To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP)after 10,000 and 20,000 thermal cycles. The tested hypothesis was that 10,000 and 20,000 thermal cycles would affect the bond strength of metal brackets bonded to enamel with the self-etching primer.
Brackets were bonded to bovine incisors with two etching protocols. In group CM (conventional method), teeth were etched with 37% phosphoric acid for 30 s. In group SEP, a self-etching primer (Transbond Plus, 3M Unitek) was applied. Brackets were bonded with light-curing adhesive (Transbond XT, 3M Unitek). The SBSs were determined after water storage at 370°C for 24 h, after 10,000 and 20,000 cycles of thermocycling.
For both groups (CM and SEP), SBSs decreased with 10,000 and 20,000 thermal cycles. These decreased SBSs were significantly different from the values obtained with no thermocycling. Highest SBSs were observed with no thermocycling for groups CM and SEP (18.6 and 18.0 MPa, respectively). These values were not statistically different from each other. Lowest SBSs were obtained with 10,000 and 20,000 thermal cycles for group SEP (14.2 and 14.7 MPa, respectively). These values were significantly different from all other SBSs.
This study indicates that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after 10,000 and 20,000 thermal cycles.
This study tested the hypothesis that 2% chlorhexidine (CHX) does not affect the 18-month clinical performance of two dentin adhesives, XP Bond (XPB) and XENO V (XEN).
Materials and methods:
A total of 120 noncarious cervical lesions (NCCL) were selected and assigned to 4 groups: (1) XPB; (2) CHX prior to the application of XPB; (3) XEN; (4) CHX prior to the application of XEN. A hybrid composite resin, EsthetX, was used for all restorations. Restorations were evaluated blindly at 6 and 18 months by two evaluators using the University of North Carolina (UNC)-modified USPHS criteria. Statistical analyses included the Mann Whitney and McNemar nonparametric tests (p < 0.05).
At 6 months, 91 (75.2%) restorations were evaluated, while 92 (76.7%) restorations were evaluated at 18 months. The 6-month/18-month overall retention rates (%) were 100/100 for XPB, 96.0/95.0 for CHX+XPB, 100/91.3 for XEN, and 100/95.8 for CHX+XEN with no statistical difference between any pair of groups at each recall. Sensitivity to air improved significantly for groups XPB, XEN, and CHX+XEN from pre-operative conditions to 1 week after insertion, to 6 and to 18 months after inserting. For group CHX+XPB, there was a statistically significant difference only between pre-operative conditions and 1 week after insertion. Marginal adaptation deteriorated for all groups, but no statistically significant differences were found. All other criteria remained statistically similar.
The application of CHX prior to the dentin adhesive did not influence the 6-month/18-month clinical performance of the two adhesives.
The aim of this study was to evaluate the clinical success potential of two nanocomposites placed in posterior teeth using an antibacterial adhesive system over 18 months.
A total of 49 Class I and 47 Class II restorations were placed in the permanent teeth of thirty adult patients. The carious lesions were restored with Grandio (Voco) or Filtek Supreme (3M ESPE) using a two-step self-etching antibacterial adhesive system Clearfil Protect Bond (Kuraray). The restorations were finished with fine-grit diamond burs, Enhance polishing system, and Sof-Lex finishing brushes. The restorations were evaluated at baseline, 6, 12, and 18 months after placement using modified Ryge criteria for color stability, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention.
The changes in the parameters were assessed using the Cochran Q test and the McNemar test at a significance level of p < 0.05. All restorations were classified as clinically satisfactory after 18 months. Statistical analysis demonstrated differences only in superficial roughness, with Grandio exhibiting more surface roughness than Filtek Supreme (p < 0.05).
Posterior restorations built up with the novel nanocomposites using an antibacterial self-etching system showed satisfactory results at the 18-month recall appointment relative to all criteria except the surface texture in the case of Grandio. Further evaluations are necessary for a more in-depth analysis.
To evaluate the 24-month clinical performance of cervical restorations using a nanohybrid and a flowable resin composite with a one-step self-etching adhesive.
