Application Of Spee’s Wire In The Case Of Molar Distalization

Objective: To investigate the clinical application of Spee’s wire in the case of molar distalization.Method: An adolescent male patient with skeletal class II malocclusion was selected from the department of the First Affiliated Hospital of Dalian Medical University in February 2014.The patient was 13 years old with permanent teeth dentition including class II molar relationship and deep anterior overbite and overjet.Curve of Spee was deep,while compensating curve was flat without dental crowding.The arch form was tapered accompanied by rhinitis and the mouth breathing.From the frontal view,the midface region was symmetrical,while teeth exposure was distinct.Lip and chin musle were tense when mouth was closed.From the lateral view,the facial type is maxillary protrusion even when the mandibular was forwarded.Two-phase treatment was suggested after systematic analysis of the patient’s situation.Phase I treatment: growth pattern modification with facebow inhibiting the maxillary growth and accelerating the mandible development efficiently.The goal of near neutral molar relationship would be reached by pendulum appliance distalizing molar.For phase II treatment,sliding method was used to retract anterior teeth.In order to save anchorage,the concept of physiologic anchorage control had been used to maintain the upper dentition compensating curve with consideration of muscle training.The changes between pre-treatment and post-treatment were analyzed and discussed.Result: The patient’s situation was significantly improved after 18 month’s treatment.After phage I treatment,the distance of U1-NA increased from 2mm to 4mm,the degree increased from 27.5° to 33.5°.The side effects that anterior teeth lip tipping of pendulum appliance could be hypothesized.Our goal for near neutral molar relationship had been reached.After phage II treament,the facial type had been obviously changed from protrusion to straight accompanied with ANB’s degree decreased from 6° to4.5°.The distance of Po-NB increased from 0mm to 1.5mm and the degree of Z-angle increased from 58° to 70°.Molar relationship was neutral.Both overbite and overjet were significantly improved.The mandibular curve of Spee was leveled from 4.5mm to2 mm.On the other side,the compensating curve was established.The width of maxilla from canine to first molar was increased 2mm,5mm,2mm,4mm,respectively.Based on the “best-fit superimposition” and “Pitchfork analysis”,we concluded that the molar was distal tipping movement during the phage I treatment,and the mesial bodily movement was obtained during the phage II treatment.After the treatment,the molar maintained distal inclination state which reduced the loss of physiological anchorage and the mandible development was accelerated efficiently.The occlusion was stable after six months reviewed.Conclusion:(1)Spee’s wire can both maintain molar distal inclination and reduce the loss of physiological anchorage.(2)Spee’s wire application after molar distalization can maintain the upper dentition compensating curve and establish a stable occlusion.The mandible development can be accelerated efficiently by breaking the original oral neuromuscular skeletal abnormal balance.