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Orthognathic Surgery
Oral Abstract Session 14 MAXILLOFACIAL RECONSTRUCTION/ORTHOGNATHIC SURGERY Saturday, September 15, 2001, 1:00 pm - 3:15 pm
Buccal Fat Pad: A Locally Available Flap in the Reconstruction of Oral Defects
Kieran Dowd, DMD, 704 Woodhaven Dr, Edison, NJ 08817 (Vincent B. Ziccardi, DDS, MD; John L. Ricci, PhD)
Methods: Twelve 2.0 mm 70:30 poly (L/DL lactide) copolymer plates were evaluated in this study. Each cycle consisted of heating an 8-hole plate in a sterile water bath set to 65°C. After heating, the plate was adapted to the right frontozygomatic suture of a skull model and allowed to cool. The samples were divided into 4 groups: group 1 consisted of unheated, unbent controls, group 2 consisted of 5 cycles, group 3 had 10 cycles, and group 4 had 15 cycles. Samples were then analyzed for molecular weight using a GPC chromatograph. Each plate was sectioned into 4 separate 2-hole segments and tensile testing was performed at the span between holes. Data were analyzed for yield force, displacement to yield, total displacement, and failure. Ratios of force to displacement were calculated for each segment. Results: Twelve segments in each group were analyzed with a 1-way ANOVA test. Control plates showed a mean yield force of 73.71N (SD, 8.2). Group 2 differed significantly, with a mean of 58.07N (SD, 7.2), groups 3 and 4 did not differ significantly from controls (P ⬍ .05). Mean displacement to yield for controls was 0.075 mm (SD, 0.01 mm). Group 4 was significantly lower, with a mean of 0.053 mm (SD, 0.008 mm). The force/ distance ratio in group 4 was significantly higher compared with the control group. Specimen failure was significantly more frequent in the control group (12 of 12), and less frequent (3 of 12) in group 4 (P ⬍ .005). Molecular weight analysis revealed a progressive loss of molecular weight, with group 4 showing an 18% loss compared with controls. Conclusions: Molecular weight, polymer crystallinity, and chain orientation may all be altered by hydration, heating, and repeated deformation. These results show that repeated heating and bending appears to introduce a loss of molecular weight and change in mechanical properties. The initial decrease in yield strength may represent a biphasic change in which altered chain alignment and crystallinity slightly decrease strength. The higher ratios in group 4 most likely reflect an increase in material stiffness with repeated manipulation. Results of this study indicate that although repeated heating and deformation of these plates affects the mechanical and molecular properties, the degree to which this occurs may not be clinically significant. It would be prudent for the clinician to limit the number of heating cycles when possible.
Purpose: The goal of this study was to determine the effect of repeated heating and bending on the biomechanical properties of 1 polylactide plating system.
Pietrzak WS, Sarver DR, Biachini SD, et al: Effect of simulated intraoperative heating and shaping on mechanical properties of a bioab-
Adnan Ali Shah, Montmorency College of Dentistry, 56-Z D.H.A., Lahore Cantt, 54792 Pakistan Statement of the Problem: There are 3 important objectives in the reconstruction of patients with defects in the maxillofacial region. The first is to restore aesthetics, second, to restore function, and thirdly, to restore the psychological and emotional confidence of these patients. To achieve these objectives, clinicians have used a variety of methods, both prosthetic and surgical. The surgical method involved local and distant flaps (pedicled or free microvascular). This study assessed the viability of the locally available buccal fat pad in the reconstruction of oral defects. Methods and Materials: Thirty-three patients (19 females, 14 males; age range, 17 to 55 y) with oral defects were involved in reconstruction with the buccal fat pad from 1997 to 2000. Out of these 33 patients, 10 had oroantral fistula, 5 had squamous cell carcinoma, 10 had salivary gland tumors, 4 had giant cell lesions, 2 had odontogenic fibromas, 1 had ameloblastoma, and 1 had oral submucous fibrosis. Results: Out of 33 patients, 30 had complete healing of the buccal fat pad flap with satisfactory closure of oral defects. One had partial closure, whereas 2 cases encountered total necrosis of the buccal fat pad flap. The buccal fat pad epithelialized between 3 and 6 weeks. Conclusion: Although the use of the buccal fat pad is a technique-sensitive procedure, it appears to be a reliable and versatile flap in the reconstruction of oral defects. References Samman N, Cheung LK, Tideman H: The buccal fat pad in oral reconstruction. Int J Oral Maxillofac Surg 22:2, 1993 Martin-Granizo RL, Naval A, Costas C, et al: Use of buccal fat pad to repair intraoral defects: Review of 30 cases. Br J Oral Maxillofac Surg, 1997
Effect of Repeated Heating and Deformation on the Properties of Biodegradable Plates
AAOMS • 2001
References
83
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery sorbable fracture plate material. J Biomed Mater Res 38:17, 1997 Amecke B, Bendix D, Entenmann G: Resorbable polyesters: Composition, properties, applications. Clin Materials 10:47, 1995
Funding Source: AO North America.
