Stem cells regenerative properties on new rat spinal fusion model.

Stem cells biology is one of the most frequent topic of physiological research of today. Spinal fusion represents common bone biology challenge. It is the indicator of osteoinduction and new bone formation on ectopic model. The purpose of this study was to establish a simple model of spinal fusion based on a rat model including verification of the possible use of titanium microplates with hydroxyapatite scaffold combined with human bone marrow-derived mesenchymal stem cells (MSCs). Spinous processes of two adjacent vertebrae were fixed in 15 Wistar rats. The space between bony vertebral arches and spinous processes was either filled with augmentation material only and covered with a resorbable collagen membrane (Group 1), or filled with augmentation material loaded with 5 × 106 MSCs and covered with a resorbable collagen membrane (Group 2). The rats were sacrificed 8 weeks after the surgery. Histology, histomorphometry and micro-CT were performed. The new model of interspinous fusion was safe, easy, inexpensive, with zero mortality. We did not detect any substantial pathological changes or tumor formation after graft implantation. We observed a nonsignificant effect on the formation of new bone tissue between Group 1 and Group 2. In the group with MSCs (Group 2) we described minor inflamatory response which indicates the imunomodulational and antiinflamatory role of MSCs. In conclusion, this new model proved to be easy to use in small animals like rats.

Stability of the miniplate osteosynthesis used for sagittal split osteotomy for closing an anterior open bite: an experimental study in mini-pigs.

Bilateral sagittal split osteotomy of the mandible with counterclockwise rotation of the occlusal plane alone has traditionally been considered the least stable treatment method. Two miniplates on each side of the osteotomy may resolve this problem. The authors compared early vertical and transverse stability of a simple mandibular advancement (group A), mandibular advancement with counterclockwise rotation (CCW) stabilized with one miniplate (group B), and two miniplates (group C) on mini-pig mandibles mounted on a custom-made loading unit. Two miniplates markedly increased the resistance to vertical bite forces. On a 100-N load, a median of dislocation of 0.53 mm, 0.46 mm, and 0.23 mm was achieved in groups A, B, and C, respectively. The difference was statistically significant between groups A and B in comparison with group C. The results of transverse displacement were not statistically significant. The use of two miniplates in larger shifts, as well as in CCW cases, increases stability in the vertical direction.

Piezosurgery prevents brain tissue damage: an experimental study on a new rat model.

Piezosurgery is a promising meticulous system for bone cutting, based on ultrasound microvibrations. It is thought that the impact of piezosurgery on the integrity of soft tissue is generally low, but it has not been examined critically. The authors undertook an experimental study to evaluate the brain tissue response to skull bone removal using piezosurgery compared with a conventional drilling method. In Wistar male rats, a circular bone window was drilled to the parietal bone using piezosurgery on one side and a conventional bone drill on the other side. The behavioural performance of animals was evaluated using the motor BBB test and sensory plantar test. The brains of animals were evaluated by magnetic resonance imaging (MRI) and histology. The results of MRI showed significantly increased depth and width of the brain lesion in the region of conventional drilling compared with the region where piezosurgery was used. Cresylviolet and NF 160 staining confirmed these findings. There was no significant difference in any of the behavioural tests between the two groups. In conclusion, piezosurgery is a safe method for the performance of osteotomy in close relation to soft tissue, including an extremely injury-sensitive tissue such as brain.

The role of intraoperative positioning of the inferior alveolar nerve on postoperative paresthesia after bilateral sagittal split osteotomy of the mandible: prospective clinical study.

Bilateral sagittal split osteotomy (BSSO) aims to correct congenital or acquired mandibular abnormities. Temporary or permanent neurosensory disturbance is the most frequent complication of BSSO. To evaluate the influence of IAN handling during osteotomy, the authors undertook a prospective study in 290 patients who underwent BSSO. The occurrence and duration of paresthesia was evaluated 4 weeks, 3 months, 6 months, and 1 year after surgery. Paresthesia developed immediately after surgery in almost half of the patients. Most cases of paresthesia resolved within 1 year after surgery. A significantly higher prevalence of paresthesia was observed on the left side. The authors found a correlation between the type of IAN position between the left and right side. The type of split (and IAN exposure) did not have a significant effect on the occurrence or duration of neurosensory disturbance of the IAN. The authors did not find a correlation between the occurrence and duration of paresthesia and the direction of BSSO. Mandibular hypoplasia or mandibular progenia did not represent a predisposition for the development of paresthesia. In the development of IAN paresthesia, the type of IAN exposure and the split is less important than the side on which the split is carried out.

Piezosurgery in oral and maxillofacial surgery.

This review summarizes current knowledge and experience with piezosurgery, a promising, meticulous and soft tissue-sparing system for bone cutting, based on ultrasonic microvibrations. The main advantages of piezosurgery include soft tissue protection, optimal visibility in the surgical field, decreased blood loss, less vibration and noise, increased comfort for the patient and protection of tooth structure. To date it has been indicationed for use in oral and maxillofacial surgery, otorhinolaryngology, neurosurgery, ophthalmology, traumatology and orthopaedics. The main indications in oral surgery are sinus lift, bone graft harvesting, osteogenic distraction, ridge expansion, endodontic surgery, periodontal surgery, inferior alveolar nerve decompression, cyst removal, dental extraction and impacted tooth removal. In conclusion, piezosurgery is a promising technical modality for different aspects of bone surgery with a rapidly increasing number of indications throughout the whole field of surgery.

Hemimandibulectomy and therapeutic neck dissection with radiotherapy in the treatment of oral squamous cell carcinoma involving mandible: a critical review of treatment protocol in the years 1994-2004.

This retrospective non-randomized 10-year follow-up study compared 147 patients with squamous cell carcinoma (SCC) of the oral cavity requiring hemimandibulectomy, treated by surgical resection, therapeutic neck dissection and radiotherapy. The 5-year survival rates were compared related to localization, size of the tumour, infiltration of locoregional lymph nodes, distant metastases, histopathological grading, radicality of surgery, and invasion of tumour into the mandible. Occurrence of tumour relapse and its localization was studied. The mean 5-year survival rate was 26%. Patients with SCC of the mandibular alveolar process had higher rates; the lowest rates occurred in SCC of the buccal mucosa. Survival rate was significantly lower with insufficient resection of the tumour (85% relapse). An important number of patients with radical resection died within 3 months of surgery. In almost 55% of the mandibles tumour was not present. In 5% of infiltrated mandibles, dissemination into inferior alveolar nerve was proven. Decreasing survival rate was seen with increasing size of tumour and higher histological grade. Therapeutic neck dissection significantly reduces survival rate and increases the percentage of lymph node relapse. Elective neck dissection should be performed in SCC requiring hemimandibulectomy. Primary reconstruction should reverse the high percentage of postoperative complication arising from increased radicality.

Factors affecting the stability of bilateral sagittal split osteotomy of a mandible.

Stability of bilateral sagittal split osteotomy (BSSO) is an important goal for every surgeon. In the article factors influencing stability of the surgery result are reviewed. Special emphasis is given to different types of fixation of bone fragments. Their advantages and disadvantages in clinical use are discussed. Relapse after BSSO is usually classified as early and long-term relapse. Early relapse is usually caused by movements at the osteotomy site or temporomandibular joint sag and should be called surgical displacement. Long term relapse happens due to the progressive temporomandibular joint condylar resorption, which causes a lost of condylar and mandibular ramus height. Four different types of fixation were described in orthognatic surgery: rigid intermaxillary fixation, osteosuture, osteosynthesis and fixation with biodegradable materials.