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.

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.

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.

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.

Clinical and tomographic comparison of dental implants placed by guided virtual surgery versus conventional technique: A split-mouth randomized clinical trial.

AIM: Our objective was to compare guided virtual surgery to conventional surgery in terms of angular deviation of single dental implants placed in the posterior mandible. MATERIALS AND METHODS: Patients with bilateral homologous single teeth missing in the posterior mandible were eligible for this split-mouth randomized clinical trial. Cone beam computed tomography (CBCT) was performed for virtual planning of implant position and manufacturing of the stereolithographic guides. One week after the surgery, a second CBCT scan was superimposed to the initial planning. Primary endpoint was the angular deviation between virtual and clinical implant position. Secondary endpoints were linear deviations and patient-reported outcomes collected with a questionnaire. RESULTS: Data from 12 patients were available for analysis. Angular deviation was significantly lower using stereolithographic guides as compared to conventional guides (2.2 ± 1.1° vs. 3.5 ± 1.6°, p = .042). Linear deviations were similar for both techniques in the coronal (2.34 ± 1.01 vs. 1.93 ± 0.95 mm) and apical (2.53 ± 1.11 vs. 2.19 ± 1.00 mm) dimensions (p Ëƒ .05). The selection of the surgical technique had no significant impact on the patient-reported outcomes. CONCLUSION: Our data suggest that the angular discrepancy between the virtual and the clinical implant position is slightly lower when using stereolithographic guides as compared to conventional guides.

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.

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.

Are sectioning and soldering of short-span implant-supported prostheses necessary procedures?

The aim of this study was to evaluate the fit between dental abutments and the metal framework of a 3-unit fixed prosthesis screwed to two implants to determine whether sectioning and soldering of the framework are in fact necessary procedures. The study was based on a model of a metal framework of a 3-unit prosthesis screwed to two implants. A total of 18 metal frameworks were constructed and divided into 3 groups: (1) NS group - each framework was cast in one piece and not sectioned; (2) CS group - the components of each sectioned framework were joined by conventional soldering; and (3) LW group - the components of each sectioned framework were joined by laser welding. The control group consisted of six silver-palladium alloy copings that were not cast together. Two analyses were mperformed: in the first analysis, the framework was screwed only to the first abutment, and in the second analysis, the framework was screwed to both abutments. The prosthetic fit was assessed at a single point using a measuring microscope (Measurescope, Nikon, Japan) and the marginal gap was measured in micrometers. Statistical analysis was performed using analysis of variance (ANOVA), Scheffe's test, Student's t-test, and Mann-Whitney U test. The NS group had larger marginal gaps than the other groups (p<0.01), while the CS and LW groups had a similar degree of misfit with no significant difference between them. The results revealed that, in the case of short-span 3-unit fixed prostheses, the framework should be sectioned and soldered or welded to prevent or reduce marginal gaps between the metal framework and dental abutments.

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.

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.

Hard and Soft Tissue Cell Behavior on Polyetheretherketone, Zirconia, and Titanium Implant Materials

PURPOSE: The aim of this study was to characterize and compare the behavior of human osteoblasts and human gingival fibroblasts in contact with polyetheretherketone (PEEK), zirconia, and titanium implant surface materials. MATERIALS AND METHODS: PEEK, yttria-stabilized zirconia (YTZP), and titanium discs were produced under appropriate and similar conditions to achieve controlled surface features. Human osteoblasts and human gingival fibroblasts were cultured on discs for 14 days. Cell viability and proliferation were evaluated using a resazurin-based method. Morphology and cellular adhesion were observed using field emission gun-scanning electron microscopy (FEG-SEM). Alkaline phosphatase (ALP) activity and bone cell mineralization were evaluated on osteoblasts. Confocal laser scanning microscopy (CLSM) images of fluorescent-stained fibroblasts were obtained at 7 and 14 days of the culture. Results were presented as mean and standard deviation (SD). Group comparisons were tested using analysis of variance (ANOVA) (Tukey's post hoc) with appropriate statistical software, and significance was set at P < .05. RESULTS: Cell viability and proliferation were higher in PEEK and YTZP groups compared with titanium on osteoblast cells (P < .05, all time points) and on fibroblasts (P < .05, 7 and 14 days). All groups showed an increase in ALP activity over time, which was not significant. Mineralization patterns demonstrated an increase in mineral content over time, which was more apparent in the YTZP group. Cell spreading was more evident on PEEK and YTZP specimens. CONCLUSION: The results suggest increased adhesion, viability, and proliferation of osteoblasts and gingival fibroblasts on zirconia and PEEK surfaces compared with titanium. These results are correlated with the increased wettability of these materials.

Mesoporous bioactive glass embedding propolis and cranberry antibiofilm compounds.

