Borate mineral loading into acrylic bone cements to gain cost-effectivity, enhanced antibacterial resistivity, and better cellular integration properties.

Polymethyl methacrylate (PMMA), called as bone cement, has been used in implant surgery, initially in dental practices, then in arthroplasty surgery for decades. Bone cement is a highly preferred chemical in the field of orthopedics due to its bone-like hardness and mechanical strength. Meanwhile, antibiotic-loaded cements are used in joints and similar surgeries are generally due to the risk of infection. In this study, we aimed to demonstrate the effects of borate mineral loading into bone cement on enhancing the antibacterial resistivity and cell integration as well as retaining mechanical properties. Moreover, the incorporation of minerals into bone cements makes them much more cost-friendly biomaterials for surgical operations. Herein, antibacterial properties were evaluated by using vancomycin- and gentamycin-susceptible strains of Enterococcus faecalis and Staphylococcus aureus whereas cell viability tests were performed by osteoblast cell lines. Three sets of the bone cements, plain, calcium borate-, and sodium borate-loaded, were prepared through commercial procedures and subjected to mechanical, antibacterial and cell viability tests. Percentage deformation determined by compression tests under 0.100 MPa pressure was determined in the range of 12.58%-10.67% in respect to the amount of sodium borate mineral loaded whereas that was determined in the range of 12.54%-9.87% in respect to the amount of calcium borate mineral loaded. Micro-CT results also supported good mineral integration and structural features of the composite bone cements. Furthermore, mineral incorporation enhanced the cell viability, in other words, cellular integrity, up to 101.28% for sodium borate-loaded (NB75, 7.5 g mineral) and 72.04% for calcium borate-loaded (CB75, 7.5 g mineral) bone cement according to the negative control group, fresh culture medium. As a conclusion, both of these minerals could be classified as promising alternatives for developing bone cements with better antibacterial resistivity and cellular integration properties.

Marginal Fit of All-Ceramic Crowns Before and After Cementation: An In Vitro Study.

The marginal integrity of all-ceramic crowns for anterior and posterior teeth were evaluated. A total of 60 ceramic crowns (In-Ceram Alumina, IPS e.max Press, and Lava) were fabricated for the epoxy resin maxillary first central incisor and first molar and divided into three groups (n = 20). The crowns were measured at the facial, lingual, mesial, and distal finish lines (52 points) before and after cementation using scanning electron microscopy. The results were analyzed using one-way analysis of variance, paired samples t test, and independent t test. The mean values of marginal gaps were within acceptable clinical limits before and after cementation. The values of the anterior crowns at the buccal finish line were higher than those at the proximal finish line areas (P < .05). However, these were insignificant at four measurement areas for posterior crowns (P > .05). Marginal gaps of crowns at the anterior teeth were higher than at the posterior teeth for all groups.

Effect of engraving speeds of CO2 laser irradiation on In-Ceram Alumina roughness: a pilot study.

OBJECTIVES: The aim of the study was to determine the effect of CO2 laser on surface roughness of In-Ceram-Alumina-ceramic. MATERIALS AND METHODS: Four aluminum-oxide ceramic disc specimens were prepared of In-Ceram Alumina. Discs received CO2 laser irradiation with different engraving speeds (100, 400, 600 and 800 mm/min) as a surface treatment. The roughness of the surfaces was measured on digital elevation models reconstructed from stereoscopic images acquired by scanning-electron-microscope. Surface roughness data were analyzed with One-Way-Analysis-of-Variance at a significance level of p<0.05. RESULTS: There was no significant difference between the roughness values (p=0.82). Due to higher laser durations, partial melting signs were observed on the surfaces. Tearing, smearing and swelling occurred on melted surfaces. Swelling accompanying melting increased the surface roughness, while laser power was fixed and different laser engraving speeds were applied. CONCLUSION: Although different laser irradiation speeds did not affect the roughness of ceramic surfaces, swelling was observed which led to changes on surfaces.

Estrogen as a novel agent for induction of adipose-derived mesenchymal stem cells for osteogenic differentiation: in vivo bone tissue-engineering study.

