Microleakage Evaluation of Composite Restorations Following Papain-Based Chemo-Mechanical Caries Removal in Primary Teeth.

AIM: To evaluate the microleakage of composite restorations following Papain-based chemo-mechanical caries removal compared to the conventional drilling method. The characteristic of the hybrid layer was also studied using scanning electron microscopy. STUDY DESIGN: The sample included thirty freshly extracted and exfoliated primary molars with open proximal carious dentin lesions. Teeth were divided into two equal groups, according to method of caries removal. Following caries removal, cavity preparations were restored with composite resin. After thermocycling, teeth were sealed apically and coated with nail polish except the surface of restorations and the surrounding 1mm. Teeth were immersed in basic fuschin dye solution, then they were sectioned mesiodistally. The extent of dye penetration was detected using a light stereomicroscope. After microleakage test, the resin/dentin interface was examined using scanning electron microscopy. RESULTS: There was no significant difference in the degree of leakage between both groups. In the Papacarie group, longer and numerous resin tags were observed with statistically significant thicker hybrid layer than those following the drilling method. However, there was no significant difference between the diameters of resin tags of both groups. CONCLUSIONS: Papacarie does not adversely affect the microleakage of composite restorations and provides a suitable surface for bonding.

Effect of Qmix and Other Irrigants on Dentin Adhesives in Pulp Chambers of Primary Teeth: SEM Study.

OBJECTIVE: To compare the effect of different endodontic irrigants on microleakage of adhesives used within pulp chamber of primary molars. STUDY DESIGN: 72 Primary molars were divided into 6 groups, according to 3 irrigants and 2 adhesives used. After de-roofing the pulp chamber, pulp was extirpated. In 36 samples, pulp chambers were bonded with Xeno V+ after irrigation with either QMix (Group1); 17%EDTA+5%NaOCl (Group2) or normal saline (Group3) and in other half samples, pulp chambers were bonded with SinglebondUniversal after irrigation with either QMix (Group 4); 17%EDTA+5% NaOCl (Group5) or normal saline (Group 6). All the samples were restored with Filtek Z350. Ten teeth from each group were assessed for dye penetration. Two samples in each group were viewed under scanning electron microscope. Data was statistically analyzed using Mann-Whitney and Kruskal Wallis tests at a significance level of P < 0.05. RESULTS: Mean microleakage scores were: Group 1-1.5±0.70, Group 2-1.6±.51, Group 3-2.4±0.96, Group 4-1.2±0.42, Group 5-1.2±0.42, Group 6-1.1±0.32. CONCLUSIONS: Irrigation with QMix significantly reduced the microleakage of XenoV+ but had no significant effect on microleakage of SinglebondUniversal. Irrigation with EDTA/NaOCl or QMix had no detrimental effect on the sealing ability of either of the adhesive tested.

Selective Acid Etching Improves the Bond Strength of Universal Adhesive to Sound and Demineralized Enamel of Primary Teeth.

PURPOSE: To evaluate the influence of enamel condition and etching strategy on bond strength of a universal adhesive in primary teeth. MATERIALS AND METHODS: Thirty-six primary molars were randomly assigned to six groups (n = 6) according to the enamel condition (sound [S] and demineralized [DEM]/cariogenic challenge by pH cycling prior to restorative procedures) and adhesive system (Scotchbond Universal Adhesive [SBU]) used in either etch-and-rinse (ER) or selfetching (SE) mode, with Clearfil SE Bond as the self-etching control. The adhesives were applied to flat enamel surfaces and composite cylinders (0.72 mm2) were built up. After 24-h storage in water, specimens were subjected to the microshear test. Bond strength (MPa) data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α = 0.05). RESULTS: Significant differences were found considering the factors adhesive system (p = 0.003) and enamel condition (p = 0.001). Demineralized enamel negatively affected the bond strength, with µSBS values approximately 50% lower than those obtained for sound enamel. SBU performed better in etch-and-rinse mode, and the bond strength found for SBU applied in self-etching mode was similar to that of CSE. CONCLUSIONS: Enamel etching with phosphoric acid improves the bond strength of a universal adhesive system to primary enamel. Demineralized primary enamel results in lower bond strength.

