Resin-based Composite Restorations Research Articles

Influence of light exposure techniques on in vitro pulp temperature rise during bulk fill composite Class I restorations.

This in vitro study assessed peak temperature and temperature increase (ΔT) within the pulp chamber during different extended photoactivation techniques (EPT-applying similar radiant exposure values) to resin-based composites (RBCs) placed in a Class I cavity preparation in an extracted human lower third molar. A T-type thermocouple was placed in the pulp chamber and connected to a temperature analysis device (Thermes, Physitemp). The tooth was attached to an assembly simulating the in vivo environment (controlled baseline pulp chamber temperature and fluid flow). The real-time pulp chamber temperature was evaluated throughout the photoactivation (Bluephase N, Ivoclar Vivadent) of two bulk-fill RBCs: Tetric N Ceram Bulk Fill (TBF; shade: IVA; Ivoclar Vivadent); Surefill SDR flow + (SDR, shade: Universal; Dentsply Sirona), which were exposed to different curing techniques: 40s-occlusal surface; 20s-occlusal + 10s-buccal + 10s-lingual surfaces; 10s-buccal + 10s + lingual + 20s-occlusal surfaces. Each EPT delivered 42.4J/cm2. Vickers hardness (VHN) was measured on the removed, sectioned RBC restorations at the top and bottom middle areas after curing. ΔT and VHN data were analyzed using 2-way ANOVA followed by Bonferroni post-hoc test (α = 0.05). Peak temperature data were analyzed using one-way ANOVA and Dunnett's post-hoc test (α = 0.05). SDR showed higher ΔT values than TBF (p = 0.008) in some EPTs. Neither technique resulted in ΔT values greater than 5.5 °C. Both composites had acceptable bottom/top hardness ratios (greater than 80%), regardless of the photoactivation technique. The evaluated EPTs may be considered safe as a low-temperature increase was noticed within the pulp chamber.

Comparison between Different Bulk-Fill and Incremental Composite Materials Used for Class II Restorations in Primary and Permanent Teeth: In Vitro Assessments.

Several advantages, including improved aesthetics and conservative cavity preparation, made resin-based composite (RBC) a popular restorative material. However, several limitations come with RBC restorations such as the necessity for proper isolation of the tooth and an incremental layering for the material due to the limitations of the depth of cure. Despite these advantages and limitations, the usage of these restorative materials is increasingly being expanded due to the advancement made since their introduction. To overcome some of the limitations, several types of RBC restorations were developed. Four different RBC materials used for class II restorations in primary and permanent teeth were compared: Z350 XT Filtek™ Universal Restorative (ZXT), Filtek™ Bulk Fill Flowable Restorative (FBF), Beautifil-Bulk Flowable (BBF) and Tetric™ N-Flow (TNF). Flexure strength, elastic modulus, surface roughness, microhardness and microleakage were assessed using standard methods or previously published protocols. The data and differences between the groups were analyzed using One-way analysis of variance (ANOVA), Tukey's multiple comparisons, Kruskal-Wallis and Wilcoxon rank-sum (Mann-Whitney) tests. The study found that BBF (86.24 ± 7.41 MPa) and ZXT (64.45 ± 11.52 MPa) had higher flexural strength than FBF (50.89 ± 8.44 MPa) and TNF (50.67 ± 9.40 MPa), while both exhibited the highest values of surface roughness. Elastic modulus was the highest with BBF, which was not statistically significant from FBF or ZXT (p > 0.05). ZXT (109.7 ± 7.83 VH) exhibited the highest value of microhardness, which was statistically significant from the other three materials (p < 0.0001). Microleakage was assessed after thermocycling for 20,000 cycles to simulate two years in the mouth. FBF (70%) exhibited the most resistance to microleakage. Different types of RBC restorations exhibit different characteristics. The clinician needs to choose the most appropriate restorative material based on different clinical scenarios.

