Dental materials: 1997 literature review.

This review of the published literature on dental materials for the year 1997 has been compiled by the Dental Materials Panel of UK. It continues a series of annual reviews started in 1973. Emphasis has been placed upon publications, which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, ceramometallic restorations and resin-bonded bridges, ceramics, denture base resins and soft lining materials, impression materials, dental implant materials, orthodontic materials, biomechanics and image processing, resin composites, and casting investment materials and waxes). Three hundred and thirty three articles have been reviewed.     

A comparative life cycle assessment of dental restorative materials

ObjectivesDifferent types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation is to determine, through a comparative cradle-to-gate life cycle assessment, the environmental impacts of three direct-placement dental restorative materials (DRMs) and their associated packaging.MethodsThree direct-placement dental materials; dental amalgam, resin-based composite (RBC) and glass polyalkenoate cements (GIC) are assessed using primary data from a manufacturer (SDI Limited, Australia). The functional unit consisted of ‘one dental restoration’ of each restorative system under investigation: 1.14 g of dental amalgam; 0.25 g of RBC (plus the adhesive = 0.10 g); and 0.54 g of GIC. The system boundary per restoration included the raw materials and their associated packaging materials for each DRM together with the processing steps for both the materials and packaging. The environmental impacts were assessed using an Egalitarian approach under the ReCiPe method using Umberto software and the Ecoinvent database. Nine different impact categories were used to compare the environmental performance of these materials.ResultsDental amalgam had the highest impact across most of the categories, but RBC had the highest Global Warming Potential. The highest sources of the environmental impacts for each restorative material were: Amalgam, derived from material use; RBC, derived from energy use in processing material and packaging material; GIC, derived from material and energy use for packaging.SignificanceLess intensive energy sources or more sustainable packaging materials can potentially reduce the impacts associated with RBC and GIC thus making them suitable alternatives to dental amalgam.     

Impact of erosive conditions on tooth-colored restorative materials

Objectives

To give an overview of the impact of erosive conditions on the behavior of tooth-colored restoratives and performance of dental adhesives.

Methods

Acid-induced erosive lesions of enamel and dentin often need restorative procedures for rehabilitation. Nowadays, mostly tooth-colored restoratives (ceramics or resin composites), which are adhesively fixed to the dental substrate are used for this purpose. In some cases it might be necessary to seal the exposed dentin before achieving this goal in order to combat hypersensitivities and to protect those teeth from further erosive and abrasive loss. Moreover, it is conceivable that patients will fall back into their old “erosive behavior” after the application of restoratives. The following overview describes in how far intra-oral erosive conditions might affect the integrity of restorative materials, such as composite resins and ceramics, or of dentin sealants. Additionally, the use of erosively altered enamel and dentin as substrate for adhesive technologies is elucidated.

Results

In the literature, information of the behavior of tooth-colored restoratives under still persisting erosive conditions are limited and mostly based on in vitro-studies. There is information that the adhesion of dental adhesives to eroded dentin is compromised as compared to regular dentin. The impact of erosive conditions relevant for the oral cavity on ceramics and resin composites seems to be rather low, although only few clinical studies are available.

Significance

The review showed that erosive conditions might have only little impact on behavior of tooth-colored restorative materials, such as composites and ceramics. Dentin sealants also seem to be rather resistant against erosive conditions and might therefore serve as an intermediary treatment option for exposed dentin surfaces. The adhesion of dentin adhesives to eroded dentin might be increased by mechanical pre-treatment of the substrate, but needs further investigation.     

