The accuracy of CBCT for the detection and diagnosis of vertical root fractures in vivo.

AIM: To compare the in vivo accuracy of CBCT for the detection of fracture lines versus the diagnosis of vertical root fractures (VRFs) according to characteristic patterns of associated bone resorption. METHODOLOGY: Eighty-eight patients with symptoms typical of VRFs in root filled teeth, who underwent a CBCT examination and later had the teeth extracted, were divided into two groups: the fracture group (n = 65) and the control group (n = 23). Five blinded observers assessed the CBCT images in two sessions. During the first session, they were asked to state the diagnosis according to the CBCT and clinical data. During the second session after 2 weeks, they assessed only axial slices and were asked to detect a fracture line. The mean CBCT specificity, sensitivity, accuracy values and area under the receiver operating characteristic (AUROC) curve were calculated and compared using the Wilcoxon signed-rank test. RESULTS: The average sensitivity of CBCT for the diagnosis of VRFs was 0.84 ± 0.2. The accuracy and AUC values were 0.81 ± 0.08 and 0.84 ± 0.17, respectively. The sensitivity, accuracy and AUC values for the detection of VRFs were significantly lower: 0.17 ± 0.24 (P = 0.042), 0.54 ± 0.07 (P = 0.043), and 0.52 ± 0.09 (P = 0.043), respectively. The specificity of CBCT for the detection and diagnosis of VRFs did not differ significantly (P = 0.50). CONCLUSION: Cone-beam computed tomography was helpful in VRF diagnosis even when it was not possible to visualize the fracture line.

[Detection of vertical root fractures by cone beam CT]. / Diagnostika vertikal'nykh treshchin kornei zubov s pomoshch'yu konusno-luchevoi komp'yuternoi tomografii.

The aim of the study was to assess the feasibility and precision of vertical root fracture diagnostics by cone beam CT (CBCT). Vertical root fractures were simulated in 25 sound teeth extracted because of orthodontic and periodontal reasons and examined by CBCT. The roots were then sectioned in corresponding planes and fractures were assessed microscopically. CBCT sensitivity and precision was significantly higher for visualization of vertical fractures >150 µm when compares to fractures <50 µm with no difference in specificity. CBCT is an effective tool for vertical root fractures detection.

Detection of artificially induced vertical root fractures of different widths by cone beam computed tomography in vitro and in vivo.

AIMS: To compare the diagnostic accuracy of cone beam computed tomography (CBCT) for the detection of artificially induced vertical root fractures (VRFs) of different widths in vitro and in vivo. METHODOLOGY: Vertical root fractures were induced in 25 extracted nonendodontically treated single-rooted human teeth (maxillary first premolars, maxillary canines and mandibular incisors). Twenty teeth without VRFs served as a control group. CBCT scanning (3D Accuitomo 170) was performed in vitro and in vivo. For the in vivo scanning, teeth were autoclaved, embedded into bite plates, placed in sterile plastic bags and then inserted into the mouths of volunteers. Teeth with VRFs were sectioned into axial slices and examined using a stereomicroscope to measure the widths of the VRFs. Five observers assessed the presence of VRFs using axial CBCT. Values for sensitivity, specificity, accuracy and interexaminer agreement were calculated. RESULTS: The accuracy, specificity and sensitivity of CBCT were significantly higher in vitro than in vivo for VRFs with widths 50-150 µm (P < 0.05). The sensitivity and accuracy of CBCT were significantly higher for the detection of VRFs with widths greater than 150 µm in vivo and in vitro (P < 0.05). The accuracy of CBCT in vivo was 0.29 and 0.8 for fracture widths ranging from 50 to 150 µm and wider than 150 µm, respectively. No significant differences in CBCT specificity were found between VRF widths both in vitro and in vivo. The interexaminer reliability of the raters revealed a kappa value of 0.72, demonstrating substantial agreement. CONCLUSION: The detectability of VRFs by CBCT in vitro and in vivo was dependent upon fracture width. The accuracy of CBCT in detecting VRFs of 50-300 µm width in vivo was significantly lower compared to the in vitro accuracy.

[A comparative study of fluoroquinolones and 3rd-generation cephalosporins in the prevention and treatment of experimental plague caused by Yersinia pestis strains typical and serologically atypical with respect to F1]. / Sravnitel'noe izuchenie ftorkhinolonov i tsefalosporinov III pokoleniia v profilaktike i lechenii éksperimental'noi chumy, obuslovlennoi tipichnym i serologicheski atipichnym po F1 shtammami chumnogo mikroba.

