A single-centre retrospective 10-year experience of the rhombic 3D condylar fracture plate for open reduction and internal fixation of condylar neck and base fractures.

Fractures of the mandibular condyle account for a significant proportion of mandibular fractures. The specific functional loads require particular specifications for the implant design used for open reduction and internal fixation of such fractures. The clinical and radiographic outcomes in patients treated using a single rhombic 3D condylar fracture plate for open reduction and internal fixation at a single institution, and who fulfilled the inclusion and exclusion criteria, are presented. The primary outcome variables were: occlusion, maximum interincisal distance and mandibular excursion at 1, 3, and 6 months postoperatively, and radiographic measurements for mandibular height and gonion angle. In total, 263 patients were included, of whom 173 (65.8%) were male and 90 (34.2%) female. The mean age was 40.4 ± 18.9 years. There was satisfactory occlusion in 98.9% of patients at the 6-month follow-up, and a significant improvement in all parameters for mandibular excursion (p < 0.001), with a reduced ramus height and an increase in the gonion angle on the fractured side. Excellent clinical and radiographic results were achieved using the rhombic-shaped implant, deeming it appropriate for the osteosynthesis of mandibular condyle fractures.

Development of a test bench for biomechanical simulation-a preliminary study of mandibular forces.

Purpose: The aim of this study is to develop a test bench, which integrates different complexity levels and enables in that way a flexible and dynamic testing for mid and long term intervals as well as testing of maximum loads till implant failure of different osteosynthesis systems on the mandible. Material and Methods: For this purpose, an analysis of the state of the art regarding existing test benches was combined with interviews of clinical experts to acquire a list of requirements. Based on these requirements a design for a modular test bench was developed. During the implementation of the test stand, functional tests were continuously carried out and improvements made. Depending on the level of complexity, the test bench can be used either as an incorporated variant or as a standalone solution. In order to verify the performance and the degree of fulfilment of the requirements of these two variants of the test bench, preliminary studies were carried out for all levels of complexity. In these preliminary studies, commercially available osteosynthesis and reconstruction plates were investigated for their biomechanical behaviour and compared with data from the literature. Results: In total, fourteen test runs were performed for the different levels of complexity. Firstly, five test runs were executed to test the simplified load scenario in the incorporated variant of the test bench. High forces could be transmitted without failure of the miniplates. Secondly a quasi-static test scenario was examined using the incorporated variant with simplified load insertion. Five experiments with a number of cycles between 40,896 and 100,000 cycles were carried out. In one case the quasi-static testing resulted in a fracture of the tested reconstruction plate with a failure mode similar to the clinical observations of failure. The last four test runs were carried out using the standalone variant of the test bench simulating complex load patterns via the insertion of forces through imitated muscles. During the test runs joint forces were measured and the amplitude and vector of the resulting joint forces were calculated for both temporomandibular joints. Differences in the force transmission depending on the implant system in comparison to the zero sample could be observed. Conclusion: The presented modular test bench showed to be applicable for examination of the biomechanical behavior of the mandible. It is characterized by the adjustability of the complexity regarding the load patterns and enables the subsequent integration of further sensor technologies. Follow-up studies are necessary to further qualify and optimize the test bench.

Three-dimensional measurements of symmetry for the mandibular ramus.

BACKGROUND: The study examines a sample of patients presenting for viscerocranial computer tomography that does not display any apparent signs of asymmetry, assesses the three-dimensional congruency of the mandibular ramus, and focuses on differences in age and gender. METHODS: This cross-sectional cohort study screened viscerocranial CT data of patients without deformation or developmental anomalies. Segmentations were obtained from the left and right sides and superimposed according to the best-fit alignment. Comparisons were made to evaluate three-dimensional congruency and compared between subgroups according to age and gender. RESULTS: Two hundred and sixty-eight patients were screened, and one hundred patients met the inclusion criteria. There were no statistical differences between the left and right sides of the mandibular ramus. Also, there were no differences between the subgroups. The overall root mean square was 0.75 ± 0.15 mm, and the mean absolute distance from the mean was 0.54 ± 0.10 mm. CONCLUSION: The mean difference was less than one millimetre, far below the two-millimetre distance described in the literature that defines relative symmetry. Our study population displays a high degree of three-dimensional congruency. Our findings help to understand that there is sufficient three-dimensional congruency of the mandibular ramus, thus contributing to facilitating CAD-CAM-based procedures based on symmetry for this specific anatomic structure.

