assessment of restorability Flashcards
what are goodacres principles
Goodacre 2001:
is a set of requirements to tell us how much tooth we need for the crown
total occlusal convergence: 10-20 degrees
occlusocervical dimension:
molars >=4mm
other teeth >=3mm
defn of retention and resistance form
GPT 9th edition
Retention form: features of a tooth prep that resists dislodgement of a crown in a vertical direction or along the path of placement
resistance form: features of a tooth prep that enhances stability of a restoration and resists dislodgement along an axis other than path of placement
disadvantages of CL
- increased C:R ratio, makes tooth more susceptible to fracture
- may expose furcations hence more difficult to maintain
- results in reduced attachment on multiple adjacent teeth
- CL also results in tooth with a thinner cross section at the poitn where root emerges from bone and hence we might have to compromise on aesthetics on anterior teeth, because even though a shoulder prep is the best for aesthetics, it will impinge on pulpal tisues
- CL also results in larger embrasure spaces interproximally, might be unaesthetic
what is the survival rate of DME
95.9% overall survival after up to 12 years, where 5 out of 8 falures were due to recurrent proximal carious lesions.
currnt evidence suggests that DME is a viable approach to restore teeth with localised subg defects as a possible alternative to CL surgery
indications and advantages of DME
- can only b performed under Grade 1 subgingival margin scenarios where grade 1 = on placement of Rubber dam in gingival sulcus, the cervical margin can be adequately visible
adv:
- facilitates optical impression making
- optimizes prep design for bonded partial coverage restorations
- facilitates isolation for bonding of coronal restoration
- reduce challenges associated with bonding to deep dentine
- when alternative options are contraindicated due to time, cost, morbidity eg CL, ortho extrusion
disadv of DME
- dependent on cavity configuration, is not possible with irregular margins or root concavities
- violation of SCTA
- multiple restorativ interfaces which means restorations are more prone to breakdown at different levels
- is very technique sensitive
