The Analysis Of The Transmission Straight Wire Technique And The Tip-Edge Technique During The Tooth Movement In Extraction Treatment

Objective:The objectives of this work were to compare the tooth movement characteristics of transmission straight wire appliance and the Tip-Edge appliance during the maxillary extraction orthodontics; explore the principles of tooth movement; make the treatment more rational and effective; improve the efficiency of clinical orthodontists; and provide the insights for clinical practice.Methods:From2010to2013,40patients (20males and20females) with Angle class II malocclusion were selected among the orthodontics outpatients from the dental Hospital of Tianjin Medical University and Tianjin Tanggu dental Hospital. These patients aged from15to20years with the average age of17.5±2.6years old. They were equally divided into two different groups according to the treatment methods, with20persons (20cases) treated via transmission straight wire appliance as the experimental group and the rest (20cases) treated via Tip-Edge appliance as a control group. The two maxillary first premolar of each patient were extracted. The results of the treatment were satisfactory without the extraoral force and palatal arch. The pretreatment and posttreatment X-ray cephalometric radiographs of each patient were taken. Cephalometric analysis were performed for28measurements.10model variables were measured too before and after treatment. The statistical analysis was performed with SPSS16.0for Windows. The arithmetic mean and standard deviation were calculated for each variable. Paired t-test and the independent sample t-test were performed to determine the treatment effects within the group and between the groups, respectively. The level of significance was P<0.05.Results:The results of the treatment via transmission straight wire appliance and the Tip-Edge appliance were determined through cephalometric X. Bone indicators,∠SNA,∠SNB,∠ANB,∠MP-FH, were not significantly changed between the two groups for the pretreatment and posttreatment; and the difference was not statistically significant (P>0.05). Dental indicators,∠UI-SN,∠UI-PP,∠L1-MP,∠U1-L1, UIA_PTV, UIE_PTV, LIE-PTV, LIA-PTV, UM-PTV, LM-PTV, were significantly changed before and after treatment within the group; and the difference was statistically significant (P<0.05). However, dental indicators were not significantly changed between the two groups; their difference was not statistically significant (P>0.05). Soft tissue targets, UL-EP, LL-EP, Z angle, were significantly changed within the group before and after treatment; the difference was statistically significant (P <0.05). However, no significant changes of soft tissue targets existed between the two groups after the treatment; the difference was not statistically significant (P>0.05). After the treatment, both methods increased the upper canine width, decreased the first molar pitch, and increased the first pitch canine. These differences were statistically significant (P<0.05).Conclusion:1. The patients with Angle class Ⅱ malocclusion were treated via transmission straight wire appliance and the Tip-Edge appliance combined with single maxillary extraction. Such treatments adducted upper incisors; improved canine neutral relationship and distal molar relationship; reduced maxillary second premolar and first molar space; increased lower incisor inclination; and increased the lower canine width.2. Soft tissue profile improved significantly when applying transmission straight wire appliance and Tip-Edge appliance technology combined with single maxillary extraction to treat Angle Ⅱ malocclusion. This treatment was effective.3. The transmission straight wire appliance combined with single maxillary extraction is superior to the Tip-Edge appliance in controlling the upper incisor torque for the treatment of Angle class Ⅱ malocclusion.