Do the ball-ended probe cause less damage than sharp explorers?-An ultrastructural analysis.

BACKGROUND: No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. METHODS: Forty-nine primary extracted teeth were tactile examined as performed for caries activity assessment. Surfaces were randomly divided into groups based on probe type (ball-ended probe or sharp explorer). Two examiners probed different surfaces using the sharp explorer and the ball-ended probe. The order for examination was randomly determined. Images were captured using environmental scanning electron microscopy (ESEM) before and after probing. Two external examiners evaluated independently the ESEM images and scored them as: 0) no damage, 1) slight marks, 2) distinct marks, 3) marks with discontinuity, 4) enamel break-offs. Multilevel Poisson regression models were used to analyze associations between probing ultrastructural damage and surface type, baseline condition and probe type. Prevalence ratios (PR) were calculated with 95 % confidence interval (CI). RESULTS: The most common defects observed on the dental surfaces were probing marks without discontinuity (scores 1 and 2). Ball-ended probes caused significantly less severe damage than sharp explorers (PR: 0.28; CI: 0.11-0.76, p = 0.01). CONCLUSION: Ball-ended probes cause less damage than sharp explorers when probing gently dental surfaces of primary teeth.

Effectiveness of Rotary Endodontic Instruments on Smear Layer Removal in Root Canals of Primary Teeth: A Scanning Electron Microscopy Study.

AIM: The present SEM study was undertaken to evaluate the effect of root canal instrumentation using both manual and rotary files in the root canals of primary anterior teeth. STUDY DESIGN: Thirty freshly extracted primary maxillary incisors were divided into 3 groups of 10 teeth each. In Group I, root canals were instrumented with rotary NiTi files; in Group II, the root canals were instrumented using manual NiTi K files and; in Group III, manual instrumentation was done with stainless steel K files. Longitudinal sections were prepared and processed for observation under SEM at the coronal, middle and apical thirds. Scoring of smear layer was done according to Hulsmann and the data obtained was subjected to statistical analysis. RESULTS: Rotary files cleaned the coronal and middle thirds of root canals more effectively. Statistically there was no significant difference between the groups. Lowest score of 2.6 in the apical third of root canals was seen with hand NiTi files. CONCLUSION: Rotary instrumentation was as effective as manual instrumentation in removal of smear layer in the root canals of primary anterior teeth.

In Vitro Evaluation of Microleakage and Microhardness of Ethanolic Extracts of Propolis in Different Proportions Added to Glass Ionomer Cement.

OBJECTIVE: To evaluate the effect of ethanolic extracts of propolis (EEP) addition in different proportions to glass ionomer cement (GIC) on microleakage and microhardness of GIC. STUDY DESIGN: The cement was divided into four groups: one using the original composition and three with 10%, 25%, and 50% EEP added to the liquid and then manipulated. For microleakage assessment, sixty primary molars were randomly divided into four groups (n=15). Standard Class II cavities were prepared and then filled with EEP in different proportions added to GICs. Microleakage test was performed using a dye penetration method. The data were analyzed using one-way ANOVA and Mann-Whitney U tests (α = 0.05). Disc shaped specimens were prepared from the tested GIC to determine Vickers hardness (VHN). The data were analyzed using one-way ANOVA and post hoc Tukey test (α = 0.05). RESULTS: There were no statistically significant differences between the groups in terms of microleakage (p > 0.05). There were statistically significant differences between the VHN values of groups (p < 0.05). Increasing addition of EEP to GIC statistically significantly increased VHN value of GIC (p < 0.05). CONCLUSIONS: The addition of EEP to GIC increased the microhardness of the GIC and did not adversely affect the microleakage. Thus, it might be used during routine dental practice due to its antibacterial properties.

Dentin Topographic Features following Chemomechanical Caries Removal in Primary Teeth.

