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Orthognathic Surgery Simulation Using Cadavers
Poster Session angle to the pterygoid plate in relation to the lateral maxillary sinus wall, the surface area of the lateral pterygoid plate (mm2), and bone density in Hounsfield Units (HU) at the pterygomaxillary junction, piriform rim, and zygomatic buttress. Of the 87 patients, 47 were females and 40 were males. Age ranged from 14-68 and the median age was 22. Fractures of the pterygoid plates occurred in 48% (N=42) of patients. Of those, 17% (N=7) had high pterygoid plate fracture and 83% (N=35) had low pterygoid plate fractures. Of the 7 cases with high pterygoid plate fracture, 3 occurred with an oscillating saw, 2 with osteotome and 2 with manual down fracture. Mean of the reference points were done on all 87 patients. Table I Anatomical mean values of fracture population Reference Points Piriform-Base Line Lateral Plate Medial Plate A-P Thickness PMJ M-L Thickness PMJ Lateral Wall-PMJ Angle of PMJ Area of Lateral Wall (mm2) HU PMJ HU Zygomatic Buttress HU Piriform
R
L
35.1 11.2 9.0 3.7 7.5 31.2 100.6 211.7 352.5 486.7 735.7
34.9 11.3 8.8 4.0 7.0 31.4 94.3 205.3 252.2 508.7 729.7
Table II Anatomical mean values of non-fracture population Reference Points Piriform-Base Line Lateral Plate Medial Plate A-P Thickness PMJ M-L Thickness PMJ Lateral Wall-PMJ Angle of PMJ Area of Lateral Wall (mm2) HU PMJ HU Zygomatic Buttress HU Piriform
R
L
34.8 12.2 9.0 5.0 7.2 31.2 99.9 208.1 311.9 491.3 713.8
34.6 11.8 9.5 4.3 6.8 30.9 96.1 204.5 277.7 438.1 723.9
References: 1. Precious DS: Pterygoid Plate Fracture in Le Fort 1 Osteotomy With and Without Pterygoid Chisel: A Computer Tomography Scan Evaluation of 58 Patients. J Oral Maxillofacial Surgery 51:151-153, 1993 2. Fonseca RJ: Oral and Maxillofacial Surgery. Volume 2:232-248.
POSTER 38 Orthognathic Surgery in the Mobius Syndrome Patient R. M. Ulma: University of California, Los Angeles, School of Dentistry, S. L. Ratner, M. Wilson Mobius syndrome has been well described in the literature since von Graffe’s seminal report in 1880. It is defined by the congenital, non-progressive palsy of the sixth and seventh cranial nerves, with occasional involvement of other cranial nerves. Facial and abducens nerve involvement can be unilateral or bilateral, and paralysis can be partial or complete. The incidence of Mobius syndrome has not been determined, although it is estimated to occur in 1:50,000 live births, with an equal gender distribution. The pathophysiology of Mobius syndrome is not completely understood. It is attributed to brainstem dysfunction, caused by agenesis of the involved cranial nerve nuclei, prompted by either environmental or genetic causes. Despite its rarity, the dental and maxillofacial management of the Mobius patient warrants attention. The management of soft tissue manifestations in these patients, particularly treatment of facial muscle paralysis, is well described. The treatment of other common maxillofacial abnormalities, however, has not been studied as extensively. A recent search of the literature on the hard tissue management of Mobius patients afforded only three case reports on a total of four patients. Three patients who underwent dentofacial deformity correction with orthognathic surgery are presented. This is the largest case series on orthognathic surgery in the Mobius syndrome patient, performed at one institution by one surgeon. Common dental and maxillofacial features of the Mobius patient and pertinent surgical treatment planning recommendations are also discussed.
