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A Comparison of Mandibular Distraction Vector Effect on Airway and Mandibular Volumes in Pierre Robin Sequence
Oral Abstract Track 1 CLEFT, RECONSTRUCTION, TMJ October 2, 2015, 7:30 AM-9:30 AM
Deproteinized Bovine Bone Graft in Maxillary Alveolar Cleft Reconstruction T. I. Elfaramawi: Faculty of Dentistry, Cairo University, M. I. Faramawey, M. M. Dahaba, M. M. Hakam Though alveolar grafting continues to be a viable treatment regimen, its associated protocols and techniques are many and varied. The present study was conducted to evaluate the use of deproteinized bovine bone xenograft mixed with autogenous mandibular symphyseal bone graft in secondary maxillary alveolar cleft reconstruction compared to the gold standard anterior iliac crest autogenous graft. 10 patients (mean age 9.3years 1.33) with unilateral maxillary alveolar cleft defect requiring secondary alveolar cleft grafting were included in this study. Patients were selected from the outpatient clinic, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University. The study was conducted from June 2012 till February 2013. Patients were divided randomly into 2 equal groups. Group A received the gold standard anterior iliac crest graft. Group B received mandibular symphyseal bone mixed with deproteinized bovine bone in a 1:1 ratio. For each patient, 3 CBCT scans were ordered: preoperatively, immediately postoperatively and 6 months postoperatively. Volumetric and densitometric measurements were made using the Mimics[1] software. Data were collected and statistical analysis was performed using SPSS (Statistical package for the social sciences)[2]. Data were represented as mean standard deviation. Paired sample student t-test was used to compare each pair of the studied variables within the studied group of patients. Independent sample t test was used to compare variables between the two studied groups. The test result was considered statistically significant if the P- value was equal to or less than 0.05. Results showed the percentage of defect filling immediately postoperatively to be 90.8 9.2% for Group A and 94.2 4.3% for Group B, while percentage of defect filling 6 months postoperatively was 86.6 10.0% for Group A and 88.4 2.8% for Group B. Comparison of the 2 groups regarding the percentage of defect filling by the graft immediately postoperatively and at 6 months showed no statistical significant difference with a P-value of 0.483 and 0.736 respectively. Comparison of the percentage of graft resorption between the 2 groups also showed no statistical significant difference. (P-value 0.704) Similarly, comparison of graft density between Group A and Group B immediately postoperatively (P-value 0.52) and after 6 months (P-value 0.81) showed no statistical significant
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difference. Moreover, comparison of change in graft density between both groups showed no statistical significant difference. (P-value 0.949) From the current study it was concluded that composite symphyseal bone mixed with deproteinized bovine bone in a 1:1 ratio gives comparable results to the gold standard anterior iliac crest graft in secondary alveolar cleft reconstruction. References: 1. Benlidayi ME, Tatli U, Kurkcu M, Uzel A, Oztunc H: Comparison of Bovine-Derived Hydroxyapatite and Autogenous Bone for Secondary Alveolar Bone Grafting in Patients With Alveolar Clefts. J Oral MaxillofacSurg 70:95-102, 2012. 2. Oberoi S, Chigurupati R, Gill P, Hoffman WY, Vargervik K: Volumetric assessment of secondary alveolar bone grafting using cone beam computed tomography. The Cleft palate-craniofacial journal. 46(5): 503–11, 2009. [1] Version 10.01, Materialize, Leuven, Belgium [2] version 20, IBM corp., U.S.A
A Comparison of Mandibular Distraction Vector Effect on Airway and Mandibular Volumes in Pierre Robin Sequence E. G. Zellner: Yale University School of Medicine, J. M. Mhlaba, R. R. Reid, D. M. Steinbacher Background: The goal of mandibular distraction in Pierre Robin Sequence is to maximally expand the oropharyngeal airway. It has been hypothesized that a steep oblique distraction vector may allow greater airway enlargement. This study compares sagittal versus oblique vectors to assess vector correlation with eventual airway volume. Methods: IRB approval was obtained from two institutions. Micrognathic infants who underwent mandibular distraction with pre- and post-op CT scans were included. Demographic, diagnostic, perioperative data and distraction protocol, including vector relative to the mandibular border , were recorded. Airway and mandibular volumes were measured using Mimics (Leuven, Belgium). Statistics involved two-tailed t-test and Pearson correlation. Results: 40 CT scans were analyzed. Mean distraction age was 41 days with devices maintained 82 days on average. Vector axis from the inferior mandibular border was # 10 degrees in group 1 (n=10), and > 10 degrees in group 2 (n=10). Airway and mandibular volumes, minimal airway area, and PAS distance were all significantly increased following distraction. Inter-group analysis showed no difference in airway measurements (no vector correlation to airway). However, mandibular volume was increased in the oblique group, approaching significance (p=0.07), attributable to greater ramus volume (p=0.03),
