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1.
J Esthet Restor Dent ; 2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33881792

RESUMO

OBJECTIVES: To evaluate the effect of atmospheric pressure plasma (PLA), sandblasting (SAN), silanization (SIL) and hydrophobic bonding resin (HBR) on the micro-shear bond strength (MSBS) of fresh nanofilled (NF) or microhybrid (MH) composites to water-aged nanofilled composite. MATERIALS AND METHODS: NF plates were fabricated and stored in distilled water for 4 months. The aged plates were assigned to the groups (n = 6): 1- untreated; 2- SAN + SIL + HBR; 3- HBR; 4- PLA + HBR; 5- SAN + HBR; 6- SAN + PLA + HBR; and 7- PLA. Two fresh composite cylinders were constructed on each plate with NF or MH composites and tested after 24 h or 1 year of water-storage, using the MSBS testing. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). RESULTS: NF yielded better outcomes than MH at 24 h, which was not observed at 1 year. HBR showed the highest MSBS results, while untreated and PLA groups yielded the lowest one. MSBS reduced for all groups after 1 year. CONCLUSIONS: Only HBR can obtain good MSBS results, while PLA alone was not beneficial. After 1 year, a reduction in repair MSBS was observed and the type of composite did not influence the results. CLINICAL RELEVANCE: The repair technique can be simplified with the use of only an adhesive and macromechanical retentions in the old composite, regardless the type of fresh composite.

3.
J Adhes Dent ; 23(2): 113-119, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33825425

RESUMO

PURPOSE: To evaluate the influence of different surface treatments of two CAD/CAM glass ceramics on surface topography, shear bond strength of composite cement, flexural strength, and elastic modulus. MATERIALS AND METHODS: Two ceramics were evaluated: lithium-disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) glass ceramics. Glass ceramics were sintered and the surfaces were sandblasted (SBL) or etched with 9% hydrofluoric acid for 10 s (HF10), 20 s (HF20) or 30 s (HF30). The treated surfaces were analyzed using scanning electron microscopy (n = 3) to evaluate the etching pattern. For bond strength testing, ceramic samples were silanized after treatments and an adhesive was applied to the surface. Afterwards, a silicone mold was used to build composite-cement cylinders, which were tested after 24 h or one year of water storage (n = 10). Flexural strength and modulus were assessed using a 3-point bending test (n = 15). The data were subjected to statistical analysis at a pre-set α = 0.05. RESULTS: SBL and HF resulted in different surface topographies. Increased HF etching time influenced the surface dissolution level and exposition of crystals for LDS, while no effect of etching time was observed for ZLS. After one year, the bond strength to LDS significantly decreased, regardless of treatments. For ZLS, HF10 and HF20 showed stable bond strengths over time. SBL yielded the lowest bond strength for both ceramics and statistically significantly reduced the flexural strength of ZLS. The flexural strength and elastic modulus of ceramics were not affected by different etching times. CONCLUSION: Bonding stability depended on the glass ceramic and the pretreatment method employed. HF etching did not change the mechanical properties of the ceramics and is indicated as a ceramic treatment for bonding.


Assuntos
Colagem Dentária , Ácido Fluorídrico , Cerâmica , Porcelana Dentária , Resistência à Flexão , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície
4.
J Esthet Restor Dent ; 2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33675162