Materials and methods:
Twenty-one patients with at least one pair of non-carious cervical lesions participated in this study. A total of 134 non-carious cervical lesions were restored (67 with a nanohybrid resin composite, Grandio; 67 with a flowable resin composite, Grandio Flow) using a one-step self-etching adhesive system, Futura Bond NR, by one dentist. The restorations were evaluated for retention, color match, marginal discoloration, marginal adaptation, surface texture, anatomic form, and secondary caries by two calibrated examiners at baseline and after 6, 12, and 24 months using modified USPHS criteria. The survival rates of the restorations were calculated by the Kaplan-Meier estimator. The comparison of resin composites for each category was performed with the Pearson chi-square test, and the performance of restorations at baseline and after each recall time was evaluated using McNemar's test (p < 0.05).
All patients attended the 24-month recall. The retention rates at 6 months were 66% and 58%, and 61% and 57% at 12 months for Grandio and Grandio Flow, respectively. At the 24-month recall, the retention rate was 60% for Grandio and 54% for Grandio Flow. No statistically significant differences were found in retention rates among the restorative materials in any evaluation period (p > 0.05). For marginal discoloration and anatomical form, three Grandio and three Grandio Flow restorations showed Bravo scores at the end of 24 months. The restorations in both groups had Alfa ratings of 100% for the rest of the criteria evaluated.
The nanohybrid and flowable resin composites showed similar clinical performances in the restoration of non-carious cervical lesions over 24 months.
To evaluate the immediate microtensile bond strengths achieved with representative adhesive systems from each of the four current bonding approaches.
Resin composite was bonded incrementally to flat, midcoronal dentin from 33 human molars, using the adhesives (Adper Scotchbond MP; Adper Scotchbond 1; Optibond Solo Plus; Clearfil SE Bond; AdheSE; Tyrian SPE + One Step Plus; Optibond Solo Plus self-etching; One-Up Bond F; iBond; Adper Prompt L-Pop; Xeno III) according to the respective manufacturer's instructions. The bonded specimens were immediately sectioned into sticks and underwent microtensile bond testing either immediately or after 24 h. Data were analyzed with two-way ANOVA and LSD tests.
No significant differences were found between immediate and 24-h bond strengths (p > 0.05). However, significant differences were observed among adhesives (p = 0.001). The all-in-one adhesive iBond showed statistically lower values when compared to all the other adhesives. Adper Prompt L-Pop, Xeno III, Tyrian SPE + One Step Plus and One-Up Bond F, all self-etching adhesives, were significantly weaker than AdheSE, Optibond Solo Plus, Adper Scotchbond 1, Optibond Solo Plus self-etching, Clearfil SE Bond, and Adper Scotchbond MP, which did not differ statistically from each other.
Microtensile bond strengths of representative adhesive systems from the four categories of bonding agents were not equivalent, with the lowest values recorded for the one-step self-etching adhesives. There were no differences in the bond strengths when measured immediately and after 24 h.
To investigate the effect of composite type and cavity size on gap and void formation using optical coherence tomography (OCT).
Materials and methods:
Class I cavities of two depths (2 mm or 4 mm; 4 mm diameter) were prepared, treated with Tri-S Bond (Kuraray Medical), and bulk filled with either Surefil SDR Flow (SF; Dentsply) or Clearfil Majesty LV (MJ; Kuraray Medical) to form four groups. After 24 h, the specimens were 3D scanned using swept-source OCT (Santec) with 1310 nm laser at a 20 kHz sweep rate. In OCT tomograms, the bonding interface and the bulk of the restorations were evaluated. The percentage values of sealed interfaces (SP) and void volume (VP) for all groups were calculated and statistically analyzed using two- and one-way ANOVA and Tukey's post-hoc test. Selected specimens were cross sectioned and observed using a scanning electron microscope (SEM) and a confocal laser scanning microscope to confirm OCT findings.
