Patterns of tooth agenesis in patients with Down syndrome in relation to hypothyroidism and congenital heart disease: An aid for treatment planning

Prevalence and patterns of permanent tooth agenesis in Down syndrome and their association with craniofacial morphology

“…A recent report described that trigeminal nerve fiber growth and patterning are integrated with tooth morphogenesis, and the report hypothesized that mesenchymal dental follicles fail to form as a result of inadequate local epithelial-mesenchymal interactions due to thyroid deficiency, causing delayed proliferation of nerve cells and decreased rate of neuron production in DS. 21 Another reason described earlier implicates poor terminal vascularization of developing tooth buds, causing complete or partial odontoblast degeneration. 18 Prevalence rates of agenesis of one or more third molar in the nonsyndromic population have been reported to be between 9% 39 and 30.8% 40 in North America, while the prevalence of simultaneous agenesis of all third molars is much lower, ranging from 0.50% 39 to 2.3%.…”

“…Most studies report that mandibular second premolars, maxillary lateral incisors, maxillary second premolars, and mandibular central incisors are the teeth most often affected (in decreasing order). 35 In DS, the prevalence of hypodontia is much greater and more severe [12][13][14][15][16][17][18][19][20][21][22] and is recognized as a characteristic phenotypical feature of the syndrome.…”

“…Similarly, measurements of subjects exhibiting absence of all third molars were compared with those without this presentation. Since dental agenesis is frequently observed in both jaws in DS, [12][13][14][15][16][17][18][19][20][21][22] ANCOVA tests were additionally adjusted for the proportion of other missing teeth (vs in the regions of interest) in the total number of missing teeth. Statistical tests were conducted using SAS (version 9.1; SAS Institute Inc, Cary, NC).…”

“…2 Cephalometric analyses of subjects with DS have described platybasia, reduced maxillary and mandibular alveolar heights, short teeth, reduced maxillary and mandibular dimensions, and forward rotation of the maxillary and mandibular planes, which collectively lead to overclosure and relative mandibular prognathism. [3][4][5][6][7][8][9][10][11][12] Hypodontia in DS is well known, [12][13][14][15][16][17][18][19][20][21][22] with prevalence documented at about 90% 12,19,20 if the third molars are considered and between 30% 13 and 60% 22 when the third molars are not considered in the analysis. A very high prevalence of total agenesis of all third molars has also been described.…”

Orthodontic treatment considerations in Down syndrome patients

“…Congenital heart disease and hypothyroidism are parameters involved in tooth agenesis. 16 The incidence of canine impaction is ten times higher than normal individual. 17 Delayed eruption of teeth is often occured, with an abnormal sequence.…”