CLINICIAN'S CORNER
Virtually fabricated guide for placement of the C-tube miniplate Janghyun Paek,a Do-Min Jeong,b Yong Kim,c Seong-Hun Kim,d Kyu-Rhim Chung,e and Gerald Nelsonf Seoul and Suwon, Korea, and San Francisco, Calif Introduction: This paper introduces a virtually planned and stereolithographically fabricated guiding system that will allow the clinician to plan carefully for the best location of the device and to achieve an accurate position without complications. Methods: The scanned data from preoperative dental casts were edited to obtain preoperative 3-dimensional (3D) virtual models of the dentition. After the 3D virtual models were repositioned, the 3D virtual surgical guide was fabricated. A surgical guide was created onscreen, and then these virtual guides were materialized into real ones using the stereolithographic technique. Results: Whereas the previously described guide required laboratory work to be performed by the orthodontist, our technique is more convenient because the laboratory work is done remotely by computer-aided design/computer-aided manufacturing technology. Because the miniplate is firmly held in place as the patient holds his or her mandibular teeth against the occlusal pad of the surgical guide, there is no risk that the miniscrews can slide on the bone surface during placement. The software program (2.5-dimensional software) in this study combines 2-dimensional cephalograms with 3D virtual dental models. This software is an effective and efficient alternative to 3D software when 3D computed tomography data are not available. Conclusions: To confidently and safely place a miniplate with screw fixation, a simple customized guide for an orthodontic miniplate was introduced. The use of a custom-made, rigid guide when placing miniplates will minimize complications such as vertical mislocation or slippage of the miniplate during placement. (Am J Orthod Dentofacial Orthop 2014;145:694-702)
C
ompared with mini-implants (sandblasted with large grit followed by acid etch [SLA]-coated) or miniscrews (machine surface screw), the use of miniplates as temporary skeletal anchorage devices has certain benefits.1 The miniplate devices are more stable and offer less risk of damage to nearby dental roots.2-5
a Clincal fellow, Department of Prosthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. b Director, Division of Periodontology, Department of Dentistry, National Medical Center of Korea, Seoul, Korea. c Research assistant, Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. d Associate professor and chairman, Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. e Professor and chairman, Department of Orthodontics, School of Medicine, Ajou University, Suwon, Korea. f Clinical professor and chair, Division of Orthodontics, Department of Orofacial Science, University of California San Francisco, San Francisco, Calif. Janghyun Paek and Do-Min Jeong are joint first authors and contributed equally to this work. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Kyung Hee University holds a patent on the device illustrated in this article and is the beneficiary of any financial gains from the device. Address correspondence to: Seong-Hun Kim, Department of Orthodontics, School of Dentistry, Kyung Hee University, #1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, Republic of Korea; e-mail, [email protected]. Submitted, October 2012; revised and accepted, February 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.02.036
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Researchers have reported that location and timing of force application are conditions that can influence the success of conventional mini-implants in interradicular spaces.1,3 Root proximity is a major factor for miniimplant failure in orthodontic anchorage applications.4 With the C-tube miniplate (Jin-Biomed Co, Bucheon, Korea), the mean placement depth of the miniplate's anchoring screw is 2.48 mm, which allows fewer complications than do longer miniscrews or mini-implants.5,6 To minimize the risks of damage to the adjacent roots or the cortical bone of the sinus wall, slippage of the screw during driving, or path-of-insertion angulation errors that might interfere with the accurate placement of the miniplate's anchoring screw, surgical guides have been designed. Paek et al7 proposed a simple customized surgical guide made of silicone material with a positioning wire. However, a virtually planned and stereolithographically fabricated guiding system will allow the clinician to plan carefully for the best location of the device and to achieve an accurate position without the afore-mentioned risks. Although several 3-dimensional (3D) programs have been introduced to reduce manual laboratory steps and potential errors, these programs still require 3D computed tomography data and involve complex computerized maneuvers. Because it is not appropriate to take 3D
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Fig 1. Preoperative radiographs (22-year-old man).
