Wetting Ability and Chemical Compatibility of Precision Impression Materials

Objective:  Hydrophilicity is critically important in the unset stage, when the material flows and is in contact with moisture on the preparation and in the oral cavity. Goal of the present study was to investigate the hydrophilicity of a polyether, a polyvinylsiloxane and two new hybrid precision impression materials. Type 2 regular set impression materials were chosen for this investigation. Their chemical compatibility was determined.

Methods: Initial contact angles were measured at room temperature at an early stage of working time (25 sec after start of mixing). A water droplet was placed on the unset material and measured using video analysis. Data was determined with a Drop-Shape-Analysis system DSA10 (Krüss GmbH, Germany) according to the method described (Berg et al. J Prosthodont 2009).  A polyether (Impregum Penta, IP, #227976, 3M ESPE), a hydrophilized vinylpolysiloxane (Honigum Mono, HM, #568576, DMG), the vinylsiloxanether (Identium Medium, IM, #80701-10, Kettenbach), and the vinylpolyether silicone (EXA'lence, EX, #810241, GC) were investigated. In addition each of the base pastes for all products were mixed in turn with the catalyst pastes for all products to determine the chemical compatibility of the materials. Mixtures were regarded as chemically compatible if they turned into rubbery products after 10 minutes at room temperature.

Results: (n=5) were analyzed by One-way ANOVA (p<0.05). Mean contact angles and standard deviations are summarized below:

HM, IM and EX were chemically compatible with each other. IP was not compatible with either HM, IM or EX.

Conclusions: Contact angles varied from 75.3° to 103.3°. HM, IM and EX displayed a hydrophobic behaviour by showing contact angles above 90°. HM, IM and EX were chemically compatible with each other, but not with IP.