Constantin A. Landes

Critical Evaluation of Piezoelectric Osteotomy in Orthognathic Surgery: Operative Technique, Blood Loss, Time Requirement, Nerve and Vessel Integrity

PURPOSE Piezo-osteotomy feasibility as a substitute for the conventional saw in orthognathic surgery was evaluated regarding operative technique, blood loss, time requirement, and nerve and vessel integrity. PATIENTS AND METHODS Fifty patients had orthognathic surgery procedures in typical distribution using piezosurgical osteotomy: 22 (44%) monosegment, 26 (52%) segmented Le Fort I osteotomies; 48 (48%) sagittal split osteotomies, 6 (12%) symphyseal, and 4 (4%) mandibular body osteotomies. Controls were 86 patients with conventional saw and chisel osteotomies: 57 (66%) monosegment, 25 (29%) segmented Le Fort I osteotomies, 126 (73%) sagittal split, and 4 (5%) symphyseal osteotomies. RESULTS Piezosurgical bone osteotomy permitted individualized cut designs, enabling segment interdigitation after repositioning. Angulated tools weakened the pterygomaxillary suture; auxiliary chisels were required in 100% of cases for the nasal septum, and lateral nasal walls as 46% pterygoid processes. After downfracture, the dorsal maxillary sinus wall and pterygoid processes were easily reduced. Hemorrhage was successfully avoided with average blood loss of 541 +/- 150 mL versus 773 +/- 344 mL (P = .001) for a conventional bimaxillary procedure. Sagittal mandibular osteotomy required considerable time (auxiliary saw in 13%); the lingual dorsal osteotomy was mostly performed tactile. Time investment remained unchanged: 227 +/- 73 minutes per bimaxillary standard osteotomy versus 238 +/- 61 minutes (P = .5); clinical courses and reossification were unobtrusive. Alveolar inferior nerve sensitivity was retained in 95% of the study collective versus 85% in the controls (P = .0003) at 3 months postoperative testing. CONCLUSIONS Piezoelectric osteotomy reduced blood loss and inferior alveolar nerve injury at no extra time investment. Single cases require auxiliary chiseling or sawing. Piezoelectric drilling for screw insertion and complex osteotomy designs may be developed to maintain bone contact or interdigitation after repositioning and minimize need for osteofixation.

Advanced Platelet-Rich Fibrin: A New Concept for Cell-Based Tissue Engineering by Means of Inflammatory Cells

Choukrouns platelet-rich fibrin (PRF) is obtained from blood without adding anticoagulants. In this study, protocols for standard platelet-rich fibrin (S-PRF) (2700 rpm, 12 minutes) and advanced platelet-rich fibrin (A-PRF) (1500 rpm, 14 minutes) were compared to establish by histological cell detection and histomorphometrical measurement of cell distribution the effects of the centrifugal force (speed and time) on the distribution of cells relevant for wound healing and tissue regeneration. Immunohistochemistry for monocytes, T and B -lymphocytes, neutrophilic granulocytes, CD34-positive stem cells, and platelets was performed on clots produced from four different human donors. Platelets were detected throughout the clot in both groups, although in the A-PRF group, more platelets were found in the distal part, away from the buffy coat (BC). T- and B-lymphocytes, stem cells, and monocytes were detected in the surroundings of the BC in both groups. Decreasing the rpm while increasing the centrifugation time in the A-PRF group gave an enhanced presence of neutrophilic granulocytes in the distal part of the clot. In the S-PRF group, neutrophils were found mostly at the red blood cell (RBC)-BC interface. Neutrophilic granulocytes contribute to monocyte differentiation into macrophages. Accordingly, a higher presence of these cells might be able to influence the differentiation of host macrophages and macrophages within the clot after implantation. Thus, A-PRF might influence bone and soft tissue regeneration, especially through the presence of monocytes/macrophages and their growth factors. The relevance and feasibility of this tissue-engineering concept have to be proven through in vivo studies.

Resorbable plate osteosynthesis of dislocated or pathological mandibular fractures: a prospective clinical trial of two amorphous L-/DL-lactide copolymer 2-mm miniplate systems.

