Do surface treatments affect the optical properties of ceramic veneers? Sedanur Turgut, DDS, PhD,a Bora Ba gıs¸, DDS, PhD,b Fatih Mehmet Korkmaz, DDS, PhD,c and Evsen Tamam, DDS, PhDd Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey; Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey; Faculty of Dentistry, Gazi University, Ankara, Turkey Statement of problem. Surface treatments may affect the optical properties of ceramic veneers before cementation. Purpose. The purpose of this study was to evaluate whether various surface treatments affect the optical properties of different types of ceramic veneers. Material and methods. Disk-shaped ceramic veneers (N¼280) were prepared from the IPS e.max Press, e.max CAD, Empress Esthetic, e.max Ceram, and Inline ceramic systems with 0.5-mm and 1.0-mm thicknesses. The ceramics were divided into 4 groups: no surface treatments; etched with hydrofluoric acid; airborne-particle abraded with 30-mm Al2O3; and irradiated with erbium:yttrium-aluminum-garnet laser. A translucent shade of resin was chosen for cementation. Color parameters were examined with a colorimeter. Statistical analyses were done with 3-way ANOVA and the Bonferroni test (P¼.05). Results. Significant interactions were noted between the surface treatments, ceramic type, and thickness for DE values (P¼.01), and no significant interactions were noted for L* (P¼.773), a* (P¼.984), and b* (P¼.998). The greatest color change occurred after airborne-particle abrasion with 0.5-mm-thick e.max Press (2.9 DE). Significant differences in DE values were found among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 0.5-mm-thick ceramics, except IPS Inline, and among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 1.0-mm-thick ceramics, except Empress Esthetic ceramics. Conclusions. The color change of the ceramics increased after the surface treatments, particularly as the ceramics became thinner. (J Prosthet Dent 2014;-:---)
Clinical Implications Selecting the surface treatment methods of ceramic veneers before cementation is critical for optimal esthetics. Airborne-particle abrasion and laser treatments should be used more carefully, particularly when the restoration is thin. Esthetic ceramic veneers demonstrate excellent clinical performance, and as materials and techniques have evolved, veneers have become one of the most predictable, most esthetic, and least invasive treatment options.1 Because the success of these restorations depends primarily on adhesion, a a
durable bond between the restoration and the dental structure is crucial.2 Enhancing the bonding by modifying the internal surface of the ceramic optimizes the micromechanical retention of the resin into ceramic microroughness.3 The surface pretreatment of porcelain increases the surface area and
promotes surface microporosities.4 Different surface treatment methods, including airborne-particle abrasion (APA) with Al2O3, acid etching with hydrofluoric acid (HF), or combinations of these methods, have been proposed to provide roughness and promote micromechanical retention.5 APA with
Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Karadeniz Technical University. Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Izmir Katip Celebi University. c Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Karadeniz Technical University. d Research Assistant, Department of Prosthodontics, Faculty of Dentistry, Gazi University. b
Turgut et al
2
Volume alumina particles and the application of a tribochemical silica coating allow for chemical bonding to a silane coupling agent and resin. HF attacks the glass phase, producing a retentive surface for micromechanical bonding by increasing the crystalline content and decreasing the glass content.6 Laser irradiation has become popular for the surface treatment of ceramic materials. Many advances in surface modification have been made by using lasers to form a glazed surface on the ceramic, etch the ceramic intaglio, or remove ceramic veneers.7-12 However, little information is available concerning the effect of lasers on restorative materials and whether the penetrated Al2O3 particles or the changes in the glass content of the ceramics affect the physical properties of the esthetic ceramic veneers. Ceramic veneers can be fabricated from feldspathic ceramics, lithium disilicate glass ceramics, or leucite glass ceramics. Lithium disilicate and leucite glass ceramics have good flexural strength and fracture toughness; additionally, they are translucent and esthetically pleasing.13,14 Different ceramic microstructures significantly influence the ceramic resin adhesion zone.15 Studies have investigated the effect of different surface treatments, including acid etching, APA, and laser, on the roughness12 and bond strength6-11 of ceramics. The results of these studies have shown that the surface treatments significantly affected the bond strength and roughness of the ceramics.16-19 However, as the roughness of the ceramics changed, some differences were observed in the optical properties of these esthetic restorations. Optical characteristics of a ceramic veneer restoration depend on the surface texture, color, or thickness of the ceramic.20 However, knowledge is lacking on the effects of HF etching, APA, or laser treatments on the optical properties of ceramics. The purposes of this study, therefore, were to assess whether different surface treatments affect the optical properties of ceramic veneers and to evaluate whether different types of ceramic
veneers with different thicknesses are affected differently by the surface treatments. The null hypotheses were that no differences would be found in the optical properties of ceramic veneers after the surface treatments; that the surface treatments would not differentially affect the optical properties of the veneer ceramics prepared with various ceramic types; and that the surface treatments would not differentially affect the optical properties of the ceramic veneers of various thicknesses.