RESUMO

BACKGROUND: Bulk-fill materials can facilitate the restorative procedure mainly for deep and wide posterior cavities. The purpose of this study was to evaluate flexural strength (biaxial flexural strength [BFS]) and microhardness (Knoop microhardness [KHN]) at different depths of bulk-fill materials. METHODS: Five bulk-fill materials were tested: two light-curable composite resins, one dual-cure composite, one bioactive restorative, and a high-viscosity glass ionomer. A conventional composite was used as control. BFS and KHN were tested at different depths. Data was analyzed by two- and one-way ANOVAs, respectively and Tukey's post-hoc (α=0.05). RESULTS: The high-viscosity glass ionomer material presented the lowest BFS at all depths. KHN for the two light-curable and the dual-cure bulk-fill resin composites was reduced following an increase in restoration depth, while the conventional composite, the bioactive material, and the high-viscosity glass ionomer were not affected. CONCLUSION: There are differences in the properties of the tested materials at 4 mm depth, showing that the studied properties of some materials vary according to the cavity depth, although the results are material dependent. CLINICAL SIGNIFICANCE: Mechanical properties of light-cured, bulk-fill materials may be affected by inadequate polymerization. Clinicians should consider complementary strategies to achieve adequate polymerization at high-increment depths.

5.
Int J Prosthodont ; 2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33651025

RESUMO

PURPOSE: To determine the effects of tooth brushing on the surface roughness (Sa) and morphology, maximum relative depth (Rv), gloss (GU), and microhardness (MH) of four esthetic restorative materials and enamel. MATERIALS AND METHODS: A light-curing composite resin (Filtek Supreme Ultra [FSU], 3M ESPE), two hybrid resin/ceramic CAD/CAM materials (Lava Ultimate [LAV], 3M ESPE, and VITA Enamic [VEN], VITA Zahnfabrik), and a CAD/CAM feldspathic ceramic (VITA Blocs Mark II [VMA], VITA Zahnfabrik) were evaluated. Bovine enamel (ENA) was used as a control group. All surfaces were polished in accordance with the manufacturer's instructions. Samples were analyzed before and after brushing (30,000 cycles) regarding Sa and Rv using a 3D laser-measuring microscope. GU was evaluated every 10,000 tooth brushing cycles. MH was also measured before and after tooth brushing. The surfaces were observed using scanning electron and laser measuring microscopies to determine the wear patterns. Data were analyzed by paired t test, one-way or two-way repeated measures analysis of variance, and Tukey test (α = .05), depending on the method performed. RESULTS: The Sa increased significantly after brushing for all materials, except for VMA, which showed the opposite effect. ENA and VEN showed higher Rv than VMA. After 30,000 tooth brushing cycles, VMA showed the highest GU, while FSU showed the lowest. Also, little surface topography changes were observed for VMA. MH did not change significantly after 30,000 brushing cycles, except for LAV. CONCLUSION: Brushing caused surface alterations in all tested materials except for feldspathic ceramic. The changes were more evident in resin-based materials.

6.
Int J Prosthodont ; 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33616562

RESUMO

PURPOSE: To evaluate the effectiveness of nonthermal atmospheric plasma (NTAP) and priming on the shear bond strength (SBS) of a resin cement to two zirconia ceramics after 24 hours and 1 year of water storage. MATERIALS AND METHODS: A total of 120 plates (9 x 7 x 2 mm) were obtained from two types of zirconia (Katana, Kuraray Noritake; and ZirCAD, Ivoclar Vivadent) plates randomly divided into 12 groups (n = 10 each). Zirconia ceramic plates were submitted to the following treatments: (1) untreated (control); (2) treated with ZPrime Plus (Bisco Dental) primer; (3) NTAP (Surface Plasma Tool Model SAP, Surface Engineering and Plasma Solution) application for 10 seconds; (4) NTAP for 30 seconds; (5) NTAP for 10 seconds followed by priming; and (6) NTAP for 30 seconds followed by priming. Two silicone molds (2.37-mm diameter x 2-mm height) were positioned on the treated surface of each zirconia plate, and the resin cement (Panavia F 2.0, Kuraray Noritake) was manipulated and inserted into the molds. After light activation, two resin cement cylinders (specimens) were obtained from each plate. One specimen was tested after 24 hours, and the other after 1 year. The shear load was applied to the base of the resin cement cylinders until failure. Data were analyzed using three-way ANOVA and post hoc Tukey test (α = .05). RESULTS: NTAP application alone (groups 3 and 4) increased SBS compared to the control group only at 24 hours. After 1 year, the NTAP/primer combination showed higher SBS than the other groups. Water storage for 1 year reduced the bond strength for all groups. CONCLUSION: NTAP, combined or not combined with primer, had a beneficial effect on adhesion after 24 hours and after 1 year. Water storage negatively influenced the adhesion in all groups.

