Insulin Therapy on Bone Macroscopic, Microarchitecture, and MechanicalProperties of Tibia in Diabetic Rats.

BACKGROUND: This study evaluated tibia's macroscopic structure, mechanical properties, and bone microarchitecture in rats with type 1 diabetes mellitus (T1DM). METHODS: Eighteen animals were divided into three groups (n=6): Non-diabetic (ND), diabetic (D), and diabetic+insulin (DI). T1DM was induced by streptozotocin; insulin was administered daily (4IU). The animals were euthanized 35 days after induction. The tibiae were removed and analyzed using macroscopic, micro-computed tomography (micro-CT) and three-point bending. The macroscopic analysis measured proximal-distal length (PD), antero-posterior thickness (AP) of proximal (AP-P) and distal (AP-D) epiphysis, and lateral-medial thickness (LM) of proximal (LM-P) and distal (LM-D) epiphysis. Micro-CT analysis closed porosity, tissue mineral density, and cortical thickness. The three-point bending test measured maximum strength, energy, and stiffness. RESULTS: The macroscopic analysis showed that D presented smaller measures of length and thickness (AP and AP-P) than ND and DI. More extensive measurements were observed of LM and AP-D thickness in DI than in D. In micro-CT, DI showed larger cortical thickness than D. Mechanical analysis showed lower strength in D than in other groups. CONCLUSIONS: T1DM reduces bone growth and mechanical strength. Insulin therapy in diabetic rats improved bone growth and fracture resistance, making diabetic bone similar to normoglycemic animals.

Do blood concentrates influence inflammatory signs and symptoms after mandibular third molar surgery? A systematic review and network meta-analysis of randomized clinical trials.

OBJECTIVES: To investigate, through a network meta-analysis, the effectiveness of blood concentrates in reducing pain perception, trismus, and edema after mandibular third molar extraction. MATERIALS AND METHODS: An electronic search was performed in nine databases to locate randomized clinical trials comparing blood concentrate use after mandibular third molar extraction. Two authors selected and extracted the data independently. The individual risk of bias in the studies was assessed with the RoB v2.0 tool. A network meta-analysis compared postoperative pain and trismus scores after applying different blood concentrates, using the mean difference (MD) as an effect estimate. The GRADE approach assessed the certainty of evidence. RESULTS: Thirty-one randomized clinical trials were included in the review and 18 in the meta-analysis. Leukocyte- and platelet-rich fibrin (L-PRF) was the most used blood concentrate, followed by platelet-rich plasma (PRP). The network meta-analysis, depending on the analyzed period, evaluated up to 1240 surgeries. Among the analyzed blood concentrates, advanced platelet-rich fibrin (A-PRF) performed better among the analyzed blood concentrates, decreasing postoperative pain in 1, 2, 3, and 7 days and reducing trismus up to the inflammatory peak compared to blood clots. Only two studies had a low risk of bias. CONCLUSIONS: Based on very low certainty of evidence, using concentrates seemed efficient compared to blood clots in reducing pain and trismus after mandibular third molar surgeries. A-PRF decreased postoperative pain throughout the evaluated time and trismus during the acute inflammatory peak. CLINICAL RELEVANCE: A-PRF after mandibular third molar extractions performed better among the analyzed blood concentrates and seemed efficient in improving postoperative quality by decreasing inflammatory signs and symptoms.

Progressive Platelet Rich Fibrin tissue regeneration matrix: Description of a novel, low cost and effective method for the treatment of chronic diabetic ulcers-Pilot study.

INTRODUCTION: Chronic lower limb ulcers (CLLU) are those injuries that persist for more than six weeks despite adequate care. They are relatively common; it is estimated that 10/1,000 people will develop CLLU in their lifetime. Diabetic ulcer, because of its unique pathophysiology (association between neuropathy, microangiopathy, and immune deficiency), is considered one of the most complex and difficult etiologies of CLLU for treatment. This treatment is complex, costly, and sometimes frustrating, as it is often ineffective, which worsens the quality of life of patients and makes its treatment a challenge. OBJECTIVE: To describe a new method for treating diabetic CLLU and the initial results of using a new autologous tissue regeneration matrix. METHOD: This is a pilot, prospective, an interventional study that used a novel protocol of autologous tissue regeneration matrix for the treatment of diabetic CLLU. RESULTS: Three male cases with a mean age of 54 years were included. A total of six Giant Pro PRF Membrane (GMPro) were used varying their application between one to three sessions during treatment. A total of 11 liquid phase infiltrations were performed varying their application between three and four sessions. The patients were evaluated weekly and a reduction in the wound area and scar retraction was observed during the period studied. CONCLUSION: The new tissue regeneration matrix described is an effective and low-cost method for the treatment of chronic diabetic ulcers.

