DNA hydrogels for bone regeneration.

DNA-based biomaterials have been proposed for tissue engineering approaches due to their predictable assembly into complex morphologies and ease of functionalization. For bone tissue regeneration, the ability to bind Ca2+ and promote hydroxyapatite (HAP) growth along the DNA backbone combined with their degradation and release of extracellular phosphate, a known promoter of osteogenic differentiation, make DNA-based biomaterials unlike other currently used materials. However, their use as biodegradable scaffolds for bone repair remains scarce. Here, we describe the design and synthesis of DNA hydrogels, gels composed of DNA that swell in water, their interactions in vitro with the osteogenic cell lines MC3T3-E1 and mouse calvarial osteoblast, and their promotion of new bone formation in rat calvarial wounds. We found that DNA hydrogels can be readily synthesized at room temperature, and they promote HAP growth in vitro, as characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Osteogenic cells remain viable when seeded on DNA hydrogels in vitro, as characterized by fluorescence microscopy. In vivo, DNA hydrogels promote the formation of new bone in rat calvarial critical size defects, as characterized by micro-computed tomography and histology. This study uses DNA hydrogels as a potential therapeutic biomaterial for regenerating lost bone.

Ozone therapy effect in medication-related osteonecrosis of the jaw as prevention or treatment: microtomographic, confocal laser microscopy and histomorphometric analysis.

OBJECTIVE: This study aimed to evaluate the efficacy of ozone therapy in the preoperative (prevention) and/or postoperative (treatment) of MRONJ. MATERIAL AND METHODS: Forty male Wistar rats were caudally treated with zoledronic acid (ZOL) and to ozone therapy before extraction (prevention, POG), after extraction (treatment, TOG), or both (prevention and treatment, TPOG), and treated with saline (SAL). The animals received intramuscular fluorochrome (calcein and alizarin), and 28 days postoperatively, they were euthanized, and the tissues were subjected to microtomographic computed tomography (microCT), LASER confocal, and histomorphometric analyses. RESULTS: Micro-CT showed a higher bone volume fraction average in all groups than that in the ZOL group (P < 0.001), the ZOL group showed high porosity (P = 0.03), and trabecular separation was greater in the TOG group than in the POG group (P < 0.05). The mineral apposition rate of the POG group was high (20.46 ± 6.31) (P < 0.001), followed by the TOG group (20.32 ± 7.4). The TOG group presented the highest mean newly formed bone area (68.322 ± 25.296) compared with the ZOL group (P < 0.05), followed by the SAL group (66.039 ± 28.379) and ZOL groups (60.856 ± 28.425). CONCLUSIONS: Ozone therapy modulated alveolar bone repair in animals treated with ZOL, mainly after surgery trauma, leading to bone formation as healing tissue. CLINICAL RELEVANCE: Osteonecrosis has been a challenge in dentistry, and owing to the lack of a consensus regarding therapy, studies presenting new therapies are important, and ozone has been one of the therapies explored empirically.

Normoglycemia partially recovers the disrupted osteoblast differentiation of mesenchymal stem cells induced by type 1 but not type 2 diabetes mellitus.

Type 1 (T1DM) and type 2 (T2DM) diabetes mellitus are characterized by changes in glucose metabolism and cause bone damage via a variety of mechanisms, including effects on osteoblasts. We aimed to evaluate the osteoblast differentiation of mesenchymal stem cells (MSCs) from rats with T1DM or T2DM and the effects of removing the hyperglycemic stimulus on the osteogenic potential of these cells. MSCs from healthy rats were cultured in normoglycemic medium, whereas MSCs from rats with T1DM or T2DM were cultured in hyperglycemic or normoglycemic medium. T1DM and T2DM reduced osteoblast differentiation of MSCs grown in hyperglycemic media, with T1DM having a more pronounced effect, as evidenced by alkaline phosphatase activity, RUNX2 protein expression, and extracellular matrix mineralization, and modulated the gene expression of several components of the bone morphogenetic protein signaling pathway. The restoration of the normoglycemic environment partially recovers the osteogenic potential of MSCs from rats with T1DM but not with T2DM. Our findings highlight the need for specific therapies to treat T1DM- or T2DM-induced bone loss, as both disrupt osteoblast differentiation at distinct levels and likely through different mechanisms.