7.
Dent Mater ; 37(4): e201-e212, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33422299

RESUMO

OBJECTIVES: The aim of this in vitro study was to incorporate two anti-caries agents, Apigenin and tt-Farnesol, to resin composite and resin cement to reduce the virulence of Streptococcus mutans around dental restorations. METHODS: Apigenin (Api, 5 mM) and tt-Farnesol (Far, 5 mM) were added alone, together, and combined with fluoride (F). Biofilm of S. mutans was grown on composite discs, and the dry-weight, bacterial viability, and the polysaccharides (alkali-soluble, intracellular and water-soluble) were quantified. CLSM images of the S. mutans biofilm were obtained after three years of water-storage. The effect of the additions on the physicochemical properties and the composite colorimetric parameters were also analyzed. RESULTS: The additions did not affect bacterial viability. Api alone and combined with Far or combined with Far and F decreased the bacterial dry-weight, alkali-soluble and intracellular polysaccharides. After three years, the composites containing the additions presented a greater EPS matrix on the top of biofilm. Statistical difference was obtained for the degree of conversion; however, the maximum polymerization rate and curing kinetics were unaffected by the additions. No difference was observed for the water-soluble polysaccharides, flexural strength, and elastic modulus. Api increased the yellowness of the composites. SIGNIFICANCE: Api, alone and combined, reduced the expression of virulence of S. mutans without jeopardizing the physicochemical properties of the composites.


Assuntos
Cárie Dentária , Streptococcus mutans , Apigenina/farmacologia , Biofilmes , Cariostáticos , Resinas Compostas , Farneseno Álcool , Humanos , Virulência
9.
J Mech Behav Biomed Mater ; 115: 104288, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33383377

RESUMO

OBJECTIVE: This study evaluated physical and mechanical properties and characterized the filler particles of seven composites. MATERIALS AND METHODS: Filtek Supreme (FS, 3M Oral Care), Forma (FO, Ultradent), Charisma Diamond (CD, Kulzer), Spectra Smart (SS, Dentsply), Filtek Bulk Fill (FB, 3M Oral Care), Tetric N-Ceram Bulk Fill (TB, Ivoclar), and Cention N (Ivoclar) in self- (CNSC) or dual-curing (CNDC) were evaluated. Fillers size, shape, and content were analyzed by scanning electron microscopy (SEM) and X-ray dispersive energy spectroscopy (EDX). Disk-shaped specimens (n = 5) were prepared for sorption (SP) and solubility (SL). Flexural strength and elastic modulus were tested at 24 h and 12 months (n = 10). Degree of conversion (DC%) and maximum rate of polymerization (Rpmax) were evaluated using micro-Raman spectroscopy. SP and SL results were submitted to Kruskal-Wallis one-way ANOVA and Dunn's pairwise test (α = 0.05). Mechanical properties were analyzed by 2-way ANOVA and Tukey's test (α = 0.05). DC% of CNSC and CNDC was compared by independent t-test (α = 0.05). Rpmax results were analyzed by 1-way ANOVA and Tukey's test (α = 0.05). RESULTS: The composites differed regarding filler size, shape, and content. CD and CNSC showed lower SP than FS. SS had lower SL than CNSC and CNDC. CNDC presented higher DC% than CNSC. CD, TB, and CNDC showed the highest Rpmax. TB, CNSC, and CNDC showed the lowest 24-h flexural strengths. Mechanical properties of CD did not decrease, while FO, TB, and CNSC showed a significant reduction after storage. CONCLUSIONS: Monomer composition and fillers characteristics greatly influenced the physico-mechanical properties of the tested composites.