AIM: Study the topographic features of dentin after caries removal with a chemomechanical agent (Papacarie) compared with the conventional drilling method. STUDY DESIGN: The sample included 7 exfoliated and extracted primary teeth with carious dentin lesions, not reaching the pulp. Each tooth was sectioned longitudinally through the center of the carious lesions into two halves. The teeth were then divided into two groups according to the method of caries removal. Following caries removal, dentin topography and the cut section were examined using the scanning electron microscope. RESULTS: Papacarie produced an irregular, porous, rough and globular dentin appearance. The dentin surfaces were generally free of smear layer, visible bacteria and the dentinal tubules were opened. The dentin cut surfaces showed patent dentinal tubules with open orifices. The drilling method created a smooth and amorphous surface with a continuous smear layer occluding the dentinal tubules. Numerous bacteria were also observed. The cut dentin surfaces showed patent dentinal tubules with their orifices plugged with smear layer. CONCLUSIONS: Papacarie produced a rough and porous surface with partial or complete removal of the smear layer and opened dentinal tubules, while the drill produced a smooth surface with uniform smear layer occluding the dentinal tubules.

In vivo scanning electron microscope assessment of enamel permeability in primary teeth with and without early childhood caries.

BACKGROUND: Over the years, certain primary teeth have been shown to be highly sensitive to dental caries, while others have remained caries-free. It has been hypothesized that this may be attributed to differences in the permeability of the enamel surface. AIM: The aim of the study was to evaluate the hypothesized differences in the permeability of primary tooth enamel in children with and those without Severe Early Childhood Caries (S-ECC) using scanning electron microscopy. MATERIALS AND METHODS: Sixteen children between 3 and 6 years of age were randomly selected and divided into two groups: Group 1, children without S-ECC (n = 8), and Group 2, children with S-ECC (n = 8). In each child, 4 teeth (the maxillary right and left central and lateral incisors) were subjected to evaluation. An impression was made with polyvinylsiloxane impression material, and scanning electron microscopy was used to inspect the negative replicas for droplets. RESULTS: The results indicated higher significance when individual regions (cervical, middle, and incisal thirds) in the two groups were evaluated and compared. Similarly, the overall results showed high statistical significance between S-ECC and non-S-ECC teeth. CONCLUSION: There could be a positive relationship between the permeability of tooth enamel and the development of caries, which needs further research.

Comparative Analysis of Root Dentin Morphology and Structure of Human Versus Bovine Primary Teeth.

This study evaluated the structural and morphological differences between human and bovine primary root canals. Primary human maxillary central incisors (H) (n=9) and primary bovine incisors (B) (n=9) were selected. The roots were sectioned in the vestibular-lingual direction, planed and delimited in cervical, middle, and apical thirds. Tubule density (number of tubules per mm2) and diameter were analyzed by scanning electron microscopy (1,000 and 5,000×) using Image J 1.47 software. Data were submitted to two-way repeated measures ANOVA and Tukey tests (α=0.05). The highest tubule density was observed for B (28.527±1.717 mm2) compared with H (15.931±0.170 mm2) (p<0.01). Regarding root thirds, the cervical third presented a greater tubule density (26.417±11.654 mm2) than the apical third (17.999±5.873 mm2). The diameter of the dentin tubules was not different for cervical (3.50±0.08 µm), middle (3.45±0.30 µm) and apical thirds (3.42±0.33 µm) and substrate (H-3.29±0.14 µm; B-3.63±0.06 µm). It could be concluded that: (1) the radicular dentin structure of human and bovine primary teeth and root thirds differ in terms of the tubule density; (2) the radicular dentin morphology of human and bovine primary teeth and root thirds are similar in terms of the diameter of the dentin tubules.

In vivo microstructural analysis of enamel in permanent and deciduous teeth.

