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Journal of Prosthodontics : Official... Feb 2017Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer-aided manufacturing. Research on... (Review)
Review
Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer-aided manufacturing. Research on material for use in additive manufacturing is ongoing, and a wide variety of materials are being used or developed for use in dentistry. Some materials, however, such as cobalt chromium, still lack sufficient research to allow definite conclusions about the suitability of their use in clinical dental practice. Despite this, due to the wide variety of machines that use additive manufacturing, there is much more flexibility in the build material and geometry when building structures compared with subtractive manufacturing. Overall additive manufacturing produces little material waste and is energy efficient when compared to subtractive manufacturing, due to passivity and the additive layering nature of the build process. Such features make the technique suitable to be used with fabricating structures out of hard to handle materials such as cobalt chromium. The main limitations of this technology include the appearance of steps due to layering of material and difficulty in fabricating certain material generally used in dentistry for use in 3D printing such as ceramics. The current pace of technological development, however, promises exciting possibilities.
Topics: Computer-Aided Design; Dental Materials; Dental Prosthesis Design; Humans; Printing, Three-Dimensional
PubMed: 27662423
DOI: 10.1111/jopr.12510 -
Operative Dentistry Nov 2021To compare the ability of two calcium-releasing restorative materials to inhibit root dentin demineralization in an artificial caries model.
OBJECTIVE
To compare the ability of two calcium-releasing restorative materials to inhibit root dentin demineralization in an artificial caries model.
METHODS AND MATERIALS
Preparations were made at the cementum-enamel junction of extracted human molars (40, n=10/material) and restored with two calcium-releasing materials (Experimental composite, Pulpdent Corporation and Cention N, Ivoclar Vivadent), a resin composite (Filtek Supreme Ultra, 3M Oral Care), and a resin-modified glass ionomer (RMGI) (Fuji II LC, GC). All materials (other than the RMGI) were used with an adhesive (Scotchbond Universal Adhesive, 3M Oral Care) in the self-etch mode, which was light cured for 10 seconds. All restorative materials were light cured in 2-mm increments for 20 seconds and then finished with a polishing disc. Teeth were incubated (37°C) for 24 hours in water. An acid-resistant varnish was painted onto the teeth around the restoration, leaving a 2-mm border of uncovered tooth. A demineralization solution composed of 0.1 M lactic acid, 3 mM Ca3(PO4)2, 0.1% thymol, and NaOH (to adjust pH=4.5), and a remineralization solution composed of 1.5 mM Ca, 0.9 mM P, and 20 mM Tris(hydroxymethyl)-aminomethane (pH=7.0) were prepared. Specimens were placed in the demineralization solution for 4 hours, followed by the remineralization solution for 20 hours and cycled daily for 30 days. The specimens were embedded, sectioned into 100-μm sections, and the interface between the restorative material and root dentin was viewed with polarized light microscopy. A line was drawn parallel with the zone of demineralization for each tooth. The area of "inhibition" (defined as the area external to the line) or "wall lesion" (defined as the area internal to the line) was measured with image evaluation software. Areas of inhibition were measured as positive values, and areas of wall lesions were measured as negative areas.
RESULTS
A one-way analysis of variance (ANOVA) found significant differences between materials for "inhibition/wall lesion" areas in root dentin (p<0.001). Tukey post hoc analysis ranked materials (μm2, mean ±SD): Fuji II LC (5412±2754) > Cention N (2768±1576) and experimental composite (1484±1585) > Filtek Supreme Ultra (-1119±1029).
CONCLUSION
The experimental composite and Cention N materials (used with an adhesive) showed net areas of inhibition greater than a reference resin composite, albeit at a lower level than a reference RMGI material (used with no adhesive).
Topics: Calcium; Composite Resins; Dental Enamel; Dental Materials; Dental Restoration, Permanent; Glass Ionomer Cements; Humans; Tooth Demineralization
PubMed: 35507898
DOI: 10.2341/20-074-L -
Journal of the Mechanical Behavior of... Apr 2019An investigation is made of wear mechanisms in a suite of dental materials with a ceramic component and tooth enamel using a laboratory test that simulates clinically...
