Enhancing Bone Healing In Calvarial Critical Size Defect Using Ozone .
Enhancing bone healing in calvarial critical size defect using ozonegel : Histological and histomorphometric analysisMohamed Ahmed Elsholkamy1, Maggie Ahmed Khairy2, Tamer Ahmed Nasr3OriginalArticleAssistant Professor of Oral and Maxillofacial Surgery, Faculty of Dentistry, Suez CanalUniversity, Ismailia, Egypt.1Assistant Professor of Oral and Maxillofacial Surgery, Faculty of Dentistry, October 6University, Cairo, Egypt.2Lecturer of Oral and Maxillofacial Surgery, Faculty of Dentistry, Misr InternationalUniversity, Cairo, Egypt.3ABSTRACTAim: The aim of this study was to examine the validity of the hypothesis that Ozone gel will accelerate bone healingin a critical size defect model experimentally created in rabbit calvaria when mixed with autografts in comparison toautogenous grafts per se.Materials and Methods: A total of twelve adult male New Zealand Rabbits were included in the study. A total of 24standardized bone grafts were harvested from 12 animals after critical size defects were created in calvaria cortical bone,each graft was crushed using a special bone mill device. After bone milling, each bone graft was collected in a specialsterile container, twelve grafts were mixed with normal saline solution (control group) and each one of the rest of thegrafts was mixed with ozone gel. Animals were sacrificed at 4 and 8 weeks’ post-surgery, dual energy x-ray absorptiometry(DEXA) scans were performed for the skull of the rabbits and bone specimens were collected for histological examination.Results: Histomorphometric analysis showed superior results in favor of the ozone treated group represented as asignificantly higher percentage of normal osteocytes and marked increase in area percentage of new bone formation.Additionally, DEXA scan revealed a significant increase in bone mineral density and bone mineral concentration of theozone treated group compared to the control group.Conclusion: The authors believe that according to the available results the use of ozone gel may be cost effective andconvenient owing to its ease of preparation. It is recommended to be used with routine bone grafting procedures as itaccelerates the new bone formation over time giving higher degree of overall maturation and strength.Key Words: Autogenous bone grafts, calvarial, critical size defect, ozone gel, rabbit model.Received: 19 June 2018, Accepted: 29 July 2018Corresponding Author: Nasr, Tamer, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Misr InternationalUniversity, Cairo, Egypt, Tel.: 0100157959, E-mail: tamer.nasr129@gmail.com.ISSN: 2090-097X, May 2018, Vol. 9, No.2INTRODUCTIONIt is a hallmark standard among researchers for testingnew bone substitutes in calvarial defects of the rat andrabbit, followed by testing in the mandibles of dogs andmonkeys using a critical size defect (CSD) which is thediameter of a bone wound such that beyond that amountcomplete calcification of the wound will not occur duringthe lifetime of the animal[11].The complete remodeling process of bone graft andregaining of bone form and strength was the goal ofmultitude of research literature[1-3]. Undisturbed normalbone healing process with the aid of bone grafting materialeither autogenous or synthetic materials gained largeattention in the past decades[4-9].Among recent bone enhancing techniques Ozonetherapy gained access to the field of dentistry in manyapproaches[12-18], there is insufficient evidence in theapplication of ozone in oral and maxillofacial surgery[19].As ozone has a therapeutic effect that facilitates woundhealing and improves the supply of blood, ozone therapycould enhance the stability and predictability of autogenousgrafts.Many materials showed different degrees of successrates and different related complications. This makesautogenous bone the supreme type for grafting in spite ofthe donor site morbidity but surgically augmented heightwith an autogenous block graft decreased to 60% after10months[10].Personal non-commercial use only. OMX copyright 2018. All rights reserved74DOI: 10.21608/OMX.2018.18828
