d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
Conclusion: The RMGIC preparation technique had an effect on the surface properties of both analysed materials. PHO showed almost double DC when an LED light was used and better wettability when using a halogen light-curing unit. Nevertheless, there was no signiﬁcant difference found in Ra whether halogen light or LED was used. FUJ revealed better Ra results when the halogen light was used and better wettability with the LED. However, no signiﬁcant difference between the halogen light and LED was found on DC.
Analyse of the physico-chemical properties of the resin-modiﬁed glass ionomer cements T.F. Dantas a,b , V. Cruz de Jesus a,c,∗ , P.F.D. Silva a,d , O.V. Aires a,e , R. Franc¸a a a
University of Manitoba, Winnipeg, Canada Universidade Federal Do Ceará - UFC, Brazil c Universidade Federal Da Bahia - UFBA, Brazil d Universidade Federal De Alagoas - UFAL, Brazil e Universidade Federal Da Paraíba - UFPB, Brazil) b
Purpose: The aim of this study is to assess the inﬂuence of mixing time and different light-curing sources on the properties of cement, focusing on the cement surface. Methods and materials: Two different resin-modiﬁed glass ionomer cements (RMGIC) were evaluated: Photac Fil, 3 M ESPE (PHO) and Fuji II LC, GC Coproration (FUJ). The samples were divided up into 12 groups based on the light-curing source LED (L) or halogen light (H), and the mixing time used (8 s, 10 s or 15 s in an auto-mix, 3MTM ESPETM CapMixTM Capsule): PHO8H, PHO10H, PHO15H, PHO8L, PHO10L, PHO15L, FUJ8H, FUJ10H, FUJ15H, FUJ8L, FUJ10L, and FUJ15L. Surface roughness (Ra) measurements were carried out using Surftest SJ-210, Mitutoyo (n = 6); wettability was evaluated by raméhart Contact Angle (CA) (n = 10); degree of conversion (DC) and chemical composition (CC) were estimated using Fourier transform infrared spectroscopy (FTIR) (Thermo Scientiﬁc NicoletTM 6700, n = 2). The obtained mean data was subjected to 2-way ANOVA and Tukey’s post hoc test at 5% signiﬁcance level. Results: Mean and standard deviation values of DC, CA, and Ra are presented in the table. The DC results revealed a signiﬁcant difference between both 10 s and 15 s mixing time for all materials (p < 0.05). PHO-L presented higher values of DC than FUJ-L and FUJ-H. Furthermore, there was a statistical difference between PHO-L and PHO-H (p < 0.05). There was no signiﬁcant difference in the CA between the 8 s and 10 s mixing time, regardless of the RMGIC or light-curing unit used (p > 0.05). The use of different light-curing units inﬂuenced the wettability of the analysed materials (p < 0.05). FTIR analysis showed no difference in CC with the evaluated techniques in this study.
RMGIC Photac Fil
Light-curing unit Halogen light
Fuji II LC
Halogen light LED
Mixing time (2) 8 10 15 8 10 15 8 10 15 8 10 15
81 The mechanical properties of dental composite resin incorporated silver zeolites P. Ekworapoj Srinakarinwirot University, Thailand Purpose: Recent report showed the antibacterial property toward to S mutan of silver inorganic materials such as silver zeolites (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP). This study aims to improve antibacterial property of dental composite by adding silver zeolites into dental composite and evaluate the effect on the compressive strength (CS) and surface microhardness (VHN) of AgZ modiﬁed composite. Methods and materials: The nanohybrid composite (SonicFill, Kerr Corp., USA) was simple blended with different weight percent of AgZ (Zeomic AW10D, Sinanen Zeomic Co., Ltd., Japan) and divided into three experimental groups (1, 2, and 3 wt%). The control group was the one without AgZ. All specimens were aged in deinonized water for 24 h, 37 ◦ C before testing. Then CS and VHN were performed using universal testing machine (Instron 5566, Instron Corp., UK) with cross head speed of 0.75 mm/min and microhardness tester (FM 700e type D, Future Tech Corp., Japan) respectively. Data was analyzed by One-way ANOVA with Tukey’s test. Results: Both CS (215.87–239.47 MPa) and VHN (63.81–71.78) of AgZ modiﬁed resin composite is higher than the non-AgZ one (CS = 203.23 MPa, VHN = 64.84). VHN decreased when the
13.7 (±1.77) 26.5 (±6.36) 11.1 (±15.6) 23.5 (±2.12) 47.5 (±2.12) 28.0 (±1.41) 22.7 (±3.82) 15.5 (±0.71) 21.7 (±12.36) 24.0 (±4.24) 22.0 (±15.56) 12.0 (±1.41)
64.21 (±3.26) 54.29 (±5.66) 48.64 (±8.77) 54.56 (±4.57) 67.26 (±0.14) 85.28 (±1.27) 76.85 (±1.47) 70.51 (±4.50) 77.09 (±1.17) 64.72 (±1.57) 65.58 (±1.58) 59.15 (±0.37)
RA (m) 0.172 (±0.03) 0.148 (±0.04) 0.178 (±0.02) 0.182 (±0.01) 0.187 (±0.01) 0.167 (±0.02) 0.107 (±0.02) 0.142 (±0.04) 0.139 (±0.03) 0.187 (±0.02) 0.145 (±0.03) 0.135 (±0.04)
d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
weight percent of AgZ increasing but not signiﬁcantly different. There was no statistical difference (P > 0.05) in the strength characteristics and surface hardness of composite resin and AgZ modiﬁed resin composite. Conclusion: The present study conﬁrmed that strength characteristics and microhardness of composite resin with AgZ were similar to non-AgZ containing composite resin. Therefore, the improvement of antibacterial property by incorporation of AgZ may not affect the mechanical properties of composite resin. The suggested percent of AgZ incorporation is at 2% by weight.
