A Cone-Beam Computed Tomographic Study on Mandibular First Molars in a Chinese Subpopulation

Abstract

The purpose of this study was to conduct a cone-beam computed tomographic (CBCT) investigation on the root and canal configuration of the mandibular first molars, especially the morphology of the disto-lingual (DL) root, in a Chinese subpopulation. A total of 910 CBCT images of the mandibular first molars were collected from 455 patients who underwent CBCT examinations as a preoperative assessment for implants or orthodontic treatment. The following information was analyzed and evaluated: tooth position, gender, root and root canal number per tooth, root canal type of the mesial root(s) and distal root(s), angle of the DL root canal curvature, distance between two distal canal orifices in the teeth with DL root, and angle of disto-buccal canal orifice–disto-lingual canal orifice–mesio-lingual canal orifice (DB-DL-ML). Most of the mandibular first molars (64.9%, n = 591) had two roots with three root canals, and most of the mesial root canals (87.7%, n = 798) were type VI. The prevalence of the DL root was 22.1% (n = 201). The right side had a higher prevalence of DL root than the left side (p<0.05). Additionally, the curvature of the DL root canal were greater in the bucco-lingual (BL) orientation (30.10°±14.02°) than in the mesio-distal (MD) orientation (14.03°± 8.56°) (p<0.05). Overall there was a high prevalence of DL root in the mandibular first molars, and most of the DL roots were curved in different degrees. This study provided detailed information about the root canal morphology of the mandibular first molars in a Chinese subpopulation.

Differences on the Root and Root Canal Morphologies between Asian and White Ethnic Groups Analyzed by Cone-beam Computed Tomography

“…As for the mandibular first molar mesial root, both ethnic groups presented a low prevalence of Vertucci type I morphologies, which is in line with the previous literature (49,50). The most common Vertucci types for this root are Vertucci type II for whites (46.9% in the white group and 12.3% in the Asian group) and type IV for Asians (76.8% in the Asian group and 41.9% in the white group).…”

“…Two Chinese studies reported a type IV prevalence in 87.7% (50) and 93.9% (51) of cases, whereas several predominantly white countries presented a lower prevalence, including Belgium (6) (16.4%), Spain (11) (37.8%), Brazil (52) (40.4%), and Italy (45) (62.4%). The same evidence is available for Vertucci type II results because Chinese studies show a prevalence of 1.7% (51) and 5.6% (50), whereas in predominantly white countries the prevalence of these morphologies was 5.0% in Belgium (6), 27.4% in Italy (45), 38.6% in Brazil (52), and 51.3% in Spain (11). The findings mentioned for the mesial root of mandibular first molars can be extended to second molars and are in agreement with the current literature (9,11,45,52).…”

Prevalence of C‐shaped canal morphology using cone beam computed tomography – a systematic review with meta‐analysis

“…The included studies (n = 25) reported data on 25 445 teeth from 13 142 patients including 2540 maxillary first molars, 3300 maxillary second molars, 5240 mandibular first molars, 11 308 mandibular second molars, 1656 mandibular first premolars and 1401 mandibular second premolars. Evaluation included at least 4110 males and 5559 females, once six studies reported incomplete data regarding gender ratio (Yu et al 2012, Zhang et al 2015, Rogazkyn et al 2016, Pawar et al 2017, von Zuben et al 2017, Pedemonte et al 2018. The average age of the patients was 42.3 years and was calculated based on 18 studies that reported this information.…”

Morphology of Root Canal System of Maxillary and Mandibular Molars

“…The mesial root has two separated canals in about 90% of cases (type IV), and in 10 % the two canals are joined into one canal at the apex (type II), while the distal root usually contains one straight oval canal (type I) (Figure 16). The incidence of C-shaped root canal is low in this tooth and about 2% [60] ( Table 5 shows the root canal configurations for mandibular first molar in recent studies [30,33,[51][52][53][54][55][56][57][58][59]).…”