Effects of platelet-rich fibrin produced by three centrifugation protocols on bone neoformation in defects created in rat calvaria.

This study evaluated the potential of Leukocyte-platelet-rich fibrin (L-PRF; fixed angle centrifugation protocol), Advanced-platelet-rich fibrin (A-PRF; low-speed fixed angle centrifugation protocol), and Horizontal-platelet-rich fibrin (H-PRF; horizontal centrifugation protocol) in bone neoformation in critical size defects (CSDs) in rat calvaria. Thirty-two rats were divided into groups: Control (C), L-PRF, A-PRF, and H-PRF. 5 mm diameter CSDs were created in the animals' calvaria. Defects from group Control (C) were filled with blood clots, while defects from groups L-PRF, A-PRF, and H-PRF were filled with respective platelet-rich fibrin (PRF) membranes. L-PRF, A-PRF, and H-PRF were prepared from animal blood collection and specific centrifugation protocols. At 14 and 30 days, calcein (CA) and alizarin (AL) injections were performed, respectively. Animals were euthanized at 35 days. Microtomographic, laser confocal microscopy, and histomorphometric analyzes were performed. Data were statistically analyzed (ANOVA, Tukey, p < .05). L-PRF, A-PRF, and H-PRF groups showed higher values of bone volume (BV), newly formed bone area (NFBA), and precipitation of CA and AL than the C group (p < .05). The H-PRF group showed higher values of BV, number of trabeculae (Tb. N), NFBA, and higher precipitation of AL than the A-PRF and L-PRF groups (p < .05). Therefore, it can be concluded that: i) L-PRF, A-PRF, and H-PRF potentiate bone neoformation in CSDs in rat calvaria; ii) H-PRF demonstrated more biological potential for bone healing.

After tooth loss, the alveolar bone (which supports the teeth) undergoes a natural process called bone remodeling, which can lead to significant decreases in bone height and thickness over time. Faced with the need to replace missing teeth, especially when it comes to dental implants, the lack of supporting tissues can compromise their correct positioning, leading to negative impacts on the success and longevity of the treatment. Therefore, over the years, several materials and procedures have been proposed to preserve and regenerate oral tissues. Leukocyte-platelet-rich fibrin (L-PRF) consists of a membrane obtained by centrifuging the patient's blood in a fixed-angle centrifuge, allowing cells to be available to stimulate tissue regeneration directly at the place of action. Several reports demonstrate high potential in stimulating the formation of new tissues using L-PRF. In recent years, new protocols have been proposed to increase cell concentration and improve the regenerative potential of these membranes, changing the speed and time of centrifugation and introducing horizontal centrifugation. However, there still needs to be concrete evidence of the superiority of the new protocols in relation to the original protocol. In this study, we evaluated the healing of defects created in rat calvaria using platelet aggregates obtained through different centrifugation protocols. Within the limits of this study, it can be concluded that platelet aggregates improve bone healing, and horizontal centrifugation promotes more satisfactory results compared to fixed-angle protocols.

Combination of leukocyte and platelet-rich fibrin and demineralized bovine bone graft enhanced bone formation and healing after maxillary sinus augmentation: a randomized clinical trial.

