Light-cured Resin Cement Research Articles

Bacterial Adhesion and In Situ Biodegradation of Preheated Resin Composite Used as a Luting Agent for Indirect Restorations.

To evaluate surface roughness and bacterial adhesion after in situ biodegradation of the cementation interface of indirect restorations cemented with preheated resin composite. Resin composite blocks (Z250XT/3M ESPE) were cemented to bovine enamel (7 × 2.5 × 2 mm) using preheated microhybrid resin composites: (1) Filtek Z100 (3M ESPE) (Z100); (2) Gradia Direct X (GC America) (GDX); and (3) Light-cured resin cement RelyX Veneer (3M ESPE) (RXV) (n = 21). The resin composites were preheated on a heating device (HotSet, Technolife) at 69°C for 30 minutes. Disk-shaped specimens (7 x 1.5 mm) were made for biodegradation analysis with the luting agents (n = 25). The in situ phase consisted of 20 volunteers' using an intraoral palatal device for 7 days. Each device had six cylindrical wells for the blocks and the disk-shaped specimens. Biodegradation was evaluated through surface roughness (Ra), scanning electron microscopy (SEM) micromorphological analysis, and colony-forming unit (CFU) count. The film thickness of the luting agents was also measured under stereomicroscopy. Increased surface roughness was observed after the cariogenic challenge without differences between the luting agents. Higher variation and surface flaws suggestive of particulate detachment were observed for Z100. No differences were observed in CFU counts. All materials underwent surface biodegradation, and the surface roughness of the resin cements was similar to or lower than that of the preheated resin composites. The resin composites' film thickness was thicker than that of the resin cement. Clinicians should be aware of these factors when choosing the use of preheated resin composite since it can lead to reduced longevity of the cementation interface and, therefore, restorations.

Effect of preparation design on fracture resistance of molars restored with occlusal veneers of different CAD-CAM materials: an in vitro study

BackgroundOcclusal veneer had been evaluated for mechanical properties using lithium disillicate. However, studies evaluating the mechanical properties of occlusal veneer with different preparation designs and ceramic materials are lacking. So, this in vitro study aimed to evaluate the fracture resistance of occlusal veneers with two designs fabricated from two different ceramic materials.Material and methodsFourty mandibular third molars were distributed to 2 groups (n = 20) according to preparation design: group (O) anatomical occlusal reduction and group (OA) anatomical occlusal and 1 mm axial reduction. Each group was additionally subdivided into two subgroups (n = 10) according to ceramic materials; in subgroup X, lithium disilicate (e.max CAD, Ivoclar AG, Schaan, Liechtenstein) was used, and in subgroup S, zirconia-reinforced lithium silicate (ZLS) (Vita Suprinity, VitaZahnfabrik, Bad Säckingen, Germany) was used. All specimens were cemented with a light-cure resin cement (Choice 2, Bisco, Schaumburg, USA). 5000 thermocycles were applied to all specimens with both temperatures of 5 °C and 55 °C in two water baths; the dwell time was 30s at each bath, and the transfer time was 10s. Then all specimens were subjected to a fatigue simulation under dynamic loading of 200 N for 250,000 cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to evaluate the fracture strength with a crosshead speed of 1 mm/min. All data were analyzed statistically by using a two-way ANOVA, and for some violations of assumptions, these results were compared with those obtained by the nonparametric test (Scheirer Ray Hare) (α = 0.05).ResultsA statistically significantly higher fracture resistance in the ‘OA’ (3389 N) compared to the ‘O’ (2787 N) group regardless of the ceramic material (P < .001) and a statistically significantly higher fracture resistance in the ‘X’ (3295 N) compared to the ‘S’ (2881 N) regardless of the preparation design (P = .015).ConclusionsFor occlusal veneers, all preparation designs and materials (such as Vita Suprinity and e.max CAD) had clinically acceptable fracture resistance values that were greater than the maximal biting forces. On the other hand, the e.max CAD with occlusal veneer, including axial reduction design, demonstrated the maximum fracture resistance value. Finally, no relationship between fracture strength and mode of failure was found.

