Efficacy of calcium‐ and fluoride‐containing materials for the remineralization of primary teeth with early enamel lesion

The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP) cream, and 5) Clinpro White varnish containing functionalized tri‐calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one‐way ANOVA (p<0.05). Mean microhardness of demineralized enamel was significantly lower than in enamel at baseline (p<0.001). Remineralization significantly increased microharness in groups 2 to 5 compared to the control group (p<0.001). Percent EMH after remineralization with CPP‐ACP was significantly higher than after fTCP (p=0.029), toothpaste (p< 0.001) or fluoride varnish (p<0.001); however, there was no significant difference between toothpaste and fluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (p<0.001) or fluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP‐ACP, toothpaste and fluoride varnish. The efficacy of CPP‐ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish. Microsc. Res. Tech. 78:801–806, 2015. © 2015 Wiley Periodicals, Inc.     

Remineralization effects of self-assembling peptide P11-4 associated with three materials on early enamel carious lesions: An in vitro study

The aim of this study was to assess the remineralization of enamel caries lesions using the self-assembling peptide P₁₁-4 associated with different materials. Artificial early enamel lesions were prepared on 154 primary teeth. The samples were randomly divided into eight groups: (1) control, (2) P₁₁-4, (3) fluoridate toothpaste (FT), (4) P₁₁-4 + FT, (5) casein phosphopeptide–amorphous calcium phosphate (CPP–ACP), (6) P₁₁-4 + CPP–ACP, (7) fluoridate bioactive glass toothpaste (BT), and (8) P₁₁-4 + BT. The surface enamel microhardness (EMH) and energy-dispersive X-ray spectroscopy (EDS) of the teeth were then measured at the baseline, after demineralization, and after 28 days of remineralization. The enamel surfaces were assessed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The data were analyzed with one-way analysis of variance (ANOVA) (p < .05). EMH after demineralization was significantly lower than the baseline value (p < .001). The interventions led to an enhanced percentage of EMH recovery (%REMH), which was higher in Groups 6 and 7. There was no significant difference between Groups 3 and 4. Groups 1 and 2 had the lowest %REMH. The mean calcium/phosphate weight percentage ratio of P₁₁-4 was significantly lower than the others (p < .001). The FESEM and AFM images revealed mineral deposition on the eroded enamel and reductions in surface roughness in Groups 5 and 7.     

Analysis of efficacy of the self‐assembling peptide‐based remineralization agent on artificial enamel lesions

The objective of this in vitro study was to analyze and compare the biomimetic remineralizing efficacy of the self‐assembling peptide (P11‐4) with agents containing casein phoshopeptide‐amorhous calcium phosphate fluoride (CPP‐ACFP) and sodium fluoride (NaF) on artificial caries lesions using DIAGNOdent and micro‐computed tomography (μCT). Artificial enamel lesions were prepared on extracted impacted sound mandibular third molars. The samples were randomly allocated to four groups (n = 8): Group 1, P11‐4 (Curodont Repair, Credentis AG, Switzerland); Group 2, CPP‐ACFP (MI Varnish, GCCo., Japan); Group3, NaF (Duraphat Varnish, Colgate, Colgate‐Palmolive, NY, USA); Group 4, artificial saliva (control). The agents were applied to demineralized surfaces according to manufacturers' instructions; all specimens were stored in artificial saliva for 1 month. Demineralization and remineralization on enamel surfaces were analyzed and quantified by DIAGNOdent (KaVo, Germany) and μCT (SkyScan1174, Belgium) for lesion depth/area/volume/mineral density (MD). The remineralization efficacy of the agents was evaluated by DIAGNOdent on 1st, 7th, 30th days and by μCT on 30th day. Data were statistically analyzed by ANOVA, Kruskal–Wallis, T test, and Wilxocon tests. The highest remineralization efficacy findings in all periods were determined in Group 1, followed by Groups 2, 3, and 4. The remineralization findings for fluorescence, MD, lesion depth in Group 1 were found significantly higher (p < 0.01) than Group 3; and no significant differences (p > 0.05) were found between Groups 1–2 and Groups 2–3. The area and volume change values in Groups 1, 2, and 3 have shown no significancy (p > 0.05). A significant correlation (p < 0.01) was found between μCT and DIAGNOdent methods. The data of this study have demonstrated that P11‐4 has showed the best remineralization efficacy, followed by CPP‐ACFP and NaF. It is concluded that self‐assembling peptide‐based remineralization agent can be used successfully for biomimetic remineralization of enamel subsurface lesions.     

