OBJECTIVE: To study the effect of collagen/hydroxyapatite(CHA) instead of autogenous bone transplantation on repairing the mandibular defects. METHODS: Ten Chinese experimental minipigs were made 2 cm bone defects in diameter in the mandible. The experimental group was implanted CHA, while the control group was implanted autogenous bone. The basic parameters of bone dynamics were determined by bone metrology. RESULTS: There was remarkable difference between the two groups in the mean distance and mineralization apposition rate of double label bands marked by tetracycline(P lt; 0.05), while the mean osteoid seam width and mineralization lag time had no remarkable difference(P gt; 0.05). It suggested that CHA had good osteogenesis. The collagen in CHA offered the condition of bone mineralization, and the mineralization peak of experimental group was present at 4 weeks earlier than that of control group (8 weeks). CONCLUSION: CHA may be a substitute of autogenous bone transplantation in repairing the mandibular defects, and the second operation for offering the implanting bone is avoidable, therefore, CHA may be an ideal material to repair bone defects.
OBJECTIVE: To establish the animal models of mandibular distraction osteogenesis in rabbits and study its osteogenetic mechanism. METHODS: The right mandibles just anterior to the first molars of 12 rabbits were performed osteotomies, and the mandibles were positioned with distractors. The left mandibles were control group without operation. After 1 week, the distractors were stretched 0.9 mm every day for 10 days progressively. One day, 2, 4, 8 weeks after distraction, the mandibles were studied with gross measurement, X-ray, and histological examination. RESULTS: The right mandible were lengthened 8.3 mm on average without bone nonunion and deformity healing. It was observed that the gaps between the distracted bone edges were first occupied by fibrous tissue. Two weeks after distraction, it was found that the gaps were bridged by callus in X-ray, the new bone and the normal bone could not be differentiated clearly after 8 weeks. In histological sections, there were collagen bundles in early distraction, then those collagen bundles were calcificated and become trabeculaes. No Cartilage was found during distraction. CONCLUSION: It suggests that the rabbit mandible can be lengthened by distraction osteogenesis, and the new bone is formed by intramembranous ossification.
Six cases of maxillary tumors after being resccted radically, a primary repair of the maxillary defects were carried out by grafting of the pedicled buccal fat pad as the oral linning combined with bone graft. The cases were followed from 8 to 14 months. The function of the maxillary sinuses was normal and the facial contour was restored symmetrical. The applied anatomy and the method of operation were introduced in details. The advantages of the method were discussed.
Objective To investigate the clinical effect of free forearm flap and titanium mesh in repairing maxillary defects. Methods From January 2002 to November 2002,partial maxillectomy or maxillectomy wereperformed in 3 patients with maxillary gingival carcinoma, in 1 patient with palatine mucoepicermoid carcinoma and in 1 patient with maxillary sinus carcinoma. Maxillary defects were reconstructed withfree forearm flaps ranging from 4 cm×5 cm to 6 cm×7 cm and titanium mesh.The effect was estimated by clinical examination, CT and nasopharyngoscope. Results Five cases were followed up 515 months. All the flaps were alive. Facial, alveolar process and palatal contours were restored well. Epithelium was found on the nostril surface of the titanium mesh. The functions of speech and chew were restored well. Conclusion A combination of the free forearm flap and titanium mesh is an ideal method in reconstruction of maxillary defects.
Objective To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distractionosteogenesis.Methods Skeletally mature-white New Zealand rabbits were established right mandibular distraction osteogenesis models and the mandibles were lengthened 7 days after osteomy. Atthe end of latency period and the end of distraction period, 10,20, 30, 40 and60 days after fixation, the regenerating tissue of animals’ lengthened mandibles and that of the other side normal mandibles were harvested to extract RNA andto analyse ACT A, FS mRNA by RT-PCR.Results The expression of ACT A mRNA was not detectable in normal bone tissue and ACT A mRNA began to express at the end of latency period. The expression of ACT AmRNA increased gradually along with the beginning of distraction and reached the peak on the 10th and 20th days of distraction which was 5.04 and 4.98 times as much as that of the end of latency period, respectively. The trend of expression of FS mRNA during mandibular distraction osteogenesis was the same as expression of ACT A mRNA. Conclusion ACT A/FS play an important role during rabbit mandibular distraction osteogenesis.
