Mesenchymal stem cells show radioresistance in vivo.

Irradiation impacts on the viability and differentiation capacity of tissue-borne mesenchymal stem cells (MSC), which play a pivotal role in bone regeneration. As a consequence of radiotherapy, bones may develop osteoradionecrosis. When irradiating human bone-derived MSC in vitro with increasing doses, the cells' self-renewal capabilities were greatly reduced. Mitotically stalled cells were still capable of differentiating into osteoblasts and pre-adipocytes. As a large animal model comparable to the clinical situation, pig mandibles were subjected to fractionized radiation of 2 χ 9 Gy within 1 week. This treatment mimics that of a standardized clinical treatment regimen of head and neck cancer patients irradiated 30 χ 2 Gy. In the pig model, fractures which had been irradiated, showed delayed osseous healing. When isolating MSC at different time points post-irradiation, no significant changes regarding proliferation capacity and osteogenic differentiation potential became apparent. Therefore, pig mandibles were irradiated with a single dose of either 9 or 18 Gy in vivo, and MSC were isolated immediately afterwards. No significant differences between the untreated and 9 Gy irradiated bone with respect to proliferation and osteogenic differentiation were unveiled. Yet, cells isolated from 18 Gy irradiated specimens exhibited a reduced osteogenic differentiation capacity, and during the first 2 weeks proliferation rates were greatly diminished. Thereafter, cells recovered and showed normal proliferation behaviour. These findings imply that MSC can effectively cope with irradiation up to high doses in vivo. This finding should thus be implemented in future therapeutic concepts to protect regenerating tissue from radiation consequences.

In vivo investigation on connective tissue healing to polished surfaces with different surface wettability.

OBJECTIVES: Connective tissue in contact to transgingival/-dermal implants presents itself as tight scar formation. Although rough surfaces support the attachment they increase bacterial colonisation as well. In contrast to surface roughness, little is known about the influence of surface wettability on soft-tissue healing in vivo. We therefore investigated the influence of different surface wettabilities on connective tissue healing at polished implant surfaces in vivo. MATERIAL AND METHODS: Three polished experimental groups (titanium, titanium coated with hydrophobic nano-crystalline diamond (H-NCD) and titanium coated with hydrophilic nano-crystalline diamond (O-NCD) were inserted into the subcutaneous connective tissue of the abdominal wall of 24 rats. Animals were sacrificed after 1 and 4 weeks resulting in eight specimen per group per time point. Specimen were subjected to histological evaluation (van Giesson's staining) and immunohistochemistry staining for proliferating cell nuclear antigen (PCNA), fibronectin and tumour necrosis factor-alpha (TNF-α). RESULTS: Histological evaluation revealed dense scar formation at the titanium and H-NCD surfaces. In contrast, the connective tissue was loose at the O-NCD surface with a significantly higher number of cells after 4 weeks. O-NCD demonstrated a strong expression of PCNA and fibronectin but a weak expression of TNF-α. In contrast, the PCNA and fibronectin expression was low at the titanium and H-NCD, with a strong signal of TNF-α at the H-NCD surface. CONCLUSIONS: Hydrophilicity influences the connective tissue healing at polished implant surfaces in vivo positively. The attachment of connective tissue and the number of cells in contact to the surface were increased. Moreover, the inflammatory response is decreased at the hydrophilic surface.

The role of oxygen termination of nanocrystalline diamond on immobilisation of BMP-2 and subsequent bone formation.

Medical implants are increasingly often inserted into bone of frail patients, who are advanced in years. Due to age, severe trauma or pathology-related bone changes, osseous healing at the implant site is frequently limited. We were able to demonstrate that coating of endosseous implants with nanocrystalline diamond (NCD) allows stable functionalization by means of physisorption with BMP-2. Strong physisorption was shown to be directly related to the unique properties of NCD, and BMP-2 in its active form interacted strongly when NCD was oxygen-terminated. The binding of the protein was monitored under physiological conditions by single molecule force spectroscopy, and the respective adsorption energies were further substantiated by force-field-calculations. Implant surfaces refined in such a manner yielded enhanced osseointegration in vivo, when inserted into sheep calvaria. Our results further suggest that this technical advancement can be readily applied in clinical therapies with regard to bone healing, since primary human mesenchymal stromal cells strongly activated the expression of osteogenic markers when being cultivated on NCD physisorbed with physiological amounts of BMP-2.