Clinical evaluation of lithium disilicate versus indirect resin composite partial posterior restorations – A 7.8-year retrospective study

ObjectiveTo evaluate retrospectively the longevity of lithium disilicate ceramic (LidiSi) vs. laboratory-processed resin-based composite (RBC) inlay/onlay/overlay restorations and risk factors associated with restoration deficiencies and failures. MethodsPatients (n = 91) receiving LidiSi (73.1%) and RBC (36.9%) inlays/onlays/overlays between 2007 and 2017 were selected. The restorations were evaluated using the modified U.S. Public Health Service criteria. The survival of the restorations was analyzed using the Kaplan-Meier method and log rank test. Factors affecting the occurrence of deficiencies were examined by logistic regression analysis. This was performed with the use of the Generalized Estimating Equation model including Repeated measurements (GEER), with the consideration that the same patient had several teeth in the sample. Risk estimation was conducted for each evaluated criterion (p < 0.05). ResultsThe survival of LidiSi and RBC restorations were 96.8% and 84.9%, respectively after a mean observation period of 7.8 ± 3.3 years. The annual failure rate was 0.2% for LidiSi and 1.0% for RBC. The probability of survival was above 98% for both restorations in the first 6 years, however, it dropped to 60% for RBC by the end of the 15th year. For both materials the reasons for failure included secondary caries, restoration fracture, and endodontic complication. In addition, LidiSi also failed due to tooth fracture, while RBC due to marginal gap formation and loss of retention. Among the evaluated risk factors, material of restoration (OR=6.8, CI95%:3.1–14.9), oral hygiene (OR=8.0, CI95%: 2.9–22.1], and bruxism (OR=1.9, CI95%: 1.1–3.3) showed a significant impact on the evaluated criteria. SignificanceLidiSi and RBC restorations showed similarly excellent 6-year survival, however, in the long term significantly more failures should be expected for RBCs.

Effects of silane coupling treatment on the clinical performance of direct repaired resin-based composite (RBC) restorations with or without prior surface sandblasting: A randomized controlled trial

ObjectiveTo evaluate the effects, of using silane coupling agent within the procedures of repairing old composite restorations with or without sandblasting their surfaces, on the clinical performance of repaired composite restorations. MethodsThe study involved repairing 130 Class I and II defective composite restorations. After recurrent caries removal, the repair process included etching with 37 % phosphoric acid, Adper Single Bond 2 application for bonding and Filtek Z250 composite for restoring all defects.The restoration surfaces were subjected to one of the following additional surface treatments within the repair process: Control: No additional treatment; the Silane-Adhesive treatment: A separate step involved the application of a silane coupling agent after acid etching; and the Sandblast-Silane-Adhesive treatment: included intra-oral sandblasting of old composite surfaces followed by silane application. Two calibrated examiners evaluated all repaired restorations according to a modified USPHS criteria after 6 months.Comparisons of the clinical performance between the treatment groups were made using Chi-square test, while responses to cold tests before and after repair treatment were made using Wilcoxon's Signed Rank's (α = 0.05). ResultsOf 130 cases, only 116 cases turned up for evaluation. The primary reasons for composite repair were recurrent caries and anatomical deficiencies. No statistically significant differences were found between the groups for all clinical criteria (p > 0.05). The control group experienced one total and two partial retention losses. ConclusionsThe application of a silane coupling agent, with or without intra-oral sandblasting, demonstrated no improvement on the clinical performance of repaired posterior composites after 6-months. Clinical significanceSurface treatment of defective composite restorations using silane with intra-oral sandblasting within their repair process offered marginal improvement in their clinical performance over conventional etching technique, but insignificantly so. Repair reduced exaggerated cold test responses and eliminated POS within 6-months. Repair reduces cold sensitivity and promotes restoration longevity.This clinical trial was registered at ClinicalTrials.gov with the registration number NCT06005571.

Development of a new universal adhesive containing CPNE7-derived peptide and its potential role in reducing postoperative sensitivity.

Post-operative sensitivity (POS) is the most common clinical dental complaint after tooth preparation and resin-based composite restoration. In our previous study, copine 7 (CPNE7) and CPNE7-derived peptide (CPNE7-DP) induced in vitro odontoblast differentiation and in vivo dentin formation. Here, we incorporated CPNE7-DP into All-Bond Universal (ABU) adhesive, developing ABU/CPNE7-DP. This study aimed to investigate the possibility of reducing POS using ABU/CPNE7-DP. We first determined the stability of CPNE7-DP under low pH. Furthermore, we evaluated its dentinal tubule penetration, in vitro odontogenic differentiation potential, in vivo tertiary dentin formation and its effects on bonding performance. CPNE7-DP was stable at pH 1.2, even lower than ABU's pH of 3.2. ABU/CPNE7-DP can penetrate dentinal tubules, stimulate odontoblast differentiation in vitro and generate tertiary dentin with tubular structure in vivo without interfering with bonding performance. Therefore, ABU/CPNE7-DP may serve as a novel bioactive adhesive for reducing POS.