10.
J Dent ; : 103550, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33276081

RESUMO

OBJECTIVES: To evaluate the incorporation of doxycycline (DOX) into a commercial dental adhesive regarding physicochemical properties, microtensile bond strength (µTBS), nanoleakage (NL), nanohardness (NH) and Young's modulus (YM), metalloproteinases (MMP) inhibition, and antibiofilm activity. METHODS: DOX was incorporated into the adhesive at 0.05, 0.1, 0.5, and 1 wt%. Restored teeth were evaluated for µTBS, NL, NH, and YM after 24 -hs and 1-year of water storage. Biofilms of Streptococcus mutans were grown on top of these adhesives and determined for bacterial viability and amount of biomass. The inhibitory effect on MMP was analyzed by in situ zymography under confocal microscopy. RESULTS: Adhesives with 0.5 and 1 wt% of DOX presented reduced pH and degree of conversion. The incorporation of DOX did not affect µTBS and hybrid layer YM. The control group (no DOX) had a decrease in µTBS and the densest silver nitrate areas after 1-year storage. Hybrid layer NH values increased with 0.1 wt% DOX compared to control and 1 wt% DOX groups, at 24 -hs. After 1-year storage, NH of 1 wt% DOX adhesive decreased compared to the control group. The 0.5 and 1 wt% concentrations of DOX decreased the bacterial viability and the biofilm biomass. Confocal images suggest an increased MMP inhibition proportional to the percentage of DOX. CONCLUSION: At any concentration, DOX-doped dental adhesives were able to inhibit MMP activity, diminish nanoleakage, and maintain the resin-dentin bond-strength after 1 year of artificial aging. CLINICAL SIGNIFICANCE: Doxycycline-doped dental adhesive inhibited metalloproteinases activity and preserved interface bond strength. This formulation has a potential to improve adhesive restorations clinical longevity.

11.
Dent Mater ; 2020 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-33229040

RESUMO

OBJECTIVE: To a self-etch adhesive doped with nano-bioglass and evaluate its ability to bond and re-mineralize artificially demineralized dentin. METHODS: Experimental Si, Ca, Na and PO4 based nanobioglass particles were synthesized, doped into experimental self-etch adhesives, and divided into 3 groups: Clearfi SE2 (CSE2), experimental (EXC), and experimental doped with 10% of nanobioglass (ExNB). The adhesives were applied onto the caries-affected dentin (chemically simulated), and evaluated after 24 h and 28 days of immersion in simulated body fluid. The remineralization process was assessed using optical coherence tomography, nanoindentation, in situ zymography, transmission electron microscopy, confocal laser scanning microscopy, µ-tensile bond strength, and pH buffer. RESULTS: The addition of nanobioglass particles into the experimental self-etch adhesives altered the µTBS in the short-term jeopardizing dentin bonding properties, when compared to the non-doped self-etch adhesive. The remineralization recovered the nanohardness, and volume lost by caries lesion (p = 0.02). Moreover, reduced the enzymatic activity (p = 1.24E-4) and formed new crystals within of the hybrid layer. CONCLUSION: The use of nanobioglass was efficient to recover the properties of a caries affected dentin. Furthermore, the adhesive properties were not hampered and the probabilistic reliability increased.