Fig 2. The 3D virtual dental casts were fabricated with a 3D laser scanner and 3Txer program (Orapix). A and B, the 3D virtual cast is automatically fitted into the 2D lateral cephalograms by digitizing the 2 landmark points. Yawing of the 3D virtual maxillary model is automatically fitted into the maxillary dentition portion of the 2D posteroanterior cephalograms by digitizing the 2 landmark points. The 3D virtual mandibular dental cast can automatically replace the mandibular dentition portion of the 2D lateral and posteroanterior cephalograms using the set position with 3D virtual maxillary dental cast. C, Combination of 3D virtual dental casts on 2D lateral and posteroanterior cephalograms. After this procedure, 3D virtual planning can be performed using the 2.5D program (Orapix). A virtual miniplate is selected from the software library and tentatively placed. D, Transparency of the superimposed images was adjusted to optimally view the location of the miniplate.
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Fig 3. Virtual planning and positioning of the C-tube guide were performed in the software: A, the final position was determined after jig positioning; B, the 3D virtual dental casts were verified in 2D lateral and posteroanterior cephalograms.
computed tomography scans for all patients, a new protocol has been introduced using 2-dimensional (2D) lateral and posteroanterior cephalograms and 3D virtual dental models (2.5D program, 3Txer version 2.5; Orapix, Seoul, Korea).8,9 In this report, the 2.5D program was used to fabricate the surgical guide with the stereolithographic technique. The purpose of this article is to introduce this novel way of virtually fabricating the surgical guide for placement of C-tube miniplates. MATERIAL AND METHODS
Preoperative dental casts were obtained with alginate impressions, using a centric occlusion wax bite and
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preoperative radiographs (Fig 1). Casts were shipped to Orapix (Seoul, Korea), where they were scanned with the proprietary 3D laser scanner (accuracy of 30 mm). The acquired scan data were edited to obtain preoperative 3D virtual casts using a 3Dxer and 3Txer program (Fig 2, A and B). The incisor edge of the maxillary right central incisor and the most distal point of the maxillary right second molar crown were digitized in both the 3D virtual maxillary dental cast and the 2D lateral cephalograms. Then the 3D virtual maxillary dental cast was automatically fitted into the maxillary dentition portion of the 2D lateral cephalograms by adjustment of the distance between these 2 points and matching the angulation of the line. The outermost buccal points of the crowns of the maxillary right and left second molars
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Fig 4. The C-tube guide was fabricated virtually with CAD/CAM technology.
were digitized in both the 3D virtual maxillary dental model and the 2D posteroanterior cephalograms. Then the 3D virtual maxillary dental model was automatically fitted into the maxillary dentition portion of the 2D posteroanterior cephalograms. The 3D virtual mandibular dental cast automatically replaced the mandibular dentition portion of the 2D lateral and posteroanterior cephalograms using the set position with the 3D virtual maxillary dental cast. As a result, the 3D virtual maxillary and mandibular dental casts could be combined with the 2D cephalograms in the 3D Cartesian coordinate system. After the 3D virtual casts were repositioned, the 3D virtual surgical guide was fabricated (Fig 2, A and B). After the correct miniplate position was determined by the doctor’s prescription on the virtual casts, the best size of virtual miniplate was selected from the software library and tentatively placed using the software (usually between the second premolar and the first molar) (Figs 2, C and D, and 3) After the position was confirmed by the doctor, a surgical guide was created on the screen, and these virtual guides were materialized into real ones using the stereolithographic technique (Figs 4 and 5). The surgical guide was adapted to the clinical site after local anesthesia (Fig 6). The miniplate can be slid along the horizontal wire for an easy incision (Fig 7, A). A minimal incision was made with a number 15 scalpel
blade (Fig 7, B and C), and then the positioning sleeve was removed after the incision (Fig 7, D and E). The sleeve is made of stereolithography resin so that it is easy to snap off the guide (Fig 7, F). Once the positioning sleeve was removed, the miniplate was flipped vertically, slipped into the incision, and placed on the underlying bone (Fig 8, A and B). Because the miniplate is firmly held in place as the patient holds his or her mandibular teeth against the occlusal pad of the surgical guide, there is no risk that the miniscrews (diameter, 1.5 mm; length, 4 mm) will slide on the bone surface during placement. A manual hand driver is adequate to drive the selfdrilling miniscrews (Fig 8, C-F). All screws were placed, and the guide was removed by slipping out the steel wire axle from the guide (Fig 9, A and B). Minimal sutures were placed using 4-0 silk to close the incision (Fig 9, C and D). The miniplate was buried under mucosa at the mucogingival junction, and the tube part of the C-tube miniplate was exposed for access to skeletal anchorage. After 1 week of healing, the sutures were removed, and the C-tubes were loaded. A postoperative computed tomography scan was taken, and no complication was observed (Fig 10). The C-tube guide has a clinical advantage for mandibular anterior teeth (Fig 11). As in the previously described biocreative technique, preadjusted 0.022-in fixed appliances were bonded only on the
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Fig 5. The plastic sleeve is an incision guide. The horizontal wire enables the miniplate to be rotated into place. The guide was designed to place the miniplate between the second premolar and the first molar as planned in the software.