Elsholkamy et al.2.1. Ozone gel preparation.The aim of this study was to examine the validity ofthe hypothesis that Ozone gel will accelerate bone healingin a critical size defect model experimentally created inrabbit calvaria when mixed with autografts in comparisonto autogenous grafts per se.The ozone gel was obtained by bubbling of 25 µ/ml O3 gas through pure olive oil for 2 days until oliveoil transforms from greenish colored liquid status to thewhitish gel status. This procedure was performed by thelongevity Ext 120 ozone generator. (Longevity Extra120,Longevity Co., Canada)MATERIAL AND METHODSThis is an experimental controlled study that includestwo groups; a control group comprised 12 autogenouscalvarial grafts, and a study group comprised 12 autogenouscalvarial grafts mixed with ozone gel. The study wasconducted following the approval of October 6 Univeristyethical committee, faculty of dentistry (Approvalnumber 2017/3) for animal use. A total of twelve adultmale New Zealand Rabbits (Oryctolagus cuniculus) wereincluded in the study with an average weight of 3.5- 4 kg.,age 6 to 8-months-old. Animals were kept in individualcages in a standard day / night cycle of 12 hours. Theywere allowed free access to water and laboratory food. Therabbits were randomly divided into two equal groups asfollows:2.2. Surgical techniqueThe animals were premedicated using midazolam(0.2 mg/kg). General anesthesia was induced byintramuscular injection of ketamine (10 mg/kg of bodyweight), 2% xylazine (4 mg/kg), 0.2% acepromazine(0.15 mg/kg) and an intravenous propofol (2 mg/kg).Local anesthesia (mepivicaine 2% containing 1:100.000levonordephrine) was infiltrated around the surgical site.Prophylactic enrofloxacin antibiotics were administratedvia intravenous route (5 mg/kg of body weight). The skinat the operative site was shaved and scrubbed using 2%iodine solution. A midline incision from the frontal area tothe occipital protuberance was made down to the osseoussurface of the skull, and a full thickness flap was raised toexpose the calvarial surface on both sides of the midline.(Fig. 1) Control group (n 12), receiving only autograftwithout ozone therapy. (Group I). Test group (n 12),receiving graft mixed with ozone gel (Group II)Fig. 1: Photographs showing the midline calvarial incision (A), the calvarial defect after taking the graft (B).Attention was made to avoid perforation of theunderlying dura mater and not to involve the sagittalsuture. A standardized bone graft was obtained fromeach animal using a trephine bur with an inner diameterof 5 mm mounted on a hand piece at 2,000 rpm undercopious saline solution irrigation. The graft consisted ofboth the outer and inner calvaria cortical bone, which wasapproximately 3 mm thick with a diameter of 5 mm. A totalof 24 grafts were harvested from 12 animals, each graftwas crushed using a special bone mill device (Fig 2).After bone milling, each bone graft was collected in aspecial sterile container. After preparing the recipient site,bone graft that was grounded with a manual bone crushedmixed with normal saline, and was implanted in the bonedefect of Group I. In Group II same procedure was doneand bone graft was mixed by Ozone gel and implanted inthe bony defect saline solution75
CALVARIAL CRITICALFig. 2: Photographs showing (A) The graft within the bone mill, (B) The graft after milling.The soft tissues were then repositioned and suturedto achieve primary closure (4-0 silk). To preventpostoperative infection, ceftriaxone was given to theanimals as intramuscular injections for 3 d (30 mg/kg).They were also given an intramuscular analgesic, 4 mg/kgcarprofen every 24 h for 3 days, starting immediately afterthe operation.than 50% of their lacunae were considered normal, andthose that occupied 50% or less of their lacunae wereconsidered abnormal. Empty lacunae were also counted.The sequence of bone repair was observed histologicallyby examining the two groups at either 7 or 14 days bymanually counting the area percentage of new boneand expressing it as areas (in mm2). To standardize ourhistomorphometric analysis, we based our measurementsin part on the work of Messora et al.[21], The total area(TA) to be analyzed corresponded to the entire area ofthe original surgical defect. The mineral deposition area(MDA) was delineated within the confines of the TA. TheTA was measured in mm2 and was considered 100% ofthe area to be analyzed. The MDA was also measured inmm2 and calculated as a percentage of TA. The numberof inflammatory cell infiltrate to the marrow spaces werealso recorded for each histological section obtained in thetwo-time intervals.2. 3. Histological techniqueUpon completion of the experimental periods foreach group, the animals were euthanized by over doseanesthesia, and the area of the original surgical defect andthe surrounding tissues were removed en bloc and fixedin 10% buffered formalin for 48h hours. The specimenswere then decalcified in 20% formic acid and 10 % sodiumcitrate for 10 days, cut transversely next to the hole, andembedded in paraffin according to standard histologicalprocedures. Five micrometer thick serial sections were cut,stained with hematoxylin and eosin to be evaluated undera light microscope by a single oral pathologist. (BlindEvaluation)2. 