Abnormal tooth development refers to abnormal number of teeth, abnormal tooth morphology, abnormal tooth structure, abnormal tooth eruption and abscission. The common clinical tooth morphological abnormalities of
include: abnormal cusp, abnormal socket, too small teeth, oversized teeth, double tooth deformity and pulp cavity abnormality, etc Spherical tooth is a rare tooth morphological abnormality. In 1969, denes and csiba first found this kind of tooth dysplasia in a mother and her son. In 1971, Toledo et al. Discovered three new cases from Brazil and pointed out that it may be related to heredity, but these two authors did not mention the relationship with deafness
In 1972, Levin and Jorgenson found that spherical teeth were often associated with high frequency sensorineural hearing loss in a family. They were named as familial odontodontal dysplasia, and later changed to otodontal dysplasia In 1976, Witkop et al. Formally named the inflated balloon like tooth as globodontia, and proposed to name the spherical tooth with high frequency sensorineural hearing loss as otodental syndrome (ODS).
this paper reviews the clinical features, diagnosis, treatment and pathogenesis of otodontia, and discusses the future research direction of this kind of tooth dysplasia
Epidemiology of otodontic syndrome
OtodentalsyndromeODSMIM166750 is a rare autosomal dominant disease. Many cases have family history, and occasionally sporadic cases, incidence rate is less than 1/1000000.
So far, only a dozen families and sporadic cases have been reported, respectively from Hungary, the United Kingdom, Brazil, Ireland, Poland, Australia, Italy, Belgium, Turkey, South Korea and China. It can be inferred that there is no regional or ethnic difference in the incidence of ODS.
so far, only two cases have been reported in China, and no Chinese literature has been found
Clinical manifestations of otodontic syndrome
The main clinical manifestations of ods are typical giant spherical teeth with abnormal morphology, mostly involving canines and molars (both deciduous and permanent dentition), accompanied by high frequency sensorineural hearing loss, and some patients with ocular defects
Oral and maxillofacial manifestations: tooth phenotype is the most typical clinical manifestation of ODS, which has important diagnostic significance.
is described in detail from the following aspects: tooth shape and size, tooth eruption and shedding, number of teeth, tooth structure, root development, occlusal relationship, facial morphology, histopathology, etc
(1) Shape and size of teeth: globodontia is the most typical and diagnostic tooth manifestation of ODS, involving canines and molars, deciduous dentition and permanent dentition can occur, usually the deciduous dentition is more serious Deciduous canines are usually spherical, with a prominent lingual protuberance, which is significantly larger than normal. Therefore, it is difficult to distinguish between deciduous canines and permanent canines according to their size and shape. Inherited permanent canines are spherical, significantly larger than normal, but sometimes they are normal in size and shape
The deciduous molars are obviously larger than normal, and consist of many protruding lobules with abnormal spherical shape. The development groove and pit are indistinct, the boundary between the tooth tip and the development groove disappears, and the development groove spreads from the center of the occlusal surface to the surrounding area. Some primary molars look like pumpkins, some have a cone-shaped cusp protruding to the occlusal surface in the center of the spherical cusp, and some of the primary molars are composed of several cusps
some authors believe that the giant primary molars are formed by the fusion of deciduous molars and premolar germs, which is based on the fact that most of these patients are associated with the loss of the corresponding premolars
The crown of
premolars is spherical, with round cusps and protruding occlusal surface. The premolars may also be in normal shape but smaller than normal teeth The size and shape of incisors were normal in primary dentition and permanent dentition. Only a few cases reported that the permanent incisors were conical and smaller than normal
(2) Eruption and exfoliation of teeth: eruption time of deciduous canines and deciduous molars was delayed by 1-3 years. Some patients often went to see a doctor because the deciduous canines or primary molars did not erupt at the age of 3 years. The eruption time of permanent dentition was obviously delayed, especially in lateral teeth group. If the premolars were congenital missing, the primary molars could stay. The shedding time of
deciduous molars was later than normal
(3) teeth: congenital premolars missing. Levin and other 29 cases of ear tooth syndrome, 14 cases of premolars missing, 34 missing premolars missing, which is significantly higher than the proportion of 3-5% incidence rate of congenital absence in normal population.
Liu and so on reported a case of congenital lacteal incisor.
anterior teeth area supernumerary teeth and small teeth were also reported in the literature.
Mixed odontoma in the upper and lower deciduous molars was also reported. In one case, the facial swelling and fistula were caused by the tumor, and the swelling disappeared after the removal of the tumor
(4) Tooth structure: yellowish white enamel dysplasia is very common in canine buccal surface near gingiva. Enamel dysplasia is also reported in the buccal surface of
deciduous molars and molars. Therefore, the patients with ods are prone to caries. Some authors also believe that the incisors of patients with ods are not completely normal, and the incisors also have enamel development defects
(5) gums: due to bad shape of teeth, poor oral hygiene, accumulation of dental plaque, gingival hyperplasia and gingival swelling are common.