Fig 6. The surgical guide is adapted to the clinical site.
maxillary anterior 6 teeth, which were then retracted against the C-tubes without requiring any attachments on the maxillary posterior teeth.10,11 This is beneficial because when the posterior teeth are engaged during temporary skeletal anchorage device retraction, they will typically be distalized, but this might not be desired. The C-tubes were comfortable for the patient throughout the entire orthodontic treatment and were easily removed with a minor incision.
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DISCUSSION
Recent advances in cone-beam computed tomography and computer-aided design/computer-aided manufacturing (CAD/CAM) technology have enabled a variety of schemes for virtual diagnosis, treatment planning, and model surgery.12-15 Sachdeva16 suggested that computer-aided 3D technology could provide 3D tools for diagnosis, monitoring, and patient communication,
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Fig 7. A, The miniplate can be slid along the horizontal wire for an easy incision; B and C, a minimal incision is made with a number 15 scalpel blade, guided by the incision positioning sleeve; D-F, the positioning sleeve is removed after the incision.
Fig 8. A, After the incision, the positioning sleeve is cut and removed. B, The miniplate is flipped vertically, slipped into the incision, and placed on the underlying bone. C-F, The miniplate is stably positioned, and the screws are drilled and fixated at the desired positions with no slippage.
as well as customized orthodontic treatment by precisely positioning the brackets. Son et al17 showed the possibility of virtual orthodontic treatment systems and suggested that more predictable tooth movements could be achieved if treatment is planned with a 3D virtual transfer jig fabricated from computer-simulated tooth
movements. According to Choi et al,14 the procedures for 3D virtual model surgery consist of creation of the 3D virtual dental casts, replacement of the dentition in the 3D computed tomography data with the 3D virtual dental casts, repositioning of the 3D virtual dental casts, and fabrication of the real surgical wafers using the
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Fig 9. A-C, All screws are fixated, and the guide is removed by slipping out the steel wire axle from the guide. D, Minimal sutures were required to close the incision area. The miniplate is buried under the mucosa at the mucogingival junction, and the C-tube part of the device is exposed for access to skeletal anchorage.
Fig 10. The postoperative cone-beam computed tomography images were reviewed, and no complication was observed.
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Fig 11. I-type C-tube application in the mandibular anterior area: A, adapation to clinical site; B, incision; C, positioning sleeve removal; D, placement of miniplate anchoring screws; E, guide removal; F, suture.
