Adhesion of veneering resins to polymethylmethacrylate-based CAD/CAM polymers after various surface conditioning methods

Effect of filler contents on the bond strength of CAD/CAM resin crowns: New resin primer versus conventional silane agents

Purpose This study aims to evaluate the effects of resin primers containing methyl methacrylate (MMA) and silane agent on the bonding effectiveness of indirect resin composite blocks with three different filler contents.Methods A commercially available computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite block and two experimental resin composite blocks with different filler contents were alumina-blasted and two surface treatments (primer and silane agent) were applied. The resin cement was built up, and the micro-tensile bond strength (μTBS) was measured after 24 hours, 1 month or 3 months of water storage (n = 24 per group). The fracture surfaces after μTBS measurements and resin block/cement interface were observed by scanning electron microscopy (SEM).Results The primer treatment group showed a significantly higher bond strength than the silane group only in F0 (filler content 0 wt%) group (P < 0.001). In the primer group, F0 and F41 (filler content 41 wt%) groups showed significantly higher bond strengths than F82 (filler content 82 wt%) group (P < 0.001). In contrast, in the silane group, F41 group showed significantly higher bond strength than F0 and F82 groups (P < 0.001), and F82 group showed significantly higher bond strength than F0 group (P < 0.001). SEM revealed that the matrix resin was partially destroyed on the fracture surface of the primer group, and an uneven interface surface was observed compared with that of the silane group.Conclusions MMA-containing primers showed higher bonding effectiveness to CAD/CAM resin composite blocks than the silane treatment.

Lithium disilicate occlusal surfaces on acrylic resin denture teeth in a mandibular implant-retained overdenture opposed by a maxillary removable complete denture: A clinical report

Decreased masticatory efficiency, loss of vertical dimension of occlusion, and loss of maxillomandibular relationships are common in relation to the wear experienced by the artificial teeth in removable complete dentures and implant-retained overdentures. To prevent early surface loss, the occlusal surfaces of acrylic resin denture teeth were replaced with adhesively luted lithium disilicate onlays in this patient's prostheses.

A method of fabricating computer aided design-computer aided manufacturing implant-supported provisional restorations with clear aligner attachments: A technical report

OBJECTIVE

To provide a method of fabricating implant-supported provisional restorations with orthodontic attachments by digital technique.

CLINICAL CONSIDERATION

Polymethylmethacrylate (PMMA) provisional restorations are usually necessary when dental implants are serving as anchors for orthodontic treatments. For clear aligner treatment, it is possible to setup the teeth virtually and determine the final position of the implants, indicating that the provisional restorations can be also predetermined. However, attachments on PMMA restorations have a higher risk of debonding due to low bond strength. To fabricate provisional restorations with predetermined shape and position and no risk of attachment debonding immediately after implant placement, a digital workflow is introduced in this article.

CONCLUSIONS

By combining "pick-up" technique and prefabricated monolithic PMMA provisional restorations, this technique is recommended for making implant-supported provisional restorations with integrated orthodontic attachments based on the digitally designed positions of the teeth.

CLINICAL SIGNIFICANCE

The present protocol describes a digital workflow of designing and manufacturing implant-supported PMMA provisional restorations with orthodontic attachments in the predetermined position of implants, which should lead to more reliable and predictable orthodontic treatment outcomes.

Bonding ability of resin cements to different types of CAD/CAM composite blocks

This study investigated the bonding performance of two different types of resin cements to computer-aided design/computer-aided manufacturing (CAD/CAM) composite blocks based on the shear bond strength (SBS) test. A silane-containing self-adhesive resin cement (Panavia SA Cement Universal) and resin luting cement (Block HC Cem) with a primer, were used. Specimens were fabricated from three different types of CAD/CAM composite blocks, and their surfaces were blasted with alumina. Resin cements were bonded to the specimens, and their SBSs were measured after 15 min, 24 h, and after being subjected to thermal cycling for 10,000 and 30,000 cycles. Three-way ANOVA for bond strength revealed that CAD/CAM composite block, resin cement and storage time significantly influenced the SBS values, and the three-way interactions between the evaluated factors, and all the interactions were significant. It was concluded that the bonding performance of resin cements to CAD/CAM composite blocks were material and storage period dependent.

Comparison of CAD-CAM and traditional chairside processing of 4-unit interim prostheses with and without cantilevers: Mechanics, fracture behavior, and finite element analysis

STATEMENT OF PROBLEM

How processing by computer-aided design and computer-aided manufacturing (CAD-CAM) or traditional chairside fabrication techniques affects the presence of defects and the mechanical properties of interim dental prostheses is unclear.