The following values were obtained for SP and VP, respectively: SF-2mm: 92% and 0.08%; SF-4mm: 66% and 0.13%; MJ-2mm: 86% and 1.79%; MJ-4mm: 33% and 1.96%. Both composites showed a significant increase in gap formation at 4-mm cavity depth (p < 0.001). While SF showed a rather homogeneous bulk compared to MJ, cavity depth did not significantly affect the void volume fraction (p = 0.08).
The flowable composite with SDR (stress-decreasing resin) technology performed better than the conventional composite; however, bulk filling a 4-mm-deep cavity will compromise the sealing of the bonding interface regardless of the type of composite. OCT is a unique method of characterizing materials and their behaviors nondestructively and precisely.
To determine the shear bond strength (SBS) of different established (Resulcin Aqua Prime & Monobond N: RA, Prompt L-Pop III: PLP) and experimental (AC-Bond: AC, AC-Bond + Desensitizer: ACD) self-etching adhesives in comparison to fourth (Optibond FL: FL) and fifth generation (Excite: EX, Gluma Comfort Bond: CB) adhesives.
All adhesives were applied on flat enamel and dentin surfaces and light cured following manufacturers' directions. Tetric Ceram A2 composite cylinders 3.5 mm in diameter and 2.0 mm in height were sheared off (1 mm/min) after thermocycling (5 to 55 degrees C, 5000x). The t-test (5% level, Bonferroni-correction) was used for statistical analysis.
SBS in enamel: RA: 27.0+/-5.8 MPa, PLP: 15.9+/-3.4 MPa, AC: 28.1+/-4.4 MPa, ACD: 22.2+/-4.1 MPa, FL: 33.2+/-3.2 MPa, EX: 30.5+/-5.1 MPa, CB: 30.1+/-3.7 MPa. SBS in dentin: RA: 25.8+/-5.7 MPa, PLP: 20.7+/-2.9 MPa, AC: 27.0+/-4.5 MPa, ACD: 20.7+/-3.7 MPa, FL: 34.4+/-3.8 MPa, EX: 30.0+/-4.6 MPa, CB: 27.9+/-2.6 MPa. FL resulted in significantly (p < 0.002) higher SBS in enamel and dentin than RA, AC, ACD, and PLP, and in higher SBS to dentin than CB. In enamel and dentin, RA performed significantly superior to PLP, but was not different from AC and ACD. EX and CB were both on the same level of significance as AC and RA, but showed superior results to ACD and PLP (enamel and dentin). PLP resulted in significantly lower SBS values in enamel and dentin than all the other materials investigated, except ACD in dentin, to which it was equivalent.
Resulcin Aqua Prime & Monobond N and AC-Bond were not significantly different than established 5th generation products. AC-Bond + Desensitizer and Prompt L-Pop have significantly different SBS from established 4th and 5th generation products. Future studies are required to investigate marginal integrity to determine if self-etching adhesives are an adequate alternative to one- and multi-bottle systems.
This study evaluated the differential composition of resin/dentin interfaces of indirect restorations created by the application of 4th and 5th generation dual-curing luting systems (bonding agents/resin cements), when each material was either light cured or allowed to self-cure.
Occlusal flat dentin surfaces of 60 human third molars were assigned into 12 groups (n = 5) according to curing mode and dual-curing cementing system: 4th generation All Bond2 (AB2)/Duolink (Bisco) and 5th generation (B1) Bond1/Lute-it (Pentron). Fluorescein-labeled dextran (FDx) was mixed with the bonding agents, while rhodamine-labeled dextran (RhDx) was incorporated into resin cements and Pre-Bond resin from AB2. Resin cements were applied to 2-mm-thick, precured resin composite disks (Z250, 3M ESPE), which were fixed to dentin surfaces containing adhesive resin in either cured (light cured; LC) or uncured (self-cured; SC) states. The restored teeth were light activated (XL3000, 3M ESPE) according to the manufacturers' instructions (LRC) or allowed to self-cure (SRC), were stored for 24 h, and then vertically, serially sectioned into l-mm-thick slabs, which were analyzed using confocal laser scanning microscopy. Fluorescent additives indicated where individual components of the bonding/cement systems were located. Additional specimens were prepared and analyzed using a conventional scanning electron microscope.
