Influence of Curing Mode on the Surface Energy and Sorption/Solubility of Dental Self-Adhesive Resin Cements

Evaluation of a biobased polycarbonate interpenetrated network in a dental resin composite

Silanization of filler particles in a dental resin composite is achieved by the formation of Si-O-Si bonds, however, these bonds are especially vulnerable to hydrolysis because this covalent bond has a significant ionic character due to the electronegativity differences between the atoms. The objective of this study was to evaluate the use of an interpenetrated network (IPN) as alternative of silanization reaction and to assess its effect in selected properties of experimental photopolymerizable resin composites. The interpenetrate network was obtained during the photopolymerization reaction of organic matrix (BisGMA/TEGDMA) with a biobased polycarbonate. Its characterization was performed via FTIR, flexural strength, flexural modulus, depth of cure, sorption water and solubility. A resin composite formulated with non-silanized filler particles was used as control. The IPN with a biobased polycarbonate was successfully synthesized. The results showed that the IPN based resin composite had higher values of flexural strength, flexural modulus, and degree of double bond conversion than the control (p < 0.05). Polymerization shrinkage, water sorption and solubility were statistically significantly lower than the control resin (p < 0.05). Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p > 0.05). The biobased IPN replaces the silanization reaction in resin composites, improving physical and chemical properties. Therefore, IPN with a biobased polycarbonate could be potentially useful in the formulation of dental resin composites.

Longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores with self-adhesive resin cement: an update of a prospective analysis with up to 106 months of follow-up

OBJECTIVES

To evaluate the longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores using a self-adhesive resin cement in a prospective clinical descriptive study.

METHODS

A total of 152 teeth were endodontically treated and received resin composite prosthetic cores and metal-ceramic crowns cemented with a self-adhesive resin cement. The patients included in the sample were recalled for clinical and radiography evaluation in an up-to-106-month period after the final cementation procedures, with an average of 62 months of follow-up. 91.5% of the sample (142 teeth) were evaluated regarding the treatment survival rate, analyzed considering the loss of crown retention (crown debonding) and tooth loss as the primary outcome. In addition, post debonding, and root fracture occurrences were also recorded as secondary outcomes to evaluate the success rate of the prosthetic treatment. The aesthetic parameters were also evaluated according to the FDI criteria. The Kaplan-Meier method and Cox regression with 95% confidence interval were applied for the statistical analysis.

RESULTS

Regarding the primary outcome, the metal-ceramic crowns cemented with self-adhesive resin cement presented a high survival rate (91.5%), with 8 crown debondings and 3 tooth losses (1 due to caries and 2 due to periodontal disease) occurring after the evaluation period. For secondary outcomes, 9 root fractures and 4 post debondings occurred, generating a success rate of 72%. All crowns had a score 1 on the FDI criteria, indicating that they were clinically excellent or very good regarding the aesthetic parameters.

CONCLUSION

The metal-ceramic crowns luted with a self-adhesive resin cement presented a survival rate of 91.5% after an average of 62 months of follow-up. Furthermore, the restorations remained aesthetically satisfactory over time, without changes that would indicate prosthetic retreatment. A success rate of 72% was obtained considering the secondary outcome, mainly related to intraradicular retainer failures (root fractures or post debonding).

CLINICAL SIGNIFICANCE

The self-adhesive resin cement is clinically indicated for cementation of metal-ceramic crowns onto resin composite prosthetic cores.

Protective effect of a nanofilled resin-based coating on wear resistance of glass ionomer cement restorative materials

BACKGROUND

The effect of nanofilled resin-based coating on the wear resistance of glass ionomer cements (GICs) is still controversial. This study aims to compare the wear resistance of four encapsulated GICs including two conventional and two resin-modified, and to evaluate the effect of G-Coat Plus on the wear resistance of GICs.

METHODS

A total of 80 disk-shaped specimens were prepared from two CGICs (riva self cure (SDI) and Equia Forte Fil (GC) and two RM- GICs (Ketac Nano (3 M/ESPE) and Fuji II LC (GC). The specimens of each material were divided into two groups (n = 10) based on the surface protection: no coating (NC), and coating with G-Coat Plus (GCP). All specimens were then placed in distilled water for 24 h at 37 °C. The specimens were subjected to thermocycling for 120,000 cycles using a chewing simulator. Wear resistance was measured using a specific formula. Data was analyzed using Kruskal-Wallis test.