PURPOSE

The purpose of this in vitro study was to compare the effects of CAD-CAM versus traditional chairside material processing on the fracture and biomechanical behavior of 4-unit interim prostheses with and without a cantilever.

MATERIAL AND METHODS

Two types of 4-unit interim prostheses were fabricated with abutments on the first premolar and first mandibular molar, one from a prefabricated CAD-CAM block and one with a traditional chairside polymer-monomer autopolymerizing acrylic resin (n=10). Both groups were assessed by compressive strength testing and additionally with or without a cantilevered second molar by using a universal testing machine with a 5-kN load cell. A finite element model (FEM) was built by scanning both prosthesis designs. Finite element analysis (FEA) replicated the experimental conditions to evaluate the stress distribution through the prostheses.

RESULTS

Interim fixed prostheses manufactured by CAD-CAM showed significantly higher mean fracture loading values (3126 N to 3136 N) than for conventionally made interim fixed prostheses (1287 N to 1390 N) (P=.001). The presence of a cantilever decreased the fracture loading mean values for CAD-CAM (1954 N to 2649 N), although the cantilever did not influence the traditional prostheses (1268 N to 1634 N). The highest von Mises stresses were recorded by FEA on the occlusal surface, with the cantilever design, and at the transition region (connector) between the prosthetic teeth.

CONCLUSIONS

Interim partial prostheses produced by CAD-CAM had a higher strength than those manufactured traditionally. The presence of a cantilever negatively affected the strength of the prostheses, although the structures manufactured by CAD-CAM still revealed high strength and homogenous stress distribution on occlusal loading.

Repair bond strength and surface topography of resin-ceramic and ceramic restorative blocks treated by laser and conventional surface treatments

This study intended to compare the repair bond strength of computer-aided design/computer-aided manufacturing (CAD/CAM) blocks consisting of resin and feldspathic ceramics following different surface treatments using the microtensile bond strength (μTBS) test. Ten specimens were prepared with 4 mm height for Vita Enamic (VE), Lava Ultimate (LU), Vita Mark II (VM), and thermocycled (10,000 cycle, 5-55°C). Each material was categorized into one of five subgroups according to following surface treatments: (a) bur grinding (BG), (b) hydrofluoric acid etching (HF), (c) neodymium-doped yttrium aluminum garnet (Nd:YAG or NY), (d) erbium-doped yttrium aluminum garnet (Er:YAG or EY), and (e) erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG or ECY) laser conditioning. After surface treatment procedures, specimens were properly restored to 4 mm high with a micro-hybrid composite resin. Bar specimens (1 × 1 × 8 mm) were obtained using a low-speed cutting machine and then thermocycled (10,000 cycle, 5-55°C). The μTBS was tested at 1 mm/min crosshead speed, and failure modes were evaluated. Data were analyzed with two-way ANOVA and post hoc Tukey tests. LU-BG showed significantly higher μTBS (32.94 ± 5.80 MPa) compared to LU-laser groups (p < .05). VE-BG showed significantly higher μTBS (22.06 ± 4.26 MPa) compared to other VE groups (p < .05). Among the laser groups, the NY laser produced the lowest (p < .05) μTBS for LU (13.42 ± 3.44 MPa) and VE (2.27 ± 0.85 MPa), while EY showed the highest (p < .05). Laser-treated VM groups were all prefailured. VM-HF produced a higher μTBS (18.73 ± 3.75 MPa) than VM-BG (5.05 ± 1.76 MPa) (p < .05).

Influence of surface treatment on bonding of resin luting cement to CAD/CAM composite blocks

The aim of this study was to determine the influence of different surface treatments of CAD/CAM composite blocks on bonding effectiveness of resin cements, based on the shear bond strength test and the surface science examination. Specimens were fabricated from two types of CAD/CAM composite blocks (Cerasmart and VITA Enamic), and the specimen surfaces were alumina sandblasted. Specimen surfaces were treated with i) silane, ii) primer, and iii) silane+primer, then two types of cements (Block HC Cem and Super Bond) were bonded. After 24 h storage, bond strengths were measured. Surface free energy measurements were performed of the treated CAD/CAM composite blocks surfaces. The groups ii) and iii) showed significantly higher bond strengths than the group i), apart from VITA Enamic with Block HC Cem. Although the total surface free energy showed different trends in different surface treatments, a similar trend was found in both CAD/CAM composite blocks.

