in patients with mandibular retrognathism , it is difficult to establish a satisfactory esthetic profile,12 improve the respiratory function,34 and achieve stable treatment outcomes25 with orthodontic treatment alone .
surgical mandibular advancement with bilateral sagittal split osteotomy ( bsso ) or distraction osteogenesis ( do ) is generally required for effective treatment,6 and both osteotomy techniques have exhibited equal effectiveness and good outcomes.7 however , progressive condylar resorption ( pcr ) sometimes occurs as a serious complication of surgical mandibular advancement.8 although the precise underlying mechanism remains unclear , overloading of the condyle during or after surgery is considered one of the main etiologies for pcr.910 moreover , kobayashi et al.11 reported that clicking in the temporomandibular joint ( tmj ) and malformation of the condyles can be risk factors for pcr . here
we report a case involving a young female patient with severe mandibular retrognathism and bilateral condylar deformities caused by severe mandibular hypogrowth after the first phase of orthodontic treatment .
bilateral pcr was suspected , and surgical mandibular advancement was associated with a high risk of further condylar resorption .
accordingly , we performed le fort i osteotomy with two genioplasty procedures , avoiding surgical mandibular advancement to prevent excessive loading of the condyles .
good esthetic and functional outcomes were achieved , with maintenance of a satisfactory facial profile at 30 months after treatment completion .
a girl aged 9 years and 9 months was referred to the outpatient clinic of our university hospital from the plastic surgery unit at another hospital .
she had been diagnosed with left - sided unilateral cleft lip and palate ( uclp ) and had undergone cheiloplasty at 4 months of age . compared with the average height of japanese girls of the same age ( 133.5  6.2 cm )
her medical history revealed epileptic seizures at 9 years of age and a congenital ventricular septal defect .
an increased lower facial height , facial asymmetry , and circumoral muscle strain on lip closure were observed .
she was in the mixed dentition stage and exhibited an anterior crossbite , with an overjet of 1.5 mm and an angle class iii molar relationship on both sides ( figure 2 ) .
surgical scars were present on the distal side of the maxillary left central incisor , which was mesially rotated by 90. the maxillary and mandibular arches were narrow , with moderate crowding in the mandibular incisor region .
clinical examination and a panoramic radiograph revealed the congenital absence of the maxillary left lateral incisor and all second premolars ( figure 3 ) .
an alveolar bone defect was observed between the maxillary left lateral incisor and the deciduous canine .
lateral and posteroanterior cephalograms showed digitate impressions on the surface of the skull and a deviated nasal septum .
cephalometric analysis ( table 1 ) showed a skeletal class ii relationship ( a point - nasion - b point angle , anb ; 9.0 ) with mandibular retrusion ( sellanasion - b point angle , snb ; 67.0 ) .
in addition , the mandibular body was short compared with the japanese norms.12 the mandibular plane ( mp ) angle was steep and the ramus plane ( rp ) was rotated clockwise ( mp  frankfort [ fh ] plane , 39.0 ; rp  fh , 90.5 ) .
the maxillary and mandibular incisors were lingually inclined and extruded ( upper incisor axis to fh , u1fh , 99.0 ; angle between axial inclination of mandibular central incisor and mp , l1mp , 85.5 ; perpendicular distance of u1 to nasal floor , u1/nf , 32.5 mm ; perpendicular distance of l1 to mp , l1/mp , 44.5 mm ) .
on the basis of her small stature and medical history of seizures , a ventricular septal defect , and uclp , we suspected a syndrome .
however , a plastic surgeon ruled out any syndrome . therefore , we diagnosed the patient with angle class iii malocclusion , a skeletal class ii jaw relationship , an anterior crossbite , moderate mandibular incisor crowding , and left - sided uclp .
the treatment objectives were as follows : correction of the anterior crossbite , expansion of the maxillary alveolar cleft before bone grafting , and achievement of dental alignment and leveling for adequate intercuspation .
orthognathic surgery was planned as the second phase of treatment if the maxilla and/or mandible failed to show ideal growth after permanent tooth eruption and growth completion .
first , the narrow maxillary arch was expanded using a quadhelix device before bone grafting at 10 years of age .
alveolar bone grafting was performed at 10 years and 3 months of age to close the left - sided uclp and ensure continuity of the alveolar bone .
after successful bone grafting , the maxillary crossbite and maxillary incisor angulation were corrected using a lingual arch at 11 years and 3 months of age .
patients with clp usually exhibit skeletal class iii malocclusion with maxillary deficiency because of the cleft itself and fibrous scar tissue formation caused by reconstructive surgery .
however , in our patient , at the completion of maxillary and mandibular growth , we recognized downward and backward rotation of the mandible caused by the lack of forward growth and excessive vertical growth of the maxilla from the cephalometric superimposition ( figure 4 ) .
