Longevity of bond strength of resin cements to root dentine after radiation therapy.

AIM: To evaluate the bond strength and adhesive interface between several resin cements and root dentine immediately and 6 months after radiotherapy. METHODOLOGY: Sixty maxillary canines were selected and randomly assigned to two groups (n = 30): one group was not irradiated and the other one was subjected to a cumulative radiation dose of 60 Gy. The teeth were sectioned to obtain roots 16 mm long and the canals were prepared with the Reciproc system (R50) and filled using a lateral condensation technique with an epoxy resin sealer. Each group was divided into three subgroups (n = 10) according to the resin cement used for fibreglass fibre post cementation: RelyX-U200, Panavia-F2.0 and RelyX ARC. The posts were cemented in accordance with the manufacturer's recommendations. Three 1-mm-thick dentine slices were then obtained from each root third. The first two slices in the crown-apex direction of each third were selected for the push-out test. The failure mode after debonding was determined with a stereo microscope. The third slice from each root third was selected for scanning electron microscopy (SEM) analyses to examine the resin cement-dentine interface with 100, 1000, 2000 and 4000× magnification. Bond strength data were analysed by anova and Tukey's test (α = 0.05). RESULTS: Significantly lower bond strength (P < 0.0001) was obtained after irradiation compared to nonirradiated teeth. RelyX-U200 cemented fibre posts had the higher bond strength (15.17 ± 5.89) compared with RelyX ARC (P < 0.001) and Panavia-F2.0 (P < 0.001). The evaluation after 6 months revealed lower bond strength values compared to the immediate values (P < 0.001) for irradiated and nonirradiated teeth. Cohesive failures occurred in the irradiated dentine. SEM revealed fractures, microfractures and fewer collagen fibres in irradiated root dentine. RelyX-U200 and Panavia-F2.0 were associated with a juxtaposed interface of the cement with the radicular dentine in irradiated and nonirradiated teeth, and for RelyX ARC, hybrid layer formation and tags were observed in both irradiated and nonirradiated teeth. CONCLUSION: Radiation was associated with a decrease in the push-out bond strength and with lower resin cement/root dentine interface adaptation. Self-adhesive resin cement was a better alternative for fibre post cementation in teeth subjected to radiation therapy. The bond strength decreased after 6 months.

Effect of ultrasonic and sonic activation of root canal sealers on the push-out bond strength and interfacial adaptation to root canal dentine.

AIM: To evaluate the effect of ultrasonic and sonic activation of two root canal sealers on interfacial adaptation and push-out bond strength (BS) to root canal dentine. METHODOLOGY: The root canals of seventy-eight roots of maxillary canines were prepared with NiTi rotary instruments under irrigation with 2.5% NaOCl and 17% EDTA. Canals were filled by lateral condensation of gutta-percha and AH Plus (n = 39) or MTA Fillapex (n = 39). Three subgroups (n = 13) were formed according to sealer activation: no activation (NA), sonic activation (SA, 20 s) and ultrasonic activation (US, 20 s). In three specimens of each subgroup, 0.1% rhodamine B was added to the sealer. Three 1-mm-thick slices were obtained from each root third. The first and second were used for push-out BS test and the third for a qualitative analysis of interfacial adaptation (gaps) and voids by confocal laser scanning microscopy (CLSM). Intratubular penetration of rhodamine B-labelled sealer was also assessed by CLSM. Data were analysed by two-way anova and Tukey's test (α = 0.05). RESULTS: AH Plus (2.58 ± 1.21) had higher push-out BS than MTA Fillapex (1.45 ± 0.71) (P = 0.000). UA (2.64 ± 1.44) had higher BS (P = 0.000) than NA (1.58 ± 0.73) and SA (1.83 ± 0.85), which did not differ significantly from each other (P = 0.3303). The coronal third had higher BS (2.48 ± 1.49) than the middle (2.08 ± 0.94) (P = 0.0003) and apical (1.48 ± 0.58) (P = 0.00) thirds. For both sealers, UA was associated with a more homogeneous filling material with better interfacial adaptation and greater quantity, density and length of tags in dentinal tubules. When UA was used, the tags had similar quantity, density and length to those formed without activation, but interfacial gaps and voids were observed. CONCLUSION: Ultrasonic activation was associated with higher BS values, deeper intratubular penetration and greater interfacial adaptation to root dentine than sonic activation and no activation techniques, AH Plus had higher BS values than MTA Fillapex irrespective of the type of activation.

