Unmanned aerial vehicles (drones) in out-of-hospital-cardiac-arrest.

BACKGROUND: The use of an automated external defibrillator (AED) prior to EMS arrival can increase 30-day survival in out-of-hospital cardiac arrest (OHCA) significantly. Drones or unmanned aerial vehicles (UAV) can fly with high velocity and potentially transport devices such as AEDs to the site of OHCAs. The aim of this explorative study was to investigate the feasibility of a drone system in decreasing response time and delivering an AED. METHODS: Data of Global Positioning System (GPS) coordinates from historical OHCA in Stockholm County was used in a model using a Geographic Information System (GIS) to find suitable placements and visualize response times for the use of an AED equipped drone. Two different geographical models, urban and rural, were calculated using a multi-criteria evaluation (MCE) model. Test-flights with an AED were performed on these locations in rural areas. RESULTS: In total, based on 3,165 retrospective OHCAs in Stockholm County between 2006-2013, twenty locations were identified for the potential placement of a drone. In a GIS-simulated model of urban OHCA, the drone arrived before EMS in 32 % of cases, and the mean amount of time saved was 1.5 min. In rural OHCA the drone arrived before EMS in 93 % of cases with a mean amount of time saved of 19 min. In these rural locations during (n = 13) test flights, latch-release of the AED from low altitude (3-4 m) or landing the drone on flat ground were the safest ways to deliver an AED to the bystander and were superior to parachute release. DISCUSSION: The difference in response time for EMS between urban and rural areas is substantial, as is the possible amount of time saved using this UAV-system. However, yet another technical device needs to fit into the chain of survival. We know nothing of how productive or even counterproductive this system might be in clinical reality. CONCLUSIONS: To use drones in rural areas to deliver an AED in OHCA may be safe and feasible. Suitable placement of drone systems can be designed by using GIS models. The use of an AED equipped drone may have the potential to reduce time to defibrillation in OHCA.

Periodontal status of secondary crowded mandibular incisors. Long-term results after orthodontic treatment.

The present study was undertaken to examine whether secondary crowded mandibular incisors experience more periodontal breakdown than aligned lower incisors long-term after orthodontic treatment. Patients from 19 to 35 years after active treatment were selected. 2 groups were established: 1 with crowded mandibular incisors and 1 with aligned incisors. The groups were matched according to age, time after treatment, gender and periodontal disease classification. A separate group with crowded and aligned incisors within the same individual was established. Accumulation of plaque, gingival inflammation, probing pocket depth and probing attachment level were registered at 6 locations around each incisor. Among the patients studied, the oral hygiene level was high. In both groups, the loss of connective tissue attachment was largely due to periodontal pocket formation in interproximal areas and gingival retraction in buccal and lingual areas. A small but statistically significant difference in probing attachment level was found between crowded and aligned interproximal areas within the same individual (P less than 0.05). No differences in accumulation of plaque or in gingival inflammation were found. No differences were found for any of the dependent variables between the groups with crowded and aligned incisors.

Long-term effect of root proximity on periodontal health after orthodontic treatment.

The present investigation was done to evaluate the incidence and distribution of root proximity after orthodontic treatment and to test the hypothesis that interproximal areas with thin interdental bone provide less resistance against marginal periodontal breakdown than areas with normal width of bone between the roots. Only adult patients were examined at least 16 years after active orthodontic treatment. The distance between the roots was measured directly on periapical radiographs. Gingival health, level of connective tissue attachment, and clinical scores for bone levels in sites with thin interdental bone and neighboring or contralateral sites with normal width of bone between the roots were compared. Among the 400 patients studied, 25 had unilateral or bilateral areas with root proximity. Root proximity was diagnosed between maxillary central and lateral incisors in 18 patients, between mandibular central and lateral incisors in two patients, and between maxillary lateral incisor and canine, maxillary first and second molars, mandibular canine and first premolar, mandibular first and second premolars, or mandibular first and second molars in only one patient. No statistically significant differences in inflammation, level of attachment, and bone level were observed between root proximity sites and control sites. The results indicate that anterior teeth are not predisposed to more rapid periodontal breakdown when roots are in close proximity. Too few molar sites were included to draw conclusions regarding such areas.

Periodontal status of teeth facing extraction sites long-term after orthodontic treatment.

