Reconstruction of the temporomandibular joint with cryopreserved cartilage and freeze-dried dura: a preliminary report

Bone marrow-derived mesenchymal stem cells enhance cryopreserved trachea allograft epithelium regeneration and vascular endothelial growth factor expression

BACKGROUND

Epithelium regeneration and revascularization of tracheal implants are challenging issues to be solved in tracheal transplantation research. Bone marrow-derived mesenchymal stem cells (BMSCs) can migrate to the damaged tissue and promote functional restoration. Here, we applied intravenous transplantation of BMSCs combined with a cryopreserved allograft to investigate the role of BMSCs in enhancing implant survival, tracheal epithelium regeneration and revascularization.

METHODS

After transplantation with cryopreserved allografts, PKH-26 labeled 3 to 5 passage BMSCs were injected into recipient rats through the tail vein. Rats in the control groups were injected with a comparable amount of phosphate-buffered saline. We observed the histology of the tracheal allograft and measured vascular endothelial growth factor (VEGF) protein levels in the epithelium to evaluate the effect of BMSCs on epithelium regeneration and revascularization.

RESULTS

Histologic observation of the rats from the BMSCs injection groups showed that the tracheal lumen was covered by pseudostriated ciliated columnar epithelium. The cartilage structure was intact. There were no signs of denaturation or necrosis. PKH-26 labeled BMSCs migrated to the implant site and exhibited red fluorescence, with the brightest red fluorescence at the anastomotic site. VEGF protein levels in the allograft epithelium of the BMSCs injection group were higher than the levels in the phosphate-buffered saline injection group.

CONCLUSIONS

Our results indicate that given systemic administration, BMSCs may enhance epithelium regeneration and revascularization by upregulating VEGF expression.

Block and Surgicel-wrapped diced solvent-preserved costal cartilage homograft application for nasal augmentation

BACKGROUND

Cartilage grafting has been used extensively to correct the nasal framework in traumatic and postrhinoplasty nasal deformities. Autologous cartilage grafts yield satisfactory reconstructive results, but their use is limited by donor-site morbidity, patient choice, the requirement for increased operative time, and the lack of a sufficient quantity and availability of tissue for more extensive deformities. Alternatively, preserved costal cartilage homograft represents a readily available, easily contoured material.

METHODS

The preserved costal cartilage homograft has been used by the authors on 68 patients over the past 5 years: in 52 patients with postrhinoplasty deformity and in 16 patients with traumatic nasal deformity. In cases with more severe nasal depression, the cartilage graft was carved and placed over the remaining septum in block form. The "Turkish Delight" technique, which was initially described by Erol, was used in cases of mild to moderate nasal depression. The cartilage graft was diced into 0.5- to 1-mm pieces. The diced cartilage mass was then wrapped in Surgicel and inserted under the dorsal nasal skin.

RESULTS

Follow-up ranged from 6 months to 5 years. During this period, no major complications were noted, and satisfactory results were obtained. Recurrence of the dorsal depression was seen in five patients and required repeated augmentation. The complication and revision rates were acceptable.

CONCLUSIONS

This technique seems to be effective for augmentation of the nose, shortens the operative time significantly by eliminating graft harvest, and avoids donor-site morbidity. Therefore, it is recommended for nasal augmentation and contouring for traumatic and postrhinoplasty nasal deformities.

Preserved costal cartilage homograft application for the treatment of temporomandibular joint ankylosis

Ankylosis of the temporomandibular joint has been a daunting problem in oral and maxillofacial surgery. Condylectomy with gap arthroplasty is the basic technique for treatment of the fully grown patient. In the past, reconstruction has primarily been accomplished with alloplastic materials or with autogenous tissue harvested from the patient. Joints reconstructed with alloplastic materials have been subject to complications such as acute infection and chronic inflammatory problems as a result of foreign-body reaction with the immune system. Biologic reconstruction with autogenous materials does expose the patient to the risk of complications at the donor site. In the last 4 years, we have treated seven patients between the ages of 20 and 42 years who had complete temporomandibular joint ankylosis. In each patient, the affected joint was exposed through an extended preauricular incision. The ankylosed mandibular condyle with the surrounding abnormal bone, together with the coronoid process, was resected and removed. The ankylosed area was resected until an improvement of at least 15 mm in the interincisal opening distance was obtained. A solvent-preserved homologous cartilage graft was sculpted according to the size and shape of the gap and was then placed in it as interpositional material. Physical therapy, including active and passive mouth-opening exercises, began on the second postoperative day and continued for 6 months. Patients were observed for 6 months to 4 years. During this period, no major complications were noted, and satisfactory results were obtained. The initial mean interincisal opening distance was 15.2 mm after surgery, and the final mean interincisal opening distance was 32 mm after completion of physiotherapy. No recurrence was seen during the 4 years of follow-up. This technique seems to be an effective, time-saving, and simple alternative to other methods of joint reconstruction in adults who have fairly extensive ankylosis of the temporomandibular joint. In this article, a description of the surgical technique, a review of all cases, and recommendations for the use of this type of graft material are discussed. Our clinical experience over the past 4 years with the use of preserved homologous costal cartilage grafts as interpositional material has been encouraging.