Platelet-Rich Fibrin Progressive Protocol: Third Generation of Blood Concentrates.

PURPOSE: Platelet-rich fibrin (PRF) has been used in several fields of dentistry to improve tissue healing. However, PRF from glass tubes results in a limited number of small membranes, increasing clinical difficulty and work time. The aim of this study was to evaluate cell and platelet amounts and biomechanical strength of PRF-giant membranes produced from plastic tubes without additives. MATERIAL AND METHODS: The investigators designed an ex vivo study, to compare 3 different centrifugation protocols for obtaining PRF: 700 × g/12 minutes (leukocyte and PRF [L-PRF]), 350 × g/14 minutes (GM350), and 60-700 × g more than 15 minutes total (progressive PRF [PRO-PRF]). We collected blood samples from 5 volunteers aged 25-54 years, over 3 different time periods (triplicate and paired study). From each venipuncture, 4 mL of blood was collected in vacutainers with ethylenediamine tetraacetic acid (EDTA) and approximately 104 mL in 12 plastic tubes without additives, which were separated into 3 groups, as per the centrifugation protocols (n = 5): L-PRF, GM350, and PRO-PRF. The PRF from the tubes of the same protocol was aspirated and 9 mL were placed in polylactic acid (PLA) forms and 3 mL were placed in a glass receptacle. The membranes from PLA forms were tested for tensile strength and the membranes from glass receptacles were evaluated by histomorphometry, while platelets and leukocytes were counted for those in tubes with EDTA. Statistical analyses were performed using Shapiro-Wilk normality test and then a one-way repeated measures analysis followed by Tukey multiple comparisons test (α < 0.05). RESULTS: In tensile analyses, PRO-PRF (0.85 ± 0.23 N) showed a significantly higher maximum breaking strength than L-PRF (0.61 ± 0.26 N, P = .01) and GM350 (0.58 ± 0.23 N, P < .01). The histomorphometry revealed no significant statistical difference in cell counts between the groups (P = .52). Furthermore, there was no significant difference between the leukocyte (P = .25) and platelet counts (P = .59) in whole blood between the groups. CONCLUSION: The progressive protocol (PRO-PRF) enabled the production of PRF giant membranes with greater tensile strength and adequate cell distribution. Moreover, it allows biomaterial incorporation during production and enables clinical control of membrane thickness and size as per the surgical procedure.

Automated bone healing evaluation: New approach to histomorphometric analysis.

This study aimed to assess different approaches for bone healing evaluation on histological images and to introduce a new automatic evaluation method based on segmentation with distinct thresholds. We evaluated the hyperbaric oxygen therapy (HBO) effects on bone repair in type 1 diabetes mellitus rats. Twelve animals were divided into four groups (n = 3): non-diabetic, non-diabetic + HBO, diabetic, and diabetic + HBO. Diabetes was induced by intravenous administration of streptozotocin (50 mg/kg). Bone defects were created in femurs and HBO was immediately started at one session/day. After 7 days, the animals were euthanized, femurs were removed, demineralized, and embedded in paraffin. Histological sections were stained with hematoxylin and eosin (HE) and Mallory's trichrome (MT), and evaluated using three approaches: (1) conventional histomorphometric analysis (HE images) using a 144-point grid to quantify the bone matrix; (2) a semi-automatic method based on bone matrix segmentation to assess the bone matrix percentage (MT images); and (3) automatic approach, with the creation of a plug-in for ImageJ software. The time required to perform the analysis in each method was measured and subjected to Bland-Altman statistical analysis. All three methods were satisfactory for measuring bone formation and were not statistically different. The automatic approach reduced the working time compared to visual grid and semi-automated method (p < .01). Although histological evaluation of bone healing was performed successfully using all three methods, the novel automatic approach significantly shortened the time required for analysis and had high accuracy.