Alloplastic reconstruction of the mandible after subtotal mandibulectomy for medication-related osteonecrosis of the jaw: An update of the method.

BACKGROUND: Reconstruction of continuity defects following osteonecrosis in multimorbid patients is challenging. In all cases of the predescribed palliative treatment method for alloplastic mandible reconstruction, plate fractures were detected in follow-up. We hypothesized that a modification could avoid these fractures, leading to stable long-term results. METHODS: This retrospective study compares the original method with a modification using single, laser-sintered CAD-CAM plates instead of manually bent miniplates. The predescribed shuttering technique was used to reconstruct the mandible in its original shape with bone cement. RESULTS: Uneventful wound healing was observed in 86% of the cases after modification of the method. No implant or plate fracture occurred. CONCLUSIONS: The presented method should be considered as a treatment option for mandible reconstruction in elderly, multimorbid patients in palliative situations. The results of this study suggest that the modification of the method leads to significantly improved long-term stability. Donor site morbidity is avoided with this method of palliative surgery.

Probing real-world Central European population midfacial skeleton symmetry for maxillofacial surgery.

OBJECTIVES: Symmetry is essential for computer-aided surgical (CAS) procedures in oral and maxillofacial surgery (OMFS). A critical step for successful CAS is mirroring the unaffected side to create a template for the virtual reconstruction of the injured anatomical structure. The aim was to identify specific anatomical landmarks of the midfacial skeleton, to evaluate the symmetry in a group of the real-world Central European population, and to use these landmarks to assess midfacial symmetry in CT scans. MATERIAL AND METHODS: The retrospective cross-sectional study defined landmarks of the midface's bony contour using viscerocranial CT data. The distances of the skeletal landmarks (e.g., the frontozygomatic suture and temporozygomatic suture) of the left and right sides from the midline were measured and statistically compared. Midfacial symmetry for reference points was defined as a difference within 0 mm and their mean difference plus one standard deviation. RESULTS: We examined a total of 101 CT scans. 75% of our population shows symmetrical proportions of the midface. The means of the differences for the left and right sides ranged from 0.8 to 1.3 mm, averaging 1.1 ± 0.2 mm for all skeletal landmarks. The standard deviations ranged from 0.6 to 1.4 mm, with a computed mean of 0.9 ± 0.3 mm. CONCLUSION: We established a methodology to assess the symmetry of the bony midface. If the determined differences were equal to or lower than 2.5 mm in the mentioned midfacial skeletal landmarks, then the symmetry of the bony midface was considered present, and symmetry-based methods for CAS procedures are applicable. CLINICAL RELEVANCE: Many CAS procedures require facial symmetry. We provide an easy-to-apply method to probe for symmetry of the midface. The method may be used for population-based research, to check for proper reduction of fractures after reposition or to screen for symmetry prior to CAS planning.

Adjuvant Radiotherapy in Patients with Squamous Cell Carcinoma of the Oral Cavity or Oropharynx and Solitary Ipsilateral Lymph Node Metastasis (pN1)-A Prospective Multicentric Cohort Study.

(1) Background: Evaluation of impact of adjuvant radiation therapy (RT) in patients with oral squamous cell carcinoma of the oral cavity/oropharynx (OSCC) of up to 4 cm (pT1/pT2) and solitary ipsilateral lymph node metastasis (pN1). A non-irradiated group with clinical follow-up was chosen for control, and survival and quality of life (QL) were compared; (2) Methods: This prospective multicentric comprehensive cohort study included patients with resected OSCC (pT1/pT2, pN1, and cM0) who were allocated into adjuvant radiation therapy (RT) or observation. The primary endpoint was overall survival. Secondary endpoints were progression-free survival and QL after surgery; (3) Results: Out of 27 centers, 209 patients were enrolled with a median follow-up of 3.4 years. An amount of 137 patients were in the observation arm, and 72 received adjuvant irradiation. Overall survival did not differ between groups (hazard ratio (HR) 0.98 [0.55-1.73], p = 0.94). There were fewer neck metastases (HR 0.34 [0.15-0.77]; p = 0.01), as well as fewer local recurrences (HR 0.41 [0.19-0.89]; p = 0.02) under adjuvant RT. For QL, irradiated patients showed higher values for the symptom scale pain after 0.5, two, and three years (all p < 0.05). After six months and three years, irradiated patients reported higher symptom burdens (impaired swallowing, speech, as well as teeth-related problems (all p < 0.05)). Patients in the RT group had significantly more problems with mouth opening after six months, one, and two years (p < 0.05); (4) Conclusions: Adjuvant RT in patients with early SCC of the oral cavity and oropharynx does not seem to influence overall survival, but it positively affects progression-free survival. However, irradiated patients report a significantly decreased QL up to three years after therapy compared to the observation group.

