Fabrication trueness and marginal quality of additively manufactured resin-based definitive laminate veneers with different restoration thicknesses

OBJECTIVES

To evaluate how restoration thickness (0.5 mm and 0.7 mm) affects the fabrication trueness of additively manufactured definitive resin-based laminate veneers, and to analyze the effect of restoration thickness and margin location on margin quality.

METHODS

Two maxillary central incisors were prepared either for a 0.5 mm- or 0.7 mm-thick laminate veneer. After acquiring the partial-arch scans of each preparation, laminate veneers were designed and stored as reference data. By using these reference data, a total of 30 resin-based laminate veneers were additively manufactured (n = 15 per thickness). All veneers were digitized and stored as test data. The reference and test data were superimposed to calculate the root mean square values at overall, external, intaglio, and marginal surfaces. The margin quality at labial, incisal, mesial, and distal surfaces was evaluated. Fabrication trueness at each surface was analyzed with independent t-tests, while 2-way analysis of variance was used to analyze the effect of thickness and margin location on margin quality (α = 0.05).

RESULTS

Regardless of the evaluated surface, 0.7 mm-thick veneers had lower deviations (P < 0.001). Only the margin location (P < 0.001) affected the margin quality as labial margins had the lowest quality (P < 0.001).

CONCLUSION

Restoration thickness affected the fabrication trueness of resin-based laminate veneers as 0.7 mm-thick veneers had significantly higher trueness. However, restoration thickness did not affect the margin quality and labial margins had the lowest quality.

CLINICAL SIGNIFICANCE

Laminate veneers fabricated by using tested urethane-based acrylic resin may require less adjustment when fabricated in 0.7 mm thickness. However, marginal integrity issues may be encountered at the labial surface.

Color Change of Laminate Veneer Restorations Applied to Bleached Teeth

OBJECTIVE

The aim of this study was to examine the color stability of laminate veneer restorations restored with CAD/CAM material applied to bleached teeth.

MATERIAL AND METHODS

In this study, 80 upper central teeth extracted because of periodontal, orthodontic or trauma problems were used. The teeth were embedded in acrylic blocks and divided into 8 groups (n=10). Groups A, B, C and D were bleached with vital bleaching agent before preparation, and teeth were prepared for laminate veneer restorations. Groups E, F, G and H were prepared without bleaching. Groups A and E were restored with A1 GC LiSi İnitial HT blocks, Groups B and F were restored with A1 GC LiSi İnitial LT blocks, Groups C and G were restored with A1 IPS Emax CAD HT blocks, Groups D and H were restored with A1 IPS Emax CAD LT blocks. All restorations were adhesively cemented and aged for 2 and 5 years with thermal cycle. Color measurements of the restorations at the beginning, after 2 and 5 years of aging were measured with a spectrophotometer.

RESULTS

All bleached groups had more color changes than the unbleached groups. The least color change after 2 years of aging was observed in GC LiSi Initial LT (ΔE00=0.81) and IPS Emax CAD LT (ΔE00=0.81) materials which were used on unbleached teeth and the most color change was observed in GC Initial LiSi HT (ΔE00=0.93) and IPS Emax CAD HT material (ΔE00=0.92) which were used on bleached teeth. After 5 years of aging, the least color change was observed in IPS Emax CAD LT (ΔE00=0.83) and GC LiSi Initial LT material (ΔE00=0.84) which were used on unbleached and the highest color change was observed in GC Initial LiSi HT (ΔE00=0.96) and IPS Emax CAD HT material (ΔE00=0.94) which were used on bleached teeth.

CONCLUSION

Bleaching and translucency affect the color stability. No difference was detected between the color changes of GC LiSi Initial and IPS Emax CAD materials. The increase in aging time increased the color changes of all materials.

CLINICAL SIGNIFICANCE

Bleaching and laminate veneer restorations may be preferred in many patients. For this reason, the long-term color change of laminate veneer restorations applied to bleached teeth is clinically very important. This study aimed to evaluate the effect of tooth bleaching on the long-term color change of laminate veneer restorations produced with different translucent CAD/CAM materials.

