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Evaluation of the effect of different polishing systems on the surface roughness of dental ceramics
RESEARCH AND EDUCATION
Evaluation of the effect of different polishing systems on the surface roughness of dental ceramics Esra Incesu, DDS, PhDa and Nuran Yanikoglu, DDS, PhDb As restorations with smooth ABSTRACT surfaces are important for both Statement of problem. How the finishing and polishing of ceramic restorations may affect their oral health and esthetics, the surface properties is unclear. effect of polishing and glazing Purpose. The purpose of this in vitro study was to evaluate the effect of different polishing systems on the surface of dental ceon the surface roughness of dental ceramics by using a profilometer, an environmental scanning 1-6 ramics has been evaluated. electron microscope (ESEM), and an atomic force microscope (AFM). The objective of finishing and Material and methods. Sixty square specimens (2×14×14 mm) of 3 popular ceramic systems glazing is to obtain an accept(monolithic zirconia and feldspathic-based ceramic containing feldspar and fluorapatite) were able contour and occlusion, a prepared, glazed, and assigned to 1 of the 5 groups: a control group with no additional healthy embrasure, and a treatment after the glaze; in the other groups, the glaze layer was removed, and the surfaces 7 smooth surface. A direct were polished by using 4 different ceramic polishing systems (OptraFine, Shofu, Meisinger, or relationship exists between Komet). The surface roughness was evaluated numerically by using a profilometer and visually surface roughness and plaque by using an ESEM and an AFM. The data were interpreted by using 2-way ANOVA. A multiple comparison of averages was conducted by using the Tukey HSD (a=.05). accumulation, discoloration of the restoration, and esthetics.8 Results. The smoothest surface was obtained in the glazed group polished with the OptraFine kit, When roughness increases, with no statistically significant difference (P=.95). The other groups showed a significant difference the wear of opposing enamel from the glazed one (P<.05); however, the difference among the other groups was not significantly different (P=.59). increases, as does restoration discoloration,9-12 staining, and Conclusions. After the adjustment of dental ceramics and upon removal of the glaze, the OptraFine plaque and calculus formapolishing kit and paste application can be used as an alternative to glazing for the 3 ceramic types tested. It was not possible to adequately polish the ceramic surface by using the Komet polishing tion.9,11 The surface roughness kit. (J Prosthet Dent 2019;-:---) of restorative materials should be minimized to eliminate these unfavorable occurrences and to optimize esthetics performed in successive steps.7 Different polishing kits 10 and oral health. are marketed with the purpose of eliminating irregularities and achieving smooth surfaces.10,12,19,20 InAfter the cementation of restorations, occlusal or contour adjustment may be needed. These adjustments struments, including tungsten carbide finishing burs, are usually made with diamond rotary instruments that diamond rotary instruments, silicone rubber disks, and remove the glazed surface and increase the surface silicon carbide or aluminum oxideecoated abrasive disks, roughness.11,13-16 A poorly finished restoration causes are used to finish restoration surfaces.21 Polishing enbiofilm accumulation and growth.17,18 To resmooth hances structural resistance and helps regain restoration gloss.10,22,23 roughened restorative surfaces, finishing and polishing is
Supported by the Atatürk University Coordination Office for Scientific Research Project (grant 2016/101). a Graduate Prosthodontist, Department of Prosthetic Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey. b Professor, Department of Prosthetic Dentistry, Faculty of Dentistry, University of Atatürk, Erzurum, Turkey.
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Clinical Implications After the adjustment and polishing of ceramic restorations, an acceptable surface smoothness can be produced with the appropriate polishing system and technique.
The roughness of adjusted surfaces can be reduced by polishing, but the result has been reported to be not as smooth as a glazed surface.24-26 However, Brewer et al27 reported that after a second firing to reglaze polished crowns, the restoration lacked an esthetic matt appearance. A surface profilometer is an appropriate instrument used for the quantitative evaluation of surface roughness.28,29 However, sometimes roughness values do not accurately represent the topography of ceramic surfaces because only a certain part of the surface is examined by using the profilometer.30 For this reason, examination with a scanning electron microscope (SEM) has been advocated for more extensive analysis.31 The environmental scanning electron microscope (ESEM) may be more suitable than the SEM as it provides electron microscope images without the need to coat the specimens with metal. In addition, the ESEM can be used to image wet or isolated specimens without prior preparation.32 Examination with an atomic force microscope (AFM) provides increased resolution and 3-dimensional display and also more details compared with a profilometer or visual evaluation.10,33 Ceramic polishing kits have been evaluated to determine whether a surface can be restored to the glazed surface before adjustment23,34-37; however, detailed evaluations with ESEM and AFM are lacking. The purpose of this in vitro study was to evaluate the surface smoothness of different ceramic systems after treatment with different polishing kits and to investigate their effectiveness. The null hypothesis was that no difference in surface roughness would be found among the polishing systems tested. MATERIAL AND METHODS Twenty specimens (14×14×2 mm) for each ceramic material type (IPS e.max Ceram; Ivoclar Vivadent AG, VITA VM9; VITA Zahnfabrik, and Lava Plus Zirconia; 3M ESPE) were produced following the manufacturer’s instructions. Custom molds were used in the preparation of IPS e.max Ceram and VITA VM9 ceramic specimens. As suggested by the manufacturer, powder and liquid were mixed at the specified ratio in a glass container until homogeneous and then loaded into the mold with a layering technique. Excess surface liquid was removed with an absorbent paper,1 and the mold was vibrated to
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reduce porosity. The specimens were sintered in a porcelain furnace (EP 600; Ivoclar Vivadent AG) according to the manufacturer’s recommendations. The zirconia specimens were milled with a computer-aided design and computer-aided manufacturing (CAD-CAM) system from disks (Lava Plus Zirconia; 3M ESPE). The specimens were sintered in a furnace (ELV MoS 160/1; Protherm Furnaces) for 8 hours at 1550 C. To ensure standardization, all specimens were abraded with a grinding machine (Phoenix Beta Grinder/ Polisher; Buehler) at a constant speed of 300 rpm with 320-, 400-, 600-, and 1200-grit silicon carbide papers for 20 seconds with water cooling.38 The thickness of the specimens was measured with digital calipers (Absolute Digimatic Caliper; Mitutoyo Corp). The specimen dimensions were based on those of previous studies.10,23,34,39-42 They were then cleaned with 99% alcohol for 3 minutes with an ultrasonic cleaner (Sonorex RK102 Transistor; Bandelin). One investigator (E.I.) applied a homogeneous thin layer of glaze paste and liquid prepared on a glass plate to each surface of the specimens. Glaze powders and liquids (VITA Akzent; VITA Zahnfabrik, IPS e.max Ceram Glaze; Ivoclar Vivadent AG, and Cercon Ceram; DeguDent GmbH) were used for the corresponding specimens, which was performed in a conventional porcelain furnace (Programat P300; Ivoclar Vivadent AG) with the manufacturer’s recommended firing program. Four random (Research Randomizer, v4.0; Urbaniak GC & Plous S, 