The Determinants of Successful Distraction Osteogenesis of the Mandible in Hemifacial Microsomia From Longitudinal Results

Evaluation of post-activation mandibular remodelling in children with craniofacial microsomia treated with distraction osteogenesis

OBJECTIVE

Patients with type IIA craniofacial microsomia (CFM) may benefit from mandibular distraction osteogenesis (MDO) treatment during childhood; however, remodelling of the mandible during the consolidation phase, which may affect the short-term outcomes of MDO, has not yet been quantitatively analysed using computed tomography. Therefore, we aimed to investigate bone remodelling of the mandible in children with type IIA CFM treated with MDO before distractor removal and the factors that influence ramus vertical elongation efficiency.

MATERIALS AND METHODS

Twenty-three children with unilateral CFM were studied between 2020 and 2024. Longitudinal computed tomography data (preoperative, end of active phase and at pre-distractor removal) were analysed. Condyle positions and the mandibular cant were analysed using a paired-sample t test. The relapse rates of vertical lengthening and mandibular cant were calculated. The correlation between distraction efficiency and preoperative craniofacial morphology was analysed.

RESULTS

The condyle on the affected side moved upwards and backwards by 28.84 ± 4.08 and 2.85 ± 4.33 mm, respectively during the active phase but lost 7.66 ± 2.64 mm of vertical extension during the consolidation phase. The relapse rates for vertical extension of the condyle and occlusal plane were 27% and 35%, respectively. The ratio of mandibular ramus height was positively related to EV.

CONCLUSIONS

In children with CFM, attention should be paid to vertical elongation instability and relapse of mandibular inclination during consolidation. Severe mandibular ramus hypoplasia is a preoperative risk factor for vertical skeletal relapse during consolidation. Further efforts are required to reduce the stress that leads to relapse.

Growth characteristics and classification systems of hemifacial microsomia: a literature review

BACKGROUND

Hemifacial microsomia is characterized by the hypoplasia of the mandible and temporomandibular joint, involving a variety of abnormalities of the craniofacial area. Since it gradually worsens as patients grow, it is necessary to understand the characteristics of facial bone growth and facial deformity in hemifacial microsomia patients in order to determine appropriate treatment timing and treatment methods.

MAIN BODY

Appropriate classification of hemifacial microsomia would facilitate accurate diagnosis, selection of treatment methods, and prognosis prediction. Therefore, in this article, we review previously published hemifacial microsomia classification and provide an overview of the growth of the facial skeleton and the characteristics of hemifacial microsomia-related facial deformities. The OMENS system is the most comprehensive classification method based on the characteristics of hemifacial microsomia deformity, but it needs to be improved to include malar/midface abnormalities and nerve involvement. In hemifacial microsomia, growth is progressing on the affected side, but to a lesser degree than the unaffected side. Therefore, surgical intervention in growing patients should be performed selectively according to the severity of deformity.

CONCLUSION

Understanding growth patterns is important to develop appropriate treatment protocols for correcting asymmetry in adult patients and to minimize secondary anomalies in growing patients.

Role of Temporomandibular Total Joint Replacement in Correction of Facial Deformities

Introduction

Individuals suffering from facial deformities experience esthetic, functional and social setback in their lives every day. These patients benefit greatly with single-stage temporomandibular joint replacement along with orthognathic surgical procedures to correct functional as well as esthetic components.

Methodology

Five individuals with facial deformities due to hemifacial macrosomia, fibrous dysplasia, idiopathic condylar resorption, ankylosis, etc., were treated with total joint replacement along with orthognathic surgical procedures for functional and esthetic correction. The customized temporomandibular joint was digitally custom designed, and the orthognathic procedures were virtually planned on NemoFAB software before performing the surgical procedure.

Results

Intraoperatively, the overall time was reduced considerably with minimal unpredictable complications. One-week postoperative computed tomographs were obtained and superimposed on preoperative virtual surgical planning which showed minimal discrepancy. Follow-up period of 18-30 months was maintained for all the patients with stable results, minimal relapse and satisfactory functional abilities.

