Search Results (64)

Background/Objectives: The increasing clinical integration of 3D-printed definitive resins requires a comprehensive understanding of their physicochemical properties and adhesive behavior. However, there is limited evidence regarding the optimal surface treatment and bonding strategies for clear aligner composite attachments on these materials. This study aimed to characterize a 3D-printed definitive resin, evaluate the effects of surface treatments on its surface topography, and compare the shear bond strength (SBS) of the bonded attachments using different adhesive systems, both before and after thermocycling. Methods: A total of 120 rectangular specimens were fabricated from a 3D printed dental resin (Crowntec^®, SAREMCO Dental AG—Mexico City, Mexico). For physicochemical characterization, six samples underwent scanning electron microscopy/energy-dispersive spectroscopy, X-ray diffraction, and thermogravimetric analysis. To evaluate surface topography, 42 polished specimens were assigned to three groups: untreated (control), etched with 4% hydrofluoric acid (HFA), or sandblasted with 50 µm Al₂O₃ (AA). Each group was subdivided for SEM observation and surface roughness (Ra) measurement. For SBS testing, 72 additional samples received the same surface treatments and were further subdivided according to the adhesive system: Transbond™ XT Primer (TXT) or Single Bond Universal (SBU). Results: The AA group showed the highest Ra (2.21 ± 0.30 µm), followed by HFA (0.81 ± 0.20 µm) and control (0.07 ± 0.30 µm) (p < 0.001). The highest SBS was observed in the AA + SBU group, followed by AA + TXT. Conclusions: Sandblasting with Al₂O₃ particles, combined with a universal adhesive, significantly improved bond strength, suggesting a viable protocol for 3D printed definitive composites in aligner attachment applications. Full article

Objectives: The widespread adoption of three-dimensional (3D)-printed resins in restorative dentistry has introduced significant challenges in establishing strong and lasting bonds with resin-based cements. Despite the development of numerous surface treatment techniques designed to improve adhesion, a clear consensus on the most effective approach remains elusive. This systematic review and meta-analysis critically examined the impact of various surface treatment protocols on the bond strength of 3D-printed resins. By comparing treated versus untreated surfaces, the study aimed to determine the most reliable strategies for enhancing adhesion, ultimately offering evidence-based guidance to inform clinical decision-making. Methods: This review identified relevant studies through a comprehensive search of MEDLINE via PubMed, Web of Science, Scielo, Scopus, and EMBASE databases, supplemented by manual reference checks, to identify in vitro studies published up to February 2025. Studies assessing the bonding of 3D-printed resins following various surface treatments and bonding protocols were included. Data on bond strength outcomes, such as shear bond strength, microtensile bond strength, and microshear bond strength, were extracted. Data extraction included study details, type of 3D-printed resin and printing technology, surface treatment protocols, bond strength testing methods, storage conditions, and results. The quality of included studies was assessed using the ROBDEMat tool. Meta-analyses were performed using the Review Manager Software (version 5.4, The Cochrane Collaboration, Copenhagen, Denmark), with statistical significance set at p < 0.05. Statistical heterogeneity among studies was evaluated using the Cochran Q test and the I² inconsistency test. Results: Nine studies met the criteria for qualitative analysis, with eight included in the meta-analysis. The findings revealed that surface treatment protocols significantly enhanced the immediate bond strength to 3D-printed resins (p = 0.01), with only sandblasting and silane demonstrating a statistically significant effect (p < 0.007). Similarly, after aging, surface treatments continued to improve bond strength (p = 0.01), with sandblasting and hydrofluoric acid being the only methods to produce a significant increase in bond strength values (p < 0.001). Conclusions: This meta-analysis underscores the importance of combining mechanical and chemical surface treatments, especially sandblasting and silane application, to achieve reliable and durable bonding to 3D-printed resins. Full article

