Before bonding biomaterials we have to keep in mind that these parts are going to take place in a hostile environment. They may need surface pretreatments. Surface pretreatments may involve cleaning or etching process to remove contaminants and expose wettable surfaces and may require the application of primers to get chemical reactivity at the surface. Usually, phosphoric, nitric, and maleic acid are being used for pretreatments, especially for dentin and enamel. .
Selection of an adhesive exhibiting a zero contact angle when liquid is important, too. Also having a low viscosity during bonding plus being able to displace air and contaminants during application are necessary characteristics of the selected adhesive.
Using soft and hard tissue adhesives are two strategies to bond the parts together. Soft tissue adhesives are intended to be temporary and to be removed or degraded when the wound is healed. This method should be applied on a dry skin or wound surfaces by using wound dressing strips with acrylate based adhesives. But even if the surface is wet with fluid and blood, the adhesive should be able to spread and facilitate the healing. For this method cynoacrylate ester and fibrin sealant are clinically used. Cynoacrylate ester is a fluid and polymerize rapidly by a weak base such as water and NH2. It has a rapid homeostasis and strong border to tissue. Fibrin sealants involve the production of a synthetic fibrin clot as a wound covering agent. Its haemostatic adheres to the connective tissue promoting wound healing and it is biodegradable. .
Hard tissue adhesives are used to adhere prosthesis to calcified tissues like bone, tooth enamel and dentin. Many of the hard tissue adhesives are used for dental restorations. These adhesives will face a harsher environment in the mouth than the rest, since they have to deal with changing in temperature, stress, and bacteria that cause them to decay.
