ONLINE ONLY

Accuracy of surgical positioning of orthodonticminiscrews with a computer-aided design andmanufacturing template

Hong Liu,a Dong-xu Liu,b Guangchun Wang,c Chun-ling Wang,d and Zhen Zhaoa

Jinan, China

Introduction: Our objective was to enable accurate miniscrew placement after preoperative simulation. Wedeveloped a new template for miniscrew placement and evaluated its accuracy. Methods: Eleven patientswho had bimaxillary protrusion were scanned with computed tomography. The 3-dimensional computed to-mography data were used to produce, with stereolithography apparatus, a template for accurate miniscrewplacement. The interradicular space available for miniscrew placement was calculated in the 3-dimensionalimages. Postoperative computed tomography images were matched with preoperative images to calculatethe deviations between the planned and actual placements. Results: The distance for placement of a mini-screw between 2 roots was 4.12 mm (SD, 0.25 mm; range, 3.7-4.5 mm). The placed miniscrews showed anaverage angular deviation of 1.2� (SD, 0.43�; range, 0.6�-2.41�) compared with the plan, whereas the meanlinear distomesial deviation was 0.42 mm (SD, 0.13 mm; range, 0.15-0.6 mm) at the tip. Conclusions: The pro-posed template has high accuracy and will be especially useful for patients who require precise miniscrewplacement. (Am J Orthod Dentofacial Orthop 2010;137:728.e1-728.e10)

Miniscrews have been used for absolute an-chorage in orthodontics for a long time.1,2

Miniscrews are always placed in alveolarbone between the first molar and the second premolar,and the placement angle is always 30� (the long axisof the miniscrew and the tooth axis) in the maxillaand 20� in the mandible.3 However, the high failurerates of miniscrews troubles orthodontists. Accordingto previous articles, the rates of failure are about 11%to 30.4%.1,2,4 Placing a miniscrew in the limited spacebetween the roots of the second premolar and the firstmolar causes some risk of injury to importantanatomic structures.4 Safe and optimal miniscrew stabi-lization requires ideal placement point and trajectory.Improper screw placement can lead to neurovascular

From Shandong University, Jinan, China.aPostgraduate student, Department of Orthodontics, School of Dentistry,

Shandong Provincial Key Laboratory of Oral Biomedicine.bProfessor, Department of Orthodontics, School of Dentistry, Shandong

Provincial Key Laboratory of Oral Biomedicine.cProfessor, Research Center of Mould.dProfessor and chairman, Department of Orthodontics, School of Dentistry.

The authors report no commercial, proprietary, or financial interest in the

products or companies described in this article.

Supported by grants from Shandong Science and Technology Planning Project

Contract Research (2008GG30002019 and 2008GG30001001) of China.

Reprint requests to: Dong-xu Liu, Department of Orthodontics, School of

Dentistry, Shandong University, Jinan, 250012, China; e-mail, liudongxu@sdu.

edu.cn.

Submitted, October 2009; revised and accepted, December 2009.

0889-5406/$36.00

Copyright � 2010 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2009.12.025

damage or suboptimal biomechanical stabilization.5-7

To achieve precise and safe placement of miniscrewsin interradicular sites, several methods have beendeveloped, but they cannot guarantee preciseplacement.8-14 A controllable method for miniscrewplacement and direction is important for orthodontists.

Computed tomography (CT), 3-dimensional (3D)software, and stereolithography apparatus (SLA)(Xi’an Jiaotong University, Xi’an, China) have beenwidely used in oral medicine.9,15-23 CT has been usedfor measurement of interradicular space forminiscrews and assessment of their position. The 3Dsoftware helps to render objects from the CT imagesfor diagnosis and treatment planning. Computer-aideddesign and computer-aided manufacturing (CAD/CAM) technology has been used in dental restorationsand implantology.24-26,33 The CAD/CAM template forimplants has been accepted and used widely, andgives us another method to aid in achievingcontrollable miniscrew placement. In this article, theCAD/CAM template for orthodontic miniscrews isintroduced, and its accuracy is assessed.

