Longevity Of Dental Restorations Research Articles

Mechanistic study of the stabilization of dentin-bonded restorative interfaces via collagen reinforcement by multi-acrylamides

Hydrolytically and enzymatically-stable multi-acrylamides have been proposed to increase the long-term durability of dental adhesive interfaces as alternatives to methacrylates. The aim of this study was to investigate the mechanical and biochemical properties of experimental adhesives containing multi-functional acrylamides concerning collagen reinforcement and metalloproteinases (MMP) activity. Multi-functional acrylamides, TMAAEA (Tris[(2-methylaminoacryl) ethylamine) and DEBAAP (N,N-Diethyl-1,3-bis(acrylamido) propane), along with the commercially available DMAM (N,N-dimethylacrylamide) (monofunctional acrylamide) and HEMA (2-Hydroxyethyl methacrylate) (monofunctional methacrylate - control) were tested for stability against enzymatic hydrolysis by cholesterol esterase/pseudocholinesterase (PC/PCE) solutions for up to 30 days. Collagen-derived substrate and gelatin zymography were performed to examine the effect of the compounds on the biological activity of human recombinant and dentin-extracted gelatinases MMP-2 and MMP-9. In situ zymography was carried out by fluorescent collagen degradation combined with confocal microscopy analysis. Hydroxyproline content was measured in collagen derived from dentin extracts though reaction with Ehrlich's reagent p-dimethylaminobenzaldehyde (DMAB), generating a stable chromophore measured at 550 nm. Storage shear modulus of demineralized dentin discs treated with the tested compounds was measured by oscillatory rheometry, in order to investigate potential collagen reinforcement. FT-IR was performed to determine qualitative differences in collagen based on observed changes in amide bands. The results were analyzed by ANOVA/Tukey's test (α = 0.05). Multi-acrylamides survived 30 days of incubation in cholinesterase/pseudo-cholinesterase (PC/PCE) solutions, while HEMA showed approximately 70 % overall degradation. Incubation with multi-acrylamides reduced collagen degradation as evidenced by the reduced hydroxyproline levels and by the 30 % increase inshear storage modulus. Biochemical and zymography assays showed no noticeable inhibition of recombinant and extracted MMPs enzymatic activity. The infra-red spectroscopy results for multi-functional acrylamides treated samples demonstrated shifts of the amide II bonds and marked increase in intensity of the bands 1200 cm-1, which may indicate partial collagen denaturation and some degree of cross-linking of the compounds with collagen, respectively. The multi-acrylamides exhibited not only comparable mechanical properties but also demonstrated significantly enhanced biochemical stability when compared to the widely used methacrylate control.Clinical relevance: These findings highlight the potential of multi-acrylamides to increase the bonding stability to tissues and, ultimately, contribute to the longevity of dental restorations.

Longevity of dental restorations in Sjogren’s disease patients using electronic dental and health record data

BackgroundDecreased salivary secretion is not only a risk factor for carious lesions in Sjögren’s disease (SD) but also an indicator of deterioration of teeth with every restorative replacement. This study determined the longevity of direct dental restorations placed in patients with SD using matched electronic dental record (EDR) and electronic health record (EHR) data.MethodsWe conducted a retrospective cohort study using EDR and EHR data of Indiana University School of Dentistry patients who have a SD diagnosis in their EHR. Treatment history of patients during 15 years with SD (cases) and their matched controls with at least one direct dental restoration were retrieved from the EDR. Descriptive statistics summarized the study population characteristics. Cox regression models with random effects analyzed differences between cases and controls for time to direct restoration failure. Further the model explored the effect of covariates such as age, sex, race, dental insurance, medical insurance, medical diagnosis, medication use, preventive dental visits per year, and the number of tooth surfaces on time to restoration failure.ResultsAt least one completed direct restoration was present for 102 cases and 42 controls resulting in a cohort of 144 patients’ EDR and EHR data. The cases were distributed as 21 positives, 57 negatives, and 24 uncertain cases based on clinical findings. The average age was 56, about 93% were females, 54% were White, 74% had no dental insurance, 61% had public medical insurance, < 1 preventive dental visit per year, 94% used medications and 93% had a medical diagnosis that potentially causes dry mouth within the overall study cohort. About 529 direct dental restorations were present in cases with SD and 140 restorations in corresponding controls. Hazard ratios of 2.99 (1.48–6.03; p = 0.002) and 3.30 (1.49–7.31, p-value: 0.003) showed significantly decreased time to restoration failure among cases and positive for SD cases compared to controls, respectively. Except for the number of tooth surfaces, no other covariates had a significant influence on the survival time.ConclusionConsidering the rapid failure of dental restorations, appropriate post-treatment assessment, management, and evaluation should be implemented while planning restorative dental procedures among cases with SD. Since survival time is decreased with an increase in the number of surfaces, guidelines for restorative procedures should be formulated specifically for patients with SD.

