Ortho Impl Aaooo

8/9/2019 Ortho Impl Aaooo

1/8


2/8

biomechanical research. Despite irregular geometry anduncertain loading conditions, nite element modelingcan achieve a 3-dimensional representation of the

internal or external structure; this is preferred over rep-resentations derived from exterior single-point measure-

ments. Factorial analysis allows a sensitivity examinationto consider all possible contributing factors and todetermine which factorshave the most inuence in the

biomechanical system.16 Once identied, the more inu-

ential factors can be further investigated, as can theinteractions between them. The purpose of this study

was to integrate a

nite element approach and factorialanalysis, to investigate the variables affecting bonestresses adjacent to alveolar bone.

MATERIAL AND METHODS

We used a commercial stainless steel mini-implant

(A-1 C type implant system; Bio-Ray Biotech, New TaipeiCity, Taiwan) with a 2-mm diameter. For the purpose ofthe study, 3 lengths (8, 10, and 12 mm) were selected formodel reconstruction. The geometry of the mandible,

including both the second premolar and the rst molar,was obtained from the Department of Dentistry of E-Da

Hospital (Kaohsiung County, Taiwan), and computed to-mography images captured at 3-mm intervals were dig-itized into digital imaging and communications inmedicine (DICOM) format. Three-dimensional solidmodels of the mini-implant and the mandible were re-

constructed and assembled by using commercialcomputer-aided design software (SolidWorks 2008;SolidWorks Corp, Waltham, Mass). The periodontal liga-ment was imitated at 0.25 mm in thickness and modeled

based on the exterior geometry of both roots. The inser-tion of the mini-implant was assumed to be the middle

point of both the premolar root in depth and the gap be-tween the premolar and molar. Because the objective ofthis study was focused on bone stress, the crowns of

both teeth were not incorporated to conserve calculation

time. The entire model was imported to the nite ele-ment package (version 11.0; ANSYS, Canonsburg, Pa)and meshed by using 3-dimensional 10-node tetrahe-dral structural elements (Fig 1). The bone, teeth, peri-odontal ligament, and mini-implant were all dened ashomogeneous, isotropic, and linear elastic materials.

The mechanical properties of the materials werebasedon published data and are listed in Table I.15,17,18

Before analysis, various element sizes were examined,ranging from 0.7 to 1.2 mm, to ensure convergence ofthe nite element model. Subsequently, 0.8 mm wasdetermined as the appropriate element mesh size forall mesh models. The interfaces between teeth,periodontal ligament, bone, and mini-implant were all

assumed to be bonded. Proximal and distal bone sur-faces were xed in all directions as the boundary condi-tions. The orthodontic force was 2 N (approximately 200g), derived from previous reports and applied at the top

surface of themini-implant and inclined in the proximaldirection.19-22 We aimed to simulate the en-masse

Fig 1. Finite element model in this study.

Table I. Mechanical properties of the materials used inthe nite element model

Material

Youngsmodulus

(MPa)Poissons

ratio Reference

Mini-implant 230000 0.3 29

Cortical bone 14000 0.3 11

Cancellous bone 300 0.3 11

Dentin 18600 0.31 10

Periodontal membrane 50 0.45 12

Fig 2. Orthodontic force angle investigated in this study.

Lin et al 183

American Journal of Orthodontics and Dentofacial Orthopedics February 2013 Vol 143 Issue 2


3/8

retraction of anterior teeth. To this effect, we useda mini-implant with a 2.0-mm diameter. In addition, 2

N force is the maximum magnitude in the generally ac-cepted range, according to the reported clinically safe

limit for immediate loading.8

Statistical analysis

The factors affecting bone stress that were investi-gated included orthodontic force angle, insertion direc-tion, and the exposure length of the mini-implant. In

total, 27 mini-implant nite element models (3 ortho-dontic force angles with 3 insertion directions and 3 ex-posure lengths of the mini-implants) were analyzed (Figs2 and 3). The orthodontic force angle was dened as that

between the line of applied force and the axis, which wasparallel to the long axis of the tooth in the sagittal plane

on the head of mini-implant. The insertion direction wasdetermined based on the long axis of the mini-implantrelative to the bone surface. Maximum von Misesstresses in cortical and cancellous bones were observed

because of the viscoelastic characteristic of the bone.The main effect described the variation of the mean

response of all factors based on the altered level for

a specied factor. Correspondingly, the main effect plotsand the contribution of each factor were generated byusing a commercial statistical package (version 15.0;

