During the adhesive luting process of ceramic res-torations, many factors may influence the adhesion between the restorative material and dental tissues. Among many protocols, the surface conditioning of glassy matrix ceramics with Hydrofluoric acid(HF) gel followed by silane application is the most often indicated method for luting resin cements.

The use of silane only without prior Hydrofluoric acid(HF) etching was shown to result in lower bond strength between ceramic and resin. Silane is responsible for chemical bonding of resin composites to ceramics, and apparently in this study, this chemical bonding alone was not sufficient to generate adequate bond strength. Although silanes can also be used to attach resin to ceramic without HF etching and the initial bond strength may be high, it deterio-rates over time due to degradation of the siloxane film. Several previous studies have concluded that etching is an essential step in adhesive cementation, and the strength of the enamel/resin-composite/ceramic bond depends primarily on the silanization of the etched ceramic surfaces.

According to Ministry of Education issued in May 2013 under the "Office of the Ministry of Education on Further Strengthening the management of dangerous chemicals on Laboratory work notice", the school's management of hazardous chemicals belong to the scope of "dangerous chemical safety regulations". According to Article 94 "dangerous chemical safety regulations" ninety-five and ninety-six, dangerous chemical accidents, resulting in bodily injury, liability according to law, and bears dangerous chemicals staff supervision and administration departments, visual serious cases criminal prosecution. Langxi currently only subject to sanctions related to principals and teachers admonishing remarks, but hydrofluoric acid damage caused by the accident to students temporarily harder conclusion, the doctor said "hydrofluoric acid injury to person is gradual increased and now we can not say absolutely no problem. "