- Email: [email protected]
Effect of fluoride corrosion on the bonding strength of Ti–porcelain under static loads
Materials Letters 63 (2009) 2486–2488
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Effect of fluoride corrosion on the bonding strength of Ti–porcelain under static loads Litong Guo a,b,⁎, Haitao Wu b, Xiaochen Liu c,d, Yabo Zhu a, Jiqiang Gao b, Tianwen Guo c a
China University of Mining and Technology, Xuzhou 221116, PR China State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, PR China c The Fourth Military Medical University, Xi'an 710032, PR China d Department of Prosthodentics, Affiliated Hospital of Stomatology, School of Medicine, Zhejiang University, Hangzhou, 310006, PR China b
a r t i c l e
i n f o
Article history: Received 26 February 2009 Accepted 23 August 2009 Available online 31 August 2009 Keywords: Adhesion Surface Static loads F− Corrosion Dental material
a b s t r a c t The effect of fluoride corrosion on the bonding strength of Ti–porcelain under different static loads was investigated. The adhesion between the titanium and porcelain was evaluated by three-point flexure test. After being immersed in artificial saliva with pH 2.7 under 0 N, 1 N and 2 N static loads, respectively, no decrease of the bonding strength of Ti–porcelain occurred. However, the decrease of bonding strength was about 30%, 37%, and 46% after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static loads, respectively. The failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface. Immersion in the artificial saliva did not affect the fracture mode of the titanium–porcelain system. The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static loads enhanced the F− corrosion on the Ti–porcelain interface. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Because of their superior corrosion resistance and biocompatibility, titanium and its alloys are clinically used for dental applications. Ti and its alloys have a high corrosion resistance because they form a passive film on their surfaces [1,2]. However, in an acidic condition, the fluoride ion formed hydrofluoric acid (HF), and the presence of an HF concentration over 30 ppm resulted in the destruction of the passive film on the Ti surface [3]. The fluorides (e.g. in terms of NaF and/or Na2FPO4) contained in commercial toothpastes and prophylactic gels are used orally and topically to prevent dental caries or to relieve sensitivity [4]. Topical fluoride will remain in place. Fluorides are inimical to all reactive metals such as titanium, especially in acidic media [5]. Therefore, it would be essential to investigate the effect of corrosion on the bonding strength of the titanium–porcelain in a fluoride-containing solution that accurately simulates the above oral environment. Clinical failure often occurred after a certain period of time. It had been proposed that immersion in a corrosive solution of sodium chloride and lactic acid reduced the bonding strength of porcelain to Au-Pt-Pd alloy by about 35% after an immersion time of only two days [6]. Titanium–porcelain restorations were always used under certain static load. Thus, the purpose of this study was to evaluate the effect of
⁎ Corresponding author. School of Materials Science and Engineering, China University of Ming and Technology, Xuzhou 221116, PR China. Tel.: +86 516 83591979; fax: +86 516 83591870. E-mail address: [email protected] (L. Guo). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.08.040
fluoride corrosion on the bonding strength of low-fusing dental porcelain to titanium under static loads, so as to study further on the fracture modes and corrosion mechanics of porcelain to titanium. 2. Experimental procedures ASTM grade II CP casted titanium was sandblasted with Al2O3 particles and then washed in an ultrasonic bath in acetone for 10 min, and dried in air. Low-fusing dental porcelain was applied to titanium with a size of 25 mm × 3 mm × 0.5 mm in a Multimat 99 furnace (Dentsply, American). The porcelain built up was about 8 × 3 × 1 mm3. The three-point flexural test was performed using a universal mechanical testing machine (Shimadzu DSS-25T). For each group a set of six samples was chosen by random sampling. The three-point bonding strength was determined by failure load (Ffail) multiplied with a coefficient (K) according to the ISO 9693 [7]. The coefficient K is a function of the thickness of the titanium (dTi = 0.5 mm), and the value of Young's modulus of titanium (ETi = 105.4 GPa). The coefficient K can be expressed as: 2
K = 54:78⋅dM −73:15⋅dM + 27:65 = 4:78:
ð1Þ
The coefficients of thermal expansion (α25–500) of the bonding, opaque and dentin porcelains used in this study were 9.1, 8.9 and 8.1 ppm/°C, respectively, which were lower than that for pure titanium (9.5 ppm/°C). For investigating the influence of corrosion on the bonding strength, specimens were immersed for different time (0.5 up to 60 days) in artificial saliva with a pH of 2.7 and pH 2.7/F− 100 ppm
L. Guo et al. / Materials Letters 63 (2009) 2486–2488
under 0 N, 1 N and 2 N static loads, respectively. The artificial saliva was supplied by the pharmaceutical preparation section of School of Stomatology, the Fourth Military Medical University. The component of the artificial saliva resembled natural saliva. Specimens without immersion were set as control. The titanium–porcelain interface was characterized by XRD and SEM/EDS.