AB2/LC and B1/LC exhibited nonuniform primer/adhesive layer thickness. AB2/SC showed adhesive resin penetration within the primed dentin, and resin cement penetration at the entrance of the dentin tubules. B1/SC/LRC demonstrated resin cement penetration within the hybrid layer and into the dentin tubules. More resin cement penetration was observed in B1/SC/SRC groups than in its LRC equivalent.
The morphological features and component interactions among materials at resin/dentin interfaces are related to the activation modes of the primer/adhesive layer and of the resin cement used.
To evaluate the effects of acidic functional monomers on the bond strength and durability of an acrylic resin joined to Ti-6Al-7Nb alloy and component metals.
Disk specimens of two different sizes (10 and 8 mm in diameter and 2.5 mm in thickness) were prepared from uncast Ti-6Al-7Nb alloy, titanium, aluminum, and niobium. The specimens were ground with abrasive paper and divided into 8 groups: unprimed control, primed with Acryl Bond, Alloy Primer, All Bond II Primer B, Estenia Opaque Primer, M.L. Primer, MR. Bond, and Super-Bond Liquid. The disks were bonded with tri-n-butylborane (TBB)-initiated acrylic resin, and shear bond strengths were determined both before and after thermocycling.
The Alloy Primer and Estenia Opaque Primer agents, which contain a hydrophobic phosphate monomer (MDP), and Super-Bond Liquid demonstrated a durable bond with Ti-6Al-7Nb alloy. MDP was also effective in bonding Ti, Al, and Nb.
The two primers containing MDP were effective for treating Ti-6Al-7Nb alloy and Ti. Al and Nb showed bonding behavior similar to Ti-6Al-7Nb alloy and Ti when the two metals were treated with acidic primers and bonded with the TBB-initiated acrylic resin.
To evaluate under controlled clinical conditions the outcomes of cast-metal slot-retained resin-bonded fixed dental prostheses (RBFDPs) in which resin composite interlocked the restoration retainers in place after cementation in cases with single missing first molars, and to collect survival data on this esthetic RBFDP design combined with an economical metal fit-surface treatment method and resin luting system.
Materials and methods:
Forty-one tub-shaped inlay-retained RBFDPs were clinically observed for up to 7.7 years in 35 recipients of both genders between 18 and 52 years of age. Clinical examinations were performed at baseline and 6 and 12 months after restoration placement, and thereafter at regular 1-year intervals. Modified US Public Health Service (USPHS) parameters, sulcus bleeding index, Silness-Löe plaque index, pocket depths, tooth mobility, pulp vitality, and periapical radiographs regarding the abutment teeth were assessed at these follow-up appointments. The Kaplan-Meier survival estimation method was performed to detect the overall and functional survival rates and mean survival times of the RBFDPs at the end of the study. The Breslow (Generalized Wilcoxon) test was used to evaluate the influence of restoration location and age and gender of the patient regarding the overall survival probability at the end of the follow-up (α = 0.05).
At the end of the study, 34 RBFDPs (83%) were still functioning with a mean follow-up of 6.3 years. According to the Kaplan-Meier survival curve, the overall and functional survival probabilities were calculated as 76% and 83%, with mean survival times of 6.8 years and 7.2 years, respectively. All clinical parameters monitored throughout the follow-up period predominantly revealed clinically acceptable results. Breslow test statistics presented nonsignificant differences with better results for the RBFDPs placed in the mandible of female recipients younger than 30 years of age. The most common failure noted with the RBFDPs was fracture of the occlusal veneering composite restoration over the retainer of a single abutment, leading to a predisposition of the restoration to partial debonding.
Within the limitations of this prospective cohort study, it can be concluded that cast-metal slot-retained RBFDPs utilizing the interlocking mechanism of a resin composite to obtain additional retention from the abutment cavities show acceptable clinical success rates, and can be considered a minimally invasive, economical, and time-saving treatment alternative for the prosthetic rehabilitation of single missing first molars.
