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Conclusions: In conclusion, HA coating seemed to improve differentiation potential of osteoblasts but also signaling for clasts differentiation and bone remodeling. doi:10.1016/j.dental.2010.08.150 143 Effects of external bleaching agents on dental tissues and cement–enamel junction M.G.A.M. Chaves, M. Oliveira, M.N. Pereira, M.R.S.P. Soares, H.D.M. Chaves Filho, F.P.P. Leite Universidade Federal De Juiz De Fora, Brazil Objectives: Evaluate with a scanning electron microscope (SEM) the alterations occurring in enamel, cementum and cementum–enamel junction after the use of different external bleaching agents. Materials and methods: Fifteen healthy pre-molars were sectioned in the middle with the aid of a cutting machine (Labcut 1010), in the longitudinal direction along the axis of the teeth, obtaining mesial and distal surfaces of each tooth. The mesial surfaces were divided into three groups in accord with the material used (AI – carbamide peroxide 10% – Whiteness Standard 10 FGM ® , AII – carbamide peroxide 16% Whiteness Standard 16 FGM ® , e AIII – hydrogen peroxide 35% Whiteness HP Maxx FGM ® ), applied according to the instructions of the manufacturers. The distal surfaces of each tooth were maintained in artificial saliva, in a bacteriological sterilizer at 37 ◦ C. After whitening the specimens were dehydrated in increasing solutions of acetone and metalized for evaluation using a scanning electron microscope. The results were submitted to statistical evaluation using the Kruskal–Wallis and Mann–Whitey tests. Results: Statistically significant differences were observed between the whitened and unwhitened specimens (p < 0.001). In enamel, insignificant alterations were observed, and no differences between the groups were found. Loss of structure, with formation of gaps and dental exposure were observed in the cemento-enamel junction of the three whitened groups. Conclusions: Tooth whitening should be done with caution principally in patients who possess gingival recession. doi:10.1016/j.dental.2010.08.151 144 Solubility in water or DMEM of F-doped MTA cements with increasing F-content A. Colin, C. Prati, G.A. Pelliccioni, M.G. Gandolfi Laboratory of Biomaterials and Oral Pathology, Department of Odontostomatological Sciences, University of Bologna, Bologna, Italy Objectives: Fluoride increases the expansion and retards the setting time of F-doped calcium-silicate MTA cements. These cements may be successfully used as endodontic sealer. The assessment of the solubility of the endodontic cements dental materials 26S (2010) e1–e84 e67 allows to predict the loss of material from the surgical site, where they are in contact with physiological fluids (blood, tubular fluid). The aim of the study was to evaluate the solubility in deionized water (ISO 6876) or in simulated body fluid (DMEM) of designed F-doped calcium-silicate MTA cements with increasing amount of fluoride. Materials and methods: A calcium-silicate powder containing di- and tricalcium-silicate, calcium sulphate and barium sulphate was prepared. An increasing percentage of fluoride (F0%, F1%, F5% and F10%) was added to the powder to obtain 4 cements. The cements were mixed with DPBS (liquid/powder ratio 0.22), placed into a mould (10 mm diameter; 2.21 mm height) and stored at 37 ◦ C and 98% relative humidity for the 75% of their own setting time. Each sample (n = 5 for each cement) was weighed (initial weight, IW) and immersed in 10 mL of DMEM or deionized water keeping a vertical position. After 1 or 21 days the samples were dehydrated at 37 ◦ C and weighed (final weight, FW), then demoulded and the moulds weighed (mould weight, MW). The percentage of weight loss (solubility) was calculated as [(IW − FW)/(IW − MW)] × 100. Results: The solubility of all cements decrease over time (from 1 to 21 days) in both soaking solutions. High F concentration increases the solubility of calcium-silicate MTA cements. The solubility in DMEM is lower than in water for all the cements; this difference is more evident at 21 days. Conclusions: The innovative MTA cement containing 1% of fluoride represents an interesting material for the endodontic surgery. The presence simulated body fluid solutions lows the solubility rate of endodontic MTA cements suggesting a reduced solubility in in vivo conditions. doi:10.1016/j.dental.2010.08.152 145 In vivo, morphological and clinical effects of a desensitizing agent E. Milia 1 , E. Cotti 2 , G. Sotgiu 1 , G. Castelli 1 , M. Masarin 1 ,A. Manunta 1 , G. Gallina 3 1 University of Sassari, Italy 2 University of Cagliari, Italy 3 University of Palermo, Italy Objectives: This study evaluated the in vivo effectiveness of Universal Dentin Sealant (UDS), a new resin-based mate-