12.
Dent Mater ; 2020 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-33143939

RESUMO

OBJECTIVE: This study evaluated the effect of beam homogeneity on the microtensile bond strength (µTBS) of two adhesive resins to dentin. METHODS: One polywave light-emitting-diode (LED) LCU (Bluephase Style, Ivoclar Vivadent AG) was used with two different light guides: a regular tip (RT, 1010 mW/cm2 emittance) and a homogenizer tip (HT, 946 mW/cm2 emittance). The emission spectra and beam profiles were measured from both light guides. Extracted third molars were prepared for µTBS evaluation using two adhesive systems: Excite F (EXF) and Adhese Universal (ADU). Bond strength was calculated for each specimen (n = 10) at locations that correlated with the output of the two LED chips emitting blue (455 nm) and the one chip that emitted violet light (409 nm) after 24-hs and after one-year water-storage. The µTBS was analyzed using a four-way analysis of variance (factors: adhesive system, light guide, LED wavelength, and storage time) and post-hoc Tukey test (α = 0.05). RESULTS: EXF always delivered a higher µTBS than ADU (p < 0.0001), with the µTBS of ADU being about 20% lower than EXF. The light guide (p = 0.0259) and storage time (p = 0.0009) significantly influenced the µTBS. The LED wavelengths had no influence on the µTBS (p > 0.05). SIGNIFICANCE: Homogeneity of the emitted light beam was associated with higher 24-h µTBS to dentin, regardless of the adhesive tested. Also, differences in the composition of adhesives can affect their compatibility with restorative composites and their ability to maintain bonding over one year.

13.
Dent Mater ; 2020 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-33143940

RESUMO

OBJECTIVE: This study aimed to test the efficacy of photodynamic inactivation (PDI) mediated by curcumin with EDTA against Streptococcus mutans in planktonic suspension using blue LED light. METHODS: Antibacterial activity of curcumin and EDTA was evaluated by determination of their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of various combination ratios of curcumin and EDTA against S. mutans. Cultures of S. mutans (18 h, 37 °C, 5% C02) were prepared to test the effect of curcumin-mediated PDI (50 µM and 500 µM) with or without 0.4% EDTA and 40 s of light-activation with blue light. EDTA and each concentration of curcumin were also tested individually. Chlorhexidine (0.2%), was used as positive control. Planktonic suspensions were also analyzed by viable colony counts (VCC), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and polymerase chain reaction (PCR). RESULTS: The MIC values of curcumin and EDTA were 5 mM and 0.125% respectively. FICI showed a synergistic interaction between curcumin and EDTA. All the combinations with curcumin and blue LED light resulted in a complete inactivation of the S. mutans and CLSM confirms these results, TEM showed morphological changes produced by the PDI. No damage on DNA structure was detected by PCR. SIGNIFICANCE: Curcumin-mediated PDI with EDTA using a blue light, shows a strong inhibitory effect against S. mutans in planktonic culture. Because of the unspecific target mechanism, it could be a promising technique for disinfection of dental tissues.

14.
Clin Oral Investig ; 24(12): 4225-4235, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33083851

RESUMO

OBJECTIVES: To perform a review on the influence of preheating and/or heating of resinous and ionomeric materials on their physical and mechanical properties and to discuss the benefits and methods of preheating/heating that have been used. MATERIAL AND METHODS: A search was performed in the Pubmed, Scopus, Scielo, and gray literature databases. In vitro studies published from 1980 until now were searched using the descriptors "composite resins OR glass ionomer cements OR resin cements OR adhesives AND heating OR preheating." Data extraction and quality of work evaluation were performed by two independent evaluators. RESULTS: At the end of reading the search titles and abstracts, 74 articles were selected. Preheating of composite resins reduces viscosity, facilitates adaptation to cavity preparation walls, increases the degree of conversion, and decreases the polymerization shrinkage. Preheating of resin cements improves strength, adhesion, and degree of conversion. Dental adhesives showed good results such as higher bond strength to dentin. However, unlike resinous materials, ionomeric materials have an increase in viscosity upon heating. CONCLUSIONS: Preheating improves the mechanical and physical properties. However, there is a lack of clinical studies to confirm the advantages of preheating technique. CLINICAL RELEVANCE: Preheating of dental restorative materials is a simple, safe, and successful technique. In order to achieve good results, agility and training are necessary so the material would not lose heat until the restorative procedure. Also, care is necessary to avoid bubbles and formation of gaps, which compromises the best restoration performance.

