Effects of different surface treatments on surface topography and bond strength in the repair of fiber-reinforced dentin composite.

OBJECTIVE: This study aimed to evaluate the effects of different surface treatments on the repair bond strength between a fiber-reinforced dentin composite and a posterior composite. METHODS: Forty fiber-reinforced dentin composite resin blocks (4 mm × 4 mm × 4 mm) were separated into eight groups (n = 5) according to the surface preparation methods: (G1) negative control group, (G2) adhesive application, (G3) 50% dimethylsulfoxide (DMSO) application, (G4) 50% DMSO + adhesive application, (G5) 37% phosphoric acid etch + adhesive application, (G6) air abrasion + adhesive application, (G7) 37% phosphoric acid etch + 50% DMSO application + adhesive application, and (G8) air abrasion +50% DMSO application + adhesive application group. The composite surfaces were repaired in two layers with a posterior composite. Composite sticks were subjected to a micro tensile bond strength (µTBS) test. Fractured surfaces were evaluated using a stereomicroscope (×25). Short fiber-reinforced composite samples' surfaces were investigated by scanning electron microscope (SEM). Shapiro Wilk, one-way ANOVA, and Tukey HSD tests were used for statistical evaluation. RESULTS: The highest average (µTBS) values were observed in G8, whereas the lowest mean µTBS values were evident in the G1 group. Statistically significant µTBS values were found in all adhesive-applied groups when compared with the negative control group. Notably, the application of 50% DMSO without adhesive did not lead to a statistically significant increase in µTBS values. SEM images demonstrated that acid etching partially eliminated residues on the composite surface, while air abrasion had a detrimental effect on the integrity of fiber structures. CONCLUSION: In the repair of fiber-reinforced dentin composite with a posterior composite, adhesive application is an effective approach. The treatment of 50% DMSO without adhesive did not confer a statistically significant advantage, and the supplemental use of acid etch or air abrasion did not show an additional benefit compared to adhesive-only repairs. CLINICAL SIGNIFICANCE: Adhesive application emerges as a potent and effective strategy for the repair of bur-roughened fiber-reinforced dentin composites. With its limitations, the study highlights the efficacy of adhesive-only repairs without the necessity for additional surface treatments.

Bulk-fill composite in challenging cavities: conversion rate, solubility, and water absorption analysis.

In a deep, curved cavity, polymerization of a bulk fill composite can be challenging. The aim of this study was to investigate the solubility, water absorption, and conversion rate of bulk-fill composite samples prepared using molds with various slope angles. Bulk-fill composite resin (Filtek One Bulk Fill) was placed into cylindrical Teflon molds with a depth of 4 mm, angled at varying degrees (90°, 75°, 60°, 45°). Two different LED light-curing units (VALO Cordless, iLed Curing Light) were used to cure the samples. Polymerizations were performed at three different distances (0 mm, 2 mm, and 4 mm). Five samples per group were used, resulting in a total of 24 groups. The Fourier Transform Infrared Spectrometer was utilized to evaluate the conversion levels of the samples. Water sorption and solubility values were determined by storing the composites in distilled water at 37 °C for 21 days. The VALO light-curing unit applied closest to samples inserted in a 90° angulation mold had the highest mean degree of conversion (41.55%), while iLED light-curing unit group that applied from 4 mm to the samples inserted in a 45° angulation mold had the lowest mean conversion (8.97%). The angle of the cavity and the distance at which the light-curing unit is applied significantly affected bulk-fill composite resin conversion. In addition, the choice of light-curing unit impacted the conversion levels. However, with the tested conditions, the water sorption and solubility values of polymerized composite resin samples remain unaffected by these factors.

Can We Prevent Coffee Stains on Teeth?