2013, http://www.randomizer.org/) glazed specimens of each porcelain material type were used as the control group, and their surface roughness was measured without further treatment. Intraoral adjustment was simulated in the other 4 groups by removing the glaze layer on both the front and back surface with fine-grain (30 mm and 15 mm) diamond rotary instruments (ISO 806 314 158 514 014, ISO 806 314 158 504 014, Komet; Komet, Gebr. Brassler GmbH & Co) for 10 seconds in one direction by using a high-speed handpiece (956 LX; W&H GmbH) with water spray. The abraded surfaces were then washed with distilled water and dried before mechanical polishing. The specimens were randomly assigned to 1 of the 4 groups based on the polishing kit used. The instruments were applied for 30 seconds at 6000 rpm for the Komet polishing kit (Keramikpolitur Kit; Komet, Gebr. Brassler GmbH & Co) and at 10 000 rpm for the Meisinger (Luster Intraoral Twist Kit; Hager & Meisinger GmbH), Shofu (Ceramisté Porcelain Veneer Kit; Shofu), and OptraFine polishing kits (Ivoclar Vivadent AG). After polishing with OptraFine, a diamond paste (OptraFine HP Polishing Paste; Ivoclar Vivadent AG) was used with a nylon brush without water spray for 60 seconds for high-gloss polishing. The polishing material was renewed for every 5 specimens. This application was performed by 1 Incesu and Yanikoglu
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Table 1. Two-way ANOVA of surface roughness values (Ra) Variation Resources Ceramic group
Sum of Squares 1.809
Table 2. Two-way ANOVA of surface roughness values (Rz)
df
Mean Square
F
P
2
0.905
213.012
<.001
Ceramic group
Variation Resources
Sum of Squares
df
Mean Square
F
P
70.713
2
35.356
264.764
<.001
Polishing method
0.775
4
0.194
45.609
<.001
Polishing method
31.564
4
7.891
59.091
<.001
Ceramic group×polishing method
0.555
8
0.069
16.332
<.001
Ceramic group×polishing method
17.480
8
2.185
16.363
<.001
Table 3. Mean ±standard deviation of surface roughness (Ra values in mm) for ceramic systems after various surface-finishing protocols and differences among groups
Table 4. Mean ±standard deviation of surface roughness (Rz values in mm) for ceramic systems after various surface-finishing protocols and differences between groups
Group
Lava Plus (mm)
IPS e.max Ceram (mm)
VITA VM9 (mm)
Total (mm)
Rz
Glaze
0.08 ±0.03a,A
0.17 ±0.03a,B
0.25 ±0.09a,C
0.17 ±0.09a
Glaze
OptraFine 0.10 ±0.02a,A
0.18 ±0.06a,B
0.33 ±0.08ab,C 0.20 ±0.12ab
c,A
a,A
Total (mm)
0.44 ±0.14a,A
0.99 ±0.18a,B
1.35 ±0.34a,C
0.93 ±0.44a
OptraFine 0.55 ±0.14a,A
1.03 ±0.37a,B
2.20 ±0.42bc,C 1.26 ±0.78ab
c,A
a,A
2.80 ±0.41bc,B 1.85 ±0.79bc
0.25 ±0.06
Shofu
1.52 ±0.48
0.24 ±0.07c,A
0.20 ±0.05a,A
0.72 ±0.10d,B
0.39 ±0.25c
Komet
1.46 ±0.42c,A
1.33 ±0.29a,A
4.21 ±0.58d,B
2.33 ±1.42c
Meisinger 0.17 ±0.03b,A
0.32 ±0.05b,B
0.48 ±0.14c,C
0.32 ±0.15bc
Meisinger 0.96 ±0.19b,A
1.92 ±0.41b,B
3.19 ±0.49c,C
2.02 ±1.00c
Total
0.17 ±0.08
0.21 ±0.07
0.45 ±0.18
B
0.30 ±0.12
VITA VM9 (mm)
Komet
A
0.45 ±0.08
bc
IPS e.max Ceram (mm)
Shofu
A
0.20 ±0.04
bc,B
Lava Plus (mm)
0.28 ±0.17
Different superscript lowercase letter in same column indicates different averages (P<.05). Different superscript uppercase letter on same row indicates different averages (P<.05).
researcher (E.I.) using finger pressure (approximately 2 N) with rotational and linear motions. A profilometer (Taylor Hobson Surtronic 25; Taylor Hobson Ltd) was used to measure the surface roughness. After calibrating the device, the cutoff value of the diamond tip was set to 0.25 mm,43,44 and a measurement force of 0.7 mN was applied. The device was recalibrated before the measurement of each group. Three parallel measurements were made on the center of each specimen, and the mean surface roughness (Ra) and the arithmetic mean height of the surface profile (Rz) were calculated.10,12,43 For each ceramic material, 1 randomly selected specimen from the control group and 1 from the other polished specimen surfaces were examined with AFM and ESEM. A 20-mm2 area was scanned 3dimensionally with the AFM (model 5100N AFM; Hitachi High-Technologies Co) at a scanning rate of 1.6 Hz. The device was calibrated before each measurement. No surface coating was applied to the specimens selected for the ESEM, and they were imaged under a focused ion beam (FIB) tomographic scanning electron microscope (Quanta 3D FEG; FEI) at magnifications of ×500, ×1000, and ×2000. The sample size was calculated with software (PASS 11; Hintze, J. (2011). PASS 11; NCSS, LLC). Based on previous published results, an effect size of D2=0.62 was assumed. A type I error rate of a=.001 was specified. Under the aforementioned assumptions, a sample size of n=7 per group was adequate to obtain a power of 80%. Two-way ANOVA was used to determine the roughness profile of the specimens, and the Tukey honestly significant difference (HSD) test was used for multiple
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0.99 ±0.54
A
1.25 ±0.25
1.30 ±0.45
A
2.75 ±1.06
B
1.68 ±1.06
Different superscript lowercase letter in same column indicates different averages (P<.05). Different superscript uppercase letter on same row indicates different averages (P<.05).
comparisons with statistical software (IBM SPSS Statistics, v21 for Windows; IBM Corp) (a=.05 for all analyses). RESULTS A statistically significant difference was found between the Ra and Rz values of the ceramic materials (P<.001) with the VITA VM9 group having the highest Ra and Rz values (Tables 1 and 2). The lowest Ra values were observed for the Lava Plus and IPS e.max Ceram groups, with no statistically significant difference between these materials (P=.218). The difference among the Ra and Rz values of polishing materials was statistically significant (P<.001) (Tables 1 and 2). The smoothest surfaces were in the control glazed group and the OptraFine group, with no significant difference (P=.95). The other groups showed differences from the glazed group (P<.05) but not when compared with each other (P=.59) (Tables 3 and 4). The Lava Plus polishing materials group was observed to have an effectiveness close to the general distribution of the polishing methods. In the IPS e.max Ceram group, the Meisinger method, which had the highest Ra and Rz values, showed a statistically significant difference from the other polishing methods (P<.05) (Tables 3 and 4). In the VITA VM9 group, the glazed (0.25 ±0.09 mm) and OptraFine (0.33 ±0.08 mm) groups yielded the lowest Ra values, and Komet (0.72 ±0.10 mm) yielded the highest Ra values (Table 3). The VITA VM9 group showed significantly higher values of Rz than the other ceramic types. In the VITA VM9 group, the lowest Rz value was observed in the
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Figure 1. Environmental scanning electron microscope images (original magnification ×2000) of specimens after glazing. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 2. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with OptraFine system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
glazed group (1.35 ±0.34 mm) and the highest in the Komet group (4.21 ±0.58 mm) (Table 4). In the Lava Plus group, Komet and Shofu polishing materials were found to have higher Rz values than the other polishing systems, but the difference between the 2 was not statistically significant (P=.398). The ESEM images of the glazed groups demonstrated a surface structure that was regular and homogeneous, with no irregular areas except a wavy surface from the
application of the glaze (Fig. 1). The OptraFine group was similar to the glazed group (Fig. 2). In the Shofu and Komet groups, the surface showed pores and scratches and was rougher than that in the glazed and OptraFine groups (Figs. 3, 4). In the Komet group, the pores were increased and more numerous and had sharper edges (Fig. 4). The Meisinger group displayed a surface more similar to that of the OptraFine group and with more regular areas than the Shofu or Komet groups. However, scratches and pores were visible on the surface (Fig. 5).