BACKGROUND: This study investigated whether the in vivo osteogenic differentiation potential of adipose-derived mesenchymal stem cells is enhanced by 17ß-estradiol. METHODS: Thirty Sprague-Dawley rats were randomized and divided into five experimental groups. For the surgical procedure, biparietal full-thickness bone defects (7 mm in diameter) were created. A chitosan-hydroxyapatite scaffold was used as the vehicle system for 17ß-estradiol-loaded nanoparticles and adipose-derived mesenchymal stem cells. The first group, the blank defect group, was the control group. The defects were filled with either scaffold, estradiol, and scaffold; scaffold and adipose-derived mesenchymal stem cells; or estradiol, scaffold, and adipose-derived mesenchymal stem cells as experimental groups. The rats were killed at the end of weeks 4 and 12, and their calvariae were harvested for histologic and microtomographic evaluation. RESULTS: Micro-computed tomographic evaluation of estradiol, scaffold, and adipose-derived mesenchymal stem cells revealed the highest median value (82.59 ± 17.17), and the difference was significant compared with the blank defect group (p = 0.004). Histologic samples demonstrated a significant difference between experimental groups for bone defect repair at the end of weeks 4 and 12 (p = 0.003 and p < 0.001). The estradiol, scaffold, and adipose-derived mesenchymal stem cell group had the highest median score (3.00 ± 0.0) at week 12, which was significantly higher than scores for the scaffold and adipose-derived mesenchymal stem cell group and the blank defect group. CONCLUSION: 17ß-Estradiol appears to be a novel and promising agent for future cell-based bone tissue-engineering studies.

Histomorphometrical and radiological comparison of low-level laser therapy effects on distraction osteogenesis: experimental study.

Distraction osteogenesis (DO) is the application of traction to the callus formed between bone segments and stimulation of bone formation by creating stress on the callus with this traction. Shorten the duration of DO and increasing the capacity of bone formation is important to prevent the possible complications of DO. For this reason, it was considered that low-level laser therapy (LLLT) may affect positively DO and it can decrease the complication range by shortening the period. Unilateral mandibular distractors were applied on 16 female white New Zealand rabbit to prove this hypothesis with micro CT, plain radiograph and histomorphometric analyses. Eight rabbits were applied LLLT with GaAlAs laser on the distraction area during the distraction period. On the post-distraction 28th day, four rabbits from study group and four rabbits from control groups were sacrificed. The rest of the rabbits were sacrificed on post-distraction 56th day. As a result of this study, significant positive effects of LLLT on post-distraction 28th day were revealed with all analyses. In histomorphometrical analyses, new bone formation was significantly higher in short-term laser applied group comparing to that of short-term control group (p = 0.029). In both microCT and plain radiograph, the highest radioopacity values were observed in short-term laser group when compared with that of the controls (p = 0.043 and p = 0.025, respectively). Even though LLLT increased the healing capacity on short-term, it was not sufficient on long-term (post-distraction 56th day) healing. LLLT application on distraction period, activate healing on bone so it may decrease DO period. The result of this study should be supported with clinical studies and the most effective laser source, dose and application time should be revealed with experimental and clinical studies.

Association of amoxicillin use and molar incisor hypomineralization in piglets: visual and mineral density evaluation.

AIM: The aim of the present study was to determine the prevalence of MIH both visually and quantitatively, and describes the range of mineral densities of enamel specimens from three groups of piglets where two groups were given different doses of amoxicillin in infancy. METHODS: In this blind randomized clinical study, 20 piglets were randomly divided into three groups. Group A received a standard dose (50mg/kg/day) and Group B received a high dose (90mg/kg/day) of amoxicillin in selected days of the month (20 working days) they were born. Group K did not receive any medication and served as control. Thirteen right mandibular permanent first molars (PFMs) were randomly collected from 3 groups of piglets at age 10 months for evaluation under X-ray micro-tomography. Tomographic data were obtained using a Skyscan 1174 compact micro-CT in the Department of Anatomy. RESULTS: Prevalence of MIH was 0% in all groups. MD values were quantified after enamel grey level (0-255) measurements on horizontal cross-sectional slices. After MD measurements, the effects of amoxicillin use on MIH are presented. CONCLUSIONS: While MIH is a multifactorial disturbance, the present study attempted to highlight the clinical findings of a possible relationship between amoxicillin use and MIH with the aid of X-ray micro-tomography.