An Advanced Surface Treatment Technique for Coating Three-Dimensional-Printed Polyamide 12 by Hydroxyapatite

Polymer 3D printing has is used in a wide range of applications in the medical field. Polyamide 12 (PA12) is a versatile synthetic polymer that has been used to reconstruct bony defects. Coating its surface with calcium phosphate compounds, such as hydroxyapatite (HA), could enhance its bonding with bone. The aim of this study was to coat 3D-printed polyamide 12 specimens with hydroxyapatite by a simple innovative surface treatment using light-cured resin cement. Polyamide 12 powder was printed by selective laser sintering to produce 80 disc-shaped specimens (15 mm diameter × 1.5 mm thickness). The specimens were divided randomly into two main groups: (1) control group (untreated), where the surface of the specimens was left without any modifications; (2) treated group, where the surface of the specimens was coated with hydroxyapatite by a new method using a light-cured dental cement. The coated specimens were characterised by both Fourier transform infrared spectroscopy (FTIR) and Transmission Electron Microscopy (TEM), (n = 10/test). The control and treated groups were further randomly subdivided into two subgroups according to the immersion in phosphate-buffered saline (PBS). The first subgroup was not immersed in PBS and was left as 3D-printed, while the second subgroup was immersed in PBS for 15 days (n = 10/subgroup). The surfaces of the control and treated specimens were examined using an environmental scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDXA) before and after immersion in PBS. Following the standard American Society for Testing and Materials (ASTM D3359), a cross-cut adhesion test was performed. The results of the FTIR spectroscopy of the coated specimens were confirmed the HA bands. The TEM micrograph revealed agglomerated particles in the coat. The SEM micrographs of the control 3D-printed polyamide 12 specimens illustrated the sintered 3D-printed particles with minimal porosity. Their EDXA revealed the presence of carbon, nitrogen, and oxygen as atomic%: 52.1, 23.8, 24.1 respectively. After immersion in PBS, there were no major changes in the control specimens as detected by SEM and EDXA. The microstructure of the coated specimens showed deposited clusters of calcium and phosphorus on the surface, in addition to carbon, nitrogen, and oxygen, with atomic%: 9.5, 5.9, 7.2, 30.9, and 46.5, respectively. This coat was stable after immersion, as observed by SEM and EDXA. The coat adhesion test demonstrated a stable coat with just a few loose coating flakes (area removed &lt;5%) on the surface of the HA-coated specimens. It could be concluded that the 3D-printed polyamide 12 could be coated with hydroxyapatite using light-cured resin cement.

Flowable composite as an alternative to adhesive resin cement in bonding hybrid CAD/CAM materials: in-vitro study of micro-shear bond strength

ObjectiveTo assess the micro-shear bond strength of light-cured adhesive resin cement compared to flowable composite to hybrid CAD/CAM ceramics.Materials and methodsRectangular discs were obtained from polymer-infiltrated (Vita Enamic; VE) and nano-hybrid resin-matrix (Voco Grandio; GR) ceramic blocks and randomly divided according to the luting agent; light-cured resin cement (Calibra Veneer; C) and flowable composite (Neo Spectra ST flow; F), resulting in four subgroups; VE-C, VE-F, GR-C and GR-F. Substrates received micro-cylinders of the tested luting agents (n = 16). After water storage, specimens were tested for micro-shear bond strength (µSBS) using a universal testing machine at 0.5 mm/min cross-head speed until failure and failure modes were determined. After testing for normality, quantitative data were expressed as mean and standard deviation, whereas, qualitative data were expressed as percentages. Quantitative data were statistically analysed using Student t test at a level of significance (P ≤ 0.05).ResultsGroup GR-F showed the highest µSBS, followed by VE-C, VE-F and GR-C respectively, although statistically insignificant. All groups showed mixed and adhesive failure modes, where VE-F and GR-C showed the highest mixed failures followed by GR-C and VE-C respectively.ConclusionsAfter short-term aging, flowable composite and light-cured resin cement showed high comparable bond strength when cementing VE and GR.