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Figure 3. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Shofu system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The AFM images showed the Lava Plus ceramic with the smoothest and VITA VM9 with the roughest surface (Figs. 6-10). In each ceramic type, the glazed specimen surfaces were observed to have a small number of irregular, scattered, sharp spikes of different heights on the surface, which appeared smoother than the mechanically polished surfaces. When the polishing effectiveness of the 4 polishing kits was compared, the OptraFine polishing kit provided a smoother result on
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Figure 4. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Komet system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
ceramic surfaces: this was supported by the AFM images (Fig. 7). DISCUSSION The study showed that the ceramic polishing kits led to a statistically significant difference in the surface roughness of ceramic systems (P<.001). Therefore, the null hypothesis was rejected.
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Figure 5. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Meisinger system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 6. Atomic force microscope images of specimens after glazing. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Although polished ceramic has been reported to have similar surface roughness to glazed ceramic,1-3 the Ra values of the polished specimens have been reported to change depending on the polishing system,1,4 rotation speed of the device,5 duration and amount of applied pressure,4 presence or absence of water during finishing,5 and type of ceramic to be polished.4,45 Even though similar diamond abrasives were used in many of the polishing materials, the difference in their performance
might be explained by variations in the diamond particle type (natural or synthetic), particle shape, particle size, density, or binding material. When polishing with diamond paste is used as the final step, polished ceramic specimens have been reported1,3,45 to have smooth surfaces comparable with those of glazed specimens, which is consistent with the present study in which OptraFine polishing paste was used. An optimal threshold has not yet been established
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Figure 7. Atomic force microscope images of specimens after polishing with OptraFine system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
for an acceptable surface roughness value for the clinical retention of bacteria. However, Ra values above 0.2 mm have been reported to lead to increased plaque accumulation and periodontal inflammation, as well as a higher risk of dental caries.46 In the present study, the VITA VM9 ceramic had a significantly greater surface roughness than the Lava Plus or IPS e.max. In addition, all 3 materials tested included groups with Ra values above the threshold value of 0.2 mm after different mechanical polishing applications.
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Figure 8. Atomic force microscope images of specimens after polishing with Shofu system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The tongue can sense roughness changes above 0.3
mm47; therefore, patient comfort may be negatively
affected by an excessively rough restoration surface. In the present study, all Lava Plus and IPS e.max Ceram specimens had a lower surface roughness than this value after every polishing application, while the VITA VM9 specimens, excluding those that were glazed, had surface roughness values higher than 0.3 mm after all types of mechanical polishing. Therefore, glazing is the most appropriate finishing method for VITA VM9 restorations.
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Figure 9. Atomic force microscope images of specimens after polishing with Komet system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 10. Atomic force microscope images of specimens after polishing with Meisinger system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The surface roughness of opposing enamel in occlusal contact areas is stated to be 0.64 mm48 and is a clinically important reference for the surface roughness of a restoration. The definitive surface roughness values obtained for all ceramic types in this study were lower than the enamel roughness in occlusal contact areas; hence, it can be considered that all 3 materials were clinically acceptable. One exception is the VITA VM9 ceramic applied with the Komet polishing kit, which had an Ra value (0.72 ±0.1 mm) higher than the critical value. For
this reason, the Komet polishing kit is not recommended for VITA VM9 veneering porcelain. Polishing has been reported to provide a smoother surface than autoglazing or glazing,11,16,36,44 but other studies have reported no difference between groups that were glazed or polished with rubber polishers.1,15,33,43 The present study also found that glazed groups and some polished groups exhibited similar surface roughnesses. These groups used the OptraFine polishing kit on Lava Plus or VITA VM9 porcelain and the OptraFine, Shofu, or
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Komet polishing kits on IPS e.max Ceram porcelain. The highest Ra value for Lava Plus monolithic ceramic was observed with the Ceramiste (Shofu) polishing kit (0.25 ±0.06 mm), possibly because of the lower diamond content and higher silicon carbide content of this polishing kit. Different roughness values were found for the different ceramic materials although finished with the same systems. Therefore, the polishing system did not have the same effectiveness on all the ceramic systems. This finding was consistent with that of Tholt et al10 who reported that polishing methods had varying effects on each of the 3 ceramic materials that they studied. Sasahara et al19 noted the importance of considering the material structure when selecting a polishing method and that leucite content influences polishability. When ceramics with a lower leucite content were polished with diamond paste using a rubber point or disk, a smoother surface was obtained. The VITA VM9, which had the highest leucite content among the ceramic materials tested, had the highest surface roughness with each of the polishing methods. Moreover, in the preparation of the VITA VM9 porcelain, manually mixing porcelain liquid and powder,49 using a brush for layering, and other uncontrollable steps50 were factors that led to porosity.51 ESEM and the AFM provided a qualitative evaluation of the surface properties in the present study. These images revealed scratches caused by the polishing instruments, and the smoothest surface was achieved by glazing. Limitations of the study included that only a limited number of polishing kits were tested and that the polishing procedure was not standardized, although all specimens were polished by 1 researcher using finger pressure with rotational and linear motions. A custom device to ensure polishing at a consistent load is recommended for future studies. CONCLUSIONS Based on the findings of this in vitro study, the following conclusions were drawn: 1. None of the commercially available ceramic polishing kits provided a smoother ceramic surface than glazing (P<.001). 2. The best polishing system after removal of the glaze layer depends on the ceramic type used. 3. Using an atomic force microscope to evaluate the surface roughness of dental restorations provided efficient results. REFERENCES 1. Sarac D, Sarac YS, Yuzbasioglu E, Bal S. The effects of porcelain polishing systems on the color and surface texture of feldspathic porcelain. J Prosthet Dent 2006;96:122-8.
