Hakan H. Tüz

Histomorphometric Evaluation of the Effects of Zoledronic Acid on Mandibular Distraction Osteogenesis in Rabbits

PURPOSE To assess the effect of systemic administration of zoledronic acid (ZA) on mineralization of newly formed bone and to determine strain-related osteoporosis on surrounding bone during lengthening of immature rabbit mandible. MATERIALS AND METHODS Eighteen New Zealand white rabbits were divided randomly into 2 groups, and bone lengthening was carried out in the left portion of the mandible through distraction osteogenesis with a rate of 0.5 mm every 12 hours for 5 days. The experimental group was administered 0.1 mg/kg ZA intravenously. The control group was given saline infusion only during operation. All animals were sacrificed at the end of the 28-day consolidation period. The mandibles of all animals were removed and regenerate was evaluated. Osteoblasts, osteoclasts, collagen fibers, and fibroblasts were marked within 0.1-mm(2) area and newly formed bone area was measured within 0.5-mm(2) area. All data were analyzed using Mann-Whitney U test. RESULTS Although irregular bone destruction spots were seen in the control group, the experimental group showed regular ossification areas and significant difference between osteoblast and osteoclast numbers (P < .05). In the regenerate zone, there was considerable difference between the 2 groups in terms of osteoblast, osteoclast, and collagen amounts (P < .05). Additionally, newly formed bone areas and fibroblast count were higher in experimental group. CONCLUSIONS The results of this study showed that ZA had positive effects on the new bone formation, which may potentially shorten the consolidation period.

Effects of Alendronate on Rate of Distraction in Rabbit Mandibles

PURPOSE Bisphosphonates are used for inhibiting bone resorption in several diseases. In this experimental study, the effects of alendronate on the mandibular distraction gap in rabbits at 2 different rates were evaluated. MATERIALS AND METHODS The study was performed using 15 New Zealand white rabbits. Group 1 consisted of animals with distraction at the rate of 1 mm/day. Group 2 consisted of animals with distraction at the rate of 2 mm/day. These experimental groups had a postoperative alendronate injection during the first 3 days of their distraction phase. Group 3 consisted of animals with distraction at the rate of 1 mm/day, without alendronate injections. Distraction was performed on only the left sides of all animals until a gap of 10 mm was achieved. On postoperative day 45, the animals were sacrificed, and the mandibles of all animals were evaluated radiographically and histologically, and with dual-energy x-ray absorptiometry (DEXA). Radiographic images were also evaluated using transmission densitometry (TD). RESULTS Histologically, bone healing was found to be significantly accelerated in groups 1 and 2 compared with group 3 (P < .05). Bone healing was superior in group 2, but the difference was not statistically significant compared with group 1. The TD results revealed no statistical difference between experimental groups, whereas the results for group 2 showed significantly denser osteogenic formation in the distraction gap compared with group 3. There was a significant increase in mean bone mineral density in the experimental groups compared with the control group. CONCLUSION Histologic, TD, and DEXA results showed that alendronate injections during the distraction phase may be effective in accelerating new bone formation in the distraction gap in rabbit mandibles. The TD results also support the concept that an administration of alendronate may allow a 2 mm/day elongation instead of 1 mm/day in the rabbit mandible.

Piezosurgery Versus Conventional Surgery in Radicular Cyst Enucleation

Objective This study compared the use of piezosurgery and conventional surgery in radicular cyst enucleation. Study Design The study was conducted with 29 patients who were radiologically and cytologically prediagnosed with radicular cysts in the jaw region. Nineteen patients were treated using piezosurgery, and 10 were treated using conventional surgical procedures. Surgical procedures were evaluated according to the following criteria: hemorrhage, soft-tissue damage, manipulation complexity, major perforation areas on the enucleated cyst tissue, and approximate operation duration. Patients were monitored postoperatively and evaluated for hemorrhaging at 24, 48, and 72 hours following surgery. Follow-up was conducted to check for recurrences and ranged from 5 to 24 months. Results No complications were observed in any of the 20 patients treated using piezosurgery, although the duration of surgery was longer than expected. Of the 10 patients treated using conventional methods, hemorrhaging that affected the operation occurred in 3 cases, perforation of the cyst epithelium and difficulties in enucleation occurred in 5 cases, postoperative hemorrhage occurred in 2 cases, and recurrence was observed in 2 cases. Conclusions Piezosurgery may be considered effective in procedures such as enucleation that require sensitive manipulation, despite the increase in the length of the overall surgical procedure. Given the results of the present study and the current lack of information in the literature regarding postoperative pain, infection, and long-term success rates associated with the use of piezosurgery in cyst enucleation, further study in this area is recommended.

