To observe the changes of sagittal, vertical and dental measurement data of skeletal classⅡ Angle classⅡ Division 1 adolescent malocclusion patients before and after the treatment of mandibular advancement with invisible functional appliance.

Twenty six skeletal class Ⅱ Angle classⅡ Division 1 patients [14 males, 12 females, average age (11.4 ± 2.3) years] with mandibular retrusion as the main cause were selected from the Department of Orthodontics of the Third Affiliated Hospital of Sun Yat-sen University and treated with A6 appliance launched by Angelalign company. The lateral cephalograms before and after treatment were retrospectively studied, and the measurement results were statistically analyzed to compare the differences of jaw and teeth before and after the functional orthopedic treatments.

After the treatment with invisible functional appliance, point A moved backward, SNA decreased from (83.5 ± 3.1) ° to (82.7 ± 2.6) °, with a statistically significant difference (t = 2.7, P = 0.013) ; Point B moved forward, SNB increased from (77.7 ± 3.3) ° to (78.4 ± 3.1) °, the difference was statistically significant (t = -2.4, P = 0.027) ; ANB decreased from (5.8 ± 1.9) ° to (4.2 ± 2.1) °, the difference was statistically significant (t = 7.5, P<0.001) ; U1-SN decreased from (111.1 ± 6.9) ° to (104.7 ± 7.2) °, the difference was statistically significant (t = 9.6, P<0.001) , indicating that the upper anterior teeth were aducted; L1-MP increased from (99.7 ± 5.5) ° to (102.3 ± 6.7) °, the difference was statistically significant (t = -3.3, P = 0.003) , indicating that the labial inclination of lower anterior teeth. In the vertical change, U6-PP and L6-MP increased from (19.6 ± 1.9) mm and (27.6 ± 3.0) mm to (20.3 ± 2.4) mm and (28.8 ± 3.4) mm respectively, and the difference was statistically significant (t_U6-PP = -3.1, P_U6-PP = 0.004, t_L6-MP = -5.3, P_L6-MP<0.001) , which indicated that the alveolar height of upper and lower posterior teeth were extended; the ratio of ANS-Me/N-Me between the lower 1/3 of the face and the total height increased from (52.6 ± 1.4) % to (53.5 ± 1.5) %, with a statistically significant difference (t = -5.5, P<0.001) ; the mandibular plane angle GoGn-SN increased from (31.1 ± 5.8) ° to (32.1 ± 6.0) ° after treatment, with a statistically significant difference (t = -2.1, P = 0.046) .

The use of invisible functional appliance for mandible forward in skeletal classⅡ Angle classⅡ Division 1 patients at the peak of growth and development can promote the sagittal reconstruction of jaws, improve face type, and coordinate lower 1/3 height of the face.