The correlation between observation distance and the width ratio of maxillary anterior teeth
Objective:To study the variation of the ration between the maxillary anterior teeth and different observation distance with front-view horizontally,and to provide a reference for the research and clinical determination of the width of maxillary anterior teeth.Methods:The natural dentition of males and females with normal tooth morphology and neat dentition,as well as showing beautiful teeth when smiling were selected as the research subjects.Taking plaster models of the maxilla and mandible,front-view photographs of the maxillary teeth were taken at distances of 20,40,80,60,110,and 140 cm,respectively.The measurements were conducted in AutoCAD 2015,with a significance level of P=0.05.The means of each group were tested for normal distribution,the paired design mean comparison t-test was used to compare the means of the left and right sides,the variance analysis of randomized block design data was used to compare the mean values of the visual width ratio of the maxillary front teeth taken at different distances.Results:There was a significant difference in the width ratio of the maxillary anterior teeth between the 20 cm distance shooting group and other distance shooting groups.There was no significant difference in the width ratio of the maxillary anterior teeth between the 40 cm and above distance shooting groups.The width ratio of the maxillary lateral incisor to the central incisor was 0.75±0.05,and the width ratio of the maxillary canine to the lateral incisor was 0.81±0.07 taken at a commonly used distance(60 cm).The width percentage of the maxillary anterior teeth was(12.28±0.56)%for the right canine,(15.61±0.71)%for the right incisor,(21.42±0.78)%for the right central incisor,(21.57±0.67)%for the left central incisor,(16.12±0.83)%for the left incisor,and(12.99±0.87)%for the left canine.Conclusion:When viewed from front-view horizontally,an observation distance of 40 cm and above has no effect on the width ratios of the maxillary anterior teeth.When the width of maxillary anterior teeth was studied or clinically observed,the researcher should be positioned in the midsagittal plane of the subject,and the observation distance should be more than 40 cm.
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