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Biomedical subjects

M J Troulis

Publications and source records attributed to M J Troulis.

At least 19 recordsLinked to original sources
PubMed2006

Pediatric facial fractures: recent advances in prevention, diagnosis and management.

During the last 25 years, there have been considerable advances in the prevention, diagnosis and management of craniomaxillofacial injuries in children. When compared to adults, the pattern of fractures and frequency of associated injuries are similar but the overall incidence is much lower. Diagnosis is more difficult than in adults and fractures are easily overlooked. Clinical diagnosis is best confirmed by computed tomographic (CT) scans. Treatment is usually performed without delay and can be limited to observation or closed reduction in non-displaced or minimally displaced fractures. Operative management should involve minimal manipulation and may be modified by the stage of skeletal and dental development. Open reduction and rigid internal fixation is indicated for severely displaced fractures. Primary bone grafting is preferred over secondary reconstruction and alloplastic materials should be avoided when possible. Children require long-term follow-up to monitor potential growth abnormalities. This article is a review of the epidemiology, diagnosis and management of facial fractures in children.

Bone Transplantation↗
PubMed2005

Pediatric facial fractures: recent advances in prevention, diagnosis and management.

During the last 25 years, there have been considerable advances in the prevention, diagnosis and management of craniomaxillofacial injuries in children. When compared to adults, the pattern of fractures and frequency of associated injuries are similar but the overall incidence is much lower. Diagnosis is more difficult than in adults and fractures are easily overlooked. Clinical diagnosis is best confirmed by computed tomographic (CT) scans. Treatment is usually performed without delay and can be limited to observation or closed reduction in non-displaced or minimally displaced fractures. Operative management should involve minimal manipulation and may be modified by the stage of skeletal and dental development. Open reduction and rigid internal fixation is indicated for severely displaced fractures. Primary bone grafting is preferred over secondary reconstruction and alloplastic materials should be avoided when possible. Children require long-term follow-up to monitor potential growth abnormalities. This article is a review of the epidemiology, diagnosis and management of facial fractures in children.

Adolescent↗
PubMed2005

Histology of the porcine mandibular distraction wound.

The purpose of this study was to document the progression and pattern of endosteal bone formation in a porcine mandibular distraction wound. Bone formation was assessed in a 0-day latency model (n=24 pigs) using distraction rates of 1, 2, or 4 mm/day to create a 12-mm gap. Macro-radiographs and sagittal histologic sections, from the center of the mandible, were evaluated by computer morphometrics (% bone fill) and by a semi-quantitative bone formation score. Mean percent area of new bone was 12.4% (0-25.9%), 7.5% (0-21.3%) and 3.8% (0-10.5%) in mandibles distracted at 1, 2 or 4 mm/day respectively. At all time points, percent area of new bone was highest in mandibles distracted at 1 mm/day. Bone was deposited from the margins of the osteotomy toward the center of the wound and occurred first around the inferior alveolar canal and tooth bud regions. New bone formed by intramembranous ossification alone. The results of this experiment document the contribution of endosteal bone formation in this model of distraction osteogenesis.

Analysis of Variance↗
PubMed2004

Assessment of bone formation in a porcine mandibular distraction wound by computed tomography.

The purpose of this study was to document the progression of bone formation in a porcine mandibular distraction wound, at various distraction rates and fixation times, using three-dimensional computed tomography. Bone formation was assessed in a 0-day latency model (n=24 minipigs) using distraction rates of 1, 2, or 4 mm/day to create a 12 mm distraction gap. Animals were sacrificed at 0, 8, 16, or 24 days fixation. For experimental and control sides, three-dimensional data from computed tomographic scans were used to calculate the percent bone volume in the regions of interest. Standardized plain radiographs were used to evaluate bone formation with a semiquantitative scale: 0, 1, 2, 3. Mean percent bone volume and radiographic bone fill scores (pooled sample) increased with fixation time from 16.8% and 0.17 at 0 days, to 64% and 2.0 at 24 days fixation. Mandibles distracted at 1mm/day had higher CT values and bone fill scores than mandibles distracted at 2 or 4 mm/day. At 24 days fixation, the maximum percent bone volume (64%--1 mm/day; 24 days fixation) remained below control values (81.3%). The results of this study indicate that despite high bone fill scores on plain radiographs, the highest percent CT bone volume achieved in this model was 64%.

Animals↗
PubMed2003

Correlation of biomechanical stiffness with plain radiographic and ultrasound data in an experimental mandibular distraction wound.

