Mesio-distal Tooth Angulation in Elderly with Many Remaining Teeth Observed by 3-D Imaging

Abstract

Few studies have investigated the morphologic characteristics of teeth, dental arches and occlusion in elderly persons with many remaining teeth. The purpose of this study was to establish a method of measurement using 3-D imaging to investigate tooth angulation in the elderly from the orthodontic point of view. The dental casts of 20 elderly persons with many remaining teeth were digitized with a 3-D laser scanner (VMS-100F, UNISN INC., Osaka, Japan) to construct 3-D images. The mesio-distal angulation of each tooth was then measured with analytical software (SURFLACER, UNISN INC. and IMAGEWARE 12, UGS PLM Solutions, MO, USA). The occlusal plane formed by the incisal edge of the central incisor and distal buccal cusp tip of the first molar on either side was used as a reference plane for measurements. Mesio-distal tooth angulation (indicated in degrees) of maxillary teeth in this subjects averaged 1.26 for central incisors, 5.46 for lateral incisors, 7.84 for canines, 6.59 for first premolars, 5.78 for second premolars, 1.64 for first molars and ‫71.4מ‬ for second molars. Average values for mandibular teeth were 0.91 for central incisors, 2.35 for lateral incisors, 7.04 for canines, 8.76 for first premolars, 10.44 for second premolars, 7.33 for first molars and 12.67 for second molars. There was no statistical difference between the data in man and women except maxillary second molar (pϽ0.05). Mesial angulation in the mandibular arch showed a progressive increase from the anterior to the posterior. However, this tendency was not observed in the maxillary arch.

Change in Anterior Crowding over 20 Years from Third Decade of Life in Untreated Angle Class I Crowding

“…The 3-dimensional (3-D) shape of the parallel dental casts was inputted using a noncontact shape measuring system (VMS-100F, UNISN, Osaka, Japan). It was measured using a 3-D point processing software package (Imageware 13, Siemens PLM Software, Inc., Plano, TX, USA) 7,8,19,26) .…”

“…2) Angulation ( Fig. 3) The angle formed by the tooth crown axis and a line orthogonal to the occlusal plane was calculated 8) . Mesial inclination of the crown with respect to the occlusal plane is indicated as positive (+) and distal inclination as negative (−).…”

Effect of Different Bracket Prescriptions on Orthodontic Treatment Outcomes Measured by Three-dimensional Scanning

“…(1) Angulation (mesiodistal axial inclination of the teeth) (Figs. 2,3) Angulation was measured using the method described by Fuma et al 6) . First, the tooth axes were determined.…”

“…The same 3-D model shape measuring apparatus as that used by Tanoi et al 18) and Fuma et al was used here also 6) . Models have traditionally been measured using a direct manipulative method 15) ; however, the recent application of computers and laser scanners in the field of dentistry has enabled more precise 3-D model shape measurement of the teeth.…”

Dimensions of central incisors, canines, and first molars in subjects with Down syndrome measured on cone-beam computed tomographs

“…3,8,9 Other 3-dimensional analysis tools developed in recent years, including stereophotogrammetry 2 and laser scanning, 8,10 allow more complex measurements, such as mesiodistal angulations. 8 Two-dimensional records include digital photographs, 11 panoramic x-rays, 12 and, in particular, periapical x-rays. 13 Cone-beam computed tomography (CBCT) is a new tool for measuring tooth dimensions.…”