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tion of colonies of S. mutans and S. total can be able to determine a significant reduction in the cariogenic risk in orthodontic patients, especially early in therapy or in case of loss of compliance. doi:10.1016/j.dental.2010.08.167 160 Microhardness of MTA and SuperEBA in acid solutions S. Loghi, D. Nicosia, M. De Biasi, D. Sossi, D. Angerame University of Trieste, Trieste, Italy Objectives: Periapical inflammation and pH changes after endodontic surgery could affect hardening and final characteristics of retrograde filling materials. The present study analyzes the microhardness of two retrograde filling materials stored into different pH solutions. Materials and methods: 48 discs (24 per material) were prepared according to manufacturer instructions and randomly divided in 8 groups (n = 6); they were let harden for 1 (SuperEBA, Bosworth) or 24 h (MTA, Dentsply) into buffered solutions at different pH values (pH = 7, pH = 6, pH = 5 and pH = 3). After storage the upper surface of the specimens was polished using a 1200 (10 �m) and 2400 (5 �m) sandpaper. Microhardness was then measured with a Vickers indenter (VHMT 30, Leica). Collected data were statistically analyzed with Kruskal–Wallis and Conover tests (p < 0.05). Results: Mean hardness values (±SD) were: pH MTA SuperEBA 7 38.59 ± 2.59 18.46 ± 5.38 b 6 3.61 ± 0.76 a 22.81 ± 5.16 c 5 4.02 ± 1.57 a 20.65 ± 5.49 bcd 3 1.21 ± 0.47 21.69 ± 6.10 d Data expressed in HV. Same letters indicate no statistical difference. Conclusions: Within the limits of the present study MTA showed high sensibility to decreasing pH of the environment, although at pH 7 it showed the greatest microhardness values. SuperEBA maintained constant or increased its hardness with increasing acidity. The pH of the surgical site seems to be relevant for retrograde filling materials, thus postsurgical inflammation should be kept under control. doi:10.1016/j.dental.2010.08.168 161 Mesenchymal stem cells and bovine bone mineral in sinus lift R. Gutwald 1 , M. Maglione 2 , S. Sauerbier 1 , R. Schmelzeisen 1 1 University of Freiburg, Germany 2 University of Trieste, Italy Objectives: New reconstructive and less invasive methods have been searched in order to optimize bone formation and osseointegration of dental implants in maxillary sinus augmentation. The aim of the presented ovine split-mouth study was to compare bovine bone mineral (BBM) alone or in com- dental materials 26S (2010) e1–e84 e75 bination with mesenchymal stem cells (MSCs) regarding their potential in sinus augmentation. Materials and methods: Bilateral sinus floor augmentations were performed in 6 adult sheep. BBM and MSCs were placed into the test side and only BBM in the contra-lateral control side of each sheep. Bone marrow was aspirated from the iliac crest. MSCs were extracted via Ficoll-separation. A volume of 3.5 cm 2 of MSCs and BBM were transplanted into the right sinus (test). The left sinus (control) was augmented only with BBM. The wounds were closed with resorbable suture material. All the surgical procedures were carried out by the same surgeon. The surgical procedures for sinus augmentation and the follow up were done according to Haas protocol. Animals were sacrificed after 8 and 16 weeks. Augmentation sites were analysed by computed tomography, histology, and histomorphometry. Results: The initial volumes of both sides were similar and did not change significantly with time. A tight connection between the particles of BBM and the new bone was observed histologically. Bone formation was significantly faster by 49% in the test sides (p = 0.027). The histological sections showed no signs of inflammation. The newly formed osseous lamellae appared as a vital bone tissue containing osteocytes inside the bone lacunae. In comparison to lamellar bone the biomaterial could be easily identified by its size, shape and color. The newly formed bone lamellae connected the biomaterial particles and stabilized the grafted complex. Bone formation appeared in the macro pores of the biomaterial as well. Blood vessels could be detected in the biopsy. The biomaterial with newly formed bone was integrated well in the surrounding host bone. Conclusions: The combination of BBM and MSCs accelerated new bone formation in this model of maxillary sinus augmentation. This could allow early placement of implants. doi:10.1016/j.dental.2010.08.169 162 Wetting behaviour of root canal sealers A. Mokeem Saleh, N. Silikas, D.C. Watts University of Manchester, UK Objectives: Wetting behaviour is an important phenomenon in dentistry in order to achieve good adhesion between the filling materials and the tooth surface (Combe et al. Dent Mater. 2004 20:262). In endodontics, root canal sealers with good flowability and low surface tension can be easily placed along the entire root canal and be capable of wetting the canal walls (Stevens et al. J Endod. 2006 32:785). The intimacy of this contact depends on the wettability of sealers on solid dentine and this property of the liquid is strictly correlated to its surface tension (Giardino et al. J Endod. 2006 32:1091). The purpose of this study was to investigate surface tension of different endodontic sealers using the pendant drop method. Materials and methods: Endodontic sealers 1–7 of different chemical composition were used to measure the surface tension, all measurements were recorded at 23 ◦ C. Water was used as a control. Once the profile of the pendant drop was obtained, a numerical method was used for obtaining
