DNT 353

CARIOLOGYDr. Shahzadi Tayyaba Hashmi

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

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

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

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

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

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

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 Biofilm consist of hydrated viscous phase

formed from bacteria and their extracellular polysaccharide matrices

Biofilm may be resistant to antimicrobials

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

DENTAL PLAQUE

Appears as translucent film

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

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