Influence of thickness and restorative system on the mechanical behavior of CAD/CAM minimally invasive occlusal veneers - in vitro study.

AIM: The aim of this study was to evaluate the physical-mechanical behavior of the occlusal veneers when subjected to thermomechanical cycling. MATERIALS AND METHODS: Sixty specimens were divided into 04 groups (n=15 per group), according with the different restorative materials and thicknesses: material - lithium dissilicate LD (IPS e.max CAD, Ivoclar Vivadent) and nano- ceramic-resins NCR (ESPE Lava Ultimate, 3M); thickness - 0.6 and 1.2mm. The occlusal veneers were bonded over human flattened fresh extracted molars with dual-polymerizing luting agent (Variolink N, Ivoclar Vivadent and RelyX Ultimate 3M) using the respective adhesive system following the selective-etch technique (self-etch in dentin and total etch in enamel). The resin cement was light cured for 40 seconds each face, using a LED light cure equipment (BlueStar II, Microdont, 1100 mW/cm2). The response variables consisted of veneer survival rates (crack formation, catastrophic cracks and debonding) when subjected to thermal cycling from 5° to 55° C and simultaneous mechanical cycling performed at load intensities of 100, 200, 300, 400 and 450N for 20,000 cycles each. RESULT: Data were submitted to the Kruskall Wallis test and Pairwise Comparison, adopting a significance level of 5%. NCRs presented a lower incidence of failures (p<0.05) when compared to LD. According to thickness factor, 1.2mm thick occlusal veneers withstand higher cycling loads. CONCLUSION: NCR occlusal veneers with 1.2mm thickness presented superior physical-mechanical behavior than lithium disilicate and 0.6mm restorations.

The stamp technique for direct restoration in a ICDAS 4 carious lesion: A 4-year follow-up.

OBJECTIVE: This case report described the use of a stamping technique associated with a bulk fill composite to restore an ICDAS 4 carious lesion on a posterior tooth. The 4-year follow-up is also presented. CLINICAL CONSIDERATIONS: A 32-year-old patient presented a carious lesion on tooth 36 with an underlying dark shadow at the dentin seen from the noncavitated enamel occlusal surface, which was compatible with an ICDAS 4 carious lesion. The lesion was radiographically detected and the caries disease was treated with dietary and hygiene habits orientations. Before accessing the lesion and selectively removing the carious tissue, an occlusal stamp was made by applying a flowable resin composite to copy the anatomy of the noncavitated enamel surface. The cavity was restored using a bulk fill resin composite (Opus Bulk Fill, FGM) with 4-mm-thick increments. Before curing the last increment, a Teflon band was adapted at the uncured bulk fill composite surface and the occlusal stamp made with the flowable composite was pressed against it to reproduce the natural characteristics and initial occlusal anatomy. The top surface was light-activated for 40 s. After 4 years, small wear could be seen in the restoration, but still within clinically acceptable levels. CONCLUSION: The occlusal stamp technique allows reproduction of the natural anatomy of teeth affected by ICDAS 4 carious lesions with good clinical longevity over 4 years. CLINICAL SIGNIFICANCE: This case report presents the use of the stamp technique to restore a tooth affected by an ICDAS 4 lesion, in which a carious process reached the dentin and the enamel anatomy was still preserved. The bulk fill resin composite associated with the occlusal stamp was chosen to quickly restore the cavity with clinical predictability. Bulk fill composites allow the insertion of up to 4-mm-thick increments and offer lower shrinkage stress, good clinical longevity and a less time-consuming procedure in cases of posterior teeth, especially if associated with the stamp technique.

Effects of radiant exposure and distance on resin-based composite polymerization.

