The Use of Virtual Models to Estimate the Amount of Grafting Material: A Case Study Richard Zimmermann, DDS1/Stefanie Seitz, DDS2/Ulysses Vargas, MS3 The authors present a case study in which a virtual model was created from a patient’s cone beam computed tomographic scans that simulated a dentoalveolar defect associated with periapical pathosis. With the information provided by the virtual model, the tooth was extracted, and both defect and alveolus were virtually grafted. The virtual amount calculated was similar to the amount used in the actual site. Int J Oral Maxillofac Implants 2015;30:e43–e44. doi: 10.11607/jomi.4101 Key words: cone beam computed tomography, grafting material, virtual grafting, virtual models
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one beam computed tomography (CBCT) provides volumetric images of a patient that can be used to create realistic three-dimensional virtual models.1 It has been shown that these virtual models provide a surgeon with realistic and accurate models for diagnosis and treatment planning.2,3 More recently, virtual models were imported into commercial computer-aided design/computer-assisted manufacture software to design block grafts for augmentation. These designs were exported into a computer numeric control milling unit, which milled the graft out of a porous hydroxyapatite block.4 While the aforementioned articles address the application of current technology for larger, more complex dentoalveolar surgeries, virtual models can also be of benefit for simpler reconstructions. Particulate bone graft material is available in varying volumes, from 0.25 to 2.0 mL. When performing an augmentation procedure, it can be difficult to estimate the volume of material that will be needed. The use of an accurate virtual model that calculates the volume required for a given augmentation would eliminate unnecessary waste of grafting material. The following case illustrates
1 Assistant
Clinical Professor and Director of Digital Dentistry Program, Department of Comprehensive Dentistry, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. 2 Assistant Clinical Professor and Assistant Director of Digital Dentistry Program, Department of Comprehensive Dentistry, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. 3Student, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. Correspondence to: Dr Richard Zimmerman, Comprehensive Dentistry, UTHSCSA Dental School, 7703 Floyd Curl Drive - MC 7914, San Antonio, TX 78229, USA. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
the use of implant planning software to estimate the volume of grafting material needed prior to surgery.
CASE PRESENTATION A 58-year-old woman presented to the predoctoral clinic at the University of Texas, San Antonio, with a chief complaint of a fractured maxillary premolar. Clinical and radiographic examination revealed that the contralateral premolar had a large radiolucency associated with past endodontic therapy (Fig 1). The patient opted to have both premolars extracted and replaced with dental implants, so she was sent to the radiology department for CBCT. The imaging data were imported into implant planning software (coDiagnostix 9.2, DWOS) for evaluation of the site and generation of a virtual model. The software contains a section called “Segmentations” that removes artifacts and designs the virtual model (Fig 2). It is within Segmentation that various tools were used to virtually extract the tooth and graft the defect (Fig 3). The software calculated that 0.42 mL of grafting material was needed to fill both the defect and tooth socket (Fig 4). The height of the defect, as measured from the most apical portion to the most cervical, was 8.8 mm. It was noted on the virtual model that a thin, narrow bridge of buccal bone remained occlusal to the defect, which could be easily fractured on tooth removal. The tooth was carefully removed with periotomes without fracturing the buccal plate. The architecture of the defect closely resembled that of the virtual model (Fig 5). After debridement of the periapical defect, demineralized ground cortical bone allograft (Straumann) was placed and covered by a collagen membrane (Bio-mend Extend, Zimmer) (Fig 6). Because the virtual model had estimated 0.42 mL of graft would be needed, a 0.5-mL container was ordered. After grafting was complete, a small amount of graft material was left (Fig 7). The International Journal of Oral & Maxillofacial Implants e43
© 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
Zimmermann et al
Fig 1 Radiograph appointment.
taken
at
initial
Fig 2 Virtual model created from CBCT scans.
Fig 3 Virtual augmentation of defect (yellow).
Fig 4 Virtual model of augmentation.
Fig 5 Dentoalveolar defect.
Fig 6 Site after grafting.
