Characterization of a novel TiF4 inclusion complex and its in vitro evaluation on inhibiting enamel demineralization

Titanium tetrafluoride (TiF4) is an anticariogenic agent with high remineralizing potential. However, the acidic pH of TiF4 solution can limit its clinical application. Dendrimers have been reported to show promising remineralizing potentials. Thus, the present study aimed to prepare and characterize a new TiF4 dendrimer inclusion complex and evaluate its ability to inhibit enamel demineralization under pH cycling conditions. PEG-citrate dendrimer and TiF4-dendrimer inclusion complex were synthesized and their molecular structures were evaluated using FTIR, H NMR, and LC-MS tests. Forty-eight enamel samples were prepared randomly and divided into four groups: distilled water (negative control), TiF4 solution (T), dendrimer solution (D), and TiF4-dendrimer solution (TD). The microhardness of the samples was measured initially. Next, the samples underwent pH-cycling, were exposed to the solutions, the microhardness was measured again, and microhardness loss was calculated. EDX analysis was performed on the surface and cross-sectional segments of the samples. The microhardness loss was significantly higher in control (-65.1± 6.0) compared to other groups. No significant difference was observed between T (-47.9± 5.6) and D (-41.7± 12.0), and also D and TD (-40.5± 9.4) in this regard. Microhardness loss was significantly higher in T compared to TD group. The T+D samples showed similar fluoride and titanium content in both surface and subsurface regions, while the T group had higher concentrations in the surface region. Moreover, the DT solution had a higher pH of 3.4 compared to the T solution's pH of 1.1. TiF4-dendrimer solution showed similar efficacy in inhibiting demineralization comparable to TiF4 solution, with the added advantage of having a higher pH.

Evaluation of cytotoxicity and antibacterial activity of different pulp capping liners

This study compares the cytotoxicity and antibacterial activity of five pulp capping liners. This in vitro study was conducted on Fuji II LC glass ionomer, Dycal, Calcimol LC, TheraCal LC, and ACTIVA BioACTIVE. For cytotoxicity, the (MTT) methyl thiazolyl tetrazolium assay was performed on 3 samples from each group of human dental pulp cells (HDPSCs) after 24 h of incubation. The direct contact test (DCT) for antibacterial activity, 6 samples (3 for each material, and 3 for negative control), from each liner were made to evaluate Streptococcus mutans (S. mutans), Lactobacillus casei (L. casei), and Lactobacillus acidophilus (L. acidophilus). Data were analyzed by one-way ANOVA and Tukey's post-hoc test (alpha = 0.05). Data analysis showed that the cytotoxicity of the materials was significantly different (p < 0.001). Fuji II LC and ACTIVA BioACTIVE showed strong cytotoxicity, TheraCal LC moderate cytotoxicity, and Dycal and Calcimol LC slight cytotoxicity. The analysis also revealed a significant difference among the materials regarding antibacterial activity (p < 0.001). Tukey's test showed that the mean percentage of reduction in colony count was significant for all liners compared with the positive control (p < 0.001). The mean percentage of reduction in colony count for Dycal was significantly greater than that of Fuji II LC (p = 0.014), Calcimol LC (p = 0.003), and TheraCal LC (p = 0.001). ACTIVA BioACTIVE did not significantly differ from the other materials as regards antibacterial activity. Dycal showed significantly higher antibacterial activity than the other materials.

Effect of Laser and Conventional Office Bleaching and Polishing on the Color Change of Stained Nanohybrid and Microhybrid Composite Resin

Aim

The present study investigated the effects of laser and conventional in-office bleaching, and polishing on the color of stained composite resin.

Materials and Methods

A microhybrid composite (Clearfil AP-X) and a nanohybrid composite (Grandio) were selected. Twenty-four discs (2 × 10 mm) for each composite were prepared. The samples were immersed in coffee solution (25 g of coffee in 250 mL water) for seven days. Then the samples were divided into three groups (n = 8) and the stains were removed using bleaching (with Opalescence Xtra Boost), diode laser irradiation with Heydent material and a Sof-Lex polishing kit. The L ∗a ∗b ∗ color parameters were determined using a spectrophotometer before and after immersion and after stain removal procedures, and the overall color changes (ΔE) were calculated. The data were analyzed with two-way analysis of variance.

Results

In the Clearfil composite resin group, the mean ΔE compared to the baseline using in-office bleaching, laser irradiation, and Sof-Lex polishing kit were 3.31, 3.35, and 4.93, respectively. These values with the Grandio composite resin were 3.31, 6.35, and 4.57, respectively. The highest capacity to remove stains was related to the conventional in-office bleaching method. Grandio composite resin underwent more color changes than Clearfil composite resin significantly (P-value < 0.05).

Conclusion

Both composite resins exhibited color changes after immersion in the discoloring solution. However, after staining-removing procedures, the ΔE values decreased. Decreases in the ΔE values were not sufficient to restore the color to that before immersion in the discoloring solution with any stain-removing methods.

Effect of Different Bleaching Methods on Monomer Release from Aged Microhybrid and Nanohybrid Resin Composites

Introduction

Recently, the application of laser-assisted bleaching has increased in dental practice. This method might affect the physical and chemical properties of resin composite and its monomer release. This study aimed to evaluate the effect of in-office, at-home, and laser-assisted bleaching on the monomer release (bisphenol A diglycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA)) from aged nanohybrid (Grandio, Voco) and microhybrid (Clearfil AP-X Esthetics, Kuraray) resin composites.