PURPOSE: To evaluate the hardness profile of three resin-based restorative composites (RBC) (Filtek Z250XT, Filtek One Bulk Fill, Filtek Bulk Fill Flow) polymerized by a multi-wave curing light. METHODS: Specimens (n= 12) were prepared by inserting 2 mm RBC increments into a split-mold and polymerized from the top using either 20- or 40-second exposure times. Specimen curing was performed directly at a 1 mm distance (control-group) or through an ivorine-tooth slot preparation at a 5 mm distance (experimental-group). Specimens were stored (37 ± 1°C/24 hours), then subjected to Knoop indenter (25g/5 seconds). Specimens' KHN values were obtained from the upper and lower surfaces. Relative hardness (RH) (lower-to-upper ratio) was calculated for each specimen. Data were analyzed with three-way ANOVA and Tukey's HSD (α= 0.05). RESULTS: There was no significant RH difference among RBCs in the control group, regardless of the exposure time (P> 0.05). Average RH ratios for all RBCs tested in this group were greater than 0.80. However, the average RH values of the experimental RBC group were significantly lower. The RH for Z250 was 0.39 in the 20-second group, while RH was 0.63 in the 40-second group. BF had an RH ratio of 0.70 in the 20-second and 0.72 in the 40-second group, while One Bulk had a ratio of 0.65 in the 20-second and 0.71 in the 40-second groups. Doubled exposure time substantially increased RH of all tested materials at a 1 mm tip-to-material distance. Clinically relevant 5 mm light-tip to material-surface distance significantly reduced polymerization efficacy of RBC specimens, regardless of the exposure time. CLINICAL SIGNIFICANCE: Adequate light-polymerization of resin-based direct restoratives is necessary for long-term clinical success. Polymerizing Class 2 restorations is challenging due to a hard-to-reach location and an increased distance between the light source and the restorative material. Insufficient polymerization is often seen at the bottom of the proximal box of the Class 2 cavity, with a detrimental effect on restoration longevity.

Radiant-exposure attenuation through Class-2 proximal slots.

PURPOSE: To determine the extent of radiant exposure (RE) attenuation of three LED light-polymerization units (LPUs), and their beam-profile, at the bottom of the Class-2 slot, using MARC-PS. METHODS: 10 seconds RE was delivered to MARC-PS' anterior sensor by Bluephase-Style, Demi-Plus, and Deep-Cure-S. Two ivorine lower first-molars received Class-2 proximal box preparations: (3×2×4 mm and 4×4×4 mm) and were sectioned horizontally above the cementoenamel junction. Tofflemire matrix-retainer was placed around each tooth and secured with a low-fusing compound. Each LPU tested delivered 10 seconds RE to MARC-PS through proximal slots. Mean RE of three readings per group was obtained. Data were analyzed using Pearson correlation, mixed ANOVAs with a pre-set alpha of 0.05. RESULTS: RE attenuation ratio calculated from the baseline to 4× 4×4/3×2×4 Class-2 boxes were: 58.25/80.03 Bluephase-Style; 49.36/80.25 Demi-Plus; 32.8/77.43 Deep-Cure-S. A significant and strong correlation (r= 0.86, P< 0.001) between the reduction in aperture size and RE was found. The beam profile of LED-LPUs tested decreased RE values at the bottom of a proximal box. More than 80% RE value reduction from the baseline to the smallest Class-2 cavity 3×2×4 aperture was observed. CLINICAL SIGNIFICANCE: Polymerization of resin-composites at the bottom of the Class-2 box is challenging due to the small aperture size, depth, and hard-to-reach location. Inadequate polymerization at the bottom of the Class-2 proximal box is a causative factor for secondary caries and, ultimately, restoration failure.

Effect of different beverages and storage period on bis-acryl color stability using two assessment methods.