the group 2 specimens and those found with the other 3 groups. Conclusions: Of the fixation methods tested, the greatest stabilization of the mandibulotomy was found with the two 2.0-mm locking plate system. References
A Laboratory Analysis of Methods of Mandibulotomy Fixation Stephen L. Engroff, DDS, MD, 612 Piccadilly Rd, Towson, MD 21204 (Remy H. Blanchaert, DDS, MD; J. Anthony vonFraunhofer, MSc, PhD) Problem: Mandibulotomy is a method used to provide access to tumors involving the tongue, posterior oral cavity, parapharyngeal space, and cranial base. Traditionally, the complication rate is 20% or greater. Rigid fixation techniques have been shown to reduce complications. Critical evaluation of available fixation systems is necessary to define the optimal configuration of hardware to provide consistently complication-free fixation. Materials and Methods: An in vitro model using a red oak model with an elastic modulus similar to the mandible was used to evaluate fixation devices. Five groups of plating configurations used to stabilize red oak mandibular blocks with 5 specimens in each group were studied. Group 1 used 2 4-hole 2.0-mm miniplates and group 2 used 2 4-hole 2.0-mm mandibular locking plates. Group 3 specimens used a 6-hole, 2.0-mm MLP while group 4 used a 6-hole, 2.4-mm rigid plate. Group 5 (controls) were nonosteotomized red oak blocks. Each specimen was tested using the Satek™ universal testing machine with vertical loads applied over the osteotomy site at a rate of 0.5 mm/min, and the specimens were supported at their lateral ends in a custom jig. The force versus displacement behavior was recorded for each specimen. Methods of Data Analysis: The raw data were subjected to a one-way ANOVA and differences between the data were identified by means of a post hoc Scheffe´ test at an a priori ␣ ⫽ 0.05. Results: Plate type and configuration affected the resistance to vertical peak load (kgf) and the fixation stiffness (kgf/mm). Configurations based on 2 plates had a greater stiffness than single-plate fixation. The greatest peak load (58.92 kgf) and stiffness (7.07 kgf/mm) were found with group 2 specimens, followed by group 1 specimens (44.98 kgf and 4.06 kgf/mm). The single-plate systems, groups 3 and 4, had lower peak loads (25.40 and 42.95 kgf) and stiffness values (2.04 and 3.32 kgf/ mm) than the 2-plate systems. The differences in system stiffness were statistically significant (P ⬍ .05), as were the peak loads for groups 1, 2, and 3. The control group (nonosteotomized red oak) had markedly higher values of peak load and stiffness (484 kg and 83 kg/mm, respectively). Differences in failure mode were noted between 84
Amin M, Deschler D, Hayden R: Straight midline mandibulotomy revisited. Laryngoscope 109:1402, 1999 McCann K, Irish J, Gullane P, et al: Complications associated with rigid fixation of mandibulotomies. J Otolaryngol 23:210, 1994 Funding Source: Synthes Maxillofacial Inc.
Radiographic Evidence of Biodegradation of Resorbable Fixation System After Orthognathic Surgery John S. Won, DDS, 115 Brauer Hall, CB 7450, Chapel Hill, NC 27599-7450 (Timothy A. Turvey, DDS) Purpose: The purpose of this study was to quantitatively and qualitatively evaluate the radiographic evidence of self-reinforced resorbable bone screws placed in the mandible of patients who underwent mandibular orthognathic surgery. Material and Methods: Eighty-eight patients who underwent orthognathic surgery involving the mandible and stabilized with self-reinforced resorbable bone plates and screw system (Bionix, USA) from 1999 through 2001 were evaluated for this study. Panoramic radiographs were used to observe evidence of a resorbable plating system immediately, 6 months, and 1-year (if applicable) postoperatively. The area of the ramus and body of the mandible were the clearest areas for observing the presence of the material. The drill holes for the screws appeared as radiolucent circles and were tracked over time to observe healing and bone consolidation. Changes in the definition of outlines of drilled holes were used as quantitative and qualitative evaluation of the radiographs. All of the radiographs of the subjects were taken from the same panoramic radiograph machine at the same institution under standard conditions. Results: Quantitative analysis of radiographs revealed that the number of holes recognizable at 6 months and 1-year postoperative radiographs did not change in any predictable pattern when compared with the immediate postoperative radiograph. Qualitatively, the definition of each drilled hole showed visibly recognizable changes at 6 months and more so at 1 year postoperatively by becoming more diffuse and indistinct. In a few instances, the diameter of the radiolucencies increased, whereas the majority either remained the same or reduced in size. No instances showed complete bone fill even up to 2 years postoperatively. Conclusion: Counting the number and assessing the quality of healing by observing radiographic changes at AAOMS • 2001
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery the screw holes is not a reliable method of following up on the status of resorbable plate systems. Radiographic positioning and film processing differences make it impossible to control for these variables. Additionally, the radiolucency represents loss of bone density and cannot be interpreted as presence or absence of the material.
