Air-particle Abrasion Research Articles

A Comprehensive Review of Techniques for Enhancing Zirconia Bond Strength: Current Approaches and Emerging Innovations.

The increasing use of zirconia in dental restorations necessitates a comprehensive understanding of effective bonding techniques to ensure long-term clinical success. Zirconia's unique chemical composition presents challenges in achieving a durable bondas it lacks the glass phase necessary for traditional etching and silanization processes. This review evaluates current methods and emerging innovations for enhancing zirconia bond strength to resin cements. Our findings emphasize the importance of mechanical surface treatments such as air-particle abrasion and tribochemical silica-coating, which significantly improve micromechanical retention. Laser irradiation, while less commonly used, also shows promise in enhancing bond strength without compromising zirconia's structural integrity; 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primers emerged as critical agents in forming stable P-O-Zr bonds, particularly when used with resin cements containing 10-MDP. However, variations in formulation and application methods impact their overall efficacy. Resin cement demonstrated superior bond strength compared to conventional cement, but clinical outcomes varied, highlighting the importance of cement-primer compatibility and strict procedural adherence. Emerging technologies such as polymer-infiltrated ceramic networks (PICNs) and additive manufacturing (AM) of zirconia offer potential for future advancements, although they require further research to address mechanical and aesthetic challenges. In conclusion, while established methods such as sandblasting and the use of MDP primers remain reliable, ongoing research into novel materials and techniques continues to offer opportunities for enhancing zirconia bonding. Clinicians must balance effectiveness, procedural complexity, and clinical practicality when selecting the most appropriate bonding protocols for zirconia restorations.

Biophysical and aesthetic recovery in incisor hypomineralisation: a modified protocol

The clinical management of incisor hypomineralisation (IH) as it pertains to biophysical and aesthetic recovery, especially in the teeth of young individuals, is fraught with complexity. Treatment modalities are wide and varied, and often, if used in the wrong sequence, can lead to a suboptimal aesthetic result. Approaches, such as chemical micro-abrasion, air particle abrasion and tooth whitening have been used in the past, in addition to resin infiltration for the treatment of affected enamel. The penetration depth of hypomineralised lesions by resin infiltrant has been reported to vary and be dependent on the pre-treatment modalities used. The elimination of brown-coloured aspects of the IH lesion via tray-delivered tooth whitening is critical prior to resin infiltration because once the resin has polymerised, it will be more impermeable and thus less likely to be modified by oxidative action. This case report describes an extended resin infiltration period under diminished ambient light prior to polymerisation that was required for aesthetic success. CPD/Clinical Relevance: Ideal sequencing of treatment prior to resin infiltration is critical for physico-aesthetic success. The length of resin infiltration can be increased if results are not seen by the manufacturer-prescribed application time.

Effect of Particle Size and Application Pressure in Air-Borne Particle Abrasion on the Adhesion of Polyetheretherketone.

This study aims to investigate the effect of different particle sizes and pressures on the shear bond strength (SBS) and the roughness (Ra) of polyetheretherketone. A total of 117 polyetheretherketone specimens were fabricated and divided into a control (CN: no air-particle abrasion) and eight pre-treatment groups (air-abraded with 50- or 110-μm Al2O3 particles at 1(A), 1.5(B), 2(C), and 2.5(D) bar). The adhesive, Visio.link was used. Thermal aging was performed. Surface properties, SBS and failure mode were assessed. Data was analyzed by linear regression, Pearson correlation and Dunnett's T3 test for pairwise comparisons (p⟨0.05). The highest and lowest Ra were found in the 110D and CN groups respectively, and the highest SBS results were obtained from the 50B group. Pressure and particle size showed significant difference on the investigated properties (p⟨0.001). Only adhesive failure was observed in the CN, and resin cohesive failure was observed in addition to adhesive failure in the overall study groups. The air-borne particle abrasion procedures and the adhesive material combination are critical to the strength of the polyetheretherketone bond. The combination of visio.link with the pre-treatment option of 50-μm Al₂O₃ particles applied at 1.5-bar pressure delivered the most favorable results.

The influence of Zircos-E® etchant, silica coating, and alumina air-particle abrasion on the debonding resistance of endocrowns with three different preparation designs.