Methods

Thirty-two samples of each composite were prepared. The samples underwent aging procedure with UV light at 65°C for 100 hr. The samples were divided into 4 groups: OB: conventional in-office bleaching with Opalescence Boost PF 40% gel; HB: home bleaching with Opalescence PF 15% gel; LB: bleaching with JW Power bleaching gel followed by diode laser application; and C: control group without bleaching. Then, the samples were immersed in a solution containing 75% ethanol + 25% distilled water. The medium was renewed after 8, 16, 24 hr, and 7 days and was analyzed using high-performance liquid chromatography method to evaluate the monomer release. The data were analyzed using Two-way ANOVA and Post hoc Tukey test.

Results

The bleaching method had no effect on TEGDMA and BisGMA release in both composites while it affected UDMA release in nanohybrid composite; UDMA release was significantly higher in LB compared to control and also higher in OB and LB compared to HB. No difference was observed in the microhybrid composite in this regard.

Conclusion

Laser-assisted bleaching did not affect monomer release from microhybrid composite while it increased UDMA release from nanohybrid composite. The bleaching method had no effect on TEGDMA and BisGMA release.

Effect of charcoal-based dentifrices on surface roughness of an aged resin composite

BACKGROUND

Recently, the use of whitening dentifrice has increased among patients. However, these products might increase the surface roughness of composite restorations and make them more susceptible to discoloration and plaque accumulation. This study aimed to compare the effects of two charcoal-based dentifrices and other whitening dentifrices with different mechanisms of action on the surface roughness of an aged resin composite.

METHODS

Forty-five composite specimens were made (2 × 7mm) and their initial surface roughness was obtained using a Profilometer. The specimens were subjected to the Accelerated Artificial Aging (AAA) process for 300 hours. Then, the surface roughness of the specimens was reevaluated using the Profilometer. The specimens were randomly divided into 5 groups (N.=9), namely Control (Gc), Bencer (Gb; Sormeh Company, Tehran, Iran), Perfect White Black (Gp), Colgate Total Whitening (Gt), and Colgate Optic White (Go) (Colgate-Palmolive Company, New York, NY, USA). The specimens were brushed for 14 minutes with respective dentifrices. In the Gc group, the specimens were only brushed with distilled water. The surface roughness of the specimens was measured again. The data were analyzed using repeated measure ANOVA at a significance level of 0.05.

RESULTS

There was no significant difference in surface roughness parameters (Ra, Rq, Rz) between the groups, but in each group, the roughness parameters decreased after the aging procedure and increased after brushing significantly except for Rz parameter in Gb group which increased after aging and decreased after brushing.

CONCLUSIONS

None of the whitening dentifrices used in the present study had an adverse effect on the surface roughness of an aged composite resin.

Combined Effect of Fluoride Mouthwash and Sub-ablative Er:YAG Laser for Prevention of White Spot Lesions around Orthodontic Brackets

Background:

Development of white spot lesions (WSLs) around orthodontic brackets compromises esthetics and necessitates additional dental treatments.

Objectives:

This study aimed to assess the efficacy of fluoride mouthwash combined with Er:YAG laser irradiation for the prevention of WSLs around orthodontic brackets.

Methods:

Orthodontic brackets were bonded to 50 bovine incisors. The entire tooth surface was coated with acid-resistant varnish except for a margin around the brackets. The microhardness of the teeth was measured at the respective area using the Vickers hardness test. The teeth were then randomly divided into five groups (n=10) of control (Gc), Orthokin fluoride mouthwash (Gf), 100 mJ/cm2 Er:YAG laser (Gl), laser + mouthwash (Glf), and mouthwash + laser (Gfl). Then, the teeth underwent pH cycling according to the standard protocol for demineralization. The microhardness of the teeth was measured again, and the percentage of change in microhardness was calculated. The amount of calcium released during pH cycling was quantified using atomic absorption spectroscopy. Data were analyzed using one-way ANOVA and Tukey’s test.

Results:

Calcium release (indicative of demineralization) in the Gf, Gfl, and Glf groups was significantly lower than that in the Gc and Gl groups (P<0.05). The reduction in surface microhardness was also the same in the five groups with no significant difference (P>0.05).

Conclusion:

Fluoride mouthwash combined with Er:YAG laser or Er:YAG laser alone cannot decrease the incidence of WSLs around orthodontic brackets compared to fluoride mouthwash alone.

Microtensile Repair Bond Strength of a Composite After Accelerated Artificial Aging: Effect of the Air Abrasion, Bur, Er:YAG Laser, Two-Step Self-etch Bonding, and Universal Bonding Repair System

Introduction: Repair of old composite restorations is a conservative approach. This study sought to compare the effects of two adhesive systems on the bond strength of repaired composites prepared by three different surface treatments: erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation, air-abrasion, and bur preparation. Methods: Eight microhybrid (Polofil Supra, VOCO, Germany) composite resin blocks were fabricated. The blocks were aged and assigned to four groups as stated by the surface treatment: (I) air-abrasion (50 µ aluminum oxide particles), (II) diamond bur (fine grit), (III) Er:YAG laser (3 W output power, 300 mJ energy) and (IV) control. After surface treatment, the blocks were acid-etched and salinized. Each group was divided two subgroups, and the Clearfil SE Bond or All-Bond Universal was applied on their surface. Composite resin was bonded to the aged composites. The blocks were cut into eight samples, and the microtensile bond strength (MTBS) was measured. Results: The maximum MTBS was noted in the air-abrasion (25.1+6 MPa) group, followed by the Er:YAG laser (21.2+4.7 MPa). The mean MTBS in laser and air-abrasion groups was significantly higher than that in other groups (P<0.05). The mean MTBS was not significantly different between the laser and air-abrasion groups (P>0.05). Composite resin conditioning by All-Bond Universal in laser and air-abrasion groups yielded significantly higher MTBS than the Clearfil SE Bond (P<0.05). Conclusion: All surface treatments created acceptable bond strength. The surface treatment of the aged composite by the Er:YAG laser or air-abrasion along with the application of silane and All-Bond Universal provide high bond strength.

