The Use of Warm Air for Solvent Evaporation in Adhesive Dentistry: A Meta-Analysis of In Vitro Studies

Abstract

Any excess solvent from dental adhesive systems must be eliminated prior to material photopolymerization. For this purpose, numerous approaches have been proposed, including the use of a warm air stream. This study aimed to investigate the effect of different temperatures of warm air blowing used for solvent evaporation on the bond strength of resin-based materials to dental and nondental substrates. Two different reviewers screened the literature in diverse electronic databases. In vitro studies recording the effect of warm air blowing to evaporate solvents of adhesive systems on the bond strength of resin-based materials to direct and indirect substrates were included. A total of 6626 articles were retrieved from all databases. From this, 28 articles were included in the qualitative analysis, and 27 remained for the quantitative analysis. The results of the meta-analysis for etch-and-rinse adhesives revealed that the use of warm air for solvent evaporation was statistically significantly higher (p = 0.005). For self-etch adhesives and silane-based materials, this effect was observed too (p < 0.001). The use of a warm air stream for solvent evaporation enhanced the bonding performance of alcohol-/water-based adhesive systems for dentin. This effect seems to be similar when a silane coupling agent is submitted to a heat treatment before the cementation of a glass-based ceramic.

Warm Air Delivery in Adhesive Application: Effect on Bonding Performance and Morphological Outcomes

“…Previous studies focused on air temperatures ranging from 37 °C to 80 °C as one of the most crucial factors of the air-blowing application [13,14,18]. Furthermore, as previously discussed, the gold-standard temperature of a warm air stream when applied to dentin should be between 50 °C and 60 °C [13]. Consequently, the 40 °C and the 60 °C were selected as the middle-level air temperatures in this present study.…”

“…Warm air temperatures between 40 • C and 60 • C were found to be effective for enhancing solvent evaporation. Nonetheless, the 60 • C temperature was better for stable BS and minimized bond breakdown [13].…”

“…Particularly, when using an air temperature of 60 • C, an increase of around 20% in the resin-dentin bonds could be detected [12]. This could be attributed to the heat from the warm air, which raises the kinetic energy of solvent molecules, facilitating the vaporization of the residual solvent and water [13]. Prior investigations have explored warm air temperatures ranging from 37 • C to 80 • C, indicating the need for determining the ideal temperature for warm air blowing [9,10,12,13].…”

“…Various methods have been proposed to improve solvent evaporation from dental adhesives, including prolonging adhesive application time, applying multiple adhesive layers, extending adhesive polymerization, and employing active adhesive application techniques. Additionally, some efforts have made in using a warm air stream to facilitate solvent evaporation [13].…”

“…This could be attributed to the heat from the warm air, which raises the kinetic energy of solvent molecules, facilitating the vaporization of the residual solvent and water [13]. Prior investigations have explored warm air temperatures ranging from 37 • C to 80 • C, indicating the need for determining the ideal temperature for warm air blowing [9,10,12,13]. Warm air temperatures between 40 • C and 60 • C were found to be effective for enhancing solvent evaporation.…”