e76 dental materials 26S (2010) e1–e84 the parameters to compute surface tension by using image analysis software (Sigma Scan Pro V). ANOVA was used to investigate differences of the surface tension properties of various root canal sealers at the significance level of 0.05, using SPSS software. Results: All sealers exhibited varied degrees of surface tension regardless of the type of the sealers. Dentalis ® exhibited the highest (59.28 mN/m) while EndoREZ ® showed the lowest (27.93 mN/m). Statistically significant differences were found between the sealers (P < 0.05). Material Manufacturer Surface tension (m N/m) ± (SD) Water Control 72.90 ± (1.52) 1Dentalis ® NEO DENTAL International Inc. 59.28 ± (4.77) 2RealSealTM SybronEndo 48.87 ± (3.64) 3AH Plus ® Dentsply, De Trey 47.65 ± (4.58) 4Apexit ® Plus Ivoclar, Vivadent 41.70 ± (4.90) 5AH-26 Dentsply, De Trey 38.22 ± (3.67) 6Tubli-Seal EWT Kerr 29.70 ± (2.68) 7EndoREZ ® Ultradent 27.93 ± (5.36) Conclusions: Due to its composition and structural arrangement, dentin can only be wetted by a liquid with a surface tension equal to or lower than 42.23 mN/m (Erickson, Oper Dent. 1992 5:81). Results showed that some of the root canal sealers analysed such as AH-26, Tubli-Seal EWT, Apexit ® Plus, and EndoREZ ® had mean surface tension values lower than 42.23 mN/m, so they satisfied their function of wetting. doi:10.1016/j.dental.2010.08.170 163 Angiogenesis in a bilateral maxillary sinus elevation with or without platelet-rich fibrin G. Morandi, T. Stocca, M. Maglione, M. Bertolotto University of Trieste, Italy Objectives: This paper attempts to assess the neoangiogenetic activity of various implants, through noninvasive methodologies such as contrast magnetic resonance (MR). In particular, the aim is to study the ability of Choukroun’s Platelet-rich fibrin improve this process. Materials and methods: I.T., male, aged 57, with an hypertensive syndrome pharmacologically controlled was referred to us for the rehabilitation of the totally edentulous upper arch. The preoperative CT detected a defect of the edentulous ridges height wise, an increased pneumatisation of the maxillary sinuses. After informed consent of the patient was obtained, it was decided to elevate the bilateral sinus by introducing endostal implants. A preliminary examination with contrast MR excluded any thickening of the mucosa of the maxillary sinuses, except for a small mucocele on the front wall of the left sinus. Following local plexic anaesthesia with vasoconstrictor (mepivacaine + adrenaline 1:100,000), a surgical procedure with the Caldwell-Luc technique was performed bilaterally. For both implant sites, 1 gr of autologous bone was mixed with 1 gr of Bio-Oss ® . In the right maxillary sinus, 0.05 gr of platelet-rich fibrin was added, obtained according to the Choukroun protocol. To assess the neo-angiogenesis, the patient was subjected to clinical follow-ups and using MR with STIR precontrastographic scans on the axial plane and TSE T1 weighed on the axial, coronal and sagittal plane, after 11, 25, 53 and 104 days. After the intravenous injection of the contrast means (Dotarem 20 ml), dynamic scans were performed on the passing plane for the maxillary sinuses, followed by SPIR sequences on the axial, coronal and sagittal plane. Finally, a postoperative CT Dentascan was performed. Results: During early clinical checks, the patient reported a decreasing postoperative discomfort at the level of the right implant. An optimal healing of the sites was visible via objective examination. The MR of the left site revealed a slow and progressive enhancement of circumferential profile, which from the most peripheral sectors of the implant was almost completely filled the newly implanted tissue. In the central portion there was still a small area with no enhancement, in the process of vascularisation. Conversely, in the right site there was a widespread and intense enhancement of the entire newly implanted bone tissue. Final volume grafts: right: 0.85 cm 3 ; left: 2.00 cm 3 . Bone density of right graft: rear: 936 ± 397.9 HU; center: 778.9 ± 408.6 HU; front: 910.6 ± 300 HU. Bone density of left graft: rear: 947.4 ± 265.6 HU; center: 727.4 ± 304.2 HU; front: 1033.9 ± 271.7 HU. Enhancement: right: 70,000 ± 18,538 (day 11th) 108,607 ± 26,342 (day 25th) 110,312 ± 27,687(day 53rd) 147,057 ± 24,165 (day 104th); left: 66,399 ± 15,653 (day 11th) 64,821 ± 9899 (day 25th) 71,151 ± 11,676 (day 53rd) 85,152 ± 28,886 (day 104th). Conclusions: Platelet-rich fibrin induces a faster enhancing of neo-angiogenesis and thus of physiological healing process in a maxillary sinus grafts. doi:10.1016/j.dental.2010.08.171 164 Effects of photoactivation in bleaching with hydrogen peroxide: Spectrophotometric evaluation A. Velo, G. Pajno, G. Cervino, A. Artemisia, G. Lo Giudice University of Messina, Italy Objectives: The main chemical agents used in dental bleaching are hydrogen peroxide and carbamide peroxide. Their penetration in dental tissues determines the dual bonds fission of chromophore groups, turning them into compounds with a low molecular weight that, because of a different light reflection, make evident a lighter and brighter colour of the tooth. The aim of our study was to evaluate the efficacy of a bleaching agent formed by 38% hydrogen peroxide 1 used with or without photo-activation with a led lamp. Materials and methods: Our research was performed using nine groups of samples, each one formed by two sound adjoining teeth of the frontal sector, extracted from the same patient. The bleaching treatment was performed on the first 1 Ogna White.
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