Andréia Bolzan de Paula

In vivo evaluation of laser fluorescence performance using different cut-off limits for occlusal caries detection.

The aim of this in vivo study was to evaluate the performance of laser fluorescence (LF) comparing different cut-off limits for occlusal caries detection. One hundred and thirty first permanent molars were selected. Visual examination and LF assessments were performed independently. The extent of caries was assessed after operative intervention. New cut-off limits were established and compared with those proposed by the manufacturer and by Lussi et al. (Eur J Oral Sci 109:14–19, 2001). Similar sensitivity and higher specificity was found at D2 (considering as disease only dentin caries) when the LF cut-off limits proposed by Lussi et al. and the new one were compared. At the D3 threshold (considering as disease only deep dentin caries), no statistically significant difference among the cut-off limits for sensitivity was found. However, the new cut-off limits showed higher specificity. The LF device provided good ability to detect dentin caries lesions. Furthermore, the new cut-off limits and the values proposed by Lussi et al. could be suggested for the in vivo detection of occlusal caries.

In vitro and in vivo investigation of the biological and mechanical behaviour of resin-modified glass-ionomer cement containing chlorhexidine

OBJECTIVES To evaluate: (1) the in vitro antibacterial, cytotoxic and mechanical properties of a resin-modified glass ionomer cement (RMGIC) containing different concentrations of chlorhexidine (CHX) and (2) the in vivo microbiologic action of the best concentration of CHX associated with the RMGIC applied on remaining dentine after indirect pulp treatment (IPT). METHODS For the in vitro studies, RMGIC was associated with 0.2, 0.5, 1.25 and 2.5% CHX. Microbiologic evaluation consisted of an agar diffusion test on cariogenic bacteria for 24h. Odontoblast-like cell metabolism and morphology analyses measured the cytotoxic effects of the RMGIC groups after 24h. The same groups were submitted to compressive and diametral tensile strength. The in vivo treatment consisted of IPT using an RMGIC associated with the best CHX concentration. Clinical and microbiologic evaluations were performed before and after 3 months. RESULTS The use of 1.25% CHX significantly improved the antibacterial effects of the evaluated RMGIC, without causing any detrimental effects to the odontoblast-like cells and on the mechanical properties. This RMGIC and CHX combination completely eliminated mutans streptococci after 3 months of IPT. CONCLUSION The RMGIC and 1.25% CHX mixture showed great biological and mechanical behaviour and could be a good treatment against caries progression. CLINICAL SIGNIFICANCE The association of CHX with a liner RMGIC opens a new perspective for arresting residual caries after IPT.

In situ and in vitro comparison of laser fluorescence with visual inspection in detecting occlusal caries lesions.

The aim of this study was to compare the in situ and in vitro performances of a laser fluorescence (LF) device (DIAGNOdent 2095) with visual inspection for the detection of occlusal caries in permanent teeth. Sixty-four sites were selected, and visual inspection and LF assessments were carried out, in vitro, three times by two independent examiners, with a 1-week interval between evaluations. Afterwards, the occlusal surfaces were mounted on the palatal portion of removable acrylic orthodontic appliances and placed in six volunteers. Assessments were repeated and validated by histological analysis of the tooth sections under a stereomicroscope. For both examiners, the highest intra-examiner values were observed for the visual inspection when in vitro and in situ evaluations were compared. The inter-examiner reproducibility varied from 0.61 to 0.64, except for the in vitro assessment using LF, which presented a lower value (0.43). The methods showed high specificity at the D1 threshold (considering enamel and dentin caries as disease). In vitro evaluations showed the highest values of sensitivity for both methods when compared to the in situ evaluations at D1 and D2 (considering only dentinal caries as the disease) thresholds. For both methods, the results of sensitivity (at D1 and D2) and accuracy (at D1) showed significant differences between in vitro and in situ conditions. However, the sensitivity (at D1 and D2), specificity and accuracy (both at D1) of the methods were not significantly different when the same condition was considered. It can be concluded that visual inspection and LF showed better performance in vitro than in situ.

Effect of Light Energy Density on Conversion Degree and Hardness of Dual-cured Resin Cement

This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturers instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. The tip of the light-curing unit (LCU) was positioned in contact with the Mylar surface. Quartz-tungsten-halogen (QTH) and light-emitting diode (LED) LCUs with light densities of 10, 20 and 30 J/cm2 were used to light-cure the specimens. After light curing, the specimens were stored dry in lightproof containers at 37 degrees C. After 24 hours, the CD was analyzed by FT-Raman and, after an additional 24-hours, samples were submitted to Knoop hardness testing. The data of the CD (%) and KHN were submitted to two-way ANOVA and the Tukeys test (alpha = 0.05). QTH and LED were effective light curing units. For QTH, there were no differences among the light energy densities for CD or KHN. For LED, there was a significant reduction in CD with the light energy density set at 10 J/cm2. KHN was not influenced by the light-curing unit and by its light energy density.