4. Bone densitometryThe skulls of the animals were harvested, after animalscarification, and a dual energy x-ray absorptiometry(DEXA) scan was performed for each skull using aperipheral DEXA device. The area of interest was detected,centralized and scanned using an examination surface areaof 4 0.5 cm2. Bone mineral density (BMD module wasverified and represented. The data for each group at 7 and14 days were recorded in table for statistical analysis.The best sections (which were given codes) wereused for evaluation for osteoblastic activity, new boneformation or any inflammatory reactions. The Pathologist’sobservations were tabulated and then the codes wererevealed by the authors.Leica application suite (LAS V4) system (Switzerland)and Image J image analysis software were used to lock onthese preselected areas for each histological section. Foreach of the two studied groups a differential osteocytecount (normal osteocyte, abnormal osteocyte, emptylacunae) was performed for each section. The osteocyteswere classified according to the morphological criteriaestablished by Moura et al.[20], those that occupied moreRESULTS3.1. Animal recoveryHealing progressed uneventfully in all animals and nopostoperative complications were noticed.76
Elsholkamy et al.3 .2. Descriptive histologyrate across the entire defect. The initial synthesis of bonerepair at 7 days was woven and confined adjacent to the preexisting lamellar cortical bone. Initially, new bone synthesisoccurred peripherally restricted to areas that were closeto the borders of the surgical defect. The biggest centralpart of the surgical defect was occupied by connectivetissue with collagen fibers parallel to the wound surfacewith a mild to moderate chronic inflammatory infiltrate.The complete closure of the defect was not observed atday 7. The repair process is associated with a rich vascularfront, which primarily forms from the marrow andpassages into the defect at right angles to the long axis ofthe bone (Figure 3).Histologically, bone matrix was secreted at day 7and increased significantly at day 14. Osteoblastic cellsappeared at the early stages of 7 days and matured overtime. Osteogenic activity was detected directly at theinterface. A higher degree of formation of vascularizedtissues, of provisional matrix, and of bone remodelingactivity at 7 and 14 days was recorded in the ozone groupas compared to the control group. Meanwhile, a highernumber of normal osteocytes were detected in the ozonegroup.At 7 days: Bone formation did not occur at a uniformFig. 3: Photomicrographs at 7 days (H&E — 200) :(A) Control group showing the parallel arrangement of the collagen fibers in relation tothe surface of the surgical defect, the collagen was restricted to areas that were close to the borders of the surgical defect while the center ofthe defect was still empty. (B) Ozone group showing woven bone attempting to close the defect. Note that the newly formed bone was mainlyrestricted to areas close to the borders of the defect (top) although attempts of bridging were seen at the bottom of the photomicrograph.Postoperative results at 7 and 14 days: All bonedefects in the two groups healed with full regeneration ofbone. The ozone group showed considerable faster healingat the end of the 14 days’ period together with decreasednumber of inflammatory cells. Bone at the periphery,which was originally woven was transformed into lamellarbone adjacent to the persisting cortices. Closer towardsthe center of the defect woven bone predominated. Allthe defects of both groups were mainly filled by newlyformed woven bone with thin and irregular trabeculaesurrounded by fibro-vascular tissue. The woven bone wasrimmed by plump surface osteoblasts. The ozone groupwas bridged by mineralized bone with irregular shape andvolume (Figure 4).Fig. 4: Photomicrographs at 14 days (H&E — 200): (A) Control group showing the longitudinal orientation of repair tissue (B) Ozone groupshowing complete closure of the surgical defect by mineralized bone trabeculae in a fibro-vascular stroma77