The Diagnosis and Management of Coronoid Process Hyperplasia Masahiro Furutani, DDS, PhD, Kobe City General Hospital, 4-6 Minatojima-Nakamachi, Chuo-ku, Kobe, 650-0046 Japan (Yoshihiro Tanaka, DDS, PhD; Toshihiko Takenobu, DDS; Mineo Kawai, DDS, PhD; Masanobu Onishi, DDS, PhD) A coronoid process hyperplasia is an uncommon condition that is characterized by restriction of mouth opening without pain. According to the studies reported previously, this symptom occurs mainly due to the bony contact of the elongated coronoid process and the zygoma. On the contrary, it is well known that only the elongated coronoid process may not restrict the mouth opening. The purpose of this study is to clarify the condition of this disease and the outcome of the surgical procedure. Materials and Methods: Thirteen cases of coronoid hyperplasia, 11 female and 2 male, the age ranged from 18 to 53 (mean, 29.2), were misdiagnosed as temporomandibular joint disorder and referred. The interincisal range of motion ranged from 18 mm to 32 mm (mean, 24.3 mm). The preoperative 3D-CT in the mouth opening position revealed that the bony contact of coronoid process and zygoma was observed only in 3 patients. On the contrary, all 13 cases showed the hypertrophy of temporal and masseter muscle, and enlargement of the coronoid process and mandibular angle. MRI of the temporomandibular joint was used to rule out the joint disorder, and bilateral coronoidectomy and resection of contracted masseter was performed via an intraoral approach. Results and Discussion: Postoperative ROM ranged from 34 mm to 45 mm (mean, 39.2 mm). Based on our management series, the restriction of mouth opening would be considered to develop not only by the elongation of the coronoid process, but also the contraction of the masseter or temporal muscle. The 3D-CT in the mouth opening position had a great role in diagnosing the interaction between the coronoid process and zygoma. References McLouglin PM, Hooper C, Bowley NB: Hyperplasia of the mandibular coronoid process: An analysis of 31 cases and a review of the literature. J Oral Maxillofac Surg 53:250, 1995 Loh HS, Ling SY, Lian CB, et al: Bilateral coronoid hyperplasia–a report with a view on its management. J Oral Rehabil 24:782, 1997
AAOMS • 2001
Maxillary Sinus Pathology: Correlation With Facial Form Curt J. Bowman, DDS, 1001 Stanton L. Young Blvd, 2nd Floor, Dept of OMFS, Oklahoma City, OK 73192 (Johan P. Reyneke, BChD, MChD; H. Coleman, DDS) Purpose: Although there has been investigation into maxillary sinus disease after maxillary orthognathic surgery, little attention has been given to the presence of presurgical sinus pathology resulting from a dentofacial deformity. Our study sought to determine a causal relationship between vertical maxillary excess and maxillary sinus pathology. Methods and Materials: A total of 110 patients who underwent maxillary Le Fort I osteotomy with downfracture were randomly selected over the course of 1 year. The patient pool included 84 women and 26 men ranging in age from 14 to 47 years with a mean age of 19 years. In all patients, preoperative cephalometric and clinical evaluation indicated a diagnosis of vertical maxillary excess. A preoperative interlabial gap of 3 mm or less in repose was recorded as normal. Biopsies were taken from bilateral maxillary sinus mucosae in all patients at the time of downfracture and examined histologically for signs of pathology. The presence of one of several histopathologic findings was noted as positive: polyps, true retention cyst formation, basement membrane thickening, dystrophic calcification, edema with a history of congestion, degree of inflammation, and type of inflammatory cells present. All patients’ symptomatic histories were unknown at the time of selection. Results: Histopathologic findings were compared with the diagnosis of vertical maxillary excess and preoperative interlabial distance. A significant positive relationship was found to exist between vertical maxillary excess and the presence of maxillary sinus pathology in the majority of patients. Conclusion: The presence of dentofacial deformity, specifically vertical maxillary excess, seems to have a positive causal relationship on the development of maxillary sinus pathology. Further investigation is required to elucidate this relationship and that of other dentofacial deformities and sinus pathology. References Bell CS, Thrash WJ, Zysset MK: Incidence of maxillary sinusitis following Le Fort I maxillary osteotomy. J Oral Maxillofac Surg 44:100, 1986 Kahnberg KE, Engstrom H: Recovery of maxillary sinus and tooth sensibility after Le Fort I osteotomy. Br J Oral Maxillofac Surg 25:68, 1987 Nustad RA, Fonseca RJ, Zeitler D: Evaluation of maxillary sinus disease in maxillary orthognathic surgery patients. Internat J Adult Orthod Orthognath Surg 1:195, 1986
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Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery
Correction of Sagittal Synostosis With a Two-Stage Procedure: Two-Year Postoperative Outcomes Sittichai Tantipasawasin, DDS, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9109 (Douglas P. Sinn, DDS) Sagittal synostosis is premature fusion of the sagittal suture. It is the most common form of isolated nonsyndromic craniosynostosis; the incidence is 46% of all synostosis of the cranium. There are 13% to 42% of sagittal synostosis patients who develop signs of increased intracranial pressure such as headache, vomiting, blindness, and decreased mental development. Surgery at an early age is the treatment of choice. There are many surgical options for management of this deformity, ie, strip craniectomy, extensive craniotomy with reconstruction, and craniotacsis. Extensive craniotomy with reconstruction provides the best management. Several single-stage craniotomies have been described. There are many risks in caring for these patients, ie, difficult position for airway management, increased operating time, and a high morbidity and mortality rate. Two-stage procedures for correction of sagittal synostasis were developed at our institution to lessen these risks. The stage I procedure is posterior cranial vault reshaping, and the stage II procedure is anterior cranial vault reshaping with orbital rim advancement. The purpose of this prospective study was to evaluate the risk/benefit, effectiveness, and morphologic results of the 2-stage procedures. There are 25 patients who were diagnosed with untreated isolated nonsyndromic sagittal synostosis and were treated at Children’s Medical Center, Dallas, Texas, included in this study. The time between the stage I procedure and the stage II procedure was 1 to 2 weeks. Measurement of patient skull was performed preoperatively and postoperatively. Mean age at surgery was 8.7 months. Cranial length decreased 15%. The upper cranial width was significantly increased (mean, 34 mm). Lateral projection increased 3%. No significant change in cranial height and anterior cranial width was noted. The morphologic changes will be shown. A complete review of the statistics will be included. Patients who were treated with 2-stage procedures had a decrease in anesthetic risks and surgical risks. This and the reduction of other risks makes this the preferred approach. The outcomes with 2-stage procedures appear better than single-stage due to increased access. The results of this approach will be shown in the presentation. References Cohen MM: Craniosynostosis: Diagnosis, Evaluation, and Management (ed 21). Oxford University Press Inc, 2000
