Clinical and preclinical evidence on the bioeffects and movement-related implications of photobiomodulation in the orthodontic tooth movement: A systematic review.

Photobiomodulation (PBM) has been demonstrated as a non-invasive and painless technique with great potential to accelerate orthodontic tooth movement (OTM). However, there is a great inconsistency among PBM protocols and reported outcomes, probably due to the poor translatability of preclinical knowledge into early clinical practice. Hence, this review aims to fill this gap by establishing the state-of-the-art on both preclinical and clinical applications of PBM, and by comprehensively discussing the most suitable stimulation protocols described in the literature. This review was conducted according to PRISMA guidelines. A bibliographic search was carried out in the PubMed, Scopus and Cochrane databases using a combination of keywords. Only studies written in English were eligible and no time limit was applied. A total of 69 studies were selected for this review. The revised literature describes that PBM can effectively reduce orthodontic treatment time and produce analgesic and anti-inflammatory effects. We found that PBM of 640 ± 25, 830 ± 20 and 960 ± 20 nm, delivered at a minimum energy density per irradiation point of 5 J/cm2 daily or every other day sessions is robustly associated with increased tooth movement rate. Pain relief seems to be achieved with lower irradiation doses compared to those required for OTM acceleration. For the first time, the bioeffects induced by PBM for the acceleration of OTM are comprehensively discussed from a translational point of view. Collectively, the evidence from preclinical and clinical trials supports the use of PBM as a coadjuvant in orthodontics for enhancing tooth movement and managing treatment-associated discomfort. Overall, the revised studies indicate that optimal PBM parameters to stimulate tissue remodelling are wavelengths of 830 ± 20 nm and energy densities of 5-70 J/cm2 applied daily or every other day can maximize the OTM rate, while lower doses (up to 16 J/cm2 per session) delivered in non-consecutive days seem to be optimal for inducing analgesic effects. Future research should focus on optimizing laser parameters and treatment protocols customized for tooth and movement type. By fine-tuning laser parameters, clinicians can potentially reduce treatment times, improve patient comfort and achieve more predictable outcomes, making orthodontic care more efficient and patient-friendly, thus consolidating PBM usage in orthodontics.

Zirconia Dental Implants Surface Electric Stimulation Impact on Staphylococcus aureus.

Tooth loss during the lifetime of an individual is common. A strategy to treat partial or complete edentulous patients is the placement of dental implants. However, dental implants are subject to bacterial colonization and biofilm formation, which cause an infection named peri-implantitis. The existing long-term treatments for peri-implantitis are generally inefficient. Thus, an electrical circuit was produced with zirconia (Zr) samples using a hot-pressing technique to impregnate silver (Ag) through channels and holes to create a path by LASER texturing. The obtained specimens were characterized according to vitro cytotoxicity, to ensure ZrAg non-toxicity. Furthermore, samples were inoculated with Staphylococcus aureus using 6.5 mA of alternating current (AC). The current was delivered using a potentiostat and the influence on the bacterial concentration was assessed. Using AC, the specimens displayed no bacterial adhesion (Log 7 reduction). The in vitro results presented in this study suggest that this kind of treatment can be an alternative and promising strategy to treat and overcome bacterial adhesion around dental implants that can evolve to biofilm.

Surface modification of zirconia or lithium disilicate-reinforced glass ceramic by laser texturing to increase the adhesion of prosthetic surfaces to resin cements: an integrative review.

