Differences in birch tar composition are explained by adhesive function in the central European Iron Age.

Birch bark tar is the most widely documented adhesive in prehistoric Europe. More recent periods attest to a diversification in terms of the materials used as adhesives and their application. Some studies have shown that conifer resins and beeswax were added to produce compound adhesives. For the Iron Age, no comparative large-scale studies have been conducted to provide a wider perspective on adhesive technologies. To address this issue, we identify adhesive substances from the Iron Age in north-eastern France. We applied organic residue analysis to 65 samples from 16 archaeological sites. This included residues adhering to ceramics, from vessel surface coatings, repaired ceramics, vessel contents, and adhesive lumps. Our findings show that, even during the Iron Age in north-eastern France, birch bark tar is one of the best-preserved adhesive substances, used for at least 400 years. To a lesser extent, Pinaceae resin and beeswax were also identified. Through statistical analyses, we show that molecular composition differs in samples, correlating with adhesive function. This has implications for our understanding of birch bark tar production, processing and mode of use during the Iron Age in France and beyond.

A Novel Concept for Developing a Precise and Predictable Post and Core Complex Using the Injectable Resin Technique (Part 2).

Post and core systems have long been used in dentistry for the purposes of replacing missing coronal tooth structure, retaining the core, and providing sufficient retention and resistance form to the final restoration to re-establish original form and function. While Part 1 of this two-part article provided a history of post and core systems and materials and discussed empirical data regarding fiber-reinforced post systems, this second part of the article focuses on an alternative approach for developing a fiber-reinforced post and core system using a monoblock system via the injectable resin technique and a recently developed fiber-optic post. The present article explains the concept of a ferrule effect and demonstrates the novel restorative procedure.

Experimental characterization and finite element investigation of SiO2 nanoparticles reinforced dental resin composite.

In this study, a commercial dental resin was reinforced by SiO2 nanoparticles (NPs) with different concentrations to enhance its mechanical functionality. The material characterization and finite element analysis (FEA) have been performed to evaluate the mechanical properties. Wedge indentation and 3-point bending tests were conducted to assess the mechanical behavior of the prepared nanocomposites. The results revealed that the optimal content of NPs was achieved at 1% SiO2, resulting in a 35% increase in the indentation reaction force. Therefore, the sample containing 1% SiO2 NPs was considered for further tests. The morphology of selected sample was examined using field emission scanning electron microscopy (FE-SEM), revealing the homogeneous dispersion of SiO2 NPs with minimal agglomeration. X-ray diffraction (XRD) was employed to investigate the crystalline structure of the selected sample, indicating no change in the dental resin state upon adding SiO2 NPs. In the second part of the study, a novel approach called iterative FEA, supported by the experiment wedge indentation test, was used to determine the mechanical properties of the 1% SiO2-dental resin. Subsequently, the accurately determined material properties were assigned to a dental crown model to virtually investigate its behavior under oblique loading. The virtual test results demonstrated that most microcracks initiated from the top of the crown and extended through its thickness.

Evaluation of Microbiological Susceptibility and Long-term Adhesive Properties to Dentin of Primers with Terminalia catappa Linn.

