Two-part implant abutments with titanium and ceramic components: Surface modification affects retention forces-An in-vitro study

OBJECTIVES

Two-part abutments consist of titanium base and ceramic coping. Their long-term success is largely determined by the mechanical stability. The aim of the present study was to investigate the retention forces of two-part implant abutments. The study included zirconia and lithium disilicate ceramics copings, with different surface treatments and resin-based luting agents.

MATERIAL AND METHODS

The analysis of retention forces was based on a total of 70 test specimens. Seven surface modifications and three resin-based luting agents were employed for the bonding of components in the seven groups (n = 70). All surfaces of titanium bases-except for a control-were pretreated with aluminum oxide blasting, either alone or in combination with surface activating primers. Surfaces of ceramic copings were also treated mechanically by sandblasting, either alone or with acid etching or different primers. All specimens underwent thermal aging (10⁴ cycles, 5°C/55°C). The retention forces between the two parts were measured with a pull-off test. The results were analyzed by two-way ANOVA statistics. Fracture patterns were evaluated by light and scanning electron microscopy.

RESULTS

No mechanical pretreatment of the titanium (group 2) base resulted in the lowest retention. The combination with Monobond plus leads to the highest pull-off forces for both ceramic materials.

CONCLUSIONS

Surface modifications and resin-based agents influence the retention of components of two-part abutments. Lithium disilicate ceramic copings reached comparable results of retention to the typically used zirconia copings.

Effect of Simplified Bonding on Shear Bond Strength between Ceramic Brackets and Dental Zirconia

The aim of this study was to evaluate the long term stability of shear bond strength (SBS) when 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing universal adhesive was used in the ceramic bracket bonding on dental zirconia. Twenty human maxillary incisors were collected. The ceramic bracket was bonded on the buccal enamel surface after the acid-etching and orthodontic primer application (Group CON). Sixty zirconia specimens were sintered, sandblasted and divided into three experimental groups; group CP—ceramic primer followed by an orthodontic primer; group U—universal adhesive; group CU—ceramic primer followed by a universal adhesive. For each specimen, the bracket was bonded onto the treated surface with composite resin (Transbond XT, 3M ESPE). The SBS tested before (CON0, CP0, U0, CU0) and after the artificial aging (CON1, CP1, U1, CU1). The data were statistically analyzed with the Kruskal–Wallis test at a significance level of 0.05. The mean SBS of CON0, CP0, U0 and CU0 were within the clinically acceptable range without significant differences. After the aging process, SBS decreased in all groups. Among the aged groups, CP1 showed the highest SBS. Based on the results, when bonding ceramic brackets to a dental zirconia surface, we can conclude that ceramic primer used with an orthodontic primer, rather than using a universal adhesive, is recommended.

Adhesion behavior of conventional and high-translucent zirconia: Effect of surface conditioning methods and aging using an experimental methodology

OBJECTIVE

Evaluate the adhesive behavior of conventional and high-translucent zirconia after surface conditioning and hydrothermal aging.

MATERIALS AND METHODS

Conventional (ZrC) and high-translucent zirconia (ZrT) specimens were divided into six groups: without surface treatment (ZrC and ZrT), air-borne particle abrasion with 50-μm Al₂ O₃ sized particles (ZrC-AO and ZrT-AO), and tribochemical treatment with 30-μm silica modified Al₂ O₃ sized particles (ZrC-T and ZrT-T). Zirconia specimens were treated using an MDP-containing universal adhesive and bonded to two resins blocks with an adhesive luting cement. Microbar specimens with cross-sectioned areas of 1 mm² were achieved. Half of the microbars were subjected to hydrothermal aging. Bond strength was evaluated by microtensile bond strength test and statistically evaluated by the Weibull analysis.

RESULTS

Roughness of the ZrC-AO and ZrT-AO groups were statistically higher. Bond strength analysis revealed higher bond strength for ZrC-AO and ZrC-T groups compared to ZrT-AO and ZrT-T, respectively. Mixed failure was the most frequent for the mechanically treated groups, while no cohesive failures were obtained.

CONCLUSION

Lower values of bond strength were obtained for the mechanically treated high-translucent zirconia groups when compared to their conventional zirconia counterparts. Mechanical surface treatment significantly improved the bond strength to conventional and high-translucent zirconia.

CLINICAL SIGNIFICANCE

Mechanical surface treatment (air-borne particle abrasion or tribochemical treatment) associated with the use of universal adhesives containing MDP could provide a durable bonding to conventional and high-translucent zirconia.

Bond strength between MDP-based cement and translucent zirconia

The purpose was to evaluate the bond strength between adhesive cement and translucent zirconia in comparison to conventional zirconia. Four brands of translucent zirconia (BruxZir^® HT, Lava™ Plus, Prettau^® Anterior, and Prettau^® Zirconia) and one conventional zirconia (Kavo Everest^® ZS) were evaluated. Specimens were divided into groups depending on the pretreatment of the cementation surface of the zirconia: as-produced, hydrofluoric acid treatment, or sandblasted. The groups underwent three different procedures of artificial aging: water storage (24 h), 5,000 thermocycles, or long-term aging, (water storage 150 days including 37,500 thermocycles) before shear bond strength testing. Sandblasting treatment increased the bond strength significantly for all the brands of zirconia, irrespective of artificial aging procedures, in comparison to the control group. Bond strength between adhesive cement to translucent zirconia is equivalent to conventional zirconia. Sandblasting creates a cementation surface that is more durable than as-produced or hydrofluoric-acid-treated, irrespective of type of zirconia.

The effect of fusion sputtering surface treatment on microshear bond strength of zirconia and MDP-containing resin cement

PURPOSE

The aim of this study is to evaluate the effect of fusion sputtering surface treatment on the microshear bond strength of zirconia and self-adhesive MDP-containing resin cement.

MATERIALS

Thirty-six zirconia discs received one of the following treatments: fusion sputtering, airborne particle abrasion with 50-μm aluminum oxide particles, while as-sintered specimens served as a control. Four treated zirconia samples from each group were examined using 3D laser scanning microscope to assess the surface roughness and scanning electron microscope to study the surface topography. The specimens of each group were bonded to composite micro discs using MDP-containing self-adhesive resin cement (Panavia SA cement plus). The specimens were thermocycled for 5000 cycles between 5 and 55 °C. Microshear bond strength test was performed using universal testing machine until bonding failure. Failure modes and fracture surfaces was evaluated using scanning electron microscope.