MATERIAL AND METHODS A total of 280 disk-shaped specimens of shade A1 were prepared from the IPS e.max Press, IPS e.max CAD, IPS Empress Esthetic, IPS e.max Ceram, and IPS Inline ceramic systems (Table I). The IPS e.max Press and IPS Empress Esthetic specimens were prepared by eliminating a 0.5mm or 1-mm thickness of wax with a diameter of 10 mm. The specimens were then heat-pressed (EP 600 press furnace; Ivoclar Vivadent) according to the manufacturer’s directions. The IPS e.max Ceram and IPS Inline specimens were made by mixing ceramic powder with distilled water and then firing according to the manufacturer’s directions. The IPS e.max Ceram and IPS Inline specimens were made by mixing ceramic powder with distilled water condensed into the silicone mold with an ultrasonic condenser. The IPS e.max CAD specimens were prepared from IPS e.max CAD ingots by using a slow-speed diamond saw (IsoMet; Buehler) under a constant flow of water. All specimens were finished flat on a grinder/polisher with wet 400- to 1200-grit silicon carbide paper, and the
Table I.
Issue
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thicknesses of the specimens were standardized (diameter, 10 mm; thickness, 0.5 0.05 and 1.0 0.05 mm). Digital calipers (Electronic Digital Caliper; Shan) were used to measure the thicknesses, and the specimens were ultrasonically cleaned in distilled water for 10 minutes. The specimens were coated on 1 side with a layer of neutral-shade glaze and fired at 765 C. The specimens were ultrasonically cleaned in distilled water for 10 minutes before the surface treatment procedures. Thereafter, the ceramic disks for each ceramic system were divided into 4 groups (n¼7). In the control group, no surface treatments were applied on the ceramic surfaces. In the HF group, the bonding surfaces of ceramic disks were etched with 5% HF (IPS Ceramic Etching Gel; Ivoclar Vivadent) for 20 seconds. The gel was rinsed with water for 20 seconds and then dried with oil-free compressed air. In the APA group, the ceramic surfaces were abraded with 30-mm Al2O3 particles (CoJet; 3M ESPE) at a pressure of 280 kPa and a distance of 10 mm (perpendicular to the treated surface) for 20 seconds by the same operator. In the laser group, an erbium:yttriumaluminum-garnet (Er:YAG) laser (Fotona d.d.) was used for laser irradiation. The laser optical fiber (1.3 mm in diameter) was aligned perpendicular to the ceramic surface at a distance of 1 mm, and the whole ceramic area was scanned. The following laser parameters were used: 500 mJ (pulse energy), 20 Hz (pulse per second), 10 W (power setting), 37.86 J/ cm2 (energy density), and 150 ms (pulse length). The laser irradiation was performed by the same operator for all specimens.