The aim of this study was to evaluate the chemical reactivity of 58S mesoporous bioactive glass (MBG) particles in as-synthesized condition and after embedding propolis and cranberry antibiofilm compounds at different concentrations. MBG 58S was synthesized by alkali sol-gel method with the addition of the triblock pluronic copolymer P123 as surfactant. Samples were characterized by physicochemical properties measurement, N2 adsorption/desorption analysis, and field emission gun scanning electron microscopy (FEGSEM) observations. MBG powders were immersed into 5 and 10 µg/mL propolis or cranberry solutions for 24 h. The chemical reactivity of the specimens was evaluated by FEGSEM, EDX, FTIR, Ca/P ratio, XRD, and sample weight gain analysis after being immersed in simulated body fluid (SBF) for 8, 24, and 72 h. MBG particles exhibited the expected chemical composition with a particle size distribution ranging from 1.44 to 955 µm, and a mean particle size of 154 µm. MBG particles exhibited a pore volume of 0.8 cc/g, pore radius of ∼2 nm, and surface area of 350.2 m2 /g, according to BJH and BET analyses. A hydroxyl-carbonate apatite (HCAp) layer was formed on all samples after SBF immersion for 72 h. Pure MBG showed the highest chemical reactivity after 72 h, with the resulting apatite layer exhibiting a Ca/P ratio of ∼1.6 in accordance to stoichiometric biological apatite. MBG embedding propolis and cranberry can be considered for future microbiological analysis since the presence of propolis or cranberry did not interfere with MBG's ability to develop a HCAp layer, which is an essential feature for bone regeneration applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1614-1625, 2018.

Histomorphologic and histomophometric evaluation of immediately and early loaded mini-implants for orthodontic anchorage.

INTRODUCTION: The purpose of this study was to evaluate the bone response to statically loaded 2.5-mm diameter mini-implants of 6 and 10 mm lengths activated after various healing periods in a dog model. METHODS: Seventy-eight machined-surface Ti-6Al-4V mini-implants were bilaterally placed in the mandibular premolar and molar regions of 6 beagle dogs. The left (experimental) and the right (control) hemi-arches received 6 and 7 mini-implants, respectively. Experimental mini-implants healing periods of 0 days (immediately activated), 1 week, and 3 weeks were followed by a 12-week load activation period (250 g between parallel implant pairs). Control (nonloaded) mini-implant groups were placed for 12 weeks, 3 weeks, and 1 week before the dogs were killed they provided data concerning the experimental groups' bone to mini-implant scenarios at load activation times. The mandibles were exposed by sharp dissection, and decalcified specimens were prepared for histomorphologic and histomorphometric (bone to mini-implant contact) assessment. RESULTS: Survival rates were 100% and 77.78% for the control and the experimental groups, respectively. Survival rates were 88.89% for the 10-mm and 66.67% for the 6-mm experimental groups. All failed devices had tissue inflammation and were lost after spring placement. The control groups showed classic bone-healing events, and the experimental groups showed mature bone morphology after 12 weeks in vivo regardless of placement time before load activation. Bone to implant contact values were not significantly different between the experimental and the control groups that remained 12 weeks in vivo. CONCLUSIONS: These results showed that low-intensity immediate or early orthodontic static loads did not affect mini-implant performance.

Clinical and radiographic evaluation of periodontal and peri-implant conditions in patients with implant-supported prosthesis.

The aim of the present study was to clinically and radiographically assess the peri-implant and periodontal conditions in partially edentulous patients with implant-supported fixtures installed, at least, one year prior to the study. 41 patients were examined by a calibrated examiner in relation to the following implant-associated parameters: Modified Plaque Index (mPlI), Modified Bleeding Index (mBI), probing depth (PD), clinical attachment level (CAL) and bleeding on probing of the bottom of the crevice (BOP). Also, the remaining teeth were assessed in terms of Plaque Index (PlI), Gingival Index (GI), PD, CAL and BOP. The peri-implant bone loss was evaluated by means of periapical radiographs. Measurements of pre-operatory and final bone levels allowed an estimation of bone loss associated to teeth and a comparison with bone loss around implants. None of the individuals presented late loss of implants until the examination took place. No statistically significant differences were observed between PlI (0.90+/-0.07) and mPlI (0.82+/-0.13), or between GI (0.11+/-0.02) and mBI (0.10+/-0.02). However, PD, CAL and BOP values were higher in implants than in teeth (Wald Test, p<0.01). Implants presented a mean annual bone loss during the study period of 0.77 mm (SE=0.06). Teeth virtually did not present any bone loss (mean value of 0.36%) whereas implants exhibited a bone loss value of 17.11%. Plaque accumulation and marginal inflammation did not differ between teeth and implants. However, subgingival inflammation was higher in implants than in teeth. The destruction measurements suggest greater losses in implants, as expected because of tissue remodelation.

