A comparison analysis of the anatomic crown width/length ratios of with and without attrition maxillary teeth between Asian and Caucasian subjects.

摘要

Background. Dimensions of teeth have gathered many interests in order to create more natural and esthetic form on maxillary anterior recognized as esthetic zone. Specially, the crown width/length ratios considered as important valuable on esthetic zone was focused since 1990's. However, all of investigations have been conducted among Caucasian populations, therefore, the other factor such as ethnicity should be also taken into consideration in order to lead comprehensive treatment plan on maxillary anterior zone.;Purpose. The purpose of this study was to analyze the anatomic extracted crowns of 4 tooth groups (central incisors, lateral incisors, canines, and first premolars) of the maxillary dentition with respect to width, length and width/length ratios among Asian populations to compare with the reported data of Caucasian subjects.;Material and methods. Standardized digital images of 264 extracted human maxillary anterior teeth from Asian subjects (91 central incisors, 76 lateral incisors, 54 canines, 43 first premolars) and 146 extracted human maxillary teeth (44 Central Incisors, 41 Lateral Incisors, 38 Canines, 23 First Premolars) from Caucasian subjects were used to measure the widest mesiodistal portion "W" (in millimeters) and the longest inciso-cervical/occluso-cervical distance "L" (in millimeters). The width/length ratio "R" (%) was calculated for each tooth. The data was then transferred to a spreadsheet program for mathematical treatment, including the calculation of the width/length ratio "R". Statistical analysis was carried out to compare the 3 tooth groups (central incisior, lateral incisiors and canine) between both esthnicity. Sample t-test was applied to each individual group in order to make comparison between Asian and Caucasian subjects for the width, length, and width/length ratios.;Results. (a) Unworn down teeth (Pristine teeth) A summary of the width, length and W/L ratio of the four tooth types of the unworn maxillary dentition in Asian and Caucasian groups and comparison data in each parameter between both ethnicities, are presented in this study. There was a statistically significant difference (p<0.05) of the width of central incisors between Asian and Caucasian groups. In addition a statistically significant difference of the length of lateral incisors and canines was present between the two groups. Most importantly, there was a significant difference of width/length ratios of all maxillary anterior teeth. (b) Worn down teeth (attrition teeth).;A summary of the width, length and W/L ratio of the four tooth types of the maxillary dentition with attrition in Asian and Caucasian groups and comparison data in each parameter between both ethnicities, are presented in this study. There was a statistically significant difference (p<0.05) in the width of central incisors and of canines between Asian and Caucasian groups. Also, a statistically significant difference in the length of central incisors and canines was presented between two groups. In addition, there was a significant difference in width/length ratios of the central incisors and canines.;Conclusions. This work investigated the anatomic crown of the four anterior maxillary tooth groups of Asian and Caucasian subjects (central incisors, lateral incisors, canines, and first premolars) with respect to width (W), length (L), and width-length ratios (R), with special attention to distinguish among unworn teeth for a selected group of tooth specimens. Within the limitations of this study, the following conclusions were drawn: (1) Width/length ratios showed significant differences in all four anterior unworn down maxillary tooth groups between both ethnic groups. Anterior maxillary teeth in Asian subjects appear to be more slender shape compared with Caucasian subjects. (2) There are variations between the dimensions of maxillary anterior teeth of Asian subjects when compared with those of Caucasians. (3) This variation should be considered prosthodontically and biologically when performing surgical and/or restorative treatments on maxillary anterior sextant of a subject from a specific ethnic group.