To assess the microshear bond strength of 3 experimental adhesives with different degrees of hydrophilicity after 1, 7 and 90 days of storage.
The bonding effectiveness of three experimental two-step etch-and-rinse adhesives (bis- GMA, bis-EMA/bis-GMA, polybutadiene [C6H12]) and one commercial adhesive (Single Bond) to sound hydrated dentin was determined using the microshear test with delimitation of the adhesive area after 1, 7, and 90 days of storage in water at 37°C. Two-way ANOVA was performed at the 0.05 probability level. The fractures were classified as adhesive, cohesive in dentin, cohesive in resin, and mixed.
The experimental adhesives showed values in the range of 11.31 to 12.96 MPa, with polybutadiene (PBH) showing the lowest bond strengths, bis-GMA the highest, and bis-EMA/bis-GMA intermediary values. Single Bond yielded bond strengths of approximately 24 MPa. Water storage decreased the bond strength in all adhesives. Adhesive fractures were predominant in experimental adhesives, while mixed fractures were the most frequent type in the Single Bond group.
The experimental dentin adhesives of this study were able to form resin tags, but they could not penetrate into the collagen fibers and form hybrid layers. The resulting low bond strength decreased with increasing length of storage.
About 35 years ago, Ryge provided a practical approach to the evaluation of the clinical performance of restorative materials. This systematic approach was soon universally accepted. While that methodology has served us well, a large number of scientific methodologies and more detailed questions have arisen that require more rigor. Current restorative materials have vastly improved clinical performance, and any changes over time are not easily detected by the limited sensitivity of the Ryge criteria in short-term clinical investigations. However, the clinical evaluation of restorations not only involves the restorative material per se but also different operative techniques. For instance, a composite resin may show good longevity data when applied in conventional cavities but not in modified operative approaches. Insensitivity, combined with the continually evolving and nonstandard investigator modifications of the categories, scales, and reporting methods, has created a body of literature that is extremely difficult to interpret meaningfully. In many cases, the insensitivity of the original Ryge methods leads to misinterpretation as good clinical performance. While there are many good features of the original system, it is now time to move on to a more contemporary one. The current review approaches this challenge in two ways: (1) a proposal for a modern clinical testing protocol for controlled clinical trials, and (2) an in-depth discussion of relevant clinical evaluation parameters, providing 84 references that are primarily related to issues or problems for clinical research trials. Together, these two parts offer a standard for the clinical testing of restorative materials/procedures and provide significant guidance for research teams in the design and conduct of contemporary clinical trials. Part 1 of the review considers the recruitment of subjects, restorations per subject, clinical events, validity versus bias, legal and regulatory aspects, rationales for clinical trial designs, guidelines for design, randomization, number of subjects, characteristics of participants, clinical assessment, standards and calibration, categories for assessment, criteria for evaluation, and supplemental documentation. Part 2 of the review considers categories of assessment for esthetic evaluation, functional assessment, biological responses to restorative materials, and statistical analysis of results. The overall review represents a considerable effort to include a range of clinical research interests over the past years. As part of the recognition of the importance of these suggestions, the review is being published simultaneously in identical form in both the Journal of Adhesive Dentistry and Clinical Oral Investigations. Additionally, an extended abstract will be published in the International Dental Journal, giving a link to the web full version. This should help to introduce these considerations more quickly to the scientific community.
The aim of this in vitro study was to evaluate the shear bond strength of two conventional glass-ionomer cements to bovine dentin when using the air-abrasion technique for cavity preparation.
Forty bovine central incisors were selected, embedded in polyester resin, and ground until the dentin surface was exposed. The teeth were randomly assigned to four groups: I and II--rotating instrument with a carbide bur; III and IV--an air-abrasion system. Groups I and III were restored with Fuji IX and groups II and IV with Ketac Molar. A 3-mm-diameter bonding site was delimited and treated with 10% polyacrylic acid for 10 s in the Fuji IX subgroups and with 25% polyacrylic acid for 10 s in the Ketac Molar subgroups. After surface treatment, a glassionomer cylinder was prepared for each specimen, using a split bisected Teflon matrix. The finished specimens were submitted to the shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed using ANOVA and Scheffé statistical tests. The dentin bonding areas were analyzed under a stereoscopic optical magnifier (40X) to assess the type of failure.
