Resin Restorations Research Articles

The Effect Of Er,Cr:YSGG Laser Conditioning on Dentin Bond Strength and Nanoleakage of Universal Adhesive Systems: An In Vitro Study.

To investigate the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser conditioning on dentin bond strength and nanoleakage of different universal and self-etch adhesives. A total of 84 intact human third molar teeth were cut at the dentin level, and half of them were laser conditioned. The specimens were divided into three groups; two different universal resins and one self-etch adhesive resin were applied and composite resin restorations were created. For the microtensile bond strength (µTBS) test, 20 microspecimens were prepared from the laser and control group of each adhesive (n = 20) and tested with a universal device. For nanoleakage observation, 10 specimens were prepared from each group (n = 10) and stored in silver nitrate solution, and then the amount of nanoleakage was analyzed by field emission scanning electron microscopy (FESEM). Data were analyzed with two-way ANOVA, Tukey's honestly significant difference, and chi-square tests. The mean dentin bond strength of all adhesives in the laser groups was found to be statistically significantly lower than those of the control groups (P < .05). No difference was found between the mean bond strength of the adhesives in the laser and control groups (P > .05). Higher nanoleakage was observed in all adhesives in the laser groups compared to the control groups (P < .05). Irradiation of the dentin surface with Er,Cr:YSGG could adversely affect the µTBS and nanoleakage, likely by affecting the structure of the hybrid layer.

A comparative assessment of color stability among various commercial resin composites

ObjectivesThe aim was to evaluate the color stability of six commercial restorative resin composites after being exposed to commonly consumed beverages. Repolishing impact on the stained composite was also assessed.MethodsOne-hundred and fifty disc specimens (8 mm diameter & 3 mm thickness) were prepared from Filtek™ Universal Restorative, SDR flow+, everX Flow, G-ænial A’CHORD, G-ænial Universal Flo and G-ænial Universal Injectable. To assess the color stability in five various beverages, 25 specimens from each material were randomly distributed into five groups (n = 5), according to the utilized staining solution. Group 1: distilled water, Group 2: coffee, Group 3: red wine, Group 4: energy drink, Group 5: coke. The color changes (∆E) for all materials were measured using spectrophotometer at the baseline, after 84 days of staining and after repolishing. Data was collected and analyzed using ANOVA (α = 0.05).ResultsBoth material type and staining solution had a significant effect on the color stability of specimens (p < 0.05). Compared to other beverages, the color value of the specimens submerged in coffee and wine showed the most statistically significant (p < 0.05) mean ∆E. SDR flow + in coffee and wine presented the highest ∆E when compared to other tested materials (p < 0.05). After staining of the composites, repolishing was successful in lowering the ∆E value.ConclusionsAll the beverages had an impact on the color stability of the tested resin composites, with coffee and wine demonstrating the most significant effects. The variations in color stability varied depending on the specific material utilized. Dentists should possess awareness regarding the chemical interactions that occur between different beverages and various types of resin composites. Additionally, repolishing serves as an effective technique for eliminating surface discoloration in composite restorations.

Effect of Aging and Different Surface Treatments on Repair Bond Strength of Hybrid Resin Composites

Background: With the trend for minimally invasive dentistry and the rapid evolution of composite resin materials, repair of defective composite resin restorations is a popular choice rather than replacement of the restoration. The durability of the bond between the old and repaired composite restoration is important for a successful outcome. Objective: To evaluate the immediate and delayed shear bond strength of two types of repaired hybrid resin composites using different chemical and mechanical surface treatments. Methods: Two types of hybrid resin composites, micro-hybrid resin composite and nanohybrid resin composite, were used to prepare 288 pre-polymerized resin composite specimens. After polymerization, repair was done after 24 hours and 6 months. Each hybrid resin composite group was divided into 3 groups according to surface treatment used to repair the substrate: group 1: no surface treatment, group 2: treated by medium abrasive stone, and group 3: treated by fine abrasive stone. Each group was further subdivided into 3 subgroups according to different agents used for repair: group 1: Silane, group 2: Universal adhesive, and group 3: Silane + adhesive. Shear bond strengths of the repaired specimens were measured using a Universal testing machine. Failure modes were evaluated under a stereomicroscope. Results: Different chemical and mechanical surface treatments had a significant effect on the shear bond strength values of all groups (p ≤ 0.05). The highest mean shear bond strength values were found in nano-hybrid composites immediately repaired by silane after treatment by a medium abrasive stone while the lowest mean shear bond strength values were found in micro-hybrid composites with delayed repair and no surface treatment. Conclusion: Diamond burs using silane with adhesive improved the repair bond strength of the tested hybrid composites. In composite repair, using abrasive mechanical pretreatment followed by adhesive conditioning is crucial for the success of the repair restoration.

