Soft And Hard-tissue Profile Changes And Correlation Analysis In Class Ⅱ Malocclusion Mandibular Retrusion’s Patients Under Therapy With Twin-block Appliance

Objective:By measuring and analyzing the twin-block appliance cephalometric X-ray of hard and soft tissue changes between pre-and post-treatment, I discuss the soft tissue profiles effects of class Ⅱ division1mandibular retrusion patients treated with twin-block appliance.Methods:Patients selected for this study were admitted by and graded according to the inclusion criteria used by the Department of Orthodontics, Xiangya Hospital of Central South University. Twenty class Ⅱ division1mandibular retrusion patients, including13males and7females, were aged from7-year old to12-year old who were at the peak or pre-peak of personal growth and development. Twelve indicators of hard tissue profile and23indicators of soft tissue profile were gathered and analyzed from the pre-and post-treatment cephalometric measurements by applying the Twin-block functional appliance to these20patients. The database was established using Excel2003, and the SPSS18.0software was used for statistical analysis. Results:The comparative analysis of hard and soft tissue changes between pre-and post-treatment by using Twin-block appliance on these patients:1:The ANS-Me, S-Go and FMA increased, in which, ANS-Me and S-Go were statistically significant (P<0.05);2:The SNA, SNB, U1-NA and IMPA increased, ANB and FMIA decreased, in which, ANB, FMIA, SNB, U1-NA and IMPA were statistically significant (P<0.05);3:The A’Ls-FH, Sn-A, Ls-E and Sn-Stms increased, NsLs-FH decreased, in which, NsLs-FH and A’Ls-FH were statistically significant (P<0.05);4:The B’Li-FH, Stmi-Me’and B’-B increased, NsLi-FH and Li-E decreased, in which, NsLi-FH, B’Li-FH, Li-E and B’Li-FH were statistically significant (P<0.05);5:The NsPg’-FH, Pg’B’-FH and LiB’Pg’increased, in which, NsPg’-FH and LiB’Pg’were statistically significant (P<0.05);6:The Li-E increased which was statistically significant (P<0.001); Ls-E increased, but the result was statistically insignificant (P>0.05).Conclusion:The Twin-block function enables class Ⅱ division1mandibular retrusion patients receive the following changes after Twin-block appliance treatment:1) In hard tissues, the mandible length increased and the inclination of upper and lower incisors increased as well, the lower1/3of facial patterns can be effectively improved;2) The Lower lip protrusion was reduced, the length of the upper and lower lip both increased, the soft tissue chin moved forward, the facial surface protrusion was reduced, and the relationship between nose, lips, and chin improved significantly, especially for the sagittal and perpendicular improvement of mandibular;3) In hard tissues, the correlation between the jaw position, the inclination of the upper and lower incisors and its corresponding soft tissues was significant.