From the Guidelines
For limited inter-occlusal space in implant-retained crowns, a screw-retained monolithic zirconia crown is the optimal choice. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of meticulous occlusal analysis and planning in implant-supported cantilever fixed dental prostheses 1. When considering the type of crown for limited inter-occlusal space, it is essential to prioritize morbidity, mortality, and quality of life as the outcome.
Key Considerations
- The use of monolithic zirconia offers excellent durability and wear resistance even at reduced thickness, preventing potential fractures that might occur with layered porcelain restorations in tight spaces 1.
- Custom abutments can be designed with minimal height, and the screw access channel eliminates the need for additional cement space, making screw-retained monolithic zirconia crowns ideal for cases with restricted vertical clearance.
- The screw-retained design also facilitates future retrievability for maintenance or repairs without damaging the restoration, which is crucial for maintaining quality of life.
Additional Options
- For extremely limited spaces (less than 4mm), consider working with your lab to design a custom milled titanium abutment with a flat occlusal surface that can be directly polished and used as the occlusal surface, completely eliminating the need for restorative material thickness on the occlusal aspect 1.
- Proper implant positioning and angulation during surgical placement are crucial to maximize available space for the restoration, and should be carefully planned to minimize complications and ensure optimal outcomes.
Evidence-Based Decision
The recommendation for a screw-retained monolithic zirconia crown is based on the most recent and highest quality study available 1, which provides evidence on the clinical outcomes of implant-supported cantilever fixed dental prostheses. This study highlights the importance of careful planning and design in achieving optimal outcomes, and supports the use of monolithic zirconia as a durable and reliable material for implant-retained crowns.
From the Research
Types of Crowns for Limited Interocclusal Space
- Screw-retained implant-supported casted integrated abutment crowns (IACs) can be used for limited interocclusal space in the molar region, with a high implant survival rate of 99.61% 2.
- Monolithic CAD-CAM lithium disilicate and zirconia crowns are suitable options for single implant-supported posterior crowns, with comparable clinical outcomes and a survival rate of 100% 3.
- Porcelain fused to metal (PFM) prosthesis with porcelain on the occlusal surface had a higher rate of ceramic fracture compared to PFM prosthesis without porcelain on the occlusal surface 2.
Considerations for Crown Selection
- The type of crown and method of manufacturing had no effect on the marginal and occlusal gap of single posterior crowns, while the method of manufacturing had a significant effect on the axial gap 4.
- Digital fabrication produced significantly smaller axial gaps than the conventional method 4.
- The retentive strength of implant-supported ceramic crowns on zirconia abutments can be affected by the type of cement used, with Multilink Hybrid Abutment (MHA) having the highest retentive strength after thermocycling 5.
Unconventional Implant Strategies
- An unconventional implant strategy can be used to manage patients with limited interocclusal space in the posterior region, providing a minimally invasive treatment alternative 6.