Enhanced osteoinductive capacity of poly(lactic-co-glycolic) acid and biphasic ceramic scaffolds by embedding simvastatin.

OBJECTIVES: This study evaluated the effect of embedding simvastatin (SIM) on the osteoinductive capacity of PLGA + HA/ßTCP scaffolds in stem cells from human exfoliated deciduous teeth (SHED). MATERIALS AND METHODS: Scaffolds were produced by PLGA solvent dissolution, addition of HA/ßTCP, solvent evaporation, and leaching of sucrose particles to impart porosity. Biphasic ceramic particles (70% HA/30% ßTCP) were added to the PLGA in a 1:1 (w:w) ratio. Scaffolds with SIM received 1% (w:w) of this medication. Scaffolds were synthesized in a disc-shape and sterilized by ethylene oxide. The experimental groups were (G1) PLGA + HA/ßTCP and (G2) PLGA + HA/ßTCP + SIM in non-osteogenic culture medium, while (G3) SHED and (G4) MC3T3-E1 in osteogenic culture medium were the positive control groups. The release profile of SIM from scaffolds was evaluated. DNA quantification assay, alkaline phosphatase activity, osteocalcin and osteonectin proteins, extracellular calcium detection, von Kossa staining, and X-ray microtomography were performed to assess the capacity of scaffolds to induce the osteogenic differentiation of SHED. RESULTS: The release profile of SIM followed a non-liner sustained-release rate, reaching about 40% of drug release at day 28. Additionally, G2 promoted the highest osteogenic differentiation of SHED, even when compared to the positive control groups. CONCLUSIONS: In summary, the osteoinductive capacity of poly(lactic-co-glycolic) acid and biphasic ceramic scaffolds was expressively enhanced by embedding simvastatin. CLINICAL RELEVANCE: Bone regeneration is still a limiting factor in the success of several approaches to oral and maxillofacial surgeries, though tissue engineering using mesenchymal stem cells, scaffolds, and osteoinductive mediators might collaborate to this topic.

Three-dimensional bioactive hydrogel-based scaffolds for bone regeneration in implant dentistry.

Bone tissue requires a range of complex mechanisms to allow the restoration of its structure and function. Bone healing is a signaling cascade process, involving cells secreting cytokines, growth factors, and pro-inflammatory factors in the defect site that will, subsequently, recruit surrounding stem cells to migrate, proliferate, and differentiate into bone-forming cells. Bioactive functional scaffolds could be applied to improve the bone healing processes where the organism is not able to fully regenerate the lost tissue. However, to be optimal, such scaffolds should act as osteoconductors - supporting bone-forming cells, providing nutrients, and sustaining the arrival of new blood vessels, and act as osteoinducers - slowly releasing signaling molecules that stimulate mesenchymal stem cells to differentiate and deposit mineralized bone matrix. Different compositions and shapes of scaffolds, cutting-edge technologies, application of signaling molecules to promote cell differentiation, and high-quality biomaterials are reaching favorable outcomes towards osteoblastic differentiation of stem cells in in vitro and in vivo researches for bone regeneration. Hydrogel-based biomaterials are being pointed as promising for bone tissue regeneration; however, despite all the research and high-impact scientific publications, there are still several challenges that prevent the use of hydrogel-based scaffolds for bone regeneration being feasible for their clinical application. Hence, the objective of this review is to consolidate and report, based on the current scientific literature, the approaches for bone tissue regeneration using bioactive hydrogel-based scaffolds, cell-based therapies, and three-dimensional bioprinting to define the key challenges preventing their use in clinical applications.

Rehabilitation Challenge in Patient With a High Smile Line: Case Report and Review of Surgical Protocols.

