Development of toothpaste formulations containing mineral clays as abrasive agents and their effects on the physical properties of dental enamel

To assess the physical properties and topographical aspect of dental enamel's surface microhardness (KHN), surface roughness (Ra), and color parameters CIELAB (∆Eab*), CIEDE 2000 (∆E00), and whiteness index for dentistry (∆WID) after toothbrushing with experimental toothpaste formulations with the following mineral clay types: kaolin, Sparclay SGY, and Tersil CGY used as abrasive component. Scanning electron microscopy (SEM) was performed for topographical analyses purposes. A total of 96 bovine incisors were used in the experiment. They were divided into eight experimental groups (n = 12), namely: NC-negative control (no treatment), CT12-Colgate Total 12®, CMP-Colgate® Máxima Proteção Anticáries, K-kaolin experimental toothpaste, SGY-Sparclay SGY experimental toothpaste; CGY-Tersil CGY experimental toothpaste, SD-SiO2 experimental toothpaste, and CC-CaCO3 experimental toothpaste. All samples were subjected to mechanical brushing protocol with 5000 cycles and kept in artificial saliva with daily exchanges. KHN was analyzed through the mixed linear model for repeated measures over time. Ra was analyzed through nonparametric Kruskal Wallis and Dunn tests to compare the groups. Paired Wilcoxon test was run to compare experimental times. ∆WID, ∆Eab*, and ∆E00 were analyzed through Kruskal Wallis and Dunn tests. All analyses were performed in R* software, at 5% significance level. EXP_SGY recorded higher KHN than EXP_SiO2 and EXP_CaCO3, whereas EXP_K showed increased Ra in comparison to CMP (p = 0.0229). ∆Eab and ∆E00 were significantly higher in the CT12, EXP_SiO2, and EXP_CaCO3 groups than in the NC and EXP_K (p < 0.0001). There were no significant changes in ∆WID (p = 0.0852). According to SEM results, toothbrushing with experimental toothpastes added with mineral clay types did not have significant impact on enamel's polishing and smoothness. CLINICAL RELEVANCE: Mineral clays have a broad application in the cosmetic industry, and recently, they have been used in the formulation of vegan toothpaste.

Remineralizing effect of the association of nano-hydroxyapatite and fluoride in the treatment of initial lesions of the enamel: A systematic review

OBJECTIVE

Assessed the effect of dental products containing nano-hydroxyapatite (nano-HA) + fluoride on the remineralization of white spot lesions (WSL) in vivo or in situ.

METHODS

Seven databases were explored using a two-pronged approach (intervention/treatment). After screening, full-text assessment, and further exclusion, the qualitative synthesis of five studies (four clinical and one in situ) was performed. Based on the Cochrane collaboration guidelines relevant data of the studies were collected and summarized. The Cochrane risk of bias tool for randomized trials (RoB 2.0) was used to appraise the studies' methodological quality and the GRADE guidelines to assess their level of evidence. The RoB 2.0 domains were rated on their risk of bias (RoB) as low, high, or with some concerns, and an adaptation of the tool was used to the in situ study.

RESULTS

The included studies assessed 151 WSL in anterior permanent teeth, on patients with varying ages. The protocol application, treatment length (7d-12 w), and control groups varied greatly between the studies making the performance of a quantitative analysis unfeasible. The general RoB of the clinical studies was classified as being of low risk (n = 2) or some concerns (n = 2). The in situ study was considered as being of low risk. The level of the evidence was moderate. Most of the studies found moderate evidence regarding the superiority of this association in clinical settings.

CONCLUSION

Even with the nano-HA + fluoride promising results for the remineralization treatment of WSL, due to the restricted number of studies and types of products, its extended use cannot be recommended based on the current systematic review, especially when considering the moderate level of the evidence found.

CLINICAL SIGNIFICANCE

Due to the biocompatibility and higher surface coverage of nano-HA and the remineralization capacity of fluoride formulations, the association of these elements to remineralize WSL has been positively reported. After the collection and qualitative appraise of the data, the clinical evidence of the use of these dental products is promising but limited.

Enzymatically Driven Mineralization of a Calcium-Polyphosphate Bleaching Gel

To examined alkaline phosphatase enzyme (ALP) activity and the effects of incorporating it in the thickener solution of a hydrogen-peroxide-based bleaching gel containing calcium-polyphosphate (CaPP) on the orthophosphate (PO43-) levels, bleaching effectiveness, and enamel microhardness. ALP activity was assessed at different pH levels and H2O2 concentrations, and in H2O- and Tris-based thickeners. Circular dichroism (CD) was used to examine the ALP secondary structure in water-, Tris-, or H2O2-based mediums. The PO43- levels were evaluated in thickeners with and without ALP. Enamel/dentin specimens were allocated into the following groups: control (without bleaching); commercial (Whiteness-HP-Maxx); Exp-H (H2O-based); CaPP-H; ALP-H (CaPP+ALP); Exp-T (Tris-based); CaPP-T; and ALP-T (CaPP+ALP). Color changes (ΔE/ΔE00) and the bleaching index (ΔWID) were calculated, and surface (SMH) and cross-sectional microhardness (CSMH) were assessed. The two-way ANOVA and Tukey's post-hoc tests were used to compare ALP and PO43- levels; generalized linear models were used to examine: ΔE/ΔE00/SMH/CSMH; and Kruskal-Wallis and Dunn's tests were used for ΔWID (α = 5%). The ALP activity was higher at pH 9, lower in H2O2-based mediums, and similar in both thickeners. The CD-spectra indicated denaturation of the enzyme upon contact with H2O2. The PO43- levels were higher after incorporating ALP, and the ΔE/ΔE00/ΔWID were comparable among bleached groups. SMH was lower after bleaching in Exp-H, while CSMH was highest in ALP-T.

Effect of incorporation of calcium polyphosphate sub-microparticles in low-concentration bleaching gels on physical properties of dental enamel

AIM

To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs).

METHODS

A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test.

RESULTS

The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05).

CONCLUSION

The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy.

Impact of chitosan-incorporated toothpaste on roughness, gloss, and antifungal potential of acrylic resin

This study aimed to test the efficacy of different silica-based toothpastes with or without chitosan, as a method of cleaning the acrylic surfaces of denture prostheses. Acrylic resin specimens were prepared to evaluate surface roughness and gloss (n = 10), and Candida albicans adhesion/inhibition (n = 2). Two toothpastes with different degrees of abrasiveness were used: Colgate (CT) and Elmex (EX), with or without 0.5% chitosan (Ch) microparticles (CTCh or EXCh, respectively). The negative control was brushed with distilled water. Brushing was simulated with a machine. Surface roughness and gloss were analyzed before and after brushing. Candida albicans incidence/inhibition was tested qualitatively to determine the acrylic resin antifungal activity. The roughness and gloss data were analyzed with a generalized linear model, and the Kruskal Wallis and Dunn tests, respectively (α = 5%). Brushing with toothpastes increased roughness and reduced gloss, compared with the negative control (p < 0.05). CT showed a more significantly different change in roughness and gloss, in relation to the other groups (p < 0.05). Addition of chitosan to CT reduced its abrasive potential, and yielded results similar to those of EX and EXCh. Specimens brushed with CT showed a higher potential for Candida albicans adherence, despite its higher antifungal action. Addition of chitosan to the toothpaste made both toothpaste and brushing more effective in inhibiting Candida albicans. CT had the potential to increase roughness, reduce gloss, and increase Candida albicans adherence. In contrast, chitosan added to CT showed greater antifungal potential, and a higher synergistic effect than EX.

Maintenance of enamel properties after bleaching with high-concentrated hydrogen-peroxide gel containing calcium polyphosphate sub-microparticles

OBJECTIVE

To assessed the physical and chemical properties of human-enamel after treatment with an experimental bleaching gel containing 35%-hydrogen peroxide (HP) and calcium polyphosphate sub-microparticles (CaPP).

