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Maria J Troulis

Publications and source records attributed to Maria J Troulis.

At least 19 recordsLinked to original sources
PubMed2006

The engineering of craniofacial tissues in the laboratory: a review of biomaterials for scaffolds and implant coatings.

Tissue engineering is a rapidly growing interdisciplinary field that focuses on the interactions between cells, growth factors, and scaffolds to produce replacement tissue and organs. Recent developments in tissue engineering technology include refinements in isolation and differentiation of progenitor cells, 3-D printing technology to produce scaffolds, new biomaterials for scaffolds, and growth factor delivery systems. The purpose of this article is to review advances in biomaterials, scaffolds, and implant coatings for craniomaxillofacial (bone) tissue engineering.

Absorbable Implants↗
PubMed2006

Endoscopic approach for mandibular orthognathic surgery.

The field of minimally invasive surgery is defined as the combination of surgical innovation with modern technology. This article describes the history of surgery and newer developments in endoscopic surgery for mandibular orthognathic surgery.

Endoscopy↗
PubMed2006

Microscopic changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.

PURPOSE: Unilateral mandibular distraction osteogenesis (DO) has been shown to cause gross changes in the mandibular condyle and articular disc. The purpose of this study was to correlate histologic findings with these gross changes in a minipig distraction model. MATERIALS AND METHODS: Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0-day latency and rates of 1, 2, or 4 mm/day for a 12-mm gap. After the minipigs were killed (at 0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested, decalcified, prepared for standard paraffin embedding, and evaluated to determine changes in 1) morphology and thickness of the articular cartilage and subchondral bone and 2) morphology of the disc. RESULTS: In control animals, there were no degenerative changes in the articular cartilage and underlying condylar bone; there were no significant differences in the mean articular cartilage thickness. The temporomandibular joint discs were normal. In experimental animals, distracted condyles showed increasing degenerative changes and mean articular cartilage thickness as the DO rate increased. The discs were thinner. These changes were present, but to a lesser degree, in the contralateral condyles. After 90 days, degenerative changes in the condyles and discs were reduced, after remodeling, except in the 4 mm/day DO group. CONCLUSIONS: Histologic changes in the condyles and temporomandibular joint discs in response to mandibular DO correlated with previously reported gross changes. These changes were greater at higher distraction rates and remodeling back to normal occurred in mandibular condyles distracted at 1 mm/day.

Animals↗
PubMed2006

Range of curvilinear distraction devices required for treatment of mandibular deformities.

PURPOSE: The purpose of this study was to determine the range of fixed trajectory curvilinear distraction devices required to correct a variety of severe mandibular deformities. MATERIALS AND METHODS: Preoperative computed tomography (CT) scans from 18 patients with mandibular deformities were imported into a CT-based software program (Osteoplan). Three-dimensional virtual models of the individual skulls were made with landmarks to track movements. An ideal treatment plan was created for each patient. Upper and lower boundaries for the dimensions of curvilinear distractors were established based on manufacturing and geometric constraints. Then, anatomically acceptable distractor attachment points were identified on the models using proximal and distal grids. Treatment plans were simulated for a series of distractors with varying radii of curvature, elongations (arc-length of device), and placements along the grids. The outcomes using these distractors were compared with the ideal treatment plans. Discrepancies were quantified in millimeters by comparing landmarks in the simulated versus ideal movements. RESULTS: Approximately 400,000 simulated 3-dimensional movements, based on the distractor parameters and variations in placement were computationally evaluated for the 18 cases. It was determined that, by varying distractor placement, a family of 5 distractors, with 3, 5, 7, and 10 cm radii of curvature and a straight-line device, could be used to treat all 18 cases to within 1.8 mm of error. CONCLUSIONS: The results of this study indicate that a family of 5 curvilinear distractors may suffice to treat a broad range of mandibular deformities.

Computer Simulation↗
PubMed2006

Effect of interferon-alpha-2b on porcine mesenchymal stem cells.