Ceramic systems used
Material
Manufacturer
Material Type
IPS e.max Press
Ivoclar Vivadent
Lithium disilicate
IPS Empress Esthetic IPS e.max Ceram IPS Inline IPS e.max CAD
The Journal of Prosthetic Dentistry
-
Technique Pressing
Leucite
Pressing
Nano-fluorapatite
Layering
Leucite
Layering
Lithium disilicate
Machining
Turgut et al
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2014
After the surface treatments of the ceramic groups, the specimens were ultrasonically cleaned in distilled water for 5 minutes. A silane coupling agent was applied to the ceramic surfaces with a clean brush, and the specimens were air-dried. A ceramic primer (RelyX Ceramic Primer; 3M ESPE) was applied for 5 seconds and air-dried. For all groups, a translucent shade of resin (RelyX Veneer; 3M ESPE) was chosen for cementation. Resins were applied directly from a syringe to the unglazed surface of the ceramics. A clean glass slide was placed onto the resin mixture, and a 9.8-N load was placed on top for 20 seconds to form a 0.1-mm-thick resin layer. Then, to simulate clinical conditions, a polymerization light was applied to the ceramic surfaces (Elipar FreeLight 2; 3M ESPE) for 40 seconds. After cementation, irregularities from excessive resin were adjusted with 600grit wet silicon carbide paper, and the specimen thickness was calibrated again and standardized at 0.6 mm for all specimens. The color was measured with a tristimulus colorimeter (ShadeEye NCC; Shofu) in a viewing booth under D65 standard illumination on a white background (based on the ISO 7491 standard). Before the experimental measurements, the colorimeter was calibrated according to the manufacturer’s instructions and positioned in the center of each specimen. The specimen was measured consecutively 3 times, and the average of the 3 readings was calculated to give the initial color of the specimen. The Commission Internationale de l’Eclairage (CIE) system made it possible to evaluate the degree of perceptible color change (DE) based on the parameters L*, a*, and b*.21-25 L* (lightness, brightness, or value) represents the lightness/darkness of a color; a* is a measure of redness (positive) or greenness (negative); and b* is a measure of yellowness (positive) or blueness (negative).24-28 The color differences between the control and the other groups were calculated from the following formula: DE* ¼ [(DL*)2 þ (Da*)2 þ (Db*)2]1/2.
Turgut et al
3 The color differences were analyzed with a 3-way ANOVA with factors of surface treatment, ceramic type, and thickness and with interactions for the L*, a*, b*, and DE values. To adjust for multiple comparisons, the Bonferroni test was used (a¼.05).
RESULTS The mean L*, a*, b*, and DE* values and the SDs of the 5 ceramic groups are shown in Tables II-IX. The 3-way ANOVA (Tables X-XIII) indicated significant interactions between the surface treatments, ceramic type, and thickness for
Table II. Material
DE values (P¼.01) and no significant interactions for L* (P¼.773), a* (P¼.984), and b* (P¼.998). For the 0.5-mm-thick specimens, significant differences were noted in the DE values among the HF, APA, and laser treatments for the ceramic specimens (P.05).
Table IV.
Values of b* for 0.5-mm ceramics
Material
Control
Laser
Airborne-Particle Abrasion
Ceram
6.8(0.3)(x)
8.1(0.2)(y)
8.3(0.4)(y)
6.7(0.5)(x)
Esthetics
5.5(0.7)(x)
6.4(0.7)(y)
7.4(0.7)(y)
5.5(0.7)(x)
Press
9.9(1.4)(x)
11(1.3)(y)
11.9(1.2)(y)
9.6(1.4)(x)
Inline
8.2(0.6)(x)
9.1(0.6)(y)
9.7(0.7)(y)
8.1(0.5)(x)
CAD
9.5(1.1)
(x)
11.1(1.3)
(y)
11.8(1.2)
Hydrofluoric Acid Etching
(y)
Same superscript letters in same row indicate no significant differences (P>.05).
9.4(1.3)(x)
4
Volume
Table V.
Values of DE for 0.5-mm ceramics
Laser
Airborne-Particle Abrasion
Ceram
1.9(0.1)(y)
1.9(0.1)(z)
0.3(0.1)(x)
Esthetics
2.4(0.2)(y)
3(0.1)(z)
0.3(0.1)(x)
Press
2.5(0.1)(y)
2.9(0.1)(z)
0.3(0.1)(x)
Inline
2.2(0.2)
(y)
(y)
0.2(0.1)(x)
CAD
2.5(0.1)(y)
2.8(0.2)(z)
0.2(0.9)(x)
Material
1.9(0.1)
Hydrofluoric Acid Etching
Same superscript letters in same row indicate no significant differences (P>.05).