Full Digital Workflow for Aesthetic Rehabilitation of the Upper Teeth: A Case Report

The present case report presents a digital workflow for designing an aesthetic rehabilitation of the upper anterior teeth in an adult male. The patient suffered from a gummy smile resulting from an unfavorable ratio between upper lip length and gingiva/tooth display. In addition, the tooth shapes, color, and position were not accepted by the patient. The treatment planning included gingivectomy based on a digitally designed PMMA guide performed using a soft tissue SOGA laser (Shenzhen Soga Technology Co., Ltd., Shenzhen, China). The preparation was guided by the plastic guides for preparation control created digitally in Exocad software (Rijeka 3.1. Darmstadt, Germany) and printed in three-dimensional plastic. Next, both arches and maximum intercuspation were scanned. The milled lithium disilicate veneers were manufactured using CAD-computer-aided manufacturing (CAM) equipment. The restorations were cemented using a translucent light-cure resin cement (RelyX Universal, 3M ESPE, St. Paul, MN, USA). Next, occlusion adjustment and polishing were executed. Based on the present case report, it can be assumed that the application of digital techniques allows us to achieve an aesthetic and functional result with reduced work time and errors. Emphasizing the clinical impact, these methods enhance patient satisfaction and treatment accuracy in intricate aesthetic rehabilitations.

Effect of computer-aided design/computer-aided manufacturing bleach shade ceramic thickness on its light transmittance and microhardness of light-cured resin cement

Effect of computer-aided design/computer-aided manufacturing bleach shade ceramic thickness on its light transmittance and microhardness of light-cured resin cement

Color Matching between Resin Cements and Try-in Pastes in Glass Ceramics at Different Thicknesses

Aim: This study aims to assess how well light-cured resin cements and the corresponding try-in pastes match in terms of color. Materials and Methods: A1 color blocks containing three different types of ceramic materials were used to generate 120 specimens (5 × 5 mm2). These specimens were split into two thickness-based groups, and the groups were then randomly allocated to receive various kinds of resin cement. Composite substrate blocks with A3 color and dimensions of 4 mm thickness were used to simulate dentin substrates. Color measurements were taken before and after the application of try-in pastes and resin cements using a spectrophotometer. The obtained results were analyzed using the CIELab and CIEDE2000 frameworks, and statistical analysis was performed using a three-way ANOVA test and paired sample t-test with a significance level of α = 0.05. Results: There were no significant interactions between material, thickness, and cement in relation to color in both evaluation systems ( p &gt; .05). However, there were significant differences in the a* values (green-red axis) between the try-in pastes and resin cements ( p &lt; .05), while no significant differences were observed in the L* (lightness) and b* (blue-yellow axis) values ( p &gt; .05). Conclusion: The try-in pastes utilized for pre-cementation evaluation exhibited favorable color compatibility with the corresponding resin cements.

Comparative Evaluation of Luting Efficacy Between a Dual-Cure and Light-Cure Resin Cement on Its Application on Root Surface Indirect Restorations: An In Vitro Study.