The mean (SD) shear bond strengths in MPa were: group I--3.49 (+/- 3.77), group II--7.17 (+/- 2.93), group III--7.55 (+/- 2.99), group IV--5.67 (+/- 3.90). Ketac Molar showed higher bond strength values in bur-prepared cavities, while on the air-abraded preparations, Fuji IX showed superior results.
It can be concluded that the air-abrasion system used for cavity preparations may influence the bonding performance of conventional glass-ionomer cements to dentin.
The purpose of this study was to test the tensile bond strength of composite resin to enamel surfaces treated with kinetic cavity preparation (KCP) and acid etching, respectively.
Plane labial surfaces of 280 human maxillary central incisors were treated with either KCP by varying treatment conditions or phosphoric acid gel. Composite samples were bonded to the pretreated surfaces with a bonding resin. After 24 hours specimens were loaded in tension in an Instron testing machine until bond failure. A two-way analysis of variance was used to determine significant differences. The failure sites were qualitatively evaluated by SEM.
The determined tensile bond strengths and observed failure modes demonstrated that acid-etched enamel has a significantly higher bond strength to composite resin than KCP-treated enamel surfaces.
KCP-prepared enamel has to be acid etched before bonding to composite resin.
This study evaluated the spatial and functional roughness parameters on air-abraded zirconia as a function of particle type and deposition pressure.
Materials and methods:
Polished zirconia blocks (Cercon, Degussa/Dentsply) (N=30) with dimensions of 5 × 4 × 4 mm3 were air abraded according to 2 factors: a) particle type - 30-μm silica-coated alumina (CoJet) or alumina particles (45 μm); b) deposition pressure (1.5, 2.5 and 4.5 bar). Roughness parameters (Sdr, Vi, Sci and Svi) were measured in an optical profilometer (Wyko NT 1100) at the center of the air-abraded area (301.3 × 229.2 μm). Two measurements were made for each parameter from each surface. The means of each group were analyzed by 2-way ANOVA followed by Tukey's adjustment test and Student's t-test (alpha = 0.05).
Both the particle type (p < 0.05) and deposition pressure (p < 0.05) significantly affected the roughness parameters. Interaction terms were significant except for Sci and Svi. With the increase in pressure from 1.5 to 4.5 bar, Sdr (CoJet 1.5: 15.7 ± 0.2; CoJet 4.5: 26.6 ± 0.2; alumina 1.5: 14.7 ± 0.2; alumina 4.5: 24.4 ± 0.2) and Vi (CoJet 1.5: 0.66 ± 0.01; CoJet 4.5: 1.37 ± 0.07; alumina 1.5: 0.62 ± 0.02; alumina 4.5: 1.19 ± 0.02) parameters showed a significant increase with both alumina and CoJet particles. Mean Sci values (CoJet 1.5: 1.62 ± 0.01, CoJet 4.5: 1.49 ± 0.02; alumina 1.5: 1.6 ± 0.03; alumina 4.5: 1.42 ± 0.04) and SVi (CoJet 1.5: 0.98 ± 0.01, CoJet 4.5: 0.112 ± 0.01; alumina 1.5: 0.98 ± 0.01, alumina 4.5: 0.12 ± 0.01) decreased significantly (p < 0.05) with the increase in pressure from 1.5 to 4.5 bar. The pressure increase from 2.5 to 4.5 bar did not cause any significant difference (p > 0.05) in these parameters for either particle type.
Considering roughness parameters for micromechanical retention and parameters for adsorption mechanisms of adhesion, zirconia surfaces presented better morphological features when air abraded with silica-coated alumina than alumina particles at pressures higher than 1.5 bar. Particle deposition at 2.5 bar may be preferable to 4.5 bar pressure for avoiding possible deposition-related damage on zirconia, as there were no significant differences for the functional parameters.
