Influence of extended light exposure time on the degree of conversion and plasticization of materials used as pit and fissure sealants

Influence of incorporation of nanostructured silver vanadate decorated with silver nanoparticles on roughness, microhardness, and color change of pit and fissure sealants

Objective

The aim of this study was to evaluate the roughness, hardness, and color change of pit and fissure sealants of two commercial brands (Fluroshield ™ and Ultraseal XT ™) incorporated with nanostructured silver vanadate nanomaterial decorated with silver nanoparticles (β-AgVO3) in concentrations (0% - control, 2.5% and 5%).

Material and methods

Two commercial brands Fluroshield TM and Ultraseal XT ™ were used to make the samples with dimensions of 6 × 6 × 4 mm. The control group was made according to the manufacturer's instructions and in the groups with the addition of β-AgVO3, the nanomaterial was added proportionally by mass at percentages of 2.5% and 5%. Roughness properties were evaluated using a 3D Laser Confocal Microscope (n = 10), Knoop microhardness by Microdurometer (n = 10), and color change by Portable Color Spectrophotometer on the CIEDE2000 system (n = 10). Data were evaluated by one-way ANOVA with Bonferroni adjustment and Tukey's mean comparison test at a 5% significance level.

Results

Ultraseal XT ™ sealant roughness showed a significant difference between concentrations with the highest mean for the 5% group (P = 0.010). Regarding the hardness, both sealants showed no significant difference between the groups. Fluroshield ™ sealant showed a significant difference in ΔE00 between the control-2.5% 24.93 (3.49) and control-5% 28.41 (2.58).

Conclusion

It may be concluded that the incorporation of β-AgVO3 influenced the increase in roughness for Ultraseal XT ™ pit and fissure sealant, did not interfere with the microhardness of both sealants, and promoted a change in the color of Fluroshield ™ sealant within clinically acceptable limits.

Marginal and internal analysis of preheated dental fissure-sealing materials using optical coherence tomography

OBJECTIVES

This study aimed to evaluate the influence of pre-photoactivation temperature on the marginal and internal integrity (occurrence of voids) of fissure-sealing materials on occlusal fissures using optical coherence tomography (OCT).

METHODS

Occlusal fissures of 40 human third molars were sealed using a resin-based fissure sealant (Fluroshield) and a flowable composite (Permaflo) photoactivated at 68 °C (preheated) or at room temperature (25 °C) (n=10). After sealing, the teeth were subjected to thermocycling (500 cycles, 5-55 °C) and 14 days of pH cycling (demineralisation for 6 hours/day and remineralisation for 18 hours/day). The occlusal surfaces were scanned in a buccolingual direction, and 20 tomographic images parallel to the long axis of each tooth were obtained. Images presenting marginal gaps and internal voids were counted and statistically analysed using analysis of variance and Tukey's test (P<0.05).

RESULTS

There were statistically significant differences between materials and temperatures (P<0.01). The flowable composite had a lower percentage of gaps and internal voids than the resin-based sealant. Preheated materials had a lower percentage of gaps and internal voids than the materials at room temperature.

CONCLUSION

Therefore, preheated flowable composite provided the best marginal sealing of fissures, and internal homogeneity of the material.

Influence of extended light exposure curing times on the degree of conversion of resin-based pit and fissure sealant materials

PURPOSE

The aim of present study was to evaluate extended curing times on the degree of conversion (DC) of filled and unfilled resin-based materials used as pit and fissure sealants.

MATERIALS AND METHODS

The materials examined were a flowable composite (Filtek™ Z350 XT Flowable) and a pit and fissure sealant (Clinpro™ Sealant). Thirty disks of each material were prepared. The 30 made of the flowable composite were divided into three groups (n = 10 each) according to the three different curing times studied: 20 s (group 1), 40 s (group 2), and 60 s (group 3). Similarly, the 30 disks made of the pit and fissure sealant were divided into three groups (n = 10 each) according to the three different curing times: 20 s (group 4), 40 s (group 5), and 60 s (group 6). After polymerization, the disks were removed from the mold and stored in dry, lightproof containers in an incubator at 37 °C for 24 h. The DC was obtained using an Avatar 320 FTIR spectrometer. Then the data were analyzed using the Kruskal-Wallis test and the Fisher's least significant difference post hoc test for multiple comparisons (alpha = 0.05).