Vickers micro-hardness study of the effect of fluoride mouthwash on two types of CAD/CAM ceramic materials erosion

Background

The aim of this study was to evaluate the protective effects of fluoride mouthwash on the surface micro-hardness of two types of CAD/CAM ceramics after exposure to acidic solutions.

Methods

40 samples (5 × 5 × 3 mm³) were prepared from two different ceramics: Vitabloc Mark II CAD, and IPS e.max CAD. The samples were randomly divided into 5 groups in each ceramic (n = 8) immersed in different solutions: G_s: saliva: G_GA: gastric acid, G_AA: acetic acid, G_FGA: sodium fluoride + gastric acid, G_FAA: sodium fluoride + acetic acid. The microhardness of samples was measured before and after immersion in different solutions by Vickers microhardness tester. By subtracting the microhardness values after and before immersion, the microhardness changes of the samples were obtained. Data were analyzed by Two-way analysis of variance, one-way analysis of variance, and Tukey test (α = 0.05).

Results

Immersion in different solutions reduced the microhardness. Microhardness loss was significantly affected in G _FAA and G _FGA groups in both types of ceramics (P < 0.05). For Vitabloc Mark II groups, the microhardness loss was significantly higher in G_FAA and G_FGA compared to IPS e.max CAD P < 0.001).

Conclusion

Fluoride mouthwash in conjunction with acidic solutions may adversely affect microhardness of Vitabloc Mark II CAD, and IPS e.max CAD that may consequently compromise the clinical service. Vitabloc Mark II CAD was significantly more affected than IPS e.max CAD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02135-z.

Marginal microleakage and modified microtensile bond strength of Activa Bioactive, in comparison with conventional restorative materials

OBJECTIVES

This study aimed to assess the enamel and dentin marginal microleakage and dentin microtensile bond strength (μTBS) of ACTIVA BioACTIVE Restorative with and without a bonding agent compared with conventional restorative materials.

MATERIAL AND METHODS

For enamel and dentin microleakage, Class II boxes were prepared in the mesial (1 mm under the cementoenamel junction) and distal (1 mm above the cementoenamel junction) surfaces of 90 extracted human third molars. The teeth were randomly divided into five groups (n = 18): Group Z (G-Premio Bond + Filtek Z250 XT), Group X (G-Premio Bond + X-tra fil bulk-fill), Group AA (G-Premio Bond + Activa Bioactive restorative), Group A (Activa Bioactive restorative), and Group G (dentin conditioner + Fuji II LC Improve). The teeth were thermocycled, and their microleakage was quantified using the dye penetration test under a stereomicroscope. For dentin μTBS measurement, 12 specimens were fabricated in metal molds (1 × 1 × 12 mm³) for each group mentioned above, and a universal testing machine measured their μTBS. Data were analyzed using one-way analysis of variance (ANOVA), the Kruskal-Wallis test, and multiple comparisons tests.

RESULTS

Significant differences were noted among the groups in marginal microleakage and μTBS (p < .001). The highest mean microleakage scores at the enamel and dentin margins were noted in Group A, which had significant differences with other groups (p < .001). The highest μTBS was found in Group X, with significant differences with Group G and Group A (p < .05). The lowest µTBS was noted in Group A, with significant differences with Groups X, Group AA, and Group Z (p < .001).

CONCLUSIONS

Activa Bioactive without a bonding agent showed significantly lower µTBS to dentin, and higher microleakage at the enamel and dentin margins. Application of adhesive resin with Activa Bioactive provided a dentine bond strength and marginal seal comparable to other restorative materials.

Effect of whitening toothpastes containing activated charcoal, abrasive particles, or hydrogen peroxide on the color of aged microhybrid composite

Background

This study aimed to assess the effect of different whitening toothpastes containing activated charcoal, abrasive particles or hydrogen peroxide on the color of aged microhybrid composite.

Materials and Methods

In this in vitro, experimental study, 45 composite discs (2 mm × 7 mm) were fabricated of a microhybrid composite. They underwent accelerated artificial aging for 300 h, corresponding to 1 year of clinical service. The composites were then randomly divided into five groups (n = 9). One group served as the control and underwent tooth brushing with distilled water. The remaining four groups underwent tooth brushing with Colgate Total whitening (Gt), Colgate Optic White (Go), Perfect White Black (Gp) and Bencer (Gb) toothpastes in a brushing machine The International Commission on Illumination values (L_m, a_m, b_m) were determined using a spectrophotometer. Color change (ΔE) calculated based on this formula: ΔE_m= ([ΔL_m] ² + [Δa_m] ² + [Δb_m] ²)^½. The differences were defined by ΔE₁ (after aging-baseline),ΔE₂ (after brushing-after aging) and ΔE₃ (after brushing-base line). ΔE₁ were evaluated to ensure that color mismatch had occurred (ΔE1 > 5.5). Difference in (L, a, b) parameters after aging and after tooth brushing in each group, color parameter changes (ΔL_2, Δa₂, Δb_2, ΔL_3, Δa₃, Δb₃) and ΔE₂ and ΔE₃ were analyzed and compared using Wilcoxon test and independent sample median test at P = 0.05 level of significance.