3. Results and discussion
2487
Table 1 Titanium–porcelain bonding strength before and after corrosion. Bonding strength (MPa)
0.5 day corrosion
1 day corrosion
7 day corrosion
14 day corrosion
30 day corrosion
pH 2.7 0 N pH 2.7 1 N pH 2.7 2 N pH 2.7/F− 100 ppm 0 N pH 2.7/F− 100 ppm 1 N pH 2.7/F− 100 ppm 2 N Control
35 ± 1.39 36 ± 2.04 35 ± 0.86 29 ± 0.89 26 ± 1.43 20 ± 1.45
35 ± 0.89 36 ± 2.87 35 ± 1.36 26 ± 2.05 22 ± 1.27 19 ± 1.78
34 ± 1.82 35 ± 3.26 34 ± 0.63 25 ± 1.76 21 ± 1.59 19 ± 2.06 35 ± 1.53
34 ± 2.39 34 ± 2.73 32 ± 1.72 25 ± 2.99 22 ± 2.03 20 ± 2.47
34 ± 1.74 34 ± 2.92 32 ± 2.18 25 ± 2.20 21 ± 2.64 19 ± 1.58
Fig. 1 is the XRD patterns of titanium surface debonded from porcelain after immersion for 7 days in artificial saliva with a pH of 2.7. In all cases, typical patterns of α-Ti(O) [JCPDS 44-1294], rutile phase [JCPDS 21-1276] and corundum phase [JCPDS 10-173] were obtained. The α-Ti (O) phase came from the substrate. The corundum phase [JCPDS 10-173] came from the alumina particles embedded on the titanium surface as a result of sandblasting. The rutile phase [JCPDS 21-1276] came from the oxidation of the titanium during the porcelain fusion. It proved that the failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface. The rutile layer was more strongly bonded to the porcelain than titanium. The poor adhesion of the rutile with the substrate was due to the thermal stress arising from large lattice mismatch and the large difference in coefficient of thermal expansion between Ti and rutile during cooling [8,9]. Titanium–porcelain bonding strength before and after corrosion is shown in Table 1. For the groups being immersed in artificial saliva with a pH of 2.7 under different static loads (0 N, 1 N and 2 N), the one-way ANOVA test indicated that there was no significant difference within the groups and the control (p > 0.05). However, in a fluoride-containing acidic condition, a different result was observed. For the group being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N and 1 N static loads, the one-way ANOVA and the Student–Newman–Kuels tests indicated that there was a significant decrease after 0.5 day corrosion (p < 0.05), but remained constant after 1 day corrosion(p > 0.05). For the group being immersed in artificial saliva with pH 2.7/F− 100 ppm under 2 N static load, there was a significant decrease after 12 day corrosion (p = 0.001 < 0.05), but remained constant for the period observed (p = 0.198 > 0.05). The decrease of bonding strength was about 30%, 37%, and 46% after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static loads, respectively. Fig. 2 shows the SEM micrograph of titanium surface debonded from porcelain after being immersed in different artificial saliva. Fig. 2(a) revealed that a sandwich of Ti existed in the interface of titanium– porcelain after being immersed in artificial saliva with pH 2.7 under 2 N static load for 7 days. Fig. 2(b) and (c) exhibited similar microstructure
Fig. 1. XRD patterns of titanium surface debonded from porcelain after immersion for 7 days in artificial saliva with (a) pH of 2.7, and (b) pH 2.7/F− 100 ppm under 2 N static load.