BioFlx crowns (BFCs) have been introduced in the dental market, combining the flexibility of stainless steel crowns (SSCs) with the esthetic appeal of preformed zirconia crowns. However, the existing literature does not provide adequate insights regarding the retentive strength of various types of luting cement with these newly developed BFCs. Therefore, this study aimed to evaluate and compare the retentive strength of BFCs and SSCs with different types of luting cement (glass ionomer cement [GIC], resin-modified glass ionomer cement [RMGIC], self-adhesive resin cement [SARC], and polycarboxylate cement [PXC]). A total of 160 standardized resin dies were fabricated and divided into two groups based on the type of crown (BFCs or SSCs). Each group was further subdivided into four subgroups (20/group) based on the luting cement used for cementing the crown on the die. A pullout test was performed using a universal testing machine to measure the retentive strength required for crown dislodgement. The residual cement in the crown was scored to determine the cement failure pattern. Data were analyzed using two-way analyses of variance (ANOVAs) to evaluate the interaction between the cement and the type of crown on retentive strength, followed by an independent t-test. Furthermore, Welch’s ANOVA and Dunnett’s T3 test were used to assess the impact of various types of luting cement on the retentive strength of each crown. The CFP was assessed by comparing the scores using descriptive statistics. Statistical significance was set at p < 0.05. The mean retentive strength of SSCs and BFCs was the highest with SARC (560.29 ± 8.74 N; 657.72 ± 20.60 N), followed by RMGIC (534.20 ± 22.84 N; 454.90 ± 7.95 N) and GIC (435.14 ± 8.66 N; 237.68 ± 9.37 N), while the lowest was with PXC (365.67 ± 19.11 N; 131.26 ± 5.37 N). A significant difference in retention was observed between the crowns (p < 0.05). Cement failure primarily manifested as adhesive failures in the SARC and RMGIC groups; however, both adhesive and cohesive failures occurred in the GIC and PXC groups. Thus, SSCs demonstrate significantly higher retention than BFCs across all types of luting cements, except when using SARC. Within the limitations of this in vitro study, SSCs emerge as the preferred choice for full-coverage restorations that require optimal retention and durability. Nevertheless, BFCs with SARC provide a viable alternative when esthetic considerations are prioritized. Full article

Background: Polymerization shrinkage of composite resins affects the marginal closure of direct dental restorations. It is responsible for developing secondary caries and indirectly affects the survival rate of restorations. This study aims to investigate the null hypothesis, which states that there are no significant differences in the marginal microleakage of Class II restorations when examined in vitro using different dental adhesives, whether the restoration material used is a composite with glass fiber reinforcement or not. Methods: Class II cavities were prepared on both proximal surfaces of thirty-six extracted human molars. A single-component (Universal VivaPen) and a two-component (Futurabond DC) self-etch adhesive system were used for the restorations in the control group (Charisma Classic) and the experimental group (Charisma Classic with Interlig glass fiber strip). An oblique layering technique and a 40-s soft-start light-curing polymerization were used. After selective pre-isolation, the specimens were placed in a 0.2% methylene blue solution and incubated at 37 °C for 24 h. The teeth were sectioned in the mesiodistal direction, and two examiners examined and graded the extent of dye penetration. Statistical analysis was conducted using the Mann–Whitney U and chi-square tests (p < 0.05). Results: All the composite restorations reinforced with glass fiber showed significantly reduced dye infiltration compared to the control group (p < 0.05). A significant difference (p < 0.05) was also observed between the two adhesives. Conclusions: The null hypothesis was rejected. Glass fiber strips significantly reduced composite restoration microleakage regardless of the adhesive. The marginal fit of the restoration was also influenced by the adhesive system used. Full article