RESULTS

There was no significant difference in volume loss (mm³) between coated and uncoated groups for all materials (P > 0.05). Ketac Nano showed significantly lower volume loss (0.65 ± 0.12) compared to all other groups (P < 0.05) among uncoated specimen, and significantly lower than Fuji II LC (P = 0.035) and Equia Forte Fil (P = 0.040) among coated groups. However, no statically significant difference was observed between volume loss of coated Ketac Nano with that of riva self cure (P = 0.087).

CONCLUSIONS

Coating with GCP did not affect the wear depth of GICs, and Ketac Nano showed significantly lower volume loss regardless of coating.

Physical and Mechanical Properties of Bulk-Fill, Conventional, and Flowable Resin Composites Stored Dry and Wet

Surface degradation, margin, and bulk fracture are common reasons that necessitate replacement of resin composite restorations. The purpose of this study was to determine filler weight (FW), fracture toughness (FT), Vickers hardness (VHN), sorption/solubility (S/S), and colour change (ΔE) of four resin composites in dry and wet conditions. Four resin composites of shade A2 were investigated: Aura bulk-fill (AB) (SDI), Tetric Evoceram (TE) (Ivoclar), G-ænial Universal Flo (GUF) (GC), and GC Kalore (GCK) (GC). For FT, VHN, and ΔE, the specimens were prepared, divided into 2 groups, and stored dry or immersed in distilled water. The specimens were subdivided into three subgroups and stored for 1, 7, and 60 days and then subjected to the relevant tests. Six fractured remnants were weighed for each material to measure FW%. To test S/S, ISO 4049 was used. The data were analysed using ANOVA and Tukey's test. There was an inverse correlation between FW and FT. A significantly higher FT was found for GUF. There were no significant differences between conditions in materials except for AB. The highest VHN was found for GCK and AB. After 1 and 7 days, a significant difference was observed in S/S between all materials with the highest values for GUF. There was a correlation between sorption and solubility. The material, the media, and aging have an influence on the properties of resin composites. It is important to emphasise that each material should be used for a specific clinical need based on their properties.

Effects of Color Modifier on Degree of Monomer Conversion, Biaxial Flexural Strength, Surface Microhardness, and Water Sorption/Solubility of Resin Composites

Color modifiers can be mixed with resin composites to mimic the shade of severely discolored tooth. The aim of this study was to assess the effects of a color modifier on the physical and mechanical properties of a resin composite. The composite was mixed with a color modifier at 0 wt% (group 1), 1 wt% (group 2), 2.5 wt% (group 3), or 5 wt% (group 4). The degree of monomer conversion (DC) was examined after light curing for 20 or 40 s. Biaxial flexural strength (BFS)/modulus (BFM), surface microhardness (SH), and water sorption (W_sp)/solubility (W_sl) were also tested. The DC of group 1 was significantly higher than that of groups 3 and 4. The increase in curing time from 20 to 40 s increased the DC by ~10%. The BFS, BFM, W_sp, and W_sl of all the groups were comparable. A negative correlation was detected between the concentration of color modifier and the BFS and DC, while a positive correlation was observed with W_sp. In conclusion, the color modifier reduced the DC of composites, but the conversion was improved by extending the curing time. The increase in color modifier concentration also correlated with a reduction in strength and the increase in the water sorption of the composites.

Evaluation of microhardness and water sorption/solubility of dual-cure resin cement through monolithic zirconia in different shades

Aim:

The objective is to evaluate the effect of shades of monolithic zirconia on the microhardness and sorption/solubility of the underlying two dual-cured resin types of cement.

Materials and Methods:

Eighty samples of two dual-cured resin cement discs were polymerized under 60 monolithic zirconia discs in three shades and directly activated resin discs of cement were used as the control group (n = 10). After 24 h storage at 37°C in an incubator, Vickers microhardness and the sorption and solubility were measured.