Several publications have discussed the use of computer-aided design/computer-assisted manufacture software to prepare block grafts prior to surgery to eliminate the time spent modifying stock blocks during surgery.5,6 This case illustrates a method to estimate the volume of grafting material needed for a simple grafting procedure; however, it could also be used for larger augmentations. Although controlled studies are needed to determine the accuracy of this method, this case provides a glimpse into what may lie ahead in terms of virtual models and grafting procedures.
ACKNOWLEDGMENTS The authors would like to thank Dental Services Group and the UTHSCSA Graduate Periodontic Program for their support. The authors reported no conflicts of interest related to this study.
Fig 7 Remaining grafting material.
REFERENCES 1. Plooij JM, Maal TJ, Haers P, Borstlap WA, Kuijpers-Jagtman AM, Bergé SJ. Digital three-dimensional image fusion processes for planning and evaluating orthodontics and orthognathic surgery. A systematic review. Int J Oral Maxillofac Surg 2011;40:341–352. 2. Shqaidef A, Ayoub AF, Khambay BS. How accurate are rapid prototyped (RP) final orthognathic surgical wafers? A pilot study. Br J Oral Maxillofac Surg 2014;52:609–614. 3. Hernández-Alfaro F, Guijarro-Martínez R. New protocol for threedimensional surgical planning and CAD/CAM splint generation in orthognathic surgery: An in vitro and in vivo study. Int J Oral Maxillofac Surg 2013;42:1547–1556. 4. Figliuzzi M, Mangano FG, Fortunato L, et al. Vertical ridge augmentation of the atrophic posterior mandible with custom-made, computer-aided design/computer-aided manufacturing porous hydroxyapatite scaffolds. J Craniofac Surg 2013;24:856–859. 5. Mangano F, Macchi A, Shibli JA, et al. Maxillary ridge augmentation with custom-made CAD/CAM scaffolds. A 1-year prospective study on 10 patients. J Oral Implantol 2014;40:561–569. 6. Rodby KA, Turin S, Jacobs RJ, et al. Advances in oncologic head and neck reconstruction: Systematic review and future considerations of virtual surgical planning and computer aided design/computer aided modeling. J Plast Reconstr Aesthet Surg 2014;67:1171–1185.
e44 Volume 30, Number 3, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
C
one beam computed tomography (CBCT) provides volumetric images of a patient that can be used to create realistic three-dimensional virtual models.1 It has been shown that these virtual models provide a surgeon with realistic and accurate models for diagnosis and treatment planning.2,3 More recently, virtual models were imported into commercial computer-aided design/computer-assisted manufacture software to design block grafts for augmentation. These designs were exported into a computer numeric control milling unit, which milled the graft out of a porous hydroxyapatite block.4 While the aforementioned articles address the application of current technology for larger, more complex dentoalveolar surgeries, virtual models can also be of benefit for simpler reconstructions. Particulate bone graft material is available in varying volumes, from 0.25 to 2.0 mL. When performing an augmentation procedure, it can be difficult to estimate the volume of material that will be needed. The use of an accurate virtual model that calculates the volume required for a given augmentation would eliminate unnecessary waste of grafting material. The following case illustrates
1 Assistant
Clinical Professor and Director of Digital Dentistry Program, Department of Comprehensive Dentistry, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. 2 Assistant Clinical Professor and Assistant Director of Digital Dentistry Program, Department of Comprehensive Dentistry, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. 3Student, University of Texas Health Science Center, School of Dentistry, San Antonio, Texas, USA. Correspondence to: Dr Richard Zimmerman, Comprehensive Dentistry, UTHSCSA Dental School, 7703 Floyd Curl Drive - MC 7914, San Antonio, TX 78229, USA. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
the use of implant planning software to estimate the volume of grafting material needed prior to surgery.
