In a recent session of the EAO Digital Days, Malin Strasding presented an insightful overview on the evolution of manufacturing dental restorations. Her talk, titled "Manufacturing Restorations: Does the Technique Matter?" explored the clinical applications, outcomes, and future directions of various restoration techniques, with a focus on the shift towards monolithic restorations and the use of titanium bases.
Historical Context and Current Standards Strasding began by reflecting on the traditional gold standard in dental restorations: metal-ceramic restorations for implants. These have shown impressive survival rates of up to 98-99% over five years and beyond. However, despite their durability, these restorations face issues such as chipping, which has driven the search for alternative materials and techniques.
One such alternative is the one-piece screw-retained veneer CAD/CAM zirconia abutment. This method, particularly useful in the aesthetic zone, offers high survival rates and an appealing aesthetic outcome. Yet, it remains costly and sometimes problematic due to wear between titanium and zirconia and potential fractures.
The Move to All-Ceramic Restorations Strasding highlighted the growing use of all-ceramic restorations, which, while aesthetically pleasing, have slightly lower survival rates compared to metal-ceramics. Particularly for multi-unit restorations, survival rates can dip to around 93%, which is less than ideal in clinical settings.
The primary challenge with all-ceramic restorations is reducing chipping while maintaining quality, aesthetics, predictability, and efficiency. The industry is moving towards monolithic crowns, which are stained, glazed, or facially veneered, offering a promising solution with reduced costs and improved aesthetics.
Innovations in Material Choice The choice of materials plays a critical role in the success of dental restorations. High-strength materials such as oxide ceramics (zirconia) and lithium disilicate are at the forefront. Hybrid ceramics are also emerging, although they present more complications.
A significant development is the titanium base concept, which combines high-strength ceramic crowns with titanium bases. Preliminary studies, such as those from the University of Geneva, indicate that this approach offers mechanical stability and could be a valid treatment option. However, questions remain about the long-term interface between the crown and the titanium base.
Clinical Applications and Case Studies Strasding shared several clinical cases to illustrate the practical application of these materials and techniques. One case involved a bone level tapered implant with a lithium disilicate crown bonded to a titanium base. Two years post-operation, the patient exhibited excellent soft tissue growth and no chipping or debonding, showcasing the method's efficacy.
Another case presented a more challenging scenario in the anterior region with a high smile line. Despite some aesthetic limitations, such as a slight grey shimmer from the titanium base, the lithium disilicate crown performed well functionally.
Research and Ongoing Studies The presentation also covered ongoing clinical studies. One such study involves comparing lithium disilicate and zirconia restorations on titanium bases in patients with bone level tapered implants. Preliminary results over four years are promising, with minimal issues observed.
Another study by Professor Chara’s group in Geneva compares metal-ceramic restorations with monolithic lithium disilicate and polymer infiltrated ceramic network (PICN) materials. The findings suggest that PICN materials present more problems, such as wear and discoloration, making them less favorable at present.
Future Directions Looking ahead, Strasding emphasized the potential of monolithic restorations to reduce chipping, especially when stained and glazed or polished, and the efficiency and cost-effectiveness of using titanium bases. However, there are still open questions about long-term outcomes, debonding risks, biological impacts, and aesthetic improvements, particularly in highly aesthetic zones.
A promising future approach involves digital workflows and rapid treatment methods. For instance, intra-surgical scans and 3D printed models allow for the efficient creation of crowns that can be inserted in a single treatment phase, significantly reducing patient wait times and costs.
Conclusion In conclusion, while traditional metal-ceramic restorations remain a gold standard, advancements in monolithic materials and titanium bases offer promising alternatives that combine durability, aesthetics, and cost-effectiveness. Ongoing research and technological innovations continue to refine these techniques, paving the way for improved dental restoration outcomes in the future. As Strasding aptly put it, understanding, creating, and harnessing these changes are crucial for the continued advancement of dental practice.