Effectiveness of Photobiomodulation Therapy on Human Bone Healing in Dentistry: A Systematic Review.

Background: Despite the association, possible causality, and contradictory results, numerous studies evaluate photobiomodulation (PBM) therapy on the process of human bone healing. It is of paramount importance to review the available literature to elucidate the effect of laser on the bone healing process in dentistry. Objective: This systematic review analyzes the effectiveness of PBM therapy to improve bone healing in dentistry. Methods: A systematic search of studies published up to September 2021 and listed in PubMed, Cochrane Library, and Embase databases and registered on PROSPERO (CRD42020212790). Twenty-five studies were selected. Results: The most used device was diode laser. PBM therapy parameters varied greatly. From the 25 selected studies, 17 had the primary outcome bone healing. Of these, 11 studies revealed improvement in bone healing with PBM therapy and six studies suggested no effect. The other eight studies evaluated secondary parameters. In seven studies, some of the clinical parameters were improved with the PBM therapy. Conclusions: Within the limitations of this systematic review, bone healing in dentistry was improved with the use of PBM. PBM therapy can promote anti-inflammatory and analgesic effects, improve healing, as well as enhance quality of life related to oral health. Within the areas analyzed in dentistry, laser parameters varied greatly, becoming difficult to consider a definite protocol as a proper one.

Type I Diabetes Mellitus and Insulin Therapy on Bone Microarchitecture, Composition and Mechanical Properties.

BACKGROUND: The aim of this study was to evaluate the microarchitecture, composition and mechanical properties of cortical bone of rats with type I diabetes mellitus (TIDM) and submitted to insulin therapy (IT). METHODS: Thirty rats were divided into three groups (n=10): non-diabetic, diabetic and diabetic+insulin. TIDM was induced by intravenous injection of streptozotocin. In diabetic+insulin group, 4IU insulin was administered twice per day (1I U at 7 am and 3I U at 7 pm). The animals were euthanized five weeks after TIDM induction; the tibiae were removed and submitted to microcomputed tomography (micro-CT, 8 µm), fourier transform infrared spectroscopy (FTIR) and dynamic microhardness indentation. RESULTS: Micro-CT analysis showed that diabetic group had lower bone surface/tissue volume ratio (BS/BV) (p=0.018), cortical thickness (Ct.Th) (p<0.001) and degree of anisotropy (Ct.DA) (p=0.034) values compared to non-diabetic group. The diabetic group showed lower Ct.Th than diabetic + insulin group (p=0.018). The non-diabetic group had lower fractal dimension (Ct.FD) values compared to diabetic groups (p<0.001). The ATR-FTIR analyses showed lower values for all measured parameters in the diabetic group than the non-diabetic group (amide I ratio: p=0.046; crystallinity index: p=0.038; matrix:mineral ratios - M:MI: p=0.006; M:MIII: p=0.028). The diabetic+ insulin group showed a lower crystallinity index (p=0.022) and M:MI ratio (p=0.002) than nondiabetic and diabetic groups, respectively. The diabetic group showed lower Vickers hardness values than non-diabetic (p<0.001) and diabetic+insulin (p=0.003) groups. CONCLUSION: TIDM negatively affects bone microarchitecture, collagen maturation, mineralization and bone microhardness. Moreover, insulin minimized the effect of TIDM on cortical thickness and organic/mineral matrix.

Automatic Segmentation of Bone Canals in Histological Images.

The literature provides many works that focused on cell nuclei segmentation in histological images. However, automatic segmentation of bone canals is still a less explored field. In this sense, this paper presents a method for automatic segmentation approach to assist specialists in the analysis of the bone vascular network. We evaluated the method on an image set through sensitivity, specificity and accuracy metrics and the Dice coefficient. We compared the results with other automatic segmentation methods (neighborhood valley emphasis (NVE), valley emphasis (VE) and Otsu). Results show that our approach is proved to be more efficient than comparable methods and a feasible alternative to analyze the bone vascular network.

