ORAL HISTOLOGY ASSIGNMENT

1. ORAL HISTOLOGY ASSIGNMENT Submitted By; Derimol Denny Roll no: 19

2. Developmental disturbances means an abnormality where the pathology starts in the embryonic stage of human life, before the formation of the dentition. • Developmental disturbances in teeth are of 5 types based on the feature of the tooth they affect: • Size of Teeth • Shape of Teeth • Number of Teeth • Structure of Teeth • Growth (Eruption) of Teeth • Here we discussing about developmental disturbances by structure of teeth.

3. AFFECTING THE STRUCTURE AmelogenesisImperfecta Environmental Enamel Hypoplasia DentinogenesisImperfecta Dentin Dysplasia Regional Odontodysplasia Dentin Hypocalcification

4. AMELOGENESIS IMPERFECTA Amelogenesisimperfecta presents with abnormal formation of the enamel[1] or external layer of teeth. Enamel is composed mostly of mineral, that is formed and regulated by the proteins in it. Amelogenesisimperfecta is due to the malfunction of the proteins in the enamel: ameloblastin, enamelin, tuftelin and amelogenin. People afflicted with amelogenesisimperfecta have teeth with abnormal color: yellow, brown or grey. The teeth have a higher risk for dental cavities and are hypersensitive to temperature changes. This disorder can afflict any number of teeth. Amelogenesisimperfecta can have different inheritance patterns depending on the gene that is altered. Most cases are caused by mutations in the ENAM gene and are inherited in an autosomal dominant pattern. This type of inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder. Amelogenesisimperfecta is also inherited in an autosomal recessive pattern; this form of the disorder can result from mutations in the ENAM or MMP20 gene. Autosomal recessive inheritance means two copies of the gene in each cell are altered.

5. General Information • Classification can be impractical for clinicians • Problems arise in one or more of the three stages of enamel formation – Elaboration of enamel matrix; hypoplastic – Mineralization; hypocalcified – Maturation; hypomaturation

6. General Information • Absence of systemic disorder • Can be part of a syndrome • Many types • Different modes of inheritance • Different phenotypes in a single family • Same phenotype with different gene mutations • Homozygotes differ from heterozygotes • 1:800 – 1:15,000 (clustering) • Both dentitions

7. Genes and Phenotypes • AMELX (amelogenin) – X-linked – Diffuse smooth hypoplastic and hypomaturation • ENAM (enamelin) – AD, AR – Generalized pitting and thin enamel • MMP-20 (enamelysin) – AR pigmented hypomaturation • KLK4 (kallikrein-4) – hypomaturation • DLX3 (genes of craniofacial development) – Hypoplastic/hypomaturation and taurodontism • AMBN (ameloblastin) – Indication for strong association

8. Hypoplastic type • Inadequate deposition of organic matrix • Normal mineralization • Radiographic contrast • Seven types

9. Treatment X-ray showing lack of enamel opacity and a pathological loss of enamel in patient with amelogenesisimperfecta Crowns are sometimes being used to compensate for the soft enamel.Usually stainless steel crowns are used in children which may be replaced by porcelain once they reach adulthood. In the worst case scenario, the teeth may have to be extracted and implants or dentures are required.

11. Dentinogenesisimperfecta Dentinogenesisimperfecta (hereditary Opalescent Dentin) is a genetic disorder of tooth development. This condition causes teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent. Teeth are also weaker than normal, making them prone to rapid wear, breakage, and loss. These problems can affect both primary (baby) teeth and permanent teeth. This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Dentinogenesisimperfecta affects an estimated 1 in 6,000 to 8,000 people.

12. Types: Types of dentinogenesisimperfecta with similar dental formalities usually an autosomal dominant trait with variable expressivity but can be recessive if the associated osteogenesisimperfecta is of recessive type. This is type l. Type II : Occurs in people without other inherited disorders (i.e. Osteogenesisimperfecta).It is an autosomal dominant trait. A few families with type II have progressive hearing loss in addition to dental abnormalities. Mutations in the DSPPgene have been identified in people with type II and type III dentinogenesisimperfecta. Type I occurs as part of osteogenesisimperfecta.

14. Dentinogenesisimperfecta type I Dentinogenesisimperfecta type I Individuals with DGI-I also have osteogenesisimperfecta. The teeth of both dentitions are typically amber and translucent and show significant attrition. Radiographically, the teeth have short, constricted roots and dentine hypertrophy leading to pulpal obliteration either before or just after eruption. Expressivity is variable even within an individual, with some teeth showing total pulpal obliteration while in others the dentine appears normal.

15. Dentinogenesisimperfecta type II The dental features of DGI-II are similar to those of DGI-I but penetrance is virtually complete and osteogenesisimperfecta is not a feature. Bulbous crowns are a typical feature with marked cervical constriction. Normal teeth are never found in DGI-II. Sensorineural hearing loss has also been reported as a rare feature of the condition [5].

16. Dentinogenesisimperfecta type III This is a form of DGI found in a tri-racial population from Maryland and Washington DC known as the Brandywine isolate. The clinical features are variable and resemble those seen in DGI-I and -II but the primary teeth show multiple pulp exposures and radiographically, they often manifest "shell" teeth i.e. teeth which appear hollow due to hypotrophy of the dentine.

18. THANK YOU