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Salyer KE: Salyer and Bardach’s Atlas of Craniofacial & Cleft Surgery. Lippincott-Raven Publishers, 1999
Effects of Age, Amount of Advancement and Genioplasty on Neurosensory Disturbance Following BSSO Joseph E. Van Sickels, DDS, University of Kentucky College of Dentistry, Oral and Maxillofacial Surgery, D512 Chandler Medical Center, Lexington, KY 405360297 (J. Hatch, PhD; C. Dolce, DDS; J. Rugh, PhD; R. A. Bays, DDS) Statement of the Problem: Neurosensory deficits are a recognized complication after bilateral sagittal split. Risk for these deficits is associated with multiple factors; however, controversy regarding interaction of these factors remains. We conducted a prospective evaluation of neurosensory deficits in patients undergoing mandibular advancement and followed for 2 years, evaluating the effects of genioplasty, length of advancement, and age. Materials and Methods: Patients were randomized to rigid or wire fixation. Genioplasties were dictated by the aesthetic demands of the patient. The patients were examined presurgery, at 1 week, 8 weeks, 6 months, 1 year, and 2 years after surgery. Damage was assessed by measuring light touch in the mental nerve distribution using Semmes-Weinstein pressure aesthesiometer monofilaments with the 2-alternate forced-choice method. Method of Data Analysis: One hundred twenty-seven subjects (mean age, 30 years; range, 14 to 57) were divided into 3 age groups ⬍24 (n ⫽ 40), 24 to 35 (n ⫽ 43), and ⬎35 (n ⫽ 44). They also were divided into small ⱕ7 (n ⫽ 73) and large ⬎7 mm (n ⫽ 54) advancements and genioplasty (n ⫽ 59) and no genioplasty (n ⫽ 68). Change in tactile sensitivity from presurgical baseline to the subsequent time periods is reported as a function of age, genioplasty, and amount of advancement plus interactions among these variables. Less than 1% of missing data were imputed using an EM technique. Data were analyzed using the Kruskal-Wallis test, and the Friedman test all at an alpha level of 0.05. Results: Older subjects showed greater sensory losses than younger subjects (most pronounced at 1 week, less so later). Patients who had a genioplasty had a greater loss of sensation initially with its effects decreasing over time. With all subjects, the sensory function of those receiving large and small advancements was not significantly different. Similarly, among subjects receiving small advancements, there was no significant difference among the 3 age groups. However, among patients receiving advancements ⬎7 mm, older patients did worse at all time intervals (P ⬍ .05 at 1 week and 1 year). Among patients not receiving genioplasty, there was no significant difference among the 3 age groups. In contrast, older subjects who received genioplasty had significantly greater sensory deficits 1 week after surgery. AAOMS • 2001
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery Conclusions: Patient age at the time of surgery and addition of a genioplasty increase the risk of a neurosensory injury. Large advancements increase the risk of neurosensory injury, especially when combined with a genioplasty in older patients. References August M, Marchena J, Konady J, et al: Neurosensory deficit and functional impairment after sagittal ramus osteotomy: A long-term follow-up study. J Oral Maxillofac Surg 56:1231, 1998 Ylikontiola L, Kinnunen J, Oikarinen K: Factors affecting neurosensory disturbance after mandibular bilateral sagittal split osteotomy. J Oral Maxillofac Surg 58:1234, 2000 Funding Source: NIH Grant DE 0963.
Functional Repair of Cleft Palate Deformities Ho Lee, DDS, MD, 18 East 50th St, 5th Floor, New York, NY 10022 (George E. Anastassov, MD, DDS; Ulrich Joos, MD, DDS, PhD, DhC) The controversy regarding the timing of repair of the cleft palate still exists. These vary between neonatal repair to the preschool-age. The polemics usually arise around the maxillary growth retardation resulting from the procedure. The techniques used are based on various treatment philosophies. However, the goals of optimal functional rehabilitation, ie, normal speech, palatopharyngeal sufficiency, and middle ear aeration of the affected patients are not always fulfilled. The aim of this presentation is to share our experience with functional, simultaneous, 1-stage soft and hard palate palatoplasties performed in the prelinguistic stage at the age of 9 months. Patients and Methods: Over a period of 20 years, we treated 2,698 patients with cleft lip and palate deformities. Out of these patients, there were 1,018 patients
AAOMS • 2001
with isolated palatal clefts. All patients were operated on according to the same protocol and the same surgical procedure. The treatment philosophy was based on early soft and hard palate functional palatoplasty. The most important part of the operation is the identification and mobilization of the palatal muscles, especially the palatoglossus and palatopharyngeus and their advancement to the midline, which re-establishes the so-called fourth perioral sphincter. Results: All patients were followed longitudinally and retrospectively. The parameters investigated were velopharyngeal competency, presence or absence of growth retardation, and the rate of middle ear infections. The parameters studied indicated that when this treatment schedule was followed, and the procedures were performed on time and according to the protocol, there was minimal growth retardation, minimal VPI, and no increased rate of ear infections compared with the normal controls. Conclusion: It is paramount to respect the functional anatomy of the palate. The repair has to be performed in the prelinguistic stage of the development of the child (before 12 months of age). This will prevent the formation of faulty articulation patterns and provide for optimal phonologic development. When m. palatoglossus and palatopharyngeus are not repaired, nothing will counteract the ventrocaudal thrust of the tongue which contributes to the mandibular forward and downward growth, with resulting mandibular hyperplasia (class III malocclusion). References Joos U: The importance of muscular reconstruction in the treatment of cleft lip and palate. Scand J Plast Reconstr Surg 21:109, 1987 Ysunza A, Pamplona C, Mendoza M, et al: Speech outcome and maxillary growth in patients with unilateral complete cleft lip/palate operated on 6 versus 12 months of age. Plast Reconstr Surg 2:675, 1998 Funding Source: University of Mu ¨ nster, Medical School.
