Biofilm Flashcards
what causes dental caries and periodontal disease?
- microorganisms in dental (microbial) biofilm
what must be examined during clinical examination and assessment of the teeth and surrounding structures? why do we do this?
- soft and hard deposits must be examined closely so that a care plan can be established based on the individual needs of the patient
what are the 3 types of calculus we might feel on patient’s teeth?
- granular
- spicules
- ledges
what do soft deposits include?
- acquired pellicle
- dental biofilm (plaque)
- materia alba
- food debris
- these are all different and the terms are not interchangeable
what are hard deposits?
- the hard, calcified deposits on teeth are termed dental calculus (tartar).
what is acquired pellicle?
- amorphous, acellular, organic structure that forms over exposed tooth surfaces, restorations and calculus
- thickness varies from 0.1 to 0.8 microns and is usually greater near the gingival margin
when is acquired pellicle formed? what is it?
- formation starts immediately after all the tooth surfaces have been cleaned
- made up of glycoproteins from the saliva that are:
- selectively adsorbed by the hydroxyappetite of the enamel
- forms a clear coating over the teeth for microorganisms to adhere to
- clear coating is highly solluble
what are the 3 types of pellicles?
1 - surface pellicle, unstained (translucent)
2 - surface pellicle, stained (can acquire stain)
3 - subsurface pellicle (embedded in demineralized areas)
what is the purpose of pellicle?
1 - protective: provides a barrier against acids - may aid in caries reduction
2 - lubrication: provides moisture and prevents drying
3 - nidus (point of origin) for bacteria: aids in adherence of bacteria
4 - attachment of calculus: pellicle is one mode of adherence of calculus to teeth and restorations
what is biofilm?
- dense
- nonmineralized
- complex mass of colonies in a gel-like intermicrobial matrix
Adheres firmly to acquired pellicle and hence to the teeth, calculus, restorations, both fixed and removable (ie. dentures) even to the gingiva
what are the 5 steps in the formation of biofilm?
1 - formation of a pellicle 2 - bacteria attach to the pellicle 3 - bacterial multiplication and colonization 4 - biofilm growth and maturation 5 - matrix formation
what is the intermicrobial matrix mainly derived from?
- saliva from supragingival deposits
- sulcular (crevicular) fluid and exudate in subgingival deposits
- produced by certain bacteria from dietary sucrose
What are the other components of the intermicrobial substances?
- polysaccarides, glucans, fructans and levans
- polysaccarides are sticky and provide the adherence of the biofilm to the teeth
what increases as the numbers of microorganisms increases?
- the probability of developing caries
what types of bacteria/microorganisms are present during days 1 to 2 of biofilm development?
- gram positive cocci
what types of bacteria/microorganisms are present during days 2 to 4 of biofilm development?
- cocci still dominant
- increasing numbers of gram positive filamentous forms and rods may be present on the cocci colonies
what types of bacteria/microorganisms are present during days 4-7 of biofilm development?
- filaments increase in number, more rods and fusobacteria appear
- gingival margin thickens with gram negative spirochetes and vibrios appearing
- coronally spread bacteria contain the cocci forms
what types of bacteria/microorganisms are present during days 7 to 14 of biofilm development?
- vibrios and spirochetes appear
- with maturation, the more gram negative and anaerobic organisms appear
- inflammation is now observable in the gingival tissues
what types of bacteria/microorganisms are present during days 14 to 21 of biofilm development?
- vibrios and spirochetes are prevalent along with the rods and cocci
- gingivitis is present
what is experimental gingivitis?
- begins with GI, BI & PI
- observable within 2-3 weeks, when the biofilm is left undisturbed
- reversible if biofilm removal is thorough for a few days
what is the main source of subgingival dental biofilm?
- results from the apical migration of microorganisms from supragingival biofilm
- in early gingivitis/periodontitis the supragingival bacteria is a strong influence on the accumulation and pathogenic features of the subgingival biofilm
what are the differences between supragingival and subgingival dental biofilm and its microorganisms?
- subgingival microorganisms consists of more anaerobic and motile organisms
- these organisms are predominately gram negative
- leukocytes present
where does biofilm attach to the tooth?
- over the pellicle
- associated with calculus formation, root caries and root resorption
where can we find unattached biofilm?
- between the 2 layers
- planktonic, motile, gram negative bacteria
what is epithelium biofilm?