Enamel alteration following tooth bleaching and remineralization

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence^® Boost and Mirawhite^® Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive^® hap+, Mirawhite^® Gelle?, GC Tooth Mousse? and Mirafluor^® C. The samples were analysed by SEM/3D‐SEM‐micrographs, SEM/EDX‐qualitative analysis and SEM/EDX‐semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line‐scans of the sample remineralized with GC Tooth Mousse?. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth‐bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes.     

Erosion effects on chemical composition and morphology of dental materials and root dentin

Purpose: This work aims to study the erosion on restorative materials and on surrounding dentin. Fifty root dentin samples were obtained from bovine incisors. Methods: Twenty samples were not restored and thirty received cavity preparations. Samples were assigned to five groups: G1, G2: sound dentin (D); G3: composite resin (CR); G4: resin‐modified glass‐ionomer cement (RMGIC); G5: glass‐ionomer cement (GIC). The samples of groups 2–5 were submitted to six cycles (demineralization–remineralization). Samples were analyzed by micro energy‐dispersive X‐ray fluorescence spectrometry (μ‐EDXRF) and by scanning electron microscopy (SEM). Results: Mineral loss was greater in G2 samples than in RMGI > CR > GIC > D (control). SEM images showed pronounced dentin demineralization in groups 2 and 4. The acid erosion has a significant effect on mineral loss (Ca and P) of root dentin without restoration. Conclusions: Composite resin had the best chemical resistance to erosion among all the materials. Fluoride contained in GIC seemed to cause some protection, however, with material degradation. Chemical interaction of tooth‐colored dental materials with root dentin could be assessed by μ‐EDXRF. Microsc. Res. Tech. 75:703–710, 2012. © 2011 Wiley Periodicals, Inc.     

Comparison of methods for quantifying dental wear caused by erosion and abrasion

Various methods have been applied to evaluate the effect of erosion and abrasion. So, the aim of this study was to check the applicability of stylus profilometry (SP), surface hardness (SH) and focus‐variation 3D microscopy (FVM) to the analysis of human enamel and dentin subjected to erosion/abrasion. The samples were randomly allocated into four groups (n = 10): G1‐enamel/erosion, G2‐enamel/erosion plus abrasion, G3‐dentin/erosion, and G4‐dentin/erosion plus abrasion. The specimens were selected by their surface hardness, and they were subjected to cycles of demineralization (Coca‐Cola®‐60 s) and remineralization (artificial saliva‐60 min). For groups G2 and G4, the remineralization procedures were followed by toothbrushing (150 strokes). The above cycle was repeated 3×/day during 5 days. The samples were assessed using SH, SP, and FVM. For each substrate, the groups were compared using an unpaired t‐test, and Pearson correlation coefficients were calculated (α = 5%). For enamel, both profilometry technique showed greater surface loss when the erosion and abrasion processes were combined (P <0.05). The correlation analysis did not reveal any relationships among SH, SP, and FVM to G2 and G4. There were significant correlation coefficients (–0.70 and –0.67) for the comparisons between the FVM and SH methods in enamel and dentin, respectively, in G1 and G3. Choosing the ideal technique for the analysis of erosion depends on the type of dental substrate. SP was not sufficiently sensitive to measure the effects on dentin of erosion or erosion/abrasion. However, SP, FVM and SH were adequate for the detection of tissue loss and demineralization in enamel. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Efficacy of in-office bleaching techniques combined with the application of a casein phosphopeptide-amorphous calcium phosphate paste at different moments and its influence on enamel surface properties