Methodology: workflow for virtual reposition of mandibular condyle fractures.

BACKGROUND: Even though mandibular condyle fractures have a high clinical relevance, their treatment remains somewhat challenging. Open reduction and internal fixation are difficult due to narrow surgical approaches, poor overview during reduction, and a possible risk of facial nerve damage. In times of technical endeavors in surgery, there is a trend towards the usage of stable CAD-CAM-implants from additive manufacturing or titanium laser sintering. Up until now, there have not been any reports of fracture treatment of the mandibular condyle using this technique. RESULTS AND CONCLUSION: We present a workflow for virtual repositioning of the fractured mandibular condyle, to manufacture patient-specific implants for osteosynthesis with the intention of use of resorbable metal alloys in the future.

Cost minimization analysis of indication-specific osteosynthesis material in oral and maxillofacial surgery.

PURPOSE: Following the introduction of the Regulation (EU) 2017/745 by the European Parliament, any bioactive substance or surgical implant introduced into the human body must be documented. The regulation requires any implant to be traced back to the manufacturer. Lot numbers need to be available for every single medical implant. Also, the manufacturer is required by law to provide implants individually packaged and sterilized. Previously, model tray systems (MOS tray) were used for osteosynthesis in oral and maxillofacial surgery, in which the individual implants could not be registered separately. The new regulation made it impossible to use such processes during surgery anymore and a need for a change in the medical practice surged. We examined a possible solution for the new legislation. The aim of this prospective cohort study is to analyze the MOS tray systems to osteosynthesis materials prepackaged in sets. We record and evaluate parameters such as surgical time and documentation time. We perform a short cost analysis of our clinic. The primary aim is to determine how much time is gained or lost by the mandatory increased patient safety. The secondary aim is to describe change in costs. METHODS: Patients that underwent standard surgical procedures in the clinic of oral and maxillofacial surgery of the faculty hospital Carl Gustav Carus in Dresden were included. We chose open reduction and internal fixation (ORIF) of anterior mandibular corpus fractures as well as mandibular advancement by means of bilateral sagittal split osteotomies (BSSO) as standardized procedures. Both of these procedures require two osteosynthesis plates and at least four screws for each plate. MOS trays were compared to prepackaged sterilized sets. The sets include a drill bit, two plates, and eight 5-mm screws. A total number of 40 patients were examined. We allocated 20 patients to the ORIF group and the other 20 patients to the BSSO group. Each group was evenly subdivided into a MOS tray group and a prepackaged group. Parameters such as the incision-suture time (IST) as well as the documentation time (DT) by the operating room (OR) staff to complete documentation for the implants are the main focus of investigation. RESULTS: For open reduction, the incision-suture time was significantly different in favor of the MOS tray (p < 0.05). There was no difference in the BSSO groups. However, we observed a significantly different (p < 0.01) documentation time advantage for the prepackaged sets in both the ORIF and BSSO groups. On top of that, we find that by using the prepackaged kits, we are able to reduce sterilization costs by €11.53 per size-reduced container. Also, there is also a total cut of costs of €38.90 and €43.70, respectively, per standardized procedure for implant material. CONCLUSIONS: By law, a change in the method of approaching surgery is necessary. For standardized procedures, the right choice of implants can lead to a reduction of documentation time and costs for implant material, sterilization, as well as utilizing less instruments. This in turn leads to lower costs for perioperative processing as well as provision of state-of-the-art implant quality implementing higher patient security.

Enhancing Anticoagulation Monitoring and Therapy in Patients Undergoing Microvascular Reconstruction in Maxillofacial Surgery: A Prospective Observational Trial.

