Teaching pulpectomy in paediatric dentistry: A national cross-sectional survey of dental schools in Brazil.

BACKGROUND: Pulpectomy is used to treat primary teeth with irreversibly inflamed or necrotic pulp tissue. There is, however, a lack of consensus on clinical protocols for teaching pulpectomy at dental schools. AIM: To determine what faculty members at Brazilian dental schools are teaching about pulpectomy in primary teeth. DESIGN: A cross-sectional, observational study was conducted using a 39-question survey available via the Google Forms® platform. A snowball sampling strategy was used for recruitment. Invitations to participate were sent via e-mail, WhatsApp® and Instagram®. The data were analysed descriptively. RESULTS: A total of 177 (58.4%) responses were obtained. Most faculty members recommended the use of Kerr hand files (66.1%), and 1% sodium hypochlorite was the most common choice for the irrigating solution (35.3%). Iodoform pastes were the first choice of faculty members (41.6%), and 60.5% of the faculty members recommended composite resin as the definitive restoration. CONCLUSION: Similarities were found in the teaching of pulpectomy for primary teeth among faculty members at dental schools in Brazil.

Surfactin application for a short period (10/20 s) increases the surface wettability of sound dentin.

The aim of this study was to evaluate the effect of spreading the lipopeptide surfactin, for short time (10/20 s), on dentin wettability. Study groups were surfactin: 2.8; 1.4; 0.7; 0.35; and 0.175 mg/mL and a control group that received no treatment. Dentin discs (4 mm height) were prepared and polished with 600-grit SiC paper. Contact angle determinations were carried out after microbrush spreading of surfactin on dentin specimens for, respectively, 10 and 20 s. Excess liquid was removed, and after 60 s, the specimens were analyzed in a goniometer using the sessile drop method to measure the contact angle. Results were analyzed by two-way ANOVA (concentration × time) and t student, with α = 0.05. Lower contact angles were obtained for surfactin (0.7 mg/mL) spread for 10 s. However, no statistical difference was observed for surfactin (2.8 mg/mL) applied during 20 s. Higher contact angles were observed for surfactin (0.7 mg/mL) spread for 20 s. In conclusion, dentin wettability is dependent on spreading time and surfactin concentration.

Impact of the intermediary layer on sealant retention: a randomized 24-month clinical trial.

OBJECTIVES: The aims of this study were to assess long-term impact of tooth eruption stages (ES) on sealant retention on occlusal surfaces previously coated with intermediary bonding layer and to determine caries prevention. MATERIALS AND METHODS: Sixty-five school children were selected (aged 6-10 years), with four non-carious permanent first molar in different ES (OP (operculum present), ME (marginal edge), CE (completely erupted)). Split-mouth and single-blind study design was used. The teeth (260) were randomly selected according to treatment (sealant/technique): F (Fluroshield), H (Helioseal Clear Chroma), SF (Single Bond + F), EH (Excite + H). Sealant retention, marginal integrity, discoloration, and caries prevention were assessed after 6, 12, 18, and 24 months by calibrated examiner (Spearman = 0.91) using visual inspection. Data were submitted to the Cox proportional hazard model (survival analysis) and Likelihood ratio χ 2 test (correlation), p ≤ 0.05. RESULTS: At baseline, ES was 20 % in OP, 54 % in ME, and 26 % in CE. There was no significant difference on sealant retention between the treatments (p = 0.2774). However, significant differences were found regarding the ES on sealant retention (p = 0.0041). The CE stage showed the highest retention survival rate during the 24 months. The overall sealant prevention average was found to be about 99.4 % and showed no difference between the groups. CONCLUSIONS: Eruption stages affect sealant retention irregardless of the intermediate layer and type of sealant. However, there was caries prevention on tooth occlusal surfaces after 24 months, regardless of treatment. CLINICAL RELEVANCE: Sealing is recommended to prevent occlusal caries of newly erupted teeth in high-caries-risk patients. However, its application is critical on moisture limited control surfaces independently of sealer material and technique.

Influence of adhesive cementation systems on the bond strength of relined fiber posts to root dentin.

