chemomechanical disinfection Flashcards
what is a biofilm
- bacteria and fungi develop into biofilm
- complex communities adhering to dentinal surfaces embedded in a matrix
what is biofilm resistance
- antimicrobial may fail to penetrate beyond the surface layers of the biofilm
- antimicrobials Amy be trapped and destroyed by enzymes
- antimicrobials may not be active against non-growing microorganisms
- expression of biofilm-specific resistance genes
- stress response to hostile environmental conditions
- protective environment where elaboration to evade attempts to eradicate them
what are the clinical objectives of endodontic therapy
- removing canal contents
- eliminating infection
how can root canal make end hard
- very complex
- all complexities enhance the ability of the bacteria and the fungi to evade our attempts to eradicate them
what is chemomechanical disinfection
- employ mechanical means to deride and shape canal and supplement this with chemical means in order to enhance biofilm destruction
what are the design objectives of endo treatment
- create a continuously tapering funnel shape
- maintain apical foramen in original position
- keep apical opening as small as possible
what does mechanical preparation do
- creates space to allow irrigating solutions and medicaments to move effectively eliminate micro-organisms from the root canal system
what are the stages in mechanical preparation
- preparation of tooth
- access cavity preparation
- creating a straight-line access
- initial negotiation
- coronal flaring
- working length determination
- apical preparation
why do we start coronally
- eradicate the most significant infected parts of root canal surface coronally first then move apically where there is less infected material
- as instrument goes deeper it is less likely to carry with it infective material down
apical preparation size?
- determined by initial size of root canal apex
- passive exploration known as gauging
- apical preparation controversial
- usually at leat ISO size 25 to allow adequate irrigation
what are the ideal properties of an irrigant
- low cost
- washing action
- reduction of friction
- improving cutting of dentine by the instruments
- temperature control
- dissolution of organic and inorganic matter
- good penetration within the root canal system
- killing of planktonic microbes
- killing of biofilm microbes
- detachment of biofilm
- non-toxic to periodical tissues
- non-allergenic
- does not react with negative consequences with other dental materials
- does not weaken dentine
what is used as an irrigant
- sodium hypochlorite = one of most successful
- Chlorhexidine used but does not give a complete kill of bugs
how does NaOCl work
- ionises in water into Na+ and the hypochlorite ion OCl-
- establishes equilibrium with hypochlorite acid
- at acid/neutral HOCl predominates
- at pH 9 or above HOCl- predominates
why do we use NaOCl
- potent antimicrobial activity
- dissolved pulp remnant and collagen
- only root canal irrigant that dissolves necrotic and vital tissue
- helps disrupt smear layer by acting on organic component
what factors are important for NaOCl function
- concentration
- volume
- contact
- mechanical agitation
- exchange