Cartilaginous injury limits cryopreservation of tracheal isograft

OBJECTIVE

Histological recovery of tracheal grafts after cryopreservation was investigated using a rat heterotopic tracheal transplant model in order to evaluate the clinical applicability of tracheal cryopreservation.

METHODOLOGY

Heterotopic syngeneic tracheal transplantation was performed between F344 rats. Recipient animals received either a non-cryopreserved or a cryopreserved tracheal graft for direct comparison with regard to the effect of cryo-injury. In the non-cryopreserved group (CP(-)), tracheal segments were transplanted syngeneically between F344 rats immediately after harvest. Grafts were implanted into the abdominal space and wrapped with the greater omentum. In the cryopreserved group (CP(+)), grafts were implanted after cryopreservation for 7 days at -85 degrees C. Recipient rats were killed on days 7, 14, 21, 28, and at 2 months after surgery. Epithelial regeneration and cartilage changes were evaluated using a semiquantitative four grade scoring system.

RESULTS

Squamous epithelium without ciliated structure was observed on day 7 in both groups. Bronchial epithelium was then regenerated gradually and normally ciliated epithelium was observed on day 28 in both groups. The condition of the epithelium was still well maintained in the CP(-) group at 2 months post-transplantation; however, a severe epithelial defect was observed in the CP(+) group. Bronchial cartilage showed a normal shape and mostly viable chondrocytes with proliferative cell nuclear antigen (PCNA) positive staining at all time points in the CP(-) group until 2 months after surgery. However, in the CP(+) group, a massive loss of viable chondrocytes was observed at 2 months post-transplantation. Macroscopically, CP(+) grafts showed a diminished structure without satisfactory airway lumen at 2 months.

CONCLUSION

The epithelium of a tracheal graft can be temporarily recovered after implantation followed by 7 days cryopreservation. However, bronchial cartilage may be severely damaged by freezing, which results in late destruction with loss of viable chondrocytes. It is suggested here that establishing a method of safe cryopreservation for tracheal cartilage will be imperative to making tracheal cryopreservation possible.

Revascularization of canine cryopreserved tracheal allografts

BACKGROUND

We examined the blood supply of a cryopreserved tracheal allograft and its morphohistologic changes after transplantation.

METHODS

In each of 22 dogs, a five-ring tracheal segment was replaced by one of the following tracheal grafts: fresh autografts (n = 8), cryopreserved tracheal allografts (n = 8), or fresh allografts (n = 6). The cryopreserved tracheal allografts were preserved at -196 degrees C for 60 days. No immunosuppressant was given to any of the animals. All grafts were retrieved at 1 and 12 weeks and assessed by microangiography and histology.

RESULTS

The epithelial denudation and the revascularization of the transverse intercartilaginous arteries were recognized within 7 days as common to each of the three types of grafts. In the cryopreserved tracheal allografts, neither cartilage degradation nor graft shrinkage occurred at 7 days. However, the recanalized transverse intercartilaginous arteries completely disappeared at 12 weeks, and marked shrinkage occurred; the cartilage cells were accompanied by karyolysis and were significantly decreased in number (p < 0.05). Recanalization of the transverse intercartilaginous arteries was also demonstrated in the fresh allografts; however, necrosis abruptly occurred as a result of acute rejection responses.

CONCLUSIONS

Cryopreservation of a tracheal allograft provided sufficient reduction of the acute rejection responses, and blood supply to the cryopreserved tracheal allograft was established through the recanalized transverse intercartilaginous arteries within 7 days; however, subsequent chronic rejection responses resulted in occlusion of the transverse intercartilaginous arteries and atrophy.