STATEMENT OF PROBLEM: Glass fiber post cementation procedures have undergone significant development. Relining the post with composite resin is a technique that aims to reduce resin cement thickness and consequently problems inherent to polymerization. Evidence is sparse regarding the efficacy of bonding procedures at increasing depths (from cervical to apical) using different adhesive cementation techniques. PURPOSE: The purpose of this in vitro study was to evaluate the push-out bond strength (PBS) of composite resin relined glass fiber posts cemented to bovine root dentin using different adhesive cementation protocols. MATERIAL AND METHODS: Eighteen bovine teeth (n=6) were embedded in polystyrene resin blocks, and the crowns were sectioned leaving a root portion of 20 mm in length. Root canals were prepared using rotary instruments provided by the post manufacturer (Whitepost DC #1), resulting in a uniform root canal preparation. The root canals were lubricated with a water-soluble glycerin gel. Silane (Prosil) was applied and the posts relined with a microhybrid composite resin (Filtek Z100) to conform to the root canal anatomy. Three adhesive cementation protocols were evaluated: a 3-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose) in combination with a dual polymerizing resin cement (RelyX ARC); a universal adhesive system (Scotchbond Universal) associated with a dual polymerizing resin cement (RelyX Ultimate); and a self-adhesive dual polymerizing resin cement (RelyX Unicem 2). The roots were sectioned, resulting in four 2-mm segments at 4 different depths (cervical to apical) and evaluated by the PBS test, using a universal testing machine (Instron 4411) at 0.5 mm/min, until failure. Interfaces were evaluated by scanning electron microscopy, and failures were classified as cohesive failure in composite resin, cohesive failure in cement, cohesive failure in root dentin, adhesive failure, or mixed. Data were analyzed by 2-way split-plot ANOVA and the Tukey post hoc test (α=.05). RESULTS: No statistical differences were found for PBS when different cementation systems were compared (P=.253). Increased depths resulted in reduced PBS values for all cementation protocols evaluated (P<.001). CONCLUSIONS: Regardless the cementation system used, the lowest PBS values were at the apical region of resin relined glass fiber posts bonded to root dentin. Furthermore, the highest PBS is observed at the cervical portion of root dentin.

Effectiveness of casein phosphopeptide-amorphous calcium phosphate and lysozyme, lactoferrin, and lactoperoxidase in reducing Streptococcus mutans counts in dentinal caries.

This study compared the capacity of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to that of a combination of lysozyme, lactoferrin, and lactoperoxidase (LLL) in root canal disinfectant for reducing the Streptococcus mutans counts from dentinal caries. Forty human permanent third molars were selected, and flat dentin surfaces were created. Carious lesions were induced using a microbiological model. The specimens were randomly divided into 2 groups (n = 20) according to the type of agent used: group 1, CPP-ACP; group 2, LLL. The S mutans counts were performed before application and after the first, second, and third applications of the agents. The duration of each application was 3 minutes. Carious dentin specimens were homogenized, diluted, and seeded onto mitis salivarius-bacitracin plates for viable counts of S mutans. Results showed that there was no significant reduction in the number of S mutans in group 1 after the applications of CPP-ACP (P > 0.05). In group 2, a significant reduction of S mutans was observed after the third application of LLL (P < 0.01). These results indicate that 3 applications of LLL enzymes can be used to reduce the number of S mutans in dentinal caries lesions.

Bond Strength of Experimental Low-viscosity Resin Materials to Early Enamel Caries Lesions: Effect of Diluent/Solvent Addition.