BACKGROUND AND OBJECTIVE: The resorption of alveolar ridge bone and maxillary sinus pneumatization are challenges to implant-supported prosthetic rehabilitation. Bone regeneration using bone substitutes and growth factors are alternatives for maxillary sinus augmentation (MSA). Therefore, we sought to evaluate the effects of the association between leukocyte and platelet-rich fibrin (L-PRF) and deproteinized bovine bone mineral (DBBM) in MSA procedures. MATERIALS AND METHODS: Thirty-six maxillary sinuses from 24 individuals were included in this randomized clinical trial. The maxillary sinuses were randomly grafted with LPRF and DBBM (test group) or grafted only with DBBM (positive control). Dental implants were installed in the test group following two periods of evaluation: after 4 (DBBM+LPRF4) and 8 (DBBM+LPFR8) months of sinus graft healing, while the control group received implants only after 8 months. Cone beam computed tomography (CBCT) was taken 1 week after surgery (T1) and before implant placement (T2). Bone samples were collected during implant placement for histomorphometric and immunohistochemical (IHC) analysis. The primary implant stability was assessed by resonance frequency analysis. RESULTS: CBCT analysis demonstrated a significant decrease in bone volume from T1 to T2 in all groups without differences among them. Histologically, the test group showed significantly increase in bone neoformation in both periods of evaluation (LPRF+DBBM4: 44.70±14.01%; LPRF+DBBM8: 46.56±12.25%) compared to the control group (32.34±9.49%). The control group showed the highest percentage of residual graft. IHC analysis showed increased staining intensity of osteocalcin (OCN), vascular endothelial growth factor (VEGF), and runt related transcription factor 2 (RUNX-2) in LPRF+DBBM4 group, and osteopontin (OPN) in the L-PRF+DBBM8. Primary implant stability was successfully achieved (above 60 in implant stability quotient) in all the evaluated groups. CONCLUSION: Combination of L-PRF and DBBM increased and accelerated new bone formation allowing early implant placement probably due to the higher protein expression of RUNX2, VEGF, OCN, and OPN. These data suggest that the use of L-PRF might be an interesting alternative to use in combination with DBBM for augment the maxillary sinuses allowing the installation of appropriate length implants in shorter period of time. CLINICAL RELEVANCE: This study showed improvement in bone neoformation and accelerated healing when associating L-PRF and DBBM for maxillary sinus augmentation procedures. TRIAL REGISTRATION: This study was registered before participant recruitment in Brazilian Registry of Clinical Trials (ReBEC - RBR-95m73t).

Synergic Action of Systemic Risedronate and Local Rutherpy in Peri-implantar Repair of Ovariectomized Rats: Biomechanical and Molecular Analysis.

Postmenopausal osteoporosis and poor dietary habits can lead to overweightness and obesity. Bisphosphonates are the first-line treatment for osteoporosis. However, some studies show that they may increase the risk of osteonecrosis of the jaw. Considering the antimicrobial, angiogenic and vasodilatory potential of nitric oxide, this study aims to evaluate the local activity of this substance during the placement of surface-treated implants. Seventy-two Wistar rats were divided into three groups: SHAM (SHAM surgery), OVX + HD (ovariectomy + cafeteria diet), and OVX + HD + RIS (ovariectomy + cafeteria diet + sodium risedronate treatment), which were further subdivided according to the surface treatment of the future implant: CONV (conventional), TE10, or TE100 (TERPY at 10 or 100 µM concentration); n = 8 per subgroup. The animals underwent surgery for implant installation in the proximal tibia metaphysis and were euthanized after 28 days. Data obtained from removal torque and RT-PCR (OPG, RANKL, ALP, IBSP and VEGF expression) were subjected to statistical analysis at 5% significance level. For biomechanical analysis, TE10 produced better results in the OVX + HD group (7.4 N/cm, SD = 0.6819). Molecular analysis showed: (1) significant increase in OPG gene expression in OVX groups with TE10; (2) decreased RANKL expression in OVX + HD + RIS compared to OVX + HD; (3) significantly increased expressions of IBSP and VEGF for OVX + HD + RIS TE10. At its lowest concentration, TERPY has the potential to improve peri-implant conditions.

Biomechanical effects of different materials for an occlusal device on implant-supported rehabilitation in a tooth clenching situation. A 3D finite element analysis.