Minitab, State College, Pa). To determine the relative im-portance of these factors, a general linear model analysisof variance (ANOVA) test was performed,withP\0.05

deemed to indicate statistical signicance.16

RESULTS

The maximum von Mises stress values of cortical andcancellous bones are listed in Table II. The ANOVA re-sults of affecting factors and their interactions, gener-ated to determine the relative importance of corticaland cancellous bones, are listed in Tables III and IV.The main-effect plots (Figs 4 and5) illustrate the varia-

tions in the maximum von Mises stresses at each level foreach factor between cortical and cancellous bones.

With regard to the cortical bone, the exposure lengthof the mini-implant (82.35%), the interactions between

the insertion angle and exposure length (9.34%), and theinsertion angle of the mini-implant (6.03%) all had

Fig 3. Factors investigated in this study: A, the insertion angle; and B, the exposure length of the mini-

implant.

184 Lin et al

February 2013 Vol 143 Issue 2 American Journal of Orthodontics and Dentofacial Orthopedics


4/8

signicant impacts (P\0.05) on cortical bone stresses.

Based on the main-effect plots derived from the corticalbone, the stressuctuations observed as the force anglevaried were minimal; although the insertion angle wasaltered from 90 to 120, the cortical stress only de-creased by approximately 12%. The stress did not differmeasurably between 60 and 90. Maximum cortical

bone stresses were observed when the exposure length

of the mini-implant was 7 mm. As the exposure lengthdecreased, cortical bone stresses diminished markedly.

All factors investigated and the interactions betweenthem affected cancellous bone stresses signicantly, ex-cept the interaction between the orthodontic force angle

and the exposure length of the mini-implant. The contri-butions of the dominant factors were the insertion angleof the mini-implant (46.93%), the interaction betweenthe insertion angle and the exposure length of themini-implant (36.41%), and the exposure length ofthe mini-implant (12.44%). The main-effect plots of

the cancellous bone suggested that stresses increased

gradually in conjunction with increases in the forceangle. Maximum cancellous bone stresses were evident

when the insertion angle of the mini-implant was 60.The observed stresses reduced signicantly as the inser-

tion angle increased. Whereas the stresses were minimalwhen the exposure length was 5 mm, the variations be-

tween each level were not as obvious as those associatedwith the insertion angle.

Most stresses were concentrated around the region ofinsertion of the mini-implant. The magnitude of stress

increased as the exposure length of the mini-implantincreased. Stress variations were not obvious among

the other factors. The stresses in cancellous bone wereobserved to be mostly distributed around the mini-implant and were extremely small compared with thoseevident in cortical bone.

DISCUSSION

The objective of this study was to investigate the fac-

tors affecting bone stresses adjacent to mini-implants.The principal stress-strain and displacement of the alve-olar bone are directional quantities and thereby used topredict the nal morphologic changes of orthodontictreatment. Although the importance of these indexes is

Table II. Simulation results of maximum von Misesstresses of cortical and cancellous bones

Model

Orthodonticforce

direction

Insertion

angle

Exposurelength

(mm)

Corticalbone

(MPa)

Cancellous

bone (MPa)

1 30 60 3 1.72 0.25

2 5 2.39 0.18

3 7 2.74 0.24

4 90 3 1.74 0.21

5 5 2.18 0.15

6 7 3.32 0.19

7 120 3 1.53 0.08

8 5 2.21 0.15

9 7 2.67 0.21

10 45 60 3 1.81 0.29

11 5 2.68 0.20

12 7 2.87 0.25

13 90 3 1.80 0.24

14 5 2.11 0.1615 7 3.51 0.20

16 120 3 1.52 0.08

17 5 2.05 0.15

18 7 2.71 0.21

19 60 60 3 1.82 0.31

20 5 2.78 0.22

21 7 3.03 0.26

22 90 3 1.76 0.25

23 5 1.92 0.16

24 7 3.39 0.20

25 120 3 1.45 0.08

26 5 2.04 0.15

27 7 2.81 0.21

Table III. Summary of the ANOVA results of the max-imum von Mises stresses of cortical bone

Source df SS MSS %TSS P

Force angle 2 0.02 0.01 0.22 0.314

Insertion angle 2 0.58 0.29 6.03 0.000*

Exposure length 2 7.91 3.95 82.35 0.000*

Force angle 3 insertion angle 4 0.11 0.03 1.12 0.065

Force angle 3 exposure length 4 0.03 0.01 0.30 0.501

Insertion angle 3 exposure

length

4 0.90 0.22 9.34 0.000*

Error 8 0.06 0.01 0.65

Total 26 9.60

SS, Sum of squares; MSS, meansum of squares; %TSS, total sum of

squares.