MATERIAL AND METHODS

Materialise’s interactive medical image control sys-tem (MIMICS) and Magics (both, Materialise, Leuven,Belgium) are both widely used medical software pro-grams. The miniscrew template described in this articlewas designed with these tools.

728.e1

Fig 1. A, Miniscrew (diameter, 1.6 mm; length, 11 mm; pitch, 0.2 mm); B, self-drilling driver.

Fig 2. A, Template with buccal and lingual vestibular border extensions was fabricated on the stonecast with the vacuum-formed technique; B, radiopaque markers were placed on the template; C andD, template was adjusted in the mouth to ensure proper seating.

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MIMICS is an interactive tool for the visualizationand segmentation of CTand magnetic resonance imagesand the 3D rendering of objects. Therefore, in medicine,MIMICS can be used for diagnosis, operation planning,and rehearsal purposes. A flexible interface to rapid pro-totyping systems is included for building distinctivesegmentation objects. Magics is companion softwareto MIMICS; the user can further process the 3D model(stereolithography [STL] file) that is created inMIMICS.

Stereolithography apparatus (SLA) is the process ofusing photosensitive resins cured by a laser that tracesthe parts across sectional geometry layer by layer.SLA produces accurate models with various materials.We used a resin (SOMOS 11120 photosensitive resin,DSM, Elgin, IL).

Eleven patients with bimaxillary protrusion agreedto have their 4 first premolars extracted; 34 miniscrews

(Beici Medical Company, Ningbo, China; Fig 1) wereplanned to provide absolute anchorage. The miniscrewswere placed in the interradicular area between the sec-ond premolar and the first molar. Six patients received4 miniscrews, and 5 patients had miniscrews placed inthe maxilla only.

The CAD/CAM template for the miniscrews in thisstudy was designed based on the CT data and fabricatedby the SLA. After preparing mounted diagnostic castswith fully extended vestibular borders of the jaws, theradiographic templates were fabricated with thevacuum-formed technique (Fig 2), and the patientsand the radiographic template were scanned before theprocedure with the double-scan technique17 (the firstscan is of the patient with the radiographic template inplace, and the second scan is of the radiographic tem-plate only). The 3D virtual models of the teeth and the2 jaws were reconstructed based on the CT data in the

Fig 3. A-C, 3D models of bone, teeth, and template were reconstructed; D, with references of theradiographic markers (arrows in A and B), the 3D models were matched to each other.

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MIMICS software (Fig 3, A-C) by superimposing the 2sets of scans (the osseous tissues and the radiographictemplate) with radiographic markers as reference points(Fig 3, D). The virtual miniscrews were placed in safeand optimal positions when the roots of teeth were visu-alized (Fig 4, A), and the placement site and angle weredetermined. The drill template was designed with the ra-diographic guide and the 3D information of the planneddrill paths (Fig 4, B-D), and the stereolithography tem-plate was fabricated with a CAD/CAM procedure (therapid prototyping [RP] apparatus was manufacturedby Xi’an Jiaotong University); the template is shownin Figure 4, E. To improve the intensity of the template,the positioning sleeves were cemented in the surgicaltemplate (Fig 4, F). When the bone-teeth and radio-graphic templates were reconstructed, the thresholdswere chosen carefully, and the thickness of the radio-graphic template was compared with the stereolithogra-phy one to assess the reliability of the threshold and theaccuracy of the RP.

When the 3D models of the teeth and the 2 jawswere reconstructed, we evaluated the osseous tissuesin relation to the position of the teeth by merging the in-dependent data, and the virtual miniscrews (cylinders)were placed in the ideal position (proper placementsite and orientation). When the position for the mini-screw was determined (Fig 5, A), a plane was createdalong the cylinder (Fig 5, B). The distance betweenthe 2 roots for the miniscrew was measured. At thisplane, the minimum distance between the 2 roots wasmeasured. As we know, the periodontal ligament is

about 0.15 to 0.38 mm thick on average,3,27 and thediameter of the miniscrew in this study was 1.6 mm.The virtual screw was placed in the midline of the 2roots, and the safe deviation for the miniscrew couldbe calculated by the formula, C 5 A/2 – B – 0.4 mm,where A is the interradicular distance, B is the radiusof the miniscrew, and C is the safe deviation. Theperiodontal ligament was assumed to be 0.4 mm thickin this study for safe placement. Thus, the alloweddeviation for the miniscrew was obtained and used asthe control for assessment of the accuracy of thetemplate.