PURPOSE: Patients undergoing enucleation and adjuvant interferon therapy for giant cell jaw tumors have been observed to exhibit exuberant bone formation in the resultant defects. We hypothesize that interferon promotes bone formation by enhancing mesenchymal stem cell (MSC) differentiation and by stimulating osteoblasts. This is a preliminary study to determine the effects of interferon on porcine mesenchymal stem cells (pMSCs) in culture. MATERIALS AND METHODS: Isolated pMSCs were grown under the following conditions: 1) MSCs alone (negative control); 2) MSCs + osteogenic supplements (positive control); and 3) MSCs + interferon (experimental). Cell cultures were evaluated morphologically, by quantitative DNA analysis, and quantitative and qualitative alkaline phosphatase analysis. RESULTS: Cells treated with interferon exhibited a slower but constant proliferation rate, did not clump, and produced more alkaline phosphatase as compared with the negative control. CONCLUSION: The data indicate that interferon may act to differentiate MSCs into osteoblasts and to stimulate metabolic activity while not increasing the proliferation rate.

Alkaline Phosphatase↗
PubMed2005

Hydrogel-beta-TCP scaffolds and stem cells for tissue engineering bone.

Trabecular bone is a material of choice for reconstruction after trauma and tumor resection and for correction of congenital defects. Autologous bone grafts are available in limited shapes and sizes; significant donor site morbidity is another major disadvantage to this approach. To overcome these limitations, we used a tissue engineering approach to create bone replacements in vitro, combining bone-marrow-derived differentiated mesenchymal stem cells (MSCs) suspended in hydrogels and 3-dimensionally printed (3DP) porous scaffolds made of beta-tricalcium-phosphate (beta-TCP). The scaffolds provided support for the formation of bone tissue in collagen I, fibrin, alginate, and pluronic F127 hydrogels during culturing in oscillating and rotating dynamic conditions. Histological evaluation including toluidine blue, alkaline phosphatase, and von Kossa staining was done at 1, 2, 4, and 6 weeks. Radiographic evaluation and high-resolution volumetric CT (VCT) scanning, expression of bone-specific genes and biomechanical compression testing were performed at 6 weeks. Both culture conditions resulted in similar bone tissue formation. Histologically collagen I and fibrin hydrogels specimens had superior bone tissue, although radiopacities were detected only in collagen I samples. VCT scan revealed density values in all but the Pluronic F127 samples, with Houndsfield unit values comparable to native bone in collagen I and fibrin glue samples. Expression of bone-specific genes was significantly higher in the collagen I samples. Pluronic F127 hydrogel did not support formation of bone tissue. All samples cultured in dynamic oscillating conditions had slightly higher mechanical strength than under rotating conditions. Bone tissue can be successfully formed in vitro using constructs comprised of collagen I hydrogel, MSCs, and porous beta-TCP scaffolds.

Alginates↗
PubMed2005

Analysis of skeletal movements in mandibular distraction osteogenesis.

PURPOSE: The purpose of this study was to use geometric parameters of movement, calculated from 3-dimensional computed tomography (CT) data, to determine the curvilinear distractor dimensions required to correct mandibular deformities in a series of patients. MATERIALS AND METHODS: Preoperative CT scans from 15 patients with symmetric (n = 5) and asymmetric (n = 10) deformities were imported into a CT-based software program (Osteoplan; an open-source visualization application developed by Gering et al at the Surgical Planning Laboratory [SPL, Brigham and Womens Hospital, Boston, MA]). The software was used to reconstruct virtual 3-dimensional models from these scans. Two experienced surgeons, working with a computer scientist, then used Osteoplan to create an ideal treatment plan for each patient. In each case, the 3-dimensional curvilinear movement was quantified using 4 "parameters of movement" (POMs). These parameters were then used to prescribe a distraction device capable of executing the planned skeletal correction. Curvilinear distractor dimensions calculated by Osteoplan included the radius of curvature of the prescribed device, and the distractor elongation, pitch, and handedness. RESULTS: Treatment plans including POMs were developed for each patient. The radii of curvature for the prescribed distractors ranged from 2.3 to 14.1 cm, the distractor elongation dimensions ranged from 0.7 to 3.2 cm, and the pitch (horizontal plane) dimensions ranged from 0.005 to 0.8 cm. Handedness was either a left (n = 12) or right (n = 8) turning helix. CONCLUSION: The results of this study indicate that, using geometric parameters of movement calculated from 3-dimensional CT scans, curvilinear devices could be prescribed for correction of the range of skeletal deformities in this group of patients.