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2. Haywood VB, Heymann HO, Kusy RP, Whitley JQ, Andreaus SB. Polishing porcelain veneers: an SEM and specular reflectance analysis. Dent Mater J 1988;4:116-21. 3. Al-Wahadni AM, Martin DM. An in vitro investigation into the wear effects of glazed, unglazed and refinished dental porcelain on an opposing material. J Oral Rehabil 1999;26:538-46. 4. Yap AU, Sau CW, Lye KW. Effects of finishing/polishing time on surface characteristics of tooth-coloured restoratives. J Oral Rehabil 1998;25:456-61. 5. Haywood VB, Heymann HO, Scurria MS. Effects of water, speed, and experimental instrumentation on finishing and polishing porcelain intraorally. Dent Mater J 1989;5:185-8. 6. Kawai K, Urano M, Ebisu S. Effect of surface roughness of porcelain on adhesion of bacteria and their synthesizing glucans. J Prosthet Dent 2000;83: 664-7. 7. Turkun LS, Turkun M. The effect of one-step polishing system on the surface roughness of three esthetic resin composite materials. Oper Dent 2004;29: 203-11. 8. Borges AB, Marsilio AL, Pagani C, Rodrigues JR. Surface roughness of packable composite resins polished with various systems. J Esthet Restor Dent 2004;16:42-7; discussion 48. 9. Chu FC, Frankel N, Smales RJ. Surface roughness and flexural strength of self-glazed, polished, and reglazed In-Ceram/Vitadur Alpha porcelain laminates. Int J Prosthodont 2000;13:66-71. 10. Tholt de Vasconcellos B, Miranda-Junior WG, Prioli R, Thompson J, Oda M. Surface roughness in ceramics with different finishing techniques using atomic force microscope and profilometer. Oper Dent 2006;31:442-9. 11. Wright MD, Masri R, Driscoll CF, Romberg E, Thompson GA, Runyan DA. Comparison of three systems for the polishing of an ultra-low fusing dental porcelain. J Prosthet Dent 2004;92:486-90. 12. Martinez-Gomis J, Bizar J, Anglada JM, Samso J, Peraire M. Comparative evaluation of four finishing systems on one ceramic surface. Int J Prosthodont 2003;16:74-7. 13. Kou W, Molin M, Sjogren G. Surface roughness of five different dental ceramic core materials after grinding and polishing. J Oral Rehabil 2006;33: 117-24. 14. Jung M, Wehlen O, Klimek J. Finishing and polishing of indirect composite and ceramic inlays in-vivo: occlusal surfaces. Oper Dent 2004;29:131-41. 15. Klausner LH, Cartwright CB, Charbeneau GT. Polished versus autoglazed porcelain surfaces. J Prosthet Dent 1982;47:157-62. 16. Hulterstrom AK, Bergman M. Polishing systems for dental ceramics. Acta Odontol Scand 1993;51:229-34. 17. Carlen A, Nikdel K, Wennerberg A, Holmberg K, Olsson J. Surface characteristics and in vitro biofilm formation on glass ionomer and composite resin. Biomaterials 2001;22:481-7. 18. Quirynen M, Bollen CM. The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature. J Clin Periodontol 1995;22:1-14. 19. Sasahara RM, Ribeiro Fda C, Cesar PF, Yoshimura HN. Influence of the finishing technique on surface roughness of dental porcelains with different microstructures. Oper Dent 2006;31:577-83. 20. Goldstein RE. Finishing of composites and laminates. Dent Clin North Am 1989;33:305-18. 210-309. 21. Jefferies SR. The art and science of abrasive finishing and polishing in restorative dentistry. Dent Clin North Am 1998;42:613-27. 22. Ancowitz S, Torres T, Rostami H. Texturing and polishing. The final attempt at value control. Dent Clin North Am 1998;42:607-12. 23. Camacho GB, Vinha D, Panzeri H, Nonaka T, Goncalves M. Surface roughness of a dental ceramic after polishing with different vehicles and diamond pastes. Braz Dent J 2006;17:191-4. 24. Campbell SD, Kelly JR. Influence of surface preparation on the strength and surface microstructure of a cast dental ceramic. Int J Prosthodont 1989;2: 459-66. 25. Patterson CJ, McLundie AC, Stirrups DR, Taylor WG. Refinishing of porcelain by using a refinishing kit. J Prosthet Dent 1991;65:383-8. 26. Patterson CJ, McLundie AC, Stirrups DR, Taylor WG. Efficacy of a porcelain refinishing system in restoring surface finish after grinding with fine and extra-fine diamond burs. J Prosthet Dent 1992;68:402-6. 27. Brewer JD, Garlapo DA, Chipps EA, Tedesco LA. Clinical discrimination between autoglazed and polished porcelain surfaces. J Prosthet Dent 1990;64: 631-4. 28. Steiner R, Beier US, Heiss-Kisielewsky I, Engelmeier R, Dumfahrt H, Dhima M. Adjusting dental ceramics: an in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface. J Prosthet Dent 2015;113:616-22. 29. Karayazgan B, Atay A, Saracli MA, Gunay Y. Evaluation of Candida albicans formation on feldspathic porcelain subjected to four surface treatment methods. Dent Mater J 2010;29:147-53. 30. Oliveira-Junior OB, Buso L, Fujiy FH, Lombardo GH, Campos F, Sarmento HR, et al. Influence of polishing procedures on the surface roughness of dental ceramics made by different techniques. Gen Dent 2013;61:e4-8.
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31. Valian A, Moravej-Salehi E. Surface treatment of feldspathic porcelain: scanning electron microscopy analysis. J Adv Prosthodont 2014;6:387-94. 32. Donald AM. The use of environmental scanning electron microscopy for imaging wet and insulating materials. Nat Mater 2003;2:511-6. 33. Demirel F, Yuksel G, Muhtarogullari M, Cekic C. Effect of topical fluorides and citric acid on heat-pressed all-ceramic material. Int J Periodontics Restorative Dent 2005;25:277-81. 34. Boaventura JM, Nishida R, Elossais AA, Lima DM, Reis JM, Campos EA, et al. Effect finishing and polishing procedures on the surface roughness of IPS Empress 2 ceramic. Acta Odontol Scand 2013;71:438-43. 35. Bottino MC, Valandro LF, Kantorski KZ, Bressiani JC, Bottino MA. Polishing methods of an alumina-reinforced feldspar ceramic. Braz Dent J 2006;17: 285-9. 36. Flury S, Lussi A, Zimmerli B. Performance of different polishing techniques for direct CAD/CAM ceramic restorations. Oper Dent 2010;35:470-81. 37. Sarac D, Turk T, Elekdag-Turk S, Sarac YS. Comparison of 3 polishing techniques for 2 all-ceramic materials. Int J Prosthodont 2007;20:465-8. 38. Oh WS, Shen C, Alegre B, Anusavice KJ. Wetting characteristic of ceramic to water and adhesive resin. J Prosthet Dent 2002;88:616-21. 39. Kosmac T, Oblak C, Jevnikar P, Funduk N, Marion L. The effect of surface grinding and sandblasting on flexural strength and reliability of Y-TZP zirconia ceramic. Dent Mater J 1999;15:426-33. 40. Isgro G, Pallav P, van der Zel JM, Feilzer AJ. The influence of the veneering porcelain and different surface treatments on the biaxial flexural strength of a heat-pressed ceramic. J Prosthet Dent 2003;90:465-73. 41. Cury-Saramago Ade A, Coimbra PR, Izquierdo Ade M, Elias CN, Ruellas AC, Sant’Anna EF. Ceramic surface polishing techniques after removal of orthodontic adhesive. Angle Orthod 2009;79:790-5. 42. Sarikaya I, Guler AU. Effects of different polishing techniques on the surface roughness of dental porcelains. J Appl Oral Sci 2010;18:10-6. 43. Fuzzi M, Zaccheroni Z, Vallania G. Scanning electron microscopy and profilometer evaluation of glazed and polished dental porcelain. Int J Prosthodont 1996;9:452-8. 44. Ward MT, Tate WH, Powers JM. Surface roughness of opalescent porcelains after polishing. Oper Dent 1995;20:106-10.