PURPOSE: To investigate the antibacterial effects of Terminalia catappa Linn (TCL) leaf extracts at different concentrations and the effects of these extracts used as primers on the long-term adhesive properties of two universal adhesives. MATERIALS AND METHODS: After extract preparation, the antimicrobial and antibacterial activities of TCL against Streptococcus mutans (UA 159) were assessed in microdilution assays to provide the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Additionally, to provide quantitative data on the ability of TCL extract to reduce cell viability, colony forming units (CFU) were counted. To examine adhesive properties, 288 human molars were randomly assigned to 32 experimental conditions (n = 9) according to the following variables: (1) treatment agent: negative control (untreated surface), and primers at concentrations of 1xMIC, 5xMIC, and 10xMIC; (2) adhesives: Scotchbond Universal (SBU) and Futurabond Universal (FBU); (3) adhesive strategy: etch-and-rinse (ER) or self-etch (SE); and (4) storage time: 24 h or after 2 years. Primers were applied for 60 s, upon which the teeth were incrementally restored and sectioned into adhesive-dentin bonded sticks. These were tested for microtensile bond strength (µTBS) and nanoleakage (NL) after 24-h and 2-year water storage, as well as in-situ degree of conversion (DC) at 24 h. The chemical profile of the hybrid layer was determined via micro-Raman spectroscopy. Biofilm assay data were analyzed using the Kruskal-Wallis test; the pH of culture media and the chemical profile were analyzed by one-way ANOVA. The adhesive properties (µTBS, NL, DC) were evaluated using a four-way ANOVA and Tukey's test. Significance was set at 5%. RESULTS: Similar values of MIC and MBC were observed (2 mg/ml), showing bactericidal potential. CFU analysis demonstrated that concentrations of 5xMIC and 10xMIC significantly inhibited biofilm formation (p < 0.001). The application of the TCL primer at all concentrations significantly increased the immediate µTBS and DC, and decreased the immediate NL values when compared to the control group (p < 0.05), regardless of the adhesive and adhesive strategies. Despite an increase in the NL values for all groups after 2 years (p > 0.05), in groups where the TCL primer was applied, the µTBS remained constant after 2 years for both adhesives, while a decrease in the µTBS was observed in the control groups (p < 0.05). Usually, 10xMIC showed better results than 1xMIC and 5xMIC (p < 0.05). The application of TCL promoted cross-linking; cross-linking rates increased proportionally to the concentration of TCL (p < 0.05). CONCLUSION: Primers containing TCL promoted bactericidal and bacteriostatic action, as well as cross-linking with dentin, while maintaining the adhesive properties of the adhesive-dentin interface after 2 years of water storage.

Effect of Surface Treatment with Alkaline Agents at Two Different Temperatures on Microshear Bond Strength of Zirconia to Composite Resin.

Background: Zirconia, with its excellent mechanical properties, has become a popular choice for esthetic and durable restorations due to the increasing demand of patients. It has overcome most of the limitations of all ceramic restorations. However, bonding to zirconia remains a challenge. Objectives: This study is aimed at assessing the effect of surface treatment with alkaline agents at two different temperatures on microshear bond strength (µSBS) of zirconia to composite resin. Materials and Methods: This in vitro, experimental study was conducted on zirconia blocks measuring 2 × 4 × 8 mm. The blocks were sandblasted with alumina powder and randomly assigned to 5 groups (n = 16 each). The blocks in groups 1 and 2 underwent surface treatment with sodium hydroxide (NaOH) and groups 3 and 4 with zirconium hydroxide (Zr(OH)4) at room temperature and 70°C. Group 5 served as the control group and did not receive any surface treatment. After the application of bonding agent and its light-curing, composite cylinders in plastic tubes were bonded to the surface of each block and cured. After incubation, they underwent µSBS test. Data were analyzed by one-way ANOVA and Tukey's test (alpha = 0.05). Results: The µSBS was significantly higher in all intervention groups than that in the control group (P < 0.05). The µSBS in Zr(OH)4 groups was significantly higher than that in NaOH groups (P < 0.05). The mean µSBS of heated groups was slightly, but not significantly, higher than the corresponding room temperature groups (P > 0.05). Conclusion: Surface treatment of zirconia with NaOH and Zr(OH)4 alkaline agents can increase its µSBS to composite resin; Zr(OH)4 was significantly more effective than NAOH for this purpose, but heating did not have a significant effect on µSBS.

Marginal adaptation of two-step self-etch versus universal adhesives for Class V restorations: Effect of Er:YAG laser vs. bur prepared cavities.