This study evaluates whether some common beverages treated before coffee could protect or increase tooth staining caused by coffee. Initial color of 50 incisor teeth were measured with a spectrophotometer and recorded according to CIELAB color system. Teeth were randomly divided into five groups, water (control), milk, green tea, orange juice, and cola (n = 10) and were kept in selected beverage for 10 min. Immediately afterward, they were immersed in coffee and allowed to stand for 24 h. The treatment was repeated for 5 days. At the end of the fifth day, L*a*b* color measurements of the teeth were repeated. Calcium, phosphorus, potassium, and magnesium changes on representative teeth surfaces were also investigated with X-ray fluorescence spectroscopy. Color differences were calculated with both CIEab and CIE00 formulas. Groups were compared with Kruskal-Wallis test complemented by the Bonferroni correction and Mann-Whitney U test for pairwise comparisons (P = .05). The teeth submitted to coffee challenges after distillated water or beverages showed a perceptible color change. Soaking in cola or orange juice before coffee immersion caused severe tooth discoloration. All the beverages tested here were not able to protect the tooth from coffee staining. People should be informed that some acidic beverages consumed before a coffee can worsen the coffee-based tooth discolorations.

Effect of Photobiomodulation on Secretion of IL-6 and IL-8 by Human Gingival Fibroblasts In Vitro.

Objective: The aim of this study was to evaluate the effects of 940-nm diode laser irradiation on proinflammatory cytokine secretions [interleukin (IL)-6 and IL-8] by human gingival fibroblasts in vitro. Background: Photobiomodulation has been routinely used in many dental procedures; however, the exact biological action mechanism of photobiomodulation and its therapeutic benefits have not been established. Methods: Cells derived from systemically healthy individuals were treated with three different laser parameters-6 J for 20 sec [0.84 J/cm2 (0.04 W/cm2)], 10 J for 20 sec [1.4 J/cm2 (0.07 W/cm2)], and 14 J for 20 sec [1.97 J/cm2 (0.09 W/cm2)]-in the presence and absence of 1 µg/mL lipopolysaccharide (LPS) stimulation. Laser irradiations were carried out by a 940-nm diode laser device in continuous pain therapy mode with a deep tissue handpiece. Changes in cell viability, cytokine secretions, and mitogen-activated protein kinase pathway expressions were investigated, and results were compared with negative (medium) and positive control (1 µg/mL LPS) groups. The data obtained were statistically analyzed by the Mann-Whitney U test for pairwise comparisons among groups at the 0.05 level of significance. Results: Laser therapy with 0.84-1.4 J/cm2 amplified IL-6 and IL-8 secretions, whereas 1.97 J/cm2 suppressed IL-6 and IL-8 release in LPS-stimulated cells. Cell viability did not show a variation with photobiomodulation. Conclusions: These results demonstrate that photobiomodulation can alter IL-6 and IL-8 release, with cytokine suppression potency at a relatively high dose, as demonstrated previously. However, in contrast, we found that a low level of stimulation (6 J) in the presence of inflammation (LPS stimulation) may further enhance IL-6 and IL-8 release. We also found that p38 and ERK1/2 pathways are activated by LPS as well as by photobiomodulation.

Effect of the lasers used in periodontal therapy on the surfaces of restorative materials.

The present study aimed to reveal potential damage of the lasers, which are used as an alternative to manual instruments in periodontal therapy, might cause to the surface of restorative materials. Four different restorative materials were used: a glass-ionomer cement (GIC), a flowable composite (FC), a universal composite (UC) and an amalgam. Ten cylindrical samples (8 mm × 2 mm) were prepared for each restorative material. Two laser systems were used in subgingival curettage mode; an 940 nm diode laser (Epic Biolase, Irvine, CA) and an Er,Cr:YSGG laser (Waterlase iPlus, Biolase, Irvine, CA). After laser irradiation, roughness of the sample surfaces was measured using a profilometer. Additionally, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses were performed to evaluate the morphology and surface deformations of the restorative materials and surfaces. The laser irradiation did not affect the surface roughness of any restorative materials relative to that of the control group (p > 0.05) except for the Er,Cr:YSGG treatment on GIC (p < 0.05). SEM and AFM images verified the results of the surface roughness tests. Within the limitations of the present study, it was demonstrated that Er,Cr:YSGG and diode lasers, aside from the Er;Cr:YSGG treatment on GIC, caused no harmful surface effects on adjacent restorative materials. SCANNING 38:227-233, 2016. © 2015 Wiley Periodicals, Inc.

Repair bond strength of composite resin to sandblasted and laser irradiated Y-TZP ceramic surfaces.