After a local anesthetic was given, the surgical tem-plate was placed intraorally. The seating of the templateshould be confirmed, and the surgical template shouldbe held in place by the patient’s bite force. Once itwas seated, the patient was asked to bite the templateto expose the surgical sites of the guide; then the self-drilling miniscrews were placed with a screwdriver(Fig 6).

The surgical procedures were performed unevent-fully, and the patients were scanned with CT again.The postoperative 3D models of the teeth, maxillae,mandibles, and miniscrews were reconstructed and reg-istered with the preoperative 3D models by using thesame anatomic sites as landmark points (Fig 7). Thepoint registration easily moved an STL image to a cer-tain location. This was done by placing 4 sets of land-mark points on the STL images, 3D objects, andimages. MIMICS then calculated the transformationmatrix for the best fit between the start and end points

Fig 4. A and B, In the 3D models, the virtual miniscrews (black arrows) were placed in ideal positions;C and D, trajectories for miniscrew placement along the cylinders (yellow arrows), and the virtual tem-plate was exported in sterolithography format; E, templates fabricated by SLA; F, bonded withguided sleeves in the trajectory and adjusted to ensure proper seating on the cast.

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and applied that transformation matrix on the selectedSTL images. Because of the radiographic template onthe occucal surface, the mandible’s position on the be-fore and after CT images was different, so the mandibleand maxilla must be registered separately (Fig 7). Afterpoint registration, the STL registration was performedto register STL images on masks to improve the accu-racy of registration. Registrations were performed 3times in 2 weeks, and we chose the best one for mea-surements of this study (Fig 8).

To measure the deviation of the center position ofthe miniscrews from the planned position (cylinders)in 3 dimensions, the new 3D coordinate was adjustedand defined at the apex of the virtual miniscrew inMagics (Fig 9). The x, y, and z axes were defined: thex-axis represents the distomesial position, the y-axisrepresents the vertical position, and the z-axis representsthe buccopalatal position. The 3D deviation of the ac-tual miniscrew was calculated at the apex and the place-ment site (Fig 9). The x, y, and z values at the apexrepresented the deviation of the actual miniscrew. In

this way, the deviation was evaluated in 3 directions,and the distomesial position (x-axis) was more impor-tant for the security of the miniscrew. In this study, wemainly focused on assessing this axis. As for angle de-viations, they were hard to evaluate, since the angle be-tween the actual miniscrew and the simulated oneshowed a twisted relationship. Therefore, in this study,both central axes were projected to the mesiodistalaxis, and the deviation of the angle between them wascalculated with the formula, q 5 tan – 1 (b – a)/c, wherea is the deviation at the tail, b is the deviation at thehead, and c is the length of the miniscrew in the bone.At the placement sites, there was little deviation, sothe deviation there was measured with linear CT mea-surements instead of 3D assessment.

Statistical analysis

All measurements were repeated for 15 randomlyselected subjects, with a 1-week interval, to assess intra-examiner reliability, which showed no statistical

Fig 5. When the position of the miniscrew was determined, the minimum distance between the rootswas measured at the new plane.

Fig 6. A-C, Local anesthetic was administered, and the miniscrews were placed with the aid of thesurgical template (screwdriver shown as black arrows); D, the miniscrews (red arrows) were placed inthe proper positions.

American Journal of Orthodontics and Dentofacial Orthopedics Liu et al 728.e5Volume 137, Number 6

differences (P .0.05) from the paired t test. The methoderror according to Dahlberg’s formula was 93.2.34 Themeans and standard deviations of the measurementswere calculated. To compare the template deviationwith the allowed deviation, a paired t test was used,and 2-way analysis of variance (ANOVA) was used toanalyze the deviations in 3 direction (SPSS for Win-dows, version 11.5, SPSS, Chicago, Ill). P \0.05 wasconsidered to be statistically significant.