PURPOSE: To compare the in vitro effect of laser and bur preparation on marginal adaptation of Class V cavities restored with a 2-step self-etch and distinct universal one-component universal adhesives used in self-etching mode. METHODS: 96 Class V cavities were prepared with conventional burs or with an Er:YAG laser. Four universal self-etch (Unibond Extra Low Shrinkage, All Bond Universal, SKB-100 and Prime&Bond active) and a 2-step self-etch adhesive (Clearfil SE Bond) that served as control were used to restore the cavities with direct composite. The percentages of continuous margins were evaluated by quantitative SEM analysis before and after a fatigue test consisting of 240,000 occlusal loads and 600 warm/cold thermal cycles. RESULTS: The marginal adaptation of bur prepared restorations was statistically superior to laser-prepared ones. Class V cavities restored with Clearfil SE Bond and the one-component self-etching universal adhesives All Bond Universal and Prime&Bond active presented the highest and statistically similar percentages of continuous margins before and after loading under both bur and laser cavity preparation. The lowest percentages of continuous margins were observed in the groups restored with the low shrinking adhesive (Unibond ELS), with medians of 49 and 21 for bur and laser prepared cavities after loading. CLINICAL SIGNIFICANCE: Class V cavities presented smoother and higher percentages of continuous margins when prepared by bur rather than by laser. The 2-step self-etch adhesive Clearfil SE Bond and 1-step self-etch universal adhesives All Bond Universal and Prime&Bond active showed a comparable marginal performance.

Effect of ultrasonic and sonic instrumentation on shear bond strength of resin composite to enamel: An in vitro study.

PURPOSE: To assess and compare the effects of sonic and ultrasonic instrumentation on shear bond strength (SBS) and investigate the influence of adhesive system application modes (etch&rinse/self-etch) on SBS. METHODS: In this experimental study, 45 extracted sound human molars were selected. Mesial and distal surfaces of the teeth were abraded until 90 smooth enamel surfaces were obtained. Specimens were divided into two groups, with half (N= 45) conditioned in etch&rinse mode and the remaining (N= 45) in self-etch mode using Tetric N Bond Universal. Composite resin discs were produced on these surfaces by filling Teflon molds. All specimens were aged via thermocycling. Each group was further divided into three more groups (n= 15) according to the type of periodontal instrumentation (ultrasonic, sonic or none). SBS values were recorded and analyzed using two-way ANOVA. Fracture sites were examined under a stereomicroscope. RESULTS: The type of periodontal instrumentation had no significant effect on SBS values, whether sonic, ultrasonic or their absence (P= 0.945). The type of adhesive system mode had a significant influence on the shear bond strength values. Etch&rinse groups had significantly higher shear bond strength values than self-etch groups (P< 0.001). CLINICAL SIGNIFICANCE: This study reassures practitioners that sonic and ultrasonic instruments are safe for enamel bonding and highlights the importance of selecting adhesive techniques for optimal restorative outcomes.

A Novel Concept for Developing a Precise and Predictable Post and Core Complex Using the Injectable Resin Technique.

Post systems have long been used in the roots of teeth to retain dental restorations. The primary objectives of current post and core systems are to replace missing coronal tooth structure, retain the core, and provide sufficient retention and resistance form to the final restoration to restore original form and function. Many varieties of user-friendly post and core systems are available today for different endodontic, restorative, and esthetic requirements. The present article provides a history of post and core usage in dentistry, describes various systems and materials for this purpose, and discusses empirical data regarding fiber-reinforced post systems.

Shear Bond Strength to Enamel, Mechanical Properties and Cellular Studies of Fiber-Reinforced Composites Modified by Depositing SiO2 Nanofilms on Quartz Fibers via Atomic Layer Deposition.