stereolithographic technique. As reported in the studies mentioned above, 3D CAD/CAM technology has become a new and powerful tool in orthodontics.18,19 Our goal was to accurately locate and fixate the miniplate as planned by the orthodontist. Other methods have been reported: eg, a simple customized surgical guide for the orthodontic miniplate with a tube was introduced by Paek et al.7 Although it was helpful, this previous guide was technique sensitive because the embedded positioning wire had some error potential, such that when the patient closed the mandibular teeth on the silicone material, the wire guide could move. Stereolithographic resin is not flexible, so this eliminates that concern. Soft material is not as accurate as the stereolithography resin. Whereas Paek et al's previously reported guide required laboratory work by the orthodontist, the technique described here is more convenient, since the laboratory work is done remotely by CAD/CAM. Virtual design of the stereolithographic surgical guide enables both the orthodontist and the surgeon to accurately predetermine the correct position for the miniplate. Use of the surgical guide introduced in this study can allow the clinician to accurately plan a safe location for the miniplate with firm and stable placement. The guide adapts to the buccal and occlusal aspects of the tooth precisely. Besides providing a firm location for the miniplate, the guide also has a scalpel guide for the incision. Before proceeding, the clinician can verify that the miniplate's screw holes match the incision location. With this technique, a large tissue flap is not necessary. The guide is
keyed to the occlusal surface, and the patient holds the guide in place by closing his or her teeth on its occlusal pad. In this report, we have introduced a C-tube guide planned with computer software (Orapix) and fabricated remotely by stereolithography. A new approach using conventional 2D cephalograms for a 3D approach was used. The recently introduced software uses 2D lateral and posteroanterior cephalograms and 3D virtual dental models. Because this program can combine 2D cephalograms with 3D virtual dental casts, it is called “2.5D software.” This program is useful because it is inappropriate to take 3D computed tomography scans for all patients. High cost and radiation exposure from 3D computed tomography scans are issues.9,20 Therefore, the 2.5D software can be regarded as a low-exposure and effective alternative to 3D software with cone-beam computed tomography. CONCLUSIONS
To confidently and safely place a miniplate with screw fixation, a simple customized placement guide for the orthodontic miniplate was introduced. The Orapix system provides extremely accurate and stable surgical guide positioning, thanks to CAD/CAM technology. The use of a custom-made, rigid guide when placing a miniplate could minimize complications such as vertical mislocation or slippage of the miniplate during placement. In-office laboratory procedures are reduced because of virtual planning and stereolithography; thus, the requirement for extremely careful technique is minimized.
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ACKNOWLEDGMENTS
We thank Soon-Yong Kwon for manuscript editing and Suk-Jin Kang, technical manager of Orapix, for his technical assistance during manuscript preparation.
10.
11.
REFERENCES 1. Chen YJ, Chang HH, Huang CY, Hung HC, Lai EH, Yao CC. A retrospective analysis of the failure rate of three different orthodontic skeletal anchorage systems. Clin Oral Implants Res 2007;18:768-75. 2. Chung KR, Kim SH, Kang YG, Nelson G. Orthodontic miniplate with tube as an efficient tool for borderline cases. Am J Orthod Dentofacial Orthop 2011;139:551-62. 3. Moon CH, Lee DG, Lee HS, Im JS, Baek SH. Factors associated with the success rate of orthodontic miniscrews placed in the upper and lower posterior buccal region. Angle Orthod 2008;78:101-6. 4. 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. 5. Kim GT, Kim SH, Choi YS, Park YJ, Chung KR, Suk KE, et al. Conebeam computed tomography evaluation of orthodontic miniplate anchoring screws in the posterior maxilla. Am J Orthod Dentofacial Orthop 2009;136:628.e1-10. 6. Ahn HW, Chung KR, Kang SM, Lin L, Nelson G, Kim SH. Correction of dental Class III with posterior open bite by simple biomechanics using an anterior C-tube miniplate. Korean J Orthod 2012;42:270-8. 7. Paek J, Su MJ, Kwon SY, Kim SH, Chung KR, Nelson G. A simple customized surgical guide for orthodontic miniplates with tube. J Craniofac Surg 2012;23:e468-70. 8. Choi JY, Choi JP, Baek SH. Surgical accuracy of the maxillary repositioning according to surgical movement type of the maxilla in two-jaw surgery. Angle Orthod 2009;79:306-11. 9. Choi JY, Hwang JM, Baek SH. Virtual model surgery and wafer fabrication using 2-dimensional cephalograms, 3-dimensional vir-
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16. 17.
18. 19.