The study aimed to evaluate the debonding resistance of three different endocrown designs on molar teeth, using three different zirconia surface pretreatments. Ninety human mandibular first molars were divided into three main groups: endocrowns without ferrule, with 1 mm ferrule, and with 2 mm ferrule. The subgroups were defined by their surface pretreatment method used (n = 15): 50 μm alumina air-particle abrasion, silica coating using 30 μm Cojet™ particles, and Zircos-E® etching. The endocrowns were fabricated using multilayer zirconia ceramic, cemented with self-adhesive resin cement, and subjected to 5000 thermocycles (5-55°C) before debonding. The data obtained were analyzed using a two-way ANOVA. All test specimens survived the thermocyclic aging. The results indicated that both the preparation design and the surface treatment had a significant impact on the resistance to debonding of the endocrowns (p < .001). The 2 mm ferrule followed by the 1 mm ferrule designs exhibited the highest debonding resistance, both were superior to the endocrown without ferrule. Zircos-E® etching and silica coating yielded comparable debonding resistance, which were significantly higher than alumina air-particle abrasion. All endocrowns demonstrated a favorable failure mode. All designs and surface treatments showed high debonding resistance for a single restoration. However, ferrule designs with Zircos-E® etching or silica coating may represent better clinical options compared to the nonferrule design or alumina airborne-particle abrasion. Nonetheless, further research, including fatigue testing and evaluations with different luting agents is recommended.

Tensile bond strength of CAD-CAM all ceramic crowns before and after thermomechanical aging.

The purpose of this in vitro study was to compare the tensile bond strength (TBS) of resin nanoceramics (RNC), zirconia, and lithium disilicate (LS2) restorations cemented to titanium abutments before and after thermomechanical aging. Twelve specimens per group were fabricated to determine the TBS between a titanium abutment and four types of crown materials (2 RNCs, LS2, and translucent zirconia crowns for the maxillary molar). After milling, the abutments and crowns were cemented with resin cement after air-particle abrasion. In addition, thermomechanical aging (200,000 cycles, 50 N, 2Hz) was applied to half of the specimens by using a mastication simulator. TBS was measured by using a universal testing machine. The interface between the crown and the cement was observed by using scanning electron microscopy (SEM). Two-way ANOVA was performed to analyze the effects of crown materials and thermomechanical aging. Failure-mode and interface analyses were also conducted. After thermomechanical aging, the TBS decreased in the LS2 specimens and increased in RNCs (p < 0.001). The ratio of mixed failure and debonding with the hole-sealing resin increased in the RNC group. SEM images showed the reduced gap between the crown and the resin cement after thermomechanical aging in the RNC group. Differences in TBS were affected by the crown materials after thermomechanical aging. After thermomechanical aging, the RNC crowns showed increased TBS, whereas LS2 and zirconia crowns exhibited decreased or similar TBS.

Osteoblast Attachment on Bioactive Glass Air Particle Abrasion-Induced Calcium Phosphate Coating.

Air particle abrasion (APA) using bioactive glass (BG) effectively decontaminates titanium (Ti) surface biofilms and the retained glass particles on the abraded surfaces impart potent antibacterial properties against various clinically significant pathogens. The objective of this study was to investigate the effect of BG APA and simulated body fluid (SBF) immersion of sandblasted and acid-etched (SA) Ti surfaces on osteoblast cell viability. Another goal was to study the antibacterial effect against Streptococcus mutans. Square-shaped 10 mm diameter Ti substrates (n = 136) were SA by grit blasting with aluminum oxide particles, then acid-etching in an HCl-H2SO4 mixture. The SA substrates (n = 68) were used as non-coated controls (NC-SA). The test group (n = 68) was further subjected to APA using experimental zinc-containing BG (Zn4) and then mineralized in SBF for 14 d (Zn4-CaP). Surface roughness, contact angle, and surface free energy (SFE) were calculated on test and control surfaces. In addition, the topography and chemistry of substrate surfaces were also characterized. Osteoblastic cell viability and focal adhesion were also evaluated and compared to glass slides as an additional control. The antibacterial effect of Zn4-CaP was also assessed against S. mutans. After immersion in SBF, a mineralized zinc-containing Ca-P coating was formed on the SA substrates. The Zn4-CaP coating resulted in a significantly lower Ra surface roughness value (2.565 μm; p < 0.001), higher wettability (13.35°; p < 0.001), and higher total SFE (71.13; p < 0.001) compared to 3.695 μm, 77.19° and 40.43 for the NC-SA, respectively. APA using Zn4 can produce a zinc-containing calcium phosphate coating that demonstrates osteoblast cell viability and focal adhesion comparable to that on NC-SA or glass slides. Nevertheless, the coating had no antibacterial effect against S. mutans.

