Microleakage of Inlay Ceramic Systems Luted with Self-adhesive Resin Cements Bulent Uludaga / Elif Yucedagb / Volkan Sahinc
Purpose: To evaluate the microleakage of Cerec 3, IPS e.max Press, and Turkom-Cera inlays cemented with three self-adhesive resin cements. Materials and Methods: Ninety standardized class III MOD cavities were prepared in intact human mandibular third molars. Ceramic inlays were fabricated according to the manufacturer’s instructions and were cemented using three self-adhesive resin cements (RelyX Unicem, Smartcem 2, and SpeedCEM). The specimens were stored in distilled water at 37°C for 24 h and subjected to 1000 thermocycles in water between 5°C and 55°C with a dwell time of 30 s. Subsequently, the specimens were subjected to 100,000 cycles of mechanical loading of 50 N at 1.6 Hz in 37°C water. The specimens were immersed in 0.5% basic fuchsine for 24 h and were sectioned using a low-speed diamond blade. The percentage of dye leakage at the tooth/restoration interface was measured and compared by Kruskal-Wallis tests with Bonferonni correction and Mann-Whitney U-tests at a significance level of p < 0.05. Results: Microleakage at the RelyX Unicem interface was lower than that with Smartcem 2 and SpeedCEM resin cements (p < 0.05). Microleakage of the Turkom-Cera system was higher than Cerec 3 and IPS e.max Press ceramic inlays (p < 0.05). Conclusions: Regardless of the ceramic system and self-adhesive resin cement used, dentin margins were associated with higher microleakage than enamel margins. Keywords: microleakage, inlay ceramic systems, resin cements. J Adhes Dent 2014; 16: 523–529. doi: 10.3290/j.jad.a32811
O
wing to increasing demands for esthetic dental materials, remarkable improvements in tooth-colored inlay systems have been recently made as an alternative to silver amalgam alloys, especially in the posterior region.28 Although esthetic restorations in the posterior teeth are amongst the critical elements of state-of-theart dentistry, their use is not a necessity.23 During polymerization, composite restorative materials undergo significant volumetric shrinkage. This property leads to poor marginal quality in composite restorations.17,19,29 Because of the limitations of resin composites, such as wear, polymerization shrinkage, and high coefficients of thermal expansion, ceramic inlays have
a
Professor, Department of Prosthodontics, Faculty of Dentistry, Ankara, Turkey. Idea, hypothesis, experimental design.
b
Doctor, Adıyaman Dental Hospital, Adıyaman, Turkey. Performed the experiments, wrote the manuscript.
c
Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Kırıkkale University, Kırıkkale,Turkey. Co-wrote and proofread the manuscript.
Correspondence: Dr. Bulent Uludag, Ankara University, Faculty of Dentistry, Department of Prosthodontics, 06500, Besevler, Ankara, Turkey. Tel: +90312-296-5706, Fax: +90-312-123-954. e-mail: [email protected]
Vol 16, No 6, 2014
Submitted for publication: 01.12.13; accepted for publication: 06.08.14
been developed as an alternative to composite inlays.31 One of the advantages of the ceramic inlay technique is that the thermal expansion of the ceramic material is similar to that of the tooth substance and the polymerization shrinkage of the composite luting resin is reduced, thus improving marginal adaptation.9,42 However, treatment involving the use of ceramic inlays is burdened by marginal discoloration, postoperative sensitivity and recurrent caries associated with microleakage. Accordingly, different types of ceramic systems have been developed as an alternative to the powder-liquid systems to improve marginal adaptation. These new technologies include the use of computer designed restorations (CAD/CAM) and heat-pressed ceramics.20,35 The Cerec CAD/CAM system (Sirona; Bensheim, Germany) offers the opportunity to prepare, design, and fabricate a ceramic restoration in a single appointment, eliminating conventional impression taking, provisional restorations, and dental laboratory involvement.14,25,26,27 The Cerec procedure includes cavity preparation, optical impression of the actual or the prepared tooth on the master cast, the design and fabrication process, and adjustment and cementation of the restoration.44 A survival rate of 95% for bonded all-ceramic inlays up to 10 years has been documented using this technology.34 IPS e.max 523
Uludag et al