OBJECTIVES: The aim of this in vitro study was to investigate the efficacy of in‐office bleaching technique combined with the application of a casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP) paste (MI Paste–MI) at different moments and its influence on enamel surface properties. METHODS: Eighty bovine dental crowns were randomly allocated into eight groups (n = 10), and bleached with either 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP). Four different protocols of application of MI were considered: without MI, MI applied before bleaching, MI applied after bleaching, and MI applied both before and after bleaching. Bleaching effectiveness was measured by the VITA EasyShade spectrophotometer utilizing the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*). Color readings were measured at baseline, 7, 14, and 21 days. Hardness and roughness were measured at baseline (T0) and immediately after bleaching (T14). Data were subjected to the two‐way ANOVA for repeated measurements and Tukey's test at 5%. RESULTS: HP groups achieved the greatest color change. The application of a CPP‐ACP paste did not reduce the efficacy of bleaching peroxides. Samples bleached with CP showed decreased hardness at T14. Samples bleached with HP that received the application of MI before and before/after bleaching did not present hardness decrease at T14. Samples bleached with peroxides only and received MI after bleaching showed increased roughness at T14. CONCLUSIONS: The use of CPP‐ACP was able to prevent negative changes in roughness and hardness of bovine enamel when associated to hydrogen peroxide, and might be applied before/after the bleaching protocol. Microsc. Res. Tech. 75:1019–1025, 2012. © 2012 Wiley Periodicals, Inc.     

Antibacterial activity of glass ionomer cement modified by zinc oxide nanoparticles

This study evaluated the antibacterial activity of zinc oxide nanoparticles incorporated into self‐cured glass ionomer cement (GIC) and light‐cured resin‐reinforced GIC on Streptococcus mutans biofilm. The GICs, Fuji II (GC America) and Fuji II LC (GC America), were incorporated with nanoparticles at concentrations of 0%, 1%, and 2% by weight, and the biofilm maturation time was one and seven days. Circular specimens of each GIC type were prepared. The antibacterial activity was evaluated by determining the number of colony forming units of S. mutans strain per milliliter. Morphology of the biofilm was analyzed by scanning electron microscopy (SEM). The data obtained for each GIC were analyzed by two‐way ANOVA (α = 5%). For chemically activated GIC, no significant difference was observed in relation to the time of biofilm maturation (p = 0.744), concentration of nanoparticles (p = 0.966), and their interaction (p = 0.800). The results from analysis of GIC modified by light‐polymerized resin showed that only of the maturing time significantly affected the number of adhered cells on the biofilm (p = 0.034, F = 4.778). The more mature the biofilm, higher the number of cells. SEM analysis showed no change in cell morphology in relation to the type of GIC, maturation time, and nanoparticles concentration. We conclude that the inclusion of zinc oxide nanoparticles at concentrations of 1% and 2% by weight into the GICs evaluated here, did not promote their antimicrobial activity against S. mutans.     

Antibacterial activity of chlorhexidine after final irrigation with ethanol: CLSM and culture‐based method analysis

This study investigated the effect of 95% ethanol on the antibacterial properties of 2% chlorexidine (CHX) over monospecies biofilm (Enterococcus faecalis) through a culture‐based method, and over multispecies biofilm using confocal laser scanning microscopy (CLSM). For monospecies model, E. faecalis biofilm was induced in 40 root canals. The irrigation procedures were: S—saline solution; S/CHX—saline solution + CHX; E—ethanol; and E/CHX—ethanol + CHX. Microbial sampling was performed at three periods: before (S1), immediately after (S2), and 72 h after the final flush (S3). For multispecies biofilm model, 28 sterilized bovine dentin blocks were fixed on a removable orthodontic device to allow intraoral biofilm development. Seven samples were used in each group. Statistical analysis was carried out by using the Kruskal–Wallis test and Dunn's test for multiple comparisons. There was a significant reduction in CFUs count immediately after the final flush (S2) in all experimental groups (P < 0.05). However, only S/CHX, E and E/CHX groups had CFU counts close to zero, without differences among them (P > 0.05). After 72h (S3), the S/CHX and E/CHX groups had CFU counts near zero (P > 0.05). The CFU count increased in S3 for S and E groups (P < 0.05). CLSM showed that the percentages of remaining live cells were similar in S/CHX, E, and E/CHX groups (P > 0.05). The S group had the highest percentage of live cells (P < 0.05). The 95% ethanol did not interfere in the antibacterial properties of 2% CHX over mono‐ and multispecies biofilms. Microsc. Res. Tech. 78:682–687, 2015. © 2015 Wiley Periodicals, Inc.     

