Basil Mizrahi discusses modern concepts and techniques in temporaries, adhesive dentistry and aesthetic materials.
How have modern aesthetic concepts in ceramics and temporaries changed over the last few years?
With the rise of aesthetic dentistry, there has been a move towards metal-free crowns, which tend to provide improved aesthetics. We now have materials such as zirconia and lithium disilicate that have all but replaced metal cores on anterior teeth.
On posterior teeth where aesthetics is not that crucial, there is still a strong indication for traditional metal ceramic crowns. I believe these can be made to fit better and the preparations can incorporate more mechanical resistance, which then becomes the primary retentive feature rather than the cement.
Despite stronger non-metal cores, the weak link still remains the veneering porcelains that are applied over these cores and used to enhance the aesthetics. Because of this weakness, there is a move to monolithic crowns systems that eliminate the veneering porcelain layer. While these may be stronger and more resistant to chipping and cracking, their aesthetics is compromised and their clinical longevity has yet to be proved.
There has also been a large movement towards digital dentistry with digital impression and crown fabrication techniques growing in popularity. However, at the highest level, I believe traditional techniques coupled with manual dental technician skills still provide a higher level of mechanical and aesthetic precision. The choice of digital versus analogue will depend on the practice and the patient’s expectations and demands.
It is much like comparing a digitally produced picture with a hand-painted one.
With regard to temporary materials, there has been a large swing towards bis-acryl gun systems. These are more aesthetic and easier to use. However, for more complex cases and where more versatility is required, my preference is still for traditional power-liquid based acrylic resins. These aspects will be discussed in my lecture at the Irish Academy of Aesthetic Dentistry (IAAD) meeting on Friday 28 October in Cork.
In what ways have restorative materials advanced, and do new materials need different techniques to yield better results?
Sometimes dentists are sucked in by the hype of marketing and the fact that their colleagues are using the latest material that they are not. I’m a strong believer that the operator is more important than the material or the technique and this is borne out by the fact we see good clinicians achieving good results with different materials and using different techniques.
Adhesive dentistry has been a major development in allowing preservation of far more tooth structure. But modern adhesive materials are very technique sensitive and their instructions for use must be followed carefully. Dentists need to have a good understanding on how to use these materials and when these different materials should be used. If these are compromised, we may see postoperative sensitivity, stained margins and bond failure. Rubber dam should be used wherever possible when adhesive materials are used.
Despite the shift towards adhesive dentistry, it is important for dentists to be knowledgeable and skilled in traditional mechanical dentistry.
I’m concerned that the younger generation are losing the ability to precisely prepare teeth for traditional mechanically retained restorations. Handpiece control is an essential skill that needs to be acquired and constantly practised and refined. An over-reliance on adhesive cements to compensate for lack of preparation resistance form may jeopardise long-term results.
Dentists should be skilled in both adhesive and mechanically retained restorations, so that they are able to offer their patients the optimal restoration for each specific situation. This is one of the main reasons I started Mizrahi Dental Teaching (www.mizrahi-dental-teaching.co.uk). A conservative adhesive restoration that fails after three years is not preferable to a slightly more aggressive mechanically retained precision restoration that lasts 25 years!
Due to the range of materials now available, is it more important now than ever before for dentists to understand their choice of materials better?
Yes. It can be quite daunting for dentists to know which materials to use and when, and they can feel inadequate if they do not have all of the latest materials. Companies often produce newer materials in the hope that dentists will buy them, but the reality is that they may not necessarily be an improvement on the existing ones. Products are often released before they have had adequate clinical trials and dentists then become the testing laboratories.
Where do you see things headed in this area of aesthetic dentistry?
I think digital dentistry will continue to evolve and gain in popularity as will adhesive dentistry. Digital impressions will replace conventional impressions. More and more laboratory procedures will become mechanised and digital – for example, models and cores. New materials and bonding agents will continue to evolve but we need to see long-term clinical evidence of how these cements hold up.