Table VI.
Values of L* for 1-mm ceramics
Material
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Control
Laser
Ceram
85.9(0.9)(x)
87.2(0.8)(y)
86.3(0.8)(y)
85.7(0.9)(x)
Esthetics
84.4(0.6)(x)
85.9(0.5)(y)
85.8(0.7)(y)
84.2(0.6)(x)
(x)
(y)
(y)
86.2(0.6)(x)
Press
86.4(0.6)
88.7(0.8)
87.2(0.6)
Inline
85.2(0.6)(x)
86.5(0.8)(y)
86.1(0.6)(y)
85.1(0.8)(x)
CAD
87.2(0.5)(x)
88.7(0.2)(y)
88(0.4)(y)
86.9(0.8)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table VII.
Values of a* for 1-mm ceramics
Material
Control
Laser
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Ceram
0.7(0.2)(x) 0.6(0.1)(x)
0.6(0.1)(x)
0.7(0.1)(x)
Esthetics
0.6(0.1)(x) 0.6(0.2)(x)
0.4(0.2)(x)
0.6(0.1)(x)
Press
1.9(0.2)(x) 1.9(0.2)(x)
1.8(0.1)(x)
1.8(0.2)(x)
Inline
1.1(0.2)(x) 1.1(0.2)(x)
0.9(0.2)(x)
1.1(0.3)(x)
CAD
1.8(0.3)(x) 1.7(0.2)(x)
1.6(0.1)(x)
1.7(0.2)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table VIII. Material
Values of b* for 1-mm ceramics
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Control
Laser
Ceram
15.8(0.5)(x)
16.5(0.5)(x)
17.3(0.6)(x)
15.6(0.6)(x)
Esthetics
7.4(0.7)(x)
8.5(0.7)(y)
10(0.7)(y)
7(0.7)(x)
Press
12.9(0.4)(x)
13.8(1.4)(y)
14.6(1.3)(y)
12.8(1.3)(x)
Inline
11.2(0.7)(x)
11.9(0.9)(x)
12.1(0.6)(x)
11(0.4)(x)
CAD
12.9(0.8)
(x)
14(0.9)
(y)
14.8(0.6)
(y)
12.6(0.6)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
(P¼.019). The greatest color change occurred after APA treatment with 0.5mm-thick e.max Press (2.92 DE)
ceramics, and the least color change occurred after HF treatment of 1.0-mmthick Inline ceramics (0.2 DE).
The Journal of Prosthetic Dentistry
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No significant differences were found in the L*, a*, or b* values of ceramics between the control and HFtreated groups (P>.05). For the L* values of the ceramic groups, significant differences were found after the APA and laser treatments for the 0.5-mm and 1.0-mm thicknesses (P.05). For the b* values of the ceramics after the APA treatment, significant differences were found for the 0.5-mm and 1.0-mm thicknesses. Laser treatment had a significant effect on all 0.5-mm-thick ceramics, except for the 1.0-mm-thick IPS Ceram (P¼.57) and IPS Inline (P¼.83).
DISCUSSION The first null hypothesis of the present study was rejected: significant differences were found between the optical properties of ceramic veneers after APA or laser treatment, although HF etching did not affect the optical properties of the ceramic veneers. The second null hypothesis was rejected: the surface treatments differentially affected the optical properties of the ceramic veneers prepared with various ceramic types. The third null hypothesis was also rejected: the surface treatments differentially affected the ceramic veneers of various thicknesses. After the HF etching procedures, the glassy matrix of the ceramic was selectively removed. The crystalline structures were exposed, and the etched porcelain surfaces showed an amorphous microstructure with numerous porosities.14 However, these changes did not affect the optical properties of the ceramics.
Turgut et al
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2014
Table IX.
