Dyract AP Research Articles

Fluoride release and recharge in giomer, compomer and resin composite

Objectives. The aim of this study was to examine the fluoride recharging and releasing abilities of resin-based materials containing fluoridated glass filler to determine whether the extent of the glass–ionomer matrix of the material affects these properties. Methods. Three materials having a different proportion of the hydrogel matrix surrounding the glass filler, namely: Reactmer paste, Dyract AP and Xeno CF, were used for this study. Five disk specimens of each material were placed into distilled/deionized water and the fluoride release measured during 38 days. For fluoride recharge the disks were exposed to 250 ppm F solution for 1 h and the pre- and post-recharge fluoride release were determined using an ion-selective electrode (total fluoride ions) and ion chromatography (free fluoride ions). Results. The amounts of total and free fluoride release from each material at the initial period in descending order were Reactmer paste>Dyract AP>Xeno CF ( p<0.05, ANOVA and Scheffe's test). After fluoride recharge, Reactmer paste showed a greater amount of fluoride release than the other materials. Dyract AP and Xeno CF showed a similar total level of fluoride release after recharging. For Xeno CF the amount of total fluoride released after recharging was significantly greater than that of free fluoride, but there was no significant difference between total and free fluoride released after recharging for Dyract AP ( p=0.05, paired t-test). Significance. These results suggested that the extent of the glass–ionomer matrix of the glass filler played an important role for fluoride-releasing and recharging abilities of the resin-based materials.

Effects of Dietary Acids on Surface Microhardness of Various Tooth-colored Restoratives

The aim of this in vitro study was to investigate if surface microhardness of Fuji IX GP, Vitremer, Dyract AP, and Prodigy is influenced by conditioning in aqueous solutions of lactic, orthophosphoric, citric, and acetic acids against bidistilled water (which was used as control). The pH values of acids used in this study were representative of dietary acids. All specimens were stored in bidistilled water for one week and then conditioned in the respective test solutions for another week. Citric (p<0.05) and acetic acids reduced, while lactic and orthophosphoric acids (p<0.05) increased the microhardness of both Fuji IX GP and Vitremer. On the other hand, microhardness of both Dyract AP and Prodigy was significantly reduced by all acidic media (p<0.05). The observed differences in the surface microhardness of various tooth-colored restorative materials conditioned in several media varied not only with the pH but also the nature of the acidic solution, and with the composition of the evaluated material.

Measurements of shrinkage stress and reduction of inter-cuspal distance in maxillary premolars resulting from polymerization of composites and compomers

The purpose of present study was to evaluate the polymerization shrinkage stress and cuspal deflection in maxillary premolars resulting from polymerization shrinkage of composites and compomers. Composites and compomers which were used in this study were as follows: Dyract AP, Z100, Surefil. Pyramid, Synergy Compact, Heliomolar, Heliomolar HB, and Compoglass F. For measuring of polymerization shrinkage stress, Stress measuring machine (R&B, Daejon, Korea) was used. One-way ANOVA analysis with Duncan's multiple comparison test were used to determine significant differences between the materials. For measuring of cuspal deflection of tooth, MOD cavities were prepared in 10 extracted maxillary premolars. And reduction of intercuspal distance was measured by strain measuring machine (R&B, Daejon, Korea) One-way ANOVA analysis with Turkey test were used to determine significant differences between the materials. Polymerization shrinkage stress is Heliomolar, Z100, Pyramid (P Z100, Heliomolar, Heliomolar HB, Synergy Compact Surefil. (P 0.05).

Comparative SEM evaluation of penetration of adhesive systems in human dentin with a non-rinse conditioner and a self-etching primer

The purpose of this study was to compare the effect of a self-etching primer and a non-rinse conditioner with the effect of a conventional adhesive system on the penetration depth in dentin of human teeth, using scanning electronic microscopy (SEM). Fifteen human third molar teeth were sectioned into 2 pieces. All pieces were flattened with grade 600 to 1200 silicon carbide paper and divided into 6 groups: group 1 - Prime & Bond NT (NT), negative control; group 2 - 37% phosphoric acid + Prime & Bond NT (PANT), positive control; group 3 - Non-rinse Conditioner (NRC) + Prime & Bond NT (NRCNT); group 4 - NRC + Prime & Bond 2.1 (NRCPB); group 5 - NRC + Scotchbond MP (NRCSB); group 6 - Prompt L-Pop (PLP). All teeth were covered with Dyract AP. The tooth fragments were decalcified, and its resin replicas were evaluated by SEM by three previously standardized examiners. The penetration was scored from 0 (no penetration) to 3 (maximum penetration). The Kruskal-Wallis and Mann-Whitney U tests (p<0.05) showed three statistically homogeneous groups: (NT, NRCPB, NRCSB and PLP), (NRCNT) and [PANT]. The authors concluded that the self-etching primer and the non-rinse conditioner provide a lower penetration depth in human tooth dentin than the conventional adhesive system.