RESULTS

The fusion sputtering surface treatment significantly influenced zirconia-resin bond strength (p < 0.001). The highest mean microshear bond strength value was observed in fusion sputtering treatment (23.18 ± 4.38). The lowest value was observed in as-sintered zirconia surfaces (7.23 ± 6.26).

SIGNIFICANCE

Fusion sputtering surface treatment enhanced the microshear bond strength of zirconia and resin cement.

Effects of alumina-blasting pressure on the bonding to super/ultra-translucent zirconia

OBJECTIVES

Translucent zirconia has brought the advantages such as less tooth preparation, biological compatibility, high strength, good mechanical properties, and less antagonist wear. This study's aim was to elucidate how clinically relevant surface treatments; alumina-abrasion and priming effect on bond strength of Y-PSZ in three different translucency grades after long-term water storage.

MATERIALS AND METHODS

Three highly translucent Y-PSZ grades were ground flat with #600-grit SiC paper. Four different surface treatments (untreated, alumina blasting at 0.1 MPa or 0.2 MPa or 0.4 MPa) and two resin cements (PANAVIA V5 and PANAVIA SA CEMENT PLUS AUTOMIX) were tested. The bonded specimens were stored in water for 1 day, 30 days and 150 days and tensile bond strength (TBS) were measured with universal testing machine at a crosshead speed of 2 mm/min (n=10). The surface roughness (Sa) measurement and surface morphology analysis without alumina-blasting pressure (untreated) and with alumina-blasting pressures (0.1 MPa, 0.2 MPa and 0.4 MPa) for three different zirconia grades were evaluated with 3D-Laser Scanning Confocal Microscope.

RESULTS

Different alumina-blasting pressures and different storage periods affected the bonding of resin cement to translucent zirconia. The Weibull moduli increased in some groups after 150 days storage. After 1 day and 30 days storage, 0.4 MPa alumina-blasting pressure provided superior bond strength, however, after 150 days, 0.2 MPa gave reliable and stable bond strength.

SIGNIFICANCE

Alumina-blasting pressure of 0.2 MPa was the most effective for reliable and durable bonding performance to translucent zirconia after long-term water storage.

Different surface modifications combined with universal adhesives: the impact on the bonding properties of zirconia to composite resin cement

OBJECTIVE

The purpose of this study was to analyze the impact of plasma treatment and (universal adhesives) UAs on the bonding properties of zirconia.

MATERIAL AND METHODS

Zirconia specimens (N = 744; n = 186/pretreatment) were prepared, highly polished, and pretreated: (i) plasma (oxygen plasma, 10s, 5 mm), (ii) airborne-particle abrasion (alumina, 50 μm, 0.05 MPa, 5 s, 10 mm), (iii) airborne-particle abrasion + plasma, and (iv) without pretreatment (highly polished surface). Surface roughness (R_a) and surface free energy (SFE) were measured (n = 6/pretreatment). Tensile bond strength (TBS) specimens (n = 180/pretreatment) were further divided (n = 18/conditioning): Clearfil Ceramic Primer (PCG), All-Bond Universal (ABU), Adhese Universal (AU), Clearfil Universal Bond (CUB), G-Premio Bond (GPB), Futurabond U (FBU), iBond Universal (IBU), One Coat 7 Universal (OCU), Scotchbond Universal (SBU), and no conditioning. PCG was luted with Panavia F2.0 and the remaining groups with DuoCem. After storage in distilled water (24 h; 37 °C) and thermocycling (5000×; 5 °C/55 °C), TBS was measured and fracture types (FTs) were determined. Data were analyzed using univariate ANOVA with a partial eta square (ƞ_P²), the Kruskal-Wallis H, the Mann-Whitney U, and the Chi² test (P < .05).

RESULTS

Plasma treatment resulted in an increase of SFE but had no impact on R_a. Airborne-particle abrasion resulted in the highest R_a and a higher TBS when compared with plasma and non-treatment. SBU and AU obtained a higher TBS when compared with PCG. OCU, FBU, ABU, IBU, and GPB indicated comparable TBS to PCG. CUB revealed the lowest TBS.

CONCLUSIONS

Plasma treatment cannot substitute airborne-particle abrasion when bonding zirconia but MDP-containing adhesives are essential for successful clinical outcomes.

CLINICAL RELEVANCE

Airborne-particle abrasion with a low pressure (0.05 MPa) in combination with UAs promotes the clinical success of adhesively bonded zirconia restorations.

Influence of Primers and Additional Resin Layer on Zirconia Repair Bond Strength

PURPOSE

To evaluate the influence of alloy/zirconia primer and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing resin layer treatments on the shear bond strength (SBS) of composite resin to zirconia after aging.

MATERIALS AND METHODS

Sixty zirconia (Y-TZP) blocks were air-abraded (35-µm Al₂ O₃ ) and divided into 6 experimental groups (n = 10) in terms of primer/resin layer as follows: (1) control, without any primer or resin; (2) AP, Alloy Primer; (3) ZPP, Z-Prime Plus; (4) PL/ZPP, Z-Prime Plus with light polymerization; (5) AP+SEB, Alloy Primer along with light-cured bonding resin of a self-etch adhesive system (SE Bond); and (6) ZPP+SEB, Z-Prime Plus with SE Bond. After composite resin placement and light polymerization, the specimens were stored in distilled water (37°C for 4 months) and thermal-cycled for 6000 cycles. The SBS was tested with a universal testing machine. Statistical analysis of the SBS data was performed with one-way ANOVA, followed by HSD Tukey test (α = 0.05).

RESULTS

There were significant differences between the groups (p < 0.001, F = 116.5). All the groups revealed significantly higher SBS than the control (p < 0.001). ZPP+SEB group exhibited the highest SBS (16.14 ± 2.52 MPa) and AP group the lowest SBS (7.00 ± 1.97 MPa) among experimental groups; both had significant differences with the other groups (p < 0.001). There were no significant differences between ZPP, PL/ZPP, and AP+SEB groups (p > 0.05).

CONCLUSIONS

The bond strength between zirconia ceramic and composite resin was affected by different primers/resin layer. Applying an MDP-containing resin layer along with both primers resulted in significant enhancement of SBS. This improvement for Z-Prime Plus was significantly higher than that of Alloy Primer.