Effect of thickness of indirect restoration and distance from the light-curing unit tip on the hardness of a dual-cured resin cement

This study evaluated the Knoop hardness and polymerization depth of a dual-cured resin cement, light-activated at different distances through different thicknesses of composite resin. One bovine incisor was embedded in resin and its buccal surface was flattened. Dentin was covered with PVC film where a mold (0.8-mm-thick and 5 mm diameter) was filled with cement and covered with another PVC film. Light curing (40 s) was carried out through resin discs (2, 3, 4 or 5 mm) with a halogen light positioned 0, 1, 2 or 3 mm from the resin surface. After storage, specimens were sectioned for hardness measurements (top, center, and bottom). Data were subjected to split-plot ANOVA and Tukeys test (alpha=0.05). The increase in resin disc thickness decreased cement hardness. The increase in the distance of the light-curing tip decreased hardness at the top region. Specimens showed the lowest hardness values at the bottom, and the highest at the center. Resin cement hardness was influenced by the thickness of the indirect restoration and by the distance between the light-curing unit tip and the resin cement surface.

Mechanical and biological characterization of resin-modified glass-ionomer cement containing doxycycline hyclate

OBJECTIVES To characterize the mechanical and biological properties of a resin-modified glass ionomer cement (RMGIC) containing doxycycline hyclate. METHODS The antibacterial effect of RMGIC containing 1.5, 3.0 and 4.5% doxycycline hyclate was assessed using two experiments - agar diffusion test for 24h and biofilm assay for 24h and 7 days - against some cariogenic bacteria. Briefly, base layers of BHI agar and 300μL of each inoculum were prepared in Petri dishes with 6 wells that were completely filled with materials. After 24h incubation, zones of bacterial growth inhibition were measured using a digital caliper. Biofilm assays were conducted using RMGIC specimens immersed in 24-well plates containing the inoculum in BHI broth. After 24h and 7 days, each specimen were removed, vortexed and the suspension diluted and inoculated in BHI plates for subsequent bacterial counting. Cytotoxicity tests used 50 specimens made in sterilized metal molds, including Vitrebond as positive control. Extracts from every specimen were applied on the MDPC-23 odontoblast-like cells for 24h. The MTT assay and SEM evaluation determined cell metabolism and morphology, respectively. 80 cylindrical specimens were made from the previously cited groups, and were submitted to testing with a universal testing machine (Instron 4411) using a crosshead speed of 1.0mm/min for compressive strength and 0.5mm/min for diametral tensile strength, respectively. Data from antibacterial and cytotoxic effects, and mechanical properties were submitted to appropriated statistical tests. RESULTS All tested groups showed growth inhibition of all tested strains (p<0.05) in 24h for both microbiological tests, but only 4.5% doxycycline have antibacterial effect after 7 days. None of doxycycline concentrations caused toxic effect to the MDPC-23 cells or presenting alterations to mechanical properties. CONCLUSION The incorporation of up to 4.5% doxycycline hyclate into RMGIC inhibits important oral microorganisms, without modifying biological and mechanical characteristics of the dental material, suggesting a new alternative for the treatment of dental caries.

Effect of Restorative Technique and Thermal/Mechanical Treatment on Marginal Adaptation and Compressive Strength of Esthetic Restorations

This study evaluated the compressive strength and marginal adaptation of composite onlays using indirect and direct techniques after thermal and mechanical cycling. Onlay standardized cavities were prepared in 50 permanent molars and restored with Z-250 resin composite using indirect (IRT) or direct (DRT) restorative techniques. The restorations were either submitted or not submitted to thermal (500 cycles, 5 degrees to 55 degrees C) and mechanical cycling (50,000 cycles, 50N). The teeth were distributed to five groups (n=10): G1-IRT/cycling; G2-IRT/no cycling; G3-DRT/cycling; G4-DRT/no cycling and G5 (control group)-sound teeth. All prepared teeth were stored in 100% relative humidity at 37 degrees C for 24 hours, followed by finishing with Sof-Lex discs. A caries detector solution was applied on the tooth-restoration interface of all teeth for five seconds, followed by washing and drying. Four digital photographs were taken of each tooth surface. The extent of gaps was measured using standard software (Image Tool 3.0). All groups were submitted to compression testing in a universal testing machine (INSTRON) at a crosshead speed of 1 mm/minute until failure. The compressive strength (CS) and marginal adaptation data were submitted to ANOVA and Tukey test (p<0.05). For both evaluation criteria (compressive strength and marginal adaptation), there were no statistically significant differences among the restorative techniques. Deterioration over time was observed for both types of restorations. However, the prevalence of catastrophic fractures increased among direct restorations. The application of thermal/mechanical cycling only influenced marginal adaptation.