Time-dependent strength and fatigue resistance of dental direct restorative materials.

Elastic modulus (EM), initial fracture strength (FS) and flexural fatigue limit (FFL) of dental restorative materials were measured in a simulated oral environment to correlate mechanical response under the influence of water with the chemical nature of the test materials under investigation. One resin composite (RC; Tetric Ceram, Ivoclar-Vivadent Corp., Liechtenstein), an ion-leaching resin composite (ILRC; Ariston pHc, Ivoclar-Vivadent Corp., Liechtenstein) a compomer (CO; Dyract AP, Dentsply Corp., USA) and a glass-ionomer cement (GIC; Ketac Molar, 3MEspe Corp., Germany) were tested. Static EM, FS and dynamic FFL experiments were performed. The FFL was determined under cyclic loading for 10(5) cycles in terms of a staircase approach. The materials were stored for 1, 8, 30, 90 and 180 days in 37 degrees C distilled water, respectively. The RC degraded over time due to water adsorption followed by failure within the resin matrix. The ILRC suffered from a pronounced decrease in FS as well as in FFL due to a constant ion-leaching and macroscopic crack growth. CO failed over time due to resin-filler interface cracking. The GIC exhibited improved mechanical performance over time due to a post-hardening mechanism. The results reveal the necessity for substantial preclinical evaluation of direct restorative materials. The material parameters under investigation are capable of predicting clinical performance over time.

Sliding wear of 19 commercially available composites and compomers

Objectives. The aim of this study was to determine the influence of particle size, particle material and morphology on the sliding wear of 19 light curing, commercially available composites (Durafill VS, Metafil CX, Heliomolar RO, Solitaire, Arabesk, Artglass, Charisma F, Pertac II, Charisma, Degufill Ultra, TPH Spectrum, Z100, Tetric classic, Pertac Hybrid, Estilux Hybrid, Dyract AP, Compoglass F, Compoglass and Hytac). Methods. The materials were applied to an aluminum sample holder (7.5 mm diameter, 2 mm depth) in one layer and polymerized in a Dentacolor XS light curing unit for 180 s. The surface was ground flat (#1000) to remove any matrix rich surface layer. Then samples were stored in Ringer's solution for 24 h at 37 °C. Occlusal contact wear was simulated in a sliding wear tester (Munich Artificial Mouth). Eight specimens of each material were tested in a pin-on-block design with oscillating sliding of a Degussit antagonist (5 mm diameter) at a vertical load of 50 N. The horizontal excursion of the antagonist was 8 mm. Wear was quantified by a replica technique every 6000, 10,000, 30,000 and 50,000 cycles using a 3D-laser scanner. The materials were compared by their mean wear after 50,000 cycles. Comparisons of different composites and compomers were performed using analysis of variance and t-tests including the Bonferroni correction. Results. The microfiller composites (Durafill VS, Metafil CX, Heliomolar RO) revealed the lowest, and the compomers (Dyract AP, Compoglass F, Compoglass and Hytac) showed the highest contact wear ( p<0.05). The wear of the hybrid composite (Estilux Hybrid) and the micro hybrid composites (Solitaire, Arabesk, Artglass, Charisma F, Pertac II, Charisma, Degufill Ultra, TPH Spectrum, Z100, Tetric classic, Pertac Hybrid) was higher than that of the microfiller composites ( p<0.05). The results showed additional significant differences within the three groups of composites. The coefficient of determination between loss of height and maximum particle size was r 2=0.41. Significance. Both particle size and morphology have a high influence on the wear properties concerning the two-body wear in the occlusal contact area.

The effect of curing with plasma light on the shrinkage of dental restorative materials.

