Change in the shrinkage forces of composite resins according to controlled deflection

As a tooth restoration material, the composite resin undergoes polymerization shrinkage, and polymerization shrinkage generates polymerization shrinkage force on the teeth under confinement due to bonding to cavity walls. Clinically, polymerization shrinkage and shrinkage force can cause debonding, marginal gap formation, microleakage, secondary dental caries, post-operative hypersensitivity, and cuspal deflection. In this study, especially with regard to cuspal deflection, the author investigated how the polymerization shrinkage forces of composite resins change with change in deflection. Five composites, SDR® (Dentsply Caulk, Milford, DE, USA), EcuSphere-Shape (DMG, Hamburg, Germany), Tetric N-Ceram® Bulk Fill (Ivoclar Vivadent, Schaan, Liechtenstein), CLEARFIL™ AP-X (Kuraray Noritake Dental Inc., Sakazu, Kurashiki, Okayama, Japan), and Filtek™ Z350 XT (3M Dental Products, St Paul, MN, USA), were tested in this experiment. The polymerization shrinkage forces of the composites were measured using a custom-made tooth deflection-mimicking device and software (R & B Inc., Daejon, Korea). In all measurements, six modes were tested, comprising maximum-deflection, zero-deflection, and four deflection-controlled modes. For each deflection mode, the shrinkage forces were recorded continuously every 0.1 for 180 s. Polymerization shrinkage and flexural modulus were also measured. Eight specimens of each material were allocated for each test. For each material, six groups of shrinkage force values were compared using one-way ANOVA and Tukey's post hoc tests at a 95% confidence level. The polymerization shrinkage force of each material in each of the six deflection modes was analysed with 95% confidence using one-way ANOVA and Tukey's post hoc tests. The relationship between the force measured in the six deflection modes and the linear polymerization shrinkage and flexural modulus was analysed with 95% confidence using Pearson’s correlation analysis. For each material, the following held true: the shrinkage force was highest in zero-deflection mode, the force decreased as deflection increased, and the smallest force appeared in maximum-deflection mode (P<0.05). There was a high negative correlation between allowable deflection and shrinkage force in all materials. Polymerization shrinkage forces and the differences in such forces between composite resins decrease with increasing cuspal deflection. When high deflection is expected, controlling composite volume with a base material or use of a layer filling technique are more practical than trying to choose a composite with low polymerization shrinkage force.open박

Volumetric polymerization shrinkage of contemporary composite resins

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (;a; or = 0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87&plusmn;0.01) and Definite (1.89&plusmn;0.01) shrank significantly less than the other composite resins. SureFil (2.01&plusmn;0.06), Filtek Z250 (1.99&plusmn;0.03), and Fill Magic (2.02&plusmn;0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation

Evaluation of in-situ shrinkage and expansion properties of polymer composite materials for adhesive anchor systems by a novel approach based on digital image correlation

The curing reaction of thermosetting resins is associated with chemical shrinkage which is overlapped with thermal expansion as a result of the exothermal enthalpy. Final material properties of the polymer are determined by this critical process. For adhesive anchor systems the overall shrinkage behavior of the material is very important for the ultimate bond behavior between adhesive and the borehole wall. An approach for the insitu measurement of 3-dimensional shrinkage and thermal expansion with digital image correlation (DIC) is presented, overcoming the common limitation of DIC to solids. Two polymer-based anchor systems (filled epoxy, vinylester) were investigated and models were developed, showing good agreement with experimental results. Additionally, measurements with differential scanning calorimetry (DSC) provided supporting information about the curing reaction. The vinylester system showed higher shrinkage but much faster reaction compared to the investigated epoxy

Immediate versus water-storage performance of Class V flowable composite restoratives

