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Orthodontic Bonding to Unconventional Surfaces - A Review

BACKGROUND The introduction of the acid etching bonding technique by Buonocore in 1955 has led to dramatic changes in dentistry. A decade later, Newman used this concept for the use of orthodontic adhesive to bond orthodontic brackets directly onto teeth. Over the past 40 years, continuous developments in dental material sciences and bioengineering resulted in modern orthodontic bonding systems and fixed appliances. Ceramics, resin composites, dental amalgams and acrylic resins are commonly used materials in restorative dentistry and prosthodontics. Most dental ceramic and metal ceramic crowns, bridges and veneers presently are made from different feldspathic porcelains containing 10 % to 20 % aluminium oxide. However, such restorations can also be made from high-aluminium porcelains and glass ceramics. Adhesive-porcelain interface failure is the predominant mode of bond failure in all groups. Conventional acid etching is ineffective in the preparation of porcelain surfaces for mechanical retention of brackets. The most reliable procedure for bonding orthodontic brackets to porcelain surfaces is through the surface treatment combinations of three methods: sandblasting, 9.6 % hydrofluoric acid treatment and silane coupling agent application. As more adults seek orthodontic treatment, we are often faced with the challenge of bonding to restorative materials other than porcelain. The goal throughout orthodontic treatment is to maintain the appliances securely attached to their original position until the end of treatment. However, the appliances should be easily removed without causing any permanent damage to tooth structure or permanent restorations, once the treatment has been concluded. This article reviews the materials and techniques used for bonding to surfaces of restorative materials, termed non-conventional surfaces in contrast to the conventional bonding to tooth enamel. Though this requires following a detailed procedure and using both safe and effective bonding materials, the result should be a reliable bond that does not compromise the integrity of the restorative surface.