FATORES QUE INFLUENCIAM NA LONGEVIDADE DE RESINAS COMPOSTAS: revisão narrativa de literatura

Currently, there is an increasing demand for procedures focused on aesthetic rehabilitation and minimally invasive interventions in dental clinical settings. These interventions coexist with restorative procedures, which already hold a notable presence in daily clinical routines. Contrary to the widely held assumption, the success of a restoration is not solely determined by the selection of high-quality resin, but is also contingent upon other criteria of significant relevance. These encompass pre-existing clinical conditions, the operator's skill, the patient's profile, and the materials employed. In this vein, this study aims to present the key factors influencing the longevity of composite resin restorations, as well as to provide guidance to the dentist regarding the importance of correctly adhering to the clinical sequence during the restorative protocol, and ultimately, to elucidate the influence of external factors: the patient's acidic diet, gastric reflux, poor oral hygiene, alcohol consumption, and smoking. To this end, qualitative research was conducted through narrative literature review. Furthermore, regular polishing of the restoration during maintenance visits is essential to preserve its properties and enhance its durability.

Flexural strength and Vickers hardness of milled and 3D-printed resins for provisional dental restorations

Various forms of temporary resins are offered on the market; however, the properties of temporary resins obtained by milling and 3D printing have not been fully examined. This study aimed to compare the flexural strength and Vickers hardness of milled and 3D-printed resins. Methods: Three resins were tested: Evolux PMMA (milled resin), Cosmos Temp (3D-printed resin), and Structur 2 SC (bis-acrylic resin, group control). Specimens were prepared with rectangular shapes (n = 12) for flexural strength measurements and disc shapes (n = 9) for Vickers hardness tests. Flexural strength tests were performed at a crosshead speed of 0.75 mm/min, and the Vickers hardness was measured under a load of 20 N for 10 s. The obtained data were subjected to the Kruskal–Wallis test. Results: A significant difference (p &lt; 0.05) in flexural strength was observed among the three sample groups: Evolux PMMA (111.76 MPa), Structur 2 SC (87.34 MPa), and Cosmos Temp (56.83 MPa). No significant difference (p &lt; 0.05) was observed between the Vickers hardness values of Structur 2 SC (33.37 VHN) and Evolux PMMA (29.11 VHN); however, both materials were statistically superior to Cosmos Temp (10.90 VHN). Conclusion: While the mechanical properties of the milled resin were superior or similar to those of the bisacrylic resin, the 3D-printed resin was statistically inferior to both the milled and bis-acrylic resins.

An in vitro assessment of biaxial flexural strength, degree of monomer conversion, color stability, and ion release in provisional restorations containing Sr-bioactive glass nanoparticles

This study examined the mechanical and chemical properties of an experimental provisional restoration containing Sr-bioactive glass nanoparticles (Sr-BGNPs) compared to commercial provisional materials. The experimental material (TempS10) contained dimethacrylate monomers with added 10 wt% Sr-BGNPs. The degree of monomer conversion (DC) of self-curing (n = 5), biaxial flexural strength (BFS)/modulus (BFM) (n = 5), and color changes (ΔE* 00 ) of materials in red wine (n = 5) were determined. Additionally, ion release (Ca, P, and Sr) in water at 2 weeks was examined (n = 3). The commercial materials tested included polymethyl methacrylate-based provisional material (Unifast) and bis-acrylic materials (Protemp4 and Cooltemp). TempS10 exhibited a comparable degree of monomer conversion (49%) to that of Protemp4 (60%) and Cooltemp (54%) (p > 0.05). The DC of Unifast (81%) was significantly higher than that of other materials (p < 0.05). TempS10 showed a BFS (126 MPa) similar to Cooltemp (102 MPa) and Unifast (123 MPa), but lower than Protemp4 (194 MPa). The immersion time for 2 weeks exhibited no detrimental effect on the strength and modulus of all materials. The highest ΔE* 00 at 24 h and 2 weeks was observed with TempS10, followed by Cooltemp, Unifast, and Protemp4. Only TempS10 showed a detectable amount of Ca (0.69 ppm), P (0.12 ppm), and Sr (3.01 ppm). The experimental provisional resin restoration containing Sr-BGNPs demonstrated polymerization and strength comparable to those of bis-acryl provisional restorations but with the added benefit of ion-releasing properties. However, the experimental material demonstrated unsatisfactory color stability.