Press (Ivoclar Vivadent; Schaan, Liechtenstein) is a heatpressed, lithium disilicate-reinforced material made by the conventional “lost wax” technique.37 This material has been used for single- or three-unit restorations in the anterior region extending to the second premolar.40 Turkom-Cera (Turkom-Ceramic; Kuala Lumpur, Malaysia) has been introduced onto the market as a high-strength, cost-effective material to improve clinical success.2 Turkom-Cera has a high-alumina core, which can be easily crystal hardened or glass infiltrated.2,36 However, alumina cores tend to be opaque and require the use of veneering to mask the core and provide the desired contours.3,22 The microleakage of Turkom-Cera inlays has not been documented so far. Adhesion between the tooth structure and the restoration is one of the most important factors determining the success of a restoration.12,42 Additionally, effective adhesion between cavity walls and restorative materials is important for the longevity of restorations.38 For adhesive cementation of all-ceramic restorations, resin cements are the material of choice.7 The technique of adhesive cementation includes etching, priming, and cement application. This procedure requires attention to detail and is extremely technique sensitive.13 A new generation of proprietary self-adhesive resin cements has been introduced recently, designed to self-etch and bond to dentin without using separate etching or priming agents. Self-adhesive resin cements are designed to provide good bond strength, easy application with favorable mechanical properties, low incidence of postoperative sensitivity, good esthetics, and effective adhesion to tooth structure and restoration.8,18,32 They have provided similar or higher microleakage values compared to conventional resin luting cements.10 However, adhesive resin cements have been shown to provide different polymerization shrinkage values.21 Microleakage is defined as the diffusion of substances from the oral cavity, such as bacteria, fluids, molecules, or ions, to the space between tooth structure and the restorative material.11,24,39,41 Dye penetration and microscopic evaluation is a well-established method for in vitro microleakage testing,30 and has been used in several studies due to its simplicity and reproducibility.5,6 Although there are a number of studies on microleakage of ceramic inlays, more research is needed on the microleakage of different all-ceramic inlays cemented with selfadhesive resin cements. The purpose of the present study was therefore to evaluate the microleakage of different all-ceramic inlays bonded to tooth preparations with different self-adhesive resin cements. It was hypothesized that there would be a correlation between microleakage and fabrication method in inlays cemented with self-adhesive resin cement.
MATERIALS AND METHODS Standardized class III MOD cavities were prepared in 90 intact human mandibular third molars. Approval was granted by the Ankara University Faculty of Dentistry Eth524
ics Committee. Each group contained 10 specimens, in accordance with studies by Uludag et al42 and Romao et al.35 No power analysis was done before starting this study. After extraction, the teeth were cleaned using scalers to remove soft tissue remnants and stored in 0.5 % thymol (Merck; Darmstadt; Germany) at room temperature. The teeth were embedded up to 2 mm apical to the cementoenamel junction (CEJ) in an autopolymerizing resin (Palavit G, Heraeus Kulzer; Wehrheim; Germany). Standardized mesio-occluso-distal class III preparations were performed using diamond rotary cutting instruments (Inlay&Crown Preparation Kit 11312, Diatech, Coltene; Altstätten, Switzerland). The cavity preparations had 3-mm-high pulpal walls with a 4-mm isthmus, 10-degree axial wall convergence, and a flat cavity floor.15,42 The cervical margin of one of the proximal boxes was placed in enamel 1 mm above the CEJ.22,42 The opposite proximal box was extended 1 mm below the CEJ to place the cervical margin in dentin. The cavity borders were outlined using a 0.1-mm-tip rapidosketch technical pen (Rotring Isograph, Rotring; Hamburg, Germany). Cavity preparation geometry was controlled given the sketched outline, and cavity depths were controlled using a peridontal probe (15UNC, Hu-Friedy; Chicago, IL, USA). All internal angles were rounded. The prepared teeth were randomly assigned to three experimental groups corresponding to the three ceramic systems tested. Turkom-Cera is made of a high-alumina core, which is subsequently crystal hardened or glass infiltrated.43 IPS e.max Press (Ivoclar Vivadent) is in the form of lithium disilicate ceramic ingots that are heat pressed into an investment mold obtained by the lost-wax technique. Cerec 3 is a chairside CAD/CAM