Results

The color parameter changes, ΔE₃ and Δ E₂ were not significantly different among the five groups (P > 0.05). In Gp and Gb charcoal a*, b*, and L* after tooth brushing (P < 0.05). In Colgate Optic group, the a* parameter significantly decreased while the L* parameter significantly increased (P < 0.05).

Conclusion

The results showed that there is no significant difference in the color change of Spectrum composite following tooth brushing with different whitening toothpastes for two weeks. It should be noted that Δ E₃ reached to <3.3 only in charcoal whitening toothpastes.

Comparison the effect of charcoal-containing, hydrogen peroxide-containing, and abrasive whitening toothpastes on color stability of a resin composite; an in vitro study

Background

This study aimed to compare the effects of charcoal-containing, hydrogen peroxide-containing, and abrasive whitening toothpastes on color stability of a resin composite.

Methods

Forty-five specimens were fabricated of spectrum TPH3 composite resin and stored in artificial saliva for 24 h. Baseline color assessment was performed using a spectrophotometer device. Then, the specimens were randomly assigned into 5 experimental groups, namely distilled water (GC), Bencer (GB), colgate optic white (GO), perfect white black (GP) and colgate total whitening (GT) toothpastes. The specimens immersed in coffee solution for 10 min and brushed for 1 min with respective toothpaste and then stored in artificial saliva until the next day. This cycle was repeated for 30 days. After 30 days, the final color assessment was performed using the spectrophotometer. Data were analyzed using one-way ANOVA and Tukey tests.

Results

Experimental groups were not significantly different in terms of Δa and ΔE values. However, ΔL and Δb values showed significant difference among the groups. Regarding Δa, GT and GC groups showed red color shift while the other groups showed green color shift. Regarding Δb, all groups showed blue color shift except GT group which showed yellow color shift.

Conclusion

None of the whitening toothpastes could decrease discoloration caused by the coffee solution to the level below the perceptibility threshold except Colgate Optic White which reduced discoloration within the clinically acceptable perceptibility range.

Cytotoxic Effect of Addition of Different Concentrations of Nanohydroxyapatite to Resin Modified and Conventional Glass Ionomer Cements on L929 Murine Fibroblasts

Objectives: In this study we assessed the cytotoxic effect of nanohydroxyapatite (NHA) incorporated into resin modified and conventional glass ionomer cements (RMGICs and CGICs) on L929 murine fibroblasts.

Materials and Methods: In this in vitro study, 0wt%, 1wt%, 2wt%, 5wt%, 7wt% and 10wt% concentrations of NHA were added to Fuji II LC RMGIC and Fuji IX CGIC powders. Eighteen samples (5×3mm) were fabricated from each type of glass ionomer, in six experimental groups (n=3): CG₀, CG₁, CG₂, CG₅, CG₇, CG_10, RMG_0, RMG₁, RMG₂, RMG₅, RMG₇, and RMG₁₀. Samples were incubated for 72h. The overlaying solution was removed and added to L929 fibroblasts. The methyl thiazolyl tetrazolium bromide (MTT) assay was performed at 24, 48 and 72h. The wavelength was read by a spectrophotometer. Data were analyzed by ANOVA and Tukey’s test.

Results: There was no significant difference in cytotoxicity of the two types of glass ionomers, with and without NHA, except for CG₀ and RMG₀ groups after 72h. RMG₀ group was significantly more cytotoxic than the CG₀ group (P<0.05). In CG groups during the first 24h, the cytotoxicity of CG₅ and CG₇ groups was significantly higher than that of CG₁; while, there was no significant difference between the RMG groups. Cytotoxicity significantly decreased in all groups after 24h (P<0.05).

Conclusion: Incorporation of NHA into Fuji II LC RMGIC and Fuji IX CGIC did not affect their biocompatibility and therefore its addition to these materials can provide favorable biological properties, especially considering its beneficial effects on the other properties of GICs.

Evaluation of Compressive Strength of Several Pulp Capping Materials

Statement of the Problem

Adequate compressive strength is an important characteristic for an ideal liner.

Purpose

This study aimed to assess the compressive strength of several commonly used liners.

Materials and Method

This in vitro, experimental study evaluated 120 samples fabricated of Dycal, Calcimol LC, Vitrebond, Activa Bioactive, and TheraCal LC (n=24) liners according to the manufacturers' instructions. The samples were fabricated using a cylindrical stainless steel mold with 6±0.1 mm height and 4±0.1 mm internal diameter. Half of the samples in each group (n=12) underwent compressive strength test immediately after completion of their primary setting while the other half (n=12) underwent compressive strength test after 24 h. During this period, the samples were immersed in deionized water (grade 3) and incubated at 37±1°C and 100% humidity for 24 h. The compressive strength was measured using a universal testing machine. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test.