RECREATING MORPHOLOGY FOR IMPROVED CLASS IV RESTORATIONS

The fractured incisor is a common occurrence in general dental practice. Achieving a positive aesthetic outcome and maximising bond strength is central to patient satisfaction and ensuring restoration longevity. Correct shade selection and the reproduction of natural anatomy in composite resin can be challenging in the anterior labial segments where the human eye’s ability to detect asymmetry plays an important role. An understanding of tooth morphology and how to replicate it will aid in this procedure. This article aims to describe a step-by-step approach towards successful morphological replication in Class IV composite resin restorations. Composite shade selection, placement techniques and polishing methods will be covered.

Making graphene oxide (GO)-cladded SiO2 spheres (SiO2 @GO) as inorganic fillers for dental restorative resin composites

ObjectiveGraphene oxide (GO) is of great interest in dentistry as the functional filler, mainly owing to its ability to inhibit the formation of cariogenic bacteria and possess low cytotoxicity to different cells, such as human dental pulp cells, HeLa cells, etc. However, its typical brown color limits the practical application. MethodsHere, the refractive-index-matched monodisperse SiO2 were used as the supporting substrates to synthesize GO-cladded SiO2 spheres (xSiO2 @ yGO) through a mild electrostatic self-assembly process, where x and y represent the amount of SiO2 and GO in the reaction mixture, respectively. The morphology and the optical performance of the obtained xSiO2 @ yGO particles were modulated by varying the mass ratio of SiO2 and GO (5:1, 10:1, 50:1, and 100:1). All developed hybrid particles were silanized and formulated with dimethacrylate-based resins. These were tested for curing depth, polymerization conversion, mechanical performance, in vitro cell viability, and antibacterial activity. ResultsOf all xSiO2 @ yGO materials, increasing the mass ratio to 100:1 made the 100SiO2 @GO particles appear light brown and possess the lowest light absorbance from 300 to 800 nm. The results of CIEL*a*b* system showed that all these hybrid particles exhibited obvious discoloration compared with SiO2 and GO, where 100SiO2 @GO possessed the smallest color difference. Furthermore, following the results of curing depth, polymerization conversion, and mechanical performance of dental composites, the optimal filler composition was 100SiO2 @GO at 5 wt% filler loading. The resultant 100SiO2 @GO-filled composite produced the highest flexural strength (115 ± 12 MPa) and the lowest bacterial concentration (6.7 × 108 CFU/mL) than those of the resin matrix (78 ± 11 MPa; 9.2 × 108 CFU/mL) and 5 wt% SiO2-filled composite (106 ± 9 MPa; 9.1 × 108 CFU/mL), respectively, without affecting in vitro cell viability. SignificanceThe facile and mild synthesis of xSiO2 @ yGO hybrid particles provided a convenient way to tune their optical property. The optimal 100SiO2 @GO particles could be considered as the promising antibacterial filler to be applied in dental care and therapy.

Effect of Chlorhexidine and Ozone Gel on Microleakage and Shear Bond Strength of Dentin Bonding Agents in Composite Resin Restorations of Primary Teeth

Aim: This study aimed to investigate the effects of two antimicrobial agents on shear bond strength and microleakage of composite resin restorations in primary teeth. Methods: Sixty extracted primary molars and canines were assigned to three different groups according to the dentin surface pretreatment (2% chlorhexidine gluconate gel, ozone gel, and control group) and two subgroups (sound and caries-affected dentin) for shear bond strength tests. For the microleakage test process, a class V cavity was prepared on the buccal surface of the teeth and restored with composite resin. Then, all the teeth were cut buccolingually. The depth of stain penetration in each specimen was measured separately according to the scale. The data have been analyzed using SPSS 24 software. Results: In both sound and caries-affected dentin, ozone gel exhibited higher shear bond strength than chlorhexidine gel and the control group (P&lt;0.001). Chlorhexidine gel had no significant effect on the shear bond strength of sound dentin (P=0.561), but it reduced it in the caries-affected dentin (P&lt;0.001). With both disinfectants, the shear bond strength of the caries-affected dentin was significantly lower than that of the sound dentin. The application of chlorhexidine gel to caries-affected dentin resulted in more microleakage than sound dentin. In addition, the amount of microleakage in the ozone gel group was similar in both types of dentin. Conclusion: In both sound and caries-affected dentin, ozone gel was associated with higher shear bond strength than chlorhexidine gel; furthermore, chlorhexidine increased microleakage and ozone gel decreased it.