RESULTS

DC values for the flowable composite (Filtek™ Z350 XT) were higher (p = 0.002) than those for the pit and fissure sealant (Clinpro™ Sealant). Group 2 and group 5 showed significantly higher DC values than group 1 and group 4, respectively. There was no difference between groups 2 and 3 or between groups 5 and 6 (p = 2.93).

CONCLUSION

An extended curing time improves the DC to some extent for both materials.

Systematic review of noninvasive treatments to arrest dentin non-cavitated caries lesions

AIM: To systematically review the literature on the efficacy of noninvasive methods of arresting the progression of non-cavitated occlusal carious lesions in dentin.

METHODS: The Medline/PubMed, LILACS, SciELO and Scopus databases were searched to identify relevant publications through to November 2013. Only clinical trials evaluating the ability of noninvasive methods to arrest the progression of occlusal non-cavitated carious lesions in dentin were included. Screening, data extraction and quality assessment were conducted independently and in duplicate.

RESULTS: Of 167 citations identified, nine full text articles were screened and five were included in the analysis. All papers reported on occlusal fissure sealing using a self-curing glass ionomer (n = 1) or resin-based (n = 4) sealant. Only the use of resin-based sealant to obliterate occlusal fissures arrested the progression of non-cavitated occlusal carious lesions in dentin.

CONCLUSION: Occlusal fissure sealing with a resin-based sealant may arrest the progression of non-cavitated occlusal dentinal caries. Further clinical trials with longer follow-up times should be performed to increase scientific evidence.

Influence of the curing mode on the degree of conversion of a dual-cured self-adhesive resin luting cement beneath ceramic

OBJECTIVE

To evaluate the effect of the delayed photoactivation and ceramic barrier on the degree of conversion (DC) of self-adhesive resin cement.

MATERIALS AND METHODS

Circular specimens (5 mm in diameter × 1 mm in thickness) of the RelyX U-100 resin cement were made using the following curing protocols (n = 10): (G1) 40 s beneath a IPS Empress II ceramic; (G2) 40 s of direct photocuring; (G3) 80 s beneath the ceramic; (G4) 80 s of direct photocuring; (G5) self-curing; (G6) 5 min in the absence of light (self-curing) followed by transceramic photocuring for 40 s; (G7) 5 min in the absence of light (self-curing) followed by transceramic photocuring for 80 s. All the specimens were photoactivated by LED (800 mW/cm(2)). After 24 h of dry storage, the DC was measured by FTIR, on the top surface of the specimens. Data were submitted to one-way ANOVA and Tukey test (p ≤ 0.05).

RESULTS

Direct photocuring with no ceramic interposition, regardless of the curing time (40 s and 80 s) promoted the highest conversion mean (56.79 ± 1.19 and 59.98 ± 2.93, respectively) and the 5 min delay time for the transceramic photocuring presented a similar mean compared to the immediate transceramic photocuring. The DC was influenced by the ceramic barrier, decreasing the conversion values (49.72 ± 1.91 for 40 s and 52.36 ± 2.50 for 80 s), with no statistical difference from the groups with the previous 5 min of photoactivation delay. The self-cure only showed the worst DC values.

CONCLUSION

Direct photocuring provided a higher degree of conversion for the self-adhesive resin cement. The delayed light activation did not influence the degree of conversion for the resin cement tested.

Filler morphology of resin-based low-viscosity materials and surface properties after several photoactivation times

AIM

This study aimed to characterize the morphology of filler particles and to analyze the effect of shortened and extended photoactivation times on hardness (VHN) and cross-link density (CLD) of resin-based low-viscosity materials.

METHODS

Sixteen commercially available materials were tested: four fissure sealants (Alpha Seal, Fluroshield Yellowed, Bioseal and Fluroshield White) and 12 flowable composites (Opallis T, Permaflo T, Opallis A2, Natural Flow A2, Master Flow A2, Permaflo A2, Filtek Z350 A2, Natural Flow O, Master Flow OA2, Opallis OA3.5, Filtek Z350 OA3, Opallis OP) at six curing times (10 s, 20 s, 30 s, 40 s, 50 s and 60 s). Specimens were fabricated (n = 5), analyzed by Scanning Electron Microscopy, by VHN and by CLD.

RESULTS

Unimodal and multimodal filler particles sizes with spherical and irregular shapes were observed. Unfilled materials were also detected. There were no differences among curing times for either VHN or CLD. Opallis A2 and Opallis OA3.5 showed the highest VHN at all curing times, whereas Master Flow A2 and Master Flow OA2 presented the lowest VHN. Opallis A2 presented the highest CLD at all curing times and Alpha Seal showed the lowest CLD.