POSTER 39 The incidence of untoward pterygoid plate fracture has been reported to be as high as 87%.1 Pterygoid plate fracture happens nearly 50% of the time and 17% were high-level fractures. Based on our data, neither surgical technique nor anatomical variability played a significant contributing role to pterygoid plate fracture pattern or incidence. Nevertheless, understanding the etiology of pterygoid plate fracture may help decrease the occurrence of neurological-ophthalmologic complications and their associated morbidities. e-62
Orthognathic Surgery Simulation Using Cadavers M. D. Walker: Hospital of the University of Pennsylvania, J. Chou, D. C. Stanton Historically, clinical training in orthognathic surgery for oral surgery residents has been gained through performing surgery on actual patients in the operating room. On the job training for these specialized surgical techniques has the potential for leading to less than ideal AAOMS 2013
Poster Session outcomes. Recently surgical simulation techniques have been shown to benefit trainees. In 2010 Tucker, et al used virtual reality surgical simulation repetitively until reaching specific target criteria to significantly improve subsequent operating room performance of residents. In 2012, Kienle et al looked at the utility of using cadavers in orthognathic surgery training. OMFS residents participated in a cadaver course in orthognathics and then were surveyed regarding the training. Residents felt the cadaver lab was of benefit and improved their surgical understanding and performance with respect to orthognathic surgery. The current study was designed to gather data regarding oral surgery residents experience with simulated orthognathic surgery training and expand the amount of information available about residents attitudes regarding the utility and benefit of receiving simulated training in orthognathic surgery. An online survey was emailed to all OMFS residents and interns who had an email listed in the AAOMS directory. A study protocol was developed and approved by the University of Pennsylvania IRB to investigate the perceived attitudes of participants in the survey. The questionnaire consisted of 8 demographic questions to assess participants experience in performing orthognathic surgery in the OR and to determine what types of orthognathic surgery training they have received outside of the OR. This was followed by a series of 10 statements about the use of cadavers in orthognathic surgery training that were each rated on a 10 point scale on level of agreement. All participants were invited to fill out the online survey after being presented an online informed consent. The survey accepted responses for up to one month. Out of 791 residents and interns invited to participate, 180 (23%) accepted the informed consent and responded to the survey. Respondents were from all years of training in both 4 and 6 year programs. Results were descriptively analyzed. Over half of respondents were from 6 year programs (54%) with the remainder from 4 year programs. 34% had performed more than 10 orthognathic cases in the role of junior surgeon. 26.5% of respondents had never operated as junior surgeon during an orthognathic case. 63.5% had never been involved in cadaver training for orthognathic surgery while 36.5% had at least once. 53.5% had been involved in some type of orthognathic training other than on cadavers, including computer simulation, model surgery, or saw bones. In general, the residents felt the cadaver lab was a realistic simulation of clinical orthognathic procedures (average 7.6/10), and that the cadaver training improved their clinical understanding of the procedures (average 8.5/10). The majority of those polled disagreed with the statement that similar or superior surgical knowledge could be attained on a computer simulation of orthognathic surgery as on cadavers (average 4.4/10). Most of those surveyed said they would recomAAOMS 2013
mend the training to all oral surgery residents (average 8.6/10). In conclusion, residents who have experienced orthognathic surgery training in the cadaver lab felt that it was worthwhile and improved their clinical understanding of the performed procedures. Surgical simulation, specifically in the cadaver lab has the potential to be a promising and effective tool for training oral surgery residents in orthognathic surgery. References: 1. Tucker, et al: Comparison of actual surgical outcomes and 3-dimensional surgical simulations. J Oral Maxillofac Surg 68:10, 2010. 2. Kienle MP, Chou JC, Stanton DCS: Cadaver Training in the Education of Orthognathic Surgery. J Oral Maxillofac Surg 70:9, Supp 2, 2012.