Maximal period of cryopreservation with the Bicell biofreezing vessel for rat tracheal isografts

OBJECTIVE

The maximal period of cryopreservation for the trachea is still unsolved. We assessed the maximal period of cryopreservation using the Bicell biofreezing vessel as an easy and cheap slow-freezing instrument for viable tracheal grafts in 95 rats.

METHODS

Each isograft was harvested from 17 donor rats, immersed in the preservative solution, and stored in a Bicell device in a deep freezer at -80 degrees C. The tracheal isografts were then randomly assigned to 9 groups according to cryopreservation periods ranging from 0 to 12 months. Included in the 9 groups were 2 subgroups (n = 6 per subgroup) that were observed immediately after being thawed and 1 month after heterotopic transplantation into the omentum after being thawed. Four subgroups (n = 6 per subgroup) were added according to the cryopreservation period for 1, 3, 6, and 12 months to evaluate the graft morphology 3 months after being thawed and transplanted heterotopically.

RESULTS

A prolonged period of cryopreservation had a degenerative effect on both the epithelium and cartilage. One month after transplantation, degeneration was more pronounced in the cartilage than in the epithelium, as characterized by the viable chondrocyte ratio and the epithelial score of isografts undergoing cryopreservation for more than 9 months. Three months after transplantation, the morphology of the epithelium and cartilage in isografts undergoing cryopreservation for less than 3 months was better preserved, whereas the morphology of both deteriorated in isografts undergoing cryopreservation for more than 6 months.

CONCLUSIONS

We conclude that the permissible period of cryopreservation to maintain tracheal isograft viability in this simple system using a Bicell biofreezing vessel is 3 months.

Experimental study of tracheal allotransplantation with cryopreserved grafts

OBJECTIVE

Tracheal reconstruction is necessary in patients with extensive tracheal stenosis caused by neoplasm, trauma, and congenital disease. We investigated the possibility of tracheal allotransplantation with cryopreserved grafts in a canine model.

METHODS

A seven-ring section of thoracic trachea was removed in 19 adult mongrel dogs. In group A (n = 4), a five-ring tracheal autograft was implanted. In group B (n = 6), a five-ring allograft was implanted without immunosuppression. In group C (n = 9), a five-ring cryopreserved tracheal allograft was implanted without immunosuppression. Omentopexy wrapping around the grafts and both anastomotic sites was used in all animals.

RESULTS

All grafts survived without any evidence of atrophy or stenosis in group A. All animals in group B died of severe airway obstruction within 1 month, and postmortem examination of these grafts showed epithelial defect and necrotic tracheal cartilage in the scar tissue. In group C, no animals died of asphyxia caused by severe stenosis of the grafts. The graft epithelium was no longer present 20 days after transplantation, and the graft was covered with regenerated epithelium within about 60 days after the operation.

CONCLUSION

These findings show that cryopreserved tracheal allografts can be transplanted by means of omentopexy without immunosuppression and that cryopreservation may reduce tracheal allogenicity.

Reconstruction of the temporomandibular joint using a temporalis graft with or without simultaneous orthognathic surgery

PURPOSE

This article reports the outcome of free temporalis fascia and muscle graft (TFG) reconstruction of the temporomandibular joint (TMJ) with and without simultaneous orthognathic surgery (SOS).

MATERIALS AND METHODS

Twenty-nine patients (45 joints) were evaluated retrospectively. Group 1 consisted of 17 patients (16 women 1 man) and 30 joints. Fifteen (88%) patients had sagittal split ramus osteotomies (SSRO); 8 (53%) of these patients also had Le Fort I osteotomies, and 2 patients (12%) had only Le Fort I osteotomies with TFG. Group 2 consisted of 12 patients (15 joints) who received only TFG and no SOS.

RESULTS

Group 1 had 9 patients (53%) with an incisal opening greater than 35 mm, 11 joints (37%) with greater than 6 mm lateral excursive movement, and 11 patients (65%) were asymptomatic postoperatively. Average follow-up was 57.4 months (range, 23 to 69 months). Group 2 had eight patients (67%) with an incisal opening greater than 35 mm, six joints (40%) with greater than 6 mm lateral excursive movement, and seven patients (58%) were asymptomatic postoperatively. Average follow-up was 55.1 months (range, 48 to 64 months).