An investigation is made of wear mechanisms in a suite of dental materials with a ceramic component and tooth enamel using a laboratory test that simulates clinically observable wear facets. A ball-on-3-specimen wear tester in a tetrahedral configuration with a rotating hard antagonist zirconia sphere is used to produce circular wear scars on polished surfaces of dental materials in artificial saliva. Images of the wear scars enable interpretation of wear mechanisms, and measurements of scar dimensions quantify wear rates. Rates are lowest for zirconia ceramics, highest for lithium disilicate, with feldspathic ceramic and ceramic-polymer composite intermediate. Examination of wear scars reveals surface debris, indicative of a mechanism of material removal at the microstructural level. Microplasticity and microcracking models account for mild and severe wear regions. Wear models are used to evaluate potential longevity for each dental material. It is demonstrated that controlled laboratory testing can identify and quantify wear susceptibility under conditions that reflect the essence of basic occlusal contact. In addition to causing severe material loss, wear damage can lead to premature tooth or prosthetic failure.
Topics: Ceramics; Dental Enamel; Dental Materials; Humans; Materials Testing; Mechanical Phenomena
PubMed: 30685728
DOI: 10.1016/j.jmbbm.2019.01.009 -
Dental Materials : Official Publication... Jan 2023Different types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation...
OBJECTIVES
Different 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.
METHODS
Three 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.
RESULTS
Dental 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.
SIGNIFICANCE
Less 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.
Topics: Animals; Dental Restoration, Permanent; Dental Amalgam; Dental Materials; Glass Ionomer Cements; Life Cycle Stages; Composite Resins
PubMed: 36428112
DOI: 10.1016/j.dental.2022.11.007 -
Dental Materials : Official Publication... Jun 2017The goal of this manuscript is to provide an overview of biofilm attributes and measurement approaches in the context of studying biofilms on tooth and dental material... (Review)
Review
OBJECTIVE
The goal of this manuscript is to provide an overview of biofilm attributes and measurement approaches in the context of studying biofilms on tooth and dental material surfaces to improve oral health.
METHODS
A historical perspective and terminology are presented, followed by a general description of the complexity of oral biofilms. Then, an approach to grouping measurable biofilm properties is presented and considered in relation to biofilm-material interactions and material design strategies to alter biofilms. Finally, the need for measurement assurance in biofilm and biofilm-materials research is discussed.
RESULTS
Biofilms are highly heterogeneous communities that are challenging to quantify. Their characteristics can be broadly categorized into constituents (identity), quantity, structure, and function. These attributes can be measured over time and in response to substrates and external stimuli. Selecting the biofilm attribute(s) of interest and appropriate measurement methods will depend on the application and, in the case of antimicrobial therapies, the strategic approach and expected mechanism of action. To provide measurement assurance, community accepted protocols and guidelines for minimum data and metadata should be established and broadly applied. Consensus standards may help to streamline testing and demonstration of product claims.
SIGNIFICANCE
Understanding oral biofilms and their interactions with tooth and dental material surfaces holds great promise for enabling improvements in oral and overall human health. Both substrate and biofilm properties should be considered to develop a more thorough understanding of the system.
Topics: Biofilms; Dental Materials; Dental Restoration, Permanent; Humans; Tooth
PubMed: 28372810
DOI: 10.1016/j.dental.2017.03.003 -
The Journal of Prosthetic Dentistry May 2024The increasing use of computer-aided design and computer-aided manufacturing (CAD-CAM) systems has led to the development of resin-ceramic materials that meet the... (Review)
Review
STATEMENT OF PROBLEM
The increasing use of computer-aided design and computer-aided manufacturing (CAD-CAM) systems has led to the development of resin-ceramic materials that meet the requirements of minimally invasive dentistry, including the resin nanoceramic (RNC) and polymer-infiltrated ceramic network (PICN). The wear characteristics of these materials are unclear.