Results

The compressive strength of the five liners was significantly different (p&lt; 0.05). Calcimol LC showed maximum compressive strength both immediately after setting and after 24 h. The compressive strength at 24 h was significantly higher than the primary compressive strength in all groups (p&lt; 0.05).

Conclusion

Within the limitations of this study, it seems that Calcimol LC, Activa Bioactive Liner, and TheraCal LC have adequate compressive strength and can be used alone to provide adequate support for the restorative materials.

Effect of fluoride varnish on glass ionomer microhardness changes in endogenous acid erosion challenge

OBJECTIVE

This study aimed to assess the effect of fluoride varnish on glass ionomer microhardness changes after endogenous acid erosion challenge.

METHODOLOGY

In this study, 40 conventional glass ionomer (CGI; Fuji IX) and 40 resin-modified glass ionomer (RMGI; Fuji IILC) discs were fabricated and divided into 4 subgroups (n = 10) for immersion in synthetic gastric acid or saliva for 27 h with/without fluoride varnish application. The surface microhardness was measured at baseline and after immersion, and the change in microhardness was calculated. Data were analyzed using analysis of variance and T-test.

RESULTS

A reduction in microhardness was noted in all subgroups following immersion. The lowest change in microhardness of both CGI and RMGI occurred in artificial saliva. In CGI groups, the highest reduction in microhardness occurred in synthetic gastric acid with fluoride varnish application, and the reduction was significantly different from that of the CGI group with fluoride varnish application (p value = .01). In RMGI groups, the highest reduction in microhardness was noted in synthetic gastric acid without fluoride varnish application, and the reduction was significantly different from that of the other groups (p value < .05).

CONCLUSIONS

Exposure to synthetic gastric acid caused a significant reduction in microhardness of RMGI. Varnish application significantly decreased the acid susceptibility of RMGI, but not that of CGI.

Degree of conversion and water sorption of self-adhesive and conventional flowable composites

Aim: Self-adhesive flowable composite resins have been recently introduced to the market. Degree of conversion (DC) and water sorption (WS) are two important parameters affecting the properties of restorative materials. This study aimed to assess the DC and WS of a self-adhesive flowable composite resin in comparison with two conventional flowable composite resins. Methods: Vertise Flow (VF) self-adhesive and Tetric-N Flow (TF) and Grandio Flow (GF) conventional flowable composites were evaluated in this in vitro, experimental study. The DC (n=3) was determined by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The WS (n=7) was measured after 7 days of immersion in artificial saliva according to ISO 4049 specifications. Data were analyzed by one-way ANOVA and a post-hoc test (p<0.05). Results: VF showed the highest DC percentage (84.3%) followed by GF (72.79%) and TF (68.7%). The latter two had no significant difference (p=0.8). WS was the highest in VF (55.2 μg/mm3), and the two conventional flowable composites had a significant difference in WS (19.5 μg/mm3 in TF and 11 μg/mm3 in GF; p<0.001). Conclusions: Flowable composite resins had significant differences in DC and WS, and VF demonstrated the highest DC and WS.

Direct Pulp Capping With ProRoot MTA Alone and in Combination With Er:YAG Laser Irradiation: A Clinical Trial

Background: Due to the complications of root canal treatment, conservative modalities to preserve pulp vitality are favorable. Direct pulp capping (DPC) refers to the coverage of the pulp tissue exposed by a biocompatible agent that can improve the prognosis of the tooth by 44% to 95%. Some recent studies have reported more predictable results (a success rate of about 90%) for DPC with laser and regenerative materials such as mineral trioxide aggregate (MTA). This study aimed to clinically compare DPC with ProRoot MTA alone and in combination with Er:YAG (erbium-doped yttrium aluminium garnet) laser irradiation (2940 nm). Methods: This clinical trial was conducted on 26 patients with a mean age of 29 years (in the range of 17 to 46 years) who required DPC following pulp exposure during deep caries removal. The teeth were divided into two groups. In the control group, the teeth underwent DPC with ProRoot MTA while in the test group, the teeth were first irradiated with a 2940 nm Er:YAG laser and then underwent DPC with ProRoot MTA. The patients were recalled at one, 3 and 6 months for the follow-up (clinical and radiographic examinations). The data were analyzed using Fisher exact test. Results: The success rate was 75% in the laser group and 93% in the control group. The groups were not significantly different (P>0.05). Conclusion: No significant difference was found in terms of the success rate of DPC with ProRoot MTA alone and in combination with Er:YAG laser irradiation.

In vitro antibacterial activity and durability of a nano-curcumin-containing pulp capping agent combined with antimicrobial photodynamic therapy

BACKGROUND

Considering the antibacterial properties of nano-curcumin (nCur) reinforced with antimicrobial photodynamic therapy (aPDT), this study aimed to assess the antibacterial activity and durability of Activa BioActive Base/Liner (ABBL) containing nCur (nCur-ABBL) as a pulp capping agent against Streptococcus mutans, the most common cause of secondary caries.

MATERIALS AND METHODS

In this in vitro experimental study, ABBL discs containing 0.5 %, 1%, 2%, and 5% (w/w) concentrations of nCur were fabricated. After aPDT using light emitting diode (LED) at 435 ± 20 nm wavelength for 5 min, the discs were undergone aging in artificial saliva for 90 days. The antibacterial activity of the discs against S. mutans was evaluated by the disc agar diffusion test, and the number of bacterial colonies present in the biofilm formed on the disc surfaces was counted after 0, 15, 30, and 60 days of aging.