Cranio-maxillofacial trauma: a 10 year review of 9,543 cases with 21,067 injuries.

INTRODUCTION: Cranio-maxillofacial trauma management requires pertinent documentation. Using a large computerized database, injury surveillance and research data describe the whole spectrum of injuries. The goal of this study was to assess the effect of the five main causes of accidents resulting in facial injury on the severity of cranio-maxillofacial trauma. PATIENTS AND METHODS: During a period of 10 years (1991-2000) 9,543 patients were admitted to the Department of Oral and Maxillofacial Surgery, University Hospital of Innsbruck with cranio-maxillofacial trauma. Data of patients were prospectively recorded including cause of injury, age and gender, type of injury, injury mechanisms, location and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures and concomitant injuries. Statistical analyses performed included descriptive analysis, chi square test, Fisher's exact test, and Mann-Whitney's U test. This was followed by logistic regression analyses for the three injury types to determine the impact of the five main causes on the type of injury at different ages in facial trauma patients. RESULTS: Five major categories/mechanisms of injury existed: in 3,613 (38%) cases it was activity of daily life, in 2991 (31%) sports, 1170 (12%) violence, in 1,116 (12%) traffic accidents, in 504 (5%) work accidents and in 149 (2%) other causes. A total of 3,578 patients (37.5%) had 7,061 facial bone fractures, 4,763 patients (49.9%) suffered from 6,237 dentoalveolar, and 5,968 patients (62.5%) from 7,769 soft tissue injuries. Gender distribution showed an overall male-to-female ratio of 2.1 to 1 and the mean age was 25.8+/-19.9 years; but both varied greatly depending on the injury mechanism (facial bone fractures: 35.4+/-19.5 years, higher risk for males; soft tissue injuries: 28.7+/-20.5, no gender preference; dentoalveolar trauma: 18+/-15.6, elevated risk for females). For patients sustaining facial trauma, logistic regression analyses revealed increased risks for facial bone fractures (225%), soft tissue lesions (58%) in patients involved in traffic accidents, and dental trauma (49%) during activities of daily life and play accidents. When compared with other causes, the probability of suffering soft tissue injuries and dental trauma, but not facial bone fractures, is higher in sports-related accidents, 12 and 16%, respectively. CONCLUSION: This study differentiated between injury mechanisms in cranio-maxillofacial trauma. The specially trained surgeons treating cranio-maxillofacial trauma are the primary source of information for the public and legislators on implementing preventive measures for high-risk activities. In facial trauma, older persons are prone to bone fractures (increase of 4.4%/year of age) and soft tissue injuries (increase of 2%/year of age) while younger persons are more susceptible to dentoalveolar trauma (decrease of 4.5%/year of age).

Dentofacial trauma in sport accidents.

Trauma due to sports shows a tremendous impact to a site of the body which is not coverable. The purpose of this study was to document the overall rates of dentofacial injuries sustained in 42 different sports and to determine the distribution of main injury types among sports and the most common injury type in frequent kinds of sport. The results indicate that sport accidents were responsible for six times as many facial injuries as work accidents and accounted for three times more injuries than violence or traffic accidents. Sports with high speed and high impact resulted more in facial bone fractures, whereas sports with low speed and low impact ended more in dental injuries.

BMP-2 immobilized on nanocrystalline diamond-coated titanium screws; demonstration of osteoinductive properties in irradiated bone.