Impact of Childhood Obesity on Bone Metabolism.

Childhood obesity is a considerable worldwide health problem and a major risk factor for several chronic diseases. Fat rich diets result in altered serum levels of lipids, cytokines and hormonal factors, which influence skeletal acquisition and promote microstructural and mechanical behavior changes in bone, especially to bone quality and quantity. However, the possible longterm implications of high-fat diets in childhood are controversial. Despite not fully understood, multiple signaling pathways which support bone tissue homeostasis are altered under hyperlipidic conditions, including RANKL/RANK/OPG, PPAR-γ/Alox5/5-LO, leptin/IGF-I/AGE, ApoE/Lrp-1, Thy-1, IL-6, TNFα, calcium, vitamin D and K metabolism. Moreover, the expression of reactive oxygen species is also modified. Considering the importance of this subject, the aim of this review was to explore the mechanisms of bone formation affected by obesity during childhood during childhood.

The effect of hyperbaric oxygen therapy on bone macroscopy, composition and biomechanical properties after ionizing radiation injury.

BACKGROUND: Radiotherapy used in tumor treatment compromises vascularization of bone tissue. Hyperbaric oxygenation (HBO) increases oxygen availability and improves vascularization, minimizing the deleterious effects of ionizing radiation (IR). Therefore, the aim of this study was to evaluate HBO therapy effect on bone macroscopy, composition and biomechanical properties after IR damage. METHODS: Twenty male Wistar rats weighing 300 ± 20 g (10 weeks of age) were submitted to IR (30 Gy) to the left leg, where the right leg was not irradiated. After 30 days, ten animals were submitted to HBO therapy, which was performed daily for 1 week at 250 kPa for 90-min sessions. All animals were euthanized 37 days after irradiation and the tibia were separated into four groups (n = 10): from animals without HBO - right tibia Non-irradiated (noIRnoHBO) and left tibia Irradiated (IRnoHBO); and from animals with HBO - right tibiae Non-irradiated (noIRHBO) and left tibia Irradiated (IRHBO). The length (proximal-distal) and thickness (anteroposterior and mediolateral) of the tibiae were measured. Biomechanical analysis evaluated flexural strength and stiffness. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used to calculate the amide I ratio, crystallinity index, and matrix to mineral ratios. RESULTS: In the macroscopic and ATR-FTIR analysis, the IRnoHBO showed lower values of length, thickness and amide I ratio, crystallinity index and matrix to mineral ratios compared to noIRnoHBO (p < 0.03). IRnoHBO showed no statistical difference compared to IRHBO for these analyses (p > 0.05). Biomechanics analysis showed that the IRnoHBO group had lower values of flexural strength and stiffness compared to noIRnoHBO and IRHBO groups (p < 0.04). In addition, the noIRHBO group showed higher value of flexural strength when compared to noIRnoHBO and IRHBO groups (p < 0.02). CONCLUSIONS: The present study concluded that IR arrests bone development, decreases the collagen maturation and mineral deposition process, thus reducing the flexural strength and stiffness bone mechanical parameters. Moreover, HBO therapy minimizes deleterious effects of irradiation on flexural strength and the bone stiffness analysis.

Hyberbaric oxygen and bone reconstruction.

INTRODUCTION: The aim of this literature review was to determine the benefits of hyperbaric oxygen therapy after bone reconstruction procedures in humans and identify information that may be useful for the development of optimal protocols for hyperbaric oxygen therapy to stimulate bone healing. EVIDENCE ACQUISITION: We searched the electronic database PubMed/Medline for studies published between January 1999 and December 2018, using the key words: "bone" or "bone graft" and "mandible reconstruction" or "jaw reconstruction" and "hyperbaric oxygen" or "HBO." First, the titles and abstracts of the studies found were evaluated and those that corresponded to the aims of this review were pre-selected for analysis of the full text. Subsequently, the full texts were analyzed, and those that met the eligibility criteria were pre-selected for the review. The full texts of studies whose abstracts did not provide enough data for decision were also evaluated. Two examiners independently assessed eligibility, risk of bias and extracted data. EVIDENCE SYNTHESIS: A total of 2237 studies were found according to pre-established criteria for data collection, of which only 5 studies were included in this systematic review. Although we observed positive results in the included studies, there are still few standardized clinical studies in the literature, assessing hyperbaric oxygen therapy after extensive bone reconstructive procedures. CONCLUSIONS: It is difficult to compare results found in different studies due to the variety of methodological and clinical conditions assessed.