Evaluation of bond strength in single-cone fillings of canals with different cross-sections.

AIM: To evaluate the effect of root canal cross-sectional shape on single-cone root filling bond strength, as well as to determine the percentage of gutta-percha-filled areas (PGFA) and sealer-filled areas (PSFA), establishing a relationship between these variables. METHODOLOGY: Distal roots of mandibular molars were selected using microcomputed tomography imaging and allocated into three groups (n = 10) according to canal shape: round, oval and long oval. The canals were prepared with an R40 reciprocating instrument and filled with matching single-cone gutta-percha and AH Plus sealer. Two 1-mm-thick dentine slices were obtained from each third of each root. PGFA and PSFA were calculated in digital images (x25 magnification) of each slice. Next, the slices were subjected to a push-out test and the failure modes (adhesive, cohesive or mixed) were assessed. Data were analysed using parametric tests (P < 0.05). RESULTS: In the coronal (2.17 ± 0.56MPa) and middle thirds (1.78 ± 0.45MPa), the round canals were associated with higher bond strength values (P < 0.01), with no difference between the groups for the apical third (P > 0.05). Adhesive and mixed failures predominated in round canals, whilst cohesive failures were more frequent in oval and long oval canals. Round canals had significantly higher PGFA and lower PSFA than all other groups (P = 0.000). The PGFA and PSFA had a positive (r = 0.521, P = 0.000) and a negative (r = -0.523, P = 0.000) correlation with bond strength, respectively. CONCLUSION: Bond strength values of gutta-percha and sealer were affected by canal shape. Higher percentage of gutta-percha-filled area resulted in higher bond strength to dentine.

Fracture resistance and stress distribution of simulated immature teeth after apexification with mineral trioxide aggregate.

AIM: To evaluate the effect of adhesive restorations on fracture resistance and stress distribution in teeth with simulated immature apices and apical plugs of mineral trioxide aggregate (MTA). METHODOLOGY: Sixty bovine incisors were sectioned 8 mm above and 12 mm below the cemento-enamel junction (CEJ). The root canal was enlarged using a diamond bur, resulting in remaining root canal walls with 0.1-0.2 mm of thickness. A 5-mm apical plug of MTA was placed and the teeth were restored according to the following groups: GP--the root canal was filled with gutta-percha and endodontic sealer; CR--the root canal was filled with light-cured composite resin inserted incrementally; FP--a fibre post was cemented into the root canal; and RFP--the fibre post was relined with composite resin prior to the cementation into the root canal. A load was applied on the crown of all teeth at 135° to their long axis until fracture. Data was analysed by one-way anova and SNK tests (α = 0.05), whilst the fracture pattern was evaluated according to the position of the fracture. Stress distributions in the restored teeth were verified by finite element analysis. RESULTS: Teeth restored with fibre posts and relined fibre posts were associated with the highest fracture resistance, whilst the GP group had the lowest values. GP and RC groups had similar fracture resistance values (P = 0.109). All fractures types involved the cervical and middle thirds of roots. The GP model had high levels of stress concentration in the cervical and middle thirds of roots. No difference was found amongst the stress concentration in the RC, FP and RFP models. CONCLUSION: Restorative protocols alter the fracture resistance and stress distribution of immature teeth after placement of MTA apical plugs.

Ex vivo evaluation of artifacts mimicking fracture lines on cone-beam computed tomography produced by different root canal sealers.

AIM: To evaluate streaking artifacts produced by several root canal sealers on CBCT images with variations in voxel resolution. METHODOLOGY: Single-rooted premolars were selected and root filled using gutta-percha cones and one of the following sealers: Endofill, Sealer 26, Fillapex or AH Plus. Root canals filled only with gutta-percha were used as control. Scans of teeth using a small-volume CBCT were performed, and the images acquired were evaluated by two calibrated observers (k > 0.75). Artifacts were identified as streaks and dark bands on root dentine in axial slices with 2 voxel sizes (0.076 and 0.2 mm). Fisher's exact test (P < 0.05) was used to compare the presence/absence ratio of artifacts considering the factors 'sealer' and 'voxel size'. RESULTS: For the 0.20 mm voxel size, Sealer 26 had significantly more artifacts than Fillapex (P = 0.006) or AH Plus (P = 0.017). No differences existed between the sealers when the 0.07 mm voxel size was used. Sealer 26 (P = 0.042) and Endofill (P = 0.035) had significantly more artifacts in the 0.20 mm voxel size than with the 0.076 mm voxel size, whilst no difference was noted for other filling conditions. CONCLUSIONS: The material used for root filling and the voxel resolution can influence the presence of streaking artifacts observed in CBCT images.