This study investigated the effects of different surface treatments on the repair bond strength of yttrium-stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP) zirconia to a composite resin. Sixty Y-TZP zirconia specimens were prepared and randomly divided into six groups (n = 10) as follows: Group 1, surface grinding with Cimara grinding bur (control); Group 2, sandblasted with 30 µm silica-coated alumina particles; Group 3, Nd:YAG laser irradiation; Group 4, Er,Cr:YSGG laser irradiation; Group 5, sandblasted + Nd:YAG laser irradiation; and Group 6, sandblasted + Er,Cr:YSGG laser irradiation. After surface treatments, the Cimara(®) System was selected for the repair method and applied to all specimens. A composite resin was built-up on each zirconia surface using a cylindrical mold (5 × 3 mm) and incrementally filled. The repair bond strength was measured with a universal test machine. Data were analyzed using a one-way ANOVA and a Tukey HSD test (p = 0.05). Surface topography after treatments were evaluated by a scanning electron microscope (SEM). Shear bond strength mean values ranged from 15.896 to 18.875 MPa. There was a statistically significant difference between group 3 and the control group (p < 0.05). Also, a significant increase in bond strength values was noted in group 6 (p < 0.05). All surface treatment methods enhanced the repair bond strength of the composite to zirconia; however, there were no significant differences between treatment methods. The results revealed that Nd:YAG laser irradiation along with the combination of sandblasting and Er,Cr:YSGG laser irradiation provided a significant increase in bond strength between the zirconia and composite resin.

Efficacy of ceramic repair material on the bond strength of composite resin to zirconia ceramic.

OBJECTIVE: The aim of this study was to evaluate the shear bond strength of composite resin in five different repair systems. MATERIALS AND METHODS: Sixty specimens (7 mm in diameter and 3 mm in height) of zirconia ceramic were fabricated. All specimen surfaces were prepared with a 30 µm fine diamond rotary cutting instrument with water irrigation for 10 s and dried with oil-free air. Specimens were then randomly divided into six groups for the following different intra-oral repair systems (n = 10): Group 1, control group; Group 2, Cojet system (3M ESPE, Seefeld, Germany); Group 3, Cimara® System (Voco, Cuxhaven, Germany); Group 4, Z-Prime Plus System (Bisco Inc., Schaumburg, IL); Group 5, Clearfil™ System (Kuraray, Osaka, Japan); and Group 6, Z-Bond System (Danville, CA). After surface conditioning, a composite resin Grandio (Voco, Cuxhaven, Germany) was applied to the zirconia surface using a cylindrical mold (5 mm in diameter and 3 mm in length) and incrementally filled up, according to the manufacturer's instructions of each intra-oral system. Each specimen was subjected to a shear load at a crosshead speed of 1 mm/min until fracture. One-way analysis of variance (ANOVA) and Tukey post-hoc tests were used to analyze the bond strength values. RESULTS: There were significant differences between Groups 2-6 and Group 1. The highest bond strength values were obtained with Group 2 (17.26 ± 3.22) and Group 3 (17.31 ± 3.62), while the lowest values were observed with Group 1 (8.96 ± 1.62) and Group 6 (12.85 ± 3.95). CONCLUSION: All repair systems tested increased the bond strength values between zirconia and composite resin that used surface grinding with a diamond bur.

Resin cement to indirect composite resin bonding: effect of various surface treatments.

Debonding at the composite-adhesive interface is a major problem for indirect composite restorations. The aim of this study was to evaluate the bond strength (BS) of an indirect composite resin after various surface treatments (air-abrasion with Al2O3, phosphoric acid-etchig and different applications of NdYAG laser irradiations). Fifty composite disks were subjected to secondary curing to complete polymerization and randomly divided into five experimental groups (n = 10) including Group 1, untreated (control); Group 2, phosphoric acid-etched; Group 3, air-abrasion with Al2 O3 ; Group 4, Nd:YAG laser irradiated with non-contact and Group 5, Nd:YAG laser irradiated with contact. They were then bonded to resin cement and shear BS was determined in a universal testing device at a crosshead speed of 1 mm/min. One way analysis of variance (ANOVA) and Tukey post-hoc tests were used to analyze the BS values. The highest BS value was observed in Group 4 and followed by Group 3. Tukey test showed that there was no statistical difference between Group1, 2 and 5. Furthermore, differences in BSs between Group 4 and the other groups except Group 3 were significant (p < 0.05) and also there were significant differences in BSs between Group 3 to 1 and Group 3 to 2 (p < 0.05). This study reveals that air-abrasion with Al2 O3 and Nd:YAG laser irradiation with non-contact provided a significant increase in BS between indirect composite and resin cement.