Shear bond strength of the ceramic veneer to additively manufactured titanium.

The objective of this in vitro study was to evaluate the shear bond strength between the ceramic veneer and additively manufactured titanium with different surface treatments, and to compare with milled titanium. Also, to characterize the surface and the presence of an α-case layer of additively manufactured and milled titanium. Sixty additively manufactured titanium grade 23, and 20 milled titanium grade 4 cylindrical specimens were divided into four groups based on surface treatments, air-particle abrasion and grinding. After ceramic veneering half of each group were thermocycled. The bond strength was analyzed using a shear bond strength test. The surfaces were analyzed using interferometry and scanning electron microscopy. The grinding procedure and air-particle abrading pressure had no significant effect on the shear bond strength (p = .264 and p = .344). Thermocycling showed a tendency towards an effect but not significant (p = .052). The group with the highest air-abrading pressure showed the highest surface roughness. No presence of an α-case layer was detected in any of the groups. Additively manufactured titanium grade 23 may be veneered with ceramics without prior grinding of the surfaces.

Shear bond strength of orthodontic brackets bonded to high-translucent dental zirconia with different surface treatments: An in vitro study

The objective of this study was to compare the shear bond strengths of orthodontic brackets bonded to translucent dental zirconia samples which are anatomically accurate and treated with various surface treatments. This in vitro study included 156 samples from 3 brands of high-translucent zirconia split into a control group and 4 surface treatment groups: 9.6% hydrofluoric acid etching, 50-micron aluminium oxide particle air abrasion, and 30-micron tribochemical silica coating (TBS) particle air abrasion with and without silane application. After surface treatment, all groups were primed with a 10-MDP primer and bonded to metal orthodontic brackets. Shear bond strength (SBS) was tested and results were compared between all groups. Data analysis consisted of a balanced two-factor factorial ANOVA, a Shapiro-Wilks test, and a non-parametric permutation test. The significance level was set at 0.05. Among all surface treatments, aluminium oxide particle abrasion produced significantly higher SBS (P≤0.002). Lava™ Plus zirconia samples had significantly higher SBS than Cercon® samples (P<0.0001). TBS surface treatment produced significantly higher SBS on Lava™ Plus samples than it did on the other zirconia brands (P=0.032). This study indicated that mechanical abrasion using aluminium oxide in combination with a 10-MDP primer creates a higher SBS to high-translucent zirconia than the bond created by tribochemical silica coating. Also, there was no significant difference in ARI regardless of zirconia brand or surface preparation.

Effect of different surface treatments on the retention force of additively manufactured interim implant-supported crowns.

To compare the effect of different pre-cementation surface treatments and bonding protocols on the retention force of additively manufactured (AM) implant-supported interim crowns. A total of 50 AM interim crowns (Temporary CB resin) were cemented on implant abutments. Five groups (n = 10) were established based on the different surface pre-treatments performed in the intaglio surface of the specimens: no surface pre-treatment (Group C or control), air-abraded with 50-μm aluminium oxide particles (Group AP), air-abraded with 50-μm aluminium oxide particles followed by the application of silane (Group AMP), silane (Group MP), and air-abraded with 30μm silica-coated aluminum oxide particles followed by the application of silane (Group CMP). Each specimen was cemented into an implant abutment using a composite resin cement (Rely X Unicem2). Afterward, the specimens underwent retention testing with a Universal Instron machine. Pull-off forces (N) and modes of failure were registered. Statistical analysis was performed using Mann-Whitney U tests with Bonferroni corrections for multiple tests (α = .05). The median retention force values were 233.27 ±79.28 N for Group Control, 398.59 ±68.59 N for Group MP, 303.21 ±116.80 N for Group AMP, 349.31 ±167.73 N for Group CMP, and 219.85 ± 55.88 N for Group AP. The pull-off forces were significantly greater for Group MP, while the differences between the remaining groups were not statistically significant (P>0.05). Group AP showed the lowest retention force values among all the groups. Failure modes after the pull-off testing were predominantly adhesive and substrate failure of the AM interim material. The surface treatment of the intaglio AM crown tested significantly influenced the retention force values measured. Pre-treatment with an MDP-containing silane improved the retentive force values computed, whereas pre-treatment with 50-μm Al2 O3 air-particle abrasion alone is not recommended prior to cementation on a titanium-based implant abutment. This article is protected by copyright. All rights reserved.