PURPOSE: The purpose of this 3D finite element analysis was to evaluate the biomechanical effects of different materials used to fabricate occlusal devices to achieve stress distribution in simulated abutment screws, dental implants, and peri-implant bone tissue in individuals who clench their teeth. MATERIALS AND METHODS: Eight 3D models simulated a posterior maxillary bone block with three external hexagon implants (Ø4.0 × 7.0 mm) supporting a 3-unit screw-retained metal-ceramic prosthesis with different crown connection (splinting), and the use of an occlusal device (OD). The OD was modeled to be 2-mm thick. ANSYS 19.2 software was used to generate the finite-element models in the pre-and post-processing phases. Simulated abutment screws and dental implants were evaluated by von Mises stress maps, and simulated bone was evaluated by maximum principal stress and microstrain maps by using a finite element software program. RESULTS: The highest stress values in the dental implants and screws were observed in single crowns without OD (M1). Furthermore, the highest stress values and bone tissue strain were found in single crowns without OD (M1). The simulated material for the OD did not cause many discrepancies in terms of the stress magnitude in the simulated dental implant and abutment screw for both single and splinted crowns; however, more rigid materials exhibited lower stress values. CONCLUSION: The use of OD was effective in reducing stress in the simulated implants and abutment screws and stress and strain in the simulated bone tissue. The material used to simulate the OD influenced the biomechanical behavior of implant-supported fixed prostheses, whereas splints with rigid materials such as PEEK and PMMA exhibited better biomechanical behavior.

The Interplay of Raloxifene and Sonochemical Bio-Oss in Early Maxillary Sinus Bone Regeneration: A Histological and Immunohistochemical Analysis in Rabbits.

The study aimed to assess the efficacy of using Raloxifene with ultrasonic processing to enhance Bio-Oss®, a bone graft substitute, for maxillary sinus bone height reconstruction. A total of 24 rabbit maxillary sinuses were distributed into three groups, each receiving different treatments: Bio-Oss® only, sonicated Bio-Oss, and sonicated Bio-Oss® with Raloxifene. Surgical procedures and subsequent histomorphometric and immunohistochemistry analyses were conducted to evaluate the bone formation, connective tissue, and remaining biomaterial, as well as the osteoblastic differentiation and maturation of collagen fibers. Results indicated that the sonicated Bio-Oss® and Bio-Oss® groups showed similar histological behavior and bone formation, but the Raloxifene group displayed inflammatory infiltrate, low bone formation, and disorganized connective tissue. The statistical analysis confirmed significant differences between the groups in terms of bone formation, connective tissue, and remaining biomaterial. In conclusion, the study found that while sonicated Bio-Oss® performed comparably to Bio-Oss® alone, the addition of Raloxifene led to an unexpected delay in bone repair. The findings stress the importance of histological evaluation for accurate bone repair assessment and the necessity for further investigation into the local application of Raloxifene. Future research may focus on optimizing bone substitutes with growth factors to improve bone repair.

Effects of premature contact in maxillary alveolar bone in rats: relationship between experimental analyses and a micro scale FEA computational simulation study.

OBJECTIVE: The aim of the investigation was to evaluate the maxillary alveolar bone morphology, bone architecture, and bone turnover in relation to the mechanical strain distribution in rats with dental premature contact. MATERIALS AND METHODS: Fifty 2-month-old male Wistar rats were used. The premature contact group (N=40) received a unilateral (right side) resin cementation on the occlusal surface of the upper first molar. The animals were distributed in 4 subgroups according to the periods of euthanasia: 7, 14, 21, and 28 days after cementation (N=10, for each period). For the control group (N=10), the teeth were kept without resin, featuring a normal occlusion. The pieces including the upper first molars, alveolar bone, and periodontal tissue were processed to histological and immunohistochemical evaluation of RANK-L and TRAP protein expression. A three-dimensional bone microarchitecture analysis was performed, where the heads of animals were scanned using microtomography and analyzed using CT-Analyser software (Bruker, Kontich, Belgium). In the computer simulation by finite element analysis, two micro-scaled three-dimensional finite element models of first molar and dentoalveolar tissues were constructed, in representation of control and premature contact groups, using Materialise MIMICS Academic Research v18 (Materialise, Leuven, Belgium). The analysis was set to simulate a maxillary molar biting during the power stroke phase. The total deformation, equivalent strain, and minimum principal strain distribution were calculated. RESULTS: The expression of RANK-L and TRAP presented higher positive ratio in the 7-day period compared to the control group. The three-dimensional morphometry showed decrease of bone volume in the premature contact, with significant values between the control and the 7-day and 14-day groups (P = 0.007). In FEA, the premature contact model presented a uniform compressive strain distribution in the alveolar bone crest compared to a non-uniform compressive strain distribution in the control model. CONCLUSIONS: The results from FEA, 3D bone microarchitecture, and histological and immunohistochemical analyses showed that a model with dental traumatic occlusion resulted in changes of alveolar bone mechanobiology and, consequently, its morphology. CLINICAL RELEVANCE: These results could be applied in dental treatment planning bringing biological and mechanical feedback to provide an effective mechanism to obtain physiological bone loss responses. Furthermore, this association between experimental and computational analyses will be important to figure out the alveolar bone response to mechanical stimulation in different clinical conditions.