INTRODUCTION: Defects in the maxillary anterior teeth are delicate and difficult to solve because of the esthetic, functional, and psychological impairment that may arise if the rehabilitation treatment does not return the damaged tissues to the naturalness. Esthetic predictability and reduced surgical interventions are some great reasons to simplify dental treatments. During the presurgical evaluation, the clinician should review the implant esthetic risk profile, considering the patient's smile line, the esthetic demands, the hard and soft tissue thickness and width, and the gingival biotype. Thus, achieving long-term esthetic results initiates with a detailed case planning before surgical intervention. CASE PRESENTATION: The present report described a complex esthetic clinical case involving teeth and dental implant related to a high smile line. The clinical case was solved through immediate implant placement and immediate loading using a personalized prosthetic abutment and finalized with the installation of metal-free prosthetic restorations. CONCLUSION: The use of a personalized prosthetic abutment helped to achieve a better emergence of the prosthesis under the periodontal tissues. Although it was a challenging esthetic case, especially because of the high smile line, the result was a natural smile while the adjacent soft tissues maintained their esthetics and health.

Multivariate analysis of the influence of peri-implant clinical parameters and local factors on radiographic bone loss in the posterior maxilla: a retrospective study on 277 dental implants.

OBJECTIVES: The aim of the present study was to investigate whether peri-implant clinical parameters (modified plaque index (mPI), bleeding and/or suppuration on probing (B/SOP)) and local factors (type of prostheses, screw emergence, platform diameter, and abutment angulation) might contribute to the development of additional bone loss and peri-implantitis around dental implants. MATERIALS AND METHODS: Two hundred seventy-seven external hex connection implants placed in the posterior maxilla of 124 patients were retrospectively evaluated. They were divided into two groups: physiologic bone loss < 2 mm (PBL) or additional bone loss ≥ 2 mm (ABL). GEE logistic regression was applied to evaluate the influence of type of prostheses (implant-supported single crown (ISSC), fixed partial denture (ISFPD), and full denture (ISFD)) and clinical parameters (mPI and S/BOP) on bone loss. RESULTS: Among the 277 implants, 159 (57.4%) presented PBL and 118 (42.6%) presented ABL. Within the ABL group, 20.6% implants were diagnosed with peri-implantitis. mPI significantly correlated with the type of prosthesis and the highest value of mPI (index = 3) was observed in ISFD (23.8%). Moreover, peri-implantitis was more frequently associated with ISFD (32.79%) than ISSC and ISFDP (13.79% and 13.48, respectively) CONCLUSIONS: ISFD in the posterior maxilla presented high rates of ABL and showed a higher prevalence of peri-implantitis. None of the local factors seemed to contribute to the development of these conditions. Further investigations are needed to prospectively support the results of the present study. CLINICAL RELEVANCE: Patients rehabilitated with ISFD should be carefully monitored and have more frequent maintenance visits to prevent or control peri-implant bone loss.

Titanium coated with poly(lactic-co-glycolic) acid incorporating simvastatin: Biofunctionalization of dental prosthetic abutments.

OBJECTIVE: To propose a biofunctionalized prosthetic abutment by analyzing physico-chemical and morphological properties, simvastatin (SIM) release, and biocompatibility of titanium (Ti) disks coated with poly(lactic-co-glycolic) acid (PLGA) incorporating SIM. METHODS: Titanium disks (8 × 3 mm) were distributed into four groups: Ti: pure Ti; Ti + PLGA: Ti coated with PLGA; Ti + PLGA + SIM6%: Ti + PLGA with 6% SIM; and Ti + PLGA + SIM0.6%: Ti + PLGA incorporating 0.6% SIM. PLGA was prepared through chloroform evaporation technique. After complete dissolution of PLGA, SIM was diluted in the solution. Ti + PLGA, Ti + PLGA + SIM6%, and Ti + PLGA + SIM0.6% were dip coated with PLGA and PLGA + SIM, respectively. Samples were sterilized by ethylene oxide. For SIM release assay, disks were submerged in PBS, pH 7.4, 37°C, 30 rpm up to 600 hours. At different time intervals, SIM was quantified by spectrophotometry (238 nm). For characterization of the biomaterial components, it was performed Fourier-transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy (SEM), optical profilometry, and atomic force microscopy. Biocompatibility analyses were performed by MTS colorimetric assay on murine fibroblasts L929, human gingival fibroblasts (HGFs), and stem cells from human exfoliated deciduous teeth (SHEDs). Absorbance was measured at 490 nm, and percentages of viable cells were calculated in relation to positive control (Ti). SEM images were obtained to verify cell adhesion and morphology. One-way ANOVA followed by Tukey's post hoc test was applied (P < 0.05) for statistical analyses. RESULTS: SIM release was slow and continuous, reaching about 21% of the incorporated SIM after 600 hours. Topographical analyses revealed success in coating Ti disks with PLGA incorporating SIM. Regarding biocompatibility test, Ti + PLGA + SIM0.6% showed the highest percentage of L929 viability at days 3 and 7. There was no significant difference for Ti, Ti + PLGA, and Ti + PLGA + SIM0.6% groups on cell viability of both SHEDs and HGFs at days 3 and 7. SEM corroborates that SHEDs and HGFs were able to adhere and proliferate on Ti, Ti + PLGA, and Ti + PLGA + SIM0.6% surfaces. CONCLUSION: A slow and controlled release of SIM was achieved, attributed to a diffusional mass transfer mechanism. Moreover, a homogenous coating topography was obtained. Additionally, 0.6% SIM incorporated into PLGA coating improved fibroblasts L929 viability compared to titanium or PLGA. Also, 0.6% SIM incorporated into PLGA promoted cell viability of about 100% for HGFs and approximately 150% for human mesenchymal stem cells. Therefore, this study allows to consider the use of PLGA-coated titanium incorporating SIM as a biofunctionalized abutment for dental implants.

