1. Summary of Lecture # 1 September 19, 2007 Abdullah S. Al-Swuailem BDS, MS, MPH, Dr PH

2. Preventive Dentistry Why Prevention? Why Prevention? Definition of Health. Definition of Health. Types of Prevention Types of Prevention Remedies if prevention fails Remedies if prevention fails Categories of oral diseases Categories of oral diseases

3. Strategies to prevent plaque diseases: Strategies to prevent plaque diseases: Dental caries and periodontal disease are caused by bacteria and hence are considered infectious diseases. Dental caries and periodontal disease are caused by bacteria and hence are considered infectious diseases. Virulent bacteria in sufficient number can cause disease in susceptible individuals. Virulent bacteria in sufficient number can cause disease in susceptible individuals. Dental plaque Composition : Dental plaque Composition : salivary components ( proteins) + bacteria + end products of bacterial metabolism. salivary components ( proteins) + bacteria + end products of bacterial metabolism.

4. Primary Prevention in Dentistry HostBacteria Diet Caries Time

5. - Fluoride - Sugar and diet - Pit and fissure sealants - Public education Primary Prevention in Dentistry

6. Read the summary of the Surgeon General Report on “Oral Health in America” p-2 in primary Preventive Dentistry by N. Harris Read the summary of the Surgeon General Report on “Oral Health in America” p-2 in primary Preventive Dentistry by N. Harris Demineralization and remineralization phases of dental caries Demineralization and remineralization phases of dental caries

7. Bacterial Plaque Learning Objectives: Learning Objectives: - Understand the concept of bacterial biofilm in the process of causing disease - Know and differentiate between subsurface pellicle and acquired pellicle - Know the stages of dental plaque formation and factors that may affect its build-up - Differentiate between sub-gingival and supra- gingival calculus

8. Bacterial Plaque Unlike most diseases, dental caries and periodontal disease are caused by a variety of bacterial species Unlike most diseases, dental caries and periodontal disease are caused by a variety of bacterial species

9. Bacterial Plaque Microbial biofilm: Microbial biofilm: - All living cells are negatively charged - Biolfim bacteria behave differently from Planktonic (liquid-phase) cells. Bacteria growing in biofilm are more resistant to host defence mechanisms and exogenous antimicrobial agents. Thus mechanical removal of bacterial biofilm is needed to have effective antimicrobial therapy

10. Bacterial Plaque - Prior to tooth eruption, microscopic voids on the enamel surface is filled by organic material of endogenous origin (subsurface pellicle) - After tooth eruption, a thin coating of salivary film covers the tooth exposed surface and subsequently become colonized by oral bacteria. This exogenous film is called acquired pellicle

11. Bacterial Plaque - If the acquired pellicle is removed it begins to reform immediately and it takes about a week for the pellicle to develop its condensed and mature structure - The acquired pellicle is also formed on artificial surfaces, e.g. dental restorations

12. Bacterial Plaque - The carbohydrate components of certain pellicle glycoproteins may serve as receptors for bacterial-binding protein such as adhesin

13. Bacterial Plaque Factors influencing the build-up of dental plaque: Factors influencing the build-up of dental plaque: 1. Mechanical displacement (chewing, tongue movement, oral hygiene aids) 2. Stagnation (colonization in sheltered environments, e.g. inter-proximal area) 3. Availability of nutrients 4. Interactions between the microbes and the host’s inflammatory immune system

14. Bacterial Plaque Plaque formation: Plaque formation: - Within 2 hours, initial plaque formation begins as a series of isolated bacterial colonies confined to tooth surface irregularities - In about 2 days, the plaque double in mass and bacterial colonies coalesce - In the first 4-5 days of plaque formation, the number of bacteria increase significantly - After approximately 21 days, bacterial replication slows so that plaque accumulation becomes relatively stable. Bacteria in the deeper portion of the developing plaque are either facultative or obligate anaerobes

15. Bacterial Plaque Plaque formation: Plaque formation: - In individuals with poor oral hygiene, superficial dental plaque may contain food debris and mammalian cells such as desquamated epithelial cells and leukocytes. This debris layer is called materia alba “white matter” - First bacteria to adhere to tooth surface are called primary colonizers, and are typically non-pathogenic - Secondary colonizers bacteria colonize on existing bacterial layer - Early colonizers are cocci (47-85% streptococci), followed by short rods and filamentous bacteria. These are mainly aerobic bacteria - Sucrose is used to synthesize intracellular and extracellular polysaccharides

16. Bacterial Plaque Dental Plaque metabolism: Dental Plaque metabolism: - Upon exposure of dental plaque to sucrose, acid forming organism such as S. mutans produce: 1. Acids 2. Intracellular polysaccharides 3. Extracellular polysaccharides [ glucans (dextran) and fructans (levan)] - 20% of plaque dry weight is made up of glucans, 10% levans, and 70-80% bacteria - Dental plaque and dental caries and periodontal disease initiation

17. Bacterial Plaque Dental calculus: Dental calculus: - From Latin word meaning stone - Tartar refers to accumulated sediment or crust on the sides of a wine cask - Calculus in itself is not harmful, but harm comes from overlying dental plaque - Smokers, children with asthma and cystic fibrosis, mentally handicapped individuals, and patients who are tube-fed over long periods have greater calculus deposits - Patients taking medications such as beta-blockers, diuretics, and anticholinergics have significantly reduced levels of calculus

18. Bacterial Plaque Dental calculus: Dental calculus: - Supra-gingival calculus: - located coronal to gingival margin and frequently develops opposite to duct orifices of major salivary glands. 30% mineralized. Yellow to white chalky mass - Sub-gingival calculus: - Located below the gingival margin and derived its minerals from crevicular fluids within the gingival sulcus. It is thinner and harder (60% mineralized) than supra- gingival calculus. Gray to black in color. - Calculus formation can be inhibited by using agents containing pyrophosphate or metal ions such as zinc