The Risk of Osseointegration in the Coronavirus Disease 19 Pandemic.

ABSTRACT: Coronavirus disease 19 (COVID-19) is associated with respiratory complications but also with alterations on bone metabolism. Coronavirus disease 19, therefore, might be a risk factor for osseointegration. Recent studies suggest that severe acute respiratory syndrome coronavirus 2 is related with bone abnormalities mainly for act via renin-angiotensin system. This report aims to list the bone alterations caused by coronavirus disease 19 and the possible consequences on the peri-implant bone healing. The current data add to the accumulating knowledge that coronavirus disease 19 may negatively impact the osseointegration and it requires further research.

Improvement of bone repair with l-PRF and bovine bone in calvaria of rats. histometric and immunohistochemical study.

OBJECTIVES: The effect of leucocyte- and platelet-rich fibrin (L-PRF), associated with DBBM (deproteinized bovine bone mineral; Bio-Oss®) was investigated and compared with autogenous bone graft as a standard material for filling bone defects. MATERIAL AND METHODS: A defect of 5 mm in diameter was performed in 40 calvaria of rats. The animals were divided into 5 groups and received blood clot (CO), autogenous bone (AUT), DBBM (BIO), L-PRF, or DBBM associated with L-PRF (BIO-LPRF). After 4 and 8 weeks, bone regeneration was assessed by histometric and immunohistochemical analyses. RESULTS: The highest mean percentage of bone formation found at 4 and 8 weeks was observed for the BIO-L-PRF group (54.0% ± 2.8 and 63.6% ± 2.2). The lowest mean percentage at 4 and 8 weeks was observed for the CO group (16.7% ± 2.5 and 20.5% ± 1.0). There was statistical similarity among the AUT, BIO, and L-PRF groups. The expressions OC, RUNX 2, and VEGF showed a favorable aspect in the formation of new bone for BIO-L-PRF. VEGF was the marker with the highest expression because it was related to the initial healing process, promoting the migration and proliferation of endothelial cells in the region of the defect. Even after weeks, VEGF maintained a moderate expression. CONCLUSIONS: The association of L-PRF with DBBM improved bone repair when these biomaterials were inserted into the defects of the calvaria of rats. CLINICAL RELEVANCE: This reinforces the good performance of bovine bone and L-PRF as filler materials, especially when associated.

Effect of intermittent teriparatide (PTH 1-34) on the alveolar healing process in orchiectomized rats.