Nano-scale modification of titanium implant surfaces to enhance osseointegration.

The main aim of this review study was to report the state of art on the nano-scale technological advancements of titanium implant surfaces to enhance the osseointegration process. Several methods of surface modification are chronologically described bridging ordinary methods (e.g. grit blasting and etching) and advanced physicochemical approaches such as 3D-laser texturing and biomimetic modification. Functionalization procedures by using proteins, peptides, and bioactive ceramics have provided an enhancement in wettability and bioactivity of implant surfaces. Furthermore, recent findings have revealed a combined beneficial effect of micro- and nano-scale modification and biomimetic functionalization of titanium surfaces. However, some technological developments of implant surfaces are not commercially available yet due to costs and a lack of clinical validation for such recent surfaces. Further in vitro and in vivo studies are required to endorse the use of enhanced biomimetic implant surfaces. STATEMENT OF SIGNIFICANCE: Grit-blasting followed by acid-etching is currently used for titanium implant modifications, although recent technological biomimetic physicochemical methods have revealed enhanced osteoconductive and anti-microbial outcomes. An improvement in wettability and bioactivity of titanium implant surfaces has been accomplished by combining micro and nano-scale modification and functionalization with protein, peptides, and bioactive compounds. Such morphological and chemical modification of the titanium surfaces induce the migration and differentiation of osteogenic cells followed by an enhancement of the mineral matrix formation that accelerate the osseointegration process. Additionally, the incorporation of bioactive molecules into the nanostructured surfaces is a promising strategy to avoid early and late implant failures induced by the biofilm accumulation.

Release of simvastatin from scaffolds of poly(lactic-co-glycolic) acid and biphasic ceramic designed for bone tissue regeneration.

The aim of this study was to evaluate the release of simvastatin from scaffolds composed of poly(lactic-co-glycolic) acid (PLGA) and biphasic ceramic designed for bone engineering and to assess the physico-chemical and mechanical properties of the scaffolds. Samples with 30% and 70% porosity were obtained with 0, 2, 5, and 8 wt %. of simvastatin through the solvent evaporation technique and leaching of sucrose particles. Scaffold degradation and simvastatin release were evaluated in phosphate-buffered saline. Scaffolds were analyzed by scanning electron microscopy and microtomography for two-dimensional and three-dimensional morphological characterization of the porosity, connectivity, and intrinsic permeability. The mechanical characterization was conducted based on the compressive strength and the chemical characterization by differential scanning calorimetry and energy dispersive X-ray spectroscopy. Gradual and prolonged simvastatin release from the scaffolds was observed. The release followed the Korsmeyer kinetics model with the predominance of case II transport for 30% porosity scaffolds, and anomalous behavior for the 70% porosity samples. Simvastatin release was also influenced by the slow scaffold degradation due to the strong chemical interaction between simvastatin and PLGA, as observed by differential scanning calorimetry. The scaffolds presented spherical and sucrose crystal-shaped pores that resulted in a homogenous porosity, with a predominance of open pores, ensuring interconnectivity. Simvastatin incorporation into the scaffolds and increased porosity did not influence the mechanical properties. The scaffolds presented gradual and prolonged simvastatin release, with satisfactory physico-chemical and mechanical properties. The scaffolds presented gradual and prolonged simvastatin release, with satisfactory physico-chemical and mechanical properties, a promise for applications in bone regeneration. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2152-2164, 2019.