system, where the inlay is machined out of fine-grained feldspathic porcelains blocks (Vitablocks Mark II, Vita Zahnfabrik; Bad Säckingen, Germany). Impressions of all teeth were taken with one-step/two-viscosity polyether impression material (ImpregumPenta H DuoSoft and ImpregumGarant L DuoSoft, 3M ESPE; Seefeld, Germany), except for those restored with the Cerec 3 system. The impressions were poured with extra hard type IV die stone (Shera; Lemförde, Germany). In the Turkom-Cera group, die spacer was applied on the cavity walls without reaching the margins. Turkom-Cera alumina gel was applied to the stone die using the brush technique. After drying the alumina gel, the inlay was removed from the stone die and fired in the furnace (EP600, Ivoclar Vivadent) for 5 min at 1150°C. The sintered ceramic inlay was glass infiltrated using Turkom-Cera Crystal Powder. The Turkom-Cera crystal powder was mixed with water, applied on the sintered Turkom-Cera inlay, and fired in the same furnace for 30 min at 1150°C. The excess crystals were removed using diamond rotary cutting instruments at low speed and finally, the restorations were autoglazed. In the IPS e.max Press (Ivoclar Vivadent) group, an inlay pattern was waxed-up directly on the die, sprued, invested (IPS PressVEST, Ivoclar Vivadent), and placed in the furnace at 850°C for 45 min. After completion of the heating cycles, the investment ring with the cold ingot and the alumina plunger were transferred to the 700°C pre-heated pressThe Journal of Adhesive Dentistry
Uludag et al
Table 1
Median and mean rank values (Kruskall-Wallis H) for microleakage (n = 30) Median
Cements
Dentin
Enamel
Ceramics
Dentin
Enamel
Mean Rank
A: RelyX Unicem
1.35
26.4
B: Smartcem 2
4.58
59.6
C: SpeedCEM
3.5
48.4
A: RelyX Unicem
1.31
23.6
B: Smartcem 2
3.98
63
C: SpeedCEM
3.09
47.7
A: Cerec 3
2.47
36.4
B: IPS e.max Press
1.89
33.7
C: Turkom-Cera
4.94
64.5
A: Cerec 3
2.57
40.1
B: IPS e.max Press
1.92
37.8
C: Turkom-Cera
3.67
56.9
p
Binary comparisons
Purpose: To evaluate the microleakage of Cerec 3, IPS e.max Press, and Turkom-Cera inlays cemented with three self-adhesive resin cements. Materials and Methods: Ninety standardized class III MOD cavities were prepared in intact human mandibular third molars. Ceramic inlays were fabricated according to the manufacturer’s instructions and were cemented using three self-adhesive resin cements (RelyX Unicem, Smartcem 2, and SpeedCEM). The specimens were stored in distilled water at 37°C for 24 h and subjected to 1000 thermocycles in water between 5°C and 55°C with a dwell time of 30 s. Subsequently, the specimens were subjected to 100,000 cycles of mechanical loading of 50 N at 1.6 Hz in 37°C water. The specimens were immersed in 0.5% basic fuchsine for 24 h and were sectioned using a low-speed diamond blade. The percentage of dye leakage at the tooth/restoration interface was measured and compared by Kruskal-Wallis tests with Bonferonni correction and Mann-Whitney U-tests at a significance level of p < 0.05. Results: Microleakage at the RelyX Unicem interface was lower than that with Smartcem 2 and SpeedCEM resin cements (p < 0.05). Microleakage of the Turkom-Cera system was higher than Cerec 3 and IPS e.max Press ceramic inlays (p < 0.05). Conclusions: Regardless of the ceramic system and self-adhesive resin cement used, dentin margins were associated with higher microleakage than enamel margins. Keywords: microleakage, inlay ceramic systems, resin cements. J Adhes Dent 2014; 16: 523–529. doi: 10.3290/j.jad.a32811
O
wing to increasing demands for esthetic dental materials, remarkable improvements in tooth-colored inlay systems have been recently made as an alternative to silver amalgam alloys, especially in the posterior region.28 Although esthetic restorations in the posterior teeth are amongst the critical elements of state-of-theart dentistry, their use is not a necessity.23 During polymerization, composite restorative materials undergo significant volumetric shrinkage. This property leads to poor marginal quality in composite restorations.17,19,29 Because of the limitations of resin composites, such as wear, polymerization shrinkage, and high coefficients of thermal expansion, ceramic inlays have
a
Professor, Department of Prosthodontics, Faculty of Dentistry, Ankara, Turkey. Idea, hypothesis, experimental design.
b
Doctor, Adıyaman Dental Hospital, Adıyaman, Turkey. Performed the experiments, wrote the manuscript.
c
Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Kırıkkale University, Kırıkkale,Turkey. Co-wrote and proofread the manuscript.