Background/Objectives: The presence of enamel on the tooth surface is crucial for the long-term success of minimally invasive adhesive restorations such as dental veneers. Our study aims to evaluate the enamel thickness in the incisal, middle, and cervical portions of the labial surface of the upper central incisors using cone beam computed tomography (CBCT). This imaging method provides detailed and accurate three-dimensional images with a low radiation dose, allowing an accurate assessment of enamel thickness. The analysis aims to identify variations in enamel thickness depending on the age and different levels of the labial tooth surface. Methods: 800 CBCT scans performed for diagnostic or therapeutic purposes on patients aged 18–60 years were analyzed. The data were gathered from the imaging archives of private practitioners from Targu Mures and the “George Emil Palade” University of Medicine, Pharmacy, Science, and Technology of Targu Mures. Enamel thickness measurements were conducted using the OnDemand3D Communicator CBCT evaluation program, with subsequent statistical analysis performed using GraphPad Instat Prism software. Results: Results showed significant variation in enamel thickness between the incisal, middle, and cervical segments of the labial surface of the upper central incisors. A decrease in enamel thickness with age has been observed. In patients aged 18–40, mean values of enamel thickness 1 mm and 3 mm above the cementoenamel junction (CEJ) were 0.48 ± 0.092, respectively, 0.819 ± 0.158. In patients over 40, the mean values were 0.454 ± 0.116 and 0.751 ± 0.067 at 1 mm, respectively, 3 mm above the CEJ. Statistically significant differences were found between the two age groups at 1 mm and 3 mm above the CEJ, with p < 0.0001 and p = 0.0214. Conclusions: A statistically significant decrease can be observed in enamel thickness in almost the entire labial surface of the upper central incisors with aging. The varied thickness of the enamel at different tooth levels requires individualized planning for each patient to maximize the long-term aesthetic and functional results. Full article

Dental adhesives play a crucial role in modern dentistry by enabling the bonding of diverse restorative materials to tooth surfaces. These systems have evolved through seven generations, each characterized by unique chemical compositions and application techniques. The advancements in dental adhesives have significantly impacted restorative dentistry by preserving tooth structure, enhancing aesthetics, and ultimately improving patient outcomes and treatment options. The choice of adhesive system depends on various factors, including the clinical scenario, material compatibility, and dentist preference. Ongoing advancements in adhesive technology continue to enhance treatment outcomes and streamline procedures for dental practitioners. The development of universal adhesives capable of functioning in both etch-and-rinse and self-etch modes has further simplified clinical protocols. This study is an observational cross-sectional study conducted among Romanian dentists. A questionnaire was distributed via email to Romanian dentists, encompassing seven questions that explored the predominant use of etch-and-rinse or self-etch adhesive systems, preferred adhesive types, and commonly encountered challenges in direct restorations. Statistical analyses were conducted using DATAtab version (2024). The study highlighted the varying preferences among Romanian dentists in selecting suitable adhesive agents. Etch-and-rinse (ER) techniques predominated in direct restorations, with universal adhesives being the most frequently used. Further investigation is warranted to delve into the preferences of Romanian dentists regarding the utilization of self-etch (SE), etch-and-rinse (ER), and universal adhesives (UAs). Full article

The rapid evolution of lithium silicate-based glass ceramics in the field of dental ceramics has led to the availability of different compositions in the market. This in vitro study was conducted to assess an effective protocol for recementing de-bonded lithium silicate-based glass ceramics by evaluating the shear bond strength of three reseating methods. The study included IPS e.max^® CAD, Vita Suprinity^®, Celtra Duo^®, and n!ce as lithium-based glass ceramics. The samples underwent a series of preparation steps, including embedding in acrylic resin, hand polishing, etching with 5% hydrofluoric acid, and application of universal primer and adhesive as per manufacturer instructions. Subsequently, adhesive resin cement was applied to the ceramic tablets, and shear bond strength was assessed using a standardized method. The findings revealed that no single method demonstrated significantly superior results compared to the others. However, it was observed that etching with 5% hydrofluoric acid for 20 s yielded favorable outcomes in terms of time efficiency and standardized results. Additionally, it was noted that although sandblasting increased surface area, it did not enhance bond strength due to unfavorable surface disturbance. In conclusion, the study suggests that etching with 5% hydrofluoric acid for 20 s is a favorable protocol for reseating de-bonded lithium disilicate-based glass ceramics, offering both time efficiency and consistent results for clinicians. Full article