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.

Custom-made root-analogue zirconia implants: A scoping review on mechanical and biological benefits.

The aim of this study was to conduct a literature review on the potential benefits of custom-made root-analogue zirconia implants. A PubMed and ScienceDirect bibliographical search was carried out from 1969 to 2017. The increased interest in zirconia-based dental structures linked to aesthetic and biological outcomes have been reported in literature. Recent technological advances have focused on novel strategies for modification of zirconia-based surfaces to accelerate osseointegration. However, only a few studies revealed mechanical and biological benefits of custom-made root-analogue zirconia implants and therefore further studies should investigate the influence of different design and surface modification on the performance of such implants. Custom-made root-analogue zirconia implants have become a viable alternative to overcome limitations concerning stress distribution, aesthetics, and peri-implantitis induced by biofilms. However, further in vitro and in vivo studies on surface-bone interactions and mechanical behavior of zirconia should be evaluated to reduce clinical issues regarding mechanical failures and late peri-implant bone loss. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2888-2900, 2018.

Mechanical integrity of cement- and screw-retained zirconium-lithium silicate glass-ceramic crowns to Morse taper implants.

STATEMENT OF PROBLEM: The improved esthetics of ceramic dental prostheses has increased their popularity, although their high elastic modulus and low fracture toughness and tensile strength may reduce the long-term performance of dental prostheses. PURPOSE: The purpose of this in vitro study was to assess the mechanical integrity of zirconium-lithium silicate glass-ceramic crowns cement- and screw-retained to a titanium implant-abutment after fatigue. MATERIAL AND METHODS: Forty titanium implants were placed in polyacetal to mimic bone support. Abutments were tightened to the implants to 20 Ncm by using a digital handheld torque meter. The implant abutment assemblies received a pressed maxillary premolar crown, either lithium disilicate (LD) or zirconium-lithium silicate glass-ceramic (LZS). The specimens (n=10) were subjected to fatigue at 200 N and 5 Hz for 500 000 cycles in a Ringer electrolytic solution (37°C). After fatigue, the crowns were removed to evaluate removal torque values on the implant-abutment connection. The remaining crown-implant-abutment assemblies were cross-sectioned at 90 degrees to the implant-abutment joint for inspection of cracks and the micro-gaps by scanning electron microscopy. RESULTS: Removal torque values before fatigue were recorded at 18 ±1.63 Ncm for the LD group and 18.2 ±0.81 Ncm for the LZS group. After fatigue, the removal torque values decreased significantly (12.8 ±1.6 Ncm for LD, 14.9 ±1.08 Ncm for LZS; P<.05). Micro-gaps at the implant-abutment connections were measured at 0.9 ±0.3 µm before fatigue and at 4.2 ±0.9 µm after fatigue. Cracks were detected at the crown adhesive or at the adhesive-abutment interface for both systems after fatigue. CONCLUSIONS: Cement- and screw-retained implant zirconium-lithium silicate glass-ceramic crowns revealed effective fatigue resistance on mean cyclic loading in an electrolyte solution. However, mechanical instability of the crown-adhesive-abutment interfaces and implant-abutment joints was detected after fatigue.

Abutment misfit in implant-supported prostheses manufactured by casting technique: An integrative review.

