BMS1-21_ Microbiology of Decay_ Assoc. Prof. Dr. Ayşe Sarıoğlu(1).pdf

MICROBIOLOGY OF DENTAL DECAY Summary p Tooth Decay: Most popular and high incidence in mouth p Tooth Decay: Progressive disease performed entirely by bacteria p Tooth Decay : Poor or rural disease. On the contrary, the disease of civilization p Tooth Decay : Chronic Inf...

MICROBIOLOGY OF DENTAL DECAY Summary p Tooth Decay: Most popular and high incidence in mouth p Tooth Decay: Progressive disease performed entirely by bacteria p Tooth Decay : Poor or rural disease. On the contrary, the disease of civilization p Tooth Decay : Chronic Infection Disease 2 Caries hypotheses 1. Specific plaque hypothesis n S. mutans and S. sobrinus initiating caries Non-specific plaque hypothesis n The bacteria that start caries are not original Ecolojic plaque hypothesis n Permanent microflora balance deterioration tooth decay occurs by dissolving the enamel with acids Acid formation in dental plaque p Depending in the variety of bacteria in the plaque; n Acid+Alcohols forms from CH n Saliva dilutes, wash and buffer acid These two mechanisms work mutually n Tooth decay; n Acid producing mechanism overcome acid removal mechanism For caries to occur; acid making rate should be more than the rate of saliva wash  Glucose shock Glucose shock “Mouth pH drops due to 10% glucose solution given by healthy individuals and rinsing their mouths for 10 sec. Stephan curve “The curve obtained by measuring the pH of the mouth by 30 sec intervals following a glucose shock’’  Stephan curve This curve is different for each human, each dental plaque, each cryogenic bacterium Some bacteria show a dramatic drop on Stephan curve; p Ex: Streptococcus, laktobasilli, Rothia (asidogenous bacteria) p Some do less sloping; n Ex: Actinomyces, Eubacterium, Peptostreptococcus Peptostreptococci are found in the dental plaque, however, they cannot break any KH (except P.productus) and cannot be held primarily responsible for tooth decay.  Demineralisation p CHs need to be converted to acids by bacteria to create caries p Ph of environment drops (usually organic acids) p Tooth enamel: is a calcified tissue around an organic matrix. large part is made up from organic salts (calcium phosphate) p Acid medium; It dissolves Ca salts p The organic matrix (collagen) remains from demineralized enamel tissue (caries are white in colour at this stage). p Decomposition of organic matrix by bacteria; p BLACK COLORED CARIES  Cavitation p In the later stages of the decay, the bacteria enter to the microcavities of the demineralized enamel p First in bacteria: Laktobacilli and Streptococci p Due to increased acid production, enamel repair on the outer surface of the cavitary cavity is not possible p Event is irreversible p Dentin decay is more progressive p Organic materials in dentin tissue is more p There are 15.000-75.000 dentin tubes in 1 cm2 dentin section p As the dentin progresses; p Dissolution of inorganic salts p Hard tissue loss CAVITY FORMATION Decay forming (karyogenic) bakteria 204 children aged 1.5 to 7 years of age flora; p Non-caries individuals: S.mitis, S.oralis, S.sanguinis, S.parasanguinis, Abiotrophia defectiva p Individuals with Caries: Actinomyces spp, Lactobacillus spp and S.mutans p In deep caries of young permanent teeth; p S.mitis, S.pneumoniae, S.infantis, Corynebacterium matruchotii, S.gordonii, S.cristatus, Capnocytophaga gingivalis, Eubacterium spp, Campylobacter rectus shown by 16 sribosomal RNA analysis Decay forming bakteria In flora determination studies on milk teeth; p Non-caries individuals: S.sanguinis p İndividuals with caries: Actinomyces spp, Lactobacillus spp, S.mutans, Veillonella spp, Bifidobacterium spp. as caries progress, bacterial count and variety increase p The most dominant bacteria in caries: n Lactobacillus, Veillonella, Bifidobacterium, Propionibacterium, Actinomyces, Atopobium, S.mutans Prevention of dental caries “Protection from tooth decay is possible with removal of plaque and acids by toothbrush” p Using antiseptic and local antibiotics is INCORRECT p Using long lasting antiseptic, destroys oral flora, NOT A GOOD IDEA p Antibiyotic chewing gums, antiseptic gargaras, sprays not good for tooth decay p Inhibiting tooth decay forming nutrition NOT CORRECT p Best method: Balanced diet, removal of plaques and hygiene education Antiseptic gargara should not be used more than 1 week Dental caries immunology “Oral hygiene prove that tooth decay is not a genetic desease” p Bacteria that cause caries are not genetically transmitted, they are trasmitted from the oral environment and multiply Familial food consumption habits p People with bad oral hygiene may have less dental caries; n Due to IgA against carcinogenic bacteria in salive n Effective non-specif immunity q Anatomical malformations reduce the washing effect of saliva