Confocal microscope was used to analyze human enamel from 10 deciduous and 10 permanent teeth. Optically sectioned images were obtained. A more intense autofluorescence was found in primary teeth. This finding might be due to the greater presence of organic substances in deciduous enamel. The mean prism diameter measurement in permanent teeth enamel was 3.150 µm and 2.602 µm in deciduous teeth. The mean prism diameter in deciduous teeth was statistically least. The results indicate that a confocal microscope may be of help in analyzing and defining the microscopic features of human enamel.

Effect of salivary contamination and decontamination on bond strength of two one-step self-etching adhesives to dentin of primary and permanent teeth.

PURPOSE: To evaluate the effects of human saliva contamination and two decontamination procedures at different stages of the bonding procedure on the bond strength of two one-step self-etching adhesives to primary and permanent dentin. MATERIALS AND METHODS: Extracted human primary and permanent molars (210 of each) were ground to mid-coronal dentin. The dentin specimens were randomly divided into 7 groups (n = 15/group/molar type) for each adhesive (Xeno V+ and Scotchbond Universal): no saliva contamination (control); saliva contamination before or after light curing of the adhesives followed by air drying, rinsing with water spray/air drying, or by rinsing with water spray/air drying/reapplication of the adhesives. Resin composite (Filtek Z250) was applied on the treated dentin surfaces. The specimens were stored at 37°C and 100% humidity for 24 h. After storage, shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by exact Wilcoxon rank sum tests. RESULTS: Xeno V+ generated significantly higher SBS than Scotchbond Universal when no saliva contamination occurred. Saliva contamination reduced SBS of Xeno V+, with the reduction being more pronounced when contamination occurred before light curing than after. In both situations, decontamination involving reapplication of the adhesive restored SBS. Saliva contamination had no significant effect on Scotchbond Universal. There were no differences in SBS between primary and permanent teeth. CONCLUSION: Rinsing with water and air drying followed by reapplication of the adhesive restored bond strength to saliva-contaminated dentin.

Bonding Performance of a Multimode Adhesive to Artificially-induced Caries-affected Primary Dentin.

PURPOSE: To investigate the bonding of a new universal adhesive applied using different etching strategies on sound and caries-affected dentin of primary teeth. MATERIALS AND METHODS: Flat dentin surfaces from 50 primary molars were randomly assigned to 10 groups according to substrate (sound dentin [SD] vs caries-affected dentin [CAD] pH cycled for 14 days) and bonding approach (Scotchbond Universal Adhesive: self-etching, vs dry or wet-bonding etch-and-rinse strategies; Adper Single Bond Plus [two-step etch-and-rinse adhesive] and Clearfil SE Bond [two-step self-etching system] as controls). After 24 h of water storage, bonded sticks with cross-sectional areas of 0.8 mm2 were tested for microtensile bond strength (µTBS). Two sticks from each tooth were immersed in silver nitrate solution in order to evaluate nanoleakage (NL) with SEM. The µTBS means were analyzed using two-way ANOVA and Tukey's tests. For NL, the Kruskal-Wallis and Mann-Whitney tests were used (α = 0.05). RESULTS: The influence of the etching strategy on the bonding performance of the universal adhesive was substrate dependent. The self-etching approach resulted in lower µTBS values and higher silver nitrate uptake into hybrid layers for Scotchbond Universal Adhesive on SD, while no difference among experimental groups was observed in CAD. CONCLUSION: It is preferable to use the universal adhesive following either a dry- or wet-bonding etch-and-rinse approach on both sound and caries-affected primary dentin.

Effect of method of caries induction on aged resin-dentin bond of primary teeth.