CALVARIAL CRITICAL3.3. Statistical Analysiswas used to compare between the two groups as well as tocompare between the two follow-up times.Numerical data were explored for normality bychecking the distribution of data and using tests ofnormality (Kolmogorov-Smirnov and Shapiro-Wilk tests).All data showed normal (parametric) distribution exceptfor number of inflammatory cells data which showed nonnormal (non-parametric) distribution. Data were presentedas mean and standard deviation (SD) values.The significance level was set at P 0.05. Statisticalanalysis was performed with IBM SPSS Statistics Version20 for Windows.3.3.1 Statistical Analysis Outcomes3.3.1.1 Percentage of normal osteocytesAfter 7 as well as 14 days; Ozone gel group showedstatistically significant higher mean percentage of normalosteocytes than control group. In both groups, the meanpercentage of normal osteocytes after 14 days showedstatistically significantly higher mean value than after 7days (Table 1) (Figure 5).For parametric data, two-way analysis of Variance(ANOVA) was used to study the effect of group and timeon different variables. Bonferroni’s post-hoc test wasused for pair-wise comparisons when ANOVA test issignificant. For non-parametric data, Mann-Whitney U testTable 1: The mean, standard deviation (SD) values and results of two-way ANOVA test for comparison between percentage of normalosteocytes in the two groups as well as the change by time within each groupOzone gel7 days14 daysP-value (Within group)Effect 2 0.001* 0.001*0.7840.842*: Significant at P 0.05Fig. 5: Bar chart representing mean normal osteocytes percentage in the two groups78P-value (Betweengroups)Effect size 0.001*0.024*0.5120.211
Elsholkamy et al.3.3.1.2 Area percentage of new bonebone than control group. In both groups, the mean areapercentage of new bone after 14 days showed statisticallysignificant higher mean value than after 7 days (Table 2)(Figure 6).After 7 as well as 14 days; Ozone gel group showedstatistically significant higher mean area percentage of newTable 2: The mean, standard deviation (SD) values and results of two-way ANOVA test for comparison between area percentage of newbone in the two groups as well as the change by time within each groupOzone gel7 days14 7P-value (Within group)Effect size 0.001* 0.001*0.9040.863P-value (Betweengroups)Effect size0.046*0.006*0.1560.295*: Significant at P 0.05Fig. 6: Bar chart representing mean area percentage of new bone in the two groups3.3.1.3 Number of inflammatory cellsinflammatory cells than control group. In both groups, themean number of inflammatory cells after 14 days showedstatistically significant lower mean value than after 7 days(Table 3) (Figure 7).After 7 as well as 14 days; Ozone gel group showedstatistically significant lower mean between number of79
CALVARIAL CRITICALTable 3: The mean, standard deviation (SD) values and results of Mann-Whitney U test for comparison between number of inflammatorycells in the two groups as well as the change by time within each groupOzone gel7 days14 -value (Within group)Effect size 0.001* 0.001*0.9040.863P-value (Betweengroups)Effect size0.046*0.006*0.1560.295*: Significant at P 0.05Fig. 7: Bar chart representing mean number of inflammatory cells in the two groups3.3.1.4 Bone Mineral Density (BMD)two groups. However, in both groups, the mean area BMDafter 14 days showed statistical significant higher meanvalue than after 7 days (Table 4) (Figure 8).After 7 as well as 14 days; there was no statisticallysignificant difference between bone mineral density in theTable 4: The mean, standard deviation (SD) values and results of two-way ANOVA test for comparison between Bone Mineral Density(BMD) in the two groups as well as the change by time within each groupOzone gel7 days14 daysP-value (Within group)Effect 40.06 0.001* 0.001*09170.896*: Significant at P 0.0580P-value (Betweengroups)Effect size0.3590.0690.0330.143
Elsholkamy et al.Fig. 8: Bar chart representing mean Bone Mineral Density (BMD) in the two groupsDISCUSSIONtriggers a series of biological mechanisms that lead tonormalizing the delivery of oxygen for several days withconsequent therapeutic effects[12]. Ozone delivery systemcan provoke several responses on the biological aspectof bone regeneration, such as improvement of the bloodcirculation in ischemic tissue by increasing oxygendelivery and enhancement of the general metabolism viamild activation of the immune system and upregulation ofcellular antioxidant enzymes and growth factors[31].Bone healing and regeneration to normal form andfunction is the ultimate goal after surgical proceduresinvolving intra-bony pathological lesions surgicalmanagement, this goal was for decades an interestingpoint of both experimental and clinical research, utilizingof many materials for achieving this goal with differentdegree of success.Several treatment modalities were recently used,such as low-level laser therapy which was effective forstimulating bone formation in critical size defects in thecalvaria of rats submitted to ovariectomy, the results werein agreement with our results. Hyperbaric oxygen therapywas