Clinical Study About The Vertical Changes Of Face In The Treatment Of The Adult Mandibular First Permanent Molar Loss

Objective: A cephalometric study of 26 adults with mandibular first molars loss treated by the Otiental Pre-adjusted Appliance KOSAKA technology was undertaken to assess the results of treament. To analyze the facial vertical changes of patients in the treatment with mandibular first molars loss, and to explore the effects of the mandibular first molars loss on facial vertical change.Methods :26 adult cases with mandibular first molars loss which were substituted by mandibular second molars were included. The pretreatment and posttreatment cephalograms were digitized, and analysed by SPSS statistical software to analyze the facial vertical changes .26 adult patients with mandibular first molars loss(male 9, female 17)were included in this study. The average age was 22.1±6.2 years old,with age range from 19 years old to 44 years old. All patients were treated by the Otiental Pre-adjusted Appliance KOSAKA technology . The average treatment time was 1.9±0.6 years .Results: Occluding relation improved obviously; Upper and lower incisor recovered normal inclination and normal overbite and overjet were established.1.The pretreatment and posttreatment facial vertical changes of patients in the treatment with mandibular first molars loss:OP-MP was significantly decreased(P<0.001). N—Me, N—Me / S—Go were very significantly increased(P<0.001). L6—MP, G—Mes were also significantly increased(P<0.005). U6—PP was not changed.2.The change of facial height proportion: The proportion of prefacial height and postfacial height and the proportion of soft tissue facial height were significantly increased(P<0.05).3. The mandibular second molar's mesial movement was obvious, but mandibular plane angle was bigger.4.It was difficult to controll the extension of the mandibular molars.5.The mandibular plane angle was not changed in the pretreatment and posttreatment.6.The comparison result was not discrepancy between the male and the female in the pretreatment and posttreatment.Conclusion: 1.The vertical changes of the mesial movement mandibular second molar: Mesial movement molar led to incisor deep overbite.It benefited to open bite patients but harmed to deep overbite patients.2. The facial vertical changes of the mesial movement mandibular second molar:The occlusal plane and mandibular plane angle was bigger during adult patients' mesial movement mandibular molars.3.The molar's wedge-shaped space effectand the incisor's clock pendulum effect led to deep overbite.It was the fundamental reason of teeth and facial vertical changes.Other factors,for example patients'facial shape,anchorage kinds, mandibular third molar had little effect.