Aim The aim is to evaluate the degree of dye penetration between a dual-cure and conventional resin cement on its application on the root surface indirect restorations to provide a reference for clinical choice. Materials and methods Ten freshly extracted human maxillary central anteriors were selected and randomly divided into twogroups of five each. Teeth were prepared for veneer restoration, andveneers were luted using two groups of cementsCalibra veneer cement and Fusion Ultra D/C cement. Afterthey were immersed in methylene blue dye solution for 24 h, the specimens were then sectioned buccolingual into three halves in a parallel vertical planeand measured dye penetration using a stereomicroscope (Zeiss). The data collected was recorded by the dye penetration index (0-4) and statistically analyzed using the IBM SPSS Statistics for Windows, Version 24(Released 2016; IBM Corp., Armonk, New York, United States). Results It is evident that group 1 (Calibra veneer cement) showed the lowest mean score of 0.43 mmand group 2 (Fusion Ultra D/C) showed a highest mean score of 0.72 mm. Overall, when the two groups were compared for microleakage using SPSS, there was a significant difference among the groups. Conclusion It was determined that both the resin cements evaluated in this study showed microleakage to some level given the limits of the investigation and the findings. To evaluate the dye penetration of microleakage, the Calibra veneer resin cement showed a better marginal adaptability for veneer restoration.Further investigations withbroader methodology and more clinical simulation are needed to evaluate other resin cements available for root surface indirect restorations to be analyzed for prospective clinical outcomes.

Physicochemical and mechanical properties of preheated composite resins for luting ceramic laminates.

This study analyzed and compared the physicochemical and mechanical properties of preheated resin composite with light-cured resin cement for luting indirect restorations. 210 specimens of resin cement/resin composite were prepared according to preheating treatment heated (Htd) or not (NHtd). Light-cured resin cement (Variolink Veneer, Ivoclar), and resin composite (Microhybrid-Z100, 3M; Nanohybrid-Empress direct, Ivoclar; and Bulk fill-Filtek One, 3M) were used (n = 10). Resin cement specimens were not preheated. The response variables were (n = 10): film thickness, microhardness, liquid sorption and solubility. Data were analyzed by 2-way ANOVA and Tukey HSD post-test (α = 0.05). Bulk fill NHtd resin had the highest film thickness values (p < 0.001). Microhybrid and nanohybrid Htd resins had the smallest thicknesses and did not differ from the cement (p > 0.05). The highest microhardness values were found for Bulk fill NHtd and Bulk fill Htd resins. The nanohybrid and microhybrid Htd resins showed the lowest microhardness values, with no difference in cement (p > 0.05). For liquid sorption, there was no significant difference between the groups (p = 0.1941). The microhybrid Htd resin showed higher solubility values than the other materials (p = 0.0023), but it did not differ statistically from resin cement (p > 0.05). Preheating composite resins reduced the film thickness. After heating, nanohybrid and Bulk fill resins retained stable microhardness, sorption, and solubility values.

Comparative Evaluation of Bond Strengths Between Dual Cure Resin Cement and Light Cure Resin Cement in Root Surface Indirect Restorations: An In Vitro Analysis Study.

Aim The aim of this study was to evaluate the shear bond strength betweendual cure and light cure resin cements in root surface indirect restorations. Materials and methods Ten recently extracted human teeth were selected. Cylindrical blocks of resin were prepared and bonded nearthe Cemento-Enamel Junction (CEJ) of the prepared teeth to mimic the restoration at the root surface.The samples were randomly luted to the root surface using the light cure (Calibra Veneer, Dentsply Sirona, India) and dual cure (Fusion Ultra D/C, DenPro, USA) formingtwo groups. The bond strength was checked using the INSTRON 3000 device (INSTRON, MA, USA). The point of fracture of the prepared sample from the tooth surface was noted. All readings were tabulated and further statistically analyzed. Results On comparing the two groups, it was found that the light cured resin had a greater mean shear bond strength (57 N) than the dual cure resin cement (41 N).The difference in the mean value of the shear bond strength between two resin cements was found to be statistically not significant according to independent T-test analysis using Levene's Test (P>0.05). Conclusion From the results obtained and within the limits of the study conducted, we can infer that Calibra Veneer is a more viable option for luting to the root surface area. On the other hand, Fusion Ultra Dual cure resin cement seems to have similar results but has a lower bond strength than the other.