RESULTS

The interradicular safe zones for miniscrews in the11 patients ranged from 3.7 to 4.5 mm, with an averageof 4.12 6 0.247 mm (mean 6 SD). The allowed devia-tion ranged from 0.65 to 1.05 mm, with an average of0.86 6 0.125 mm (mean 6 SD).

The templates were adapted to the patients in a satis-factory and stable manner. All miniscrews were placedsmoothly without problems. Some miniscrews did not

Fig 7. A, Pretreatment; and B, posttreatment models registered with the same anatomic sites aslandmarks (maxillary [black arrows], mandibular [red arrows]); C and D, registrations of the 2 models.

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touch the adjacent roots (Fig 8, B). The accuracy of dril-ling, and the deviations of the positions and angles of theactual miniscrew from the simulations, were examinedin 3 directions.

The position deviations at the distomesial, vertical,and buccopalatal directions were 0.42 6 0.13, 0.47 6

0.12, and 0.59 6 0.26 mm at the tip, respectively, and0.10 6 0.012 mm at the placement sites. The miniscrewdeviations of the angles from the planned position at thedistomesial, vertical, and buccopalatal directions were1.2� 6 0.43�, 1.3� 6 0.41�, and 1.6� 6 0.79�, respec-tively. No statistically significant differences were ob-served between the deviations at the distomesial andvertical directions. The buccopalatal deviation wasgreater than the other 2 directions, with a significant dif-ference (Fig 10, A). In this study, the deviations at thevertical and buccopalatal directions did not influencethe security of miniscrew; we focused mainly on the di-stomesial deviations. All deviations of the miniscrewswere in the safe zone, and each actual deviation wassmaller than the allowed one. As seen in Figure 10,the deviation of the template guide group was signifi-cantly smaller than that of the control group (alloweddeviation); the difference was statistically significant(P \0.05).

DISCUSSION

CT is an important diagnostic tool for the craniofa-cial region and is used for many applications includingthe study of its various components, growth, develop-

mental anomalies, impacted teeth, management of max-illofacial trauma, treatment planning for orthognathicand reconstructive surgery, bone grafting, distractionosteogenesis, and dental implantology. Qualitative andquantitative findings and measurements from CT tech-niques are accurate and reproducible, and offer greaterand more reliable assessment of deeper anatomic struc-tures than systems involving biplanar radiography.5,7-12,30

Yet there are many reports on the use of CT to measureinterradicular spaces for placement of miniscrews.Poggio et al,27 Park,31 and Carano et al32 measuredthe distances between the roots of adjacent teeth usingdifferent methods; they all demonstrated that interra-dicular spaces for miniscrews are limited, and minis-crews must be placed accurately. In those studies,the measurements of interradicular spaces for minis-crews were based on 2-dimensional (2D) images(slices) of the CT scans. However, miniscrews are al-ways placed with an inclined angle, obviously limitingmeasurement of the 2D images.3 In this study, the 3Dinterpolation technique that transforms 2D images(slices) into 3D models was used; with 3D software,the simulated miniscrew can be placed in an idealposition. Along the axis of the miniscrew, the mesio-distal distance between adjacent roots can bemeasured individually, and the safe zone for the mini-screw was calculated. By using this method, the safezone is more reliable, and the mesiodistal distancebetween the 2 roots was shown to be limited forminiscrew placement (Fig 10, B).

Fig 8. After registration, the actual miniscrews (red arrows) were matched to the virtual ones (blackarrows): A, pretreatment models; B, posttreatment models; C and D, registrations of the 2 models.

Fig 9. A and B, Registration of virtual and actual miniscrews; C, new 3D coordinate was adjusted anddefined at the apex of the virtual miniscrew in Magics software; D, measurement of the 3D distance ofthe virtual and actual miniscrews at the apex.

