Utilization of an Er,Cr:YSGG Laser for the Removal of All-Ceramic Restorations
Patrick J. Broome, DMD, MBA
Adhesive bonding lies at the core of aesthetic dentistry and involves various restorative materials that can be used to “mimic” nature. When the removal of a bonded porcelain restoration is necessary, a high-speed handpiece with a diamond bur has been the only option for clinicians to facilitate removal and reveal the remaining tooth structure. By using minimally invasive laser technology, however, the clinician may remove a bonded restoration without cutting it off by simply reversing the light- or dual-cure resin chemical reaction. Feldspathic and/or pressed ceramic restorations can be removed via an Er,Cr:YSGG laser, which selectively interacts in water molecules in the adhesive resin and hybrid zone.
Laser energy passes through the porcelain glass unaffected and is absorbed by the water molecules present in the adhesive. Clinical observations indicate that the de-bonding occurs at the silane-resin interface since the denatured resin remains attached to the tooth structure and the restoration debonds without any residual resin attached to its inner surface. The water molecules are selectively excited, thus causing delamination of the restoration. Once bond failure occurs, the restoration can be removed—often in one piece—and the original preparation may be accessed without underlying tooth structure removal. Residual resin can be easily removed with a polishing cup or point. Thus, this achieves selective reversal of the adhesive bond with the Er,Cr:YSGG laser.
This technique can save a significant amount of chairtime and reduce patient and dentist anxiety. Typical de-bonding time for feldspathic veneers is between 5 and 30 seconds per restoration for complete removal. Pressed ceramics require 20 seconds to two minutes per restoration due to increased porcelain density and interproximal material thickness. Another benefit of this removal technique is improved laboratory communication. Fractured restorations can be removed and forwarded to the laboratory for an exact shade match.
Since the laser energy must penetrate through the porcelain and reach the silane-resin layer to effectively de-bond the restoration, the presence of an opaque layer will reduce the amount of light energy that will reach the adhesive layer, thus increasing the time or energy required to excite the water molecules. Restorations with dense cores such as alumna, zirconium and metal will completely block laser energy from reaching the bond interface and require removal via traditional methods.