Evaluation of the efficacy of a simulation model used in oral and maxillofacial surgery education.

BACKGROUND: The traditional teaching methods of dental education are gradually being replaced with futuristic education methods based on the usage of educational tools such as mannequin-based simulation models and virtual reality. However, the effectiveness of mannequin-based simulation models as a learning method in the field of oral surgery remains unclear. This study aims to investigate the efficacy of training on a tooth extraction model (TEM) in view of undergraduate dental students' experience and perception of their education. METHODS: A quasi-experimental trial was implemented with two consecutive year classes, totaling 136 students at the Dentistry Faculty of Altinbas University, Turkiye. Two cohorts were created from dental students in the classes of 2023 and 2022 graduates. Cohort 1 (n = 71) received 14 h of theoretical education followed by 10 h of preclinical education on TEM. Cohort 2 (n = 65) received only 14 h of theoretical education. An anonymous questionnaire was prepared with four main sections including the preferences of learning style, participants' perceptions of the preclinical training methods, the students' competency and free text comments. Students' opinions were quantified with both 7-point Likert scales and thematic analysis. Anxiety levels were measured with the interval scale of anxiety response (ISAR). Descriptive statistics, inferential statistical and thematic analyses were conducted according to survey responses. Student characteristics were summarized and compared for two cohorts using a t-test. For all statistical analyses, the significance level was set atP ≤ 0.05. RESULT: Cohort 1 was more comfortable with sequential motions performed with the forceps (P = 0.033) and felt more ready for their first clinical tooth extraction experience (P = 0.028). Cohort 2 showed a significantly higher preference for textbooks among supplementary materials (P = 0.04); however, they tended to exhibit lower self-confidence and higher anxiety levels, though without any statistical significance (P > 0.05). CONCLUSION: It is clear that the students who have yet to start seeing patients benefit from increased practice with training models, which adequately reflect and represent real-life situations encountered in everyday practice.

Ultrastructural investigation of the effect of toothpastes containing different remineralizing agents on demineralized enamel.

OBJECTIVE: The present study aimed to evaluate the effect of remineralizing agents on demineralized enamel intended for use as fluoride substitutes or supplements for oral hygiene applications. METHODOLOGY: Enamel samples were obtained from 30 bovine teeth. The enamel blocks were stored in 20 mL of demineralization solution for 72 h. They were then brushed with the following toothpaste for the remineralization protocol: NaF, NaF/SnF2 combination, NovaMin, or nano-hydroxyapatite. SEM/EDX examinations and microhardness measurements of the samples were performed to investigate the remineralization efficacy of the studied toothpaste. One-way analysis of variance (ANOVA) with post hoc Tukey's HSD test was used to analyze the change in microhardness values in different remineralization protocols (p < 0.05). RESULTS: Differences in the mean remineralization (%RP) and hardness recovery (%HR) were determined between the groups (p < 0.05). Groups 1 and 4 showed significant differences in %RP (p < 0.05). In the SEM/EDX examinations, the samples treated with n-HAp showed an accumulation of crystal deposits on the enamel surface, although at a lower density than those treated with NaF and NaF/SnF2 combination. CONCLUSION: The remineralization strategy in toothpaste plays an important role in enamel remineralization. NovaMin-containing toothpaste showed positive effects on the enamel surface with better Ca/P ratio. Toothpastes containing n-HAp triggered less change in the increase of microhardness values compared to other toothpastes. The use of SnF2 in toothpaste in combination with NaF significantly increased the binding of fluoride to demineralized enamel compared to toothpaste containing NaF alone.

Influence of surface treatments and adhesive protocols on repair bond strength of glass-matrix and resin-matrix CAD/CAM ceramics.