Multifunctional Dental Adhesives Formulated with Silane-Coated Magnetic Fe3O4@m-SiO2 Core-Shell Particles to Counteract Adhesive Interfacial Breakdown.

The process of bonding to dentin is complex and dynamic, greatly impacting the longevity of dental restorations. The tooth/dental material interface is degraded by bacterial acids, matrix metalloproteinases (MMPs), and hydrolysis. As a result, bonded dental restorations face reduced longevity due to adhesive interfacial breakdown, leading to leakage, tooth pain, recurrent caries, and costly restoration replacements. To address this issue, we synthesized and characterized a multifunctional magnetic platform, CHX@SiQuac@Fe3O4@m-SiO2, to provide several beneficial functions. The platform comprises Fe3O4 microparticles and chlorhexidine (CHX) encapsulated within mesoporous silica, which was silanized by an antibacterial quaternary ammonium silane (SiQuac). This platform simultaneously targets bacterial inhibition, stability of the hybrid layer, and enhanced filler infiltration by magnetic motion. Comprehensive experiments include X-ray diffraction, FT-IR, VSM, EDS, N2 adsorption-desorption (BET), transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Then, CHX@SiQuac@Fe3O4@m-SiO2 was incorporated into an experimental adhesive resin for dental bonding restorations, followed by immediate and long-term antibacterial assessment, cytotoxicity evaluation, and mechanical and bonding performance. The results confirmed the multifunctional nature of CHX@SiQuac@Fe3O4@m-SiO2. This work outlined a roadmap for (1) designing and tuning an adhesive formulation containing the new platform CHX@SiQuac@Fe3O4@m-SiO2; (2) assessing microtensile bond strength to dentin using a clinically relevant model of simulated hydrostatic pulpal pressure; and (3) investigating the antibacterial outcome performance of the particles when embedded into the formulated adhesives over time. The results showed that at 4 wt % of CHX@SiQuac@Fe3O4@m-SiO2-doped adhesive under the guided magnetic field, the bond strength increased by 28%. CHX@SiQuac@Fe3O4@m-SiO2 enhanced dentin adhesion in the magnetic guide bonding process without altering adhesive properties or causing cytotoxicity. This finding presents a promising method for strengthening the tooth/dental material interface's stability and extending the bonded restorations' lifespan.

Optimizing Dental Bond Strength: Insights from Comprehensive Literature Review and Future Implications for Clinical Practice.

This review examines the modifying factors affecting bond strength in various bonding scenarios, particularly their relevance to the longevity of dental restorations. Understanding these factors is crucial for improving clinical outcomes in dentistry. Data were gathered from the PubMed database, ResearchGate, and Google Scholar resources, covering studies from 1992 to 2022. The findings suggest that for dentin-resin bonds, minimizing smear layers and utilizing MMP inhibitors to prevent hybrid layer degradation are essential. In the case of resin-resin bonds, reversing blood contamination is possible, but preventing saliva contamination is more challenging, underscoring its critical importance during clinical procedures. Additionally, while pretreatment on ceramics has minimal impact on bond strength, the influence of specific colorings should be carefully considered in treatment planning. This comprehensive review highlights that although established practices recognize significant bond strength factors, ongoing research provides valuable insights to enhance the clinical experience for patients. Once confirmed through rigorous experimentation, these emerging findings should be swiftly integrated into dental practice to improve patient outcomes.

