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ORIGINAL ARTICLE
Year : 2021  |  Volume : 24  |  Issue : 8  |  Page : 1126-1132

Dental Implant for Maxillary Cancellous Alveolar Bone with Expandable Transformation in Apical Part


Department of Biomedical Engineering Biomaterials, Corlu Engineering Faculty, Namık Kemal University, Tekirdag, Turkey

Date of Submission20-Aug-2020
Date of Acceptance12-Jan-2021
Date of Web Publication14-Aug-2021

Correspondence Address:
Dr. S Sozkes
Department of Biomedical Engineering Biomaterials, Corlu Engineering Faculty, Namık Kemal University, Silahtarağa Mahallesi Üniversite 1, Sokak No: 13 59860 Çorlu/Tekirdağ
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_518_20

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   Abstract 


Aim: The focus of this study is to propose a new implant design that will resemble the tooth anatomy as with three roots thus increase the primary stability in bone and open new indications to dental implant applications. Methods: Developed implant design and control implants were fabricated from Grade 4 type medical titanium. Three different media are selected as similar structural mechanical properties of alveolar cancellous bone quality; bovine iliac bone, bovine spinal bone, and polymer block. Implant sites were prepared with a 2-mm final drill. Then implants were inserted and all insertion torques were recorded. Starting from 5 Ncm implants were applied removal torques to test the initial stability. The sample that withstands the removal torque is marked with “+” until the torque value where the implant started to move out from the bone socket. Results: Different bone structures and polymer material, designed implant with apical arms have shown relatively average gains of % 38.6 in bovine spinal bone samples, % 38.2 in bovine iliac bone samples and % 46.4 gain in polymer block in retention to removal torques. In the Bovine spinal bone environment, the percentage of gain of the Implant Group developed was significantly higher than the Control Implant Group (p: 0.000; P < 0.05). In the Bovine iliac bone medium, the percentage of gain of the Implant Group developed was significantly higher than the Control Implant Group (p: 0.002; P < 0.05). In the Polymer block environment, the gain percentage of the Implant Group developed was significantly higher than the Control Implant Group (p: 0.008; P < 0.05). Conclusions: The results of this study indicate promising positive future directions to make further researches on the material production and testings of such a new dental implant design including in vivo clinical controlled studies will be beneficial for better understanding the behavior of the developed implant design under different conditions.

Keywords: Biomedical engineering, bone, dental implants, implant design, titanium


How to cite this article:
Sozkes S. Dental Implant for Maxillary Cancellous Alveolar Bone with Expandable Transformation in Apical Part. Niger J Clin Pract 2021;24:1126-32

How to cite this URL:
Sozkes S. Dental Implant for Maxillary Cancellous Alveolar Bone with Expandable Transformation in Apical Part. Niger J Clin Pract [serial online] 2021 [cited 2022 Jul 3];24:1126-32. Available from: https://www.njcponline.com/text.asp?2021/24/8/1126/323862




   Introduction Top


Like so many other discoveries, clinically reliable dental implants were preceded by a serendipitous observation, rather than a logical chain of experiments, leading to the final product. In an attempt to film the microcirculation of rabbit bones, Branemark noticed that the metallic cap at the end of a fiber optic cable embedded in the bone of an experimental animal had apparently become fused to the bone after remaining in situ for some days. This observation led him to postulate that the metal of the end cap, namely Titanium, had properties that could be valuable in the construction of dental implants. In order to test his hypothesis, Branemark and his collaborators began a series of experiments, first in animals and later in humans, which led to the development of the first reliable dental implant.[1],[2],[3],[4]

The animal experiments provided the basis for a long-term clinical trial in humans that culminated. In the eventual report by Adell[5] of 15-year results on the use of dental implants in the edentulous mandible and maxilla to support implant-borne restorations reported high success rate of dental implants. The report, which covered 2768 implants placed from 1965 to 1980 in 410 jaws of 371 consecutive patients, indicated that “implant stability” was achieved in 81% of the maxillary and 89% of the mandibular implants, and restorations retained in 89% of the maxillary and 100% of the mandibular cases. These clinical results constituted a significant improvement over the results that had been achieved up to that time with other systems.[6],[7] The success of dental implants has been published in many longitudinal studies. The high success rate of implants has been well responded by the clinicians and implantology became a treatment modality in modern dentistry.

