cariology

1. DNT 353 cariology Dr. Shahzadi Tayyaba Hashmi

2. LEARNING OBJECTIVES • To describe caries process • To describe sites that are vulnerable to caries • List bacterial strains most responsible for caries • Explain importance of carbohydrates exposure to caries

3. INTRODUCTION • The study of dental caries and cariogenesis is known as cariology DENTAL CARIES • also known as tooth decay or a cavity • It is defined as an infection which is bacterial in origin and causes demineralization and destruction of hard tissues of teeth (enamel, dentine and cementum) CARIOGENESIS • The Production of dental caries is termed as cariogenesis

4. ETIOLOGY OF DENTAL CARIES • Dental caries is a multifactorial disease of teeth. • The major factors in the etiology of dental caries are as follows: • Diet • Bacteria • Susceptible tooth surface • Time

5. Essential requirements for development of dental caries • Cariogenic (acidogenic) bacteria • Bacterial plaque • Stagnation areas • Fermentable bacterial substrate(sugar) • Susceptible tooth surfaces • time

6. 1) Essential properties of cariogenic bacteria • Streptococci are essential for development of dental caries • Acidogenic • Able to produce a pH low enough (<5) to decalcify tooth substance • Able to survive and produce acid at low levels of pH • Able to produce polysaccharides (glucans) • It adheres to pellicle and contributes to plaque formation

8. Microbiological aspects of dental caries • Dental caries is a bacterial disease • The organisms mainly responsible are specific strains of Streptococcus mutans • The presence of S.mutans in the human mouth is associated with caries activity • Other bacteria including lactobacilli and other strains of streptococci are weakly cariogenic

9. 2) Bacterial plaque • Plaque is a tenaciously adherent deposit that forms on tooth surfaces • Consist of an organic matrix containing a dense concentration of bacteria • In microbiological terms, plaque is a biofilm • Biofilmconsist of hydrated viscous phase formed from bacteria and their extracellular polysaccharide matrices • Biofilm may be resistant to antimicrobials

10. Clinical appearance of bacterial plaque • Clinically, bacterial plaque is a tenaciously adherent deposit on the teeth • It can only be readily removed by tooth brushing • However no tooth brushing removes plaque from inaccessible areas or pits (stagnation areas) • Plaque becomes visible, particularly on the labial surfaces of incisors, when tooth brushing is stopped for 12-24 hours • Appears as a translucent film

11. DENTAL PLAQUE Appears as translucent film

12. Stages of plaque formation • Deposition of cell-free pellicle of salivary glycoprotein • Further deposition of pellicle enhanced by bacterial action • Colonisation of cell free layer by bacteria, particularly by S.sanguis and S.mutans within 24 hours • Progressive build-up of plaque substance by bacterial polysaccharides

14. 3)Factors determining the cariogenecity of sucrose • Sucrose forms up to a third of the carbohydrate content of many person’s diet • It promotes colonisation of teeth by streptococcus mutans • Its small molecular size allows it to diffuse rapidly into plaque • Its dissacharide bond contains enough energy to react with bacterial enzymes to form extracellular dextran matrix