Zirconia Primers Improve the Shear Bond Strength of Dental Zirconia

PURPOSE

Various resin cements and priming agents are available for adhesive luting of zirconia restorations. The purpose of this study was to investigate how cement type and priming protocol affect the shear bond strength on zirconia ceramics.

MATERIALS AND METHODS

Yttria-stabilized tetragonal zirconia polycrystalline ceramic cylinders were bonded to flat zirconia ceramic surfaces using 7 commercially available resin cements. Ten specimens of each cement group were pretreated with a universal primer, and 10 specimens per group were bonded without pretreatment. In addition, 10 specimens per group were pretreated with system-specific zirconia primers, which were available for 3 cements. Altogether, 170 bonded specimens were water-stored, thermal-cycled, and then submitted to shear bond strength tests. The shear bond strength and the fracture types were documented. Differences in shear bond strengths were assessed using 2-way ANOVA with post-hoc test (α = 0.05). A point-biserial correlation was run between the fracture patterns and the shear bond strengths.

RESULTS

The mean shear bond strengths of cements in the unprimed group showed large variations between 2.52 ± 3.01 (mean ± SD) MPa and 33.15 ± 7.35 MPa. Pretreating the specimens with a universal primer improved the shear bond strengths significantly in all groups (p < 0.05) with a range of 21.80 ± 12.51 to 57.20 ± 11.40 MPa. The system-specific primers also improved the shear bond strength significantly, compared to the unprimed group (p < 0.01); however, only one system-specific primer achieved a shear bond strength superior to the universal primer (p < 0.01). There was also a statistical correlation between the fracture type and the shear bond strength (p < 0.0005), with cohesively fractured specimens showing higher shear bond strengths (37.24 ± 19.87 MPa) than adhesively fractured specimens (23.10 ± 17.65 MPa) (p < 0.001).

CONCLUSION

Using universal primer can enhance the maximal shear bond strength of zirconia.

Influência do método de limpeza da zircônia na adesão da prótese após a contaminação com saliva

Resumo Introdução A contaminação das restaurações de zircônia com saliva antes da cimentação influencia na resistência da adesão face à afinidade com os íons da saliva. Objetivo Analisar os métodos de limpeza da zircônia na adesão à dentina após a contaminação com saliva. Material e método Oitenta amostras de zircônia com dimensão 4×11×3 mm foram cortadas de blocos pré-sinterizados (3Y-TZP, In-Ceram - VITA) e sinterizadas. Após a sinterização, as amostras foram jateadas com partículas de óxido de alumínio, lavadas em água destilada e divididas em dois grupos com base no tipo de cimento de adesão: RelyX U200 Clicker® (grupo R) ou Multilink N® (grupo M). As amostras foram divididas em quatro subgrupos (n=10) de acordo com os métodos de limpeza e com o tipo de cimento: RG1 e MGI (sem contaminação com saliva); RG2 e MG2 (sem contaminação e limpeza com Ivoclean®); RG3 e MG3 (com contaminação e limpeza com água); RG4 e MG4 (com contaminação e limpeza com Ivoclean®). Após a cimentação, as amostras foram armazenadas em água por 10 dias. A resistência da adesão foi determinada pelo teste de cisalhamento. Resultado Os resultados mostraram que a maior e a menor resistência foram do Grupo RG2 e MG2, respectivamente. Entre as amostras cimentadas com RelyXTM, somente o grupo RG4 apresentou diferença na resistência da adesão (p=0,018) em relação aos demais subgrupos. Entre os grupos cimentados com Multilink N®, não houve diferença estatística (p>0,05) na resistência. Conclusão Os resultados mostraram que o agente de limpeza Ivoclean® não foi efetivo na descontaminação e não influenciou na resistência ao cisalhamento.

Effects of laser treatments on surface roughness of zirconium oxide ceramics

BACKGROUND

The aim of this study was to analyze the surface roughness of yttrium stabilized tetragonal polycrystalline zirconia (Y-TZP) ceramics after different laser treatments (CO_2, ER: YAG).

METHODS

5x5x2 mm rectangular prisms of forty eight Y-TZP (Zirkonzahn) ceramic specimens were prepared. In order to standardize surfaces, 600-, 1200- grid silicon carbide papers were used to gradually ground wet on 300 rpm grinding machine for 10 s. Eight groups (n = 6) were randomly formed from the specimens of each ceramic as control (GroupC), sandblasted (GroupS), two different CO₂ laser treatments (Group3W: 3 W and 382 w/cal, Group4W: 4 W and 509w/cal) and four different Er: YAG laser treatments (Group150SP: 150 mJ and 10-Hz with 100μS; Group150SSP: 150 mJ and 10-Hz with 300μS; Group300SP: 300 mJ and 10-Hz with 100μS; Group300SSP: 300 mJ and 10-Hz with 300μS). A profilometer was used to conduct surface roughness measurements (Ra). Surface morphologies of the specimens were evaluated under SEM after laser treatment.

RESULTS

To analyze the data one-way ANOVA and to compare the mean values Tukey HSD tests (α = .05) were used. One - way ANOVA results showed that Group S had the highest Ra value and Group150 SP had the lowest. After sandblasting group the highest value was seen in Group4W. There were no statistically significant differences among Group C, Group3W, Group150SSP, Group300SP, and Group300SSP.

CONCLUSIONS

The study showed that surface roughness of zirconium oxide ceramics was increased with CO2 laser.

High Bond Durability of Universal Adhesives on Glass Ceramics Facilitated by Silane Pretreatment

Objective:

This study aimed to investigate the long-term effectiveness of ceramic–resin bonding with universal adhesives in non–silane-pretreated and silane-pretreated modes after 10,000 cycles of thermal aging.

Methods and Materials:

All Bond Universal, Adhese Universal, Clearfil Universal Bond, and Single Bond Universal were selected. Etched lithium disilicate glass ceramics were prepared, randomly assigned to groups, and pretreated with or without ceramic primer containing silane coupling agent prior to the application of universal adhesive (ie, silane-pretreated or non–silane-pretreated mode). The shear bond strength (SBS), microleakage, and field-emission scanning electron microscopy images of the ceramic–resin interfaces were examined after 24 hours of water storage or 10,000 thermal cycles. Light microscopy and confocal laser scanning microscopy (CLSM) were performed to analyze marginal sealing ability.

