| Ceramic veneers are one of the most popular treatments for restoration of unaesthetic anterior teeth due to its excellent biocompatibility, natural appearance, and a reliable clinical success rate. The final color of ceramic veneers is determined by the combination of tooth structure color, ceramic layer thickness, and cement color.Objective:The purpose of this study is to analyze the effect of resin cements shades on the final esthetic effect of the disk-shaped ceramic veneers specimens or the ceramic veneer restoration specimens; analyze the effect of different thickness of ceramic materials on the color matching of ceramic veneer restorations; and analyze the effect of different thickness of ceramic materials and resin cement shades on the color matching of ceramic veneers at the grey shade of tooth structures.Test 1 The effect of resin cement shades on the final colors of disk-shaped ceramic veneer specimensMaterials and Methods:50 disk-shaped ceramic specimens (LT A3 shade, IPS e.Max,0.6 mm × 8.0 mm diameter) and disk-shaped composite resin background specimens (4.0 mm × 8.0 mm diameter) were prepared and divided into 10 groups (n=5). These paired specimens were bonded using ten shades of resin cement (Variolink Veneer, shades LV-3, LV-2, MV, HV+2, HV+3; Panavia F, shades light and brown; and RelyXTM Veneer, shades WO, TR, A3). A spectrophotometer (VITA Easyshade) was used to measure the color parameters (CIE L*a*b* values) of the paired disks before and after cementation. The color differences (△E values) after cementation were calculated and statistically analyzed by the One-way ANOVA (at the significant level p<0.05).Results:The color parameters of the ceramic disks were measured in terms of the increase in L* value, and the decrease in C*ab value after bonding with the resin cement. The △E values of ceramic disks after cementation ranged from 1.38 to 7.16. The AE values were more than 3.3 when the ceramic disks were cemented with resin cements in shade HV+3 (4.90) and shade WO (7.16). One-way ANOVA of AE values revealed significant differences in the resin cement shades.Test 2 The effect of shades of resin cements on final color of the ceramic veneersMaterials and Methods:48 artificial maxillary central incisor teeth (A2 shade, Endura, Shofu) were sequenced according to the measured color parameters and divided at random into 8 groups (n= 6). These artificial teeth were prepared according to veneer tooth preparation in practice. A improved lithium-disilicate pressed glass ceramic materials (IPS e.max Press, Ivoclar Vivadent) were selected to fabricate the veneer restorations, which were the same shape and curve on the surface of veneering using impression duplicating to make the wax patterns. The ceramic veneer specimens were bonded to the artificial teeth by the resin cements of 8 shades and the corresponding try-in pastes (Variolink Veneer, shades of LV-3, LV-2, MV, HV+2, HV+3; and 3M RelyXTM Veneer, shades of WO, TR, A3). A clinical spectrophotometer (Crystaleye, Olympus) was used to measure the color parameters of the ceramic veneers before the cementation treatment, treatment by the corresponding try-in pastes and after cementation; AE values and C*ab values were calculated.Results:The result of one-way ANOVA indicated that the color changes of ceramic veneer cementation by resin cements were statistically significant difference in the shades of resin cements (p< 0.001). The AE values of ceramic veneer after cementation ranged from 0.93 to 6.79. The color changes of ceramic veneer specimens using the shades of LV-3, HV+3, WO were 3.31,4.90 and 6.79, respectively (AE> 3.3). The AE values of the ceramic veneer specimens between the resin cements and corresponding try-in pastes were from 0.72 to 1.79 (except the shade of HV+3).Test 3 The effect of ceramic thickness on the color matching of ceramic veneersMaterials and Methods:18 artificial teeth (maxillary central incisors, Endura, Shofu) were selected and divided into three groups according to the color parameters of them, randomly. These artificial teeth were reduced according to the requirement of clinical veneer tooth preparation. IPS e.Max (HT A2) was used to fabricate the 0.50 mm,0.75 mm and 1.00 mm thick of ceramic veneers at the mesial section.18 ceramic veneer specimens were made into the identical curving of surface through wax impression replication technology and de-waxing casting method. The ceramic veneer specimens were bonded into the reduced artificial teeth with resin cement (TR shade,3M RelyXTM Veneer), respectively. Then, the color parameters of cemented ceramic veneer specimens were measured by a clinical spectrophotometer (Crystaleye, Olympus). The color differences of ceramic veneer specimens and A2 shade tab (Vitapan classical) were calculated. Two-way ANOVA was used to analyze the effect of the thickness of ceramic materials and section of ceramic veneer.Results:The color parameters of ceramic veneer specimens showed that L* values and a* values increased and b* values and C*ab values decreased with the increasing thickness of ceramic materials. The color differences (AE) of ceramic veneer specimens and A2 shade ranged from 2.17 to 3.68, and △E values decreased with the increasing thickness of ceramic materials. The color difference of different thickness of ceramic veneers was 0.45 (0.75-1.00 mm incisal section) to 2.82 (0.5-1.0 mm mesial section). The result of two-way ANOVA showed that the thickness of ceramic materials and the sections of ceramic veneers were significant difference of AE values of ceramic veneer and A2 shade tab (p< 0.001).Test 4 The effect of the thickness of ceramic materials and resin cement shades on the color matching of ceramic veneers in discolored of teethMaterial and methods:72 artificial maxillary central incisor teeth (C2 shade) were prepared according to veneer tooth preparation in practice. IPS e.max Press ceramic materials (LT A2 shade) were selected to fabricate the 0.50 mm and 0.75 mm thick of veneers at the mesial section. The ceramic veneer specimens were bonded to the artificial teeth by the 6 shades of resin cements (Variolink Veneer, shades of HV+3, LV-2, LV-3; and 3M RelyXTM Veneer, shades of WO, TR, A3). A clinical spectrophotometer (Crystaleye, Olympus) was used to measure the color parameters of the ceramic veneers after cementation; AE values of veneer and A2 shade tab (Vitapan classical) and C*ab values were calculated.Results:The result of Three-way ANOVA indicated that the color differences (AE value) of ceramic veneer and A2 shade tab were statistically significant difference in the thickness of ceramic materials, shades of resin cements and the measuring section (p< 0.001). The AE values ranged from 1.17 to 6.54. The color parameters of ceramic veneer specimens showed that L* values were low at the cervical and mesial sections and C*ab values high at the incisal section. There were significant differences between 0.50 mm thick ceramic veneers that exhibited higher AE values compared with veneers that were 0.75 mm in thickness.Conclusions1. Resin cements can affect the final color of ceramic veneers. The WO and HV+3 shades of resin cements increased the lightness and decreased the chroma of the disk-shaped ceramic veneers. LV-3 shade and brown shade of resin cement led to increase of the chroma of ceramic specimens.2. The LV-3, HV+3, WO shades were able to change the final color of a ceramic veneer. The color of resin cements and corresponding try-in pastes achieved high agreement (except the shade of HV+3)3. The thickness of ceramic materials was significant influence on the color parameter of ceramic veneer specimens. With the increasing of ceramic thickness, the values of ceramic veneer specimens increased and the chroma values decreased.4. The color matching of ceramic veneers was significant influenced by the thickness of ceramic materials, the shade of resin cements and the tooth section. |
PDF Full Text Request