Tissue integrity,costs and time associated with different agents for histological bone preparation

The selection of an appropriate demineralizing solution in pathology laboratories depends on several factors such as the preservation of cellularity, urgency of diagnostic and financial costs. The aim of this study was to test different decalcification bone procedures in order to establish the best value of these in formalin‐fixed and paraffin‐embedded samples. Femurs were removed from 13 adult male Wistar rats to obtain 130 bone disks randomly divided into five groups that were demineralized in different concentrations of nitric acid (Group I); formic acid (Group II); acetic acid (Group III); EDTA, pH7.4 (Group IV) and Morsés solution (Group V). Serial, 3‐μm‐thick sections were obtained and stained with hematoxylin‐eosin to calculate the percentage of osteocyte‐occupied lacunae. The sections were also stained with Masson's trichrome in conjunction with picrosirius red under polarized light followed by a semi‐quantitative analysis to verify the adjacent muscle‐to‐bone integrity and preservation of collagen fibres. The highest percentage of osteocyte‐occupied lacunae was found with 10% acetic acid solution (95.64 ± 0.95%) and Group I (nitric acid) demanded the shorter time (0.8–5.7days). Of all solutions, 5% nitric acid incurred the lowest cost to achieve complete demineralization compared with other solutions (p < .001). Group IV (EDTA) had the highest integrity of muscle and collagen type I and III (P < 0.01). Demineralization with 10% acetic acid was the most effective at preserving bone tissue, while 5% EDTA was the best at maintaining collagen and adjacent muscle to bone. In conclusion, nitric acid at 5% showed the most efficient result as it balanced both time and cost as a demineralizing solution.     

Effect of final irrigation protocols on microhardness and erosion of root canal dentin

The aim of this study was to evaluate the effect of final irrigation protocols (17% EDTA, BioPure MTAD, SmearClear, and QMiX) on microhardness and erosion of root canal dentin. Fifty roots were sectioned transversely at the cement–enamel junction and each root was sectioned horizontally into 4‐mm‐thick slices. The samples were divided into five groups (n = 10) according to the final irrigation protocol: G1: distilled water (control group); G2: 17% EDTA; G3: BioPure MTAD; G4: SmearClear; and G5: QMiX. The dentin microhardness was then measured with a load of 25 g for 10 s. Initially, the reference microhardness values were obtained for the samples without any etching. The same samples were then submitted to the final irrigation protocols. A new measure was realized and the difference between before and after the procedures was the dentin microhardness reduction. In sequence, the specimens were submitted to SEM analysis to verify the dentinal erosion. The Kruskal Wallis and Dunn tests (α = 5%) were used to compare the results. The dentin microhardness decreased for all final irrigation protocols. There was no significant difference between groups 2, 3, 4, and 5 (P > 0.05), but this groups presented significant dentin microhardness reduction than G1 (P < 0.05). In G2, occurred the highest incidence of dentinal erosion (P < 0.05). 17% EDTA, BioPure MTAD, SmearClear, and QMiX promoted significant dentin microhardness reduction. Dentinal tubules erosion was promoted by 17% EDTA. Microsc. Res. Tech., 76:1079–1083, 2013. © 2013 Wiley Periodicals, Inc.     

Does laser etching have an effect on application mode of a universal adhesive?—A microleakage and scanning electron microscopy evaluation

This study aimed to evaluate the microleakage of a universal adhesive's different application modes incorporated with Er,Cr:YSGG laser on Class V resin composite restorations. Sound human molar teeth (n = 30) were used for microleakage evaluations. Specimens with 60 standardized Class V cavities were divided into five groups according to the adhesive modes of universal adhesive, Adhese Universal (n = 12). Group 1‐etch‐and‐rinse mode with phosphoric acid; Group 2‐etch‐and‐rinse mode with Er,Cr:YSGG laser; Group 3‐selective‐etch mode with phosphoric acid; Group 4‐selective‐etch mode with Er,Cr:YSGG laser; Group 5‐self‐etch. After restorations were performed with a resin composite, Tetric N‐Ceram, the specimens were polished and subjected to thermocycling (10,000X). Following immersion in 0.5% basic fuschin for a day, the teeth were sectioned and the degree of microleakage was determined along the tooth‐resin composite interface using a light microscopy(40X). Five specimens from each group were examined by scanning electron microscopy. The Kruskal–Wallis, Siegel Castello, and Wilcoxon tests were used for statistical analyses (α = .05). At the enamel margins, significant differences were obtained among the groups (p < .05). Significantly higher microleakage scores were detected in Group 5 in comparison with Groups 1, 2, and 3. There were no significant differences between different adhesive strategies at the dentin margins (p > .05). While analyzing enamel and dentin microleakage scores, no statistically significant differences were observed in Groups 4 and 5 (p > .05). The laser application time and the adhesive modes of universal adhesives could affect the microleakage at the enamel margins. Different adhesive modes of universal adhesives combined with laser etching had no influence on the microleakage scores of dentin margins.     

