Study On Preparing RTV Silicone Rubber Dental Impression Materials

RTV silicone rubber dental impression materials are superior to any traditional dental impression materials as to have the advantages of short setting time, fine reproduction of details, dimensional stability and favorable handing properties, which have resulted in their popularity in today's prosthodontic and restorative dentistry, are ideal dental impression materials. Now, in the developed countries, silicone rubber dental impressions is the preferred clinical impression materials, but in the domestic alginate dental impression material is still the most widely used, silicone rubber dental impressions are all relied on imports.In this paper, two kinds of dental impressions, condensed and additional RTV silicone rubber, were prepared. The condensed RTV silicone rubber dental impression material was prepared with α, ω-dihydroxy polydimethylsiloxane and catalyst reaction system as raw materials, adding surface-modified fumed silica filler, silica powder and liquid paraffin additives, curing agent and so on. In the presence of platinum-based catalysts, the additional RTV silicone rubber dental impression material was prepared with vinyl silicone oil and crosslinking HMSO as raw materials, adding surface-modified fumed silica filler, silica power and liquid paraffin additives, divinyl tetramethyl disiloxane as retarder and so on.Two kinds of process, "wet process" and "dry process", were used for modifying the surface hydrophobicity of fumed silica which is the reinforcing filler in silicone rubber. And the surface hydrophobicity of modified fumed silica was investigated. Effects of the different treating compounds, such as dimethyldiethoxylsilane, HMDS, KH550, KH570 etc., on the hydrophobicity of fumed silica were also investigated. Considering the product performance and cost, the results of experiments show that it is a cost-effective method using the dimethyldiethoxylsilane as a treating agent and the "dry process" surface treatment of the fumed silica.The platinum-based catalyst was synthesized with the chloroplatinic acid and divinyl tetramethyl disiloxane as raw materials by the Karstedt method. And the platinum complexes with high reactivity can serve as an appropriate catalyst for preparing dental impression materials.The properties of contrast merchandise and preparation of silicone rubber impression material were measured. The results show that the tear strength of...