Orthodontic Morphological Evaluation of Treacher Collins Syndrome

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1 Cong. Anorn., 39: ,1999 Original Orthodontic Morphological Evaluation of Treacher Collins Syndrome Sachio UMEMURA Department of Orthodontics, Ohu University School of Dentistry, 31-1 Misumido Tomita, Koriyama , Japan ABSTRACT To establish a treatment for Treacher Collins syndrome, the maxillocraniofacial morphology was quantitatively evaluated by means of cephalometric radiography and the following results were obtained.. The cranial base showed a small value of S-ER (length of sphenoid bone in anterior cranial base), S-SOS (length of sphenoid bone in posterior cranial base) and S-Ba (length of posterior cranial base) in addition to similarly reduced NSBa, indicating undergrowth of the the cranial base as well. 2. Though the orbit had large BOD and BODfW with ocular hypertelorism, no abnormal finding was obtained in the antero-posterior positioning of the orbit in the skull. 3. n the maxillary region, the maxilla showed undergrowth but no abnormal finding was recorded on the vertical and antero-posterior positioning of the mandible. 1. The mandible showed undergrowth with a wide mandibular angle. n conclusion, the morphology evaluated quantitatively in patients with Treacher Collins syndrome varied considerably. Therefore, it was considered essential to evaluate the morphology accurately for treating this syndrome including surgery and orthodontic treatment. Key words: Treacher Collins syndrome, growth, cephalogram, dysmorphology Various specialists, including those from medical and dental fields, treat Treacher Collins syndrome. They require establishment of a good operative procedure and timing thereof. n particular, the role of orthodontists may be significant in consideration of improved occlusal anomalies. When treatment for disharmony of the jaw-oral cavity system is considered, it is very important to grasp accurately the maxillocraniofacial morphology characteristic of this syndrome and evaluate it quantitatively. n a patient who had visited our department with the chief complaint of open bite and was subsequently diagnosed as Treacher Collins syndrome, the maxillocraniofacial morphology was quantitatively evaluated using cephalometric radiographs in order to establish a treatment thereof.

cephalometric radiographs were taken. Fig. 1 Facial photographs Fig.

2 244 S. Umemura SUBJECT AND METHODS 1. Subject n order to quantitatively evaluate the maxillocraniofacial morphology in a patient with Treacher Collins syndrome who visited the orthodontic department of Ohu University, lateral cephalometric radiographs were taken. Fig. 1 Facial photographs Fig. 2 Oral photographs A 12 year 11 month old child in whom Treacher Collins syndrome was diagnosed at Kanagawa Children s Medical Center was referred to our department for detailed examination (Figs. 1,2) 2. Methods 1) Measurement points (Fig. 3) n accordance with the method proposed by Susami et al. (1986) the measurement points employed in this study included S, N, Ba, ANS, PNS, N, B, Ar, Go, Pog, OR, ER, ER and SOS. 2) Determination and calculation items The determination and calculation items were selected in accordance with the method of Susami et al. ( 1986).

3 Evaluation of Treacher Collins syndrome 245 Cranium Orbit w Cranial Base Maxilla Mandible Fig. 3 Cephalometric anlysis A) Cranium H: L: Ha: Hp: W: H/L: H/W: W/L: Hmp: H+L+W/3: B) Cranial base S-N: S-Ba: S-ER : s-sos : NSBa: S-ER /S-N: S-SOS k-ba: S -B a/s -N C) Maxilla N-ANS: S-PNS: ANS-PNS: Maximum height of skull Maximum length of skull Maximum height of anterior skull Maximum height of posterior skull Maximum width of skull Cranial morphology index Cranial morphology index Cranial morphology index Cranial morphology index Cranial volume index Length of anterior cranial base Length of posterior cranial base Length of sphenoid bone in anterior cranial base Length of sphenoid bone in posterior cranial base Angle of cranial base Ratio of sphenoid bone to posterior basilar length Ratio of sphenoid bone to posterior basilar length Ratio of anterior to posterior basilar length Height of anterior maxilla Height of posterior maxilla Anterior to posterior length of maxilla