OBJECTIVE: To specify the effects of self-etching ceramic primer, Monobond Etch and Prime (MEP), and universal adhesive (UA) on repair bond strength between CAD/CAM blocks and resin composite. MATERIALS AND METHODS: Vita Mark II (VM), IPS e.max CAD (EMAX), Shofu Block HC (SHC), and Tetric CAD (TET) blocks were sliced and thermocycled. They were divided into four groups according to surface treatments (n = 24): control, sandblasting (AL), hydrofluoric acid etching (HF), and MEP application. SEM analysis assessed surface topography. Subdivided, specimens followed distinct adhesive protocols (n = 12): control (silane + adhesive [SA] or adhesive [A] only for MEP group) and UA. Microshear bond strength (µSBS) was measured following resin composite repair. Data were analyzed using two-way ANOVA and Tukey tests (p < 0.05). RESULTS: The µSBS of CAD/CAM blocks was significantly influenced by surface treatment type and adhesive protocol. The highest µSBS values for each block, considering surface treatment + adhesive protocol, were VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA. CONCLUSIONS: Except for EMAX, it was not the adhesive protocol that made the significant difference in bond strength for each CAD/CAM block, but the surface treatment. MEP + UA application on glass ceramics lowered µSBS values significantly, so it is not recommended in clinical conditions. CLINICAL SIGNIFICANCE: Repair is an essential therapeutic option, particularly in esthetic restorations, to swiftly repair the impaired esthetics caused by fracture. Repair protocol is dependent on the restorative material, and to have a reliable repair bond strength, the following surface treatment and adhesive protocol combinations are recommended for each CAD/CAM block: VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA.

Effects of calcium silicate-based cements on odonto/osteogenic differentiation potential in mesenchymal stem cells.

The objective of this study was to evaluate the biological effects and odonto/osteogenic differentiation potential of Biodentine, NeoMTA Plus and TheraCal LC in tooth germ-derived stem cells (TGSCs). TGSCs were exposed to the material extracts. Biocompatibility was tested with MTS cell proliferation assay. Odonto/osteogenic differentiation was assessed with alkaline phosphatase (ALP) activity and mRNA gene expressions (RUNX2, DSPP and DMP-1). Scanning electronic microscopy/energy-dispersive X-ray (SEM/EDX) analysis and pH analysis were also performed for the materials. Data were evaluated using the one-way ANOVA and Tukey's tests. TGSCs remained viable after 7 days of incubation with all tested materials. Biodentine and NeoMTA Plus showed high ALP activity and increased expression of RUNX2, DSPP and DMP-1 compared to that of TheraCal LC. All materials can induce odonto/osteogenic differentiation of MSCs in various levels. Biocompatibility and odonto/osteogenic differentiation potential of Biodentine and NeoMTA Plus are similar and superior to that of TheraCal LC.

Does Knot Configuration Improve Tensile Characteristics of Monofilament Suture Materials?

PURPOSE: The effects of knot configuration used in surgical procedures are often overlooked when surgeons are looking for an ideal suture material. This study aimed to investigate the mechanical properties of monofilament suture materials used in oral and maxillofacial surgery under diverse knot configurations. MATERIALS AND METHODS: A custom-made experimental platform and a microtensile test device were used to evaluate the mechanical properties of the tested subjects. There were 2 predictor variables: suture material and knot configuration. Three types of nonabsorbable and monofilament suture materials with 4-0 gauge, including nylon, polypropylene, and polytetrafluoroethylene, were tested. Four different knot configurations-a surgeon's knot square plus a square knot (2 = 1 = 1), a surgeon's knot granny plus a square knot (2 × 1 = 1), a reverse surgeon's knot granny plus a square knot (1 × 2 = 1), and a reverse surgeon's knot square plus a square knot (1 = 2 = 1)-were also used with each of the suture materials. The tensile strength (N) and elongation (µm) of each sample were measured as the outcomes. The data were statistically analyzed using 2-way analysis of variance and Tukey's honestly significant difference tests. The significance level was set at P < .05. RESULTS: Overall, 120 samples were tested. Statistical analysis revealed that the highest tensile strength (28.6 N) was found for nylon in the surgeon's knot square plus a square knot (P < .05). Polypropylene showed a similar high tensile strength value (24.7 N) in the reverse surgeon's knot granny plus a square knot (P > .05). Polytetrafluoroethylene demonstrated significantly lower values for both tensile strength in tested configurations (within the range of 5.2-8.5 N). Under diverse configurations, polypropylene suture samples offered the most stable tensile strength and elongation. CONCLUSIONS: The present study demonstrated that different knot configurations might improve the mechanical profile of commonly used monofilament suture materials. The surgeon's knot square (2 = 1), commonly used by surgeons worldwide, proved to be the most beneficial knot configuration in this study in terms of tensile strength and elongation. Further research on optimal knot configuration may be just as important as seeking an ideal suture material.

Adhesive Performance of Resin Cement to Glass-Ceramic and Polymer-Based Ceramic CAD/CAM Materials after Applying Self-Etching Ceramic Primer or Different Surface Treatments.