PURPOSE: To evaluate the effect of different concentrations of monomers and solvents/diluents on the microtensile bond strength (µTBS) bond strength of experimental low-viscosity resins (infiltrants) to enamel caries-like lesions (ECLL). MATERIALS AND METHODS: Flat enamel blocks obtained from sound human third molars were submitted to ECLL formation and randomly distributed into 9 groups (n = 10): G1: TEG-DMA 100%; G2: TEG-DMA 80%, ethanol 20%; G3; TEG-DMA 80%, HEMA 20%; G4: TEG-DMA 75%, UDMA 25%; G5: TEG-DMA 60%, UDMA 20%, ethanol 20%; G6: TEG-DMA 60%, UDMA 20%, HEMA 20%; G7: TEG-DMA 75%, bis-EMA 25%; G8: TEG-DMA 60%, bis-EMA 20%, ethanol 20%; G9: TEG-DMA 60%, bis-EMA 20%, HEMA 20%. After etching with 37% phosphoric acid for 60 s, experimental infiltrants were actively applied and photocured for 60 s, then stored in 100% humidity (24 h, 37°C). Hourglass-shaped specimens were obtained and the µTBS test performed (MPa). The fracture patterns were assessed by SEM. Data were submitted to two way-ANOVA and Tukey's tests (α = 0.05). RESULTS: The highest µTBS value was observed for G4 (TEG-DMA/UDMA, 19.18 MPa) and the lowest for G5 (TEG-DMA/UDMA/ethanol, 9.00 MPa). A significant decrease in µTBS was observed for all groups containing ethanol (G2, G5, and G8). The addition of HEMA did not affect µTBS values. Most groups showed a high frequency of mixed failure between infiltrant and enamel. CONCLUSION: The addition of bis-EMA or UDMA to TEG-DMA-based infiltrants did not improve bond strength to carious enamel. The ethanol addition negatively affected the bonding strength of infiltrants to enamel caries-like lesions, regardless of the resin matrix composition of the infiltrant.

Effect of Different In Vitro Aging Methods on Color Stability of a Dental Resin-Based Composite Using CIELAB and CIEDE2000 Color-Difference Formulas.

PURPOSE: To evaluate the effect of different in vitro aging methods on color change (CC) of an experimental dental resin-based composite using CIELAB (ΔEab ) and CIEDE2000 (ΔE00 ) color-difference formulas. MATERIALS AND METHODS: The CC was evaluated with a spectrophotometer (CM700d, Konica Minolta, Tokyo, Japan) according to the CIE chromatic space. Disk-shaped specimens (Φ = 5 × 1 mm thick) (N = 10) were submitted to different in vitro aging methods: 30 days of water aging (WA); 120 hours of ultraviolet light aging (UVA); or 300 hours of an accelerated artificial aging (AAA) method with cycles of 4 hours of UV-B light exposure and 4 hours of moisture condensation to induce CC. The temperature was standardized at 37°C for all aging methods. CC was evaluated with ΔEab and ΔE00 formulas. Differences in individual Lab coordinates were also calculated. Data for the individual color parameters were submitted to one-way analysis of variance and Tukey's test for multiple comparisons (α = 0.05). RESULTS: All in vitro aging methods tested induced CC, in the following order: WA: ΔEab = 0.83 (0.1); ΔE00 = 1.15 (0.1) < AAA: ΔEab = 5.64 (0.2); ΔE00 = 5.01 (0.1) < UVA: ΔEab = 6.74 (0.2); ΔE00 = 6.03 (0.4). No changes in L* or a* coordinates were ≥1; the methods with UV aging showed a yellowing effect due a large positive change in b*. CONCLUSIONS: All in vitro aging methods tested induced a CC, but to different extents. Changes in color followed similar trends, but with different absolute values when calculated with the CIELAB and the CIEDE2000 formulas. CLINICAL SIGNIFICANCE: Establishing the efficacy of different artificial aging methods and differences between color change using CIELAB and CIEDE2000 formulas are important to standardize color stability evaluations and facilitate the comparison of outcomes from different studies in the literature.

In vitro effect of S. mutans biofilm on fluoride/MDPB-containing adhesive system bonded to caries-affected primary dentin.