Biomechanical evaluation of malleable noncompression miniplates in mandibular angle fractures: an experimental study

The purpose of this experimental study was to test the reliability of a single malleable titanium miniplate using Champys method of fixing fractures of the mandibular angle. Eighteen sheep hemimandibles were used to evaluate 2 plating techniques. The groups were tested with either a single non-compression titanium miniplate or a single malleable titanium miniplate. A cantilever bending biomechanical test model was used for the samples. Each group was tested with vertical forces using a servohydraulic testing unit. The displacement values in each group at each 10N stage up to 90N were compared using 2-way analysis of variance (ANOVA). The displacement values for the 2 groups differed significantly (p<0.01). The variance analyses showed that the biomechanical behaviour of a single non-compression miniplate was better than that of a single malleable miniplate. The non-compression miniplate fixed by screws had greater resistance to occlusal loads than the malleable plate fixed by screws, and the malleable plate alone was not sufficient to withstand the early postoperative bite force.

Correction of postsurgical alveolar ridge defect with vertical alveolar distraction of the onlay block graft.

Alveolar bone augmentation for dental implant rehabilitation is one of the greatest challenges for oral and maxillofacial surgeons. Bringing out an inadequate quantity of vertical bone during augmentation compromises correct implant positioning and the resulting prosthetic restoration. Alveolar distraction osteogenesis is now generally used in correcting alveolar ridge atrophy due to trauma, congenital defects, or periodontal defects. Onlay block grafting is a suitable method for restoring the alveolar bony defects. However, it sometimes can become a complicated procedure to repair the horizontal defect accompanying a vertical defect using only bone blocks. This clinical report presents a successful reconstruction of a severe anterior mandibular alveolar bony defect as a result of impacted teeth extraction and periodontal problem in a 50-year-old healthy female patient. The defect was reconstructed with symphysis graft and platelet-rich fibrin in the first step. Vertical alveolar distraction was performed on the grafted site to maintain the suitable bony height 3 months later. Grafted bony segment distraction and the treatment options in similar cases were also discussed in this clinical report among with the literature.

Histomorphometric evaluation of delayed changes in masseter muscle after lengthening the rabbit mandible by distraction osteogenesis.

OBJECTIVE The aim of the study was to evaluate the delayed responses and changes of gradually lengthened masseter muscles of rabbit mandibles. STUDY DESIGN Unilateral lengthening of rabbit mandibles was performed in 18 New Zealand rabbits for 7 days at the rate of 1 mm day(-1). Mandibles of animals were removed at months 3, 4, and 6 after distraction. Biopsy samples of distracted and contralateral side masseter muscles were histopathologically evaluated and mean area of muscle fibers (MAF) was evaluated with histomorphometric methods. Results were statistically analyzed. RESULTS Mild to moderate atrophy of the fibers, and necrosis and myophagocytosis in some areas were the leading features at month 3 and which were decreased at month 4 in distracted side-muscle specimens, with no statistically significant differences when compared with non-distracted side muscles at the same periods. Almost completely, normal fibers were detected in distracted muscle specimens at month 6. Evidence of myopathic changes was found to disappear at month 6 and no significant difference was found in the MAF of distracted side muscles. CONCLUSION This study showed that the masseter muscle could adapt to gradual lengthening of the mandible within 6 months. Regenerative features and some degree of atrophic changes that could be observed at months 3 and 4 disappeared at month 6, with adaptation of the fibers.

Finite-Element Analysis of a New Designed Miniplate which is Used via Intraoral Approach to the Mandible Angle Fracture: Comparison of the Different Fixation Techniques.