Ensuring optimum bond strength during cementation is vital for restoration success, with the practicality of the process being crucial in clinical practice. This study analyzed the effect of a single-step self-etching ceramic primer (MEP) and various surface treatments on the microshear bond strength (µSBS) between resin cement and glass-ceramic or polymer-based ceramic CAD/CAM materials. Specimens were fabricated from leucite-based glass-ceramic (LEU), lithium disilicate glass-ceramic (LDC), resin nanoceramic (RNC), and polymer infiltrated ceramic network (PICN) (n = 160). They were then classified based on the surface treatments (n = 10): control (no treatment); sandblasting with Al2O3 (AL); etching with hydrofluoric acid (HF); and MEP application. Scanning electron microscopy was used to evaluate the surface topography. µSBS was measured after cementation and thermocycling procedures. Failure modes were examined with a stereomicroscope. Statistical analysis involved two-way analysis of variance and Tukey HSD tests with a significance level of 0.05. µSBS was significantly influenced by both surface treatment and CAD/CAM material type. The most enhanced µSBS values for each material, regarding the surface treatment, were: LEU and LDC, HF; RNC, AL; PICN, AL or HF. MEP significantly increased the µSBS values of CAD/CAM materials except RNC, yet it did not yield the highest µSBS values for any of them.

Effects of acidic beverages on color stability of bulk-fill composites with different viscosities / Efectos de las bebidas ácidas sobre la estabilidad del color de resinas tipo Bulk con diferentes viscosidades

Abstract The aim of this in vitro study is to investigate the effects of acidic beverages on the discoloration of bulk-fill composites with different viscosities. 144 disc-shaped specimens (8mm diameter × 2mm thick) were prepared from four different composite resins including a nanohybrid (Filtek Ultimate), two packable bulk- fill (Filtek Bulk Fill, Tetric N Ceram Bulk Fill), and a flowable bulk-fill composite (Tetric N Flow Bulk Fill). The specimens of each group were divided into 3 subgroups and submerged in distilled water, orange juice and coke (n=12). Color difference (ΔE) were measured using CIELab color space and a compact spectrophotometer (VITA Easyshade) at baseline and after 30 days of immersion. Data were analyzed using two- way ANOVA and Tukeys HSD post-hoc tests (P2.7) was observed for all bulk-fill composites tested. It can be speculated that orange juice has a more negative effect on the color stability compared to coke. Additionally, flowable bulk-fill composite was more prone to discoloration than condensable bulk-fill composites.

Resumen El objetivo de este estudio fue investigar los efectos de las bebidas ácidas en la decoloración de resinas compuestas tipo Bulk con diferentes viscosidades. Se prepararon 144 muestras en forma de disco (8mm de diámetro x 2mm de grosor) a partir de cuatro resinas compuestas diferentes que incluyen un nanohíbrido (Filtek Ultimate), dos de pasta condensables tipo Bulk (Filtek Bulk Fill, Tetric N Ceram Bulk Fill) y una fluida (Tetric N Flow Bulk Fill). Las muestras de cada grupo se dividieron en 3 subgrupos y se sumergieron en agua destilada, jugo de naranja y Coca-Cola (n=12). La diferencia de color (ΔE) se midió utilizando el CIELab y un espectrofotómetro compacto (VITA Easyshade) al inicio y después de 30 días de inmersión. Los datos se analizaron mediante ANOVA bidireccional y pruebas post-hoc HSD de Tukey (P2,7) para todos los materiales resinosos. Se puede especular que el jugo de naranja tiene un efecto más negativo sobre la estabilidad del color en comparación con la Coca-Cola. Además, la resina fluida fue más propensa a la decoloración que las resinas condensables.

The cytotoxic effects of various endodontic irrigants on the viability of dental mesenchymal stem cells.

This study aimed to evaluate cytotoxic effects of various irrigation solutions used in regenerative endodontic treatments (RETs) on mesenchymal stem cells, and further examine the long-term effect of hypochlorous acid (HOCl) on the cell viability and alkaline phosphatase (ALP) activity. Stem cells were exposed to various concentrations of NaOCl, EDTA, chlorhexidine (CHX), etidronic acid (HEDP)/NaOCl combination and HOCl. HOCl was tested for its effects on ALP activity up to 21 days. Additionally, cell viability was measured fluorescently using calcein AM. The most cytotoxic irrigant was CHX even with the lowest concentration. NaOCl and HEDP/NaOCl with 1:100 dilution decreased viability to around 40%. HOCl showed the lowest cytotoxicity among all tested irrigants. HOCl also showed no significant reduction in ALP activity compared with the controls. The cytotoxicity of endodontic irrigants was time and concentration dependent. HOCl demonstrated promising results regarding viability and ALP activity, since RETs require host stem cell survival.