Evaluation of the Effect of Two Surface Treatment Methods on Shear Bond Strength between Porcelain Veneer and Two Different Zirconia Blocks

Introduction: The aim of the study was to test the effect of two surface treatment methods on shear bond strength between a porcelain veneer and two different zirconia blocks. Materials and Methods: Sixty disk-shaped zirconia samples (30 samples of Novi brand and 30 samples of Rainbow brand) were used (diameter of 10 mm and thickness of 4 mm). Based on surface treatment, the samples were randomly divided into 3 groups: control, air-particle abrasion, and Zircos-E Etching Solution. Using the metal mold, the porcelain was veneered on the zirconia surface and then fired. Then, all samples were subjected to shear bond strength testing using a universal testing machine at a speed of 1 mm/min until breaking. Results: There was a statistically significant difference between the mean variable shear bond strength of the control group and two other groups, so the shear bond strength in the control group was less than in both groups. And there was no statistically significant difference between the mean variable of shear bond strength in the two groups of “airborne particle abrasion” and “Etching”. There was a statistically significant difference between the mean shear bond strength of the two types of zirconia samples and this amount was lower in Novi than in Rainbow. There was also no interaction between the type of surface preparation and the type of zirconia. Conclusion: It can be concluded that surface preparation with air particle abrasion and etching increases the shear bond strength of zirconia to porcelain veneer and the shear bond strength of zirconia and porcelain veneer is affected by the type of zirconia.

Effect of surface treatment on the repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable substrates

ObjectivesTo compare repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable composite substrates. Also, to evaluate the influence of different surface treatments on repair bond strength. MethodsA total of 80-disc shaped specimens was fabricated using two resin based composite materials; IPS Empress Direct Enamel and OptiShade (n = 40). Substrate discs were thermocycle 5000 cycles then each substrate material was subdivided based on the surface treatment into two groups; air particle abrasion (APA) and silicon carbide grinding (SiCr) both groups followed by phosphoric acid etching. All groups received a single bond universal adhesive application prior to repairing with composite, in a smaller disc shape. All specimens were thermocycled for 10,000 cycles prior to shear bond strength testing and subsequent failure analysis. Statistical analyses were conducted and the level of statistical significance was set at 0.05. ResultsThe comparison of mean values (considering the combination of the two types of substrates, surface treatments and repairing materials) showed a highly statistically significant difference in the shear bond strength among the eight study groups (p < 0.0001). The highest value of mean shear bond strength was associated with OptiShade substrates repaired by Diamond ONE (38.6 ± 2.4). Meanwhile, the lowest value was recorded for the SiCr treated OptiShade group repaired by Diamond ONE (13.6 ± 2.3). The failure analysis revealed that cohesive mode of failure was the most predominant. ConclusionOmnichroma showed higher repair bond strength values with SiCr surface treatment. Meanwhile, Charisma Diamond ONE had better bond strength with APA. Surface pretreatment had a significant impact on the repair bond strength where APA groups had significantly higher values compared to SiCr groups. Clinical Significance: Within the limitation of the present study; APA is recommended as surface pretreatment for improved bond strength in restorative composite repairs.

The effect of different tooth preparation finishing procedures and immediate dentin sealing on the scanning accuracy of different intraoral scanners