The central aim of adhesive dentistry is to improve the compatibility between current adhesives and a range of substrates by employing diverse application techniques. Therefore, the overarching objective of this review is to offer a comprehensive analysis of dentin bonding systems, starting with an introduction to adhesion and a detailed overview of enamel and dentin structures, their histology, and the impact of dentin structure on resin–dentin bonding. It covers the mechanisms of resin–dentin bonding, including resin adhesive application, bonding mechanisms, and factors influencing efficacy. Further, this review explores the composition of resin adhesive systems, including acidic components, cross-linking monomers, solvents, and other critical elements. It also examines various adhesive strategies—etch-and-rinse, self-etch, and universal adhesives—highlighting their applications and advantages. The review extends to clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), demonstrating the practical implications of adhesive systems in enhancing restoration longevity and performance. In conclusion, despite significant advancements, no gold-standard method for optimal adhesion exists. Each adhesive system has distinct strengths and limitations. The review emphasizes the importance of evaluating methods for achieving durable adhesion and staying current with technological advancements in adhesive systems. Summary: This review provides a thorough analysis of dentin bonding systems, delving into the structures and bonding mechanisms of both enamel and dentin. By exploring various adhesive systems and their components, it highlights the ongoing challenges in achieving optimal resin–dentin adhesion. The review also addresses the clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), illustrating how different adhesive techniques impact clinical outcomes. It underscores the necessity for continuous innovation and assessment of adhesive systems to enhance long-term bonding effectiveness in clinical practice. Full article

The objectives of this study were to evaluate the bonding durability of four different self-etch adhesives to dentin after 24 h and thermal cycling (TC) and to measure the degree of polymerization conversion (DC) in situ. Two-step self-etch adhesives, Clearfil SE Bond 2 (SE2, Kuraray Noritake Dental) and G2-Bond Universal (G2B, GC), and one-step self-etch adhesives, Scotchbond™ Universal Plus Adhesive (SBU, 3M ESPE) and Clearfil Universal Bond Quick (UBQ, Kuraray Noritake Dental), were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces. The adhesives were applied according to the manufacturers’ instructions. After resin composite buildup and 24 h water storage, the specimens were sectioned into beams and all groups were subjected to thermal stress for 0, 10,000 (10k), or 20,000 (20k) cycles followed by micro-tensile bond strength (µTBS) testing. In situ DC was investigated with a laser Raman microscope. The µTBS data were statistically analyzed and subjected to a Weibull analysis. The different groups were compared at the characteristic strength (63.2% probability of failure) (α = 0.05). Two-Way ANOVA was used to show the effect of different adhesives and thermal cycling on the mean DC% followed by Tukey’s multiple comparison post hoc test. G2B/TC10k resulted in a significant increase in the µTBS compared to TC0. SBU/TC20k showed significantly higher µTBS compared to TC0. For comparison between different tested adhesives, SBU showed a significantly lower µTBS compared to G2B after TC10k. G2B and SBU showed a greater number of adhesive failures after TC. Mean DC% was different for each adhesive. The newly developed MDP- and HEMA-free 2-SEA showed similar bonding performance with the gold-standard 2-SEA. However, there is still room for further improvement in terms of SEAs. Full article

The development of high-filled 3D printing resin necessitates a bonding protocol for dental indirect restorations to achieve optimal bond strength after cementation. This study evaluates shear bond strengths of high-filler 3D printed materials for permanent restorations with various surface treatments. Rodin Sculpture 1.0 (50% lithium disilicate fillers) and 2.0 Ceramic Nanohybrid (>60% zirconia and lithium disilicate fillers) were tested, with Aelite All-Purpose Body composite resin as control. Samples were prepared, post-cured, and sandblasted with alumina (25 µm). Surface roughness was analyzed using an optical profilometer. Two bonding protocols were compared. First, groups were treated with lithium disilicate silane (Porcelain Primer) or zirconia primer (Z-Prime Plus) or left untreated without a bonding agent. Beam-shaped resin cement (DuoLink Universal) specimens were bonded and stored in a 37 °C water bath. Second, additional sets of materials were coated with a bonding agent (All-Bond Universal), either followed by silane application or left untreated. These sets were then similarly stored alongside resin cement specimens. Shear bond tests were performed after 24 h. SEM images were taken after debonding. One-Way ANOVA and post hoc Duncan were performed for the statistical analysis. Rodin 1.0 exhibited increased adhesive failure with silane or zirconia primer coating, but significantly improved bond strengths with bonding agent application. Rodin 2.0 showed consistent bond strengths regardless of bonding agent application, but cohesive failure rates increased with bonding agent and filler coating. In all groups, except for Rodin 1.0 without bonding agent, silane coating increased cohesive failure rate. In conclusion, optimal shear bond strength for high-filler 3D printing materials can be achieved with silane coating and bonding agent application. Full article