PURPOSE: To evaluate the effect of storage in S. mutans culture or water on the durability of fluoride and MDPB-containing adhesive system on artificial caries-affected primary dentin. METHODS: Dentin flat surfaces of primary molars were submitted to artificial caries development using S. mutans biofilm. CAPD cavities were restored with Adper Scotchbond Multi-Purpose (SBM) or Clearfil Protect Bond (CPB) and they were serially sectioned into sticks (1 mm2 cross-sectional area) and stored in S. mutans biofilm for 3 days, in deionized water for 3 months and afterwards subjected to microtensile bond strength (µTBS) test. A control group was submitted to immediate TBS testing. Two-way ANOVA and Tukey's tests were used. Failure sites were observed by SEM and classified as cohesive (dentin or resin) and adhesive failures. RESULTS: The control group showed the highest µTBS values (MPa) for both SBM (25.2 ± 8.5) and CPB (15.6 ± 6.1) adhesive systems. A significant decrease in µTBS values after S. mutans biofilm and water storage was observed for SBM (18.7 ± 5.7 and 17.4 ± 4.1, respectively) and CPB (13.9 ± 5.2 and 13.7 ± 4.8, respectively), but no difference was found between them. The highest percentage of adhesive failure was observed for all groups. However, cohesive failure in dentin was observed in a higher percentage for SBM than CP.

Exploring the role of flavonoids in caries-affected dentin adhesion: A comprehensive scoping review.

OBJECTIVES: The aim of this scoping review was to evaluate the available scientific evidence regarding the use of flavonoids in the treatment of caries-affected dentin focusing on bonding to dentin. METHODS: A comprehensive literature search was performed in five databases from March 2022 and updated in April 2023: PubMed, EMBASE, Scopus, Web of Science, and Scielo. Additionally, the references of included studies were manually searched. Gray literature was excluded from the review. STUDY SELECTION: Inclusion criteria included in vitro, in situ, and in vivo studies (animal or human) published in English. Abstracts, reviews, case reports, book chapters, doctoral dissertations, guidelines, and studies using pure plant extracts were excluded. Data collected from the selected studies were summarized and subjected to narrative and descriptive analysis. Out of the 91 studies identified, only 16 studies met the inclusion criteria. RESULTS: The review analyzed eight different flavonoids (hesperidin, galardin, proanthocyanidin, genipin, quercetin, naringin, epigallocatechin-3-gallate, and other catechins subtypes) used as pretreatment or loaded into adhesive systems, primers, and phosphoric acid. The use of flavonoids improved the mechanical properties of the materials and modified the biological properties of the dentin, reducing collagen loss by the inhibition of proteolytic activity of matrix metalloproteinases (MMPs). CONCLUSIONS: Based on the findings of this scoping review, it can be concluded that the use of flavonoids as pretreatment or incorporation into dental materials preserves collagen in the hybrid layer, inhibiting the MMPs activities, modifying the collagen fibrils of the dentin matrix and improving the mechanical properties of the dental adhesive systems. Therefore, it represents a promising approach for promoting dentin biomodification. This can result in more stable bonding of adhesive restorations to caries-affected dentin.

Thermo-mechanical degradation of composite restoration photoactivated by modulated methods-a SEM study of marginal and internal gap formation.

OBJECTIVE: To evaluate the influence of thermal-mechanical degradation on superficial and internal gap formation of composite restorations photoactivated using modulated methods. MATERIALS AND METHODS: An experimental composite was prepared using a resin matrix containing 65wt% Bis-GMA and 35wt% TEGDMA. Camphorquinone (0.5wt%) and dimethylaminoethyl-methacrylate (0.5wt%) were dissolved in the resin as a photo-initiator system and 65wt.% silanized glass fillers were added to the matrix. Ground buccal surfaces of bovine lower incisors were used to make 160 preparations (3 mm × 3 mm × 2 mm in depth). An adhesive system (Adper Single Bond 2) was applied and the specimens were assigned into 16 groups (n = 10), according to the photoactivation method [high intensity (HI), low intensity (LI), soft-start (SS) and pulse-delay (PD)] and the degradation protocol [(control/no degradation; thermal cycling (TC); mechanical loading (ML); thermo-mechanical loading (TC+ML)]. Marginal and internal interfaces of bonded restorations were replicated in epoxy resin and analyzed by SEM. Gaps were expressed as a percentage of the total length of the margins. Data were submitted to 2-way ANOVA and Tukey's test (α = 0.05). RESULTS: For the control group no significance was noted among the photoactivation methods. TC had no effect in gap formation. ML and TC+ML increased the incidence of superficial gaps for both HI and SS groups as well as increased the internal gaps for all groups. CONCLUSION: Although photoactivation methods do not influence gap formation at first, composite restoration photoactivated by low intensity or modulated methods showed improved resistance to thermo-mechanical degradation. Mechanical loading is determinant for interfacial degradation of composite restorations, while thermal cycling has no effect on gap formation.