Introduction: Poor interfacial bonding between the fibers and resin matrix in fiber-reinforced composites (FRCs) is a significant drawback of the composites. To enhance the mechanical properties of FRC, fibers were modified by depositing SiO2 nanofilms via the atomic layer deposition (ALD) technique. This study aims to evaluate the effect of ALD treatment of the fibers on the mechanical properties of the FRCs. Methods: The quartz fibers were modified by depositing different cycles (50, 100, 200, and 400) of SiO2 nanofilms via the ALD technique and FRCs were proposed from the modified fibers. The morphologies, surface characterizations of nanofilms, mechanical properties, and cytocompatibility of FRCs were systematically investigated. Moreover, the shear bond strength (SBS) of FRCs to human enamel was also evaluated. Results: The SEM and SE results showed that the ALD-deposited SiO2 nanofilms have good conformality and homogeneity. According to the results of FTIR and TGA, SiO2 nanofilms and quartz fiber surfaces had good chemical combinations. Three-point bending tests with FRCs showed that the deposited SiO2 nanofilms effectively improved FRCs' strength and Group D underwent 100 deposition cycles and had the highest flexural strength before and after aging. Furthermore, the strength of the FRCs demonstrated a crescendo-decrescendo tendency with SiO2 nanofilm thickness increasing. The SBS results also showed that Group D had outstanding performance. Moreover, the results of cytotoxicity experiments such as cck8, LDH and Elisa, etc., showed that the FRCs have good cytocompatibility. Conclusion: Changing the number of ALD reaction cycles affects the mechanical properties of FRCs, which may be related to the stress relaxation and fracture between SiO2 nanofilm layers and the built-up internal stresses in the nanofilms. Eventually, the SiO2 nanofilms could enhance the FRCs' mechanical properties and performance to enamel by improving the interfacial bonding strength, and have good cytocompatibility.

Evaluation of mechanical properties of anatomically customized fiber posts using E-glass short fiber-reinforced composite to restore weakened endodontically treated premolars.

OBJECTIVE: This study was conducted to assess the influence of combining different forms of fiber-reinforced composites (FRC) on the mechanical behavior and bond strength of compromised endodontically treated teeth (ETT). MATERIALS AND METHODS: Eighty extracted human premolar teeth were randomly divided into five experimental groups according to the type of intra-radicular restoration and the canal preparation design which was either non-flared (Group 1), flared (Groups 2-5), closed-apex (Groups 1,3,5) or open-apex (Groups 2,4). Standard prefabricated fiber posts were used as intra-radicular restoration for Groups 1-3 while Groups 4-5 were restored with anatomically customized relined fiber posts. After composite core fabrication, all samples were sent for an artificial aging process. Fracture resistance and push-out bond strength tests were then carried out through a universal testing machine followed by mode of failure analysis via a stereomicroscope and scanning electron microscope. RESULTS: Pairwise Log-Rank comparisons revealed that the survival rate of Group 2 and Group 3 was significantly lower than all other groups after artificial aging. The highest fracture resistance value (1796 N) was recorded in Group 5 and was significantly higher than that of the other groups (p < 0.05), while Group 2 exhibited the lowest fracture resistance (758 N), which was significantly lower compared to the other groups. Group 5 and Group 4 demonstrated a significantly higher push-out bond strength, at all root thirds, than Group 3, Group 2, and Group 1 (p < 0.05). The most frequently observed failure mode in the tested groups occurred between the resin cement and radicular dentin. CONCLUSION: The use of short fiber-reinforced composite (SFRC) to reline the prefabricated FRC post has been proven to have superior fracture resistance with favorable failure patterns and increased push-out bond strength values compared to standard prefabricated FRC posts.

High-Performance Dental Resins Containing a Starburst Monomer.