also used in enhancing bone healing in ungraftedrabbit calvarial critical-sized defects and may likewiseincrease the rate of residual graft resorption in autogenousbone–grafted defects[22-26]. However, the use of low-levellaser therapy requires expensive equipment with hazardsfor both the patient and the operator, also hyperbaricoxygen therapy is time consuming and utilizes chamberwith patient commitment to attend many dives.Unfortunately, few literature has utilized Ozone incalvarial bone defects, the histological findings of thecurrent study revealed an obvious enhancement in newbone formation and a marked reduction in concentrationof inflammatory cells of the ozone gel treated specimens.These results are in accordance with Ozdemir et al. whofound similar results of increase bone healing whenutilized in calvaria of rats in terms of increase osteoblastnumber and new bone formation these observationsshowed superior results for ozone therapy group, both inhistomorphometric assessments (using image analysissoftware), and histological analyses, compairing ozonetherapy to controlled non-grafted group and autogenousgraft without ozone therapy[32].The rabbit model was used for this study becausethe bone repair process of rabbits, although faster, isphysiologically similar to that of humans[27,28]. Furthermore,the use of cranial bone for grafting purposes has somesignificant benefits, such as a higher amount of survivingbone graft and a relatively short postoperative recoveryperiod. Moreover, cranial bone harvesting is a relativelysafe procedure, with a low morbidity compared to iliac crestbone harvesting[29]. Additionally, and most emphasizedfeature, is the embryologic, morphologic, and physiologicsimilarity of this bone to that in the maxillofacial region[30].Ozdemir et al. used sophisticated technology usingOzonix Ozone Generator , a device that produces ozone ata fixed concentration through a connected hand-piece. Theuse of this device is an additional cost and requires skillfuloperator.In our study, Bone densitometry measurements andarea percentage of new bone showed an understandableincrease in mean values within the ozone gel group,however mineral bone density and concentration meanvalue increase was not statistically significant. This maybe considered as an additional confirmatory verdict toBocci stressed that during ozone therapy, ozone81
CALVARIAL CRITICALthe distinct biocompatibility of ozone gel as a potentialadditional benefit for bone grafts as it increases the newbone formation thus help accelerating bone filling andmaturation rates in comparison to control group.6. Cecchi, Simon J B. and Manit A. Bonemorphogenetic protein-7: Review of signallingand efficacy in fracture healing Steven Journal ofOrthopaedic Translation (2016) 4: 28-34DISCUSSION7. Healing of a Large Long-Bone Defect throughSerum-Free In Vitro Priming of HumanPeriosteum-Derived Cells. Stem Cell Reports,Vol. 8, (2017) 758–772: March.The authors believe that according to the available resultsthe use of ozone gel may be cost effective and convenientowing to its ease of preparation. It is recommended to beused with routine bone grafting procedures as it acceleratesthe new bone formation over time giving higher degree ofoverall maturation and strength.8. Joensuua K., Uusitaloa L., Almb J.J., ArobH.T., Hentunena T.A. and Heinoa T.J. Enhancedosteoblastic differentiation and bone formation inco-culture of human bone marrow mesenchymalstromal cells and peripheral blood mononuclearcells with exogenous VEGF., Orthopaedicsand Traumatology: Surgery and Research101 (2015) 381–386.ACKNOWLEDGEMENTThe authors would like to express their deep gratitudeto Prof. Heba Dahmoosh, Oral Pathology Dept., Faculty ofDentistry, Cairo University.9. Elcin B., Selim E. and Volkan A., Vascularendothelial growth factor and biphasic calciumphosphate in the endosseous healing of femoraldefects: An experimental rat study. Journal ofDental Sciences 12, (2017) 7-13.CONFLICT OF INTERESTThere are no conflicts of interest.10. Oh K.C., Cha J.K., Kim C.S., Choi S.H., ChaiJ.K. and Jung U.W. The influence of perforatingthe autogenous block bone and the recipient bedin dogs. Part I: a radiographic analysis. Clin OralImplants Res (2011); 22: 1298–1302.REFERENCES1. Wenhao W., Kelvin W.K. Yeung Bone grafts andbiomaterials substitutes for bone defect repair: Areview. Bioactive Materials 2 (2017) 224-247.11. El-Rashidy A. A., Judith A. R., Leila H., Ulrich K.and Aldo R. B. Regenerating bone with bioactiveglass scaffolds: A review of in vivo studies in bonedefect models. Acta Biomaterialia 62 (2017) 1–28.2. Masahiro Y., Hiroshi E. Current bone substitutesfor