The cross-linking and protective effect of artemisinin and its derivatives on collagen fibers of demineralized dentin surface

ObjectiveTo investigate the cross-linking and protective effect of artemisinin (ART), dihydroartemisinin (DHA), and artesunate (AST) on collagen fibers of demineralized dentin surface. MethodsMolecular docking was used to predict potential interactions of ART, DHA, and AST with dentin type I collagen. Human third molars without caries were completely demineralized and treated with different solutions for 1 min. The molecular interactions and cross-linking degree of ART and its derivatives with dentin collagen were evaluated by FTIR spectroscopy, total extractable protein content, and a ninhydrin assay. Scanning electron microscopy, hydroxyproline release, and ultimate microtensile strength tests (μUTS) were employed to confirm the mechanical properties and anti-collagenase degradation properties of dentin collagen fibers. ResultsART, DHA, and AST combined with dentin type I collagen mainly through hydrogen bonding and hydrophobic interactions, and the cross-linking reaction sites were mainly C=O and CN functional groups. Compared to the control group, ART and its derivatives significantly increased the degree of cross-linking. Additionally, significant increases were observed in resistance to enzymatic digestion and mechanical properties of the artemisinin and its derivatives group. ConclusionART, DHA, and AST could cross-link with demineralized dentin collagen, through improving the mechanical properties and anti-collagenase degradation properties. Clinical significanceThe study endorses the potential use of ART and its derivatives as a prospective collagen cross-linking agent for degradation-resistant and long-period dentin bonding in composite resin restorations.

Optical behavior of 3D-printed dental restorative resins: Influence of thickness and printing angle.

To evaluate the influence of thickness and printing angle on the optical properties of 3D-printed dental restorative resins. Four 3D printing resin systems were evaluated: DFT-Detax Freeprint Temp; FP- Formlabs Permanent Crown; FP- Formlabs Temporary CB; and GCT- GC Temporary-. Samples from each material were printed at 0° and 90°, and polished up to 0.5, 1.0, 1.5 and 2.0mm thickness. Scattering (S), absorption (K) and albedo (a) coefficients, transmittance (T%), light reflectivity (RI) and infinite optical thickness (X∞) were calculated using Kubelka-Munk's model. Data were statistically analyzed using Kruskal-Wallis¸ Mann-Whitney tests, and VAF coefficient. The spectral distribution on S, K, T%, RI,X∞ were wavelength dependent. Although the spectral behaviors were similar for all the specimens evaluated, the values of S, K, T% andX∞ presented significant differences between specimen thicknesses for all the materials used and for both printing orientations. Values for S and K increased, and T% and X∞ decreased. Significant differences between 0° and 90° were found for RI values at 0.5 and 1.0 mm thick samples, for S and K at 2.0 mm, for X∞ at 0.5 and 1.0 mm for DFT, and at 0.5 mm for FT. Optical properties of 3D-printed restorative resins vary between thicknesses, and could be affected by the building orientation. Therefore, these factors should be considered in order to improve the biomimetic potential of 3D-printed dental restorative resins. Understanding the optical behavior of the 3D-printed restorative resins is essential to optimize their clinical performance.

