Treatment Of Crowding Malocclusion With Maxillary Impacted Canine In Adolescent

Objective: The purpose of this study was to investigate the clinical treatment effect of extraction on a crowding malocclusion adolescent patient with maxillary impacted canine.Method: An adolescent patient treated at Dalian Drs Dental Clinic in February 2014 was recruited into the study.The patient was a eleven years and six months old female with Angle,s Class ?,Skeletal Class ?,high angle and in growing stage.The extraoral examination showed his face was symmetrical and underpart 1/3 of the face was normal.Meanwhile,the profile was straight,upper and lower lip thickness was increased.The bilateral molar occlusal was both class I relationship.The maxillary canine was impacted on the both sides.3.5mm space between 12 and 14.The lower incisors were proclined lead to blade teeth.33,22 crossbite.Both upper and lower arch was severe dentition crowding.The curve of Spee was 2 mm on both sides.Midline shift was 1 mm towards left on lower arch when comparing with facial midline.Treatment plan was drawn according to clinical examination and analysis results: we decide to remove four first premolars followed by placement of Straight Wire Appliances.In the bilateral maxillary canine before eruption maintain the space between the lateral incisor and first premolar.TPA was used to avoid extrusion of molars.Maximum anchorage was used to align and level the dentition.Extraction space was closed by sliding mechanics.Wire bending for finishing adjustment when the space had been closed and Hawley retainers for upper and lower.According to the pre and post treatment cephalometric radiograph was done to judge the changes of soft and hard tissue before and after treatments.Result: The active treatment lasted for 19 months.Extraction could provide space to traction impacted canine to normal dentition and relief of crowding.Dentition was well aligned and extraction spaces were closed.Canine relationship and molar relationship was both Class ?.A good antero-posterior relationship was achieved with normal overbite and overjet.Midline shift 1 mm to left on lower arch.(1)SNA,SNB,ANB angle appraisal changed slightly after treatment,which indicated the skeletal pattern remained Class ?.FMA decreased by 0.2°,indicating the mandible rotate anticlockwise.ANS-Ptm increased by 3mm,Co-Po increased by 2mm,Wit's appraisal increased by 1mm,indicating the length of jaw both increased in treatment and in harmony with each other.(2)The extraction treatment to provide sufficient space for 13 and 23 moving into the normal dentition.They maintain natural endodontium,good periodontal condition and beautiful shape gums.The U1-SN angle and U1-NA angle were increased.The U1-NA distance,L1-NB distance and L1-NB angle were decreased,improving labial inclination of the lower incisors.(3)ULEP decreased by 0.5mm and LLEP decreased by 1.5mm respectively.Z angle increased from 63°to 65°.Overall chin and lip relationship improved,enhancing aesthetics.Conclusion: For the malocclusion with severe dental crowding could relieve denture crowding,prove denture arch protrusion and coordinate the teeth quantity with the bone quantity by extraction the four first premolars.For high angle cases,TPA can be used as maximum anchorage in the orthodontic treatment.Especially to reinforce the vertical anchorage and prevent the mandible rotate clockwise.When orthodontic expansion or extraction can achieve enough space for impacted canine and the canine can erupt spontaneously,helping eruption is preferred.When orthodontic treatment alone cannot remove the obstacle in the path of the canine eruption,using orthodontic approach combined surgical would acquire satisfied treatment result.