Dimethacrylate-based chemistries feature extensively as resin monomers in dental resin-based materials due to their distinguished overall performance. However, challenges endure, encompassing inadequate mechanical attributes, volumetric shrinkage, and estrogenicity. Herein, we first synthesized a novel resin monomer, 9-armed starburst polyurethane acrylate (NPUA), via the grafting-onto approach. Compared to the primary commercial dental monomer 2,2-bis [p-(2'-hydroxy-3'-methacryloxypropoxy) phenyl] propane (Bis-GMA) (with a viscosity of 1,174 ± 3 Pa·s and volumetric shrinkage of 4.7% ± 0.1%), the NPUA monomer achieves the lower viscosity (158 ± 1 Pa·s), volumetric shrinkage (2.5% ± 0.1%), and cytotoxicity (P < 0.05). The NPUA-based resins exhibit the higher flexural strength, flexural modulus, hardness, and hydrophobicity and lower volumetric shrinkage, water absorption, and solubility compared to the Bis-GMA (70 wt%)/TEGDMA (30 wt%) resins. The NPUA-based composites exhibit significantly higher flexural strength, flexural modulus, and hardness and lower volumetric shrinkage (171.4 ± 3.0 MPa, 12.6 ± 0.5 GPa, 2.0 ± 0.2 GPa, and 3.4% ± 0.2%, respectively) compared to the Bis-GMA group (120.3 ± 4.7 MPa, 9.4 ± 0.7 GPa, 1.5 ± 0.1 GPa, and 4.7% ± 0.2%, respectively; P < 0.05). This work presents a viable avenue for augmenting the physicochemical attributes of dental resins.

Influence of printing orientation on mechanical properties of aged 3D-printed restorative resins.

OBJECTIVE: To evaluate the influence of printing orientation on flexural strength (σf) and elastic modulus (E) of different 3D printing dental restorative resins. METHODS: Bar-shaped specimens (n = 20) were fabricated from two SLA-printed resins (FT- Formlabs Temporary, and FP- Formlabs Permanent) and two DLP-printed resins (DFT- Detax Freeprint Temp, and GCT- GC Temporary) using two building orientations (0º and 90º). The 3D-printed structures were aged (14 d) before submitted to three-point bending in 37ºC distilled water at a crosshead speed of 1.0 ± 0.3 mm/min until fracture to calculate the σf and the E values. The fractured surfaces were evaluated using stereomicroscopy and scanning electron microscopy (SEM) following fractography principles. Data were statistically analyzed using two-way ANOVA and Tukey post-hoc (α = 0.001). RESULTS: FP and FT showed significantly higher E values than DFT and GCT, irrespectively of printing orientation (p < 0.001). There was no statistical difference between the building orientations (0º and 90º) for the mean σf and E values for the resin materials evaluated. Fractographic characteristics were similar for the surface fracture from all the materials evaluated, showing typical brittle fracture behavior. SIGNIFICANCE: Printing orientation did not influence of flexural strength and elastic modulus values for the 3D-printed resin structures evaluated. Surface topography was mostly governed by the 3D printer type.

Componeer as an aesthetic treatment option for anterior teeth: a case report.

INTRODUCTION: Structural abnormalities or anomalies in the anterior teeth, also known as the aesthetic zone, are an important problem for patients and a challenge for dentists. Structural abnormalities or tooth anomalies can change in color, shape, and function. Most dentists prefer minimally invasive aesthetic treatment. One of the aesthetic treatment options for anterior teeth is veneers. Veneer is a restoration that covers the labial part of the tooth with a thin layer of material to correct abnormalities in the color, shape, or function of the tooth. Veneer restoration can be done indirectly with porcelain material made in a laboratory and directly with composite material on the tooth surface or prefabricated which is available from the factory. Componeer is a prefabricated composite veneer that combines the aesthetic properties of ceramic veneers and the adhesive ability of composite veneers to the tooth structure. This case report describes the treatment of two central incisors that had been filled with composite and peg shapes on both lateral incisors using a componeer. CASE REPORT: A 32-year-old female patient came to the Dental Conservation Clinic at Dentistry Hospital, Padjadjaran University with the main complaint of her right and left upper front teeth and wanted to repair her old fillings and close the gap between her right and left upper front teeth and her canine teeth. Clinical examination showed that teeth 11 and 21 had been filled with composite which had changed color and had an inharmonious shape as well as a gap between the upper front teeth on the right and left sides and the right and left canine teeth. TREATMENT: The maxilla and mandibular teeth are molded for study models and working models. In the working model, a wax-up is carried out, then a mock-up on the patient's teeth. Next, choose the color and size of the components that match the mock up results. Teeth 11 and 21 had their old composite fillings cleaned and refilled with dentin colored composite, teeth 13, 12, 11, 21, 22, and 23 were prepared with a minimum thickness of 0.3 mm to make room for the componeer material. The teeth was etched and bonded, and bonding was applied to the inner surface of the componeer. The composite is placed on the inner surface of the componeer then placed on the labial surface of the tooth and pressed with a special tool, then light cured. The final step is polishing. TREATMENT RESULTS: Teeth 13, 12, 11, 21, 22, and 23 which had undergone veneer treatment using componeer, were controlled after 1 week of treatment. The patient did not complain about the results of the treatment and said he was satisfied with the treatment.