Effect of 4-META on microtensile bond strength of cements to ceramics

Background: This study assessed the effect of different concentrations of 4-methacryloyloxyethy trimellitate anhydride (4-META) added to silane on microtensile bond strength (µTBS) of light-cure and dual-cure resin cement to hybrid and zirconia-reinforced lithium silicate ceramics. Materials and Methods: This in vitro, experimental study was conducted on 32 Celtra Duo and 32 VITA Enamic ceramics bonded to Allcem Veneer light-cure and Allcem dual-cure resin cements using silane impregnated with 4-META in 0%, 2.5%, 5%, and 10 wt% concentrations in 16 groups (n = 4). The µTBS of specimens was measured by a universal testing machine and analyzed by the Kruskal–Wallis and Mann–Whitney tests, and the mode of failure was determined under a stereomicroscope and analyzed by the Chi-square test (alpha = 0.05). Results: The lowest mean µTBS was recorded in the Enamic ceramic group with 4-META (0%) bonded to dual-cure cement (14.26 MPa), and the highest mean µTBS was recorded in Enamic ceramic with 4-META (10%) bonded to light-cure cement (18.59 MPa) (P &lt; 0.001). The µTBS of Celtra Duo was significantly higher than that of Enamic in bonding to light-cure cement using 4-META (2.5%) (P = 0.003). All failures (100%) were adhesive in most groups. The frequency of adhesive failure was the lowest (90%) in Celtra Duo bonded to dual-cure cement with 4-META (5%). Conclusion: According to the results of this pilot study, the addition of 4-META (10%) to silane caused a significant improvement in µTBS to light-cure cement. The addition of 4-META in all concentrations significantly improved the µTBS to Enamic ceramic in the use of dual-cure cement; however, it had no significant effect on µTBS of Celtra Duo. Nonetheless, the results should be interpreted with caution due to the relatively small sample size.

Effect of diode laser irradiation on bond strength of resin cements to high-translucent zirconia.

Treatment of acid-resistance high-translucent zirconia prior to luting procedures is usually carried out with sandblasting. Considering that this process could lead to the formation of cracks on the zirconia surface, laser irradiation became an alternative to sandblasting. The effect of diode laser, however, was never investigated under this context. Therefore, this study aimed to evaluate the effect diode laser irradiation on the bond strength between zirconia and two resin cements after 48-hour and 12-month water aging. Slabs of high-translucent zirconia were sandblasted with 50-µm Al2O3 particles (SB), irradiated with diode laser (DL), or SB+DL. All slabs were etched with 10% hydrofluoric acid and layered with a universal adhesive. Plastic tubes with 0.8-mm internal diameter positioned on treated zirconia surfaces were used as matrices to insert a dual- (DUAL) or a light-cure (LC) resin cement. All specimens were light-cured for 40 seconds at 1000 mW/cm2 and submitted to the µSBS test after 48-hour or 12-month water storage. Data were statistically analyzed with a three-way analysis of variance (p<0.05). The µSBS of DUAL was higher than LC only after 12 months for SB or SB+DL-treated zirconia (p<0.05); in addition, SB+DL resulted in higher µSBS than DL only for DUAL resin cement (p<0.05). The 12-month aging resulted in higher µSBS for DUAL resin cement luted on SB or SB+DL-treated zirconia, as well as for LC luted on DL-treated zirconia (p<0.05). Most of the DUAL specimens presented adhesive failures after 48 hours. After 12 months, the majority of DUAL specimens luted on DL or SB+DL-treated zirconia presented adhesive failures. The use of dual-cure resin cement on sandblasted or sandblasted and diode laser-irradiated zirconia exhibited superior bond strength after aging. Key words:Microshear bond strength, Resin cement, Diode laser, Zirconia, Sandblasting.

Influence of Mono- and Multiwave Light-curing Units on the Microhardness and Degree of Conversion of Light-cured Resin Cements.

