Ergun Yücel

Bone lid technique with piezosurgery to preserve inferior alveolar nerve

The inferior alveolar nerve is at risk during surgical removal of impacted mandibular teeth and excision of benign tumors of mandible. Manual and/or mechanical instruments used in the close proximity of delicate structures do not allow the control of the cutting depth and can damage these structures by accidental contact. Piezoelectric surgery is a new and innovative bone surgery technique using the microvibrations of special scalpels at ultrasonic frequency so therefore soft tissue will not be damaged even upon accidental contact with the cutting tip. This article presents an alternative technique that uses piezoelectricity to minimize trauma to the inferior alveolar nerve, vascular tissues, or surrounding dental tissues.

Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA. Part 1: Advancement surgery

The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Recurrent osteoblastoma of the mandible : a case report

Osteoblastoma is an uncommon bone tumor most often found in the vertebral column, long bones of the appendicular skeleton, and in the small bones of hands and feet.’ The jaws are rarely involved. Strand-Pettinen et al found 33 cases reported in the literature and added a case of their own.* Although considered a benign neoplasm, osteoblastoma may show an aggressive behavior3 or even sarcomatous transformation4 An aggressive osteoblastoma of the maxilla has been reported.’ An osteoblastoma in the mandible, although rare, can recur6 and may resemble osteosarcoma histologically. A case of osteoblastoma of the mandible that recurred within a year after initial treatment is presented.

Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA

The aim of the second part of this study was to evaluate the mechanical behaviour of 2- versus 4-plate fixation and bony structures after Le Fort I impaction surgeries using three-dimensional finite element analysis (3D-FEA). Two 3D-FEA models were created to fixate the impacted maxilla at the Le Fort I level as 2-plate fixation at the piriform rims (IMP-2 model) and 4-plate fixation at the zygomatic buttresses and piriform rims (IMP-4 model). The IMP-2 model contained 225664 elements and 48754 nodes and the IMP-4 model consisted of 245929 elements and 53670 nodes. The stresses in each maxillary model were computed. The models were loaded on one side, at the molar-premolar region, in vertical, horizontal and oblique directions to reflect the chewing process. It was concluded that the use of 4-plate fixation following Le Fort I advancement surgery provides fewer stress fields on the maxillary bones and fixation materials than 2-plate fixation from a mechanical point of view.

Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA: Part 3: Inferior and anterior repositioning surgery

Having studied the effect of maxillary advancement and maxillary impaction in parts 1 and 2 of this research, the purpose of this study was to investigate the biomechanical behavior of different fixation models in inferiorly and anteriorly repositioned maxilla following Le Fort I osteotomy. Two separate three-dimensional finite element models, simulating the inferiorly advanced maxilla at Le Fort I level, were used to compare 2- and 4-plate fixation. Model INF-2 resulted in 247,897 elements and 53,247 nodes and INF-4 consisted of 273,130 elements and 59,917 nodes. The stresses occurring in and around the bone and plate-screw complex were computed. The highest Von Mises stresses on the plates and maximum principal stresses on the bones were found in INF-2, especially under horizontal and oblique loads, when compared with INF-4. The present biomechanical study shows that the traditionally used 4-plate fixation technique, following Le Fort I inferior and anterior repositioning surgery, without bone grafting, provides fewer stress fields on the maxillary bones and fixation materials.

Early treatment of unilateral temporomandibular joint ankylosis: a multidisciplinary approach.

Ankylosis of temporomandibular joint is a condition in which partial or complete immobilization of mandible occurs because of fusion between mandibular condyle and skull base. This condition can be treated orthodontically, surgically, or therapeutically or by prosthodontic rehabilitation. A 10-year-old female patient presented to the Department of Oral and Maxillofacial Surgery, Gazi University Faculty of Dentistry, with limited mouth opening. She got injury in the face when she was 5 years old. Extraoral and intraoral examination findings were facial asymmetry on the left side, micrognathic mandible, and 19-mm mouth opening. After radiographic examination, ankylosis (Shawney type I) on the left side was revealed, and the patient was referred to Department of Orthodontics. After orthodontic clinical examination, we create following multidisciplinary treatment approach: (1) acrylic posterior bite block with spring application, (2) interpositional arthroplasty operation, and (3) physiotherapy (passive mouth-opening exercises). After the follow-up of 9 months, significant improvement (5 mm) was noticed in the opening of the mouth, and we decided to remove appliance and operate on the patient. Surgical procedure was performed under general anesthesia via blinded nasotracheal intubation. To prevent postoperative relapse, temporal fascia was interpositioned and sutured. Passive mouth-opening exercises were started 10 days after the surgery. Thirty-one-millimeter mouth opening was reached after the surgery and passive mouth-opening exercises. Patients routine controls have been continued for 2 years.

The quantitative investigation of infrared laser effects on the levels of copper and zinc in various tissues

In order to study the effects of infrared laser irradiation on biological systems, the levels of copper and zinc in various irradiated tissues have been investigated. The zinc level in the muscle of the irradiated group increased (P less than 0.001) compared with the control group while in submandibular glands its level decreased (P less than 0.001). The copper levels in these two types of tissues decreased significantly (P less than 0.001). In irradiated skin, both copper and zinc levels increased compared with the control group (P less than 0.005). Quantitative determination of the trace elements copper and zinc indicated the necessity for more detailed studies of the effect of infrared laser irradiation at the cellular level.