RESUMO
Objective To study the relative effects of environment and genes on the soft tissue surface plane during the mixed dentitions, and to provide theoretical evidence to establish the correct teeth treatment plan. Methods The lateral cephalograms of one hundred and eighty-three female twins from six to twelve years old were studied. The environmental and genetic effects were analyzed on soft tissue profile by twin method. Results The influence of environmental factors was detected by measurement items of subnasale (F3), upper lip concave point(F4),upper lip sudden point (F5), upper stomion(F6), lower stomion(F7), lower lip sudden point(F8), lower lip concave point(F9), menton of soft tissue(F10)(P<0. 05). Among them,lower stomion(F7)and lower lip sudden point(F8)were more affected by environmental impact, the influence of environmental and genetic factors was detected by measurement items of subnasale(F3),upper lip concave point(F4),and lower lip concave point(F9). Conclusion The lower lip is more be influenced by environmental factors, whereas the subnasale, upper lip concave point,and lower lip concave point are mainly by both the environmental and genetic factors.
RESUMO
Objective To study the safety and effectiveness of the double chain method on the closure of the space of the teeth. Methods Totally 72 cases of different maxillary and mandible dentition space were included in the study. The pulp vitality was measured before and after treatment, the maxillary and mandible first molar teeth. All values were compared to assess the safety of dental pulp vitality. There were 36 cases in tooth extraction group and non-tooth extraction group.The observation period was 4 weeks, the changes of the alveolar space between maxillary and mandible teeth in adult and minor groups were measured before and after treatment. The difference of the total groove spacing before and after treatment were calculated and compared, to assess the effectiveness of space closure. Results In all 72 patients, there was no significant difference in the vitality of the pulp before and after treatment (P>0. 05). Compared to before treatment, the sum of the distance between the upper and lower mandibular groove using the double chain method was significantly reduced for both adult and juvenile patients in the four week tooth extraction group and the nontooth extraction group,the difference was statistically significant (P<0. 05). Conclusion Double chain closed teeth space does not cause pulp degeneration and necrosis. It is safe in clinical practice. Double chain method is effective, and can simplify the clinical operation.