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45. Akar GC, Pekkan G, Cal E, Eskitascioglu G, Ozcan M. Effects of surfacefinishing protocols on the roughness, color change, and translucency of different ceramic systems. J Prosthet Dent 2014;112:314-21. 46. Bollen CM, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater J 1997;13:258-69. 47. Jones CS, Billington RW, Pearson GJ. The in vivo perception of roughness of restorations. Br Dent J 2004;196:42-5. discussion 31. 48. Willems G, Lambrechts P, Braem M, Vuylsteke-Wauters M, Vanherle G. The surface roughness of enamel-to-enamel contact areas compared with the intrinsic roughness of dental resin composites. J Dent Res 1991;70: 1299-305. 49. Fleming GJ, Shaini FJ, Marquis PM. An assessment of the influence of mixing induced variability on the bi-axial flexure strength of dentine porcelain discs and the implications for laboratory testing of porcelain specimens. Dent Mater J 2000;16:114-9. 50. Lima JM, Souza AC, Anami LC, Bottino MA, Melo RM, Souza RO. Effects of thickness, processing technique, and cooling rate protocol on the flexural strength of a bilayer ceramic system. Dent Mater J 2013;29:1063-72. 51. Zhang Y, Griggs JA, Benham AW. Influence of powder/liquid mixing ratio on porosity and translucency of dental porcelains. J Prosthet Dent 2004;91: 128-35. Corresponding author: Dr Esra Incesu Department of Prosthetic Dentistry Faculty of Dentistry Atatürk University Erzurum TURKEY Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.07.003
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Evaluation of the effect of different polishing systems on the surface roughness of dental ceramics Esra Incesu, DDS, PhDa and Nuran Yanikoglu, DDS, PhDb As restorations with smooth ABSTRACT surfaces are important for both Statement of problem. How the finishing and polishing of ceramic restorations may affect their oral health and esthetics, the surface properties is unclear. effect of polishing and glazing Purpose. The purpose of this in vitro study was to evaluate the effect of different polishing systems on the surface of dental ceon the surface roughness of dental ceramics by using a profilometer, an environmental scanning 1-6 ramics has been evaluated. electron microscope (ESEM), and an atomic force microscope (AFM). The objective of finishing and Material and methods. Sixty square specimens (2×14×14 mm) of 3 popular ceramic systems glazing is to obtain an accept(monolithic zirconia and feldspathic-based ceramic containing feldspar and fluorapatite) were able contour and occlusion, a prepared, glazed, and assigned to 1 of the 5 groups: a control group with no additional healthy embrasure, and a treatment after the glaze; in the other groups, the glaze layer was removed, and the surfaces 7 smooth surface. A direct were polished by using 4 different ceramic polishing systems (OptraFine, Shofu, Meisinger, or relationship exists between Komet). The surface roughness was evaluated numerically by using a profilometer and visually surface roughness and plaque by using an ESEM and an AFM. The data were interpreted by using 2-way ANOVA. A multiple comparison of averages was conducted by using the Tukey HSD (a=.05). accumulation, discoloration of the restoration, and esthetics.8 Results. The smoothest surface was obtained in the glazed group polished with the OptraFine kit, When roughness increases, with no statistically significant difference (P=.95). The other groups showed a significant difference the wear of opposing enamel from the glazed one (P<.05); however, the difference among the other groups was not significantly different (P=.59). increases, as does restoration discoloration,9-12 staining, and Conclusions. After the adjustment of dental ceramics and upon removal of the glaze, the OptraFine plaque and calculus formapolishing kit and paste application can be used as an alternative to glazing for the 3 ceramic types tested. It was not possible to adequately polish the ceramic surface by using the Komet polishing tion.9,11 The surface roughness kit. (J Prosthet Dent 2019;-:---) of restorative materials should be minimized to eliminate these unfavorable occurrences and to optimize esthetics performed in successive steps.7 Different polishing kits 10 and oral health. are marketed with the purpose of eliminating irregularities and achieving smooth surfaces.10,12,19,20 InAfter the cementation of restorations, occlusal or contour adjustment may be needed. These adjustments struments, including tungsten carbide finishing burs, are usually made with diamond rotary instruments that diamond rotary instruments, silicone rubber disks, and remove the glazed surface and increase the surface silicon carbide or aluminum oxideecoated abrasive disks, roughness.11,13-16 A poorly finished restoration causes are used to finish restoration surfaces.21 Polishing enbiofilm accumulation and growth.17,18 To resmooth hances structural resistance and helps regain restoration gloss.10,22,23 roughened restorative surfaces, finishing and polishing is
Supported by the Atatürk University Coordination Office for Scientific Research Project (grant 2016/101). a Graduate Prosthodontist, Department of Prosthetic Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey. b Professor, Department of Prosthetic Dentistry, Faculty of Dentistry, University of Atatürk, Erzurum, Turkey.
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Clinical Implications After the adjustment and polishing of ceramic restorations, an acceptable surface smoothness can be produced with the appropriate polishing system and technique.
The roughness of adjusted surfaces can be reduced by polishing, but the result has been reported to be not as smooth as a glazed surface.24-26 However, Brewer et al27 reported that after a second firing to reglaze polished crowns, the restoration lacked an esthetic matt appearance. A surface profilometer is an appropriate instrument used for the quantitative evaluation of surface roughness.28,29 However, sometimes roughness values do not accurately represent the topography of ceramic surfaces because only a certain part of the surface is examined by using the profilometer.30 For this reason, examination with a scanning electron microscope (SEM) has been advocated for more extensive analysis.31 The environmental scanning electron microscope (ESEM) may be more suitable than the SEM as it provides electron microscope images without the need to coat the specimens with metal. In addition, the ESEM can be used to image wet or isolated specimens without prior preparation.32 Examination with an atomic force microscope (AFM) provides increased resolution and 3-dimensional display and also more details compared with a profilometer or visual evaluation.10,33 Ceramic polishing kits have been evaluated to determine whether a surface can be restored to the glazed surface before adjustment23,34-37; however, detailed evaluations with ESEM and AFM are lacking. The purpose of this in vitro study was to evaluate the surface smoothness of different ceramic systems after treatment with different polishing kits and to investigate their effectiveness. The null hypothesis was that no difference in surface roughness would be found among the polishing systems tested. MATERIAL AND METHODS Twenty specimens (14×14×2 mm) for each ceramic material type (IPS e.max Ceram; Ivoclar Vivadent AG, VITA VM9; VITA Zahnfabrik, and Lava Plus Zirconia; 3M ESPE) were produced following the manufacturer’s instructions. Custom molds were used in the preparation of IPS e.max Ceram and VITA VM9 ceramic specimens. As suggested by the manufacturer, powder and liquid were mixed at the specified ratio in a glass container until homogeneous and then loaded into the mold with a layering technique. Excess surface liquid was removed with an absorbent paper,1 and the mold was vibrated to