Study of Water Sorption in Methacryl-Based Polyhedral Oligomeric Silsesquioxane (POSS) Dental Composites Using Molecular Dynamics Simulations.

Methacrylate-based polyhedral oligomeric silsesquioxane (POSS) is one of the new composites used as a dental resin. Both monofunctional methacryl isobutyl POSS (MIPOSS) and multifunctional methacryl POSS (MAPOSS) are reported to be possible resins that possess the desired properties for using them as dental resins. Our group's previous comparative study on these two resins showed that the MAPOSS composite has superior mechanical properties compared with the MIPOSS composite. In this article, molecular dynamic simulations (MD simulations) are performed to study the water sorption in these two composites. Water sorption in dental composites can have several effects on the material properties, performance, and longevity of dental restorations. Water sorption in MAPOSS and MIPOSS composites is analyzed by studying the hydrogen bonding, cluster analysis, density projection calculations, and diffusion coefficient calculation of water molecules within the resin matrix. MD simulations results are further used to understand the interaction of water molecules with the resin matrix comprehensively, which governs the composite's mechanical properties. The water sorption study showed that the MAPOSS composite has less water sorption capacity than the MIPOSS composite. The practical significance of this study is to find properties that affect dental restoration and longevity, which can help in the design of better materials for dental applications.

The impact of occlusal forces on the longevity of restorations

The longevity of dental restorations like fillings, crowns, and bridges is critically influenced by occlusal forces exerted during biting and chewing. These forces vary among individuals based on diet, masticatory habits, and the structural soundness of the dental arch and can range from 11 to over 450 Newtons, depending on circumstances. The choice of restorative material is important for withstanding these forces. While amalgam is durable, modern dentistry has shifted towards aesthetic restoratives such as composite resins and ceramics. However, these materials respond differently to occlusal forces. Ceramics might fracture under excess load, whereas composite resins resist wear but can degrade over time due to other factors. Precision in restoration is crucial to preventing undue occlusal forces that might lead to restoration failure. Tools like T-scan assist in this precision. The manner and distribution of occlusal forces, along with the health of the periodontal ligament, are critical for restoration durability. Bruxism, a parafunctional habit, can significantly impact restorations, necessitating protective measures like occlusal splints and patient education. The interplay of occlusal forces and the chosen restorative material greatly affects the success and lifespan of dental restorations.

An Overview of Antibacterial Dental Restorative Materials

Antibacterial dental restorative materials (ADRM) have been developed to prevent or treat dental caries and other infections. Glass ionomer cements (GICs), composite resins, calcium hydroxide-based materials, mineral trioxide aggregate (MTA), bioactive glasses, silver-containing materials, quaternary ammonium compounds (QACs), chlorhexidine, nanoparticles, and photodynamic therapy (PDT) are common types of ADRMs. They have antibacterial properties due to the release of fluoride ions, QACs, silver nanoparticles, calcium and hydroxyl ions. ADRMs can prevent tooth decay, promote healing of pulp tissue and regenerate damaged tissues. Researchers are exploring new agents like nanoparticles and antimicrobial peptides to improve the antibacterial properties of ADRMs. PDT is a promising technology for improving the antibacterial properties of dental restorative materials. Antibacterial bioactive dental materials like bioactive glasses, calcium phosphate-based materials, hydroxyapatite-based materials, antibacterial peptides, and silver-containing materials have been developed to provide an additional layer of protection against infection and improve the longevity of dental restorations.

