The under maturation of the enamel causes the tooth structure to be softer, and more susceptible to the effects of bruxism due to abnormalities in skeletal development. The oral abnormalities are evaluated by radiographs and visual examination. Oral radiographs are frequently repeated due to the high incidence of infection due to abnormal biting patterns seen in TDO cases. Cause
TDO is caused by autosomal dominant mutations in the DLX gene family. Known mutations include a 4-basepair deletion in exon 3 of DLX3 on chromosome 17q21, causing a frameshift mutation. Pathogenesis
DLX3 plays numerous significant roles during osseous, connective tissue, and dermal cell differentiation. It is expressed in the placenta and is important for embryonic development of hard bone tissue in the teeth, skull, and long bones such as in the arms and legs. During normal tooth development, DLX3 is predominantly expressed in the inner tooth enamel epithelium. In TDO cases, DLX3 is expressed in the outer enamel epithelium and leads to the abnormally thin enamel observed in the disease, which leads to tooth attrition and is most often the cause of dental abscess seen in TDO persons. DLX3 in TDO is also responsible for upper cranial thickness, calvaria, osteosclerosis of the long bones, long narrow head (dolichocephaly), abnormally thin brittle nails, and premature closing of fibrous joints. Consequently, 95% of people with TDO that are 16 years old or younger show skeletal abnormalities before full maturation takes place.Lack of mastoid pneumatization by mastoid cells occurs in 82% of the cases and is rarely prevalent outside of TDO diagnosis.
The involvement of the orbitofrontal cortex and dorsolateral prefrontal cortex in OCD is shared with bipolar disorder, and may explain the high degree of comorbidity. Decreased volumes of the dorsolateral prefrontal cortex related to executive function has also been observed in OCD.People with OCD evince increased grey matter volumes in bilateral lenticular nuclei, extending to the caudate nuclei, with decreased grey matter volumes in bilateral dorsal medial frontal/anterior cingulate gyri. These findings contrast with those in people with other anxiety disorders, who evince decreased (rather than increased) grey matter volumes in bilateral lenticular/caudate nuclei, as well as decreased grey matter volumes in bilateral dorsal medial frontal/anterior cingulate gyri. Increased white matter volume and decreased fractional anisotropy in anterior midline tracts has been observed in OCD, possibly indicating increased fiber crossings. Cognitive models
Generally, two categories of models for OCD have been postulated. The first category involves deficits in executive dysfunction and is based on the observed structural and functional abnormalities in the dlPFC, striatum and thalamus. The second category involves dysfunctional modulatory control and primarily relies on observed functional and structural differences in the ACC, mPFC, and OFC.One proposed model suggests that dysfunction in the OFC leads to improper valuation of behaviors and decreased behavioral control, while the observed alterations in amygdala activations leads to exaggerated fears and representations of negative stimuli.Due to the heterogeneity of OCD symptoms, studies differentiating various symptoms have been performed.