Mandibular symphyseal midline distraction osteogenesis for micrognathia associated with aglossia and situs inversus totalis

Abstract

Aglossia is a rare congenital abnormality, often associated with micrognathia and limb defects. Situs inversus totalis is also a rare congenital abnormality, defined as a mirror-image reversal of all the asymmetric organs of the thorax and abdomen. The concurrence of these two abnormalities has only been reported in eight similar cases in the literature. Although micrognathia and malocclusion were observed in all of these cases, few treatments were performed for the patients’ dentofacial deformities. This report describes the case of a 7-year-old boy suffering from micrognathia, aglossia, and situs inversus totalis simultaneously, and the treatment for his micrognathia by mandibular symphyseal midline distraction osteogenesis, guided by virtual surgical planning and a three-dimensional printed surgical template. In a review of the literature, this is the first case of micrognathia associated with aglossia and situs inversus totalis that has been treated by mandibular symphyseal midline distraction osteogenesis for the dentofacial deformity.

Aglossia is a rare congenital abnormality, occurring either as an isolated abnormality or in association with others, particularly micrognathia and limb defects . Situs inversus totalis (SIT), defined as a mirror-image reversal of all the asymmetric structures of the thorax and abdomen, is also a rare congenital abnormality . Since the first report in 1925 by Watkin, their concurrence has only happened in eight similar and sporadic cases in the literature . Although micrognathia and malocclusion were observed in all of these cases, few cases paid attention to the patients’ dentofacial deformities, which led to several secondary problems (e.g. masticatory difficulty, negative perception of facial aesthetics, psychological problems, and malnutrition) and greatly decreased the patients’ quality of life.

The case of 7-year-old boy suffering from micrognathia, aglossia, and SIT simultaneously is presented herein. The treatment provided for the patient’s dentofacial deformity − mandibular symphyseal midline distraction osteogenesis (MMD) − is described. Virtual surgical planning and a three-dimensional (3D) printed surgical template were applied to guide the surgery. In a review of the literature, this is the first case of micrognathia associated with aglossia and SIT treated by MMD for the dentofacial deformity.

Case report

The patient was a 7-year-old boy, who was admitted due to masticatory difficulty and facial deformity. He was born at term by normal spontaneous delivery, with normal weight, body measurements, and head circumference. At birth, aglossia and micrognathia were observed, but there were no limb defects or other external abnormalities. The boy subsequently experienced several functional problems. First, taking food was difficult. Because of the aglossia, the boy had difficulties sucking and swallowing. Thus, he was fed via a nasogastric tube until he could feed orally at the age of 1 year. Moreover, because of the micrognathia, his masticatory efficiency was very low and it was hard for him to eat fast and carefully. Second, the patient’s speech was problematic. Most of the Chinese words he said, especially words with retroflex, were not clear. Third, when he was sleeping, snoring was noted by his parents, although this was not severe and was managed by lateral positioning. Since the boy’s development was otherwise normal while the development of his hypoplastic mandible was abnormal, his masticatory difficulty and facial deformity became increasingly obvious. Eventually, he was admitted to the hospital for treatment.

There was no family history of congenital abnormalities, and the parents were healthy. The mother was in good condition during gestation, with no history of smoking, drinking, prenatal illness, drug usage, or radiation exposure. However, during the first 7 months of gestation she had worked in a chemical plant that produced many kinds of fibreglass.

The patient had no abnormalities in the head, eyes, ears, limbs, or any other part of his body. His anterior mandible was narrow and wedge-shaped, while the maxilla was normal in size. Intraoral examination revealed a complete absence of the tongue and there was mucosal thickening in the floor of the mouth. The malocclusion was severe: bilateral buccal crossbite, deep overjet, deep overbite, crowded lower canines, and congenital absence of four mandibular permanent incisors. In addition, the lower alveolar arch had not developed transversely and had left no gap for mandibular incisors, whereas the upper alveolar arch was normal in form ( Fig. 1 A, B).

Fig. 1
Features of the patient: (A) preoperative frontal photograph of the patient showing micrognathia; (B) intraoral photograph showing aglossia and the congenital absence of four mandibular permanent incisors; (C) preoperative CT showing a wedge-shaped mandible and lower tooth arch, and malocclusion; (D) chest radiograph showing situs inversus totalis.

Routine haematological studies, thyroid function tests, and urinalysis were within normal limits. Chromosome analysis was also normal. Chest radiography and abdominal Doppler ultrasound revealed complete situs inversus: dextrocardia, liver on the left, and stomach and spleen on the right. Panoramic radiography and spiral computed tomography (CT) of the facial skeleton showed the wedge-shaped mandible and lower alveolar arch, absence of the mandibular permanent incisors, and other dentofacial deformities as revealed in the physical examination ( Fig. 1 C, D).

The treatment procedures were in compliance with the Declaration of Helsinki and were approved by the Institutional Ethics Committee of West China Hospital of Stomatology. The patient’s guardian also signed an informed consent agreement. MMD was chosen to widen the narrow mandible. To avoid damaging the permanent tooth germs, virtual surgical planning and a three-dimensionally (3D) printed surgical template were utilized to guide the surgery. The procedures of the virtual surgical simulation and the transfer of the virtual surgical design to the operating room using the 3D-printed guiding template were similar to the procedures described in a previous article from the study institution .

Using data from surface scanning of the dental arch (3Shape, Copenhagen, Denmark) and spiral CT, a composite skull model with accurate dentition was constructed. After detailed analysis of the patient’s dentofacial deformity and the distribution of the permanent tooth germs, Dolphin Imaging 11.7 Premium (Dolphin Imaging and Management Solutions, Chatsworth, CA, USA) and Mimics 10.01 (Materialise, Leuven, Belgium) were applied for the virtual surgical design, especially for the location of the osteotomy line ( Fig. 2 A, B). A surgical template designed by the virtual surgical simulation was fabricated by 3D printing. The template consisted of three components: an occlusion plate, a bone attachment on which the osteotomy line was indicated, and a connecting arm ( Fig. 2 C).

Dec 14, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Mandibular symphyseal midline distraction osteogenesis for micrognathia associated with aglossia and situs inversus totalis
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