RESULTS

The maximum growth inhibition zone was noted around the 5% nCur-ABBL discs. Increasing the concentration of nCur from 0.5 % to 5% combined with aPDT significantly decreased the number of S. mutans colonies in the biofilm over time (P < 0.05). nCur-ABBL discs containing 2% and 5% nCur had no difference in antibacterial activity at any time point up to 60 days (P > 0.05).

CONCLUSION

According to our data, 5% nCur-ABBL revealed the largest growth inhibition zone in S. mutans culture. Moreover, 5% nCur can serve as an excellent ABBL additive in aPDT producer against S. mutans biofilms up to 60 days of aging period.

Effect of Three Wavelengths of Diode Laser on the Efficacy of Bleaching of Stained Teeth

Objectives:

Light irradiation and heat have been used to accelerate the process of tooth bleaching. This study aimed to assess the efficacy of conventional bleaching compared to laser-bleaching using three different wavelengths of diode lasers.

Materials and Methods:

In this in-vitro experimental study, 40 extracted human central incisors were immersed in a coloring solution made of tea, coffee, and cola for 21 days. The L*, a*, and b* color parameters were measured before and after the immersion using spectrophotometry. The teeth were then randomly divided into four groups (n=10) as follows: group 1: 810-nm diode laser + Biolase Laser White 20, group 2: 940-nm diode laser + Biolase Laser White 20, group 3: 980-nm diode laser + Biolase Laser White 20, and group 4: conventional bleaching with Opalescence Boost without laser irradiation. One-way analysis of variance (ANOVA) was used to assess the effect of laser type and bleaching technique on color parameters.

Results:

The 940-nm (ΔE=28.5896) and 810-nm laser groups (ΔE=21.2382) showed the highest and the lowest bleaching efficacy, respectively; however, the groups were not significantly different in terms of bleaching efficacy (P>0.05).

Conclusion:

Laser-bleaching with 810-, 940- and 980-nm wavelengths of diode laser has an efficacy similar to that of conventional bleaching but in a shorter period. No difference was noted between different laser wavelengths in terms of bleaching efficacy.

Degree of Conversion of Resin-Modified Glass Ionomer Cement Containing Hydroxyapatite Nanoparticles

Objectives

Hydroxyapatite (HA) nanoparticles are used to improve the physical and mechanical properties of glass ionomers (GIs). This study aimed to assess the effect of addition of different weight percentages of nano-HA on degree of conversion (DC) of Fuji II LC GI cement using a spectrometer.

Materials and Methods

In this in vitro experimental study, 30 samples were fabricated of Fuji II LC (improved) GI cement in six groups (n=5) containing 0%, 1%, 2%, 5%, 7% and 10wt% nano-HA. The obtained paste in each group was subjected to Fourier-transform infrared spectroscopy (FTIR) before curing to assess the monomer to polymer DC percentage. The paste was then light-cured and underwent FTIR again. One-way ANOVA was applied to compare the DC percentage of different groups. Pairwise comparisons were performed using the Tukey's test.

Results

The DC was 57.88±0.57% in 0%, 60.04±0.63% in 1%, 66.92±0.54% in 2%, 65.5±0.71% in 5%, 51.49±0.24% in 7% and 50.09±0.32% in 10% nano-HA group. The difference in DC among the groups was statistically significant (P<0.0001). The highest DC was noted in 2% nano-HA and the lowest DC was found in 10% nano-HA group. Pairwise comparisons revealed significant differences between the groups in DC (P<0.0001).

Conclusion

Increasing the weight percentage of nano-HA to 2% increased the DC but increasing the nano-HA weight percentage over 5% decreased the DC of resin-modified glass ionomer cement (RMGIC). The highest DC was noted in 5w% and 2w% nano-HA groups. Thus, 5w% and 2w% nano-HA can be used to improve the DC of RMGIC.

Efficacy of cavity liners with/without atmospheric cold helium plasma jet for dentin remineralization

Aim: This study aimed to assess the efficacy of cavity liners with/without the atmospheric cold plasma jet (ACPJ) for dentin remineralization.

Color Stability of Ceramic Veneers Cemented with Self-Adhesive Cements after Accelerated Aging

Objectives:

Color change of cements over time can be detected through translucent ceramic veneers, compromising the aesthetic appearance of restorations in the long-term. This study aimed to assess the color stability of ceramic laminate veneers cemented with self-adhesive resin cements after accelerated aging.

Materials and Methods:

In this study, 21 IPS e.max ceramic discs, measuring 8mm in diameter and 0.7 mm in thickness, were fabricated and divided into three groups (n=7) for the application of Choice 2 total-etch light-cure resin cement, RelyX U200 dual-cure self-adhesive resin cement, and SpeedCEM self-cure self-adhesive resin cement. The ceramic discs in each group were cemented on the prepared facial surface of bovine teeth. The color parameters were assessed using a spectrophotometer. Subsequently, the samples were subjected to accelerated aging for 100 hours, and the color parameters were measured again. The data were analyzed using two-way repeated-measures analysis of variance (ANOVA) and Tamhane’s post-hoc test (P<0.05).

Results:

Aging significantly affected the ceramic laminate color parameters in all three groups (P<0.05). SpeedCEM cement showed the lowest color stability (ΔE=4.2) after aging, and its color change was clinically unacceptable (ΔE>3.5). The color change of the other two groups was clinically acceptable (1<ΔE<3.5).