OBJECTIVE: The purpose of this study was to perform an integrative review on laser texturing the inner surface of lithium disilicate-reinforced glass ceramic or zirconia to increase their bond strength to resin-matrix cements. MATERIALS AND METHOD: A bibliographic review was performed on PubMed using the following search terms: "zirconia" OR "lithium disilicate" AND "laser" AND "surface" OR "roughness" AND "bond strength" AND "luting agent" OR "resin cement." Studies published in English language until March 15, 2023, were selected regarding the purpose of this study. RESULTS: A total of fifty-six studies were identified althoug thirteen studies were selected. The findings revealed that zirconia surfaces were significantly modified after laser irradiation resulting in macro-scale aligned retentive regions with depth values ranging from 50 to 120 µm. Average roughness values of laser-textured zirconia by Er,Cr:YSGG laser (~ 0.83 µm) were quite similar when compared to grit-blasted zirconia surfaces (~ 0.9 µm) although roughness increased up to 2.4 µm depending on the laser type and parameters. Lithium disilicate-reinforced glass ceramics textured with Er:YAG revealed an average roughness of around 3.5 µm while surfaces textured using Nd:YAG laser revealed an average roughness of 2.69 µm; that was quite similar to the roughness values recorded for etched surfaces (2.64 µm). The shear bond strength (SBS) values of zirconia surfaces textured on Nd:YVO4 laser irradiation were slightly higher (~ 33.5 MPa) than those recorded for grit-blasted zirconia surfaces (28 MPa). Laser-textured zirconia surfaces on CO2 laser revealed higher SBS values (18.1 ±0.8 MPa) than those (9.1 ± 0.56 MPa) recorded for untreated zirconia surfaces. On lithium disilicate-reinforced glass ceramics, higher SBS values to resin-matrix cements were recorded for specimens textured with a combination of fractional CO2 laser irradiation and HF acid etching (~ 22-24 MPa) when compared with grit-blasted specimens (12.2 MPa). Another study revealed SBS values at around 27.5 MPa for Er:YAG-textured lithium disilicate-reinforced glass ceramics to resin-matrix cements. CONCLUSIONS: The laser irradiation at high power increases the roughness of the inner surface of lithium disilicate-reinforced glass ceramic or zirconia leading to an enhanced bond strength to resin-matrix cements. Thus, the laser type and irradiation parameters can be adjusted to enhance the macro- and micro-scale retention of zirconia and glass ceramic surfaces to resin-matrix cements. CLINICAL RELEVANCE: Alternative methods for surface modification of lithium disilicate-reinforced glass ceramic and zirconia surfaces have been assessed to provide proper morphological aspects for enhanced adhesion to resin-matrix cements. An increase in the bond strength of glass ceramics or zirconia to resin-matrix cements can improve the long-term performance of cemented prosthetic structures in the oral cavity.

Root canal disinfection and maintenance of the remnant tooth tissues by using grape seed and cranberry extracts.

The purpose of this study was to perform an integrative review on the effects of cranberry and grape seed extracts concerning the disinfection of root canals maintaining the strength of the remnant tooth tissues' structure. A bibliographical search was carried out on the PubMed electronic platform using the following key terms: cranberry, grape seed, vaccinium macrocarpon, proanthocyanidin, antibacterial, antimicrobial, decontamination, disinfection, bacteria removal, bacteria eradication, bacteria elimination, endodontic, root canal, faecalis, and strength. The inclusion criteria involved articles published in the English language, until March, 2022, reporting the antibacterial effect of grape seed and cranberry extracts. Of 185 studies identified, 13 studies were selected for the present review. The grape seed extract (GSE), composed of proanthocyanidins, showed an antioxidant activity against the main bacteria found in endodontic secondary infection. The percentage of bacteria removal was recorded at around 96.97% by using GSE. Studies on cranberry extracts, which are composed of proanthocyanidins, revealed antimicrobial effects against bacteria related to periodontitis and dental caries. Additionally, GSE or cranberry allowed the dentin collagen cross-linking that preserved the 3D collagen network leading to the maintenance of the strength of the remnant tooth structure. However, the contaminated smear layer could not be removed by using only GSE or cranberry. Cranberry extracts and GSE revealed a significant antimicrobial activity in endodontic disinfection without changing the mechanical properties of the remnant dentin tissues. Furthermore, those components can be associated with traditional compounds to enhance their antimicrobial effects and eliminate the smear layer.

Toxicity of resin-matrix cements in contact with fibroblast or mesenchymal cells.

The main aim of this study was to perform an integrative review on the toxic effects of resin-matrix cements and their products in contact with fibroblasts or mesenchymal cells. A bibliographic search was performed on PubMed using the following search terms: "cytotoxicity" AND "fibroblast" OR "epithelial" OR "mesenchymal" AND "polymerization" OR "degree of conversion" OR "methacrylate" OR "monomer" AND "resin cement" OR "resin-based cement". The initial search in the available database yielded a total of 277 articles of which 21 articles were included in this review. A decrease in the viability of mouse fibroblasts ranged between 13 and 15% that was recorded for different resin-matrix cements after light curing exposure for 20 s. The viability of human fibroblasts was recorded at 83.11% after light curing for 20 s that increased up to 90.9% after light curing exposure for 40 s. Most of the studies linked the highest toxicity levels when the cells were in contact with Bis-GMA followed by UDMA, TEGDMA and HEMA. Resin-matrix cements cause a cytotoxic reaction when in contact with fibroblasts or mesenchymal cells due to the release of monomers from the polymeric matrix. The amount of monomers released from the resin matrix and their cytotoxicity depends on the polymerization parameters.