Effect of surface treatments on the bond strength of indirect resin composite to resin matrix ceramics

PURPOSE

The purpose of this study was to evaluate the shear bond strength (SBS) of an indirect resin composite (IRC) to the various resin matrix ceramic (RMC) blocks using different surface treatments.

MATERIALS AND METHODS

Ninety-nine cubic RMC specimens consisting of a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) were divided randomly into three surface treatment subgroups (n = 11). In the experimental groups, untreated (Cnt), tribochemical silica coating (Tbc), and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser irradiation (Lsr) with 3 W (150 mJ/pulse, 20 Hz for 20 sec.) were used as surface treatments. An indirect composite resin (IRC) was layered with a disc-shape mold (2 × 3 mm) onto the treated-ceramic surfaces and the specimens submitted to thermal cycling (6000 cycles, 5 – 55℃). The SBS test of specimens was performed using a universal testing machine and the specimens were examined with a scanning electron microscope to determine the failure mode. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α=.05).

RESULTS

According to the two-way ANOVA, only the surface treatment parameter was statistically significant (P<.05) on the SBS of IRC to RMC. The SBS values of Lsr-applied RMC groups were significantly higher than Cnt groups for each RMC material, (P<.05). Significant differences were also determined between Tbc surface treatment applied and untreated (Cnt) PIHC materials (P=.039).

CONCLUSION

For promoting a reliable bond strength during characterization of RMC with IRC, Nd:YAG laser or Tbc surface treatment technique should be used, putting in consideration the microstructure and composition of RMC materials and appropriate parameters for each material.

Effectiveness of current adhesive systems when bonding to CAD/CAM indirect resin materials: A review of 32 publications

The purpose of this review was to assess the available literature regarding bonding between current adhesive systems and computer-aided design/computer-aided manufacturing (CAD/CAM) indirect resin materials, to provide clinicians with a comparative overview of the relevant bonding procedures. An electronic search was performed through PubMed based on the keywords CAD/CAM and dental bonding. Additional relevant literature was obtained from the citations in the articles. A total of 313 papers were identified, of which 281 were excluded as being unsuitable, and an additional 3 papers were identified, giving a total of 32 articles that are included in this review. Based on this survey, it is recommended that microretentive surfaces should be generated by either blasting or hydrofluoric acid etching. This initial process should be followed by silanization to ensure chemical adhesion prior to bonding to CAD/CAM indirect resin composite materials (including Lava Ultimet, KATANA AVENCIA block, Gradia Block, Cerasmart, Paradigm, and Block HC) and CAD/CAM polymer-infiltrated ceramics (such as Vita Enamic). The use of materials containing methyl methacrylate (MMA) also appears to improve the bonding of CAD/CAM poly(methyl methacrylate) (PMMA) resin materials (including XHIPC-CAD/CAM, artBloc Temp, and Telio).

Shear Bond Strength of Nanohybrid Composite to the Resin Matrix Ceramics After Different Surface Treatments

OBJECTIVE

The purpose of this study was to evaluate the effects of different surface treatments on the shear bond strength (SBS) of a composite resin to the various resin matrix ceramics (RMC).

BACKGROUND

Clinical applications of physical and chemical surface conditioning methods may be required for RMC to optimize the adhesion of additional resin materials.

MATERIALS AND METHODS

Ninety-nine RMC specimens (6 × 6 × 2 mm) were prepared from a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) block with a cutting machine under copious water. All specimens divided randomly into three surface treatment subgroups (n = 11): (1) untreated (Cnt), (2) tribochemical silica coated (Tbc), and (3) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiated with 3 W (150 mJ/pulse, 20 Hz) for 20 sec. A nanohybrid composite resin was layered with a disc-shape mold (2 × 3 mm) onto the ceramics and submitted to thermal cycling (3000 cycles, 5-55°C). The SBS test of specimens was performed using a universal testing machine. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05).

RESULTS

The type of RMC, surface treatments, and their interactions was statistically significant on SBS, according to the ANOVA (p < 0.05). Both the Tbc and Lsr surface treatments significantly increased the SBS values of FHC (p < 0.001), while significant increases were observed only for Lsr0applied RNC and Tbc applied PIHC groups (p < 0.001).

CONCLUSIONS

The tribochemical silica coating and laser irradiation techniques may be suitable for improving the surface topography of specific types of RMC. While the same surface treatment technique may not provide similar successful results for all types of RMC, it is recommended to choose the most effective and reliable technique for clinical application.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system

Objective

The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system.

Material and Methods

Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive).

Results

PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths.