Effects of ionizing radiation on woven bone: influence on the osteocyte lacunar network, collagen maturation, and microarchitecture.

OBJECTIVES: Evaluate the effects of ionizing radiation on microarchitecture, the osteocyte lacunar network, and collagen maturity in a bone repair site. MATERIALS AND METHODS: Bone defects were created on tibias of 20 New Zealand rabbits. After 2 weeks, the animals were randomly divided into (n = 10) NoIr (nonirradiated group) and Ir (irradiated group). In the Ir, the animals received single-dose irradiation of 30 Gy on the tibia and were euthanized after 2 weeks. Bone microarchitecture parameters were analyzed by using micro-CT, and the osteocyte lacunar network, bone matrix, and collagen maturation by histomorphometric analysis. The data were analyzed using unpaired Student's t test (α = 0.05). RESULTS: Trabecular thickness in Ir was lower than that in NoIr (P = 0.028). No difference was found for bone volume fraction and bone area. Lacunae filled with osteocytes were more numerous (P < 0.0001) in NoIr (2.6 ± 0.6) than in Ir (1.97 ± 0.53). Empty lacunae were more prevalent (P < 0.003) in Ir (0.14 ± 0.10) than in NoIr (0.1 ± 0.1). The mean osteocyte lacunae size was higher (P < 0.01) in Ir (15.4 ± 4.41) than in NoIr (12.7 ± 3.7). Picrosirius red analysis showed more (P < 0.05) mature collagen in NoIr (29.0 ± 5.3) than in Ir (23.4 ± 4.5). Immature collagen quantification revealed no difference between groups. CONCLUSIONS: Ionizing radiation compromised bone formation and an impairment in bone repair in irradiated woven bone was observed. CLINICAL RELEVANCE: Before radiotherapy, patients usually need surgical intervention, which may be better performed, if clinicians understand the repair process in irradiated bone, using novel approaches for treating these individuals.

Protective effects of a polyphenol-enriched fraction of the fruit peel of Annona crassiflora Mart. on acute and persistent inflammatory pain.

Different parts of Annona crassiflora Mart., a native species from Brazilian savanna, were traditionally used for the treatment of a wide variety of ailments including arthritis. Thus, this study aimed to investigate the possible antinociceptive and anti-inflammatory properties of a polyphenol-enriched fraction of the fruit peel of A. crassiflora, named here as EtOAc, in mice. Pro-inflammatory cytokines and nitric oxide (NO) production were evaluated in LPS-activated macrophages. Then, EtOAc fraction was administered by oral route in male C57BL/6/J mice, and the animals were submitted to glutamate-induced nociception and complete Freund's adjuvant (CFA)-induced monoarthritis tests to assess nociception (mechanical, spontaneous and cold pain) and inflammation (edema and neutrophil infiltration), and to the open-field and rotarod tests for motor performance analysis. EtOAc fraction inhibited the production of IL-6 and NO in the LPS-induced macrophages, and reduced spontaneous nociception induced by glutamate, without altering the animals' locomotor activity. In addition, the polyphenol-enriched fraction was able to revert the early and late hyperalgesia induced by CFA, as well as edema at the acute phase. Reduction of myeloperoxidase activity and inflammatory cell infiltration was observed in the paw tissue of mice injected with CFA and treated with EtOAc fraction. Together, our results support the antinociceptive and anti-inflammatory effects of the polyphenol-enriched fraction of A. crassiflora fruit peel and suggest that these effects are triggered, at least in part, by suppressing pro-inflammatory cytokines and neutrophils infiltration.

Ionizing radiation and bone quality: time-dependent effects.