Comparative study of physical-chemical properties of bioactive glass ionomer cement.

This study analyzed the physical-chemical properties of bioactive ionomer materials. Cention N bioactive materials were evaluated chemically activated (CN) and light-cured (CN-LC), Equia Forte Fill (EQUI); conventional resin composite Filtek Z350 XT (Z350); resin glass ionomer cement Riva light Cure (RIVA) and flowable resin composite Filtek Bulk Fill Flow (BULK-F) were evaluated. Sixty specimens (n=10) were prepared for sorption (SR), solubility (SL), flexural strength (FS), shrinkage stress (SS), conversion degree (CD), microhardness (MI), and surface roughness (SR) tests. Non-cured and light-cured materials were assessed on FTIR. 30 human molar teeth were used in the bond strength test (BS). Data were subjected to ANOVA and post-hoc Tukey's test (5% of significance). EQUI showed more sorption in SR and no statistical difference from RIVA and CN-LC. CN group showed more solubility and EQUI presented less (p<0.05). BULK-F showed higher FS (MPa), without differences from CN and Z350, whereas EQUI presented the lowest FS not differing from RIVA. BULK-F and CN-LC showed more shrinkage stress differing from EQUI. CN-LC and CN showed higher CD differing from the other which showed no differences (p>0.05) between them. EQUI showed the highest hardness (p<0.05) in MI. There were no differences (p>0.05) in SR (µm). Z350 and BULK-F presented higher BS, whereas CN-LC showed the lowest, although not differing from EQUI and RIVA. Equia Forte's solubility and microhardness make it a good alternative as a restorative material. Cention N degree of conversion and flexural strength making it an esthetic option to amalgam.

Effect of chitosan and CMCS on dentin after Er:YAG laser irradiation: shear bond strength and surface morphology analysis.

OBJECTIVES: The aim of the present study was to evaluate the effect of chitosan and carboxymethyl chitosan (CMCS) on dentin surface morphology and bonding strength after irradiation of Er:YAG laser. METHODS: Eighty-four laser-irradiated dentin samples were randomly distributed into three groups (n = 28/group) according to different surface conditioning process: deionized water for 60s; 1wt% chitosan for 60s; or 1wt% CMCS for 60s. Two specimens from each group were subjected to TEM analysis to confirm the presence of extrafibrillar demineralization on dentin fibrils. Two specimens from each group were subjected to morphological analysis by SEM. Seventy-two specimens (n = 24/group) were prepared, with a composite resin cone adhered to the dentin surface, and were then randomly assigned to one of two aging processes: storage in deionized water for 24 h or a thermocycling stimulation. The shear bond strength of laser-irradiated dentin to the resin composite was determined by a universal testing machine. Data acquired in the shear bond strength test was analyzed by one-way ANOVA with the Tukey honestly significant difference post hoc test and Independent Samples t-test (α = 0.05). RESULTS: CMCS group presented demineralized zone and a relatively smooth dentin surface morphology. CMCS group had significantly higher SBS value (6.08 ± 2.12) without aging (p < 0.05). After thermal cycling, both chitosan (5.26 ± 2.30) and CMCS group (5.82 ± 1.90) presented higher bonding strength compared to control group (3.19 ± 1.32) (p < 0.05). Chitosan and CMCS group preserved the bonding strength after aging process (p > 0.05). CONCLUSIONS: CMCS has the potential to be applied in conjunction with Er:YAG laser in cavity preparation and resin restoration.