Surface modification of zirconia dental implants by laser texturing.

The aim of this work was to perform an integrative literature review on the influence of laser irradiation on zirconia implants to enhance surface topographic aspects and the biological response for osseointegration. An electronic search was carried out on the PubMed database using the following search terms: "zirconia" AND "laser" AND "surface modification" OR "surface treatment" AND "dental implants" OR "bone" OR "osteoblast" OR "osseointegration." Of the identified articles, 12 studies were selected in this review. Results reported that the laser irradiation was capable of promoting changes on the zirconia surfaces regarding topographic aspects, roughness, and wettability. An increase in roughness was recorded at micro- and nano-scale and it resulted in an enhanced wettability and biological response. Also, adhesion, spreading, proliferation, and differentiation of osteogenic cells were also enhanced after laser irradiation mainly by using a femtosecond laser at 10nJ and 80 MHz. After 3 months of osseointegration, in vivo studies in dogs revealed a similar average percentage of bone-to-implant contact (BIC) on zirconia surfaces (around 47.9 ± 16%) when compared to standard titanium surfaces (61.73 ±16.27%), denoting that there is no significant difference between such different materials. The laser  approach revealed several parameters that can be used for zirconia surface modification such as irradiation intensity, time, and frequency. Laser irradiation parameters can be optimized and well-controlled to reach desirable surface morphologic aspects and biological response concerning the osseointegration process.

The influence of inorganic fillers on the light transmission through resin-matrix composites during the light-curing procedure: an integrative review.

PURPOSE: The objective of this study was to perform an integrative review on the effect the inorganic fillers on the light transmission through the resin-matrix composites during the light-curing procedure. METHOD: A bibliographic review was performed on PubMed using the following search terms: "fillers" OR "particle" AND "light curing" OR "polymerization" AND "light transmission" OR "light absorption" OR "light irradiance" OR "light attenuation" OR "light diffusion" AND "resin composite." The search involved articles published in English language in the last 10 years. RESULTS: Selected studies reported a decrease in biaxial strength and hardness in traditional resin-matrix composites in function of the depth of polymerization. However, there were no significant differences in biaxial strength and hardness recorded along the polymerization depth of Bulk-Fill™ composites. Strength and hardness were enhanced by increasing the size and content of inorganic fillers although some studies revealed a progressive decrease in the degree of conversion on increasing silica particle size. The translucency of glass-ceramic spherical fillers promoted light diffusion mainly in critical situations such as in the case of deep proximal regions of resin-matrix composites. CONCLUSIONS: The amount of light transmitted through the resin-matrix composites is influenced by the size, content, microstructure, and shape of the inorganic filler particles. The decrease of the degree of conversion affects negatively the physical and mechanical properties of the resin-matrix composites. CLINICAL RELEVANCE: The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization. As a consequence, the clinical performance of resin-matrix composites can be compromised leading to variable physical properties and degradation. The polymerization mode of resin-matrix composites can be improved according to the type of inorganic fillers in their chemical composition.

Surface modification of glass fiber-reinforced composite posts to enhance their bond strength to resin-matrix cements: an integrative review.