BACKGROUND: In reconstructive surgery, loss of a microvascular free flap due to perfusion disorders, especially thrombosis, is a serious complication. In recent years, viscoelastic testing (VET) has become increasingly important in point-of-care (POC) anticoagulation monitoring. This paper describes a protocol for enhanced anticoagulation monitoring during maxillofacial flap surgery. OBJECTIVE: The aim of the study will be to evaluate, in a controlled setting, the predictive value of POC devices for the type of flap perfusion disorders due to thrombosis or bleeding. VET, Platelet monitoring (PM) and standard laboratory tests (SLT) are comparatively examined. METHODS/DESIGN: This study is an investigator-initiated prospective trial in 100 patients undergoing maxillofacial surgery. Patients who undergo reconstructive surgery using microvascular-free flaps will be consecutively enrolled in the study. All patients provide blood samples for VET, PM and SLT at defined time points. The primary outcome is defined as free flap loss during the hospital stay. Statistical analyses will be performed using t-tests, including the Bonferroni adjustment for multiple comparisons. DISCUSSION: This study will help clarify whether VET can improve individualized patient care in reconstruction surgery. A better understanding of coagulation in relation to flap perfusion disorders may allow real-time adaption of antithrombotic strategies and potentially prevent flap complications.

Multiple periapical dysplasias analyzed by cone-beam-computer tomography and 99Tcm-Scintigraphy.

Periapical cemental dysplasia (PCD) is considered a non-neoplastic proliferation of fibrous tissues and cementum-like hard tissues, usually occurring in the periapical regions of teeth. PCD is characterized by the presence of vital pulp and is often accidentally discovered during a general radiographic survey. PCD may arise from the tissue of odontogenic origin or occur as a reactive process in the periapical tissue. Multilocular occurrences in both jaws are rare. However, we encountered a case of multiple PCDs by orthopantomography, which showed different degrees of maturation in the mandible and maxilla by osteodensitometric detection via cone-beam computed tomography (CB-CT) validated by Tc-99m bone-scintigraphy (BS). Biopsies confirmed the radiological results. CB-CT osteodensitometry allows for the categorization and assessment of different stages of PCD maturation from beginning to florid, detection of remittent osseous changes, and evaluation in the clinical follow-up. When using the local cortical bone as a reference value of 100%, periapical dysplasias show density values of 75% in the mandible and 80% in the maxilla. Early classification of PCD is possible with CB-CT osteodensitometry.

Osteosynthesis of the Mandibular Condyle With Magnesium-Based Biodegradable Headless Compression Screws Show Good Clinical Results During a 1-Year Follow-Up Period.

PURPOSE: The use of titanium-based implants in mandibular condyle fractures can require implant removal because of screw penetration through the condylar surface. The use of biodegradable implants can avoid a second operation for implant removal and the associated possible complications. We investigated the clinical and radiologic outcomes of osteosynthesis of mandibular condyle fractures (MCFs) with biodegradable magnesium-based compression screws. MATERIALS AND METHODS: We performed a retrospective observational study of 6 patients who had been treated at our department. We recorded the changes in jaw movements over time, occlusion, and possible complications at defined intervals of 1, 3, 6, and 12 months postoperatively. We also compared the preoperative computed tomography (CT) scans with the postoperative cone-beam CT (CBCT) scans at 6 and 12 months postoperatively to evaluate mandibular condyle healing and screw degradation. RESULTS: Of the 6 patients, 4 were men and 2 were women, with a mean age of 43.2 years (range, 30 to 66 years). All 6 patients had unilateral MCFs. All the patients showed well-restored function of the temporomandibular joint with significant improvement in mouth opening (46.17 ± 6.49 mm), right (10.67 ± 1.03 mm) and left (10.67 ± 1.97 mm) laterotrusion, and protrusion (10.17 ± 1.33 mm) distances to physiologic values. The CBCT scans showed the remodeling processes of the mandibular condyle and a few radiolucencies indicating the magnesium-based screws. Although penetration of 1 screw tip through the condylar surface had occurred, no implant removal was necessary owing to biodegradation of the implant. CONCLUSIONS: The results of the present study have shown that biodegradable magnesium-based compression screws provide good clinical results and avoid implant removal.