The present study was undertaken to examine the long-term periodontal status of teeth orthodontically moved into extraction sites. Patients were examined 14 to 34 years after active orthodontic treatment involving extraction of four first premolars. Three groups were established: one with closed tooth contacts and parallel adjacent teeth, one with closed tooth contacts and tipped adjacent teeth, and one with open contacts between adjacent teeth. Within each group accumulation of plaque, gingival health status, probing pocket depth, and probing attachment level of interproximal tooth surfaces, facing extraction sites and adjacent control sites between canine and lateral incisor were compared. Significantly more probing attachment loss was found in extraction sites with open tooth contacts (P less than 0.01) and with parallel adjacent teeth and closed tooth contacts (P less than 0.05) than in control sites. However, the mean differences were less than 0.5 mm, which may not be considered clinically significant. Tipping of teeth into the extraction sites had no long-term detrimental effect on the probing attachment level. No differences in accumulation of plaque and in gingival health status were observed.

Long-term periodontal status of labially erupted canines following orthodontic treatment.

Periodontal status was studied at the mesiobuccal, midbuccal and distobuccal aspects of contralateral pairs of canines in 22 postorthodontic patients aged 30 to 51 years with a mean time of 26.4 years (SD, 5.6) out of active treatment. The pretreatment models showed one canine erupting severely to the labial ("ectopic") with a contralateral canine in good arch alignment (control). None of the patients experienced relapse of the "ectopic" canine in a labial direction, and none had missing teeth, malalignment, overhanging restorations or open tooth contacts adjacent to the canines evaluated. Periodontal parameters were examined using a Michigan #0 probe with Williams markings. A nonstandardized light force was used and the measurements were rounded to the nearest millimeter. The results demonstrated statistically significant differences between the canines in probing attachment and bone levels (mean, 0.75; SD, 0.92; P less than 0.01) and width of attached gingiva (mean, 0.50; SD, 1.07; p less than 0.05) at the midbuccal aspects. The reason for these differences could only be speculated upon.

Long-term effect of thin interdental alveolar bone on periodontal health after orthodontic treatment.

The present experiment was undertaken to determine if an interproximal area with a thin interdental bone septum following orthodontic treatment provides less resistance against marginal periodontal breakdown than an interproximal area with a normal width of bone between the roots. Only adult patients, at least 16 years after active orthodontic treatment, were studied. The distance between the roots was measured directly on periapical radiographs. Gingival health, level of attachment and bone level in sites with thin interdental bone were compared with neighboring or contralateral sites with a normal width of bone between the roots. No statistically significant differences in inflammation, level of attachment and clinical scores for bone level were observed. When measured radiographically the distance from the cementoenamel junction to the alveolar bone was significantly shorter in neighboring control sites (P less than 0.05). This discrepancy was most likely due to radiographic distortion. The results of this investigation suggest that in anterior areas marginal periodontal breakdown is unrelated to the thickness of bone between the roots. Too few molar sites were included to draw conclusions regarding such areas.

The effect of extraction and orthodontic treatment on dentoalveolar support.

Full-mouth radiographs of ninety-six patients treated by extraction of four first premolars were taken at least 10 years postextraction. Three groups were established: one with extensive crowding in the full permanent dentition treated by extraction and fixed appliance therapy; one treated by serial extraction and fixed appliance therapy; and one treated by serial extraction only. Measurements of tooth length and alveolar bone height were made from the projected radiographs, and buccolingual socket areas were measured from direct tracings of the radiographs. Comparison between groups revealed reduced mean radiographic tooth lengths for incisors and mandibular molars in the orthodontically treated groups. The incidence of root resorption was similar for both treated groups. Reduced alveolar bone heights were noted in the extraction sites of the two orthodontically treated groups but not in the group treated by serial extraction only. Most reduction in long-term dentoalveolar support occurred as a result of root resorption except in the extraction sites, where it occurred largely as a result of bone loss. Root parallelism did not appear to influence proximal bone heights at the extraction site. In malocclusions involving arch length deficiency, maximally displaced canines had reduced long-term proximal bone compared to nondisplaced canines, supporting the concept of encouraging autonomous distal eruption through serial extraction.

Rapidly progressive periodontitis. A distinct clinical condition.