The Longevity and Clinical Performance of Direct and Indirect Restorations, Including Amalgam, Composite, Ceramic, and Metal Restorations

The longevity of dental restorations depends on patient-related, dentist-related, and material-related factors. Patientrelated factors include restoration size, chewing habits, oral hygiene, and systemic conditions. Strength, wear resistance, water tolerance, dimensional stability, and colour stability are all material-related variables. When deciding on a course of treatment, dentists must take these things into account. Since the 19th century, dental amalgam, which is composed of mercury, silver, tin, copper, and other metals, has been used effectively. Although it has limits in terms of tooth colour matching, it is appropriate for Class I and II restorations. Amalgam offers good load-bearing qualities, wear resistance, and tolerance for various clinical conditions. Safety concerns include the release of mercury vapor and the possibility of localized allergic reactions. Resin-based composites are esthetic and safe materials used for anterior and small to moderate-sized posterior fillings. Postoperative tooth sensitivity and shrinkage-related issues can occur, but improvements have minimized these problems. Adequate field control is essential for successful placement. Indirect restorative materials include all-ceramic and base metal casting alloys. All-ceramic restorations provide excellent aesthetics, high strength, and biocompatibility. However, they rely on resin-based cements and adhesives for retention, and allergies can occur. Base metal alloys offer an economical alternative and are effective for crown-and-bridge restorations. The choice of restorative materials depends on various factors, and dentists must consider the specific needs of each patient to achieve successful outcomes.

Fiber-Reinforced Composites in Dentistry: Enhancing structural integrity and aesthetic appeal

This review explored the recent advancements in fiber-reinforced composites (FRCs) within the context of restorative dentistry. Dental composites have undergone significant transformations, with FRCs emerging as a groundbreaking development at the intersection of aesthetics and mechanical performance. The objective of this review is to provide a comprehensive understanding of the innovative strategies employed in FRCs to address the challenges of polymerization shrinkage, wear resistance, mechanical strength, and aesthetics. FRCs, composed of fiber reinforcements strategically aligned within a resin matrix, offer enhanced flexural strength, fracture toughness, and wear resistance, essential for the longevity of dental restorations. The review further explored the dynamic relationship between fiber alignment and restoration design, highlighting the adaptability of FRCs for varied applications, from post and core restorations to bridges and splints. Through an intricate interplay of materials science and clinical demands, FRCs have revolutionized dental composites by seamlessly integrating form and function. This review underscores the transformative potential of FRCs in restorative dentistry, shedding light on the path to enhanced clinical outcomes and patient satisfaction

Smoothed quantile regression for censored residual life

We consider a regression modeling of the quantiles of residual life, remaining lifetime at a specific time. We propose a smoothed induced version of the existing non-smooth estimating equations approaches for estimating regression parameters. The proposed estimating equations are smooth in regression parameters, so solutions can be readily obtained via standard numerical algorithms. Moreover, the smoothness in the proposed estimating equations enables one to obtain a robust sandwich-type covariance estimator of regression estimators aided by an efficient resampling method. To handle data subject to right censoring, the inverse probability of censoring distribution is used as a weight. The consistency and asymptotic normality of the proposed estimator are established. Extensive simulation studies are conducted to validate the proposed estimator’s performance in various finite samples settings. We apply the proposed method to dental study data evaluating the longevity of dental restorations.

Enhancing the Stability of the Resin-Dentin Bonding Interface with Ag+- and Zn2+-Exchanged Zeolite A.