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Buccal Fat Pad: A Locally Available Flap in the Reconstruction of Oral Defects
Kieran Dowd, DMD, 704 Woodhaven Dr, Edison, NJ 08817 (Vincent B. Ziccardi, DDS, MD; John L. Ricci, PhD)
Methods: Twelve 2.0 mm 70:30 poly (L/DL lactide) copolymer plates were evaluated in this study. Each cycle consisted of heating an 8-hole plate in a sterile water bath set to 65°C. After heating, the plate was adapted to the right frontozygomatic suture of a skull model and allowed to cool. The samples were divided into 4 groups: group 1 consisted of unheated, unbent controls, group 2 consisted of 5 cycles, group 3 had 10 cycles, and group 4 had 15 cycles. Samples were then analyzed for molecular weight using a GPC chromatograph. Each plate was sectioned into 4 separate 2-hole segments and tensile testing was performed at the span between holes. Data were analyzed for yield force, displacement to yield, total displacement, and failure. Ratios of force to displacement were calculated for each segment. Results: Twelve segments in each group were analyzed with a 1-way ANOVA test. Control plates showed a mean yield force of 73.71N (SD, 8.2). Group 2 differed significantly, with a mean of 58.07N (SD, 7.2), groups 3 and 4 did not differ significantly from controls (P ⬍ .05). Mean displacement to yield for controls was 0.075 mm (SD, 0.01 mm). Group 4 was significantly lower, with a mean of 0.053 mm (SD, 0.008 mm). The force/ distance ratio in group 4 was significantly higher compared with the control group. Specimen failure was significantly more frequent in the control group (12 of 12), and less frequent (3 of 12) in group 4 (P ⬍ .005). Molecular weight analysis revealed a progressive loss of molecular weight, with group 4 showing an 18% loss compared with controls. Conclusions: Molecular weight, polymer crystallinity, and chain orientation may all be altered by hydration, heating, and repeated deformation. These results show that repeated heating and bending appears to introduce a loss of molecular weight and change in mechanical properties. The initial decrease in yield strength may represent a biphasic change in which altered chain alignment and crystallinity slightly decrease strength. The higher ratios in group 4 most likely reflect an increase in material stiffness with repeated manipulation. Results of this study indicate that although repeated heating and deformation of these plates affects the mechanical and molecular properties, the degree to which this occurs may not be clinically significant. It would be prudent for the clinician to limit the number of heating cycles when possible.
Purpose: The goal of this study was to determine the effect of repeated heating and bending on the biomechanical properties of 1 polylactide plating system.
Pietrzak WS, Sarver DR, Biachini SD, et al: Effect of simulated intraoperative heating and shaping on mechanical properties of a bioab-
Adnan Ali Shah, Montmorency College of Dentistry, 56-Z D.H.A., Lahore Cantt, 54792 Pakistan Statement of the Problem: There are 3 important objectives in the reconstruction of patients with defects in the maxillofacial region. The first is to restore aesthetics, second, to restore function, and thirdly, to restore the psychological and emotional confidence of these patients. To achieve these objectives, clinicians have used a variety of methods, both prosthetic and surgical. The surgical method involved local and distant flaps (pedicled or free microvascular). This study assessed the viability of the locally available buccal fat pad in the reconstruction of oral defects. Methods and Materials: Thirty-three patients (19 females, 14 males; age range, 17 to 55 y) with oral defects were involved in reconstruction with the buccal fat pad from 1997 to 2000. Out of these 33 patients, 10 had oroantral fistula, 5 had squamous cell carcinoma, 10 had salivary gland tumors, 4 had giant cell lesions, 2 had odontogenic fibromas, 1 had ameloblastoma, and 1 had oral submucous fibrosis. Results: Out of 33 patients, 30 had complete healing of the buccal fat pad flap with satisfactory closure of oral defects. One had partial closure, whereas 2 cases encountered total necrosis of the buccal fat pad flap. The buccal fat pad epithelialized between 3 and 6 weeks. Conclusion: Although the use of the buccal fat pad is a technique-sensitive procedure, it appears to be a reliable and versatile flap in the reconstruction of oral defects. References Samman N, Cheung LK, Tideman H: The buccal fat pad in oral reconstruction. Int J Oral Maxillofac Surg 22:2, 1993 Martin-Granizo RL, Naval A, Costas C, et al: Use of buccal fat pad to repair intraoral defects: Review of 30 cases. Br J Oral Maxillofac Surg, 1997
Effect of Repeated Heating and Deformation on the Properties of Biodegradable Plates
AAOMS • 2001
References
83
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery sorbable fracture plate material. J Biomed Mater Res 38:17, 1997 Amecke B, Bendix D, Entenmann G: Resorbable polyesters: Composition, properties, applications. Clin Materials 10:47, 1995
Funding Source: AO North America.