Comparison between tensile characteristics of various suture materials with two suture techniques: an in vitro study.

OBJECTIVE: The first objective of the present study was to evaluate the tensile strength and elongation to failure of commonly used suture materials in oral surgery. As a secondary objective, it was aimed to make a comparison between two different suture techniques within the same suture materials. MATERIALS AND METHODS: Eight different suture materials with 3-0 gauge (silk, polytetrafluoroethylene, polypropylene, polyester, polyglactin 910, polyglycolic acid, poliglecaprone 25, polydioxanone) underwent tensile testing for maximum load of failure and elongation rate. All strands were tied by one investigator on the experimental platform using the surgeon's knot plus additional square knots in both simple suture and horizontal mattress suture techniques. Prepared specimens were examined using a microtensile testing device before (baseline) and after 3, 7, and 14 days' immersion in artificial saliva. RESULTS: Statistical analysis of the current study revealed that the tensile strength for polyglycolic acid, polyglactin 910, polypropylene, and silk sutures was significantly lower at day 3 than at the baseline. By day 14, polyglycolic acid and polyglactin 910 showed a significant reduction in tensile strength for both techniques. While polydioxanone obtained the highest tensile strength and elongation values in both techniques, polytetrafluoroethylene showed the most stable tensile strength even with the lowest value. Tensile strength in simple suture techniques was almost twice than that of horizontal mattress suture technique for each specimen. CONCLUSIONS: Polyglycolic acid and polyglactin 910 were considerably sensitive to immersion time. Polydioxanone demonstrated optimum performance during each immersion period among the tested materials, whereas polytetrafluoroethylene was the most stable. CLINICAL RELEVANCE: The selection of the most proper suture material remains challenging for clinicians. The present study provides relevant information for clinicians to guide them in their choice of the suitable material. In this context, clinicians can benefit from the use of polydioxanone for its high tensile strength regardless of the suture technique used, whereas polytetrafluoroethylene shows a long-term stability. The strength and stability differences among suture materials and techniques need to be considered before making an informed decision.

Impact of peri-implant bone resorption, prosthetic materials, and crown to implant ratio on the stress distribution of short implants: a finite element analysis.

The purpose of this study was to determine the effects of prosthetic materials and crown/implant (C/I) ratio on short implants with a marginal bone resorption. Three-dimensional finite element analysis was used to simulate stress distribution under static loading in non-resorption and resorption scenarios (3-mm vertical bone loss) in implants restored with single crowns and C/I ratios of 1:1, 1.5:1, and 2:1 were evaluated. Different crown materials were used: porcelain-fused to metal, porcelain-fused to zirconia, monolithic zirconia, and zirconia-based crown veneered with indirect composite resin. The C/I ratio, the peri-implant bone resorption, and the loading conditions were the key factors affecting the generated stress in short implants. In non-resorption models, von Mises stress ranged between 50 and 105 MPa whereas in resorption models, the values ranged from 168 to 322 MPa, both increasing with the higher C/I ratio under oblique forces. Under axial loading, the C/I ratio did not influence the stress values as the presence of resorption was the only parameter increasing, 57 MPa for the non-resorption models and 101 MPa for the resorption models, respectively. Preference of a prosthetic material was ineffective on the distribution of stress in the bone and implant structure under static loading in any models. The peri-implant bone resorption and a higher C/I ratio in short implants increase the stress values under both axial and oblique forces, whereas the crown material does not influence stress distribution in the surrounding bone and implant structure.

Dentin-Pulp Tissue Regeneration Approaches in Dentistry: An Overview and Current Trends.

Conventional treatment approaches in irreversible pulpitis and apical periodontitis include the disinfection of the pulp space followed by filling with various materials, which is commonly known as the root canal treatment. Disadvantages including the loss of tooth vitality and defense mechanism against carious lesions, susceptibility to fractures, discoloration and microleakage led to the development of regenerative therapies for the dentin pulp-complex. The goal of dentin-pulp tissue regeneration is to reestablish the physiological pulp function such as pulp sensibility, pulp repair capability by mineralization and pulp immunity. Recent dentin-pulp tissue regeneration approaches can be divided into cell homing and cell transplantation. Cell based approaches include a suitable scaffold for the delivery of potent stem cells with or without bioactive molecules into the root canal system while cell homing is based on the recruitment of host endogenous stem cells from the resident tissue including periapical region or dental pulp. This review discusses the recent treatment modalities in dentin-pulp tissue regeneration through tissue engineering and current challenges and trends in this field of research.