The aim of this study was to perform an integrative review of the literature on the clinically usual prosthesis-abutment misfit over implant-supported structures manufactured by conventional casting technique. The present integrative review used the PRISMA methodology. A bibliographical search was conducted on the following electronic databases: MEDLINE/PubMed (National Library of Medicine), Scopus (Elsevier), ScienceDirect (Elsevier), Web of Science (Thomson Reuters Scientific), Latin American and Caribbean Center on Health Sciences Information (BIREME), and Virtual Health Library (BVS). A total of 11 relevant studies were selected for qualitative analysis. The prosthetic-abutment vertical misfit considered clinically usual ranged from 50 to 160 µm. The vertical misfit depends on several steps during technical manufacturing techniques, which includes the materials and technical procedures. Lower values in misfit are recorded when precious metal or titanium alloys are utilized. Although a vertical misfit mean value of 100 µm has been considered clinically usual, most of the previous studies included in this revision showed lower mean values.

Biofilm Formation on Different Materials Used in Oral Rehabilitation.

The aim of this study was to evaluate the density and the morphological aspects of biofilms adhered to different materials applied in oral rehabilitation supported by dental implants. Sixty samples were divided into four groups: feldspar-based porcelain, CoCr alloy, commercially pure titanium grade IV and yttria-stabilized zirconia. Human saliva was diluted into BHI supplemented with sucrose to grow biofilms for 24 or 48 h. After this period, biofilm was removed by 1% protease treatment and then analyzed by spectrophotometry (absorbance), colony forming unit method (CFU.cm-2) and field-emission guns scanning electron microscopy (FEG-SEM). The highest values of absorbance and CFU.cm-2 were recorded on biofilms grown on CoCr alloys when compared to the other test materials for 24 or 48 h. Also, FEG-SEM images showed a high biofilm density on CoCr. There were no significant differences in absorbance and CFU.cm-2 between biofilms grown on zirconia, porcelain and titanium (p<0.05). Microbiological assays associated with microscopic analyses detected a higher accumulation of oral biofilms on CoCr-based materials than that on titanium or zirconia that are used for prosthetic structures.

Biofilm Formation on Different Materials Used in Oral Rehabilitation

Abstract The aim of this study was to evaluate the density and the morphological aspects of biofilms adhered to different materials applied in oral rehabilitation supported by dental implants. Sixty samples were divided into four groups: feldspar-based porcelain, CoCr alloy, commercially pure titanium grade IV and yttria-stabilized zirconia. Human saliva was diluted into BHI supplemented with sucrose to grow biofilms for 24 or 48 h. After this period, biofilm was removed by 1% protease treatment and then analyzed by spectrophotometry (absorbance), colony forming unit method (CFU.cm-2) and field-emission guns scanning electron microscopy (FEG-SEM). The highest values of absorbance and CFU.cm-2 were recorded on biofilms grown on CoCr alloys when compared to the other test materials for 24 or 48 h. Also, FEG-SEM images showed a high biofilm density on CoCr. There were no significant differences in absorbance and CFU.cm-2 between biofilms grown on zirconia, porcelain and titanium (p<0.05). Microbiological assays associated with microscopic analyses detected a higher accumulation of oral biofilms on CoCr-based materials than that on titanium or zirconia that are used for prosthetic structures.

Resumo O objetivo deste estudo foi avaliar a densidade e os aspectos morfológicos dos biofilmes aderidos a diferentes materiais aplicados em reabilitação oral sobre implantes dentários. Sessenta amostras foram divididas em quatro grupos: porcelana à base de feldspato, liga de CoCr, titânio grau IV comercialmente puro e zircônia estabilizada com ítrio. Saliva humana diluída em BHI foi suplementada com sacarose para possibilitar a formação de biofilme por 24 e 48 h. Após este período, o biofilme foi removido utilizando protease a 1% e, em seguida, analisada por espectrofotometria (absorbância), unidades formadoras de colônia (CFU.cm-2) e microscopia eletrônica de varredura (MEV). Os valores mais elevados de absorbância e CFU.cm-2 foram encontrados em ligas de CoCr quando comparado com os outros materiais testados. Os resultados obtidos foram semelhantes nos biofilmes formados sobre titânio e zircônia durante 24 e 48 h (p<0,05). As análises microbiológicas e microscópicas demostraram uma maior tendência ao acúmulo de biofilmes orais sobre estruturas protéticas baseadas em CoCr quando comparadas com porcelana feldspática, titânio ou zircônia.