the group 2 specimens and those found with the other 3 groups. Conclusions: Of the fixation methods tested, the greatest stabilization of the mandibulotomy was found with the two 2.0-mm locking plate system. References
A Laboratory Analysis of Methods of Mandibulotomy Fixation Stephen L. Engroff, DDS, MD, 612 Piccadilly Rd, Towson, MD 21204 (Remy H. Blanchaert, DDS, MD; J. Anthony vonFraunhofer, MSc, PhD) Problem: Mandibulotomy is a method used to provide access to tumors involving the tongue, posterior oral cavity, parapharyngeal space, and cranial base. Traditionally, the complication rate is 20% or greater. Rigid fixation techniques have been shown to reduce complications. Critical evaluation of available fixation systems is necessary to define the optimal configuration of hardware to provide consistently complication-free fixation. Materials and Methods: An in vitro model using a red oak model with an elastic modulus similar to the mandible was used to evaluate fixation devices. Five groups of plating configurations used to stabilize red oak mandibular blocks with 5 specimens in each group were studied. Group 1 used 2 4-hole 2.0-mm miniplates and group 2 used 2 4-hole 2.0-mm mandibular locking plates. Group 3 specimens used a 6-hole, 2.0-mm MLP while group 4 used a 6-hole, 2.4-mm rigid plate. Group 5 (controls) were nonosteotomized red oak blocks. Each specimen was tested using the Satek™ universal testing machine with vertical loads applied over the osteotomy site at a rate of 0.5 mm/min, and the specimens were supported at their lateral ends in a custom jig. The force versus displacement behavior was recorded for each specimen. Methods of Data Analysis: The raw data were subjected to a one-way ANOVA and differences between the data were identified by means of a post hoc Scheffe´ test at an a priori ␣ ⫽ 0.05. Results: Plate type and configuration affected the resistance to vertical peak load (kgf) and the fixation stiffness (kgf/mm). Configurations based on 2 plates had a greater stiffness than single-plate fixation. The greatest peak load (58.92 kgf) and stiffness (7.07 kgf/mm) were found with group 2 specimens, followed by group 1 specimens (44.98 kgf and 4.06 kgf/mm). The single-plate systems, groups 3 and 4, had lower peak loads (25.40 and 42.95 kgf) and stiffness values (2.04 and 3.32 kgf/ mm) than the 2-plate systems. The differences in system stiffness were statistically significant (P ⬍ .05), as were the peak loads for groups 1, 2, and 3. The control group (nonosteotomized red oak) had markedly higher values of peak load and stiffness (484 kg and 83 kg/mm, respectively). Differences in failure mode were noted between 84
Amin M, Deschler D, Hayden R: Straight midline mandibulotomy revisited. Laryngoscope 109:1402, 1999 McCann K, Irish J, Gullane P, et al: Complications associated with rigid fixation of mandibulotomies. J Otolaryngol 23:210, 1994 Funding Source: Synthes Maxillofacial Inc.
Radiographic Evidence of Biodegradation of Resorbable Fixation System After Orthognathic Surgery John S. Won, DDS, 115 Brauer Hall, CB 7450, Chapel Hill, NC 27599-7450 (Timothy A. Turvey, DDS) Purpose: The purpose of this study was to quantitatively and qualitatively evaluate the radiographic evidence of self-reinforced resorbable bone screws placed in the mandible of patients who underwent mandibular orthognathic surgery. Material and Methods: Eighty-eight patients who underwent orthognathic surgery involving the mandible and stabilized with self-reinforced resorbable bone plates and screw system (Bionix, USA) from 1999 through 2001 were evaluated for this study. Panoramic radiographs were used to observe evidence of a resorbable plating system immediately, 6 months, and 1-year (if applicable) postoperatively. The area of the ramus and body of the mandible were the clearest areas for observing the presence of the material. The drill holes for the screws appeared as radiolucent circles and were tracked over time to observe healing and bone consolidation. Changes in the definition of outlines of drilled holes were used as quantitative and qualitative evaluation of the radiographs. All of the radiographs of the subjects were taken from the same panoramic radiograph machine at the same institution under standard conditions. Results: Quantitative analysis of radiographs revealed that the number of holes recognizable at 6 months and 1-year postoperative radiographs did not change in any predictable pattern when compared with the immediate postoperative radiograph. Qualitatively, the definition of each drilled hole showed visibly recognizable changes at 6 months and more so at 1 year postoperatively by becoming more diffuse and indistinct. In a few instances, the diameter of the radiolucencies increased, whereas the majority either remained the same or reduced in size. No instances showed complete bone fill even up to 2 years postoperatively. Conclusion: Counting the number and assessing the quality of healing by observing radiographic changes at AAOMS • 2001
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery the screw holes is not a reliable method of following up on the status of resorbable plate systems. Radiographic positioning and film processing differences make it impossible to control for these variables. Additionally, the radiolucency represents loss of bone density and cannot be interpreted as presence or absence of the material.
