Júlio C. M. Souza

The main aim of this study was to perform a systematic review on the detection of submicron-scale titanium debris at peri-implant tissues focusing on the a

Purpose: The aim of this study was to evaluate the cytocompatibility of micro- and nano-scale commercially pure Titanium (cpTi) particles in contact with fibroblasts and keratinocytes and the penetration of cpTi particles across keratinocytes' layers. Method: Commercially pure titanium (cp-Ti) particles with 50-nm or 1-µm size were chemically and morphologically characterized using a Field Emission Guns Electron Microscopy (FEGSEM), Scanning Transmission Electron Microscope (STEM), and Energy Dispersion Spectrometry (EDAX). Then, the cytotoxic profile of the particles was monitored in contact with murine L929 fibroblasts and TR146 keratinocytes for 1, 4, and 7 days. Further permeability assays were performed across a TR146 monolayer via Transwell^TM model. Results: Physicochemical characterization of cpTi nano-scale particles (cpTi NPs) revealed a mean size at 70 nm and a specific surface area at around ~ 17.2 m²/g, while micro-scale particles (cpTi MP) size ranged from 0.3 up to 5.3 μm with a mean size of 1.4 μm at dry conditions. The optimized de-agglomeration of nanoparticles resulted in an increased specific surface area up to 57.3 m²/g. The metabolic activity of fibroblasts decreased against 50 or 100 µg/ml cpTi over 3 days cell culture while keratinocytes were not affected. Moreover, cpTi NP were internalized and steadily translocated into keratinocyte monolayers, showing an apparent permeability coefficient of 6.65 × 10⁻⁶ cm/s for 50 µg/mL and 3.96 × 10⁻⁶ cm/s for 100 µg/mL. Conclusions: Altogether, nano-scale titanium particles decreased the viability of fibroblasts although a significant viability of keratinocytes has been detected by standard cell culture assays. However, nano-scale titanium particles were found into keratinocytes and even trespassed the cells' layers that could reach other cells and blood vessels in an in vivo scenario. Thus, toxicity of titanium particles depends on their particle size, exposure time, content, and interaction with the surrounding media. Graphical

Purpose of the Review: The purpose of this study was to perform a scoping review on the comparison between tooth-derived matrix and demineralized bovine bone mineral (DBBM) granules for enhanced bone healing. Recent Findings: Previous studies reported micro-scale pores in dentin-matrix granules due to the remnant dentin that promote the adsorption of proteins and bioactive molecules. It should be highlighted the remnant dentin is an intrinsic source of collagen and growth factors such as TGF-1, BMP-2, VEGF, and PDGF. The DBBM showed macro-scale interconnected pores which enhances the adhesion of cells and formation of new blood vessels. DBBM also revealed a porosity of around 80% and a lower resorption rate when compared to tooth-derived granules. On in vivo models, dentin-matrix granules induced quite similar results for bone growth when compared to grafting with DBBM as confirmed by histological analyses. Summary: The dentin-derived matrix granules showed morphological aspects and chemical composition suitable for enhancing bone repair comparable to the effects of deproteinized bovine bone mineral granules. The adequate space among particles and size of pores plays a key role in the events of bone formation since the protein adsorption towards the bone growth. Also, a well-adjusted content of DBBM and dentin-derived granules in the mixture maintains the bone volume over the bone healing. Thus, autologous dentin-derived granules are alternative materials for bone healing without any adverse inflammatory reactions.

The aim of this study was to perform a systematic review to comprehensively explore the factors contributing to the resin-matrix composites′ toxicity in patients. A systematic review was performed according to the PRISMA guidelines. The bibliographic review was performed in the following databases: PubMed, Cochrane Central and Web of Science. Inclusion and exclusion criteria were established to retrieve articles published in English over the last 20 years. The research yielded 1261 articles, with 1227 articles remaining after removing duplicates. Following a title and abstract screening, 20 articles underwent full-text review, and 12 in vivo studies were included. Detectable levels of free monomers and potential toxicity exposure were reported in the selected studies on saliva, urine, and blood samples. The selected in vivo studies suggest relatively low local and systemic toxicity although the available methods show technical limitations and therefore further studies are required. Dental operator-dependent factors were also identified. Standard chair-side guidelines on handling of resin-matrix composites placement plays a key role on the properties of the materials. The results reported noticeable changes in samples were not considered significant to affect patient's health, although, manufacturer’s instructions must be followed whilst using resin-matrix composites. In fact, adequate light curing parameters maintain a high degree of conversion of the resin-matrix composites decreasing the release of residual monomers and thus the probability of related toxicity.