Chemical and crystallographic study of remineralized surface on initial carious enamel treated with Galla chinensis

To investigate the morphologic, chemical and crystallographic characters of remineralized surface on initial carious enamel treated with Galla chinensis, scanning electron microscopy equipped with energy dispersive analysis spectroscopy were used, and X‐ray microdiffraction (microzone XRD) was used for the first time to analyze in situ the microzone crystallite of remineralized surface on carious enamel. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days of remineralization. Each daily cycle included 4×1 min applications with one of the three treatments: distilled and deionized water (DDW); 1 g/L NaF; 4 g/L G. chinensis extract (GCE). After the treatments, some rod‐like deposits and many irregular prominences were found on GCE‐treated enamel surface, and the intensities of Ca and P signals showed a tendency to increase; Ca:P ratio was significantly higher than that of DDW‐treated enamel. X‐ray microdiffraction showed hydroxyapatite was still the main component of GCE‐treated enamel, and the crystallinity was increased, the crystal lattice changed gently with decreased lattice parameter a. These results indicated the potential of GCE in promoting the remineralization of initial enamel carious lesions, and supported the previous hypothesis about GCE mechanism. Combined with the anti‐bacteria and demineralization inhibition properties of GCE, the natural G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 236–245, 2009. © 2010 Wiley Periodicals, Inc.     

Peracetic acid as a single endodontic irrigant: effects on microhardness,roughness and erosion of root canal dentin

The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl.     

Comparison of total‐etch,self‐etch,and selective etching techniques on class V composite restorations prepared by Er:YAG laser and bur: a scanning electron microscopy study

The purpose of this study was to compare total‐etch, self‐etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group‐1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group‐2: laser preparation(lp)+(ASB)+(FZ); Group‐3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group‐4: lp+(CSBP) (FZ); Group‐5: bp + acid etching+(CSBP)+(FZ); Group‐6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5–55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur.     

Effects of Galla chinensis on the surface topography of initial enamel carious lesion: an atomic force microscopy study

To investigate the effect of Galla chinensis on the surface topography of initial enamel carious lesion, atomic force microscope (AFM) was used, and it was a new AFM application in enamel de‐/remineralization research. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of three treatments: negative control group: deionized water; positive control group: 1 g/L aqueous solutions of NaF; experimental group: 4 g/L aqueous solutions of G. chinensis extract (GCE). The surface topography and roughness were investigated on the enamel slabs before and after pH‐cycling by AFM. 3D AFM images revealed the surface topographical changes of GCE‐treated enamel. Significant difference existed before and after the pH‐cycling among the groups. AFM offers a powerful tool for enamel de‐/remineralization research. The surface roughness results provide the evidences to remineralization of carious lesion, and indicate the potential of G. chinensis in promoting the remineralization. G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 195–203, 2009. © 2010 Wiley Periodicals, Inc.     

