principals of cavity preparation Flashcards
what are some properties that determine cavity design
- structure and properties of the dental tissue involved
- the disease (caries, PDD, surface loss)
- properties of restorative materials
need to consider if the cavity will need to modified to accommodate a specific restorative material because the binding will differ depending on the surface
which factors of cavity preparation must be reviewed and assessed continually when preparing a tooth to receive a restoration
- position of the caries
- extent of the caries
- shape of the prepared cavity
- final restorative material
what are the different positions caries can be found in
- pit and fissure
- inter proximal (anteriorly or posteriorly)
- Smooth surface caries (also relevant when looking at erosion, abrasion, abfraction or hypoplasia)
- root caries
when should there be operative intervention to a tooth (ie when would a cavity need to be prepared and restored)
when the lesion is caveatted
when the patient cannot access the lesion for prevention
when is operative management something that should be considered for a lesion without necessarily being essential
if the lesion is into dentine radiographically
lesion is causing pulpits
lesion is unaesthetic
explain the features of enamel in relation to cavity prep and restoration
brittle
fractures run along prisms
any fragile enamel under occlusal load should be removed before restoring because it will not support the restoration
dry tissue
which dental tissue is wet
dentine
why are gingival tissues important to consider when restoring teeth
can be inflamed in the presence of plaque
margins of the restorations should be easy to clean so need to consider using a provisional restoration that is replaced when the swelling goes down
why is tertiary dentine harder to restore
the tubular structure is less organised than primary and secondary dentine
if there are multiple dentine types exposed which material would be used - one to match primary or secondary
you would have to treat the dentine types differently so there would be a combination
does the area on the tooth and the way enamel has been cut make a difference to the type of restorative material being used
no it does not make a large difference
describe the significance of linings in relation to operative management of caries
can impact bonding, enamel contamination, protection of pulpal therapeutic agents, risks if micro leakage occurs and secondary caries
this means it is important to assess the quality of the proposed dentine bond
what are the different features of exposed dentine that should be considered when deciding on the bonding and restorative agents
the type (primary secondary or tertiary)
if it is intra inter or peri tubular dentine
the diameter
the density
the mineralisation
if it healthy, diseased or reactive dentine
what are the principles of cavity preparation driven by
caries removal
necessary finishing ( modification of the cavity) to allow for
- maximising adhesion
- occlusal relationships
- ease of patient cleaning
- properties of the materials used
why should an attempt be made to remove healthy tooth tissue
if the material used for the restoration requires it or if the margins of the cavity cross an occlusal contact
outline the principles of caries removal and cavity preparation (know this card!!)
- identify and remove carious enamel
- remove enamel to identify the maximal extent of the lesion at the ameldodentinal junction and smooth the enamel margins
- progressively remove the peripheral caries in the dentine from the ADJ first, then circumferentially deeper
- only then remove the deep caries over the pulp
- outline form modification (Cavo surface margins) for enamel finishing, occlusion and requirements of the restorative material
- internal design modification including internal line and point angles, and to match the requirements of the restorative material
what is the Cavo surface margin
junction of the outline form of the external surface and the internal surface of the tooth
what steps should be taken for the final Cavo surface margins during cavity preparation
remove enamel that will not be supported by the etch technique
smooth cavosurface margins and line angles
ensure there are no excessively acute line angle transitions and that the outline form is smooth and rounded
check for stress concentrators
why should sharp lines be avoided when preparing cavities
they can cause fractures
what is the line angle
the junction between two surfaces
what is the point angle
the junction between three surfaces
what are the steps to final cavity design
- where an existing restoration has been removed, ensure that no traces of restorative material remain unless placing a repair
- smooth external enamel sharp line or point angles
- create appropriate Cavo surface margin angles
- removal internal dentinal sharp line or point angles
- check for stress concentrators
the final seal of the restoration is critical. which elements need to be met for this seal to be effective
- smooth margins
- approvate cavo surface margin angle
- no unsupported tooth tissue
- no stress concentrators
- internal anatomy that allows adaptation of material
why do marginal seals need to be perfect when restoring teeth
because bacteria can get in and form plaque leading to further caries
what is secondary caries
caries caused by failed restorations allowing build up of plaque
what should be done once the prepared cavity is satisfactory
clean the cavity to ensure it is free from debris generated during preparation
what is the first principle of cavity preparation
access the caries
- apply the dental dam
- remove overlying enamel with a high speed bur to gain access to carious dentine
- follow the cares at the ADJ
- do not extend into non carious areas
what are the three labels pointing to
bevel
line angle
point angle