The Diagnosis and Management of Coronoid Process Hyperplasia Masahiro Furutani, DDS, PhD, Kobe City General Hospital, 4-6 Minatojima-Nakamachi, Chuo-ku, Kobe, 650-0046 Japan (Yoshihiro Tanaka, DDS, PhD; Toshihiko Takenobu, DDS; Mineo Kawai, DDS, PhD; Masanobu Onishi, DDS, PhD) A coronoid process hyperplasia is an uncommon condition that is characterized by restriction of mouth opening without pain. According to the studies reported previously, this symptom occurs mainly due to the bony contact of the elongated coronoid process and the zygoma. On the contrary, it is well known that only the elongated coronoid process may not restrict the mouth opening. The purpose of this study is to clarify the condition of this disease and the outcome of the surgical procedure. Materials and Methods: Thirteen cases of coronoid hyperplasia, 11 female and 2 male, the age ranged from 18 to 53 (mean, 29.2), were misdiagnosed as temporomandibular joint disorder and referred. The interincisal range of motion ranged from 18 mm to 32 mm (mean, 24.3 mm). The preoperative 3D-CT in the mouth opening position revealed that the bony contact of coronoid process and zygoma was observed only in 3 patients. On the contrary, all 13 cases showed the hypertrophy of temporal and masseter muscle, and enlargement of the coronoid process and mandibular angle. MRI of the temporomandibular joint was used to rule out the joint disorder, and bilateral coronoidectomy and resection of contracted masseter was performed via an intraoral approach. Results and Discussion: Postoperative ROM ranged from 34 mm to 45 mm (mean, 39.2 mm). Based on our management series, the restriction of mouth opening would be considered to develop not only by the elongation of the coronoid process, but also the contraction of the masseter or temporal muscle. The 3D-CT in the mouth opening position had a great role in diagnosing the interaction between the coronoid process and zygoma. References McLouglin PM, Hooper C, Bowley NB: Hyperplasia of the mandibular coronoid process: An analysis of 31 cases and a review of the literature. J Oral Maxillofac Surg 53:250, 1995 Loh HS, Ling SY, Lian CB, et al: Bilateral coronoid hyperplasia–a report with a view on its management. J Oral Rehabil 24:782, 1997
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Maxillary Sinus Pathology: Correlation With Facial Form Curt J. Bowman, DDS, 1001 Stanton L. Young Blvd, 2nd Floor, Dept of OMFS, Oklahoma City, OK 73192 (Johan P. Reyneke, BChD, MChD; H. Coleman, DDS) Purpose: Although there has been investigation into maxillary sinus disease after maxillary orthognathic surgery, little attention has been given to the presence of presurgical sinus pathology resulting from a dentofacial deformity. Our study sought to determine a causal relationship between vertical maxillary excess and maxillary sinus pathology. Methods and Materials: A total of 110 patients who underwent maxillary Le Fort I osteotomy with downfracture were randomly selected over the course of 1 year. The patient pool included 84 women and 26 men ranging in age from 14 to 47 years with a mean age of 19 years. In all patients, preoperative cephalometric and clinical evaluation indicated a diagnosis of vertical maxillary excess. A preoperative interlabial gap of 3 mm or less in repose was recorded as normal. Biopsies were taken from bilateral maxillary sinus mucosae in all patients at the time of downfracture and examined histologically for signs of pathology. The presence of one of several histopathologic findings was noted as positive: polyps, true retention cyst formation, basement membrane thickening, dystrophic calcification, edema with a history of congestion, degree of inflammation, and type of inflammatory cells present. All patients’ symptomatic histories were unknown at the time of selection. Results: Histopathologic findings were compared with the diagnosis of vertical maxillary excess and preoperative interlabial distance. A significant positive relationship was found to exist between vertical maxillary excess and the presence of maxillary sinus pathology in the majority of patients. Conclusion: The presence of dentofacial deformity, specifically vertical maxillary excess, seems to have a positive causal relationship on the development of maxillary sinus pathology. Further investigation is required to elucidate this relationship and that of other dentofacial deformities and sinus pathology. References Bell CS, Thrash WJ, Zysset MK: Incidence of maxillary sinusitis following Le Fort I maxillary osteotomy. J Oral Maxillofac Surg 44:100, 1986 Kahnberg KE, Engstrom H: Recovery of maxillary sinus and tooth sensibility after Le Fort I osteotomy. Br J Oral Maxillofac Surg 25:68, 1987 Nustad RA, Fonseca RJ, Zeitler D: Evaluation of maxillary sinus disease in maxillary orthognathic surgery patients. Internat J Adult Orthod Orthognath Surg 1:195, 1986
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Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery
Correction of Sagittal Synostosis With a Two-Stage Procedure: Two-Year Postoperative Outcomes Sittichai Tantipasawasin, DDS, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9109 (Douglas P. Sinn, DDS) Sagittal synostosis is premature fusion of the sagittal suture. It is the most common form of isolated nonsyndromic craniosynostosis; the incidence is 46% of all synostosis of the cranium. There are 13% to 42% of sagittal synostosis patients who develop signs of increased intracranial pressure such as headache, vomiting, blindness, and decreased mental development. Surgery at an early age is the treatment of choice. There are many surgical options for management of this deformity, ie, strip craniectomy, extensive craniotomy with reconstruction, and craniotacsis. Extensive craniotomy with reconstruction provides the best management. Several single-stage craniotomies have been described. There are many risks in caring for these patients, ie, difficult position for airway management, increased operating time, and a high morbidity and mortality rate. Two-stage procedures for correction of sagittal synostasis were developed at our institution to lessen these risks. The stage I procedure is posterior cranial vault reshaping, and the stage II procedure is anterior cranial vault reshaping with orbital rim advancement. The purpose of this prospective study was to evaluate the risk/benefit, effectiveness, and morphologic results of the 2-stage procedures. There are 25 patients who were diagnosed with untreated isolated nonsyndromic sagittal synostosis and were treated at Children’s Medical Center, Dallas, Texas, included in this study. The time between the stage I procedure and the stage II procedure was 1 to 2 weeks. Measurement of patient skull was performed preoperatively and postoperatively. Mean age at surgery was 8.7 months. Cranial length decreased 15%. The upper cranial width was significantly increased (mean, 34 mm). Lateral projection increased 3%. No significant change in cranial height and anterior cranial width was noted. The morphologic changes will be shown. A complete review of the statistics will be included. Patients who were treated with 2-stage procedures had a decrease in anesthetic risks and surgical risks. This and the reduction of other risks makes this the preferred approach. The outcomes with 2-stage procedures appear better than single-stage due to increased access. The results of this approach will be shown in the presentation. References Cohen MM: Craniosynostosis: Diagnosis, Evaluation, and Management (ed 21). Oxford University Press Inc, 2000