MATERIALS AND METHODS

Enamel/dentin specimens (4 × 4 × 3 mm) were obtained (n = 120) and allocated to different groups: control (saliva only); experimental (HP35%); commercial (whiteness-HP-Maxx); CaPP0.5% (HP35% + CaPP0.5wt%); CaPP1.5% (HP35% + CaPP1.5wt%). Three sessions were performed. The specimens' color was assessed using a spectrophotometer and the color (ΔE/ΔE00) and bleaching index (ΔWID) determined. The surface roughness and microhardness were assessed with a roughness tester and Knoop indenter. Raman spectroscopy was performed to obtain the ratios between the areas under the 431, 580, and 1070 cm-1 and the 960 cm-1 bands (430:960, 580:960, 1070:960). Kruskal-Wallis and Dunn compared the color, Ra, and SMH data. The Raman data was analyzed with Kruskal-Wallis and Dunn (α = 5%).

RESULTS

The ΔE, ΔE00, and ΔWID were similar among the bleached groups (p > 0.05). The roughness was not different between the groups (p > 0.05). After the 3rd session, CaPP0.5% had higher microhardness than the experimental (p < 0.05). The 1070:960 was higher in the experimental than in the CaPP1.5% and control (p < 0.05).

CONCLUSIONS

In human enamel, CaPP did not alter the bleaching effectiveness or roughness, and additionally, CaPP-containing gels increased the microhardness and preserved the mineral content when compared to the experimental without CaPP.

CLINICAL RELEVANCE

Experimental bleaching gels containing calcium polyphosphate sub-microparticles as a mineral source reduce the mineral content alteration and superficial microhardness reduction, known potential side effects of the in-office bleaching treatments.

Application of polyetheretherketone (PEEK) posts: evaluation of fracture resistance and stress distribution in the root: in vitro and finite element analyses

To evaluate the feasibility of using a milled polyetheretherketone (PEEK) post and core in endodontically treated teeth with or without a ferrule. Sixty bovine tooth roots were endodontically treated followed by cementation of intraradicular retainers (IR), according to each experimental group: a) non-ferrule glass fiber post (f0FP); b) 2-mm-ferrule glass fiber post (f2FP); c) non-ferrule resized glass fiber post (f0PR); d) 2-mm-ferrule resized glass fiber post (f2PR); e) non-ferrule PEEK post and core (f0PPC); and f) 2-mm-ferrule PEEK post and core (f2PPC). Metal crowns were made and cemented. A periodontal ligament was simulated using polyether. A force was applied to the palatine portion of each sample at 45°, until fracture. Fracture resistance data were submitted to two-way ANOVA and Tukey's test (α = 0.05). Three-dimensional digital models were developed to calculate the tensions formed in the root using finite element analysis. Models of glass fiber posts and PEEK posts and cores were evaluated with or without a ferrule. The results were analyzed by the Mohr-Coulomb criterion. The type of IR was not influenced by fracture strength (p = 0.243). There were significant statistical differences among the remaining factors. Ferrule groups had greater fracture resistance, and the failure mode of teeth with a ferrule was more catastrophic than the non-ferrule group. A ferrule increases fracture resistance and influences failure mode; the PEEK post and core did not modify the biomechanics of endodontically treated teeth, and resembled the glass fiber post results. The crack initiation point differed between the ferrule and non-ferrule groups.

Effect of experimental bleaching gels with polymers Natrosol and Aristoflex on the enamel surface properties

Natrosol and Aristoflex® AVC polymers are widely applied in the cosmetic industry and have recently been applied as a thickener option in the composition of dental bleaching gels, with the purpose to reduce the adverse effects on enamel mineral components. The aim of this study was to evaluate the color variation (ΔE* ab, ΔE00, ∆WID), surface roughness (Ra), and mineral content quantification (Raman Spectroscopy) of dental enamel after bleaching treatment with experimental gel-based on 10% carbamide peroxide (CP), containing Carbopol, Natrosol, and Aristoflex® AVC. Sixty bovine teeth were randomly divided into 6 groups (n=10): Negative Control (NC) - no treatment; Positive Control (PC) - Whiteness Perfect 10% - FGM; CP with Carbopol (CPc); CP with Natrosol (CPn); CP with Aristoflex® AVC (CPa); NCP - no thickener. Data were analyzed, and generalized linear models (∆WID -T0 x T1) were used for repeated measurements in time for Ra and with a study factor for ΔE* ab and ΔE00. For the evaluation of the mineral content, data were submitted to one-way ANOVA and Tukey tests. For enamel topographic surface analysis the Scanning Electron Microscope (SEM) was performed. A significance level of 5% was considered. ΔE* ab and ΔE00 were significantly higher for CPc, CPn, CPa, and NCP groups. (∆WID) showed a significantly lower mean than the other groups for NC in T1. After bleaching (4-hour daily application for 14 days), Ra was higher in the CPc, CPn, and PC groups. For CPa, Ra was not altered. No significant difference was found in the quantification of mineral content. CPa preserved the surface smoothness more effectively. Aristoflex® AVC is a viable option for application as a thickener in dental bleaching gels, presenting satisfactory performance, and maintaining the whitening efficacy of the gel, with the advantage of preserving the surface roughness of tooth enamel without significant loss of mineral content.

Calcium-Polyphosphate Submicroparticles (CaPP) Improvement Effect of the Experimental Bleaching Gels' Chemical and Cellular-Viability Properties

The aim of this research was to develop and characterize the chemical and cellular-viability properties of an experimental high-concentration bleaching gel (35 wt%-H2O2) containing calcium-polyphosphate particles (CaPP) at two concentrations (0.5 wt% and 1.5 wt%). The CaPP submicroparticles were synthesized by coprecipitation, keeping a Ca:P ratio of 2:1. The CaPP morphology, size, and chemical and crystal profiles were characterized through scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction, respectively. The assessed bleaching gels were experimental (without CaPP); 0.5% CaPP; 1.5% CaPP; and commercial. The gels’ pH values and H2O2 concentrations (iodometric titration) were determined. The odontoblast-like cell viability after a gel’s exposure was assessed by the MTT assay. The pH and H2O2 concentration were compared through a repeated-measures analysis of variance (ANOVA) and a Tukey’s test and the cell viability through a one-way ANOVA and a Tukey’s test using a GraphPad Prism (α < 0.05). The CaPP particles were spherical (with Ca and P, 135.7 ± 80.95 nm size) and amorphous. The H2O2 concentration decreased in all groups after mixing (p < 0.001). The 0.5% CaPP resulted in more-stable pH levels and higher viability levels than the experimental one (p < 0.05). The successful incorporation of CaPP had a positive impact on the bleaching gel’s chemical and cellular-viability properties when compared to the experimental gel without these particles.

Characterization of whitening toothpastes and their effect on the physical properties of bulk-fill composites

To characterize activated charcoal and 2% hydrogen peroxide-based toothpastes and investigate their effects on roughness, color change, and gloss of bulk-fill composite resin. Composite resin specimens (Aura Bulk Fill, SDI) were subjected to 5,000 brushing cycles with regular toothpaste (Colgate Total 12, [RT]), activated charcoal toothpaste (Bianco Dental Carbon, [AC]), or hydrogen peroxide-containing toothpaste (Colgate Luminous White Advanced, [HP]), with or without coffee exposure. The pH, particle characterization by scanning electron microscopy (SEM), and weight% of solid particles in the toothpaste were assessed. Roughness (Ra) was evaluated using a surface profile-measuring device, color change (∆Eab/∆E00) by reflectance spectrophotometer, and gloss unit (GU) by glossmeter. Kruskal-Wallis, Dunn, Friedman, and Nemenyi tests were used, and the correlation coefficient test was performed between Ra and GU (α=0.05). RT presented a higher Ra after brushing and did not change after staining with coffee; moreover, the ∆Eab/∆E00 values were higher for RT than HP. Regarding gloss, AC and HP obtained higher values compared to RT. A significant negative correlation between gloss and Ra was found for RT exposed to coffee. All toothpastes had a neutral pH; however, RT had the largest percentage of solids by weight. SEM images showed particles of many sizes: irregular shape (RT), more regular particles (AC), and spherical clusters (HP). Although surface roughness, color change, and gloss may compromise the longevity of restorations, the whitening toothpastes tested did not promote more morphology changes than regular toothpastes.

Effect of bleaching gels with different thickeners under normal and hyposalivation conditions: in situ study

BACKGROUND

Bleaching gel thickeners induce important changes in tooth enamel and these changes are reversed by saliva.

OBJECTIVE

This in situ study aimed to evaluate the effect of bleaching gels with different thickeners on tooth enamel under normal and hyposalivation conditions.