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tual dental models, and stereolithographic technology. Oral Surg Oral Med Oral Pathol Oral Radiol 2012;113:193-200. Chung KR, Kim SH, Kook YA, Choo H. Anterior torque control using partial-osseointegrated mini-implants: biocreative therapy type II technique. World J Orthod 2008;9:105-13. Mo SS, Kim SH, Sung SJ, Chung KR, Chun YS, Kook YA, et al. Factors controlling anterior torque with C-implants depend on en-masse retraction without posterior appliances: biocreative therapy type II technique. Am J Orthod Dentofacial Orthop 2011;139:e183-91. Song KG, Baek SH. Comparison of the accuracy of the threedimensional virtual method and the conventional manual method for model surgery and intermediate wafer fabrication. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:13-21. Xia JJ, Gateno J, Teichgraeber JF. Three-dimensional computeraided surgical simulation for maxillofacial surgery. Atlas Oral Maxillofac Surg Clin North Am 2005;13:25-39. Choi JY, Song KG, Baek SH. Virtual model surgery and wafer fabrication for orthognathic surgery. Int J Oral Maxillofac Surg 2009; 38:1306-10. Swennen GR, Mollemans W, Schutyser F. Three-dimensional treatment planning of orthognathic surgery in the era of virtual imaging. J Oral Maxillofac Surg 2009;67:2080-92. Sachdeva RC. SureSmile technology in a patient-centered orthodontic practice. J Clin Orthod 2001;35:245-53. Son KH, Park JW, Lee DK, Kim KD, Baek SH. New virtual orthodontic treatment system for indirect bonding using the stereolithographic technique. Korean J Orthod 2011;41:138-45. Oh JY, Park JW, Baek SH. Surgery-first approach in Class III openbite. J Craniofac Surg 2012;23:e283-7. Silva MA, Wolf U, Heinicke F, Bumann A, Visser H, Hirsch E. Conebeam computed tomography for routine orthodontic treatment planning: a radiation dose evaluation. Am J Orthod Dentofacial Orthop 2008;133:640.e1-5. Hwang HS, Yuan D, Jeong KH, Uhm GS, Cho JH, Yoon SJ. Threedimensional soft tissue analysis for the evaluation of facial asymmetry in normal occlusion individuals. Korean J Orthod 2012;42:56-63.
American Journal of Orthodontics and Dentofacial Orthopedics
Virtually fabricated guide for placement of the C-tube miniplate Janghyun Paek,a Do-Min Jeong,b Yong Kim,c Seong-Hun Kim,d Kyu-Rhim Chung,e and Gerald Nelsonf Seoul and Suwon, Korea, and San Francisco, Calif Introduction: This paper introduces a virtually planned and stereolithographically fabricated guiding system that will allow the clinician to plan carefully for the best location of the device and to achieve an accurate position without complications. Methods: The scanned data from preoperative dental casts were edited to obtain preoperative 3-dimensional (3D) virtual models of the dentition. After the 3D virtual models were repositioned, the 3D virtual surgical guide was fabricated. A surgical guide was created onscreen, and then these virtual guides were materialized into real ones using the stereolithographic technique. Results: Whereas the previously described guide required laboratory work to be performed by the orthodontist, our technique is more convenient because the laboratory work is done remotely by computer-aided design/computer-aided manufacturing technology. Because the miniplate is firmly held in place as the patient holds his or her mandibular teeth against the occlusal pad of the surgical guide, there is no risk that the miniscrews can slide on the bone surface during placement. The software program (2.5-dimensional software) in this study combines 2-dimensional cephalograms with 3D virtual dental models. This software is an effective and efficient alternative to 3D software when 3D computed tomography data are not available. Conclusions: To confidently and safely place a miniplate with screw fixation, a simple customized guide for an orthodontic miniplate was introduced. The use of a custom-made, rigid guide when placing miniplates will minimize complications such as vertical mislocation or slippage of the miniplate during placement. (Am J Orthod Dentofacial Orthop 2014;145:694-702)
C
ompared with mini-implants (sandblasted with large grit followed by acid etch [SLA]-coated) or miniscrews (machine surface screw), the use of miniplates as temporary skeletal anchorage devices has certain benefits.1 The miniplate devices are more stable and offer less risk of damage to nearby dental roots.2-5
a Clincal fellow, Department of Prosthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. b Director, Division of Periodontology, Department of Dentistry, National Medical Center of Korea, Seoul, Korea. c Research assistant, Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. d Associate professor and chairman, Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea. e Professor and chairman, Department of Orthodontics, School of Medicine, Ajou University, Suwon, Korea. f Clinical professor and chair, Division of Orthodontics, Department of Orofacial Science, University of California San Francisco, San Francisco, Calif. Janghyun Paek and Do-Min Jeong are joint first authors and contributed equally to this work. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Kyung Hee University holds a patent on the device illustrated in this article and is the beneficiary of any financial gains from the device. Address correspondence to: Seong-Hun Kim, Department of Orthodontics, School of Dentistry, Kyung Hee University, #1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, Republic of Korea; e-mail, [email protected]. Submitted, October 2012; revised and accepted, February 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.02.036
