Assertion: zircon's use | /r/HasProperty | justified
Facets:
value: as a rule of thumb
type: MANNER
Source sentences:
text: As a rule of thumb, the use of crowns and other indirect restorations for root treated teeth is justified when the surface area of the access cavity exceeds one third of the occlusal surface of the tooth, when the lingual or buccal walls are undermined or when the mesial and distal marginal ridges are missing.