METHODOLOGY

Of 28 participants, 14 had normal salivary flow and 14 had low salivary flow. For each salivary flow, four types of treatment were performed with different thickeners: no bleaching (negative control), bleaching with a commercial 10% carbamide peroxide (CP) gel with carbopol (positive control) and bleaching with experimental 10% CP gels with natrosol and aristoflex. Participants used a palatal appliance containing bovine enamel/dentin specimens for 15 days. From day 2 to day 15, specimens were bleached extraorally. The bleaching gel was applied according to the groups for four hours. When the bleaching gel was removed, the palatal appliance was inserted again in the participants' mouth until the next day for another bleaching application. This procedure was repeated for 14 days and on day 15, surface microhardness (SMH), color (ΔE*ab and ΔE00), surface roughness (Ra), scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry (EDS) analyses were performed and data were subjected to statistical analysis.

RESULTS

Neither salivary flow nor thickeners influenced ΔE*ab and ΔE00 results. Carbopol had the lowest SMH, the highest Ra, and the lowest Ca% among all groups. For normal flow, natrosol and aristoflex had higher SMH. For low flow, aristoflex had higher SMH and natrosol and aristoflex had lower Ra. Aristoflex had higher Ca% and Ca/P and differed from carbopol for normal flow.

CONCLUSION

For normal flow, 10% CP gels with natrosol and aristoflex caused fewer surface changes, and for low flow, only the 10% CP gel with aristoflex.

Effect of Different Bleaching Gels Thickeners on Cytotoxicity to Human Gingival Fibroblasts and Enamel Physical Properties: an in Situ Study

Objective

This study evaluated in vitro, the effects of carbamide peroxide 10% (CP) associated with Carbopol® (CP-ct) and Aristoflex® (CP-at) thickeners on human gingival fibroblasts (HGF) cytotoxicity and assessed in situ their effects on dental enamel.

Material and methods

The cytotoxicity was analyzed using MTT - Vybrant® proliferation test. For in situ stage, 144 bovine enamel/dentin blocks were randomized into seven groups (n=12). Samples were stained, fixed in intraoral palatal devices and bleached for 4 h, during 14 days, with: Carbopol thickener (ct), Aristoflex thickener (at), CP-ct, CP-at, CP without thickener (CP-wot), Commercial CP (CP-com). The samples had their microhardness (SMH), roughness (Ra) and color analyzed using a microdurometer, a rugosimeter and a spectrophotometer, respectively. The analyses were performed at baseline and 24-h after completion of tooth bleaching.

Results

Different thickeners were similar regarding their cytotoxicity. The experimental gels with Carbopol exhibited lower SMH values, while the groups treated with CP exhibited higher Ra values. For the color change results, the groups treated with CP had values above the acceptability and perceptibility limits.

Conclusion

CP-at was able to promote an effective bleaching with less alterations of the tooth surface compared to the CP-ct. Hence, Aristoflex stands as a promising thickener in conjunction with CP in order to preserve the physical properties of dental enamel after home bleaching.

Nano-hydroxyapatite-induced remineralization of artificial white spot lesions after bleaching treatment with 10% carbamide peroxide

OBJECTIVE

To assessed in vitro the effect of nanohydroxyapatite (n-HA) to improve the aesthetic appearance and microhardness of white spot lesions (WSL) when associated with a low-concentration bleaching agent (carbamide peroxide-CP10%).

MATERIAL AND METHODS

Enamel/dentin specimens (n = 60) of 5 × 5 × 2.2 mm were prepared, of these, 48 were submitted to pH-cycling to create artificial WSL. Subsequently, these were allocated into five groups (n = 12): n-HA; n-HA + CP10%; CP10%; WSL control (WSL_C ); sound control (Sound). The color was assessed at baseline, pre-treatment, and post-treatment using a spectrophotometer, and the color (ΔE/ΔE₀₀ ) and whiteness index (ΔWID) alterations were determined. The enamel cross-sectional microhardness (CSMH) was evaluated (post-treatment) with a Knoop indenter, 25gf/5 s, 20-200 μm. The data was analyzed through generalized linear models (α = 5%).

RESULTS

ΔE and ΔE₀₀ were significantly higher for the bleached groups (n-HA + CP10% and CP10%), and the n-HA was higher than the WSL_C group (p < 0.05). ΔWID was significantly higher for the bleached groups (p < 0.05). The CSMH values were significantly higher in the sound group than in the n-HA, CP10%, and WSL_C groups (p < 0.05). The WSL_C had lower microhardness than the n-HA + CP10% and sound groups (p < 0.05).

CONCLUSION

n-HA is suitable to remineralize and recover the color of the WSL. However, its association with CP10% maintains the esthetical outcome while increasing its in-depth remineralizing effect.

CLINICAL SIGNIFICANCE

Considering the aesthetic and functional repercussions of the WSL persistence, treatments that tend to improve its physical appearance and reinforce its weakened substructure in a non-invasive way are ideal. For this associating low-concentration, bleaching agents to the remineralizing treatments is promising to treat this type of lesions.

Assessment of influence of LED curing units used on microhardness of resin-modified glass ionomer sealants

Aim: Resin modified glass ionomer (RMGI) is class of material that can be used as sealant for preventing and arresting the progression of caries in pits and fissures. As these are hybrid materials, their properties can be affected by factors related to the polymerization process. Therefore, this study aimed to evaluate the influence of different generations of LED curing units (Elipar DeepCure-L and VALO Grand) on Knoop microhardness values (KHN) of RMGI sealants (Clinpro XT and Vitremer). Methods: Forty cylindrical specimens (6mm ø x 1 mm high) were prepared according to the manufacturer’s instructions and divided into four groups (n=10) according to the type of RMGI and LED used. The KHN of the top surface of each sample was calculated 7 days after light-curing. Data were submitted to two-way ANOVA (α = 0.05). Results: Vitremer had higher KHN values than Clinpro XT after using both LEDs (p<0.0001), but especially when light-cured with the use of VALO Grand (p<0.0001). Whereas the KHN value of Clinpro was not influenced by the LED device (p>0.05). Conclusions: Top surface microhardness values of RGMI sealants were affected by both material composition and generations of LED curing units used. Third generation LED curing units seemed to be more efficient for the polymerization of RMGI-based sealants.

PEEK and fiberglass intra-radicular posts: influence of resin cement and mechanical cycling on push-out bond strength

OBJECTIVES

To evaluate the bond strength of four types of posts (pre-fabricated fiberglass post, fiberglass post anatomized with composite resin, milled fiberglass post, and milled polyetheretherketone (PEEK) post), and two types of resin cements (conventional and self-adhesive) by assessing immediate bond strength and post-mechanical aging at each root third.

MATERIALS AND METHODS

Bovine endodontically treated roots (16 groups, n = 8) were prepared and the posts were produced and luted; the specimens of aging groups were cycled (300,000 cycles under 50 N load at 1.2 Hz frequency); six slices of each root were obtained; push-out test was performed by using a universal testing machine (500 N load at 1 mm/min cross speed); fracture pattern was classified into five levels. The statistical analyses used were three-way ANOVA, Tukey's test (for bond strength), and Fisher's test (for fracture pattern) (α < 0.05).

RESULTS

Differences were found between the cements for posts (conventional: p < 0.001; self-adhesive: p = 0.002), whereas no difference was found for root region (p = 0.941; p = 0.056, respectively); analysis of each root showed significant differences for cements (p < 0.001), posts (p < 0.001), and mechanical cycling (p = 0.001); in terms of double interaction, differences were found for posts and mechanical cycling (p = 0.005); no other interactions were observed (double or triple); the fracture pattern showed difference between the groups for both cements.

CONCLUSIONS

Milled PEEK posts seem to be a good clinical option, but they require improvement of CAD-CAM technology and advances towards their adhesion.

CLINICAL RELEVANCE

Milled posts are promising and can reduce clinical time for rehabilitation of extensively destroyed teeth.

Effect of at-home bleaching gels with different thickeners on the physical properties of a composite resin without bisphenol A

OBJECTIVE

To investigate, in vitro, the influence of at-home bleaching with 16% carbamide peroxide (CP) gels containing different thickeners on the color, gloss, roughness, and microhardness of a composite resin with bisphenol A (BPA) and without bisphenol A (BPA-free).