Objectives The aims of this investigation were to clarify the effects of 24 h water-storage and finishing time on mechanical properties and marginal adaptation to a Class V cavity of eight modern flowable resin-composites. Methods Eight flowable composites, plus two controls (one microfilled and one hybrid composite), were investigated with specimen sub-groups (n = 10) for each property measured. The principal series of experiments was conducted in model Class V cavities with interfacial polishing either immediately (3 min) after setting or after 24 h water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of marginal-gaps was measured (and then summed for each cavity) at 14 points (each 0.5 mm apart) along the cavity restoration interface (n = 10 per group; total points measured = 140). The shear bond-strengths to enamel and to dentin, and flexural strengths and moduli data were also measured at 3 min and after 24 h water-storage. Results For all flowable composites, polished immediately after setting, 14–30 summed gaps were observed (controls: 64 and 42). For specimens polished after 24 h, a significantly (p &#60; 0.05) reduced number of 8–17 summed gaps occurred for only 3 flowable composites; whereas for 5 flowable composites there were non-significantly-different (p &#62; 0.05) numbers (11–17) of summed gaps (controls: 28 and 22). After 24 h storage, shear bond-strengths to enamel and to dentin, flexural strengths and moduli increased highly significantly (p &#60; 0.001) for all materials, except Silux Plus. Significance A post-cure interval of 24 h resulted in enhanced mechanical and adhesive properties of flowable dental composites. In a minority of cases there was also a reduced incidence of marginal-gap formation. However the latter effect may be partly attributed to 24 h delayed polishing, even though such a delay is not usual clinical practice.</p

Digital Holographic Interferometry - A New Method for Measuring Polymerization Shrinkage of Composite Materials

Polimerizacija kompozitnih materijala smatra se iznimno važnim čimbenikom dugotrajnosti kompozitnog ispuna. Kakvoća polimerizacije utječe na fizičko-mehanička svojstva, stabilnost boje, volumetrijske promjene restoracije te na biokompatibilnost samoga materijala. Neizbježna posljedica stvrdnjavanja kompozitnih materijala jest polimerizacijsko skupljanje. Iznos polimerizacijskoga skupljanja do sada se je mjerio s viπe različitih postupaka. Digitalna holografska interferometrija, opisana u ovome radu, jedini je postupak koji omogućuje da se izravno prati polimerizacijsko skupljanje u svakoj sekundi osvjetljavanja kompozitnog materijala. Vrijednosti polimerizacijskoga skupljanja dobivene ovim postupkom u okviru su veličina polimerizacijskoga skupljanja izmjerenih drugim postupcima.Polymerization of composite filling is considered to be an important factor in achieving longevity of the restorative treatment. Quality of the polymerization influences physico-mechanical characteristics, color stability, volumetric changes of restoration and biocompatibility of the material itself. Polymerization shrinkage is an unavoidable consequence of setting of the composite material. So far, it has been measured by several different methods. Digital holographic interferometry, a method described in this study, is the only procedure that enables direct monitoring of the polymerization shrinkage for every second of polymerization of the composite material. Values of the polymerization shrinkage obtained by this method correspond with the values obtained by other methods

Readout fidelity of coaxial holographic digital data page recording in nanoparticle–(thiol–ene) polymer composites

We report on an experimental investigation of nanoparticle-concentration and thiol-to-ene stoichiometric ratio dependences of symbol error rates (SERs) and signal-to-noise ratios (SNRs) of digital data pages recorded at a wavelength of 532 nm in thiol–ene based nanoparticle–polymer composite (NPC) films by using a coaxial holographic digital data storage method. We show that SERs and SNRs at the optimized material condition can be lower than 1 × 10−4 and higher than 10, respectively, without error correction coding. These results show the usefulness of thiol–ene based NPCs as coaxial holographic data storage media

Synthesis of a novel monomer “DDTU-IDI” for the development of low-shrinkage dental resin composites