PurposeTo measure the effect of different tooth preparation finishing procedures (super-coarse grit, fine grit, and air-particle abrasion) and immediate dentin sealing (IDS) on the scanning accuracy of 4 intraoral scanners (IOSs). Material and methodsA tooth preparation for a full-coverage restoration was performed on an extracted mandibular molar using super-coarse diamond burs. Four groups were created depending on the tooth preparation finishing procedure: super-coarse grit (bur with a grit size of 150 µm) (SCG group), fine grit (bur with a grit size of 30 µm) (FG), air-particle abrasion with 27-µm aluminum oxide particles (APA group), and IDS (IDS group). Each group was divided into 5 subgroups according to the scanning system used to digitize the tooth preparation: laboratory scanner (control subgroup) (T710; Medit), Trios 4 (Trios subgroup), CS 3800 (CS subgroup), i700 wireless (i700 subgroup), and iTero Element 5D Plus (iTero subgroup) (n=20). For each subgroup, the control file was aligned with each experimental scan using the best-fit algorithm and an engineering program (Geomagic Control X). The discrepancy between the control and experimental files of each subgroup was computed by measuring the root mean square (RMS) error. Two-way ANOVA and Tukey tests were used to analyze the data (α=.05). ResultsTooth preparation finishing procedures (P<.001) and the IOS assessed (P<.001) were significant predictors of the trueness and precision values obtained. The highest trueness and precision values were measured in the APA group, while the IDS group had the lowest trueness and precision. Additionally, the i700 subgroup obtained the highest trueness and precision values, while the CS and Trios subgroups had the lowest trueness and precision values. ConclusionsThe different tooth preparations finishing procedures tested influenced on the scanning accuracy of the 4 IOSs considered. The air-particle abrasion procedure obtained the best accuracy values. The trueness discrepancies measured among all the subgroups was 19µm and the precision discrepancies measured among all the subgroups was 4.69 µm. Clinical SignificanceThe tooth preparation finishing procedure used can reduce the intraoral scanning accuracy of any of the intraoral scanners tested. The air-particle abrasion finishing procedure might be recommended for maximizing the scanning accuracy of the IOSs tested.

Single-retainer all-ceramic resin-bonded fixed dental prostheses: Long-term outcomes in the esthetic zone.

To present an update on the concept of cantilevered single-retainer all-ceramic resin-bonded fixed dental prostheses (RBFDPs) first presented 25 years ago in the Journal of Esthetic Dentistry. The initially presented case of the concept was followed clinically over 26 years and is presented along with two additional clinical long-term cases using varying methods to obtain an esthetic and hygienic ovate pontic design. Veneered alumina and zirconia ceramic (3mol% yttria-tetragonal zirconia polycrystalline ceramic; 3Y-TZP) was used and bonded with a phosphate monomer containing luting resin after 50 μm alumina particle air-abrasion at 0.25 MPa pressure. The restorations replacing incisors did not debond and soft tissues in the pontic area were maintained over 26 years. Cantilevered single-retainer all-ceramic RBFDPs today made from veneered 3Y-TZP zirconia ceramic can be considered a standard of care for the replacement of single incisors and provide an excellent esthetic outcome with a long-term preservation of soft tissues in the pontic area. Bonding nonretentive oxides ceramics such as alumina and zirconia ceramic with phosphate monomer containing luting resins after alumina particle air-abrasion is durable over decades. This proves that bonding to zirconia ceramic is not of any problem when adequate methods are used. Single-retainer zirconia ceramic RBFDPs maintain soft tissues in the edentulous area of single missing incisors and often deem implants unessential for this indication.

Effects of cold atmospheric plasma treatment on resin bonding to high-translucency zirconia ceramics.

This study aims to evaluate the effects of cold atmospheric plasma (CAP) treatment on the bonding of resin cement to high-translucency zirconia. Zirconia specimens were subjected to different treatments: no treatment (ZrT), 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primer (ZrT-M), alumina particle air-abrasion with/without MDP-containing primer (ZrT-AM/ZrT-A), CAP with/without MDP-containing primer (ZrT-PM/ZrT-P). The surface topography, wettability, and chemical composition were evaluated. The shear bond strength (SBS) was tested before and after thermocycling. CAP did not alter the morphology, increased the wettability, and decreased the carbon/oxygen ratio of zirconia surface. The SBSs of ZrT-PM and ZrT-P were significantly higher than the other groups. After thermocycling, ZrT-A, ZrT-M, ZrT-AM, and ZrT-P showed comparable SBSs, all of which were lower than ZrT-PM. It was concluded that CAP improved the bonding performance of high-translucency zirconia without damaging its surface. The combination of CAP with MDP further enhanced the bond strength and may enable durable bonding.

Enhancing Resin Cement Adhesion to Zirconia by Oxygen Plasma-Aided Silicatization.