Conclusion

A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

Adhesive bonding to polymer infiltrated ceramic

Aim of this study was to investigate the mechanism of adhesive bonding to the polymer-infiltrated ceramic VITA Enamic [VE]. Shear bond strength was measured with three resin composite cements: RelyX Unicem 2 Automix, Clearfil SA and Variolink II on polished surfaces of VE and its components silicate ceramic [SC] and polymer [PM] (n=12). Further, the effect of etching VE with 5% HF for 15-240 s and the application of silane coupling agents was analyzed in a screening test (n=6). Shear bond strength measurements were performed after 24 h of water storage at 37°C. Significant bonding to polished substrates could only be achieved on VE and SC when silane coupling agents were used. Etching of VE with 5% HF increased shear bond strength. Following silanization of etched VE, a further increase in shear bond strength could be established. Etching for more than 30 s did not improve shear bond strength.

Effects of tributylborane-activated adhesive and two silane agents on bonding computer-aided design and manufacturing (CAD/CAM) resin composite

The present study was conducted to evaluate the effects of an experimental adhesive agent [methyl methacrylate-tributylborane liquid (MT)] and two adhesive agents containing silane on the bonding between a resin composite block of a computer-aided design and manufacturing (CAD/CAM) system and a light-curing resin composite veneering material. The surfaces of CAD/CAM resin composite specimens were ground with silicon-carbide paper, treated with phosphoric acid, and then primed with either one of the two silane agents [Scotchbond Universal Adhesive (SC) and GC Ceramic Primer II (GC)], no adhesive control (Cont), or one of three combinations (MT/SC, MT/GC, and MT/Cont). A light-curing resin composite was veneered on the primed CAD/CAM resin composite surface. The veneered specimens were subjected to thermocycling between 4 and 60 °C for 10,000 cycles, and the shear bond strengths were determined. All data were analyzed using analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). MT/SC (38.7 MPa) exhibited the highest mean bond strengths, followed by MT/GC (30.4 MPa), SC (27.9 MPa), and MT/Cont (25.7 MPa), while Cont (12.9 MPa) and GC (12.3 MPa) resulted in the lowest bond strengths. The use of MT in conjunction with a silane agent significantly improved the bond strength. Surface treatment with appropriate adhesive agents was confirmed as a prerequisite for veneering CAD/CAM resin composite restorations.

Evaluation of the accuracy of 7 digital scanners: An in vitro analysis based on 3-dimensional comparisons

STATEMENT OF PROBLEM

As digital impressions become more common and more digital impression systems are released onto the market, it is essential to systematically and objectively evaluate their accuracy.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the trueness and precision of 6 intraoral scanners and 1 laboratory scanner in both sextant and complete-arch scenarios. Furthermore, time of scanning was evaluated and correlated with trueness and precision.

MATERIAL AND METHODS

A custom complete-arch model was fabricated with a refractive index similar to that of tooth structure. Seven digital impression systems were used to scan the custom model for both posterior sextant and complete arch scenarios. Analysis was performed using 3-dimensional metrology software to measure discrepancies between the master model and experimental casts.

RESULTS

Of the intraoral scanners, the Planscan was found to have the best trueness and precision while the 3Shape Trios was found to have the poorest for sextant scanning (P<.001). The order of trueness for complete arch scanning was as follows: 3Shape D800 >iTero >3Shape TRIOS 3 >Carestream 3500 >Planscan >CEREC Omnicam >CEREC Bluecam. The order of precision for complete-arch scanning was as follows: CS3500 >iTero >3Shape D800 >3Shape TRIOS 3 >CEREC Omnicam >Planscan >CEREC Bluecam. For the secondary outcome evaluating the effect time has on trueness and precision, the complete- arch scan time was highly correlated with both trueness (r=0.771) and precision (r=0.771).

CONCLUSIONS

For sextant scanning, the Planscan was found to be the most precise and true scanner. For complete-arch scanning, the 3Shape Trios was found to have the best balance of speed and accuracy.

Effects of cementation surface modifications on fracture resistance of zirconia

OBJECTIVES

To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia.

METHODS

Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending.

RESULTS

Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength.

SIGNIFICANCE

While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia.

Repairability of CAD/CAM high-density PMMA- and composite-based polymers

OBJECTIVE

The study aimed to analyse the shear bond strength of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA)- and composite-based polymer materials repaired with a conventional methacrylate-based composite after different surface pretreatments.