e68 dental materials 26S (2010) e1–e84 rial, as dentinal desensitizing agent on dentin morphology and clinical symptoms. Materials and methods: Thirty premolars, exhibiting noncarious cervical lesions, and scheduled for extraction for periodontal reasons, were selected for the ultrastructural study. These samples were randomly divided into three groups (n = 10): group 1, brushing with UDS; group 2, brushing with Flor-Opal ® Varnish (FOV); and group 3, untreated control. After 7 days, teeth were extracted and samples processed for SEM and TEM comparative observations. The in vivo study was carried out on 90 teeth with non-carious cervical lesions. The assessment method used to quantify sensitivity was the cold air syringe, recorded using the visual analogue scale (VAS), prior to treatment (baseline) and after 7 days. Teeth were randomly assigned to three groups (n = 30): group 1, UDS; group 2, FOV; and group 3, untreated control. Analysis was based on the Student’s t-test for paired data, with a 5% significance level. Results: The ultrastructure of UDS/dentin interface was characterized by a superficial porous layer of spherical clusters immersed in a loose matrix that fully covered the superficial dentin. A poorly crystalline aspect of peritubular and intertubular fibrils with sealed tubular orifices was observed. The FOV/dentin interface showed an irregular layer of precipitates with partial exposure of the dentin surface. The presence of intratubular crystals partially occluding the tubular orifices and densely mineralized peritubular fibrils was also noted. Untreated control dentin showed a superficial thin layer of smear with porous plugs within the tubular orifices. Comparing clinical results, the statistical analysis revealed significant differences between both the tested materials (p < 0.001) and the control group (p > 0.05) in term of the periods of examination. Conclusions: The application of UDS resulted in effective and stable dentinal tubular occlusion, leading to a statistically significant decrease in clinical discomfort of particular relevance to cases of dentinal hypersensitivity. doi:10.1016/j.dental.2010.08.153 146 Increases of intracanal and root surface temperatures during the obturation of canal using the E&Q master system and the system E. Cumbo 1 , R. Russo 1 , E. Milia 2 , G. Gallina 1 1 University of Palermo, Italy 2 University of Sassari, Italy Objectives: The purpose of our study is to assess the increases of intracanal and root surface temperatures during the obturation of canal system using the E&Q Master System and the System B. Materials and methods: A split-tooth model was built. To measure the temperature, 6 grooves for the placement of thermocouples were made in the buccal half of the model. On the mesial side, three grooves were made at 2, 4 and 6 mm from the anatomical apex and were extended to the root surface, while on the distal side three grooves were made at 2, 4 and 6 mm up to the intracanal portion. In each of these grooves was inserted a type T thermocouple (Copper-Costantana) with a diameter of 0.076 mm. 40 canal obturations were done: 20 using the E&Q Master System and 20 using the System B, set at 250 ◦ C, both with plugger FM increased to 3.5 mm from WL. The temperatures were recorded at 1 s intervals for a period of 200 s. Results: During the continuous wave obturation technique two peaks in temperature occurred, the first caused by the plugger in the canal, the second during the separation phase. In the E&Q Master System the highest increases were recorded in the thermocouple N.6, which reported average increases of 6.30 ◦ C, while the lowest were recorded in the thermocouple N.1, which reported a value of 2.11 ◦ C. In the System B group the highest increases were recorded in the thermocouple N.6, which reported average increases of 2.80 ◦ C, while the lowest were recorded in the thermocouple N.1, which reported a value of 0.4 ◦ C. Conclusions: Analysis of the obtained results showed that both systems allow us to get a good thermal mass increase of gutta-percha. Results show that the use of E&Q Master System and System B, in vitro, appears to cause a dangerous increase in temperature along the surface of the root that may create iatrogenic injury. doi:10.1016/j.dental.2010.08.154 147 Assessment of gutta-percha adaptation with different root canal obturation techniques P. Cusimano 1 , E.M. Cumbo 2 , S. Provenzano 2 , C. Goracci 1 ,G. Gallina 2 , M. Ferrari 1 1 University of Siena, Italy 2 University of Palermo, Italy Objectives: To compare in vitro the gutta-percha adaptation obtained with three different root canal obturation systems, using an experimental model of a single-root tooth. Materials and methods: A ‘split-tooth’ model was prepared. Lateral grooves and dentin depressions were created at 2, 4, 6 and 8 mm from the established apex length. Sixty models were randomly divided into 3 groups (n = 20), based on the obturation technique to be performed: System B, non-standardized 06-30 gutta-percha cones (VDW, Munchen, Germany) and System B (SybronEndo, Orange, Usa); GuttaFlow, calibrated master cone (taper 06-30) and gutta-based fluid cement carried by an applicator (Coltene, Whaledent Switzer-
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