Color recovery effect of commercial mouth rinses on a discolored composite.

STATEMENT OF THE PROBLEM: Several mouth rinses promising whiter smiles are on the market today. PURPOSE: The aim of this study was to investigate the in vitro color recovery effects of six commercial mouth rinses on a stained universal composite resin. MATERIALS AND METHODS: Sixty composite resin specimens were prepared with a universal composite resin (Filtek Z250), and baseline Commission Internationale de l'Eclairage L*a*b* color coordinates were measured by spectrophotometry. Specimens were subjected to two cycles of staining with coffee and cherry juice for 2 weeks, followed by immersion into mouth rinses (Listerine Whitening Vibrant, Scope White, Crest 3D White, Signal White Now, Oral-B 3D White, and Colgate Optic White). Changes in color coordinates were measured after staining and after 24- and 72-hour immersion periods. Color alterations were calculated both by CIEDE2000 and CIELAB formulas. Data were submitted to analysis of variance for repeated measures and Tukey's multiple comparison test. (α = 0.05). RESULTS: Immersion in colorant beverages caused perceptible discolorations on composite resin samples (ΔE00 > 2.25 and ΔEab * > 3.46). Immersion period and mouth rinses were significant factors for the color recovery procedure (p < 0.001). The interaction between immersion time and WMR was also significant (p < 0.001). CONCLUSIONS: The color recovery of composite resin was affected by the brand of mouth rinse and the period of immersion. CLINICAL SIGNIFICANCE: This in vitro study revealed that tested mouth rinses are capable of recovering discolored composite resin colors after a prolonged exposure period.

Effect of water storage and additional polymerization on the color parameters of flowable resin composites.

AIMS: Tooth colored dental restorative materials should maintain their chromatic properties throughout their service period. The aim of this study was to examine the possible color changes of flowable resin composite filling materials following water storage. The effect of additional light curing on color stability of restorative materials was also investigated. MATERIALS AND METHODS: Six brands of light-cured flowable resin composites of the same shade (A3) were prepared from two groups generated by curing for 20 or 60 seconds. The initial color parameters of the flowable composite samples were measured with a dental colorimeter according to the CIELAB color scale, and the samples were stored in distilled water at 37°C. Following 2 weeks' water storage, the measurements were repeated. The color differences (ΔE*(ab)) were calculated according to the CIELAB formula. Statistical differences between the measurements were analyzed by ANOVA and Duncan's tests. RESULTS: No initial color variation between the samples cured for 20 seconds and 60 seconds was perceptible (ΔE*(ab)<3.3). However, after 2 weeks' water storage, a noticeable color change, ΔE*(ab)>3.3, was detected in Eco-flow, Filtek Supreme and Grandio samples in both polymerization groups. CONCLUSION: Flowable resin composites may exhibit a significant color change as a result of water storage. Sixty seconds exposure period does not influence the final color. CLINICAL SIGNIFICANCE: Clinicians should be aware of color shifts in flowable resins.

The color differences of direct esthetic restorative materials after setting and compared with a shade guide.

BACKGROUND: The authors conducted a study to evaluate esthetic restorative materials' color differences after setting and color matching between set materials and a shade guide. MATERIALS AND METHODS: The authors evaluated 13 resin-based composites, one silorane-based composite, two polyacid-modified resin composites and one conventional glass ionomer cement. They measured the color parameters of the samples, which were 8 millimeters in diameter and 1.5 mm in thickness, before and after they were set according to the Commission International de l'Eclairage (CIE) L*a*b* color scale relative to standard illumination against a white background by means of a dental colorimeter. They also compared the final colors of the restorative materials with a shade guide. RESULTS: Color difference values for each restorative material ranged from 3.25 to 14.04. With the exception of Fuji IX (GC, Tokyo), Filtek P60 (3M ESPE) and Te-Econom (Ivoclar Vivadent), the restorative materials exhibited a perceptible color change after setting. Color difference values between the set materials and the shade guide tabs ranged from 1.86 to 11.83. With the exception of Filtek Supreme XT (3M ESPE) and Fuji IX, the materials exhibited a perceptible difference. CONCLUSION: Most of the materials tested exhibited a significant color change after polymerization and did not match the shade guide tab after undergoing light curing.