We report radiographic, clinical, historical, and laboratory observations on seven patients selected to illustrate the features and characteristics of rapidly progressive periodontitis, with the aim of establishing this disease as a distinct clinical entity. This form of periodontitis is seen most commonly in young adults in their twenties, but it can occur in postpubertal individuals up to approximately 35 years of age. During the active phase, the gingival tissues are extremely inflamed and there is hemorrhage, proliferation of the marginal gingiva, and exudation. Destruction is very rapid, with loss of much of the alveolar bone occurring within a few weeks or months. This phase may be accompanied by general malaise, weight loss, and depression, although these symptoms are not seen in all patients. The disease may progress, without remission, to tooth loss, or alternatively, it may subside and become quiescent with or without therapy. The quiescent phase is characterized by the presence of clinically normal gingiva that may be tightly adapted to the roots of teeth with very advanced bone loss and deep periodontal pockets. The quiescent phase may be permanent, it may persist for an indefinite period, or the disease activity may return. Most patients with rapidly progressive periodontitis have serum antibodies specific for various species of Bacteroides, Actinobacillus, or both, and manifest defects in either neutrophil or monocyte chemotaxis. Affected patients generally respond favorably to treatment by scaling and open or closed curettage, especially when accompanied by standard doses of antibiotics for conventional time periods. A small minority of patients do not respond to any treatment, including antibiotics, and the disease progresses inexorably to tooth loss even in the presence of aggressive periodontal therapy and maintenance. At the present time it is not possible to distinguish prior to treatment which individuals will respond to therapy and which will not.

Variation of erythrocyte glutathione peroxidase activity in Finn sheep.

Erythrocyte glutathione peroxidase (GSH-Px) which was analysed on a flock of Finn sheep (266 sheep) showed variable activity despite the same diet and selenium intake. Mating experiments suggested that the GSH-Px activity was genetically determined. The low GSH-Px animals showed better performance as shown by a significantly reduced mortality rate of their offspring. Evidence of larger weight gain and wool production in the low GSH-Px sheep was obtained. The GSH-Px activity slightly decreased with age. The erythrocyte GSH-Px activity did not show much correlation with other genetical markers such as the potassium type, GSH type, haemoglobin type or sex. It is proposed that the low GSH-Px may represent an adaptation to low selenium intake.

Association between glutathione, haemoglobin and transferrin in finnsheep.

Haemoglobin (Hb) and transferrin (Tf) types were determined in 760 Finnsheep and correlated with the reduced glutathione (GSH) levels of packed erythrocytes. The gene frequencies of the two haemoglobin alleles A and B were: HbA = 0.748 and HbB = 0.252. Five transferrin alleles were found: A, B, C, D and E, with gene frequencies of 0.056, 0.226, 0.620, 0.075 and 0.023, respectively. The Hb B group had significantly higher GSH levels and lower haematocrit values than heterozygotes (Hb AB) and homozygote (Hb AA). There was no significant difference in GSH concentration among the haemoglobin types in lambs. Erythrocyte glutathione levels of Tf BC ewes were significantly higher than the levels in sheep with other transferrin types, whereas young lambs of Tf AB types had the highest GSH levels. The significance of these findings is discussed.

Subgingival microflora of periodontal patients on tetracycline therapy.

Samples of subgingival plaque were collected from periodontal patients receiving two different tetracycline treatment regimens following conventional periodontal therapy. Four patients had received an oral dose of 1000 mg/day for 2 weeks and nine had received 1000 mg/day for 1 week followed by 250 mg/day for extended time periods. The latter regimen is similar so that commonly prescribed for the chronic skin disease, acne vulgaris. Taxonomic characterization of plaque isolates indicated that the predominant organisms cultured from both treatment groups were species of Streptococcus and the branching, filamentous Gram-positive rods, Actinomyces and Rothia. A much greater microbial complexity was observed among the flora isolated from patients taking 250 mg/day. The latter group harbored many of the fastidious Gram-negative organisms presently implicated in the etiology of periodontal disease. All bacterial strains isolated were tested for resistance to tetracycline by replica-plating cultures on an agar medium containing two-fold dilutions of the antibiotic. Streptococcus, Veillonella and Neisseria were the bacterial genera found to be consistently resistant to tetracycline, with minimum inhibitory concentrations as high as 128 micrograms/ml. Among the Actinomyces, selection for antibiotic resistance was common only within a single species, A. odontolyticus. However, A viscosus strains isolated at 54% of the subgingival flora from one patient did demonstrate an intermediate resistance level, growing on concentrations up to 8 micrograms/ml. Tetracycline resistance was shown by a variety of Gram-negative rods isolated from the low dosage group. Although a minimum number of patients were studied, extensive microbial analyses of the predominating subgingival bacteria indicated that the goal of tetracycline therapy was achieved during the 2-week therapy period at 1000 mg/day.