OBJECTIVE: To evaluate intermittent teriparatide therapy's influence on the alveolar healing process in rats with induced osteoporosis. MATERIALS AND METHODS: Fifty-four male rats were divided into three groups: fictitious surgery (SHAM), bilateral orchiectomy (ORQ NT), and bilateral orchiectomy treated with teriparatide (ORQ TERI). Right upper incisor extraction was performed. After 14 and 42 days, the rats were euthanized. Immunolabeling analysis was performed in order to characterize bone turnover through Wnt, alcaline phosphatase, osteocalcin, and TRAP presence in tissue; micro-CT analysis was performed in order to determine the bone volume fraction (BV/TV), trabecular thickness, separation, and number (Tb.Th, Tb.Sp, Tb.N). For the micro-CT data, statistical analysis was performed through one-way ANOVA and Tukey post-test, for parametrical data, with significance level adopted in p < 0.05. Days, Wnt, alkaline phosphatase, and osteocalcin revealed more labeling for ORQ TERI and less for TRAP. For the Tb.N in the ORQ NT group was 0.496 mm, a significant statistical difference was observed between the groups of ORQ NT and ORQ TERI (p < 0.05). For the BV/TV, Tb.Sp, and Tb.Th parameters, no significant statistical difference was observed among the three experimental groups (p > 0.05). CONCLUSIONS: Treatment with intermittent teriparatide reverted impairment in the metabolism of repairing bone tissue in orchiectomized animals. CLINICAL RELEVANCE: Cases of decreased bone density such as osteoporosis can lead to delayed alveolar repair process. PTH 1-34 has been shown to be a medication that improves this repair, making bone of low quality into one with normal features.

Use of Calcium Phosphate Cement for Repairing Bone Defects: Histomorphometric and Immunohistochemical Analyses.

This study aimed to assess the repair of surgically created bone defects filled with blood clot, autogenous bone, and calcium phosphate cement, by histomorphometric and immunohistochemical analyses. Ten adult male rabbits were used. Three bone defects were prepared with an 8-mm diameter trephine bur in the parietal region of each animal and filled with blood clot (Group BC), autogenous bone (Group AB), and calcium phosphate bone cement (Group CPC). The animals were euthanized at 40 and 90 postoperative days. The sections were subjected to histomorphometric analysis of the new bone formed inside the calvarial defects and immunohistochemical staining to determine the expression of osteocalcin (OC), osteopontin (OP), and tartrate-resistant acid phosphatase (TRAP) proteins. Histomorphometric data were analyzed statistically by analysis of variance and Tukey's post hoc test at 5% significance level. In the results at 40 and 90 days, Group AB differed significantly from Group CPC regarding the area of newly formed bone. The immunohistochemical analysis revealed expression of OP, OC, and TRAP proteins in all groups. Group AB showed prevalence of OC and OP, and lower TRAP expression. Therefore, the calcium phosphate bone cement assessed in the present study did not accelerate the protein expression dynamics during bone healing, compared with the autogenous group.

Strategy of Mandibular Central Arch Reconstruction After Firearm Injury.

Gunshot wounds can cause extensive destruction of soft tissue and bone, and the maxillofacial region is often affected. The reconstructive treatment is complex due to the difficulty to reestablish the central arch mandibular contour and volume. Moreover, the goal is to avoid postoperative infections and obtain bone graft neovascularization. Therefore, this report shows a clinical case of a patient presenting mandibular deformity with a mandibular central arch discontinuity caused by a firearm injury. The strategy to the reconstructive treatment as performed with a condensed and stabilized particulate autogenous bone graft was essential and effectiveness. After 1 year, it was obtained a satisfactory result to the patient.

Bone repair with raloxifene and bioglass nanoceramic composite in animal experiment.

OBJECTIVE: This study proposes to evaluate, by means of microtomographic analysis, the topical potential of raloxifene combined with BioGran® through the sonochemical method in the repair of critical bone defects in the calvaria of rats. The hypothesis was that the homogenization of Raloxifene to Biogran at the 20% concentration would improve the bone repair at the grafted site. MATERIALS AND METHODS: A 5-mm calvaria bone defect was induced in three groups: CTR (100% BioGran®); RAL10 (90% BioGran® and 10% raloxifene), and RAL20 (80% BioGran® and 20% raloxifene). The animals were euthanized after 30 days and the microCT analysis was then performed to evaluate the parameters bone volume (BV), bone volume percentage (BV/TV), trabecular bone thickness (Tb.Th), and the separation and number of trabeculae (Tb.Sp and Tb.N). The obtained results were compared using ANOVA and Tukey test (p < 0.05). RESULTS: The best results were found for the CTR and RAL20 groups, in which the BV, BV/TV, Tb.Sp, and Tb.N parameters were statistically significant in comparison with RAL10 (p < 0.05). CONCLUSIONS: In view of the results obtained in this experiment, we can conclude that BioGran® alone or in an 80/20 mass concentration with raloxifene can lead to favorable bone formation.

