RESUMO
Objective@# To study the buccolingual inclination of posterior premolars and molars and the curve of Wilson in patients with different sagittal skeletal patterns, to explore the compensation mechanism of horizontal inclination of posterior teeth in patients with different sagittal skeletal patterns and to provide a reference for the control of posterior tooth inclination in the treatment of bone malocclusion.@*Methods@#This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. Ninety CBCT scans of adults and ninety scans of adolescents before orthodontic treatment were evaluated in this cross-sectional study. There were 30 skeletal Class I, Class Ⅱ, and Class Ⅲ patients in the adult group and adolescent group. The inclination angles of posterior teeth and the curve of Wilson of first and second molars were measured, and data were analyzed between adolescents and adults with different sagittal skeletal patterns.@*Results @#Compared with skeletal Class Ⅰ adult patients, the upper posterior molar inclination of skeletal Class Ⅱ patients was significantly lower, and the lower posterior molar inclination was significantly higher. Compared with skeletal ClassⅠ adult patients, the upper posterior molar inclination of skeletal Class Ⅲ adult patients was higher, and the lower posterior molar inclination was significantly lower. The Wilson curve of the second molar in skeletal Class Ⅱ adult patients was significantly higher than that in the other groups. Compared with skeletal ClassⅠ adolescent patients, skeletal Class Ⅲ adolescent patients had a significantly higher upper posterior molar inclination; however, no difference was found between the inclination of the posterior teeth between skeletal Class Ⅰ, Class Ⅱ and Class Ⅲ adolescent patients. Comparing adolescent and adult samples, in skeletal Class Ⅱ patients, adults showed more lingual inclination than adolescents in the upper posterior teeth and less lingual inclination in the lower posterior teeth except for the mandibular first molar. Comparing adolescent and adult samples, in skeletal Class Ⅲ patients, adults showed more lingual inclination than adolescents in the lower posterior teeth except for the mandibular second molars and showed no difference in the upper posterior teeth.@*Conclusions@#The inclination of the posterior teeth and the curve of Wilson show significant differences between the three sagittal skeletal patterns. Compared with those of skeletal Class Ⅰ patients, the posterior teeth of skeletal Class Ⅱ patients show more lingual inclination in the upper arch and less lingual inclination in the lower arch. Meanwhile, posterior teeth of skeletal Class Ⅲ patients show more lingual inclination in the lower arch and maintain the inclination in the upper arch.
RESUMO
Objective@#To analyze the correlation between skeletal vertical patterns and mandibular dental arch width, basal arch width and the dental buccolingual inclination of patients with skeletal ClassⅠ@*Methods@#The CBCT data of 62 skeletal ClassⅠ malocclusion patients were collected and divided into a high-angle group with 19 cases, a mean-angle group with 22 cases, and a low-angle group with 21 cases according to the GoGn-SN angle. Mandible 3D reconstruction of the three groups was performed using Dolphin software, and dental arch widths, basal arch widths and buccolingual inclination of canines, first premolars and first molars, were measured and statistically analyzed respectively. @*Redults@#Mandibular dental arch width showed no significant difference among the three groups (P>0.05). The basal arch widths of mandibular canines and first premolars in low-angle group were larger than those in the other groups (P<0.05). The buccolingual inclinations of mandibular canines and first premolars in high-angle group were larger than those in the other groups (P<0.05). The buccolingual inclination and basal arch width of the first molars among the three groups showed no significant differences (P>0.05). Pearson correlation tests showed that the basal arch widths of mandibular canines and first premolars were negatively correlated with GoGn-SN angle. Excluding the influence of dental arch width and basal arch width, there was still a significant positive correlation between the buccolingual inclination of mandibular canines and first premolars and the GoGn-SN angle (P<0.05).@*Conclusion@#The width of the basal bone arch between different skeletal vertical patterns mainly differs in the canine segment and the premolar segment, and the difference in the buccolingual inclination of the teeth is mainly to compensate for the difference in the GoGn-SN angle. In clinical practice, individualized therapy should be adopted according to the differences to achieve the long-term efficacy of correction.
RESUMO
Introduction: The general feature of occlusal curvature,when viewed from the front, consists of a buccal inclinationof the maxillary molars and a lingual inclination of themandibular molars. The fourth key of Andrews six keys ofocclusion is related to the curve of Wilson, describing theposterior inclination of the crowns of the lower posterior teethas a concave curve, setting the molars with a lingual torque.The aim of this study was to measure buccolingual inclinationof maxillary and mandibular first molars in untreated sampleof pre-orthodontic patients.Material and Methods: CBCT scans from 36 untreatedsubjects (26 females and 10 males; average age, 24.6 years) withminimal dental discrepancies, no prior history of orthodontictreatment, minimal dental wear, no posterior crossbite, nocrowns or significant restorations on any first molars, absenceof remaining primary dentition, were selected. The angleswere measured between long axis of each maxillary molar to avertical reference line that was perpendicular to the horizontalreference line and between each mandibular first molar to thesame reference line.Results: The average inclination of maxillary molar was+4.98º ± 4.26º. There was no significant difference betweenthe right and left mean values. The average inclinationof mandibular molar was -13.10º ± 6.10º. There was nosignificant difference between the right and left values.Conclusion: Maxillary and mandibular molars have a naturalcurvature of their inclinations where the maxillary molarshave a slight buccal inclination and mandibular molars have aslight lingual inclination
RESUMO
Background and Objective: Buccolingual inclination of teeth is an essential factor in establishing good occlusion. The objective of this study was to evaluate the buccolingual inclination of molar teeth in different vertical skeletal patterns by using computed tomography scans. Materials and Methods: Coronal section of the jaws obtained from computed tomograms were used to measure the buccolingual inclination of the long axis of the molars relative to their skeletal base. Forty male adult individuals with class I dental occlusion were selected. They were classified as short (Group 1), average (Group II), and long faced (Group III) as per their skeletal patterns measured by GoGn-SN, FH-MP, Y-axis and facial height index in cephalograms. Statistical Analysis: ANOVA and Tukey HSD tests were applied to calculate if there were any significant differences in the mean molar inclination between the groups. Pearson's coefficients of correlation were calculated between the facial parameters and tooth inclination. Results: The differences in the mean molar inclination between the short, average, and long faced groups is significant for mandibular 1 st and 2 nd molars and maxillary 2 nd molars. Conclusion: Variations in mean molar inclination values are observed between short, average, and long faced groups.