Esposito and his working group have proposed a classification of failures according to the osseointegration concept.[8] It has been suggested that oral implants should not be subject to micro movements during the healing period to achieve a direct bone to implant apposition. Newly formed supporting bone can lead to differentiated, after 4 weeks of healing, into connective fibrous tissue, when an unstable mechanical situation is induced.[9] It has been stated that overloading of an oral implant can result in loss of the marginal bone or complete loss of implants where osseointegration has been achieved.[5],[10],[11] The most convincing evidence for this theory, has been presented by Sanz in 1991.[12] In six patients who had implants with mobility and peri-implant radiolucency or marginal loss but without pockets exceeding 3 mm and without bleeding. They found healthy peri-implant mucosa without the signs of inflammation in light and electron microscope evaluations. This result was interpreted by authors to mean that overload had caused the peri-implant breakdown.

A load on a bone deforms or strains it. This can result in mechanical fatigue damage (microdamage), but remodeling normally repairs the damage and thus keeps it from accumulating. Overloading the bone can increase the microdamage. When bone is loaded to 1500-2000 (LIE (microstrain)), the bone is deformed 0.15-0.2% the small micro damage that occurs can be repaired, and loads influencing the bone in this interval may even result in an osseous adaptation by the formation of bone (reshaping and strengthening), presumably for reducing the future functional strain within the bone.[13] In comparison, normal bone fractures at forces causing deformation of about 2.5% (25,000) Lie. Apposition of bone around an oral implant, therefore, seems to be the biological response to mechanical stress below a certain threshold, whereas the loss of osseointegration may be the result of mechanical stress beyond this threshold.

Hence, the premier stability of dental implants is critical both for the day of implantation and the design of the implant is an important factor for long-term life of the dental implant with better force distribution.


   Materials and Methods Top


In maxillary posterior regions where bone quality is not good, the shape of the molar tooth would be a very good model to develop. The molar tooth has three roots and a furcation separates roots, such as a tripod has more stability in bone rather than one rooted teeth. That's why we have tried to create a design to mimic the tooth structure.

However, the bone structure is very narrow coronally in most of the implant sites, and to open a big insertion hole will cause complications on the osseointegration. The ideal but also the difficult aspect is to design such a model that will enter the bone site in a conical shape and then change its shape to a three rooted teeth structure as a tripod.

The design is then worked in detail in Rhino Ceros software (Robert McNeel & Associates) to precisely adapt the pieces. Afterwards we have developed the design with a transvertical passing screw to open the apical arms. This gave us the choice of controlling the degree of opening at the apical arms to form the rooted teeth structure and also in case of any complication to remove back the screw to easily remove from the applied bone. The design was developed in the apical portion with three cuts, which will enable the move of the apical portions externally [Figure 1]. This movement will transform the implant inside the bone in a three-rooted tripod-shaped form, which we believe will increase the primary stability of the dental implant [Figure 2] and [Figure 3].
Figure 1: Drawing of developed model apical arms open and apical arms close

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Figure 2: Drawing of developed model apical arms open and apical arms close. (Occlusal view)

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Figure 3: Drawing of developed model apical arms open and close. (Apical view)