Conclusion: Hands-on training signiﬁcantly improved the ability of students to light cure on a patient simulator. Before Mean irradiance (mW/cm2 ) Maximum irradiance (mW/cm2 ) Total energy delivered (J/cm2 ) Time required for 16J/cm2 (s)
549 ± 133
675 ± 159
700 ± 157
823 ± 160
5.5 ± 1.4
7.0 ± 1.6
31 ± 10
26 ± 11
Control 1 wt% AgZ 2 wt% AgZ 3 wt% AgZ
Compressive strength (MPa)
203.23 (29.94) 215.87 (49.89) 235.68 (43.25) 239.47 (12.11)
Vickers hardness (VHN) 64.84 (6.50) 71.78 (2.27) 70.48 (3.12) 63.81 (4.98)
83 Comparative evaluation of polymerization stress with two different testing systems K. Esquibel 1,∗ , A.P. Fugolin 2,3 , C.S. Pfeifer 2 , M. Kumor 1 , N. Elmogtaba 1 , C. Bracho-Troconis 1 , M. Trujillo-Lemon 1 1
http://dx.doi.org/10.1016/j.dental.2013.08.082 82 Effect of training for undergraduate dental students on curing technique G. De Souza, W. El-Badrawy ∗ , L. Tam University of Toronto, Toronto, Canada Purpose: An optimal light curing procedure is required to maximize composite resin polymerization and ensure operator safety. However, attention to this step is often taken lightly. Therefore, the aim of this study was to evaluate the effect of hands-on training on the efﬁcacy of a light curing procedure done by undergraduate dental students. Methods and materials: 21 ﬁrst year dental students were used for this pilot study. Students received basic information about light-curing in a lecture and watched a presentation detailing the “7 steps to ensure better light curing”. Students were then asked to light-cure a class I cavity preparation on tooth #27 using a patient simulator (Marc patient simulator, BlueLight Analytics) and a halogen light curing device (Demi Plus LED curing light, Kerr.) Curing time was restricted to 10 s. Light intensity and energy delivered to the sensor at the bottom of the cavity were recorded, and the time required to deliver 16 J/cm2 was calculated. Following that, students received orientation with regard to the mistakes observed during the light curing procedure. A “gold-standard” light curing technique was demonstrated and the light-intensity curves presented by the group were presented and discussed. After that, students were requested to light cure the same tooth again, and light intensity and energy were recorded again for comparison. Paired t-tests were used for statistical analysis (p < 0.05). Results: Results (mean + SD and t-test p-value) are shown in the table.
Septodont, Colorado Research Center, Louisville, CO, USA 2 Oregon Health & Science University, Portland, OR, USA 3 UNICAMP, Piracicaba, SP, Brazil Purpose: In resin-based dental composites, the polymerization stress transferred to the bonded interface can lead to recurrent decay and post-op sensitivity, among other things. Over the years, several techniques have been developed to measure shrinkage stress. The purpose of this study is to compare the results of polymerization shrinkage stress (PS, in MPa) of commercially available composite materials using two different mechanical testing systems. Both are based on cantilever beam deﬂection theory – the Bioman (Watts et al., 2005) and the Tensometer (Lu et al., 2004). Methods and materials: The polymerization stress of nine commercial composites (Esthet-X HD (Dentsply), Filtek Z250, Filtek Supreme Ultra and Filtek LS (all from 3 M ESPE), Grandio (Voco), Vit-l-escence (Ultradent), Simile (Pentron Clinical), Image (Septodont), and N’Durance (Septodont)) were assessed using the two testing systems mentioned above. Specimens curing conditions were similar for all of the materials (QTH light source, 500 mW/cm2 × 40 s). Data were analyzed with one-way ANOVA/Tukey’s test (a = 5%) within the same test. Material ranking according to each test was compared with Student’s t-test (a = 5%). Results: Results were normal and homoscedastic (p < 0.05) and are displayed in Fig. 1. The ranking of different materials was not consistent between the two test apparatus. With only one exception (Filtek LS), the Bioman produced higher stress values than the tensometer. The differences in average stress varied over a wide range, from 3% (Vit-l-escence) up to 65% (N’Durance). In general, only the extreme values of stress (Filtek LS for the lower end and Vit-l-escence for the higher end) showed good agreement between the two test systems. It can be speculated that, even though the irradiance reaching the specimen was the same in both tests, the spectral distribution might have been different after transmission through