Computer Simulation↗
PubMed2005

Synovial chondromatosis of the temporomandibular joint: report and analysis of eleven cases.

PURPOSE: Synovial chondromatosis (SC) is a benign monoarticular condition that is uncommon in the temporomandibular joint (TMJ). The purpose of this article is to present 11 additional cases of SC of the TMJ and discuss newer modes of imaging, diagnostic approaches, treatment options, and follow-up data. METHODS: Medical records of 11 patients with SC treated within our department from 1991 to the present were reviewed. Demographic data, etiology, clinical presentation, diagnostic evaluation, treatment, and follow-up information were collected. Previously reported cases (both TMJ and others) from 1988 to present were identified for comparison and the literature reviewed. RESULTS: There were 8 females and 3 males with an average age of 54 years. Pain and preauricular swelling were the most common presenting clinical complaints. Etiologic factors (parafunction, inflammatory joint disease) were found in 7 of 11 cases. Plain radiographs showed joint calcifications in only 2 of 11 cases. Computed tomography identified calcifications in 3 of 6. Magnetic resonance imaging clearly demonstrated the mass and its extension in 10 of 10 cases. Fine needle aspiration was diagnostic in 4 of 9. All patients were treated with an open arthrotomy. Meniscectomy was required in 7 of 11. Average follow-up was 5.2 years with no recurrences reported. CONCLUSION: The current case series of SC shows a female predilection with age and presenting complaints similar to those previously reported. A traumatic etiology was not identified, although a weak association is reported in the literature. The superiority of magnetic resonance imaging for both diagnosis and evaluation of extension of disease is shown. In a subset of cases, fine needle aspiration is useful for confirming the clinicoradiographic impression. Complete removal of involved tissue is associated with an excellent prognosis.

Adult↗
PubMed2005

Mandibular advancement by distraction osteogenesis for tracheostomy-dependent children with severe micrognathia.

PURPOSE: The purpose of this study was to evaluate mandibular lengthening by distraction osteogenesis (DO) to achieve decannulation of micrognathic children with "permanent" tracheostomies. PATIENTS AND METHODS: Using a retrospective chart review, patients were included who had 1 ) airway compromise/tracheostomy, 2 ) micrognathia, 3 ) polysomnography-documented obstructive apnea, and 4 ) mandibular advancement using DO. Excluded were 1 ) adults, 2 ) neonates without tracheostomy, and 3 ) patients with central apnea. Patient age, past medical history, age at tracheostomy, and distraction protocol were documented. Oxygen saturation, posterior airway space (in millimeters), and sella-nasion-B point (SNB) angle were recorded. The distraction protocol consisted of a latency of 48 hours and a rate of 1 mm/day. RESULTS: There were 5 children, aged 2 to 14 years, who received a tracheostomy between ages 2 and 36 months for airway obstruction. All patients underwent bilateral mandibular distraction using semiburied, unidirectional devices. The average latency was 58 hours, the rate was 1 mm/day, the duration of fixation was 40 to 60 days, and the magnitude of advancement was 23 mm. Healing was evaluated by clinical, radiologic, and ultrasound examinations. No complications were experienced. Mean follow-up was 3.2 years. Postdistraction sleep studies demonstrated no obstructive apneic events and a mean oxygen saturation of 98% (preoperative, 76%, P < .005). Cephalometric values improved: posterior airway space 4 to 14 mm; SNB 66 degrees to 72 degrees ( P < .005 for both variables). Four of the 5 patients have been successfully decannulated to date. CONCLUSIONS: The results of this preliminary study indicate that mandibular advancement by DO is a potentially viable treatment option for tracheostomy-dependent children with upper airway obstruction secondary to micrognathia.