&NA; The purpose of this study was to evaluate the indication for resorbable miniplates in traumatic and pathological mandibular fractures. Two resorbable miniplate systems, the 2.0‐mm MacroSorb (Macropore, San Diego, Calif.) and the PolyMax (Synthes, Oberdorf, Switzerland), were prospectively used in 24 mandibular osteosyntheses. Made from amorphous 70:30 poly‐L/DL‐lactide, amorphous copolymer plates have not yet been evaluated for mandibular osteosyntheses. The main advantage of the amorphous copolymer‐structure is continuous hydrolysis through water penetration into the implant body during the first 6 months. Hydrolysis breaks the copolymer chains into smaller particles that later become degraded through phagocytotic cells. Twelve patients, aged 13 to 83 years, were treated after providing informed consent. Fourteen dentate patients with moderately dislocated traumatic fractures and two edentulous atrophic and dislocated traumatic mandibular fractures were treated. Two patients with pathological fractures due to osteomyelitis received osteosynthesis after sequestrectomy. Histological specimens of the plates, screws, and surrounding soft tissues were taken after 3, 6,9, and 12 months in secondary dental implant operations. A total of 22 osteosyntheses healed well without clinical or radiological signs of dislocation, insufficient or excess formation of callus, pseudarthrosis, or plate fracture. The follow‐up time ranged from 4 to 22 months. One patient with osteomyelitis worsened because of widespread osseous infection, and one with atrophic fracture developed a bland fibrous pseudarthrosis. The histological specimens showed a moderate inflammatory foreign body reaction. No sinuous drainage or clinically apparent inflammation occurred. The presented osteosynthesis systems showed reliable stability for mandibular osteosynthesis in cooperative patients; however, two treatment failures occurred (8 percent). Disadvantages of the resorbable osteosyntheses were costs, greater diameter, screw breakage, and the need to place the screws vertically to the plate. The use of resorbable osteosyntheses in dislocated fractures should be further evaluated in controlled studies. (Plast. Reconstr. Surg. 111: 601, 2003.)

Skeletal stability in bimaxillary orthognathic surgery: P(L/DL)LA-resorbable versus titanium osteofixation.

Background: One-year skeletal stability following bimaxillary orthognathic surgery was assessed by comparing poly(L-lactide-co-DL-lactide) to titanium osteofixation. Methods: Thirty patients underwent osteofixation with poly(L-lactide-co-DL-lactide) copolymer and 30 had 2.0-mm titanium-miniplate osteosyntheses. Lateral cephalograms were analyzed preoperatively, postoperatively, and at 1-year follow-up. Average ± SD values were as follows in resorbable plate-osteosyntheses (number of cases/titanium controls): for maxillary advancement, 3.5 ± 4.1 mm (n = 19)/5.4 ± 3.5 mm (n = 21); setback, 2.8 ± 3.7 mm (n = 9)/1.9 ± 1.8 mm (n = 8); elongation, 4.2 ± 3.6 mm (n = 18)/3.7 ± 5.2 mm (n = 14); and intrusion, 1.9 ± 1.7 mm (n = 12)/3.3 ± 2.7 mm (n = 13); for mandibular advancement, 4.6 ± 3.6 mm (n = 10)/6.3 ± 8.8 mm (n = 18); setback, 7.5 ± 8.3 mm (n = 20)/7.2 ± 3.2 mm (n = 12); enlargement of the mandibular angle, 11.8 ± 9.9 degrees (n = 19)/7.9 ± 6.6 degrees (n = 21); and reduction, 4.5 ± 3.2 degrees (n = 9)/6.3 ± 6.6 degrees (n = 9). Results: Preoperative to postoperative landmark positions within the study and control groups differed highly significantly (p = 0.008, paired t test), yet the amount of operative movement was comparable between the study and control groups (p = 0.5, two-sided t test). Absolute instability at the advanced A-point was (study group/controls) 2.3 ± 1.8/2.4 ± 2 mm, setback was 2.3 ± 1.9 mm/2.5 ± 1.7 mm, elongation at the anterior nasal spine was 3.8 ± 3.1 mm/3.1 ± 3.6 mm, intrusion was 2.1 ± 1.9 mm/2.2 ± 1.5 mm, advancement instability at the B-point was 4.9 ± 4.3 mm/5.1 ± 8.2 mm, setback was 3.0 ± 2 mm/1.7 ± 2 mm, mandibular angle enlargement instability was 6.7 ± 8.9 degrees/8.2 ± 9.6 degrees, and angle narrowing was 6.8 ± 5.2 degrees/4.2 ± 5.9 degrees. Absolute postoperative instability did not differ significantly between the study and control groups (p = 0.6). Conclusions: Resorbable osteofixation as tested proved to be as reliable as titanium, but as the study and control groups were not matched, the results have to be interpreted as preliminary. Resorbable materials permitted clinically faster occlusal and condylar settling than standard titanium osteosyntheses, as bone segments showed slight clinical mobility up to 6 weeks postoperatively.