PURPOSE: To evaluate the effect of nozzle distance, nozzle angle, and deposition duration on the silica content attained on zirconia by air abrasion.
MATERIALS AND METHODS: Disk-shaped zirconia (LAVA, 3M ESPE) (diameter: 10 mm, thickness: 2 mm) specimens (N = 54) were obtained. They were wet-ground finished using 600-, 800-, and 1200-grit silicone carbide abrasive papers in sequence and ultrasonically cleaned. The specimens were mounted in a specially designed apparatus that allowed the chairside air-abrasion device to be operated under standard conditions. Alumina-coated silica particles (CoJet Sand, 3M ESPE) were deposited on the zirconia disk surfaces varying the following parameters: a) nozzle distance (2, 5, 10 mm), and b) deposition duration (5, 13, 20 s) at two nozzle angles (45 and 90 degrees) under 2.5 bar pressure at three locations on each ceramic disk. The specimen surfaces were then gently air dried for 20 s. Silica content in weight percentage (wt%) was measured from 3 surfaces on each disk using Energy Dispersive X-ray Spectroscopy (EDS) (150X) in an area of 0.8 mm x 0.6 mm (n = 3 per group). Surface topographies were evaluated using SEM. Data were analyzed using ANOVA and Tukey's tests (α = 0.05).
RESULTS: Nozzle angle (p = 0.003) and deposition duration (p = 0.03) significantly affected the results, but nozzle distance (p = 0.569) did not. A significantly higher amount of silica (wt%) was achieved when the nozzle angle was 45 degrees to the surface in all distance-duration combinations (16.7 to 28.2 wt%) compared to the 90-degree nozzle angle (10.7 to 18.6 wt%) (p < 0.001). The silica amount was significantly higher after 20-s deposition duration than after 13 s (p < 0.05). EDS analysis demonstrated not only Si but also Al, Zr, and O traces on the substrate. SEM images indicated that deposition at a nozzle distance of 2 mm often created cavitations in zirconia.
CONCLUSION: Effective silica deposition using a charside air-abrasion device can be achieved when the nozzle is held at 45 degrees to the surface with more than 2-mm nozzle distance for 20 s.
To evaluate in vitro the influence of different cleaning methods after low-pressure air abrasion on the bond strength of a phosphate monomer-containing luting resin to zirconia ceramic.
A total of 112 zirconia ceramic disks were divided into 7 groups (n = 16). In the test groups, disks were air abraded at low pressure (L) 0.05 MPa using 50-μm alumina particles. Prior to bonding, the disks were ultrasonically (U) cleaned either in isopropanol alcohol (AC), hydrofluoric acid (HF), demineralized water (DW), or tap water (TW), or they were used without ultrasonic cleaning. Disks air abraded at a high (H) pressure of 0.25 MPa and cleaned ultrasonically in isopropanol served as positive control; original (O) milled disks used without air abrasion served as the negative control group. Plexiglas tubes filled with composite resin were bonded with the adhesive luting resin Panavia 21 to the ceramic disks. Prior to testing tensile bond strength (TBS), each main group was further subdivided into 2 subgroups (n=8) which were stored in distilled water either at 37°C for 3 days or for 30 days with 7500 thermal cycles. Statistical analyses were conducted with two- and one-way analyses of variance (ANOVA) and Tukey's HSD test.
Initial tensile bond strength (TBS) ranged from 32.6 to 42.8 MPa. After 30 days storage in water with thermocycling, TBS ranged from 21.9 to 36.3 MPa. Storage in water and thermocycling significantly decreased the TBS of test groups which were not air abraded (p = 0.05) or which were air abraded but cleaned in tap water (p = 0.002), but not the TBS of the other groups (p > 0.05). Also, the TBS of air-abraded groups were significantly higher than the TBS of the original milled (p < 0.01). Cleaning procedures did not significantly affect TBS either after 3 days or 30 days storage in water and thermocycling (p > 0.05).
Air abrasion at 0.05 MPa and ultrasonic cleaning are important factors for improving bonding to zirconia ceramic.