Enhancing the stability of the resin-dentin bonding interface via simultaneously improving the antibacterial, mechanical, and adhesive properties of a dental adhesive is the key to prolonging the longevity of dental restoration for caries treatment. Herein, we present the stabilization effect of Ag+- and Zn2+-exchanged zeolite A (denoted as Ag-A and Zn-A, respectively) on the resin-dentin bonding interface. Ag-A and Zn-A zeolites exhibited sustained ion release capability, outstanding biocompatibility to L929 cells (<2 mg/mL), and excellent antibacterial ability to Streptococcus mutans (minimum inhibitory concentration: 100 μg/mL for Ag-A and 200 μg/mL for Zn-A). One-step self-etching adhesives modified by Ag-A, Zn-A, or Ag-/Zn-A (1/1 in weight) zeolites with an ultralow loading of 0.2 wt % exhibited favorable antibacterial activity with the inhibition of biofilm formation by 70.33, 56.47, and 62.54%, respectively. Compared to the control group, Zn-A- and Ag-/Zn-A-modified adhesives significantly increased the wettability properties of the adhesive and the long-term resin-dentin bond strength (by ∼25%) after 5000 thermocycles of aging. The current data demonstrated that the introduction of 0.2 wt % Zn-A or Ag-/Zn-A into the adhesive remarkably enhanced the stability of the resin-dentin bonding interface. Our findings provide a new strategy to modify the dental adhesive for further optimizing the longevity of dental restorations for caries.

Promoting mineralization at biological interfaces Ex vivo with novel amelotin-based bio-nano complexes

Interfacial failure at the resin-dentin interface is a significant disadvantage of resin-based dental restoration. In this study, we created bio-inspired bio-nano complexes using the enamel protein amelotin (AMTN) or AMTN with an engineered collagen-binding site (AMTN-Col) to coat hydroxyapatite nanoparticles (HANP). The resulting nano-bio complexes, AMTN-HANP and AMTN-Col–HANP, were evaluated for their ability to promote collagen mineralization. Our study comprises three separate phases.In phase I, developing a method for functionalizing HANP with AMTN/AMTN-Col was explored. HANP were synthesized and characterized using TEM, SAED-TEM, XRD and ATR-FTIR. The nanoparticles were functionalized with AMTN or AMTN-Col. The successful coating of the nanoparticles with the proteins was confirmed using a TEM image of immunogold-labelled samples.In phase II of the study, the mineralization potential of the synthesized bio-nano complexes was studied using model systems consisting of simulated body fluid (SBF), polymerized collagen gels, and dentin disks prepared from human extracted molars. Mineral formation in SBF was recorded with a light scattering assay using a microplate reader on 8 replicates of each sample per study time point. Statistical analysis was performed using one-way ANOVA and the Tukey test. Significance was assigned at P ​< ​0.01. The extent of mineral formation on collagen gel and remineralization of demineralized dentin was studied with SEM. Accelerated mineral formation collagen mineralization of bio-nano complexes treated samples were observed in all model systems.In phase III of the study, the clinical utilization of AMTN/AMTN-Col coated HANP in bio-integration and enhancing the bond strength of a resin-based dental restoration and the dentin interface was investigated. The bio-nano complexes were applied as a pretreatment on dentin disks prepared from human extracted molars prior to the composite resin restoration. The micro-shear bond strength test was done on 8 samples per treatment group (a total of 32 samples). Statistical analysis on shear bond strength was performed using one-way ANOVA and the Tukey test. Significance was assigned at P ​< ​0.01. Shear bond strength values indicated that pretreatment of dentin with the bio-nano complexes before adhesive application significantly improved shear bond strength.ConclusionWe have shown that AMTN based bio-nano complexes promote mineral formation on collagenous interfaces. Our findings can be the basis of new bio-inspired, bio-nano materials that may improve dental restoration longevity by enhancing the stability and integrity of the dentin-composite resin interface.

Host Response to Adhesive Restorative Dental Treatment.

When dental caries or erosive tooth wear lesions progress into dentin, the speed of their progression into the pulp will be modulated in part by the physiology of the dentin-pulp complex. In some individuals, this physiology allows for a quicker progression of the lesions. Research on the longevity of dental restorations has focused almost solely on the technical aspects needed to improve the adhesive properties and longevity of the restorations. Studying the possible individual variations in the quality of dental tissue may enable further developments targeting specific dental tissue phenotypes. This chapter discusses the results of the initial studies exploring phenotypes that consider manifestations of deep caries or erosive lesions in dentin.