5 Values of DE* for 1-mm ceramics
Laser
Airborne-Particle Abrasion
Ceram
1.5(0.3)(y)
1.5(0.2)(y)
0.2(0.2)(x)
Esthetics
1.8(0.18)(y)
2.1(0.1)(z)
0.3(0.1)(x)
Press
1.9(0.1)(y)
2(0.2)(y)
0.2(0.4)(x)
Inline
1.9(0.2)
(y)
CAD
2.2(0.1)(y)
Material
1.9(0.2)
Hydrofluoric Acid Etching
(y)
0.2(0.2)(x)
2(0.2)(y)
0.2(0.1)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table X.
Results of 3-way ANOVA for L* values
Type III Sum of Squares
Corrected model Intercept
Source
df
Mean Square
F
3276.129(a)
39
84.003
148.466
Clinical Implications Selecting the surface treatment methods of ceramic veneers before cementation is critical for optimal esthetics. Airborne-particle abrasion and laser treatments should be used more carefully, particularly when the restoration is thin. Esthetic ceramic veneers demonstrate excellent clinical performance, and as materials and techniques have evolved, veneers have become one of the most predictable, most esthetic, and least invasive treatment options.1 Because the success of these restorations depends primarily on adhesion, a a
durable bond between the restoration and the dental structure is crucial.2 Enhancing the bonding by modifying the internal surface of the ceramic optimizes the micromechanical retention of the resin into ceramic microroughness.3 The surface pretreatment of porcelain increases the surface area and
promotes surface microporosities.4 Different surface treatment methods, including airborne-particle abrasion (APA) with Al2O3, acid etching with hydrofluoric acid (HF), or combinations of these methods, have been proposed to provide roughness and promote micromechanical retention.5 APA with
Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Karadeniz Technical University. Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Izmir Katip Celebi University. c Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Karadeniz Technical University. d Research Assistant, Department of Prosthodontics, Faculty of Dentistry, Gazi University. b
Turgut et al
2
Volume alumina particles and the application of a tribochemical silica coating allow for chemical bonding to a silane coupling agent and resin. HF attacks the glass phase, producing a retentive surface for micromechanical bonding by increasing the crystalline content and decreasing the glass content.6 Laser irradiation has become popular for the surface treatment of ceramic materials. Many advances in surface modification have been made by using lasers to form a glazed surface on the ceramic, etch the ceramic intaglio, or remove ceramic veneers.7-12 However, little information is available concerning the effect of lasers on restorative materials and whether the penetrated Al2O3 particles or the changes in the glass content of the ceramics affect the physical properties of the esthetic ceramic veneers. Ceramic veneers can be fabricated from feldspathic ceramics, lithium disilicate glass ceramics, or leucite glass ceramics. Lithium disilicate and leucite glass ceramics have good flexural strength and fracture toughness; additionally, they are translucent and esthetically pleasing.13,14 Different ceramic microstructures significantly influence the ceramic resin adhesion zone.15 Studies have investigated the effect of different surface treatments, including acid etching, APA, and laser, on the roughness12 and bond strength6-11 of ceramics. The results of these studies have shown that the surface treatments significantly affected the bond strength and roughness of the ceramics.16-19 However, as the roughness of the ceramics changed, some differences were observed in the optical properties of these esthetic restorations. Optical characteristics of a ceramic veneer restoration depend on the surface texture, color, or thickness of the ceramic.20 However, knowledge is lacking on the effects of HF etching, APA, or laser treatments on the optical properties of ceramics. The purposes of this study, therefore, were to assess whether different surface treatments affect the optical properties of ceramic veneers and to evaluate whether different types of ceramic
veneers with different thicknesses are affected differently by the surface treatments. The null hypotheses were that no differences would be found in the optical properties of ceramic veneers after the surface treatments; that the surface treatments would not differentially affect the optical properties of the veneer ceramics prepared with various ceramic types; and that the surface treatments would not differentially affect the optical properties of the ceramic veneers of various thicknesses.
