Board Français d'Orthodontie

SummaryA. Pretreatment documents1/2006 (age of patient: 12 y 8 m).DiagnosisFacial examination:-convex profile with retrusive upper lip;-open nasolabial angle;-short, everted lower lip;-protruding chin;-balanced smile.Functional examinationA complete examination was done. The painful signs observed at the two TMJs originated from a position high up and behind the mandibular condyles in the glenoid cavities, thus producing compression in the bilaminar regions.Endooral examination and analysis of castsAll the permanent teeth were present.We noted a bilateral canine and molar relationship with incisor deep bite.The midlines were 2 mm off-center with the maxillary midline to the right and the mandibular midline to the left of center.There was no crowding in the upper arch. The lower arch displayed diastemas between 32, 41 and 42 and mild crowding between 32 and 33.We observed a partial scissor-bite resulting from the coronobuccal tipping of 14 and 24, which were distally rotated, and from the coronolingual tipping of 34 and 44.Overbite was 6.2 mm and overjet 8.4 mm.The distal angle of 11 was chipped.PanorexAll the wisdom teeth were present.Cephalometric analysisCephalomtery enabled us to calculate:-a skeletal Class II with a retruded maxilla and even more pronounced mandibular retrognathism (ANB = 7.6°; SNA = 78.4° and SNB = 70.8°) as confirmed by the Ao-Bo value (6 mm);-skeletal normal bite (FMA = 26.5°);-coronopalatal tipping of the upper incisors (UI/NA = 15.4°), expression of compensation of the skeletal pattern with correct positions of the lower incisors (IMPA = 89°);-a very open interincisor angle (I/I = 140.2°) with a 6.2 mm overbite and 8.4 mm overjet.TreatmentThe severity of the malocclusion and the treatment planned in conjunction with the parents would depend on the patient's foreseeable growth and on the evolution of his facial esthetics.First phase: January 2006In order to relieve the TMJs and treat the partial and bilateral scissor-bite, a maxillary plate with an inclined retroincisal plane was fitted to the banded maxillary first molars. Subsequently and gradually, the thickness of the inclined plane was raised to allow the mandible to recover its vertical contacts and move slightly forward. The non-occlusion achieved on placing this apparatus enabled spontaneous correction of the tipping of the first premolars and of the partial, bilateral scissor-bite occlusion.One month later, the pain had disappeared in both TMJs.Second phase: June 2006The inclined retroincisal plane was kept in place for a further 6 months.When all the joint symptoms had disappeared and the situation had been consolidated by lateral and posterior dental contacts, a second complete examination was performed. This pointed to two possible protocols, either orthodontic treatment alone, or orthodontic-surgical treatment, the decision being dependent upon future growth.As the parents refused the idea of surgery, we opted to undertake bimaxillary orthodontic treatment.The treatment stages in order were: alignment, levelling, intrusion of upper and lower incisors, Class II elastics and finishing.B. Posttreatment documents6/2008 (age of patient: 15 y 1 m).RetentionFace analysis: concave profile but with indisputable esthetic improvement; the nose and chin had grown a lot but the smile was pleasant.Functional examinationJoint examination (absence of pain and noises, etc.), muscle examination (symmetrical and synchronous during effort, absence of spasm) and the magnitude of the mandibular movements demonstrated the quality of the functional balance.Endooral examination and analysis of castsStable and functional dental occlusion was obtained with a bilateral canine and molar Class I.Alignment of the two midlines with the axis of the face.Correction of the deep bite with normal overjet and overbite.PanorexCorrect root positions, extraction of the third molars was advised.Cephalometric analysis-Improved sagittal relationships with reduction of the Class II (the ANB angle reduced from 7.6° to 4.1° and the Ao-Bo from 6 mm to 5.3 mm) due to the closing of the SNA angle from 78.4° to 76.6° and the opening of the SNB angle from 70.8° to 72.5°.-Regarding the vertical dimension, the skeletal pattern as measured by the FMA had reduced from 26.5° to 24° but remained normodivergent.-Dentoalveolar compensations:-the angle formed by the upper incisors with the NB line increased considerably from 15.4° to 25.2° while the IMPA also increased from 89° to 91.8°;-the overjet and overbite decreased, respectively, from 8.4 mm to 4.6 mm and from 6.2 mm to 4.1 mm;-the intercisal angle closed from 140.2° to 131°, thus contributing to enhanced correction of the incisor overbite;-the occlusal plane underwent clockwise rotation.Analysis of the superimpositions-General superimposition: we observed considerable horizontal mandibular growth with very significant development of all levels of the face, notably ample development of the nose and cutaneous chin, anticlockwise rotation of the occlusal plane due to growth of maxilla and mandible in the same direction.-Maxillary superimposition: the sagittal dentoalveolar adjustments went as planned; despite the use of Class II mechanics, the maxillary incisor torque increased; there was noticeable retrusion of point A.-Mandibular superimposition: some mandibular growth was expressed contributing to the correction of the skeletal and dental Class II as well as to the coronovestibular repositioning of the mandibular incisors.-In the vertical dimension, we observed good control over the occlusal plane and remodelling of the curve of Spee.C. Postretention records9/2009 (age of patient: 16 y 4 m).D. Clinical observations-The first orthopedic stage aimed to decompress the craniomandibular joints and reposition the mandibular condyles. This was done using an anterior bite plane.-The second phase was conducted using a bimaxillary appliance in order to obtain the necessary interdigitation to maintain the previously achieved mandibular position. To preserve this mandibular reference position, the anterior bite plane was left in place for 6 months during wearing of the fixed bimaxillary appliance.-The length of treatment was due to the major mechanics required and to the uncertainty concerning the mandibular growth response. Thanks to exceptional compliance on the part of the patient, the achieved occlusion was highly satisfactory and stable.-The anterior bite plane was used to slightly advance the mandible. Class II intermaxillary elastics were also used at the end of treatment to maintain control over the anterior teeth.