BACKGROUND: The aim of this study was to evaluate the ionizing radiation (IR) effects on rat bone 30 and 60 days after irradiation. METHODS: Wistar rats were submitted to IR (30 Gy) on the left leg and were euthanized after 30 and 60 days. The legs were divided into four groups according to the treatment and euthanization time: C30 and C60 (right leg-without IR), IR30 and IR60 (left leg-with IR). RESULTS: CT analysis showed more radiodensity in C60 compared with other groups, and IR60 showed more radiodensity than IR30. In histomorphometric analysis, C30 showed lower bone matrix values compared with IR30 and C60. Lacunarity analyses showed more homogeneous bone channel distribution in C30 than IR30. ATR-FTIR showed decrease in ratio of mature and immature crosslinks in IR30 compared with C30. Crystallinity Index was decrease in IR60 compared with C60. The Amide III + Collagen/HA ratio was increased in C60 compared with C30; however this ratio decreased in IR60 compared with IR30. Biomechanical analysis showed lower values in IR groups in both time. CONCLUSIONS: IR damaged bone quality and decreased stiffness. Moreover, the results suggested that the deleterious effects of IR increased in the late time points.

Effect of ionizing radiation after-therapy interval on bone: histomorphometric and biomechanical characteristics.

OBJECTIVES: This study aimed to evaluate the effects of radiotherapy on biomechanical, histomorphometric, and microstructural characteristics of bone, in diverse periods, compared with intact bone tissue. MATERIALS AND METHODS: Eighteen adult male New Zealand rabbits were treated with a single radiation dose of 30 Gy. The animals were randomly divided into six groups: NoIr, control group, no radiation, and five irradiated groups sacrificed after 24 h (Ir24h), 7 (Ir7d), 14 (Ir14d), 21 (Ir21d), and 28 (Ir28d) days. After these periods, the animals were sacrificed and their tibias (n = 6) evaluated using three-point bending test to calculate the ultimate force, work to failure, and bone stiffness. Dynamic indentation test was used to quantify Vickers hardness and elasticity modulus of bone tissue. Micro-CT was used to analyze the cortical volume (CtV), cortical thickness (CtTh), and porosity (Ct.Po). Histomorphometric assessment was based on the lacunarity of bone tissue. Data were analyzed using one-way ANOVA and Kruskal-Wallis tests followed by Tukey, Dunnet, and Dunn's post-tests (P < 0.05). RESULTS: The ultimate force, work to failure, stiffness, elastic modulus, and Vickers hardness values of irradiated bone were significantly lower that non-irradiated bone. Irradiated bone showed significantly lower CtTh and CtV values and higher CtPo than non-irradiated bone. No significant difference was found for lacunarity between non-irradiated bone and irradiated bone. CONCLUSIONS: Ionizing radiation decreases normal anisotropy on microarchitecture of cortical bone, and increases bone fragility compared with non-irradiated bone. Further, these changes were seen after longer periods (e.g., 14 and 21 days), and not immediately after radiation therapy. CLINICAL RELEVANCE: The radiotherapy reduces bone mechanical properties and the normal structure of organic and inorganic bone matrix. For studying the protocols to protect the radiotherapy effect using rabbit model, the use of the sacrificing period between 14 and 21 days is recommended.

Influence of Platelet-Poor Plasma on Angiogenesis and Maintenance of Volume in Autogenous Bone Grafts.

PURPOSE: The aim of this study was to evaluate the effect of different storage media on angiogenesis and maintaining autogenous bone graft volume in rabbits. MATERIAL AND METHODS: Two grafts were removed bilaterally from the calvaria of 18 rabbits. One graft was removed and immediately fixed in the right mandibular angle (control group). The other graft was stored for 30 minutes in 1 of the following storage media (n = 6): saline solution (saline group), air exposure (dry group), or platelet-poor plasma (PPP group) and then retained by a screw in the right mandibular angle in the same animal. Four weeks later the animals were euthanized, and the grafted areas were harvested, fixed in 10% phosphate buffered formaldehyde solution, and embedded in paraffin. The 5-µm semi-serial sections were stained in hematoxylin and eosin and Mallory trichrome. RESULTS: Histologic analysis of all groups showed the bone graft was vascularized and well incorporated into the recipient site. The number of blood vessels decreased in the saline and dry groups compared with the control group (P < .03); in contrast, the number of blood vessels increased in the PPP group (P < .05). There were fewer osteoclasts in the saline group compared with the control group (P < .05). Furthermore, the saline group showed larger numbers of blood vessels than the dry group (P < .01). The PPP group showed larger bone graft volumes compared with the dry and saline groups (P < .01). In addition, the saline group showed larger bone graft volumes than the dry group (P < .01). CONCLUSIONS: PPP improved angiogenesis, maintained the volume of the autogenous bone graft, and was a better storage medium during the trans-surgical period than the dry and saline media.