*P\0.05.

Table IV. Summary of the ANOVA results of the max-imum von Mises stresses of cancellous bone

Source df SS MSS %TSS P

Force angle 2 0.0019 0.0009 2.04 0.000*

Insertion angle 2 0.0430 0.0215 46.93 0.000*

Exposure length 2 0.0114 0.0057 12.44 0.000*

Force angle 3 insertion angle 4 0.0012 0.0003 1.36 0.005*

Force angle 3 exposure length 4 0.0005 0.0001 0.51 0.074

Insertion angle 3 exposure

length

4 0.0334 0.0083 36.41 0.000*

Error 8 0.0003 0.0000 0.32

Total 26 0.0917

SS, Sum of squares; MSS, mean sum of squares; %TSS, total sum of

squares.

*P\0.05.

Lin et al 185

http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-


5/8

well recognized, in this study, we aimed to quantify the

relative contributions of affecting factors once themini-implant was inserted and subjected to orthodonticforces. Our quantitative results showed that bone

stresses were higher in cortical than in cancellous bone.It was obvious that the orthodontic stress was mainlyborne by the cortical bone. This observation agrees

with the research of Miyamoto et al.23Furthermore, Mo-toyoshi et al12 suggested that the thickness of cortical

bone should be 1 mm or more to ensure the stability ofmini-implants. Therefore, the primary stability of mini-

implants is positively correlated with the quality andthickness of the cortical bone at the insertion site.

The mechanical properties of biologic tissue, includ-ing bone and periodontal ligament, are well-known to

be viscoelastic and highly dependent on strain rate.Orthodontic treatment is a progressive process that

uses low-magnitude orthodontic force, because the de-formation and displacement of a dental tissue requiresa period of time for modulation. Based on this conditionand assuming that alveolar bone is a ductile material, theassociated von Mises stress has proved to be widely ac-ceptable in orthodontic research. Moreover, selecting

this stress index was advantageous because it is a scaledesigned to quantify stress, without orientation. Thisstress index makes it easier for clinicians to predict wherestress concentrations can occur; this is important, since

high stress potentially leads to failure.The results of our study indicated that the von Mises

stress in cortical bone was affected primarily by theexposure length of the mini-implant (82.35%). Previousresearch focused mainly on the insertion length of mini-implants. In 2011, Chatzigianni et al24 reported that thedisplacement of longer mini-implants under 2.5 N offorce was greater than that exhibited by shorter implants.

Several studies have shown that longer mini-implantsyield higher success rates than shorter implants.25,26

Occasionally, the head of the mini-implant can becomecovered by alveolar mucosa. In such cases, intervention

with orthodontic devices such as an elastic chain ora coil spring could lead to inammation of the alveolar

tissue, which is highly correlated with mini-implantfailure. Partial insertion of longer mini-implants would

A

B

C

7 mm3 mm 5 mm

1.8

2.1

2.4

2.7

3.0

3.3

1.5

(MPa)

3.6

1209060

1.8

2.1

2.4

2.7

3.0

3.3

3.6

1.5

(MPa)

30 45 60

1.8

2.1

2.4

2.7

3.0

3.3

3.6

1.5

(MPa)

Fig 4. Main-effect plots for each level of: A, force angle;B, insertion angle; and C, exposure length of the mini-

implant on the cortical bone stresses. The horizontal

and vertical axes, respectively, showed variations of

each investigated factor and the mean von Mises

stresses (MPa).

