To evaluate the properties of self-adhesive restorative materials used as sealants in comparison with sealants with hydrophobic or hydrophilic monomers.
The self-adhesive materials tested were Fusio (FS) and Vertise-Flow (VF) and the sealants Embrace Wetbond (EM/hydrophilic) and Helioseal-F (HS/hydrophobic). The properties tested were: (a) degree of cure (%DC, n : 5, ATR-FTIR), (b) extent of oxygen inhibition ( n : 5, transmission optical microscopy), (c) flow ( n : 5, ASTM D-4242 method), (d) hardness (VH 0.2kp/10s dry/1 w in water), (e) adaptation, microleakage and fissure penetration ( n : 10, 1% fuschin dye, reflection optical microscopy and ESEM). Statistical analysis was performed by one-way ANOVA plus Tukey test (a–d), Fisher’s exact and Kruskal–Wallis plus Tukey tests (e) at a 95% confidence level.
VF showed the highest %DC(76.1) followed by HS(68.7) and EM(61.3), FS(59.2). HS demonstrated the highest extent of oxygen inhibition (23 μm vs. 13–10 μm of the rest). EM and HS exhibited the greatest flow, followed by FS and VM. The VHN (0.2kp/10s) ranking before and after 1week water exposure was FS≥VF > EM≥HS. Water storage increased VF and reduced HS values. The lowest adaptation and microleakage scores were found in HS. FS and VF after alumina sandblasting showed the worst adaptation and leakage scores, that were improved after acid-etching. Improved fissure penetration was found in HS, EM and FS, VF after acid-etching.
Although the self-adhesive materials presented improved setting characteristics, their low flow affected fissure penetration capacity. When combined with enamel acid-etching, adaptation and microleakage scoring were substantially improved in comparison with enamel sandblasting. The sealant with the hydrophobic monomers demonstrated the best sealing characteristics.
Full retention and adaptation of pit and fissure sealants have long been considered of paramount importance for their clinical efficacy in reducing occlusal caries . Over the years, many efforts have been undertaken, to improve these properties by non-invasive methods including sandblasting and chemical drying of enamel , application of bonding agents , use of flowable composites and compomers as sealants and employing sealants with hydrophilic monomers . As these developments have been mostly tested in vitro, there is still a controversy on their clinical relevance and efficacy.
Recently, self-adhesive flowable composites have been introduced mainly for cavity lining and restorative purposes. These materials do not require cavity pretreatment, as their resin matrix contains adhesive monomers mediating bonding with dental hard tissues. The easy handling characteristics and simple application procedures expanded their indications to other fields, including pit and fissure sealing.
The aim of the present study was to comparatively evaluate the laboratory performance of self-adhesive flowable liners and restoratives in a series of properties considered important for pit and fissure sealants. The null hypothesis was that the self-adhesive materials do not demonstrate differences in setting characteristics, flow and sealing capacity from conventional sealants.
Materials and methods
The materials tested are listed in Table 1 . EM is a sealant containing hydrophilic monomers for application on slightly moist, acid-etched enamel surface. FS is a self-adhesive material; when used as a pit and fissure sealant it should be placed on slightly moist enamel surface, following air-abrasion or acid-etching. HS is a conventional hydrophobic sealant applied on dry, acid-etched enamel. VF is a self-adhesive restorative; as a sealant it should be placed on dry air-abraded or acid-etched enamel. For EM and HS, static application is recommended (simple extrusion of sealant from the needle tip), whereas for FS and VF, dynamic application is suggested by rubbing each material onto enamel surface.
|Product (Batch)||Code||Description/composition a||Manufacturer|
|EM||Hydrophilic sealant, static application b
Resin: UEDMA, BMEP, HEMA, TMPTMA, H 2 O,
Fillers: SiO 2 , NaF (37 wt%).
|FS||Self-adhesive liner, dynamic application
Resin: UEDMA,TEGDMA, HEMA, 4-MET, catalysts.
Fillers: Silanated Ba-glass, SiO 2 (65 wt%).
|Pentron Clinical, Orange, CA, USA|
|HS||Conventional Sealant, static application
Resin: UEDMA, BisGMA, TEGDMA, catalysts.
Fillers: FSiO 4 -glass, SiO 2 , TiO 2 (41 wt%).
|Ivoclar Vivadent, Schaan, FL|
|VF||Self-adhesive restorative, dynamic application
Resin: GPDMA, HEMA, BisGMA, catalysts.
Fillers: Prepolymers, silanated Ba-glass, SiO 2 ,YF 3 (70 wt%).
|Kerr, Orange, CA, USA|