CONCLUSION

TFG with and without SOS produced similar treatment outcomes in comparing groups 1 and 2. No significant differences were observed for the number of patients with an incisal opening > 35 mm (P = .703), lateral excursion > 6 mm (P = 1.00), and successful elimination of pain (P = 1.00), even though group 2 had a significantly greater number of patients (P < 0.01) that were operated on unilaterally. Combining treatment outcomes for both groups, the number of previous joint surgeries significantly affected success (P < .01). The presence of osteoarthritic changes did-not significantly affect treatment outcome (P = .187).

Reliable cryopreservation of trachea for one month in a new trehalose solution

We previously reported that trehalose, a reduced disaccharide, was effective in the preservation of lungs. In this study, we investigated the possibility of prolonged cryopreservation of tracheas in a preservative solution containing trehalose. Five rings of cervical trachea were removed and immersed in the preservative solution. The harvested tracheas were then cryopreserved and stored in a deep freezer at -85 degrees C. One month later, five rings of mediastinal trachea were removed. The cryopreserved cervical tracheas were thawed and autotransplanted in place of the excised mediastinal trachea (n = 6). The anastomotic site and graft were then covered with an omental pedicle. All six animals survived for more than 6 months. All grafts survived without any evidence of atrophy or stenosis. Microscopic examination of the grafts showed that the integrity of the tracheal tissues was maintained. Our findings show that consistent cryopreservation of the trachea for 1 month is possible in a preservative solution containing trehalose.

Temporomandibular joint disc replacement made by tissue-engineered growth of cartilage

OBJECTIVE

To test the effectiveness of the new technique of tissue-engineered growth of cartilage, temporomandibular joint (TMJ) disc replacements were created by seeding dissociated chondrocytes on synthetic, three-dimensional, bioresorbable polymer constructs of a predetermined anatomic shape, incubating the cell-polymer constructs in vitro, and transplanting them into test animals.

MATERIALS AND METHODS

Twelve highly porous and bioresorbable cell-transplantation devices in the shape of TMJ discs were created using biodegradable polylactid and polyglycolic acid fibers. Bovine articular cartilage was dissociated into chondrocytes and the cells were allowed to attach to the three-dimensional polymer scaffolds and multiply in vitro. After 1 week, the cell-polymer constructs were implanted subcutaneously into nude mice. The neocartilage was assessed by magnetic resonance imaging (MRI) techniques, gross inspection, histology, and biomechanical and biochemical analysis after 12 weeks.

RESULTS

All implants seeded with chondrocytes showed gross evidence of histologically organized hyaline cartilage. The scaffolds maintained their specific shape. They not only showed appropriate intrinsic stability during neomorphogenesis of cartilage in vitro and in vivo, but also seemed to guide the growth of cartilage. The presence of sulfated glycosaminoglycans was shown by aldehyde fuchsin alcian blue staining of the specimens. Type II collagen, considered to be indicative of cartilage formation, was found in the specimens tested. MRI showed signal characteristics similar to those of hyaline cartilage. Analysis of neocartilage force/displacement curves and aqueous phase compliance using a closed compression chamber suggested that the ability of the constructs to resist deformation was similar to that of native donor cartilage.

CONCLUSION

The technology of tissue-engineered growth of cartilage on individually designed scaffolds may have many applications not only in reconstructive surgery of the TMJ, but also in craniomaxillofacial, plastic, and orthopedic surgery.

Long-term viability of the temporalis muscle/fascia flap used for temporomandibular joint reconstruction

Temporalis muscle/fascia axial flaps (TFs) were used in 115 temporomandibular joints (TMJs) in 81 patients to correct ankylosis (n = 25 joints), traumatic defects (n = 8), congenital anomalies (n = 4), defects resulting from tumor resection (n = 2), degenerative joint disease (n = 52), autoimmune arthritides (n = 21), and lateral capsule flaccidity (n = 3). The follow-up period ranged from 6 months to 5.5 years. Seven patients (8.6% of the group; 10 TMJs) were reevaluated for recurrent symptoms (pain and decreased motion), with a mean of 1.7 years (range = 1 to 3 years) postoperatively. Four of these patients (seven TMJs) had magnetic resonance imaging (MRI) as part of their diagnostic workup and four patients (five TMJs) required a second operative procedure. This study reports the results of the MRI, intraoperative, and histologic evaluations of the TFs in these seven patients. The MRIs showed vascularized tissue between the condyle and roof of the glenoid fossa in all seven joints examined. The signal was consistent with muscle and/or fat as opposed to scar tissue. All flaps examined at the time of surgery (arthroscopy, n = 1; arthrotomy, n = 4) were in place and had the gross appearance of normal muscle. Histologic examination of biopsies of four flaps indicated the presence of viable muscle with normal-appearing nuclei. The results of this study indicate that the TF does survive when it is carefully dissected and inferiorly based to preserve blood supply.