:

186 Lin et al



6/8

minimize the possibility of the alveolar mucosa covering

the head ofthe mini-implant, thus reducing the chanceof its failure.27

The results of this study suggest that cortical bone

stress increases in association with increases in exposurelength, because the bending moment increases with theelongation of the moment arm. Excessive bone stress in-

duced by longer exposure lengths might facilitate localbone resorption. The closer the screw head is to the at-tached mucosa, the less destructive will be the appliedload. When the screw head is farther from the attached

mucosa, the orthodontic load should be reduced accord-ingly. Furthermore, food debris and plaque can accumu-

late around the exposed thread; this in turn could lead toinammation of the attached mucosa and subsequentinammation of the cortical bone surrounding themini-implant. Thus, the exposure length, which has

not been emphasized in previous research, might be asimportant as insertion length in clinical practice.

The pullout test is the most popular in-vitro protocolto evaluate the stability and strength of the screws usedin orthopedics and dentistry.28,29 In contrast to theapplied force that is parallel to the longitudinal axis ofthe mini-implant in the pullout test, the orthodontic

force is mostly applied perpendicularly to the mini-implant itself. The bone stresselds are completely dif-ferent under these 2 loading conditions. Some studieshave investigated the relevance of both the insertion an-gle of the mini-implant and the direction of orthodontic

force to the stability of the implant.7,30 The results of thefactorial analysis showed that the angle of orthodonticforce has no signicant effect on cortical bone stress(P 5 0.314). Whereas all factors investigated hada statistically signicant inuence on cancellous bone

stress, the stress value of cancellous bone was muchless than that of cortical bone.

Extensive nite element analysis has been applied toinvestigate the mechanical response of biologic struc-tures, especially in orthopedics31,32 and dentistry.33,34

Although this method is considered to be a powerfultool for biomechanical research, the numeric results

produced by this method still require appropriateinterpretation. Factorial analysis is a statistical method

A

B

C

3 mm 5 mm 7 mm

0.16

0.18

0.20

0.22

0.24

0.26

0.14

(MPa)

45 30 60

0.16

0.18

0.20

0.22

0.24

0.26

0.14

(MPa)

60 90 120

0.16

0.18

0.20

0.22

0.24

0.26

0.14

(MPa)

Fig 5. Main-effect plots for each level of: A, force angle;B, insertion angle; and C, exposure length of the mini-

implant on the cancellous bone stresses. The horizontal

and vertical axes, respectively, showed variations of

each investigated factor and the mean von Mises

stresses (MPa).

:

Lin et al 187



7/8

used to describe the variability among factors and the

interactions between them. Therefore, the distortioncaused by the differences between numeric models andthe actual environment could be diminished by

integration of the

nite element model and factorialanalysis, and the results might be more authentic.Although the assumptions incorporated into nite

element modeling are based on clinical conditions, it iswell recognized that they are not identical. It isimpossible to measure stresses accurately around themini-implant in vivo. Hence, this study incorporated

biomechanical factors, which might not be exactly com-parable with the real situation. With insufcient

attached gingiva, as the mandible has, the site of mini-implants in the mandible varies. In the treatment of ClassIII patients, for example, mini-implants often need to beinserted at the external oblique ridge or the retromolar

pad for en-masse retraction. To overcome the encapsu-lation of mobile gingiva, the exposed length of mandib-ular mini-implants must be longer than that of implantsin the maxilla. Longer exposure length also occurs whenthere is bone destruction around the mini-implant. The

von Mises stress distributions show the mechanicalchange as well as the causes of failure under compro-mised bone conditions. In addition, further investiga-tions could provide imperative information leading to

innovations or techniques for use in clinical practice.There were limitations to this study. For numeric

convergence, the mechanical behavior of the materials

was assumed to be linear elastic (homogeneous and iso-tropic), and the value of each material was inferred fromprevious reports. The interface of bone and mini-implant

was set to fully bonded,to investigate the interactionbetween all other potentially contributing factors.Although the magnitude of orthodontic force was posi-tively correlated with bone stress, in this analysis, it didnot exceed the maximum suggested clinical value. Cor-tical bone thickness and cancellous bone quality were

not incorporated into the analysis to prevent bone stressfrom being dominated by bone quality and potentiallyconfounding the outcomes related to other relevant fac-

tors. In addition, the stress induced by insertion torquewas excluded from this investigation. Regardless of theselimitations, we integrated a nite element approach withfactorial analysis to investigate the comparative inu-ences of the exposure length of mini-implants, their in-sertion angles, and the direction of orthodontic forceexerted on bone adjacent to the implantation site.