AAOMS 2015
Oral Abstract Track 1 with similar body volumes between groups. Clinically, patients had improved sleep studies post-distraction. Conclusions: Significant airway enlargement occurs following mandibular distraction. An oblique vector does not result in a greater volumetric airway increase compared to sagittal elongation, but does confer modest increase in ramus volume. Successful clinical outcomes are achieved using both trajectories. Further work will assess vector influence on overall mandibular morphology and presence/persistence of open bite. References: 1. Steinbacher DM, Kaban LB, Troulis MJ. Mandibular advancement by distraction osteogenesis for tracheostomy-dependent children with severe micrognathia. J Oral Maxillofac Surg. 2005; 63(8):1072–9. doi:10.1016/j.joms.2005.04.013. 2. Hernandez-Alfaro F, Guijarro-Martı´nez R, Mareque-Bueno J. Effect of mono- and bimaxillary advancement on pharyngeal airway volume: cone-beam computed tomography evaluation. J Oral Maxillofac Surg. 2011;69(11):e395–400. doi:10.1016/j.joms.2011.02.138. 3. Roth DA, Gosain AK, McCarthy JG, Stracher MA, Lefton DR, Grayson BH. A CT scan technique for quantitative volumetric assessment of the mandible after distraction osteogenesis. Plast Reconstr Surg. 1997;99(April):1237–1247; discussion 1248–1250. doi:10.1097/ 00006534-199704001-00006.
AV loop model, and investigating the efficacy of inducing collateral vessels. In this study, four models (extrinsic control, intrinsic control, arteriogenesis and AV loop) were investigated to identify the optimal strategy to vascularize bioceramic scaffolds. Following in vivo periods of 2 and 4 weeks, tissue specimens were analyzed histologically (immunohistochemistry) to quantify the density of blood vessels, and radiographically (micro-computed tomography) to determine the degree of graft resorption. The monetite scaffolds were manufactured through rapid-prototyping and featured two designs (Figure 1). The first contains a central lumen of constant diameter for the control, Angiogenesis and AV loop groups. The second design retains a tapering central lumen to obstruct the artery distally - this was used in the arteriogenesis group. The femoral vasculature was utilized, and a total of 30 Wistar rats were operated on (Figure 2). At both 2- and 4-week time points, the arteriogenesis model displayed a greater density of blood vessels.
Axial Vascularization of Bioceramic Scaffolds for Segmental Bone Defects H. S. Mangat: McGill University, J. Barralet, N. Makhoul The current gold standard for the reconstruction of critical-sized maxillofacial defects is the transfer of vascularized bone flaps. These flaps have significant limitations including a size mismatch to the recipient site as well as donor site morbidity, leading to compromised facial aesthetics and oral/masticatory function. Bone tissue engineering presents a promising alternative to the current reconstruction techniques. However, tissue engineered constructs have thus far failed to make a significant clinical translation, largely due to a lack of robust strategies to generate patent vascularization (1). In order to generate vessels large enough to perfuse clinically relevant scaffolds, two techniques exist: vessel grafting (as in the AV Loop model) or collateralization (also known as arteriogenesis). Much of what is known regarding collateralization is related to ischemic cardiac and brain injuries. In this literature, full or partial vessel occlusion of blood vessels generates a hypoxic environment conducive to the expansion of vestigial collateral vessels. The severity of occlusion is proportional to the intensity of arteriogenesis. Bone regeneration of segmental bone defects has not yet implemented this knowledge. Only the arteriovenous (AV) loop model investigated by independent German and US research groups, has displayed the necessary pro-angiogenic properties to repair critical-sized defects (2). Therefore, the ideal strategy to vascularize large scaffolds must induce both arteriogenesis and angiogenesis. The aim of this study is to optimize vascularization of a complex bioceramic scaffold by improving the current AAOMS 2015
Figure 1. Monetite scaffolds including either a tapering (A) or nontapering central channel (B).