Discussion

Total joint replacement along with orthognathic procedure provides single-stage functional and esthetic corrections for the patients, considerably improving their quality of life. Precise preoperative surgical planning proves to be an indispensable step for achieving desired results with minimal margin of error and avoid any unseen complications during the surgical procedure.

Distribution and Phenotype of Goldenhar Syndrome and Its Association With Other Anomalies

The purpose of this study was to investigate the distribution and phenotype of Goldenhar syndrome (GS) and its association with other anomalies. The samples consisted of 18 GS patients (6 males and 12 females; mean age at investigation, 7.4 ± 4.8 y) who were treated or followed up at the Department of Orthodontics, Seoul National University Dental Hospital between 1999 and 2021. The prevalence of side involvement and degree of mandibular deformity (MD), midface anomalies, and association with other anomalies were evaluated using statistical analysis. The prevalence of unilateral and bilateral MD did not differ (55.6% versus 44.4%). In unilateral MD cases, there was a tendency for higher prevalence of more severe Pruzansky-Kaban types than mild ones (type I, 10%; type IIa, 10%; type IIb, 50%; type III, 30%). Despite hypoplasia of the condyle/ramus complex, compensatory mandibular body growth occurred in 33.3% of GS patients (more severe side in bilateral MD cases, 37.5%, and ipsilateral side in unilateral MD cases, 30%). Class II molar relation was more prevalent than class I and class III molar relations (72.2% versus 11.1% versus 16.7%, P <0.01). Al total of 38.9% of patients had congenitally missing tooth. #7 facial cleft was found in 44.4% of patients. In midface anomalies, ear problem was the most common anomaly, followed by hypoplasia/absence of zygomatic arch and eye problem (88.9% versus 64.3% versus 61.1%, P <0.01). Association with the midface, spine, cardiovascular, and limb anomalies did not differ between unilateral and bilateral MD cases. These results might provide a basic guideline for diagnosis and treatment planning for GS patients.

Bone Density of the Condyle of Children with Craniofacial Microsomia and its Correlation with Condylar Resorption After Mandible Distraction Osteogenesis

OBJECTIVE

To investigate condylar bone density (BD) in children with craniofacial microsomia (CFM) and identify factors that contribute to early stage condylar resorption (CR) after mandibular distraction osteogenesis (MDO).

DESIGN

Retrospective study.

SETTING

Craniofacial department of a plastic surgery hospital.

PATIENTS

Fifty-one children with CFM classified as Pruzansky IIa based on complete pre-(T0) and post-MDO (T1) computed tomography (CT) data.

INTERVENTION AND MAIN OUTCOME MEASUREMENTS

Mimic 21.0 (Materialise Inc., Belgium) was used to measure bilateral BD and condylar height (CH) and volume (CV) of affected side. Children were split into groups based on either affected side BD or the distraction length (DL,25 mm as cutoff) .Bilateral BD was compared using a paired t-test in each group. The CH and CV of affected side at T0 and T1 were compared. The relative values of the CH and CV (CH ratio) and the volume (CV ratio) of the affected side were compared across the groups.

RESULTS

The BD was lower on affected side than on unaffected side. Regarding BD, CH and CV decreased after MDO in group I, while the CH ratio and CV ratio of group I was lower than that of groups II and III. Regarding DL, the CV ratio was lower in Group L than Group S.

CONCLUSIONS

The condylar bone quality on affected side is compromised in type IIa CFM. A low BD in combination with a larger distraction distance may increase the risk of CR; therefore, MDO in patients with such characteristics should be postponed.

Treatment modalities for Korean patients with unilateral hemifacial microsomia according to Pruzansky-Kaban types and growth stages

Objective

To investigate the treatment modalities (Tx-Mods) for patients with unilateral hemifacial microsomia (UHFM) according to Pruzansky–Kaban types and growth stages.