Results:

SBS and microleakage percentage were significantly affected by bonding procedure (non–silane-pretreated or silane-pretreated mode) and aging (24 hours or 10,000 thermal cycles). After the universal adhesives in the non–silane-pretreated mode were aged, SBS significantly decreased and microleakage percentage increased. By contrast, the SBS of Adhese Universal, Clearfil Universal Bond, and Single Bond Universal decreased, and the microleakage percentage of all of the adhesives increased in the silane-pretreated mode. However, after aging, the SBS of the silane-pretreated groups were higher and their microleakage percentages lower than those of the non–pretreated groups. In the non–silane-pretreated mode, adhesive failure was dominant and gaps between composite resin and the adhesive layer were significant when observed with CLSM.

Conclusions:

The simplified procedure reduced the ceramic–resin bonding effectiveness of universal adhesives after aging, and additional silane pretreatment helped improve the long-term durability.

Bond to Zirconia Ceramic: Evaluation of Different Primers and a Universal Adhesive

Objective:

The aim of the study was to evaluate the effect of a universal adhesive and different primers on the bond strength to zirconia ceramic.

Materials and Methods:

Seventy-five zirconia ceramic samples were obtained and divided into five groups (n=15): G1–Scothbond Universal (SBU); G2 – silane + SBU; G3 - Signum Zirconia Bond; G4 - Z-Prime Plus; G5 - MZ Primer. A cone of composite resin was built. The specimens were stored in 100% relative humidity with distilled water at 37°C for 48 h and then submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The type of failure that occurred during the de-bonding procedure was analyzed.

Results:

The mean results of the bond strength test (MPa) followed by the same letter represent no statistical difference by ANOVA and Tukey’s post-hoc test (p<0.05): G2=27.55a (±6.99), G4=23.71a (±5.65), G1=22.64a (±5.67), G5=13.64b (±5.49), G3=7.54c (±4.75). G2 and G4 exhibited predominantly cohesive failure in the composite resin cone. G1 and G5 had predominantly mixed failures, and G3 exhibited only adhesive failures.

Conclusion:

The SBU and Z-Prime Plus provided higher bond strength to zirconia ceramic.

Assessment of Bonding Effectiveness of Adhesive Materials to Tooth Structure using Bond Strength Test Methods: A Review of Literature

Background

The rapid developments in the field of adhesive dental materials have led to improvements in many aspects of clinical dentistry. Adhesive bond strength plays an important role in determining the clinical performance and longevity of dental restorations. Nevertheless, bond strength tests have never been well-standardized, although a number of important recommendations have been made.

Objective

The aim of this paper is to critically review the validity of different bond strength testing methods for assessment of bonding effectiveness of adhesive materials to tooth structure and discuss factors that may affect bond strength measurement.

Data Collection

Relevant literature published between 1983 and 2018 was collected and reviewed from the PubMed database and Google scholar resources.

Review Results

Results of the current bond testing methods should be used to compare materials tested under the same laboratory settings, but they shouldn't be used to make direct inferences on their clinical behaviour. Shear and micro-shear tests, result in non-uniform stress distribution, stress concentration at the substrate area, and predominantly tensile stresses rather than shear stresses. Micro-tensile bond tests provide many advantages over the shear tests, although these methods are technique sensitive and labour intensive.

Conclusion

Bond strength testing methods should be well-standardized, but there are many factors that cannot be fully controlled which leads to variation and misinterpretation of the data about the bonding abilities of adhesives.

Clinical Significance

New adhesive materials should be subjected to a combination of testing protocols to properly assess their bonding effectiveness.

Influence of the amount of tooth surface preparation on the shear bond strength of zirconia cantilever single-retainer resin-bonded fixed partial denture

PURPOSE

Conventional resin-bonded fixed partial dentures (RBFPDs) are usually made with a two-retainer design. Unlike conventional RBFPDs, cantilever resin-bonded fixed partial dentures (Cantilever RBFPDs) are, for their part, made with a single-retainer design. The aim of this study was to compare the effect of tooth surface preparation on the bond strength of zirconia cantilever single-retainer RBFPDs. The objective is to evaluate the shear bond strength of these single-retainer RBFPDs bonded on 3 different amount of tooth surface preparation.

MATERIALS AND METHODS

Thirty extracted bovine incisors were categorized to 3 groups (n=10), with different amounts of tooth surface preparations. Teeth were restored with single-retainer RBFPDs with different retainer surfaces: large retainer of 32 mm²; medium retainer of 22 mm²; no retainer and only a proximal connecting box of 12 mm². All RBFPDs were made of zirconia and were bonded using an adhesive system without adhesive capacity. Shear forces were applied to these restorations until debonding.

RESULTS

Mean shear bond strength values for the groups I, II, and II were 2.39±0.53 MPa, 3.13±0.69 MPa, and 5.40±0.96 MPa, respectively. Statistical analyses were performed using a one-way ANOVA test with Bonferroni post-hoc test, at a significance level of 0.001. Failure modes were observed and showed a 100% adhesive fracture.

CONCLUSION

It can be concluded that the preparation of large tooth surface preparation might be irrelevant. For zirconia single-retainer RBFPD, only the preparation of a proximal connecting box seems to be a reliable and minimally invasive approach. The differences are statistically significant.

Dental Cements for Luting and Bonding Restorations: Self-Adhesive Resin Cements

Self-adhesive resin cements combine easy application of conventional luting materials with improved mechanical properties and bonding capability of resin cements. The presence of functional acidic monomers, dual cure setting mechanism, and fillers capable of neutralizing the initial low pH of the cement are essential elements of the material and should be understood when selecting the ideal luting material for each clinical situation. This article addresses the most relevant aspects of self-adhesive resin cements and their potential impact on clinical performance. Although few clinical studies are available to establish solid clinical evidence, the information presented provides clinical guidance in the dynamic environment of material development.

Bond strength of resin cement to zirconia treated in pre-sintered stage

PURPOSE

Aim of this study was to evaluate the tensile bond strength (TBS) between resin cement and zirconia surface treated in different sintering stages.

MATERIALS AND METHODS

Eighty zirconia discs having final dimensions of 12 mm diameter and 3.2 mm thickness were milled then divided into three main groups according to the type of surface treatment performed (group 1: air abrasion using 50 µm Al₂O₃ particles, group 2: silica coating using Rocatec soft, and group 3: a control group receiving no surface treatment). Groups 1 and 2 were divided into two subgroups each according to the stage in which the surface treatment was performed (subgroup A; surface treatment performed in the pre-sintered stage and subgroup B; surface treatment performed in the post-sintered stage). Discs were later bonded to composite core materials using resin cement then tested for TBS either being subjected to 3 days of water storage or 150 days of water storage and 37,500 thermal cycles.

