03 DISORDERS OF DEVELOPMENT OF TEETH AND CRANIOFACIAL ANOMALIES.pptx

range of congenital and acquired conditions affecting the formation, structure, and function of teeth and the craniofacial region. These disorders include enamel and dentin defects like amelogenesis imperfecta and dentinogenesis imperfecta, tooth number anomalies

1. Disturbances in structure of dentine Dr Asma begum Lecturer Oral Pathology

2. DENTINOGENESIS IMPERFECTA (hereditary opalescent dentine) Type I associated with osteogenesis imperfecta Type II commonest, only the teeth are affected Type III only occurs in a rare racial isolate in the USA

3. Dentinogenesis imperfecta type II Autosomal dominant disorder The most common dental genetic disease Both the deciduous and permanent dentitions are affected On eruption the teeth have a normal contour, but an opalescent amber-like appearance

4. They may have an almost normal colour , following which they become translucent , and finally grey or brownish with bluish reflections from the enamel In most cases the enamel is structurally normal, but it is rapidly lost and the teeth then show marked attrition

5. Radiological examination shows short, blunt roots with partial or even total obliteration of the pulp chambers and root canals by dentine

6. Histological examination shows: Apart from a thin layer of normal tubular mantle dentine (the dentine immediately adjacent to the enamel/ cementum ), the dentine contains a reduced number of tubules, many of which are wide and irregular Areas of atubular dentine may be present

7. This abnormal dentine partly or totally obliterates the pulp chamber and root canal Vascular inclusions are often found in the dentine, representing remnants of odontoblasts and pulp tissue

8. There’s an increased water content and a decreased mineral content when compared with normal dentine The microhardness of the dentine is low, explaining the rapid attrition of the teeth which occurs following loss of enamel

9. Caries is unusual in affected teeth Shell-teeth: the pulp cavities in deciduous teeth may not be obliterated, the dentine may remain thin and the pulps may become exposed by attrition

10. Dentinogenesis imperfecta type I Associated with osteogenesis imperfecta Genetically distinct from dentinogenesis type II Primary dentition more severely affected than permanent Appearances in the primary dentition as for type II

11. Dentinogenesis imperfecta type III occurs in a particular racial isolate group in southern Maryland, USA (the Brandywine isolate) Genetic studies have shown that type III overlaps with the same region on chromosome 4 as type II

12. DENTINAL DYSPLASIA Rare autosomal dominant disease Type I (rootless teeth): Permanent teeth have normal crowns associated with roots composed of dysplastic dentine, containing numerous calcified, spherical bodies The pulp chamber and root canals are largely obliterated and the roots are usually very stunted The abnormality is due to a defect in Hertwig's root sheath that induces formation of fused globular masses of abnormal dentine The first sign may be premature exfoliation either spontaneously or with minor trauma

13. Type II dentinal dysplasia (coronal dentine dysplasia): May not be a distinct entity Linked to the same area on chromosome 4 as dentinogenesis imperfecta type II The appearances in the primary dentition are the same but the permanent teeth are of normal colour and root length

14. The end…..