Figure 2. Orientation of the implanted scaffolds as either encompassing the artery, or near the artery (extrinsic control group).
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Deproteinized Bovine Bone Graft in Maxillary Alveolar Cleft Reconstruction T. I. Elfaramawi: Faculty of Dentistry, Cairo University, M. I. Faramawey, M. M. Dahaba, M. M. Hakam Though alveolar grafting continues to be a viable treatment regimen, its associated protocols and techniques are many and varied. The present study was conducted to evaluate the use of deproteinized bovine bone xenograft mixed with autogenous mandibular symphyseal bone graft in secondary maxillary alveolar cleft reconstruction compared to the gold standard anterior iliac crest autogenous graft. 10 patients (mean age 9.3years 1.33) with unilateral maxillary alveolar cleft defect requiring secondary alveolar cleft grafting were included in this study. Patients were selected from the outpatient clinic, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University. The study was conducted from June 2012 till February 2013. Patients were divided randomly into 2 equal groups. Group A received the gold standard anterior iliac crest graft. Group B received mandibular symphyseal bone mixed with deproteinized bovine bone in a 1:1 ratio. For each patient, 3 CBCT scans were ordered: preoperatively, immediately postoperatively and 6 months postoperatively. Volumetric and densitometric measurements were made using the Mimics[1] software. Data were collected and statistical analysis was performed using SPSS (Statistical package for the social sciences)[2]. Data were represented as mean standard deviation. Paired sample student t-test was used to compare each pair of the studied variables within the studied group of patients. Independent sample t test was used to compare variables between the two studied groups. The test result was considered statistically significant if the P- value was equal to or less than 0.05. Results showed the percentage of defect filling immediately postoperatively to be 90.8 9.2% for Group A and 94.2 4.3% for Group B, while percentage of defect filling 6 months postoperatively was 86.6 10.0% for Group A and 88.4 2.8% for Group B. Comparison of the 2 groups regarding the percentage of defect filling by the graft immediately postoperatively and at 6 months showed no statistical significant difference with a P-value of 0.483 and 0.736 respectively. Comparison of the percentage of graft resorption between the 2 groups also showed no statistical significant difference. (P-value 0.704) Similarly, comparison of graft density between Group A and Group B immediately postoperatively (P-value 0.52) and after 6 months (P-value 0.81) showed no statistical significant
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difference. Moreover, comparison of change in graft density between both groups showed no statistical significant difference. (P-value 0.949) From the current study it was concluded that composite symphyseal bone mixed with deproteinized bovine bone in a 1:1 ratio gives comparable results to the gold standard anterior iliac crest graft in secondary alveolar cleft reconstruction. References: 1. Benlidayi ME, Tatli U, Kurkcu M, Uzel A, Oztunc H: Comparison of Bovine-Derived Hydroxyapatite and Autogenous Bone for Secondary Alveolar Bone Grafting in Patients With Alveolar Clefts. J Oral MaxillofacSurg 70:95-102, 2012. 2. Oberoi S, Chigurupati R, Gill P, Hoffman WY, Vargervik K: Volumetric assessment of secondary alveolar bone grafting using cone beam computed tomography. The Cleft palate-craniofacial journal. 46(5): 503–11, 2009. [1] Version 10.01, Materialize, Leuven, Belgium [2] version 20, IBM corp., U.S.A
A Comparison of Mandibular Distraction Vector Effect on Airway and Mandibular Volumes in Pierre Robin Sequence E. G. Zellner: Yale University School of Medicine, J. M. Mhlaba, R. R. Reid, D. M. Steinbacher Background: The goal of mandibular distraction in Pierre Robin Sequence is to maximally expand the oropharyngeal airway. It has been hypothesized that a steep oblique distraction vector may allow greater airway enlargement. This study compares sagittal versus oblique vectors to assess vector correlation with eventual airway volume. Methods: IRB approval was obtained from two institutions. Micrognathic infants who underwent mandibular distraction with pre- and post-op CT scans were included. Demographic, diagnostic, perioperative data and distraction protocol, including vector relative to the mandibular border , were recorded. Airway and mandibular volumes were measured using Mimics (Leuven, Belgium). Statistics involved two-tailed t-test and Pearson correlation. Results: 40 CT scans were analyzed. Mean distraction age was 41 days with devices maintained 82 days on average. Vector axis from the inferior mandibular border was # 10 degrees in group 1 (n=10), and > 10 degrees in group 2 (n=10). Airway and mandibular volumes, minimal airway area, and PAS distance were all significantly increased following distraction. Inter-group analysis showed no difference in airway measurements (no vector correlation to airway). However, mandibular volume was increased in the oblique group, approaching significance (p=0.07), attributable to greater ramus volume (p=0.03),