Correspondence: Dr. Bulent Uludag, Ankara University, Faculty of Dentistry, Department of Prosthodontics, 06500, Besevler, Ankara, Turkey. Tel: +90312-296-5706, Fax: +90-312-123-954. e-mail: [email protected]
Vol 16, No 6, 2014
Submitted for publication: 01.12.13; accepted for publication: 06.08.14
been developed as an alternative to composite inlays.31 One of the advantages of the ceramic inlay technique is that the thermal expansion of the ceramic material is similar to that of the tooth substance and the polymerization shrinkage of the composite luting resin is reduced, thus improving marginal adaptation.9,42 However, treatment involving the use of ceramic inlays is burdened by marginal discoloration, postoperative sensitivity and recurrent caries associated with microleakage. Accordingly, different types of ceramic systems have been developed as an alternative to the powder-liquid systems to improve marginal adaptation. These new technologies include the use of computer designed restorations (CAD/CAM) and heat-pressed ceramics.20,35 The Cerec CAD/CAM system (Sirona; Bensheim, Germany) offers the opportunity to prepare, design, and fabricate a ceramic restoration in a single appointment, eliminating conventional impression taking, provisional restorations, and dental laboratory involvement.14,25,26,27 The Cerec procedure includes cavity preparation, optical impression of the actual or the prepared tooth on the master cast, the design and fabrication process, and adjustment and cementation of the restoration.44 A survival rate of 95% for bonded all-ceramic inlays up to 10 years has been documented using this technology.34 IPS e.max 523
Uludag et al
Press (Ivoclar Vivadent; Schaan, Liechtenstein) is a heatpressed, lithium disilicate-reinforced material made by the conventional “lost wax” technique.37 This material has been used for single- or three-unit restorations in the anterior region extending to the second premolar.40 Turkom-Cera (Turkom-Ceramic; Kuala Lumpur, Malaysia) has been introduced onto the market as a high-strength, cost-effective material to improve clinical success.2 Turkom-Cera has a high-alumina core, which can be easily crystal hardened or glass infiltrated.2,36 However, alumina cores tend to be opaque and require the use of veneering to mask the core and provide the desired contours.3,22 The microleakage of Turkom-Cera inlays has not been documented so far. Adhesion between the tooth structure and the restoration is one of the most important factors determining the success of a restoration.12,42 Additionally, effective adhesion between cavity walls and restorative materials is important for the longevity of restorations.38 For adhesive cementation of all-ceramic restorations, resin cements are the material of choice.7 The technique of adhesive cementation includes etching, priming, and cement application. This procedure requires attention to detail and is extremely technique sensitive.13 A new generation of proprietary self-adhesive resin cements has been introduced recently, designed to self-etch and bond to dentin without using separate etching or priming agents. Self-adhesive resin cements are designed to provide good bond strength, easy application with favorable mechanical properties, low incidence of postoperative sensitivity, good esthetics, and effective adhesion to tooth structure and restoration.8,18,32 They have provided similar or higher microleakage values compared to conventional resin luting cements.10 However, adhesive resin cements have been shown to provide different polymerization shrinkage values.21 Microleakage is defined as the diffusion of substances from the oral cavity, such as bacteria, fluids, molecules, or ions, to the space between tooth structure and the restorative material.11,24,39,41 Dye penetration and microscopic evaluation is a well-established method for in vitro microleakage testing,30 and has been used in several studies due to its simplicity and reproducibility.5,6 Although there are a number of studies on microleakage of ceramic inlays, more research is needed on the microleakage of different all-ceramic inlays cemented with selfadhesive resin cements. The purpose of the present study was therefore to evaluate the microleakage of different all-ceramic inlays bonded to tooth preparations with different self-adhesive resin cements. It was hypothesized that there would be a correlation between microleakage and fabrication method in inlays cemented with self-adhesive resin cement.