MATERIAL AND METHODS A total of 280 disk-shaped specimens of shade A1 were prepared from the IPS e.max Press, IPS e.max CAD, IPS Empress Esthetic, IPS e.max Ceram, and IPS Inline ceramic systems (Table I). The IPS e.max Press and IPS Empress Esthetic specimens were prepared by eliminating a 0.5mm or 1-mm thickness of wax with a diameter of 10 mm. The specimens were then heat-pressed (EP 600 press furnace; Ivoclar Vivadent) according to the manufacturer’s directions. The IPS e.max Ceram and IPS Inline specimens were made by mixing ceramic powder with distilled water and then firing according to the manufacturer’s directions. The IPS e.max Ceram and IPS Inline specimens were made by mixing ceramic powder with distilled water condensed into the silicone mold with an ultrasonic condenser. The IPS e.max CAD specimens were prepared from IPS e.max CAD ingots by using a slow-speed diamond saw (IsoMet; Buehler) under a constant flow of water. All specimens were finished flat on a grinder/polisher with wet 400- to 1200-grit silicon carbide paper, and the
Table I.
Issue
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thicknesses of the specimens were standardized (diameter, 10 mm; thickness, 0.5 0.05 and 1.0 0.05 mm). Digital calipers (Electronic Digital Caliper; Shan) were used to measure the thicknesses, and the specimens were ultrasonically cleaned in distilled water for 10 minutes. The specimens were coated on 1 side with a layer of neutral-shade glaze and fired at 765 C. The specimens were ultrasonically cleaned in distilled water for 10 minutes before the surface treatment procedures. Thereafter, the ceramic disks for each ceramic system were divided into 4 groups (n¼7). In the control group, no surface treatments were applied on the ceramic surfaces. In the HF group, the bonding surfaces of ceramic disks were etched with 5% HF (IPS Ceramic Etching Gel; Ivoclar Vivadent) for 20 seconds. The gel was rinsed with water for 20 seconds and then dried with oil-free compressed air. In the APA group, the ceramic surfaces were abraded with 30-mm Al2O3 particles (CoJet; 3M ESPE) at a pressure of 280 kPa and a distance of 10 mm (perpendicular to the treated surface) for 20 seconds by the same operator. In the laser group, an erbium:yttriumaluminum-garnet (Er:YAG) laser (Fotona d.d.) was used for laser irradiation. The laser optical fiber (1.3 mm in diameter) was aligned perpendicular to the ceramic surface at a distance of 1 mm, and the whole ceramic area was scanned. The following laser parameters were used: 500 mJ (pulse energy), 20 Hz (pulse per second), 10 W (power setting), 37.86 J/ cm2 (energy density), and 150 ms (pulse length). The laser irradiation was performed by the same operator for all specimens.
Ceramic systems used
Material
Manufacturer
Material Type
IPS e.max Press
Ivoclar Vivadent
Lithium disilicate
IPS Empress Esthetic IPS e.max Ceram IPS Inline IPS e.max CAD
The Journal of Prosthetic Dentistry
-
Technique Pressing
Leucite
Pressing
Nano-fluorapatite
Layering
Leucite
Layering
Lithium disilicate
Machining
Turgut et al
-
2014
After the surface treatments of the ceramic groups, the specimens were ultrasonically cleaned in distilled water for 5 minutes. A silane coupling agent was applied to the ceramic surfaces with a clean brush, and the specimens were air-dried. A ceramic primer (RelyX Ceramic Primer; 3M ESPE) was applied for 5 seconds and air-dried. For all groups, a translucent shade of resin (RelyX Veneer; 3M ESPE) was chosen for cementation. Resins were applied directly from a syringe to the unglazed surface of the ceramics. A clean glass slide was placed onto the resin mixture, and a 9.8-N load was placed on top for 20 seconds to form a 0.1-mm-thick resin layer. Then, to simulate clinical conditions, a polymerization light was applied to the ceramic surfaces (Elipar FreeLight 2; 3M ESPE) for 40 seconds. After cementation, irregularities from excessive resin were adjusted with 600grit wet silicon carbide paper, and the specimen thickness was calibrated again and standardized at 0.6 mm for all specimens. The color was measured with a tristimulus colorimeter (ShadeEye NCC; Shofu) in a viewing booth under D65 standard illumination on a white background (based on the ISO 7491 standard). Before the experimental measurements, the colorimeter was calibrated according to the manufacturer’s instructions and positioned in the center of each specimen. The specimen was measured consecutively 3 times, and the average of the 3 readings was calculated to give the initial color of the specimen. The Commission Internationale de l’Eclairage (CIE) system made it possible to evaluate the degree of perceptible color change (DE) based on the parameters L*, a*, and b*.21-25 L* (lightness, brightness, or value) represents the lightness/darkness of a color; a* is a measure of redness (positive) or greenness (negative); and b* is a measure of yellowness (positive) or blueness (negative).24-28 The color differences between the control and the other groups were calculated from the following formula: DE* ¼ [(DL*)2 þ (Da*)2 þ (Db*)2]1/2.