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Researchers have reported that location and timing of force application are conditions that can influence the success of conventional mini-implants in interradicular spaces.1,3 Root proximity is a major factor for miniimplant failure in orthodontic anchorage applications.4 With the C-tube miniplate (Jin-Biomed Co, Bucheon, Korea), the mean placement depth of the miniplate's anchoring screw is 2.48 mm, which allows fewer complications than do longer miniscrews or mini-implants.5,6 To minimize the risks of damage to the adjacent roots or the cortical bone of the sinus wall, slippage of the screw during driving, or path-of-insertion angulation errors that might interfere with the accurate placement of the miniplate's anchoring screw, surgical guides have been designed. Paek et al7 proposed a simple customized surgical guide made of silicone material with a positioning wire. However, a virtually planned and stereolithographically fabricated guiding system will allow the clinician to plan carefully for the best location of the device and to achieve an accurate position without the afore-mentioned risks. Although several 3-dimensional (3D) programs have been introduced to reduce manual laboratory steps and potential errors, these programs still require 3D computed tomography data and involve complex computerized maneuvers. Because it is not appropriate to take 3D
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Fig 1. Preoperative radiographs (22-year-old man).
Fig 2. The 3D virtual dental casts were fabricated with a 3D laser scanner and 3Txer program (Orapix). A and B, the 3D virtual cast is automatically fitted into the 2D lateral cephalograms by digitizing the 2 landmark points. Yawing of the 3D virtual maxillary model is automatically fitted into the maxillary dentition portion of the 2D posteroanterior cephalograms by digitizing the 2 landmark points. The 3D virtual mandibular dental cast can automatically replace the mandibular dentition portion of the 2D lateral and posteroanterior cephalograms using the set position with 3D virtual maxillary dental cast. C, Combination of 3D virtual dental casts on 2D lateral and posteroanterior cephalograms. After this procedure, 3D virtual planning can be performed using the 2.5D program (Orapix). A virtual miniplate is selected from the software library and tentatively placed. D, Transparency of the superimposed images was adjusted to optimally view the location of the miniplate.
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Fig 3. Virtual planning and positioning of the C-tube guide were performed in the software: A, the final position was determined after jig positioning; B, the 3D virtual dental casts were verified in 2D lateral and posteroanterior cephalograms.
computed tomography scans for all patients, a new protocol has been introduced using 2-dimensional (2D) lateral and posteroanterior cephalograms and 3D virtual dental models (2.5D program, 3Txer version 2.5; Orapix, Seoul, Korea).8,9 In this report, the 2.5D program was used to fabricate the surgical guide with the stereolithographic technique. The purpose of this article is to introduce this novel way of virtually fabricating the surgical guide for placement of C-tube miniplates. MATERIAL AND METHODS
Preoperative dental casts were obtained with alginate impressions, using a centric occlusion wax bite and
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preoperative radiographs (Fig 1). Casts were shipped to Orapix (Seoul, Korea), where they were scanned with the proprietary 3D laser scanner (accuracy of 30 mm). The acquired scan data were edited to obtain preoperative 3D virtual casts using a 3Dxer and 3Txer program (Fig 2, A and B). The incisor edge of the maxillary right central incisor and the most distal point of the maxillary right second molar crown were digitized in both the 3D virtual maxillary dental cast and the 2D lateral cephalograms. Then the 3D virtual maxillary dental cast was automatically fitted into the maxillary dentition portion of the 2D lateral cephalograms by adjustment of the distance between these 2 points and matching the angulation of the line. The outermost buccal points of the crowns of the maxillary right and left second molars
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Fig 4. The C-tube guide was fabricated virtually with CAD/CAM technology.