Effect of artificial accelerated aging on the optical properties and monomeric conversion of composites used after expiration date.

This study sought to evaluate how artificial accelerated aging (AAA) affected color stability (ΔE), opacity (ΔOP), and degree of conversion (DOC) for 3 composite materials (Tetric Ceram, Tetric Ceram HB, and Tetric Flow) used both 180 days before and 180 days after their expiration dates. To evaluate the materials' optical properties, 10 specimens of each composite-5 prior to expiration and 5 after the materials' expiration date-were made in a teflon matrix. After polishing, the specimens were submitted to initial color and opacity readings and submitted to AAA for 384 hours; at that point, new readings were taken to determine ΔE and ΔOP. To evaluate monomeric conversion evaluation, 6 specimens from each composite and expiration date-3 prior to AAA and 3 after-were submitted to DOC analysis. Results of the 2-way ANOVA and Bonferroni's tests (P < 0.05) demonstrated that all composites had ΔE values above the clinically acceptable level (ΔE ≥ 3.3). When expiration dates were compared, only Tetric Flow showed a statistically significant difference (P < 0.05). Regardless of the expiration date, ΔOP values for all composites increased after AAA, but not significantly (P > 0.05). The expired Tetric Flow had the highest DOC values (71.42% ± 4.21) before AAA, significantly different than that of the other composites (P > 0.05). It was concluded that both expiration date and AAA affected the properties of the composites tested.

The Self-assembling peptide P11-4 influences viability and osteogenic differentiation of stem cells of the apical papilla (SCAP).

OBJECTIVE: To analyze the effect of P11-4 self-assembly peptide on cell viability and osteogenic capacity of SCAPs through mineral deposition and gene expression of osteogenic markers. METHODS: SCAPs were seeded in contact with P11-4 (10 µg/ml, 100 µg/ml and 1 mg/ml) solution. Cell viability was evaluated using a colorimetric assay MTT: 3-(4,5-dimethyl-thiazolyl-2)-2,5- diphenyltetrazolium bromide) in an experimental time of 24, 48 and 72 h (n = 7). Mineral deposition and quantification provided by the cells was tested using the Alizarin Red staining and Cetylpyridinium Chloride (CPC), respectively, after 30 days (n = 4). Gene expression of Runt-related transcription factor 2 (RUNX2), Alkaline phosphatase (ALP) and Osteocalcin (OCN) was quantified using quantitative polymerase chain reaction (RT-qPCR), at 3 and 7 days with Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as the housekeeping gene, and relative gene expression was measured using the ΔΔCq method. Data were analyzed using Kruskall-Wallis followed by multiple comparisons, and T-test for gene expression with α=0.05. RESULTS: All tested concentrations (10 µg/ml, 100 µg/ml and 1 mg/ml) were not cytotoxic at time 24 and 48 h. After 72 h, a slight decrease in cell viability was observed for the lowest concentration (10 µg/ml). The concentration of 100 µg/ml P11-4 showed the highest mineral deposition. However, qPCR analysis of P11-4 (10 µg/ml) showed upregulation of RUNX2 and OCN at 3 days, with downregulation of ALP at 3 and 7d CONCLUSION: P11-4 did not affect cell viability, induced mineral deposition in SCAPs, and upregulated the expression of RUNX2 and OCN genes at 3 days, while downregulating ALP expression at 3 and 7 days. CLINICAL SIGNIFICANCE: Based on the results obtained in this study it can be stated that self-assembling peptide P11-4 is a potential candidate to induce mineralization on dental stem cells for regenerative purposes and also for a clinical use as a capping agent without compromising the cells health.

Effect of Biosilicate® Addition on Physical-Mechanical and Biological Properties of Dental Glass Ionomer Cements.