Statistical Analysis Used:

Two-way ANOVA , one-way ANOVA, Independent t-test, Tukey's honestly significant difference, and Tamhane's T2 tests.

Results:

The mean microhardness of the Variolink N resin cements were significantly higher than Panavia SA ones (P < 0.001). Furthermore, Variolink N cements exhibited lower sorption/solubility than Panavia SA resin cements (both P < 0.05). The ceramic shade had a significant influence on the microhardness of both cements (P < 0.001) but had no significant effect on the sorption/solubility of resin cements (P > 0.05).

Conclusion:

Interposition of monolithic zirconia decreases the microhardness of resin cement especially Panavia SA. In Variolink N, by increasing the chroma saturation of ceramics, the microhardness decreased, however in Panavia SA, it was altered by the shades, but not in a specific pattern. For both cements, there were no statistical differences between the sorption/solubility of samples photo-cured under different shades. There was a reverse correlation between microhardness and water sorption/solubility of both cements.

Evaluation and comparison on the wettability of three root canal sealers after three different irrigant activation techniques: An in vitro study

Background

Wettability of root canal sealers to the root canal wall plays a significant role in the attainment of a fluid-tight seal.

Aims

This study aimed to evaluate and compare the wettability of three different root canal sealers on the root canal walls after three different irrigant activation techniques using the contact angle meter.

Subjects and Methods

Thirty-six single-rooted mandibular premolars after decoronation and cleaning and shaping up to size #35 were randomly divided into three groups with 12 samples in each group (n = 12) based on the different activation techniques: Group I (passive irrigation with side-vented needle), Group II (manual dynamic agitation), and Group III (passive ultrasonic irrigation). Root segments were split longitudinally and were subdivided into three subgroups based on the root canal sealers tested with four samples in each subgroup (n = 4): Subgroup A (Tubliseal EWT), Subgroup B (AH Plus), and Subgroup C (Endosequence BC sealer). A controlled volume droplet of sealer was placed on each specimen and was subjected to the contact angle meter.

Statistical Analysis

Data were statistically analyzed using the one-way ANOVA and Tukey's post hoc test at a significance level of 0.05 (P < 0.05).

Results

A statistically significant difference was seen among all the groups and subgroups with the highest contact angle value for Group III and Subgroup C and the least value for Group I and Subgroup A.

Conclusions

Passive irrigation with side-vented needle and Tubli-Seal EWT showed better wettability on dentin.

Root dentin surface activation to improve bioceramic bonding: A scanning electron microscopic study

Background. Bioceramics need to interact chemically with dentin to exhibit adequate bioactivity. Proper bonding of bioceramics with dentin is of considerable importance. This study aimed to evaluate the wettability and marginal adaptation of bioceramics after the use of surface-active agents on dentin: %0.5 cetrimide and %1 alkylbenzene sulfonate.

Methods. Of ninety maxillary central incisors, 45 teeth were sectioned longitudinally with 45 root halves randomly assigned to three groups (n=15): group I: no pre-treatment; group II: %0.5 cetrimide; group III: %1 alkylbenzene sulfonate. Then, the samples were subdivided into three subgroups (n=5): subgroup I: MTA; subgroup II: Biodentine, and subgroup III: BioRoot. A controlled-volume droplet of bioceramic material was placed on each root half, which was positioned in a dynamic contact angle analyzer to record the static contact angle for wettability. The remaining 45 samples were decoronated; the root canals were prepared and randomly categorized, as mentioned above. The root canal surfaces were treated, filled with the bioceramic material, transversely sectioned, and then each middle section was analyzed microscopically for marginal adaptation. Statistical tests used included post hoc Tukey tests and one-way ANOVA. The level of statistical significance set at %95 (P<0.05).

Results. The contact angle values and interfacial gap width values after surface pre-treatment were significantly lower when compared to no pre-treatment group (P<0.05). The values were significant for %0.5 cetrimide in the case of Biodentine and %1 alkylbenzene sulfonate in the case of BioRoot (P<0.05).

Conclusion. The two surfactants yielded promising results for enhancing the wettability and marginal adaptation of materials to the root dentin, which is required for obtaining an adequate seal, penetration, and bond strength of bioceramics.