Modern conservative dentistry is taking the lead in daily clinical practice and is relying on adhesion. Whether it is a simple composite, ceramic inlays, onlays, veneers or crowns, the common factor for a successful outcome is a good bonding of these elements to dental structures. Thus, the purpose of this study was to evaluate the bond strength of resin composite to dentin when using a new device, the DENTIPURE KM™ (KM, Beirut, Lebanon), which provides a pure air flow, free of any contaminants and without humidity, when compared to other dental equipment. One hundred and eighty extracted human molars were equally divided into three groups according to the device used, the DENTIPURE KM™ (KM, Beirut, Lebanon), the KAVO™ (ESTETICA E30/E70/E80 Vision, KAVO, Biberach, Germany), or the ADEC™ (A-dec Performer 200, Newberg, OR, USA). The shear bond strength (SBS) was evaluated after 24 h of storage in distilled water on a universal testing machine. Statistical analysis was set with a level of significance at p ≤ 0.05. The results revealed that significantly different bond strength was imparted by the DENTIPURE KM™ device and the ADEC™ dental unit (p = 0.042). In conclusion, while the DENTIPURE KM™ device shows promise in providing contaminant-free air during bonding, its impact on dentin bond strength compared to devices like the KAVO™ appears minimal. Further research is needed to fully assess its potential in enhancing dentinal adhesion procedures. Full article

Ensuring a secure bond between a framework structure and layering composite resin veneer is essential for a long-lasting dental restoration. A variety of primer systems are available to facilitate the adhesive bonding. Nevertheless, the growing preference for efficiency and simplicity in dentistry has made the one-bottle universal primers a desirable option. This study aims to compare the effectiveness of universal primers on the shear bond strength (SBS) of base metal alloy (BMA) and zirconia to layering composite resin. Each 160 BMA and zirconia 20 × 10 × 5 mm test specimen was fabricated. Eight different primers (SunCera Metal Primer, Metal Primer Z, Reliance Metal Primer, Alloy Primer, MKZ Primer, Monobond Plus, ArtPrime Plus, and Clearfil Ceramic Primer Plus) were applied to 20 specimens in each group. Subsequently, a 5 × 2 mm composite resin build-up was applied. SBS tests were performed after 24 h of water storage and after thermocycling (25,000 cycles, 5–55 °C). On BMA, after water storage for 24 h, the bond strength values ranged from 26.53 ± 3.28 MPa (Metal Primer Z) to 29.72 ± 2.00 MPa (MKZ Primer), while after thermocycling, bond strength values ranged from 25.19 ± 1.73 MPa (MKZ Primer) to 27.69 ± 2.37 MPa (Clearfil Ceramic Primer Plus). On a zirconia base, after 24 h, the bond strengths values ranged from 22.63 ± 2.28 MPa (Reliance Primer) to 29.96 ± 2.37 MPa (MKZ Primer) and from 23.77 ± 3.86 MPa (Metal Primer Z) to 28.88 ± 3.09 MPa (Monobond Plus) after thermocycling. While no significant difference in bond strength was found between the primers on the BMA base, five primer combinations differed significantly from each other on zirconia (p = 0.002–0.043). All primers achieved a bond strength greater than 23 MPa on both framework materials after thermocycling. Thus, all primers tested can be applied to both framework materials with comparable results. Full article

