Summary of Lecture # 2 October 3, 2007 Abdullah S. Al-Swuailem BDS, MS, MPH, Dr PH

Bacterial Plaque - 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 - subsurface pellicle vs. acquired pellicle

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

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

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

Dental Caries Learning objectives: - Be able to define the dental caries and know the different types of dental caries and the process of disease initiation and progression - Know the risk factors associated with root caries - Explain how Stephan’s curve is plotted and its significance - Recognize methods to prevent dental caries - Know the difference between gingivitis and periodontitis - Understand how periodontal disease can be prevented

Dental Caries Definition of tooth cavitation: localized, post- eruptive pathological process involving bacterial acid demineralization of hard tooth tissue resulting in the formation of a cavity. Definition of tooth cavitation: localized, post- eruptive pathological process involving bacterial acid demineralization of hard tooth tissue resulting in the formation of a cavity. Theories of caries: Theories of caries: - Worm theory - Vital theory (1700s) - Chemo-parasitic theory (W.D Miller 1890)

Dental Caries Types of caries lesions: Types of caries lesions: 1. Pit and fissure caries 2. Smooth surface caries 3. Root surface caries 4. Secondary (recurrent) caries

Dental Caries Mature enamel is composed of 95% inorganic (minerals) and 5% organic material and water (Fig 3-5). Mature enamel is composed of 95% inorganic (minerals) and 5% organic material and water (Fig 3-5). Enamel of a newly erupted tooth is not fully mineralized. Therefore, newly erupted teeth are more susceptible for caries than teeth that have been present in the mouth for some time. Enamel of a newly erupted tooth is not fully mineralized. Therefore, newly erupted teeth are more susceptible for caries than teeth that have been present in the mouth for some time.

Dental Caries Stages of dental caries: Stages of dental caries: 1. Incipient lesion 2. Lesion extending to or beyond DE junction 3. Frank lesion with cavitation In theory, caries extending to dentin with intact enamel surface can be slowly be remineralized (ten Cate, 2001) In theory, caries extending to dentin with intact enamel surface can be slowly be remineralized (ten Cate, 2001)

Dental Caries Incipient lesion Incipient lesion - Characterized by white spot on the enamel surface. - In fissure caries, usually occurs bilaterally on the two surfaces at the orifice of the fissure and eventually coalesces at the base - The surface enamel is usually intact and lesion is located subsurface

Dental Caries Progression of caries depends on Progression of caries depends on 1. Ions concentration 2. pH 3. Salivary flow 4. Buffering action Plaque acids dissolve first the magnesium and carbonate ions and followed later by less soluble ions such as calcium and phosphate ions. Plaque acids dissolve first the magnesium and carbonate ions and followed later by less soluble ions such as calcium and phosphate ions.

Dental Caries For caries to develop, acidogenic bacteria must be present and a means must exist to prevent the acid from being washed away. For caries to develop, acidogenic bacteria must be present and a means must exist to prevent the acid from being washed away. Germ-free animals do not develop caries even when fed cariogenic diet (Orland et al 1954) Germ-free animals do not develop caries even when fed cariogenic diet (Orland et al 1954) Mutans streptococci and lactobacilli are the two major acidogenic bacteria Mutans streptococci and lactobacilli are the two major acidogenic bacteria

Dental Caries Mutans streptococci: Mutans streptococci: 1. Ability to adhere to tooth surfaces 2. Production of abundant insoluble extracellular polysaccharides (glucan) 3. Production of intracellular polysaccharides 4. Rapid production of lactic acid 5. Acid tolerance Damage observed in carious lesion is due to lactic acid, although other acids are present within the plaque Damage observed in carious lesion is due to lactic acid, although other acids are present within the plaque

Dental Caries Lactobacilli: Lactobacilli: - LB does not play a major role in carious lesion initiation, but important in the progression of lesion - With established low pH, the number of LB increases and the number of MS decreases.