Changes in color and contrast ratio of resin composites after curing and storage in water

PurposeTo verify the color change and contrast ratio of resin composites after curing and after 30 days of storage in water.MethodsDentin A2 shades of different light-cured dental resin composites (Vittra APS, FGM, Brazil; Z350 XT, 3M ESPE, EUA; Tetric N-Ceram, Ivoclar Vivadent, Liechtenstein, and Charisma Diamond, Heraeus Kulzer, Germany) were tested. Ten rounded specimens (8 mm × 2 mm) were prepared for each material. Reflectance for all samples was obtained using a spectrophotometer (Minolta CM 3700d, Konica Minolta, Japan) before curing, immediately after curing, and after 30 days of storage in water. The color change (ΔE*lab) and contrast ratio (CR) data were analyzed using a one-way analysis of variance with Tukey's and paired t-tests (α = 1%).ResultsFor all materials tested, significant color changes were noticeable after curing and after 30 days in water (p < 0.01). Significant changes in the CR values before curing, after curing, and 30 days of storage in water were observed in the resin composites investigated (p < 0.01) except for Z350 (p > 0.01).ConclusionThe CR values and color changes after curing and 30 days of storage in water varied depending on the material tested. This study corroborates the clinical practice of curing a small amount of unpolymerized resin composite on the tooth surface to select the desired shade before undertaking esthetic restorative procedures.     

Effect of porous glass–ceramic fillers on mechanical properties of light-cured dental resin composites

ObjectivesThe aim of this work was to study the effect of porous particles on the mechanical properties of dental resin composites.MethodsTwo kinds of glass–ceramic powders with different calcium–mica to fluorapatite ratio were used as inorganic fillers for light-cured dental resin composites. The glass–ceramic particles were etched to introduce porous structures. The microstructures of particles and the fractography of dental composites were observed using SEM/EDS. The crystalline phases in the fillers were determined by XRD. The specific surface areas (SBET) of porous fillers were tested to show the degree of porosity. 6 samples were prepared for each bending strength test, which was conducted in a Mechanical Testing System.ResultsThe results show that the bending strength does not vary monotonically with the porosity of the particles. For the glass–ceramics with a high nominal calcium–mica to fluorapatite ratio, the dental resin filled with porous particles has a higher strength than that filled with dense particles; however, for the glass–ceramics with a low nominal calcium–mica to fluorapatite ratio, the dental resin filled with porous particles has a lower strength.SignificanceThe study indicates that the porosity itself is not a decisive factor for strengthening of dental resin composites. The composition of the glass–ceramic particles and the porous structure are also essential factors influencing the mechanical strength. The investigation on the effect of porous glass–ceramic fillers will provide more understanding on the mechanical properties of dental resin composites and will help with the design of new dental restorative materials.     

Dental materials: 1983 literature review part 2

In this second part of the review of 1983 literature on dental materials, the following topics are discussed: impression, model die and mould materials, denture-base polymers, aspects of adhesion and fissure sealants. The following restorative materials are also considered: composites, cements, endodontic materials and dental amalgam.     

A review and current state of autonomic self-healing microcapsules-based dental resin composites

ObjectiveThis study systematically reviews the literature on self-healing microcapsule technology and evaluates the biocompatibility of self-healing microcapsules and the efficiency of crack repair within resin-based dental composites.MethodsAn electronic search was carried out using the following databases: MedLine (PubMed), Embase, the Cochrane Library and Google Scholar. All titles and abstracts of the articles and patents found were analysed and selected according to the eligibility criteria. Only studies published in English were included; the outcomes sought for this review were dental resin composites with self-healing potential. There were no restrictions on the type of self-healing system involved in dental resin composites.ResultsThe search yielded 10 studies and 2 patents involving self-healing approaches to dental resin composites. According to the current literature on self-healing dental resin composites, when a crack or damage occurs to the composite, microcapsules rupture, releasing the healing agent to repair the crack with a self-healing performance ranging from 25% to 80% of the virgin fracture toughness.SignificanceSelf-healing strategies used with resin composite materials have, to date, been bioinspired. So far, self-healing microcapsule systems within dental composites include poly urea-formaldehyde (PUF) or silica microcapsules. The main healing agents used in PUF microcapsules are DCPD monomer and TEGDMA-DHEPT, with other agents also explored. Silica microcapsules use water/polyacid as a healing agent. All self-healing systems have shown promising results for self-repair and crack inhibition, suggesting a prolonged life of dental composite restorations. More investigations and mechanical enhancements should be directed toward self-healing technologies in dental resin composites.     