BACKGROUND: Endodontically treated teeth usually can reveal an extensive loss of dental structure and require the use of intraradicular posts to provide adequate support and retention. Retention of the post depends on the surface treatment of the endodontic post itself and on the root canal dentin as well as on the type of resin-matrix cement. PURPOSE: The main aim of this study was to conduct an integrative review on the influence of different surface treatment methods of glass fiber-reinfored resin composite (GFRC) posts on their push-out bond strength to resin-matrix cements in endodontically treated teeth rehabiliation. METHOD: A literature search was performed on PubMed (via National Library of Medicine) regarding articles published within the last 10 years, using the following combination of search terms: "intracanal post" OR "endodontic post" OR "root canal post" OR "intraradicular post" OR "glass fiber" AND "resin cement" AND "adhesion" OR "bond strength" OR "shear bond strength" OR "push out". RESULTS: Results from the selected studies recorded the highest push-out bond strength around 22.5 MPa) on GFRC posts to resin-matrix cements when the surfaces were pre-treated by grit-blasting with silicate followed by silane conditioning. However, high values of push-out bond strength (21.5 MPa) were also noticed for GFRC posts after etching with hydrogen peroxide followed by silance conditioning. Thus, the highest values of bond strength of endodontic posts to the resin-matrix cements were recorded when a combined physico-chemical approach was assessed. Non-treated surfaces showed the lowest bond strength values between 5 to and 9 MPa. Surface analyses of GFRC posts showed an increased roughness after grit-blasting or etching that promoted a mechanical interlocking of the adhesive and resin-matrix cements. CONCLUSION: The combined treatment of glass fiber-reinforced resin composite post surfaces by physical and chemical methods can promote the increase in roughness and chemical functionalization of the surfaces prior to cementation., That results in a high mechanical interlocking of the resin-matrix cements and a stable retention of the teeth root intracanal posts. CLINICAL RELEVANCE: Combining chemical and physical modification methods of surfaces can provide the most promising adhesion-enhancing pathways of GFRC posts to resin-matrix cements, that can decrease the risk of clinical failures by fracture and detachment of endodontic posts.

Cytotoxic effects of submicron- and nano-scale titanium debris released from dental implants: an integrative review.

OBJECTIVE: This integrative review aimed to report the toxic effect of submicron and nano-scale commercially pure titanium (cp Ti) debris on cells of peri-implant tissues. MATERIALS AND METHODS: A systematic search was carried out on the PubMed electronic platform using the following key terms: Ti "OR" titanium "AND" dental implants "AND" nanoparticles "OR" nano-scale debris "OR" nanometric debris "AND" osteoblasts "OR "cytotoxicity" OR "macrophage" OR "mutagenic" OR "peri-implantitis". The inclusion criteria involved articles published in the English language, until December 26, 2020, reporting the effect of nano-scale titanium particles as released from dental implants on the toxicity and damage of osteoblasts. RESULTS: Of 258 articles identified, 14 articles were selected for this integrative review. Submicron and nano-scale cp Ti particles altered the behavior of cells in culture medium. An inflammatory response was triggered by macrophages, fibroblasts, osteoblasts, mesenchymal cells, and odontoblasts as indicated by the detection of several inflammatory mediators such as IL-6, IL-1ß, TNF-α, and PGE2. The formation of a bioactive complex composed of calcium and phosphorus on titanium nanoparticles allowed their binding to proteins leading to the cell internalization phenomenon. The nanoparticles induced mutagenic and carcinogenic effects into the cells. CONCLUSIONS: The cytotoxic effect of debris released from dental implants depends on the size, concentration, and chemical composition of the particles. A high concentration of particles on nanometric scale intensifies the inflammatory responses with mutagenic potential of the surrounding cells. CLINICAL RELEVANCE: Titanium ions and debris have been detected in peri-implant tissues with different size, concentration, and forms. The presence of metallic debris at peri-implant tissues also stimulates the migration of immune cells and inflammatory reactions. Cp Ti and TiO2 micro- and nano-scale particles can reach the bloodstream, accumulating in lungs, liver, spleen, and bone marrow.

The resin-matrix cement layer thickness resultant from the intracanal fitting of teeth root canal posts: an integrative review.