Fig. 2. SEM micrograph of titanium surface debonded from porcelain after being immersed in artificial saliva with (a) pH 2.7 under 2 N static load for 7 days, (b) pH 2.7/F− 100 ppm under 0 N static load for 0.5 day, and (c) pH 2.7/F− 100 ppm under 2 N static load for 0.5 day.
2488
L. Guo et al. / Materials Letters 63 (2009) 2486–2488
to Fig. 2(a). Fig. 2(b) and (c) revealed that many ‘corrosion pores’ existed in the interface of titanium–porcelain. With the static load increased, the quantity of the corrosion pores increased. The EDS based on raster analysis results showed that O, Ti and Al elements were obtained at the interface in all cases. Only O, Ti and Al were found at the interface after being immersed in artificial saliva with pH 2.7 under 2 N static load for 7 days. This indicated that the fracture occurred at the oxide layer and titanium. However, fluorine was found at the interface after being immersed in artificial saliva with pH 2.7/F− 100 ppm for 0.5 day. The EDS analysis revealed the existence of 21.2 wt% O, 66.4 wt% Ti, 5.3 wt% Al and 7.1 wt% F at the interface far away from the margins after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N static load for 0.5 day. The EDS analysis revealed the existence of 16.9 wt% O, 62.2 wt% Ti, 4.8 wt% Al and 16.1 wt% F at the interface far away from the margins after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 2 N static load for 0.5 day. Fluorine came from the artificial saliva as a result of corrosion on the titanium–porcelain interface. This indicated that failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface [10,11]. Immersion in the artificial saliva did not affect the fracture mode of the titanium–porcelain system [3]. With the static load increased, the content of fluorine at the interface increased and the bonding strength of Ti–porcelain decreased subsequently. It is well known that the titanium is very corrosion resistant, especially if acid solutions are used [10,12]. The influence of the pH value was important in a fluoride-containing condition. The fluorine ion formed hydrofluoric acid (HF), which resulted in the destruction of the passive film on the Ti surface [3]. At the same time, the HF also corroded the porcelain which was mostly composed of glass phase. The authors attributed reduction of bonding strength to the corrosion of the titanium–porcelain interface, because after debonding of the porcelain corrosion products could be detected at the interface far away from the margins [3,13]. This explains the observed differences.
The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static load enhanced the F− corrosion on the Ti–porcelain interface. 4. Conclusions After being immersed in artificial saliva with pH 2.7 under 0 N, 1 N and 2 N static loads, respectively, no decrease of the bonding strength of Ti–porcelain occurred. However, the decrease of bonding strength was about 30%, 37%, and 46%, respectively, after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static load, respectively. The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static load enhanced the F− corrosion on the Ti–porcelain interface. Acknowledgements The authors gratefully acknowledge the Fourth Military Medical University for providing support for porcelain fusion. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
Zhang H, Guo TW, Song ZX, Xu KW. Surf Coat Technol 2007;201:5637–40. Nakagawa M, Matono Y, Matsuya S, Udoh K, Ishikawa K. Biomater 2005;26:2239–46. Guo LT, Liu XC, He ZY, Gao JQ, Yang JF, Guo TW. Mater Lett 2008;62:2204–6. Huang HH, Lee TH. Dent Mater 2005;21:749–55. Al-Mayouf AM, Al-Swayih AA, Al-Mobarak NA, Al-Jabab AS. Mater Chem Phys 2004;86:320–9. Fischer J. Biomater 2002;23:1303–11. 9693. Geneva: International Organization for Standardization; 1999. Siva Rama Krishna D, Brama YL, Sun Y. Trib Inter 2007;40:329–34. Grosgogeat B, Reclaru L, Lissac M, Dalard F. Biomater 1999;20:933–41. Demetrescu I, Popescu B, Ionita D. Mol Cryst Liquid Cryst 2006;48:103–13. Guo LT, Liu XC, He ZY, Gao JQ, Yang JF, Guo TW. J Sol-Gel Sci Technol 2008;47:239–42. Al-Mobarak NA, Al-Mayouf AM, Al-Swayih AA. Mater Chem Phys 2006;99:333–40. Kraft J, Stender E. Dtsch Zahnarztl Z 1995;50:371–4.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Effect of fluoride corrosion on the bonding strength of Ti–porcelain under static loads Litong Guo a,b,⁎, Haitao Wu b, Xiaochen Liu c,d, Yabo Zhu a, Jiqiang Gao b, Tianwen Guo c a
China University of Mining and Technology, Xuzhou 221116, PR China State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, PR China c The Fourth Military Medical University, Xi'an 710032, PR China d Department of Prosthodentics, Affiliated Hospital of Stomatology, School of Medicine, Zhejiang University, Hangzhou, 310006, PR China b