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reduce porosity. The specimens were sintered in a porcelain furnace (EP 600; Ivoclar Vivadent AG) according to the manufacturer’s recommendations. The zirconia specimens were milled with a computer-aided design and computer-aided manufacturing (CAD-CAM) system from disks (Lava Plus Zirconia; 3M ESPE). The specimens were sintered in a furnace (ELV MoS 160/1; Protherm Furnaces) for 8 hours at 1550 C. To ensure standardization, all specimens were abraded with a grinding machine (Phoenix Beta Grinder/ Polisher; Buehler) at a constant speed of 300 rpm with 320-, 400-, 600-, and 1200-grit silicon carbide papers for 20 seconds with water cooling.38 The thickness of the specimens was measured with digital calipers (Absolute Digimatic Caliper; Mitutoyo Corp). The specimen dimensions were based on those of previous studies.10,23,34,39-42 They were then cleaned with 99% alcohol for 3 minutes with an ultrasonic cleaner (Sonorex RK102 Transistor; Bandelin). One investigator (E.I.) applied a homogeneous thin layer of glaze paste and liquid prepared on a glass plate to each surface of the specimens. Glaze powders and liquids (VITA Akzent; VITA Zahnfabrik, IPS e.max Ceram Glaze; Ivoclar Vivadent AG, and Cercon Ceram; DeguDent GmbH) were used for the corresponding specimens, which was performed in a conventional porcelain furnace (Programat P300; Ivoclar Vivadent AG) with the manufacturer’s recommended firing program. Four random (Research Randomizer, v4.0; Urbaniak GC & Plous S, 2013, http://www.randomizer.org/) glazed specimens of each porcelain material type were used as the control group, and their surface roughness was measured without further treatment. Intraoral adjustment was simulated in the other 4 groups by removing the glaze layer on both the front and back surface with fine-grain (30 mm and 15 mm) diamond rotary instruments (ISO 806 314 158 514 014, ISO 806 314 158 504 014, Komet; Komet, Gebr. Brassler GmbH & Co) for 10 seconds in one direction by using a high-speed handpiece (956 LX; W&H GmbH) with water spray. The abraded surfaces were then washed with distilled water and dried before mechanical polishing. The specimens were randomly assigned to 1 of the 4 groups based on the polishing kit used. The instruments were applied for 30 seconds at 6000 rpm for the Komet polishing kit (Keramikpolitur Kit; Komet, Gebr. Brassler GmbH & Co) and at 10 000 rpm for the Meisinger (Luster Intraoral Twist Kit; Hager & Meisinger GmbH), Shofu (Ceramisté Porcelain Veneer Kit; Shofu), and OptraFine polishing kits (Ivoclar Vivadent AG). After polishing with OptraFine, a diamond paste (OptraFine HP Polishing Paste; Ivoclar Vivadent AG) was used with a nylon brush without water spray for 60 seconds for high-gloss polishing. The polishing material was renewed for every 5 specimens. This application was performed by 1 Incesu and Yanikoglu
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Table 1. Two-way ANOVA of surface roughness values (Ra) Variation Resources Ceramic group
Sum of Squares 1.809
Table 2. Two-way ANOVA of surface roughness values (Rz)
df
Mean Square
F
P
2
0.905
213.012
<.001
Ceramic group
Variation Resources
Sum of Squares
df
Mean Square
F
P
70.713
2
35.356
264.764
<.001
Polishing method
0.775
4
0.194
45.609
<.001
Polishing method
31.564
4
7.891
59.091
<.001
Ceramic group×polishing method
0.555
8
0.069
16.332
<.001
Ceramic group×polishing method
17.480
8
2.185
16.363
<.001
Table 3. Mean ±standard deviation of surface roughness (Ra values in mm) for ceramic systems after various surface-finishing protocols and differences among groups
Table 4. Mean ±standard deviation of surface roughness (Rz values in mm) for ceramic systems after various surface-finishing protocols and differences between groups
Group
Lava Plus (mm)
IPS e.max Ceram (mm)
VITA VM9 (mm)
Total (mm)
Rz
Glaze
0.08 ±0.03a,A
0.17 ±0.03a,B
0.25 ±0.09a,C
0.17 ±0.09a
Glaze
OptraFine 0.10 ±0.02a,A
0.18 ±0.06a,B
0.33 ±0.08ab,C 0.20 ±0.12ab
c,A
a,A
Total (mm)
0.44 ±0.14a,A
0.99 ±0.18a,B
1.35 ±0.34a,C
0.93 ±0.44a
OptraFine 0.55 ±0.14a,A
1.03 ±0.37a,B
2.20 ±0.42bc,C 1.26 ±0.78ab
c,A
a,A
2.80 ±0.41bc,B 1.85 ±0.79bc
0.25 ±0.06
Shofu
1.52 ±0.48
0.24 ±0.07c,A
0.20 ±0.05a,A
0.72 ±0.10d,B
0.39 ±0.25c
Komet
1.46 ±0.42c,A
1.33 ±0.29a,A
4.21 ±0.58d,B
2.33 ±1.42c
Meisinger 0.17 ±0.03b,A
0.32 ±0.05b,B
0.48 ±0.14c,C
0.32 ±0.15bc
Meisinger 0.96 ±0.19b,A
1.92 ±0.41b,B
3.19 ±0.49c,C
2.02 ±1.00c
Total
0.17 ±0.08
0.21 ±0.07
0.45 ±0.18
B
0.30 ±0.12
VITA VM9 (mm)
Komet
A
0.45 ±0.08
bc
IPS e.max Ceram (mm)
Shofu
A
0.20 ±0.04
bc,B
Lava Plus (mm)
0.28 ±0.17
Different superscript lowercase letter in same column indicates different averages (P<.05). Different superscript uppercase letter on same row indicates different averages (P<.05).
researcher (E.I.) using finger pressure (approximately 2 N) with rotational and linear motions. A profilometer (Taylor Hobson Surtronic 25; Taylor Hobson Ltd) was used to measure the surface roughness. After calibrating the device, the cutoff value of the diamond tip was set to 0.25 mm,43,44 and a measurement force of 0.7 mN was applied. The device was recalibrated before the measurement of each group. Three parallel measurements were made on the center of each specimen, and the mean surface roughness (Ra) and the arithmetic mean height of the surface profile (Rz) were calculated.10,12,43 For each ceramic material, 1 randomly selected specimen from the control group and 1 from the other polished specimen surfaces were examined with AFM and ESEM. A 20-mm2 area was scanned 3dimensionally with the AFM (model 5100N AFM; Hitachi High-Technologies Co) at a scanning rate of 1.6 Hz. The device was calibrated before each measurement. No surface coating was applied to the specimens selected for the ESEM, and they were imaged under a focused ion beam (FIB) tomographic scanning electron microscope (Quanta 3D FEG; FEI) at magnifications of ×500, ×1000, and ×2000. The sample size was calculated with software (PASS 11; Hintze, J. (2011). PASS 11; NCSS, LLC). Based on previous published results, an effect size of D2=0.62 was assumed. A type I error rate of a=.001 was specified. Under the aforementioned assumptions, a sample size of n=7 per group was adequate to obtain a power of 80%. Two-way ANOVA was used to determine the roughness profile of the specimens, and the Tukey honestly significant difference (HSD) test was used for multiple
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0.99 ±0.54
A
1.25 ±0.25
1.30 ±0.45
A
2.75 ±1.06
B
1.68 ±1.06
Different superscript lowercase letter in same column indicates different averages (P<.05). Different superscript uppercase letter on same row indicates different averages (P<.05).
comparisons with statistical software (IBM SPSS Statistics, v21 for Windows; IBM Corp) (a=.05 for all analyses). RESULTS A statistically significant difference was found between the Ra and Rz values of the ceramic materials (P<.001) with the VITA VM9 group having the highest Ra and Rz values (Tables 1 and 2). The lowest Ra values were observed for the Lava Plus and IPS e.max Ceram groups, with no statistically significant difference between these materials (P=.218). The difference among the Ra and Rz values of polishing materials was statistically significant (P<.001) (Tables 1 and 2). The smoothest surfaces were in the control glazed group and the OptraFine group, with no significant difference (P=.95). The other groups showed differences from the glazed group (P<.05) but not when compared with each other (P=.59) (Tables 3 and 4). The Lava Plus polishing materials group was observed to have an effectiveness close to the general distribution of the polishing methods. In the IPS e.max Ceram group, the Meisinger method, which had the highest Ra and Rz values, showed a statistically significant difference from the other polishing methods (P<.05) (Tables 3 and 4). In the VITA VM9 group, the glazed (0.25 ±0.09 mm) and OptraFine (0.33 ±0.08 mm) groups yielded the lowest Ra values, and Komet (0.72 ±0.10 mm) yielded the highest Ra values (Table 3). The VITA VM9 group showed significantly higher values of Rz than the other ceramic types. In the VITA VM9 group, the lowest Rz value was observed in the
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Figure 1. Environmental scanning electron microscope images (original magnification ×2000) of specimens after glazing. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 2. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with OptraFine system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
glazed group (1.35 ±0.34 mm) and the highest in the Komet group (4.21 ±0.58 mm) (Table 4). In the Lava Plus group, Komet and Shofu polishing materials were found to have higher Rz values than the other polishing systems, but the difference between the 2 was not statistically significant (P=.398). The ESEM images of the glazed groups demonstrated a surface structure that was regular and homogeneous, with no irregular areas except a wavy surface from the
application of the glaze (Fig. 1). The OptraFine group was similar to the glazed group (Fig. 2). In the Shofu and Komet groups, the surface showed pores and scratches and was rougher than that in the glazed and OptraFine groups (Figs. 3, 4). In the Komet group, the pores were increased and more numerous and had sharper edges (Fig. 4). The Meisinger group displayed a surface more similar to that of the OptraFine group and with more regular areas than the Shofu or Komet groups. However, scratches and pores were visible on the surface (Fig. 5).