furthermore , the mandibular notch had become significantly deeper relative to the initial position ( figure 4c ) . as a result ,
the facial profile appeared significantly retrognathic compared with the initial profile ( figure 5 ) .
moreover , an excessive overjet and an anterior open bite were observed ( figure 6 ) .
the snb angle had decreased by 6.5 and the anb and mp - fh angles had increased by 5.5 and 10.0 , respectively ( table 1 ) .
in addition , bilateral finger - shaped condyles with anterior bone surface resorption were observed ( figures 7 and 8) .
we reassessed the patient at the beginning of the second phase of treatment and diagnosed suspected bilateral pcr on the basis of the growth pattern and imaging findings .
the treatment objectives in the second phase were as follows : correction of the retrognathic facial profile from esthetic and functional perspectives , correction of the anterior open bite and excessive overjet , and achievement of an acceptable occlusion .
to achieve the abovementioned treatment objectives , surgical orthodontic treatment with double - jaw surgery ( le fort i intrusion osteotomy and mandibular ramus osteotomy ) was considered necessary to advance the mandible .
bsso and do are the most common procedures for surgical mandibular advancement and generally result in good treatment outcomes . however , we suspected bilateral pcr in our patient and preferred to avoid mandibular advancement osteotomy to prevent any further condylar resorption . therefore , we planned le fort i osteotomy with genioplasty to avoid ingravescence of pcr and achieve counterclockwise rotation of the mandible .
we planned two genioplasty procedures to achieve an esthetic facial profile through advancement and vertical reduction of the chin .
the maxilla must be positioned posteriorly in cases of maxillary impaction to achieve autorotation of the mandible . to eliminate the risk of forward repositioning of the maxilla by posterior interference
, we reluctantly decided to extract the impacted second molar to create enough space for setback osteotomy .
in the second phase of treatment , at 15 years and 6 months of age , preadjusted edgewise appliances with 0.018-inch slots were placed in the maxilla and mandible and leveling of both arches was initiated .
the patient also had to wear a high - pull headgear appliance at least 10 hours per day for intrusion of the maxillary molars and prevention of clockwise mandibular rotation caused by molar extrusion .
after 18 months of presurgical orthodontic treatment , we observed discontinuation of mandibular growth and active condylar erosion by superimposition of serial cephalometric tomograms obtained in the last 6 months . therefore , le fort i intrusion osteotomy was performed with advancement genioplasty and extraction of the maxillary second molar .
the maxilla was impacted by 7.0 mm in the incisor region and 5.0 mm in the first molar region , and the chin was advanced by 11.0 mm because of counterclockwise rotation of the mandible led by maxillary impaction and advancement genioplasty . during postsurgical orthodontic treatment , a second genioplasty procedure
was performed with 8.0-mm advancement and 6.0-mm vertical reduction of the chin , along with rhinocheiloplasty .
subsequently , a vacuum - formed retainer for the maxillary arch and a vacuum - formed retainer and a lingually bonded retainer for the mandibular arch were provided for retention .
the patient s post - treatment records showed significant resolution of both skeletal disharmony and malocclusion ( figures 9 , 10 , 11 ) .
cephalometric evaluation showed an increased snb angle ( 64.0 ) and a decreased mp - fh angle ( 34.0 ) , although the skeletal jaw relationship was still class ii ( anb , 11.0 ; table 1 ) .
the maxilla was impacted by 7.0 mm in the incisor region and 5.0 mm in the first molar region , while the pogonion was advanced by 18.0 mm through mandibular counter - clockwise rotation and the two advancement genioplasty procedures ( figure 12 ) .
morphological changes in the bilateral condyles were not observed on computed tomography ( figure 13 ) .
in addition , hyoid bone advancement and an increased pharyngeal airway volume were observed ( figure 14 ) . at the 30-month follow - up examination
, we observed a satisfactory facial profile and a slightly decreased overbite ( figure 15 ) .
there were minimal changes in the dentition and negligible clockwise rotation of the mandible ( figure 12 ) .
we described the effective treatment of severe mandibular retrognathism with suspected pcr using le fort osteotomy and two genioplasty procedures , thus eliminating the need for surgical mandibular advancement .
the treatment was mainly aimed toward achieving satisfactory esthetics and respiratory function and long - term stability . to achieve improved esthetics and
simultaneously avoid condylar overloading , le fort i osteotomy for superior repositioning of the maxilla and advancement genioplasty for counterclockwise rotation of the mandible and anterior projection of the chin were performed .
do and bsso are two commonly used procedures for the treatment of mandibular retrognathism from esthetic and functional perspectives.67 however , these procedures occasionally result in pcr , particularly in patients who undergo long - span mandibular advancement with continuous overloading in the tmj region.81113 although the precise etiology of pcr remains unclear , tmj stress or overloading is considered one of the main causes.91014 unfortunately , despite the presence of severe mandibular retrognathism , our patient developed finger - shaped condyles on both sides after the first phase of orthodontic treatment , probably because of bone surface absorption .