Losartan reverses impaired osseointegration in spontaneously hypertensive rats.

OBJECTIVE: Hypertension is not only associated with cardiovascular diseases but also with alterations in bone quality. Hypertension therefore might be a risk factor for osseointegration. Preclinical studies suggest that losartan, an angiotensin II receptor blocker widely used to treat hypertension, has a beneficial effect in graft consolidation. Here, we determine the effect of hypertension and losartan on osseointegration. METHODS: We used spontaneously hypertensive rats (SHR) and normotensive Wistar albinus rats receiving losartan (30 mg/kg, p.o.) or left untreated. After 1 week, titanium miniscrews were inserted into the tibia. Sixty days after implantation, implant stability was evaluated by removal torque measurement considered the primary endpoint. Microcomputed tomography and histomorphometric analysis were secondary endpoints. RESULTS: Losartan increased the removal torque in the hypertensive SHR group to levels of the Wistar controls. While the cortical parameters of osseointegration remained unchanged, losartan increased medullary bone formation. Microcomputed tomography revealed a higher bone volume per tissue volume and trabecular thickness in the SHR rats treated with losartan. Histomorphometric analysis further showed that losartan significantly increased the thickness of newly formed bone in medullary area in hypertensive SHR rats. Losartan did not significantly alter the parameters of osseointegration in normotensive rats. CONCLUSIONS: The data presented suggest that the angiotensin II receptor antagonist losartan increases the medullary parameters of osseointegration in a tibia model of spontaneously hypertensive rats. Considering the study limitations, understanding the impact of hypertension and the respective drugs on osseointegration requires further research.

Prospective and Randomized Evaluation of ChronOS and Bio-Oss in Human Maxillary Sinuses: Histomorphometric and Immunohistochemical Assignment for Runx 2, Vascular Endothelial Growth Factor, and Osteocalcin.

PURPOSE: The aim of this study was to compare ChronOS (ß-tricalcium phosphate), Bio-Oss, and their addition to an autogenous bone graft in a 1:1 ratio in human maxillary sinus bone augmentation. MATERIALS AND METHODS: Thirty maxillary sinuses were divided in 5 groups: group 1 included 6 maxillary sinuses grafted with autogenous bone graft alone; group 2 included 6 maxillary sinuses grafted with ChronOS; group 3 included 6 maxillary sinuses grafted with ChronOS and autogenous bone graft in a 1:1 ratio; group 4 included 6 maxillary sinuses grafted with Bio-Oss; and group 5 included 6 maxillary sinuses grafted with Bio-Oss and autogenous bone graft in a 1:1 ratio. The number of samples for each group was determined by the statistical power test. RESULTS: The median areas of new bone formation in groups 1, 2, 3, 4, and 5 were 121,917.0, 83,787.0, 99,295.0, 65,717.0, and 56,230.0 µm2, respectively. Statistically significant differences were found between groups 3 and 5, groups 1 and 4, and groups 1 and 5 (P < .05). The median areas of remaining biomaterial were 2,900.5, 5,291.0, 2,662.0, 56,258.5, and 64,753.5 µm2 in groups 1, 2, 3, 4 and 5, respectively. Statistically significant differences occurred between groups 1 and 5, groups 3 and 5, and groups 2 and 5 (P < .05). Areas of connective tissue were 67,829.0 ± 22,984.6 µm2 in group 1, 97,445.9 ± 18,983.3 µm2 in group 2, 88,256.0 ± 21,820.5 µm2 in group 3, 65,501.8 ± 6,297.6 in group 4, and 70,203.2 ± 13,421.3 µm2 in group 5. CONCLUSIONS: ChronOS combined with autogenous bone graft presented a behavior similar to that of autogenous bone graft alone. However, the groups treated with Bio-Oss showed immuno-labeling results indicating maturation of grafted bone.