BACKGROUND: To investigate the influence of chemical and microbiological methods of caries induction on bond degradation of adhesive systems to primary dentin. METHODS: Flat dentin surfaces from 36 primary molars were assigned to three groups (n = 12) according to method to induce caries-affected dentin: (1) control (sound dentin); (2) pH-cycling; and (3) microbiological caries induction model. Teeth were submitted to caries induction for 14 days for both methods, and the sound dentin was stored in distilled water during the same period. Specimens from each experimental group were then randomly reassigned to two subgroups (n = 6) according to the adhesive system tested: two-step etch-and-rinse adhesive (Adper Single Bond 2 - SB) or two-step self-etch system (Clearfil SE Bond - CSEB). Composite buildups were constructed and sectioned to obtain bonded sticks to be subjected to microtensile (µTBS) testing immediately or after 12 months of water aging. The µTBS means were analyzed by three-way repeated measures ANOVA and Tukey's tests (α = 0.05). RESULTS: The µTBS values obtained to artificially-created caries-affected dentin were lower compared with sound dentin, but were not affected by method of caries induction. Water storage for 12 months reduced bond strengths, except to CSEB bonded to sound dentin. CONCLUSION: Chemical and microbiological methods affect similarly the stability of resin-dentin bonds in primary teeth.

Evaluation of different irrigating solutions on smear layer removal of primary root dentin.

AIM: To evaluate the efficacy of ethanolic extract of Salvadora persica (S. persica) and BioPure MTAD (a mixture of a tetracycline isomer, an acid, and a detergent) in removing the intracanal smear layer of primary teeth. MATERIALS AND METHODS: The root canal of 40 extracted human primary anterior teeth were cleaned, shaped and grouped into experimental (n = 30) and control (n = 10). The root canals of the positive (n = 5) and the negative control (n = 5) were irrigated for 3 minutes with 5 ml of 17% ethylenediaminetetraacetic acid (EDTA) or saline respectively. The canals in the experimental groups were irrigated for 3 minutes with 5 ml of 1 mg/ml ethanolic extract of S. persica (n = 15) or BioPure MTAD (n = 15) and then flushed with 2 ml of saline. The presence or absence of smear layer at the coronal and middle portion of each canal were examined under a scanning electron microscope (SEM). RESULTS: A significant difference (p = 0.004) in smear layer removal between S. persica and MTAD at the middle third of the canal was observed. MTAD solution was as effective as 17% EDTA in removing the smear layer. CONCLUSION: MTAD was significantly more effective in smear layer removal than S. persica solution at the middle third of the canal wall. CLINICAL SIGNIFICANCE: Both tested irrigant solutions have the ability to remove the intracanal smear from primary root dentin following cleaning and shaping of the root canal and could be an alternative to EDTA.

Effect of Smear Layers Created by Different Burs on Durability of Self-Etching Adhesive Bond to Dentin of Primary Teeth.

AIM: The aim of this study was to evaluate the effects of a smear layer generated by a high-speed diamond or carbide bur on the durability of microtensile bond strength (µTBS) of a self-etching adhesive to primary dentin. STUDY DESIGN: Flat occlusal dentin surfaces of 105 human primary molars were exposed using 600 grit silicon carbide paper before being divided into 2 groups for further grinding with either a highspeed diamond or carbide bur. Ten prepared dentin surfaces treated by each bur were evaluated for the characteristics of the smear layer using a scanning electron microscope (SEM). Seventy-five specimens from each bur-prepared group were applied with a 2-step self-etching adhesive (Clearfil SE Bond(®)) then built up with a resin composite. Each bonded specimen was sectioned into a 1-mm thick slab and trimmed to a dumbbell shape with a cross-sectional area of approximately 1 mm(2). All slabs were divided into 3 groups (n=25) according to 3 storage times of 24 hrs, 3 months, and 6 months, in distilled water at 37°C. After storage, the µTBS was determined using a universal testing machine. All fracture specimens were prepared for observation of failure modes. Ten bonded specimens of each bur group were prepared for observation of the resin-dentin interface using an SEM. Smear-layer thickness, µTBS, and failure mode distributions were statistically analyzed. RESULTS: The high speed carbide bur created a significantly thinner smear layer than the diamond bur (p < 0.05). Dentin surfaces treated with a high-speed carbide bur generally obtained significantly higher µTBS than the diamond bur group (p < 0.05). The µTBS gradually decreased over time such that specimens stored for 6 months had significantly lower bond strength than those stored for 24 hrs (p < 0.05). Self-etching adhesive created a hybrid layer of the same thickness when prepared with either a carbide bur or diamond bur, but the carbide bur group had longer and more resin tags. CONCLUSION: Highspeed carbide bur groups had a higher µTBS than diamond bur groups for all storage times, and bond strengths decreased over time in both substrate groups. The use of a carbide bur produced a thinner smear layer and therefore is recommended when using this 2-step self-etching adhesive to bond the resin composite to primary dentin.