The combinations of alumina particle air abrasion (AA) and a 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) primer and a tribochemical silica coating (TSC) and a silane–base primer are contemporary pre-cementation treatments for zirconia restorations for bonding with resin cements. However, the stability of zirconia resists the mechanical or chemical preparations. The purpose of this study was to develop an atmospheric-pressure oxygen plasma (OP)-aided silicatization method to enhance the adhesion of resin cements to zirconia. Zirconia discs were prepared to receive surface treatments of different combinations: (1) AA or TSC (2) with or without OP treatment, and (3) a chemical primer (no primer, silane, or a silane–MDP mixture). The surface morphology, hydrophilicity, and chemical compositions were characterized, and the resin–zirconia bond strengths were examined either after 24 h or a thermocycling test. The results indicated that the OP treatment after the TSC facilitated the homogeneous distribution of silane and crosslinking of silica particles, and effectively improved the hydrophilicity. The OP increased the O and Si and reduced the C elemental contents, while the combination of TSC, OP, and silane induced SiOx generation. Among the groups, only the TSC-OP–silane treatment effectively enhanced the bond strength and maintained the adhesion after thermocycling. With these results, the OP aided the silicatization protocol effectively, generated silane crosslinking, and resulted in superior resin–zirconia bond strength and durability compared to the current treatments.

Effect of Different Cleaning Methods on Shear Bond Strength of Resin Cement to Contaminated Zirconia

The aim of this study was to evaluate the effect of different cleaning methods on the shear bond strength (SBS) of resin cement to contaminated zirconia specimens. Eighty rectangular-shaped specimens (2 × 5 × 10 mm) were fabricated from Zirconia blocks (IPS e.max ZirCAD) and randomly divided into 8 groups (n = 10). Group A (control) was not exposed to contaminants. The following tests specimens were contaminated with saliva and silicone indicating paste. Group B was coated with ceramic primer, then subjected to contamination. Groups C, D, E, F, G, and H were contaminated; cleaned with water rinse, Ivoclean, air particle abrasion, hydrofluoric acid, KATANATM Cleaner and ZirCleanTM, respectively, and then coated with ceramic primer and bonded to dual cure resin cement cylinders. All the specimens were subjected to artificial aging and surviving specimens were subjected to the SBS test. For statistical analysis, ANOVA and multiple comparison methods at the 0.05 significance level were used. There was no statistically significant difference among Ivoclean (21.48 ± 2.90 MPa), air particle abrasion (21.92 ± 2.85 MPa), and the control group (24.68 ± 5.46). The application of ceramic primer before contamination did not preserve the SBS of resin cement to zirconia. Cleaning the contaminated zirconia surface with hydrofluoric acid (15.03 ± 3.63) or KATANATM Cleaner (17.27 ± 7.63) did not restore SBS to the uncontaminated state, but it was significantly higher than simply rinsing with water (12.46 ± 5.17) or the use of ZirCleanTM (11.59 ± 5.53). The bond strength of resin cement to zirconia was influenced by cleaning methods.

Adhesion to a new CAD/CAM resin composite: Effects of the machining roughness simulation, surface treatments, and long-term aging

ObjectivesTo evaluate the effect of surface treatments, finishing condition (polished vs. ground) and aging on the microtensile bond strength of a CAD/CAM resin composite to resin cement. Materials and methodsCAD/CAM resin composite blocks (Tetric CAD HT) were sectioned (7 × 12 × 4 mm), randomly divided according to finishing condition (polished or ground) and surface treatment groups (Ctrl: no treatment; AA: air-abrasion with 110 μm Al2O3 powder; TBS: tribochemical silica coating). A coupling agent corresponding to each surface treatment was applied for cementation (Ctrl and AA groups: ExciTE F DSC; TBS group: RelyX Ceramic Primer) and each block was adhesively cemented (Variolink N) with another one from the same conditioning. Next, 1 mm2 cross-section beams were produced after sectioning, with half being tested under microtensile test after 24 h, while the other half was aged (25,000 cycles of thermocycling + 90 days of storage) (n = 50). Contact angle and Scanning Electron Microscopy (SEM) analysis were performed. Bond strength data (MPa) were statistically analyzed using Three-way ANOVA and Tukey tests (α = 0.05). The failure types were examined and classified as predominantly adhesive, cohesive or mixed under stereomicroscopy. ResultsThe surface treatments (AA and TBS) promoted higher bond strength than the Ctrl group. Grinding finishing improved the bond strength only when no treatment was performed (Ctrl group), having a negative effect for the TBS treatment. The long-term aging damaged the resin bond, independent of the condition. The failure analysis showed that 92% of the failures were classified as adhesive in the baseline conditions, and 94.7% in aged specimens. TBS showed the lowest contact angle among the tested groups for both conditions (baseline and aged). ConclusionSurface conditioning with alumina particle air-abrasion or tribochemical silica coating improves the bond strength. CAD/CAM milling roughness induces better surface condition for adhesion, in particular when no treatment is performed. Bond degradation occurs after long-term aging for all the test conditions. Clinical relevanceWhen luting CAD/CAM resin composite restorations, the surface treatment and roughness due to the grinding by burs in the manufacturing process influence the adhesion of restoration to resin cement.