Methods

The samples consisted of 82 Korean UHFM patients. Tx-Mods were defined as follows Tx-Mod-1, growth observation due to mild facial asymmetry; Tx-Mod-2, unilateral functional appliance; Tx- Mod-3, fixed orthodontic treatment; Tx-Mod-4, growth observation due to a definite need for surgical intervention; Tx-Mod-5, unilateral mandibular or bimaxillary distraction osteogenesis (DO); Tx-Mod-6, maxillary fixation using LeFort I osteotomy and mandibular DO/sagittal split ramus osteotomy; Tx- Mod-7, orthognathic surgery; and Tx-Mod-8, costochondral grafting. The type and frequency of Tx-Mod, the number of patients who underwent surgical procedures, and the number of surgeries that each patient underwent, were investigated.

Results

The degree of invasiveness and complexity of Tx-Mod increased, with an increase in treatment stage and Pruzansky–Kaban type (initial < final; [I, IIa] < [IIb, III], all p < 0.001). The percentage of patients who underwent surgical procedures increased up to 4.2 times, with an increase in the Pruzansky–Kaban type (I, 24.1%; IIa, 47.1%; IIb, 84.4%; III, 100%; p < 0.001). However, the mean number of surgical procedures that each patient underwent showed a tendency of increase according to the Pruzansky–Kaban types (I, n = 1.1; IIa, n = 1.5; IIb, n = 1.6; III, n = 2.3; p > 0.05).

Conclusions

These findings might be used as basic guidelines for successful treatment planning and prognosis prediction in UHFM patients.

Leveling the Maxillary Occlusal Plane Without Orthodontic Appliances in Patients With Hemifacial Microsomia Using Unilateral Vertical Mandibular Distraction Osteogenesis

PURPOSE

To assess maxillary occlusal plane correction in patients with hemifacial microsomia (HFM) after vertical vector mandibular distraction osteogenesis (vMDO) without orthodontic appliances.

METHODS

A retrospective study was performed on consecutive patients with HFM and Kaban-Pruzansky type-II mandibular deformities who underwent unilateral vMDO by a single surgeon over an 18-month period. Patients with 12-months minimum clinical follow-up and postero-anterior (PA) cephalograms taken preoperatively and at a minimum of 3 months post-consolidation were included.

RESULTS

Five patients met inclusion criteria, 3 were female, median age was 13 years, median distraction length was 21.3 mm. Median radiographic follow-up was 5 months (range 3-38) post-consolidation. Median correction of the ramus height differential (difference between non-diseased and diseased side) was 97.3%. Median maxillary height differential correction was 72.2%. Median maxillary occlusal plane angle correction (towards zero) was 84.2%. Relative and absolute maxillary bone growth was greater on the diseased side (median 7.4%, 3.5 mm versus 2.8%, 1.4 mm). Dentoalveolar height decreased bilaterally in 4 of the 5 patients. Median chin point correction (towards midline) was 31.4%.

CONCLUSION

Unilateral vMDO without orthodontic appliances effectively corrected mandibular ramus height, leveled the maxillary occlusal plane, and preferentially increased maxillary bone growth on the diseased side in patients with HFM.

Distribution and phenotypes of hemifacial microsomia and its association with other anomalies

Objective

To investigate the distribution and phenotypes of hemifacial microsomia (HFM) and its association with other anomalies.

Methods

This study included 249 Korean patients with HFM, whose charts, photographs, radiographs, and/or computed tomography scans acquired during 1998–2018 were available from Seoul National University Hospital and Dental Hospital. Prevalence according to sex, side involvement, degree of mandibular deformity, compensatory growth of the mandibular body, and Angle's classification, and its association with other anomalies were statistically analyzed.

Results

Prevalence was not different between male and female patients (55.0% vs. 45.0%, p > 0.05). Unilateral HFM (UHFM) was more prevalent than bilateral HFM (BHFM) (86.3% vs. 13.7%, p < 0.001). Although distribution of the Pruzansky–Kaban types differed significantly in patients with UHFM (I, 53.0%; IIa, 18.6%; IIb, 24.7%; III, 3.7%; p < 0.001), no difference was observed in occurrence between the right and left sides (52.6% vs. 47.4%, p > 0.05). Among patients with BHFM, prevalence of different Pruzansky–Kaban types on the right and left sides was greater than that of the same type on both sides (67.6% vs. 32.4%, p < 0.05). Despite hypoplasia of the condyle/ramus complex, compensatory growth of the mandibular body on the ipsilateral side occurred in 35 patients (14.1%). Class I and II molar relationships were more prevalent than Class III molar relationships (93.2% vs. 6.8%, p < 0.001). Forty-eight patients (19.3%) had other anomalies, with 50.0% and 14.4% in the BHFM and UHFM groups (p < 0.001).

