title: Descriptive classification of variations in primary mandibular first molars.
abstract: Variability in tooth morphology can play a significant role in the achievable results of restorative treatment. This study identified the variations of morphology of the primary mandibular first molar (Type I and II coronal outline and Type A-F cusp alignment.) Type I coronal outline was found more frequently (86 percent) than Type II (14 percent). 93 percent of the primary mandibular first molars comprise four cusps, 5 percent comprise five cusps, and 2 percent comprise 3 cusps (F). Among the four-cusp group, 70 percent had an oblique transverse ridge (C), 25 percent had a poorly developed transverse ridge (A). Among the five-cusp-group, 67 percent had a distal cusp (E), and 33 percent had a fifth lingual cusp (D). The most frequent combination of coronal outline and cusp alignment was Type I-C (60 percent), and followed by Type I-B (22 percent), II-C (5 percent), and II-A (4 percent).
authors.affiliation: Department of Pedodontics, School of Dentistry, China Medical College, 91 Hsueh Shih Road, Taichung, 404 Taiwan.
authors.forename: H H
authors.initials: HH
authors.lastname: Tsai
mesh_terms: D002648:Child; D002965:Classification; D003724:Dental Arch; D003743:Dental Enamel / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008334:Mandible; D003765:Models, Dental; D008963:Molar / Q000033:anatomy & histology*; D009811:Odontometry; D010781:Photography; D014094:Tooth, Deciduous / Q000033:anatomy & histology*