Durham Anthropology Journal
Volume 12(2-3). Copyright © 2005, Mariusz Lipski, Krzysztof Woźniak, Ryta Łagocka, Mańgorzata Tomasik

Root and canal morphology of the first human maxillary premolar

Mariusz Lipski (1), Krzysztof Woźniak (1), Ryta Łagocka (1), Mańgorzata Tomasik (2)

1. Department of Conservative Dentistry, Pomeranian Medical University, Al. Powstańców Wlkp. 72, Blok 18, 70-111 Szczecin, Poland

2. Department of General Dentistry, Pomeranian Medical University, Al. Powstańców Wlkp. 72, Blok 18, 70-111 Szczecin, Poland

lipam@sci.pam.szczecin.pl

Summary: In this in vitro study the root and canal morphology of the first human maxillary premolar was evaluated. One hundred forty two first maxillary premolars (142 teeth) were examined. After visual inspection, the teeth were radiographed in two planes (mesiodistal and mesiodistal + horizontal angle of 40 degrees). Each tooth was examined as to the number of roots and root canals and their types. Twenty two teeth (15.5%) had one root, 107 (74.3%) had two roots and 13 (9.2%) had three roots. The numbers of canals ranged from one to three. The incidence of type I canals (one canal) was 2.1% (three teeth), whereas 88.6% (126 teeth) in the total samples had two canals (type II and III). Type IV (three canals) was found in 9.2% (13 teeth) in the total samples. In conclusion, the root and canal morphology of the first maxillary premolar evaluated in this study shows a higher incidence of three-root and three-canal forms, and a lower incidence of the one-root and one-canal forms, than previously reported. A knowledge of these variations will assist the dentist when diagnosing and treating endodontic cases.

Key words: Maxillary first premolar - Human - Morphology - Root and root canal

1. Introduction

1.1. Before endodontic therapy is performed, the clinican should know the number of roots and canals of the tooth that is to be treated. False assumptions about root and canal morphology may lead to incomplete debridement and obturation of the canal space and this can eventually lead to endodontic failure.

1.2. When one reviews the literature, it becomes apparent that there is a divergence of opinion concerning the root and canal morphology of the first maxillary premolar. The incidence of one root varied from 22.0 to 49.4%; two roots, 50.6 to 72%; and three roots, 0 to 6% (Carns and Skid 1973, Kartal et al. 1998, Loh 1996, Vertucci and Gegayff 1979). Studies reported by Carns and Skid (1973), Green (1973) and Pineda and Kuttler (1972), dealing with the canal morphology of the first maxillary premolars, have revealed that in most instances they have two canals (from 73.3 to 92%), although teeth with one or three root canals do often exist (from 8 to 26.2% and from 0 to 6%, respectively).

1.3. Clinically, it has been observed in patients from the Pomeranian region that first maxillary premolars have three canals relatively often and very rarely one root canal. Therefore, it was decided to evaluate root and canal morphology in first maxillary premolars from the population of the north-western part of Poland.

2. Materials and methods

2.1. One hundred forty two left and right first maxillary premolars (142 teeth), which had previously been extracted because of trauma, periodontal disease, or orthodontic reasons, were selected. All of the teeth were absolutely identified, at the time of extraction, as maxillary first premolars from Pomeranian region patients. They were washed after extraction and stored in a 10% formalin solution until the collection was complete. Each tooth was cleaned of any adherent soft tissues, bone fragments and calculus by scaling and polishing. The teeth were washed under running tap water and dried using a 95% ethanol solution.

2.2. Visual inspection of the root morphology was made and the findings were recorded. The teeth were classified into groups according to number of the roots (Table 1).

2.3. After visual examination, the teeth were radiographed in two planes (mesiodistal and mesiodistal + horizontal angle of 40 degrees) to evaluate the root canal morphology. Examination of the root canal system of the teeth was based on Wein's classification with some modification (Table 2) (Weine 1996). All teeth and radiographs were evaluated by two endodontists, and classified by agreement.

3. Results

3.1. Twenty two teeth (15.5%) had one root and 107 (74.3%) had two roots. Of the two-rooted premolars, 70 (49.3%) teeth had separate roots, whilst 37 (26%) had fused roots. Thirteen (9.2%) premolars had three roots. Of those premolars presented as having three root forms, five (3.5%) had separate roots, five (3.5%) had fused buccal roots, and three (2.1%) had fused all roots ( Fig. 1).

3.2. The numbers of canals ranged from one to three. The incidence of type I canals (one canal) was 2.1% (three teeth), whereas 88.6% (126 teeth) within the total samples had two canals (type II and III). Of the two-canalled premolars, 117 (82.4%) teeth had two separate canals with two separate foramen apicale (type II), whilst nine (6.3%) had two canals leaving the pulp chamber and joining short of the apex in the form of one canal (one foramen apicale) (type III). Type IV (three canals) was found in 9.2% (13 teeth) of the total samples.