a r t i c l e
i n f o
Article history: Received 26 February 2009 Accepted 23 August 2009 Available online 31 August 2009 Keywords: Adhesion Surface Static loads F− Corrosion Dental material
a b s t r a c t The effect of fluoride corrosion on the bonding strength of Ti–porcelain under different static loads was investigated. The adhesion between the titanium and porcelain was evaluated by three-point flexure test. After being immersed in artificial saliva with pH 2.7 under 0 N, 1 N and 2 N static loads, respectively, no decrease of the bonding strength of Ti–porcelain occurred. However, the decrease of bonding strength was about 30%, 37%, and 46% after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static loads, respectively. The failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface. Immersion in the artificial saliva did not affect the fracture mode of the titanium–porcelain system. The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static loads enhanced the F− corrosion on the Ti–porcelain interface. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Because of their superior corrosion resistance and biocompatibility, titanium and its alloys are clinically used for dental applications. Ti and its alloys have a high corrosion resistance because they form a passive film on their surfaces [1,2]. However, in an acidic condition, the fluoride ion formed hydrofluoric acid (HF), and the presence of an HF concentration over 30 ppm resulted in the destruction of the passive film on the Ti surface [3]. The fluorides (e.g. in terms of NaF and/or Na2FPO4) contained in commercial toothpastes and prophylactic gels are used orally and topically to prevent dental caries or to relieve sensitivity [4]. Topical fluoride will remain in place. Fluorides are inimical to all reactive metals such as titanium, especially in acidic media [5]. Therefore, it would be essential to investigate the effect of corrosion on the bonding strength of the titanium–porcelain in a fluoride-containing solution that accurately simulates the above oral environment. Clinical failure often occurred after a certain period of time. It had been proposed that immersion in a corrosive solution of sodium chloride and lactic acid reduced the bonding strength of porcelain to Au-Pt-Pd alloy by about 35% after an immersion time of only two days [6]. Titanium–porcelain restorations were always used under certain static load. Thus, the purpose of this study was to evaluate the effect of
⁎ Corresponding author. School of Materials Science and Engineering, China University of Ming and Technology, Xuzhou 221116, PR China. Tel.: +86 516 83591979; fax: +86 516 83591870. E-mail address: [email protected] (L. Guo). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.08.040
fluoride corrosion on the bonding strength of low-fusing dental porcelain to titanium under static loads, so as to study further on the fracture modes and corrosion mechanics of porcelain to titanium. 2. Experimental procedures ASTM grade II CP casted titanium was sandblasted with Al2O3 particles and then washed in an ultrasonic bath in acetone for 10 min, and dried in air. Low-fusing dental porcelain was applied to titanium with a size of 25 mm × 3 mm × 0.5 mm in a Multimat 99 furnace (Dentsply, American). The porcelain built up was about 8 × 3 × 1 mm3. The three-point flexural test was performed using a universal mechanical testing machine (Shimadzu DSS-25T). For each group a set of six samples was chosen by random sampling. The three-point bonding strength was determined by failure load (Ffail) multiplied with a coefficient (K) according to the ISO 9693 [7]. The coefficient K is a function of the thickness of the titanium (dTi = 0.5 mm), and the value of Young's modulus of titanium (ETi = 105.4 GPa). The coefficient K can be expressed as: 2
K = 54:78⋅dM −73:15⋅dM + 27:65 = 4:78:
ð1Þ
The coefficients of thermal expansion (α25–500) of the bonding, opaque and dentin porcelains used in this study were 9.1, 8.9 and 8.1 ppm/°C, respectively, which were lower than that for pure titanium (9.5 ppm/°C). For investigating the influence of corrosion on the bonding strength, specimens were immersed for different time (0.5 up to 60 days) in artificial saliva with a pH of 2.7 and pH 2.7/F− 100 ppm
L. Guo et al. / Materials Letters 63 (2009) 2486–2488
under 0 N, 1 N and 2 N static loads, respectively. The artificial saliva was supplied by the pharmaceutical preparation section of School of Stomatology, the Fourth Military Medical University. The component of the artificial saliva resembled natural saliva. Specimens without immersion were set as control. The titanium–porcelain interface was characterized by XRD and SEM/EDS.