Entire Dental Arch Mesial Movement after Extraction of Maxillary Right Central Incisor due to Root Fracture Treated with Temporary Anchorage Devices

This case report describes a 19-year-old woman with skeletal Class I crowding and an unsalvageable maxillary right central incisor. She visited our clinic with the chief complaint of mobility of the maxillary right central incisor due to a traffic accident. After extraction of the maxillary right central incisor, the space was closed orthodontically. All the maxillary right teeth were moved mesially with an elastic chain attached to a palatal lever arm which was connected to palatal temporary anchorage devices (TADs). After orthodontic treatment had been completed, the maxillary right lateral incisor and peg-shaped left lateral incisor were restored with a porcelain laminate veneer. The maxillary right canine was morphologically reshaped and built up with composite resin. Consequently, esthetically ideal occlusion and functional lateral guidance with uncontacted molars were obtained. These results show that mesial movement of the entire dental arch with TADs is a useful orthodontic treatment option in patients in whom the maxillary central incisor has been extracted.

Clinical performance of laminate veneers: A review of the literature

PURPOSE

This narrative review aimed to survey the clinical outcomes of laminate veneers (LVs), including their survival and success rates.

STUDY SELECTION

An electronic search of MEDLINE/PubMed, Web of Science, Cochrane Library, and Google Scholar from 2000 to April 2023 was conducted using the keywords "laminate" OR "veneer" OR "porcelain" OR "feldspathic" OR "lithium disilicate" OR "composite resin" OR "zirconia" OR "survival" OR "success." Case reports, case series, reviews, abstracts, in vitro studies, and observational studies were excluded. Five researchers independently evaluated the titles and abstracts of all identified studies.

RESULTS

A total of 55 studies were identified. None of the studies met the criteria for zirconia LVs. According to the studies in this review, LVs fabricated with feldspathic porcelain, leucite-reinforced glass ceramics (LRG), and lithium disilicate ceramics (LDS) exhibited satisfactory survival and success rates. Furthermore, hydrofluoric acid etching followed by silane priming of the surface of ceramic LVs is necessary for improved clinical outcomes. The extent of dentin exposure significantly decreases the success rate of ceramic LVs. An appropriate adhesive luting process is required to achieve the long-term success of ceramic LVs. Dentin exposure should be minimized or sealed during tooth preparation to achieve a reliable and durable bond between LVs and abutment teeth.

CONCLUSIONS

Based on this narrative review of the literature, the use of silica-based ceramic feldspathic porcelain, LRG, and LDS is recommended for LVs.

Influence of an internal firing of feldspathic porcelain before or after sintering on adaptation of high-translucent zirconia laminate veneers

The aim of the present study was to evaluate the influence of two different internal surface treatments, namely, the firing of feldspathic porcelain before or after zirconia sintering, on the marginal and internal adaptation of laminate veneers (LVs) made of high-translucent zirconia. A total of 33 zirconia LVs were fabricated using a CAD/CAM system and divided into three groups based on the internal surface treatment method: the pre-firing (PRE) group involved firing feldspathic porcelain before zirconia sintering, the post-firing (POS) group involved firing feldspathic porcelain after zirconia sintering, and the no treatment (NT) group involved no application of feldspathic porcelain. The adaptation of the LVs was measured using a silicone replica technique. Data were analyzed using the Kruskal-Wallis and Steel-Dwass tests (α = .05). The POS group showed significantly higher marginal discrepancy values than the PRE group across all sites. The internal space values of the PRE groups were significantly lower than those of the NT group at all sites. The internal firing of feldspathic porcelain before zirconia sintering resulted in better marginal adaptation of the high-translucent zirconia LVs than the internal firing of feldspathic porcelain after zirconia sintering. The internal firing of feldspathic porcelain before zirconia sintering can achieve uniform internal adaptation of high-translucent zirconia LVs.

Fracture strength and bonding interface morphology of CAD/CAM-fabricated ceramic laminate veneers on bleached enamel treated with two different antioxidants

This study aimed to investigate the effects of two antioxidants and their application time on the fracture strength of computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated ceramic laminate veneers to bleached enamel, as well as their effects on the bonding interface micromorphology. Eight groups were set: Group NC (without bleaching and antioxidant treatment); Group NA (bleaching without antioxidant treatment); Group SA30, SA60, SA120 and Group PAC30, PAC60, PAC120 (bleaching and treating with sodium ascorbate or proanthocyanidins for 30, 60, and 120 min, respectively). After cementation of veneers, fracture strength values and failure modes were analyzed. The bonding interface morphology was observed by confocal laser scanning microscopy. The fracture strength was impaired when cementation procedure was performed immediately after bleaching. This reduction in fracture strength was reestablished with antioxidant treatment, and an extended treatment time contributed to better improvement. The resin tags at the bonding interfaces of the bleached enamel were impaired. Antioxidant treatments were able to reverse this unfavorable trend.