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Figure 3. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Shofu system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The AFM images showed the Lava Plus ceramic with the smoothest and VITA VM9 with the roughest surface (Figs. 6-10). In each ceramic type, the glazed specimen surfaces were observed to have a small number of irregular, scattered, sharp spikes of different heights on the surface, which appeared smoother than the mechanically polished surfaces. When the polishing effectiveness of the 4 polishing kits was compared, the OptraFine polishing kit provided a smoother result on
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Figure 4. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Komet system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
ceramic surfaces: this was supported by the AFM images (Fig. 7). DISCUSSION The study showed that the ceramic polishing kits led to a statistically significant difference in the surface roughness of ceramic systems (P<.001). Therefore, the null hypothesis was rejected.
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Figure 5. Environmental scanning electron microscope images (original magnification ×2000) of specimens after polishing with Meisinger system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 6. Atomic force microscope images of specimens after glazing. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Although polished ceramic has been reported to have similar surface roughness to glazed ceramic,1-3 the Ra values of the polished specimens have been reported to change depending on the polishing system,1,4 rotation speed of the device,5 duration and amount of applied pressure,4 presence or absence of water during finishing,5 and type of ceramic to be polished.4,45 Even though similar diamond abrasives were used in many of the polishing materials, the difference in their performance
might be explained by variations in the diamond particle type (natural or synthetic), particle shape, particle size, density, or binding material. When polishing with diamond paste is used as the final step, polished ceramic specimens have been reported1,3,45 to have smooth surfaces comparable with those of glazed specimens, which is consistent with the present study in which OptraFine polishing paste was used. An optimal threshold has not yet been established
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Figure 7. Atomic force microscope images of specimens after polishing with OptraFine system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
for an acceptable surface roughness value for the clinical retention of bacteria. However, Ra values above 0.2 mm have been reported to lead to increased plaque accumulation and periodontal inflammation, as well as a higher risk of dental caries.46 In the present study, the VITA VM9 ceramic had a significantly greater surface roughness than the Lava Plus or IPS e.max. In addition, all 3 materials tested included groups with Ra values above the threshold value of 0.2 mm after different mechanical polishing applications.
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Figure 8. Atomic force microscope images of specimens after polishing with Shofu system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The tongue can sense roughness changes above 0.3
mm47; therefore, patient comfort may be negatively
affected by an excessively rough restoration surface. In the present study, all Lava Plus and IPS e.max Ceram specimens had a lower surface roughness than this value after every polishing application, while the VITA VM9 specimens, excluding those that were glazed, had surface roughness values higher than 0.3 mm after all types of mechanical polishing. Therefore, glazing is the most appropriate finishing method for VITA VM9 restorations.
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Figure 9. Atomic force microscope images of specimens after polishing with Komet system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
Figure 10. Atomic force microscope images of specimens after polishing with Meisinger system. A, Lava Plus. B, IPS e.max Ceram. C, VITA VM9.
The surface roughness of opposing enamel in occlusal contact areas is stated to be 0.64 mm48 and is a clinically important reference for the surface roughness of a restoration. The definitive surface roughness values obtained for all ceramic types in this study were lower than the enamel roughness in occlusal contact areas; hence, it can be considered that all 3 materials were clinically acceptable. One exception is the VITA VM9 ceramic applied with the Komet polishing kit, which had an Ra value (0.72 ±0.1 mm) higher than the critical value. For
this reason, the Komet polishing kit is not recommended for VITA VM9 veneering porcelain. Polishing has been reported to provide a smoother surface than autoglazing or glazing,11,16,36,44 but other studies have reported no difference between groups that were glazed or polished with rubber polishers.1,15,33,43 The present study also found that glazed groups and some polished groups exhibited similar surface roughnesses. These groups used the OptraFine polishing kit on Lava Plus or VITA VM9 porcelain and the OptraFine, Shofu, or
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Komet polishing kits on IPS e.max Ceram porcelain. The highest Ra value for Lava Plus monolithic ceramic was observed with the Ceramiste (Shofu) polishing kit (0.25 ±0.06 mm), possibly because of the lower diamond content and higher silicon carbide content of this polishing kit. Different roughness values were found for the different ceramic materials although finished with the same systems. Therefore, the polishing system did not have the same effectiveness on all the ceramic systems. This finding was consistent with that of Tholt et al10 who reported that polishing methods had varying effects on each of the 3 ceramic materials that they studied. Sasahara et al19 noted the importance of considering the material structure when selecting a polishing method and that leucite content influences polishability. When ceramics with a lower leucite content were polished with diamond paste using a rubber point or disk, a smoother surface was obtained. The VITA VM9, which had the highest leucite content among the ceramic materials tested, had the highest surface roughness with each of the polishing methods. Moreover, in the preparation of the VITA VM9 porcelain, manually mixing porcelain liquid and powder,49 using a brush for layering, and other uncontrollable steps50 were factors that led to porosity.51 ESEM and the AFM provided a qualitative evaluation of the surface properties in the present study. These images revealed scratches caused by the polishing instruments, and the smoothest surface was achieved by glazing. Limitations of the study included that only a limited number of polishing kits were tested and that the polishing procedure was not standardized, although all specimens were polished by 1 researcher using finger pressure with rotational and linear motions. A custom device to ensure polishing at a consistent load is recommended for future studies. CONCLUSIONS Based on the findings of this in vitro study, the following conclusions were drawn: 1. None of the commercially available ceramic polishing kits provided a smoother ceramic surface than glazing (P<.001). 2. The best polishing system after removal of the glaze layer depends on the ceramic type used. 3. Using an atomic force microscope to evaluate the surface roughness of dental restorations provided efficient results. REFERENCES 1. Sarac D, Sarac YS, Yuzbasioglu E, Bal S. The effects of porcelain polishing systems on the color and surface texture of feldspathic porcelain. J Prosthet Dent 2006;96:122-8.