(6) dental arch development and occlusion: most of the ODS patients had normal dental arch development, which showed class I relationship. However, because the deciduous molars and deciduous canines were significantly larger than the normal teeth, dentition crowding was more common; Some anterior teeth open and some angle class Ⅲ malocclusion
Face shape: most of the patients have symmetrical bilateral faces and moderate facial proportion.
, however, some patients have a long face, with nostrils forward, middle length, full buccal like mouth full of food, and tension of orbicularis oris and genitalia muscles when closing lips
(8) X-ray examination: the pulp cavity of the molar area was obviously enlarged, showing double pulp cavity or three pulp cavity. The root was short and the pulp stone was often found in the root canal and pulp cavity. The second was the loss of premolar germ and the smaller than normal morphology of premolar. The first permanent molar impaction and anterior tooth impaction were also often found Some authors found that the enamel thickness of anterior teeth was normal, but the thickness of enamel in molar area was half of that in normal tooth tissue Some authors examined the internal structure of extracted deciduous molars with micro CT. It was found that the dentin of the tooth fused with each other, and the enamel at the apical development groove was poorly developed. The cross-section showed that the thickness of the enamel increased significantly. In the fusion area, part of the enamel protruded into the dentin with irregular calcification, and there were multiple pulp stones in the root canal The root canal system was complex, and the main root canal was fused with two extra teeth
(9) Histopathology: Beck mannagetta et al. Carried out histological examination on the extracted teeth of ODS patients, and found that the enamel and dentin structure were normal, and small tooth like pulp stones were found in the pulp cavity.
Enright et al. Made extracted teeth into grinding slices and found that the crown was spherical, huge pulp cavity, abnormal root morphology, enamel and dentin structure were normal Liu et al. Found that the dentin of the three tooth like structures of the left upper first primary molar fused together. There were pulpstones in the pulp cavity and necrotic tissue in the pulp cavity. The necrotic tissue was outside the main root canal system. Odontoblast cells were high columnar and had a lot of liquefaction changes
2.2 ear manifestations: sensorineural hearing loss is a typical clinical manifestation of ODS patients. It often shows that the hearing of all frequencies is decreased at 65dB, especially when the frequency is above 1000Hz. The onset age of
deafness varies from infancy to middle age.
In general, deafness is bilateral and progressive, but it usually reaches the plateau stage around 35-40 years old, and the deafness does not continue to progress. The influence of language development of
is relatively slight, and some patients have a history of repeated inflammation and suppuration of the middle ear
2.3 ocular manifestations: complicated with ocular tissue defect (oods), also known as oculo oto dental syndrome (oods) At present, only one family had ocular symptoms, including iris transmission defect, choroidal defect, iris defect, iris and choroidal defect, optic nerve papilla defect, iris and lens defect, cornea, microphthalmos, etc
3. Diagnosis, differential diagnosis, treatment and management of otodontic syndrome
The main points of diagnosis are as follows: (1) the tooth phenotype itself has diagnostic significance, and the clinical manifestations are as mentioned above.
② sensorineural hearing loss above 1000Hz.
③ some patients have eye defects
3.2 differential diagnosis: there are more than 200 kinds of hereditary diseases involving hearing loss and tooth development deformity.
ODS is mainly distinguished from the following diseases: ① sensorineural hearing loss, vertigo and oligodontia, mainly manifested in the loss of permanent anterior teeth ② Bilateral sensorineural hearing loss and multiple anterior teeth were invaginated and fused. The anterior teeth tended to be molars. The lower anterior teeth, canines and the first premolars all had multiple cusps ③ Sensorineural hearing loss combined with eye face heart tooth syndrome is characterized by hypoplasia of middle face, nasal tip cleft in two, upper palate narrow and high arch or cleft palate, delayed eruption of teeth, few teeth, retention of deciduous teeth, etc ⑤ Lamm syndrome, which is sensorineural hearing loss with microtia and denticulation, is similar to ODS. It is mainly caused by the mutation of fibroblast growth factor 3 (FGF3).
3.3 treatment and management: the treatment of ODS is more complex and challenging.
part of ODS patients suffer from enamel dysplasia, irregular tooth shape, poor oral hygiene, and easy caries. Therefore, regular inspection, oral health guidance and regular local fluoride application are particularly important However, due to the complexity of the root canal system, endodontic treatment is very difficult.
mesaros et al. Demonstrated the complexity of root canal therapy for a spherical tooth, and pointed out that the prognosis may be poor. Due to the particularity of tooth morphology, pulp periodontal joint lesions are also common Third, multidisciplinary treatment, such as planned tooth extraction, orthodontic treatment, denture repair and so on, is very necessary for ODS patients.