MATERIAL AND METHODS

Cylindrical samples (7 × 2 mm) of a composite resin with BPA (Filtek Z350 XT®; 3M/ESPE) and composite resin BPA-free (Vittra APS®; FGM) were subdivided into six subgroups (n = 12), according to the bleaching gel used: no bleaching (control), commercial gel with 16% CP and carbopol, experimental gel with 16% CP and carbopol, experimental gel with 16% CP and natrosol, experimental gel with carbopol and experimental gel with natrosol. At the end of the experimental phase, the specimens were analyzed for color (ΔE*_ab and ΔE₀₀ ), surface roughness (Ra), gloss (GU), and surface microhardness (SMH). The data for all analyzes were submitted to Levene's test, Shapiro-Wilk's test and ANOVA.

RESULTS

For ΔE*_ab and ΔE₀₀ no statistically significant differences were found between all groups evaluated. Bleaching with experimental 16% CP gel with carbopol resulted in the lowest GU values for both composite resins evaluated. 16% CP experimental gel with natrosol resulted in higher Ra for the BPA composite resin and the bleaching with natrosol resulted in higher Ra for BPA-free. About 16% CP experimental gel with carbopol and 16% CP experimental gel with natrosol resulted in the lowest final SMH for composite resin with BPA. For the BPA-free composite resin, no differences were found between the groups in SMH for the same resin, however they presented the lowest values compared with all others groups.

CONCLUSION

The effects on physical properties are dependent on the composition of the composite resin and the thickener/bleaching gel used. The BPA-free composite resin showed less changes after exposure to bleaching agent, although its initial physical properties were worse compared to a bleached BPA.

CLINICAL RELEVANCE

The hydrogen peroxide and thickener of the at-home bleaching gel does impact the properties of composites with BPA or BPA-free such as gloss, roughness and surface microhardness, extremely important factors for maintaining an aesthetically and physically satisfactory restoration. BPA-free composite resins have inferior properties after at-home bleaching with different thickeners.

Effect of accelerated stability on the physical, chemical, and mechanical properties of experimental bleaching gels containing different bioadhesive polymers

OBJECTIVE

To evaluate the physical-chemical (weight, pH, quantification of hydrogen peroxide) and mechanical (texture profile and rheology tests) properties of the experimental bleaching gel based on the bioadhesive polymer Aristoflex® AVC, after accelerated stability testing.

MATERIALS AND METHODS

A total of 300 syringes of bleaching gels were divided into 5 groups (n = 60): Whiteness Perfect® 10%-FGM (WP); carbamide peroxide 10% with aristoflex (CPa); carbamide peroxide 10% with Carbopol (CPc); aristoflex thickener (A); and Carbopol thickener (C). According to the following requirements and time, the accelerated stability test was performed: in an incubator at 40 °C and 75% humidity per 1, 3, and 6 months, and baseline (refrigerator at 5 °C and 25% humidity). The variables were analyzed following the statistical tests: Two-way ANOVA and Tukey's test were applied to pH; weight data were analyzed using a mixed model for repeated measurements over time and the Tukey-Kramer test; one-way ANOVA and Tukey's test analyzed the rheology test; generalized linear models were used to quantify the peroxide amount and texture profile data. A significance level of 5% was considered.

RESULTS

The experimental bleaches CPa and CPc had the highest pH values when compared to the others in 6 months. Thickeners A and C did not change the pH, weight, and active content over the accelerated stability times (p > 0.05). Furthermore, there was weight loss after 3 months of storage for CPa and CPc (p < 0.05). In the quantification of hydrogen peroxide, the WP group showed the highest values over time (p < 0.0001), only showing a significant loss after the 3rd month. Meanwhile, CPa and CPc showed a reduction in quantification from the 1st month.

CONCLUSIONS

Temperature and humidity directly influenced the active content and properties of bleaching gels. In addition, the presence of components regardless of thickeners, such as stabilizers, in the commercial gel allowed for greater stability over time.

CLINICAL RELEVANCE

The development of experimental bleaching gels for clinical use requires careful testing. Therefore, accelerated stability testing represents a valuable tool in the development and evaluation of cosmetic formulations.

In-office tooth bleaching with chitosan-enriched hydrogen peroxide gels: in vitro results

OBJECTIVE

This study aimed to evaluate the effects of adding chitosan to 35% hydrogen peroxide gels (for in-office bleaching), with or without calcium gluconate, on tooth properties and bleaching efficacy.

METHODS

Bovine enamel/dentin specimens (4 × 4 × 2.5 mm) were randomly allocated into groups (n = 10): negative control (unbleached), bleaching with 35% hydrogen peroxide gel (35% HP, commercial gel); 35% HP with 2% chitosan (% wt) (35% HP + chitosan), 35% HP and calcium (35% HP + Ca, commercial gel), and 35% HP + Ca + 2% chitosan. Variation of surface profile (ΔRa) and color analyses (ΔL*, Δa*, Δb*, ΔE*_ab, ΔE₀₀, and ΔWID) were performed comparing specimens at baseline (initial) and 24 h after of storage in artificial saliva (final). Surface microhardness (KHN) values and scanning electron microscopy (SEM) images were obtained on conclusion. The data were analyzed by ANOVA and Tukey's tests (KHN), generalized linear models (ΔL*, ΔE_ab, ΔE₀₀, ΔWID, ΔRa), and Kruskal-Wallis and Dunn tests (Δa*, Δb*) (α = 0.05).

RESULTS

Considering ΔL*, Δa*, Δb*, ΔE*_ab, ΔE₀₀, and ΔWID values, the bleached groups differed from negative control. For ΔRa, chitosan-based groups showed lower variation in surface roughness compared to 35% HP, without significant difference from negative control. For KHN, chitosan groups did not differ from negative control (unbleached control = chitosan groups > 35% HP + Ca > 35% HP). For SEM, slight surface changes were observed in all bleached groups, but the intensity varied according to gel used (35% HP > gels with Ca > gels with chitosan).

CONCLUSION

Chitosan-enriched hydrogen peroxide gels can reduce negative impacts on tooth properties without affecting bleaching efficacy.

CLINICAL RELEVANCE

Although commercial gels containing remineralizing agents such as calcium reduce the negative effects on the properties of teeth, the addition of chitosan appears to be a promising approach to preservation of dental properties without interfering in bleaching efficacy.

Effects of desensitizing products on the reduction of pain sensitivity caused by in-office tooth bleaching: a 24-week follow-up

Objective

To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching.

Methodology

A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05).

Results

The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning.

Conclusion

Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

Glass fiber posts

Aim: Glass fiber posts are indicated in the rehabilitation of extensively damaged teeth; their cementation represents a critical step in restorative dentistry. The aim of this study was to quantify and compare the push-out bond strength of glass fiber posts cemented by conventional technique, two-step technique with luting agent and two-step technique associating bulk-fill composite and luting agent. Methods: Eighty maxillary bovine incisors were endodontically treated and divided into eight groups (n = 10) according to the luting agent (Rely X ARC and Duo-link) and cementation technique (conventional technique; two-step technique with luting agent; and two-step technique associating bulk-fill composite – Filtek Bulk-fill flow or Surefil SDR flow – and luting agent). Samples were submitted to pushout bond strength test, and the fracture pattern was evaluated through scanning electron microscope. Data were submitted to two-way ANOVA and Tukey’s test (α = 0.05). Results: When Rely X ARC was used, the conventional cementation technique obtained higher bond strength values than the twostep technique associated with Filtek Bulk-fill flow. When Duolink was used, the two-step technique associated with Filtek Bulk-fill flow presented higher bond strength values than the conventional technique. The most prevalent fracture patterns were adhesive between luting agent and dentin, and adhesive between bulk-fill composite and dentin. Conclusion: Two-step cementation technique associated with bulk-fill composite may be promising depending on the luting agent used.

Resolution of a fluorosis case through the association of minimally invasive techniques

Color changes may interfere with smile balance and they represent a clinical challenge to dentists. Dental fluorosis originates from intrinsic factors and it is a disorder of enamel formation during the phase of teeth development, resulting in the change of enamel color. This clinical case report aimed to present the resolution of a case of dental fluorosis through the association of minimally invasive techniques, namely microabrasion and tooth bleaching. A 27-year-old male patient sought the dental clinic of the School of Dentistry of Piracicaba (FOP - UNICAMP, Brazil) presenting striped and symmetrical white stains and generalized chromogenic biofilm. After anamnesis and clinical examination, the patient was diagnosed with fluorosis stains. Initially, adequacy of the oral environment was performed with prophylaxis and supragingival scraping. Then, the enamel microabrasion technique was performed with 6% hydrochloric acid associated with silicon carbide (Whiteness RM - FGM) and supervised at-home bleaching was performed with 16% carbamide peroxide (Whiteness Simple 16% - FGM). In conclusion, the treatment performed reestablished the aesthetics and harmony of smile color with minimally invasive procedures without causing tooth sensitivity.