RESULTS

Long-term aging caused a significant decrease in TBS of all subgroups except the subgroup air-abraded in the post-sintered stage. After long-term aging, the group silica coated in the pre-sintered stage showed the significantly lowest TBS compared to all other groups. There was also no significant difference between the subgroups air-abraded and silica coated in the pre-sintered stage. All specimens in the control group debonded during long-term aging.

SIGNIFICANCE

Air-abrading zirconia with Al₂O₃ at a reduced pressure in the pre-sintered stage may result in durable bond strength to resin cement.

Evaluation of the Effect of Different Types of Abrasive Surface Treatment before and after Zirconia Sintering on Its Structural Composition and Bond Strength with Resin Cement

This study evaluated the effect of air abrasion before and after sintering with different particle type, shape, and size on the surface morphology, monoclinic phase transformation, and bond strength between resin cement and zirconia surface using primer containing silane and MDP. Airborne particle abrasion (APA) was performed on zirconia before and after sintering with different particle shape and size (50 μm Al₂O₃ and 25 μm silica powder). 120 square shaped presintered zirconia samples (Amann Girrbach) were prepared (3 mm height × 10 mm width × 10 mm length) and polished with grit papers #800, 1000, 1200, 1500, and 2000. Samples were divided into 6 groups according to surface treatment-group A: (control) no surface treatment; group B: APA 50 μm Al₂O₃ before sintering (BS); group C: APA 50 μm Al₂O₃ after sintering (AS); group D: APA25 μm silica powder (BS); group E: APA25 μm silica powder (AS) at a pressure of 3.5 bar; and group F: APA 25 μm silica powder (AS) at a pressure of 4 bar. Samples were analyzed using XRD, AFM, and SEM. The samples were submitted to shear bond strength (SBS) test. A dual cure resin cement (RelyX Ultimate) and primer (Scotchbond Universal) were used. Data were analyzed with ANOVA and Tukey test (α ≥ 0.05). APA in group B significantly increased the surface roughness when compared to all other groups. A significant monoclinic phase transformation (t-m) value was observed in groups C and F and a reverse transformation occurred in presintered groups. The SBS value of group A was 11.58 ± 1.43 and the highest significant shear bond strength value was for groups B (15.86 ± 1.92) and C (17.59 ± 2.21 MPa) with no significant difference between them. Conclusions. The use of APA 50 μm Al₂O₃ before sintering and the application of primer containing MDP seem to be valuable methods for durable bonding with zirconia. The use of APA 50 μm Al₂O₃ after sintering induced the highest (t-m) phase transformation.

Effect of surface treatments with acid solutions on the surface roughness of an Yttrium-Tetragonal Zirconia Polycrystal

Background

The purpose of this in vitro study was to evaluate the effect of conventional surface treatment with acid solutions on the surface roughness of a zirconia-based ceramic.

Material and Methods

Specimens of yttrium-tetragonal zirconia polycrystal (Y-TZP) -based ceramic were fabricated (5.0 x 5.0 x 2.0 mm, n=40). The specimens were submitted to the tested surface treatment method and divided into 4 groups (n=10): no treatment-control (GI), airborne 110 µm aluminum oxide particle abrasion for 1 minute-conventional method (GII); etching with 48% hydrofluoric acid for 2 minutes (GIII), and nitric acid/hydrofluoric acid etching for 2 minutes (GIV). The surface roughness (Ra) test was performed, followed by AFM analysis. The results were analyzed by ANOVA and the Tukey test, with the level of significance set at a=.05.

Results

The surface treatment with acid solutions (0.16 ± 0.02-GIII; 0.11 ± 0.01-GIV) promoted a significant increase in roughness, with higher mean Ra values of Y-TZP (μm) compared to control (0.06 ± 0.01-GI) (p >.05), and lower values compared to the conventional method (0.21 ± 0.06-GII). The aluminum oxide particle treatment resulted in deep microretentions forming sharp Y-TZP peaks compared to only microretentions with acid solution treatments.

Conclusions

All Y-TZP treatments effectively promoted microretention in the ceramic. Hydrofluoric acid (48%) proved to be more effective in increasing the Ra of Y-TZP than the nitric acid/hydrofluoric acid treatment. Atomic force microscopy images revealed that both acid solutions modified the surface of the Y-TZP in a uniform manner.

Key words:Zirconia, surface modification, roughness, yttria-stabilized tetragonal zirconia polycrystal.

The effect of continuous application of MDP-containing primer and luting resin cement on bond strength to tribochemical silica-coated Y-TZP

Objectives

This study investigated the effect of continuous application of 10-methacryloyloxydecyldihydrogen phosphate (MDP)-containing primer and luting resin cement on bond strength to tribochemical silica-coated yttria-stabilized tetragonal zirconia polycrystal (Y-TZP).

Materials and Methods

Forty bovine teeth and Y-TZP specimens were prepared. The dentin specimens were embedded in molds, with one side of the dentin exposed for cementation with the zirconia specimen. The Y-TZP specimen was prepared in the form of a cylinder with a diameter of 3 mm and a height of 10 mm. The bonding surface of the Y-TZP specimen was sandblasted with silica-coated aluminium oxide particles. The forty tribochemical silica-coated Y-TZP specimens were cemented to the bovine dentin (4 groups; n = 10) with either an MDP-free primer or an MDP-containing primer and either an MDP-free resin cement or an MDP-containing resin cement. After a shear bond strength (SBS) test, the data were analyzed using 1-way analysis of variance and the Tukey test (α = 0.05).

Results

The group with MDP-free primer and resin cement showed significantly lower SBS values than the MDP-containing groups (p < 0.05). Among the MDP-containing groups, the group with MDP-containing primer and resin cement showed significantly higher SBS values than the other groups (p < 0.05).

Conclusions

The combination of MDP-containing primer and luting cement following tribochemical silica coating to Y-TZP was the best choice among the alternatives tested in this study.

Effects of different ceramic primers and surface treatments on the shear bond strength of restorative composite resin to zirconium

Background and aims

Data are limited about the effect of ceramic primers on the bond of zirconia to restorative resin composite. The aim of this study was to assess the effect of different surface treatments and two ceramic primers on shear bond strength (SBS) of zirconia to restorative resin composite.