BACKGROUND: Irradiation results in impaired bone healing. Thus, osteosynthesis procedures are afflicted with increased failure rates. To improve osseointegration bone morphogenetic protein-2 (BMP-2) immobilized on nanocrystalline diamond (NCD)-coated implant surfaces might be 1 solution. METHODS: By 4 weeks after irradiation of pig's mandible with a dose of 60 Gy a fracture was accomplished. Osteosynthesis was performed either with titanium osteosynthesis screws or NCD-coated screws with immobilized BMP-2. Nonirradiated animals served as control. After 1, 2, 4, and 8 weeks screws were evaluated histologically. Bone biopsies were gained to extract mesenchymal stem or precursor cells (MSCs). RESULTS: MSCs after irradiation demonstrated a behavior comparable to that of unirradiated cells. Consequently, immobilized BMP-2 resulted in an initial increased bone contact ratio (p = .014) but demonstrated no sustainable effect compared with osseointegration in nonirradiated bone (p = .08). CONCLUSION: Immobilized BMP-2 demonstrates an osteoinductive effect in irradiated bone. MSCs as effector cells possess protective mechanisms to overcome the destructive effect of irradiation.

Epidemiologic evidence of barometric pressure changes inducing increased reporting of oral pain.

BACKGROUND AND OBJECTIVE: The daily patient flow at dental emergency departments is subject to fluctuations. The aim of the present study was to investigate whether meteorological parameters were associated with the number of patients reporting acute pain in the oral cavity. METHODS: We performed a retrospective review of all patients presenting with acute oro-dental pain (n=1090) at the dental outpatient clinic in Innsbruck, Austria from January to March 2005. In addition, local weather data were supplied by the Central Institute for Meteorology and Geodynamics Austria. After exponential smoothing of both series of observations, linear regression on the number of patients was performed. RESULTS: Statistical analysis revealed that the acute pain symptoms are not related to the air pressure itself but to the deviation of air pressure. The stronger the daily deviation from the average atmospheric pressure was, the more patients presented with acute pain at the dental emergency department (p=4.2 × 10(-14)). Our findings implicate that the association of air pressure deviation with variation in patient flow at dental clinics is a consequence of barometric pressure-related oral pain. CONCLUSIONS: These findings suggest that changes in barometric pressure were the reason for the observed initiation and/or exacerbation of the various oral pains observed in the emergency room setting. This association has been considered to be rare, with most reports suggesting this phenomenon primarily affects divers and aircraft personnel. Our data suggests otherwise, by providing clear evidence that atmospheric pressure changes commonly influences painful oral conditions.

Craniomaxillofacial trauma in children: a review of 3,385 cases with 6,060 injuries in 10 years.

PURPOSE: Trauma is the leading cause of diseases and death in children. The goal of this study was to assess the impact of the main causes of accidents among children resulting in pediatric craniomaxillofacial trauma. PATIENTS AND METHODS: Between 1991 and 2000, data for 3,385 patients younger than 15 years of age who sustained a total of 6,060 craniomaxillofacial injuries were recorded for cause of injury, age and gender distribution, frequency and type of injury, injury mechanisms, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, and concomitant injuries. Univariate statistical analyses were followed by logistic regression analyses for the 3 injury types to determine the impact of the main injury causes on the type of injury at different ages in pediatric facial trauma patients. RESULTS: Play (58.2%), sport (31.8%), and traffic accidents (5%), acts of violence (3.9%), and other causes (1.1%) were noted. A total of 389 patients (11.5%) had 615 fractures, 2,582 patients (76.3%) had 3,384 dentoalveolar injuries, and 1,697 patients (50.1%) had 2,061 soft tissue injuries. The girl-to-boy ratio was 3:5, and the mean age was 7 +/- 4.4 years. For children sustaining facial trauma, logistic regression analyses revealed increased risks for fractures (+238%) and soft tissue lesions (+89%) in children involved in traffic accidents. Dental trauma was more frequent (>+38%) in both sport and play accidents (all P <.001). CONCLUSIONS: This study dissected the distinct impact of injury mechanisms in pediatric craniomaxillofacial trauma. Logistic regression analyses revealed statistically highly significant outcome differences in pediatric facial trauma depending on the injury mechanism.