OBJECTIVE: The aim of this study was to perform an integrative review on the layer thickness and microstructure of resin-matrix cements around custom-made or standard teeth root intracanal posts. MATERIALS AND METHODS: An electronic search was conducted on the PubMed using a combination of the following scientific terms: intraradicular post, root intracanal post, resin cement, thickness, adaptation, endodontic post, layer thickness, fit, shape, and endodontic core. The literature selection criteria accepted articles published in the English language, up to May 2021, involving in vitro analyses, meta-analyses, randomized controlled trials, and prospective cohort studies. RESULTS: The search identified 154 studies, of which 24 were considered relevant to this study. The selected studies provided important data considering cement layer thickness, tooth preparation, endodontic post, and type of resin-matrix cement. The anatomical variability of root canal systems, such as the oval- or C-shaped, represents a challenge in dental restoration with tooth root intracanal posts. The fitting of intracanal posts to different root regions is variable resulting in thick and irregular layers of resin-matrix cement. Defects like pores, micro-cracks, and micro-gaps were detected in the resin-matrix cement microstructure and represent spots of stress concentration and fracture. Custom-made tooth root intracanal posts provide a proper fitting and decrease the layer thickness of resin-matrix cement. CONCLUSIONS: In fact, the layer thickness of resin-matrix cements depends on the fitting of endodontic posts to tooth root canals. An increase of resin cement thickness causes the appearance of defects like pores, micro-cracks, and micro-gaps that can induce stress concentration and fractures at interfaces. CLINICAL RELEVANCE: The fitting of the endodontic post into the teeth root canal determine the layer thickness of the resin-matrix cement to establish an adequate retention. However, the increase in the thickness of the resin-matrix cement layer can lead to a high number of defects like pores or cracks and therefore decrease the strength of the interface.

The influence of zirconia veneer thickness on the degree of conversion of resin-matrix cements: an integrative review.

OBJECTIVE: The main aim of this study was to conduct an integrative review on the influence of the zirconia veneer thickness on the degree of conversion of resin-matrix cements. MATERIALS AND METHOD: An electronic search was performed on PubMed using a combination of the following search items: zirconia, thickness, veneer, degree of conversion, resin cement, light curing, and polymerization. Articles published in the English language, up to July 2020, were included regarding the influence of ceramic veneer thickness on the degree of conversion of resin-matrix cements. Randomized controlled trials and prospective cohort studies were also evaluated. RESULTS: Of the 21 selected studies, 9 investigated the light-curing effect, while five other articles evaluated the ceramic translucency. Three studies evaluated the degree of conversion of the resin-matrix cement while four articles assessed the veneer thickness. Results revealed a significant decrease of light transmission through the zirconia with a thickness ranging from 0.1 up to 1.5 mm. However, the ultra-thin thickness around 0.1 and 0.3 mm allowed a full polymerization of the dual-curing resin-matrix cement resulting in the integrity of the interface properties. The light-curing process of resin-matrix cements is also affected by the shade, chemical composition, and microstructure of zirconia and resin cement. Optimal conditions of light-curing are required to reach the threshold intensity of light and energy for polymerization of resin-matrix cements. CONCLUSIONS: The increase in zirconia veneer thickness negatively affects the degree of conversion of resin-matrix cements. Also, shade and microstructure are key factor to improve the light curing of resin cements. CLINICAL RELEVANCE: Clinicians should consider the zirconia thickness on resin-based cementation since a higher veneer thickness can negatively affect the light irradiation intensity towards the dual-curing resin-matrix cement. Thus, the degree of conversion of the resin-matrix cement can decrease leading to a low chemical stability (e.g., color instability) and poor mechanical properties.

Bioactive-Enhanced Polyetheretherketone Dental Implant Materials: Mechanical Characterization and Cellular Responses.

The aim of this study was to characterize the mechanical properties of a bioactive-modified polyetheretherketone (PEEK) manufacturing approach for dental implants and to compare the in vitro biological behavior with titanium alloy (Ti6Al4V) as the reference. PEEK, PEEK with 5% hydroxyapatite (HA), PEEK with 5% beta-tricalcium phosphate (ßTCP), and Ti6Al4V discs were produced using hot pressing technology to create a functionally graded material (FGM). Surface roughness values (Ra, Rz), water contact angle, shear bond strength, and Vickers hardness tests were performed. Human osteoblasts and gingival fibroblasts bioactivity was evaluated by a resazurin-based method, alkaline phosphatase activity (ALP), and confocal laser scanning microscopy (CLSM) images of fluorescent-stained fibroblasts. Morphology and cellular adhesion were confirmed using field emission gun-scanning electron microscopy (FEG-SEM). Group comparisons were tested using analysis of variance (Tukey post hoc test), α = .05. All groups presented similar roughness values (P > .05). Ti6Al4V group was found to have the highest contact angle (P < .05). Shear bond strength and Vickers hardness of different PEEK materials were similar (P > .05); however, the mean values in the Ti6Al4V group were significantly higher when compared with those of the other groups (P < .05). Cell viability and proliferation of osteoblast and fibroblast cells were higher in the PEEK group (P < .05). PEEK-ßTCP showed the highest significant ALP activity over time (P < .05 at 14 days of culture). An enhanced bone and soft-tissue cell behavior on pure PEEK was obtained to the gold standard (Ti6Al4V) with equivalent roughness. The results substantiate the potential role of chemical composition rather than physical properties of materials in biological responses. The addition of 5% HA or ßTCP by FGM did not enhance PEEK mechanical properties or periodontal cell behavior.