CONCLUSIONS

Filler particle morphology differed among the resin-based low-viscosity materials tested. The shortest photoactivation time tested could yield similar VHN and CLD means to those provided by the most extended photoactivation time.

Arrest of non-cavitated dentinal occlusal caries by sealing pits and fissures: a 36-month, randomised controlled clinical trial

OBJECTIVE

This study aimed to evaluate the progression of sealed non-cavitated dentinal occlusal caries in a randomised controlled clinical trial.

MATERIALS AND METHODS

Sixty teeth with non-cavitated dentinal occlusal caries were selected in patients with a high risk for caries. Patients were randomly divided into two groups so that each group included 30 teeth. Patients in the experiment group were given oral hygiene instructions and a fissure sealant. Patients in the control group were given oral hygiene instructions only. Caries progression and sealant loss were monitored over a period of 36 months by clinical and radiographic examinations.

RESULTS

Clinical and radiographic progression of caries was significantly more frequent in the control group than in the experiment group. Three teeth lost their sealant and showed caries progression, but this was apparent only at the 12-month follow-up. At the 24- and 36-month recall appointments, neither sealant loss nor caries progression were observed.

CONCLUSION

The pit and fissure sealant utilised in this study was shown to be effective in arresting carious lesions at 36 months.

Effect of the application of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste and adhesive systems on bond durability of a fissure sealant

This study aimed to evaluate the effect of the previous application of a casein phosphopeptide-amorphous calcium phosphate paste (MI Paste, MI) and adhesive systems on the bond durability of a fissure sealant. Ninety-eight enamel blocks were obtained from proximal surfaces of erupted third molars. Specimens were divided into 14 groups (n = 7) according to the previous application of MI (with and without) and the adhesive systems used (no adhesive system; hydrophobic resin of a three-step etch-and-rinse adhesive system; etch-and-rinse single-bottle adhesive system; all-in-one adhesive system; two-step self-etching adhesive system; additional phosphoric acid conditioning and all-in-one adhesive system; additional phosphoric acid conditioning and two-step self-etching adhesive system). A fissure sealant (Fluroshield) was applied and photoactivated for 20 s. Beams (~0.7 mm(2)) were prepared for the microtensile bond strength test, which was executed after 24 h or 6 months of water storage. Fractured specimens were analyzed by scanning electronic microscopy. Data were analyzed by two-way ANOVA with repeated measures/Tukey's test (P < 0.05). Groups that received MI application and adhesive systems presented higher means than those groups where MI was not applied. Higher frequency of cohesive failures was observed for groups with MI. Applying a CPP-ACP containing paste on enamel before adhesive systems was an effective method to increase bond durability of the sealant tested.

Effect of irradiation times on the polymerization depth of contemporary fissure sealants with different opacities

The aim of this study was to evaluate the depth of curing of 10 contemporary blue light-activated dental flowable materials at several opacities, influenced by different irradiation times using FT-IR spectroscopy. Fifty-five specimens (n = 5) with a 5-mm diameter and 1-mm thickness of translucent (Opallis Flow T), yellowed (Master Flow A2; Opallis Flow A2; Natural Flow A2; Fluroshield Yellowed), and opaque materials (Master Flow OA2; Natural Flow O; Opallis Flow OA3.5; Opallis Flow OP; Fluroshield White) were obtained at six curing times (10s, 20s, 30s, 40s, 50s, and 60s) using a high-intensity LED (Coltolux, Coltène/Whaledent). The degree of conversion (DC) (%) was obtained using the Nexus 470 FTIR Spectrometer (Nicolet Instruments, USA). The FTIR-ATR spectra for uncured and cured samples were analyzed using a ZnSe crystal. The top and bottom surfaces of the cured specimens were analyzed to obtain the depth of curing. Two-way ANOVA was used to analyze the data. The highest curing depth was obtained by Natural Flow OA2, while the lowest was shown by Master Flow OA2. The shortest curing time generated similar depths of cure in comparison with the most extensive for Opallis Flow A2 and Fluroshield Yellowed. Therefore, depth of curing, influenced by the irradiation time, was dependent on the materials. Using the Natural Flow OA2 opaque sealant and the 10-s curing time for Opallis Flow A2 and Fluroshield Yellowed may represent alternative approaches to sealing tooth fissures.