The effect of filling technique on the cuspal strain, polymerization shrinkage stress, enamel crack formation and depth of cure of restored molars.

OBJECTIVE: Evaluate the effect of different restorative filling techniques on the residual shrinkage stress (ShrS), cuspal strain (CS), depth of cure (DC), and enamel crack formation (Ec) in molars with MOD restorations. METHODS: Post-gel shrinkage, elastic modulus, compressive and diametral tensile strength of the Filtek One Bulk Fill composite were calculated. Sixty molars with MOD preparations were restored using four filling techniques: Bulk; Horizontal; Oblique; Natural enamel and dentin substitution (NEDS) technique. CS was measured using a strain gauge (n = 10). The DC (n = 5) was measured using Knoop hardness. Shrinkage stress/strain was analyzed using 3D finite element analysis. The Ec analysis was carried out by transillumination. Two-way ANOVA with repeated measures and Tukey's HSD test (α = 0.05) was performed for the CS data. Two-Way ANOVA and Tukey's HSD test was performed for the DC data (α = 0.05). RESULTS: CS was higher at the lingual cusp for the horizontal and NEDS technique. No statistical difference was found between the buccal and lingual CS values for the Bulk (p = 0.367) or Oblique techniques (p = 0.192). CS values were lower for the Bulk. More enamel cracks were found for the Bulk. DC was lower at 4 mm regardless the filling technique. The Horizontal showed the highest ShrS values. The Bulk generated the lower ShrS values. SIGNIFICANCE: A Bulk technique caused the lowest shrinkage stress/strain. An Oblique technique yielded the best balance between stress, strain and crack formation. NEDS technique is a good alternative to decrease the number of increments while maintaining the stress levels nearby the Oblique technique.

Lumbar Myelopathy Caused by Multiple Cartilaginous Exostoses in a Dog.

A 6-months-old male mixed-breed dog was admitted to the veterinary hospital with lameness in the right pelvic limb, proprioceptive ataxia, and suspected spinal cord injury in the lumbosacral segment. Upon palpation, firm nodules were noted on the bony surface of the thoracic and pelvic limbs, ribs, vertebrae, and tail. The radiographic study showed nodules of low radiopacity with well-defined limits and smooth contours, one of which was overlapping the fifth lumbar vertebra. Given the clinical presentation indicative of spinal cord injury, the animal was subjected to hemilaminectomy for nodular resection. Histopathological examination of the biopsy enabled the diagnosis of osteochondroma. The clinical follow up after surgery showed improvement in walking, despite persistent monoparesis in the right pelvic limb. The radiographic study in association with clinical and histopathological exams allowed the diagnosis and monitoring of the lesions.

Post-polio syndrome: epidemiologic and prognostic aspects in Brazil.

OBJECTIVES: To describe the clinical and epidemiological aspects of post-polio syndrome (PPS) and identify predictors of its severity. MATERIALS AND METHODS: 132 patients with PPS were selected at the Neuromuscular Disease Outpatient Clinic of the Federal University of São Paulo. Descriptive analysis was carried out and predictors of PPS severe forms were investigated using an unconditional logistic regression. RESULTS: The average age at onset was 39.4 years. The most common symptoms were fatigue (87.1%), muscle pain (82.4%) and joint pain (72.0%); 50.4% of the cases were severe. The following were associated with PPS severity: a < or =4-year period of neurological recovery (OR 2.8), permanent damage in two limbs (OR 3.6) and residence at the time of acute polio in a city with more advanced medical assistance (OR 2.5). CONCLUSIONS: Health professionals should carefully evaluate polio survivors for PPS and be aware of the implications of muscle overuse in the neurological recovery period.

Basal metabolic rate and body composition in patients with post-polio syndrome.

The aim of this study was to compare basal metabolic rate (BMR) of post-polio syndrome (PPS) patients with healthy individuals and to determine its correlation to body composition. BMR (kcal/day) was determined by indirect calorimetry and body composition by dual energy X-ray absorptiometry. BMR was lower in the PPS patient group than in the control group, although it was similar in both groups when adjusted for body surface area, total body mass (TBM), lean body mass (LBM) and fat-free mass (FFM). PPS patients also showed reduced TBM, LBM and FFM in relation to controls. As muscle energy expenditure while at rest contributes only 20% to the BMR, a proportional reduction in BMR and FFM or LBM could suggest that muscle mass or other factors may interfere more than predicted. It was concluded that the prediction of BMR from the Harris-Benedict equation in PPS patients must be carefully reviewed.