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2. Haywood VB, Heymann HO, Kusy RP, Whitley JQ, Andreaus SB. Polishing porcelain veneers: an SEM and specular reflectance analysis. Dent Mater J 1988;4:116-21. 3. Al-Wahadni AM, Martin DM. An in vitro investigation into the wear effects of glazed, unglazed and refinished dental porcelain on an opposing material. J Oral Rehabil 1999;26:538-46. 4. Yap AU, Sau CW, Lye KW. Effects of finishing/polishing time on surface characteristics of tooth-coloured restoratives. J Oral Rehabil 1998;25:456-61. 5. Haywood VB, Heymann HO, Scurria MS. Effects of water, speed, and experimental instrumentation on finishing and polishing porcelain intraorally. Dent Mater J 1989;5:185-8. 6. Kawai K, Urano M, Ebisu S. Effect of surface roughness of porcelain on adhesion of bacteria and their synthesizing glucans. J Prosthet Dent 2000;83: 664-7. 7. Turkun LS, Turkun M. The effect of one-step polishing system on the surface roughness of three esthetic resin composite materials. Oper Dent 2004;29: 203-11. 8. Borges AB, Marsilio AL, Pagani C, Rodrigues JR. Surface roughness of packable composite resins polished with various systems. J Esthet Restor Dent 2004;16:42-7; discussion 48. 9. Chu FC, Frankel N, Smales RJ. Surface roughness and flexural strength of self-glazed, polished, and reglazed In-Ceram/Vitadur Alpha porcelain laminates. Int J Prosthodont 2000;13:66-71. 10. Tholt de Vasconcellos B, Miranda-Junior WG, Prioli R, Thompson J, Oda M. Surface roughness in ceramics with different finishing techniques using atomic force microscope and profilometer. Oper Dent 2006;31:442-9. 11. Wright MD, Masri R, Driscoll CF, Romberg E, Thompson GA, Runyan DA. Comparison of three systems for the polishing of an ultra-low fusing dental porcelain. J Prosthet Dent 2004;92:486-90. 12. Martinez-Gomis J, Bizar J, Anglada JM, Samso J, Peraire M. Comparative evaluation of four finishing systems on one ceramic surface. Int J Prosthodont 2003;16:74-7. 13. Kou W, Molin M, Sjogren G. Surface roughness of five different dental ceramic core materials after grinding and polishing. J Oral Rehabil 2006;33: 117-24. 14. Jung M, Wehlen O, Klimek J. Finishing and polishing of indirect composite and ceramic inlays in-vivo: occlusal surfaces. Oper Dent 2004;29:131-41. 15. Klausner LH, Cartwright CB, Charbeneau GT. Polished versus autoglazed porcelain surfaces. J Prosthet Dent 1982;47:157-62. 16. Hulterstrom AK, Bergman M. Polishing systems for dental ceramics. Acta Odontol Scand 1993;51:229-34. 17. Carlen A, Nikdel K, Wennerberg A, Holmberg K, Olsson J. Surface characteristics and in vitro biofilm formation on glass ionomer and composite resin. Biomaterials 2001;22:481-7. 18. Quirynen M, Bollen CM. The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature. J Clin Periodontol 1995;22:1-14. 19. Sasahara RM, Ribeiro Fda C, Cesar PF, Yoshimura HN. Influence of the finishing technique on surface roughness of dental porcelains with different microstructures. Oper Dent 2006;31:577-83. 20. Goldstein RE. Finishing of composites and laminates. Dent Clin North Am 1989;33:305-18. 210-309. 21. Jefferies SR. The art and science of abrasive finishing and polishing in restorative dentistry. Dent Clin North Am 1998;42:613-27. 22. Ancowitz S, Torres T, Rostami H. Texturing and polishing. The final attempt at value control. Dent Clin North Am 1998;42:607-12. 23. Camacho GB, Vinha D, Panzeri H, Nonaka T, Goncalves M. Surface roughness of a dental ceramic after polishing with different vehicles and diamond pastes. Braz Dent J 2006;17:191-4. 24. Campbell SD, Kelly JR. Influence of surface preparation on the strength and surface microstructure of a cast dental ceramic. Int J Prosthodont 1989;2: 459-66. 25. Patterson CJ, McLundie AC, Stirrups DR, Taylor WG. Refinishing of porcelain by using a refinishing kit. J Prosthet Dent 1991;65:383-8. 26. Patterson CJ, McLundie AC, Stirrups DR, Taylor WG. Efficacy of a porcelain refinishing system in restoring surface finish after grinding with fine and extra-fine diamond burs. J Prosthet Dent 1992;68:402-6. 27. Brewer JD, Garlapo DA, Chipps EA, Tedesco LA. Clinical discrimination between autoglazed and polished porcelain surfaces. J Prosthet Dent 1990;64: 631-4. 28. Steiner R, Beier US, Heiss-Kisielewsky I, Engelmeier R, Dumfahrt H, Dhima M. Adjusting dental ceramics: an in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface. J Prosthet Dent 2015;113:616-22. 29. Karayazgan B, Atay A, Saracli MA, Gunay Y. Evaluation of Candida albicans formation on feldspathic porcelain subjected to four surface treatment methods. Dent Mater J 2010;29:147-53. 30. Oliveira-Junior OB, Buso L, Fujiy FH, Lombardo GH, Campos F, Sarmento HR, et al. Influence of polishing procedures on the surface roughness of dental ceramics made by different techniques. Gen Dent 2013;61:e4-8.
THE JOURNAL OF PROSTHETIC DENTISTRY
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31. Valian A, Moravej-Salehi E. Surface treatment of feldspathic porcelain: scanning electron microscopy analysis. J Adv Prosthodont 2014;6:387-94. 32. Donald AM. The use of environmental scanning electron microscopy for imaging wet and insulating materials. Nat Mater 2003;2:511-6. 33. Demirel F, Yuksel G, Muhtarogullari M, Cekic C. Effect of topical fluorides and citric acid on heat-pressed all-ceramic material. Int J Periodontics Restorative Dent 2005;25:277-81. 34. Boaventura JM, Nishida R, Elossais AA, Lima DM, Reis JM, Campos EA, et al. Effect finishing and polishing procedures on the surface roughness of IPS Empress 2 ceramic. Acta Odontol Scand 2013;71:438-43. 35. Bottino MC, Valandro LF, Kantorski KZ, Bressiani JC, Bottino MA. Polishing methods of an alumina-reinforced feldspar ceramic. Braz Dent J 2006;17: 285-9. 36. Flury S, Lussi A, Zimmerli B. Performance of different polishing techniques for direct CAD/CAM ceramic restorations. Oper Dent 2010;35:470-81. 37. Sarac D, Turk T, Elekdag-Turk S, Sarac YS. Comparison of 3 polishing techniques for 2 all-ceramic materials. Int J Prosthodont 2007;20:465-8. 38. Oh WS, Shen C, Alegre B, Anusavice KJ. Wetting characteristic of ceramic to water and adhesive resin. J Prosthet Dent 2002;88:616-21. 39. Kosmac T, Oblak C, Jevnikar P, Funduk N, Marion L. The effect of surface grinding and sandblasting on flexural strength and reliability of Y-TZP zirconia ceramic. Dent Mater J 1999;15:426-33. 40. Isgro G, Pallav P, van der Zel JM, Feilzer AJ. The influence of the veneering porcelain and different surface treatments on the biaxial flexural strength of a heat-pressed ceramic. J Prosthet Dent 2003;90:465-73. 41. Cury-Saramago Ade A, Coimbra PR, Izquierdo Ade M, Elias CN, Ruellas AC, Sant’Anna EF. Ceramic surface polishing techniques after removal of orthodontic adhesive. Angle Orthod 2009;79:790-5. 42. Sarikaya I, Guler AU. Effects of different polishing techniques on the surface roughness of dental porcelains. J Appl Oral Sci 2010;18:10-6. 43. Fuzzi M, Zaccheroni Z, Vallania G. Scanning electron microscopy and profilometer evaluation of glazed and polished dental porcelain. Int J Prosthodont 1996;9:452-8. 44. Ward MT, Tate WH, Powers JM. Surface roughness of opalescent porcelains after polishing. Oper Dent 1995;20:106-10.
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45. Akar GC, Pekkan G, Cal E, Eskitascioglu G, Ozcan M. Effects of surfacefinishing protocols on the roughness, color change, and translucency of different ceramic systems. J Prosthet Dent 2014;112:314-21. 46. Bollen CM, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater J 1997;13:258-69. 47. Jones CS, Billington RW, Pearson GJ. The in vivo perception of roughness of restorations. Br Dent J 2004;196:42-5. discussion 31. 48. Willems G, Lambrechts P, Braem M, Vuylsteke-Wauters M, Vanherle G. The surface roughness of enamel-to-enamel contact areas compared with the intrinsic roughness of dental resin composites. J Dent Res 1991;70: 1299-305. 49. Fleming GJ, Shaini FJ, Marquis PM. An assessment of the influence of mixing induced variability on the bi-axial flexure strength of dentine porcelain discs and the implications for laboratory testing of porcelain specimens. Dent Mater J 2000;16:114-9. 50. Lima JM, Souza AC, Anami LC, Bottino MA, Melo RM, Souza RO. Effects of thickness, processing technique, and cooling rate protocol on the flexural strength of a bilayer ceramic system. Dent Mater J 2013;29:1063-72. 51. Zhang Y, Griggs JA, Benham AW. Influence of powder/liquid mixing ratio on porosity and translucency of dental porcelains. J Prosthet Dent 2004;91: 128-35. Corresponding author: Dr Esra Incesu Department of Prosthetic Dentistry Faculty of Dentistry Atatürk University Erzurum TURKEY Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.07.003
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