Raloxifene but not alendronate can compensate the impaired osseointegration in osteoporotic rats.

OBJECTIVES: Alendronate and raloxifene, a bisphosphonate and a selective estrogen modulator, respectively, are established osteoporosis therapies. Current evidence suggests that simultaneous application of osteoporosis therapies modulates osseointegration. However, alendronate shows inconsistent findings and raloxifene has not been studied comprehensively. This study aimed to evaluate the bone dynamics and molecular and microstructural features at the peri-implant bone interface in osteoporotic rats. MATERIALS AND METHODS: Thirty female rats underwent ovariectomy and were fed a diet low in calcium and phosphate and treated with alendronate or raloxifene for 30 days or underwent fictional ovariectomy surgery (SHAM) prior to implant insertion in the tibia; osteoporosis therapies continued thereafter. After 42 days, peri-implant bone was evaluated by histometric and micro-CT analysis. Fluorochrome incorporation and gene expression was determined to evaluate bone turnover. RESULTS: We report here that alendronate had no impact on bone-to-implant contacts and the mineral apposition rate. The RANKL/OPG ratio and local bone volume, however, were increased compared to the untreated osteoporotic rats. Even though signaling to bone resorption activity through RANKL production was observed in the alendronate group, the blockade of bone resorption activity that occurs in decorrence to alendronate activity took place and resulted in an increase in bone volume. Raloxifene significantly increased osseointegration in osteoporotic rats, as indicated by bone-to-implant contacts, mineral apposition, and local bone volume. Raloxifene, however, had no considerable impact on the RANKL/OPG ratio compared to untreated osteoporotic rats. As expected, the SH group showed higher bone-to-implant contacts and mineral apposition rates than the untreated osteoporotic rats. CONCLUSIONS: These findings suggest that raloxifene but not alendronate can compensate for the impaired osseointegration in osteoporotic rats. CLINICAL RELEVANCE: Regarding the superiority of raloxifene observed in the improvement of bone dynamics response, this statement suggests that raloxifene could be a good option for osteoporosis patients in oral rehabilitation procedures.

Orbital Emphysema: A Rare Postoperative Complication.

Orbital emphysema can be a rare and severe postoperative complication. Fast and critical diagnosis is essential to avoid permanent visual loss to the patient. Therefore, a case of a male patient victim of a motorcycle accident with a postoperative complication of orbital emphysema has been presented. The immediate diagnosis and treatment of the orbital emphysema revealed to be the main success factors for the resolution of this complication.

Comparative Evaluation of Cell Viability Immediately After Osteotomy for Implants With Drills and Piezosurgery: Immunohistochemistry Analysis.

OBJECTIVE: To evaluate the effect of reusing drills and piezosurgery tips during implant osteotomy on immediate bone cell viability through immunohistochemical analysis. MATERIALS AND METHODS: Six male rabbits were divided into 2 groups and then divided into 5 subgroups-correspond to drills and tips used 10, 20, 30, 40, and 50 times, respectively. All animals received 10 osteotomies in each tibia, by use of the classic drilling procedure in one group (G1) and the piezosurgery device in the other group (G2). For immunohistochemical technique were utilized the osteoprotegerin, RANKL, osteocalcin, and caspase 3. Control procedures were performed by omitting the primary antibodies (negative control). RESULTS: Bone formation and resorption responses presented in more intense way during the piezosurgery. The expression of osteocalcin had become quite intense in piezosurgery groups, but with reduced immunostaining from the 30th osteotomy. The caspase 3 showed the viability of the osteoblast from the 20th osteotomy with piezosurgery and remained constant until the 50th. CONCLUSION: Piezosurgery provides greater osteoblastic cell viability than the system of conventional drilling. CLINICAL RELEVANCE: This study will provide data so that the authors can recycle the drills and tips for implant placement, thus enabling a better cell viability for osseointegration.