Live WebinarIntegration of the operating microscope in the workflow with CEREC
12 Dec 2019, 10:00 AM EST (New York)
Dr. Christian del Rey Schnitzler
Four years ago, Reliance released a revolutionary product, Assure Plus. On top of bonding to every artificial surface found in the mouth, one of the most attractive features of Plus, according to the company, is the ability to eliminate the intraoral use of hydrofluoric acid to etch ceramic crowns.
To the naked eye, all “ceramic” substrates look similar intraorally. The unfortunate fact is a “ceramic” surface can potentially be fabricated from lithium disilicate, porcelain, layered zirconia, monolithic zirconia and so on. In previous years, bond strength values were very poor if porcelain conditioner was applied to a zirconia surface; thus the clinician had to be confident the substrate was porcelain.
According to Reliance, there is news on the ever-developing situation of bonding to ceramic crowns. Extensive tests have shown that roughening or even sandblasting are no longer needed when using Reliance Porcelain Conditioner and Assure Plus. Furthermore, the task of differentiating zirconia from porcelain is unnecessary.
When confronted with bonding to a crown (porcelain or zirconia), the steps are as follows:
Far too often we take for granted the benefit of a thorough prophylaxis. If adapting the above bonding modality, a thorough prophy is absolutely imperative to an acceptable bond strength. The air drying of the active ingredient in Reliance Porcelain Conditioner now allows the clinician to skip the substrate identification. If the substrate is porcelain, the silane will bond to the glass filler. If the surface is zirconia, the drying and 60-second wait time allow the silane to go unutilized without interfering with Assure Plus.
Artificial but not ceramic? The remaining substrates (gold, amalgam, stainless steel, composite, acrylic) are handled with the following protocol:
Much like Assure regular, Assure Plus built its foundation on being the only primer to bond to wet or dry, normal or atypical surfaces. According to the company, atypical enamel (hypocalcified, fluorosced, aprismatic, etc.) presents a serious challenge if the clinician is not using Assure or Assure Plus. On top of all the artificial surface bonding capabilities above, the variable reducing properties on enamel are the reason offices with the lowest bond failure rates utilize Assure Plus as a full-time, everyday primer, according to Reliance.
There are only two cases where any etching step is necessary: amalgam or composite restorations. Clinicians need to eliminate the idea that phosphoric acid will simply “clean” the work surface. The reasons are two-fold: chairside efficiency and primer interference.
If there is no enamel present, etching is a waste of time and money. Furthermore, etching can be detrimental to the bonding process when bonding to zirconia. If phosphoric acid is applied to a zirconia crown to “clean the surface,” the phosphate ions will attach to the substrate and subsequently repel the primers.