OBJECTIVE: This study aimed to evaluate the color stability (ΔE00 ) of bis-acryl resins after different immersion solutions and storage time by different evaluation methods. MATERIALS AND METHODS: Sixty specimens (n = 30) were prepared from Protemp 4 and Structur 3. The specimens were divided into three groups (n = 10), according to the immersion solution (artificial saliva, cola beverage, and yerba mate tea) and evaluated at two storage times (7 and 14 days). The ΔE00 of each group was calculated using color coordinates obtained by a spectrophotometer and by a digital method, using the CIEDE2000 color difference formula. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). RESULTS: The 7-day period presented the lowest ΔE00 values, regardless of the material and solution evaluated for both evaluation methods (ΔE00 < 0.93; ΔE00 < 3.12). The immersion solution with the highest color change was yerba mate tea after 14 days (ΔE00 > 2.11). For digital analyses, all materials and solutions at both times presented ΔE00 values higher than the clinically acceptable (ΔE00 > 1.8), while in spectrophotometer only in yerba mate tea (14 days) Structur was above the clinical acceptability level. CONCLUSIONS: Yerba mate tea was the immersion solution with a higher color change in both materials and assessment methods. The highest values were found after 14 days of immersion, regardless of the solution. The ΔE00 for the digital method was higher than the spectrophotometer analysis. CLINICAL SIGNIFICANCE: It is important to identify the influence of staining beverages on interim materials used in patients requiring temporary rehabilitation. The use of a spectrophotometer seems to be more accurate than the digital method for the evaluation of color parameters of the tested materials.

Physical and surface properties of a 3D-printed composite resin for a digital workflow.

STATEMENT OF PROBLEM: Information related to the optical and surface properties, including health compatibility, surface roughness, and esthetics, of 3D-printed dental materials is scarce. PURPOSE: The purpose of this in vitro study was to compare the physical and surface properties of a 3D-printed resin with those of materials used for interim restorations. MATERIAL AND METHODS: A 3D-printed resin (PR) (NextDent C&B MFH; 3D Systems), an autopolymerizing interim material (BA) (Protemp 4; 3M ESPE), and a composite resin (Z350) (Filtek Z350XT; 3M ESPE) were tested for degree of color change (ΔE) (n=7) at different timepoints-24 hours after polishing/baseline (P0), 8 days after polishing (P1), and after artificial aging in water at 60 °C for 24 hours (P2)-by using a CIELab-based colorimeter; flexural strength (σ) (n=10) with a 3-point bend test; Knoop hardness (H) (n=8); and surface roughness (Ra) (n=7) with a profilometer. All specimens were polished 24 hours after polymerization, except for the additional group for surface roughness (BA) without polishing (BANP). A statistical analysis was performed by using 2-way repeated-measures ANOVA followed by the Fischer test for ΔE and 1-way ANOVA followed by the Fisher test for microhardness and surface roughness (α=.05). RESULTS: The Z350 showed the highest values for σ and H, followed by PR. BA showed the lowest results for both tests (P<.05). Considering roughness, the Z350 showed similar values to those of BA but lower than PR; PR showed similar roughness when compared with BA. PR showed the highest color variation among the groups at all timepoints, followed by BA. The Z350 was the most color stable material at all timepoints. CONCLUSIONS: The 3D-printed composite resin had adequate mechanical and surface properties for an interim restorative material. It has the potential to be a low-cost workflow in dentistry, although its color stability could be a concern for long-term use.

Influence of resin-coating agents on the roughness and color of composite resins.

STATEMENT OF PROBLEM: Resin-coating agents can be used to fill microstructural defects within composite resin restorations, which might result in a smoother surface. Nevertheless, data about the color stability and surface roughness of coated restorations are lacking. PURPOSE: The purpose of this in vitro study was to compare the surface roughness and color stability of restorations before and after application of different resin-coating agents. MATERIAL AND METHODS: Forty specimens of composite resin (Filtek Z250) (diameter×height, 6×2 mm) were divided into 5 groups according to the surface treatments (n=8 per group): control (CTR), Fortify (FT), Lasting touch (LT), BisCover (BIS), and Fill Glaze (FG). The specimens were evaluated for surface roughness by using a profilometer with 3 readings for each specimen (separated by 300 µm) before immersion in a staining solution (coffee) and after 5 days immersed in coffee and for color stability (▵E) by using a spectrophotometer before being immersed in coffee (initial reading) and after 6 hours, 12 hours, 1, 2, 3, 4, and 5 days. RESULTS: Two-way ANOVA with repeated measures and the Tukey test showed that the CTR group showed the highest roughness values, similar to those of the FT and LT groups. The BIS and FG groups showed lower roughness than the other groups but similar results when compared with each other. All groups, except LT, showed increased roughness values after immersion in coffee solution, and the BIS group showed the lowest variation over time. Color alterations were found for all groups, with the CTR group showing the lowest ▵E values when compared with the other groups except for the BIS group. No correlation was found between surface roughness and degree of color change (P=.401). CONCLUSIONS: The BisCover surface sealant showed the lowest surface roughness and the best color stability. Surface sealants can be used to fill microcracks and microgaps but should not be used as a substitute for polishing.