Behavior of mesenchymal stem cells stained with 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) in osteogenic and non osteogenic cultures.

4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) is a DNA dye widely used to mark and trace stem cells in therapy. We here studied the effect of DAPI staining on the behavior of mesenchymal stem cells cultured in either a control, non-osteogenic medium or in an osteogenic differentiation medium. In the control medium, the number of stem cells/field, as well as the number of fluorescent cells/field increased up to the sixth day in both control and DAPI-treated cultures. Afterwards, both the number of fluorescent cells and their fluorescence intensity decreased. Control cells were fusiform and with some long extensions that apparently linked them to neighboring cells, while DAPI-treated cells were mostly round cells with fine and short extensions. The trypan-blue exclusion method showed 99% cell viability in both groups, however, both alkaline phosphatase activity and the thiazolyl blue formazan assay (indicative of mitochondrial metabolism) gave significantly lower values in DAPI-marked cells. The mitochondrial mass, as indicated by specific staining and flow cytometry, showed no differences between groups. Mesenchymal stem cells gave origin to mineralized nodules in the osteogenic differentiation medium and there were not DAPI-marked cells on the ninth day of culture. Alkaline phosphatase activity, viability assay and number of cells/field and of mineralized nodules/field were similar in both groups. So, DAPI treatment did not change cell viability and proliferation during osteogenic differentiation of mesenchymal stem cells. However, since these cells loose DAPI marking after 9 days in osteogenic cultures suggests that DAPI may not be an effective marker for mesenchymal stem cells implanted in bone tissue for long periods.

Effect of Photoactivation Timing on the Mechanical Properties of Resin Cements and Bond Strength of Fiberglass Post to Root Dentin.

OBJECTIVES: This study tested the hypothesis that photoactivation timing and resin cement affect mechanical properties and bond strength of fiberglass posts to root dentin at different depths. METHODS: Fiberglass posts (Exacto, Angelus) were luted with RelyX Unicem (3M ESPE), Panavia F 2.0 (Kuraray), or RelyX ARC (3M ESPE) using three photoactivation timings: light curing immediately, after three minutes, or after five minutes. Push-out bonding strength, PBS (n=10) was measured on each root region (coronal, middle, apical). The elastic modulus (E) and Vickers hardness (VHN) of the cement layer along the root canal were determined using dynamic indentation (n=5). A strain-gauge test was used to measure post-gel shrinkage of each cement (n=10). Residual shrinkage stress was assessed with finite element analysis. Data were analyzed with two-way analysis of variance in a split-plot arrangement and a Tukey test (α=0.05). Multiple linear regression analysis was used to determine the influence of study factors. RESULTS: The five-minute delay photoactivation timing significantly increased the PBS for all resin cements evaluated. The PBS decreased significantly from coronal to apical root canal regions. The mean values for E and VHN increased significantly with the delayed photoactivation for RelyX Unicem and decreased from coronal to apical root regions for all resin cements with the immediate-curing timing. CONCLUSIONS: The PBS of fiber posts to root dentin, E, and VHN values were affected by the root canal region, photoactivation timing, and resin cement type. Shrinkage stress values decreased gradually with delayed photoactivation for all the cements.

First isolation of dengue 1 virus from Aedes aegypti in Federal District, Brazil.

Dengue is present in the Federal District since 1991 and virological studies of the vector began in 1998. Two strains of DEN1 were isolated from 9 pools of female Aedes aegypti (78 mosq.), collected in April in Gama county, where the Breteau index was 5.4, and 32 autochtonous human cases were notified.

Incremental filling technique and composite material--part I: cuspal deformation, bond strength, and physical properties.