Comparative bonding performance of coronal dentin disks and CAD/CAM resin composite disks for biological restoration: The impact of resin-coating technique.

This study evaluated the bonding performance of coronal dentin disks, designed for biological restoration, and CAD/CAM resin composite disks when bonded to flat dentin surfaces using dual-cure resin cements, with and without a resin-coating (RC) technique. Three distinct groups were established within the non-RC group, each using one of the two types of resin cements in a self-adhesive mode: one-step self-etch adhesive (1-SEA) without light-cure, 1-SEA with light-cure, and a separate group using an alternate cement. Within the RC group, a subgroup was established for each cement. The microtensile bond strength (µTBS) of the disk-dentin beam was tested after 0 and 10,000 thermocycles in a 5°C/55°C. No significant µTBS difference was observed among the non-RC groups. However, when using RC, the µTBSs of coronal dentin disks significantly exceeded those of CAD/CAM resin composite disks. Thermocycle aging did not affect µTBS in any of the bonding methods, except in self-adhesive mode.

Adhesion of tooth fragment after trauma: effect of adhesion strategy and storage in the rescue box.

This study aims to investigate the impact of storage conditions for crown fragments (specifically, whether they were stored within a tooth rescue box or in tap water) on their adhesion to fractured teeth when subjected to two different adhesive systems (namely, total etch and self etch). Sixty maxillary premolars were sectioned to obtain tooth fragments. These fragments were stored briefly (2 hours) and reattached in the following groups: Group 1 (fragments stored in tooth rescue box and reattached with etch and rinse (E&R) technique), Group 2 (fragments stored in tap water and reattached with E&R technique), Group 3 (fragments stored in tooth rescue box and reattached with self-etch (SE) technique), and Group 4 (fragments stored in tap water and reattached SE technique). After reattachment, the bonded tooth fragments underwent thermal cycling (500 cycles, 5-55 °C) and bond strength testing using a universal testing machine. Two-way Analysis of Variance (ANOVA) and Tukey's tests were used for bond strength comparison (p ≤ 0.05). A two-parameter Weibull distribution was conducted to evaluate the reliability of the storage medium and adhesion modality on bond strength. The results showed that measured shear bond values (MPa ± Standard deviation (SD); arranged in descending order) for each group were: Group 2 (Tap water/E&R = 6.5 ± 2.1), Group 1 (Rescue box/E&R = 6.0 ± 2.5), Group 4 (Tap water/E&R = 5.1 ± 2.8), and Group 3 (Rescue box/SE = 3.6 ± 3.2). Significant differences were found only between Groups 2 and 3 (p = 0.002). In conclusion, storing crown fragments in a tooth rescue box did not significantly affect the shear bond strength of the restored tooth. However, fragments reattached using the self-etch technique showed comparable shear bond strength but a higher rate of adhesive failures compared to the E&R technique.

Two-body wear of novel monolithic lithium-silicate ceramic materials and their corresponding different antagonists.

OBJECTIVES: Evaluation of the two-body wear of lithium-silicate ceramics against different antagonists compared to a direct resin composite and human teeth. METHODS: Initial LiSi Block [LISI], IPS e.max CAD [EMA], and CEREC Tessera [TESE] were investigated and compared with direct resin composite [FILL] and human teeth [tooth]. As antagonists were used: steatite, ceramic, and human enamel. The control group tooth was only tested with enamel antagonist. The combinations underwent thermomechanical aging using a chewing simulator. Material losses were calculated using GOM-analysis software. Kolmogorov-Smirnov test, Kruskal-Wallis H, Mann-Whitney-U-test with Bonferroni correction and Spearman-rho correlation were calculated. A fractographic analysis was performed. RESULTS: Within TESE, enamel antagonists led to lower restoration losses than steatite and ceramic antagonists. Within FILL, enamel and steatite antagonists caused lower material losses compared to ceramic antagonists. Against steatite antagonists, LISI showed lowest material losses. Against ceramic antagonists, the use of LISI led to lower material losses compared to FILL. Against tooth antagonists, TESE showed lower material losses than tooth and FILL and LISI lower than FILL. Within LISI, steatite antagonists showed lower material losses on the antagonist than ceramic. Within EMA, steatite antagonists showed higher material losses than ceramic ones. Within ceramic antagonists, LISI restoration material showed lower material losses than FILL and EMA. CONCLUSIONS: Regardless of the antagonist material, the material losses of LISI and EMA were comparable. However, the abrasion resistance of LISI tended to be higher than EMA. CLINICAL SIGNIFICANCE: LISI is a fully crystallized lithium-silicate ceramic and no longer needs to be processed after milling. In addition, the abrasion resistance is very good, regardless of the antagonist material chosen.