Commercially available light activated dental composites were used in this study to compare the shrinkage following curing with plasma light (Apollo95E, DMDS) and a convention halogen dental curing light (Prismetics Lite II, Dentsply). Polymerization shrinkage was determined by measuring the strain in one dimension by means of a contacting transducer. The percentage linear shrinkage were: Spectrum H = 1.84 + 0.31, P = 1.49 + 0.35*; Ana aesthetic H = 2.04 + 0.38, P = 1.85 + 0.27; Esthet.x H = 1.66 + 0.28, P = 1.69 + 0.25; Dyract AP H = 2.39 + 0.33, P = 2.18 + 0.35*; Apollo Restore H = 1.88 + 0.36, P = 1.42 + 0.33*; Surefil H = 0.88 + 0.28, P = 0.99 + 0.30 where * = significantly different, t-test at P < 0.05. The results suggested that there was less shrinkage when curing some, but not all, materials using the plasma light, although this could be attributed to a reduced level of polymerization.

The effect of different power densities and method of exposure on the marginal adaptation of four light-cured dental restorative materials

Purpose: To determine whether marginal adhesion is sensitive to different irradiation parameters, we investigated the in vitro adhesion values of four dental resins on metal surfaces. Methods: Four groups of eight specimens each of Z250, Filtek flow, Dyract AP and Dyract flow were placed in pre-treated stainless steel cavities and irradiated using different methods of exposure. The curing lights used were a Spectrum 800 halogen curing light at settings of 800 and 450 mW/cm 2 and an Optilux 501 ramping light. The maximum amount of push-out force required to displace the resin from the metal cavity was equated with adhesive value (shear bond strength). Comparisons (ANOVA, p<0.0001) were made within the same material and between the different materials when using different curing protocols. Results: Significant lower bond strengths were recorded when curing was done by gradually increasing the intensity (ramping method) compared to curing with the fixed intensities ( p>0.0001) Comparing the fixed intensities, significant lower bond strength values were obtained at 800 mW/cm 2 compared to 450 mW/cm 2 ( p<0.0001). For all exposures, the two flowable materials demonstrated weaker values when compared to the higher filled materials. Clinical significance: The advantage of initial slow polymerization (more elasticity and less tension) obtained by the so-called “soft start” method, was offset by a rise in total polymerization shrinkage, when final curing was completed at 1130 mW/cm 2. These tests demonstrated that using halogen units, exposure for 40 s with an intensity of 450 mW/cm 2 appeared to be the most promising for light-curing dental resin composites.

Finite element analysis of strength characteristics of various resin based restorative materials in Class V cavities.

This study investigated the strength characteristics of various composites (Tetric Ceram, Tetric Flow, Prisma AP.H, Synergy Duo Shade, Synergy Compact, and Z 100) and compomers (Compoglass, Compoglass F, Dyract AP, F 2000) that were applied in a Class V cavity of a maxillary central incisor. The study was conducted by using a 3-dimensional finite element approach and in the study ansys package program was used. The tooth model had 294 elements and 420 nodes. The teeth considered were assumed to be subjected to an incisal load of 200 N acting at an angle of 26 degrees with the longitudinal axis of the tooth but the effects of different loading angles and different loads were also analysed. Hence, the loads of 100 and 400 N and the loading angles of 0 degrees representing bruxism and 90 degrees representing a traumatic load were also taken into consideration. The effects of the cavity preparation size were also studied. It was determined that any increase in the loading angle and/or the amount of the load resulted in a proportional increase in the stresses developed in the tooth. Furthermore it was also verified that, as a cavity weakens the tooth structure by creating a discontinuity in an intact tooth, the larger sized cavity preparations inevitably cause larger stresses to be developed in the tooth. Strictly from the mechanical point of view, the stresses developed in the restored teeth were determined to be inversely proportional with the modulus of elasticity of the restorative materials. Therefore within the scope of the study Z 100 was found to be superior to the other materials concerned.