Physical Properties of Nanohybrid and Microhybrid Resin Composites Subjected to an Acidic Environment: A Laboratory Study

BACKGROUND

This study investigated the hardness and color stability of five resin composites subjected to different polishing methods following immersion in distilled water or lactic acid for up to three months.

METHODS AND MATERIALS

Three nanohybrid, Paradigm (3M ESPE), Estelite Sigma Quick (Tokuyama), Ice (SDI), and two microhybrid, Filtek P60 and Filtek Z250, composites were examined. Disc-shaped specimens (10×1.5 mm) were prepared and immersed in distilled water for 24 hours then polished using either silicon carbide paper, the Shofu polishing system or were left unpolished (control). The CIE values and microhardness were determined using a spectrophotometer and digital Vickers hardness tester, respectively (n=10) after one, 45, and 90 days of storage in distilled water or lactic acid. Data were analyzed using analysis of variance, Tukey test, and Pearson correlation coefficient.

RESULTS

Ice exhibited the greatest color change, yet Paradigm and Filtek P60 demonstrated the least. Overall, discoloration of tested materials was multifactorial and the effect of storage media depended on the material, polishing method and time interval. The greatest hardness was obtained for Paradigm and the lowest for Estelite. Hardness was found to be significantly higher in lactic acid after 45 days (p=0.014) and even higher after 90 days (p<0.001) compared with distilled water.

CONCLUSIONS

An acidic environment did not adversely affect color stability or microhardness of the resin composites. There was a significantly mild reverse correlation between hardness and color change in both storage media.

[Effect of intrapulpal pressure on the bonding strength of resin cement to dentin]

OBJECTIVE

To evaluate the effect of intrapulpal pressure simulation on the micro-tensile bond strength (μTBS) of resin cement to dentin.

METHODS

Thirty extracted human third molars were selected. Occlusal enamel was removed to expose dentine surface and teeth with residual dentin thickness of 0.5-2.5 mm were selected. Dye permeation through dentin tubules with or without intrapulpal pressure (IPP) simulation, or after Single Bond Universal (SBU) application on dentin surface with IPP simulation were observed at the end of 0 min, 5 min, 30 min and 2 h. The teeth with residual dentin thickness of (1.0±0.1) mm were divided into 2 groups with IPP simulation of 15 or 0 cmH₂O (1 cmH₂O=0.098 kPa), which was maintained for 30 min before bonding procedure. SBU was applied on the dentin surface and light cured, then RelyX Ultimate (RLX) cement was heaped on the dentin surface (diameter=10 mm, height=4 mm) and light-cured. After the dentin-resin cement samples were stored in distilled water for 24 h at 37 °C, the samples were cut into beams with cross sectional area of 0.9 mm×0.9 mm for μTSB testing (n=100). The data were analyzed with two independent samples t-test (α=0.05). The fracture mode was observed using scanning electron microscopy (SEM). The results were analyzed with Fisher exact test (α=0.05). The rest of dentin-resin cement samples (five samples for each group) were cut perpendicular to the bonding interface and the morphology of the bonding interface was observed using SEM.

RESULTS

The dye permeation through dentin tubules with IPP simulation was faster than those without IPP simulation. The μTSB of RLX to dentin with and without IPP simulation were (26.26±9.78) MPa and (28.70±9.0) MPa, respectively. The most frequent fracture mode was mixed-fracture mode. There was no significant difference between the two groups for neither bond strength nor fracture types distribution (P>0.05). Regarding the morphology of dentin-resin cement bonding interface, both groups showed 4-8 μm finger-like resin tags.

CONCLUSION

With SBU pretreatment, the IPP simulation had no influence on the immediate bond strength of RLX to dentin.

Comparison to Color Stability Between Amine with Benzoyl Peroxide Includes Resin Cement and Amine-reduced, Amine-free, Lacking of Benzoyl Peroxide Resin Cements After Thermocycle

Objective:

This study aims to compare the color change (Δ E) of 5 resin cements (Panavia SA, Panavia V5, RelyX U200, Variolink NLC clear and +1) after thermocycling. Changes in color of specimens were determined after 10,000 cycles of thermocycling by spectrophotometer in the CIELAB.