Comparison between the use of thermoplasticized gutta‐percha and a polydimethyl siloxane‐based material in filling internal resorptive cavities using spiral computed tomography

To evaluate the fill of internal resorption cavities obturated with thermoplasticized gutta‐percha and GuttaFlow2 using CT scan. Twenty human maxillary anterior teeth were selected and root canals were prepared using ProTaper system to size F3. Irrigation was performed with 5 ml of 2.5% sodium hypochlorite (NaOCl) and 5 ml of 17% ethylenediaminetetraacetic acid (EDTA). Each root was then sectioned horizontally into two halves and semicircular cavities were prepared around the periphery of the root canal opening of each root half, using a round bur. Both the root halves were then fixed using cyanoacrylate glue. All the specimens were subjected to preoperative CT scan analysis to determine the volume of internal cavities. The samples were then randomly divided into two groups. In Group 1, the specimens were obturated with thermoplasticized gutta‐percha (E&Q system) and specimens in Group 2 were obturated using GuttaFlow2. All specimens were then subjected to postoperative CT scan analysis. The volume of voids in internal resorptive cavities were calculated, which was then used to estimate the amount of gutta‐percha filled. There was no significant difference in volume of internal resorptive cavities between thermoplasticized gutta‐percha and GuttaFlow2 groups before obturation (p = 0.466). However, after obturation there was a significant difference between both the groups, in which GuttaFlow2 demonstrated better fill (p = .014). Thermoplasticized gutta‐percha filled 81% of internal resorptive cavity while GuttaFlow2 filled 91%, respectively. GuttaFlow2 showed better fill than thermoplasticized gutta‐percha in the filling of internal resorptive cavities.     

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 Tukey's 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. © 2013 Wiley Periodicals, Inc.     

Effects of etchant on the nanostructure of dentin: an atomic force microscope study

The objective of this study is to investigate effects of etchant on dentin surface as a function of etching time by atomic force microscopy (AFM). Twenty intact, freshly extracted noncarious human teeth were used to make 40 dentin discs and the discs were randomly divided into 4 groups. A commercial etchant was applied on these dentin discs. The main component of the etchant is 32% phosphoric acid and the etching time for the four dentin disc groups was 0, 20, 40, and 60 s. The AFM results show progressive changes of the surface morphology as the etching time increases. Significant difference of average roughness (R_a) exists in the dentin surface among all four groups (p<0.05). The statistic difference of diameters of dentinal tubule orifice (D_t) exists between the control group and all other groups (p<0.05), whereas the D_ts for the 40‐s group and 60‐s group are not statistically different (p>0.05). Our results showed that acid treatment has a significant influence on dentin demineralization and the effective etching time of the dentin surface appears to be 60 s. We provide a new nanoscale insight into the dentin surface treatment and this can help us to select the optimal etching time in clinic. SCANNING 31: 28–34, 2009. © 2009 Wiley Periodicals, Inc.     

Histological analysis of biocompatibility of different surgical adhesives in subcutaneous tissue

The focus of this study was to test the hypothesis that there would be no difference between the biocompatibility of cyanoacrylate‐based adhesives in rat subcutaneous tissues. In total, 60 male Wistar rats were used, and divided into four groups (n = 15): Group C (control, PVA‐polyvinyl alcohol sponge), Group NO (N‐butyl‐2‐octylcyanoacrylate), Group NH (n‐hexyl‐cyanoacrylate), and Group EC (Ethyl‐cyanoacrylate). The animals were sacrificed after time intervals of 7, 15, and 30 days and tissues were analyzed under optical microscope as regards the events of inflammatory infiltrate, edema, necrosis, granulation tissue, giant cells, young fibroblasts, and collagen formation. The results were statistically analyzed by the Kruskal–Wallis and Dunn tests (p < .05). Significant inflammatory infiltrate was shown for all the adhesives in the time intervals of 7 (p = .004) and 15 days (p = .003). In the time interval of 30 days, moderate inflammatory infiltrate was observed in Groups NH and EC, with significant difference from Control (p = .001). The quantity of collagen fibers in all the experimental groups showed significant difference compared with Control in the time intervals of 7 (p = .002) and 15 days (p = .001), at 30 days only Group EC showed a smaller quantity of collagen fibers in comparison with Control (p = .001). The hypothesis was rejected. The adhesive N‐butyl‐2‐octylcyanoacrylate had less influence on the inflammatory intensity of multinucleated giant cells. Ethyl‐cyanoacrylate demonstrated the lowest level of biocompatibility among the adhesives, but its use in clinical practice may be promising for coaptation of smaller edges of superficial tissue. Surgical adhesives were shown to be feasible for clinical use in substitution of conventional suturing. Ethyl‐cyanoacrylate should be used with caution due to its greater influence on tissues.