Comparative Evaluation of the Repair Bond Strength of Dental Resin Composite after Sodium Bicarbonate or Aluminum Oxide Air-Abrasion.

The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the repair bond strength. The purpose of this study was to compare the effect of sodium bicarbonate (SB) and aluminum oxide (AO) surface treatments on the microtensile bond strength (µTBS) of repaired, aged RBC. Bar specimens were prepared from microhybrid RBC and aged in deionized water for 8 weeks. Different surface treatments (AO air-abrasion; SB air-polishing), as well as cleaning (phosphoric acid, PA; ethylene-diamine-tetraacetic-acid, EDTA) and adhesive applications (single bottle etch-and-rinse, ER; universal adhesive, UA), were used prior to the application of the repair RBC. Not aged and aged but not surface treated RBCs were used as positive and negative controls, respectively. The repaired blocks were cut into sticks using a precision grinding machine. The specimens were tested for tensile fracture and the µTBS values were calculated. Surface characteristics were assessed using scanning electron microscopy. AO-PA-UA (62.6 MPa) showed a 20% increase in µTBS compared to the NC (50.2 MPa), which proved to be the most significant. This was followed by SB-EDTA-UA (58.9 MPa) with an increase of 15%. In addition to AO-PA-UA, SB-EDTA-UA could also be a viable alternative in the RBC repair protocol.

Impact of Irradiation on the Adhesive Performance of Resin-Based Dental Biomaterials: A Systematic Review of Laboratory Studies

Head and neck cancers are a significant global health burden, with radiation therapy being a frequently utilized treatment. The aim of this systematic review was to provide a critical appraisal of laboratory studies that assessed the effect of irradiation on the adhesive performance of resin-based biomaterials. The analysis included 23 laboratory studies obtained from five databases, with most studies using human enamel, dentin, or both, and bonding procedures involving the fabrication of direct restorations, standardized specimens, bonding of orthodontic brackets, and luting of endodontic fiber posts. The protocols used for irradiation varied, with most studies exposing specimens made from extracted teeth to irradiation using cabinet irradiators to simulate treatment of head and neck cancer. The findings indicate that irradiation reduces the bond strength of dental adhesives and resin-based composites on flat, ground enamel and dentin specimens, with different adhesives and timing of irradiation having a significant impact on adhesive performance. Irradiation also increased microleakage in most studies. The effect of irradiation on marginal adaptation of direct resin-based composite restorations was inconclusive. This systematic review indicates that irradiation has detrimental effects on the adhesive performance of resin-based biomaterials and highlights the need for further clinical and laboratory studies evaluating the performance of adhesive materials and approaches to improve it.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study

ObjectivesTo assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays.Materials and methodsPermanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05).ResultsSimulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052).ConclusionsArtificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays.Clinical relevanceThis laboratory study suggests that—in select cases—intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.

Teaching of composite restoration repair in Brazilian dental schools

ObjectivesThe aim was to investigate aspects of the teaching of restoration repair as a minimally invasive alternative to replacing defective direct composite restorations in undergraduate curricula teaching programs in Brazilian dental schools. MethodsA 14-item validated survey questionnaire was mailed to directors/coordinators of operative/restorative dentistry teachers of Brazilian Dental Schools. Data were collected on demographic characteristics of the teachers and institutions, together with questions on the teaching of the repair of defective resin-based composite restorations as part of the school curriculum; the rationale behind the teaching; the nature of the teaching (preclinical and/or clinical); how techniques were taught, indications for repair, operative techniques, materials used, patient acceptability and expected longevity of completed repairs. ResultsTwo hundred and twenty-two (94%) directors/ coordinators of dental curricula in Brazil were contacted. One hundred and thirty-one directors/coordinators (59%) replied, providing the e-mail address from the teacher responsible for the operative/restorative dentistry program in their school. Of these, 104 responded to the questionnaire (79% response rate). Ninety-three (89%) of the participating schools reported teaching composite repairs as an alternative to replacing restorations. Of the theoretical content, 43% was taught at preclinical and clinical levels, whereas most practical experience (53%) was acquired at clinical levels. Eighty-eight schools (95%) reported tooth substance preservation being the main reason for teaching repair techniques. All schools that taught repairs reported high patient acceptability. ConclusionsThe teaching of composite restoration repair as an alternative to restoration replacement is established in undergraduate programs in most of the Brazilian dental schools surveyed. Clinical significanceThe reasons for teaching restoration repair in Brazil were found to be quite unanimous among teachers, especially regarding the preservation of tooth structure. Variations were found in the clinical indications for repair, suggesting the need for further investigations. Monitoring repaired restorations should be encouraged and could contribute to future studies.

