When prevention fails Flashcards
what is needed when presentation fails?
restoration or extraction required
You can only restore a tooth if?
if there is sufficient viable tooth surface (hold restorative material in place)
what is class I of caries?
Occlusal surfaces of molars and premolars, buccal pits of molars
what is class II of caries?
approximal surfaces of molars and premolars
what is class III of caries?
approximal surfaces of incisors and canines
what is class IV of caries?
incised edges of incisors and canines
what is Class V of caries?
cervical margins
what are the principles of cavity preparation?
- convenience form
- outline form
- resistance
- retention form
- treatment of residual caries
- correction of enamel margins
- cavity debridement
what is convenience form?
when you prepare a cavity - we enlarge it so we can get instruments in but before we can establish outline form
what is resistance form?
support the restoration (if there is a curved bottom, apply cement to level out because if not it can rotate)
what is needed in retention form?
-with parallel sided cavity , restorations can slide out so undercuts are needed - it will be locked in place (non adhesive material to stay in place)
In retention forms, what is needed to prevent restoration moving along occlusal floor?
cross brace to prevent movement (occlusal key/lock) -when it comes to class II, any force is resisted
Describe the correction of enamel margins.
- remove weakened tooth substance
- facilitates placement of matrix retainers
- bevel to increase surface area for bonding
what is used for cavity debridement.
- triple syringe
- aspiration
what are further considerations on treatment of residual caries?
- classically excavator and round bur- judicious use of large bur as opposed to small
- consider use of caries detector dyes (some say risk excessive tooth tissue removal )
- may facilitate when used with chemical agent in chemomechanical method
what is the reason for using larger bur drill over a small drill?
- the large bur can rotate slowly so it will remove caries slowly so it is more controlled and more efficient
- with a small diameter round burr, large amounts of pressure into soft dentine so could end up in dental pulp
Describe the chemomechanical method.
- chemicals make soft dentine to remove with hand instruments
- Carisolv, amino acids(leucine, lysine,glutaminc acid) and sodium hypochlorite when combined there is proteolytic action
- this acts on denatured proteins of carious dentine and enables separation of sound and carious dentine
- use specific hand instruments with rubbing action
- reduces need for local anaesthesia and less/no time with rotary instruments
- of value in children and anxious
Describe stepwise excavation.
- wise to adopt when conventional caries removal is likely to expose pulp
- clear periphery
- free cavity floor of superficial necrotic and demineralised dentine avoiding areas close to pulp
- line CaOH and temporary GIC resin
- 8-12 weeks reopen and excavate to yellow/greyish hard dentine
- line decal , vitrebond and restore
Do we need to augment the retention afforded by the cavity design?
- use of acid arch technique
- use of dentine bonding agents
what do these techniques reduce?
reduce the need for the mechanical creation of undercuts for retentive purposes and conserve tooth substance
Describe the acid etch technique.
-Buonocore
-application of acid gel
-selective decalcification of enamel prisms
(allows restorative material to penetrate and hold in place)
-micromehcnical tags into Inyo which bonding resin may flow
-20-30MPa
when are dentine pins or adhesive bonding agent considered?
-if restoring cavity with amalgam need mechanical retention , where little tooth substance remains and there are no cavity walls problem
how are dentine pins inserted?
- placed at corners of tooth
- cut pin channel first
- insert pin
when are dentine pins used?
used for amalgam where one or more cusp is missing
where are pins inserted?
- one pin per missing cusp except in premolars where two pins should be used
- placed 1mm within ADJ at corners of tooth so as to avoid the pulp
what is the risk of dentine pins?
- risk pulpal exposure, pal and so rarely used
- helpful when modern bonding fails
what happens when caries spreads along the ameldodentinal junction?
- unsupported enamel is weak
- trim back for non adhesive materials
- consider leaving for adhesive materials as weakened enamel may be splinted by the use of such materials
what restorative materials are to be used?
- amalgam and resin composite non adhesive
- glass polyalkenoate is adhesive
what is conservation of tooth substance?
- restorations don’t last forever
- small is beautiful
- preserve oblique ridge in maximally molars
what injures the tooth?
caries and cavity preparation
what do you do when preparing cavity?
- minimise further plural injury
- water coolant
- aim to : maintain pulp cell function and viability , reduce probability of post operative complications
what are significant factors associated with potential for damage?
- remaining dentine thickness
- cavity morphology -depth , area, volume
- pulpal inflammation due to restorative dental technique e.g. acid etch , lining - all can release TGFb
- type of restorative material
Describe the restorative escalator.
- complexity has gone up because cavity is getting bigger each time
- so small as possible with mimunum intervention
- more likely to surface the whole life of patient
when do you restore caries?
- where it is active or aesthetic concerns
- only remove soft caries
how do you avoid exposure for deep penetrating lesions?
stepwise techniques
what procedures/materials are selected?
least likely to damage pulp