Intraosseous anesthesia in symptomatic irreversible pulpitis: Impact of bone thickness on perception and duration of pain.

BACKGROUND: Intraosseous anesthesia (IO) allows the anesthetic solution to be injected directly into the cancellous bone. The anesthetic solution immediately reaches the periapical region, and thus the axonal area of the nerve, where it can temporarily disable the sodium pump. The effect is felt almost without any time delay, and only a small amount of anesthetic solution is required. METHODS: This study aims to investigate the efficacy of IO using the Anesto® device after infiltration anesthesia (IA) and/or inferior alveolar nerve block anesthesia (IANB) failed to work in symptomatic irreversible pulpitis (hot tooth). The 33 patients included in the study were treated additionally with 1.7 ml articaine hydrochloride with 1:100,000 epinephrine hydrochloride (Ultracain® D-S, Sanofi-Aventis, Frankfurt, Germany) IO. RESULTS: The electrical pulp test showed that 95.76% of the volunteers reacted positively to the combination of IANB or IA with the IO. In women, the additive IO was effective at 97.22%. In men, the IO led to pain elimination in 94.00% of cases. The duration of the IO was less than a quarter of an hour (13.03 min). The IO worked longer in women than in men (13.61 min vs. 12.33 min). Overall, more than every third tooth that needed trepanation was located in the posterior area of the mandible (36.4%). Treatment of hot teeth in this area was associated with an increased pulse rate and increased residual pain. There was a moderate correlation (Spearman-Rho [IRI] = 0.280) between the Visual Analog Scale (VAS) score and bone density, and a significant correlation (IRI = 0.612) between subjective residual pain and bone width. The IO resulted in a moderate, transient increase in the pulse rate by approximately 20 bpm. This is similar to the temporary increase in heart rate after conventional anesthesia techniques in non-preloaded patients and can be considered clinically irrelevant. CONCLUSION: IO with the Anesto® device as an extension and deepening of local pain elimination is recommended for the treatment of hot teeth.

Biomechanical Evaluation of Mandibular Condyle Fracture Osteosynthesis Using the Rhombic Three-Dimensional Condylar Fracture Plate.

PURPOSE: The aim of the present study was to evaluate the biomechanical stability of osteosynthesis in mandibular condyle fractures using a newly designed rhombic 3-dimensional (3D) condylar fracture plate and compare it with that using standard two 4-hole miniplates and with that in nonfractured condyles. MATERIALS AND METHODS: Using 200 porcine mandibles, 3 different monocortical plating techniques were evaluated. The condyles were fractured along a defined line tangentially through the sigmoid notch and perpendicular to the posterior border. After anatomic reduction, osteosynthesis was performed using either standard rhombic 3D condylar fracture plates and standard screws (group A) or locking rhombic 3D condylar fracture plates, which were fixed either with standard screws (group B) or locking screws (group C). For comparison, nonfractured condyles (group D) and condyles fixed with standard two 4-hole miniplates and 8 screws (group E) were included. Using a universal mechanical testing machine (TIRA Test 2720; TIRA GmbH Schalkau, Germany), each group was subjected to linear loading from laterally to medially, medially to laterally, anteriorly to posteriorly, and posteriorly to anteriorly. The maximum axial force and displacement at the maximum force were measured. The mean values were compared for statistical significance using analysis of variance with Bonferroni's correction (statistical significance set at P < .05). RESULTS: The main mode of failure in the plating techniques investigated was the pull out of screws from the proximal fragment. We found no statistically significant differences in the stability of osteosynthesis between the two 4-hole miniplates and the rhombic 3D condylar fracture plate when loading from posteriorly to anteriorly, laterally to medially, and medially to laterally. However, when loading from anteriorly to posteriorly, a statistically significant difference between the standard and locking system and the two 4-hole miniplate system was observed, with the latter proving more stable. CONCLUSIONS: The results of the present biomechanical study suggest that the rhombic 3D condylar fracture plates are suitable for the treatment of condylar neck fractures. Both types of the plate are able to resist physiologic strains comparable to the two 4-hole miniplates.

Multiple brain abscesses in an immunocompetent patient after undergoing professional tooth cleaning.

