Significance of oral health in persons with Down syndrome: a literature review

Abstract

Down syndrome (DS) is an autosomal chromosomal anom-aly resulting from trisomy of all or a critical part of chromo-some 21. It affects approximately 1 in 700 to 800 live births. Despite the development of prenatal diagnosis, the inci-dence of DS births is predicted to remain static or even to increase over the next decade, partly due to increased mater-nal age in Western societies 1–3 . Many of the medical and phys-iological characteristics of DS have direct consequences for the oral health of subjects affected and indirect conse-quences for the quality of life of persons with DS and their carers. This article aims to give an overview of the current lit-erature concerning the orofacial problems confronting patients with DS, and to explain the different treatment modalities available. Anatomical considerations The different anatomical aspects of DS have been well described 4 and form the basis of the orofacial problems experienced by this population. The principal skeletal cran-iofacial features include brachycephaly with a flattened occiput and decreased length and flattening of the cranial base 5–9 . The facial mid-third is underdeveloped, producing a hypoplastic maxilla with a high, short, and narrow palate 10 . The frontal and paranasal sinuses 11 are hypoplastic and the ethmoid bone is retracted 7 . Mandibular prognathism is mild or marked relative to the maxilla 8 . Soft-tissue features include a fissured and protrusive tongue that often rests between the dental arches and high against the palate 12 . The tongue appears macroglossic due to the relatively small size of the oral cavity (relative macroglos-sia 13). The tonsils and adenoids are enlarged 14 . Dental anomalies noted include structure (taurodontia, decreased root to crown ratio, decreased tooth size, altered crown shape) 15 , number (hypodontia or partial anodontia, frequently 7s and 8s), eruption (delayed or abnormal sequence of eruption) 16,17 , and position (protrusion of the lower incisors) 18 . There is often a 'pseudo Class-III malocclu-sion' 7 or maxillary endognathism with an anterior open bite due to abnormal tongue position 19 . Facial appearance is altered with short palpebral fissures, hypertelorism, a wide nasal root, a narrow soft nose with a high nasal tip, a high upper lip, and wide short low ears 8 . The muscles of mastication and facial expression are hypotonic 14,20 and there may be laxity of the temporo-mandibular joint ligaments 21 . These classically described features vary significantly between individuals despite the widely recognized typical facies of DS.