Clinical survival of No-prep indirect composite laminate veneers: a 7-year prospective case series study

BACKGROUND

The no preparation technique which is a reversible form of treatment characterized by the absence of tooth tissue preparation and preserves the soft tissue architecture while preserving all natural tooth structures is indicated in cases where the tooth structure allows material to be added. The aim of this study is to evaluate the clinical performance and survival rates of indirect composite laminate veneers with no preparation after 7 years.

MATERIALS AND METHODS

A total of 80 indirect composite veneers were placed on maxillary anterior teeth in 35 patients (n = 80). Diastema (n = 64), wedge tooth anomalies (n = 9) and re-shaping (n = 7) were the main indications for veneer treatments. All laminate veneers were fabricated with an indirect microhybrid composite material (Gradia, GC Dental). No tooth preparation was performed. Light-cured resin cement (Choice 2, Bisco) was used to lute the veneers. Composite veneers were evaluated using Modified United States Public Health Service criteria. Survival rates of the veneers were calculated using Kaplan-Meier statistics. The data containing the results of the USPHS criteria at baseline, 2 years and 7 years was statistically analyzed using Wilcoxon Signed Rank test at the 0.05 level of significance.

RESULTS

The overall survival rate was 91.3%. After 7 years, 7 absolute failures including 4 debonding (marginal adaptation, score 4) and 3 fractures (fracture of restoration, score 3) were noted. Color match was scored as 1 (n = 34) and 2 (n = 15). Slightly rough surfaces (41 of 73 laminates) and slight marginal discoloration (15 of 73 laminates) were noted. The overall scores after 84 months were significantly higher than the baseline scores for the marginal adaptation (p = 0.008), color match (p = 0.000), marginal discoloration (p = 0.000), surface roughness (p = 0.000), and fracture of restoration (p = 0.001) criteria.

CONCLUSIONS

In this study, indirect composite veneers without any preparation on maxillary anterior teeth showed acceptable performance in terms of both survival rate and quality of restorations. This procedure offers a predictable and successful treatment that ensures maximum preservation of the intact tooth.

The effect of resin cement shade and restorative material type and thickness on the final color of resin-matrix ceramics

PURPOSE

This study aims to evaluate the effects of cement shade, restorative material type, and thickness on the final color of resin-matrix ceramics.

METHODS

Ninety A2 shade resin-matrix ceramic specimens were prepared from Vita Enamic, GC Cerasmart, and Lava Ultimate at 0.5 and 1.0 mm thicknesses. Sixty resin cement disks were fabricated from different shades (A1, A3O, B05, and TR) of RelyX Ultimate at 0.1 mm thickness. CIE color coordinates were measured using a spectrophotometer, and color differences (∆ E 00 ) were calculated. Data were statistically analyzed (P =0.05).

RESULTS

The ΔE 00 values were influenced by the cement shade, restorative material type, thickness, and their interactions ( P < 0.05). A3O cement caused clinically unacceptable values for all groups at 0.5 mm thickness and GC at 1.0 mm thickness. A1 and TR cement shades demonstrated visually perceptible but clinically acceptable values, except for VE-A1 and LU-A1 at 0.5 mm thickness. The ∆E 00 values of the B05 cement shade were lower than the visually perceptible threshold for both thicknesses except for GC at 0.5 mm thickness.

CONCLUSIONS

The shade of the resin cement and the type and thickness of the resin-matrix ceramic material significantly affected the resulting final color. To provide a shade matching with natural dentition and to obtain esthetic restorations, especially for the anterior teeth, the resin cement shade and resin-matrix ceramic material should be carefully selected.

OCT evaluation of the internal adaptation of ceramic veneers depending on preparation design and ceramic thickness

OBJECTIVES

In-vitro evaluation of the influence of preparation design and thickness of ceramic veneers on the interfacial bond using optical coherence tomography (OCT).