OBJECTIVES: To evaluate the effect of composite resins (one conventional and two low-shrink composites) and filling techniques on cuspal strains (CS), microtensile bond strength (µTBS), composite ultimate tensile strength (UTS), and mechanical properties of the composites at various depths in molars with large Class II restorations. MATERIALS AND METHODS: One hundred seventeen human molars received standardized Class II mesio-oclusal-distal cavity preparations and restorations with three composites (Filtek LS [3M-ESPE]; Aelite LS [BISCO]; and Filtek Supreme [3M-ESPE]) using three filling techniques (bulk, eight increments, and 16 increments). CS was measured using strain gauges, after which the same restored teeth were used to assess µTBS and UTS. The elastic modulus (E) and Vickers hardness (VH) at different depths were determined from microhardness indentations. The CS, µTBS, UTS, E, and VH data were statistically analyzed using split-plot analysis of variance and Tukey test (p=0.05). RESULTS: The CS was higher when using 16 increments. The 'low-shrink' composites caused lower CS. The µTBS and UTS were similar for eight- and 16-increment techniques and higher when compared to the bulk filling in all composites. E and VH were constant through the depth when applied in eight or 16 increments. CONCLUSIONS: Type of composite and filling technique affected the CS, µTBS, UTS, and mechanical properties of large Class II restorations. The eight-increments filling technique resulted in generally less CS with the same µTBS and UTS than was obtained with 16 increments, without affecting E and VH through the depth of the composites.

Desvio para a esquerda associado a compartimento medular de reserva dos neutrófilos não esgotado em cadelas portadoras de piometra / Nuclear left deviation associated with medullary reserve compartment of non exhausted neutrophils in female dogs with pyometra

From fifteen female dogs with clinical diagnoses of pyometra, hematological exams were performed at three times: M0 (prior to the surgery), M24 (24h after ovarysalpingohisterectomy-OSH) and M48 (48h after OSH). Anemia was seen in 80% of the cases, characterized as mild normocytic normochromic type. The means of total leukocyte counts were 27.043, 57.940 and 40.139 céls/µL in M0, M24 and M48. A total of80% of the animals presented neutrophilic left shift in all moments. During medullar exams, the cellular, iron reserve and megakaryocytic concentration were raised as well as the ME ratio, showing a value of 26,3:1,0, probably due to the elevation of granular proliferation and maturation compartment, as the mean of the reserve compartment was within normal range. As 83% of the animals with neutrophilic left shift showed a melullary reserve compartment raised, it can be concluded that female dogs with piometra had left shift of neutrophils with disproportionally between compartments, without segmented medullar saturation.(AU)

Effects of Solanum malacoxylon extract on rachitic chicks. Comparative study with vitamin D3.

A comparative study of the effects of vitamin D3 and of a partially purified extract of Solanum malacoxylon has been carried out in rachitic chicks. Vitamin D3 and Solanum malacoxylon increased intestinal calcium absorption and serum calcium levels. They normalized the bone water and ash content. Vitamin D3 produced an increase of serum phosphate while Solanum malacoxylon further decreased the already low phosphate values. Vitamin D3 significantly increased the body weight increment of rachitic chicks, but Solanum malacoxylon did not. It appears that Solanum malacoxylon duplicates certain actions of vitamin D but lacks its phosphate-regulating and growth-promoting actions.

Behavior of mesenchymal stem cells stained with 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) in osteogenic and non osteogenic cultures

4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) is a DNA dye widely used to mark and trace stem cells in therapy. We here studied the effect of DAPI staining on the behavior of mesenchymal stem cells cultured in either a control, non-osteogenic medium or in an osteogenic differentiation medium. In the control medium, the number of stem cells/field, as well as the number of fluorescent cells/field increased up to the sixth day in both control and DAPI-treated cultures. Afterwards, both the number of fluorescent cells and their fluorescence intensity decreased. Control cells were fusiform and with some long extensions that apparently linked them to neighboring cells, while DAPI-treated cells were mostly round cells with fine and short extensions. The trypan-blue exclusion method showed 99% cell viability in both groups, however, both alkaline phosphatase activity and the thiazolyl blue formazan assay (indicative of mitochondrial metabolism) gave significantly lower values in DAPI-marked cells The mitochondrial mass, as indicated by specific staining and flow cytometry, showed no differences between groups. Mesenchymal stem cells gave origin to mineralized nodules in the osteogenic differentiation medium and there were not DAPI-marked cells on the ninth day of culture. Alkaline phosphatase activity, viability assay and number of cells/field and of mineralized nodules/field were similar in both groups. So, DAPI treatment did not change cell viability and proliferation during osteogenic differentiation of mesenchymal stem cells. However, since these cells loose DAPI marking after 9 days in osteogenic cultures suggests that DAPI may not be an effective marker for mesenchymal stem cells implanted in bone tissue for long periods.