Root canals and apical foramina of the buccal root of maxillary first premolars with longitudinal sulcus

Abstract

In the present study, periapical radiographs were analyzed to investigate the number of canals of the buccal root of maxillary 1st premolars with longitudinal sulcus, and compare the number of apical foramina observed on the radiographs to that revealed by scanning electron microscopy (SEM). Thirty-nine human maxillary 1st premolars had their crowns and palatal roots removed and the root canals (C) were explored with endodontic files until the tip of the instrument was visualized exiting the apical foramen/foramina (AF). Radiographs were taken with files inside the root canals and the specimens were classified as follows: 1C/1AF; 2C/2AF; 1C/2AF; 2C/1AF. Apices were examined under SEM and the number of apical foramina (considering those measuring >80 µm in diameter) was recorded. Only 17.1% (n=6) of the specimens had 1C/1AF; 77.2% (n=27) had 2AF in which 42.9% (n=15) had 2C and 34.3% (n=12) had 1C; 5.7% (n=2) had 2C/1AF. SEM examinations showed that 46.1% (n=18) of the specimens had 2AF; 23.1% (n=9) had 1AF; 23.1% (n=9) had 3AF; 7.7% (n=3) had 4AF. Radiographic and SEM findings for the number of AF coincided in 62.8% of the cases. A buccal longitudinal sulcus in the maxillary 1st premolar is usually accompanied by total bifurcation (42.9%) or apical bifurcation (34.3%) of the root canal. SEM identified a statistically higher number of apical foramina than radiographs (p<0.01).

Translated abstract

Avaliamos radiograficamente o número de canais da raiz vestibular de 1º pré-molares superiores com sulco longitudinal vestibular, e comparamos com microscopia eletrônica de varredura (MEV) quanto ao número de forames apicais (FA). As coroas e raízes palatinas de 39 dentes foram amputadas e os canais radiculares (C) explorados com lima endodôntica fina até suas pontas serem visualizadas apicalmente. As raízes foram radiografadas com as limas em seu interior e classificados pelo critério a seguir: 1C/1FA; 2C/2FA; 1C/2FA; 2C/1FA. Os ápices da raiz vestibular foram seccionados e preparados para MEV. Os números de FA (>80 µm) foram obtidos. A avaliação radiográfica demonstrou que 17,1% (n=6) das raízes apresentaram 1C/1FA 77,2% (n=27) tinham 2FA, sendo 42,9% (n=15) oriundos de 2C, e 34,3% (n=12) de 1C; 5,7% (n=2) apresentaram 2C terminando no mesmo FA. Em MEV, 46,1% (n=18) dos ápices apresentaram 2FA; 23,1% (n=9), apenas 1FA; 23,1% (n=9), 3 FA; e 7,7% (n=3), 4 FA. Houve correlação entre o diagnóstico radiográfico e MEV quanto ao número de FA em 62,8% dos casos. O sulco longitudinal vestibular no primeiro pré-molar superior predispõe à bifurcação total (42,9%) ou apical (34,3%) do canal radicular; sendo o método radiográfico estatisticamente inferior (p<0.01) à MEV no diagnóstico de FA.