Conclusions

Patients with HFM require individualized diagnosis and treatment planning because of diverse phenotypes and associations with other anomalies.

Goldenhar syndrome: current perspectives

BACKGROUND

Progress in medical branches that has taken place since the first child with Goldenhare syndrome (GS) had been described in 1952 by Maurice Goldenhar, facilitated better understanding of this congenital defect. It also gave new perspectives and the opportunity to achieve satisfactory treatment results, mainly due to development of surgical techniques.

DATA SOURCES

Based on the literature and own experience, we discussed the phenotype of presentation of GS, ethiopathogenesis, genetic counselling and treatment with particular emphasis on surgery correction of hemifacial microsomia.

RESULTS

The spectrum of GS abnormalities ranges from mild to severe ones and include patients with barely noticeable facial asymmetry to very pronounced facial defect with more or less severe abnormalities of internal organs and/or skeleton. It is characterized most commonly by impaired development of eyes, ears, lips, tongue, palate, mandible, maxilla, zygomatic and orbital structures and deformations of the teeth structures. Ethiopathogenesis is multifactorial and dependent on genetic and environmental factors but there are still many unknowns about the syndrome which should be revealed.

CONCLUSIONS

Patients with GS due to a large variety of abnormalities and different severity of symptoms pose a challenge for clinicians. All of this necessitate an individual approach to each single patient and involvement a team of specialists in treatment planning. It is a complex, long-lasting, multidisciplinary process and should be divided into stages, according to patient's age, as well as the extent and severity of observed abnormalities. Neonatologists and pediatricians are involved in care of these patients from the onset.

Combined Bimaxillary Distraction Osteogenesis Associated with Orthognathic Surgery for Hemifacial Microsomia in Adults

BACKGROUND

Hemifacial microsomia (HFM) is one of the most common congenital craniofacial asymmetries. Distraction osteogenesis (DO) is always recommended as an effective option for the treatment of HFM, but some studies showed that the asymmetry remained after DO. In comparison with DO, stable clinical outcomes could be achieved by orthognathic surgery approach as well. However, soft tissue expansion cannot be performed. In this study, we aim to assess the radiographic and clinical results of bimaxillary DO associated with staged orthognathic surgery in the treatment of craniofacial asymmetry for adult HFM patients.

METHODS

Twelve HFM patients who had been treated with bimaxillary DO and secondary orthognathic surgery between 2006 and 2013 were included in this study. Bimaxillary DO and staged orthognathic surgery were performed according to the particular condition. Clinical and cephalometric photographs were carried out pre- and postoperatively to evaluate the outcomes.

RESULTS

No significant complications occurred postoperatively. Excellent cosmetic outcomes such as notable improvement in facial pattern and occlusion were achieved. Cephalometrically, the height ratios of the affected/unaffected ramus were improved by 23.81% on average, and the photographic analysis demonstrated a rotation of the chin point toward the mid-line. Moreover, the occlusal cant was corrected from the slant to level by 8.95° on average.

CONCLUSION

The application of bimaxillary DO associated with staged orthognathic surgery in correcting the asymmetry of adult patients with HFM could have satisfactory aesthetic results, and it should be considered an alternative option for these patients.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Bimaxillary Orthognathic Approach to Correct Skeletal Facial Asymmetry of Hemifacial Microsomia in Adults

BACKGROUND

Hemifacial microsomia (HFM) is the second most common congenital craniofacial deformity after cleft lip and palate. Distraction osteogenesis (DO) is regarded as an alternative and efficient treatment option for patients with HFM. However, DO was not proven effective for all cases, and the results of long-term follow-up were not satisfactory as expected. Compared with DO, the orthognathic surgery approach may offer more stable clinical outcomes for this kind of disease. The purpose of this study is to evaluate the long-term clinical and radiographic outcome of bimaxillary orthognathic surgery in the treatment of adult HFM.

