Polymer-based Restorative Materials Research Articles

Дослідження сили адгезії фотокомпозитних емалевих герметиків до поверхні зуба

The purpose of the study was to compare an adhesion strength of some modern enamel sealants to the enamel of a developing tooth which occurs without adhesive preparation of tooth surface. Materials and methods. In laboratory the shear adhesion strength to human teeth enamel without adhesive system application was compared for “Fissurit FX” (VOCO), “Clinpro™ Sealant” (3M™ ESPE™) and “Jen-Fissufil” (Jendental-Ukraine LLC). 30 samples were tested on tensometric system. Tests were performed according to requirements of ISO 4049:2019 “Dentistry – Polymer-based restorative materials” and ISO 6874:2005 “Dentistry – Polymer-based pit and fissure sealants”. Results and discussion. Performed experimental studies of sealant adhesion (without the use of adhesive systems, only with acid etching) showed that it was the largest in the domestic “Jen-Fissufil” – 9.80 ± 1.17 MPa (M=10.42 MPa, min – 7.41 MPa, max – 11.07 MPa); less in “Fissurit FX” – 9.78 ± 1.33 MPa (M=9.43 MPa, min – 8.23 MPa, max – 12.62 MPa) and “Clinpro™ Sealant” – 9.55 ± 1.88 MPa (М=8.69 MPa, min – 6.35 MPa, and max – 14.73 MPa). The performed statistical tests did not reveal any significant differences between the adhesion strength in all three subgroups. Due to the changes in the concept of dental caries development and approaches to its control that have taken place in dentistry over the past 30 years, the role of enamel sealants in achieving caries control in individual and communal prevention of dental diseases has significantly increased. The tendency to expand the indications for the use of photocomposite enamel sealants in clinical practice is also worth noting. In addition to their direct purpose, the materials can be used for “repair” and restoration of individual photocomposite fillings with minor wear and used as a lining material for the restoration of teeth with carious cavities with a high C-factor. Conclusion. In modern dentistry the use of enamel photocomposite sealants is one of the most effective and reliable methods of preventing caries of the occlusal surfaces of teeth. The study of shear adhesion to acid-etched enamel for photocomposite materials “Fissurit FX”, “Clinpro™ Sealant” and “Jen-Fissufil” did not reveal any significant differences. The technology of composite tooth enamel sealants is currently successful in clinical practice and continues to improve and develop. The development of new and quality improvement of such materials is an urgent issue for science and technology

Technique for simple apatite coating on a dental resin composite with light-curing through a micro-rough apatite layer.

Tooth root surfaces restored with dental resin composites exhibit inferior biocompatibility. The objective of this study was to develop a simple technique for coating apatite onto a resin composite to improve its surface biocompatibility. First, we fabricated a polymer film coated with a micro-rough apatite layer and pressed it (coating-side down) onto a viscous resin composite precursor. As a result of light-induced curing of the precursor through the overlaid film, the micro-rough apatite layer was integrated with the resin composite and, thus, transferred from the polymer film surface to the cured resin composite surface as a result of the difference in interfacial adhesion strength. The transferred apatite layer attached directly to the cured resin composite without any gaps at the microscopic level. The adhesion between the apatite layer and the cured resin composite was so strong that the layer was not peeled off even by a tape-detaching test. The flexural strength of the resulting apatite-coated resin composite was comparable to that of the clinically used resin composite while satisfying the ISO requirement for dental polymer-based restorative materials. Furthermore, the apatite-coated resin composite showed better cell compatibility than the uncoated resin composite. The present apatite coating technique is well suited for dental treatment because the coating is applied during a conventional light curing procedure through simple utilization of the apatite-coated polymer film in place of an uncoated film. The proposed technique represents a practical evolution in dental treatment using light-curing resin composites, although further in vitro and in vivo studies are needed.