3. Results and discussion
2487
Table 1 Titanium–porcelain bonding strength before and after corrosion. Bonding strength (MPa)
0.5 day corrosion
1 day corrosion
7 day corrosion
14 day corrosion
30 day corrosion
pH 2.7 0 N pH 2.7 1 N pH 2.7 2 N pH 2.7/F− 100 ppm 0 N pH 2.7/F− 100 ppm 1 N pH 2.7/F− 100 ppm 2 N Control
35 ± 1.39 36 ± 2.04 35 ± 0.86 29 ± 0.89 26 ± 1.43 20 ± 1.45
35 ± 0.89 36 ± 2.87 35 ± 1.36 26 ± 2.05 22 ± 1.27 19 ± 1.78
34 ± 1.82 35 ± 3.26 34 ± 0.63 25 ± 1.76 21 ± 1.59 19 ± 2.06 35 ± 1.53
34 ± 2.39 34 ± 2.73 32 ± 1.72 25 ± 2.99 22 ± 2.03 20 ± 2.47
34 ± 1.74 34 ± 2.92 32 ± 2.18 25 ± 2.20 21 ± 2.64 19 ± 1.58
Fig. 1 is the XRD patterns of titanium surface debonded from porcelain after immersion for 7 days in artificial saliva with a pH of 2.7. In all cases, typical patterns of α-Ti(O) [JCPDS 44-1294], rutile phase [JCPDS 21-1276] and corundum phase [JCPDS 10-173] were obtained. The α-Ti (O) phase came from the substrate. The corundum phase [JCPDS 10-173] came from the alumina particles embedded on the titanium surface as a result of sandblasting. The rutile phase [JCPDS 21-1276] came from the oxidation of the titanium during the porcelain fusion. It proved that the failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface. The rutile layer was more strongly bonded to the porcelain than titanium. The poor adhesion of the rutile with the substrate was due to the thermal stress arising from large lattice mismatch and the large difference in coefficient of thermal expansion between Ti and rutile during cooling [8,9]. Titanium–porcelain bonding strength before and after corrosion is shown in Table 1. For the groups being immersed in artificial saliva with a pH of 2.7 under different static loads (0 N, 1 N and 2 N), the one-way ANOVA test indicated that there was no significant difference within the groups and the control (p > 0.05). However, in a fluoride-containing acidic condition, a different result was observed. For the group being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N and 1 N static loads, the one-way ANOVA and the Student–Newman–Kuels tests indicated that there was a significant decrease after 0.5 day corrosion (p < 0.05), but remained constant after 1 day corrosion(p > 0.05). For the group being immersed in artificial saliva with pH 2.7/F− 100 ppm under 2 N static load, there was a significant decrease after 12 day corrosion (p = 0.001 < 0.05), but remained constant for the period observed (p = 0.198 > 0.05). The decrease of bonding strength was about 30%, 37%, and 46% after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static loads, respectively. Fig. 2 shows the SEM micrograph of titanium surface debonded from porcelain after being immersed in different artificial saliva. Fig. 2(a) revealed that a sandwich of Ti existed in the interface of titanium– porcelain after being immersed in artificial saliva with pH 2.7 under 2 N static load for 7 days. Fig. 2(b) and (c) exhibited similar microstructure
Fig. 1. XRD patterns of titanium surface debonded from porcelain after immersion for 7 days in artificial saliva with (a) pH of 2.7, and (b) pH 2.7/F− 100 ppm under 2 N static load.
