The Application Of Micro-implant Anchorage In An Adult Patient With Bimaxillary Protrusion

Objective: The aim was to search the clinical effect of micro-implant anchorage in orthodontic treatment of adult patients with bimaxillary protrusion.Method: An adult patient treated at Dalian Drs Dental Clinic in 2014 was recruited into this case.The patient’s oral examination showed: poor sanitary conditions,a small amount of calculus have lower anterior teeth lingual neck of the incisors at the gingival recession.There is no impaction.Upper incisors flared serious and upper arch protrusion,she was convex facial profile.The muscle around lip and chin are tense and the total crowding in upper arch was 10 mm and lower arch was 8.5mm.The overjet was6 mm and overbite was normal.Curve of Spee was normal too;the midline is normal.Treatment plan was drawn according to analysis result: extract all of first bicuspids,use the straight wire technology with upper and lower arch and cooperate with micro-implant to retrude and depress forward and molar teeth.Upper arch protrusion was reduced and vertical height was controlled.Class II elastic and triangular traction was used to adjust molar relationship.Vacuum-formed retainer was made both for upper and lower teeth.After the case,we will analyse the comparison between original and final figure.Results: Total procedure was 25 months followed by retention with vacuum-formed retainer.Upper and lower arch were oval.Overjet and overbite are normal.Harmonious facial profile.The occlusion was stable.Teeth tip and torque harmonize.Dental midline was the same with facial midline.The right side of the molar and canine teeth maintain neutral relationship,on the left side of the molar and canine teeth change relationship to neutral.TMJ were all suitable.Comparisn of pre and post treatment cephalometric tracing indicated following changes:(1)SNA unchanged,SNB decreased by 0.5 degrees,ANB increased by 0.5 degrees,and wits changed from 2mmto 1mm,maintaining the relationship of bone.(2)FMA maintained at 30 degrees,the vertical to be maintained.(3)Overjet change from the original 8 mm down to 2 mm,U1-NA °decreased 12°,U1-NA° decreased 7 mm,NA/PA change from 12°to 10°,indicating protrusion upper arch and flared incisors got obvious improvement.(4)IMPA consists of 103 degrees is now reduced to 84 degrees,a total reduction of 20 degrees,indicating the lower incisor adduction and upright.(5)Z Angle from 57°increases to71°.ULEP reduced from 4 mm to 0 mm,LLEP reduced from 8 mm to 0 mm,lower lip exhibited obvious retrusion,mentolabial sulcus depth increases from 1 mm to 3 mm,chin and lower lip were harmonious,profile got obvious improvement.Dentition was well aligned and no obvious root resorption.Conclusion: For adult patients with a high angle skeletal class I malocclusion,extracting four first premolar,with strong anchorage as micro-implant,can maximize the retruded anterior teeth,reduce the patient’s deep overjet,improve the side profile.The development of adult dental arch has been stable.The improvement of dental arch volume needs to rely on tooth reduction.The implant anchorage is effective in reducing the loss of anchorage,and bring more and more satisfactory results.