Evaluation of sorption/solubility, softening, flexural strength and elastic modulus of experimental resin blends with chlorhexidine

OBJECTIVES To evaluate physical-chemical properties of experimental diacetate chlorhexidine (CHX)-added resin blends. METHODS Blends were formulated: G1)TEGDMA; G2)TEGDMA/0.1%CHX; G3)TEGDMA/0.2%CHX; G4)TEGDMA/UDMA; G5)TEGDMA/UDMA/0.1%CHX; G6)TEGDMA/UDMA/0.2%CHX; G7)TEGDMA/BisEMA, G8)TEGDMA/BisEMA/0.1%CHX; G9)TEGDMA/BisEMA/0.2%CHX. Icon(®) was the control group. For sorption/solubility (SS), cylindrical specimens (n=5) were prepared and their weight obtained. The specimens were immersed in deionized water for 7days at 37°C and their weight was verified again. SS were calculated using accepted formulas. For softening, cylindrical specimens (n=10) were prepared and initial Knoop hardness number (KHN) obtained. The specimens were immersed in absolute ethanol for 24h at 37°C and final KHN accomplished. Softening values were calculated by KHN reduction percentage. For elastic modulus (EM) and flexural strength (FS) bar specimens were prepared (n=10) and values obtained with a universal device (three point, 5mm distance, 0.5mm/min, load of 50N). The data was analyzed using one-way ANOVA and Tukey test (α=5%). RESULTS TEGDMA/BisEMA blends and Icon(®) showed the lowest sorption from blends (p>0.05), and Icon(®) was the most soluble material (p<0.01). TEGDMA/UDMA/0.1%CHX showed the highest softening, similar to Icon(®) (p>0.05). For EM, all blends were different than Icon(®) (p<0.01). For FS, TEGDMA blends were similar to Icon(®), showing the lowest averages (p>0.05). CONCLUSIONS Monomers chemical characteristics influenced the physical-chemical properties of experimental blends more than CHX. Between the blends tested, UDMA blends presented satisfactory results for assays evaluated. CLINICAL SIGNIFICANCE Infiltrants CHX-added could arrest and reinforce initial caries lesions, and the antimicrobial effect could prevent new lesions in sound enamel adjacent to the infiltrated area.

Marginal adaptation of indirect restorations using different resin coating protocols.

This study evaluated the influence of material combinations used in the resin coating technique (RCT) on the marginal adaptation of indirect restorations with gingival margins in enamel (EM) and cement (CM). Eighty third-molars were used. Two cavities were prepared in each tooth. The cavities were distributed into 16 groups. Cavities with EM were filled with the following material combinations: G1: Single-Bond 2 (Sb2), G2: Sb2 + Bond/Scotchbond-Multipurpose (Sb2B), G3: Sb2 + Filtek-Flow Z350 (Sb2Fl), G4: Scotchbond-Multipurpose (SBMP), G5: Clearfil-S3 (CS3), G6: CS3 + Bond/Clearfil-SE Bond (CSE3B), G7: CS3 + Protect Liner F (CS3PL) and G8: Clearfil SE Bond + Protect Liner F (CSEBPL). The same combinations were applied to the cavities in CM: G9, G10, G11, G12, G13, G14, G15, G16, respectively. The fillings were performed with the Sinfony-System (3M/ESPE). After 24 h, the teeth were submitted to thermocycling (2,000 cycles, 5° to 55°C) and load-cycling (50,000 cycles, 50 N). Next, the Caries-Detector (Kuraray) was applied to the restoration margins. Images from the proximal margin were evaluated using the Image-Tool 3.0 software. The results were submitted to ANOVA and Tukeys test (α=0.05). The mean values (%) for the groups were: EM: G1=46.68, G2=15.53, G3=19.83, G4=27.53; G5=59.49, G6=25.13, G7=34.37, G8=15.20; CM: G9=38.38, G10=23.25, G11=26.97, G12=25.85, G13=37.81, G14=30.62, G15=29.17, G16=20.31. The highest percentages of marginal gap on EM or CM were found in the groups that did not use a liner. It can be concluded that the most appropriate RCT combinations were the groups that used a liner.

Effects of Chemical Agents on Physical Properties and Structure of Primary Pulp Chamber Dentin

This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty‐five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n = 5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl + Endo‐PTC®; SH1E, 1% NaOCl + 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one‐way ANOVA and Tukeys test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo‐PTC® were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52–56, 2014.