BACKGROUND: Dental disorders and dental treatment are among the variety of causes of brain abscess. CASE DESCRIPTION: The authors present the case of a patient who developed multiple brain abscesses after undergoing professional tooth cleaning. The results of a diagnostic work-up ruled out an underlying immunodeficiency. After receiving neurosurgical intervention and intensive care treatment by means of local and intravenous antibiotics for 24 days, the patient was transferred to another hospital for rehabilitation. Six months after the treatment, the patient still had moderate residual paresis of the left leg. PRACTICAL IMPLICATIONS: Although it happens rarely, professional tooth cleaning may be considered a cause of brain abscesses even in otherwise healthy patients.

Biomechanical study of the Delta plate and the TriLock Delta condyle trauma plate.

PURPOSE: The aim of this study was to evaluate in mandibular condylar process fractures the biomechanical stability of osteosynthesis using the Delta plate and the TriLock Delta condyle trauma plate and to compare these with 2 4-hole miniplates. MATERIALS AND METHODS: The condyles of 120 porcine mandibles were fractured at a defined location. After anatomic reduction, the fractures were fixed with a Delta plate, a TriLock Delta condyle trauma plate, or 2 4-hole miniplates (40 per group). Each group was subjected to linear loadings in 4 different directions with a universal mechanical testing machine (TIRA Test 2720). Yield load and yield displacement were measured for the 2 Delta plates and the 2 miniplates. Means were derived and compared for statistical significance using the Kruskal-Wallis test with a confidence level of 95% (P < .05). RESULTS: None of the plates broke. In 4 cases using the double miniplate and in 2 cases using the Delta plate, osteosynthesis screw loosening was registered. In lateral-to-medial and anterior-to-posterior directions, the 2 miniplates tolerated the highest loads. From medial to lateral and from posterior to anterior, the TriLock Delta condyle trauma plate resisted the highest loads. However, there was a statistically significant difference among all osteosynthesis systems only for medial-to-lateral loads. Statistical analysis for displacement showed significant differences among all plates in the 4 directions. CONCLUSIONS: This biomechanical study indicates that for rigid internal fixation of condylar fractures of the mandible, similar to 2 miniplates, the 2 Delta plates (Delta plate with gliding holes and TriLock Delta plate) fulfill the principles of a functional and stable osteosynthesis. Both are able to resist physiologic strains. The locking plate (TriLock Delta condyle trauma plate) has the advantages of greater primary stability and decreased likelihood of screw loosening.

Resorbable triangular plate for osteosynthesis of fractures of the condylar neck.

We describe a new design of resorbable plate for use in the treatment of fractures of the condylar neck, and report the outcome of initial treatment in two patients.

Prefabricated bony radial forearm flap for secondary mandible reconstruction after radiochemotherapy.

BACKGROUND: Primary reconstruction of the mandible is the golden standard of surgical treatment after ablative tumor surgery. Many different microvascular bone grafts are used to reduce wound healing complications at the severely compromised recipient site. The loss of primary grafts due to radiotherapy or osteoradionecrosis can make secondary mandibular reconstruction necessary. To address this problem, we developed the technique of the prefabrication of a radial forearm flap with cancellous bone. The aims were to establish these techniques into the clinical routine and to create a safe and reliable flap with low donor site morbidity. METHODS: In patients who had undergone ablative tumor surgery radiochemotherapy, and primary reconstruction, prefabricated bony radial forearm flaps (PBRFFs) were applied for secondary reconstruction of the mandible. Cylinders of cancellous bone taken from the iliac crest were implanted in the lower forearm to allow the necessary vascularization. After a healing period of 4 weeks, the PBRFF was elevated and grafted into the mandibular defect. RESULTS: All grafts healed uneventfully. However, 1 case required revision of the venous anastomosis after 2 days. The transplants improved the contour of the lower face enabling a good correction of the facial asymmetry. During the follow-up of up to 4 years, the radiographic controls showed good bony consolidation between the graft and the stumps of the mandible as well as formation of cortical bone around the cancellous bone cylinders. CONCLUSION: These results demonstrate that the PBRFF is a safe and reliable graft which provides alternate solution in which other microvascular bone grafts have already failed. In the future, the iliac bone graft may be replaced with scaffold seeded with stem cells for further reduction of donor site morbidity.

Immunohistochemical comparison of markers for wound healing on plastic-embedded and frozen mucosal tissue.

