Epoxy resins for bonding orthodontic attachments to teeth.

S umm ary An epoxy resin formulation has been developed to bond orthodontic attachments to enamel sur­ faces. The disruptive force required to break the bond under experimental conditions was in excess of the forces exerted on the orthodontic attach­ ments during treatment. This formulation has been subjected to a limited number of clinical trials. These tend to substantiate the experimental findings. ANDING of teeth for orthodontic treatment provides the means of con­ necting the attachments to the teeth. This technique has certain drawbacks: it is time-consuming; the inter-dental space occupied by the band material and cement is not only a source of discomfort to the patient but may also hamper the treat­ ment; and gingival irritation and enamel decalcification are not uncommon. These disadvantages would be obviated if a suitable adhesive material was avail­ able to bond orthodontic attachments directly to enamel surfaces. Many such materials, including the epoxy resins, have been evaluated for this purpose (Bowen 1956, Newman 1965, Phillips 1966 and Mitchell 1967). The application of these resins to dental tissues, however, presents special problems. Because of the high temperature often re­ quired for curing, the toxicity of the curing agents and the length of the cure, most of them cannot readily be used intra-orally. In addition previous work has shown that optimum bonding is obtained and main­ tained only under dry conditions. I . T h e E p o x y R esins These are synthetic materials manufac­ tured from by-products of the petroleum industry, most of them by reacting epichlorohydrin with diphenylolpropane in an alkaline medium as shown below. o / \ ?H3 / ° \ H2C CK-CH2 + Cl 4h!o (__) C ( ) OJH + Cl ; CH2 CH CK2 + 2NaOH