A depth-resolved quantitative evaluation method for non-carious cervical lesions treatment with optical coherence tomography.

OBJECTIVES: The aim of this study is prognostic assessment of surface smoothness and the presence of internal bubbles after treatment of non-cancerous cervical lesions (NCCLs) using optical coherence tomography (OCT). METHODS: After treatment with NCCLs, cross-sectional images of the lesion parts of the sample were non-invasively acquired and analyzed. The surface smoothness between tooth and resin, resin and cemento-enamel junction, and the presence bubble inside resin was confirmed. In addition, using an algorithm that distinguishes between resin and dental structure based on OCT cross-sectional images, we quantitatively analyzed the amount of resin used in treating NCCLs and acquired 3D images. RESULTS: The inner structure of the resin in each sample was checked, and the presence of bubbles was confirmed. In addition, the resin sections were separated from the tomographic images acquired by OCT to visualize 3D images. The volume of resin used in the treatment part of each NCCLs samples was quantitatively analyzed as 3.7216 ∼ 14.889 mm3. CONCLUSIONS: OCT is able to measure not only the surface abrasion provided by existing intraoral scanner, but also the size and depth location of interal bubbles, which is distinctive advantage of our method. Based on our results, OCT is a significant tool for qualitative and quantitative analysis of dental NCCLs treatment before and after treatment. CLINICAL SIGNIFICANCE: The study used OCT, a non-destructive diagnostic, to reveal the structure of the resin and the location and size of bubbles after NCCLs treatment. These findings could be golden standard in determining the prognosis of NCCLs treatment.

Clinical performance of short fiber reinforced composite and glass hybrid on hypomineralized molars: A 36-month randomized split-mouth study.

OBJECTIVES: This study aimed to assess the clinical performance outcome at 36 months of molars with molar incisor hypomineralization and carious lesions, treated with two different restorative approaches following selective caries removal. METHODS: The children aged 6 to 12 years (18 female, 13 male) included in the study had at least two carious permanent first molars diagnosed with molar incisor hypomineralization. Sixty-two molars were restored in a split-mouth design. In all subjects, selective caries removal was performed so that caries was completely removed from the cavosurface walls and only soft dentin was left above the pulp chamber. Short fiber reinforced composite (SFRC; EverX Flow™) covered by micro-hybrid composite (G-Aenial® posterior composite) and Glass Hybrid (GH; Equia Forte® HT) were used as restorative materials. The restorations were evaluated according to modified United States Public Health Service (USPHS) criteria at baseline, 6, 12, 18, 24, and 36 month follow-ups. RESULTS: During the 36-month follow-up, eight GH and four SFRC restorations failed. The clinical success of both restorations decreased statistically over time (p < 0.001 for both). When variables such as restoration type, sex, age, tooth type, and time were included in the model, the risk of failure of the restorations of the left lower first molar was statistically significantly higher than that of the left upper first molar (p < 0.002). CONCLUSION: Direct composite restorations with SFRC and GH restorations perform similar clinical success with selective caries removal in the management of permanent molars affected by molar incisor hypomineralization. CLINICAL SIGNIFICANCE: SFRC or GH restorations with similar clinical success might be preferred for the management of MIH-affected molars.