Cement film thickness may have an impact on the shear bond strength (SBS) of lithium disilicate dental ceramics luted to human enamel with resin cement. The objective of this study was to evaluate SBS of lithium disilicate ceramics adhered to enamel using resin cement at different thicknesses. In total, 50 ceramic specimens (3 × 3 × 3 mm) and 50 premolar teeth were prepared and randomly assigned to 5 groups (n = 10 each). Ceramic specimens were designed with five cement film thicknesses (50 μm; 100 μm; 150 μm; 200 μm; and 300 μm). Teeth surfaces (4 × 4 mm) were prepared with a high-speed handpiece mounted on a dental surveyor. Ceramic specimens were cemented to teeth with resin cement (3M^TM RelyX^TM U200, Resin-Self-Adhesive-Cement). The specimens were then thermocycled for 6000 cycles with a 30 s dwell time and a 5 s transfer time in water (5 °C and 55 °C). A Universal-Testing-Machine was used to measure SBS (MPa). Statistical analysis in SPSS included Anova and Tukey’s tests. The SBSs of ceramics adhered to teeth revealed significantly different values across all test groups (p = 0.000). The findings showed that as cement layer thickness increased, so did the SBS. The cement spaces at 50 and 300 μm had the lowest SBS (9.40 + 1.15 MPa) and maximum SBS (21.98 + 1.27 MPa), respectively. The SBS of the lithium disilicate ceramic luted to natural human enamel increased along with the cement layer thickness. Full article

Even after more than six decades of dental composite invention (1962), there is still controversial information about the time in which composite restorations should be polished in order to avoid marginal gap formation at the tooth–composite interface. The aim of the present study was to analyze the influence of adhesive strategy, the type of dental composite, and polishing time on marginal gap formation (%MG) at the tooth–composite interface. Class I-like cavities were hybridized with a universal adhesive system (Single Bond Universal) through two strategies: selective enamel etching (SEE) or self-etching mode (SEM). Cavities were filled with two types of dental composites: nanofilled (Z350) or bulk fill (Filtek One Bulk Fill—ONE), and polishing was performed immediately or delayed for 7 days (n = 5). %MG was evaluated by using a 3D laser confocal microscope. As flexural modulus (FM) and degree of conversion (DC%) are determinants of marginal integrity in dental composite restorations, these properties were evaluated for both composites. Data were analyzed by ANOVA and Tukey’s HSD test (α = 0.05). Cavities hybridized following the SEE strategy presented lower %MG (p < 0.05). Z350 showed higher %MG than ONE (p < 0.05). There was no difference in %MG between the polishing times when the SEE strategy was used (p > 0.05). Z350 presented higher FM than ONE (p < 0.05). DC% was found to be not significant (p > 0.05). The results suggest that selective enamel etching (SEE) is a better strategy for producing less %MG in composite restorations with enamel margins irrespective of the time in which the restoration is polished. Full article

The purpose of this paper is to compare the fracture behavior of interfaces obtained using fourth-generation and universal dental adhesives. The study relies on optic and SEM to evaluate the dentin–adhesive–restoration material interface of the samples and also on FEA simulation of fracture behavior. Specimen fabrication relied on 20 extracted teeth, in which class I cavities were created according to a protocol established based on the rules of minimally invasive therapy. For the direct adhesive technique, the adhesives used were: three-step All Bond, three-batch A and one-step Clearfil Universal Bond Quick-batch B. The restoration was performed with the same composite for both adhesives: Gradia direct posterior. The simulation used a 3D reconstructed molar on which geometric operations were performed to obtain an assembly that replicated a physical specimen. Material properties were applied to each component based on the information found in the literature. A simplified model for crack propagation was constructed, and using the fracture mechanics tool in Ansys 2019, the stress intensity factors that act at the crack tip of the adhesive interface were obtained. Mechanical simulation and microscopic investigation showed us how the interface of the dentine–adhesive–filling material performed in cases of both dental adhesives and for a certain loading condition. Important differences were identified among the adhesives, the fourth generation being superior to the fourth generation especially due to the separate steps in which the tooth surface was prepared for adhesion. Full article