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The plastic models were taken from specially developed prototyping machines and pre-manufacturing function tests were successful [Figure 4]. Developed implant design and control implants were fabricated from Grade 4 type titanium and tested for full functionality [Figure 5] and [Figure 6]. It has been suggested that implants should also be evaluated for possible rotational movements for primary stability which was a reverse-torque test, with forces not exceeding 10 Ncm, to every single implant at abutment connection to discover mobile implants.[14] With this procedure, an incidence of 4.7% of early failures was reported. Sullivan also reported an increase of the reverse-torque test to 20 Ncm was shown to reduce the number of late failures.[14]
Figure 4: Model developed in final specification at software is transferred to prototype is tested to function (opening) in apical arms

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Figure 5: Manufactured control implant (left) and developed implant design (right)

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Figure 6: Manufactured implant design, apical arms of the implant are opened

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Four implant application sites were prepared with 2.0 mm drill on each sample (5 Polymer Block samples,5 Bovine Spinal and 5 Bovine Iliac Bone Samples bought from butcher shop). All applicable international and national ethical guidelines for the care and use of animals were followed and no animal subject was included in the study. The drilling speed is fixed with 800 rpm using W&H Implamed device (W&H Co). Each implant site is cleaned from excess bone particles after the drilling is finished. Drilling is done by the same surgeon (more than 20 years of experience in implantology), under the same conditions and on the same day. After holes are prepared in the bone, implants both the control implant and the developed design are inserted in their prepared sockets the simultaneously recording the insertion torque values. Each implant in all samples and three different media was applied with digital torque control in sequences of 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 Ncm. Insertion torque values are recorded by the digital torque meter of the W&H Implamed Device, and the torque values are increased gradually until the implants reach to its final position. Then the implants are applied to removal torques again with gradually applied forces. The removal torque values are gradually increased from 5 to 50 Ncm with 5 Ncm intervals. The same procedure is repeated for 5 Bovine Spinal Bone samples, 5 Bovine Iliac Bone Samples and 5 Polymer Block samples and all data are recorded.


   Results Top


The designed implants were tested in different media to compare the behavior of the proposed implant design compared to the control implant in different types of bones [Table 1] and [Table 2].
Table 1: Results of the digital torque (Ncm) recordings from the developed implant design

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Table 2: Results of the digital torque (Ncm) recordings from the control implant design

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The percentage of gain in primary stability

In the Bovine spinal bone environment, the percentage of gain of the Implant Group developed was statistically significantly higher than the Control Implant Group (p: 0.000; P < 0.05) [Table 3]. In the Bovine iliac bone medium, the percentage of gain of the Implant Group developed was statistically significantly higher than the Control Implant Group (p: 0.002; P < 0.05). In the Polymer block environment, the gain percentage of the Implant Group developed was statistically significantly higher than the Control Implant Group (p: 0.008; P < 0.05). In the Developed Implant Group, there was no statistically significant difference between the bovine spinal bone, bovine iliac bone and polymer block groups gain percentages (p: 0.534; P > 0.05). In the Control Implant Group, there is a statistically significant difference between the gain percentages in the bovine spinal bone, bovine iliac bone and polymer block groups (p: 0.006; P < 0.05). As a result of Post Hoc comparisons made to determine the media from which meaningfulness originated, the gain percentage in the Polymer Block group was significantly lower than the Bovine spinal bone and bovine iliac bone groups (p1: 0.025; p2: 0.005; P < 0.05). There is no statistically significant difference between the gain percentages of the bovine spinal bone and bovine iliac bone groups (p > 0.05).
Table 3: Gain percentage (%) evaluation

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The insertion torque level comparisons

In the Bovine spinal bone environment, the insertion torque level of the Implant Group developed was statistically significantly lower than the Control Implant Group (p: 0.000; P < 0.05) [Table 4]. In the Bovine iliac bone medium, the insertion torque level of the Implant Group developed was statistically significantly lower than the Control Implant Group (p: 0.004; P < 0.05). In the Polymer block environment, there is no statistically significant difference between the insertion torque levels of the Implant and Control Implant groups developed (p > 0.05).
Table 4: Insertion torque evaluation