CASE PRESENTATION A 58-year-old woman presented to the predoctoral clinic at the University of Texas, San Antonio, with a chief complaint of a fractured maxillary premolar. Clinical and radiographic examination revealed that the contralateral premolar had a large radiolucency associated with past endodontic therapy (Fig 1). The patient opted to have both premolars extracted and replaced with dental implants, so she was sent to the radiology department for CBCT. The imaging data were imported into implant planning software (coDiagnostix 9.2, DWOS) for evaluation of the site and generation of a virtual model. The software contains a section called “Segmentations” that removes artifacts and designs the virtual model (Fig 2). It is within Segmentation that various tools were used to virtually extract the tooth and graft the defect (Fig 3). The software calculated that 0.42 mL of grafting material was needed to fill both the defect and tooth socket (Fig 4). The height of the defect, as measured from the most apical portion to the most cervical, was 8.8 mm. It was noted on the virtual model that a thin, narrow bridge of buccal bone remained occlusal to the defect, which could be easily fractured on tooth removal. The tooth was carefully removed with periotomes without fracturing the buccal plate. The architecture of the defect closely resembled that of the virtual model (Fig 5). After debridement of the periapical defect, demineralized ground cortical bone allograft (Straumann) was placed and covered by a collagen membrane (Bio-mend Extend, Zimmer) (Fig 6). Because the virtual model had estimated 0.42 mL of graft would be needed, a 0.5-mL container was ordered. After grafting was complete, a small amount of graft material was left (Fig 7). The International Journal of Oral & Maxillofacial Implants e43
© 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
Zimmermann et al
Fig 1 Radiograph appointment.
taken
at
initial
Fig 2 Virtual model created from CBCT scans.
Fig 3 Virtual augmentation of defect (yellow).
Fig 4 Virtual model of augmentation.
Fig 5 Dentoalveolar defect.
Fig 6 Site after grafting.
Several publications have discussed the use of computer-aided design/computer-assisted manufacture software to prepare block grafts prior to surgery to eliminate the time spent modifying stock blocks during surgery.5,6 This case illustrates a method to estimate the volume of grafting material needed for a simple grafting procedure; however, it could also be used for larger augmentations. Although controlled studies are needed to determine the accuracy of this method, this case provides a glimpse into what may lie ahead in terms of virtual models and grafting procedures.
ACKNOWLEDGMENTS The authors would like to thank Dental Services Group and the UTHSCSA Graduate Periodontic Program for their support. The authors reported no conflicts of interest related to this study.
Fig 7 Remaining grafting material.
REFERENCES 1. Plooij JM, Maal TJ, Haers P, Borstlap WA, Kuijpers-Jagtman AM, Bergé SJ. Digital three-dimensional image fusion processes for planning and evaluating orthodontics and orthognathic surgery. A systematic review. Int J Oral Maxillofac Surg 2011;40:341–352. 2. Shqaidef A, Ayoub AF, Khambay BS. How accurate are rapid prototyped (RP) final orthognathic surgical wafers? A pilot study. Br J Oral Maxillofac Surg 2014;52:609–614. 3. Hernández-Alfaro F, Guijarro-Martínez R. New protocol for threedimensional surgical planning and CAD/CAM splint generation in orthognathic surgery: An in vitro and in vivo study. Int J Oral Maxillofac Surg 2013;42:1547–1556. 4. Figliuzzi M, Mangano FG, Fortunato L, et al. Vertical ridge augmentation of the atrophic posterior mandible with custom-made, computer-aided design/computer-aided manufacturing porous hydroxyapatite scaffolds. J Craniofac Surg 2013;24:856–859. 5. Mangano F, Macchi A, Shibli JA, et al. Maxillary ridge augmentation with custom-made CAD/CAM scaffolds. A 1-year prospective study on 10 patients. J Oral Implantol 2014;40:561–569. 6. Rodby KA, Turin S, Jacobs RJ, et al. Advances in oncologic head and neck reconstruction: Systematic review and future considerations of virtual surgical planning and computer aided design/computer aided modeling. J Plast Reconstr Aesthet Surg 2014;67:1171–1185.
e44 Volume 30, Number 3, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