Materials and methods

100 samples of zirconium ceramic blocks were randomly divided into 5 groups (n = 20) and received the following surface treatments: a)Control groupb)AL₂O₃ abrasionc)Nd:YAG laserd)Er:YAG lasere)Bur preparation.Next, each group was divided into two subgroups of 20. In ten out of 20 specimens in each group, monobond plus and Tetric ceram composite resin were applied on the surface. ZPrime Plus and Elite composite were applied on the surfaces of the remaining 10 specimens in each group. Samples were then subjected to shear bond strength test in a universal testing machine until fracture. The mean SBS were calculated and statistically analyzed by two-way ANOVA and T-Test. P < 0.05 was considered statistically significant.

Results

In ZPrime plus subgroups, diamond bur yielded the highest bond strength. Laser groups showed no significant difference with the control group. In monobond plus subgroups, SBS of air abrasion and diamond bur subgroups was highest and Nd:YAG laser showed the lowest SBS. The lowest bond strength belonged to the Nd:YAG laser subgroup of monobond plus group.

Conclusions

Type of surface preparation significantly affected the bond strength.

Effect of tribochemical treatments and silane reactivity on resin bonding to zirconia

OBJECTIVE

The aim of the study was to assess the roughness, structure and bond strength with zirconia of four grit-blasting treatments combined with three silane types, the reactivity of which was evaluated, as well.

METHODS

The grit-blasted treatments performed on zirconia (Lava) were alumina (ALU), CoJet (COJ), SilJet (SLJ) and SilJet Plus (SJP, with silica-encapsulated silane). The other two silanes selected were the S-Bond (SB, prehydrolyzed) and Clearfil Ceramic Primer Plus (CP, prehydrolyzed with 10-MDP). The activity of the silanols in the silanes was evaluated by FTIR spectroscopy. Optical profilometry and Raman microspectroscopy were used for the assessment of roughness (Sa, Sz, Sdr parameters) and structure (monoclinic volume-Vm) of zirconia, before (REF) and after grit-blasting, and a shear bond strength (SBS) with a flowable resin composite, for the investigation of the bonding capacity of the treatments.

RESULTS

Only SB demonstrated reactive silanols. CP and the SJP silanes were mostly in a polymerized siloxane state. Roughness was increased after grit-blasting as follows: ALU>SLJ,SJP>COJ>REF (Sa,Sz) and ALU>SLJ,COJ,SJP>REF (Sdr). ALU demonstrated the highest Vm (7.52%) from all other treatments (4.16-4.81%) and the REF (0%). COJ and SLJ showed the highest SBS (14-15.94MPa) regardless of the silane type used. SJP showed no significant differences from SLJ-SB and COJ-SB. Weibull analysis showed a reliability (β) ranking of COJ, SJP, SLJ, ALU-CP>ALU-SB>REF and a characteristic life (η) ranking of COJ, SLJ, ≥SLJ-SB, SJP, ALU≥ALU-SB,REF-CP>REF-SB.

SIGNIFICANCE

The reactivity of the silanes used showed great variations to support a predictable effect in all treatments. CP with deactivated silanols demonstrated a) the most reliable and strongest treatment with a silica-rich powder (COJ), despite the lowest Sa,Sz substrate values and b) high strength with a low-silica powder (SLJ) with higher Sa,Sz substrate values. Therefore, it may be concluded that 10-MDP greatly contributes to the bonding mechanism of the silane containing primers.

Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

OBJECTIVES

To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al₂O₃) particles at different pressures.

MATERIALS AND METHODS

Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ² tests (α = 0.05).

RESULTS

The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure.

CONCLUSIONS

CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.

Deposition of crystalline hydroxyapatite nano-particle on zirconia ceramic: a potential solution for the poor bonding characteristic of zirconia ceramics to resin cement

The poor bonding strength of zirconia to different dental substrates is one of the challenging issues in restorative dentistry. Hydroxyapatite is an excellent biocompatible material with fine bonding properties. In this study, it was hypothesized that hydroxyapatite coating on zirconia would improve its bond strength. Forty-five zirconia blocks were prepared and randomly divided into three groups: hydroxyapatite coating, sandblasting, and no preparation (control). The blocks were bonded to cement and the micro-shear bond strength was measured following load application. The bond strength values were analyzed with the Kruskal-Wallis test in 3 groups and paired comparisons were made using the Mann-Whitney U test. The failure patterns of the specimens were studied by a stereomicroscope and a scanning electron microscope and then analyzed by the chi-square test (significance level = 0.05). Deposition of hydroxyapatite on the zirconia surface significantly improved its bond strength to the resin cement in comparison with the control specimens (p < 0.0001). Also, the bond strength was similar to the sandblasted group (p = 0.34). The sandblasted and control group only showed adhesive failure, but the hydroxyapatite coated group had mixed failures, indicating the better quality of bonding (p < 0.0001). As a final point, hydroxyapatite coating on the zirconia surface improved the bond strength quality and values.

Adhesive Bonding to Computer-aided Design/ Computer-aided Manufacturing Esthetic Dental Materials: An Overview

AIM

To review the adhesive bonding to different computer-aided design/computer-aided manufacturing (CAD/CAM) esthetic restorative materials.

BACKGROUND

The use of CAD/CAM esthetic restorative materials has gained popularity in recent years. Several CAD/ CAM esthetic restorative materials are commercially available. Adhesive bonding is a major determinant of success of CAD/ CAM restorations. Review result: An account of the currently available bonding strategies are discussed with their rationale in various CAD/ CAM materials.

CONCLUSION

Different surface treatment methods as well as adhesion promoters can be used to achieve reliable bonding of CAD/CAM restorative materials. Selection of bonding strategy to such material is determined based on its composition. Further evidence is required to evaluate the effect of new surface treatment methods, such as nonthermal atmospheric plasma and self-etching ceramic primer on bonding to different dental ceramics.

CLINICAL SIGNIFICANCE

An understanding of the currently available bonding strategies to CA/CAM materials can help the clinician to select the most indicated system for each category of materials.