Methacrylate-functionalized proanthocyanidins as novel polymerizable collagen cross-linkers — Part 2: Effects on polymerization, microhardness and leaching of adhesives

ObjectiveThe aim of the study was to investigate the effects of a novel polymerizable collagen cross-linker methacrylate-functionalized proanthocyanidins (MAPA) on the polymerization, microhardness and leaching of a HEMA-based experimental dental adhesive system. MethodsThree MAPAs were synthesized using different methacrylate (MA) to proanthocyanidins (PA) feeding ratios of 1:2, 1:1, and 2:1 to obtain MAPA-1, MAPA-2, and MAPA-3, respectively. The resulting three MAPAs and PA were added to an experimental adhesive formulated with HEMA and a tri-component photoinitiator system (0.5 wt% CQ/EDMAB/DPIHP) at 1%, 5% and 10% MAPA or PA concentrations (wt%). The adhesive polymerization kinetics was measured continuously in real-time for 10 min using a Fourier-transform infrared spectroscopy (FTIR) with an attenuated total reflectance (ATR) accessory. Degree of conversion (DC) and Vickers microhardness (MH) of cured adhesives were measured at 72 h post-cure. The leaching of cured adhesives in DI water was monitored using UV–vis spectrophotometer. Statistical analysis was performed using one-way and two-way ANOVA, Tukey’s (p < 0.05). ResultsThe adhesive formulations with 1%, 5% and 10% MAPAs-1, -2, -3 all generated higher rate of polymerization and 10-min DC than the formulations with PA at the same concentrations. At 72 h post-cure, the adhesive formulation with 5% MAPA-2 exhibited significantly higher DC (99.40%) and more than doubled MH (18.93) values than the formulation with 5% PA (DC = 89.47%, MH = 8.41) and the control (DC = 95.46%, MH = 9.33). Moreover, the cured adhesive with 5% MAPA-2 demonstrated significantly reduced PA leaching in comparison with cured adhesive with 5% PA. SignificanceSynthesized MAPA is a novel class of polymerizable collagen cross-linker that not only stabilizes dentin collagen via its PA component, but also improves polymerization, mechanical properties and stability of HEMA-based adhesives via its MA component. By inheriting the benefit while overcoming the drawback of PA, MAPA offers a revolutionary solution for improved bond-strength and longevity of dental restorations.

Repair bond strength of dental computer-aided design/computer-aided manufactured ceramics after different surface treatments.

To evaluate the microtensile bond strength of four dental computer-aided design/computer-aided manufactured (CAD/CAM) ceramics after application of four different surface treatments. Four dental CAD/CAM ceramics were tested: feldspathic ceramic (VITABLOCKS-Mark II), polymer-infiltrated ceramic network (VITA ENAMIC), zirconia-reinforced lithium silicate (VITA SUPRINITY), and yttria-stabilized zirconia (VITA YZ T). Four surface treatments were applied: no treatment, 5% hydrofluoric acid-etching, airborne particle abrasion, and tribochemical silica coating. The ceramic blocks were repaired with nanohybrid composite (Tetric N-Collection). Sixteen test groups of 12 specimens were prepared. After thermocycling, microtensile bond testing was performed. The microtensile strengths values were statistically analyzed using two-way analysis of variance and Tukey's post-hoc test. Repaired feldspathic and resin polymer-infiltrated ceramic network ceramics demonstrated superior microtensile bond strengths compared to zirconia-reinforced lithium silicate and yttria-stabilized zirconia. Etched feldspathic and polymer-infiltrated ceramic network ceramics had higher bond strength than the untreated groups. Surface treatments did not affect the bond strength of zirconia-reinforced lithium silicate and yttria-stabilized zirconia with the exception of etching, which reduced the bond strength of yttria-stabilized zirconia. Feldspathic ceramic and polymer-infiltrated ceramic network were repaired with dental composite after surface etching with hydrofluoric acid. Repair of zirconia-reinforced lithium silicate and yttria-stabilized zirconia did not demonstrate promising results. Repair of feldspathic ceramic and polymer-infiltrated ceramic network restorations may be a cost-effective means to promote the longevity of dental restorations. However, zirconia and zirconia-reinforced lithium disilicate restorations do not offer such an option.