American Journal of Orthodontics and Dentofacial Orthopedics Liu et al 728.e7Volume 137, Number 6

The CAD/CAM surgical template has been widelyused for implants and prostheses, and its accuracy hadbeen shown in many studies.24-29 Similar to implants,miniscrews placed in limited interradicular spacesneed high accuracy. The CAD/CAM template givesorthodontists another safe way to place miniscrews.Accuracy and security were evaluated in this study,and it was demonstrated that the surgical template can

place the miniscrew in the safe zone with limiteddeviation. Many reasons were proposed to account forthe deviations observed in the template evaluation, asfollows.

The stability and inherent support of the template issurely a crucial factor.24,28 In this study, the templatewas supported by 2 surfaces—occusal teeth andbuccal mucosa—and the bite force on the template

Fig 10. A, Deviations in 3 directions; B, allowed and actual distomesial deviations. No statisticallysignificant differences were observed between the distomesial and vertical deviation groups. Thebuccopalatal deviation was greater than other 2 directions. The actual distomesial deviation was sig-nificantly smaller than that of the control group (allowed deviation) (P \0.05).

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provided support to keep it stable. So the interocclusalrecord with a rigid vinyl polysiloxane (Access Blue,Centrix Dental, Shelton, Conn) for the patient to holdthe radiographic template in position during the CTscan and prevent movement could help hold the CAD/CAM template in the right position.

The size of the 3D model depends on the thresholdvalue, which is a specific density on a slice image thatseparates the organ of interest and other regions. There-fore, it is important to select the proper threshold value.An inadequate threshold value of the radiographic tem-plate affected the accuracy of the STL model greatly. Inthis study, the maxillary, mandibular, teeth, and radio-graphic templates were reconstructed with differentthreshold values (387-1988HU, 415-1988HU, 1430-2850HU, and -630-690HU in Mimics). When the 3Dmodels are reconstructed, the size must be comparedto the actual one, so that the proper threshold can be ob-tained.

During the procedure of template design, the regis-tration was based on the landmarks that were added onthe radiographic template (Fig 2, A and B). The accu-racy was assessed after the registration of the preoper-ative and postoperative models. In this study, thecombination of 2 registration methods improvedthe accuracy. The before and after models were thesame, but the miniscrews and the STL images’ regis-trations achieved better results. Repeated registrations,choosing the best registration by visual inspection, andidentifying corresponding landmarks ensured the accu-racy of the registrations. The registrations were per-formed carefully, and the results were satisfactory(Figs 8 and 9).

RP is a relatively new technology that producesphysical models by selectively solidifying ultraviolet-sensitive liquid resin with a laser beam. Choi et al29 in-vestigated errors generated during the production ofmedical RP models and showed that the absolutemean deviation between the original and RP modelsover the 16 linear measurements was 0.56% 6 0.39%;this had little influence on the accuracy of the template.In our study, the thickness of the template was mea-sured, and the mean deviation was about 0.87% 6

0.45%, so that the RP deviation caused little change inthe deviation of miniscrew placement.

The template in the study was designed with CAD/CAM implant template methods, but there are still somedifferences. A miniscrew is placed in the buccopalataldirection and an implant is in the vertical direction, sothe shape and the support methods are different withthe implant template. To keep the miniscrew stable, atleast 1 anchor pin through the alveolar process is usedfor more support of the implant template. The mini-screw template remains stable from the patient’s biteforce. There are scale markers at the head of the drillsfor implant depth control, and we also put a markeron the screwdriver to control the depth of the minis-crews in this study; 3D control of miniscrew wasachieved even though the buccopalatal deviation wasgreater than in the other 2 directions (Fig 10, A).

The template still has some deficiencies, and im-provement of its elaborate design and further studiesshould be performed to evaluate the reliability, validity,and global applicability of stereolithographic surgicalguides for miniscrews. The high radiation of a CTscan and the high cost limit the broad use of this

American Journal of Orthodontics and Dentofacial Orthopedics Liu et al 728.e9Volume 137, Number 6

CAD/CAM guide for miniscrews. But this studyshowed a CAD/CAM guide system constructed for or-thodontic miniscrews similar to prosthetic implantguides and verified that the accuracy of the CAD/CAM template was enough for miniscrew control andsafe placement.

