Caries and cavity prep Flashcards
Define caries
A reversible (in earliest stages) progressive disease of the dental hard tissues, instigated by the action of bacteria upon fermentable carbohydrates in the plaque biofilm on the tooth surfaces leading to acid demineralisation and ultimately proteolytic destruction of the organic component of the dental hard tissues
Define primary caries
Caries lesions on a previously sound tooth
Define recurrent (secondary) caries
caries lesions which have developed adjacent to a restoration
Define rampant caries
Historically used to describe multiple caries lesions in the same patient. Often arrises in association with early childhood caries or radiation caries
Define early childhood caries
Early onset of caries in young children with fast progression - can result in complete destruction of primary dentition
Which bacteria are responsible for caries?
- Steptococcus mutans
- Lactobacillus - progression of deep lesions
- Bifidobacteria - root caries lesions
Describe how fermentable carbohydrates affect caries
- Sucrose and glucose
- Produce acids (lactic, acetic and propionic acid)
- Initiates demineralisation
Which tooth structures are susceptible to caries progression?
- Depths of pits and fissures
- Approximal surfaces
- Smooth surfaces
- Ledged/overhanging restorations/defective margins
What are the 4 factors needed for caries progression?
- Bacteria
- Susceptible tooth surface
- Fermentable carbohydrates
- Time
At which pH does demineralisation occur? Critical pH?
pH 5.5
What is a normal pH?
pH 7.0
How long does it take for the critical pH to climb?
Approx 60m
How do carious lesions present in enamel?
- Active white spot lesions
- Brown spot lesion
What is an active white spot lesion?
Smooth, frosty white/ opaque non cavitated lesion
Lesion - chalky over time
Rough and micro-cavitated over time
What is a brown spot lesion?
Arrested lesion
Porosities filled with deposited mineral and dietary molecules causing staining
Hard and shiny surface
What are the carious lesions within dentine?
- Infected dentine - outermost, superficial, irreparable necrotic zone of destruction. Dark brown, soft, wet and mushy
- Affected dentine - inner layer, reparable, hard and paler brown, harder, sticky-scratchy
- Translucent dentine
- Hypermineralised dentine
What are the Black’s cavity classifications?
Class I: Carious lesions on the Occlusal areas or Buccal areas or Lingual Pits on the tooth surface.
Class II: Carious Lesions on the Posterior occlusal and inter-proximal surfaces of the tooth.
Class III: Carious Lesions on the Anterior inter-proximal surfaces of the tooth.
Class IV: Carious lesions on the anterior inter-proximal surfaces of the tooth including incisal corners
Class V: Carious lesions on gingival third of the crown on buccal or lingual surfaces of the tooth
What is caries risk?
Probability of an individual developing new carious lesions
Enables implementation of preventative strategies and effective monitoring to encourage the early detection of carious lesions with more and minimally invasive management.
Recheck at short intervals
Risk factors for caries shown to have strong association with risk factors related to diabetes and cardiovascular disease (angina pectoris and obesity)
What are the caries risk factors?
- Bacteria
- Time
- Diet
- Saliva
- MH
- Susceptible tooth surface
What classifies a high risk caries patient?
- Frequent sugar intake
- Drinking unfluoridated water, no fl toothpaste
- Infrequent cleaning, poor manual dexterity
- Low saliva flow rate/buffering capacity
- High S.mutans, lactobacillus
- New lesions, premature XLA, anterior caries/restorations, partial dentures, ortho fixed appliances
presence of active lesions and a yearly increment of more than 2 new/progressive/filled lesions in the preceding two-three years
How do you manage high risk caries patients?
OHI, diet analysis, Fl toothpaste 2500/5000ppm, F mouthwash > 8y (0.05%daily NaF or 0.2% weekly). F varnish 22600ppm or 2.2% (3-6m) Topical remineralising agent CPP-ACP (recaldent)
Recall 3-6m
How to manage low risk caries patients?
No active lesions and no history of recurrent restorations in the past 2-3y.
Lesion - standard and active care. high F app. Recall 6-12m
No lesions - standard care, OHI and dietary advice and fluoridated toothpaste/ 12-18m recall
Cavity prep for composite
Macro - enamel bevel margin - remove unsupported prisms, increase surface area for seal/bind.
Rounded internal line angles
Micro - 37.5% phosphoric acid removes smear layer and creates micro mechanical retention for resin. Bond.
Cavity prep for GIC
Enamel bevel margin
micro - dentine conditioner - 10% polyacrylic acid - modify/remove smear layer to prep surface for chemical adhesion
Cavity prep for amalgam
Macro - undercuts, grooves, slots, flat surfaces. prevent displacement and aid retention
How to internal line angles help cavity preps?
Reduces internal stresses and risk of crack propagation within a restoration.