METHODS

Sixty-four central incisors were randomly assigned to four preparation designs differing from no to complete dentine exposure (n = 16 each): non-prep (NP), minimal-invasive (MI, no dentine exposure), semi-invasive (SI, 50% dentine) and invasive (I, 100% dentine). Ceramic veneers (IPS InLine Veneer) of two thicknesses (0.2-0.5 mm (T1) and > 0.5-1.2 mm (T2)) were etched, silanized, and adhesively luted (Optibond FL, Variolink Veneer). After water storage (37 °C, 21d), thermocycling (2000 cycles, 5°-55 °C), and mechanical loading (2 + 1 million cycles, 50 + 100 N) specimens were imaged by spectral-domain OCT (Telesto II, Thorlabs). Adhesive defects at the ceramic-composite and tooth-composite interfaces were quantified on 35 equidistantly distributed OCT B-scans (length, %). Statistical differences were verified with Wilcoxon-/Mann-Whitney-U-test (α = 0.05).

RESULTS

Adhesive defects appeared in all groups at both interfaces, albeit to differing extents (0.1 - 31.7%). NP and MI veneers showed no significant differences at the interfaces (p_i > 0.05). In groups, SI and I, significantly more adhesive defects appeared at the tooth-composite compared to the veneer-composite interface (p_i ≤ 0.039). The following preparation designs and veneer thicknesses showed differences (p_i ≤ 0.021): Veneer-composite: NP-T1 < I-T1, MI-T1 < I-T1, I-T1 > I-T2; Tooth-composite: NP-T1 < SI-T1, NP-T1 < I-T1, NP-T2 > MI-T2, MI-T1 < SI-T1, MI-T1 < I-T1, SI-T1 < I-T1, MI-T2 < SI-T2, MI-T2 < I-T2.

SIGNIFICANCE

The interface adhesion of ceramic veneers was influenced by the preparation design and the veneer thickness. A ceramic thickness of at least 0.5 mm and a preparation without exposing dentine is advantageous for the interfacial bond.

Marginal discrepancy and load to fracture of monolithic zirconia laminate veneers: The effect of preparation design and sintering protocol

To investigate and analyze the impact of teeth preparation designs and sintering protocol on marginal fit and fracture resistance of monolithic translucent zirconia laminate veneers. A total of 40 extracted intact human maxillary central incisors were assigned into 4 groups (n=10/each group) to investigate 2 variables: (1) the design of tooth preparation (a 1.5 mm incisal reduction with or without palatal chamfer) and (2) the two different sintering programs used for translucent zirconia restoration (standard or speed sintering procedure). Marginal discrepancy was evaluated using a digital microscope. The specimens were loaded to failure in the compression mode, using a universal testing machine with a crosshead speed of 0.5 mm/min. Marginal adaptation of monolithic translucent zirconia laminates are affected by both tooth preparation design and sintering protocol. However, resistance to fracture of translucent zirconia laminates has affected mainly by sintering procedure regardless the teeth preparation design used.

Comparison of conventional ceramic laminate veneers, partial laminate veneers and direct composite resin restorations in fracture strength after aging

OBJECTIVES

The objectives of this study were to test the fracture strength in vitro of laminate veneers, partial laminate veneers and composite restorations after aging and analyze the failure mode.

METHODS

Forty extracted, sound human teeth were selected and divided into four groups: 1) Control group (CG); 2) Conventional Laminate Veneer (CLV); 3) Partial Laminate Veneer (PLV); 4) Direct Composite Resin (DCR). Laminate veneer preparations with incisal overlap were made in group CLV whereas only incisal preparations were made with a 1 mm bevel in group PLV and DCR. The indirect restorations were luted with a resin composite and the DCR group was restored with a direct resin composite restoration. The restored teeth were subsequently aged by thermocycling (20.000 cycles, 5-55 degrees C). Subsequently, the fracture strength was tested by a load to failure test at 135° on the incisal edge. A failure analysis was performed using light microscopy. The results were analyzed using Shapiro-Wilk and Kruska-Wallis test.

RESULTS

After thermocycling, one sample from group CLV presented a premature adhesive failure and was excluded. Three restorations from groups PLV and DCR presented small cracks but were taken to the fracture test. After aging mean fracture load + SD (N) were: Group DCR (n = 10): 385 ± 225; Group CG (n = 10): 271 ± 100; Group PLV (n = 10): 266 ± 69; Group CLV (n = 9): 264 ± 66. Fracture strength means from groups CLV and PLV did not differ statistically from each other nor from control (p = 0.05). In the group CLV the root fracture was the most occurring fracture. In groups PLV and DCR, material cohesive failures and a mix (adhesive, tooth and material cohesive) failures were most observed.