Adolescent↗
PubMed2004

Staged protocol for resection, skeletal reconstruction, and oral rehabilitation of children with jaw tumors.

PURPOSE: The purpose of this study was to evaluate a staged protocol for resection of jaw tumors and reconstruction including implants in pediatric patients. PATIENTS AND METHODS: Nine children were evaluated retrospectively. Data included age at resection, tumor type, use of adjuvant therapy, type of bone graft, and number of implants. Occurrence of postoperative infection, tumor margins, recurrence, plate fractures, number of bone grafts, implants restored, and failures were recorded. RESULTS: Ages ranged from 3.5 to 16 years with 2 maxillary and 7 mandibular tumors. Diagnoses included giant cell lesion (n = 3), osteosarcoma (n = 2), myofibroma (n = 1), ossifying fibroma (n = 1), desmoplastic fibroma (n = 1), and ameloblastoma (n = 1). No patients experienced postoperative infection, wound dehiscence, or jaw instability after en bloc resection. One patient had recurrence of a giant cell lesion. To date (mean, 56 months; range, 24 to 93 months), there have been no additional recurrences. There was 1 plate fracture. Eight patients underwent iliac bone grafts (stage 2), and in 1 patient, the mandible regenerated. There were no graft infections or wound dehiscences. Three patients required additional bone grafting for implant placement. Twenty-three implants were placed in 7 patients without complications, and 21 implants have gone to second stage. One implant failed to osseointegrate. Six patients have had prostheses placed and loaded for a mean of 26 months (range, 5 to 64 months). One patient is scheduled for prosthetic restoration and 2 for implant placement. CONCLUSION: Pediatric maxillofacial tumors can be successfully treated by resection, rigid fixation, and delayed reconstruction with minimal morbidity and a high success rate.

Adolescent↗
PubMed2004

Endoscopic mandibular condylectomy and reconstruction: early clinical results.

PURPOSE: The purpose of this study was to evaluate early outcomes in patients who underwent endoscopic condylectomy and costochondral graft reconstruction (CCG) of the ramus/condyle unit (RCU). PATIENTS AND METHODS: A retrospective evaluation of 10 consecutive patients who underwent endoscopic condylectomy and CCG (n = 17 sides) for the treatment of idiopathic condylar resorption (n = 7), degenerative joint disease (n = 1), and malunion of a fractured condyle (n = 2) was completed. Patients were included who had 1) adequate documentation after endoscopic condylectomy and CCG reconstruction and 2) a minimum of 6-months follow-up. Patients with inadequate documentation or follow-up were excluded. The surgical technique included a 1.5-cm incision inferior to the mandibular angle. Blunt dissection was carried to the masseter muscle, which was incised using needle point electrocautery. An optical cavity was created for insertion of a Hopkins (Karl Storz, Culver City, CA) endoscope. The resection and reconstruction were carried out with endoscopic instrumentation. Preoperative (T0), postoperative (T1), and follow-up (T2) clinical examinations, lateral cephalograms, and panoramic radiographs were used to evaluate the outcomes. RESULTS: In all 10 cases, condylectomy and CCG reconstruction (n = 17 sides) were successfully performed using the endoscopic approach. The mean follow-up period was 17 months (range, 8 to 38 months). All submandibular scars were aesthetically satisfactory, and there were no facial, inferior alveolar, or lingual nerve injuries. No other intraoperative or postoperative complications occurred. Postoperative RCU length, mandibular position, and correction of the occlusion were documented using lateral cephalometric and panoramic radiographs. CONCLUSION: The results of this study indicate that endoscopic condylectomy and CCG reconstruction produce satisfactory clinical outcomes without significant morbidity. Long-term follow-up studies are in progress.

Adult↗
PubMed2004

Reconstruction of mandibular defects with autologous tissue-engineered bone.

