Adhesion of resin–resin and resin–lithium-disilicate ceramic: A methodological assessment

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light-curing for 3 min and then heated at 120 ◦ C for 2 h, resulting in the hard nanocomposite resin blocks, CRB1 (170 MPa) and CRB2 (950 MPa). The inorganic filler content was measured by ignition residue at 600 ◦ C and the volume content was calculated by the gravity of nanosilica and matrix polymer. TEM observations were carried with the 50 nm thickness sectioned specimen. The flexural strengths were measured according to ISO4049, the specimens, 2 mm × 2 mm × 25 mm, were cut from the CRB using a diamond saw. Results: The inorganic filler contents were 70.1 wt% (56 vol%) for CRB1 and 76.0 wt% (64 vol%) for CRB2. The TEM images of the CRB (Fig. 1) reveal that the nanofiller are uniformly and densely distributed. The flexural strengths were 201 MPa for CRB1 and 208 MPa for CRB2, the flexural modulus were 10.1 GPa for CRB1 and 15.2 GPa for CRB2. Conclusions: The greater the pressure of the nanofiller molding in the FPMI method, the more nanofiller in the CRB resulting in a high elastic modulus CRB. The nanocomposite material in this study will be useful for the fabrication of permanent resin crown. http://dx.doi.org/10.1016/j.dental.2017.08.120 120 Can glass ionomer cements inhibit cariogenic species? In vitro study N.A. Oliveira ∗ , F.B. Andrade, I.F. Leão, S.K. Ishikiriama, J.F.S. Bombonatti Department of Operative Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil Purpose/aim: The objective of this in vitro study was to determine whether glass ionomer cements (GICs) can inhibit bacteria involved in caries lesion process. For this, three strains were selected: Streptococcus mutans (ATCC 25175), Lactobacillus casei (ATCC 334) and Bifidobacterium dentium (ATCC 27534). Materials and methods: Three GICs were tested, two conventional GICs (Fuji IX Extra and IonZ – a new GIC available in Brazil, that present in its composition zinc oxide particles) and one resin modified GIC (Fuji II LC) using two methodology: agar diffusion test and direct contact test. The GICs were tested immediately after manipulation (I) and after 10 min (M). For the agar diffusion test the mean inhibition zones in millime-

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ters were measured and for direct contact test the number of colony forming units was evaluated by scores. The tests were done in triplicate. Results: For S. mutans, just Fuji IX Extra (I) and Ion-Z (I) presented inhibition zones of 3.00 (±5.19) and 10.66 (±4.61) mm respectively in agar diffusion test, and, a score of 3 (dense bacterial growth) for direct contact test. L. casei was inhibited in agar diffusion test by Fuji IX Extra (I) and (M), Ion-Z (I) and (M), and the major inhibition zone was for Fuji IX Extra (M) with 14.00 (±1.73) mm. In direct contact test, L. casei presented a score 2, a moderate bacterial growth against the cements. In agar diffusion test, B. dentium was inhibited by Fuji IX Extra (M) with 9.33 (±8.14) mm, Ion-Z (M) 7.33 (±1.52) mm and Ion-Z (I) 6.33 (±5.68) mm of inhibition zones. In direct contact test, Fuji II LC (I) allowed a higher B. dentium growth (score 3), and the others GICs I or M presented a slight bacterial growth (score between 1.66 and 2.22). Conclusions: The conventional GICs (Fuji IX Extra and Ion-Z) could inhibit the growth of cariogenic species, varying among bacteria. B. dentium demonstrated lower resistance against the conventional GICs tested. The resin modified GIC (Fuji II LC) could not present inhibition zones for the bacteria tested in this in vitro study. http://dx.doi.org/10.1016/j.dental.2017.08.121 121 Adhesion of resin–resin and resin–lithium-disilicate ceramic: A methodological assessment N. Al-Haj Husain, A. Alshihri, M. Özcan ∗ Division of Dental Materials, University of Zurich, Zurich, Switzerland Purpose/aim: Dental literature contains overwhelming amount of work on adhesion to dental ceramics but several test methods have not been studied in one investigation. This study compared the adhesion of resin composite to resin and lithium-disilicate ceramic using four common adhesion test methods. Materials and methods: Resin composite specimens (N = 180, Quadrant Universal LC) were obtained and randomly assigned to test the adhesion to resin composite (Quadrant Universal LC) and lithium disilicate ceramic (IPS e.max CAD) using one of the following test methods: (a) macroshear test (SBT) (n = 30), (b) macrotensile test (TBT) (n = 30), (c) microshear test (␮SBT) (n = 30) and (d) microtensile test (␮TBT) (n = 6, ncomposite : 216, nceramic : 216). Bonded specimens were stored for 24 h at 23 ◦ C. Adhesion tests were performed in a Universal Testing Machine (1 mm/min) and failure types were analyzed after debonding. Data were analyzed using Univariate and Tukey’s, Bonneferroni post-hoc test (alpha = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Results: Both the test method (p < 0.05) and adherendsubstrate type (p < 0.05) significantly affected the adhesion results. Interaction terms were also significant (p < 0.05). When testing adhesion of resin to resin, SBT (24.4 ± 5)a, TBT (16.1 ± 4.4)b and ␮SBT (20.6 ± 7.4)a,b test methods showed