METHODS

Each 48 specimens was prepared from six different CAD/CAM polymer materials (Ambarino high-class, artBloc Temp, CAD-Temp, Lava Ultimate, Telio CAD, Everest C-Temp) and a conventional dimethacrylate-based composite (Filtek Supreme XTE, control) and aged by thermal cycling (5000 cycles, 5-55 °C). The surfaces were left untreated or were pretreated by mechanical roughening, aluminium oxide air abrasion or silica coating/silanization (each subgroup n = 12). The surfaces were further conditioned with an etch&rinse adhesive (OptiBond FL) before the repair composite (Filtek Supreme XTE) was adhered to the surface. After further thermal cycling, shear bond strength was tested, and failure modes were assessed. Shear bond strength was statistically analysed by two- and one-way ANOVAs and Weibull statistics, failure mode by chi(2) test (p ≤ 0.05).

RESULTS

Shear bond strength was highest for silica coating/silanization > aluminium oxide air abrasion = mechanical roughening > no surface pretreatment. Independently of the repair pretreatment, highest bond strength values were observed in the control group and for the composite-based Everest C-Temp and Ambarino high-class, while PMMA-based materials (artBloc Temp, CAD-Temp and Telio CAD) presented significantly lowest values. For all materials, repair without any surface pretreatment resulted in adhesive failures only, which mostly were reduced when surface pretreatment was performed.

CONCLUSIONS

Repair of CAD/CAM high-density polymers requires surface pretreatment prior to adhesive and composite application. However, four out of six of the tested CAD/CAM materials did not achieve the repair bond strength of a conventional dimethacrylate-based composite.

CLINICAL RELEVANCE

Repair of PMMA- and composite-based polymers can be achieved by surface pretreatment followed by application of an adhesive and a conventional methacrylate-based composite.

Effect of different adhesives combined with two resin composite cements on shear bond strength to polymeric CAD/CAM materials

This study tested the impact of different adhesives and resin composite cements on shear bond strength (SBS) to polymethyl methacrylate (PMMA)- and composite-based CAD/CAM materials. SBS specimens were fabricated and divided into five main groups (n=30/group) subject to conditioning: 1. Monobond Plus/Heliobond (MH), 2. Visio.link (VL), 3. Ambarino P60 (AM), 4. exp. VP connect (VP), and 5. no conditioning-control group (CG). All cemented specimens using a. Clearfil SA Cement and b. Variolink II were stored in distilled water for 24 h at 37 °C. Additionally, one half of the specimens were thermocycled for 5,000 cycles (5 °C/55 °C, dwell time 20 s). SBS was measured; data were analyzed using descriptive statistics, four- and one-way ANOVA, unpaired two-sample t-test and Chi(2)-test. CAD/CAM materials without additional adhesives showed no bond to resin composite cements. Highest SBS showed VL with Variolink II on composite-based material, before and after thermocycling.

The effect of different pretreatment methods of PMMA-based crowns on the long-term tensile bond strength to dentin abutments

OBJECTIVES

The objective of the study was to test the effect of different pretreatments on tensile bond strength (TBS) of adhesively bonded CAD/CAM-generated polymethyl methacrylate (PMMA) crowns to dentin.

MATERIALS AND METHODS

Two hundred human molars were prepared and divided into 20 groups (n = 10/group). PMMA crowns were pretreated thusly: Monobond Plus/Heliobond (MH), Visio.link (VL), Ambarino P60 (AM), VP connect (VP), and nontreated as control groups (CG). Two resin cements were used for cementation of crowns: Clearfil SA Cement (CSA) and Variolink II (VAR). TBS was measured initially (24 h water storage, 37 °C) and after aging (5,000 thermal cycles, 5/55 °C). TBS was analyzed using one-way ANOVA with Scheffé post hoc, unpaired Student t, Mann-Whitney U, Kruskal-Wallis H, and chi-squared tests.

RESULTS

Within CSA, pretreatment with MH and VL showed higher initial TBS compared with AM-treated groups. All other groups showed no statistical differences. For MH, VL, AM, and VP in combination with CSA, a negative impact of aging was observed (p < 0.001), whereas in all VAR groups, no impact was measured. Pretreatment with MH (p = 0.001) and VP (p = 0.008) presented higher initial TBS for CSA than for VAR. After aging, MH (p = 0.025) and VL (p = 0.034) cemented with VAR showed higher results than CSA.

CONCLUSIONS

All tested groups showed very low TBS values. Pretreatments with MH, VL, and VP have minimally improved the tensile strength after aging.

CLINICAL RELEVANCE

Although the tensile strength results were low, crowns adhesively cemented with pretreatments with MH, VL, and VP showed, after aging, a higher tensile strength than nontreated groups.