Materials and Methods:

Ceramic disks, simulating laminate veneers, with thicknesses of 0.5, 0.7, and 1.0 mm (A1, IPS e.max) were fabricated. Color differences (Δ E) between the control and test groups were calculated. Data were statistically analyzed by 2-way analysis of variance (ANOVA). Also, Tukey’s multiple comparison tests were applied to know the difference between the groups (α = 0.05).

Results:

The factors of cement type and thickness of ceramic showed significant influence on Δ E values ( P < .05). After thermocycling, all resin cements, except benzoyl peroxide including resin cement (Pan SA), were showed clinically acceptable to color change limits (Δ E < 3.3). On evaluating the effects of ceramic thickness on color change after thermocyle aging, control group (no ceramic thickness) showed color change ( P < .05) visually.

Conclusion:

Amine-reduced, amine-free and lacking benzoyl peroxide resin cement showed minimal color change and better color stability.

An Evaluation of Wetting and Adhesion of Three Bioceramic Root Canal Sealers to Intraradicular Human Dentin

Root canal sealers should have good wetting and adhesion with intraradicular dentin. This study evaluated the wetting and adhesion properties of three bioceramic root canal sealers on dentin using contact angle (CA) measurements and calculations based on the Owens–Wendt–Rabel–Kälble (OWRK) model and compared the properties with those of a resin sealer. Three bioceramic sealers (EndoSequence BC Sealer (BC); Endoseal MTA (EM); and MTA Fillapex (MF)) were tested, together with one epoxy resin-based sealer (AH Plus (AP)). Disc-shaped sealer specimens and human premolar teeth with flat and polished intraradicular dentin surfaces were prepared (n = 12). The CAs of two liquids (water and methylene iodide) were measured on the surfaces using the sessile drop method. The wetting and adhesion properties of the four sealers were calculated using the wetting envelope and isogram diagram, respectively. Group BC showed the best wettability among the four sealer groups. The best adhesion was achieved for group EM, followed by group BC, with a significant difference being present between the two groups (p < 0.05). The OWRK-based calculation indicated that the bioceramic BC and EM sealers showed superior wetting and adhesion properties to the AP sealers.

Evaluation of Compressive Strength and Sorption/Solubility of Four Luting Cements

STATEMENT OF PROBLEM

Compressive strength (CS) and sorption/solubility of the luting cements are two associated factors. Searching a correlation between sorption/solubility and compressive strength of various luting cements is required.

OBJECTIVES

To measure the water sorption/solubility, and compressive strength of three resin-based and one conventional glass ionomer (CGI) luting cement after 1 and 24 h of immersion in distilled water and to determine if there is any correlation between those properties found.

MATERIALS AND METHODS

Four luting cements were investigated. For each material, 10 disc shaped specimens were prepared for measuring the sorption/solubility. The specimens were cured according to the manufacturer's instructions, and the sorption/solubility were measured in accordance with the ISO 4049's. For testing the compression strength, for each material 16 cylindrical specimens were prepared by insertion of cements into a stainless steel split mould. The specimens were cured, divided into groups of 8, and then stored in distilled water at (37 ± 1)°C for 1 and 24 h. The test was performed using the universal testing machine, the maximum load was recorded and CS was calculated. The data were analysed using SPSS software version 18. One-way ANOVA, post-hoc Tukey's test and Pearson's correlation coefficient were performed.

RESULTS

G-CEM had the highest mean CS (153.60± 25.15) and CGI luting had the lowest CS (21.36±5.37) (p <0.001). After 24 h, mean CS values showed an increase for almost all materials except for RelyXTM U200 which showed a slight reduction. However, no statistically significant difference was founded (all p > 0.05). The lowest mean sorption/solubility value was for RelyX^TM U200 and Panavia F, and the highest for CGI luting (all p < 0.001).

CONCLUSIONS

The compressive strength of all cements did not necessarily increase after 24 h and varied depending on the materials. There was a strong reverse correlation between sorption and CS values after both 1 and 24 h immersion. It may be practical for clinician to use those cements with the less sorption / solubility and more stable compression strength over time.