4 246 S. Umemura SNA: Anterior to posterior protrusion degree of maxilla S-PNS/N-ANS: Ratio of anterior to posterior length of maxilla D) Orbit SN-OR BOD: Anterior to posterior protmsion degree of orbit nterorbital distance BOD/W: Ratio of interorbital distance to cranial width E) Mandible Ar-Go: Mandibular ramus height Go-Pog: Mandibular body length Ar-Pog: Total mandibular length SNB: Mand.p.-SN: Anterior to posterior protrusion degree of mandible Mandibular position G0.A: Gonial angle RESULTS Evaluation of maxillocraniofacial morphology is briefly described below. A) Cranium (Table ) The determined values for H, L, and W were mm, mm, and 159 mm, respectively, and all were within the standard ranges. H+L+W/3 was mm, within the standard range. B) Cranial base (Fig. 4, Table 2) S-Ba was relatively small, 43.5 mm exceeding -1 S.D. S-ER' was small, 24.5 mm exceeding -3 S.D. S-SOS' was small, 13.0 mm exceeding -2 S.D. S-BdS-N was small, 0.62 exceeding -2 S.D. S-ER'/S-N was small, 0.35 markedly exceeding -2 S.D. S-SOS'/S-Ba was small, 0.29 exceeding -2 S.D. NSB was small 119.0", exceeding -2 S.D. Table 1 Measurements of cranium tems Standard No Mean S.D. Meas. H L W Ha HP W/L H/L w H+L+W/ Hp/Ha (unit : mm,")

5 ~ S-ER' ~ N-S Evaluation of Treacher Collins syndrome s-sos' S-Ba (rnrn) S-Ba/S-N i (' 1 L... Fig. 4 Measurement of crainal base Table 2 Measurements of cranium base tems Standard No Mean S.D. Meas. N- s S-Ba S-ER' s-sos' S -B a/s-n S-ER'/S-N S-SOS'/S-Ba NSBa (unit : mm,") C) Orbit (Fig. 5, Table 3) BOD was relatively large, 30.0 exceeding +3 S.D. BOD/W was large, 0.18 exceeding +4 S.D. D) Maxilla (Fig. 6, Table 4) ANS-PNS was relatively small, exceeding -1 S.D.

6 248 S. Umemura! ! B..O.D./W t Fig. 5 Measurement of orbit Table 3 Measurements of orbit tems Standard No Mean S.D. Meas. B..0.D B..0.D.N SNOR (unit : mm,") E) Mandible (Fig. 7, Table 5) Ar-Go was relatively small, 37.0 mm exceeding -1 S.D. Go-Pog was small 59.5 mm, exceeding -1 S.D. Ar-Pog was small 87.5 mm, exceeding -1 S.D. Go.A was large 139.0", exceeding +2 S.D. Mand.P.-SN was large 56.5", exceeding +2 S.D. SNB was small 71.5, exceeding -1 S.D. DSCUSSON 1. Evaluation of maxillocraniofacial morphology Abnormal skeletal morphology, a representative finding of this syndrome, is characteristically observed

7 ~ _._. Evaluation of Treacher Collins syndrome '49 1 Table 4 Measurements of maxilla tems Standard No Mean S.D. Meas. ANS-PNS N-ANS S-PNS S-PNS/N-ANS SNA (unit : mm,') r-- Go-Pog 10 Standard,i ~ r- LMand.P-SN LG0.A - i (mm) (' ) - _~ Fig. 7 Measurements of mandible