Scaffolds and coatings for bone regeneration.

Bone tissue has an astonishing self-healing capacity yet only for non-critical size defects (<6 mm) and clinical intervention is needed for critical-size defects and beyond that along with non-union bone fractures and bone defects larger than critical size represent a major healthcare problem. Autografts are, still, being used as preferred to treat large bone defects. Mostly, due to the presence of living differentiated and progenitor cells, its osteogenic, osteoinductive and osteoconductive properties that allow osteogenesis, vascularization, and provide structural support. Bone tissue engineering strategies have been proposed to overcome the limited supply of grafts. Complete and successful bone regeneration can be influenced by several factors namely: the age of the patient, health, gender and is expected that the ideal scaffold for bone regeneration combines factors such as bioactivity and osteoinductivity. The commercially available products have as their main function the replacement of bone. Moreover, scaffolds still present limitations including poor osteointegration and limited vascularization. The introduction of pores in scaffolds are being used to promote the osteointegration as it allows cell and vessel infiltration. Moreover, combinations with growth factors or coatings have been explored as they can improve the osteoconductive and osteoinductive properties of the scaffold. This review focuses on the bone defects treatments and on the research of scaffolds for bone regeneration. Moreover, it summarizes the latest progress in the development of coatings used in bone tissue engineering. Despite the interesting advances which include the development of hybrid scaffolds, there are still important challenges that need to be addressed in order to fasten translation of scaffolds into the clinical scenario. Finally, we must reflect on the main challenges for bone tissue regeneration. There is a need to achieve a proper mechanical properties to bear the load of movements; have a scaffolds with a structure that fit the bone anatomy.

First report of Spirocerca vulpis in red foxes (Vulpes vulpes) in Portugal.

Recent studies have described Spirocerca lupi-like nematodes in the stomach of red foxes (Vulpes vulpes) in Europe. A phylogenetic analysis of those specimens using mitochondrial DNA and their morphological reexamination allowed their characterization as a different species, Spirocerca vulpis. Between the years of 2010 and 2017, roundworms were collected from seven red foxes of northeastern Portugal found at necropsy with nodular lesions on their stomach wall. Histopathological analysis of four foxes revealed granulomatous lesions of the gastric nodules. On morphological assessment, by light microscopy, nematodes revealed the presence of six triangular teeth-like buccal capsule structures, which are absent in S. lupi. Polymerase chain reaction was run to amplify a 551 bp partial fragment of the cytochrome c oxidase subunit 1 gene. Sequences were 99% similar to S. vulpis (85% coverage) of red foxes from Spain and Bosnia and Herzegovina, 99% similar (99% coverage) to sequences of Spirocerca sp. of red foxes from Denmark and 93% similar (99% coverage) to S. lupi from South Africa. This is the first report of S. vulpis in foxes or any other host from Portugal.

Laser Nd:YAG patterning enhance human osteoblast behavior on zirconia implants.

Zirconia has been regarded as a promising material for dental implants, and Nd:YAG laser treatment has been proposed as a potential strategy to improve its bioactivity. The main aim of the present study was to evaluate the in vitro behavior of human fetal osteoblasts in contact with laser-textured zirconia implant surfaces assessing the effect of different texture patterns, spacing between laser passes and number of laser passes. Zirconia discs were produced and treated with Nd:YAG laser according to test group variables: texture (microgrooves and micropillar array), distance between surface features (25 µm, 30 µm and 35 µm), and laser passes [1, 2, 4, and 8]. Untextured sandblasted and acid-etched zirconia discs (SBAE) were used as controls. Human osteoblasts (hFOB 1.19) were cultured for 14 days on test and control samples. Morphology and cellular adhesion were observed using scanning electron microscopy (SEM). Cell viability and proliferation were evaluated at 1, 3, 7, and 14 days using a commercial resazurin-based method. Collagen type I was evaluated at 3 days using ELISA. Alkaline phosphatase (ALP) activity was evaluated at 7 days using a colorimetric enzymatic technique. Group comparisons were tested using ANOVA or Mann-Whitney test (Tukey's post hoc) using statistical software, and significance was set at p < 0.05. Cell viability and proliferation increased over time for all groups with statistically higher values for laser-textured groups when compared with control at 7 and 14 days in culture (p < 0.05). Collagen type I levels were higher for study groups (p < 0.05) when compared with control group. No statistically differences were detected for ALP activity levels between texture and control groups (p > 0.05). The results suggest that laser-machined zirconia implant surfaces may benefit biological osteoblast response. However, the type of texture, spacing at the range of 25-35 µm, and number of laser passes did not seem to be relevant variables.