Management of dental caries guided by the ICDAS-LAA: a 28-month follow-up.

Dental caries is a significant oral health issue and public health concern. Currently conceptualized as a dynamic and multifactorial process, caries is a continuum of disease stages, during which tooth damage may be reversed or controlled, depending on lesion progression. The International Caries Detection and Assessment System, when used in conjunction with the Lesion Activity Assessment (ICDAS-LAA), reflects the dynamic caries process and allows the classification of cavitated lesions according to their severity and progression, which is essential to selecting the appropriate treatment. This case report describes the diagnosis and treatment of a patient who had caries in the past and in whom old lesions remained untreated. The ICDAS-LAA was used to assess caries accurately and guide treatment decisions. The patient maintained a dietary journal for 2 weeks to help establish her risk of developing caries. Treatment involved a minimally invasive dentistry approach, which consisted of remineralization via fluoride applications, placement of a composite resin restoration, microabrasion, and periodic maintenance. During the 28-month follow-up period, rigorous control of caries risk factors was achieved, and the results were satisfactory, demonstrating the effectiveness of the ICDAS-LAA in diagnosing and managing carious lesions.

Delayed Light Activation Improves Color Stability of Dual-Cured Resin Cements.

PURPOSE: To evaluate the color change caused by post-irradiation conversion (ΔE24h and ΔE8 days ) and artificial aging (ΔEAGING ) of resin cements light activated through ceramics of different opacities immediately and 6 minutes after manipulating the material. MATERIALS AND METHODS: Resin cement disks (Allcem and LuxaCore) were light activated through ceramics (without ceramic, e.max HT, LT, and MO) immediately and 6 minutes after the manipulation (n = 10). Spectrophotometry was used to evaluate ΔE24h and ΔE8 days after 37˚C-dry-dark-storage for 24 hours and 8 days, and ΔEAGING after 60˚C-water-storage for 24 hours. Data were analyzed with three-way ANOVA and Tukey's HSD (α = 0.05). RESULTS: Regarding the post-irradiation color change, significant differences were found between the cements (p < 0.0001), light activation protocols (p = 0.037), and ceramics (p < 0.001). The immediate activation (16.2 ± 0.1) showed lower ΔE values than the delayed activation (16.5 ± 0.1). Ceramics influenced the ΔE values as follows: MO (14.0 ± 1.2) < LT (14.9 ± 1.2) ≈ HT (15.4 ± 1.2) < control (21.2 ± 1.2). Regarding ΔEAGING , significant differences were found between cements (p < 0.001), light activation (p = 0.006), and ceramics (p < 0.001). The delayed activation (8.4 ± 0.1) showed lower values than the immediate activation (8.9 ± 0.1). Ceramic spacers influenced ΔEAGING as follows: control (5.6 ± 0.2) < MO (6.6 ± 0.2) < HT (11.0 ± 0.2) ≈ LT (11.5 ± 0.2). CONCLUSION: The delayed light activation resulted in increased color stability, while the ceramic interposition resulted in lower color stability.

Fracture strength of the remaining dental structure after different cavity preparation designs.