- associated biofilm: loosely attached to the pocket epithelium
- microorganisms invade the connective tissue
composition of biofilm
- biofilm is composed of microorganisms and an intermicrobial matrix
- water accounts for 80%
- organic and inorganic solids make up 20%
- microogranisms make up 70-80% of the solid matter - higher in subgingival biofilm
what inorganic elements can be found in biofilm?
- calcium, phosphorus, magnesium and fluoride
- deposits on the lingual surfaces of the mandibular teeth contain a higher concentration of calcium and phosphorus than on other teeth
- fluoride concentration is higher in dental biofilm where the water is fluoridated. it also increases following professional fluoride application and the use of fluoridated pastes and mouth rinses
what organic compounds can we find surrounding the microorganisms of biofilm?
-primarily carbohydrates, proteins and a small amount of lipids
what is the purpose of carbohydrates in bacteria?
- produced by the bacteria themselves
- contribute to adherence of microorganisms to each other and to the tooth and
- energy storage of carbohydrates for reserve use by biofilm bacteria
where does biofilm derive its proteins from?
- supra-g: proteins from the saliva
- sub-g: proteins from the gingival sulcus fluid
clinical aspects of biofilm:
1 - location
2 - by surfaces
3 - factors influencing biofilm accumulation
where can we find biofilm (location)?
- supra-g, gingival, sub-g, and fissure biofilm
what factors influence biofilm accumulation?
- crowded teeth
- rough surfaces
- difficult to clean areas
- teeth out of occlusion
- bacterial multiplication
what are the 4 ways we can detect biofilm?
1 - direct vision
2 - use of explorer or probe
3 - use of disclosing agent
4 - clinical record
how do we record biofilm detection?
- record by location and extent (mild, moderate or severe)
- indices are used for comparison in conjunction with patient instruction for home care at each appointment
what is the significance of biofilm?
- microbial biofilm plays a major role in the initiation and progression of both dental caries and periodontal disease
- general oral cleanliness depends on the daily removal of dental biofilm deposits
- accumulation of deposits contributes to an unpleasant look as well as halitosis (bad breath, caused by microorganisms on the tongue)
variations in biofilm:
- varies amongst individuals
- varies amongst tooth surfaces
- varies as it ages
what 3 things must happen for dental caries to occur?
1 - must be a susceptible tooth
2 - must be microorganisms
3 - must be cariogenic foodstuff as source
what are 4 contributing factors for the formation of dental caries?
1 - time: acid forms immediately when sugar is taken into biofilm
2 - the pH of the biofilm. critical pH is 4.5-5.5 enamel, root surface is 6-6.7
3 - frequency of carbohydrate intake. a large amount at mealtime is less damaging than frequent intervals during the day
4 - duration. how long each time CHO is consumed
what effect does diet have on biofilm?
- cariogenic foods: affects dental caries and sucrose in amount and pH of biofilm
- food intake: food particles are not needed in the mouth for biofilm to form
- texture of diet: the friction of mastication has been shown to affect only the occlusal and incisal thirds of the crowns of teeth
what can cause periodontal infections?
- the microorganisms of periodontal infections
what is materia alba?
- loosely adherent mass of bacteria and cellular debris
- distinguishes itself clinically as a bulky, soft deposit that is clearly visible; resembles cottage cheese. can be rinsed away with water or air, whereas dental biofilm cannot
- forms over dental biofilm
food debris
- adds to the general unsanitary condition of the mouth
- cariogenic foods contribute to dental caries
- some self-cleansing takes place through the action of the tongue, lips, saliva and related factors
how can we remove food debris?
- toothbrushing, flossing and other aids constitutes a total biofilm control program
- cleansing of debris from around fixed prostheses and orthodontic appliances is important to the plan for oral sanitation
when does food impaction occur?
when there are:
- open contacts
- mobile teeth
- irregularities in occlusion (plunger cusp)
- facial and lingual embrasures (below the contact) with reduced interproximal papillae
conclusion:
- biofilm reforms within 8-24 hours
- biofilm takes 21 days to reach full maturity
- within 7-14 days inflammation is observable in the gingival tissues
- gingival inflammation is reversible with regular removal of biofilm
- it is our ethical responsibility to ensure patients understand the link between biofilm and inflammation/disease