This study evaluated the Knoop hardness (KH, N/mm2) and degree of conversion (DC, %) on the margins of light-cured resin cements with different photoinitiators using a single light-curing unit (LCU) with two heads (mono- and multiwave). Three types of resin cements were used with different photoinitiators: Megalink Esthetic (Odontomega, São Paulo, Brazil) with a camphorquinone photoinitiator; Allcem Veneer (FGM, Joinville, Brazil) with the Advanced Polymerization system (APS), and Variolink Esthetic LC (Ivoclar Vivadent, Schaan, Liechtenstein). Thirty samples were collected and divided into six groups (n=5 each). The resin cement samples were made into the shape of a maxillary right central incisor and photoactivated under a 0.5-mm-thick ceramic sheet. A single LCU (Radii Xpert, SDI) with two heads (mono- and multiwave) was used. The tip of the LCU was positioned at the center of the sample in a standardized manner. Raman spectroscopy was performed to evaluate the DC, and KH was evaluated through the Knoop microhardness test. Five regions were evaluated: cervical, mesial, buccal (center), distal, and incisal. There was a significant difference in the DC only for the type of cement (p<0.001), indicating that the cement with the APS photoinitiator presented excellent results. There were significant differences in the type of cement (p<0.001), type of light (p<0.001), region (p<0.001), and the interaction between the type of cement and type of light (p<0.001). The resin cement with the APS photoinitiator cured with monowave light showed the highest KH values. The beam profiles of all groups, with and without the interposition of ceramic and resin cement, were examined by light transmission. The cement with the APS photoinitiator presented the best results with respect to the DC and KH. In comparison with mono- and multiwaves, the LCU may not be a determining factor for the properties of light-cured resin cements. The buccal region showed the best results for DC and KH, indicating the need for a greater amount of light-curing at the cementation margins.

Effects of Ceramic Translucency and Thickness on Polymerization of a Photosensitive Resin Cement

We investigated the effects of lithium disilicate ceramic thickness and translucency on the degree of polymerization of light-cured resin cement using the measure of hardness. Lithium disilicate specimens of three translucencies (low, medium and high) were prepared to four thicknesses (0.5, 1.0, 2.0 and 3.0 mm). A light-cured resin cement was cured through each of the ceramic specimens using a handheld curing light for 50 s. A 3D printed jig was used to achieve a uniform thickness of the resin cement. Directly cured resin cement was used as the control. Hardness was measured using nano-indentation to determine the degree of polymerization of the resin cement. Two-way ANOVA and Tukey post hoc tests were used to evaluate interaction between translucency and thickness. Hardness values from control specimens were assessed using the two-tailed t-test with the Bonferroni approach. The translucency of the specimens significantly influenced the hardness (p &lt; 0.001), where a negative linear relationship between cement hardness and ceramic thickness was present for low translucency and high translucency. However, at a 0.5 mm thickness, all specimens showed similar hardness regardless of the translucency. The translucency of ceramics affected the hardness, and hence polymerization, of light-cure resin cement. However, the effect of increased thickness was a more significant factor.

Finite element stress analysis of dental cement application on endocrown and onlay restoration.

The aim of the study was to evaluate the influence of resin cement material types on tooth with endocrown and onlay restorations. The first molar was scanned using Micro-CT and underwent a modelling process to obtain the 3D model for computational simulation. Eight models were simulated in the current study with two loading conditions (720N vertical load and 200N oblique load), two types of restoration (onlay and endocrown restorations), and two resin cement variants (dual-cure resin cement and light-cure resin cement). The tooth with onlay restoration showed a significant stress reduction (up to 70%) when using light-cure resin cement compared to dual-cure resin cement. In contrast, types of cement did not affect stress distribution in the tooth with endocrown restoration. The current study found that dual-cure resin cement was preferable in Endocrown and Onlay restorations, due to dual-cure resin cement provided better bond strength compared to light-cure resin cement.

Color stability of dual-cured and light-cured resin cements: A systematic review and meta-analysis of in vitro studies.