PURPOSE
The purpose of this systematic review was to compare the wear resistance of resin-ceramic materials when compared with one another or with lithium disilicate glass-ceramics.
MATERIAL AND METHODS
The PubMed, Scopus, and DOSS search engines were used to identify articles published between 2013 and 2021. Two independent researchers conducted the systematic review by following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and by following a combination of keywords.
RESULTS
Of a total of 310 articles, 26 were selected, including only 1 clinical study. Among these, 15 compared resin-ceramic materials with each other, while 11 compared resin-ceramic materials with lithium disilicate ceramics. Two types of wear were used to compare the materials: attrition and abrasion. The most commonly studied materials were 2 RNCs (Lava Ultimate and Cerasmart), 1 PICN (Vita Enamic), and 1 ceramic (IPS e.max CAD). Among the resin-ceramic materials, the PICN (Vita Enamic) showed less wear than the RNCs. Of the RNCs, Cerasmart had less attrition wear and less wear of the opposing teeth.
CONCLUSIONS
Lithium disilicate glass-ceramics have a higher wear resistance than resin-ceramic materials, but they cause more wear of the opposing teeth.
Topics: Computer-Aided Design; Ceramics; Humans; Dental Porcelain; Dental Restoration Wear; Dental Materials; Resins, Synthetic
PubMed: 35459543
DOI: 10.1016/j.prosdent.2022.01.027 -
Journal of the American Dental... Dec 2022This narrative review addresses dental restorative materials with sustained antibacterial action, especially those containing quaternary ammonium compounds. Secondary... (Review)
Review
BACKGROUND
This narrative review addresses dental restorative materials with sustained antibacterial action, especially those containing quaternary ammonium compounds. Secondary caries occurs around restorations, causing further loss of mineral and breakdown of the restoration. Lesions adjacent to restorations account for more than 40% of needed restorations. Restorative materials with antibacterial properties will potentially solve this problem.
TYPES OF STUDIES REVIEWED
Several groups are researching composite restorative materials that incorporate antibacterial agents. These agents are mostly exhausted over time. Newer studies involve materials that incorporate antibacterial microparticles that remain active and do not leach out.
RESULTS
One such antibacterial agent, quaternary ammonium coupled with inorganic silica into minute particles (QASi), has been studied in the laboratory and in humans. QASi particles incorporated into dental materials retain their antibacterial action over time without leaching or loss of activity. A clinical in situ study in humans using dental composite containing QASi resulted in highly significantly less demineralization in the adjacent enamel than the control composite material.
CONCLUSIONS AND PRACTICAL IMPLICATIONS
Dental restorative materials that contain QASi have sustained antibacterial properties, have mechanical properties comparable to those of presently marketed materials, and have been cleared by the US Food and Drug Administration. Clinical studies have shown that composites incorporating QASi have the potential to markedly reduce the occurrence of caries around restorations. Because caries around restorations is a major problem, restorative materials with sustained antibacterial properties will have an important effect in reducing secondary caries around restorations.
Topics: Humans; Quaternary Ammonium Compounds; Composite Resins; Dental Caries; Anti-Bacterial Agents; Dental Enamel; Dental Materials; Dental Restoration, Permanent
PubMed: 36272816
DOI: 10.1016/j.adaj.2022.09.006 -
Dental Materials : Official Publication... Jan 2016This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications. (Review)
Review
OBJECTIVES
This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications.
METHODS
Initially the basis of interpenetrating network materials is defined along with placing them into a materials science perspective. This involves identifying potential advantages of such structures beyond that of the individual materials or simple mixing of the components.
RESULTS
Observations from a number of recently published papers on this class of materials are summarized. These include the strength, fracture toughness, hardness and damage tolerance, namely to pointed and blunt (spherical) indentation as well as to burr adjustment. In addition a summary of recent results of crowns subjected to simulated clinical conditions using a chewing simulator are presented. These results are rationalized on the basis of existing theoretical considerations.