Influence of dental prophylaxis procedures on the tooth veneer interface in resin-based composite and polymer-infiltrated ceramic veneer restorations: an in vitro study

ObjectivesThe aim of this study was to investigate the influence of dental prophylaxis cleaning procedures and artificial aging on veneers in human teeth. The external marginal and internal tooth veneer as well as the restoration surfaces were examined.Material and methodsThirty-two extracted premolars were restored with resin-based composite (RBC) and polymer-infiltrated ceramic network (PICN) veneers. Artificial aging by alternating thermocycling and subsequent prophylaxis procedure (glycine-based powder air polishing or ultrasonic scaling) was conducted for five consecutive cycles. The external marginal interface was examined by height profile measurements and the internal interface was investigated using micro X-ray computed tomography. In addition, the surface texture of the veneer surface was analyzed using confocal laser scanning microscopy.ResultsThe application of both prophylaxis procedures resulted in a deepening of the marginal interface (10 µm ± 8 µm) for materials. Furthermore, the internal interface of PICN restorations showed marginal gaps after both treatments and artificial aging (16 µm ± 3 µm). In contrast to the RBC specimens, a significant increase in surface roughness was identified for PICN veneers after ultrasonic scaling.ConclusionsThe marginal and internal interface regions in veneers fabricated from PICN and RBC were affected by prophylaxis procedures. Furthermore, it may result in increased veneer surface roughness, especially in PICN and after ultrasonic scaling, which might affect bioadhesion and longevity.Clinical relevanceAfter dental prophylaxis procedures, examination of the marginal and the internal interface as well as the veneer surface provides a precise insight into damage mechanisms and offers an assessment of longevity.

Gut microbiota may mediate the impact of chronic apical periodontitis on atherosclerosis in apolipoprotein E-deficient mice.

There are growing evidences linking chronic apical periodontitis (CAP) to atherosclerosis. Gut microbiota is found to be involved in the development of atherosclerosis. Recent studies have shown that CAP could change the diversity and composition of the gut microbiota. It was therefore, we hypothesized that gut microbiota and its metabolites could mediate the impact of CAP on atherosclerosis. Twenty-four 5-week-old lipoprotein E knockout (apoE-/- ) mice were randomly divided into four groups: the CAP group, Con group, Co-CAP (cohoused with CAP) and Co-Con (cohoused with Con) group. In the CAP group, sterile cotton wool containing P.gingivalis was placed into the exposed pulp chamber, followed by coronal resin-based composite restoration of the bilateral maxillary first and second molars. In the Con group, a sham operation was performed. Biweekly, mice in the CAP group were anaesthetised to check the sealing of coronal access. Meanwhile, the animals in the Con group were anaesthetised. The cohousing approach was used to introduce gut microbiota from the CAP and Con groups into the Co-CAP and Co-Con groups, respectively. Alterations in the abundance and diversity of the gut microbiota were detected using 16S rRNA sequencing, Oil-red O staining was used to demonstrate the extent of lesions, and serum levels of trimethylamine N-oxide (TMAO), and immunohistochemistry of flavin-containing monooxygenase 3 (FMO3) in liver were used to assess TMAO-related metabolic alterations. Alterations of alpha and beta diversity were shown both in the CAP and the Co-CAP groups. Moreover, the percentage of atherosclerotic lesion area increased in the CAP and Co-CAP groups (p < .05). Linear discriminant analysis effect size (LEfSe) at the family level found the increases of Lachnospiraceae and Ruminococcaceae (p < .05), which were positively correlated with serum TMAO levels (p < .05). In the redundancy analysis technique (RDA), serum levels of TMAO were positively associated with the atherosclerotic lesions. Co-occurrence analysis revealed that the relative abundances of Lachnospiraceae and Porphyromonadacae were positively correlated with both the percentage of lesion area and TMAO level (p < .05). Thus, within the limitations of this study, the data suggest that the gut microbiota can mediate the effects of CAP on atherosclerosis.