Fluoroquinolones (ciprofloxacin and pefloxacin) and 3rd generation cephalosporins (cefoperazone, cefotaxime, ceftazidime and ceftriaxone) were comparatively studied in the prevention and treatment of experimental plague in albino mice caused by F1+ and F1- strains of the plague microbe. Despite the phenotype of the strain which caused the infection, the drugs were highly efficient in the etiotropic therapy. However, in the experimental plague due to F1- strains it was needed to use the maximum mean daily doses of the fluoroquinolones, cefoperazone and cefotaxime. For the prevention of the infection such doses should be used for not less than 7 days. By the efficacy ceftriaxon was superior to the other cephalosporins and should be considered as a drug of choice.

[Effectiveness of new quinolones in experimental aerogenic plague infection of albino mice]. / Effektivnost' novykh khinolonov pri aérogennoi éksperimental'noi chume belykh myshei.

It was shown that unlike nalidixic acid the 3rd generation quinolones i.e. the nitrogen-containing quinolones (LIB-71 and LIB-80) and the fluorine-containing quinolones (pefloxacin and ciprofloxacin) were highly efficient in the prophylaxis and treatment of experimental plague in albino mice infected via the plague microbe inhalation. By the ED50 the efficacy of pefloxacin was 25-30 times higher than that of nalidixic acid and 60-90 times higher than that of ciprofloxacin. The fluorine-containing quinolones proved to be more active than the nitrogen-containing ones.

[Combined use of quinolones with other antibiotics in treatment of experimental plague infection]. / Kombinirovannoe ispol'zovanie khinolonov s drugimi antibiotikami v lechenii éksperimental'noi chumnoi infektsii.

The efficacy of combinations of fluoroquinolones (ciprofloxacin and pefloxacin) with betalactams (ampicillin, azlocillin and cefotaxime), aminoglycosides (amikacin) and rifampicin was studied on albino mice infected subcutaneously with plague. The drugs were used in deliberately ineffective or insufficiently effective doses. Synergism was observes with the use of ciprofloxacin and pefloxacin in combinations with amikacin, cefotaxime or rifampicin. The combinations of ciprofloxacin with ampicillin or azlocillin had no synergistic action though the therapeutic effect was not lower. With using the specifically determined doses the efficacy of the combinations could be increased by comparison with that of the drugs used alone.

[Virulence of rifampicin and quinolone resistant mutants of strains of plague microbe with Fra+ and Fra- phenotypes]. / Virulentnost' ustoichivykh k rifampitsinu i khinolonam mutantov iz shtammov chumnogo mikroba s Fra+ i Fra- fenotipom.

Experiments with 15 highly virulent antigenically typical strains (Fra+) and 3 fraction-free strains (Fra-) of the plague microbe were conducted. It was demonstrated that a single exposure of the plague microbe to rifampicin or nalidixic acid (100 micrograms/ml) resulted in the formation of mutants (Rifr or Nalr) resistant to the drugs. The mutation frequency was 10(-10)-10(-8). All the Nalr mutants showed cross resistance to ciprofloxacin, a 3rd generation quinolone. A comparative study of the virulence of the clones in the population of the initial strains of the plague microbe and the cultures of the Rifr and Nalr mutants revealed that the predominating majority of the variants resistant to rifampicin and the quinolone preserved their high virulence. The resistance level of the mutants was sufficient for inducing the infection development in the albino mice at the background of the therapy with rifampicin, nalidixic acid or ciprofloxacin: no statistically significant differences in the values of the LD50 of the culture for the treated and nontreated animals were recorded. The Rifr and Nalr variants of the fraction-free strains of the plague microbe preserved their ability to overcome the specific immunity in the albino mice. The experimental data indicated that the rifampicin or quinolone monotherapy required a caution and the combined etiotropic therapy was more advantageous since it decreased the risk of the complications due to the drug resistant virulent variants of the plague microbe forming during the treatment.

[Effectiveness of the new quinolones, ciprofloxacin and pefloxacin in experimental plague]. / Izuchenie éffektivenosti novykh khinolonov--tsiprofloksatsina i pefloksatsina pri éksperimental'noi chume.

Efficacy of ciprofloxacin and pefloxacin in plague infection was studies on albino mice by comparison with that of nalidixic acid. The mice were contaminated subcutaneously. The treatment with the drugs was started 6 or 24 hours after the contamination. The MICs of ciprofloxacin, pefloxacin and nalidixic acid were 0.01 to 0.02, 0.15 and 1.25 to 2.5 micrograms/ml respectively. By the ED50 ciprofloxacin proved to be the most efficient. Pefloxacin was 6 times less efficient and nalidixic acid was 100 times less efficient. The quinolones were shown to be highly efficient when administered at 48-hour intervals.