The interactions of tooth colored dental restorative materials with aqueous lactic acid

AbstractIn this study, the interaction of packable composite and ormocer with aqueous lactic acid solutions were determined and changes compared with those for a polyacid modified resin composite and a glass ionomer.For each material, namely Solitaire, Z‐100, Definite, Dyract AP and Vitremer, eight cylindrical specimens of 6 mm diameter and 12 mm height were prepared and weighed. They were stored individually in 20 cm3 0.02 mol−1 lactic acid solution for 1 week, then the pH was determined and the specimens reweighed. This was repeated at 1 week intervals until the specimens were 6 weeks old.The results of this study showed that; polyacid modified resin composites and resin‐modified glass‐ionomers were capable of increasing the pH of lactic acid solutions. The same groups showed an increase in mass during the first week. Composite resins and ormocer showed less increase in mass than the others. Copyright © 2003 John Wiley &amp; Sons, Ltd.

The effect of current bleaching agents on the color of light-polymerized composites in vitro

Statement of problem Bleaching agents may affect the color of existing composite restorations. Purpose The purpose of this study was to compare the effect of 10% carbamide peroxide and 10% hydrogen peroxide on the color of light-polymerized hybrid, macrofilled, and polyacid-modified composites. Material and methods Two light-polymerized hybrid composites (3M Valux and Spectrum TPH), 1 macrofilled condensable composite (Solitaire), and 2 polyacid-modified composites (Dyract AP and Compoglass) were used. The hybrid composites served as controls. The color of 8 specimens of each material was analyzed by use of a spectrophotometer before bleaching. The specimens were then divided randomly into 2 subgroups (n=4). One group was immersed in 10% carbamide peroxide solution and the other in 10% hydrogen peroxide, for 8 hours each for 14 consecutive days. After bleaching, color changes (Δ E) were determined for each material and compared by use of the Kruskal-Wallis test, followed by the Mann-Whitney U test ( P<.05). Results After bleaching with carbamide peroxide, the color changes (ΔE) for Dyract AP (2.18; SD = 1.41), Compoglass (1.14; SD = 0.26) and Solitaire (1.56; SD = 0.89) were higher than the color changes recorded for 3M Valux (0.63; SD = 3.60), and Spectrum TPH (0.66; SD = 1.24). The differences between materials bleached with carbamide peroxide were not statistically significant. After bleaching with hydrogen peroxide, the color changes for Dyract AP (9.39; SD = 0.53) and Compoglass (5.15; SD = 0.52) were higher than the changes recorded for Spectrum TPH (4.53; SD = 1.53) and 3M Valux (3.41; SD = 4.40), whereas the color change of Solitaire (3.69; SD = 0.57) was significantly higher than that of 3M Valux ( P=.01). The color changes for all restorative materials tested were clinically detectable after the application of 10% hydrogen peroxide. However, clinically noticeable discoloration was observed only for Dyract AP treated with 10% carbamide peroxide. Conclusion In comparison to 10% carbamide peroxide, 10% hydrogen peroxide caused more color changes in the composites tested.

Polymerization contraction stress in light-cured compomer restorative materials

Objective. The magnitude and kinetics of polymerization contraction stress build-up may be potential predictors of bond failure of adhesive restorations. The present study determined these properties of seven commercial compomers (Dyract, Dyract AP, F2000 Rasant, Hytac, Compoglass F, Luxat, Glasiosite). Methods. Polymerization shrinkage was generated by 40 s light curing the test materials (800 mW/cm 2). The contraction force induced was recorded for 300 s at room temperature (23–24 °C) by means of a Stress–Strain-Analyzer ( C factor=0.33). Maximum contraction stress (MPa), coefficient of near linear fit of contraction force/time (gradient) and relative force rate (%/s) of each material were compared with that of two hybrid composites (Tetric Ceram, Prodigy). The statistical analysis was conducted by ANOVA ( α=0.05) and post hoc Tukey's test. Results. No statistically significant differences in the maximum stress between Glasiosite (2.27±0.06 MPa), Hytac (2.31±0.07 MPa) and Tetric Ceram (2.21±0.11 MPa), and between Compoglass F (2.60±0.18 MPa) and Prodigy (2.70±0.06 MPa) were found. The contraction stress of F2000 Rasant (3.41±0.09 MPa) and Luxat (3.33±0.08 MPa) were significantly highest, whilst Dyract exhibited the significantly lowest shrinkage stress (1.27±0.08 MPa) among the tested materials. Significance. High contraction stress, early start of stress build-up and rapid contraction force development may lead to failure of bond to tooth structure. This study suggested that the contraction stress and kinetic behavior of compomers are generally similar to those of hybrid composites in a dry condition. Dyract might be superior in maintaining the bond with cavity walls compared to conventional hybrid composites in view of its low shrinkage stress.