ObjectiveThe current dental resin composites often suffer from polymerization shrinkage, which can lead to microleakage and potentially result in recurring tooth decay. This study presents the synthesis of a novel monomer, (3,9-diethyl-1,5,7,11-tetraoxaspiro[5,5]undecane-3,9-diyl)bis(methylene) bis((2-(3-(prop-1-en-2-yl)phenyl)propan-2-yl)carbamate) (DDTU-IDI), and evaluates its effect in the formulation of low-shrinkage dental resin composites.MethodsDDTU-IDI was synthesized through a two-step reaction route, with the initial synthesis of the required raw material monomer 3,9-diethyl-3,9-dihydroxymethyl-1,5,7,11-tetraoxaspiro-[5,5] undecane (DDTU). The structures were confirmed using Fourier-transform infrared (FT-IR) spectroscopy and hydrogen nuclear magnetic resonance (1HNMR) spectroscopy. Subsequently, DDTU-IDI was incorporated into Bis-GMA-based composites at varying weight percentages (5, 10, 15, and 20 wt%). The polymerization reaction, degree of conversion, polymerization shrinkage, mechanical properties, physicochemical properties and biocompatibility of the low-shrinkage composites were thoroughly evaluated. Furthermore, the mechanical properties were assessed after a thermal cycling test with 10,000 cycles to determine the stability.ResultsThe addition of DDTU-IDI at 10, 15, and 20 wt% significantly reduced the polymerization volumetric shrinkage of the experimental resin composites, without compromising the degree of conversion, mechanical and physicochemical properties. Remarkably, at a monomer content of 20 wt%, the polymerization shrinkage was reduced to 1.83 ± 0.53%. Composites containing 10, 15, and 20 wt% DDTU-IDI exhibited lower water sorption and higher contact angle. Following thermal cycling, the composites exhibited no significant decrease in mechanical properties, except for the flexural properties.Significance. DDTU-IDI has favorable potential as a component which could produce volume expansion and increase rigidity in the development of low-shrinkage dental resin composites. The development of low-shrinkage composites containing DDTU-IDI appears to be a promising strategy for reducing polymerization shrinkage, thereby potentially enhancing the longevity of dental restorations

Bulk-fill 복합레진 수복시 치아-수복물 계면 파괴와 관련된 중합수축, 탄성계수, 수축응력

학위논문 (박사)-- 서울대학교 대학원 : 치의과학과, 2015. 2. 이인복.Objectives. The aim of the present study was to measure the polymerization shrinkage, modulus, and shrinkage stress of bulk-fill and conventional composites during polymerization and to investigate the relationship between tooth-composite interfacial debonding and polymerization shrinkage stress of the composites. Methods. Polymerization shrinkage, dynamic modulus, and shrinkage stress of two non-flowable bulk-fill: SonicFill (SF) and Tetric N-Ceram Bulk-Fill (TNB)two flowable bulk-fill: Filtek Bulk-Fill (FB) and SureFil SDR Flow (SDR)one non-flowable conventional: Filtek Z250 (Z250)and one flowable conventional: Filtek Z350 XT Flowable (Z350F) composites were measured using custom-made instruments. Acoustic emission (AE) analysis was performed to evaluate the tooth-composite interfacial debonding during polymerization of the composites in Class 1 cavities on extracted third molars. Results. Polymerization shrinkage (%) of Z350F (3.53) at 10 min was the highest, followed by FB (3.05), SDR (2.99), TNB (2.22), Z250 (2.09), and SF (2.05). Complex shear modulus (MPa) after 20 s of light-curing was highest in SF (996.2), followed by Z250 (831.8), TNB (723.6), Z350F (553.2), SDR (421.3), and FB (334.8). Polymerization shrinkage stress values (MPa) were: Z350F (3.51), TNB (2.42), Z250 (2.38), SF (2.36), FB (2.24), and SDR (1.68). The numbers of AE events were: Z350F (12.6), TNB (7.0), Z250 (7.0), FB (6.8), SF (6.6), and SDR (6.0). Z350F showed the highest polymerization shrinkage stress and AE event number (p 0.05). Conclusions. Composites that exhibited greater polymerization shrinkage stress generated more tooth-composite interfacial debonding. In contrast to similar outcomes among the non-flowable composites (conventional: Z250, bulk-fill: TNB and SF), the flowable bulk-fill composites (FB and SDR) demonstrated lower polymerization shrinkage stress and tooth-composite interfacial debonding than did the flowable conventional composite (Z350F).Contents Abstract (in English) 1. Introduction …………………………………………………… 1 2. Materials and Methods …………………………………… 5 3. Results ……………………………………………………… 12 4. Discussion …………………………………………………… 15 5. Conclusions ………………………………………………… 22 6. References …………………………………………………… 23 Table and Figures ……………………………………………… 29 Abstract (in Korean) …………………………………………… 40Docto