Twelve-month randomized controlled trial of 38% silver diamine fluoride with or without potassium iodide in indirect pulp capping of young permanent molars

BackgroundThe clinical and radiographic effectiveness of 38% silver diamine fluoride (SDF) with and without potassium iodide (KI) was tested and compared with resin-modified glass ionomer cement (RMGIC) in indirect pulp capping of deep carious lesions in young permanent molars. MethodsOne hundred eight permanent first molars with deep occlusal cavitated carious lesions in 49 children aged 6 through 9 years were randomly allocated into 3 groups (n = 36 molars per group) and treated with SDF plus KI, SDF, and RMGIC. RMGIC was used as a base and a resin-based composite restoration followed. Clinical assessments for secondary caries (primary outcome), postoperative pain, tooth vitality, and restoration success and quality rates according to Modified US Public Health Service and Ryge Criteria for Direct Clinical Evaluation of Restorations were performed after 3, 6, and 12 months. Periapical radiographs were obtained at baseline, 6 months, and 12 months. Outcomes were assessed using mixed effects multilevel logistic and linear regression analyses. ResultsThere were no significant differences (P = .26) among the groups at all times for secondary caries, postoperative pain, tooth vitality, clinical abscess, radiographic signs of pulpal pathology, restorations’ marginal adaption, anatomic form, and surface roughness. There was a significant difference (P = .03) in restoration color, marginal staining, and luster. The RMGIC group outperformed the 2 SDF groups in color and luster. ConclusionsThe authors did not find differences among the groups in preventing secondary caries or pain or in maintaining pulpal health. The RMGIC group had better restoration color and luster than both SDF groups and better marginal staining than the SDF group. Practical ImplicationsThe results of this study can help guide treatment decision making regarding use of SDF and SDF plus KI as indirect pulp capping materials in deep cavitated lesions.This clinical trial was registered at ClinicalTrials.gov. The registration number is NCT04236830.

Effect of thickness on the degree of conversion of two bulk-fill and one conventional posterior resin-based composites at high irradiance and high temporal resolution

ObjectivesThis study: 1) measures the effect of sample thickness and high irradiance on the depth-dependent time delay before photopolymerization reaction onset; 2) determines if exposure reciprocity exists; 3) measures the conversion rate at four irradiance levels; 4) determines the time, t0, at which the maximum DC rate is reached for two bulk-fill and one conventional posterior resin-based composites (RBCs). MethodsTetric PowerFill IVA shade (Ivoclar Vivadent) and Aura bulk-fill ultra universal restorative (SDI), and one conventional posterior resin-based composite (RBC), Heliomolar A3 (Ivoclar Vivadent), that were either 0.2 mm, 2 mm, or 4 mm thick were photocured using a modified Bluephase G4 (Ivoclar Vivadent) light-curing unit (LCU) that delivered a single emission band (wavelength centered at 449 nm). The same radiant exposure of 24 J/cm2 was delivered at irradiances ranging from 0.5 to 3 W/cm2 by adjusting the exposure time. PowerFill was also photocured for 3 s or 6 s using a Bluephase PowerCure LCU (Ivoclar Vivadent) on the 3 s mode setting. The degree of conversion (DC) was measured in real-time at a high temporal resolution at 30 °C using Attenuated Total Reflection (ATR) FTIR spectroscopy with a sampling rate of 13 DC data points per second. The DC data were analyzed using a phenomenological autocatalytic model. The RBC viscosity was measured at 21 °C and 30 °C. Light transmission through the RBC samples at 22 °C was monitored with time to calculate the extinction coefficients of the RBCs. ResultsThe time delay before photopolymerization started increased as the RBC thickness increased and the irradiance decreased. An autocatalytic model described the DC data. The time t0 was less than 77 ms for the 0.2 mm thick samples of PowerFill irradiated using the highest irradiance of 3 W/cm2. Among the three RBCs for each sample thickness and irradiance level, the PowerFill had the smallest time t0. There was a time delay of 0.59 s and 1.25 s before the DC started to increase at the bottom of 4 mm thick samples for the PowerFill and Aura, respectively, when an irradiance of 1 W/cm2 was delivered. The time delay increased to 3.65 s for the Aura when an irradiance of 0.5 W/cm2 was delivered.The extinction coefficients near 449 nm were 0.78 mm−1, 0.76 mm−1, and 1.55 mm−1 during the first 2 s after the start of photocuring of PowerFill, Aura, and Heliomolar, respectively. Only PowerFill followed exposure reciprocity. At T = 30 °C, the viscosity was 3400, 17000, and 5200 Paˑs for PowerFill, Aura, and Heliomolar, respectively. SignificanceThe time delay between when photopolymerization starts at the top and bottom of 2- or 4-mm thick RBC restorations may affect the structural integrity of the bond between the tooth and the bottom of the restoration. Only PowerFill followed exposure reciprocity between irradiance levels of 0.5 to 3 W/cm2. Exposure reciprocity did not occur for Aura or Heliomolar, neither of which are optimized for short light exposure or high irradiance conditions.

