Case analysis is an essential element for accurate definition of the scheduled restorative work, anticipation of potential problems, and development of any necessary solutions.
When a meeting with the patient at the laboratory is not feasible, for geographic reasons for instance, a photograph provides a good idea of the morphological modifications to be made for successful integration in a given type of face.
Case analysis for restoration of function and/or esthetics can take different forms: wax-up, mock-up, removable model…. This approach provides the patient with a reassuring simulation of the final result while serving as an indispensable guide for actual fabrication of the prosthesis.
One of the unquestionable advantages of CAD/CAM is the possibility to associate two dissimilar materials: a titanium base guarantees precision and a solid interface while zirconia offers excellent esthetics and biocompatibility. This combination is the response to even the most demanding requests. Whether it be a single crown or a full-arch bridge, a solution of this type exists for all implant systems using full zirconia or partially or completely layered zirconia.
Another indisputable advantage of CAD/CAM is the design and fabrication of highly accurate titanium or chromium-cobalt frameworks guaranteeing a passive fit. From the custom-made abutment to the complete screw-secured framework and the bar for a removable appliance, digital technology has become an indispensable actor in successful fabrication of implant-supported restorations. The precision and quality of a machined alloy has allowed us to make a great leap towards perfection.
Provisional prostheses can be classified in three categories depending on the moment of use: pre-implant prostheses, immediately loaded implant-supported prostheses, and prostheses installed after implant placement.
Removable dentures can be stabilized using various techniques :
In both cases, the intrados of the prosthesis is always reinforced to reduce the risk of fracture due to the difference in rigidity between the implant and the mucosal support.
CAD/CAM technologies have revolutionized metallurgy. Numerical milling procedures and the laser microfusion technique that appeared several years ago have significantly increased the possibilities for the fabrication of frameworks.
The traditional lost-wax technique remains a frequent option and, when mastered and used with quality alloys, constantly provides full satisfaction. Vacuum pressure casting, a technique we have used for many years, preserves the characteristics of the metals.
Our laboratory began working with this material as early as 2004 when it was first introduced in the dental world.
In 1789, the German chemist M.H. Klaproth discovered a new member of the family of silicate minerals. Found in igneous rocks, it was named zircon, from the Persian word zargun. The first natural accumulation was found in 1892, in Sri Lanka, by Joseph Baddeley, who gave it another name: baddeleyite. Dental zirconia or zirconium oxide (ZrO2) obtained from this mineral is purified by chemical and thermal processes; 5.15% yttria is added to stabilize its excellent mechanical characteristics.
To date, this restorative material offers the best biocompatibility and the most obvious acceptation by the tissues. Opaque in the beginning, today’s zirconia comes in a wide range of translucencies allowing satisfaction of increasingly demanding esthetic goals.
In 2002, the Zirkonzahn company supplied us with zirconia for the fabrication of 100% zirconia bridges. Although solid, the translucency and the particular color of this material permit achievement of excellent esthetic results. All surfaces in contact with the mucosa are made of polished zirconia in order to take advantage of its high biocompatibility. The masticatory surfaces are just colored to avoid the risk of “chipping”. Ceramic layering is limited to visible zones and the vestibular sector in order to obtain an even more natural-looking result.
This glass ceramic with a lithium disilicate base is unquestionably the “all ceramic” solution offering the most natural-looking results.
Its tensile strength of 400 mPa, although lower than that of zirconia, is more than sufficient even for extremely thin restorative work such as veneers, crowns, inlays and onlays. To ensure long-term reliability, we privilege its use in the anterior zone. Bonding increases the adhesive link with the support and thus its solidity.
Although lithium disilicate is compatible with CAD/CAM technologies, we prefer to use the press technique in order to increase the precision of fit.
This semicrystalline thermoplastic (polyether ether ketone) was first introduced industrially in 1978. Its resistance to wear and hydrolysis first led to adoption for vertebral and cranio-facial orthopedic surgery. This polymer was introduced in the dental world in 2010.
The biocompatibility and low density of PEEK combined with a rigidity close to that of bone make this material an option for the fabrication of implant-supported bridges. It can be associated with composite, zirconia or ceramic denture teeth for coronal areas and with a gingival mask in other sectors. Its capacity to diffuse masticatory shock waves may make it an attractive option in cases where absence of proprioception is a problem.