Evaluation of antioxidant application on bond strength of composite resins to bleached enamel

Abstract Aim: This study aims to assess and evaluate the application of 10% sodium ascorbate, 5% green tea extract, 5% pomegranate peel extract, and 5% grape seed extract on shear bond strength of composite to bleached enamel. Materials and Methods: Sixty extracted human maxillary central incisors were randomly divided into seven groups. The enamel surface of these specimens was bleached with hydrogen peroxide (35%), except group VII (control group). Postbleaching, the specimens of group II were placed in artificial saliva for 2 weeks before restoration and the specimens of groups III and IV and groups V and VI underwent antioxidant application; 10% sodium ascorbate, 5% green tea extract, 5% pomegranate peel extract, 5% grape seed extract, respectively, for 10 min, followed by composite resin restoration, respectively. The specimens of group I were restored with composite resin immediately after bleaching. The specimens’ shear bond strength was tested using universal testing equipment. The data obtained were statistically analyzed using a one-way analysis of variance and the Tukey post hoc test. Results: There was no statistically significant difference in the effects of various antioxidants on the shear bond strength of bleached enamel. Conclusion: Within the constraints of the study, it was concluded that the application of antioxidants efficiently recovered the bond strength of bleached enamel. The application of 5% grape seed extract treatment demonstrated better bond strength among the antioxidants tested. Clinical Significance: Antioxidants can be used immediately following bleaching to restore resin composite bond strength without the requirement of delay in the treatment to reduce the nascent oxygen species in bleached teeth.

Effect of Er,Cr:YSGG and Nd:YAG Lasers on Microleakage of Composite Resin Restorations Using Universal Adhesives

Background: Clinical long-term success of bonded restorations is depended to reduce marginal microleakage and the laser application with combination of new bonding systems may play positive role. The aim of this study was comparative evaluation of Er,Cr:YSGG and Nd:YAG lasers effect on microleakage of class V composite resin restorations using several universal adhesives. Methods: In this in vitro study, standard class V cavities were prepared on both lingual and buccal surfaces of 72 intact premolar teeth. For evaluation of microleakage, the cavities were divided into 9 groups according to conditioning method (n=15): G1: G-Premio Bond [GP]; G2: Scotchbond Universal Adhesive [SU]; G3: All-Bond Universal [AB]; G4: GP+Nd:YAG Laser; G5: SU+Nd:YAG Laser; G6: AB+Nd:YAG Laser; G7: GP+Er,Cr:YSGG Laser; G8: SU+Er,Cr:YSGG Laser; and G9: AB+Er,Cr:YSGG Laser. The cavities were filled with composite resin and then subjected to thermocycling, placed in methylene blue solutions, embedded in resin blocks and vertically cut in the bucco­lingual direction. The microleakage in occlusal and gingival margins was defined as linear penetration of methylene blue and determined with a stereomicroscope to assign microleakage scores using a four­point scale. Data were analyzed by using SPSS software and Kruskal-wallis and Mann-Whitney U tests. Results: Microleakage scores had statistically significant different before and after laser irradiation in dependent to the adhesive used (P&lt;0.05) but there were no significant different between Nd:YAG and ER,Cr:YSGG laser, also between different universal adhesives (GP, SU, AB). The results showed that total microleakage scores of occlusal margins had significant statistical different in comparison with gingival margins (P&lt;0.001). Conclusion: The results indicate that Nd:YAG and Er,Cr:YSGG lasers irradiation, after using the investigated universal adhesives, had a positive effect on reducing the microleakage of composite Class V restorations. The microleakage rate was shown to be independent of adhesives and lasers type used in this study.

Mechanical properties of 3D-printed and milled composite resins for definitive restorations: An in vitro comparison of initial strength and fatigue behavior.

To evaluate the flexural strength and fatigue behavior of a novel 3D-printed composite resin for definitive restorations. Fifty disc-shaped specimens were manufactured from each of a nanohybrid composite resin (NHC), polymer-infiltrated ceramic network (PICN), and 3D-printed composite resin (3D) with CAD-CAM technology. Biaxial flexural strength (σin ) (n = 30 per group) and biaxial flexural fatigue strength (σff ) (n = 20 per group) were measured using piston-on-three-balls method, employing a staircase approach of 105 cycles. Weibull statistics, relative-strength degradation calculations, and fractography were performed. The results were analyzed with 1-way ANOVA and Games-Howell post hoc test (α = 0.05). Significant differences in σin and σff among the groups (p < 0.001) were detected. The NHC group provided the highest mean ± standard deviation σin and σff (237.3 ± 31.6 MPa and 141.3 ± 3.8 MPa), followed by the PICN (140.3 ± 12.9 MPa and 73.5 ± 9.9 MPa) and the 3D (83.6 ± 18.5 MPa and 37.4 ± 23.8 MPa) groups. The 3D group exhibited significantly lower Weibull modulus (m = 4.7) and up to 15% higher relative strength degradation with areas of nonhomogeneous microstructure as possible fracture origins. The 3D-printed composite resin exhibited the lowest mechanical properties, where areas of nonhomogeneous microstructure developed during the mixing procedure served as potential fracture origins. The clinical indications of the investigated novel 3D-printed composite resin should be limited to long-term provisional restorations. A cautious procedure for mixing the components is crucial before the 3D-printing process, since nonhomogeneous areas developed during the mixing could act as fracture origins.