Flexural and Microtensile Bond Strength of Bulk Fill Materials.

AIM: The aim of this study was to evaluate the flexural and µTBS of bulk-fill materials. STUDY DESIGN: Bulk-fill materials SDR, X-trabase (XTR) and TetricEvoCeramBulkFill (EVO) were used in this study. To test flexural strength, 25x2x2mm samples were prepared and tested with three point bending test. To test the microtensile bond strength (µTBS), two blocks (4x4x4mm) were prepared for each material. In Group A+B, acid-etching was applied to the surface of one of these blocks and no acid-etching was applied in Group B. After applying bonding agent, two blocks were placed into the mold and composite resin (COMP; Tetric N-Ceram) was applied with incremental layering. To evaluate the µTBS of primary dentin, the bulk-fill materials were applied to flat dentin up to 4mm. The new blocks and the teeth were sectioned to obtain sticks and the sticks were loaded in tension until failure. Flexural and microtensile bond strength was calculated based on failure load. RESULTS: The ranking of materials with regards to flexural strength values were SDR>XTR>EVO>COMP,respectively. In GroupA+B, the µTBS values were XTR>SDR>EVO and were XTR>EVO>SDR in GroupB (p>0.05). The µTBS values of these materials to dentin were XTR>EVO>SDR (p>0.05). CONCLUSION: Within the limitations of this study, the use of a bonding agent without acid-etching showed positive interactions between base materials and composite resin and there were no significant differences in µTBS of these materials to dentin.

A spectroscopic and surface microhardness study on enamel exposed to beverages supplemented with lower iron concentrations.

OBJECTIVES: This study aimed to compare the in vitro mineral loss and surface microhardness (SMH) changes in human enamel specimens following supplementation of acidic carbonated beverages with low iron concentrations than when treated without. STUDY DESIGN: 180 enamel blocks each from primary and permanent teeth were prepared and equally subdivided (n=10) for their respective treatments in Group 1 (Coca Cola and Sprite without iron supplementation) and Group 2 (beverages supplemented with 2/5 mmol/L FeSO4.7H2O). Following initial SMH estimation, the blocks were subjected to 3 treatment cycles of 5/20 minute incubation periods, equally interspaced by a 5-min treatment in artificial saliva. The calcium and phosphate released after each cycle were analyzed spectrophotometrically and the final SMH was recorded. The results were tested using student's T test, One-way ANOVA and Kruskal Walli's test (p<0.05). RESULTS: Two and five mmol/L FeSO4.7H2O supplementation produced a highly significant SMH change and calcium and phosphate reduction than when treated without (p<.0005). Both the enamel specimens showed similar patterns of mineral loss and SMH reduction, with pronounced effects in the twenty minute incubation cycles. CONCLUSION: Our results suggest that 2 mmol/L FeSO4.7H2O supplementation to acidic beverages is beneficial in reducing mineral loss and preserving surface microhardness of human enamel.

Bone sialoprotein, matrix metalloproteinases and type I collagen expression after sealing infected caries dentin in primary teeth.

The objective of this in vivo study was to compare the expression of matrix metalloproteinases (MMP-2, MMP-8, MMP-9), type I collagen and bone sialoprotein (BSP) in infected dentin of primary teeth at baseline and after cavity sealing with glass ionomer cement. Dentin samples from 45 primary molars with deep and active carious lesions were collected before (baseline sample) and after cavity sealing (60-day sample). The samples were fixed, demineralized and processed for immunohistochemistry assays. Monoclonal antibodies were used for the localization of the cited antigens with an avidin-biotin method. Digital images of the sections were captured and analyzed with ImageJ software. The mean intensity of RGB channels in the images was obtained and compared using Student's t test (α = 0.05). The expression of the MMPs, type I collagen and BSP increased after sealing, but statistical differences were observed only for MMP-8, type I collagen and BSP. MMP-2 and MMP-9 were more concentrated around dentin tubules; MMP-8 and collagen showed strong expression throughout the organic matrix; BSP exhibited strong expression both in the matrix and around dentin tubules. The increased expression of the enzymes investigated 60 days after cavity sealing suggests that they are not related with disease progression but with the healing process of dentin.