Evaluation of home bleaching gel modified by different thickeners on the physical properties of enamel: An in situ study

Objective:

This in situ study evaluated the influence of 10% carbamide peroxide (CP) in combination with different thickeners on physical characteristics of enamel.

Materials and Methods:

Eighty-four bovine blocks of enamel and dentin (4 mm × 4 mm × 2.5 mm) were divided into seven groups (n = 12), fixed in palatal intraoral devices, and submitted to different treatments: CP + carbopol (FGM), CP + carbopol + glycerin (ultradent), CP + natrosol (experimental gel), carbopol, carbopol + glycerin, and natrosol, without treatment (control group). The physical properties tested were color (ΔE), roughness (Ra), and Knoop microhardness (KHN).

Statistical Analysis Used:

Data were submitted to ANOVA, Tukey's, and Dunnett's tests (α = 0.05). Results: all groups presented significant color variation, except carbopol. For microhardness, all bleached groups did not differ from control. Roughness increased in all bleached groups when compared to the control group, but CP + natrosol presented statistical lower results than CP + carbopol.

Conclusion:

Replacement of carbopol by natrosol caused less change on roughness surface, at the same time yielding an effective whitening result.

Effects of desensitizing dentifrices on the reduction of pain sensitivity caused by in-office dental whitening: a double-blind controlled clinical study

Objective: The purpose of this study was to clinically evaluate the influence of desensitizing dentifrices applied through a plastic tray on reducing the pain sensitivity and color variation caused by in-office dental whitening and to evaluate differences among such dentifrices through a controlled double-blind clinical study.

Materials and methods: A prospective study was conducted with 48 individuals between 18 and 30 years without gender distinction. For the dental whitening, 35% hydrogen peroxide was used in three clinical sessions. After each whitening session, the volunteers used a plastic tray containing one of the dentifrices (sucralose– S, sodium fluoride – SF, arginine and calcium carbonate – ACC, and 5% potassium nitrate – PN) for 4 hrs during the night. The evaluation of the sensitivity associated with the use of the plastic tray in each whitening session was performed using the analog numerical scale with scores from 0 to 10. The color variation (ΔE) was determined with a spectrophotometer. The pain sensitivity data were submitted to the multivariate analysis of variance with repeated measurements and a Lambda Wilks test (p<0.05). To analyze the color variation, a one-way ANOVA was applied (p<0.05).

Results: The ACC and 5% NP groups showed a reduction in sensitivity in relation to the other groups (p<0.05). There was a reduction in sensitivity after placement of the tray with dentifrice. The color evaluation associated with the dentifrice showed no difference (p=0.9186).

Conclusion: The use of desensitizing dentifrices with ACC or 5% NP in a plastic tray was effective for the reduction of pain sensitivity, and the use of a desensitizing dentifrice did not decrease the effectiveness of whitening.

Effect of Dentin Pretreatment with Arginine on Microshear Bond Strength of Etch-and-Rinse or Self-Etch Adhesive Systems

Objective The main purpose of this study was to evaluate the effect of dentin pretreatment with 8% arginine on the immediate and 6-month bond strength (BS) of adhesive systems and surface morphology of dentin.

Materials and Methods Dentin bovine specimens (5 × 5 mm) were allocated into following pretreatments: without pretreatment (conventional technique, C) or exposure to arginine solution (A) for 5 minutes prior to tooth restoration. The adhesive procedure was performed using ( n = 12): 3-step etch-and-rinse adhesive (Scotchbond Multipurpose—SBMP [C+SBMP and A+SBMP]); 2-step etch-and-rinse adhesive (Single Bond 2 - SB [C+SB and A+SB]); or 2-step self-etch adhesive (Clearfil SE Bond - CSEB [C+CSEB and A+CSEB]). After 24 hours, the composite resin restorations were evaluated immediately and after 6 months of water storage using a microshear test and fracture pattern. The dentin surface exposed to A was assessed by scanning electron microscopy (SEM). The immediate BS data were submitted to a two-way analysis of variance and Tukey's test, and the long-term BS results were analyzed using Kruskal–Wallis and Dunn tests (α = 0.05).

Results There was a significant decrease in immediate and 6-month BS for the A+SB and A+CSEB groups, which differed statistically from the C group. The fracture pattern was predominantly adhesive for SB and CSEB adhesive for C and A. The SEM images presented a different conditioning pattern of the dentin exposed to A.

Conclusion The dentin pretreatment with arginine interfered negatively in the immediate and long-term BS of the simplified adhesive system. However, the SBMP adhesive was not affected by arginine pretreatment presenting the most satisfactory results.

Evaluation of Bond Strength, Nanoleakage, and Marginal Adaptation of Bulk-fill Composites Submitted to Thermomechanical Aging

PURPOSE

To evaluate the bond strength (BS), nanoleakage, and marginal adaptation (MA) of three bulk-fill and one conventional composite, submitted or not to mechanical and thermal cycling.

MATERIALS AND METHODS

Ninety-six molars were selected and 4-mm-deep class I cavities were prepared and restored. Half of the teeth were submitted to mechanical and thermal cycling (MTC). Teeth were divided into 8 groups (n = 12), according to the composite used - Filtek Z350 XT (Z350), Tetric N-Ceram Bulk Fill (TET), Filtek Bulk Fill Posterior Restorative (FBF) and SonicFill (SF) - and aging, submitted or not to MTC. Fifty-six teeth (n = 7) were used for bond-strength testing, which was performed on stick-shaped specimens obtained from the restored area. Two sticks per tooth were selected to assess nanoleakage. For MA analysis, 40 teeth (n = 5) were sectioned parallel and perpendicular to the occlusal surface and resin-based replicas from the obtained surfaces were prepared. Fracture pattern, nanoleakage, and MA were evaluated using SEM. Quantitative analysis of nanoleakage and MA were performed with ImageJ software. Data obtained were submitted to two-way ANOVA and Tukey's test (ɑ = 0.05).

RESULTS

TET presented good MA and higher values of BS when compared to SF. Z350 and FBF presented poorer MA and lower BS, which was statically similar to the other groups. SF obtained the best MA values. Regarding nanoleakage, the highest values were obtained for TET, which differed significantly from the other groups, which presented similar results among themselves. Aging by MTC solely affected MA.

CONCLUSION

Bulk-fill composites presented similar performance to the conventional nanocomposite and remained stable when aged.

Evaluation of Finishing/Polishing Techniques on Low-Shrink Posterior Restorative After Mechanical Cycling

O objetivo deste estudo foi avaliar a rugosidade superficial de resinas compostas à base silorano e metacrilato submetidas a diferentes técnicas de acabamento/polimento. Foram preparadas 12 amostras de disco de cada resina composta: P90®, Z350® e Carisma, divididas em 12 grupos de acordo com a técnica de acabamento / polimento: sem acabamento / polimento (controle); acabamento com ponta diamantada 1112 FF; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo / Polishing / Pastas Poli I e II / Fotogloss. Após as leituras iniciais da rugosidade da superfície, os espécimes foram submetidos a ciclos mecânicos (1.200.000 ciclos) e submetidos imediatamente a leituras de rugosidade final. As medias de rugosidade superfícial foram analisadas estatisticamente por ANOVA e teste de Tukey-Kramer (α = 0,05). As imagens de MEV foram realizadas após o acabamento / polimento e após a ciclagem mecânica. O compósito P90 mostrou valores de rugosidade superficial semelhantes a outros compósitos investigados. Tough, mostrou diferença significativa nas técnicas de acabamento / polimento. O grupo de pontas damantadas apresentou maior rugosidade superficial que diferiu das outras resinas compostas (α <0,05). Enance / Pogo mostrou os menores resultados, que não apresentaram diferença em relação ao grupo de pasta de polimento (α> 0,05). O material restaurador posterior de baixa contração apresentou rugosidade superficial semelhante quando comparado as resinas compostas de dimetacrilato e são restaurações adequadas para região posterior.Palavras-chave: Dente. Resinas de Silorano.  Propriedades de Superfície. AbstractThe aim of this study was to evaluate the surface roughness of a silorane and methacrylate-based composite resins subjected to different finishing/polishing techniques. Twelve disk specimens were prepared from each composite resin: P90®, Z350® and Charisma, divided into 12 groups according to the finishing/polishing technique: no finishing/polishing (control); finishing with 1112 FF diamond burs; finishing with 1112 FF diamond burs associated to Enhance/Pogo; finishing with 1112 FF diamond burs associated to Enhance/Pogo/Polishing/Poli I and II pastes/Fotogloss. After initial readouts of surface roughness, the specimens were subjected to mechanical cycling (1.200.000 cycles) and immediately subjected to final roughness readouts.  Surface roughness means was statistically analyzed by ANOVA and Tukey-Kramer test (α=0.05). SEM images were realized after finishing/polishing and after mechanical cycling. The P90 composite showed surface roughness values similar to other investigated composites. However, significant difference was observed in finishing/polishing techniques. The diamond burs group showed the highest surface roughness differing from the other composite resins (α < 0.05). Enance/Pogo showed the lowest results, which presented no difference compared to the polishing paste group (α > 0.05). The low-shrink posterior restorative showed similar surface roughness when compared to dimethacrylate composite resins and suitable to posterior restorations. Keywords: Tooth. Silorane Resins. Surface Properties. 