were digitized in both the 3D virtual maxillary dental model and the 2D posteroanterior cephalograms. Then the 3D virtual maxillary dental model was automatically fitted into the maxillary dentition portion of the 2D posteroanterior cephalograms. The 3D virtual mandibular dental cast automatically replaced the mandibular dentition portion of the 2D lateral and posteroanterior cephalograms using the set position with the 3D virtual maxillary dental cast. As a result, the 3D virtual maxillary and mandibular dental casts could be combined with the 2D cephalograms in the 3D Cartesian coordinate system. After the 3D virtual casts were repositioned, the 3D virtual surgical guide was fabricated (Fig 2, A and B). After the correct miniplate position was determined by the doctor’s prescription on the virtual casts, the best size of virtual miniplate was selected from the software library and tentatively placed using the software (usually between the second premolar and the first molar) (Figs 2, C and D, and 3) After the position was confirmed by the doctor, a surgical guide was created on the screen, and these virtual guides were materialized into real ones using the stereolithographic technique (Figs 4 and 5). The surgical guide was adapted to the clinical site after local anesthesia (Fig 6). The miniplate can be slid along the horizontal wire for an easy incision (Fig 7, A). A minimal incision was made with a number 15 scalpel
blade (Fig 7, B and C), and then the positioning sleeve was removed after the incision (Fig 7, D and E). The sleeve is made of stereolithography resin so that it is easy to snap off the guide (Fig 7, F). Once the positioning sleeve was removed, the miniplate was flipped vertically, slipped into the incision, and placed on the underlying bone (Fig 8, A and B). Because the miniplate is firmly held in place as the patient holds his or her mandibular teeth against the occlusal pad of the surgical guide, there is no risk that the miniscrews (diameter, 1.5 mm; length, 4 mm) will slide on the bone surface during placement. A manual hand driver is adequate to drive the selfdrilling miniscrews (Fig 8, C-F). All screws were placed, and the guide was removed by slipping out the steel wire axle from the guide (Fig 9, A and B). Minimal sutures were placed using 4-0 silk to close the incision (Fig 9, C and D). The miniplate was buried under mucosa at the mucogingival junction, and the tube part of the C-tube miniplate was exposed for access to skeletal anchorage. After 1 week of healing, the sutures were removed, and the C-tubes were loaded. A postoperative computed tomography scan was taken, and no complication was observed (Fig 10). The C-tube guide has a clinical advantage for mandibular anterior teeth (Fig 11). As in the previously described biocreative technique, preadjusted 0.022-in fixed appliances were bonded only on the
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Fig 5. The plastic sleeve is an incision guide. The horizontal wire enables the miniplate to be rotated into place. The guide was designed to place the miniplate between the second premolar and the first molar as planned in the software.
Fig 6. The surgical guide is adapted to the clinical site.
maxillary anterior 6 teeth, which were then retracted against the C-tubes without requiring any attachments on the maxillary posterior teeth.10,11 This is beneficial because when the posterior teeth are engaged during temporary skeletal anchorage device retraction, they will typically be distalized, but this might not be desired. The C-tubes were comfortable for the patient throughout the entire orthodontic treatment and were easily removed with a minor incision.
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DISCUSSION
Recent advances in cone-beam computed tomography and computer-aided design/computer-aided manufacturing (CAD/CAM) technology have enabled a variety of schemes for virtual diagnosis, treatment planning, and model surgery.12-15 Sachdeva16 suggested that computer-aided 3D technology could provide 3D tools for diagnosis, monitoring, and patient communication,
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Fig 7. A, The miniplate can be slid along the horizontal wire for an easy incision; B and C, a minimal incision is made with a number 15 scalpel blade, guided by the incision positioning sleeve; D-F, the positioning sleeve is removed after the incision.