POSTER 40 Randomized Prospective Clinical Trial on Use of Resorbable Screws in Fixating Bilateral Sagittal Split Osteotomies for Mandibular Advancement S. H. Yu: University of Washington, D. Bloomquist Statement of the Problem: The use of metal rigid fixation in maxillofacial surgery is now standard in trauma of the maxillofacial skeleton, orthognathic surgery and craniofacial surgery.1 Resorbable fixation material is an attractive option for those patients undergoing orthognathic surgery. Besides the obvious benefit of not having permanent implants, it decreases the possible need for surgical implant removal that will be an additional cost and risk to the patient.2 The purpose of this randomized prospective clinical trial is to compare resorbable screw fixation to titanium screw fixation in orthognathic surgical procedures. In particular, efficacy of resorbable screws will be tested in bilateral mandibular sagittal split osteotomies (BSSO), which are performed for correction of retrognathic mandible. Materials and Methods: A total of 101 patients with mandibular retrognathia who needed mandibular advancement were enrolled in this prospective randomized clinical trial. Patients were randomly assigned to one of two groups with different fixation systems. Patients in Group 1 (n = 51) received titanium screws (Stryker) and patients in Group 2 (n = 50) received resorbable screws (Inion CPS). Outcome measures were clinical evidence of relapse, incidence of infection/inflammation, need for post-operative elastic rubber band use, changes in pre- and post-operative maximal incisal opening and need for additional procedures. Method of Data Analysis: To compare differences between dichotomous variables, the Chi-square or the Fisher’s exact test was used. To test continuous variables,
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R
L
35.1 11.2 9.0 3.7 7.5 31.2 100.6 211.7 352.5 486.7 735.7
34.9 11.3 8.8 4.0 7.0 31.4 94.3 205.3 252.2 508.7 729.7
Table II Anatomical mean values of non-fracture population Reference Points Piriform-Base Line Lateral Plate Medial Plate A-P Thickness PMJ M-L Thickness PMJ Lateral Wall-PMJ Angle of PMJ Area of Lateral Wall (mm2) HU PMJ HU Zygomatic Buttress HU Piriform
R
L
34.8 12.2 9.0 5.0 7.2 31.2 99.9 208.1 311.9 491.3 713.8
34.6 11.8 9.5 4.3 6.8 30.9 96.1 204.5 277.7 438.1 723.9
References: 1. Precious DS: Pterygoid Plate Fracture in Le Fort 1 Osteotomy With and Without Pterygoid Chisel: A Computer Tomography Scan Evaluation of 58 Patients. J Oral Maxillofacial Surgery 51:151-153, 1993 2. Fonseca RJ: Oral and Maxillofacial Surgery. Volume 2:232-248.
POSTER 38 Orthognathic Surgery in the Mobius Syndrome Patient R. M. Ulma: University of California, Los Angeles, School of Dentistry, S. L. Ratner, M. Wilson Mobius syndrome has been well described in the literature since von Graffe’s seminal report in 1880. It is defined by the congenital, non-progressive palsy of the sixth and seventh cranial nerves, with occasional involvement of other cranial nerves. Facial and abducens nerve involvement can be unilateral or bilateral, and paralysis can be partial or complete. The incidence of Mobius syndrome has not been determined, although it is estimated to occur in 1:50,000 live births, with an equal gender distribution. The pathophysiology of Mobius syndrome is not completely understood. It is attributed to brainstem dysfunction, caused by agenesis of the involved cranial nerve nuclei, prompted by either environmental or genetic causes. Despite its rarity, the dental and maxillofacial management of the Mobius patient warrants attention. The management of soft tissue manifestations in these patients, particularly treatment of facial muscle paralysis, is well described. The treatment of other common maxillofacial abnormalities, however, has not been studied as extensively. A recent search of the literature on the hard tissue management of Mobius patients afforded only three case reports on a total of four patients. Three patients who underwent dentofacial deformity correction with orthognathic surgery are presented. This is the largest case series on orthognathic surgery in the Mobius syndrome patient, performed at one institution by one surgeon. Common dental and maxillofacial features of the Mobius patient and pertinent surgical treatment planning recommendations are also discussed.