This study investigated the influence of incorporating Biosilicate® on the physico-mechanical and biological properties of glass ionomer cement (GIC). This bioactive glass ceramic (23.75% Na2O, 23.75% CaO, 48.5% SiO2, and 4% P2O5) was incorporated by weight (5%, 10%, or 15%) into commercially available GICs (Maxxion R and Fuji IX GP). Surface characterization was made by SEM (n = 3), EDS (n = 3), and FTIR (n = 1). The setting and working (S/W time) times (n = 3) and compressive strength (CS) were analyzed (n = 10) according to ISO 9917-1:2007. The ion release (n = 6) was determined and quantified by ICP OES and by UV-Vis for Ca, Na, Al, Si, P, and F. To verify cell cytotoxicity, stem cells from the apical papilla (SCAP) were exposed to eluates (n = 3, at a ratio of 1.8 cm2/mL) and analyzed 24 h post-exposure. Antimicrobial activity against Streptococcus mutans (ATCC 25175, NCTC 10449) was analyzed by direct contact for 2 h (n = 5). The data were submitted for normality and lognormality testing. One-way ANOVA and Tukey's test were applied for the working and setting time, compressive strength, and ion release data. Data from cytotoxicity and antimicrobial activity were submitted for Kruskal-Wallis' testing and Dunn's post hoc test (α = 0.05). Among all experimental groups, only those with 5% (wt) of Biosilicate® showed better surface quality. Only M5% showed a comparable W/S time to the original material (p = 0.7254 and p = 0.5912). CS was maintained for all Maxxion R groups (p > 0.0001) and declined for Fuji IX experimental groups (p < 0.0001). The Na, Si, P, and F ions released were significantly increased for all Maxxion R and Fuji IX groups (p < 0.0001). Cytotoxicity was increased only for Maxxion R with 5% and 10% of Biosilicate®. A higher inhibition of S. mutans growth was observed for Maxxion R with 5% of Biosilicate® (less than 100 CFU/mL), followed by Maxxion R with 10% of Biosilicate® (p = 0.0053) and Maxxion R without the glass ceramic (p = 0.0093). Maxxion R and Fuji IX presented different behaviors regarding Biosilicate® incorporation. The impacts on physico-mechanical and biological properties were different depending on the GIC, but therapeutic ion release was increased for both materials.

Effects of water storage on bond strength and dentin sealing ability promoted by adhesive systems.

PURPOSE: To evaluate the dentin bond strength (BS) and sealing ability (SA) promoted by adhesive systems after 24 h or 6 months of water storage. MATERIALS AND METHODS: The tested adhesive systems were: one three-step etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, SBMP) and three single-step self-etching systems (Adper Easy Bond, Bond Force, and G-Bond Plus). Bovine incisors were used for both evaluations, BS (n = 11) and SA (n = 5). To examine BS, the buccal surface was ground with SiC paper to expose a flat dentin surface. After adhesive application, a block of resin composite was incrementally built up over the bonded surface and sectioned into sticks. These bonded specimens were subjected to microtensile bond strength testing after 24 h and 6 months of water storage using a universal testing machine. For SA analysis, enamel was removed from the buccal surfaces. The teeth were connected to a device to measure the initial SA (10 psi), and the second measurement was taken after treating dentin with EDTA. Afterwards, the adhesive systems were applied to dentin and the SA was re-measured for each adhesive after 24 h and 6 months of water storage. The SA was expressed in terms of percentage of dentinal sealing. BS and SA data were submitted to two-way ANOVA and Tukey's test (α = 0.05). RESULTS: All adhesives showed a reduction of SA after 6 months of water storage. The SA promoted by self-etching adhesives was higher than that of SBMP. No adhesive system showed a reduction of the BS after 6 months. CONCLUSION: Sealing ability was affected by water storage, while no changes in microtensile bond strength were observed after 6 months of water storage. The single-step self-etching systems showed greater sealing ability than did SBMP, even after 6 months of storage in water.

Biomechanical degradation of the nano-filled resin-modified glass-ionomer surface.

