Michael R. Backstrand
Backstrand, Michael R.
University of Pennsylvania School of Dental Medicine, Department of Preventive and Restorative Sciences
Dental practitioners utilize many different dental materials to fabricate strong, durable, and aesthetic fixed prostheses, including single crowns for their patients. Often times, however, the practitioners may not be considering the future treatment options of their patients or selecting the appropriate materials. In the field of orthodontics in particular, there have traditionally been concerns about the bond strength between brackets and ceramic crown materials. A wide variety of bonding materials and protocols have been developed to address the aforementioned issues with bracket placements on to the teeth. However, as the popularity of esthetic treatment options - such as clear aligner Invisalign therapy - continues to grow, there will be increased importance in extending this bonding knowledge to the application of the composite buttons utilized in clear aligner therapies. Since this bonding performance with the crown materials has been shown to be an issue in dentistry today, we investigated the most retentive ceramic-based crown material to deliver optimal composite shear bond strength for attachment buttons.Methods
A search was performed on shear bond strength of composite resin materials to three common dental fixed prosthetic materials (zirconia, lithium disilicate, and feldspathic porcelain) from November 1997 to August 2020. The research study primer application, thermocycling controlled variables, and composite resin choice was assessed.Results
Upon review, the collective studies presented contradicting results due to the lack of controlled variables. An assessment was made based on the mean shear bond strengths of the several assessments conducted on each dental material. Using this knowledge, zirconia presented a slightly higher shear bond strength than the other two materials before applying thermocycling treatment; however, some studies with differing controlled variables contradict these findings.Conclusion
Without conducting a direct research study with controlled variables comparing the three materials - with the same primer setup, thermocycling protocol, composite resin, and ceramic material - it is difficult to compare the efficacy of their individual shear bond strengths. With the current knowledge assessed from the included literature, we can assume that zirconia has the highest shear bond strength before thermocycling, while lithium disilicate is strongest when using the thermocycling assessment.