Conclusion:

The self-adhesive dual-cure cement showed color stability comparable to that of the total-etch light-cure cement for cementation of IPS e.max ceramic laminates. The color stability of both cements was superior to that of the self-adhesive self-cure cement.

Hydrogen peroxide penetration into the pulp chamber during conventional in-office bleaching and diode laser-assisted bleaching with three different wavelengths

BACKGROUND AND AIMS

Penetration of hydrogen peroxide into the pulp chamber and subsequent tooth hypersensitivity is a common concern in dental bleaching. The aim of this study was to assess the penetration of hydrogen peroxide (H2O2) into the pulp chamber in diode-laser activated bleaching with different laser wavelengths.

MATERIALS AND METHODS

Fifty extracted human maxillary anterior teeth were collected and divided into five groups(n = 10). Group 1: conventional in-office bleaching using Opalescence Boost gel. Group 2: Bleaching with Biolase Laser White 20 gel activated by 980 nm diode laser. Group 3: Bleaching with Biolase Laser White 20 gel activated by 810 nm diode laser. Group 4: Bleaching with Biolase Laser White 20 gel activated by 940 nm diode laser. Group 5: No bleaching control group.After bleaching, the solution into the pulp chamber was collected and analyzed using a spectrophotometer. The recorded data were compared with a standard sample and the results were analyzed and compared using one-way ANOVA and Tukey's HSD tests.

RESULTS

In all bleached groups, H2O2 had infiltrated into the pulp chamber. The highest level of penetration was noted in group 2 (2.32 ± 0.25 µg), while the lowest level was noted in group 3 (1.85 ± 0.33 µg). The difference in this regard was significant between groups 2 and 3 (P = 0.024), but the differences between other groups were not statistically significant (P ≥ 0.42).

CONCLUSION

Considering the results of this study, it can be stated that hydroge peroxide penetration in to pulp chamber in diode laser activation of bleaching agent according to manufactures instruction is not higher than in-office bleaching. The wavelength of diode laser had significant effect on penetration of hydrogen peroxide into pulp chamber.

Evaluation of the Final Color of Ceramic Veneers with Different Self-Adhesive Resin Cements

Background:

Proper selection of cement plays an effective role in the success of ceramic laminate veneers. The cement can affect the final color by changing the optical properties of the ceramic.

Objective:

Due to the ease of clinical use of the seventh generation of cement (Self-Adhesive Cement), this study aimed to evaluate the effect of this type of cement on the final color of Ceramic Veneers (CV).

Methods:

In this study, 21 IPS e.max ceramic disks (8mm× 0.7 mm) were used. They were divided into 3 groups of 7, depending on the type of cement. (Choice 2, RelyX U200, Speed Cem). In the first stage, ceramic disks were set on the facial surface of bovine’s teeth by bonding agents and the color properties were analyzed by spectrophotometer. In the next stage, specimens were cemented on the prepared surfaces according to the manufacturer’s instructions and their color was evaluated subsequently.

Results:

Results were analyzed by repeated measures two-way ANOVA and TAMHANE post hoc methods (P < 0.05). Results showed that cement influences the color of the ceramic laminate. ∆E values were reported to be higher than the critical point after cementation (∆E > 2.69).

Conclusion:

There was no significant difference between the effects of three cement types on the final color of the ceramic veneers.

In Vitro Effect of Bleaching With 810 nm and 980 nm Diode Laser on Microhardness of Self-cure and Light-Cure Glass Ionomer Cements

Introduction: This study sought to assess the effect of bleaching combined with irradiation of 810 nm and 980 nm diode laser on microhardness of 2 commonly used self-cure and light-cure glass ionomer cements (GICs) in comparison with conventional bleaching (without laser). Methods: In this in vitro, experimental study, 60 samples were fabricated of A2 shade of Fuji IX and Fuji II LC GICs (n=30) and each group was divided into 3 subgroups (n=10). The first subgroups were subjected to bleaching with Opalescence Xtra Boost plus 980 nm diode laser irradiation. The second subgroups were subjected to bleaching with Opalescence Boost plus 810 nm diode laser irradiation and the third subgroups were subjected to bleaching with Opalescence Xtra Boost without laser. Microhardness was measured at baseline and after the intervention using Vickers hardness tester. The data were analyzed using two-way analysis of variance (ANOVA) (P<0.05). Results: Microhardness decreased in all subgroups after the intervention (P<0.001) irrespective of the type of GIC (P=0.201) or surface treatment (P=0.570). The baseline microhardness of the three subgroups within each group of GIC was not significantly different (P=0.456), but the baseline microhardness of conventional GIC was significantly higher than that of resin modified GIC (P=0.004). Conclusion: Bleaching with/without laser irradiation decreases the microhardness of GICs. The baseline microhardness of conventional GIC is higher than that of resin modified GIC.

Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite

BACKGROUND AND AIMS

Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite.

MATERIALS AND METHODS

32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD.

RESULTS

The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups.

CONCLUSION

Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

Effect of Intracanal Post Space Treatments on Push-Out Bond Strength of Fiber Posts to Root Dentin

OBJECTIVES

The main disadvantage of fiber posts is their low bond strength to root canal wall. The aim of the present study was to assess the effect of different root canal post space treatments on push-out bond strength of fiber posts to root canal dentin.