Development of Bis-GMA-free biopolymer to avoid estrogenicity

ObjectiveAlthough bisphenol A-glycidyl methacrylate (Bis-GMA)-based dental materials are widely used in dentistry, Estrogenicity from released bisphenol A remains a concern due to possibility of adversely affecting the growth of children and homeostasis of adults. Here, a new family of isosorbide-derived biomonomers were synthesized and experimentally utilized as a matrix of dental sealants to provide physico-mechanical and biological properties comparable to those of a conventional Bis-GMA-based material but without the the potential estrogenicity. MethodsAfter synthesis of isosorbide-derived biomonomers (ISDB) by light polymerization, an experimental dental sealant with different silica filler concentrations (0–15wt%) was characterized and compared to a commercially available Bis-GMA-based sealant. Cytotoxicity and estrogenicity assays were conducted with human oral keratinocytes and estrogen-sensitive MCF-7 cells, respectively. ResultsISDB-based dental sealants exhibited typical initially smooth surfaces with depth of cure, Vickers hardness, compressive strength/modulus, water resorption/solubility, and flowability comparable to those of the commercial sealant and met the ISO standard for dental sealants and polymer-based restorative materials. Indirect cytotoxicity tests using an extract showed comparable viability among experimental ISDB-based materials and a commercial Bis-GMA-incorporated control. DNA synthesis in MCF-7 cells (a marker of estrogenicity) and the release of bisphenol A under enzymatic incubation were not detected in ISDB-based materials. SignificanceIn conclusion, the comparable physico-mechanical properties of ISDB-based materials with their cytocompatibility and lack of estrogenicity suggest the potential usefulness of ISDBs as a newly developed and safe biomaterial.

Bisphenol A in human saliva and urine before and after treatment with dental polymer-based restorative materials.

The aim of this study was to quantify bisphenol A (BPA) concentrations in saliva and urine before and after treatment with dental polymer‐based restorative materials to assess if placement of this material is associated with increased BPA levels in saliva and urine. Twenty individuals in need of at least one dental restoration with polymer‐based restorative material were included in this study. The participants were instructed to abstain from eating, drinking, and brushing their teeth for at least 10 h prior to sampling. Saliva and urine were collected before and 10 min (saliva only), 1 h, 24 h, and 1 wk after treatment. Samples were stored at −80°C before analyses. BPA in saliva and urine was determined with liquid chromatography/mass spectrometry. Linear mixed effects regression models were used for statistical analyses. There was a statistically significant increase of salivary BPA concentration directly after placement of the dental polymer‐based restorations. Following placement, the concentration of BPA decreased exponentially with time. One week after treatment the BPA level in saliva was only marginally higher than before treatment. In urine, no statistically significant change of the BPA concentration was detected after treatment.

Effects of surface properties of polymer-based restorative materials on early adhesion of Streptococcus mutans in vitro

ObjectiveWe investigated the effects of the surface properties of polymer-based restorative materials on early adhesion of Streptococcus mutans (UA159) in vitro. MethodsFour direct polymer-based restorative materials, including a nanoparticle restorative (Filtek™ Z350, 3M ESPE, USA), a nano hybrid universal restorative (Filtek™ Z250 XT, 3M ESPE, USA), a low shrink posterior restorative (Filtek™ P90, 3M ESPE, USA) and a polymer-based pre-reacted glass ionomer (Beautifil II, Shofu, Japan), were selected. After polishing under different conditions, surface morphology was examined using scanning electron microscopy. Surface roughness (SR), water contact angle (CAW) and surface free energy (SFE) were determined by profilometry and the sessile drop method. Early adhesion of S. mutans was investigated using confocal laser scanning microscopy. The area occupied by adherent bacteria (A%) was calculated with COMSTAT2 software. The correlations between A% and SR, CAW, and SFE were analyzed by linear regression using SPSS 20.0 software at a significance level of 0.05. ResultsThe value of A% was strongly correlated with SR (r=0.893, P<0.01) for surface roughness (Ra) of 0.02–0.80μm, whereas a weaker correlation was obtained between A% and SR when Ra≤0.20μm (r=0.643, P < 0.01). On super smooth surfaces (0.02μm≤Ra≤0.06μm), SR did not influence early bacterial adhesion (r=0.001, P>0.05), a medium positive correlation between A% and SFE was obtained (r=0.426, P<0.01), and no correlation between A% and CAW was found (r=−0.028, P>0.05) ConclusionsEarly adhesion of S. mutans on direct polymer-based restorative materials was mainly affected by SR. SFE influenced early adhesion of S. mutans on super smooth surfaces, while hydrophobicity did not.