Dental restorative composite materials: A review

BackgroundThis review article discusses the effect of reinforcements in the parent dental restorative materials that results in enhanced performance in real-time situations.HighlightThe review article includes the details of the properties of different reinforced dental composite materials such as mechanical strength, thermal properties, physical/chemical properties, tribological performance.ConclusionIt revealed that nanofiller particles enhance the properties of various dental composite materials. The hybrid dental composites also contribute significantly in increasing the mechanical and tribological properties. A silane-treated filler improved the dental composite bonding strength.     

Is the radiopacity of CAD/CAM aesthetic materials sufficient?

ObjectivesThis study was designed to investigate CAD/CAM restorative blocks and other resin-based materials by (i) determining their chemical composition, (ii) comparing their radiopacity and (iii) correlating their radiopacity with specimen thickness.MethodsDisk specimens, of 1and 2 mm thickness (n = 3), were prepared from five CAD/CAM and six resin-based composites (RBCs). The CAD/CAM resin-composites included aesthetic types: CeraSmart (CS), Grandio Blocs (GB), Lava Ultimate (LU), plus a polymer infiltrated ceramic Vita Enamic (VE), and a feldspathic ceramic Vita Mark II (VM II). The six RBCs were for different clinical applications: direct filling, flowable, bulk fill, base and two luting cements. The specimens were radiographed alongside an aluminium step wedge and a tooth section. Digital images were analysed, and the radiopacity of each specimen was determined according to ISO 1311/2014. Statistical analyses of radiopacity, expressed as mm Al (n = 15), were carried out using the Kruskal-Wallis test followed by pairwise comparisons (α = 0.05).ResultsRadiopacities of CAD/CAM materials were, in ascending order, VE, VM II, CS, LU, and GB. At 1 mm thickness, the radiopacities of all CAD/CAM specimens were matching or slightly lower than enamel. At 2-mm thickness, the resin composite blocks were significantly more radiopaque than the ceramics VE and VM II (p < 0.0001). No statistically significant differences in radiopacity were detected between the 1-mm thick infiltrated ceramic, enamel, dentin and various resin composites except for filling and bulk fill types. The radiopacity of polymer-infiltrated ceramics was low despite the presence of radiopacifying elements and high filler content.SignificanceIdentifying thin restorations in standard radiographs is necessary with the development and expanded application of ‘digital’ dental materials in restorative treatment. This study confirmed the joint influence of composition and thickness on radiopacity. CAD/CAM restorative materials showed thickness-dependant radiopacity. But polymer-infiltrated ceramics were fairly radiolucent. There is a need to revisit radiopacity requirements for CAD/CAM restorative materials.     

Dental biomaterials: where are we and where are we going?

This article reviews the current state of the art for restorative biomaterials by examining the roles of 1) truly biological biomaterials, with respect to the "near-future" of five to ten years, 2) traditional synthetic biomaterials, and 3) performance outcomes for biomaterials. Biological biomaterials are discussed in terms of tissue engineering and stem cell research, self-assembling system opportunities, and nanotechniques or technologies. Future developments for major areas of synthetic biomaterials are considered for bonding systems, composites, VLC curing, ceramics, and cements. Performance outcomes are discussed for all biomaterials in terms of safety, efficacy, and longevity of materials.     

Dental materials: 1975 literature review

This paper reviews the work on dental materials published in 1975. The main areas reviewed are dental amalgam, casting alloys, polymeric materials including composites and fissure sealants, impression materials, ceramics, dental cements of all types, dental implants and dental biomechanics.     

Future perspectives of resin-based dental materials

ObjectiveThis concise review and outlook paper gives a view of selected potential future developments in the area of resin-based biomaterials with an emphasis on dental composites.MethodsA selection of key publications (1 book, 35 scientific original publications and 1 website source) covering the areas nanotechnology, antimicrobial materials, stimuli responsive materials, self-repairing materials and materials for tissue engineering with direct or indirect relations and/or implications to resin-based dental materials is critically reviewed and discussed. Connections between these fields and their potential for resin-based dental materials are highlighted and put in perspective.ResultsThe need to improve shrinkage properties and wear resistance is obvious for dental composites, and a vast number of attempts have been made to accomplish these aims. Future resin-based materials may be further improved in this respect if, for example nanotechnology is applied. Dental composites may, however, reach a completely new quality by utilizing new trends from materials science, such as introducing nanostructures, antimicrobial properties, stimuli responsive capabilities, the ability to promote tissue regeneration or repair of dental tissues if the composites were able to repair themselves.SignificanceThis paper shows selected potential future developments in the area of resin-based dental materials, gives basic and industrial researchers in dental materials science, and dental practitioners a glance into the potential future of these materials, and should stimulate discussion about needs and future developments in the area.     