The aim of this in vitro study was to evaluate the loss of tooth structure after cavity preparation for direct (retentive) and indirect (nonretentive) restorations and its relationship to the fracture strength of the prepared tooth. Sound human third molars (60 maxillary and 60 mandibular) were randomly assigned into 12 groups (n = 10) according to the type of cavity preparation and the respective buccolingual width. Class II mesio-occlusodistal cavity preparations, for both indirect inlay and direct resin restorations, were prepared with standardized dimensions of one-half, one-third, or one-quarter of the occlusal intercuspal distance. Fracture resistance was lower and weight loss was greater for all nonretentive preparations. Greater losses in weight and fracture resistance occurred when the buccolingual width for both types of cavities increased, except for the weight loss of the one-quarter and one-third indirect cavity preparations in the mandibular molars, and the fracture resistance of the one-half and one-third direct cavity preparations in maxillary molars. Higher tooth structure loss and lower fracture strength were recorded after preparation of the inlay cavities.

Direct Composite Restorations to Mask Intrinsic Staining: An Eighteen-Year Follow-Up.

In this case example, the use of direct composite resin allowed for a relatively simple, conservative treatment that provided excellent function and aesthetics, while preserving healthy dental tissue. The importance of continued follow-up and a periodic maintenance and minor repair process will ensure longevity of the restorations, as aesthetics, and the occlusion.

Niobium oxyhydroxide as a bioactive agent and reinforcement to a high-viscosity bulk-fill resin composite.

OBJECTIVE: The present in vitro study incorporated niobium oxyhydroxide fillers into an experimental high-viscosity bulk-fill resin composite to improve its mechanical performance and provide it a bioactive potential. METHODOLOGY: Scanning electron microscopy synthesized and characterized 0.5% niobium oxyhydroxide fillers, demonstrating a homogeneous morphology that represented a reinforcement for the feature. Fillers were weighed, gradually added to the experimental resin composite, and homogenized for one minute, forming three groups: BF (experimental high-viscosity bulk-fill resin composite; control), BF0.5 (experimental high-viscosity bulk-fill resin composite modified with 0.5% niobium oxyhydroxide fillers), and BFC (commercial bulk-fill resin composite Beautifil Bulk U, Shofu; positive control). In total, 10 specimens/groups (8 × 2 × 2 mm) underwent flexural strength (FS) tests in a universal testing machine (Instron) (500N). Resin composites were also assessed for Knoop hardness (KH), depth of cure (DoC), degree of conversion (DC), elastic modulus (E), and degree of color change (ΔE). The bioactive potential of the developed resin composite was evaluated after immersing the specimens into a simulated body fluid in vitro solution and assessing them using a Fourier-transformed infrared spectroscope with an attenuated total reflectance accessory. One-way ANOVA, followed by the Tukey's test (p<0.05), determined FS, DC, KH, and ΔE. For DoC, ANOVA was performed, which demonstrated no significant difference between groups (p<0.05). CONCLUSIONS: The high-viscosity bulk-fill resin composite with 0.5% niobium oxyhydroxide fillers showed promising outcomes as reinforcement agents and performed well for bioactive potential, although less predictable than the commercial resin composite with Giomer technology.

A conservative treatment approach using direct composite resins for anterior teeth eroded by lemon sucking.

An excessively acidic diet results in the progressive deterioration of dental health, with functional, esthetic, and biological consequences. Previously, rehabilitation required placing numerous full crowns and root canal treatments; however, with improved adhesive techniques, a more conservative approach may be utilized to preserve tooth structure. This article describes 2 cases that utilized conservative dental treatments (involving direct composite resins with minimal preparation of the tooth structure) to treat eroded dentition induced by lemon sucking.

Effect of nanofibers as reinforcement on resin-based dental materials: A systematic review of in vitro studies.