In the present in vitro study, we evaluated the adhesion of an injectable platelet-rich fibrin (i-PRF) to laser-textured zirconia surfaces and their resultant friction behavior against bone tissue. Three types of zirconia surfaces were compared regarding the i-PRF coating effects: 1) grit blasted with 250-μm spherical alumina particles and acid etched with 20% hydrofluoric acid (ZLA), 2) laser textured with a random (RD) surface pattern, or 3) laser textured with a designed pattern based on 16 lines and 8 passages (L16N8). The coefficient of friction (COF) of the specimens was assessed on a reciprocating sliding pin-on-plate tribometer at 1-N normal load, 1 Hz, and a 2-mm stroke length. Sliding wear tests were carried out against bovine femoral bone tissue in 0.9% sodium chloride solution at room temperature. Surfaces were then assessed by scanning electron microscopy. COF mean values for test groups (0.35, ZLA; 0.45, L16N8) were lower when compared with the control groups (0.52, ZLA; 0.60, L16N8), with the exception of the RD group (0.47, test; 0.43, control). Results did not show significant differences in COF mean values between RD and L16N8 surfaces after coating with i-PRF. The 3-dimensional fibrin network embedded with leukocytes, platelets, and red blood cells was responsible for decreasing COF mean values over the zirconia surfaces, thus providing a lubricant effect. Also, the morphologic aspects of the laser-treated zirconia surfaces increased the adhesion of the platelet-rich fibrin, which could speed up the osseointegration process of zirconia implants.

On the rehabilitation of endodontic treated teeth using intraradicular retention, adhesive failures often occur between the intraradicular post and the resin-matrix cement. The main aim of this study was to conduct a scoping review on the surface modification of glass fiber-reinforced composite posts by hydrogen peroxide solutions. An electronic search was performed in the PubMed database, using combinations of keywords pursuing articles published between 2010 and 2024 in English language. Of the 13 selected studies, 12 investigated the bond strength between the glass fiber-reinforced composite (GFRC) post and the resin-matrix cement after the surface treatment of the post, 5 articles analyzed failures using a stereomicroscope, and 7 studies analyzed the surface topography by scanning electron microscopy (SEM). Etching procedures with hydrogen peroxide (H₂O₂) altered the surface of the GFRC post by selectively dissolving the matrix without damaging the fibers, resulting in a larger surface area of exposed fibers available to react with the adhesive system or silane. Studies revealed high bond strength values between the etched GFRC posts to the resin-matrix materials. Surface treatment of GFRC posts with hydrogen peroxide seems promising considering the feasibility on the surface modification resulting in the improvement of bond strength of intraradicular posts to resin-matrix cements.

Purpose: The main aim of the present study was to carry out a scoping review on the differences in degree of conversion of monomers regarding several types resin cements, indirect restorative materials, and light-curing procedures used in dentistry. Method: A bibliographic review was performed on PubMed using the following search items: “degree of conversion” OR “filler” AND “resin cement” OR “inorganic cement” AND “organic” OR “radiopacity” OR “refractive” OR “transmittance” OR “type” AND “resin composite.” The search involved articles published in English language within the last thirteen years. A research question has been formulated following the PICO approach as follow: “How different is the degree of conversion of monomers comparing several types of resin-matrix cements?”. Results: Within the 15 selected studies, 8 studies reported a high degree of conversion (DC) of the organic matrix ranging from 70 up to 90% while 7 studies showed lower DC values. Dual-cured resin-matrix cements revealed the highest mean values of DC, flexural strength, and hardness when compared with light- and self-polymerized ones. DC mean values of resin-matrix cements light-cured through a ceramic veneer with 0.4 mm thickness were higher (~ 83%) than those recorded for resin-matrix cements light-cured through a thicker ceramic layer of 1.5 mm (~ 77%). Conclusions: The highest percentage of degree of conversion of monomers was reported for dual-cured resin-matrix cements and therefore both chemical and light-induced pathways promoted an enhanced polymerization of the material. Similar degree of conversion of the same resin-matrix cement were recorded when the prosthetic structure showed a low thickness. On thick prosthetic structures, translucent materials are required to allow the light transmission achieving the resin-matrix cement. Clinical relevance: The chemical composition of resin-matrix cements and the light-curing mode can affect the polymerization of the organic matrix. Thus, physical properties of the materials can vary leading to early clinical failures at restorative interfaces. Thus, the analysis of the polymerization pathways of resin-matrix cements is significantly beneficial for the clinical performance of the restorative interfaces.

The purpose of the present study was to perform a preliminary analysis of the fitting of different fiber-reinforced composite (GFRC) posts to tooth root canals and determine the resin cement layer thickness. The following GFRC posts were assessed: bundle posts (Rebilda GT^TM, VOCO, Germany), sleeve system (SAP^TM, Angelus Ind, Brazil), and accessory posts (Reforpin^TM, Angelus, Brazil). Twenty-four freshly extracted mandibular single-rooted pre-molars were endodontically treated and divided into six groups, according to the type of GFRC post and resin cement (self-adhesive or conventional dual-cured). Then, specimens were cross-sectioned and inspected by optical microscopy regarding the cement layer thickness and presence of defects such as pores, voids, or fissures were assessed. Bundle and accessory posts revealed a regular distribution of resin cement with a lower number of voids than found with sleeve systems. The sleeve system posts showed poor fitting at the apical portion of the root canals. The type of resin cement did not affect the thickness of the interface, although both bundle and accessory posts allow a better distribution of resin cement and fibers. The present preliminary study reveals interesting insights on the fitting of bundle and accessory posts to root dentin and resin cement layer thickness in oval-shape root canals. The sleeve system posts showed adequate fitting only at the coronal portion of the canals.