Restoration of non carious cervical tooth surface loss lesions using composite and dentin pins: report of two cases / Restauração de lesões não cariosas cervicais utilizando compósitos e pinos dentinários: relato de dois casos

OBJETIVO: Ilustrar um método alternativo para a restauração de perdas cervicais não cariosas utilizando compósitos e pinos dentinários. MÉTODO: Nos casos apresentados, extensas lesões cervicais não cariosas foram restauradas com resinas compostas e pinos dentinários, para avaliação dos resultados. RESULTADOS E CONCLUSÕES: Os pinos de dentina podem ser um suporte alternativo na restauração de dentes com grandes lesões cervicais não cariosas.

OBJECTIVE: To illustrate an alternative method for the restoration of non carious cervical tooth surface loss lesions using composite and dentin pins. METHOD: In these two cases, extensive Class V non carious cervical tooth surface lesions were restored with composite resins and dentin pins and results were evaluated. RESULT AND CONCLUSION: Dentin pins could be an alternative support in large non carious cervical lesions.

Cytotoxic effects of TEGDMA on THP-1 cells in vitro.

OBJECTIVE: Resin based dental materials are not stable in the oral environment and may release their components into biological media. These components may include substances such as triethylene glycol dimethacrylate (TEGDMA), which is a major co-monomer of dental resin materials. This release can trigger host immune and inflammatory responses against foreign materials, mediated by monocytes. The aim of this study was to investigate the possible cytotoxic effects of TEGDMA on human THP-1 monocytes. MATERIAL AND METHODS: THP-1 cells were exposed to various concentrations of TEGDMA (0.5 mM, 1 mM, 2 mM, 4 mM, or 8 mM) for 48 hours. An untreated group was used as control. The effects of TEGDMA on cell proliferation, cell viability and apoptosis were analyzed by light microscopy. RESULTS: Cell proliferation was inhibited by 4 mM and 8 Mm TEGDMA. Increasing TEGDMA concentrations caused a decrease in cell viability. All TEGDMA concentrations used in this study had an apoptotic effect on THP-1 cells when compared with the control group. CONCLUSIONS: The dental monomer TEGDMA had an adverse effect on cell proliferation and exerted an apoptotic and toxic effect on THP-1 cells in a concentration-dependent manner.

Restoration of crown fractures with a fiber post, polyethylene fiber and composite resin / Restauração de fraturas coronárias com pinos de fibra, de polietileno e de resina composta: técnica restauradora combinada com dois relatos de caso

OBJECTIVE: To describe the treatment of two patients who had horizontal crown fractured maxillary incisors a few years after endodontic treatment. METHOD: The 23 and 19-year-old male patients presented to Atatürk University Dentistry Faculty with complex crown fractures. The treatment includeda glass fiber reinforced root canal post, a fiber ribbon core and restoration with a universal resin composite. RESULTS AND CONCLUSION: The one-year follow-up examinations showed thatthe restorations were still in place and successful.

OBJETIVO: Descrever o tratamento de dois pacientes com fraturas horizontais de coroas de incisivos superiores, alguns anos após tratamento endodôntico. MÉTODO: Os pacientes, ambos do sexo masculino, com 23 e 19 anos de idade, apresentaram-se na Faculdade de Odontologia da Universidade Ataturk com fraturas coronárias complexas de incisivos superiores. O tratamento consistiu de utilização de pinos intracanais reforçados com fibra de vidro, tiras de fibra de vidro e restauração com uma resina composta universal. RESULTADOS E CONCLUSÃO: Oacompanhamento do paciente por um ano mostrou o sucesso do tratamento.