Dental Caries Ecology of dental caries: Ecology of dental caries: - Before teeth eruption the number of MS is very low - The source of infection of infant by MS is from caregiver (usually the mother) by mouth-to- mouth transmission via kissing or sharing spoon during feeding

Dental Caries Root Caries: Root Caries: - Individuals are living longer and therefore retained teeth may develop root caries associated with gingival recession - Most seniors are consuming medications known to reduce the salivary flow and therefore increase the risk of root caries - Prevention of root caries can be achieved by preventing periodontal disease

Dental Caries Stephan Curve: Stephan Curve: - Named after Dr. Robert Stephan - Showed the effect of eating or drinking different foods and beverages on plaque pH (Fig 3-9)

Dental Caries Demineralization and remineralization: Demineralization and remineralization: - Long term exposure of teeth to low concentration of fluoride (as in fluoridated water) results in gradual incorporation of fluoride into existing hydroxyapatite (HAP) crystals to form fluorhydroxyapatite (FHA) that is more resistant to acid damage. This form is known to be firmly bound fluoride - Topical application of higher concentration of fluoride to the tooth surface results in the formation of surface globules of calcium fluoride that is subsequently covered with phosphate and proteins from saliva rendering these globules more insoluble. This form is known to be loosely bound fluoride

Dental Caries Demineralization and remineralization: Demineralization and remineralization: - Following an attack by the plaque acids, the CaF2 dissolve first followed by HAP and finally FHA. - With the increase of ions concentration, the crystals dissolution slows. - New HAP and FHA reform to fill the defect with most of fluoride ions coming from CaF2 and newly adsorb CaF2

Dental Caries Demineralization and remineralization: Demineralization and remineralization: - Use of fluoride varnish: Some studies have shown that biannual application of fluoride varnish may stop the activity of 81% of active enamel caries on primary teeth

Periodontal Disease Definition: periodontal disease is a dental plaque-induced disease affecting the supporting tissue of the tooth (periodontium). It ranges from mild reversible form (gingivitis) to a more severe and irreversible form (periodontitis). Definition: periodontal disease is a dental plaque-induced disease affecting the supporting tissue of the tooth (periodontium). It ranges from mild reversible form (gingivitis) to a more severe and irreversible form (periodontitis).

Periodontal Disease Structures of periodontium Structures of periodontium

Periodontal Disease Gingivitis: An inflammation process of the gingiva in which the junctional epithelium, although altered by the disease, remains attached to the tooth at its original level. Gingivitis: An inflammation process of the gingiva in which the junctional epithelium, although altered by the disease, remains attached to the tooth at its original level. Periodontitis: An inflammation condition of the gingival tissues, characterized by loss of attachment of the periodontal ligament and the bony support of the tooth Periodontitis: An inflammation condition of the gingival tissues, characterized by loss of attachment of the periodontal ligament and the bony support of the tooth

Periodontal Disease Factors affecting the PD: Factors affecting the PD: 1. Bacterial plaque 2. Patient’s medical conditions 3. Patient’s environmental factors 4. Patient’s genetic background

Periodontal Disease Development of gingivitis Development of gingivitis - Gingivitis can be observed 9-21 days after cessation of oral hygiene measures in a healthy mouth - The degree of gingival inflammation depends on the amount of plaque accumulation

Periodontal Disease Development of gingivitis Development of gingivitis - Damaged caused by gingivitis can be reversed by practicing removing the cause of disease, i.e., dental plaque and calculus - Systemic conditions such as pregnancy or hormonal imbalance may exaggerate gingival tissue response to bacterial presence in the dental plaque - Similar reactions maybe also seen with certain drugs

Periodontal Disease Development of gingivitis Development of gingivitis - Clinical changes observed with gingivitis: 1. Alterations in color (pink red) 2. Knife-edge margin of free gingiva rolled 3. Gingiva firm consistency Spongy consistency 4. Bleeding maybe observed

Periodontal Disease Periodontal Microflora Periodontal Microflora - Periodontal disease process is understood in the frame of two Hypotheses: 1. Non-specific plaque Hypothesis 2. Specific plaque Hypothesis

Periodontal Disease All periodontitis is preceded by gingivitis progresses, but not all untreated gingivitis progresses to periodontitis All periodontitis is preceded by gingivitis progresses, but not all untreated gingivitis progresses to periodontitis The development of periodontal pocket (pathological) implies that there is apical migration of junctional epithelium The development of periodontal pocket (pathological) implies that there is apical migration of junctional epithelium

Periodontal Disease Prevention of periodontal disease Prevention of periodontal disease 1. Mechanical plaque control: - Regular toothbrushing - Routine use of dental floss 2. Chemical plaque control: - Use of mouth rinses such as chlorhexidine - Topical fluoride maybe used to prevent root caries 3. Removal of local factors such as calculus (via scaling) or restorations with defective margin (i.e. new restorations)

Tooth-Brushes and Tooth Brushing Methods Tooth-Brushes and Tooth Brushing Methods