Plaque Formation and Composition PDF

Bacterial plaque (Microbial plaque) Dental Biofilm A dense , non mineralized complex mass of colonies in a gel like intermicrobial matrix. Gingivitis Periodontitis Caries formation Ecology-complex community with over 1010 of bacteria /milligram of plaque...

Bacterial plaque (Microbial plaque) Dental Biofilm A dense , non mineralized complex mass of colonies in a gel like intermicrobial matrix. Gingivitis Periodontitis Caries formation Ecology-complex community with over 1010 of bacteria /milligram of plaque psst hey  Plaque (dental biofilm) Fusobacterium nucleatum is thought to be the beginning of gingivitis  What plaque is not Food debris Stains Materia Alba – Collection of microorganisms and cellular debris – Soft deposits that loosely adheres on top of plaque – composed of collection of living and dead bacteria, sloughed epithelial cells, salivary proteins and food debris (Cottage cheese like)  Initiation of plaque formation Formation of acquired pellicle – A amorphous, organic, tenacious membrane layer composed primarily of salivary proteins. – Forms over exposed tooth surfaces, dental restorations and dental calculus – Can be easily removed but reforms within hours  Acquired pellicle important because May provide barrier against acids responsible for caries formation Means for bacterial attachment to tooth surface – Bacterial colonization depends on this attachment  Plaque formation Not random, a complex sequence of events 1. Pellicle formation 2. Bacterial attachment initially random but then specific bacteria with attachment abilities take over 3. Bacterial multiplication/ colonization – growth and multiplication and joining of masses of colonies  Plaque formation cont. 4. Bacterial growth and multiplication Mass becomes denser 5. Matrix formation – slim layer Substance that binds colonies together. Contains: Saliva (supragingival plaque) Sulcular fluid, exudate (subgingival plaque) polysaccharides, glucans, levans ( metabolic end products of bacteria and sucrose)  Clinical Appearance Initially transparent, close observation show a a dull matte appearance to clinically visible surfaces of the teeth. Disclosing solution reveals plaque. The darker the color the denser the plaque. Liquid or tablets for take home use Disclosing agents  Microbial changes in plaque formation Initially mainly gram positive and oxygen tolerant organisms (gram+ aerobic) non motile – Streptococcus mutans – Streptococcus sanguis – Actinomyces viscosus  Day 1-2 – same as above Days 2-4 – Cocci dominant, filamentous forms arrive start to replace cocci Days 4 -7 – Filamentous increase, rods and fusobacteria also seen. Gingival plaque increases in density and vibrios and spirochetes arrive  Days 7-14 Early signs of inflammation – Vibrios, spirochetes and wbc’s increase in numbers. Gram negative (-) anaerobes arrive. – Cocci and fusiforms form corn cob, or test tube brushes  Days 14-21 Gingivitis is evident – Vibrios, spirochetes, cocci and filaments evident in older plaque, continuous new formations occur. – Stage 3 Vibrios Spirochetes Filamentous forms Cocci Rods  Quick review Stage 1 Salivary proteins +Tooth = Pellicle Stage 2 Pellicle + Microorganisms = Plaque Stage 3 Plaque + Time = Mature plaque  Most rapid changes occur in first 5 days. Stabilize by 21st day. Constant remodeling occurs. Remodeling accelerated by – Salivary flow – Muscular action – Home care 3 times pressure needed to remove 3 day old plaque  Supra and Subgingival plaque Differences include – Microorganisms involved – Significance of formation – Structure – Nutrient sources for bacteria – Distribution  Supragingival plaque Begins formation at gingival margin Moves coronally to gingival 1/3 of crown Thickest at proximal surfaces, cervical third, pits and fissure Etiologic factor in – gingivitis – supragingival calculus – formation of dental caries 48 hours 96 hours 48 hours 96 hours  Subgingival plaque Difficult to access Adheres to tooth surfaces, calculus and subgingival pellicle Most subgingival plaque organism attached to tooth structure are gram negative anaerobes and non- motile  Subgingival plaque Attached – extension of supragingival – provide basis for calculus formation – Provide basis for root caries Unattached – Swarm around attached plaque. Composed of highly motile gram negative organisms in crevicular fluid. Destroys epithelial attachment BACTERIAL INVASION INTO THE CT AND BONE  Plaque composition 20% organic and inorganic solids – Of this 20%, 70 -80% various microorganisms – More organisms in sub than supra 80% Water  Organic elements of plaque Carbohydrates – glucans, fructans, levans Proteins from saliva OR crevicular fluid Lipids (fats) in small quantities  Inorganic elements Calcium Phosphorous Higher in mandibular lingual area Fluoride – Higher in fluoridated water consumers  Plaque formation dependant on: Number and type of bacteria Character of tooth surface Affinity of bacteria to acquired pellicle Natural cleansing of area Oral hygiene habits  Factors influencing plaque accumulation Malposed or crowded Orthodontic dentition- Appliances MALOCCLUSION Partial Dentures Rough tooth surfaces Deep Pockets Poorly contoured Mouth Breathing restoration Tobacco Use Dental calculus Certain Medications Teeth not used for Areas of carious mastication lesions (decay)