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Oral and craniofacial disorders
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Hypodontia, or lack of one or a few permanent teeth, is extremely common (5%–10% in most surveys) and is often inherited as a variable autosomal dominant trait. One gene implicated in both syndromic and non-syndromic tooth agenesis is MSX1. Hypodontia may be the only significant finding in female heterozygotes for X-linked hypohidrotic ectodermal dysplasia (see Chapter 18), where incisors may also be peg shaped. Oligodontia and complete anodontia are commonly associated with this disorder in males, but can also occur in other ectodermal dysplasia syndromes, in orofaciodigital (OFD) syndrome type 1 (X-linked dominant) and with iris dysplasia in Rieger syndrome (autosomal dominant). A single central incisor tooth may be associated with midline abnormalities such as holoprosencephaly (e.g. in association with SHH).
Benign Oral and Dental Disease
Published in John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford, Head & Neck Surgery Plastic Surgery, 2018
Konrad S. Staines, Alexander Crighton
Abnormalities of tooth development and eruption may occur either as isolated defects or as part of a wider developmental disorder. Cleft lip and palate is an example of a disorder that may affect both tooth development and eruption. A discussion of other syndromes with associated craniofacial deformity and dental developmental disorders is outwith the scope of this chapter and is discussed in Volume 2, Chapter 6, The child with a syndrome. The effect of trauma may range from root dilaceration of a developing tooth or temporomandibular joint (TMJ) injury. Commonly the last tooth in each dental series may be missing or malformed, more commonly in the adult rather than the primary dentition. This is most often seen by the absence of the third molar tooth, followed by the lateral incisor and finally the second premolar. Multiple missing teeth is termed ‘hypodontia’ and requires a specialist assessment to plan for a functioning adult dentition. The commonest malformed tooth visible is the upper lateral incisor which is termed a ‘peg’ lateral incisor (Figure 42.4). Adhesive dental restorations, orthodontic tooth movement and dental implants have radically changed the outlook for patients with dental anomalies.
Whitening for Patients Younger Than 18
Published in Linda Greenwall, Tooth Whitening Techniques, 2017
Hypodontia, missing teeth, or teeth that are malformed on eruption—for example, saucer-shaped defects, ridges, and pitted and mottled teeth.Incisor discrepancies—a difference in the diameter of the central and lateral incisor teeth. The lateral incisors can often be peg shaped, so the esthetics become more of an issue.
Testing the London atlas for age estimation in Thai population
Published in Acta Odontologica Scandinavica, 2020
Wanwisah Namwong, Scheila Mânica
Ethical approval was granted from the Ethic Review Committee for Human research, Police General Hospital, Bangkok, Thailand (COA no. 94/2016). The London atlas for age estimation was tested in 111 digital panoramic radiographs from the General Police Hospital, Bangkok, Thailand. The sample was composed of children (57 ♂ and 54 ♀) aged between 4.00 and 15.99 years. The CA of each subject was calculated by subtracting the date of birth from the date of radiographic examination. Inclusion criteria included good quality panoramic radiographs of healthy children with no medical history of systemic diseases/disorders. Children who presented hypodontia, hyperdontia, gross pathology and previous orthodontic treatment or severe malocclusion were excluded. The distribution between female and male was almost equal in order to avoid age mimicry as seen in Table 1. The radiographs were assessed by the main author using the sex-specific application software to determine the developmental and eruption stages of all teeth in the left side, both upper and lower jaws, according to AlQahtani et al. [8].
Hypodontia and retention of third molars in Norwegian medieval skeletons: dental radiography in osteoarchaeology
Published in Acta Odontologica Scandinavica, 2019
Christina Heuck Henriksson, Maud Els-Marie Andersson, Anne Møystad
Hypodontia, a collective term for congenitally absent teeth, is the most common craniofacial developmental anomaly in humans [12–15]. In modern Scandinavian populations, third molar hypodontia is about 23–25% [16,17]. It is generally accepted that hypodontia is a multifactorial condition. Various genetic and environmental factors that vary in different populations over time, possibly due to differences in ethnic background and gender, have been implicated in the aetiology of hypodontia [13,14,18,19]. Genetic studies in mice suggest that hypodontia represents a complex multifactorial trait influenced by gene function, environmental interaction and developmental timing [14,20].
Dental and dentoalveolar dimensions in individuals with osteogenesis imperfecta
Published in Acta Odontologica Scandinavica, 2021
Janna Waltimo-Sirén, Henri Tuurala, Ella Säämäki, Petteri Holst, Marjut Evälahti, Heidi Arponen
Genetic defects, such as OI, that are associated with disturbance of mesenchymal matrix deposition can be speculated to also affect tooth morphogenesis, which is regulated by reciprocal interaction between dental epithelium and the underlying tooth mesenchyme. Dentine is of ectomesenchymal origin and rich in type I collagen. During tooth morphogenesis, formation of a layer of type I collagen-containing predentin precludes final differentiation of epithelium-derived ameloblasts and deposition of enamel. Disturbances in tooth morphogenesis due to mutations in several regulatory signalling genes are known to cause hypodontia and oligodontia, but quantitative factors may also be involved [20]. In OI patients with the DI phenotype, the abnormal dentine displays significantly less than normal dentinal tubules with varying shape and size [2,21,22]. DI is present in approximately one fourth of OI patients [15,16]. However, normally coloured teeth and absence of radiographic signs of DI do not necessarily indicate absence of dentine anomalies [4,22,23]. Individuals with OI have twice as many missing teeth as the general population [14]. Tooth agenesis has been noted to be slightly more common in OI patients with a mutation leading to qualitative defect in collagen type I and the severe disorder type than in those with quantitative mutations [24]. Presence of dentine abnormality has been shown to increase the risk of hypodontia in individuals with OI [21], and the diminished amount or structural abnormality of predentin might have an effect on tooth size [2,22]. This study supports evidence from a previous observation reporting smaller than normal tooth size in several teeth of patients with OI [25]. The exact mechanism of hypodontia in OI is thus far unknown, but the diminished tooth size and hypodontia may be of shared aetiology as in population in general [26].