Fig 8. A, After the incision, the positioning sleeve is cut and removed. B, The miniplate is flipped vertically, slipped into the incision, and placed on the underlying bone. C-F, The miniplate is stably positioned, and the screws are drilled and fixated at the desired positions with no slippage.
as well as customized orthodontic treatment by precisely positioning the brackets. Son et al17 showed the possibility of virtual orthodontic treatment systems and suggested that more predictable tooth movements could be achieved if treatment is planned with a 3D virtual transfer jig fabricated from computer-simulated tooth
movements. According to Choi et al,14 the procedures for 3D virtual model surgery consist of creation of the 3D virtual dental casts, replacement of the dentition in the 3D computed tomography data with the 3D virtual dental casts, repositioning of the 3D virtual dental casts, and fabrication of the real surgical wafers using the
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Fig 9. A-C, All screws are fixated, and the guide is removed by slipping out the steel wire axle from the guide. D, Minimal sutures were required to close the incision area. The miniplate is buried under the mucosa at the mucogingival junction, and the C-tube part of the device is exposed for access to skeletal anchorage.
Fig 10. The postoperative cone-beam computed tomography images were reviewed, and no complication was observed.
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Fig 11. I-type C-tube application in the mandibular anterior area: A, adapation to clinical site; B, incision; C, positioning sleeve removal; D, placement of miniplate anchoring screws; E, guide removal; F, suture.
stereolithographic technique. As reported in the studies mentioned above, 3D CAD/CAM technology has become a new and powerful tool in orthodontics.18,19 Our goal was to accurately locate and fixate the miniplate as planned by the orthodontist. Other methods have been reported: eg, a simple customized surgical guide for the orthodontic miniplate with a tube was introduced by Paek et al.7 Although it was helpful, this previous guide was technique sensitive because the embedded positioning wire had some error potential, such that when the patient closed the mandibular teeth on the silicone material, the wire guide could move. Stereolithographic resin is not flexible, so this eliminates that concern. Soft material is not as accurate as the stereolithography resin. Whereas Paek et al's previously reported guide required laboratory work by the orthodontist, the technique described here is more convenient, since the laboratory work is done remotely by CAD/CAM. Virtual design of the stereolithographic surgical guide enables both the orthodontist and the surgeon to accurately predetermine the correct position for the miniplate. Use of the surgical guide introduced in this study can allow the clinician to accurately plan a safe location for the miniplate with firm and stable placement. The guide adapts to the buccal and occlusal aspects of the tooth precisely. Besides providing a firm location for the miniplate, the guide also has a scalpel guide for the incision. Before proceeding, the clinician can verify that the miniplate's screw holes match the incision location. With this technique, a large tissue flap is not necessary. The guide is
keyed to the occlusal surface, and the patient holds the guide in place by closing his or her teeth on its occlusal pad. In this report, we have introduced a C-tube guide planned with computer software (Orapix) and fabricated remotely by stereolithography. A new approach using conventional 2D cephalograms for a 3D approach was used. The recently introduced software uses 2D lateral and posteroanterior cephalograms and 3D virtual dental models. Because this program can combine 2D cephalograms with 3D virtual dental casts, it is called “2.5D software.” This program is useful because it is inappropriate to take 3D computed tomography scans for all patients. High cost and radiation exposure from 3D computed tomography scans are issues.9,20 Therefore, the 2.5D software can be regarded as a low-exposure and effective alternative to 3D software with cone-beam computed tomography. CONCLUSIONS
To confidently and safely place a miniplate with screw fixation, a simple customized placement guide for the orthodontic miniplate was introduced. The Orapix system provides extremely accurate and stable surgical guide positioning, thanks to CAD/CAM technology. The use of a custom-made, rigid guide when placing a miniplate could minimize complications such as vertical mislocation or slippage of the miniplate during placement. In-office laboratory procedures are reduced because of virtual planning and stereolithography; thus, the requirement for extremely careful technique is minimized.
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ACKNOWLEDGMENTS
We thank Soon-Yong Kwon for manuscript editing and Suk-Jin Kang, technical manager of Orapix, for his technical assistance during manuscript preparation.
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