The aim of this study was to determine the stiffness of a porcine mandibular distraction wound at the end of neutral fixation.Twenty-four Yucatan minipigs underwent unilateral mandibular distraction: zero-day latency, rates of 1, 2, and 4 mm per day, distraction gap of 12 mm. Radiographic and ultrasound bone fill scores at 0, 8, 16 and 24 days of neutral fixation were used to evaluate interval healing. At sacrifice, biomechanical stiffness was determined using an Instron machine to produce a downward force of 2 mm/min at the premolar occlusal surface. Force (kilo-Newton, kN) and displacement (mm) were recorded at a rate of 10,000 points/second. Stiffness across the distraction wound, plain radiographic and ultrasound bone fill scores all increased with duration of neutral fixation and were highest for the 1 mm per day group at all time points. At the end of fixation, even in the most clinically stable group, stiffness across the distraction wound was only 25.5% of control.Despite clinical stability and high bone fill scores by X-ray and ultrasound, the distraction wound did not achieve normal stiffness at the end of neutral fixation in this model. This may have implications for the management of patients who undergo large movements by distraction.

Animals↗
PubMed2002

IGF-I, TGF-beta, and BMP-4 are expressed during distraction osteogenesis of the pig mandible.

The mechanisms that regulate bone formation during distraction osteogenesis (DO) are not completely understood. Our hypothesis is that local cytokines that stimulate osteoblast activity are potential regulators of this process. The purpose of this study was to determine gene expression of insulin-like growth factor I (IGF-I), transforming growth factor-beta (TGF-beta), and bone morphogenetic protein 4 (BMP-4) in distracted wounds. A semiburied, rigid distraction device was placed across an osteotomy at the right mandibular angle in 9 Yucatan minipigs. Distraction was begun immediately at a rate of 1 mm/day. The animals were sacrificed after 4 and 7 days of distraction, and after 7 days of distraction plus 4 days of neutral fixation. Excised wound tissues were processed for histologic and gene expression analyses. Competitive reverse-transcription polymerase chain reaction (RT-PCR) assays were developed and validated for porcine genes. Histologic analysis showed membranous ossification within the DO wound. Gene expression of IGF-I, TGF-beta and BMP-4 was detected during distraction and neutral fixation. These results show that gene expression analyses can be performed in a large animal model of mandibular DO. As the pig mandible closely resembles that of the human in morphology and physiology, this is an important step toward characterization of the early molecular events in the DO wound.

Animals↗
PubMed2002

Development of a three-dimensional treatment planning system based on computed tomographic data.

Current surgical treatment planning systems predict three-dimensional (3D) corrections from two-dimensional (2D) data and are inadequate for complex movements. In this paper, we present a 3D planning system based on computed tomographic (CT) data. A three-dimensional CT scan of the craniofacial skeleton forms the database. Software developed in the Harvard Surgical Planning Laboratory was modified for the craniofacial skeleton. Reproducible skeletal landmarks are identified for superimposition. A 'cutting tool' is used to segment the mandible and segments are moved to their predicted positions. A 'collision tool', alerts the operator of skeletal interferences. An analysis of selected scans is used to demonstrate the system. Three-dimensional visualization of the facial skeleton, selection of landmarks, measurement of angles and distances, simulation of osteotomies, repositioning of bones, detection of collisions and super-imposition of scans were accomplished. In an illustrative case of Hemifacial Microsomia, predicted and actual 3D corrective movements of the entire mandible were documented. Analysis of scans indicated that 3D planning can prevent insufficient jaw lengthening or other surgical inaccuracies which occur with standard 2D methods. Software demonstrated here will allow the surgeon to accurately plan treatment and evaluate craniomaxillofacial surgery outcomes. Future applications may include surgical navigation.

Algorithms↗
PubMed2001

Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.

PURPOSE: Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation. MATERIALS AND METHODS: Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA). RESULTS: Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%). CONCLUSIONS: The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.

Animals↗
PubMed2001

Endoscopic approach to the ramus/condyle unit: Clinical applications.