Surface damage of dental implant systems and ions release after exposure to fluoride and hydrogen peroxide.

OBJECTIVE: The aim of this study was to evaluate surface changes on dental implant systems and ions release after immersion in fluoride and hydrogen peroxide. METHODS: Ten implant-abutment assemblies were embedded in acrylic resin and cross-sectioned along the implant vertical axis. Samples were wet ground and polished. Delimited areas of groups of samples were immersed in 1.23% sodium fluoride gel (F) or in 35% hydrogen peroxide (HP) for 16 min. Gels (n = 3) were collected from the implant surfaces and analyzed by inductively coupled plasma mass spectrometry (ICP-MS), to detect the concentration of metallic ions released from the implant systems. Selected areas of the abutment and implant (n = 15) were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). RESULTS: SEM images revealed surface topographic changes on implant-abutment joints after immersion in fluoride. Implants showed excessive oxidation within loss of material, while abutment surfaces revealed intergranular corrosion after immersion in fluoride. ICP-MS results revealed a high concentration of Ti, Al, V ions in fluoride after contact with the implant systems. Localized corrosion of implant systems could not be detected by SEM after immersion in hydrogen peroxide although the profilometry showed increase in roughness. ICP-MS showed the release of metallic ions in hydrogen peroxide medium after contact with dental implants. CONCLUSION: Therapeutical substances such as fluorides and hydrogen peroxide can promote the degradation of titanium-based dental implant and abutments leading to the release of toxic ions.

Evaluation of the color and translucency of glass-infiltrated zirconia based on the concept of functionally graded materials.

STATEMENT OF PROBLEM: Infiltrated zirconia has promising mechanical properties. However, information about its optical behavior is scarce. PURPOSE: The purpose of this in vitro study was to evaluate the color and translucency of zirconia submitted to infiltration and aging. MATERIAL AND METHODS: Sixty zirconia disks were machined. Ten disks received no treatment (NT group), 10 disks were immersed in a coloring liquid (A2 group), and 10 disks were immersed in a fluorescent liquid (F group). The other 30 disks were submitted to the same treatments plus glass infiltration (NT+I, A2+I, and F+I groups). The coordinates L*, a*, and b* and the Y tristimulus values were obtained to calculate the color (ΔE00), lightness, chroma, and hue differences; the translucency parameter (TP); and the contrast ratio (CR) associated with the specimens. After aging in an autoclave for 4 hours (T1), new measurements were made. Two- and 3-way ANOVAs were used to analyze color differences, TP, and CR. The lightness, chroma, and hue differences were evaluated by a repeated measures ANOVA. Multiple comparisons were made with the Tukey honestly significant difference (HSD) test (α=.05). RESULTS: The greatest color differences were observed in the A2+I group (11.23 ΔE00) (P<.001). Aging affected the chroma of the colored groups (P=.013 and P=.001) but did not affect their translucency (P=.347 for TP and P=.132 for CR). The greatest TP values were found in the NT and NT+I groups (2.54 and 2.34, respectively), whereas the CR was equal to or close to 1 in all groups. CONCLUSIONS: Color differences were observed in the glass-infiltrated groups. The TP and CR were affected by infiltration. Aging did not influence the optical behavior of the specimens.

Fluorescence of natural teeth and restorative materials, methods for analysis and quantification: A literature review.

