Biopsy and Dental caries

1. Biopsy and Dental caries

2. Introduction Pathology : Science for studying disease and its etiology. Disease : any deviation in the structure or function of any part of the body.

3. Oral and maxillofacial pathology: is the specialty of dentistry and the discipline of pathology that addresses the nature, identification and management of diseases affecting the oral and maxillofacial regions.

5. Biopsy:is the term used to describe the process of surgi­cally removing tissue from a patient for histopathologic examination. Indication of biopsy: 1.any lesion suspected to be neoplastic& ulcer or lesion (white patches)prolonged more than 3 weeks 2.any tissue surgically removed. 3.any intraosseous lesion can not be diagnosed in radiograph.

6. Types of biopsy: 1.Excisional biopsy:is a therapeutic and diagnostic procedure performed when the lesion is no larger than 1 cm or so in diameter and when its re­moval does not necessitate a major surgical procedure. 2.Incisional biopsy: is indicated if the lesion is too large for an excisional procedure while Punch biopsies are a type of incisional biopsy that may be used on surface oral lesions

7. 3.Fine-needle aspiration: (21 ­gauge – 23 gauge) is inserted into ,a.. tissue or suspected lesion to exam the aspiration if it is pus or clear fluid or keratin or blood or air . 4. Drill biopsy: for bone and other organs Autopsy is a postmortem assessment or examination of a body to determine the cause of death. It is performed by a physician trained in pathology.

8. Dental Caries is a progressive bacterial disease of the hard structure of the teeth, characterized by decalcification of the inorganic substance and destruction of the organic substance of the tooth to form a cavity. 1. Bacterial Causes: as dental caries. 2. Non-bacterial Causes:

9. Mechanical Causes: • Abrasion : particularly at the gingival 1/3 by over vigorous brushing. • Attrition : by the action of opposing teeth.A small amount of attrition occurs with age, but accelerated wear may occur in bruxism . • B. Chemical Causes: • Erosion : usually caused by repeated application of acid. • C. Pathological Resorption.

10. Etiology : • Acidogenic Theory (Miller's Theory : It is the most accepted and supported theory , the acid formed from the fermentation of dietary carbohydrates by oral bacteria leads to decalcification of tooth substance with subsequent disintegration of organic matrix.

11. 2) Proteolytic Theory : This theory suggested that bacteria could penetrate into enamel through lamellae and interprismatic substance. 3) Proteolysis-Chelation Theory: Organic part of the enamel is thought to be attacked first, followed by a chelation process that removes calcium from enamel and dentin without acid.

12. In general, the essential requirements for development of dental caries are: 1. Plaque microorganism. 2. susceptible tooth surface. 3. bacterial substrate. 4. time for process to develop.

13. Etiological variables Factors influencing site attack and rates of progression in dental caries: Factors intrinsic to the tooth 1.Enamel composition 2.Enamel structure 3.Tooth morphology 4.Tooth position

14. Factors extrinsic to the tooth 1.Saliva : ↑ Flow rate , ↑ buffering capacity, availability of calcium and phosphate ions for mineralization, and the presence of antimicrobial agents 2.Diet : the presence of phosphates may reduce the incidence of caries. Increasing the proportion of fat in the diet reduces the cariogenic effect of sugar. 3.Immunity

15. Clinical Classification of Dental Caries According to site of attack, it is classified as follow: A. According to site of attack 1 . Pit and fissure caries. 2. Smooth surface caries. 3.Cemental or root caries. 4 . Recurrent caries.

16. B. Classification by rate of attack 1.Rampant or acute caries: 2.Chronic caries or slowly progressive: 3. Arrested caries:

17. Histopathology of enamel caries: (white-spot lesion)in smooth surface enamel caries is cone-shaped .The shape is modified in pit and fissure caries with base of the cone towards the amelodentinal junction this depend on the direction of enamel prisms. Before destruction of enamel, several zones can be distinguished in ground section.

18. 1.Translucent zone : more porous than normal enamel and contain 1% by volume of spaces In this demineralization has taken place (magnesium and carbonates are dissolved). 2.dark zone: Contain 2-4% by volume of pores ,some remineralization happens due to reprecipitation of minerals lost from translucent zone.

19. 3.Body of the lesion : pore volume of 5 to 25%. 4.Surface zone :remain relatively normal despite subsurface loss of mineral, because it is an area of active reprecipitation of mineral derived both the plaque and from that dissolve from deeper areas of lesion as ions diffuse outwards.

20. Histopathology of dentin caries: 1.Zone of sclerosis: translucent zone is located beneath and at the site of carious lesion and is regarded as a vital reaction of odontoblasts to irritation. 2. Zone of demineralization : the intertubular matrix is mainly affected by acid diffusing from pioneer bacteria

21. 3. Zone of bacterial invasion: The bacteria extend down and multiply within the dentinal tubules. The walls of tubules are softened and distended by proteolytic activity and multiplying bacteria resulting in areas of liquefaction foci parallel to the direction of tubules.

22. 4. Zone of destruction: liquefaction foci enlarge and increase in number. Clefts containing bacteria and necrotic tissue also appear at right angle to dentinal tubules which is called transverse clefts.

23. Protective reactions of dentine and pulp under caries: The reactions in dentine are mainly due to odontoblast activity . They are not specific and may be provoked by other irritants. Reactionary changes in dentine develop significantly under slowly progressing caries by formation tertiary or irregular dentine .