This systematic review provides an update on the effect of nanofibers as reinforcement on resin-based dental materials. A bibliographic search was conducted in MEDLINEPubMed, Embase, Web of Science, Scopus, BVS (LILACS, BBO e IBECS), Cochrane, LIVIVO, and gray literature (BDTD) to identify relevant articles up to May 2021. In vitro studies that evaluated and compared the mechanical properties of nanofibers resin-based composite materials, were eligible. No publication year or language restriction was applied, and methodological quality was assessed using two methods. In a total of 6100 potentially eligible studies, 81 were selected for full-text analysis and 35 were included for qualitative analysis. Of the 35 included studies, a total of 29 studies evaluated the flexural strength (FS) of the materials. These groups were distinguished according to the resin-based materials tested and nanofiber types. Most of the studies evaluated materials composed of glass fibers and demonstrated higher values of FS when compared to resin-based materials without nanofibers. The incorporation of nanofibers into resin-based dental materials improved the mechanical properties compared to resin-based materials without nanofibers, suggesting better performance of these materials in high-stressbearing application areas. Further clinical studies are required to confirm the efficacy of resin-based materials with nanofibers.

Effects of hybrid inorganic-organic nanofibers on the properties of enamel resin infiltrants - An in vitro study.

This in vitro study aimed to evaluate the overall mechanical properties of resin infiltrants doped with bioactive nanofibers and their ability in inhibiting enamel demineralization or achieving remineralization of the adjacent enamel to white spots. A commercial resin infiltrant (ICON, DMG) was doped with hybrid inorganic-organic nanofibers and analyzed for degree of conversion (DC, n = 3) and surface hardness (SH, n = 6). Subsequently, enamel specimens (6 × 4 × 2 mm3) were prepared and submitted to a demineralizing/remineralizing process to produce a subsurface caries-like lesion. The specimens were treated with one of the following materials: ICON infiltrant, DMG (control); ICON + nanofibers of poly-lactic acid (PLA)-filled with silica (PLA-SiO2); ICON + nanofibers of (PLA)-filled with calcium incorporated into a silica network (SiO2-CaP). Then, the specimens were subjected to a pH-cycling demineralizing/remineralizing model for 7 days at 37 °C. The %ΔSH change (after treatment), %SH loss and %SH recovery (after pH-cycling regimen) were calculated after SH evaluation (n = 9/group). The Ca/P weight ratio before and after pH-cycling regimen was evaluated through SEM/EDX. The results of DC were analyzed through the T-test (p < 0.05). ANOVA followed by Tukey's test (p < 0.05) was performed for hardness and EDX. A significant SH increase was observed in the ICON/SiO2CaP group (p < 0.05). The ICON/PLA-SiO2 presented higher DC values than the control group (p = 0.043). All groups presented significant difference in %ΔSH (p < 0.05), although the specimens treated with ICON/SiO2CaP presented greater values. Regarding the %SHL and %SHR, the ICON/SiO2CaP and ICON/PLA-SiO2 were significantly different compared to the control group (p < 0.001). However, no difference was observed between the ICON/SiO2CaP and ICON/PLA-SiO2. The Ca/P ratio showed that the ICON/SiO2CaP and ICON/PLA-SiO2 after the pH-cycling regimen differed from sound enamel and modified infiltrants before pH-cycling. In conclusion, tailored hybrid nanofibers may be incorporated into enamel resin infiltrants without compromise the mechanical properties of such experimental materials. These latter can inhibit the demineralization of enamel and increase its hardness during pH-clycling challange.

Mechanical performance of a hybrid zirconia developed through hydrothermal treatment and Room-Temperature Atomic Layer Deposition (RT-ALD).