Utilizing the optical properties of composite resins to improve esthetics: a layering technique for anterior restorations

A comprehensive knowledge of the optical properties of composite resins is essential to achieving optimal results in direct anterior restorations. This case report describes an anterior composite resin restoration fabricated with a layering technique and explains how to use a simple photographic method to verify that the desired optical effects are reproduced. A Class IV restoration was completed on a maxillary central incisor with the help of a silicone guide. An esthetic result was achieved through careful color examination as well as material selections that were based on knowledge of the translucency, opacity, and fluorescence of the chosen direct composite resins. The approach of combining a composite resin designed for bleached teeth with highly opalescent and translucent resins as well as matching the natural dental anatomy provided excellent esthetic results. The suitable reproduction of optical characteristics was confirmed by increasing the contrast of the final photograph, which highlighted the translucency achieved in the area of the mamelons.

Physical and photoelastic properties of bulk-fill and conventional composites

Purpose

This study evaluated the influence of thickness increment on degree of conversion (DC), Knoop microhardness (KHN), and polymerization-shrinkage stress (PSS) by photoelasticity of three dental composites.

Methods

For DC and KHN, 45 samples were prepared and divided into nine groups (n=5), according to composite (microhybrid [Filtek Z250 - Z250], bulk-fill flowable [SureFil SDR Flow - SDR], and nanohybrid composite [N’Durance - NDU]) and increment thickness (1, 1.5, and 3 mm). PSS was measured by photoelastic analysis. Composites were placed into a photo-elastic model cavity and light-cured. DC and KHN data were subjected to two-way ANOVA and Bonferroni post hoc test. PSS results were qualitatively evaluated through Kruskal–Wallis test.

Results

SDR showed the highest DC values. At top and bottom surfaces, the highest KHN was obtained by Z250. Z250 showed higher PSS than SDR in 1.5 mm increments. NDU showed higher PSS than SDR in 3 mm increments.

Conclusion

The bulk-fill composite demonstrated better DC and similar KHN and PSS in deeper layers compared to conventional composites. Bulk-fill composites may perform as well as conventional nanohybrid and microhybrid composites.

Influence of a hydrophobic monomer on the physical and mechanical properties of experimental surface sealants

This study evaluated the effect of adding the hydrophobic monomer 1,12 dodecanediol dimethacrylate (DDDMA) to experimental sealants with and without thermocycling on degree of conversion (DC), water sorption (WS), water solubility (WSB), color stability (ΔE), and micro-shear bond strength (μSBS). Five experimental and one commercially available sealant (Bisco - BIS) were tested. The experimental sealants were formulated by mixing different percentages of DDDMA monomers and urethane dimethacrylate (UDMA). The photoinitiator system was composed by camphorquinone (CQ) and tertiary amine 4-ethyl benzoate dimetilamiono (EDBA). Ethanol was used as a solvent. The experimental groups were named sequentially according to the monomeric content (DDDMA/UDMA): S40/40 (40/40), S50/30 (50/30), S60/20 (60/20), S70/10 (70/10) and S80/0 (80/0). Data were analyzed separately by one-way ANOVA, followed by Tukey's test (p<0.05). The values of DC ranged from 94.59% (S40/40) to 54.02% (S80/10). BIS showed the highest WS value (p<0.05) and S40/40, S50/30, S60/20 and S80/0 showed the lowest WS values of all tested sealants. WSB values ranged from 7.88 µg/mm3 (BIS) to 13.27 µg/mm3 (S70/10). The highest ΔE value was 11.05±2.88 for BIS and the highest μSBS value was found for S60/20. No significant difference was observed in bond strength between sealants and bovine enamel after thermocycling. Adding DDDMA to the composition of surface sealants can improve its performance, once the monomer increased the degree of conversion and the color stability.

Treatment of non-carious lesions: Diagnosis, restorative materials and techniques

Management of non-carious cervical lesions (NCCLs) still is a challenge in clinical practice. The diagnosis is the key to treat these lesions successfully. Aim/Case report: Therefore, the aim of this case report is to describe the diagnosis and treatment of generalized abfraction lesions associated to abrasion lesions of a 43 years old patient and to discuss considerations about the technique and materials to be used appropriately. After the diagnosis, a treatment plan with preventive and restorative approach was elaborated. The occlusal adjustment was performed to distribute the contact points and the patient was instructed in relation to tooth brushing habits. It was also recommended that the patient use a dentifrice with potassium nitrate for the control of sensitivity. For lesions over 1mm deep, the restorative treatment was performed using the self-etching adhesive system and nanohybrid composite by the stratification technique. Unsatisfactory restorations have been replaced. Occlusal splint was done and the patient was instructed to use the device every day overnight. One year after treatment, follow-up was performed. The appearance of new NCCLs was not observed. There was no progression of lesions smaller than 1 mm. There was no loss of restorations. All restorations were fully satisfactory and the patient reported absence of dentin hypersensitivity. Conclusion: The treatment performed besides being aesthetically satisfactory after 1 year resulted in the control of the disease, preventing the appearance of new lesions and guaranteeing a better quality of life to the patient.

Effect of different concentrations of nanohydroxyapatite on tooth bleaching effectiveness and enamel bond strength

Objective: To evaluate the effect of 35% hydrogen peroxide (35% HP) combined to different concentrations of nanohydroxyapatite (nHA) on the effectiveness of dental bleaching (superficial enamel and deep dentin) and enamel bond strength. Material and Methods: Fifty bovine dental specimens (5x5x2mm) were divided into 5 groups, according to the treatments (n = 10): no bleaching (negative control); 35% HP (positive control); 35% HP+ 5% nHA; 35% HP + 10% nHa; and 35% HP + 15% nHA. Three in-office bleaching sessions were made. The color analysis was performed on the enamel surface and the opposite dentin, using a spectrophotometer. The results were expressed in the CIE L*a*b* system. After this, the adhesive system was applied to the tooth structure, and the dental specimens received a composite restoration. The microshear bond strength test was performed 24 h after the restoration. Data were submitted to ANOVA and Tukey's test (?=0.05). Results: For the enamel color analysis, all bleached groups differed statistically from the unbleached group, with increasing L* values and decreasing b* values. The addition of different concentrations of nHA did not interfere with the bleaching effectiveness for the enamel and opposite dentin. For microshear bond strength, no statistically significant differences were presented between groups. The adhesive failure rate of the 35% HP + 10% nHA group was lower than the 35% HP group and similar to the negative control. Conclusion: The addition of different concentrations of nHA in 35% of hydrogen peroxide did not interfere with the bleaching efficacy of enamel and deep dentin and did not affect the enamel bond strength after bleaching KeywordsEnamel; Shear strength; Tooth bleaching. 

Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite

Objective

The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC), microhardness (KHN), plasticization (P), and depth of polymerization (DP) of a bulk fill composite.

