Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.
Say–Meyer syndrome is a rare X-linked genetic disorder that is mostly characterized as developmental delay. It is one of the rare causes of short stature. It is closely related with trigonocephaly. People with Say–Meyer syndrome have impaired growth, deficits in motor skills development and mental state.
Turricephaly is a type of cephalic disorder where the head appears tall with a small length and width. It is due to premature closure of the coronal suture plus any other suture, like the lambdoid, or it may be used to describe the premature fusion of all sutures. It should be differentiated from Crouzon syndrome. Oxycephaly is a form of turricephaly where the head is cone-shaped, and is the most severe of the craniosynostoses.
Scaphocephaly or sagittal craniosynostosis is a type of cephalic disorder which occurs when there is a premature fusion of the sagittal suture. Premature closure results in limited lateral expansion of the skull, resulting in a characteristic long, narrow head. The skull base is typically spared. The word comes from Ancient Greek σκᾰ́φη (skáphē) 'boat' and κεφαλή (kephalḗ) 'head'.
Trigonocephaly is a congenital condition due to premature fusion of the metopic suture, leading to a triangular forehead. The premature merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion. It may occur as one component of a syndrome together with other abnormalities, or in isolated form. The term is from Ancient Greek trigonon 'triangle' and kephale 'head'.
Hyperdontia is the condition of having supernumerary teeth, or teeth that appear in addition to the regular number of teeth. They can appear in any area of the dental arch and can affect any dental organ. The opposite of hyperdontia is hypodontia, where there is a congenital lack of teeth, which is a condition seen more commonly than hyperdontia. The scientific definition of hyperdontia is "any tooth or odontogenic structure that is formed from tooth germ in excess of usual number for any given region of the dental arch." The additional teeth, which may be few or many, can occur on any place in the dental arch. Their arrangement may be symmetrical or non-symmetrical.
Apert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial arch, the precursor of the maxilla and mandible. Disturbances in the development of the branchial arches in fetal development create lasting and widespread effects.
Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpendicular to the fused suture, it compensates by growing more in the direction parallel to the closed sutures. Sometimes the resulting growth pattern provides the necessary space for the growing brain, but results in an abnormal head shape and abnormal facial features. In cases in which the compensation does not effectively provide enough space for the growing brain, craniosynostosis results in increased intracranial pressure leading possibly to visual impairment, sleeping impairment, eating difficulties, or an impairment of mental development combined with a significant reduction in IQ.
Saethre–Chotzen syndrome (SCS), also known as acrocephalosyndactyly type III, is a rare congenital disorder associated with craniosynostosis. This affects the shape of the head and face, resulting in a cone-shaped head and an asymmetrical face. Individuals with SCS also have droopy eyelids (ptosis), widely spaced eyes (hypertelorism), and minor abnormalities of the hands and feet (syndactyly). Individuals with more severe cases of SCS may have mild to moderate intellectual or learning disabilities. Depending on the level of severity, some individuals with SCS may require some form of medical or surgical intervention. Most individuals with SCS live fairly normal lives, regardless of whether medical treatment is needed or not.
Jackson–Weiss syndrome (JWS) is a genetic disorder characterized by foot abnormalities and the premature fusion of certain bones of the skull (craniosynostosis), which prevents further growth of the skull and affects the shape of the head and face. This genetic disorder can also sometimes cause intellectual disability and crossed eyes. It was characterized in 1976.
Cleidocranial dysostosis (CCD), also called cleidocranial dysplasia, is a birth defect that mostly affects the bones and teeth. The collarbones are typically either poorly developed or absent, which allows the shoulders to be brought close together. The front of the skull often does not close until later, and those affected are often shorter than average. Other symptoms may include a prominent forehead, wide set eyes, abnormal teeth, and a flat nose. Symptoms vary among people; however, intelligence is typically unaffected.
Porencephaly-cerebellar hypoplasia-internal malformations syndrome is a rare autosomal recessive syndrome that mainly affects the central nervous system. It causes cardiac defects, brain anomalies, and craniofacial dysmorphisms. It has been reported in a pair of German siblings of the opposite sex born to consanguineous Turkish parents.
Craniosynostosis, Adelaide type (CRSA) is a syndrome characterized by cone-shaped epiphyses, phalangeal hypoplasia, and carpal bone malsegmentation along with craniosynostosis.
Low anterior hairline is a dysmorphic feature in which the frontal hairline which defines the top and sides of the forehead is unusually low. This can mean that either the distance between the trichion (hairline) and glabella at the midline is more than 2 SD below the mean, or that this distance is apparently (subjectively) decreased.
Flat forehead is a dysmorphic feature in which the surface of the forehead is unusually flat.
Cardiocranial syndrome, Pfeiffer type is a rare multiple disorder syndrome characterized by congenital heart defects, sagittal craniosynostosis, and severe developmental delay. The condition has been reported in less than 10 patients worldwide.