Turgut et al
3 The color differences were analyzed with a 3-way ANOVA with factors of surface treatment, ceramic type, and thickness and with interactions for the L*, a*, b*, and DE values. To adjust for multiple comparisons, the Bonferroni test was used (a¼.05).
RESULTS The mean L*, a*, b*, and DE* values and the SDs of the 5 ceramic groups are shown in Tables II-IX. The 3-way ANOVA (Tables X-XIII) indicated significant interactions between the surface treatments, ceramic type, and thickness for
Table II. Material
DE values (P¼.01) and no significant interactions for L* (P¼.773), a* (P¼.984), and b* (P¼.998). For the 0.5-mm-thick specimens, significant differences were noted in the DE values among the HF, APA, and laser treatments for the ceramic specimens (P.05).
Table IV.
Values of b* for 0.5-mm ceramics
Material
Control
Laser
Airborne-Particle Abrasion
Ceram
6.8(0.3)(x)
8.1(0.2)(y)
8.3(0.4)(y)
6.7(0.5)(x)
Esthetics
5.5(0.7)(x)
6.4(0.7)(y)
7.4(0.7)(y)
5.5(0.7)(x)
Press
9.9(1.4)(x)
11(1.3)(y)
11.9(1.2)(y)
9.6(1.4)(x)
Inline
8.2(0.6)(x)
9.1(0.6)(y)
9.7(0.7)(y)
8.1(0.5)(x)
CAD
9.5(1.1)
(x)
11.1(1.3)
(y)
11.8(1.2)
Hydrofluoric Acid Etching
(y)
Same superscript letters in same row indicate no significant differences (P>.05).
9.4(1.3)(x)
4
Volume
Table V.
Values of DE for 0.5-mm ceramics
Laser
Airborne-Particle Abrasion
Ceram
1.9(0.1)(y)
1.9(0.1)(z)
0.3(0.1)(x)
Esthetics
2.4(0.2)(y)
3(0.1)(z)
0.3(0.1)(x)
Press
2.5(0.1)(y)
2.9(0.1)(z)
0.3(0.1)(x)
Inline
2.2(0.2)
(y)
(y)
0.2(0.1)(x)
CAD
2.5(0.1)(y)
2.8(0.2)(z)
0.2(0.9)(x)
Material
1.9(0.1)
Hydrofluoric Acid Etching
Same superscript letters in same row indicate no significant differences (P>.05).
Table VI.
Values of L* for 1-mm ceramics
Material
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Control
Laser
Ceram
85.9(0.9)(x)
87.2(0.8)(y)
86.3(0.8)(y)
85.7(0.9)(x)
Esthetics
84.4(0.6)(x)
85.9(0.5)(y)
85.8(0.7)(y)
84.2(0.6)(x)
(x)
(y)
(y)
86.2(0.6)(x)
Press
86.4(0.6)
88.7(0.8)
87.2(0.6)
Inline
85.2(0.6)(x)
86.5(0.8)(y)
86.1(0.6)(y)
85.1(0.8)(x)
CAD
87.2(0.5)(x)
88.7(0.2)(y)
88(0.4)(y)
86.9(0.8)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table VII.