CONCLUSIONS

In this study, the nite element approach integratedwith factorial analysis was adopted for elucidating

factors related to orthodontic mini-implants. The expo-

sure length of the mini-implants signicantly inuencedbone stress; increased exposure lengths resulted ingreater bone stresses adjacent to the mini-implant.

The relative in

uence of the insertion angle of themini-implant (6.03%) was also statistically signicantbut was much less than that of exposure length

(82.35%). The direction of orthodontic force had no sig-nicant effect on cortical bone stress. Decreasing the ex-posure length is recommended to improve the stabilityof mini-implants in clinical practice.

REFERENCES

1. Shapiro P, Kokich V. Uses of implants in orthodontics. Dent Clin

North Am 1988;32:539-50.

2. Cope JB. Temporary anchorage devices in orthodontics: a para-

digm shift. Semin Orthod 2005;11:3-9.

3. Reynders R, Ronchi L, Bipat S. Mini-implants in orthodontics:a systematic review of the literature. Am J Orthod Dentofacial

Orthop 2009;135:564.e1-19.

4. Buchter A, Wiechmann D, Koerdt S, Wiesmann H, Piffko J,

Meyer U. Load-related implant reaction of mini-implants used

for orthodontic anchorage. Clin Oral Implants Res 2005;16:473-9.

5. Cheng SJ, Tseng IY, Lee JJ, Kok SH. A prospective study of the risk

factors associated with failure of mini-implants used fororthodon-

tic anchorage. Int J Oral Maxillofac Implants 2004;19:100-6.

6. Fritz U, Ehmer A, Diedrich P. Clinical suitability of titanium micro-

screws for orthodontic anchoragepreliminary experiences. J Oro-

fac Orthop 2004;65:410-8.

7. Wiechmann D, Meyer U, Buchter A. Success rate of mini- and

micro-implants used for orthodontic anchorage: a prospective

clinical study. Clin Oral Implants Res 2007;18:263-7.

8. Crismani AG, Bertl MH, Celar AG, Bantleon HP, Burstone CJ. Min-iscrews in orthodontic treatment: review and analysis of published

clinical trials. Am J Orthod Dentofacial Orthop 2010;137:108-13.

9. Antoszewska J, Papadopoulos MA, Park HS, Ludwig B. Five-year

experience with orthodontic miniscrew implants: a retrospective

investigation of factors inuencing success rates. Am J Orthod

Dentofacial Orthop 2009;136:158.e1-10.

10. Leung M, Lee T, Rabie A, Wong R. Use of miniscrews and mini-

plates in orthodontics. J Oral Maxillofac Surg 2008;66:1461-6.

11. Park HS,Jeong SH,Kwon OW.Factors affectingthe clinical success

of screw implants used as orthodontic anchorage. Am J Orthod

Dentofacial Orthop 2006;130:18-25.

12. Motoyoshi M, Yoshida T, Ono A, Shimizu N. Effect of cortical bone

thickness and implant placement torque on stability of orthodon-

tic mini-implants. Int J Oral Maxillofac Implants 2007;22:779-84.

13. Miyawaki S, Koyama I, Inoue M, Mishima K, Sugahara T, Takano-

Yamamoto T. Factors associated with the stability of titanium

screws placed in the posterior region for orthodontic anchorage.

Am J Orthod Dentofacial Orthop 2003;124:373-8.

14. Jiang L, Kong L, Li T, Gu Z, Hou R, Duan Y. Optimal selections of

orthodontic mini-implant diameter and length by biomechanical

consideration: a three-dimensional nite element analysis. Adv

Eng Software 2009;40:1124-30.

15. Motoyoshi M, Ueno S, Okazaki K, Shimizu N. Bone stress for

a mini-implant close to the roots of adjacent teeth3D nite ele-

ment analysis. Int J Oral Maxillofac Surg 2009;38:363-8.

16. Dar FH, Meakin JR, Aspden RM. Statistical methods in nite ele-

ment analysis. J Biomech 2002;35:1155-61.

188 Lin et al



8/8

17. Lin C, Chang Y, Chang C, Pai C, Huang S. Finite element and Wei-

bull analyses to estimate failure risks in the ceramic endocrown

and classical crown for endodontically treated maxillary premolar.