CONCLUSIONS

Within the limits of this study, we presented an ac-curacy evaluation of the CAD/CAM template for minis-crews, and the registrations of the 3D modelsreconstructed with the preoperative and postoperativeCT data were validated. The average measured devia-tions of the miniscrews were in the safe range. These re-sults verified the template’s accuracy and security. Thetemplate, manufactured with the Nobel method, canprovide safe placement for miniscrews.

We thank Professor Guang-chun Wang for his assis-tance.

REFERENCES

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

risk factors associated with failure of mini-implants used for or-

thodontic anchorage. Int J Oral Maxillofac Implants 2004;19:

100-6.

2. 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.

3. Lim JE, Lim WH, Chun YS. Quantitative evaluation of cortical

bone thickness and root proximity at maxillary interradicular sites

for orthodontic mini-implant placement. Clin Anat 2008;21:

486-91.

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

miniscrews. Am J Orthod Dentofacial Orthop 2007;131:43-51.

5. Moon CH, Lee DG, Lee HS, Jin JS, Baek SH. Factors associated

with the success rate of orthodontic miniscrews placed in the up-

per and lower posterior buccal region. Angle Orthod 2008;78:

101-6.

6. Yuan-Hou Chen, Hao-Hueng Chang, Yi-Jane Chen, David Lee,

Hsien-Hsiung Chiang, Chung-Chen Jane Yao. Root contact dur-

ing insertion of miniscrews for orthodontic anchorage increases

the failure rate: an animal study. Clin Oral Implants Res 2008;

19:99-106.

7. Kuroda S, Yamada K, Deguchi T, Hashimoto T, Kyung HM,

Takano-Yamamoto T. Root proximity is a major factor for screw

failure in orthodontic anchorage. Am J Orthod Dentofacial Orthop

2007;131(Suppl):S68-73.

8. Park HS, Jeong SH, Kwon OW. Factors affecting the clinical

success of screw implants used as orthodontic anchorage. Am J

Orthod Dentofacial Orthop 2006;130:18-25.

9. Sammartino G, Della Valle A, Marenzi G, Gerbino S,

Martorelli M, di Lauro AE, et al. Stereolithography in oral im-

plantology: a comparison of surgical guides. Implant Dent

2004;13:133-9.

10. Adams GL, Gansky SA, Miller AJ, Harrell WE, Hatcher DC.

Comparison between traditional 2-dimensional cephalometry

and a 3-dimensional approach on human dry skulls. Am J Orthod

Dentofacial Orthop 2004;126:397-409.

11. De Smet E, Jacobs R, Gijbels F, Naert I. The accuracy and reliabil-

ity of radiographic methods for the assessment of marginal bone

level around oral implants. Dentomaxillofac Radiol 2002;31:

176-81.

12. Suzuki EY, Suzuki B. A simple three-dimensional guide for safe

miniscrew placement. J Clin Orthod 2007;41:342-6.

13. Maino BG, Bednar J, Pagin P, Mura P. The spider screw for skel-

etal anchorage. J Clin Orthod 2003;37:90-7.

14. Graham JW, Cope JB. Miniscrew troubleshooting—how to

manage potential complications of using temporary anchorage

devices. Orthod Prod 2006;13:26-32.

15. Lal K, White GS, Morea DN, Wright RF. Use of stereolitho-

graphic templates for surgical and prosthodontic implant plan-

ning and placement. Part I. The concept. J Prosthodont 2006;

15:51-8.

16. Tardieu PB, Vrielinck L, Escolano E. Computer-assisted implant

placement. A case report: treatment of the mandible. Int J Oral

Maxillofac Implants 2003;18:599-604.

17. Marchack CB. CAD/CAM-guided implant surgery and fabrica-

tion of an immediately loaded prosthesis for a partially edentulous

patient. J Prosthet Dent 2007;97:389-94.