PURPOSE: To evaluate in the laboratory the roughness (Ra) and micromorphology surface of the nanofilled resin-modified glass-ionomer (Ketac N100) subjected to biomechanical degradation, compared to Vitremer, Ketac Molar Easymix and Fuji IX. METHODS: Specimens obtained from the ionomers were divided into two storage groups (n = 10): relative humidity and S. mutans biofilm (biodegradation). After 7 days, Ra values and micrographs were obtained. Then, the brushing abrasion test (mechanical degradation) was conducted with dentifrice slurry (three-body) and the specimens were reassessed. Data were submitted to repeated measures three-way ANOVA and Tukey tests (P < 0.05). RESULTS: There was significant interaction among the factors: material, storage and abrasion (before/after). Vitremer showed similar Ra values between storage groups, while the other materials presented higher Ra values after biodegradation test. Concerning biomechanical challenge, Ketac N100 presented the lowest Ra values. Ketac Molar Easymix and Fuji IX presented undesirable roughening of their surfaces under the detrimental conditions tested. The eroded aspect after biodegradation with filler exposure after mechanical degradation was evident.

In vitro long-term degradation of aesthetic restorative materials in food-simulating media.

OBJECTIVE: The aim of this study was to evaluate the effect of long-term food-simulating media storage on degradation of restorative materials through roughness measurements. MATERIALS AND METHODS: Sixty cylindrical specimens of each material (Filtek Z250, Esthet X, Filtek Flow, Dyract AP and Vitremer) were prepared, stored for 24 h, and polished. The surface roughness analysis was conducted using Surfcorder (SE1700) roughness-measuring instrument. Three traces were recorded on each specimen at three different locations. The specimens were randomly distributed into five groups (n = 12) according to the storage media: (water, ethanol, Coca-Cola®, citric acid and lactic acid). Roughness measurements were recorded after 1 week, 1, 3 and 6 months. The storage solutions were weekly changed. Data were submitted to ANOVA and Tukey test (p < 0.05). RESULTS: There was no significant increase on roughness means for Filtek Z250, Filtek Flow and Vitremer over time, regardless the storage media. Significant increase on surface roughness was observed for Esthet X after 1 month of storage in Coca-Cola® and after 3 months of storage in citric acid and for Dyract AP after 6 months in water. There were no significant differences on surface roughness between resin composites and compomer. Resin-modified glass ionomer showed a significantly higher surface roughness mean than the other materials. CONCLUSIONS: Food-simulating media affects the surface roughness of the materials. Biodegradation is material-, solution- and time-dependent.

Self-assembly peptide P11-4 induces mineralization and cell-migration of odontoblast-like cells.

OBJECTIVES: Self-assembling peptide P11-4 is amphiphilic and pH-triggered, effective on repairing early enamel carious lesions and dentin remineralization. However, P11-4 effects on dentin biomineralization and repair ability remain unexplored. Thus, cytocompatibility and effectiveness of P11-4 on inducing mineralization and migration of odontoblast-like cells (MDPC-23) were investigated. METHODS: MDPC-23 were seeded in contact with P11-4 (0.5 and 1 µg/ml), Dentin Matrix Protein 1 (DMP1 0.5 and 1 µg/ml) or Calcium hydroxide (Ca(OH)2 100 µg/ml) solutions. Cell viability was verified using MTT (n = 6/group). Mineral deposition was tested using Alizarin Red (n = 4/group). Cell migration was assessed by light microscopy (n = 2/group). MTT and Alizarin Red data were compared using Kruskal-Wallis and Mann-Whitney (α=0.01). RESULTS: P11-4 (0.5 and 1 µg/ml) and DMP1 (0.5 and 1 µg/ml) resulted the highest cell viability; Ca(OH)2 presented the lowest. 1 µg/ml DMP1 and 1 µg/ml P11-4 promoted the highest mineral deposition. Ca(OH)2 presented lower values of mineral deposits than DMP1 1 µg/ml (p < 0.01), but similar to P11-4 1 µg/ml. P11-4 and DMP1 at 0.5 µg/ml induced lesser mineral precipitation than P11-4 and DMP1 at 1 µg/ml (p < 0.01), with no difference to Ca(OH)2. All materials stimulated cell migration, however, lower concentrations of DMP1 and P11-4 demonstrated a higher migration potential. CONCLUSION: P11-4 did not affect cell viability, induces mineral deposition and MDPC-23 migration like DMP1. CLINICAL SIGNIFICANCE: Self-assembling peptide P11-4 does not affect the cell viability and induces mineral deposition comparable to native protein involved in biomineralization. Combined with its ability to bind type I collagen, P11-4 is a promising bioinspired molecule that provides native-tissue conditions and foster further studies on its ability to form dentin bridges in pulp-capping strategies.