Gazing into the future of esthetic restorative materials.

This article outlines the authors' perceptions of the future of esthetic dental restorative materials such as composites, glass ionomer cements, pit and fissure sealants and laboratory fabricated resin.     

Dental materials: 1979 literature review Part I

This paper, which is presented in two parts, reviews the work on dental materials published in 1979. Included in Part I are sections on dental biomechanics, fissure sealants, cements, amalgam, composite filling materials, endodontic materials and, for the first time, microleakage. Part II will include sections on impression materials, model, die and investment materials, waxes, acrylic resins, denture base polymers, soft lining materials and tissue conditioners, cast and' wrought dental alloys, ceramics, implants and, finally, corrosion.     

Sol-gel bioactive glass containing biomaterials for restorative dentistry: A review

ObjectiveBioactive glasses (BAGs) have been researched extensively for dentistry due to their favourable biocompatibility and hard tissue bonding ability. However, the specific application of BAGs produced through sol-gel synthesis in restorative dentistry has not been reviewed previously. This review provides a comprehensive account of the principles behind sol-gel derived BAGs and their investigation for dental tissue restoration materials.MethodsA search for in vitro and in vivo studies was performed using the databases Web of Science®, Medline®, Scopus® and Google Scholar®. Articles published over the past 20 years were selected and data on the BAG composition and morphology was extracted. Analysis of the effect of specific BAG additives on the properties of experimental dental materials was also performed.ResultsA majority of BAG particles investigated were spheres ranging in size from 5 nm to ~650 µm. Sol-gel BAGs are mainly applied in the treatment of hypersensitive dentine and for pulp-dentine tissue engineering, while a handful have been used in target drug delivery. BAG fillers are promising additives that result in improved biological properties, antibacterial effects, hardness, acid buffering and remineralization. Unfortunately, some detrimental effects on optical properties have been observed with BAG addition. Additionally, in vivo data, investigations into radiopacity and standardization of test protocols are identified as areas for improvement and further studies.SignificanceFuture work should consider the pertinent issues raised in order to improve the quality of available data and expand knowledge in this area of dental biomaterials research and development.     

Influence of surface modified dental implant abutments on connective tissue attachment: A systematic review

ObjectiveDetermine whether surface modified prosthetic abutments for dental implants influence connective tissue attachment to the implant-abutment system.DesignA systematic review was conducted using the MEDLINE-PubMed database, with two independent reviewers filtering the titles and abstracts. Two reviewers assessed all potentially relevant articles. An assessment was carried out on the level of evidence of the research according to the guidelines of the Oxford Centre for Evidence-Based Medicine (OCEBM).ResultsAfter an initial search, 109 potentially relevant articles were found. After reading the titles and abstracts, 99 articles were excluded because the surface treatment was limited to the implant and not to the abutment, or because different materials were analysed instead of surface treatments; 28 were also duplicate articles. An additional 6 research studies were included that were of interest and were found by reading the references of the included articles. The studies included are: 7 in vitro studies, 5 experimental studies in animals, 2 clinical trials in humans and 2 clinical cases.ConclusionSurface modification for prosthetic abutments on dental implants can achieve connective tissue attachment to the abutment; however, more studies should be conducted in humans to obtain more and better evidence of these results.     

Dental materials: 1979 literature review Part II

This paper, which is presented in two parts, reviews the work on dental materials published in 1979. Included in Part II are sections on impression materials, model, die and investment materials, waxes, acrylic resins, denture base polymers, soft lining materials and tissue conditioners, cast and wrought dental alloys, ceramics, implants and, finally, corrosion. Part I included sections on dental biomechanics, fissure sealants, cements, amalgam, composite filling materials, endodontic materials and microleakage.     

