Adhesion of dental ceramic materials to titanium and titanium alloys: a review

In recent years, the application of titanium and its alloys for production of metal frameworks for metal–ceramic fixed partial dentures (FPDs) has been increasing. They are fabricated mainly by casting, CAD/CAM milling and selective laser melting. Manufacturing technologies affect the surface characteristics of the metal, which in turn affects the adhesion in the metal–ceramic system. Therefore, the purpose of the present article is to analyse the information about the adhesion of dental ceramics to pure titanium and its alloys, emphasizing the methods most commonly applied to improve adhesion. Based on the papers published last 10 years, the pure titanium and its alloys, the main technologies for their production and the porcelains applied in the fabrication of metal–ceramic FPDs are examined. It is summarized that the methods for increasing the adhesion strength of the porcelains to the titanium and Ti alloys can be classified into five large groups: mechanical, physical, chemical methods, application of bonding agents and combined treatments, as clear boundaries between them cannot be set. In the last decade, the successful technologies for improving the adhesion strength of Ti and its alloys to the porcelain usually consist of a combination of successive treatments of the metal surface. Abrasion of the titanium surface by sandblasting is most often used initially. At the next stage, a bonding agent or other type of intermediate layer of different coatings is applied to the metal, which further improves the adhesion strength to the porcelain.