Effect of Sandblasting Angle and Distance on Biaxial Flexural Strength of Zirconia-based Ceramics

AIM

Surface treatment is necessarily required for bonding of zirconia to the veneering porcelain and luting cements. Sandblasting is the most common and probably the most efficient surface treatment method. Sandblasting roughens the surface and may affect the flexural strength of zirconia. Different sandblasting protocols may yield variable results. This study sought to assess the effect of sandblasting angle and distance on the biaxial flexural strength of zirconia-based ceramics.

MATERIALS AND METHODS

This in vitro experimental study was conducted on 50 zirconia discs measuring 1.2 ± 0.2 mm in thickness and 15 ± 0.2 mm in diameter, which were randomly divided into five groups (n = 10) of one control and four experimental groups subjected to sandblasting with 110 μm aluminum oxide particles under 2 bar pressure for 10 seconds at 15 and 25 mm distances and 45 and 90° angles (between the nozzle head and zirconia surface). Surface roughness was measured by a roughness tester and samples were subjected to thermocycling followed by biaxial flexural strength testing according to ISO6872. The data were analyzed using one-way analysis of variance (p < 0.05).

RESULTS

No statistically significant difference was noted in the mean biaxial flexural strength of the five groups (p = 0.40). Different sandblasting protocols yielded significantly different surface roughness values (p < 0.001). The highest and the lowest mean surface roughness belonged to 15 mm/90° (0.51 μm) and control (0.001 μm) groups respectively.

CONCLUSION

Change in sandblasting angle and distance had no significant effect on the biaxial flexural strength of zirconia-based ceramic, but surface roughness was significantly different in the study groups. Clinical significances: Regardless of sandblasting angle, increasing distance to 25 mm significantly decreases surface roughness that may negatively affect zirconia bond strength.

Effect of adhesive luting on the fracture resistance of zirconia compared to that of composite resin and lithium disilicate glass ceramic

OBJECTIVES

The purpose of this study was to evaluate the effect of adhesive luting on the fracture resistance of zirconia compared to that of a composite resin and a lithium disilicate glass ceramic.

MATERIALS AND METHODS

The specimens (dimension: 2 mm × 2 mm × 25 mm) of the composite resin, lithium disilicate glass ceramic, and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) were prepared. These were then divided into nine groups: three non-luting groups, three non-adhesive luting groups, and three adhesive luting groups, for each restorative material. In the non-luting groups, specimens were placed on the bovine tooth without any luting agents. In the non-adhesive luting groups, only zinc phosphate cement was used for luting the specimen to the bovine tooth. In the adhesive luting groups, specimens were pretreated, and the adhesive luting procedure was performed using a self-adhesive resin cement. For all the groups, a flexural test was performed using universal testing machine, in which the fracture resistance was measured by recording the force at which the specimen was fractured.

RESULTS

The fracture resistance after adhesive luting increased by approximately 29% in the case of the composite resin, 26% in the case of the lithium disilicate glass ceramic, and only 2% in the case of Y-TZP as compared to non-adhesive luting.

CONCLUSIONS

The fracture resistance of Y-TZP did not increased significantly after adhesive luting as compared to that of the composite resin and the lithium disilicate glass ceramic.

Surface analysis and shear bond strength of zirconia on resin cements after non-thermal plasma treatment and/or primer application for metallic alloys

There is no established protocol for bonding zirconia (Y-TZP) with resin cements. Non-thermal plasma (NTP) may be an alternative for the clinical problems related to adhesion. The purpose of the present study was to characterize the surface of Y-TZP exposed to methane (CH₄) NTP or coated with a layer of primer for metal alloys and the association between the two methods and to evaluate the effect of NTP treatment on bond strength between Y-TZP and two resin cements. A total of 235 Y-TZP discs (8×2mm) were distributed into five groups: Co (no surface treatment), Pr (primer), NTP (methane plasma), Pr+NTP and NTP+Pr. The effect of the treatment type on the surface free energy, morphology, topography and chemical composition of the Y-TZP discs was investigated. The discs were cemented to composite resin substrates using Panavia F2.0 or RelyX U200. Shear bond strength (n=10) analyses were performed (1mm/min) before and after thermocycling (5-55°C, 2000cycles) on the bonded specimens. The data were analyzed with one and three-way ANOVAs and Bonferroni tests (α=0.05). NTP reduced the surface energy and roughness of the Y-TZP discs. SEM-EDS and XPS analyses showed the presence of the organic thin film, which significantly improved the bond strength results when Rely X U200 was used, whereas the primer treatment was more effective with Panavia F2.0. Thermocycling significantly reduced the bond strength results of the NTP and Pr+NTP groups cemented with Rely X U200 and the Pr and NTP+Pr groups cemented with Panavia F2.0. Nonthermal plasma improves the bond strength between Rely X U200 and Y-TZP and also seems to have water-resistant behavior, whereas Panavia F2.0 showed better results when associated with primer.

Surface topography and bond strengths of feldspathic porcelain prepared using various sandblasting pressures

OBJECTIVE

The purpose of this study was to determine the bond strength of composite resin to feldspathic porcelain and its surface topography after sandblasting at different pressures.

METHODS

In this in vitro study, 68 porcelain disks were fabricated and randomly divided into four groups of 17. The porcelain surface in group 1 was etched with hydrofluoric acid. Groups 2, 3, and 4 were sandblasted at 2, 3 and 4 bars pressure, respectively. Surface topography of seven samples in each of the four groups was examined by a scanning electron microscope (SEM). The remaining 40 samples received the same silane agent, bonding agent, and composite resin and they were then subjected to 5000 thermal cycles and evaluated for shear bond strength. Data were analyzed using one-way anova. The mode of failure was determined using stereomicroscope and SEM.

RESULTS

The highest shear bond strength was seen in group 4. however, statistically significant differences were not seen between the groups (P = 0.780). The most common mode of failure was cohesive in porcelain. The SEM showed different patterns of hydrofluoric acid etching and sandblasting.

CONCLUSION

Increasing the sandblasting pressure increased the surface roughness of feldspathic porcelain but no difference in bond strength occurred.

Retentive strength of implant-supported CAD-CAM lithium disilicate crowns on zirconia custom abutments using 6 different cements

STATEMENT OF PROBLEM

The optimal retention of implant-supported ceramic crowns on zirconia abutments is a goal of prosthodontic treatment.

PURPOSE

The purpose of this in vitro study was to evaluate the retentive strength of implant-supported IPS e.max CAD-CAM (e.max) crowns bonded to custom zirconia implant abutments with different cements.