Structuring, reuse and analysis of electronic dental data using the Oral Health and Disease Ontology

BackgroundA key challenge for improving the quality of health care is to be able to use a common framework to work with patient information acquired in any of the health and life science disciplines. Patient information collected during dental care exposes many of the challenges that confront a wider scale approach. For example, to improve the quality of dental care, we must be able to collect and analyze data about dental procedures from multiple practices. However, a number of challenges make doing so difficult. First, dental electronic health record (EHR) information is often stored in complex relational databases that are poorly documented. Second, there is not a commonly accepted and implemented database schema for dental EHR systems. Third, integrative work that attempts to bridge dentistry and other settings in healthcare is made difficult by the disconnect between representations of medical information within dental and other disciplines’ EHR systems. As dentistry increasingly concerns itself with the general health of a patient, for example in increased efforts to monitor heart health and systemic disease, the impact of this disconnect becomes more and more severe.To demonstrate how to address these problems, we have developed the open-source Oral Health and Disease Ontology (OHD) and our instance-based representation as a framework for dental and medical health care information. We envision a time when medical record systems use a common data back end that would make interoperating trivial and obviate the need for a dedicated messaging framework to move data between systems.The OHD is not yet complete. It includes enough to be useful and to demonstrate how it is constructed. We demonstrate its utility in an analysis of longevity of dental restorations. Our first narrow use case provides a prototype, and is intended demonstrate a prospective design for a principled data backend that can be used consistently and encompass both dental and medical information in a single framework.ResultsThe OHD contains over 1900 classes and 59 relationships. Most of the classes and relationships were imported from existing OBO Foundry ontologies. Using the LSW2 (LISP Semantic Web) software library, we translated data from a dental practice’s EHR system into a corresponding Web Ontology Language (OWL) representation based on the OHD framework. The OWL representation was then loaded into a triple store, and as a proof of concept, we addressed a question of clinical relevance – a survival analysis of the longevity of resin filling restorations. We provide queries using SPARQL and statistical analysis code in R to demonstrate how to perform clinical research using a framework such as the OHD, and we compare our results with previous studies.ConclusionsThis proof-of-concept project translated data from a single practice. By using dental practice data, we demonstrate that the OHD and the instance-based approach are sufficient to represent data generated in real-world, routine clinical settings. While the OHD is applicable to integration of data from multiple practices with different dental EHR systems, we intend our work to be understood as a prospective design for EHR data storage that would simplify medical informatics. The system has well-understood semantics because of our use of BFO-based realist ontology and its representation in OWL. The data model is a well-defined web standard.

The adverse effects of radiotherapy on the structure of dental hard tissues and longevity of dental restoration