8 250 S. Umemura Table 5 Measurements of mandible tems Standard No Mean S.D. Meas. Ar-Go Go-Pog Ar-Pog Ar-GoGo-Pog Go.A Mand.P-SN SNB (unit : mm,") throughout the maxillocraniofacial region and requires prolonged treatment. There have been fewer reports on this syndrome from the orthodontic field than those from the medical field. n addition, the evaluation of the maxillocraniofacial morphology in the orthodontic field is mainly morphological evaluation by Down's method. Since only anterior-posterior evaluation is successfully performed with this method, an analytical method for malocclusion usually employed in daily orthodontic practice is considered to be inadequate for knowing the complicated maxillocraniofacial morphology seen in this syndrome. Motohashi and Kuroda ( 1982) presented the following problems encountered when a conventional morphological analysis was applied to examine congenital anomalies. 1) The morphological properties of this syndrome are hardly grasped from the standpoint of harmonized complex as a whole. 2) A standard plane (FH plane, SN-Ba plane) frequently used in general is apt to be included in the phenotype of congenital anomalies. 3) The shape and size of skull and cranial base, which should be analyzed as a minor deformity, are difficult to grasp. From the problems mentioned above, the method of evaluation for this syndrome employed in the present study was in accordance with the analytical items proposed by Susami et al. ( 1986). They reported that ER' and SOS' were established to know which constitution unit in the antero-posterior cranial base has a morphological anomaly. n this study, therefore, the vertical component was assessed in addition to the antero-posterior size of the maxilla and the degree of protrusion towards the cranium. As for the abnormal orbit in this syndrome, a quantitative evaluation was made according to the method proposed by Pruzansky (1976) and Motohashi (1985). Thus, in order to know the congenital morphological anomalies, it seems necessary to quantitatively grasp the cranium as a whole when orthodontic or surgical treatment is performed. n this study, therefore, the method by Susami et al. (1986) was employed for examination. 2. ndividual assessment of maxillocraniofacial morphology 1) Cranium When the morphology of cranium was evaluated in the present case of Treacher Collins syndrome, the determined cranial volume index was within standard ranges. No information on the morphological measurements of cranium is, however, available in previous reports on Treacher Collins syndrome. The small value of cranial volume index determined in the present case may indicate that an adverse

Evaluation of Treacher Collins syndrome 75 influence on the development of the brain itself might have resulted in a smaller cranium and its suppressed growth.

9 Evaluation of Treacher Collins syndrome 75 influence on the development of the brain itself might have resulted in a smaller cranium and its suppressed growth. Based on the above mentioned evidence, it was estimated that Treacher Collins syndrome observed in the present study is probably giving some adverse influence on the cranium during the developmental period as well. 2 ) Cranial base t was revealed from the present evaluation of cranial base morphology that S-Ba was considerably small, exceeding - S.D. Small determined values were also obtained for S-ER, exceeding -3 S.D., and for S-SOS, exceeding -2 S.D. S-ER /S-N, S-SOS /S-Ba, and S-Ba/S-N also showed small determined values exceeding their normal ranges. Furthermore, the determined value of NSBa was small, exceeding -3S.D. As for the frontal base in Treacher Collins syndrome, Hara et al. ( 1977) showed that S-N was indicative of anterior cranial base. n the patient with Treacher Collins syndrome examined in this study, poor growth of the sphenoethomoidal suture was observed. Undergrowth of the occipital base and S-ER were observed in Treacher Collins syndrome examined in this study, a finding similar to that observed by Hara et al. (1977). As for the pathogenesis of Treacher Collins syndrome, Franceschetti and Klein (1949) reported that this syndrome is caused by disturbed 1st and 2nd branchial arches from the 7th to 9th weeks of the prenatal period. t is considered that some disturbance may participate in the early stage of the prenatal period, resulting in undergrowth of the cranial base. n the present study, the indices exceeding -3 S.D. suggested undergrowth in the anterior to posterior dimension of the cranial base. n the present case of Treacher Collins syndrome, a suppressed growth of the sutured site of sphenoid bone was evident. Suppressed growth of posterior cranial base and S-ER was observed in the present case of Treacher Collins syndrome, quite similar to that reported by Hara et al. (1977). t is considered that some disturbance may participate in the early stage of the prenatal period, resulting in abnormal values for the cranial base angle. n the present study, the patient with Treacher Collins syndrome showed small determined values for cranial base angle. However, Hara et al. (1977) made no statement concerning the cranial base angle in Treacher Collins syndrome. The above suggested that the size of the cranial base angle may vary in response to the degree of influence on the growth of the cranial base. t was also indicated from the above that a growth disturbance of the cranial base may occur due to some adverse influences from the 10th to 30th weeks of the prenatal period when the cranial base generally grows. n addition, the growth of the cranial base was indicated to be influenced by the growth of the brain. The smaller values for the cranial volume index determined in this study suggested that undergrowth of the cranial base might have induced a narrow angle of the cranial base. 3) Orbit As a result of examination of the orbit in the patients with Treacher Collins syndrome, BOD and BlOD/W showed large values exceeding the normal range but SN-OR was within the normal range. Although no anteroposterior abnormality was detected in the orbit, positioning of the orbit varied depending on the ratio of cranial width to diameter. However, no report on the orbit in patients with Treacher Collins syndrome is available in the related literature. The large determined value of BOD may indicate ocular hypertelorism with hypoexophoria of eyelid, a skeletal form when the appearance is evaluated morphologically. 4) Maxillary region Patients with Treacher Collins syndrome showed undergrowth with smaller values of ANS-PNS, and the vertical and antero-posterior positioning of the maxilla against the frontal base were within the normal range.