condylar malformation is also suggested as a risk factor for pcr.11 because our patient had suspected pcr and was at a high risk of further resorption with surgical mandibular advancement , we decided to perform le fort i osteotomy with two advancement genioplasty procedures and avoided mandibular surgery , which would improve the facial profile without stressing the tmj at the end of mandibular growth .
some studies have reported a relationship between le fort i osteotomy with superior repositioning and condylar resorption .
hoppenreijs et al.15 reported that the incidence of condylar resorption was 9% with le fort i intrusion osteotomy only , and this was lower than the incidence with bimaxillary osteotomies in patients with an anterior open bite .
they suggested that intermaxillary fixation ( imf ) with rigid internal fixation should be avoided to minimize condylar changes .
therefore , we used compression bandages around the head and neck as an alternative to imf after le fort i osteotomy .
consequently , no significant changes in the condylar morphology were observed at 24 months after surgery .
to assess the respiratory function , we evaluated the pharyngeal area by superimposition of pre - treatment and post - treatment cephalograms ( figure 14a ) and the airway volume using the dolphin 3d software ( dolphin imaging and management solutions , chatsworth , ca , usa ) for airway analysis ( figure 14b ) .
severe mandibular retrognathism is often accompanied by pharyngeal airway obstruction,3 probably because of downward displacement of the tongue .
therefore , advancement genioplasty can achieve extensive anterior retraction of the suprahyoid musculature and decrease the signs and symptoms of obstructive sleep apnea syndrome , including the apnea 
hypopnea index.1617 moreover , the posterior airway space significantly increases after advancement genioplasty.1819 our patient also snored during her sleep before treatment , and we believe that her treatment has minimized any future risks of obstructive sleep apnea .
with regard to long - term stability , the maxillary , chin , and jaw positions appeared stable at the 30-month follow - up examination in our patient .
le fort i osteotomy with superior repositioning of the maxilla and advancement genioplasty are considered more stable than other procedures.20 in fact , these procedures have been successfully used for effective correction of juvenile idiopathic / rheumatoid patients.21 we suggest that maxillary impaction surgery with advancement genioplasty offers a good prognosis without ingravescence of pcr . at the 30-month follow - up examination for our patient , we observed a slight decrease in the overbite caused by a moderate relapse in the mandibular dentition .
we will continue careful follow - ups for her , considering that surgically treated patients are generally at a high risk of relapse because of condylar remodeling or other skeletal changes.2
in the present report , we showed that le fort i osteotomy with two advancement genioplasty procedures was effective for the treatment of severe mandibular retrognathism with suspected pcr and eliminated the need for surgical mandibular advancement using bsso or do , which increases the risk of pcr in some patients .
the findings from our case suggest that this surgical treatment is effective for the correction of occlusion and esthetics in patients with severe mandibular retrognathism and condylar deformities , thus decreasing the risk of pcr observed with surgical mandibular advancement .
 we report a case involving a young female patient with severe mandibular retrognathism accompanied by mandibular condylar deformity that was effectively treated with le fort i osteotomy and two genioplasty procedures . at 9 years and 9 months of age , 
 she was diagnosed with angle class iii malocclusion , a skeletal class ii jaw relationship , an anterior crossbite , congenital absence of some teeth , and a left - sided cleft lip and palate . 
 although the anterior crossbite and narrow maxillary arch were corrected by interceptive orthodontic treatment , severe mandibular hypogrowth resulted in unexpectedly severe mandibular retrognathism after growth completion . 
 moreover , bilateral condylar deformities were observed , and we suspected progressive condylar resorption ( pcr ) . 
 there was a high risk of further condylar resorption with mandibular advancement surgery ; therefore , le fort i osteotomy with two genioplasty procedures was performed to achieve counterclockwise rotation of the mandible and avoid ingravescence of the condylar deformities . 
 the total duration of active treatment was 42 months . 
 the maxilla was impacted by 7.0 mm and 5.0 mm in the incisor and molar regions , respectively , while the pogonion was advanced by 18.0 mm . 
 this significantly resolved both skeletal disharmony and malocclusion . 
 furthermore , the hyoid bone was advanced , the pharyngeal airway space was increased , and the morphology of the mandibular condyle was maintained . at the 30-month follow - up examination , 
 the patient exhibited a satisfactory facial profile . 
 the findings from our case suggest that severe mandibular retrognathism with condylar deformities can be effectively treated without surgical mandibular advancement , thus decreasing the risk of pcr . 
INTRODUCTION
DIAGNOSIS AND ETIOLOGY
TREATMENT OBJECTIVES
TREATMENT ALTERNATIVES
TREATMENT PROGRESS
RESULTS
DISCUSSION
CONCLUSION