Evaluation of urinary stones ex vivo with micro-computed tomography: preliminary results of an investigational technique.

PURPOSE: To evaluate the ultrastructural features of the urinary stones removed with endoscopic stone surgery, using micro computed tomography (micro-CT). MATERIALS AND METHODS: Patients who had endoscopic surgery for renal or ureteral stones removal were included in this study. After surgery, the stones were classified into three groups and investigated with Skyscan 1174 micro-CT. Group I underwent percutaneous nephrolithotomy (PNL) with ultrasonic lithotripsy; group II had ureteroscopic stone surgery (USS) with pneumatic lithotripsy; and group III (the control group) had stone removal with USS or PNL without lithotripsy. Stone homogeneity, voids, and the internal structure of the stones were evaluated. Chi-square test was used to evaluate the difference statistically. P values less than .05 were considered statistically significant. RESULTS: A total of 24 "calcium oxalate monohydrate" stones from 24 patients were scanned with micro-CT. Stones treated with ultrasonic lithotripsy (group I) were more fragile, fragmented, and cracked than those treated with the pneumatic lithotripsy (group II; P = .01). Stones in group II were more homogeneous and smooth than those in group I and resembled those of the control group (P = .02). Homogeneous, non-fragile stones and heterogeneous, fragile calculi were seen in all groups. CONCLUSION: The stone fragility could be confirmed by micro-CT investigation. Ultrasonic lithotripters increase the stone fragility, which is demonstrated with increased heterogeneity by micro-CT.

WDS versus silicon drift detector EDS: a case report for the comparison of quantitative chemical analyses of natural silicate minerals.

Electron probe microanalysis (EPMA) is an essential analytical approach to determine elemental concentrations of various solid specimens quantitatively in mineralogical, petrological and materials research. Either wavelength dispersive X-ray (WDS) or energy dispersive X-ray (EDS) spectrometric techniques can collect the characteristic X-rays generated from each element in the specimen by an incident electron beam in order to define chemical constituents. Although WDS has been the preferred technique because of its higher spectral resolution and ability to detect trace elements, new generation EDS systems with silicon drift detectors (SDD), equipped with thin windows and integrated digital processing electronics, are claimed to approach the WDS throughput. In this study, we compared the analytical capability of a SDD EDS system with respect to WDS equipped systems on natural silicate minerals. For this purpose, natural rock samples, in which the silicate minerals present had already been analysed by various WDS systems, were chosen to compare these results with the ones acquired with a SDD EDS system. SDD EDS yielded satisfactory results for major elements (Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe) compared with the results of the same minerals obtained by various WDS systems.

Quantitative analysis on volcanic ash surfaces: application of extended depth-of-field (focus) algorithm for light and scanning electron microscopy and 3D reconstruction.

The depth-of-field mainly affects the image quality either in scanning electron microscopy (SEM) or conventional light microscopy. The limited depth-of-field handicap of microscopy imaging can be used for obtaining "optically sectioned" specimens by moving the object along the optical axis. In this study, multiple images corresponding to different object planes were taken in order to overcome limited depth-of-field on conventional light microscope and SEM, estimation of an elevation surface and 3D reconstruction of different type volcanic ash surfaces. We used extended depth-of-field, a fusion algorithm that combines those images into one single sharp composite. Because of larger depth-of-field, we got higher-quality results even with image stacks taken by SEM with a fixed aperture in variable pressure mode. We calculated roughness descriptors, quadtree decomposition and greylevel standard deviation (sGL) and analyzed the shape of polar plots based on gradient analysis of constructed depth-maps. Furthermore, we calculated fractal dimensions of surfaces. Correlation analysis was performed to measure how these quantitative variables are related with different type ash surfaces. Roughness descriptors, quadtree decomposition, sGL and fractal dimension discriminate different types of volcanic ash surfaces.