Design,Manufacture And Clinical Application Of Mini-twinblock Functional Appliance In The Treatmen Of Class â…¡ Division 1 Malocclusion

Objective To investigate the functional orthopedic charactors of Mini-twinblock functional appliance in the treatment of ClassⅡdivision 1 malocclusion and changes in the craniofacial soft and hard tissues profiles(maxilla,mandible,alveolar bone,tooth,pogonion of soft,lip etc.).Methods Twenty-three ClassⅡdivision 1 patients with a normal or mild maxillary excess , deficiencies of mandibular development and function,the overjet 5mm or over 5mm , aged 6-13 years were included into this study. They were not orthodontic treated before .There were 10 boys and 13 girls. The time of treatment course between 12.1 and 13 months ,on an average of 12.5 months.Questionnaire,routine clinical evaluation, function analysis, lateral cephalograph,panoramic,left hand and wrist radiographs,photographs of face and dental occlusion were taken for each patient before treatment.Study model and working model were performed,remodel and registered bite(end to end mandibular anterior teeth relationship by the mandibular mesial shift one times or several times,central and mild mesial first molar relationship of both sides and coordinate of midline between maxilla and mandible).Mini-twinblock functional appliance were designed,made and applied in clinic . Lateral cephalograph was taken after treatment. Soft and hard tissues measurements of cephalometrics before and after treatment were done. The Student T test was applied to the data.Results The data were obtained from soft and hard tissues measurements of cephalometrics before and after treatment of mini-twinblock functional appliance .They showed that SNB,U1-L1,NLA,Co-Gn,Co-Go,U1-PP and L6-MP were increased by 2.47°,13.56°,4.59°,2.35mm,2.57mm,1.35mm and 2.89mm,respectively;ANB,U1-SN,H angle,UL-E,LL-E were reduced by 3.19°,4.98°,2.76°,1.29mm and 1.91mm,respectively;They were significant different. SNA,IMPA,FMA,L1-MP and U6-PP were changed by 0.9°,1.17°,0.23°,1.21mm and 0.37mm,respectively;They were not significant different.Conclusions 1.The Mini-twinblock functional appliance has the following characters1.1 The functional appliance is fixed style in the first two weeks ,and removable style after two weeks.The character can guarantee cooperation of patient at the beginning ,provide the favourable condition for successful treatment ,avoid occurrence of decayed tooth and any serious harm to tooth.1.2 There is a transpalatal arches on the hard palate and a lingual arches on the mandible .The stainless steel wire takes the place of some plastics .The functional appliance is small and exquisite ,easy to clean and accepted by patient .It can control the posterior extrusion.It is fit for patients, who own a big mandibular plane angle .The functional appliance's transpalatal arches should be improved for patients ,who own a narrow maxillary arch .Jackscrew should be designed on hard palate to enlarge maxillary arch,coordinate maxillary and mandibular arch for shift the mandible forward smoothly.1.3 Lip bow is designed on the lower incisor .It can avoid the lower incisors tipping labially and make the functional appliance more stable.2. The functional orthopedic application of Mini-twinblock functional appliance was effective on improvement of facial balance in ClassⅡdivision 1 patients with deficiencies of mandibular development and function in the mixed or early permanent dentition stage .The functional appliance can promote mandibular development ,increase mandibular length and height significantly inhibit maxillary growth ,induce the lower first molar extrusion,achieve the class I occlusal relationship ,reduce a little of inclination of the upper incisor ,and limit inclination and length of the lower incisor.Pogonion of soft tissue deficiency,upper lip excess and lower lip roll are improved.