MATERIALS AND METHODS Standardized class III MOD cavities were prepared in 90 intact human mandibular third molars. Approval was granted by the Ankara University Faculty of Dentistry Eth524
ics Committee. Each group contained 10 specimens, in accordance with studies by Uludag et al42 and Romao et al.35 No power analysis was done before starting this study. After extraction, the teeth were cleaned using scalers to remove soft tissue remnants and stored in 0.5 % thymol (Merck; Darmstadt; Germany) at room temperature. The teeth were embedded up to 2 mm apical to the cementoenamel junction (CEJ) in an autopolymerizing resin (Palavit G, Heraeus Kulzer; Wehrheim; Germany). Standardized mesio-occluso-distal class III preparations were performed using diamond rotary cutting instruments (Inlay&Crown Preparation Kit 11312, Diatech, Coltene; Altstätten, Switzerland). The cavity preparations had 3-mm-high pulpal walls with a 4-mm isthmus, 10-degree axial wall convergence, and a flat cavity floor.15,42 The cervical margin of one of the proximal boxes was placed in enamel 1 mm above the CEJ.22,42 The opposite proximal box was extended 1 mm below the CEJ to place the cervical margin in dentin. The cavity borders were outlined using a 0.1-mm-tip rapidosketch technical pen (Rotring Isograph, Rotring; Hamburg, Germany). Cavity preparation geometry was controlled given the sketched outline, and cavity depths were controlled using a peridontal probe (15UNC, Hu-Friedy; Chicago, IL, USA). All internal angles were rounded. The prepared teeth were randomly assigned to three experimental groups corresponding to the three ceramic systems tested. Turkom-Cera is made of a high-alumina core, which is subsequently crystal hardened or glass infiltrated.43 IPS e.max Press (Ivoclar Vivadent) is in the form of lithium disilicate ceramic ingots that are heat pressed into an investment mold obtained by the lost-wax technique. Cerec 3 is a chairside CAD/CAM system, where the inlay is machined out of fine-grained feldspathic porcelains blocks (Vitablocks Mark II, Vita Zahnfabrik; Bad Säckingen, Germany). Impressions of all teeth were taken with one-step/two-viscosity polyether impression material (ImpregumPenta H DuoSoft and ImpregumGarant L DuoSoft, 3M ESPE; Seefeld, Germany), except for those restored with the Cerec 3 system. The impressions were poured with extra hard type IV die stone (Shera; Lemförde, Germany). In the Turkom-Cera group, die spacer was applied on the cavity walls without reaching the margins. Turkom-Cera alumina gel was applied to the stone die using the brush technique. After drying the alumina gel, the inlay was removed from the stone die and fired in the furnace (EP600, Ivoclar Vivadent) for 5 min at 1150°C. The sintered ceramic inlay was glass infiltrated using Turkom-Cera Crystal Powder. The Turkom-Cera crystal powder was mixed with water, applied on the sintered Turkom-Cera inlay, and fired in the same furnace for 30 min at 1150°C. The excess crystals were removed using diamond rotary cutting instruments at low speed and finally, the restorations were autoglazed. In the IPS e.max Press (Ivoclar Vivadent) group, an inlay pattern was waxed-up directly on the die, sprued, invested (IPS PressVEST, Ivoclar Vivadent), and placed in the furnace at 850°C for 45 min. After completion of the heating cycles, the investment ring with the cold ingot and the alumina plunger were transferred to the 700°C pre-heated pressThe Journal of Adhesive Dentistry
Uludag et al
Table 1
Median and mean rank values (Kruskall-Wallis H) for microleakage (n = 30) Median
Cements
Dentin
Enamel
Ceramics
Dentin
Enamel
Mean Rank
A: RelyX Unicem
1.35
26.4
B: Smartcem 2
4.58
59.6
C: SpeedCEM
3.5
48.4
A: RelyX Unicem
1.31
23.6
B: Smartcem 2
3.98
63
C: SpeedCEM
3.09
47.7
A: Cerec 3
2.47
36.4
B: IPS e.max Press
1.89
33.7
C: Turkom-Cera
4.94
64.5
A: Cerec 3
2.57
40.1
B: IPS e.max Press
1.92
37.8
C: Turkom-Cera
3.67
56.9
p
Binary comparisons