4. Disscusion

4.1. The number of roots and canals in the first maxillary premolar shows wide variation. In the studies concerning root anatomy, the percentage of single-rooted first maxillary premolars has been reported as being from 22.0 to 49.4%. Our study indicates that 15.5 % of the first maxillary premolars had a single root. This is lower than several earlier studies (Carns and Skid 1973, Kartal et al. 1998, Loh 1996, Vertucci and Gegayff 1979) (Table 3). An interesting observation is that our percentage of two-rooted and three-rooted premolars demonstrates a slighly higher percentage than studies conducted in North America (Carns and Skid 1973, Vertucci and Gegayff 1979) and considerably higher than studies of the maxillary first premolars of Turks (Kartal et al. 1998) and Singaporeans (Loh 1996). In the study conducted in Singapore (957 teeth) no three-rooted premolars were detected. The above differences, especially significant in the Singaporean and Polish population, may be explained by racial differences. In Singapore, the population primarily consists of Chinese, with other racial groups being of Indian, Malay and Sri Lankan origin (Mongoloid stock), with only a small percentage of Caucasian (Loh 1996). It is possible that the discrepances between the present data and those from the studies cited result from an imprecise identification of teeth. In our research, all of the teeth studied were absolutely identified, at time of extraction, as first maxillary premolars. However, in most studies cited, the tooth designation was not recorded at the time of extraction as they were not individualy stored and labeled, but identiefied by the coronal morphological features, which have lead to mistakes because of the very small differences in the crown anatomy between the first and second maxillary premolar.

4.2. In this study 13 (9.2%) premolars have three roots. Some teeth have separate roots, others fused. Unfortunately, the results achieved cannot be compared to the results of other investigation as they were not performed.

4.3. In this study, as well as the number of the roots, the number of the canals and their type are also evaluated, which is more important for the clinican. Our study indicates that only 2.1% of the teeth examined have one canal. This percentage is considerably lower when compared with those of earlier studies (Carns and Skid 1973, Green 1973; Kartal et al. 1998; Pineda and Kuttler 1972, Vertucci and Gegayff 1979) (Table 4). Interestingly enough, our findings of 88.6% for two-canalled premolars and 9.2% for three-canalled are higher than all of the previous studies reviewed. The differences above, as with the number of roots, can explained by racial differences and the procedure of teeth identification.

4.4. Various methods are recommended for the anatomic investigation of root canals. Some researches sectioned extracted teeth (Baisden et el. 1992, Weine et al. 1969) or made casts of the root canal system with polyester resin (Carns and Skidmore 1973) or latex rubber (Skidmore and Bjorndal 1971). Others radiographed the teeth from two or more different views (Martinez-Lozano et al. 1999, Weine et al. 1999) or used magnetic resonance microscopy to create a three-dimensional reproduction of the root canal space (Baumann and Doll 1997). However, the most commonly technique used transparent teeth (clearing technique) (Kartral et al. 1998, Vertucci and Gegauff 1979, Vertucci et al. 1974). This study used vacuum injection of ink into the pulp chamber followed by a clearing technique (Yamamoto et al. 2001).

4.5. In this study, the teeth were radiographed to visualize the root canal morphology. Although the radiograph is a two-dimensional image of a three-dimensional object, we managed to achive a relatively good reproduction of the root canal system. Radiographing teeth in two planes enables such a reproduction of the root canal system to be performed. Additionally, it should be remarked that the clinical evaluation of the root canal system is possible only by taking into consideration such radiography.

4.6. In conclusion, the root and canal morphology of the first maxillary premolar shows a higher incidence of three-root and three-canal forms, and a lower incidence of one-root and one-canal forms, than previously reported. A knowledge of these variations will assist the dentist when diagnosing and treating endodontic cases.

5. References

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Baumann MA, Doll GM (1997) Spatial reproduction of the root canal system by magnetic resonance microscopy. J Endod 23: 778-784

Carns EJ, Skidmore AE (1973) Configuration and deviations of root canals of maxillary first premolars. Oral Surg 36: 880-886

Green D (1973) Double canals in single roots. Oral Surg 35: 690-691

Kartal N, Ozelik B, Cimilli H (1998) Root canal morphology of maxillary premolars. J Endod 24: 417-419

Martínez-Lozano MÁ, Forner-Navarro L, Sánchez-Cortés JL (1999) Analysis of radiographic factors in detremining premolar root canal systems. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 88: 719-722

Loh HS (1998) Root morphology of the maxillary first premolar in Singapoureans. Aust Dent J 43: 339-402

Peters LB (1992) Präparation der endodontischen Zugangskavität und Darstellung der Kanäle. Teil I: Prämolaren. Endodontie 2: 141-149

Pineda F, Kuttler Y (1972) Mesiodistal and buccolinqual roentgenographic investigation of 7,275 root canals. Oral Surg 33: 101-110

Skidmore AE, Bjorndal AM (1971) Root canal morphology of the human mandibular first molars. Oral Surg 32: 778-784

Vertucci FJ, Gegauff A (1979) Root canal morphology of the maxillary first premolars. J Am Dent Assoc 99: 194-198

Vertucci F, Seeling A, Gillis R (1974) Root canal morphology of the human maxillary second premolar. Oral Surg 38: 456-464

Weine FS (1996) Endodontic Therapy. 5th ed., Mosby-Yearbook, St. Louis, 242-243

Weine FS, Healey HJ, Gerstein H, Evanson L (1969) Canal configuration in the mesiobuccal root of the maxillary first molar and its endodontic significance. Oral Surg 28: 419-425

Weine FS, Hayami S, Hata G, Toda T (1999) Canal configuration of the mesiobuccal root of the maxillary first molar of a Japanese sub-population. Int Endod J 32: 79-87

Yamamoto T, Domon T, Takahashi S, Islam N, Suzuki R (2001) A resin embedding method for transparent teeth with ink-infiltrated pulp cavities. Ann Anat 183: 481-483