in addition, regular hearing examination, if you need to wear hearing aids as soon as possible, will help children’s language development, the establishment of self-confidence
4. The etiology, genetic research status and future research direction of otodontic syndrome
ODS is a rare autosomal dominant hereditary disease with a certain diversity of clinical phenotypes. Most tooth phenotypes are associated with sensorineural hearing loss, some have only tooth phenotype, and some have only deafness symptoms Levin et al. Comprehensively analyzed a family from Italy. Among the 119 members in six generations, 33 patients with ODS had typical spherical tooth phenotype combined with deafness, 2 patients only showed spherical teeth without hearing loss, and 1 patient less than 2 years old only showed spherical teeth without hearing loss. However, deafness may also appear with age increase, and only 4 patients had typical spherical tooth phenotype with deafness It can be seen that the clinical phenotype of ODS has a certain diversity. Chi square test showed that the genetic mode of ODS was autosomal dominant inheritance
Santos Pinto et al. Described a pedigree of ODS from Brazil, and made follow-up observation on the proband, her son and daughter, and confirmed the genetic mode and genetic phenotype diversity of autosomal dominant inheritance. The mother was not deaf, the son was deaf at puberty, and the daughter was deaf since childhood Genetic research is an effective means for us to understand genetic diseases. The etiology and pathogenesis of ods are very limited. In 2002, Vieira et al. Carried out genetic analysis on an oods family with eye defects from the United Kingdom, trying to locate the candidate gene of the disease. The results showed that the pathogenesis of oods may be related to chromosome 20q13.1
In 2007, Gregory Evans et al. Made a genetic study on three different families with otodontic syndrome, including the family studied by Vieira in 2002. It was found that the microdeletion of chromosome 11q13 containing fibroblast growth factor 3 (FGF3) may be related to the pathogenesis of ODS. Insufficient haploid dose of FGF3 may be the cause of the pathogenesis of ODS, while insufficient haploid dose of Fas related death domain protein (FADD) and eye defects Therefore, ODS is also known as chromosomal 11q13 deletion syndrome In 2016, Kim et al. Conducted a study on a female infant with growth retardation and delayed tooth eruption, but no deafness was detected. It was found that there was a 2.75mb deletion in the region of chromosome 11q13.2-q13.3, including FGF3 gene. Considering the difference in the onset age of deafness, the author speculated that the patient might have deafness in the later stage, and considered that the microdeletion of chromosome 11q13 was the cause of the girl’s disease
In 2017, Liu et al. Found that the pathogenic gene FGF3 did not amplify in a girl with ODS. Therefore, it is speculated that insufficient haploid dose of FGF3 may be the cause of the disease Fibroblast growth factor (FGF) gene family is composed of at least 22 ligand coding genes. It plays an important regulatory role in the formation of many organs, such as limbs, midbrain, pituitary gland, hair and skin. The morphological formation and cell differentiation of
teeth are formed by the interaction between oral epithelial cells and neural crest derived ectodermal mesenchymal cells
Niswander et al. For the first time discovered the limited expression of Fgf4 on the glandular nodules (the regulating center of tooth morphogenesis) at the cap stage of tooth development, which opened the prelude to the study of the relationship between FGF family and tooth development. Subsequently, the relationships between Fgf4, Fgf8, fgg9, FGF3, FGF10, FGF7 and tooth development were successively discovered In the study of mice, FGF3 was found to be an important regulator of epithelial cell differentiation during tooth morphogenesis Cherles et al. Found that all the research samples of FGF3 gene mutation mice have similar tooth phenotype. FGF3 gene expression regulates molar morphology by controlling the size of teeth, adjusting the number and position of the cusps and the relationship between them The dose of FGF3 plays an important role in the development and evolution of mammalian teeth At the same time, FGF3 also plays a very important role in the development and formation of the inner ear. Some people think that FGF3 can induce the formation of auricular vesicles, while others think that FGF3 is not necessarily necessary to induce the formation of ear vesicles, but it is a necessary regulatory factor in the process of further differentiation and formation of inner ear fine structure
At present, it has been found that FGF3 gene mutation can cause Lamm syndrome, with clinical manifestations of complete labyrinthine dysplasia, small ears and small teeth.
FGF3 and Fgf4 gene microduplication may be associated with odontoma dysphagia syndrome. Phenotypes include tooth dysplasia, oligodontia, jaw dysplasia, odontoma, dysphagia and esophageal stenosis Some studies have also found that FGF3 and Fgf4 gene microduplication is associated with premature closure of cranial suture It can be seen that the different pathological types of FGF3 gene are completely different: tooth phenotype, ear phenotype and other organ phenotypes caused by mutation, haploid dose deficiency, microduplication. Therefore, for dental medical workers, how to accurately regulate tooth development and differentiation, tooth morphology, tooth eruption and shedding will be our future research direction
To sum up, this paper reviews the clinical features, diagnosis, treatment, pathogenesis and future research direction of otodontics syndrome, which is a rare tooth morphological abnormality. It is hoped that it will be helpful for dentists, especially children dentists, to understand this kind of abnormal tooth development
Source: Su Jimei, Xia Bin. Otodontic syndrome [J]. Journal of Modern Stomatology, 2019,33 (03): 175-178