Treatment outcomes for temporomandibular joint reconstruction after Proplast-Teflon implant failure

A retrospective study of 107 patients (male, n = 13; female, n = 94) with 163 joints previously treated with Proplast-Teflon (PT; Vitek, Inc, Houston, TX) implants was performed. The average time in situ for the PT was 59.8 months (range, 2 to 126 months). Average length of follow-up was 84.6 months (range, 59 to 126 months). Only 12% of joints showed no significant osseous changes radiographically. Forty-five patients (42%) continue to have in situ PT implants and 36% of them experience pain that requires medication; 25% have developed an anterior open bite and malocclusion; 9% have limited vertical opening; and 40% are asymptomatic. Temporomandibular joint (TMJ) reconstruction after PT implant failure was performed with five different autologous tissues or a total joint prosthesis. Autologous tissues used to reconstruct the TMJ and the rates of success were as follows: 1) 31% free temporalis fascia and muscle graft with and 13% without sagittal split ramus osteotomy, 2) 8% dermis, 3) 25% conchal cartilage, 4) 12% costochondral grafts, and 5) 21% sternoclavicular grafts. The success rate decreased in all autologous tissue groups as the number of TMJ surgeries performed before reconstruction increased. Ankylosis was the most common cause of failure. Results of TMJ reconstruction with a total joint prosthesis were as follows: 1) 88% functional and occlusal stability of total joint prosthesis; 2) level of pain reduction was rated as 46% good, 38% fair, and 16% poor; and 3) an average interincisal opening of 27 mm at 24 months or less, and 33 mm at 25 months and beyond.(ABSTRACT TRUNCATED AT 250 WORDS)

Repair of long tracheal defects with cryopreserved cartilaginous allografts

Tracheoplasties with various autografts (cartilage, periosteum, pericardium) have been used in the treatment of long-segment tracheal stenosis. Previous studies have shown that cartilage allografts survive transplantation on a long-term basis in various sites of the body. In this study we set out to determine if cryopreserved cartilage and cryopreserved tracheal allografts would survive when used to cover tracheal defects in animals. A rectangular defect (2.8 +/- 0.3 cm long and incorporating 50% of tracheal circumference) was created in the thoracic trachea of 18 piglets. The defect was covered with the excised tracheal segment in 6 (group A, control group), with a cryopreserved tracheal allograft in 6 (group B), and with a cryopreserved cartilage allograft harvested from the scapula in 6 (group C). The allografts were cryopreserved, by a standard slow-freezing technique, at -80 degrees C for more than 21 days. All animals survived the grafting procedure and were killed after 2 months. None had signs of airway obstruction. Using the trachea above the defect as the standard, the mean sagittal narrowing of the airway in the repaired trachea was 0.4 mm in group A, 0.7 mm in group B, and 0.6 mm in group C; the coronal diameter in normal and grafted trachea was similar. The lumen of all grafts was lined by regenerating respiratory epithelium, and cilia were seen in many. Some cartilage was reabsorbed in group A and B but cartilage islands were present in all. In group A, reabsorption of cartilage was minimal. These findings suggest that segments of trachea or cartilage allografts can be cryopreserved, stored, and, subsequently, used when necessary for tracheoplasty.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

Subjects of the past decade in the dental literature are reflected in this year's Committee report. We note the decrease in the prevalence of caries, the influence of dental implants, the advancements in dental materials, and the continued efforts to control adhesive events in the oral cavity. This year we included comments from and about many significant review articles published this past year. The Committee continues to be concerned about the quality of some of the work reported and the quality of the reporting. We have attempted to select the distinguished work, that which provides new information to our profession. The subjects covered include pulp biology, caries prevention, periodontics, implants, craniomandibular function and dysfunction, occlusion, and dental materials.