ObjectiveTo establish a method to prefabricate titanium plate with three-dimensional (3-D) printing technique for correction of mandibular prognathism in sagittal splint ramous osteotomy (SSRO). MethodsBetween January 2012 and May 2013, 12 patients with mandibular prognathism (Angle III malocclusion) were treated. Among them, 9 cases were male and 3 cases were female. Their ages ranged from 19 to 35 years (mean, 25.6 years). With the 3-D facial CT data of these patients, 3-D printer was used to print the models for preoperational simulation. SSRO was performed on 3-D models, and the titanium plates were prefabricated on the models after the distal segments were moved backward and rotated according to occlusal splint. During operations, the proximal segments were fixed to distal segments by the prefabricated titanium plates. 3-D CT scans were taken to examine the temporomandibular joint position changes before operation and at 6 months after operation. ResultsThe skull models were manufactured by 3-D printing technique, and the titanium plates were reshaped on the basis of them. Twenty-four prefabricated titanium plates were placed during operations, and they all matched with the bone segments well. Evaluation of 3-D CT scans showed that the temporomandibular joint position had no change. All patients were followed up 7-12 months (mean, 10.6 months). The face type and dental articulation were improved greatly. All cases obtained satisfactory opening function and occlusion. ConclusionWith the titanium plate fabricated based on 3-D models, surgeons are able to improve or refine surgical planning so that the operation can be performed according to preoperative simulation precisely and the complications, such as dislocation of temporomandibular joint, can be prevented.
Objective To explore the application of personalized guide plate combined with intraoperative real-time navigation in repairing of mandibular defect using fibula muscle flap, providing the basis for the precise repair and reconstruction of mandible. Methods The clinical data of 12 patients (9 males and 3 females) aged from 23 to 71 years (mean, 55.5 years) between July 2019 and December 2021 were recorded. These patients were diagnosed as benign or malignant mandibular tumors, including 2 cases of ameloblastoma, 6 cases of squamous cell carcinoma, 2 cases of osteosarcoma, 1 case of adenoid cystic carcinoma, and 1 case of squamous carcinoma. All patients were treated with mandibular amputation, and then repaired by double-stacked three-segment fibula muscle flap. Preoperative virtual design scheme and guide plate were performed. During the operation, personalized guide plate combined with real-time navigation was used for fibular osteotomy and shaping. Thin-slice CT examination was performed at 2-3 weeks after operation, and was fitted with the preoperative virtual design scheme. The difference between the distance of bilateral mandibular angles relative to the reference plane in three-dimensional directions (left-right, vertical, and anterior-posterior) and the difference of the medial angle of the lower edge of the mandible reconstructed by fibula were measured, and the mean error of chromatographic fitting degree was calculated. Results The guide plate and navigation were applied well, and the fibula shaping and positioning were accurate. The fibula muscle flap survived, the incision healed well, and the occlusal relationship was good. All 12 patients were followed up 1-29 months, with an average of 17 months. There was no significant difference on the distance of bilateral mandibular angles relative to the reference plane in the left-right [(−0.24±1.35) mm; t=−0.618, P=0.549], vertical [−0.85 (−1.35, 1.40) mm; Z=−0.079, P=0.937], and anterior-posterior [(−0.46±0.78) mm; t=−2.036, P=0.067] directions. The difference of the medial angle of the lower edge of the mandible reconstructed by fibula was also not significant [(−1.35±4.34)°; t=−1.081, P=0.303)]. Postoperative CT and preoperative virtual design fitting verified that there was no significant difference in the change of the mandibular angle on both sides, and the average error was (0.47±1.39) mm. ConclusionThe personalized guide combined with intraoperative real-time navigation improves the accuracy of peroneal muscle flap reconstruction of the mandible, reduces the complications, and provides a preliminary basis for the application of visual intraoperative navigation in fibula muscle flap reconstruction of the mandible.
Objective To investigate the method of combining radial forearm free flap and adjacent tissue flap in reconstruction of palatomaxillary defects and its effectiveness. Methods Between March 2005 and May 2010, 17 patients with palatomaxillary defects were treated. There were 11 males and 6 females with an age range of 45-74 years (mean, 62.5 years), including 1 case of benign tumor and 16 cases of malignant tumors (7 cases of squamous cell carcinoma of palate, 1 case of recurring squamous cell carcinoma of palate, 1 case of malignant melanoma of palate, 1 case of adenoid cystic carcinoma of palate, 1 case of malignant melanoma of maxilla, 1 case of ductal carcinoma of maxilla, and 4 cases of squamous cell carcinoma of maxilla). The maxillectomy defect ranged from 7.0 cm × 5.5 cm to 10.0 cm × 7.5 cm. According to Brown’s classification for the maxillectomy defect, there were type II in 15 cases, type III in 2 cases. Palatomaxillary defects were repaired with radial forearm free flap and buccal fat pad in 11 cases, and with radial forearm free flap, buccal fat pad, and mandibular osteomuscular flap pedicled with temporal muscle in 6 cases. The effectiveness was evaluated after operation by observing the vitality of the flap, the functions of speech, swallowing, breath, and the facial appearance. Results All cases were followed up 6-12 months without tumor recurrence. All flaps and skin grafts at donor sites survived. The functions of seech, swallowing, and breath were normal without obvious opening limitation. The facial appearance was satisfactory without obvious maxillofacial deformity. No enophthalmos occurred in patients with orbital floor and infraorbital rim defects. The patients had no oronasal fistula with satisfactory oral and nasal functions. Conclusion According to the type of palatomaxillary defects, it can have good early effectiveness to select combining radial forearm free flap and buccal fat pad or combining radial forearm free flap, buccal fat pad, and mandibular osteomuscular flap for repairing defects.