OBJECTIVE: A silica-based nanofilm has been successfully deposited via Room-Temperature Atomic Layer Deposition (RT-ALD) on the surface of a glass. The purpose of this study was to evaluate the mechanical performance of a hybrid interface created between yttria-stabilized zirconia (Y-PSZ) transformed layer and silica-based nanofilm via RT-ALD. MATERIAL AND METHODS: Fully-sintered Y-PSZ (14 × 4.0 × 1.5 mm) specimens in different translucencies (MO, MT, LT; IPS e.max Zircad, Ivoclar Vivadent) were distributed in 5 groups: control (C - no treatment); hydrothermal treatment (HT- 15h, 134°C, 2 bar); alumina blasting (B - 50 µm Al2O3); RT-ALD silica deposition (S); HT followed by silica deposition (HTS). RT-ALD cycles consisted of the sequential exposure of specimens to tetramethoxysilane orthosilicate (TMOS - 60s) and ammonium hydroxide (NH4OH - 10 min) vapors in 40 cycles. Mechanical performance was analyzed by flexural strength (FS) (n = 10) and fatigue failure load (staircase method; n = 20) tests. Surface hardness (H) and Young's modulus (YM) were analyzed by nanoindentation. For surface chemical and topographical characterization, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were performed. Data from surface H, YM, FS, and fatigue limit (FL) were analyzed by two-way analysis of variance (ANOVA). RESULTS: The interaction between material and treatment had a significant effect on FS (p < 0.001). The FS values ranged from 436.23 MPa to 856.65 MPa. HT resulted in the highest FS (856.65 MPa) for LT and the lowest FS (436.23 MPa) for MO zirconia. For all materials, S and B treatments resulted in similar FS values (p > 0.410). S did not affect FL when compared to the C group (p > 0.277) for any material investigated. HTS resulted in higher FL than S for LT and MO materials (p < 0.001). Surface hardness and modulus were similar between control and S-treated specimens for all materials analyzed. XPS analysis showed homogeneous silica content after 20 and 40 RT-ALD cycles, and SEM did not show significant changes in surface morphology between C and S-treated specimens. CONCLUSION: RT-ALD resulted in effective silica deposition without any deleterious effect on zirconia-based materials mechanical properties. Alumina blasting promoted higher alteration on surface topography. HT prior to S resulted in superior FL (for MO and MT) and flexural strength (MO) for some of the materials investigated.

In Vitro Evaluation of Desensitizing Agents Containing Bioactive Scaffolds of Nanofibers on Dentin Remineralization.

This study evaluated the effect of the incorporation of bioactive nanofibers in desensitizing agents on dentin permeability. Sixty disks of dentin were randomly distributed in four groups (n = 15). Distribution was based on the desensitizing agents, fluoride varnish and self-etching adhesive, and the presence of nanofibers: C (self-etching adhesive Clearfil SE Bond), CN (Clearfil SE Bond with 1% nanofiber), D (Duraphat varnish), and DN (Duraphat varnish with 1% nanofiber). Dentin permeability was determined using hydraulic conductivity. For a qualitative analysis, confocal laser microscopy and scanning electron microscopy were performed. The C group showed the lowest hydraulic conductance (Lp%) (89.33), while the DN group showed the highest Lp% (116.06). No statistical significance was observed in the Lp% values in all groups after the treatment and 6% citric acid challenge (p > 0.239). In the images, the CN group presented a higher superficial and intratubular deposition. In addition, this group presented a more homogeneous dentin surface and wide occlusion of dentinal tubules than the other treatments. Despite there being no statistical differences among the treatments employed, the images showed that the CN group presented a higher surface and intratubular deposition compared to the other treatments, even after the acid challenge.

Cephalometric and occlusal changes of Class III malocclusion treated with or without extractions.