TiO2 nanotube-containing glass ionomer cements display reduced aluminum release rates.

Titanium dioxide nanotubes (TiO2-nts) were incorporated into a glass ionomer cement (GIC) with improved mechanical properties and antibacterial activity. The aims of the present in vitro study were to define the elemental characterization, aluminum (Al) release rate, and initial working time for GIC reinforced with TiO2-nts, in an experimental caries model. TiO2-nts were incorporated into GIC powder components at 5% by weight, and compared with unblended GIC. Experimental approaches used energy-dispersive spectrometry (EDS), atomic absorption spectrophotometry (AAS), and brightness loss to define surface element properties, Al release rates, and initial working time, respectively. Statistical analysis was performed by 2-way ANOVA, Tukey's test, generalized linear models, and Student's t test (a = 0.05). EDS data analysis revealed that TiO2-nts incorporated into GIC had no significant impact on the typical elemental composition of GICs in an in vitro caries model. Regarding the demineralizing solution, GIC with TiO2-nt significantly decreased the Al release rate, compared with the control group (p < 0.0001). Moreover, TiO2-nt incorporated into GIC did not alter the initial working time of the material (p > 0.05). These findings add information to our scientific body of knowledge concerning the potential impact of TiO2-nt on the performance of conventional GICs.

Influence of different enamel substrates on microtensile bond strength of sealants after cariogenic challenge.

PURPOSE: To evaluate the microtensile bond strength (µTBS) of resin sealer on enamel substrates after cariogenic challenge. MATERIALS AND METHODS: Enamel blocks were obtained from human third molars and randomly divided into 6 groups (n = 10) according to enamel substrates (S: sound, CL: caries-like lesion, or CLTF: caries-like lesion + topical fluoride application) and sealant material (F: FluroShield, or H: Helioseal Clear Chroma). Sealants were placed on enamel surfaces, stored in 100% humidity (24 h, 37°C), and longitudinally sectioned into hourglass shapes. According to the groups, pH cycling was applied and the µTBS test was performed. The fracture patterns were assessed by SEM. RESULTS: Regarding substrates, the highest µTBS values in MPa were observed for CLTF enamel (26.0 ± 7.6), followed by S (22.0 ± 7.4) and CL (15.5 ± 4.9). A significant interaction was found between material and pH cycling (p = 0.0395). F (23.9 ± 7.6) showed higher µTBS values than H (18.3 ± 7.5) when submitted to pH cycling. The majority of samples presented mixed failure. CONCLUSIONS: Enamel substrate significantly affected µTBS, with the highest values for remineralized caries-like enamel lesions. Furthermore, µTBS values were dependent on both materials and pH cycling.

CHX Stabilizes the Resin/demineralized Dentin Interface.

The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on microtensile bond strength (µTBS) between an adhesive system and under 3 dentin conditions. For that, this study evaluated the adhesive interface at initial, after 6 months and 1 year of storage. Forty-eight human third molars were prepared and randomly divided into 3 groups, according to dentin substrates: sound dentin (Sd), caries-infected dentin (Ci) and caries-affected dentin (Ca). The groups were subdivided into two according to the dentin pre-treatment: application of 2% CHX or without pre-treatment (control). The dentin surfaces were etched with 35% phosphoric acid gel and bonded with Adper Single Bond 2 (3M ESPE) adhesive system according to manufacturer's instructions. Subsequently, the specimens were stored in deionized water at 37°C for 24h, 6 months and 1 year. Two additional teeth were used to analyze the bonding interfaces by SEM. Data was submitted to three-way ANOVA in a split plot design and Tukey's test (α = 0.05). The results showed that Ci decreased µTBS values when compared to Ca and Sd, regardless storages time or treatment. Stored samples for 6 months and 1 year decreased the µTBS for the control group, but no difference was found between storages time for the CHX group. As a conclusion, the 2% CHX application after etching showed improved dentin bond strength in the storage time, regardless of the substrates evaluated.