PURPOSE: The purpose of this report is to describe use of an endoscopic technique for exposure of the mandibular ramus/condyle unit (RCU) to facilitate reconstructive jaw procedures. PATIENTS AND METHODS: This is a retrospective evaluation of 10 patients with diagnoses of idiopathic condylar resorption (n = 2), subcondylar fracture (n = 5), mandibular prognathism (n = 1), condylar hyperplasia (n = 1), and mandibular asymmetry (n = 1), who underwent endoscopic exposure of the RCU. RESULTS: All 10 patients had successful reconstruction of the RCU using the endoscopic approach. The procedures performed included the following: condylectomy (n = 5 sides), costochondral graft reconstruction (n = 4 sides), reduction of subcondylar fracture (n = 5 sides), and mandibular ramus osteotomy (n = 4 sides). Mean operating time was 84 minutes. No patients had marginal mandibular nerve weakness or other complications. CONCLUSION: This case series demonstrates the feasibility of endoscopic access to the RCU. The procedures can be performed with no increase in operative time and with minimal morbidity.

Adolescent↗
PubMed2000

Effects of latency and rate on bone formation in a porcine mandibular distraction model.

PURPOSE: Long treatment protocols currently limit the application of distraction osteogenesis (DO). The purpose of this study was to develop a porcine model for DO and to define the effects of latency and distraction rate on bone formation. MATERIALS AND METHODS: Distractors were placed through submandibular incisions. For analysis of latency, mandibular osteotomies were distracted after 0 (n = 3) or 4 (n = 2) days at a rate of 1 mm/d (7 days) with 14 days fixation. For analysis of rate, osteotomies were distracted at 1 mm (n = 4), 2 mm (n = 4), or 4 mm (n = 4) per day to produce a 12-mm gap with 24 days fixation. DO wounds were assessed in vivo with bimanual palpation to detect mobility across the gap. Harvested specimens were evaluated by gross appearance and bimanual palpation. Standardized radiographic techniques were used to estimate bone density. RESULTS: During DO, animals showed normal activity. There were no infections, and no distractors were removed prematurely. Clinical and radiographic evaluation of the groups that underwent distraction after 0- or 4-day latency showed equivalent healing. In the comparison of distraction rates, stability was greatest in the group distracted at 1 mm/d. CONCLUSIONS: A porcine model for mandibular DO has been developed in which mandibular lengthening was successfully performed without latency and at a rate of 1 mm/d. The relationships among latency, gap size, rate, and duration of fixation are poorly understood and can be defined with relevant animal models.

Animals↗
PubMed2000

Extended genioplasty: long-term cephalometric, morphometric and sensory results.

The incision, dissection, osteotomy design and fixation are important technical considerations when performing a genioplasty. The purpose of this study was to describe an extended genioplasty technique and to evaluate stability of position, form, surface area of the chin and incidence of postoperative sensory deficit. Records of 15 consecutive adult patients who underwent the extended genioplasty procedure were reviewed. The technique included incision in the labial vestibule from 2nd premolar to 2nd premolar, dissection, mobilization and retraction of the mental nerves, osteotomy parallel to the occlusal plane extending proximally to the antegonial notch and rigid fixation. Lateral cephalograms pre- and postoperatively and at the latest follow-up (> 6 months) were analyzed by linear and computer morphometric measurements to evaluate changes in position, shape and surface area of the chin. Neurosensory data from examination or questionnaire were recorded. Immediately postoperatively (T1), mean advancement in the sagittal plane was +8.7 mm and increase in surface area was +1.1 cm2. At the end of follow-up (T2), there were no significant changes (T2-T1) in chin position or surface area. Inferior border form was rated as smooth in all cases. Neurosensory evaluation revealed that 12/12 patients evaluated had functional sensory return at T2.

Adult↗
PubMed2000

Minimally invasive orthognathic surgery: endoscopic vertical ramus osteotomy.

The endoscopic procedure for placement and activation of a distraction device for mandibular advancement has been previously reported. The purpose of this study was to demonstrate the feasibility of endoscopic exposure, dissection and osteotomy for mandibular set-back. Two cadaver and three anesthetized minipigs were used in this study. Access to the mandibular ramus was achieved through a 2.0 cm submandibular incision. The dissection was carried sharply to the mandible and completed in the subperiosteal plane. Visualization was achieved using a 2.7 mm diameter endoscope (Karl Storz, Germany). Landmarks were identified and a custom-made retractor was inserted into the sigmoid notch. A vertical ramus osteotomy was created (bilaterally) from the sigmoid notch to the mandibular angle. The mandible was set back (average 6 mm) and fixed using 2.0 mm diameter, bicortical screws. Live animals were sacrificed three weeks postoperatively. The mandibles were examined clinically and radiographically to verify proper osteotomy position and clinical union. In all animals, exposure, accurate identification of landmarks, osteotomy placement and screw fixation were achieved. In the live animals (n=3), union between the proximal and distal segments was documented by clinical and radiographic examination. This study demonstrates the feasibility of the EVRO procedure for mandibular set-back in a minipig model.