This systematic review and meta-analysis aimed to evaluate the difference in the color stability of light-cured and dual-cured resin cements. Two separate reviewers used the PubMed, Scopus, Web of Science, Embase, and Scielo databases to execute the systematic review. For the analysis, studies that evaluated the color stability of dual-cured and light-cured resin cements over time were used. The random effects model was used in the meta-analysis. Analyses of subgroups were carried out based on the aging technique. The methodological quality of each in vitro study was evaluated in accordance with the parameters of a prior systematic review. From all databases, a total of 2223 articles were retrieved. Following the screening of titles and abstracts, 44 studies were selected for full text review, and a total of 27 articles were used for the qualitative analysis. Finally, 23 articles remained for the qualitative analysis. The majority of studies were labeled as having a medium risk of bias. The global analysis showed that the dual-cure resin cements had considerably greater differences in the color change (p=0.006). A high heterogeneity index (86%) was found in the analysis. The best available in vitro evidence suggests that dual-polymerizing cement has higher color variation than light-polymerized materials. To reduce the likelihood of color change after the luting of thin ceramic restorations, clinicians should employ light-polymerizable resin cements.

Color Stability and Degree of Conversion of Light-cured Resin Cements

Objective: To evaluate the color stability and degree of conversion of light-cured resin cement with different activator-initiator systems using LED lights with different wavelengths (polywave x monowave). Materials and Methods: Sixteen resin cement samples were made using a circular silicone matrix (7 mm diameter, 0.5 mm thickness) for each of the following tested materials: Variolink Esthetic LC (Ivoclar, color Light+); RelyX Veneer (3M ESPE, color A1); Filtek Z350XT flow resin (3M ESPE, color A1); Allcem Veneer APS (FGM, color A1); NX3 Light cure (Kerr, color A1). Half of the samples were photocured with a monowave LED light (Elipar Deep Cure), and the other half with a polywave LED light (Valo Grand). The initial color of each cement was measured using a high translucency ceramic sample simulating ceramic venner. Color measurements were performed with a reflectance colorimetric spectrophotometer and the data was collected according to the CIE L* a* b* system in two steps. The degree of conversion was measured using an infrared spectrometer by Fourier transform (FTIR / ATR) and the absorbance method. Statistical analysis was performed using ANOVA repeated measures and Tukey’s post hoc tests (p &lt;0.05). Results: For the color analysis, there were no significant differences between the cement related to time versus light curing (p = 0.084) and also related to time versus cement versus light curing (p = 0.142). Among the factors, there was only a statistically significant difference for the type of cement (p &lt;0.01). In contrast, for the photocuring device (p = 0.504) and the interaction between them (p = 0.738), there was no significant difference. For the degree of conversion analysis, it showed a statistically significant difference for both factors, resin cements (p &lt;0.01) and light curing units (p &lt;0.01). Conclusion: The color stability of RelyX cement is low compared to other cements, while Variolink cement presented the best degree of the conversion value.

Interaction of different concentrations of 10-MDP and GPDM on the zirconia bonding.

To analyze the influence of different concentrations of 10-MDP and GPDM used, combined or not, on the bonding to zirconia. Specimens of zirconia and a resin-composite (7mm length, 1mm width, and 1mm thick) were obtained. The experimental groups were obtained according to the functional monomer (10-MDP and GPDM) and the concentrations (3 %, 5 %, and 8 %). For the groups with combined 10-MDP and GPDM, the agents were used with a proportion of 50 %/50 % wt until reaching the 3 %, 5 % and 8 % concentrations. All monomers were diluted in ethanol to obtain the primers. Two control groups were established: ethanol (negative control) and a commercial reference Monobond N (positive control). The zirconia surface treatment was performed with the primer application followed by the bonding to a resin-composite sample with a light-curing resin cement. Twenty-four hours after the adhesive procedure, a microtensile test was performed and the failure pattern of each sample was analysed with a stereoscopic magnifying glass. Data were analysed by a two-way ANOVA and Dunnet test. All experimental primers presented a higher bond strength than the negative control (ethanol). Excepting the 8 % GPDM primer, all groups presented statistically similar bond strength compared to the positive control, with a predominance of adhesive failure. 10-MDP, GPDM, and the combination of both for the concentrations tested promote an effective chemical bonding to zirconia. However, using 10-MDP and GPDM in the same primer has no synergistic effect.