NON-INVASIVE ESTHETIC REHABILITATION OF ANTERIOR DIASTEMA WITH DIRECT COMPOSITE RESTORATION

Diastema is a gap between adjacent teeth that occur physiologically from the teeth eruption. However, diastema between the maxillary central incisors in an adult can be an aesthetic problem and sometimes impair speech. Diastema treatment with low or enlarged superior labial frenulum includes frenectomy, orthodontic treatment, veneers, crown, and bridge or resin-based composite direct restorations. This case report will discuss the rehabilitation of diastema in an aesthetic zone of maxillary central incisors due to low frenulum attachment. It was done by a minimally invasive approach using direct composite restoration, completed within several hours after the study model was analyzed, and much less expensive than other forms of treatment. The protocol involved model analysis, smile design, mock-up, silicon index creation, and composite selection. Patient cooperation and understanding of the limitations are critical to long-term treatment success. The direct composite resin is a fast, simple method yet durable to achieve good improvement of small diastema in the aesthetic zone. And stable after three years.

Short fiber-reinforced resin-based composites (SFRCs); Current status and future perspectives.

One technique for placing of resin-based composite for large posterior cavities is the use of short fiber-reinforced resin-based composite (SFRC) to replace dentin in a biomimetic approach. As endurance under mastication cycles is a significant consideration in the clinical success of resin-based composite posterior restorations, the use of SFRC as a base material may prevent restorative fracture due to the fibers' effectiveness in stopping cracks. This review article specifies the characteristics of SFRC and describes the major underlying mechanisms of short fiber reinforcement for resin-based composite. Insights are further taken from laboratory studies used to define the short fiber-related properties of resin-based composite and the performance of currently available materials, focusing on aspects that are relevant to the reinforcement of resin-based composite. Finally, future standpoints on the development of SFRCs with nano fibers and different resin monomers, and their role in digital dentistry, are discussed.

DEAE-Dextran Coated AgNPs: A Highly Blendable Nanofiller Enhances Compressive Strength of Dental Resin Composites.

Micro-crack formation and resultant bacterial infiltration are major causes of secondary caries formation in dental resin-based composite restorations. Improving dental resin composites’ mechanical and biological properties using highly bendable nanoparticles (NPs) can resolve this issue. This study aims to develop novel Diethylaminoethyl (DEAE)-Dextran silver nanoparticles (AgNPs) and subsequently modify composite resins with these NPs to enhance their mechanical and antibacterial properties. DEAE-Dextran AgNPs were successfully synthesized using a chemical reduction method that was confirmed with the help of ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Zeta potential, and energy-dispersive X-ray spectroscopy (EDS). Antibacterial activity of a composite disc with DEAE-Dextran AgNPs was tested against Streptococcus mutans, Enterococcus faecalis, and oral microcosm. The composite discs prepared with DEAE-Dextran AgNPs exhibited excellent antibacterial activity compared with composite resin reinforced by simple AgNPs (p < 0.05). Mechanical properties were significantly enhanced by adding DEAE-Dextran into composite resin (p < 0.05). Moreover, unlike AgNPs, DEAE-Dextran AgNPs were found to be less hemolytic. The results establish strong ground applications for DEAE-Dextran-modified dental composite resins in restorative dental applications.