10 252 S. Umemura This may indicate that some influence from the cranial base occurred, but the influence was reflected only on the size of the maxilla. Hara et al. (1977) reported that the size of the maxilla tended to be small with no abnormal antero-posterior positioning as described for patients with Treacher Collins syndrome. Takeshita et al. (1994) also reported that both SNA and N-ANS were within the normal range in patients with Treacher Collins syndrome. n conclusion, maxillary growth may show no anomalies vertically and antero-posteriorly though undergrowth is evident in Treacher Collins syndrome. 5) Mandibular region n the mandibular region of the patient with Treacher Collins syndrome, Ar-Go, Go-Pog and Ar-Pog all showed small values, exceeding the normal range, indicating undergrowth of the mandible. Go.A and Mand.P- SN showed large values exceeding the normal range, while SNB showed a small value exceeding the normal range with a wide mandibular angle positioned posteriorly against the cranial base. Roberts and Purzansky (1975) reported that SNB and SNP were remarkably small with so called bird-like or fish-like appearance. Arvystas and Shprinzen (1991) reported that ANS-Me was augmented due to the markedly receded mental region. Takeshita et al. (1994) reported that SNB and ANP were very small but the gonial angle and SNmandibular plane were very large similar to our finding. Treacher Collins syndrome is considered to have remarkable morphologic properties in the mandible. These findings of the mandible are characteristic of a lot of related syndromes, might have influenced the masticatory muscles adhering to the mandible, leading to a markedly abnormal mandible. From the above, the mandible in patients with Treacher Collins syndrome showed undergrowth with wide mandibular angle attached to posterior positioning. n conclusion, to establish a treatment for Treacher Collins syndrome, the maxillocraiofacial morphology should be quantitatively evaluated by means of cephalometric radiography. Patients with Treacher Collins syndrome varied considerably. Therefore, it is essential to evaluate the morphology accurately for treating this syndrome including surgery and orthodontic treatment. REFERENCES Arvystas, M. and Shprintzen, R.J. (1991) Craniofacial morphology in Treacher Collins syndrome. Cleft Palate Craniofac. J., 28: Franceschetti, A. and Klein, D. ( 949) The mandihulo-facial dysostoais: A new herediatary syndrome. Opthalmol., 27: Acta Hara, M., Sakuda, M., Ozeki, S. and Kitamura, T. (1977) Tow cases of mandibulofacial dysostosis. J Osaka Univ. Dent. Soc., 22: Motohashi, N. ( 1985) Craniofacial dysmorphology in syndromes associated with abnormal physical growth. J. Craniofac. Genet. Devel. Biol. Suppl., 1: Motohashi, N. and Kuroda, T. ( 1982) Morphological analysis of congenital anomalies... Stom. SOC., 49: 698. Pruzansky, S. (1976) Symposium on Development of the Basicranium. Bethesda, Maryland, DHEW Publication (NH), Roberts, F.G. and Pruzansky, S. (1975) An X- radiocephalometric study of mandibulo-facial dysostosis in man. Arch. Oral. Biol., 20: Susami, T., Terashima, T., Lin, T. Motohashi, N. and Kuroda, T. (1986) Morphological evaluation on craniofacial dysmorphology of Apert s syndrome and Crouzon disease. J. Jpn. Orthod. Soc., 45: Takeshita, T., Maruyama, Y., Maeda, A,, Hirano. A. and Kohayashi, K. ( 1994) Surgical orthodontic treatment of Treacher Collins syndrome: A case report. J. Jpn. Orthod. Soc., 53:

EUROPEAN SOCIETY OF LINGUAL ORTHODONTICS

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