Immunohistologic investigations of wound healing in human oral mucosa require specific cell biological markers as well as consecutive small biopsies. Small specimens are ideally embedded in plastic (methylmethacrylate, MMA) resin due to their miniature size. This limits the use of antibodies for these markers. In this immunohistochemical study, the distribution of wound healing markers, e.g. cytokeratin (CK), laminin, collagen IV, vimentin, vinculin and fibronectin, were compared between semithin sections of plastic-embedded tissue and frozen sections of mucosal tissue in order to assess their use for future investigations. The antibodies against laminin, collagen IV and CK 1/2/10/11, 5/6, 13, 14, 17, 19 gave comparable staining patterns on cryostat sections of attached mucosa and on semithin sections of MMA-embedded attached mucosa. In the epithelial cell layers, the following distribution of CK immunostaining was observed: The basal cell layer was positive for CK 5/6, CK 14 and CK 19; the intermediate cell layer for CK 13, CK 17 and CK 1/2/10/11, and the superficial cell layer for CK 13 and CK 1/2/10/11. For most of these antibodies, enzyme digestion with 0.1% trypsin was adequate for demasking the antigens, except for anti-CK 14, anti-CK 17 and anti-laminin; predigestion with 0.4% pepsin in 0.01 N HCl gave similar staining results. The antibodies against vimentin, vinculin, fibronectin and CK 4 showed no affinity or a reciprocal reaction on the semithin sections. Therefore, the antibodies against CK 1/2/10/11; 5/6; 13; 14; 17, and 19, as well as the basement proteins laminin and collagen IV are deemed markers suitable on semithin sections of plastic-embedded attached oral mucosa.

O-phospho-L-serine: a modulator of bone healing in calcium-phosphate cements.

Bone substitution materials are seen as an alternative to autogenous bone transplants in the reconstruction of human bone structures. The aim of the present animal study was to evaluate the clinical handling and the conditions of bone healing after the application of a phosphoserine and collagen-I-modified calcium-phosphate cement (Biozement D). The application of phosphoserine is supposed to influence the texture of the extracellular matrix. Standardised bone defects were created in the lower jaw of 10 adult minipigs. These defects were reconstructed with a pasty calcium-phosphate cement mixture. After a healing time of 4 months, the animals were sacrificed. The mandibles of all animals were resected and non-decalcified histological sections of the areas of interest were prepared. The experiment was evaluated by means of qualitative histology and histomorphometry. The hydroxyapatite cement entirely hardened intraoperatively. Modelling and handling of the cement was facile and the margin fit to the host bone was excellent. Histology showed that resorption started in the periphery and proceeded exceptionally fast. The bony substitution, especially in phosphoserine-endowed cements, was very promising. After a healing period of 4 months, phosphoserine cements showed a bone regeneration of nearly two-thirds of the defect sizes. In the applied animal experiment, the newly developed hydroxyapatite collagen-I cement is well suited for bone substitution due to its easy handling, its excellent integration and good resorption characteristics. The addition of phosphoserine is very promising in terms of influencing resorption features and bone regeneration.

Bone welding--a histological evaluation in the jaw.

The expansion of biodegradable osteosynthesis systems in clinical application correlates well to the progress in development of new materials as to the improvement of application methods. One of those new application methods is the ultrasound-aided insertion of Resorb-X pins. The aim of this study was the histological evaluation of possible thermal damage to bone due to the ultrasound insertion. For this purpose, condylar neck fractures in 12 sheep were produced, repositioned and fixed by Resorb-X plates and pins. The animals were sacrificed in two groups, one after 2 weeks and one after 9 weeks. The bone-pin interlinkage and the structure of the bone were histologically evaluated. After 2 weeks a tight bone-polymer interlinkage was seen. Neither a pronounced foreign body reaction nor an interposition of fibrous tissue at the interface or a thermally induced necrosis was observed. The late phase of wound healing after 9 weeks showed pathomorphological characteristics within the normal range of bone healing. The bone seemed to be free of any alteration caused by process engineering. We conclude that thermal stress caused by ultrasound-aided pin insertion does not lead to cellular reaction in the bone. The fast and easy application of this improved biodegradable osteosynthesis system will bring a clear advantage in clinical use.