Intrapulpal temperature changes during the cementation of ceramic veneers

Adhesive cementation of ceramic veneers may increase pulpal temperature (PT) due to the combined effect of heat generated by the curing unit and the exothermic reaction of the luting agent (LA). PT increase may induce pulpal damage. The aim was to determine the PT rise during the luting of ceramic veneers (CV) of different thicknesses with light- or dual-curing (LC, DC) adhesive cements as well as pre-heated restorative resin-based composites (PH-RBC). For this a thermocouple sensor was positioned in the pulp chamber of a prepared maxillary central incisor. LC, DC adhesive cements and PH-RBCs heated to 55 °C were used for the luting of CVs of 0.3, 0.5, 0.7, and 1.0 mm thicknesses. The exothermic reaction of LAs added significantly to the thermal effect of the curing unit. PT change ranged between 8.12 and 14.4 °C with the investigated combinations of LAs and ceramic thicknesses (p ≤ 0.01). The increase was inversely proportional to the increasing CV thicknesses. The highest rise (p ≤ 0.01) was seen with the polymerization of PH-RBCs. Temperature changes were predominantly influenced by the composition of the LA, which was followed by CV thickness.

The Effect of Different Light-curing Units and Tip Distances on the Polymerization Efficiency of Bulk-fill Materials.

In an average class II posterior preparation, the curing light tip is placed at a distance from the restoration surface that far exceeds the 1-mm manufacturer's recommendation. This distance can have potentially detrimental effects on the curing efficiency of the light-curing unit as well as the properties of the resin-based composite restoration, especially at the bottom of the cavity preparation. The purpose of this study was to evaluate the effects of various types of light-curing units (LCUs) and the different curing distances on the degree of conversion (DC) and the surface hardness of bulk-fill composite materials. A total of 390 specimens of three resin-based composites (RBCs) were fabricated. Two bulk-fill RBCs, including Filtek Bulk Fill Posterior (3M ESPE GmbH, Seefeld, Germany) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent AG, Schaan, Liechtenstein), as well as a Filtek Z350 XT nano-filled composite (3M ESPE GmbH, Seefeld, Germany), were utilized. In this study, the Vickers microhardness number (VMN) and the DC were evaluated at 2 and 4 mm thicknesses. Polymerization for 20 seconds was performed using two high-power light-curing units, namely the polywave Bluephase G2 light-emitting diode (LED) LCU (Ivoclar Vivadent AG, Schaan, Liechtenstein) and the monowave Elipar Deep Cure S LED LCU (3M Oral Care, St Paul, MN, USA) at 0, 2, and 4 mm distance between the curing tip and the RBC surface. The results were analyzed using the two-way analysis of variance method. Scheffe's post-hoc multiple comparison tests were used to determine significant differences between the materials, the LCU, and the tip distances. The highest DC (70.17) was shown by Filtek Bulk Fill Posterior at a distance of 0 mm, whereas the lowest DC (45.99) was measured for the conventional Filtek Z350 XT at a 4 mm distance. Moreover, higher VMNs were shown by Filtek Bulk Fill and Filtek Z350 composites at 0 mm distance than by the Tetric N-Ceram Bulk Fill composite material when cured with a Bluephase G2 LCU. For all materials, a significant decrease in the DC and mean VMN values was observed at a 4 mm distance in comparison with 0 and 2 mm distances. The DC and VMN values among the studied bulk fill materials were more significantly affected by the material composition and curing protocols. The increased distance from the light tip has a detrimental effect on the mechanical properties of composite resin materials. Significant differences were observed in the curing efficiency of the two LCUs investigated.

Clinical evaluation of the functional performance of organically modified ceramics (ormocers), nanohybrid, and microhybrid composite in permanent posterior teeth restorations.