A Case Report of Different Management Protocols for Uncomplicated Crown Fracture in Young Permanent Teeth; Fragment Reattachment vs. Resin Restoration

Introduction: An uncomplicated crown fracture (enamel-dentin fracture) is the most clinically reported traumatic injury. Many techniques have been reviewed to manage this traumatic injury. The literature has no consensus on the best strategy to establish optimal biological, functional, and esthetical success. Objective: This clinical case reports different management of uncomplicated crown fractures in young permanent teeth that were successfully treated using both tooth fragment reattachment and composite build-up. Case Report: A 9-year-old female presented as an emergency patient with immature fractured upper central incisors. She hit her mouth into a solid wall and broke her front teeth during playing. Upon parental advice, the fragments were stored in a container of milk since the incident. For dental management, two treatment approaches were used. Conclusion: After a two-year follow-up, the treatment is considered successful and the traumatized teeth are vital, functional and presented with a complete root development.

Effect of Coffee and Polishing Systems on the Color Change of a Conventional Resin Composite Repaired by Universal Resin Composites: An In Vitro Study.

The purpose of this study was to evaluate the color stability of repaired aesthetic restorative resin matrix materials after immersion in coffee and the effect of polishing systems after staining. One hundred and eighty cylindrical discs (8 mm × 2 mm) were prepared using a conventional nano-fill resin composite (Clearfil Majesty Esthetic A2 shade) with round cavities (3 × 1 mm). Cavities were repaired by three resin composite materials: Clearfil Majesty Esthetic A2 shade, one-shaded nano-fill resin composite (Omnichroma) and group-shaded nano-hybrid resin composite (Optishade, medium shade). Each group was polished with three polishing systems (n = 20); aluminum oxide (Soflex Spiral Wheels, 3M ESPE), silicon carbide (Occlubrush, Kerr, CA, USA) and diamond particulate (Twist Dia Spiral Wheels, Kuraray, Okayama, Japan). Color change (ΔE00) measurements were performed with a spectrophotometer at the baseline. Half of the polished samples were either kept in distilled water or immersed in coffee for 15 days, and color measurements were repeated before and after polishing. Statistical analysis was performed using the Kruskal-Wallis test. Repaired samples showed different color correspondence values in all groups. All three restorative materials showed significant color changes (ΔE00) after immersion in coffee (p ≤ 0.05). Repolishing of stained samples showed color improvement values in all groups. The content of the polishing system played an important role in removing the stains.

Performance of direct and indirect onlay restorations for structurally compromised teeth

Research is lacking on the restoration of structurally compromised posterior teeth using direct composite resin or indirect restorations. The purpose of this in vitro study was to measure the fracture resistance and microleakage of different onlay restorations fabricated by using conventional and digital computer-aided design and computer-aided manufacturing (CAD-CAM) to restore structurally compromised teeth. Mandibular molars (n=54) were prepared for onlay restorations. Teeth were allocated to 3 groups (n=18) according to the type of restoration materials, nanohybrid composite resin (Grandio blocs), resin hybrid ceramic (SHOFU Block HC), and fiber-reinforced composite resin (everX Posterior). Onlays were bonded using a dual-polymerized adhesive resin cement. All specimens were thermocycled, followed by cyclic loading. Based on the type of investigation conducted, fracture resistance, and microleakage test, each group was then divided into 2 equal subgroups (n=9). The collected data were statistically analyzed with the chi-square of the Fischer exact test (α=.05). Fracture resistance testing revealed a statistically significant difference between groups (P<.001). The fiber-reinforced composite resin demonstrated the highest fracture resistance, with statistically significantly less microleakage compared with the other groups (P=.013). Direct fiber-reinforced composite resin could be considered a suitable alternative to CAD-CAM composite resin for the restoration of structurally compromised teeth.