Use of Micro-Computed Tomography for Bone Evaluation in Dentistry.

Micro computed tomography (µCT) follows the same principle of computed-tomography used for patients, however providing higher-resolution. Using a non-destructive approach, samples can be scanned, and each section obtained is used to build a volume using tridimensional reconstruction. For bone analysis, it is possible to obtain information about the tissue's microarchitecture and composition. According to the characteristics of the bone sample (e.g. human or animal origin, long or irregular shape, epiphysis or diaphysis region) the pre-scanning parameters must be defined. The resolution (i.e. voxel size) should be chosen taking into account the features that will be evaluated, and the necessity to identify inner structures (e.g. bone channels and osteocyte lacunae). The region of interest should be delimited, and the threshold that defines the bone tissue set in order to proceed with binarization to separate the voxels representing bone from the other structures (channels, resorption areas, and medullary space). Cancellous bone is evaluated by means of the trabeculae characteristics and their connectivity. The cortex is evaluated in relation to the thickness and porosity. Bone mineral density can also be measured, by the amount of hydroxyapatite. Other parameters such as structure-model-index, anisotropy, and fractal dimension can be assessed. In conclusion, intrinsic and extrinsic determinants of bone quality can be assessed by µCT. In dentistry, this method can be used for evaluating bone loss, alterations in bone metabolism, or the effects of using drugs that impair bone remodeling, and also to assess the success rate of bone repair or surgical procedures.

Use of micro-computed tomography for bone evaluation in dentistry

Abstract Micro computed tomography (µCT) follows the same principle of computed-tomography used for patients, however providing higher-resolution. Using a non-destructive approach, samples can be scanned, and each section obtained is used to build a volume using tridimensional reconstruction. For bone analysis, it is possible to obtain information about the tissue's microarchitecture and composition. According to the characteristics of the bone sample (e.g. human or animal origin, long or irregular shape, epiphysis or diaphysis region) the pre-scanning parameters must be defined. The resolution (i.e. voxel size) should be chosen taking into account the features that will be evaluated, and the necessity to identify inner structures (e.g. bone channels and osteocyte lacunae). The region of interest should be delimited, and the threshold that defines the bone tissue set in order to proceed with binarization to separate the voxels representing bone from the other structures (channels, resorption areas, and medullary space). Cancellous bone is evaluated by means of the trabeculae characteristics and their connectivity. The cortex is evaluated in relation to the thickness and porosity. Bone mineral density can also be measured, by the amount of hydroxyapatite. Other parameters such as structure-model-index, anisotropy, and fractal dimension can be assessed. In conclusion, intrinsic and extrinsic determinants of bone quality can be assessed by µCT. In dentistry, this method can be used for evaluating bone loss, alterations in bone metabolism, or the effects of using drugs that impair bone remodeling, and also to assess the success rate of bone repair or surgical procedures.