[Effectiveness of cefotaxime in experimental plague infection]. / Effektivnost' tsefotaksima pri eksperimental'noi chumnoi infektsii.

Cefotaxime was shown highly efficient in prophylaxis and treatment of experimental plague infection in albino mice. The in vitro activity of cefotaxime against natural strains of the plague microbe was 32 to 64 times higher than that of cefazolin, cephalothin and cefmetazole. The combined use of cefotaxime with amikacin significantly increased the percentage of the survived albino mice with plague infection as compared to the use of the antibiotics alone.

[Doxycycline in the prevention of experimental plague induced by plague microbe variants]. / Doksitsiklin v profilaktike éksperimental'noi chumy, obyslovlennoi variantami shtamma vozbuditelia.

A comparative study was performed on the efficacy of doxycycline in experimental plague infection induced in albino mice by strain 231 of the plague microbe and its variant 231 Fra- deprived of the ability to produce the fraction I antigen. It was shown that the LD50 for strain 231 during animal treatment with doxycycline was significantly higher than that for variant 231 Fra-. Prophylaxis of the plague infection caused by the Fra- forms of the plague microbe required significantly higher doses of doxycycline (ED50) than that of the infection caused by the Fra+ forms. The use of the daily maximum permissible doses of doxycycline (50 to 100 mg/kg a day) for 10 days in treatment of albino mice infected with the strain Fra- did not provide animal survival at the level higher than 60 to 70 per cent while the survival rate in the animals infected with the strain Fra+ of the plague microbe and treated according to the same scheme amounted to 90-100 per cent. The lower therapeutic efficacy of doxycycline in the treatment of the infection caused by the fractionless variant of the plague microbe should be considered in development of rational schemes for prophylaxis and treatment of plague.

[Effectiveness of phosphomycin and its combinations with amikacin and cefotaxime in experimental plague infection]. / Izuchenie éffektivnost' fosfomitsina i ego sochetanii s amikatsinom i tsefotaksimom pri éksperimental'noi chumnoi infektsii.

When administered intramuscularly in doses of 8 and 16 mg/mouse, phosphomycin was highly active in the treatment of albino mice with experimental plague infection (80-100-percent protection of the animals from death). Combinations of phosphomycin with cefotaxime in inefficient or not sufficiently efficient doses had a synergistic effect. When the albino mice were treated with combinations of phosphomycin and amikacin, the percentage of the survived animals significantly increased in comparison to that after the use of the antibiotics alone.

[Antibiotics of the aminoglycoside group (gentamicin, sisomicin and amikacin) in the prevention and treatment of experimental plague]. / Antibiotiki gruppy aminoglikozidov (gentamitsin, sizomitsin, amikatsin) v profilaktike i lechenii éksperimental'noi chumnoi infektsii.

Activity of aminoglycosides such as gentamicin, sisomicin and amikacin against plague microbe strains of natural origin was studied in vitro. It was also studied in prophylaxis and treatment of experimental plague infection in albino mice. The MAC of gentamicin and sisomicin for 50 strains of the plague microbe was 0.2-1.6 micrograms/ml. For the majority of the strains it was 0.4 micrograms/ml. The amikacin MICs were 0.4-3.2 and 0.8 micrograms/ml, respectively. High efficacy of gentamicin, sisomicin and amikacin was shown in prophylaxis and treatment of experimental plague infection in albino mice. The optimal doses of the antibiotics were determined. Under definite conditions such as the use of short-term regimens and higher intervals, advantages of sisomicin over gentamicin and amikacin in prophylaxis of experimental plague infection were observed.

[Chromosomal resistance of plague agent to quinolones]. / Khromosomnaia ustoichivost' chumnogo mikroba k khinolonam.

The nature of increasing chromosomal resistance to quinolones was studied in a model of the plague microbe. Five virulent strains of the natural plague microbe (Y. pestis) were used in the experiment: 363 (1/1479), 231, 2385, 2442 and 2444. The one-stage procedure for isolation of the mutants was applied. It was shown that the frequency of the one-stage mutants resistant to oxalinic acid, pefloxacin and ciprofloxacin amounted to 10(-9)-10(-11) and was 2 to 3 orders of magnitude lower than that of the mutants resistant to nalidixic acid. Two types of the plague microbe mutants resistant to the quinolones were detected: those resistant to the quinolones to the generations (Nalr-phenotype) and those resistant to the representatives of the 3rd generation quinolones (Nals-phenotype). The quinolones were not efficient in the treatment of albino mice with experimental plague caused by the quinolone-resistant forms of the plague microbe.