A Research On Preparation And Properties Of Vinyl Polysiloxane Dental Impression Material

Silicone rubber materials are widely used in dental clinic. Recently, the interest focuses on the addition silicones. Its primary polymer is vinyl polysiloxane (VPS), which is cross-linked with hydride silicone activated by a platinum salt catalyst. The addition polymerization reaction goes fast and completely. No reaction by-products develop as long as correct proportion of vinyl silicone and hydride silicone is maintained. Therefore, the VPS materials have short setting time, minor dimensional change and excellent dimensional stability. Additionally, the network polymer is mainly constructed with Si-0 chemical bondings. The whole structure is strong enough to assure mechanical properties. Unfortunately, the well-developed industrial VPS materials cannot be used as dental material for reasons. It is necessary to specially design the VPS dental impression material according to the specified requirements. Studies on design and modification of this material never stopped for the last years in Europe and American, while it is rarely reported in China. The purpose of this study was to develop well-qualified VPS dental impression material of medium-bodied consistency. Furthermore, inorganic antimicrobial agents were added to the rubber compounds for the ability of self-disinfection.The primary formulation of VPS dental impression material came from industrial VPS mould material, and was modified according the required properties including tensile strength, rigidity and viscosity. Effects of vinyl content, hydride silicone dosage and fillers dosage on the required properties were studied so as to establish the property formulation of VPS dental impression material (HC).Properties of HC compared with other 3 silicone dental impression materials were investigated. Mixing time, consistency, working time, detail reproduction, linear dimensional change, compatibility with gypsum, elastic recovery and strain-in-compression were tested under the conditions simulating ISO 4823; tensile strength, tear strength and rigidity were tested following ASTM D624; wettability was investigated by means of sessile drop goniometry and tilting plate goniometry. Results indicated HC material was as good as the other materials, even better in some mechanical properties, except for lower wettability comparing to AFFINIS 75 MonoBody.3 inorganic antimicrobial agents were added to HC, and the resulting materials showed the ability of self-disinfection. There was no statistical difference of tested mechanical properties between antimicrobial-agent-free material and material containing Conval Pag40.In conclusion, the VPS dental impression material of HC had excellent properties; and by adding appropriate inorganic antimicrobial agent, it would get the ability of self-disinfection.