A comparative study of the properties of dental resin composites polymerized with plasma and halogen light

Objectives. Newly developed curing units utilizing plasma arc methodology have been advocated for rapid curing of dental composites. This study was conducted to investigate the effect of plasma light using a 3 s and a step cure regime on the properties of four dental restorative materials and compare it with properties resulting from halogen light curing of the same materials. Methods. Composites Quadrant, Filtek and two polyacid modified composites (compomers) Dyract AP and Compoglass F were cured, using a conventional halogen light, a plasma light for 3 s (Apollo95E) and a plasma step cure (Apollo 95E) method. The parameters studied for characterization of the restorative materials were polymerization exotherm, surface hardness and their interactions with saline. Results. Irradiation with plasma light for 3 s or step cure produced an order of hardness: Filtek>Compoglass F>Dyract AP>Quadrant ( p<0.001), however, halogen cure yielded an order of hardness: Filtek>Quadrant>Dyract AP>Compoglass F. No significant differences in hardness were observed on the exposed and non-exposed surfaces of the materials cured by plasma step cure whereas a 3 s cure yielded a significant difference in the cases of Quadrant, Compoglass F and Dyract AP ( p<0.001). Mass losses were also found to be greater in the specimens cured by plasma light for 3 s in comparison with plasma step cure and halogen cure. Significance. Plasma step and halogen curing were found to yield composites with superior properties in comparison to a 3 s plasma cure, suggesting, that a step cure regime is a preferred method, when a plasma light unit is used. A 3 s curing with a plasma light may lead to less than optimum properties of the composite cements.

Compressive strength, fluoride release and recharge of fluoride-releasing materials

The compressive strength, fluoride releases and recharge profiles of 15 commercial fluoride-releasing restorative materials have been studied. The materials include glass ionomers (Fuji IX, Ketac Molar, Ketac Silver, and Miracle Mix), resin-modified glass ionomers (Fuji II LC Improved, Photac-Fil, and Vitremer), compomers (Compoglass, Dyract AP, F2000, and Hytac) and composite resins (Ariston pHc, Solitaire, Surefil and Tetric Ceram). A negative linear correlation was found between the compressive strength and fluoride release ( r 2=0.7741), i.e., restorative materials with high fluoride release have lower mechanical properties. The fluoride-releasing ability can be partially regenerated or recharged by using a topical fluoride agent. In general, materials with higher initial fluoride release have higher recharge capability ( r 2=0.7088). Five equations have been used in curve fitting to describe the cumulative fluoride release from different materials. The equation [ F] c =[ F] I (1− e −bt)+β t best describes the cumulative fluoride release for most glass ionomers, resin-modified glass ionomers, and some high fluoride-releasing compomers and composites, whereas [F] c=[F] I/( t 1/2+ t)+ αt best describes the cumulative fluoride release for most compomers and composite resins. The clinic applications of different fluoride-releasing materials have also been discussed.

Effect of storage time on microtensile strength of polyacid-modified resin composites

Objective. The purpose of this study was to determine the cohesive microtensile strength of four polyacid-modified resin composites (PAMRC: Dyract, Dyract AP, Freedom and F2000) after 24 h and 6 months of storage in water using the microtensile technique. Methods. Blocks measuring 1.5 cm×1.5 cm×1.0 cm were constructed incrementally for each material using a silicone matrix. The blocks were stored in distilled water at 37 °C for 24 h and were then serially sectioned in both x and y directions to obtain several beams measuring 1.0 cm×1.0 mm×1.0 mm. Each beam was gently trimmed from two sides with ultra-fine diamond burs to reduce the cross-sectional area to a ‘neck’ of approximately 0.4 mm 2 located in the middle of their length. The beams (18–22 per material) were randomly divided and tested in tension either after 24 h or after 6 months of storage in water at 37 °C in a Vitrodyne testing machine at 0.6 mm/min. Results. Mean microtensile strengths (MPa) at 24 h were: 48.7±13.8 for Dyract AP; 36.5±14.1 for Dyract; 38.2±14.5 for Freedom and 48.6±7.2 for F2000. There was no statistically significant difference among the materials ( p>0.05). At 6 months, only Dyract AP showed significant increase in microtensile strength ( p<0.05) while the other materials showed no differences in microtensile strength with time ( p>0.05). Significance. The results indicate that storage in water for 6 months caused no reduction of the microtensile strength of PAMRC materials.