MATERIALS AND METHODS

After post space preparation in 40 endodontically treated human premolars, the teeth were randomly divided into four experimental groups: Group 1: control group, group 2: Endsolv R, group 3: ultrasonic cleaning, group 4: Clearfil Repair. Afterwards, the posts were bonded with Panavia F 2.0 bonding cement. The bond strength of fiber posts to root canal wall in the middle part of canal was evaluated following thermocycling using push-out test. Data were analyzed using one-way ANOVA and Tamhane's multiple comparisons test. The failure mode of each group was determined under a stereomicroscope.

RESULTS

There was a significant difference in the mean push-out bond strength among the groups (P<0.05). The lowest bond strength was noted in the control group. The control group had significant differences with ultrasonic and Clearfil Repair groups (P<0.05). The bond strength of Endsolv R group increased; however, it was not significant (P>0.05).

CONCLUSIONS

It seems that ultrasonic cleaning and Clearfil Repair can modify the root canal wall and significantly increase the bond strength of fiber posts.

Shear Bond Strength of Two Types of Glass Ionomer to Bleached Dentin: Effect of Delayed Bonding and Antioxidant Agent

BACKGROUND

Studies have shown a reduction in bond strength of composites and glass ionomer to bleached enamel and dentin. Several methods have been proposed to reverse compromised bond strength.

OBJECTIVE

The aim of this study was to evaluate the effect of delayed bonding and application of antioxidant agent on the bond strength of reinforced self-cured (Fuji IX) and light-cured glass ionomers (Fuji II LC) to bleached dentin.

MATERIAL

Eighty extracted third molars were randomly divided into 8 groups. Buccal dentin surfaces received different treatments: Two control groups: no treatment + bonding Fuji IX or Fuji II LC. Two immediate bonding groups: bleaching + bonding Fuji IX or Fuji II LC. Two delayed bonding groups: bleaching + 7 days delay + bonding Fuji IX or Fuji II LC. Two sodium ascorbate application groups: Bleaching + application of 10% sodium ascorbate + bonding Fuji IX or Fuji II LC. All samples were tested for shear bond strength. Two-way analysis of variance (ANOVA) was used to compare the mean and standard deviations among groups, followed by the Tukey's test for significant interaction.

RESULTS

No statistically significant difference was detected in shear bond strength of Fuji IX to bleached or normal dentin. Although a significant reduction was found shear bond strength values of Fuji II LC to bleached dentin, no significant difference was observed between no bleaching group and those treated with 10% sodium ascorbate or 7 days of delay in bonding for both types of glass ionomer.

CONCLUSION

Bleaching had no significant effect on shear bond strength of Fuji IX to dentin; this type of GI can be used immediately after bleaching.

Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

INTRODUCTION

The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM).

METHODS

Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM.

RESULTS

The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets.

Comparison of Dentin Permeability After Tooth Cavity Preparation with Diamond Bur and Er:YAG Laser

OBJECTIVES

The aim of this study was to compare the permeability of dentin after using diamond bur and Er:YAG laser.

MATERIALS AND METHODS

Seventy-two recently extracted, intact, and restoration-free human permanent molars were used in this study. The samples were randomly divided into three groups of 24 each and class I cavities were prepared as follows. Group 1: High speed diamond bur with air and water spray. Group 2: Er:YAG laser. Group 3: Er:YAG laser followed by additional sub-ablative laser treatment. Each group consisted of two subgroups with different cavity depths of 2mm and 4mm. The entire cavity floor was in dentin. Two samples from each subgroup were observed under scanning electron microscope (SEM). The external surfaces of other samples were covered with nail varnish (except the prepared cavity) and immersed in 0.5% methylene blue solution for 48 hours. After irrigation of samples with water, they were sectioned in bucco-lingual direction. Then, the samples were evaluated under a stereomicroscope at ×160 magnification. The data were analyzed using two-way ANOVA and Tukey's HSD test.

RESULTS

Two-way ANOVA showed significant difference in permeability between groups 2 and 3 (laser groups with and without further treatment) and group 1 (bur group). The highest permeability was seen in the group 1. There was no significant difference in dentin permeability between groups 2 and 3 and no significant difference was observed between different depths (2mm and 4mm).

CONCLUSION

Cavities prepared by laser have less dentin permeability than cavities prepared by diamond bur.

Effect of Air Abrasion and Erbium-Doped Yttrium Aluminum Garnet (Er: YAG) laser preparation on Shear Bond Strength of Composite to Dentin

INTRODUCTION

The aim of this study was to assess shear bond strength of composite to dentin after air abrasion and laser treatment.

METHODS

40 human extracted molars divided into 4 groups (n=10) received the following treatments. Group 1: carbide bur, Group 2: air abrasion with aluminum oxide 50 μm, Group 3: irradiated with Erbium-Doped Yttrium Aluminum Garnet (Er: YAG) laser (150 mJ/20Hz), Group 4: irradiated with Er:YAG laser (150 mJ/20Hz)+ air. Specimens in all groups were chemically etched with phosphoric acid 37% and treated with bonding agent (single bond 3M). Then, composite build-up was performed by tygon tube. After storage in distilled water at 37°c for one week, all specimens were subjected to a shear bond strength test with universal testing machine. Data were analyzed with ANOVA and T-Test.

RESULTS

The mean and standard deviation of shear bond strength of the 4 groups were 20.8±6.76, 14.98±3.98, 11.43±4.36 and 14.95± 3.18 MPa, respectively.

CONCLUSION

Air abrasion after laser treatment improved the shear bond strength.