1984), which combines Deans index and the TF index; and the fluorosis risk index (Pendrys 1990), which is intended to define the time at which fluoride exposure occurs, and relates fluorosis risk with tooth development stage. Deans index
Deans fluorosis index was first published in 1934 by H. Trendley Dean. The index underwent two changes, appearing in its final form in 1942. An individuals fluorosis score is based on the most severe form of fluorosis found on two or more teeth. TF index
Proposed by Thylstrup and Fejerskov in 1978, the TF index represents a logical extension of Deans index, incorporating modern understanding of the underlying pathology of fluorosis. It scores the spectrum of fluorotic changes in enamel from 0 to 9, allowing more precise definition of mild and severe cases. Causes
Dental fluorosis is caused by a higher than normal amount of fluoride ingestion whilst teeth are forming. Primary dentine fluorosis and enamel fluorosis can only happen during tooth formation, so fluoride exposure occurs in childhood. Enamel fluorosis has a white opaque appearance which is due to the surface of the enamel being hypomineralised.The most superficial concern in dental fluorosis is aesthetic changes in the permanent dentition (the adult teeth). The period when these teeth are at highest risk of developing fluorosis is between when the child is born up to 6 years old, though there has been some research which proposes that the most crucial course is during the first 2 years of the childs life.
Cerebro-costo-mandibular syndrome is a very rare genetic disorder which is characterized by jaw/chin, palate and rib abnormalities. Signs and symptoms
The following list comprises the most common symptoms people with this disorder exhibit:
Severe micrognathia
Thorax in the shape of a bell
Cleft palate
Neonatal respiratory difficulties
Rib gapsCommon (but not the most) symptoms include:

External auditory canal atresia
Hearing loss
Failure to thrive
Glossoptosis
Intellectual disabilities
Fetal growth delays
Kyphosis
Short height
TracheomalaciaNot common but also not rare symptoms include:

Fifth finger clinodactyly
Cerebral calcification
Hydranencephaly
Meningocele
Microcephaly
Polycystic kidney dysplasia
Myelomeningocele
Porencephalic cyst
Short, hard palate
Spina bifida
Ventricular septal defect
Webbed neck

Causes
This disorder is caused by autosomal dominant mutations in the SNRPB gene, in chromosome 20. Epidemiology
Only 110 cases have been described in medical literature. == References ==