OBJECTIVE: The aim of this retrospective study was to evaluate the cephalometric and occlusal changes of orthodontically treated Class III malocclusion patients. METHODS: The experimental groups comprised 37 Class III patients treated: G1) without (n=19) and G2) with extractions (n=18) . The control group (G3), matched by age and sex with the experimental groups, consisted of 18 subjects with untreated Class III malocclusion. Cephalometric (radiographs) and occlusal (study models) changes were assessed between the beginning (T1) and the end (T2) of treatment. Intergroup comparisons were performed with one-way ANOVA followed by Kruskal-Wallis tests (p< 0.05). Occlusal changes were evaluated by the peer assessment rating (PAR) index (ANOVA and Kruskal-Wallis tests), and the treatment outcomes were evaluated by the Objective Grading System (OGS) (t-tests). RESULTS: The experimental groups showed a restrictive effect on mandibular anterior displacement and a discrete improvement in the maxillomandibular relationship. Extraction treatment resulted in a greater retrusive movement of the incisors and significant improvements in the overjet and molar relationship in both groups. The PAR indexes were significantly reduced with treatment, and the OGS scores were 25.6 (G1) and 28.6 (G2), with no significant intergroup difference. CONCLUSIONS: Orthodontic treatment of Class III malocclusion patients with fixed appliances improved the sagittal relationships, with greater incisor retrusion in the extraction group. Both the extraction and non-extraction treatments significantly decreased the initial malocclusion severity, with adequate and similar occlusal outcomes of treatment.

Effect of cavosurface angle beveling on the exposure angle of enamel prisms in different cavity sizes.

The quality of the micromechanical retention between the enamel prisms exposed through acid etching and adhesive system can be influenced by the relationship between the angle of the exposed enamel prisms and the external surface/restorative material. Therefore, the aim of the present study was to determine the influence of the enamel cavosurface beveling in different cavity sizes on the angle relation between enamel prisms and the restorative material. For this research, 30 human permanent molars were used and divided into three groups according the isthmus aperture of class I cavities (1/4, 1/3, and 1/2 of the intercuspal distance). Cavosurface angle beveling was performed in each tooth buccal or palatal/lingual side, and a resin composite restoration was placed. Each restored tooth was sectioned in buccal/palatal direction followed by analysis in scanning electron microscope. Means of the angles observed between enamel prisms and the restorative material were registered and statistically analyzed by Kruskal-Wallis test. Results showed higher mean angle values for beveled groups when comparing with the values observed in the unbeveled margins (p < .05) regardless of the isthmus aperture, being 1/4 (beveled = 48.36°; unbeveled = 20.71°), 1/3 (beveled = 39.75°; unbeveled = 29.15°), and 1/2 (beveled = 37.02°; unbeveled = 26.34°). It was also observed that in some unbeveled cavities, there were the presence of laterally exposed enamel prisms (0°), mainly in more conservative cavities. It was concluded that the presence of higher angles values occurred in the samples with beveled margins, without presence of laterally exposed enamel prisms.

Effect of a resin-modified glass-ionomer with calcium on enamel demineralization inhibition: an in vitro study.

We assessed the effect of a new coating material based on resin-modified glass-ionomer with calcium (Ca) in inhibiting the demineralization of underlying and adjacent areas surrounding caries-like lesions in enamel. The measures used were surface hardness (SH) and cross-sectional hardness (CSH). Thirty-six bovine enamel specimens (3 × 6 × 2 mm) were randomly allocated into three groups (n = 12): No treatment (NT); resin-modified glass-ionomer with Ca (Clinpro XT Varnish, 3M ESPE) (CL), and fluoride varnish (Duraphat, Colgate) (DU). The specimens were subjected to alternated immersions in demineralizing (6 h) and remineralizing solutions (18 h) for 7 days. SH measurements were conducted at standard distances of 150, 300, and 450 µm from the treatment area. CSH evaluated the mean hardness profile over the depth of the enamel surface and at standard distances from the materials. The energy-dispersive X-ray spectroscopy analysis was conducted to evaluate the demineralization bands created on the sublayer by % of calcium (Ca), phosphorus (P), and fluoride (F). Ca/P weight ratio was also calculated. Based on SH and CSH measurements, there was no difference between groups at the distances 150 µm (p = 0.882), 300 µm (p = 0.995), and 450 µm (p = 0.998). Up to 50 µm depth (at 150 µm from the treatment area), CL showed better performance than DU ( p< 0.05). NT presented higher loss of Ca and P than CL and DU (p < 0.05). There was no significant difference in the % of F ion among the three groups. The new coating material was similar to F varnish in attenuating enamel demineralization.