Methods

Forty disc-shaped samples (n = 5) of a bulk fill composite were prepared (5 × 4 mm thick) and randomly divided into 4 groups according to light-curing unit (quartz–tungsten–halogen [QTH] or light-emitting diode [LED]) and preheating temperature (23 or 54 °C). A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey’s test (α = 0.05).

Results

Regardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill.

Conclusion

Composite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated.

Esthetic smile rehabilitation of anterior teeth by treatment with biomimetic restorative materials: a case report

BACKGROUND

In daily clinical practice, esthetics of anterior teeth is a common presenting complaint of patients.

OBJECTIVE

This case report discusses the management of asymmetric smile associated with unsatisfactory extensive composite restorations and describes a clinical protocol using the direct composite resin for smile enhancement to restore the dental harmony of anterior teeth.

METHODS

The treatment planning was based on a diagnostic wax-up and cosmetic mock-up. After clinical and patient approvals were obtained, the patient was subjected to direct and indirect restorative treatment.

CONCLUSION

Nanocomposites are an effective alternative for anterior teeth restorations. Additionally, good planning enables satisfactory esthetic results, leading to the correction of an inappropriate axial inclination of incisors.

Efficacy of Stannous Ions on Enamel Demineralization under Normal and Hyposalivatory Conditions: A Controlled Randomized in situ Pilot Trial

The study aim was to investigate the effect of antierosive agents on enamel under normal and hyposalivatory conditions. This double-blind crossover in situ pilot study evaluated 4 toothpastes: placebo (0 ppm F), sodium fluoride (NaF, 1,450 ppm), stannous/sodium fluoride (SnF/NaF, 1,450 ppm F-, 1,090 ppm Sn2+), and sodium fluoride, stannous chloride and chitosan (NaF/Sn/Ch, 1,450 ppm F-, 3,500 ppm Sn2+, 0.5% Ch). Twenty participants were assigned to 2 groups (n = 10 each): normal and low salivary flow. Participants wore palatal appliances holding 4 bovine enamel specimens previously eroded in vitro (D1) for 20 min prior to an in situ phase after which they were eroded again (D2). Surface microhardness was determined at baseline (BL), after D1, in situ phase and D2 to assess hardness loss (%SMH), residual hardness loss (%RHL) and erosion resistance (%RER). Additional specimens were evaluated by scanning electron microscopy after the in situ phase. ANOVA and a factorial analysis for between-subject effects were performed. Sn-based toothpastes showed the best effects (p < 0.05). Under normal flow, SnF/NaF showed higher efficacy, with a significant difference compared to NaF/Sn/Ch, NaF, and placebo (p < 0.05). Under low flow, SnF/NaF and NaF/Sn/Ch were comparable (p > 0.05); NaF and placebo were statistically similar. Comparing salivary conditions, there were significant differences for SnF/NaF for %SMH after the in situ phase (%SMHtotal)), %RHL and for all toothpastes in case of %RER. Factorial analysis revealed interactions between toothpaste and saliva flow for %SMHtotal and %RHL. Salivary flow can influence the efficacy of the antierosive toothpastes; however, Sn2+ preparations show even under low salivary flow conditions the highest efficacy in the prevention of enamel erosion.

Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis

This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey’s test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy.

Effect of Cigarette Smoke on Resin Composite Bond Strength to Enamel and Dentin Using Different Adhesive Systems

Objective: To evaluate the microshear bond strength of composite resin restorations in dental blocks with or without exposure to cigarette smoke.

Method: Eighty bovine dental blocks were divided into eight groups (n=10) according to the type of adhesive (Scotchbond Multi-Purpose, 3M ESPE, St Paul, MN, USA [SBMP]; Single Bond 2, 3M ESPE [SB]; Clearfil SE Bond, Kuraray Medical Inc, Okayama, Japan [CSEB]; Single Bond Universal, 3M ESPE [SBU]) and exposure to smoke (no exposure; exposure for five days/20 cigarettes per day). The adhesive systems were applied to the tooth structure, and the blocks received a composite restoration made using a matrix of perforated pasta. Data were statistically analyzed using analysis of variance and Tukey test (α&lt;0.05).

Results: For enamel, there was no difference between the presence or absence of cigarette smoke (p=0.1397); however, there were differences among the adhesive systems (p&lt;0.001). CSEB showed higher values and did not differ from SBU, but both were statistically different from SB. The SBMP showed intermediate values, while SB demonstrated lower values. For dentin, specimens subjected to cigarette smoke presented bond strength values that were lower when compared with those not exposed to smoke (p&lt;0.001). For the groups without exposure to cigarette smoke, CSEB showed higher values, differing from SBMP. SB and SBU showed intermediary values. For the groups with exposure to cigarette smoke, SBU showed values that were higher and statistically different from SB and CSEB, which presented lower values of bond strength. SBMP demonstrated an intermediate value of bond strength.

Conclusion: The exposure of dentin to cigarette smoke influenced the bonding strength of adhesives, but no differences were noted in enamel.

Effect of at-home bleaching with different thickeners and aging on physical properties of a nanocomposite

Objective:

To evaluate the influence of 16% carbamide peroxide (CP) containing different thickeners on the physical characteristics of a nanocomposite resin submitted or not to accelerated artificial aging (AAA).

Materials and Methods:

One hundred samples were randomly distributed into two groups (n = 50) according to AAA. Each group was divided into 5 subgroups (n = 10) depending on the bleaching/thickener treatment: CP + carbopol, CP + natrosol, carbopol, natrosol, and no treatment (control). The physical properties tested were color (ΔE), gloss (GU), mean roughness (Ra), and Knoop microhardness (KHN). The resin surface was performed with atomic force microscopy (AFM).

Statistical Analysis:

The color (variable Δ E) was assessed with two-way analysis of variance (ANOVA) and additionally with Tukey's and Dunnett's tests, the roughness values were submitted to Kruskal–Wallis, Dunn's, and Mann–Whitney's tests. Data on gloss and KHN were submitted to two-way ANOVA and Tukey's test (α = 0.05).

Results:

Among the physical properties evaluated, CP + carbopol promoted a reduction in composite microhardness only, thus differing statistically from the controls. As for CP + natrosol, such a change was not observed. The aging process reduced all the physical properties, thus differing statistically from the nonaging group. CP + carbopol increased the roughness and decreased the gloss of aged resins, whereas natrosol reduced gloss only, which differed statistically from the controls.

Conclusions:

AFM showed evidence of the loss of organic matrix and exposure to load particles in the aged samples. Therefore, the replacement of carbopol with natrosol provided maintenance of the composite microhardness following bleaching. The aging process reduced the physical properties evaluated, and some changes were enhanced by the application of bleaching.

Tooth enamel properties and morphology after microabrasion: an in situ study

AIM

This study evaluated the effect of saliva on enamel after microabrasion with different microabrasive compounds under in situ conditions.

METHODS

Enamel/dentin blocks (16 mm² ) from bovine incisors were divided into nine groups (n = 19): one control group (no treatment), four groups treated with microabrasion using 35% phosphoric acid (H₃ PO₄ ) + pumice, and the last four groups treated with microabrasion using 6.6% hydrochloric acid (HCl) + silica. The treated groups were subdivided according to the in situ regimen: without salivary exposure, 1 h, 24 h, or 7 days of saliva exposure. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were tested. Scanning electron microscopy (SEM) was used to evaluate enamel morphology. Microhardness data were tested by analysis of variance, and Tukey's and Dunnett's tests (α = 0.05).

RESULTS

The SMH analysis revealed that all the microabrasion-treated groups presented significantly-reduced SMH values when compared to the control group (P < 0.05). Treatment with HCl + silica was more prone to the effect of saliva than H₃ PO₄ + pumice, even for CSMH analysis, once the superficial layers reached the same microhardness of that of the control group (P > 0.05). These results were confirmed by SEM, which demonstrated the mineral recovery effect over time.

CONCLUSION

Saliva was effective in promoting the rehardening of enamel after microabrasion, mainly for the surfaces treated with HCl + silica.

In vitro evaluation of the effect of different polishing techniques on the surface roughness of composite resins submitted to at-home and in-office bleaching procedures

Objective:

Bleaching agents may affect the properties of dental materials. The aim of this study was to evaluate the effect of different polishing techniques on the surface roughness of composite resins submitted to the at-home and in-office bleaching treatment.