METHODS

Eight patients with HFM who had undergone bimaxillary orthognathic surgery between 2008 and 2012 were included in the study. The surgical procedures included Le Fort I osteotomy, inverted-L osteotomy, sagittal split ramus osteotomy, genioplasty, and iliac bone grafting. Pre- and postoperative orthodontic treatments were performed, respectively. Clinical and radiographic examinations were carried out to assess postoperative outcomes.

RESULTS

No obvious complications appeared postoperatively and no recurrences occurred during follow-up. All patients obtained satisfactory aesthetic results. Marked improvement in facial contour and occlusion were observed. Plain radiographs showed that the height ratios between the affected and unaffected ramus were ameliorated significantly.

CONCLUSION

The bimaxillary orthognathic approach to correct the deformity of adult HFM can obtain stable results in the long-term follow-up, and should be considered as a priority method for the treatment of adult patients with dentofacial deformity.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Clinical care in craniofacial microsomia: a review of current management recommendations and opportunities to advance research

Craniofacial microsomia (CFM) is a complex condition associated with microtia, mandibular hypoplasia, and preauricular tags. It is the second most common congenital facial condition treated in many craniofacial centers and requires longitudinal multidisciplinary patient care. The purpose of this article is to summarize current recommendations for clinical management and discuss opportunities to advance clinical research in CFM.

Changes in width of lower face after unilateral mandibular distraction osteogenesis

Distraction osteogenesis (DO) has been popular to improve hypoplastic mandible in patients with hemifacial microsomia in craniofacial surgery. However, changes in width of the lower face after DO still lack in literatures. The aim of this pilot study was to evaluate cephalometric changes in width of the lower face at different time points after DO and to give an insight into the influence on facial contour. A total of 10 patients (8 males and 2 females) with hemifacial microsomia received DO of the mandibular body measured by posteroanterior cephalograms. Five landmarks (crista galli, latero-orbitale, gonion of the unaffected side, incisor point superior of the unaffected maxilla, incisor point inferior of the unaffected side of the mandible) were chosen for cephalometric analysis. Six distances from the soft tissue contour perpendicularly to the vertical reference line (through crista galli) were calculated through the incisor point superior of the unaffected maxilla, gonion of the unaffected side, incisor point inferior of the unaffected side of the mandible. Measurements were taken preoperatively and postoperatively on the day distraction started (time 1), at the end of distraction (time 2), and at the end of the consolidation period (time 3). Calculations for statistical significance were done for all patients. Mean differences between 3 periods were measured by repeated-measures analysis with significance determined at the 0.05 level of confidence. The results suggested that the values of 6 distances at times 2 and 3 had no significant differences when compared with the values at time 1 (P>0.05). In conclusion, DO of the unilateral mandibular body in patients with hemifacial microsomia should not be beneficial to improve the width of the lower face at a short-term follow-up.

No evidence for long-term effectiveness of early osteodistraction in hemifacial microsomia

BACKGROUND

The authors performed a critical literature review to find evidence of the long-term stability after early distraction osteogenesis of the mandible in patients with hemifacial microsomia.

METHODS

The PubMed, Cochrane, MEDLINE, EMBASE, CENTRAL, and CINAHL databases were searched systematically for studies performed between 2002 and 2008. Abstracts from the 89 relevant articles were reviewed for evidence.

RESULTS

Thirteen articles met the inclusion criteria. Data were tabulated with respect to the length of follow-up, number of patients, age group, Pruzansky-Kaban classification of the patients, methods of analysis and validation, and level of evidence. Methods for long-term follow-up studies were not standardized, and no objective studies have been published on stability after growth cessation.

CONCLUSIONS

Thus far, no randomized controlled trials on early distraction osteogenesis in hemifacial microsomia patients have been published. The authors conclude that there is a lack of statistical evidence to support the use of early distraction osteogenesis for correcting hemifacial microsomia as a single treatment modality. The results call into question its rationale.

