Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material

STATEMENT OF PROBLEM: Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. PURPOSE: This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. MATERIAL AND METHODS: Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. RESULTS: The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. CONCLUSION: Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

Tensile bond strength between elastomeric impression materials and tray resins depending on the thickness of the tray adhesive / 대한치과보철학회지

STATEMENT OF PROBLEM: Elastomeric impression materials have been widely used to obtain an accurate impression. However there have not been enough studies on the influence of the thickness of the tray adhesives on the bonding strength between the trays and the elastomeric impression materials. PURPOSE: In order to understand the relationship between the thickness of the tray adhesive and the tensile bond strength and to suggest the thickness at which the bonding strength is strongest, tensile bond strength related to the thickness of adhesives of 3 different elastomeric impression materials were tested. MATERIALS AND METHODS: 3 impression materials, Permlastic(R) Regular Set(Kerr Corp., Romulus, Michigan, U.S.A.), Impregum(TM) Penta(TM)(3M ESPE, Seefeld, Germany), and Aquasil Ultra Monophase Regular Set Smart Wetting(R) (Dentsply Caulk, Milford, Delaware, U.S.A.), were used in this study, and tray adhesives from the same manufacturers of the impression materials were used, which were Rubber Base Adhesive, Polyether Adhesive, and Silfix, respectively. The tray specimens were prepared by autopolymerizing the tray material(Instant Tray Mix, Lang, Wheeling, Illinois, U.S.A.), and a PVC pipe was used to house the impression material. In group A, tray adhesives were applied in multiple thin layers of 1 to 5 and in group B, adhesives were applied only once, in the thickness equivalent to several applications. Lightness(L*) of the adhesion surface was measured with a spectrophotometer (CM-3500d, Konica Minolta, Sakai, Osaka, Japan). The tensile bond strength of the elastomeric impression material and the tray resin was measured with universal materials testing machines(Instron, Model 3366, Instron Corp, Nowood, Massachusetts, U.S.A.). A formula between the number of adhesive application layers and the lightness of the adhesion surface was deduced in group A, and the number of adhesive layers in group B was estimated by applying the lightness(L*) to the deduced formula. RESULTS: 1. In group A, a statistically significant increase in tensile bond strength appeared when the number of application layers increased from 1 to 2 and from 4 to 5, and no significant difference was present between 2, 3, and 4 layers in Permlastic. In Impregum, the tensile bond strength was significantly increased when the number of adhesive layers increased from 1 to 3, but no significant difference after 3 layers. In Aquasil, the tensile bond strength significantly increased as the number of application layers increased up to 4 but showed no significant difference between 4 and 5. 2. In group B, the tensile bond strength was decreased when the thickness of the adhesive increased in Permlastic. Impregum showed an increased tensile bond strength when the thickness of the adhesive was increased. In Aquasil, the tensile bond strength increased as the number of adhesive application layers increased up to approximately 2.5 layers but it sharply decreased after approximately 4.5. CONCLUSION: From the study, the common idea that it is better to apply a thin and single coat of tray adhesive needs correction in more detailed ways, and instructions on some of the tray adhesives should be reconsidered since there were several cases in which the tensile bond strength increased according to the increase in the thickness of the adhesives.