Title:  In vitro study of penetration of flowable resin composite and compomer into occlusal fissures

Abstract:  The penetration of a sealant into the tooth fissures can establish longer retention time for a pit and fissure sealant restoration. Aim This in vitro study was to evaluate the penetration ability of two low-viscosity resin materials, a composite and a compomer, applied with and without their bonding agents in comparison to an unfilled resin sealant. Methods Forty premolars with shallow/wide (group I) and forty with deep/narrow occlusal fissures (group II) were used. Each group was divided into five subgroups (A-E). The teeth in the subgroups were sealed as follows: A - Delton LC Clear (unfilled resin); B - Dyract flow (compomer); C - Prime&Bond NT (bonding agent) and Dyract flow; D - Tetric flow (resin composite); E - Syntac Sprint (bonding agent) and Tetric flow. Longitudinal sections were cut along the mesiodistal direction of fissures and examined under a videomicroscope. The resin penetration was rated according to the scale “low”, “medium”, “high”, indicating penetration up to one third and two thirds of fissure depth and to the fissure bottom, respectively. Results These revealed the following: a) the penetration of all sealants was higher in shallow/wide than in deep/narrow fissures; b) the low-viscosity resin materials provided higher penetration than the unfilled resin sealant in shallow/wide fissures, whereas the unfilled resin achieved superior penetration rates in deep/narrow ones; c) the combination of a hydrophilic sealant (Dyract flow) with a hydrophilic bonding agent (Prime&Bond NT) significantly promoted the penetration depth in deep/narrow fissures. Conclusion The penetration ability of all sealants was higher in shallow/wide than in narrow/deep fissures; low-viscosity resin composite and compomer provided higher penetration efficiency than the unfilled resin sealant in shallow/wide fissures, whereas the unfilled resin achieved superior penetration rate in deep/narrow ones. The combination of a hydrophilic sealant with a hydrophilic bonding agent significantly enhanced the penetration depth in deep/narrow fissures.