Marginal gap formation of composites in dentine: effect of water storage.

This study investigated the effects of water storage on the marginal adaptation of two composite resins (Spectrum TPH and Ariston AT), two polyacid-modified composite resins (Dyract AP and F2000) and a new PRG composite (Reactmer) to dentine over time. Two cylindrical dentine cavities (1.5 mm diameter and 1.5 mm deep) were prepared on the horizontally sectioned surfaces of freshly extracted teeth. In each tooth, one cavity was restored using composites with their respective bonding system and the other without the bonding system. The sample size for each material with/without bonding system was 6. The composites were placed in one increment, bulk-polymerized, immediately finished/polished with the Sof-lex discs system and fine polished on 30 microm silicon carbide/9 microm aluminium oxide lapping film discs in a microgrinding system. The specimens were then stored in distilled water at 37 degrees C and the maximum marginal gap width between the material and the dentine wall was determined at 24 h, 1 week, 2 weeks, 3 weeks and 4 weeks using a measurescope at x500 magnification. Results were subjected to statistical analysis using monva, anova/Scheffe's post hoc test and independent samples of t-test at significance level 0.05. At all time intervals, no significant difference in marginal gap formation was observed between materials. Where bonding systems were not used, a decrease in gap widths over time was observed with most materials but only Dyract AP exhibited a significant decrease. The latter was observed after 2 weeks storage in water. The use of bonding systems reduced dentine marginal gaps significantly and is therefore mandatory for all composites evaluated. Marginal gaps arising from polymerization contraction of conventional, polyacid-modified and PRG composites cannot be fully compensated by hydroscopic expansion. Clinical relevance Bonding systems are mandatory for all composites when bonding to dentin. In the event of a bond failure at placement, hygroscopic expansion of composites can reduce marginal gaps but not completely.

Short-term fluoride and cations release from polyacid-modified composites in a distilled water, and an acidic lactate buffer

Fluoride and various cations release from three commercial compomers (Dyract, Dyract AP and Compoglass-F) and a resin-modified glass ionomer (Fuji-II LC) as a control were measured up to 7 days in distilled water and 0.01 m lactate buffer solution with pH 4.1. The surface morphological change before and after the release experiment was observed with a scanning electron microscopy. Fluoride, aluminum and strontium ions were released from Dyract, Dyract AP and Fuji-II LC much more in the lactate buffer than in the distilled water. With compoglass-F containing barium instead of strontium, barium was released in the same way. X-ray diffraction analysis confirmed that fluoride release from Dyract and Dyract AP was derived mainly from SrF 2 contained in Dyract and Dyract AP. However, fluoride release from Compoglass-F was derived from glassy phase though it contained much fluoride as YbF 3. Cumulative release amount of each species versus square root of time plot showed good linearity, indicating that the dissolution was controlled by the diffusion mechanism. The surface characteristics of disks for each material, which were immersed in the lactate buffer, were quite different from the surface before and after immersion in deionized water, especially with Dyract. After immersion in the lactate buffer, many voids which were left after dissolution of the filler particle, were seen obviously on the surface of Dyract.

Sorption and solubility of resin-based restorative dental materials

Objectives. To measure the water sorption and solubility of different resin-based restorative dental materials. Methods. Eight commercial restorative materials were selected: two resin composites (Z100 and Prodigy), four polyacid-modified resin composites (Compoglass, Compoglass F, Dyract and Dyract AP), and two light-cured glass ionomers (Vitremer and Fuji II LC). Five disc specimens were prepared of each material, following the manufacturer's instructions, and were grounded wet with silicon carbide paper. Water sorption and solubility of the different materials were calculated by means of weighting the samples before and after water immersion and desiccation. Data were analyzed by one-way ANOVA and Student-Newman-Keuls tests ( P<0.05). Results. Compoglass and Compoglass F showed the lowest values of water sorption and solubility, while Vitremer and Fuji II LC displayed the highest values. Solubility values of Prodigy, Z100, Dyract and Dyract AP did not show significant differences among them, while their water sorption values attained some differences and were lower for Prodigy followed by Dyract and Z100. Conclusions. The attained water sorption and solubility values are mainly influenced by the generic type of material and variations occurring between materials of the same type may result from differences in resin matrix compositions.