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In the Developed Implant Group, there are statistically significant differences in the insertion torque levels of the bovine spinal bone, bovine iliac bone and polymer block groups (p: 0.000; P < 0.05). As a result of Post Hoc comparisons made to determine the media from which meaningfulness originated; The insertion torque level of the Bovine spinal bone group was significantly higher than the Bovine iliac bone and Polymer Block groups (p1: 0.000; p2: 0.010; P < 0.05). There is no statistically significant difference between the insertion torque levels of the Bovine iliac bone and Polymer Block groups (p > 0.05). In the Control Implant Group, there are statistically significant differences in the insertion torque levels of bovine spinal bone, bovine iliac bone and polymer block groups (p: 0.000; P < 0.05). As a result of Post Hoc comparisons made to determine the media from which meaningfulness originated, the insertion torque level of Bovine spinal bone group was significantly higher than Bovine iliac bone and Polymer Block groups (p1: 0.000; p2: 0.015; P < 0.05). There is no statistically significant difference between the insertion torque levels of the Bovine iliac bone and Polymer Block groups (p > 0.05).

The removal torque level comparisons

In the Bovine spinal bone environment, the removal torque level of the Implant Group developed was statistically significantly lower than the Control Implant Group (p: 0.003; P < 0.05) [Table 5]. In the Bovine iliac bone medium, there is no statistically significant difference between the removal torque levels of the Implant and Control Implant groups developed (p > 0.05). In the Polymer block environment, the removal torque level of the Implant Group developed was statistically significantly higher than the Control Implant Group (p: 0.013; P < 0.05). In the Developed Implant Group, removal torque levels of bovine spinal bone, bovine iliac bone and polymer block groups are statistically significant (p: 0.000; P < 0.05). As a result of Post Hoc comparisons made to determine the media from which meaningfulness originated, the removal torque level of the Bovine spinal bone group was significantly higher than the Bovine iliac bone and Polymer Block groups (p1: 0.002; p2: 0.001; P < 0.05). There is no statistically significant difference between the removal torque levels of Bovine iliac bone and Polymer Block groups (p > 0.05). In the Control Implant Group, removal torque levels of bovine spinal bone, bovine iliac bone and polymer block groups are statistically significant (p: 0.000; P < 0.05). As a result of Post Hoc comparisons made to determine the media from which meaningfulness originated, the removal torque level of the Bovine spinal bone group was significantly higher than the Bovine iliac bone and Polymer Block groups (p1: 0.004; p2: 0.000; P < 0.05). There is no statistically significant difference between the removal torque levels of the Bovine iliac bone and Polymer Block groups (p > 0.05).
Table 5: Removal torque evaluation

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   Discussion Top


Earlier studies reported different success rates in different regions of the jawbone: 97%, 99%, 89%, and 71% in 673 implants[15] and 94%, 95%, 88%, and 87% in 2359 implants[16], in the anterior mandible, posterior mandible, anterior maxilla and posterior maxilla, respectively.

Seong et al.[16] reported that cAD-composite apparent density was lower in the posterior maxilla than in any other region. For Elastic Modulus (EM) and Hardness (H), the posterior bone was superior to the anterior bone. These findings suggest that the amount of cortical bone and trabecular bone per unit volume available for the implant is more important for implant success, than stiffness of the cortical bone or trabeculae in contact with an implant.

The Seong[16] study found that elastic modulus differed significantly between the maxilla (14.9 GPa) and mandible (18.3 GPa). Also, the posterior jawbone (17.5 GPa) had a significantly higher elastic modulus than the anterior jawbone (15.7 GPa), perhaps because of adaptation to higher chewing force in the posterior part of the jawbone. The elastic modulus of cortical bone (17.7 GPa) and trabecular bone (15.4 GPa) (averaging together maxillas and mandibles) also differed significantly. This result agrees with previous findings that cortical bone elastic modulus is higher than trabecular bone elastic modulus.[17] Wolff's assumption that compact bone is simply more dense than cancellous bone, so cortical and trabecular bones should have approximately the same elastic properties might not be accurate, based on the current and above-mentioned studies.