Fig. 2. SEM micrograph of titanium surface debonded from porcelain after being immersed in artificial saliva with (a) pH 2.7 under 2 N static load for 7 days, (b) pH 2.7/F− 100 ppm under 0 N static load for 0.5 day, and (c) pH 2.7/F− 100 ppm under 2 N static load for 0.5 day.
2488
L. Guo et al. / Materials Letters 63 (2009) 2486–2488
to Fig. 2(a). Fig. 2(b) and (c) revealed that many ‘corrosion pores’ existed in the interface of titanium–porcelain. With the static load increased, the quantity of the corrosion pores increased. The EDS based on raster analysis results showed that O, Ti and Al elements were obtained at the interface in all cases. Only O, Ti and Al were found at the interface after being immersed in artificial saliva with pH 2.7 under 2 N static load for 7 days. This indicated that the fracture occurred at the oxide layer and titanium. However, fluorine was found at the interface after being immersed in artificial saliva with pH 2.7/F− 100 ppm for 0.5 day. The EDS analysis revealed the existence of 21.2 wt% O, 66.4 wt% Ti, 5.3 wt% Al and 7.1 wt% F at the interface far away from the margins after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N static load for 0.5 day. The EDS analysis revealed the existence of 16.9 wt% O, 62.2 wt% Ti, 4.8 wt% Al and 16.1 wt% F at the interface far away from the margins after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 2 N static load for 0.5 day. Fluorine came from the artificial saliva as a result of corrosion on the titanium–porcelain interface. This indicated that failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface [10,11]. Immersion in the artificial saliva did not affect the fracture mode of the titanium–porcelain system [3]. With the static load increased, the content of fluorine at the interface increased and the bonding strength of Ti–porcelain decreased subsequently. It is well known that the titanium is very corrosion resistant, especially if acid solutions are used [10,12]. The influence of the pH value was important in a fluoride-containing condition. The fluorine ion formed hydrofluoric acid (HF), which resulted in the destruction of the passive film on the Ti surface [3]. At the same time, the HF also corroded the porcelain which was mostly composed of glass phase. The authors attributed reduction of bonding strength to the corrosion of the titanium–porcelain interface, because after debonding of the porcelain corrosion products could be detected at the interface far away from the margins [3,13]. This explains the observed differences.
The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static load enhanced the F− corrosion on the Ti–porcelain interface. 4. Conclusions After being immersed in artificial saliva with pH 2.7 under 0 N, 1 N and 2 N static loads, respectively, no decrease of the bonding strength of Ti–porcelain occurred. However, the decrease of bonding strength was about 30%, 37%, and 46%, respectively, after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static load, respectively. The corrosion of the Ti–porcelain interface resulted in the reduction of bonding strength. The static load enhanced the F− corrosion on the Ti–porcelain interface. Acknowledgements The authors gratefully acknowledge the Fourth Military Medical University for providing support for porcelain fusion. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
Zhang H, Guo TW, Song ZX, Xu KW. Surf Coat Technol 2007;201:5637–40. Nakagawa M, Matono Y, Matsuya S, Udoh K, Ishikawa K. Biomater 2005;26:2239–46. Guo LT, Liu XC, He ZY, Gao JQ, Yang JF, Guo TW. Mater Lett 2008;62:2204–6. Huang HH, Lee TH. Dent Mater 2005;21:749–55. Al-Mayouf AM, Al-Swayih AA, Al-Mobarak NA, Al-Jabab AS. Mater Chem Phys 2004;86:320–9. Fischer J. Biomater 2002;23:1303–11. 9693. Geneva: International Organization for Standardization; 1999. Siva Rama Krishna D, Brama YL, Sun Y. Trib Inter 2007;40:329–34. Grosgogeat B, Reclaru L, Lissac M, Dalard F. Biomater 1999;20:933–41. Demetrescu I, Popescu B, Ionita D. Mol Cryst Liquid Cryst 2006;48:103–13. Guo LT, Liu XC, He ZY, Gao JQ, Yang JF, Guo TW. J Sol-Gel Sci Technol 2008;47:239–42. Al-Mobarak NA, Al-Mayouf AM, Al-Swayih AA. Mater Chem Phys 2006;99:333–40. Kraft J, Stender E. Dtsch Zahnarztl Z 1995;50:371–4.