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significantly lower mean bond values compared to ␮TBT (36.7 ± 8.9)c (p < 0.05). However, for resin composite-glass ceramic adhesion, ␮SBT (6.6 ± 1)B showed the lowest and ␮TBT (24.8 ± 7)C,D the highest values (p < 0.05). Only SBT and ␮TBT presented significant difference in adhesion results for resin–resin (24.4 ± 5; 36.7 ± 9) and resin–ceramic adhesion (14.6 ± 5; 25 ± 7), respectively (p < 0.05). Weibull distribution presented the highest shape values for resin–ceramic (7.6) and resin–resin (5.7) among all substrate-test combinations when ␮TBT was employed. Incidence of cohesive failures (%) were most frequent in resin–resin combination (SBT: 87; TBT: 50; ␮SBT: 50), while mixed failures were more common in resin–ceramic specimens (SBT: 100; TBT: 90; ␮SBT: 90). Conclusions: Considering bond strength values, Weibull modulus and the failure types, resin–resin adhesion was more reliable than resin–ceramic. ␮TBT tests could be considered more suitable for testing adhesion of resin to resin, and ␮TBT and ␮SBT for resin to lithium disilicate materials as these tests showed significant distinction to other test methods in one study. http://dx.doi.org/10.1016/j.dental.2017.08.122 122 Hybrid manufacturing of metal framework for full arch dental restoration L. Ciocca 1 , C. Parisi 1,∗ , R. Meneghello 2 , C. Monaco 1 , P. Baldissara 1 1

Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy 2 Université de Montréal, Montréal, Québec, Canada Purpose/aim: Selective Laser Melting (SLM) technology used for the production of a full-arch prosthetic restoration on implants generates geometry inaccuracies and surface roughness, which do not fulfill clinical requirements, with biological consequences on the osteointegration of implants. Modern approach to Additive Manufacturing (AM) for precision production integrates SLM and milling techniques in the so-called hybrid manufacturing process to produce a more accurate interface to implant. Materials and methods: The virtual (CAD) model of the framework was designed as for a full-arch prosthetic rehabilitation and served as the control of the experiment. Directly from the framework CAD model, eighteen specimens were produced by two different manufacturing centers using hybrid technology, (lab #1 and lab #2). This is a recently introduced productive process, which integrates the SLM, for the production of a semi-finished framework, and the milling technique, for the finishing operation at the interface to implant. Measurements of the frameworks were made in vitro according to a metrological approach that uses an opto-mechanical coordinate measuring machine (OCMM), a CAD-based reconstruction of actual interface, and a geometric error analysis to describe manufacturing inaccuracies. Each implant platform of framework was reduced to its center for the calculation of the relative (between implants) and absolute distances (between manufactured framework and its CAD model).

Results: The relative 3D distances between implant platforms showed a mean error varying from 0 to 25 ␮m for lab #1 and 0 to 38 ␮m for lab #2; the 3D mean position error of the implant platforms with respect to the CAD model was 8–16 ␮m for lab #1 and 9–22 ␮m for lab #2. No statistically significant difference was registered between the two groups. Considering both groups, the absolute values of inaccuracy were between 0.011 mm and 0.019 mm ± 0.005–0.010 mm (SD). Conclusions: The hybrid technology used for the manufacturing of the metal framework for an implant-supported full-arch restoration showed acceptable levels of accuracy, regardless the specific hybrid system. Using the hybrid technology, the geometric error generated during the framework production is lower than 22 ␮m, which is comparable to errors shown in the literature for direct CAD-CAM manufacturing from metal blanks. http://dx.doi.org/10.1016/j.dental.2017.08.123 123 Effect of radiotherapy on resin cements bond strength R.D. Pereira 1,∗ , P.A. Yamin 1 , P.C. Saquy 1 , H.F. Oliveira 2 , A.M. Queiroz 1 , M.D. Sousa-Neto 1 1

School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil 2 Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil Purpose/aim: Evaluate the influence of radiotherapy on bond strength (BS) and adhesive interface among different resin cements and root dentin. Materials and methods: Sixty maxillary canines were selected and distributed into two groups (n = 30) according to the irradiation protocol: non-irradiated and irradiated. The irradiated group was submitted to X-ray radiotherapy of 6 MV in fractions of 2 Gy, with 30 cycles, until complete 60 Gy. The teeth were sectioned to obtain 16 mm of root length, followed by biomechanical preparation with R50 reciproc instrument and filling using the lateral condensation technique with epoxy resin-based sealer. Then, each group was subdivided according to the resin cement used for the glass fiber post cementation (n = 10): RelyX U200, Panavia F 2.0 and RelyX ARC. The posts were cemented according to the manufacturer instructions. After the posts cementation, the teeth were sectioned transversely into 1 mm thick slices, and 3 slices were obtained from each root third. The most cervical slice of each third was used to evaluate the BS by the push-out test at 0.5 mm/min and the failure pattern was analyzed. Apical slice of each third was selected for SEM analysis, which were prepared and metalized. The dentin/cement interface analysis was performed at the following magnification: 100, 1000, 2000 and 4000×. The BS data were submitted to statistical analysis by ANOVA and Tukey’s test. Results: The irradiated specimens had lower BS values (8.23 + 4.26) compared to non-irradiated group (11.88 + 6.42) (p < 0.00001). Regarding the resin cements, the RelyX U200 showed the higher values in BS (15.17 + 5.89) compared