Morphometric Analysis of Maxillary Central Incisor to Determine its Crown Form: A Model‑based Cross‑sectional Study

The size and shape of tooth crowns are morphogenetically predetermined during embryogenesis.The maxillary central incisors have contributed to sexual dimorphism,and several classifications of the form of maxillary central incisors are available in the literature.We,in the present study,aimed to analyze the mesiodistal(MD)measurements at two levels of maxillary central incisor,to determine its crown form.The study was conducted on 100 dental plaster models(50 males and 50 females).The MD dimensions at the contact area level MD_incisal(MD_I)and at the gingival papilla level(MD_G)and the gingivo‑incisal height of the crown were measured in the dental models using digital Vernier caliper.The data were analyzed using SPSS version 16 statistical software.The mean values of all the three parameters measured were slightly greater for males and also for the left central incisors.There were no significant differences in all the three variables when the right and left incisors were compared.Significant differences were noted when the parameters are compared between genders.The height/width ratio of crown showed a significant difference between male and female.The value of the ratio between the two MD dimensions(MD_I and MD_G)was used to determine the crown form.The ratio between the MD dimensions at incisal and gingival area showed a significant difference between genders and no such significance was found between right and left central incisors.There is a significant difference in the form of maxillary central incisors between male and female samples and not between right and left.The MD dimensions at incisal and gingival thirds decide the form of crown.

Correlation between Maxillary Central Incisor Crown Form and Maxillary Dental Arch Form:A Model‑Based Morphometric,Cross‑Sectional Study

The crown form of maxillary central incisor tooth is one of the vital phenomenon for a person’s esthetics.Its crown form has been compared with other anatomical parameters such as arch form and facial form.Three different classes of tooth forms which relate to square,tapered,and ovoid forms are identified.The aim of this study was to morphometrically evaluate the correlation between maxillary dental arch form and the maxillary central incisor crown form.Dentate cast models of fifty male and fifty female normal occlusion controls in the age group of 18-23 years were analyzed.The mesiodistal(MD)dimensions of the maxillary central incisors were measured at incisal(MD_I)and at gingival(MD_G)levels.The transverse widths of maxillary casts were measured at the first molar and at the first premolar levels.The measured data were statistically analyzed using the SPSS software.The MD dimensions of maxillary central incisor were significantly greater in males than females.The ratio between the two MD dimensions also varied significantly among genders.The intermolar width(IMW)and interfirst premolar width(IPmW)between males and females were highly significant(P<0.05),whereas the ratio between these two parameters in males and females was not significant(P=0.43).Eighty‑eight percentage of the participants were found to have an ovoid type of maxillary arch,while only 45%of them had the ovoid form of maxillary central incisors.The MD_I and the IMW were found to be in the ratio of 1:5.5 in both genders.The MD_G and the IPmW were in the ratio of 1:4.7 in males and 1:4.5 in females.There was a weak positive correlation between MD_I and IMW(r^(2)=0.146)and between MD_G and IPmW(r^(2)=0.05).No significant concordance between the maxillary central incisor crown form and the maxillary arch form was found in this study.