Histological and histomorphometrical analysis of a silica matrix embedded nanocrystalline hydroxyapatite bone substitute using the subcutaneous implantation model in Wistar rats

The clinical suitability of a bone substitute material is determined by the ability to induce a tissue reaction specific to its composition. The aim of this in vivo study was to analyze the tissue reaction to a silica matrix-embedded, nanocrystalline hydroxyapatite bone substitute.The subcutaneous implantation model in Wistar rats was chosen to assess the effect of silica degradation on the vascularization of the biomaterial and its biodegradation within a time period of 6 months. Already at day 10 after implantation, histomorphometrical analysis showed that the vascularization of the implantation bed reached its peak value compared to all other time points. Both vessel density and vascularization significantly decreased until day 90 after implantation. In this time period, the bone substitute underwent a significant degradation initiated by TRAP-positive and TRAP-negative multinucleated giant cells together with macrophages and lymphocytes. Although no specific tissue reaction could be related to the described silica degradation, the biomaterial was close to being fully degraded without a severe inflammatory response. These characteristics are advantageous for bone regeneration and remodeling processes.

Sentinel Node Biopsy as Staging Tool in a Multimodality Treatment Approach to Cancer of the Oral Cavity and the Oropharynx

OBJECTIVES: Feasibility of sentinel lymph node (SLN) biopsy in head and neck cancer as a staging tool embedded in a multimodality regimen including neoadjuvant intraarterial chemotherapy. STUDY DESIGN AND SETTING: 39 patients with oral and anterior oropharyngeal cancer classified N0 by [18F]FDG-PET underwent SLN scintigraphy. Selective SLN biopsy without elective neck dissection (ND) was performed, immediately followed by radical resection of the primary tumor. Histopathology included step-serial sections and immunocyto-chemistry. RESULTS: Lymphoscintigraphy detected 104 spots. In 15 patients there was bilateral drainage. 114 SLN were excised due to additional intraoperative discrimination. 95% of visualised SLN could be removed. Histology was positive in 3 patients (8%), all underwent ND which yielded another positive node in 2 cases. Median observation time was 30 months. Two patients (5%) had a neck relapse in combination with a second primary. CONCLUSIONS: SLN biopsy as only surgical staging tool seems to be feasible. SIGNIFICANCE: Method promises reduction of elective ND and morbidity in N0 patients.

Closed versus open operative treatment of nondisplaced diacapitular (Class VI) fractures.