15.
J Adhes Dent ; 22(4): 421-431, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32666069

RESUMO

PURPOSE: To investigate the effects of 1-year water storage and surface treatments on shear bond strength (SBS) of two composite cements bonded to resin matrix CAD-CAM ceramics (RMCs) and on the mechanical properties of RMCs. MATERIALS AND METHODS: Three types of RMCs were tested: 1. polymer-infiltrated hybrid ceramic (PIHC, Enamic, VITA Zahnfabrik); 2. resin nanoceramic (RNC, Lava Ultimate, 3M Oral Care); and 3. flexible hybrid ceramic (FHC, Cerasmart, GC). One indirect laboratory composite (ILC, Epricord, Kuraray Noritake) was used as control. For each material, 60 plates (14 x 7 x 1 mm) were prepared for the SBS test and submitted to three different surface treatments: following manufacturer's instructions, non-thermal atmospheric plasma application (30 s), and plasma + bonding agent. Two composite cements were tested: RelyX Ultimate (3M Oral Care) and Panavia V5 (Kurarary Noritake). Two resin cylinders (1.5 mm diameter x 1.5 mm height) were bonded to each plate (n = 10), with one tested after 24-h storage in distilled water and the other after 1 year of storage in distilled water. Twenty rectangular bars (12 x 2 x 1 mm) of each indirect material were prepared and submitted to the 3-point flexural test after 24-h or 1-year water storage to determine the elastic modulus (EM) and flexural strength (FS) (n = 10). Fractured samples were also examined with SEM and energy dispersive x-ray spectroscopy (EDS). SBS data were analyzed by four-way ANOVA, and EM and FS data by two-way ANOVA, followed by Tukey's post-hoc test (α = 0.05). RESULTS: Groups treated in accordance with manufacturer's instructions exhibited higher SBS than did plasma and plasma + bonding agent groups for all indirect materials, composite cements, and storage periods tested. In general, RelyX Ultimate displayed higher mean SBS than did Panavia V5, except for some groups of ILC where manufacturer's instructions were followed. After 1-year storage in water, all groups exhibited a significant reduction in SBS, except for some groups that following manufacturer's instructions. ILC showed the lowest values of EM and FS. Among the CAD-CAM materials, FHC exhibited the lowest EM and highest FS means, while PIHC possessed the highest EM and lowest FS means for both storage periods. CONCLUSIONS: In general, following the respective manufacturer's instructions yielded the best bond strength results. For most materials, 1-year water storage decreased bond strength of composite cements to RMCs, as well as their FS, while increasing their EM. Microstructure and composition influenced the mechanical properties studied.


Assuntos
Cerâmica , Colagem Dentária , Desenho Assistido por Computador , Teste de Materiais , Polímeros , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
17.
J Esthet Restor Dent ; 32(5): 521-529, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32598095

RESUMO

OBJECTIVE: To evaluate the effects of human saliva decontamination protocols on bond strength of resin cement to zirconia (Y-PSZ), wettability, and microbial decontamination. MATERIALS AND METHODS: Zirconia plates were sandblasted and divided into (a) not contaminated, (b) contaminated with human saliva and: (c) not cleaned, (d) cleaned with air-water spray, (e) cleaned with 70% ethanol, (f) cleaned with Ivoclean, or (g) cleaned with nonthermal atmospheric plasma (NTAP). The wettability and microbial decontamination of the surfaces were determined after saliva contamination or cleaning. Monobond Plus (Ivoclar Vivadent) was applied after cleaning, followed by Variolink LC (Ivoclar Vivadent). The samples were stored 1 week before shear bond strength (SBS) testing, and data (SBS and wettability) were analyzed by one-way analysis of variance and Tukey test (α = .05). RESULTS: Saliva contamination reduced SBS to zirconia compared to not contaminated. Both Ivoclean and NTAP produced higher SBS compared to not cleaned and were not significantly different from the not contaminated. Ivoclean produced the highest contact angle, and NTAP the lowest. With the exception of using just water-spray, all cleaning protocols decontaminated the specimens. CONCLUSIONS: Both Ivoclean and NTAP overcame the effects of saliva contamination, producing an SBS to zirconia comparable to the positive control. CLINICAL SIGNIFICANCE: Dental ceramics should be cleaned prior to resin cementation to eliminate the effects of human saliva contamination, and Ivoclean and NTAP are considered suitable materials for this purpose.