POSTER 39 The incidence of untoward pterygoid plate fracture has been reported to be as high as 87%.1 Pterygoid plate fracture happens nearly 50% of the time and 17% were high-level fractures. Based on our data, neither surgical technique nor anatomical variability played a significant contributing role to pterygoid plate fracture pattern or incidence. Nevertheless, understanding the etiology of pterygoid plate fracture may help decrease the occurrence of neurological-ophthalmologic complications and their associated morbidities. e-62
Orthognathic Surgery Simulation Using Cadavers M. D. Walker: Hospital of the University of Pennsylvania, J. Chou, D. C. Stanton Historically, clinical training in orthognathic surgery for oral surgery residents has been gained through performing surgery on actual patients in the operating room. On the job training for these specialized surgical techniques has the potential for leading to less than ideal AAOMS 2013
Poster Session outcomes. Recently surgical simulation techniques have been shown to benefit trainees. In 2010 Tucker, et al used virtual reality surgical simulation repetitively until reaching specific target criteria to significantly improve subsequent operating room performance of residents. In 2012, Kienle et al looked at the utility of using cadavers in orthognathic surgery training. OMFS residents participated in a cadaver course in orthognathics and then were surveyed regarding the training. Residents felt the cadaver lab was of benefit and improved their surgical understanding and performance with respect to orthognathic surgery. The current study was designed to gather data regarding oral surgery residents experience with simulated orthognathic surgery training and expand the amount of information available about residents attitudes regarding the utility and benefit of receiving simulated training in orthognathic surgery. An online survey was emailed to all OMFS residents and interns who had an email listed in the AAOMS directory. A study protocol was developed and approved by the University of Pennsylvania IRB to investigate the perceived attitudes of participants in the survey. The questionnaire consisted of 8 demographic questions to assess participants experience in performing orthognathic surgery in the OR and to determine what types of orthognathic surgery training they have received outside of the OR. This was followed by a series of 10 statements about the use of cadavers in orthognathic surgery training that were each rated on a 10 point scale on level of agreement. All participants were invited to fill out the online survey after being presented an online informed consent. The survey accepted responses for up to one month. Out of 791 residents and interns invited to participate, 180 (23%) accepted the informed consent and responded to the survey. Respondents were from all years of training in both 4 and 6 year programs. Results were descriptively analyzed. Over half of respondents were from 6 year programs (54%) with the remainder from 4 year programs. 34% had performed more than 10 orthognathic cases in the role of junior surgeon. 26.5% of respondents had never operated as junior surgeon during an orthognathic case. 63.5% had never been involved in cadaver training for orthognathic surgery while 36.5% had at least once. 53.5% had been involved in some type of orthognathic training other than on cadavers, including computer simulation, model surgery, or saw bones. In general, the residents felt the cadaver lab was a realistic simulation of clinical orthognathic procedures (average 7.6/10), and that the cadaver training improved their clinical understanding of the procedures (average 8.5/10). The majority of those polled disagreed with the statement that similar or superior surgical knowledge could be attained on a computer simulation of orthognathic surgery as on cadavers (average 4.4/10). Most of those surveyed said they would recomAAOMS 2013
mend the training to all oral surgery residents (average 8.6/10). In conclusion, residents who have experienced orthognathic surgery training in the cadaver lab felt that it was worthwhile and improved their clinical understanding of the performed procedures. Surgical simulation, specifically in the cadaver lab has the potential to be a promising and effective tool for training oral surgery residents in orthognathic surgery. References: 1. Tucker, et al: Comparison of actual surgical outcomes and 3-dimensional surgical simulations. J Oral Maxillofac Surg 68:10, 2010. 2. Kienle MP, Chou JC, Stanton DCS: Cadaver Training in the Education of Orthognathic Surgery. J Oral Maxillofac Surg 70:9, Supp 2, 2012.
POSTER 40 Randomized Prospective Clinical Trial on Use of Resorbable Screws in Fixating Bilateral Sagittal Split Osteotomies for Mandibular Advancement S. H. Yu: University of Washington, D. Bloomquist Statement of the Problem: The use of metal rigid fixation in maxillofacial surgery is now standard in trauma of the maxillofacial skeleton, orthognathic surgery and craniofacial surgery.1 Resorbable fixation material is an attractive option for those patients undergoing orthognathic surgery. Besides the obvious benefit of not having permanent implants, it decreases the possible need for surgical implant removal that will be an additional cost and risk to the patient.2 The purpose of this randomized prospective clinical trial is to compare resorbable screw fixation to titanium screw fixation in orthognathic surgical procedures. In particular, efficacy of resorbable screws will be tested in bilateral mandibular sagittal split osteotomies (BSSO), which are performed for correction of retrognathic mandible. Materials and Methods: A total of 101 patients with mandibular retrognathia who needed mandibular advancement were enrolled in this prospective randomized clinical trial. Patients were randomly assigned to one of two groups with different fixation systems. Patients in Group 1 (n = 51) received titanium screws (Stryker) and patients in Group 2 (n = 50) received resorbable screws (Inion CPS). Outcome measures were clinical evidence of relapse, incidence of infection/inflammation, need for post-operative elastic rubber band use, changes in pre- and post-operative maximal incisal opening and need for additional procedures. Method of Data Analysis: To compare differences between dichotomous variables, the Chi-square or the Fisher’s exact test was used. To test continuous variables,
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