A few previous studies have measured the apparent density of jawbones. O'mahony[18] reported a mean hydrated apparent density of 0.55 g/cm3 from an edentulous mandibular trabecular bone from a 74-year-old female. Misch[19] presented a mean apparent density with bone marrow in situ of 1.18 g/cm3 from 9 human mandibular trabecular bones. Schwartzdabney and Dechow[20] reported a density of 1.85–2.0 g/cm3 from 10 dentate human mandibular cortical bones. Trabecular bone elastic modulus from compression tests was found to be proportional to the cube of the apparent density and strength proportional to the square of the apparent density. Both Young's modulus and strength were found to be proportional to the square of the apparent density.[21] Age-related bone loss has been associated with a decrease in bone density and mineral content in cortical and trabecular bone. Atkinson and Woodhead[22] measured the bone density of mandibular cortical bone from 43 subjects (aged 44–84 years) and found that cortical bone became less dense and had more porosity with increasing age, while tooth loss did not induce a significant density change but rather a reduction of alveolar bone crest height. Owing to the edentulism and high average age (83.3 years) of the subjects in the current study, it is reasonable to expect the lower level of composite apparent density measurements found.[23]

Wang and Puram[24] defined toughness as a quantitative measure of bone quality in terms of its susceptibility to fracture. A few earlier studies[25] showed that the fracture toughness of cortical bone depends on bone density. Wang[26] studied the relationship of fracture toughness to other physical bone properties in femurs from 18 baboons. They found that fracture toughness of bone decreased as age increased and only micro-hardness changed significantly (increased) while other parameters, such as bone mineral density, elastic modulus, yield strength and porosity did not.

The clinically observed low implant success rates in the posterior maxilla might be due to the posterior maxilla has the lowest composite apparent density and relatively high hardness, which might indicate low fracture toughness. This could lead to relatively easy fractures of bone during surgical drilling and implant insertion, and resultant low implant stability and success.

The suggested implant design aims to increase the primary stability of the material just after application in the prepared bone site. We have given in detail the results of the tests made in all different media with each having five samples. The designed implants were tested in different media to compare the behavior of the proposed implant design in different types of bones. The results of this research are promising, and that's worthwhile to study to develop this design in a more precise production facility and researches to be carried in vivo to be clinically proven the efficacy of the developed model.


   Conclusions Top


This research focused to propose a new implant design, not conical or cylindrical designs as available products, but a new design which will resemble the tooth anatomy as tripod with roots, thus increase the primary stability and open new indications to implant applications. Dental implant for maxillary cancellous alveolar bone with expandable transformation in apical part when tested clinically may serve in the future to diminish the observed low implant success rates in the posterior maxilla. Expanding apical portions of the designed implant may overcome the fact that the posterior maxilla has the lowest composite apparent density and relatively high H, which might indicate low fracture toughness. Relatively easy fractures of bone during surgical drilling and implant insertion, and result in low implant stability and success may be overcome with the proposed design. The suggested implant design aims to increase the primary stability by the apical arms which extend inside the bone when the apical arms are opened with the activating screw. The shape of the conical implant transforms into three-rooted molar teeth. Furthermore, stability tests in means of anti-rotational resistance were applied to the samples of the developed implant design.

The results of this study indicates promising outcomes in different bone structures and polymer material, designed implant with apical arms has shown relatively average gain of % 38.6 in bovine spinal bone samples, % 38.2 in bovine iliac bone samples and % 46.4 gain in polymer block in retention to removal torques; thus encouraging for positive future directions to make further researches on the implant material production. The future perspective we propose is to test this new dental implant design including in vivo clinical controlled studies, which we believe will be beneficial for better understanding the behavior of the developed implant design under different conditions.