Resumo A microtomografia computadorizada segue o mesmo princípio da tomografia computadorizada utilizada para avaliação dos pacientes, mas neste caso, é empregada para pequenas amostras com alta resolução. De forma não destrutiva, as amostras podem ser escaneadas, e cada fatia obtida é organizada de forma seriada para formar um volume tridimensional (3D). Para análise óssea, é possível obter informações de microarquitetura e composição mineral, permitindo avaliação distinta entre diferentes sítios. De acordo com as características de cada amostra óssea, como amostras de humanos, animais, ossos longos ou achatados, epífise ou diáfise, etc, devem ser definidos os parâmetros pré-escaneamento com a resolução desejada, levando em consideração quais informações serão extraídas da avaliação. Depois do escaneamento e da reconstrução, deve-se proceder com a seleção da região de interesse (ROI), e depois seguir com o processo de binarização, que se caracteriza pela escolha de um limiar que define os voxels que compõem a região de osso e àqueles que compõem a região dos buracos (canais, áreas de reabsorção e espaço medular). No osso trabecular e no reparo os parâmetros avaliados se baseiam nas características das trabéculas e sua conectividade. No osso cortical os parâmetros estão relacionados com a espessura e porosidade. Além dos parâmetros de microarquitetura, também é possível avaliar a densidade mineral óssea, calculada por volume de hidroxiapatita. Outros parâmetros também podem ser mensurados, utilizando técnicas computacionais como a análise de textura. Parâmetros intrínsecos e extrínsecos da qualidade óssea podem ser avaliados pela microtomografia computadorizada. Na odontologia, este método pode ser empregado em estudos que objetivem avaliar doenças, alterações metabólicas e medicamentos com repercussão no metabolismo ósseo, e na avaliação do processo de reparo e de técnicas cirúrgicas.

Influence of hyperbaric oxygen on biomechanics and structural bone matrix in type 1 diabetes mellitus rats.

BACKGROUND: The aim of this study was to evaluate the biomechanics and structural bone matrix in diabetic rats subjected to hyperbaric oxygen therapy (HBO). METHODS: Twenty-four male rats were divided into the following groups: Control; Control + HBO; Diabetic, and Diabetic + HBO. Diabetes was induced with streptozotocin (STZ) in the diabetic Groups. After 30 days, HBO was performed every 48h in HBO groups and all animals were euthanized 60 days after diabetic induction. The femur was submitted to a biomechanical (maximum strength, energy-to-failure and stiffness) and Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) analyses (crosslink ratio, crystallinity index, matrix-to-mineral ratio: Amide I + II/Hydroxyapatite (M:MI) and Amide III + Collagen/HA (M:MIII)). RESULTS: In biomechanical analysis, diabetic animals showed lower values of maximum strength, energy and stiffness than non-diabetic animals. However, structural strength and stiffness were increased in groups with HBO compared with non-HBO. ATR-FTIR analysis showed decreased collagen maturity in the ratio of crosslink peaks in diabetic compared with the other groups. The bone from the diabetic groups showed decreased crystallinity compared with non-diabetic groups. M:MI showed no statistical difference between groups. However, M:MIII showed an increased matrix mineral ratio in diabetic+HBO and control+HBO compared with control and diabetic groups. Correlations between mechanical and ATR-FTIR analyses showed significant positive correlation between collagen maturity and stiffness. CONCLUSIONS: Diabetes decreased collagen maturation and the mineral deposition process, thus reducing biomechanical properties. Moreover, the study showed that HBO improved crosslink maturation and increased maximum strength and stiffness in the femur of T1DM animals.

Hyperbaric Oxygen therapy effects on bone regeneration in Type 1 diabetes mellitus in rats.

PURPOSE: The aim of this study was evaluate the effect of HBO on diabetic rats. MATERIALS AND METHODS: Twenty rats were distributed into four groups (n = 5): Control (C); Control + HBO (CH); Diabetes (D) and Diabetes + HBO (DH). Diabetes was induced by streptozotocin, and bone defects were created in both femurs in all animals. HBO therapy began immediately after surgery and was performed daily in the CH and DH groups. After 7 days, the animals were euthanized. The femurs were removed, demineralized, embedded in paraffin, and histologic images were analyzed. RESULTS: Qualitative histologic analyses showed more advanced stage bone regeneration in control groups (C and CH) compared with diabetic groups (D and DH). Histomorphometric analysis showed significantly increased bone neoformation in CH compared with the other groups (p < 0.001). Diabetic Group (D) showed decreased bone neoformation compared with non-diabetic groups (C and CH) (p < 0.001); however DH did not differ from C Group (p > 0.05). The mast cell population increased in CH compared with the other groups (C, D, and DH) (p < 0.05). The mast cell population did not differ between D and DH Groups. CONCLUSIONS: This study showed that HBO therapy improved early bone regeneration in diabetic rats and increased the mast cell population only in non-diabetic animals. HBO was shown to be important treatment for minimizing deleterious effects of diabetes on bone regeneration.