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 behavior on sulfonated poly(ether-ether-ketone) (sPEEK).

Poly(ether-ether-ketone) (PEEK) has also shown to be very attractive for incorporating therapeutic compounds thanks to a sulfonation process which modifies the material structure resulting in a sulfonated-PEEK (sPEEK). Concerning biomedical applications, the objective of this work was to evaluate the influence of different sulfonation degree of sPEEK on the biofilm growth. PEEK samples were functionalized by using sulphuric acid (98%) and then dissolved into dimethyl-sulfoxide. A dip coating technique was used to synthesize sPEEK thin films. The sulfonation degree of the materials was analyzed by FT-IR, H NMR, TG and IEC. The surfaces were characterized by scanning electron microscopy, profilometry and contact angle analyses. Subsequently, the biofilm formation on sulfonated-PEEK based on Streptococcus mutans and Enterococcus faecalis was measured by spectrophotometry, colony forming units (CFUmL-1) and SEM. Results obtained from thermal and chemical analyses showed an intensification in sulfonation degree for sPEEK at 2 and 2.5h. The E. faecalis or S. mutans biofilm growth revealed statistically significant differences (p<0.05) between 2 and 3h sulfonation groups. A significant decrease (p<0.05) in CFUmL-1 was recorded for S. mutans or E. faecalis biofilm grown on 2.5 or 3h sPEEK. Regarding the thermal-chemical and microbiologic analyses, the sulfonation degree of sPEEK ranging from 2 up to 3h was successful capable to decrease the biofilm growth. That revealed an alternative strategy to embed anti-biofilm and therapeutic compounds into PEEK avoiding infections in biomedical applications.

On the synthesis and characterization of ß-tricalcium phosphate scaffolds coated with collagen or poly (D, L-lactic acid) for alveolar bone augmentation.

OBJECTIVES: After tooth loss, dimensional alterations on the alveolar bone ridge can occur that can negatively affect the placement of dental implants. The purpose of this study was to evaluate the synthesis, and mechanical properties of ß-tricalcium phosphate (ß-TCP) scaffolds coated with bioabsorbable polymers, namely, collagen and poly (D, L-lactic acid) (PDLLA). MATERIALS AND METHODS: ß-TCP powder was obtained by reactive milling and then characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). ß-TCP scaffolds were obtained by replica method, in which polyurethane foams are immersed in ß-TCP suspension and thereafter submitted to a thermal treatment to remove the polyurethane and sinter the ceramic. Type-I collagen or PDLLA were used to coat the ß-TCP scaffolds by dip-coating method. Scaffolds were separated in four groups depending on the coating material: noncoated (Group A), double immersion in collagen (Group B), double immersion in PDLLA (Group C), and ten immersions in PDLLA (Group D). Samples were characterized by compressive tests and SEM/EDS. Data were statistically analyzed through two-way ANOVA (p = 0.05). RESULTS: Chemical and microscopic analyses revealed proper morphology and chemical composition of powder particles and scaffolds with or without polymeric coatings. Scaffolds coated with PDLLA showed higher compressive strength (0.11 ± 0.054 MPa) than those of collagen (0.022 ± 0.012 MPa) or noncoated groups (0.024 ± 0.012 MPa). CONCLUSIONS: The coating method of ß-TCP with PDLLA revealed a potential strategy to increase the mechanical strength of porous ceramic materials while collagen can enhance cell migration.

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.

Morse taper dental implants and platform switching: The new paradigm in oral implantology.

The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: "Bone loss and platform switching," "bone loss and implant-abutment joint," "bone resorption and platform switching," "bone resorption and implant-abutment joint," "Morse taper and platform switching." "Morse taper and implant-abutment joint," Morse taper and bone resorption," "crestal bone remodeling and implant-abutment joint," "crestal bone remodeling and platform switching." The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends.

Biofilm Affecting the Mechanical Integrity of Implant-Abutment Joints.

PURPOSE: This in vitro study evaluated the effect of biofilms on abutment torque loss and wear of implant internal connection surfaces. MATERIALS AND METHODS: Morse taper abutments were torqued to corresponding implants and then the implant-abutment assemblies were immersed in a biofilm medium for 72 hours. After detorque evaluation, the abutments were removed and the inner implant surfaces were observed via scanning electron microscopy and profilometry. RESULTS: The removal torque values and the implant damaged areas decreased after contact with biofilms. CONCLUSION: The lubricating effect of biofilms decreased the friction between contacting surfaces, negatively affecting the mechanical integrity of the implant-abutment connection.