Acknowledgments

There are no acknowledgments to declare. The study did not receive funding or financial support to declare.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Branemark PL, Adell R, Breine U, Hansson BO, Lindström J, Ohlsson A. Intra-osseous anchorage of dental prostheses. I. Experimental studies. Scand J Plast Reconstr Surg 1969;3:81-100.  Back to cited text no. 1
    
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Brånemark PI, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10 year period. Scand J Plast Reconstr Surg Suppl 1977;16:1-132.  Back to cited text no. 2
    
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Branemark PL, Adell R, Albrektsson T, Lekholm U, Lindström J, Rockler B. An experimental and clinical study of osseointegrated implants penetrating the nasal cavity and maxillary sinuses. Int J Oral Maxillofac Surg 1984;42:497-505.  Back to cited text no. 3
    
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Adell R, Lekholm U, Rockler B, Brånemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10:387-416.  Back to cited text no. 5
    
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Sanz M, Alandez J, Lazaro P, Quirynen M, Steenberghe D. Histo-pathologic characteristics of peri-implant soft tissues in Branemark implants with 2 distinct clinical and radiological patterns. Clin Oral Implant Res 1991;2:128-34.  Back to cited text no. 12
    
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Frost HM. Wolff's law and bone's structural adaptations to mechanical usage: An overview for clinicians. Angle Orthod 1994;64:175-88.  Back to cited text no. 13
    
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Sullivan DY, Sherwood RL, Collins TA, Krogh PH. The reverse-torque test: A clinical report. Int J Oral Maxillofac Implants 1996;11:179-85.  Back to cited text no. 14
    
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Drago CJ. Rates of osseointegration of dental implants with regard to anatomical location. J Prosthodont 1992;1:29–31.  Back to cited text no. 15
    
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Buser D, Mericske-Stern R, Bernard JP, Behneke A, Behneke N, Hirt HP, et al, Longterm evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multicenter study with 2359 implants. Clin Oral Impl Res 1997;8:161-72.  Back to cited text no. 16
    
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O'Mahony A, Williams J, Katz J, Spencer P. Anisotropic elastic properties of cancellous bone from a human edentulous mandible. Clin Oral Impl Res 2000;11:415–21.  Back to cited text no. 18
    
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Misch C, Zhimin Q, Bidez M. Mechanical properties of trabecular bone in the human mandible: Implications for dental implant treatment planning and surgical placement. J Oral Maxillofac Surg 1999;57:700–6.  Back to cited text no. 19
    
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Schwartz-Dabney CL, Dechow PC. Variations in cortical material properties throughout the human dentate mandible. Am J Phys Anthropol 2003;120:252–77.  Back to cited text no. 20
    
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Rice JC, Cowin SC, Bowman JA. On the dependence of the elasticity and strength of cancellous bone on apparent density. J Biomech 1988;21:155–68.  Back to cited text no. 21
    
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Atkinson PJ, Woodhead C. Changes in human mandibular structure with age. Arch Oral Biol 1968;13:1453–63.  Back to cited text no. 22
    
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Schnitzler CM, Mesquita J. Bone marrow composition and bone microarchitecture and turnover in blacks and whites. J Bone Miner Res 1998;13:1300–7.  Back to cited text no. 23
    
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Wang D, Puram S. The toughness of cortical bone and its relationship with age. Ann Biomed Eng 2004;32:123–35.  Back to cited text no. 24
    
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Wright TM, Hayes WC. Fracture mechanics parameters for compact bone – Effects of density and specimen thickness. J Biomech 1977;7:419–30.  Back to cited text no. 25
    
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Wang XD, Masilamani NS, Mabrey JD, Alder ME, Agrawal CM. Changes in the fracture toughness of bone may not be reflected in its mineral density, porosity, and tensile properties. Bone 1998;23:67–72.  Back to cited text no. 26
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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