Eur J Oral Sci 2010;118:87-93.

18. Rees JS,Jacobsen PH.Elastic modulusof theperiodontal ligament.

Biomaterials 1997;18:995-9.19. Ammar HH, Ngan P, Crout RJ, Mucino VH, Mukdadi OM. Three-

dimensional modeling and nite element analysis in treatment

planning for orthodontic tooth movement. Am J Orthod Dentofa-

cial Orthop 2011;139:e59-71.

20. Jang HJ, Kwon SY, Kim SH, Park YG, Kim SJ. Effects of washer on

the stress distribution of mini-implant. Angle Orthod 2011;82:

137-44.

21. Liu TC, Chang CH, Wong TY, Liu JK. Finite element analysis of

miniscrew implants used for orthodontic anchorage. Am J Orthod

Dentofacial Orthop 2012;141:468-76.

22. Singh S, Mogra S, Shetty VS, Shetty S, Philip P. Three-dimensional

nite element analysis of strength, stability, and stress distribution

in orthodontic anchorage: a conical, self-drilling miniscrew

implant system. Am J Orthod Dentofacial Orthop 2012;141:

327-36.23. Miyamoto I, Tsuboi Y, Wada E, Suwa H, Iizuka T. Inuence of cor-

tical bone thickness and implant length on implant stability at the

time of surgeryclinical, prospective, biomechanical, and imaging

study. Bone 2005;37:776-80.

24. Chatzigianni A, Keilig L, Reimann S, Eliades T, Bourauel C. Effect

of mini-implant length and diameter on primary stability under

loading with two force levels. Eur J Orthod 2011;33:381-7.

25. Freire JN, Silva NR, Gil JN, Magini RS, Coelho PG. Histomorpho-

logic and histomophometric evaluation of immediately and early

loaded mini-implants for orthodontic anchorage. Am J Orthod

Dentofacial Orthop 2007;131:704.e1-9.

26. Tseng YC, Hsieh CH, Chen CH, Shen YS, Huang IY, Chen CM. The

application of mini-implants for orthodontic anchorage. Int J Oral

Maxillofac Surg 2006;35:704-7.

27. Kravitz ND, Kusnoto B. Risks and complications of orthodontic

miniscrews. Am J Orthod Dentofacial Orthop 2007;131(Supp):

S43-51.28. Salmoria KK, Tanaka OM, Guariza-Filho O, Camargo ES, de

Souza LT, Maruo H. Insertional torque and axial pull-out strength

of mini-implants in mandibles of dogs. Am J Orthod Dentofacial

Orthop 2008;133:790.e15-22.

29. Wu JH, Wang HC, Chen CM, Lu PC, Lai ST, Lee KT, et al. Pullout

strengths of orthodontic palatal mini-implants tested in vitro. J

Dent Sci 2011;6:200-4.

30. Suzuki A, Masuda T, Takahashi I, Deguchi T, Suzuki O, Takano-

Yamamoto T. Changes in stress distribution of orthodontic minis-

crews and surrounding bone evaluated by 3-dimensional nite

element analysis. Am J Orthod Dentofacial Orthop 2011;140:

e273-80.

31. Hussain M, Natarajan RN, Fayyazi AH, Braaksma BR,

Andersson GBJ, An HS. Screw angulation affects bone-screw

stresses and bone graft load sharing in anterior cervical corpec-tomy fusion with a rigid screw-plate construct: a nite element

model study. Spine J 2009;9:1016-23.

32. Strange DG,Fisher ST,Boughton PC,Kishen TJ, Diwan AD.Restora-

tion of compressiveloading properties of lumbar discs with a nucleus

implanta nite element analysis study. Spine J 2010;10:602-9.

33. Lin CL, Yu JH, Liu HL, Lin CH, Lin YS. Evaluation of contributions

of orthodontic mini-screw design factors based on FE analysis and

the Taguchi method. J Biomech 2010;43:2174-81.

34. Lin TS, Huang TT, Wu JH. The effects of designs and materials of

the posts on endodontically treated premolar using nite element

analysis. J Med Biol Eng 2010;30:79-83.

Lin et al 189

A i J l f O th d ti d D t f i l O th di F b 2013 V l 143 I 2

Documents

Ortho Impl Aaooo