MATERIAL AND METHODS

An optical scan of a zirconia custom abutment and a complete-coverage modified crown was designed using an intraoral E4D scanner. One hundred twenty lithium disilicate crowns (IPS e.max CAD) were cemented to 120 zirconia abutment replicas with 1 of 6 cements: Panavia 21 (P21), Multilink Hybrid Abutment (MHA), RelyX Unicem 2 (RXU), RelyX Luting Plus (RLP), Ketac Cem (KC), and Premier Implant (PI). The specimens were stored at 37°C in 100% humidity for 24 hours. Half of the specimens were thermocycled for 500 cycles. The retentive force was measured using a pull-out test with a universal testing machine. Mean retentive strengths (MRS) were calculated using 2-way ANOVA and the Tukey-Kramer test (α=.05).

RESULTS

The MRS (MPa) after 24-hour storage were P21 (3.1), MHA (2.5), RXU (2.5), RLP (1.3), KC (0.9), and PI (0.5). The MRS after thermocycling were MHA (2.5), P21 (2.2), RLP (1.8), KC (1.4), RXU (1.1), and PI (0.3). P21 had the highest MRS after 24-hour storage (P<.001), but after thermocycling MHA had the highest MRS (P<.001). RXU showed a significant decrease in MRS after thermocycling (P<.05). Cement residue was mostly retained on the zirconia abutments for P21, while for the other cements' residue was retained on the lithium disilicate crowns.

CONCLUSIONS

The cements tested presented a range of retentive strengths, providing the clinician with a choice of more or less retentive cements. MHA was the most retentive cement after thermocycling. Thermocycling significantly affected the retentive strengths of the P21 and RXU cements.

Bonding of Metal Orthodontic Attachments to Sandblasted Porcelain and Zirconia Surfaces

This study evaluates tensile bond strength (TBS) of metal orthodontic attachments to sandblasted feldspathic porcelain and zirconia with various bonding protocols. Thirty-six (36) feldspathic and 36 zirconia disc samples were prepared, glazed, embedded in acrylic blocks and sandblasted, and divided into three groups according to one or more of the following treatments: hydrofluoric acid 4% (HF), Porcelain Conditioner silane primer, Reliance Assure® primer, Reliance Assure plus® primer, and Z Prime™ plus zirconia primer. A round traction hook was bonded to each sample. Static tensile bond strength tests were performed in a universal testing machine and adhesive remnant index (ARI) scoring was done using a digital camera. One-way ANOVA and Pearson chi-square tests were used to analyze TBS (MPa) and ARI scores. No statistically significant mean differences were found in TBS among the different bonding protocols for feldspathic and zirconia, p values = 0.369 and 0.944, respectively. No statistically significant distribution of ARI scores was found among the levels of feldspathic, p value = 0.569. However, statistically significant distribution of ARI scores was found among the levels of zirconia, p value = 0.026. The study concluded that silanization following sandblasting resulted in tensile bond strengths comparable to other bonding protocols for feldspathic and zirconia surface.

Surface treatment with a fractional CO2 laser enhances shear bond strength of resin cement to zirconia

AIMS

The present study investigated the effect of different surface treatments on shear bond strength (SBS) of resin cement to zirconia.

MATERIALS AND METHODS

Ninety zirconia blocks were prepared and divided into 6 groups of 15 by treatment. Group 1 served as the control group, whereas groups 2 and 3 were treated with air abrasion and a universal primer (Monobond plus), respectively. The remaining zirconia copings were treated with a fractional CO2 laser for 10 seconds using 10 W/10 mJ (group 4), 10 w/14 mJ (group 5) or 20 W/10 mJ (group 6). A luting cement (Clearfil SA) was bonded to the treated zirconia surfaces and cured for 40 seconds. SBS was measured with a universal testing machine and the type of bond failure was determined.

RESULTS

There was a statistically significant difference in SBS among the study groups (p<0.001). The highest SBS values were observed in the groups treated with the fractional CO2 laser at settings of 20 W/10 mJ (28.1 MPa) or 10 W/14 mJ (27.4 MPa), followed by the specimens treated with the universal primer (22.8 MPa). The control specimens exhibited the lowest SBS (9.4 MPa) among the study groups (p<0.05). There was no significant difference in the distribution of failure modes among the groups (p=0.871).

CONCLUSIONS

The application of fractional CO2 laser can improve bond strength of resin cement to zirconia ceramic, and thus it could be considered as an appropriate alternative to conventional methods of zirconia surface treatment.

Effect of diphenyliodonium hexafluorphosphate on resin cements containing different concentrations of ethyl 4-(dimethylamino)benzoate and 2-(dimethylamino)ethyl methacrylate as co-initiators

OBJECTIVE

The present study evaluated the influence of diphenyliodonium hexafluorphosphate (DPI) combined with two different amines [ethyl 4-(dimethylamino)benzoate (EDAB) and 2-(dimethylamino)ethyl methacrylate (DMAEMA)] on the properties of model resin cements.

METHODS

A comonomer base containing a 1:1 mass ratio of 2.2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) was obtained, after which 1mol% of camphorquinone and 0.1mol% of hydroxyl butyl toluene were added to the comonomer blend. Concentrations of co-initiators varied at 0, 0.5 or 1mol% for DPI and in 1 or 2mol% for amines (DMAEMA or EDAB). Silanated Ba-Al-Si glass (60wt%) was added as filler. The combination of each amine and DPI concentration resulted in 12 formulations, which had the following properties analyzed: degree of conversion (DC), water sorption (Wsp) and solubility (Wsl), flexural strength (FS) and flexural modulus (Ef). Data for DC, FS and Ef were analyzed by two-way ANOVA and Tukey's test (α=0.05) and Wsp and Wsl by Kruskal-Wallis and Dunn tests (α=0.05).

RESULTS

EDAB promoted a higher DC than did DMAEMA; however, DPI increased DC for all materials with DMAEMA. The physical properties of resin formulations containing EDAB were significantly better than those of groups with DMAEMA; however, DPI had a positive influence on the chemical and physical properties of the model resin cement containing DMAEMA, especially with higher concentrations of amine.

SIGNIFICANCE

EDAB proved to be more reactive than DMAEMA, being less influenced by DPI. Resins containing a 1:2 CQ/amine ratio had better properties than those with 1:1.

Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives

A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 ± 2.2 MPa) than that of cast metal (9.2 ± 3.5 MPa) restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred.