The evolution of dentistry with new technology and techniques are applied for preservation of tooth structure (1). Resin infiltration is a relatively new treatment material appeared in dentistry 2008 (2), and acts through a micro infiltration technology (3), postponing as long as possible the transition from initial demineralization to actual cavitations (4), giving back the characteristics similar to the adjacent sound enamel (5).
The concept of caries infiltration resinous material is to fill the gap between prevention and restoration (6). It was first developed at the charite Berlin as a micro-invasive technique for management of initial caries lesion with marketing name ICON (DMG America Company, Englewood, NJ) (7). The principle of resin infiltration Icon is depending on the high penetration capability into the given porous lesion through capillary forces (8).
The in-vitro study which conducted by Paris S et al (9) to assess the penetration co-efficient of the ICON'' resin material in comparison to a commercially available adhesive has shown that the mean maximum penetration depth and penetration percentage was significantly higher for the infiltrant (ICON'') compared to the adhesive. Also Meyer et al (10) tested and compared the efficacy of three different etching gels in removing the surface layer. The etching gels that used were 37% phosphoric acid and two experimental HCl gels for varying applications times. The study demonstrated that 15% hydrochloric acid was more effective than 37% phosphoric acid in surface erosion and creating porosity to enable the infiltration .All those data were limited to the evaluation of resin infiltrant on enamel lesion only. Until the effect of resin infiltration in exposed dentin surface was tested by Paris et al (11), They assessed and evaluated the effect of caries infiltration technique on the infiltration patterns of proximal caries lesions differing in ICDAS (International Caries Detection and Assessment System) classification. They concluded that the resin infiltration penetrated deeply in all the demineralized parts, but no significant difference in percentage infiltration of demineralized enamel of various ICDAS codes, they also stated that Caries Infiltrant was a low viscosity resin capable of penetrating several ''m into dentin.
Several in vitro studies were conducted on cavitated and non-cavitated proximal and smooth surface lesions to test and compare the infiltration pattern between available adhesive systems with Icon and measure shear bond strength on sound and demineralized enamel (12, 13, 14). Also, clinical trials on non-cavitated proximal carious lesions extended up to the outer third of dentin, using caries infiltration in combination with non-operative procedure compared with non-operative measurement alone (15,16). Of all the studies that had been done with resin materials' infiltration capacity and ability of those materials in prevention of secondary demineralization (secondary caries), some showed promising results (17, 18), and some concluded that further research was required (19, 20, 21). A question arisen can we use Resin infiltrant as adhesive system?
Therefore this study was carried out to evaluate the effect of low viscosity resin (caries infiltrant) on dentin substrate compared with Etch and Rinse and Self-Etch adhesive systems on microtensile bond strength of direct resin composite.
materials anD methoDs
Materials which are used in the present study have been illustrated in table (1) sample preparation
Thirty molar teeth were selected for this study. All collected teeth were extracted for therapeutic reasons from patients of age group (35-45 years). The selected teeth were free of caries, cracks and showed no apparent hypoplastic defects. The selected teeth were thoroughly cleaned from calculus, tissue deposits, polished with pumice and rotating brush at conventional speed. The teeth were
TABLE (1) Materials used in the study.
Material Content Manufacture
(ICON) Tetra-ethylene glycol di-methacrylate(TEGDMA), HEMA additive, Initiator
Icon etch 15% hydrochloric acid gel
Icon dry: solution ethanol 100% DMG (America 242 south dean street, Engle wood, NJ 07631
www, dmg.america.com) Icon Etch, DMG, Hamburg, Germany).
( Icon Dry, DMG, Hamburg, Germany ).
All-bond Universal Phosphate monomer MDP, Bis-GMA, HEMA, ethanol, nanofiller, initiator Bisco; Schaumburg, IL www.bisco.com 1-800-247-
(Nano hybrid composite) Bis-GMA, UDMA, Bis-EMA, PEGDMA, and TEGDMA
Fillers were a combination of surface modified zirconia/ silica and 20nm surface modified silica particles. The inorganic filler loading is 81.8% by weight (67.8% by volume) with a particle size of nm for silica and 0.1-10 microns for zirconia/silica. 3M ESPE, Dental products, lot#20030509 St.Paul, M N55144-
Etching gel 37% phosphoric acid, 5% xanthium gum, and water,benzalkoium chloride. (Etch-37 TM w/BAC) Pentron Clinical Technologies, LLC.
stored in saline solution at room temperature until the time of their use.
A specially fabricated cylindrical, split Teflon mould of 19mm height, 22mm external diameter and 17mm internal diameter was used for the fabrication of acrylic resin blocks. Each tooth was vertically embedded into self-curing acrylic resin* up to the level of the cervical line with their occlusal surface being parallel to the acrylic resin base. (22).
The occlusal enamel of teeth were removed perpendicular to the long axis of teeth, parallel to the acrylic resin base to expose flat dentin surface at a standardized depth. The occlusal tables were ground with a rotary grinding milling machine using #180-grit silicon carbide paper** under continuous water coolant to create a uniform thickness of smear layer. (22).
* Acrostone Dental Factor, England
The teeth were divided into three main groups of 10 teeth each; according to the 3 materials used namely; Etch and rinse adhesive system***, self-etch adhesive system 2 and resin infiltrant****. experimental groups
Group A1 control (Etch & rinse adhesive)
** Gamberini s.r.1, Via Della Bastia, Caslecchio Di Reno, Italy
*** All-bond Universal, Bisco
***** Etch-37 TM w/BAC
The flat dentin occlusal surfaces were etched using 37% semi-gel phosphoric acid with Benzalkonium Chloride***** for 15 seconds, rinsed for 10 seconds, and blotted dry with absorbent sponge pellet leaving the dentin surface visibly moist. Two consecutive coats of adhesive system (All-bond Universal) were applied using a fully saturated brush tip and gently air-thinned for 5 seconds leaving a shiny surface and then polymerized with a light-emitting diode (LED) light curing unit for 20 seconds according to the manufacturer's instructions
Group A2 (Self-etch adhesive):
The All-bond Universal was applied according to manufacturer instructions. Two coats of adhesive were applied, air dried and light cured for 10 s using light-emitting diode Light Curing unit.*
Group A3 (ICON) application
The flat dentin surfaces were etched with 15% hydrochloric acid gel* for 2 min and then rinsed with water for 30 s. The surface was dried with ethanol**, applied for 30 s. Then, the low viscosity Infiltrant resin*** was applied on the surface for 3 min with a spo...
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