AbstractThe mandible is the largest facial bone as well as the most commonly fractured bone in the maxillofacial region. Despite numerous studies conducted to identify optimal treatment modalities and plates configurations for intraoral and transoral approaches, no definitive conclusion has been reached.This study used finite element analysis (FEA) to assess 4 scenarios for treatment of an angle fracture (6-hole noncompression miniplate; 6-hole single plate/Champys technique, 3D strut plate; 2 parallel 4-hole noncompression miniplates). Analysis included segmental displacement and Von Mises Stress evaluations of a 3D reconstruction of a human mandible.Von Mises Stress values for plates did not vary significantly among treatment groups. Moreover, no significant differences were observed in cumulative displacement of segments subjected to vertical and horizontal loads, with all treatment configurations demonstrating clinical acceptability.

Histomorphometric examination of long-term changes in temporomandibular joints after mandibular lengthening by distraction osteogenesis in rabbits

OBJECTIVE The purpose of this study was to evaluate long-term histomorphometric changes in temporomandibular joints (TMJs) of rabbits after mandibular distraction osteogenesis (DO). STUDY DESIGN Twenty-six rabbits were used in this study. Two of them served as control subjects, and the remaining 24 underwent DO procedures in their left mandibular bodies. After a latency period of 5 days, 5 mm lengthening was performed at a rate of 1 mm/d. The rabbits in the experimental group were randomly divided into 4 subgroups and killed after 1, 2, 4, and 6 months. TMJs from both sides were harvested and prepared with hematoxylin and eosin stain for histomorphometric examination under an optical microscope. RESULTS Compared with control subjects and nondistracted sides, fibrous articular, proliferative, and hypertrophic areas were significantly increased (P < .05) in the first 2 months in distracted sides. The changes were insignificant in the fourth and sixth postoperative months. CONCLUSION Unilateral mandibular distraction of 5 mm was found to be well tolerated and no degenerative changes were observed histologically in the rabbit TMJs in the long-term period.

Reconstruction of a patient with Rosai-Dorfman disease using ramus graft and osseointegrated implants: a case report.

R osai-Dorfman disease (RDD), or sinus histiocytosis with massive lymphadenopathy, is a rare and benign, frequently self-limited histiocytic disorder of unknown etiology. The most common clinical findings are broad painless lymphadenopathy accompanied by fever, weight loss, tonsillitis, rhinorrhea, nasal obstruction, and sometimes hepatosplenomegaly. Laboratory findings in patients with RDD include an elevated erythrocyte sedimentation rate, anemia, leukocytosis and polyclonal hypergammaglobulinemia. RDD classically presents with painless massive cervical lymphadenopathy, which is caused by accumulation of lymphocytes and histiocytes distending the lymph node sinuses. However, the disease may occur at extranodal sites. In most instances, the extranodal sites include the eyes, head and neck, skin, or bone. Mandibular cortical grafts are the gold standard in the restoration of intraoral osseous defects. These grafts do not produce immune reactions and are incorporated by osteoclastic resorption with a short healing period when compared with other methods of osseous repair. Intraoral donor sites include the mandibular ramus, angle of the mandible, mandibular symphysis, and mandibular exostoses. The mandibular ramus provides primarily a dense cortical graft. Other advantages of a mandibular ramus transplant are minimal resorption, maintenance of osseous density, intraoral access, and proximity to the recipient site. Cortical grafts, including the ramus, are reliable donor sites for the reconstruction of the alveolar ridge deformities before dental implant placement. The highest concentrations of promoter proteins (eg, bone morphogenetic proteins) are found in the mandibular cortical grafts. This report presents a case of an isolated RDD involving the mandible as well as its surgical management, preprosthetic reconstruction, and restoration with dental implants.

A Simple Solution for Vector Control in Vertical Alveolar Distraction Osteogenesis

One of the important and frequent complications in alveolar distraction osteogenesis is vectorial change of the transport segment. This report presents a simple solution for vector angulation control by placing intermaxillary fixation screws intraoperatively. Advantages of the technique are also discussed.