Amount of polymerization shrinkage and shrinkage stress in composites and compomers for posterior restoration

# The purpose of present study was to evaluate the polymerization shrinkage stress and amount of linear shrinkage of composites and compomers for posterior restoration. For this purpose, linear polymerization shrinkage and polymerization stress were measured. For linear polymerization shrinklage and polymerization stress measurement, custom made Linometer (RB Dyract AP (Dentsply Detrey, Gumbh. German) Z100 (3M Dental Products, St. Paul, USA) Surefil (Dentsply Caulk, Milford, USA) Pyramid(Bisco, Schaumburg, USA) Synergy Compact (Coltene, Altstatten, Switzerland), Heliomolar (Vivadent/Ivoclar, Liechtenstein), and Compoglass (Vivadent Ivoclar/ Liechtenstein) were used. 15 measurements were made for each material. Linear poly- merization shrinkage or polymerization stress for each material was compared with one way ANOVA with Tukey at 95% levels of confidence. For linear shrinkage; Heliomolar, Surefil<Synergy Compact, Z100<Dyract AP<Pyramid, Compoglass F (p<0.05) For Shrinkage stress; Heliomolar< Z100, Pyramid<Synergy Compact, Compoglass F<Dyract AP<Heliomolar HB, Surefil (p< 0.05) ABSTRACT

The Effect of Different Drying Methods for Single Step Adhesive Systems on Microleakage of Tooth Colored Restorations

The purpose of this in vitro study was to evaluate microleakage of tooth colored restoratives and accompanying single step adhesive systems using two drying methods (syringe air versus "sponge" applicator blotting). Eighty teeth were randomly assigned to four material groups. Class V cavity preparations, located half in enamel and half in cementum at the cementoenamel junction (CEJ), with a 1.0 mm enamel bevel were completed. The adhesive/composite groups included: (1) Single-Bond/Z-100 Composite, (2) Prime & Bond 2.1/Dyract AP Compomer, (3) OptiBond Solo Plus/Prodigy Composite, and (4) Scotchbond MultiPurpose/Z-100 Composite. Each material group (n=20), consisted of preparation Subgroups dried with syringe air (A), (n=10) and sponge applicators (B), (n=10). The preparations were conditioned, rinsed, and gently dried followed by placement of the primer/adhesive and restorative materials. All teeth were thermocycled, stained with methylene blue dye, invested in clear acrylic resin, and sectioned longitudinally through the center of the restoration. Readings were taken at the occlusal and gingival surface positions of each restoration section. A ratio (%) of wall length to amount of leakage along each wall was established. One-way Analysis of Variance (ANOVA) testing revealed: (1) no significant (p<0.05) differences existed between materials at the occlusal surface position in Subgroups A and B (syringe vs. applicator drying), (2) significantly (P<0.05) greater leakage of OptiBond Solo Plus compared to Single-Bond, Prime & Bond 2.1, and Scotchbond MultiPurpose at the gingival surface position in Subgroups A and B, (3) significantly (p<0.05) greater leakage of OptiBond Solo Plus compared to Single-Bond and Scotchbond MultiPurpose, combining the occlusal/gingival surface position scores, (4) no significant difference existed between Single-Bond Subgroups A/B, OptiBond Solo Plus Subgroups A/B, Scotchbond MultiPurpose Subgroups A/B, (5) significantly (p<0.05) greater leakage of Prime & Bond 2.1 Subgroup B compared to Subgroup A, (6) no significant (p<0.05) difference existed between material groups, except OptiBond Solo Plus (occlusal vs. gingival surface position), (7) no significant (p<0.05) difference between Single-Bond, OptiBond Solo Plus, and Scotchbond MultiPurpose comparing both Subgroups, same materials, and surface positions, and (8) no significant (p<0.05) difference existed between Prime & Bond 2.1, comparing both Subgroups, occlusal surface position. In the present study, significantly greater leakage was revealed with OptiBond Solo Plus compared to the other material groups, especially at the gingival surface positions. Significantly greater leakage was also recorded with OptiBond Solo Plus and Prime & Bond 2.1 sponge applicator drying as compared to the same materials, syringe air drying.