Effect of cariogenic challenge on bond strength of adhesive systems to sound and demineralized primary and permanent enamel.

PURPOSE: To evaluate the effect of cariogenic challenge on the bond strength of adhesive systems to sound and artificially demineralized enamel of primary and permanent teeth. MATERIALS AND METHODS: Eighty molars (40 primary, 40 permanent) were randomly assigned to 16 groups (n = 5) according to the type of tooth (primary [PRIM] or permanent [PERM]), enamel condition (sound [S] or demineralized [DEM]), treatment after the restorative procedure (control [C] or cariogenic challenge [pH]), and adhesive system (Adper Single Bond [SB] or Clearfil SE Bond [SE]). Teeth from the DEM group were subjected to cariogenic challenge by pH cycling prior to restorative procedures and pH group specimens were subjected to cariogenic challenge before the microshear test. One of two adhesive systems was applied to the flat enamel surfaces and composite cylinders (0.45 mm2) were built. The microshear bond test was performed. The data (MPa) were subjected to ANOVA and Tukey's test (α = 0.05). RESULTS: No statistically significant differences were detected between the adhesive systems. The S groups exhibited higher bond strength values than the DEM groups, as did C groups compared to pH groups. PERM groups also had higher bond strength values than PRIM groups, excluding PRIM S and PERM S, which had similar values. CONCLUSION: The bond strength to demineralized enamel of primary teeth was lower than to the demineralized enamel of permanent teeth. Cariogenic challenge negatively influenced enamel bond strength, regardless of the type of tooth and adhesive system.

Ferric sulphate alterations on primary dentin and the adhesive interface.

PURPOSE: The purpose of this study was to test the hypothesis that the pulp medication ferric sulphate (FS) may remain on primary dentin, affecting its microchemical structure and the bond strength of adhesives to primary dentin. MATERIALS AND METHODS: The effects of FS and pre-bonding conditioning (37% phosphoric acid [PA] for 15 s or a self-etching primer, with or without the use of 2% chlorhexidine [CHX]) on FS-treated primary dentin were characterized using optical microscopy with Masson's and Perls' stains, variable-pressure SEM/energy-dispersive x-ray spectroscopy (VP-SEM/EDS), Fourier transform infrared spectroscopy (FT-IR), and x-ray diffraction. Ferric sulphate was applied for 30 s or 1 h for microchemical analysis. The adhesive interface and the bond strength were studied by VP-SEM/EDS and the µTBS test (1 mm2 bars, crosshead speed 0.5 mm/min), respectively. The study groups were: etch-and-rinse (E&R, Excite) adhesive (group 1); FS+E&R (group 2); FS+CHX+E&R (group 3); self-etching (SE, Adper Scotchbond) adhesive (group 4); FS+SE (group 5); FS+CHX+SE (group 6). RESULTS: Ferric sulphate application produced demineralization, gypsum formation, and adsorption of Fe on the dentin surface, and it modified the collagen structure of primary dentin. There were no effects of FS on bond strength of the tested etch-and-rinse adhesive system. FS slightly reduced the bond strength between the primary dentin and the SE adhesive, and the values were not restored by CHX (group 4 = 17.58 ± 5.52 MPa > group 5 = 14.26 ± 7.08 MPa = group 6 = 13.96 ± 4.87 MPa). CONCLUSIONS: Ferric sulphate alters the microchemical structure of primary dentin and can impair the adhesive strength of some self-etching adhesives.