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Salyer KE: Salyer and Bardach’s Atlas of Craniofacial & Cleft Surgery. Lippincott-Raven Publishers, 1999
Effects of Age, Amount of Advancement and Genioplasty on Neurosensory Disturbance Following BSSO Joseph E. Van Sickels, DDS, University of Kentucky College of Dentistry, Oral and Maxillofacial Surgery, D512 Chandler Medical Center, Lexington, KY 405360297 (J. Hatch, PhD; C. Dolce, DDS; J. Rugh, PhD; R. A. Bays, DDS) Statement of the Problem: Neurosensory deficits are a recognized complication after bilateral sagittal split. Risk for these deficits is associated with multiple factors; however, controversy regarding interaction of these factors remains. We conducted a prospective evaluation of neurosensory deficits in patients undergoing mandibular advancement and followed for 2 years, evaluating the effects of genioplasty, length of advancement, and age. Materials and Methods: Patients were randomized to rigid or wire fixation. Genioplasties were dictated by the aesthetic demands of the patient. The patients were examined presurgery, at 1 week, 8 weeks, 6 months, 1 year, and 2 years after surgery. Damage was assessed by measuring light touch in the mental nerve distribution using Semmes-Weinstein pressure aesthesiometer monofilaments with the 2-alternate forced-choice method. Method of Data Analysis: One hundred twenty-seven subjects (mean age, 30 years; range, 14 to 57) were divided into 3 age groups ⬍24 (n ⫽ 40), 24 to 35 (n ⫽ 43), and ⬎35 (n ⫽ 44). They also were divided into small ⱕ7 (n ⫽ 73) and large ⬎7 mm (n ⫽ 54) advancements and genioplasty (n ⫽ 59) and no genioplasty (n ⫽ 68). Change in tactile sensitivity from presurgical baseline to the subsequent time periods is reported as a function of age, genioplasty, and amount of advancement plus interactions among these variables. Less than 1% of missing data were imputed using an EM technique. Data were analyzed using the Kruskal-Wallis test, and the Friedman test all at an alpha level of 0.05. Results: Older subjects showed greater sensory losses than younger subjects (most pronounced at 1 week, less so later). Patients who had a genioplasty had a greater loss of sensation initially with its effects decreasing over time. With all subjects, the sensory function of those receiving large and small advancements was not significantly different. Similarly, among subjects receiving small advancements, there was no significant difference among the 3 age groups. However, among patients receiving advancements ⬎7 mm, older patients did worse at all time intervals (P ⬍ .05 at 1 week and 1 year). Among patients not receiving genioplasty, there was no significant difference among the 3 age groups. In contrast, older subjects who received genioplasty had significantly greater sensory deficits 1 week after surgery. AAOMS • 2001
Oral Abstract Session 14: Maxillofacial Reconstruction/Orthognathic Surgery Conclusions: Patient age at the time of surgery and addition of a genioplasty increase the risk of a neurosensory injury. Large advancements increase the risk of neurosensory injury, especially when combined with a genioplasty in older patients. References August M, Marchena J, Konady J, et al: Neurosensory deficit and functional impairment after sagittal ramus osteotomy: A long-term follow-up study. J Oral Maxillofac Surg 56:1231, 1998 Ylikontiola L, Kinnunen J, Oikarinen K: Factors affecting neurosensory disturbance after mandibular bilateral sagittal split osteotomy. J Oral Maxillofac Surg 58:1234, 2000 Funding Source: NIH Grant DE 0963.
Functional Repair of Cleft Palate Deformities Ho Lee, DDS, MD, 18 East 50th St, 5th Floor, New York, NY 10022 (George E. Anastassov, MD, DDS; Ulrich Joos, MD, DDS, PhD, DhC) The controversy regarding the timing of repair of the cleft palate still exists. These vary between neonatal repair to the preschool-age. The polemics usually arise around the maxillary growth retardation resulting from the procedure. The techniques used are based on various treatment philosophies. However, the goals of optimal functional rehabilitation, ie, normal speech, palatopharyngeal sufficiency, and middle ear aeration of the affected patients are not always fulfilled. The aim of this presentation is to share our experience with functional, simultaneous, 1-stage soft and hard palate palatoplasties performed in the prelinguistic stage at the age of 9 months. Patients and Methods: Over a period of 20 years, we treated 2,698 patients with cleft lip and palate deformities. Out of these patients, there were 1,018 patients
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with isolated palatal clefts. All patients were operated on according to the same protocol and the same surgical procedure. The treatment philosophy was based on early soft and hard palate functional palatoplasty. The most important part of the operation is the identification and mobilization of the palatal muscles, especially the palatoglossus and palatopharyngeus and their advancement to the midline, which re-establishes the so-called fourth perioral sphincter. Results: All patients were followed longitudinally and retrospectively. The parameters investigated were velopharyngeal competency, presence or absence of growth retardation, and the rate of middle ear infections. The parameters studied indicated that when this treatment schedule was followed, and the procedures were performed on time and according to the protocol, there was minimal growth retardation, minimal VPI, and no increased rate of ear infections compared with the normal controls. Conclusion: It is paramount to respect the functional anatomy of the palate. The repair has to be performed in the prelinguistic stage of the development of the child (before 12 months of age). This will prevent the formation of faulty articulation patterns and provide for optimal phonologic development. When m. palatoglossus and palatopharyngeus are not repaired, nothing will counteract the ventrocaudal thrust of the tongue which contributes to the mandibular forward and downward growth, with resulting mandibular hyperplasia (class III malocclusion). References Joos U: The importance of muscular reconstruction in the treatment of cleft lip and palate. Scand J Plast Reconstr Surg 21:109, 1987 Ysunza A, Pamplona C, Mendoza M, et al: Speech outcome and maxillary growth in patients with unilateral complete cleft lip/palate operated on 6 versus 12 months of age. Plast Reconstr Surg 2:675, 1998 Funding Source: University of Mu ¨ nster, Medical School.
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