Influence of thickness and degree of opacity of lithium disilicate on the degree of conversion and bond strength of resin cements

The aim of this study was to evaluate the influence of various opacities and thicknesses of lithium disilicate on the degree of conversion (DC) of two resin cements and on their bond strength (BS) to the ceramic. Two hundred and forty ceramic samples of lithium disilicate with high translucency (HT), low translucency (LT), and medium opacity (MO) were obtained from IPS e. max CAD in five different thicknesses. Light-cured and dual-cured resin cements were used for DC (n = 9) and BS (n = 8). Cement samples were light-cured under ceramic samples and analyzed using a Raman confocal spectrometer to determine the DC. For BS, resin cement cylinders were fabricated using ceramic samples which were thsen subjected to a microshear bond strength test. The mean values were provided for statistical analysis. The increase in thickness resulted in a decrease in DC for both cements under all experimental conditions, but only affected the BS of the light-cured cement for the MO ceramic. Comparing the opacities, the most translucent ceramics with particular thicknesses exhibited higher DC values than the less translucent ceramics. The LT and MO ceramics with certain thicknesses exhibited the highest BS values than the HT. The dual-cured cement generally showed highest values in both analyses than the light-cured cement. A thicker and more opaque ceramic material can reduce the DC of the cement. The BS decreases with the increasing thickness of the more-opaque ceramics.

Clinical survival of No-prep indirect composite laminate veneers: a 7-year prospective case series study

BackgroundThe no preparation technique which is a reversible form of treatment characterized by the absence of tooth tissue preparation and preserves the soft tissue architecture while preserving all natural tooth structures is indicated in cases where the tooth structure allows material to be added. The aim of this study is to evaluate the clinical performance and survival rates of indirect composite laminate veneers with no preparation after 7 years.Materials and methodsA total of 80 indirect composite veneers were placed on maxillary anterior teeth in 35 patients (n = 80). Diastema (n = 64), wedge tooth anomalies (n = 9) and re-shaping (n = 7) were the main indications for veneer treatments. All laminate veneers were fabricated with an indirect microhybrid composite material (Gradia, GC Dental). No tooth preparation was performed. Light-cured resin cement (Choice 2, Bisco) was used to lute the veneers. Composite veneers were evaluated using Modified United States Public Health Service criteria. Survival rates of the veneers were calculated using Kaplan-Meier statistics. The data containing the results of the USPHS criteria at baseline, 2 years and 7 years was statistically analyzed using Wilcoxon Signed Rank test at the 0.05 level of significance.ResultsThe overall survival rate was 91.3%. After 7 years, 7 absolute failures including 4 debonding (marginal adaptation, score 4) and 3 fractures (fracture of restoration, score 3) were noted. Color match was scored as 1 (n = 34) and 2 (n = 15). Slightly rough surfaces (41 of 73 laminates) and slight marginal discoloration (15 of 73 laminates) were noted. The overall scores after 84 months were significantly higher than the baseline scores for the marginal adaptation (p = 0.008), color match (p = 0.000), marginal discoloration (p = 0.000), surface roughness (p = 0.000), and fracture of restoration (p = 0.001) criteria.ConclusionsIn this study, indirect composite veneers without any preparation on maxillary anterior teeth showed acceptable performance in terms of both survival rate and quality of restorations. This procedure offers a predictable and successful treatment that ensures maximum preservation of the intact tooth.