Background : In recent times, resin-based direct composite restorations have become a routine and well-established dental practice, meeting the demands for aesthetics and minimally invasive restorative care. The use of resin-based composite resin for defects in posterior teeth is on the rise. A good knowledge of adhesives, composite resins, and polymerization kinetics is required to effectively use composite in patient care.Objective : To compare the functional clinical performance of an ormocer and a nanohybrid to that of a traditional microhybrid composite in posterior teeth restorations.Material and Method : Patients with at least three carious lesions which required replacement (Class Ι and/or Class ΙΙ), each with an opposing tooth, were enrolled in this study. A total of 105 restorations were placed, 35 for each. The materials used for this study included an ormocer-based composite, a nanohybrid resin composite, and a micro-hybrid resin composite. One operator placed all the restorations according to the manufacturers’ instructions. Each restoration is finished and polished immediately after placement. The patient returned for follow-up evaluation at one(1 )month, three (3 )months,six6 months, and 12 months. Two independent examiners calibrated with the web-based training called e-calib performed the evaluation using the FDI Criteria.Results : A total of 105 resin composite restorations, 35 restorations for each of the study materials, were placed in 35 subjects, with a female to male ratio of 4.8:1. The subject recall rate was 100%. All ormocer, nanohybrid, and micro-hybrid resin composites restorations recorded 100% clinically excellent scores from baseline to 3 months for all parameters. Most of the study materials showed a decrease from 100% clinically excellent scores, with a few recordings clinically good at 12 months. At least one restoration of each material experienced a deterioration of the parameters, fracture, retention of materials, and proximal anatomic form.The functional clinical performance of ormocer admira (voco), Tetric EvoCeram (Ivoclar Vivadent), a Nanohybrid, and tetric Ceram (Excite), a micro-hybrid were satisfactory in the restorations of carious posterior permanent teeth. The majority of the restorations maintained clinically excellent scores from 1 month to 12 months. There was, however, no record of scores 3, 4, or 5 by any of the test materials throughout the study.Conclusion : The functional clinical performance of ormocer admira (voco), Tetric EvoCeram (Ivoclar Vivadent), a Nanohybrid, and tetric Ceram (Excite) micro-hybrid were satisfactory in the restorations of posterior permanent teeth restorations.

Comparison of a resin-based sealant with a nano-filled flowable resin composite on sealing performance of marginal defects in resin composites restorations: a 36-months clinical evaluation

Our goal was to evaluate the clinical behavior of resin-based composite (RBC) restorations with sealed marginal defects using nano-filled flowable RBCs (FRS) compared with resin-based sealant (RBS); this work used marginal adaptation, marginal staining, and secondary caries according to the World Dental Federation (FDI) criteria. This was a prospective, randomized, double-blind, controlled trial. Fifty-four patients who met the inclusion criteria (older than 18years old; with high cariogenic risk determined by Cariogram software; and restorations with marginal defects, 3 and 4 according to FDI criteria) were randomly divided into three groups. There were three defective RBC restorations per patient and were repaired (n = 162). The groups were RBS-marginal sealing using a resin-based sealant (Clinpro Sealant, 3M ESPE, MN, USA) plus adhesive (Single Bond Universal, 3M ESPE, MN, USA); FRS-sealing using flowable resin (Filtek Flow Z350XT, 3M ESPE, MN, USA) plus adhesive (Single Bond Universal, 3M ESPE, MN, USA); and control-no repair treatment. All procedures were performed under complete isolation. Evaluations were evaluated at 1-week post treatment (baseline) as well as at 18 and 36months after treatment regarding marginal adaptation, marginal staining, and secondary caries according to FDI criteria. The data were analyzed using the Wilcoxon test (α = 0.05) to compare the differences in each treatment group at different evaluation times. Marginal adaptation of micro-repaired RBC restorations were seen in patients with a high risk of caries using flowable resin composite or resin-based sealants. There were differences (P < 0.001) when baseline was compared at 18 and 36months. Marginal staining showed differences when baseline was compared to 18months (P < 0.001) and 36months (P = 0.001) for both treatments. Secondary caries parameters for RBS treatment showed differences when baseline was compared to 36months (P = 0.025) and when 18months was compared to 36months (P = 0.046). Micro-repair of RBC restorations resulted in clinical deterioration of marginal adaptation and marginal staining. Nano-filled flowable resin composites were sealed on defective restorations; 3 and 4 FDI marginal defects have better clinical performance to prevent secondary caries than resin-based sealants after 36months. Micro-repair with RBS does not seem to be an effective treatment to prevent secondary caries.