AAOMS 2015
Oral Abstract Track 1 with similar body volumes between groups. Clinically, patients had improved sleep studies post-distraction. Conclusions: Significant airway enlargement occurs following mandibular distraction. An oblique vector does not result in a greater volumetric airway increase compared to sagittal elongation, but does confer modest increase in ramus volume. Successful clinical outcomes are achieved using both trajectories. Further work will assess vector influence on overall mandibular morphology and presence/persistence of open bite. References: 1. Steinbacher DM, Kaban LB, Troulis MJ. Mandibular advancement by distraction osteogenesis for tracheostomy-dependent children with severe micrognathia. J Oral Maxillofac Surg. 2005; 63(8):1072–9. doi:10.1016/j.joms.2005.04.013. 2. Hernandez-Alfaro F, Guijarro-Martı´nez R, Mareque-Bueno J. Effect of mono- and bimaxillary advancement on pharyngeal airway volume: cone-beam computed tomography evaluation. J Oral Maxillofac Surg. 2011;69(11):e395–400. doi:10.1016/j.joms.2011.02.138. 3. Roth DA, Gosain AK, McCarthy JG, Stracher MA, Lefton DR, Grayson BH. A CT scan technique for quantitative volumetric assessment of the mandible after distraction osteogenesis. Plast Reconstr Surg. 1997;99(April):1237–1247; discussion 1248–1250. doi:10.1097/ 00006534-199704001-00006.
AV loop model, and investigating the efficacy of inducing collateral vessels. In this study, four models (extrinsic control, intrinsic control, arteriogenesis and AV loop) were investigated to identify the optimal strategy to vascularize bioceramic scaffolds. Following in vivo periods of 2 and 4 weeks, tissue specimens were analyzed histologically (immunohistochemistry) to quantify the density of blood vessels, and radiographically (micro-computed tomography) to determine the degree of graft resorption. The monetite scaffolds were manufactured through rapid-prototyping and featured two designs (Figure 1). The first contains a central lumen of constant diameter for the control, Angiogenesis and AV loop groups. The second design retains a tapering central lumen to obstruct the artery distally - this was used in the arteriogenesis group. The femoral vasculature was utilized, and a total of 30 Wistar rats were operated on (Figure 2). At both 2- and 4-week time points, the arteriogenesis model displayed a greater density of blood vessels.
Axial Vascularization of Bioceramic Scaffolds for Segmental Bone Defects H. S. Mangat: McGill University, J. Barralet, N. Makhoul The current gold standard for the reconstruction of critical-sized maxillofacial defects is the transfer of vascularized bone flaps. These flaps have significant limitations including a size mismatch to the recipient site as well as donor site morbidity, leading to compromised facial aesthetics and oral/masticatory function. Bone tissue engineering presents a promising alternative to the current reconstruction techniques. However, tissue engineered constructs have thus far failed to make a significant clinical translation, largely due to a lack of robust strategies to generate patent vascularization (1). In order to generate vessels large enough to perfuse clinically relevant scaffolds, two techniques exist: vessel grafting (as in the AV Loop model) or collateralization (also known as arteriogenesis). Much of what is known regarding collateralization is related to ischemic cardiac and brain injuries. In this literature, full or partial vessel occlusion of blood vessels generates a hypoxic environment conducive to the expansion of vestigial collateral vessels. The severity of occlusion is proportional to the intensity of arteriogenesis. Bone regeneration of segmental bone defects has not yet implemented this knowledge. Only the arteriovenous (AV) loop model investigated by independent German and US research groups, has displayed the necessary pro-angiogenic properties to repair critical-sized defects (2). Therefore, the ideal strategy to vascularize large scaffolds must induce both arteriogenesis and angiogenesis. The aim of this study is to optimize vascularization of a complex bioceramic scaffold by improving the current AAOMS 2015
Figure 1. Monetite scaffolds including either a tapering (A) or nontapering central channel (B).
Figure 2. Orientation of the implanted scaffolds as either encompassing the artery, or near the artery (extrinsic control group).
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