Influence of different surface treatments and universal adhesives on the repair of CAD-CAM composite resins: An in vitro study.

STATEMENT OF PROBLEM: The repairability of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins might be adversely affected by the high degree of matrix polymerization that occurs during their manufacturing process. However, information on their repairability is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the microtensile bond strength of CAD-CAM composite resins subjected to simulated repair procedures by using varying surface treatments and universal adhesives. MATERIAL AND METHODS: Four different CAD-CAM blocks (Brilliant Crios, Lava Ultimate, Shofu Block HC, and Vita Enamic) were thermocycled (5000 times, 5/55 °C) and divided into 4 groups according to the surface treatment: control, 9% hydrofluoric acid etching, aluminum oxide airborne-particle abrasion, and tribochemical silica airborne-particle abrasion. After surface treatments, the surface roughness was measured with a nanoindenter and further examined with scanning electron microscopy. After the application of 3 different universal adhesives (Clearfil Universal Bond, Prime&Bond Universal, and Single Bond Universal), the specimens were subjected to a simulated repair process with composite resin. Bonded specimens were cut into 1 mm2 beams, and microtensile bond strength values were determined until failure at a crosshead speed of 0.5 mm/min. The bond strength data were analyzed with 3-way analysis of variance, and surface roughness data were analyzed with 2-way analysis of variance tests. Pairwise analyses were performed with the Tukey test (α=.05). RESULTS: All surface treatments effectively improved repair microtensile bond strength values compared with the control (P<.05). Aluminum oxide airborne-particle abrasion had similar mean bond strength values compared with tribochemical silica airborne-particle abrasion (P>.05). Among the CAD-CAM blocks treated with hydrofluoric acid etching, Vita Enamic had the highest mean bond strength values. The highest mean microtensile bond strength repair values with the highest cohesive failure rates were found with the silane-containing universal adhesive (Single Bond Universal). CONCLUSIONS: Surface treatment with aluminum oxide airborne-particle abrasion and tribochemical silica airborne-particle abrasion produced successful repair results for aged resin nanoceramics, whereas hydrofluoric acid etching can be used for aged hybrid ceramic repair. Silane-containing universal adhesive reported increased bond strength. Application of universal adhesive after surface treatment is recommended to increase repair strength.

Cytotoxic effects of different self-adhesive resin cements: Cell viability and induction of apoptosis.

PURPOSE: The effects of four different self-adhesive resin cement materials on cell viability and apoptosis after direct and indirect exposure were evaluated using different cell culture techniques. MATERIALS AND METHODS: Self-adhesive cements were applied to NIH/3T3 mouse fibroblasts by the extract test method, cell culture inserts, and dentin barrier test method. After exposure periods of 24 h and 72 h, the cytotoxicity of these self-adhesive materials was evaluated using the MTT assay (viability) and the Annexin-V-FITC/PI staining (apoptosis). RESULTS: The lowest cell viability was found in cells exposed to BeautiCem SA for 24 h in the extract test method. Cell viability was reduced to 70.6% compared to negative controls. After the 72 h exposure period, viability rate of cell cultures exposed to BeautiCem SA decreased more than 2- fold (29.5%) while cells exposed to RelyX U200 showed the highest viability rate of 71.4%. In the dentin barrier test method, BeautiCem SA induced the highest number of cells in apoptosis after a 24 h exposure (4.1%). Panavia SA Cement Plus was the material that caused the lowest number of cells in apoptosis (1.5%). CONCLUSION: The used self-adhesive cements have showed different cytotoxic effects based on the evaluation method. As exposure time increased, the materials showed more cytotoxic and apoptotic effects. BeautiCem SA caused significantly more severe cytotoxic and apoptotic effects than other cements tested. Moreover, cements other than BeautiCem SA have caused necrotic cell death rather than apoptotic cell death.