Next-generation biomaterials for dental pulp tissue immunomodulation

ObjectivesThe current standard for treating irreversibly damaged dental pulp is root canal therapy, which involves complete removal and debridement of the pulp space and filling with an inert biomaterial. A regenerative approach to treating diseased dental pulp may allow for complete healing of the native tooth structure and enhance the long-term outcome of once-necrotic teeth. The aim of this paper is, therefore, to highlight the current state of dental pulp tissue engineering and immunomodulatory biomaterials properties, identifying exciting opportunities for their synergy in developing next-generation biomaterials-driven technologies.MethodsAn overview of the inflammatory process focusing on immune responses of the dental pulp, followed by periapical and periodontal tissue inflammation are elaborated. Then, the most recent advances in treating infection-induced inflammatory oral diseases, focusing on biocompatible materials with immunomodulatory properties are discussed. Of note, we highlight some of the most used modifications in biomaterials’ surface, or content/drug incorporation focused on immunomodulation based on an extensive literature search over the last decade.ResultsWe provide the readers with a critical summary of recent advances in immunomodulation related to pulpal, periapical, and periodontal diseases while bringing light to tissue engineering strategies focusing on healing and regenerating multiple tissue types.SignificanceSignificant advances have been made in developing biomaterials that take advantage of the host’s immune system to guide a specific regenerative outcome. Biomaterials that efficiently and predictably modulate cells in the dental pulp complex hold significant clinical promise for improving standards of care compared to endodontic root canal therapy.     

Ceramic dental biomaterials and CAD/CAM technology: State of the art

PurposeCeramics are widely used as indirect restorative materials in dentistry because of their high biocompatibility and pleasing aesthetics. The objective is to review the state of the arts of CAD/CAM all-ceramic biomaterials.Study selectionCAD/CAM all-ceramic biomaterials are highlighted and a subsequent literature search was conducted for the relevant subjects using PubMed followed by manual search.ResultsDevelopments in CAD/CAM technology have catalyzed researches in all-ceramic biomaterials and their applications. Feldspathic glass ceramic and glass infiltrated ceramic can be fabricated by traditional laboratory methods or CAD/CAM. The advent of polycrystalline ceramics is a direct result of CAD/CAM technology without which the fabrication would not have been possible.ConclusionsThe clinical uses of these ceramics have met with variable clinical success. Multiple options are now available to the clinicians for the fabrication of aesthetic all ceramic restorations.     

Longevity of composite restorations is definitely not only about materials

ObjectivesThis review study provides an overview of factors that influence the longevity of all types of direct resin composite restorations.MethodsA systematic search was performed in PubMed, Scopus, and Web of Science databases for articles reporting data from primary longitudinal clinical studies on composite longevity published 2011–2021. Prospective or retrospective studies with restorations in permanent dentition, with follow-up periods of at least 5 years were included.ResultsIn total, 33 articles were included with different study designs, practice settings, datasets, countries of origin, and sample sizes. Annual failure rates of restorations ranged from 0.08% to 6.3%. Survival rates varied between 23% and 97.7%, success rates varied between 43.4% and 98.7%. Secondary caries, fractures, and esthetic compromise were main reasons for failures. Risk factors for reduced restoration durability included patient-level factors (e.g., caries risk, parafunctional habits, number of check-ups per year, socioeconomic status), dentist factors (different operators, operator’s experience), and tooth/restoration factors (endodontic treatment, type of tooth, number of restored surfaces). Patient gender and the composite used generally did not influence durability.SignificanceA number of risk factors are involved in the longevity of composite restorations. Differences between composites play a minor role in durability, assuming that materials and techniques are properly applied by dentists. Patient factors play a major role in longevity. The decision-making process implemented by dentists relative to the diagnosis of aging or failed restorations may also affect the longevity of restorations. Clinicians should treat patients comprehensively and promote a healthy lifestyle to ensure longevity.