Materials and Methods:

Disc-shaped specimens were carried out of nanofilled and microhybrid composites (n = 10). Finishing step was performed after light curing (L1) and polishing after 24 h with two systems (L2). Then, specimens were submitted to the home or in-office bleaching procedures, and roughness was re-evaluated (L3). The surface roughness (Ra) readings were measured at L1, L2, and L3 times using a profilometer. Data were statistically analyzed by multiple-way analysis of variance and Tukey test (α = 0.05).

Results:

The polishing procedures decreased Ra for both composites compared to baseline values (L1). The roughness of specimens polished with jiffy did not present significant difference after polishing step (L2) and bleaching treatment (L3). However, the groups polished with Sof-Lex discs had increase on the Ra values after bleaching.

Conclusion:

The polishing is an important procedure to reduce the roughness of dental restorations and composite surface polished with jiffy system improved the degradation resistance to the bleaching agents compared to Sof-Lex discs.

Effect of Toothpaste Application Prior to Dental Bleaching on Whitening Effectiveness and Enamel Properties

OBJECTIVE

The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching.

METHODS

Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α<0.05). The relationship between the physical surface properties and color properties was evaluated using a multivariate Canonical correlation analysis.

RESULTS

Color changes were statistically similar in the bleached groups. After treatments, SMH and CSMH decreased in PC. SMH increased significantly in the toothpaste groups vs the negative and positive control (NM > PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH).

CONCLUSION

The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious effects of dental bleaching.

Effect of 7.5% hydrogen peroxide containing remineralizing agents on hardness, color change, roughness and micromorphology of human enamel

PURPOSE

To determine the microhardness, color change, surface roughness, and micromorphology of tooth enamel submitted to bleaching treatment with 7.5% hydrogen peroxide (HP) with added calcium, amorphous calcium phosphate, sodium fluoride (NaF), and hydroxyapatite (HA).

METHODS

80 enamel slabs were used (n = 10). Three commercial agents [Pola Day 7.5%, Day White ACP 7.5% (DW-ACP), and White Class Calcium 7.5% (WC-Calcium)], three experimental (7.5% HP+NaF, 7.5% HP+HA, and 7.5% PH+NaF+HA), a positive control (with HP), and a negative control (without HP) groups were assessed. The commercial products were applied according to manufacturers' recommendations and the experimental ones were applied for 1.5 hours daily. During and after treatment, specimens were stored in artificial saliva. Tests were performed at baseline, 7, 14, 21, 28, and 35 days. Data were analyzed by ANOVA and Tukey's test (α = 0.05).

RESULTS

DW-ACP presented lower microhardness and HP+HA presents the highest values (P < 0.05); only the experimental group presented color change similar to the commercial agents (P > 0.05). Overall, roughness increased with time (P < 0.05) and porosities, and deposition of crystalline structures in groups HP+HA and HP+NaF+HA were noted. The HP+HA agent was capable of reducing the loss of enamel microhardness due to bleaching and also present color change similar to the commercial products.

Adhesive Restorations as An Esthetic Solution in Dentinogenesis Imperfecta

Loss of tooth structure is the main sequela of dentinogenesis imperfecta (DI). Due to severe enamel attrition, patients with DI often present with esthetic, occlusal, endodontic, and speech complications. Therefore, an interdisciplinary approach, divided into separate clinical steps, should be developed to provide comprehensive dental rehabilitation. The purpose of this case report is to discuss the use of composite resin restorations as a transitional treatment step for the anterior teeth of an eight-year-old boy with DI until his bone and dental development permit orthodontic and orthognatic surgery.

Influence of Staining Solution and Bleaching on Color Stability of Resin Used for Caries Infiltration

OBJECTIVE

The objective of this study was to evaluate the color stability of Icon-infiltrated white spot lesions after staining and the bleaching effect on the infiltrated and stained surfaces.

METHODS AND MATERIALS

Enamel-dentin specimens (N=30, 5 × 5 × 3 mm, 1-mm enamel + 2-mm dentin thickness) were prepared from bovine incisors and randomly allocated into three groups (n=10): control, demineralized, and infiltrated. Artificial enamel subsurface lesions were created using 50 mL of 0.05 M acetate buffer solution. Specimens were produced by Icon application in enamel caries-like lesions, according to the manufacturer's instruction. Baseline color readings were assessed using a spectrophotometer, and CIE L*a*b* measurements of each specimen were performed using a white background. To simulate extrinsic dietary staining, specimens were placed into a 4-mL coffee infusion, three times daily for 15 minutes, for 14 days. After the staining procedure, color measurements were performed again. Then, bleaching procedures were performed using 16% carbamide peroxide gel for four hours daily for 21 days, and a final color assessment was performed. To compare the baseline and final measurements, t-test was used (α =0.05). The statistical comparison between the groups was performed using the one-way analysis of variance and Tukey tests (α =0.05).

RESULTS

Coffee staining provided a significant reduction of L* values and an increase of a* and b* in all groups (control, decayed, and infiltrated). The bleaching procedure provided a significant increase in L* and decrease of a* and b* values in all groups. There was no significant difference in ΔE values between decayed and infiltrated groups before bleaching, and after bleaching, the infiltrated group showed the lowest ΔE values.

CONCLUSION

It can be concluded that enamel infiltrated with Icon presents significant alteration of color after staining when compared with sound enamel. However, if there is discoloration of the infiltrant, the bleaching treatment can be used successfully.

Enamel morphology after microabrasion with experimental compounds

BACKGROUND

Enamel microabrasion is an esthetic treatment for removing superficial stains or defects of enamel.

AIM

This study evaluated the roughness after enamel microabrasion using experimental microabrasive systems.

MATERIALS AND METHODS

One hundred and ten samples (5 × 5 mm) were obtained from bovine incisors and divided into 11 groups (n = 10) in accordance with the treatment: Microabrasion using 6.6% hydrochloric acid (HCl) or 35% phosphoric acid (H3PO4) associated with aluminum oxide (AlO3) or pumice (Pum) with active application (using rubber cup coupled with a micro-motor of low rotation) or passive application (just placing the mixture on the enamel surface); just the use of acids in a passive application (negative control), and a group without treatment (positive control). Roughness analysis was performed before and after treatments. The statistical analysis used analysis of variance (PROC MIXED), Tukey-Kramer and Dunnet tests (P < 0.05). Representative specimens were evaluated using scanning electron microscopy (SEM).

RESULTS

There was no significant difference between the acids used (P = 0.0510) and the applications (P = 0.8989). All of the treated groups were statistically different from the positive control. When using passive application, the use of HCl + AlO3 resulted in higher roughness when compared with HCl + Pum. Additionally, this treatment was statistically different from the passive application of H3PO4 (negative control) (P < 0.05). However, SEM analysis showed that the treatment with AlO3 resulted in an enamel surface with a more polished aspect when compared with Pum.

CONCLUSION

AlO3 may be a suitable particle for use in microabrasive systems.

Influence of successive light-activation on degree of conversion and Knoop hardness of the first layered composite increment

PURPOSE

To evaluate the influence of light-activation of second, third and fourth increments on degree of conversion (DC) and microhardness (KHN) of the top (T) and bottom (B) surface of the first increment.

MATERIALS AND METHODS

Forty samples (n = 5) were prepared. In groups 1-4, after each increment light-activation (multiple irradiation), T and B of the first increment were measured in DC and KHN. In groups 5-8, only the first increment was made (single irradiation) and measurements of DC and KHN were taken at 15 min intervals. The light-activation modes were (XL) 500 mW/cm(2) × 38 s (G1/G5); (S) 1000 mW/cm(2) × 19 s (G2/G6), (HP) 1400 mW/cm(2) × 14 s (G3/G7); (PE) 3200 mW/cm(2) × 6 s (G4/G8). Data for DC and KHN were analyzed separately by using PROC MIXED for repeated measures and Tukey-Kramer test (α = 0.05).

RESULTS

For KHN, B showed lower values than T. PE resulted in lower values of KHN in B surface. For single and multiple irradiations, T and B of first measurement showed the lowest KHN and the fourth measurement showed the highest, with significant difference between them. For single irradiation, first and second increments presented similar KHN, different from the third and fourth increment, which did not differ between them. For multiple irradiations, the second light-activation resulted in KHN similar to first, third and fourth increments. For DC, except QTH, T presented higher DC than B.

CONCLUSION

The light-activation of successive increments was not able to influence the KHN and DC of the first increment.