implant dentistry. Journal of prosthodonticresearch 62 (2018) 152–161.12. Bocci V.A., Scientific and medical aspects ofozone therapy. State of the art. Arch Med Res2006; 37:425–435.3. Ibrahim E., Alberto T., Wei X., Birgitta N., AnnaJ., Christer D., Peter T. and Omar O. Guidedbone regeneration using resorbable membraneand different bone substitutes: Early histologicaland molecular events., Acta Biomaterialia29 (2016) 409–423.13. Sagai M. and Bocci V. Mechanisms of actioninvolved in ozone therapy: Is healing inducedvia a mild oxidative stress? Med Gas Res2011; 20: 1–29.4. Galo F. G. C., Mayra E. P. M., Juan A. B.B.,Katerine I. N. B., and Denisse V. S. G. Gingivaland bone tissue healing in lower third molarsurgeries. Comparative study between use ofplatelet rich ſibrin versus physiological healing.Revista Odontológica Mexicana, Vol. 21, (2017)No. 2 April-June.14. Polydorou O., Halili A., Wittmer A., Pelz K. andHahn P. The antibacterial effect of gas ozone after2 months of in vitro evaluation. Clin Oral Investig2012; 16: 545–550.15. Huth K.C., Jakob F.M., Saugel B. et al. Effect ofozone on oral cells compared with establishedantimicrobials. Eur J Oral Sci 2006; 114: 435–440.5. Jung-Seok L., Seul K. K., Byung-Joo J., SeongBok C., Eun-Young C. and Chang-Sung K.Enhancing proliferation and optimizing theculture condition for human bone marrow stromalcells using hypoxia and fibroblast growth factor-2,Stem Cell Research (2018) 28 :87–95.16. Polydorou O., Pelz K. and Hahn P. Antibacterialeffect of an ozone device and its comparison withtwo dentin-bonding systems. Eur J Oral Sci 2006;114: 349–353.82
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After bone milling, each bone graft was collected in a special sterile container. After preparing the recipient site, bone graft that was grounded with a manual bone crushed mixed with normal saline, and was implanted in the bone defect of Group I. In Group II same procedure was done and bone graft was mixed by Ozone gel and implanted in
bone autografts were considered for long time one of the best maneuvers to repair and aid in bone healing (2). The fact that this procedure is associated with several drawbacks including morbidity of the donor site and limited graft quantity (3), gave way EFFECTS OF ERYTHROPOIETIN ON THE HEALING OF CALVARIAL BONE DEFECT
bone vs. cortical bone and cancellous bone) in a rabbit segmental defect model. Overall, 15-mm segmental defects in the left and right radiuses were created in 36 New Zealand . bone healing score, bone volume fraction, bone mineral density, and residual bone area at 4, 8, and 12 weeks post-implantation .
healing process. When injected into a critical-size calvarial defect in rabbits, the biocomposites supported ingrowth of new bone. The addition of 80 μg mL 1 recombinant human bone morphogenetic protein-2 (rhBMP-2) enhanced new bone formation in the interior of the defect, as well as bridging of the defect with new bone.
when a bone defect is treated with bone wax, the num-ber of bacteria needed to initiate an infection is reduced by a factor of 10,000 [2-4]. Furthermore, bone wax acts as a physical barrier which inhibits osteoblasts from reaching the bone defect and thus impair bone healing [5,6]. Once applied to the bone surface, bone wax is usually not .
Direct (Primary) Bone Healing Direct bone healing tends to take one of 2 forms: 1. Contact healing 2. Gap healing. Contact healing occurs when the defect between the bone ends is less than 0.01 mm. With contact healing, cutting cones—an osteoclastic tunneling process—develop, resulting in direct formation of lamellar bone oriented in the .
bone matrix (DBX), CMC-based demineralized cortical bone matrix (DB) or CMC-based demineralized cortical bone with cancellous bone (NDDB), and the wound area was evaluated at 4, 8, and 12 weeks post-implantation. DBX showed significantly lower radiopacity, bone volume fraction, and bone mineral density than DB and NDDB before implantation. However,
whether systemic administration of VPA is able to improve bone regeneration in vivo. The objective of this study was to evaluate the effects of systemically administrated VPA on bone healing of maxillary bone defect in rats. In this study, bone cavity healing was assessed and the results will be applied to establishing a novel bone augmentation
Introduction to Magnetic Fields 8.1 Introduction We have seen that a charged object produces an electric field E G at all points in space. In a similar manner, a bar magnet is a source of a magnetic field B G. This can be readily demonstrated by moving a compass near the magnet. The compass needle will line up