PURPOSE: Maxillofacial reconstructive procedures often require bone graft harvesting, which results in donor site morbidity; the use of tissue-engineered bone would eliminate this problem. In this study, a novel scaffold design and new fabrication protocol were used to produce autologous tissue-engineered constructs (scaffolds seeded with cells) to reconstruct segmental mandibular defects in a minipig model. MATERIALS AND METHODS: Porcine mesenchymal stem cells were isolated from the ilium. They were expanded in culture and seeded onto poly-dl-lactic-coglycolic acid scaffolds. The constructs were placed in a bioreactor and incubated for 10 days in medium and osteogenic supplements. Four full-thickness bony defects (2 x 2 cm) were created in the same pig's mandible. The constructs (n = 2) were placed into 2 of the defects as autologous grafts. One unseeded scaffold and 1 empty defect served as controls. At 6 weeks postimplantation, the pig was sacrificed, the mandible was harvested, and the grafted sites were evaluated by clinical, radiographic, and histologic methods. RESULTS: The construct-implanted defects appeared to be filled with hard tissue resembling bone, whereas controls were filled with fibrous tissue. Radiographically, the tissue-engineered constructs were uniformly radiodense with bone distributed throughout. The interface between native bone and constructs was indistinct. Complete bone ingrowth was not observed in control defects. Osteoblasts, osteocytes, bone trabeculae, and blood vessels were identified throughout the defects implanted with constructs. CONCLUSION: This "proof-of-principle" study indicates that porcine mandibular defects can be successfully reconstructed by in vitro cultured autologous porcine mesenchymal stem cells on a biodegradable polymer scaffold with penetration of bone and blood vessels.

Animals↗
PubMed2004

Endoscopic vertical ramus osteotomy: early clinical results.

PURPOSE: The benefits of minimally invasive surgery have been well documented. The purpose of this report was to present early results in a series of patients who had endoscopic mandibular orthognathic surgery. Patients and methods This is a retrospective evaluation of 14 patients who underwent endoscopic vertical ramus osteotomy and rigid fixation for the treatment of mandibular prognathism (n = 9), malocclusion secondary to trauma (n = 3), or other pathology (n = 2). A 1.5-cm incision was made directly below the mandibular angle. The dissection was continued bluntly to the masseter muscle, which was incised using a needlepoint electrocautery. Then, with endoscopic elevators, an optical cavity was created for insertion of a Hopkins endoscope and visualization of the ramus/condyle unit. Anatomic landmarks were identified and the operation carried out with specially designed endoscopic equipment. Preoperative (T0), postoperative (T1), and follow-up (T2) clinical examinations; lateral cephalograms; and panoramic radiographs were used to evaluate the outcomes. RESULTS: The procedures performed included: vertical ramus osteotomy (n = 13 patients, 23 sides) and condylectomy plus vertical ramus osteotomy (n = 1 patient, 1 side). Mean operating time was 37 minutes per side. One patient had temporary marginal mandibular nerve weakness. The occlusal result was as planned in all cases. Panoramic radiographs documented postoperative ramus/condyle unit position and lateral cephalograms documented mandibular position. CONCLUSIONS: The results of this case series indicate that endoscopic vertical ramus osteotomy with rigid fixation is feasible for correction of a variety of mandibular deformities.

Adolescent↗
PubMed2003

Ultrasound: assessment of the distraction osteogenesis wound in patients undergoing mandibular lengthening.

PURPOSE: Common methods of assessment of the clinical distraction osteogenesis (DO) wound consist of serial physical examinations, plain radiographs, and computed tomography (CT). Ultrasound (US) is an inexpensive and efficient method of imaging that provides detailed assessment of bone formation across a defect. It has proved to be useful for the evaluation of long bone DO healing. The purpose of this study was to determine the efficacy of US for evaluation of bone formation in the mandibular distraction wound. PATIENTS AND METHODS: Ten patients underwent mandibular expansion (18 sides) with semiburied, unidirectional distraction devices. The wounds were assessed with plain radiographs and US immediately before device removal. Estimates of bone formation, using a semiquantitative bone fill score, were made for plain radiographs and US. US beam penetration depth, in millimeters, was also measured. During removal of the distraction device, bone formation and mandibular stability were assessed by the surgeon and graded on a semiquantitative scale. RESULTS: US bone fill scores correlated with intraoperative assessment of bone formation and stability (r = 0.758, P =.0018) at all 18 mandibular sites. Plain radiographic scores also correlated with bone formation (r = 0.592). However, in 14 of 18 sides, plain radiographs underestimated bone formation compared with US and operative findings. CONCLUSION: The results of this study indicate that US is an accurate noninvasive technique that may prove to be useful in assessing the mandibular DO regenerate in patients.