SIGNIFICANCE

This in vitro study showed for the first time that partial laminate veneers can exhibit fracture strength values similar to direct composite restorations or conventional ceramic laminate veneers. All three restorative procedures presented clinically acceptable values of fracture strength. Even though three samples from groups PLV and three from DCR presented small cracks after thermocycling, these cracks do not appear to have a negative effect on the fracture strength.

Sub-ablative Er,Cr:YSGG laser irradiation under all-ceramic restorations: effects on demineralization and shear bond strength

This study evaluated the caries resistant effects of sub-ablative Er,Cr:YSGG laser irradiation alone and combined with fluoride in comparison with fluoride application alone on enamel prepared for veneer restorations. And also, evaluated these treatments' effects on the shear bond strength of all-ceramic veneer restorations. One hundred and thirty-five human maxillary central teeth were assigned to groups of 1a-control, 1b-laser treated, 1c-fluoride treated, 1d-laser + fluoride treated for shear bond testing and to groups of 2a-positive control(non-demineralised), 2b-laser treated, 2c-fluoride treated, 2d-laser + fluoride treated, 2e-negative control (demineralised) for microhardness testing (n = 15, N = 135). Demineralisation solutions of microhardness measurements were used for the ICP-OES elemental analysis. The parameters for laser irradiation were as follows: power output, 0.25 W; total energy density, 62.5 J/cm² and energy density per pulse, 4.48 J/cm² with an irradiation time of 20 s and with no water cooling. Five percent NaF varnish was used as fluoride preparate. ANOVA and Tukey HSD tests were performed (α = 5%). Surface treatments showed no significant effects on shear bond strength values (p = 0.579). However, significant differences were found in microhardness measurements and in elemental analysis of Ca and P amounts (p < 0.01). Surface-treated groups showed significantly high VNH values and significantly low ICP-OES values when compared with non-treated (-control) group while there were no significance among surface-treated groups regarding VHN and ICP-OES values. Sub-ablative Er,Cr:YSGG treatment alone or combined with fluoride is as an effective method as at least fluoride alone for preventing the prepared enamel to demineralization with no negative effect on shear bond strength.

Effect of newly Developed Resin Cements and Thermocycling on the Strength of Porcelain Laminate Veneers

AIM

The aim of this study was to determine the effect of different luting cements and accelerated artificial aging (AAA) in the fracture resistance of porcelain laminate veneers (PLVs).

MATERIALS AND METHODS

A total of 80 disc-shaped specimens were prepared using computer-aided design/computer-aided milling technology from lithium disilicate glass-ceramic blocks. Specimens (0.5 mm thick, 10 mm diameter) were divided into eight groups of 10 specimens per group. The control groups consisted of specimens without cement and not subjected to AAA (CN group) and specimens prepared without cement but subjected to AAA (CW group). The experimental groups were subjected to AAA and cemented with Variolink Veneer, Variolink Esthetic LC, Variolink Esthetic DC, RelyX Unicem, RelyX Veneer, or RelyX Ultimate. Specimens were individually tested for biaxial flexure on a universal testing machine. One-way analysis of variance and the Tukey's post hoc test were used to compare the groups' significance statistically (α = 0.05).

RESULTS

The loads to fracture (LTF) values in the CN group were higher than those in the CW and experimental groups. The lowest LTF value was in the CW group (31.5 ± 9.5 N) and the highest LTF value in the CN group (56.7 ± 10.6 N). Tukey's post hoc test demonstrated a statistically significant (p < 0.01) difference between the CN group and the other groups.

CONCLUSION

Artificial aging had a significant effect on the LTF value of the tested specimens compared with the resin cements used. Cohesive failure within the PLVs was the most common mode of failure.

CLINICAL SIGNIFICANCE

Fatigue strength of dental ceramics and moisture was shown to affect the mechanical properties of all-ceramic restorations. All-ceramic material is extremely sensitive to humidity and thermocycling.

How will surface treatments affect the translucency of porcelain laminate veneers?

PURPOSE

The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses.

MATERIALS AND METHODS

A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-µm Al₂O₃; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (α=0.05).

RESULTS

There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768).

CONCLUSION

The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values.