Surface Treatments and Adhesives Used to Increase the Bond Strength Between Polyetheretherketone and Resin-based Dental Materials: A Scoping Review.

To identify and discuss the available surface treatments and adhesives for polyetheretherketone (PEEK) to increase its bond strength to resin-based materials used in dentistry. The reporting of this scoping review was based on PRISMA. The study protocol was made available at: https://osf.io/4nur9/. Studies which evaluated PEEK surface treatments and its bond strength to resin-based materials were selected. The search was performed in PubMed, Scopus, Web of Sciences and Cochrane databases. The screening was undertaken by 3 independent researchers using the Rayyan program. A descriptive analysis was performed considering study characteristics and main findings (title, data of publication, authors, PEEK characteristics, surface treatments, control group, bonded set, luting agent, specimen geometry, storage, thermocycling, pre-test failures, test geometry, failure analysis, main findings, and compliance with normative guidelines). The initial search yielded 1965 articles, of which 32 were included for descriptive analysis. The review showed that the use of surface treatments and adhesives are important to promote bond strength to PEEK. Up until now, various surface treatments have been explored for bond improvement to PEEK. Sulfuric acid etching is commonly reported as promoting the highest bond strength, followed by alumina-particle air abrasion. Regarding adhesives, the use of a specific adhesive containing MMA, PETIA (pentaerythritol triacrylate), and dimethacrylates yields the best adhesive performance. Sulfuric acid etching and alumina particle air abrasion followed by application of bonding agents containing MMA, PETIA and dimethacrylates are the most effective choices to increase resin-based materials' adhesion to PEEK.

Effect of silanization on shear bond strength between high translucency zirconia and resin cement

Aim: This in-viro study aimed to evaluate and compare the shear bond strength of resin cement with high translucency zirconia with silane coupling agents and bonding agent separately (Group3), bonding agent containing silane (Group 2) and bonding agent which does not have silane (Group 1). Materials and Methods: The study was conducted by using the high translucency zirconia blanks along with the CAD-CAM equipments. After sintering the specimens according to manufacturer’s instructions surface modifications, bonding procedures and evaluation of bond strength was performed. Bond strength of the samples was tested using universal testing machine. The results were analyzed statistically using descriptive analysis. Results: The mean shear bond strength obtained for group 1, group 2 and group 3 was 17.97, 22.01, 28.87MPA respectively. The SBS of group 3 was significantly higher than the other two groups as the surface of zirconia was treated with both Silane and Silane-containing universal adhesive. Conclusion: The null hypothesis was rejected. Within the limitations of the study, it was concluded that the shear bond strength between resin cement and high translucency zirconia was highest when treated with bonding agent (universal adhesive) and silane coupling agent separately after air particle abrasion.

Optical coherence tomography evaluation of deep dentin crack removal techniques

BackgroundThis in vitro study used optical coherence tomography for noninvasive evaluation of the effectiveness of current clinical techniques to remove deep coronal dentin cracks. MethodsStandard dentin cracks were induced on the pulpal floor of 40 decoronated, extracted, sound human posterior teeth using a diamond disk, resembling cracks extending from marginal ridges. The specimens were randomly assigned to 1 of 5 treatment groups for crack removal using airborne-particle abrasion or a bur (fissure, small round, medium round, or tapered fine diamond). Optical coherence tomographic scans were obtained before and after the crack removal. Three-dimensional image registration analyzed the amount of dentin removed and the dimensions of cracks initiated or propagated in each treatment group. ResultsParticle abrasion resulted in the smallest crack propagation in each dimension, which was significantly different from all bur groups (Mann-Whitney, P < .01). Removed dentin depth and width differed among burs (P < .05). All burs resulted in a degree of crack formation, and there was no difference in crack dimensions among bur groups (P > .05). The amount of removed dentin during crack treatment was the largest in the particle abrasion group, which was significantly different from those of the bur groups (Mann-Whitney, P < .005). ConclusionsDental burs used with the purpose of removing pulpal floor dentin cracks induced new small cracks and extended existing cracks, and the volume of removed dentin depended on the shape and size of the bur. Air particle abrasion induced the fewest new cracks despite removing larger dentin volume.