OBJECTIVE: This review integrates published scientific information about the fluorescence of natural teeth, dental resins and ceramics, and the main methods of analysis and quantification presented in the literature. OVERVIEW: Fluorescence is an emission of light (photons) by a substance that has absorbed light of higher energy. In natural teeth, it is more intense in the dentin than in the enamel and presents a bluish-white color. In dental resins and ceramics, fluorescence is obtained by the incorporation of materials that contain rare-earth luminescence centers (more precisely lanthanide luminescence centers), which allows these artificial materials to simulate natural teeth in a more beautiful and vital-looking way. However, the lack of knowledge about this optical phenomenon on the part of professionals indicates the need for more scientific studies and dissemination on this topic. CONCLUSIONS: Aesthetic materials have variable spectral compositions and fluorescence intensities, which are not always compatible with natural teeth. The fluorescence of teeth and restorative materials can be influenced by several factors, such as aging, temperature, and bleaching. Several devices for fluorescence evaluation and quantification are used in studies under different methodologies, but the small number of studies on the subject make it difficult to compare their results. CLINICAL SIGNIFICANCE: Fluorescence is a fundamental optical property for aesthetic rehabilitations since its presence and intensity in the restorative materials allows achieving an aesthetic result much closer to reality. However, the fluorescent behavior of natural teeth and aesthetic restorative materials is not yet fully understood by researchers and clinicians. Greater understanding of this phenomenon will contribute to the selection, indication, and clinical use of these materials.

Color stability of a bis-acryl composite resin subjected to polishing, thermocycling, intercalated baths, and immersion in different beverages.

OBJECTIVE: To evaluate the color of a bis-acryl resin after polishing, aging, and colorants. MATERIALS AND METHODS: From the 140 disks obtained, 35 were not polished (NP), 35 were polished with 3-µm (3P), 35 with 3- and 1-µm (1P), and 35 with 3-, 1-, and 0.5-µm sized particles (05P). Five disks of each group were thermocycled for 20, 100, and 200 cycles. Sixty disks were thermocycled and kept in beverages (tea, wine, and coffee) after four cycles. Sixty disks were immersed in the beverages for 24 hours, a week, and a month. The coordinates L*a*b* were measured and the color differences were analyzed by ANOVA. The lightness, chroma, and hue differences were evaluated by repeated measures ANOVA. Comparisons were made with Tukey's test (α = 0.05). RESULTS: Similar behaviors were observed between 3P and 05P groups (1.53 and 1.95ΔE00 ) (P < .05). The NP group submitted to 200 cycles showed the biggest color differences (3.02) (P = .003). The greatest color differences were observed in the NP group submitted to immersion in coffee (8.30) and wine (7.93) (P < .05). CONCLUSIONS: The polished surfaces were the least stained. Coffee and wine provided the greatest color changes, both for baths and immersions. CLINICAL SIGNIFICANCE: Polishing of provisional surfaces restorations made of bis-acrylic resin is essential to minimize staining caused by aging and use of colorants, regardless of the particle size present in the polishing paste. The contact with coffee and red wine should be avoided, especially for clinical times greater than 1 week.

Wear of Morse taper and external hexagon implant joints after abutment removal.

The aim of this in vitro study was to evaluate the removal torque values on abutments and the morphological wear aspects of two different dental implant joints after immersion in a medium containing biofilm from human saliva. Twenty implant-abutment assemblies were divided into four groups in this study: (A) Morse taper free of medium containing biofilm, and (B) after contact with a medium containing biofilm from human saliva; (C) External Hexagon free of medium containing biofilm, and (D) after contact with medium containing biofilm from human saliva. The abutments were firstly torqued to the implants according to the manufacturer´s recommendations, using a handheld torque meter. Groups B and D were immersed into 24 well-plates containing 2 ml BHI medium with microorganisms for 72 h at 37 °C under microaerophilic conditions. After detorque evaluation, the abutments were removed and the implants were analyzed by scanning electron microscopy (SEM) and profilometry. On the detorque evaluation, the torque values decreased for the external hexagon implants and increased for the Morse taper implants. However, the values were lower when both implant-abutment assemblies were in contact with a medium containing biofilm from human saliva. The wear areas of contacting surfaces of the implants were identified by SEM. The highest average roughness values were recorded on the surfaces free of biofilm. The medium containing biofilm from human saliva affected the maintenance of the torque values on Morse taper and external hexagon abutments. Additionally, the removal of abutment altered the inner implant surfaces resulting in an increase of wear of the titanium-based connection.