REMOVAL SURGICAL OF MESIODENS IN THE PALATE FOR OCCLUSAL REESTABLISHMENT: A CASE REPORT

The purpose of this work is to report on the reestablishment of the patient's occlusion through the surgical removal of mesiodens in the palate. A 15-year-old male patient sought care at the dental clinic at Nilton Lins University accompanied by his guardian, carrying a panoramic radiograph and presenting aesthetic discomfort due to fracture of tooth 21 as the main complaint, the clinical evaluation verified the presence of a structure similar to a supernumerary tooth, this structure prevented a satisfactory occlusion of the patient, destabilizing the lower arch and acting on the intrusion effect of the lower incisors of the third quadrant. Based on the clinical characteristics presented along with the imaging exam, the person responsible for the removal of the mesiodens for occlusal reestablishment and subsequent fabrication of composite resin restoration with return of the disocclusion guide was chosen. The mesiodens was extracted and the occlusal normality was reestablished. Therefore, in view of the clinical resolution presented, the treatment was satisfactory, allowing the advancement to the restorative stages, and returning a normal pattern of the patient's occlusal profile.

Long term clinical performance of 'open sandwich' and 'total-etch' Class II composite resin restorations showing proximal deterioration of glass-ionomer cement.

To compare clinical performance of resin composite posterior Class-II restorations placed with etch-and-rinse adhesive or open sandwich technique using glass-ionomer cement. Data on Class II restorations placed by one dentist between 1990 and 2016 were collected from patient files, including caries risk, tooth related variables, applied materials and dates of last check-up visit and restoration placement. Open sandwich restorations were placed before 2001, while after 2001, a total-etch technique using etch-and-rinse 3-step adhesive was used when placing a Class II composite restoration. For statistical analysis, Kaplan-Meier statistics and a multilevel Cox-Regression was conducted (p<0.05). Annual Failures Rates (AFR) were calculated. 675 Class II restorations were placed in 91 patients, 491 total-etch restorations (observation time 2-18y), and 184 open sandwich restorations (observation time 19-29y) showing AFRs at 15 years as 2.9% for total-etch and 9.7% for open sandwich restorations. Secondary caries as failure was equally distributed among the 2 groups and 27% of the failures in the open sandwich group were due to proximal deterioration of glass-ionomer cement. The Cox-regression showed a significant higher risk for failure for the open sandwich technique compared to total-etch class-II composite restorations (HR=2.9; p<0.001). Application of glass-ionomer cement using the open sandwich technique cannot be recommended for class-II restorations as being more complex and showing poorer clinical performance.

Comparison of the Surface Properties of 3D-printed Permanent Restorative Resins and Resin-based CAD/CAM Blocks.

This study aimed to investigate the surface roughness, microhardness, and color changes of resin-based computer-aided design/computer-aided manufacturing (CAD/CAM) blocks and 3D-printed permanent resins in different beverages. Resin-based CAD/CAM blocks (Cerasmart 270 and Grandio Blocs) and 3D-printed permanent restorative resins (Crowntec and Permanent Crown) were used in this study. A total of 96 specimens were prepared from CAD/CAM blocks and 3D-printed permanent resins. The initial surface roughness, microhardness, and shade value of the specimens were measured. Then, the specimens prepared from each material were divided into three subgroups (n=8) and immersed in tea, coffee, and distilled water for 30 days. After the specimens were immersed in the beverages, the surface roughness, microhardness, and tone values were measured again. The data were statistically analyzed using a two-way analysis of variance test (p<0.05). No statistically significant difference was found in the surface roughness values of the resin-based CAD/CAM blocks and 3D-printed resins (p<0.05). Resin-based CAD/CAM blocks showed statistically significantly higher microhardness than 3D-printed permanent resins (p<0.05). Although the color changes in 3D-printed resins in tea and coffee were similar to those in resin-based CAD/CAM blocks on the first and seventh days, more color changes appeared in the 3D-printed resins after 30 days. The surface roughness and microhardness values of the specimens submerged in tea, coffee, and distilled water showed no statistically significant changes (p<0.05). Although the surface roughness of 3D-printed permanent resins was similar to that of resin-based CAD/CAM blocks, they had a lower microhardness value. Moreover, 3D-printed permanent resins showed more color changes in tea and coffee.