18. Rosenfeld AL, Mandelaris GA, Tardieu PB. Prosthetically

directed implant placement using computer software to ensure

precise placement and predictable prosthetic outcomes. Part

3: stereolithographic drilling guides that do not require bone

exposure and the immediate delivery of teeth. Int J Periodontics

Restorative Dent 2006;26:493-9.

19. Van Steenberghe D. Interactive imaging for implant planning.

J Oral Maxillofac Surg 2005;63:883-4.

20. Ganz SD. Techniques for the use of CT imaging for the fabrication

of surgical guides. Atlas Oral Maxillofac Surg Clin North Am

2006;14:75-97.

21. van Steenberghe D, Glauser R, Blomback U, Andersson M,

Schutyser F, Pettersson A, et al. A computed tomographic scan-

derived customized surgical template fixed prosthesis for flapless

surgery immediate loading of implants in fully edentulous maxil-

lae: a prospective multicenter study. Clin Implant Dent Relat Res

2005;7(Suppl 1):S111-20.

22. Hieu LC, Bohez E, Vander Sloten J, Phien HN, Vatcharaporn E,

An PV, et al. Design and manufacturing of personalized implants

and standardized templates for cranioplasty applications. Pro-

ceedings of the 2002 IEEE International Conference on Industrial

Automations; 2002 Dec 11-14; Bangkok, Thailand. Vol. 2. Bang-

kok, Thailand; 2002. p. 1025-30, http://ieeexplore.ieee.org/xpl/

freeabs_all.jsp?arnumber=1189312.

23. Nickenig HJ, Eitner S. Reliability of implant placement after vir-

tual planning of implant positions using cone beam CT data and

surgical (guide) templates. J Craniomaxillofac Surg 2007;35:

207-11.

24. Sarment DP, Sukovic P, Clinthorne N. Accuracy of implant place-

ment with a stereolithographic surgical guide. Int J Oral Maxillo-

fac Implants 2003;18:571-7.

25. Ruppin J, Popovic A, Strauss M, Spuntrup E, Steiner A, Stoll C.

Evaluation of the accuracy of three different computer-aided sur-

gery systems in dental implantology: optical tracking vs. stereoli-

thographic splint systems. Clin Oral Implants Res 2008;19:

709-16.

26. Suzuki EY, Suzuki B. Accuracy of miniscrew implant placement

with a 3-dimensional surgical guide. J Oral Maxillofac Surg 2008;

66:1245-52.

27. Poggio PM, Incorvati C, Velo S, Carano A. ‘‘Safe zones’’: a guide

for miniscrew positioning in the maxillary and mandibular arch.

Angle Orthod 2006;76:191-7.

728.e10 Liu et al American Journal of Orthodontics and Dentofacial Orthopedics

June 2010

28. Ohtani T, Kusumoto N, Wakabayashi K, Yamada S, Nakamura T,

Kumazawa Y, et al. Application of haptic device to implant

dentistry—accuracy verification of drilling into a pig bone.

Dent Mater J 2009;28:75-81.

29. Choi JY, Choi JH, Kim NK, Kim Y, Lee JK, Kim MK, et al.

Analysis of errors in medical rapid prototyping models. Int J Oral

Maxillofac Surg 2002;31:23-32.

30. Suri S, Utreja A, Khandelwal N, Mago SK. Craniofacial comput-

erized tomography analysis of the midface of patients with re-

paired complete unilateral cleft lip and palate. Am J Orthod

Dentofacial Orthop 2008;134:418-29.

31. Park HS. An anatomical study using CT images for the implanta-

tion of micro-implants. Korean J Orthod 2002;32:435-41.

32. Carano A, Velo S, Incorvati C, Poggio P. Clinical applications of

the mini-screw-anchorage-system (M.A.S.) in the maxillary alve-

olar bone. Prog Orthod 2004;5:212-35.

33. Rudolph H, Luthardt RG, Walter MH. Computer-aided analy-

sis of the influence of digitizing and surfacing on the accuracy

in dental CAD/CAM technology. Comput Biol Med 2007;37:

579-87.

34. Houston WJB. The analysis of errors in orthodontic measure-

ments. Am J Orthod 1983;83:382-90.