Table 2 Material and technical factors influencing the selection of an indirect restoration
From: Principles guiding the restoration of the root-filled tooth
Material | Advantages | Disadvantages | Survival rates | Considerations | Preparation techniques |
|---|---|---|---|---|---|
Metal-ceramic | Acceptable aesthetics High strength and toughness Good support for veneering porcelain Low cost Well-established technique | Not usually as aesthetic as all-ceramic options (lack translucency) Metal can show through cervically, or if the porcelain chips Exposed opaceous porcelain can wear opposing teeth | 79% - 20 yrs62 | Most common posterior crown material due to strength, aesthetics and cost Suitable for most patients, including those with bruxism May use polished metal surfaces on high-wear areas | Traditional preparation Requires adequate reduction for both metal and porcelain layers in areas of aesthetic need |
Zirconia monolithic or layered/veneered | Good aesthetics (esp. layered/veneered options) Strongest and most fracture-resistant ceramic (flexural strength ~1,200 MPa) Low plaque accumulation Biocompatible and tissue-friendly (polished, unglazed) | Layered/veneered zirconia prone to chipping and micro-cracks (esp. with reduced core support or in bridges) Can be more difficult to adjust and polish | 97.3% - 5 yrs (zirconia-based)68 97.4% - 5 yrs (metal-based with over-pressed veneers)68 | Monolithic zirconia preferred for ETPT due to reduced risk of chipping More studies needed with larger sample sizes and longer follow-up periods to provide definitive longevity | Traditional preparation (may be able to use more minimal techniques eg vertiprep60 or ‘biologically oriented preparation technique'61 - but only very limited evidence available for the efficacy of these) |
Glass ceramics: lithium disilicate (eg IPS E.max) leucite-reinforced (eg IPS Empress) | Excellent aesthetics - translucency mimics natural teeth Can be used both anteriorly and posteriorly Conservative preparations possible | Lower fracture resistance than zirconia, esp. posteriorly May not be suitable for patients with bruxism or parafunctional habits | 97.1% - 11 yrs (IPS Empress II and IPS E.max Press)70 | Suitable for ETPT in specific cases with high aesthetic need Survival rates may vary between materials Careful case selection is important | Traditional preparation Adequate reduction needed to accommodate chosen material with adequate strength |
Gold | Long survival times Excellent wear resistance Conservative preparations - strong in thin sections Biocompatible and tolerated by gingival tissues Does not wear opposing teeth Easily adjusted and polished | Compromised aesthetics Increasingly a loss of technician expertise High cost | Very high survival rates at 30 years55 70% - 20 yrs (gold crowns)74 | Excellent option for non-aesthetic zones, esp. in parafunction May be a good choice for patients with limited interocclusal space | Traditional preparation Specific finishing margin requirements for optimal gold adaptation |