Values of a* for 1-mm ceramics
Material
Control
Laser
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Ceram
0.7(0.2)(x) 0.6(0.1)(x)
0.6(0.1)(x)
0.7(0.1)(x)
Esthetics
0.6(0.1)(x) 0.6(0.2)(x)
0.4(0.2)(x)
0.6(0.1)(x)
Press
1.9(0.2)(x) 1.9(0.2)(x)
1.8(0.1)(x)
1.8(0.2)(x)
Inline
1.1(0.2)(x) 1.1(0.2)(x)
0.9(0.2)(x)
1.1(0.3)(x)
CAD
1.8(0.3)(x) 1.7(0.2)(x)
1.6(0.1)(x)
1.7(0.2)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table VIII. Material
Values of b* for 1-mm ceramics
Airborne-Particle Hydrofluoric Acid Abrasion Etching
Control
Laser
Ceram
15.8(0.5)(x)
16.5(0.5)(x)
17.3(0.6)(x)
15.6(0.6)(x)
Esthetics
7.4(0.7)(x)
8.5(0.7)(y)
10(0.7)(y)
7(0.7)(x)
Press
12.9(0.4)(x)
13.8(1.4)(y)
14.6(1.3)(y)
12.8(1.3)(x)
Inline
11.2(0.7)(x)
11.9(0.9)(x)
12.1(0.6)(x)
11(0.4)(x)
CAD
12.9(0.8)
(x)
14(0.9)
(y)
14.8(0.6)
(y)
12.6(0.6)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
(P¼.019). The greatest color change occurred after APA treatment with 0.5mm-thick e.max Press (2.92 DE)
ceramics, and the least color change occurred after HF treatment of 1.0-mmthick Inline ceramics (0.2 DE).
The Journal of Prosthetic Dentistry
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Issue
-
No significant differences were found in the L*, a*, or b* values of ceramics between the control and HFtreated groups (P>.05). For the L* values of the ceramic groups, significant differences were found after the APA and laser treatments for the 0.5-mm and 1.0-mm thicknesses (P.05). For the b* values of the ceramics after the APA treatment, significant differences were found for the 0.5-mm and 1.0-mm thicknesses. Laser treatment had a significant effect on all 0.5-mm-thick ceramics, except for the 1.0-mm-thick IPS Ceram (P¼.57) and IPS Inline (P¼.83).
DISCUSSION The first null hypothesis of the present study was rejected: significant differences were found between the optical properties of ceramic veneers after APA or laser treatment, although HF etching did not affect the optical properties of the ceramic veneers. The second null hypothesis was rejected: the surface treatments differentially affected the optical properties of the ceramic veneers prepared with various ceramic types. The third null hypothesis was also rejected: the surface treatments differentially affected the ceramic veneers of various thicknesses. After the HF etching procedures, the glassy matrix of the ceramic was selectively removed. The crystalline structures were exposed, and the etched porcelain surfaces showed an amorphous microstructure with numerous porosities.14 However, these changes did not affect the optical properties of the ceramics.
Turgut et al
-
2014
Table IX.
5 Values of DE* for 1-mm ceramics
Laser
Airborne-Particle Abrasion
Ceram
1.5(0.3)(y)
1.5(0.2)(y)
0.2(0.2)(x)
Esthetics
1.8(0.18)(y)
2.1(0.1)(z)
0.3(0.1)(x)
Press
1.9(0.1)(y)
2(0.2)(y)
0.2(0.4)(x)
Inline
1.9(0.2)
(y)
CAD
2.2(0.1)(y)
Material
1.9(0.2)
Hydrofluoric Acid Etching
(y)
0.2(0.2)(x)
2(0.2)(y)
0.2(0.1)(x)
Same superscript letters in same row indicate no significant differences (P>.05).
Table X.
Results of 3-way ANOVA for L* values
Type III Sum of Squares
Corrected model Intercept
Source
df
Mean Square
F
3276.129(a)
39
84.003
148.466