Animals↗
PubMed1999

Endoscopic mandibular osteotomy, and placement and activation of a semiburied distractor.

PURPOSE: The purpose of this study was to demonstrate the feasibility of endoscopic placement and activation of a semiburied distraction device in the porcine mandible. MATERIALS AND METHODS: Sixteen cadaver and two live anesthetized minipigs were used in this study. Access to the mandible was gained through two 1.0-cm submandibular incisions used for a working port and a visualization port. Under endoscopic visualization, dissection was carried sharply to the mandible and completed in the subperiosteal plane. Landmarks were identified through the endoscope, and a mandibular angle osteotomy was created. A semiburied distractor was then implanted, fixed to the mandible, and activated to create a bone gap. Finally, the site was explored through a submandibular incision to verify the accuracy of the endoscopic procedure. RESULTS: Endoscopic exposure; accurate identification of landmarks; creation of an osteotomy; and placement, fixation, and activation of a semiburied distractor were achieved in all 18 specimens. The inferior alveolar nerve was identified as the bone gap was expanded. CONCLUSION: The results of this study indicate that the endoscopic approach described here allows exposure and osteotomy of the mandible, and placement, fixation, and activation of a distractor. In the future, this technique will be used with totally buried, miniature distraction devices.

Animals↗
PubMed1999

Evaluation of a semiburied, fixed-trajectory, curvilinear, distraction device in an animal model.

PURPOSE: This study evaluated a new small, buried distractor, capable of curvilinear movement while following a fixed trajectory. The geometrical basis for such devices and the 3-dimensional treatment planning system required to make buried distractors practical are discussed. MATERIALS AND METHODS: A curved rack and worm-gear device, based on the design of a hose clamp, was constructed to produce a curved distraction path, and this distractor was tested in 2 minipigs using a protocol with zero latency and 1 mm/d x 7 days of distraction. Serial standardized lateral cephalograms were used to verify distractor function and path. RESULTS: Curvilinear distraction was documented by clinical examination and serial cephalometric analysis in the 2 minipigs. Observed angulation of the margins of the wedge-shaped distraction gap conformed to the calculated angulation based on the fixed radius of curvature of the distractor. CONCLUSION: Distraction along a curved trajectory using a small, semiburied, curvilinear device of novel design is feasible in the minipig mandible.

Animals↗
PubMed1998

Dental extractions in patients on an oral anticoagulant: a survey of practices in North America.

PURPOSE: The World Health Organization (WHO) recommends the use of the International Normalized Ratio (INR) for reporting prothrombin time (PT) values. However, there are no scientifically based guidelines for performing dental extractions when using the INR. Oral and maxillofacial surgeons were surveyed to determine whether the INR is the method they use to monitor the level of anticoagulation and to determine what protocols are followed when anticoagulated patients require dental extractions. MATERIALS AND METHODS: A mail survey of academic oral and maxillofacial surgeons in North America was conducted to determine their choice of laboratory tests for assessing patients on oral anticoagulants and their protocol before proceeding to dental extractions. RESULTS: Fifty-three of 73 respondents (73%) routinely use the INR, but only 21% rely on this method alone. Twelve percent and 11% of respondents, respectively, also use the PT value and PT ratio. The level of anticoagulation at which surgeons would proceed with dental extractions was variable. For those using the INR, it was from 1.3 to 4.0, for those using PT ratios the perceived safe range was from 1.0 to 2.0, and for those using the PT value, the range was from 13 to 21 sec. CONCLUSIONS: Despite the support in the medical literature for use of the INR, many oral and maxillofacial surgeons still use the PT for monitoring oral anticoagulant therapy. There is no consensus on the INR interval at which dental extractions can be safely performed. Prospective studies are needed in this area.

Administration, Oral↗
PubMed1996

What is the INR?

The World Health Organization (WHO), the International Committee for Thrombosis and Hemostasis, and the International Committee for Standardization in Hematology, have strongly suggested that INR (International Normalized Ratio) values should be used to report a patient's level of coagulation. This paper discusses the use of the INR to monitor a patient's coagulation level, and reviews the recommendations on the INR levels at which dental extractions and similar oral surgical procedures may be performed safely. Studies are needed to determine whether new local hemostatic agents are sufficient for the safe management of patients at higher INR levels, thereby avoiding the need for hospitalization and heparin therapy.

Anticoagulants↗