Vertucci 1984) and anthropological (Tratman 1950, Dahlberg 1965, Walker 1988a,b) significance. It is important to be familiar with variations in tooth anatomy and characteristic features in various racial groups since such knowledge can aid location and negotiation of canals, as well as their subsequent management. Additionally, a number of studies have shown different trends in shape and number of roots and canals amongst the different races (Somogyi-Csimazia & Simmons 1971, Curzon 1974, Vertucci & Williams 1974, Cooke & Cox 1979, Reichart & Metah 1981, Walker & Quackenbush 1985, Walker 1988a, Weine et al . 1988, Yang et al . 1988, Manning 1990a,b, Melton et al . 1991, Sperber & Moreau 1998, Weine & members of the Arizona Endodontic Association 1998, Haddad et al . 1999). These variations appear to be genetically determined (Curzon 1974) and are important in tracing the racial origins of populations.
One example of such variation is the mandibular first molar with three roots. This variant has a frequency of less than 5% in white people (British, Dutch, German, Finnish and other European), African (Bushmen, Bantu, Senegalese), Eurasian and Indian populations, whereas in those with Mongoloid traits, such as the Chinese, Eskimos and Native Americans, it occurs with a frequency of 5 to over 40% (Somogyi-Csimazia & Simmons 1971, Curzon 1974, Vertucci & Williams 1974, Reichart & Metah 1981, Walker & Quackenbush 1985). Another reported variation is the ‘C-shaped root and canal configuration’. Seldom found in white people, they have a relatively high prevalence in mandibular second molars of Chinese and Lebanese populations (Walker 1988b, Weine et al . 1988, Yang et al . 1988, Manning 1990a, Weine & members of the Arizona Endodontic Association 1998, Haddad et al . 1999).

Classification of root canal system types
Figure 1. Classification of root canal system types.

The population of Thailand originates from a mixture of Indian and Chinese emigrants. The aim of this study was to investigate the relative contribution of Mongoloid and Caucasian traits in root and canal morphology of Thai mandibular molars.

Materials and methods.
The sample teeth comprised 351 mature mandibular permanent molars extracted from patients attending the Oral Surgery Department of the Christian and Rajchaviti hospitals in Bangkok. All attached soft tissue and calculus was removed using an ultrasonic scaler and by soaking the teeth in 3% sodium hypochlorite. The teeth were classified into first (118), second (60) or third (173) molars based on crown morphology. Access cavities were cut and pulp tissue was removed by immersion in 3% sodium hypochlorite overnight before placement in an ultrasonic bath. The teeth were then rinsed under running tap water for 2 h and dried overnight. An endodontic irrigating syringe with gauge 27 needle (Sherwood Medical Company, St. Louis, USA) was used to inject the Indian ink (Calder Colours Ltd, Ashby-de-la-Zouch, Leicester, UK) into the root canal systems. Ink penetration was assisted by vacuum suction applied apically. The teeth were air dried and immersed in 10% nitric acid (MJ Patterson, Dunstable, UK) to decalcify for between 5 and 14 days. The acid solution was changed daily and the end-point of decalcification determined by periodic radiography. The teeth were washed under running tap water, dried and dehydrated using ascending concentrations of ethanol (70%, 95%, 100%) for 3 days. Finally, the teeth were rendered transparent by immersion in methyl salicylate (Merck Ltd, Poole, UK) for 2 days.
The following observations were made: (i) number of roots and their morphology; (ii) number of root canals (defined as root canal orifices in the pulp chamber) per tooth; (iii) number of root canals per root; (iv) root canal configuration in each root using Vertucci’s classification (1984) with additional modifications (Fig. 1); and (v) presence and location of lateral canals and intercanal communications. Lateral canals were defined as those branches of main canals that diverged at right or oblique angles to exit on the lateral aspect of the root. Inter-canal communications were defined as those complex canal ramifications that ran from and between main canals but did not communicate with the root surface.