Effect of Polishing Systems on Fluoride Release and Surface Roughness of Different Restorative Materials / El efecto de los sistemas de pulido en la liberación de flúor y rugosidad de diferentes materiales restauradores

ABSTRACT Secondary caries is an important factor in the replacement of the restorations, and it is thought that fluoride-releasing materials may prevent this problem. Furthermore, the fluoride release of the materials may be increased by polishing process. Available knowledge about the effect of polishing systems (PS) on the fluoride release of materials is limited. Therefore, this study was conducted to evaluate the effect of PS on the fluoride release of fluoride-containing materials. Restorative materials were divided into 6 groups: Fuji IX GP, Fuji II, Dyract XP, Beautifil II, Beautifil-Bulk, and Filtek Ultimate. Each group was also divided into four subgroups: Mylar strip, Sof-Lex Discs, Sof-Lex Diamond, and OneGloss. Fluoride release was determined using a fluoride ion-selective electrode. Surface roughness was evaluated with a profilometer. Two- way repeated measure and one-way ANOVA tests were used for statistical analysis. The initial rapid fluoride release was observed only in Fuji IX. The PS increased the fluoride release of Fuji IX and Fuji II and Dyract XP materials while reducing the fluoride release of resin-based materials. The highest surface roughness values were obtained with OneGloss. Further, a significant relationship between fluoride release and surface roughness was found. The polishing provides an increase in fluoride release, especially in glass-ionomer-based materials. This article revealed that there is a relationship between fluoride release and surface roughness. Proper PS must be chosen according to the material to provide the best clinical benefits in terms of fluoride release and surface roughness.

RESUMEN La caries secundaria es un factor importante para el reemplazo de restauraciones y se considera que los materiales que liberan flúor pueden prevenir este problema. Además, la liberación de fluoruro de estos materiales podría incrementarse mediante el proceso de pulido. El conocimiento disponible sobre el efecto de los sistemas de pulido (SP) en la liberación de fluoruro de los materiales es limitado. Por lo tanto, este estudio se realizó para evaluar el efecto de los SP sobre la liberación de fluoruro de materiales que contienen fluoruro. Los materiales de restauración se dividieron en 6 grupos: Fuji IX GP, Fuji II, Dyract XP, Beautifil II, Beautifil-Bulk y Filtek Ultimate. Cada grupo también se dividió en cuatro subgrupos: Banda Mylar, Discos Sof-Lex, Sof-Lex Diamond y OneGloss. La liberación de fluoruro se determinó usando un electrodo selectivo de iones fluoruro. La rugosidad de la superficie se evaluó con un perfilómetro. Se utilizaron medidas repetidas bidireccionales y pruebas ANOVA de una vía para el análisis estadístico. La liberación inicial rápida de fluoruro se observó solo en Fuji IX. El SP aumentó la liberación de fluoruro de los materiales Fuji IX y Fuji II y Dyract XP al tiempo que redujo la liberación de fluoruro de los materiales a base de resina. Los valores más altos de rugosidad de la superficie se obtuvieron con OneGloss. Además, se encontró una relación significativa entre la liberación de fluoruro y la rugosidad de la superficie. El pulido proporciona un aumento en la liberación de fluoruro, especialmente en materiales a base de ionómero de vidrio. Este artículo reveló que existe una relación entre la liberación de fluoruro y la rugosidad de la superficie. El SP adecuado debe elegirse de acuerdo con el material para proporcionar los mejores beneficios clínicos en términos de liberación de fluoruro y rugosidad de la superficie.

Effect of surface treatments and universal adhesive application on the microshear bond strength of CAD/CAM materials.

PURPOSE: The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols. MATERIALS AND METHODS: Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, µSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests. RESULTS: The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05). CONCLUSION: Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.

Effectiveness of different resin composite materials for repairing noncarious amalgam margin defects.

OBJECTIVES: The specific objective of this in vitro study was to determine whether the current flowable resin composites can establish an effective seal in repairing noncarious amalgam margin defects. MATERIAL AND METHODS: A total of 30 freshly extracted caries-free human third molars were used for this investigation. Class I preparations with a standardized 160-µ marginal defect were made by condensing amalgam against a Mylar strip. Accelerated aging and corrosion protocols were then applied to simulate oral conditions. The prepared teeth were randomly divided into five groups (n = 6 per group) according to the repair material employed as follows: (1) no treatment (control); (2) self-adhering flowable resin composite (Vertise Flow); (3) flowable resin composite (Filtek Ultimate Flowable); (4) sonic-activated resin composite (SonicFill); and (5) self-adhesive cement (SmartCem2). Specimens were thermocycled again and then immersed in 5% methylene blue at 37°C for 24 h. For dye-leakage measurements, specimens were sliced longitudinally using a low-speed diamond disk. RESULTS: The results indicated that the flowable resin composite material significantly reduced marginal microleakage compared to the control and SonicFill (P < 0.05). CONCLUSION: Current flowable resin composites were found to be adequate materials for repairing noncarious amalgam margin defects.