1. DNT 353 Dr. Shahzadi Tayyaba Hashmi

2.  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.  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.  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.  Cariogenic (acidogenic) bacteria  Bacterial plaque  Stagnation areas  Fermentable bacterial substrate(sugar)  Susceptible tooth surfaces  time

6.  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.  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.  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  Biofilm consist of hydrated viscous phase formed from bacteria and their extracellular polysaccharide matrices  Biofilm may be resistant to antimicrobials

10.  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.  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.  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