Clinical Application Of Alternate Rapid Maxillary Expansions And Constrictions In Angle Class Ⅲ Malocclusion

Objective: To study the clinical application of alternate rapid maxillary expansions and constrictions(Alt-RAMEC)in Angle Class Ⅲ malocclusion.Materials and methods: Two patients with maxillary deficiencies were selected as cases for the study.The first patient was an 8 years old boy with mixed dentition.The results of cast and X-ray analyses showed that the relationship of his first molars was Angle class Ⅲ,and there were reverse deep overbite and overjet of the anterior and posterior teeth in the left side,the tooth axis of the upper anterior teeth was proclined,while the tooth axis of the lower anterior teeth was retroclined,mild crowding existed in both upper and lower dental arches,his profile was concave with maxillary deficiency and his tonsil and adenoid were hypertrophied.According to the clinical examination and diagnosis,in order to promote the development of maxilla,correct his reverse deep overbite and overjet,improve occlusal function and facial profile,a modified maxillary expansion appliance with bite splints and hyperbolic reed was applied to this patient with the rapid maxillary expansions and constrictions,along with a facemask.This process lasted for 9 weeks,and then the bite splint was removed gradually,finally we told the patient to maintain the new occlusal relation by continuing to wear the appliance for more than 3 months.The second patient was a 4 years old girl with primary dentition.Results of cast and X-ray analyses showed that the relationship of her second primary molar was Angle Ⅲ classification,there were reverse overbite and overjet of the anterior teeth,moderate space existed in both the upper and lower dental arches,her lower midline was 2-3 mm shifted to the right and the upper midline was 1-2mm shifted to the right side,her profile was concave with maxillary deficiency and she has tonsil and adenoid hypertrophy.According to the clinical examination and diagnosis,in order to promote the development of the maxilla,correct her reverse deep overbite and overjet,improve occlusal function and profile,a modified maxillary expansion appliance with bite splints was applied to this patient with the rapid maxillaryexpansions and constrictions,along with a facemask.This process lasted for 9 weeks,and then the bite splint was removed gradually,finally we told the patient to maintain the new occlusal relationship by continuing to wear the appliance for more than 3months.X-ray films and orofacial images before and after treatment were taken for both patients.Results: In the first case,the development of the maxilla was promoted effectively and obviously,and reverse deep overbite and overjet were corrected.By comparing cephalometric measurements of before and after treatment,SNA increased from 78°to79°,ANB increased from-2°to 0.5°,A-X increased from 44 mm to 46 mm,ANS-X increased from 40 mm to 41 mm,A-Y increased from 55 mm to 57 mm,and ANS-Y increased from 61 mm to 62 mm.In the second case,the development of the maxilla was promoted effectively and obviously,reverse deep overbite and overjet were corrected and the patient’s profile was changed to some degree.By comparing cephalometric measurements before and after treatment,SNA increased from 81°to 84°,ANB increased from-1.5°to 2°,A-X increased from 33.5mm to 38 mm,ANS-X increased from 32 mm to 33 mm,A-Y increased from 59 mm to 60 mm,ANS-Y increased from62 mm to 64.5mm.Conclusions: Both patients suffered from maxillary deficiency.According to their conditions,the rapid maxillary expansions and constrictions method was chosen.The development of their maxillas were promoted forward effectively and obviously,reverse deep overbite and overjet were corrected and the patient’s profile was changed to some degree.The advantages of rapid maxillary expansions and constrictions is that it can loosen and activiate circumaxillary sutures to a bigger degree,promoting the forward development of the maxilla effectively and obviously.At the same time,it won’t produce too much teeth compensatory effect or make the upper dental arch expand excessively,which may cause deeper overjet of posterior teeth and make the case more complex and difficult.Its disadvantage were the uncomfortable feeling and poor adaptability when patients first wear it,complex to adjust the appliance in their mouth by themselves and not easy to clean the appliance and keep their oral hygiene.Clinically,as long as we choose a suitable indication and an appliance,and the patient cancooperate with us well,a better development of maxillary and profile will be reached with rapid maxillary expansions and constrictions.