PURPOSE The purpose of the study was assessment of whether open reduction and internal fixation of high nondisplaced, nondislocated diacapitular fractures (Class VI according to Spiessl and Schroll) have better 1-year results compared with closed treatment. PATIENTS AND METHODS Twenty-two patients treated 2001 to 2005 with 26 (4 double) Class VI fractures prospectively entered this evaluation; in randomized fashion 9 (41%) patients had open reduction and internal fixation, 13 (59%) had closed treatment. Facial symmetry, nerve function, scarring, pain, and interincisal maximum distance were judged clinically; condylar translation by sonography; repositioning and reossification upon postoperative and 1-year follow-up radiographs. RESULTS Altogether 17 (77%) patients presented for follow-up; 8 (47%) closed treatment, 9 (53%) open reduction and internal fixation. All patients evinced normal vertical opening. Insufficient condylar translation (<6 mm opening, <3 mm protrusion and mediotrusion) was prevalent in 2 open reduction and internal fixation and 2 closed treatment patients, persistent pain in 2 open reduction and internal fixation patients, and deflection greater than 4 mm in 2 open reduction and internal fixation patients. Partial facial nerve paresis was not encountered. In 1 open reduction and internal fixation patient a broken osteofixation was removed and 1 closed treatment patient had dysocclusion. Vertical medial fragment position was successfully restored by open reduction and internal fixation with, however, considerable remodeling (lateral condyle support is unaltered in Class VI). Closed treatment did not succeed in vertical repositioning but also evinced less remodeling. Angular fragment rectification in open reduction and internal fixation was successful; in closed treatment slight enlargement of the angulation was encountered at follow-up. CONCLUSIONS Closed treatment within this study produced 2 of 8 (25%), open reduction and internal fixation compared with 2 of 9 (22%) unacceptable results and postoperative condyle remodeling. Therefore success rates of 75% versus 78% were attained, and closed treatment should therefore be preferred. However, sufficiently retentive resorbable osteofixation with intraosseous localization could permit better open reduction and internal fixation results than the microplates and screws at the dorsal condylar circumference applied within this study.

Harvesting of intraoral autogenous block grafts from the chin and ramus region: Preliminary results with a variable square pulse Er:YAG laser

It was the aim of this pilot study to evaluate the feasibility, benefits and limitations of a variable square pulse (VSP) Er:YAG laser for harvesting intraoral bone grafts from either the chin or ramus region.

Synthetic bone substitute material comparable with xenogeneic material for bone tissue regeneration in oral cancer patients: First and preliminary histological, histomorphometrical and clinical results.

Background: The present study was first to evaluate the material-specific cellular tissue response of patients with head and neck cancer to a nanocrystalline hydroxyapatite bone substitute NanoBone (NB) in comparison with a deproteinized bovine bone matrix Bio-Oss (BO) after implantation into the sinus cavity. Materials and Methods: Eight patients with tumor resection for oral cancer and severely resorbed maxillary bone received materials according to a split mouth design for 6 months. Bone cores were harvested prior to implantation and analyzed histologically and histomorphometrically. Implant survival was followed-up to 2 years after placement. Results: Histologically, NB underwent a higher vascularization and induced significantly more tartrate-resistant acid phosphatase-positive (TRAP-positive) multinucleated giant cells when compared with BO, which induced mainly mononuclear cells. No significant difference was observed in the extent of new bone formation between both groups. The clinical follow-up showed undisturbed healing of all implants in the BO-group, whereas the loss of one implant was observed in the NB-group. Conclusions: Within its limits, the present study showed for the first time that both material classes evaluated, despite their induction of different cellular tissue reactions, may be useful as augmentation materials for dental and maxillofacial surgical applications, particularly in patients who previously had oral cancer.

Treatment of mandibular angle fractures – Linea obliqua plate versus grid plate

OBJECTIVES To compare treatment outcomes, handling and long term results between two osseo-fixation systems for mandibular angle fractures - the external oblique ridge (external oblique) plate and the grid plate. MATERIAL AND METHODS Sixty patients with mandibular angle fracture were analyzed regarding their operative treatment: 30 patients were treated with an external oblique plate and compared to 30 patients treated with a grid plate on the vestibular cortex. The follow up period was at least 1 year for both groups and the following complications were noted: infection, abnormality in fracture healing, nonunion, pain, hypoaesthesia and dysocclusion. RESULTS The overall average operation time (from intubation to extubation) was 102.1 min (± 44.1 min). Single sided fractures treated with the grid plate needed in average 81.07 min (± 37.9 min) of operation time while single sided fractures treated with the external oblique plate needed 89.3 min (± 42.2 min). In multiple mandibular fractures, no significant change in the operation time between either plating system was found (118.8 ± 35.2 min). After the follow up period fracture healing was considered clinically complete in all patients, but complications occurred significantly more often in the external oblique group (13.3%; N=8) than in the grid plate group (0%; N=0). CONCLUSION Isolated mandibular angle fractures can be more effectively treated using grid plates than using other osteosynthesis techniques. It is an easy to use alternative to conventional miniplate systems with good clinical outcome and fewer complications. An angulated burr and screwdriver has to be used to put on the plate laterally.