Assuntos
Colagem Dentária , Cerâmica , Descontaminação , Análise do Estresse Dentário , Humanos , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície , Molhabilidade , Zircônio
18.
Photodiagnosis Photodyn Ther ; 31: 101848, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32492521

RESUMO

AIM: This in vitro study assessed the effects of in-office bleaching with gels (35% hydrogen peroxide [HP] or 37% cabamide peroxide [CP]) and two activation sources (violet radiation [LED] or nonthermal atmospheric plasma [NTAP]) on the mineral content of bovine enamel. MATERIAL AND METHODS: Dental blocks (n = 90) were assessed for initial microhardness before random distribution into nine groups: LED, LED + HP, LED + CP, NTAP, NTAP + HP, NTAP + CP, HP, CP and control (without treatment). Specimens were subjected to bleaching (2 clinical sessions, 7 days apart) using LED [20x/session, 1-min/each, 30 s apart] or NTAP [1x/session, 10 min]. µRaman determined contents of phosphate (PO43) and carbonate (CO32). Micro-energy dispersive X-ray fluorescence (µEDXRF) and spectrophotometry of enamel microbiopsy evaluated the calcium to phosphorous ratios (Ca/P). Two-way ANOVA and Tukey tests analyzed µRAMAN and µEDXRF results. Spectrophotometry results were analyzed using Kruskal-Wallis and Dunn tests. Pearson correlation tested µEDXRF and spectrophotometry results (α = 5%). RESULTS: NTAP and NTAP + HP exhibited greater PO43- content than LED, LED + HP and control (p < 0.05). No statistical differences were detected between CO32- among groups. While µEDXRF evaluation demonstrated that NTAP and LED did not alter Ca/P ratio of enamel (p > 0.05), spectrophotometry showed that Ca/P reduced for LED + HP (p < 0.05). No correlation was found between µEDXRF and enamel microbiopsy spectrophotometry (p > 0.05). CONCLUSIONS: Activation sources did not adversely impact enamel's phosphate and carbonate concentrations after specimens' exposure to bleaching gels (either HP or CP). Visible light radiation emitted by a LED source was shown to adversely impact specimens' Ca/P ratios when treated with HP-containing bleaching gels.

19.
Eur J Oral Sci ; 128(4): 336-344, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32502304

RESUMO

This study evaluated the effect of extending the duration of exposure to curing light on the depth of cure of two conventional (RBC1-conventional and RBC2-conventional) and two bulk-fill (RBC1-bulk and RBC2-bulk) resin composites. Polywave and single-peak photocuring units were used. Cylinder-shaped specimens were exposed to curing light either for the time period recommended by the manufacturer or twice the length of that time, and depth of cure was estimated using manual scraping (similar to the ISO-4049 standard) and solvent immersion techniques. Depth of cure was analyzed, using two-way ANOVA, for the factors measurement method and exposure time. For RBC1-conventional and RBC1-bulk, the solvent immersion technique estimated a greater depth of cure than did manual scraping; for RBC1-conventional, both techniques and both light-exposure time periods resulted in a depth of cure of >2 mm; and for RBC1-bulk, only the solvent method after photocuring for twice the manufacturer's recommended time resulted in a depth of cure of 5 mm. For RBC2-conventional and RBC2-bulk, neither technique nor exposure time resulted in estimated depths of cure that matched those indicated by the manufacturer. The results suggest that extending the duration of photopolymerization increases depth of cure. Also, calculation of depth of cure can vary according to the measurement technique used.

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