Purpose: The main goal of this study was to evaluate the impact of different ionizing radiation doses on the mineral (carbonate/phosphate ratio, crystallinity index [CI]) and organic (amide III/phosphate, amide I sub-band ratios) structures, as well as the microhardness, of enamel and dentin, along with their influence on the bonding strength stability of the etch-and-rinse (ER) and self-etch (SE) dental adhesive strategies.Materials and methods: Enamel and dentin human tissue specimens were irradiated (with 0, 20, 40, and 70 Gy radiation doses, respectively) and sectioned to perform an attenuated total reflection-Fourier transform IR spectroscopy assay (ATR-FTIR) and the Vickers microhardness (VHN) test to conduct a biochemical and biomechanical evaluation of the tissues. Regarding the adhesive properties, restored enamel and dentin specimens exposed to the same radiation doses were submitted to microshear bond strength (μSBS) tests for enamel in immediate time (IM) and to microtensile bond strength (μTBS) tests after for IM and 12-month (12 M) period of time, Mann–Whitney U tests were implemented, using the ATR-FTIR data for significant differences (α < 0.05), and three- and two-way analyses of variance, along with post-testing, were performed on the μTBS and μSBS data (MPa), respectively (Tukey post hoc test at α = 0.05).Results: The ATR-FTIR results showed a significant decrease (p < .05) in the amide III/phosphate ratio after 20 Gy for the enamel and after 40 Gy for the dentin. The CI was significantly reduced for both tissues after a dose of 70 Gy (p < .05). All radiation doses significantly decreased microhardness values, relative to the respective enamel and dentin controls (p < .05). In both tissues and adhesive strategies, the decrease in bond strength was influenced by ionizing radiation starting from 40 Gy. The ER strategy showed high percentages of enamel cohesive failure. In general, ER in both tissues showed greater and more stable bond strength than SE against increased radiation doses and long term.Conclusions: It is possible to conclude that structural alterations of enamel and dentin are generated by all radiation doses, decreasing the microhardness of dental hard tissues and influencing bond strength over time, starting at 40 Gy radiation dose. The etch-and-rinse strategy demonstrates better adhesive performance but generates cohesive fractures in the enamel.

Research Progress on All Ceramic Zirconia Core/Veneer Interface: A Review

The application of veneered zirconia system in clinical has last for few decades due to the excellent aesthetic performance. It was reported in many cases that porcelain delamination occurred in the interface between the zirconia infrastructure and veneer ceramics. There were many works have been carried out to improve the bond strength of interface. Most of the studies focused on the influence factors that affected the longevity of dental restoration. There existed different points of view both in vitro and in vivo. Hence, this review mainly focuses on veneered zirconia system and some interesting controversial findings that may lead to dental restoration failure. Furthermore, it was also found that the next generation of zirconia (such as monolithic zirconia, self-glazed zirconia) have brought the challenge to veneered zirconia system.

The use of clays for chlorhexidine controlled release as a new perspective for longer durability of dentin adhesion.

The adhesive systems have the function to establish the connection between the restorative material and dental tissue, therefore it is of fundamental importance, because failures in the adhesive interface can reduce the life of a dental restoration. This study investigated the possibility of using the adhesive layer as a chlorhexidine modified release system evaluating their impact on the properties of these systems as well as evaluating the impact of these systems on immediate and post-aging dentin adhesion. Were used a matrix with BisGMA, UDMA, HEMA and TEGDMA copolymer and clay particles (Dellite 67G); associated with a chlorhexidine and a camphorquinone photoinitiator system. The properties of these systems were evaluated by the XRD, FTIR spectrophotometer, flexural strength, elasticity modulus, drug release, enzymatic inhibition and dentin adhesion resistance. The presence of the clay can raise the mechanical properties of the adhesive systems engendering a more resistant hybrid layer and led to a more sustained release of chlorhexidine in the systems, allowing a longer effective period of MMP-2 inhibition. The hypothesis that the addition of clays as release modulators could increase the effectiveness of these drugs in inhibiting the dentin's MPPs and consequently enhancing the adhesive durability was confirmed. These results indicate that the controlled release of chlorhexidine is able to reduce the process of loss of adhesion presenting itself as a promising system to increase the longevity of dental restorations.

Clinical criteria for the assessment of dental restoration

It is necessary to adopt a standard assessment system to evaluate the quality of restorations in clinical trials on operative dentistry. A new clinical assessment system for dental restorations was proposed in 2007. The crireria is based on three categories (aesthetic, functional and biological) among which includes 16 indexes such as restoration fractures and retention, surface luster, marginaladaptation, secondary carious, postoperative sensitivity and so on. It has been officially approved by World Dental Federation (FDI). Due to the practicability, sensitivity and standardization, more and more clinical trials use FDI criteria to assess the quality and longevity of dental restorations.