Adolescent↗
PubMed2003

Formation of a mandibular condyle in vitro by tissue engineering.

PURPOSE: Mandibular reconstructive procedures often produce significant donor site morbidity. Recently, the use of minimally invasive techniques has been reported for mandibular reconstruction with decreased morbidity at the primary operative site. To date, these techniques have not addressed the graft donor site. We hypothesize that tissue-engineering techniques may be used to fabricate bone and thereby eliminate donor site morbidity. METHODS: Porcine mesenchymal stem cells (pMSCs) were isolated from the bone marrow of 3 Yucatan minipigs and grown in standard culture flasks. When they became near-confluent, cells were detached and replated with the addition of osteogenic supplements. A model of a porcine mandibular condyle was made and used to fabricate porous polymer scaffolds from biodegradable poly DL-lactic-co-glycolic acid (PLGA). Differentiated osteoblasts were transferred to the PLGA scaffold and cultured for 6 weeks in a rotational oxygen-permeable bioreactor system. The cultured constructs, consisting of scaffold and cells, were evaluated by gross, radiologic, and histologic examinations. RESULTS: The engineered constructs were white and hard and had a shape that closely resembled that of the model condyle. Plain radiographs demonstrated that the radiodensity of the construct was between that of the normal condyle and that of control scaffolds. Histologically, bone was observed on the entire surface of the PLGA scaffolds with an average thickness of 0.03 mm. Bone was not observed in the control scaffolds. CONCLUSION: In this pilot study, autologous tissue-engineered bone constructs were successfully made by combining biodegradable polymers and pMSCs.

Alkaline Phosphatase↗
PubMed2003

Dedifferentiation of odontogenic keratocyst epithelium after cyst decompression.

PURPOSE: Cytokeratin-10 expression by cystic epithelium has been shown in the suprabasilar layers of odontogenic keratocyts (OKCs) but not in dentigerous cysts. Cyst decompression and irrigation result in the loss of keratinization. In this study, we used cytokeratin-10 antibody staining to evaluate changes in OKC epithelium to determine if decompression/irrigation treatment results in an epithelial modulation that may be associated with lower long-term recurrence. METHODS: Fourteen OKCs were exteriorized by removal of mucosa and bone. An irrigation port was placed into the cyst for twice-daily irrigations. At 3-month intervals, panoramic radiographs were obtained and cyst-lining cells were sampled and stained for cytokeratin-10. Residual cystectomy was performed when necessary based on clinical and radiographic criteria, and the lining was evaluated by histologic and immunohistochemical examination. RESULTS: There were 6 males and 8 females with a mean age of 32 years. Ten cysts were mandibular, and 4 were maxillary. Average duration of irrigation was 8.4 months (range, 6 to 12 months), and the mean shrinkage of the radiolucency was 65% (range, 5% to 91%). All cytologic samples obtained at 3 and 6 months contained cytokeratin-10-positive epithelial cells. At the time of cystectomy, 9 of 14 cases were cytokeratin-10 negative and no longer showed histologic features of OKCs. Specimens from the remaining 5 patients were histologically consistent with OKC and were cytokeratin-10 positive. Mean treatment time of the cytokeratin-10-positive group was 7 months, and that of the cytokeratin-10-negative group was 9 months. CONCLUSION: Epithelial dedifferentiation and loss of cytokeratin-10 production were observed in 64% of patients treated by cyst decompression/irrigation after a 9-month average treatment time. Longitudinal follow-up of these patients will determine whether this change is associated with lower rates of recurrence than alternative OKC therapy.

Adolescent↗