Ten-year follow-up of a patient with hemifacial microsomia treated with distraction osteogenesis and orthodontics: an implant analysis

INTRODUCTION

Distraction osteogenesis (DO) has become an accepted treatment method for patients requiring mandibular lengthening because of congenital malformations. However, the skeletal growth pattern of a distracted mandible in the long term has still not been clearly shown in the literature. The purpose of this report was to analyze the dentofacial changes observed during a 10-year follow-up period in a patient treated with mandibular DO.

METHODS

The patient was a 12-year-old girl with hemifacial microsomia who had undergone DO with an external device. Morphologic changes during the observation period were evaluated on panoramic radiographs and posteroanterior and lateral cephalograms. Six Björk-type titanium implants were placed bilaterally in the mandible under local anesthesia to analyze the mandibular skeletal changes over time.

RESULTS

Marked lengthening was achieved during the active phase of mandibular distraction. The ratio between the ramus heights of the affected and normal sides improved significantly in the affected side's favor as the mandible was lengthened, but this ratio returned to its initial value after 10 years.

CONCLUSIONS

Although there was some growth on the affected side during the follow-up period, it was not enough to catch up with the growth on the normal side. The original asymmetry recurred as a consequence of the growth pattern in this patient with hemifacial microsomia.

Time Course of Expression of Bcl-2 and Bax in Rabbit Condylar Chondrocytes Following Forward Mandibular Positioning

Objective: To clarify the expression of Bcl-2 and Bax following forward mandibular positioning (FMP) in the condylar chondrocytes of rabbits.

Materials and Methods: Sixty rabbits at 8 weeks of age were randomly allocated to the experimental group (n = 36) and control group (n = 24). Rabbits in the experimental group were induced to FMP by a functional appliance. Six rabbits from the experimental group and four from the control group were sacrificed after 3 days and 1, 2, 4, 8, and 12 weeks, respectively. All the right temporomandibular joints (TMJs) were collected and the expression of Bcl-2 and Bax was evaluated by immunohistochemical staining.

Results: The results showed the expression pattern of Bcl-2 and Bax during 12 weeks after FMP. The expression of Bcl-2 reached the highest level at 1 week, whereas Bax reached its maximal expression after 4 weeks. Subsequently, the expression of Bcl-2 and Bax gradually decreased. The ratio of Bcl-2/Bax began to decrease 3 days after FMP and continued to decline until 12 weeks.

Conclusions: FMP with functional appliances could change the expression of Bcl-2 and Bax, which is related to apoptosis in condylar chondrocytes.

Meta-analysis of mandibular distraction osteogenesis: clinical applications and functional outcomes

BACKGROUND

Mandibular distraction osteogenesis has been used effectively to treat syndromic craniofacial deformities. In recent years, its scope of application has widened to include treatment of airway obstruction in adults and children and nonsyndromic class II mandibular hypoplasia. So far, there has been no evidence-based review of mandibular distraction osteogenesis for mandibular lengthening.

METHODS

Two rounds of searches were performed by two independent assessors. The first-round PubMed search used the keywords "mandible" and "distraction osteogenesis." In the second-round search, the reference lists of the articles were retrieved. For both rounds, abstracts and then full articles were reviewed and selected on the basis of a set of inclusion and exclusion criteria.

RESULTS

The 178 retrieved articles yielded 1185 mandibular distraction osteogenesis patients: 539 received unilateral mandibular distraction osteogenesis and 646 received bilateral mandibular distraction osteogenesis. Mandibular distraction osteogenesis was reported to improve facial asymmetry and retrognathia (50.1 percent), correct the slanted lip commissure (24.7 percent), and improve or level the mandibular occlusal plane (11.1 percent) in unilateral asymmetry cases, whereas bilateral mandibular distraction osteogenesis was shown to be effective in preventing tracheostomies for 91.3 percent of neonates or infants with respiratory distress, and in relieving symptoms of obstructive sleep apnea for 97.0 percent of children and 100 percent of adult patients.

CONCLUSIONS

Mandibular distraction osteogenesis is effective in treating craniofacial deformities, but further clinical trials are required to assess the long-term stability and to compare the treatment with conventional treatment methods, especially in cases of obstructive sleep apnea or class II mandibular hypoplasia.