SIGNIFICANCE
The currently available ceramic-resin IPN material for clinical application is softer, exhibits comparable strength and fracture toughness but with substantial R-curve behavior, has lower E modulus and is more damage tolerant than existing glass-ceramic materials. Chewing simulation observations with crowns of this material indicate that it appears to be more resistant to sliding/impact induced cracking although its overall contact induced breakage load is modest.
Topics: Ceramics; Composite Resins; Computer-Aided Design; Dental Materials; Dental Restoration, Permanent; Hardness; Materials Testing; Surface Properties
PubMed: 26454798
DOI: 10.1016/j.dental.2015.09.009 -
The Journal of Prosthetic Dentistry Sep 2022Information regarding the masking ability of ceramic crowns over different implant abutment materials is scarce.
STATEMENT OF PROBLEM
Information regarding the masking ability of ceramic crowns over different implant abutment materials is scarce.
PURPOSE
The purpose of this in vitro study was to evaluate the masking ability of different monolithic or bilayer ceramic materials with different thicknesses over substrates indicated for implant restorations by using opaque and translucent evaluation pastes.
MATERIAL AND METHODS
Disk-shaped specimens, shade A1 (VITA Classic; Ø10×1.5 to 2.5 mm), of different ceramics (a bilayer system [yttria-stabilized zirconia infrastructure+porcelain veneer: Zir+Pc] and monolithic systems [lithium disilicate under low, medium, or high translucency: LtLD, MtLD, or HtLD, respectively, and a high-translucent yttria-stabilized zirconia: HtZir]) were made (n=4). The color difference (ΔE) was assessed by using the CIEDE2000 formula and considering the different ceramic systems over 5 implant abutment materials (A1 shade Zir [Zir A1]; white Zir [White Zir]; A1 low-translucency lithium disilicate [LD]; polyetheretherketone [PEEK]; and titanium [Ti]) when using 2 different evaluation pastes (translucent or opaque). The control comparison was the restorative material positioned over the Zir A1 substrate with a translucent evaluation paste. Statistical analysis was made by using a 2-way ANOVA and Tukey post hoc tests (α=.05) for ΔE data considering the restorative material and luting agent factors as their association. Additionally, ΔE data were qualitatively analyzed considering the acceptability and perceptibility thresholds. The translucency parameter (TP) of each restorative material was evaluated, and data were submitted to 1-way ANOVA and Tukey post hoc tests (α=.05).
RESULTS
The most predictable masking ability was seen with Zir+Pc regardless of the evaluation paste used. Nevertheless, under 1.5-mm thickness, Zir+Pc did not adequately mask Ti (ΔE>1.77). Most monolithic ceramics did not mask discolored substrates (PEEK or Ti, ΔE>1.77). The exception was HtZir, which presented acceptable masking ability over PEEK at 2.5-mm thickness with both evaluation pastes (ΔE<1.77). Regardless of the restorative material thickness, Zir+Pc showed the lowest (P<.05) TP values (TP=3.45 at 1.5-mm thickness; TP=2.00 at 2.5-mm thickness), and HtLD presented the highest (P<.05, TP=23.50 at 1.5-mm thickness; TP=13.36 at 2.5-mm thickness). HtZir showed similar TP to MtLD at 1.5-mm thickness and similar TP to Zir+Pc when used at 2.5-mm thickness (P>.05).
CONCLUSIONS
Monolithic ceramics should be used with caution over discolored implant abutments. Bilayer systems (Zir+Pc) were the most predictable approach to adequately masking discolored substrates such as PEEK or Ti. An increased restoration thickness provided higher masking ability for all restorative materials tested.
Topics: Benzophenones; Ceramics; Color; Crowns; Dental Cements; Dental Implants; Dental Materials; Dental Porcelain; Materials Testing; Polymers; Surface Properties; Titanium; Yttrium; Zirconium
PubMed: 35985853
DOI: 10.1016/j.prosdent.2022.05.010 -
Advances in Dental Research Mar 2016The degree of interplay among variables in dental implant treatment presents a challenge to randomized clinical trials attempting to answer questions in a timely,... (Review)
Review
The degree of interplay among variables in dental implant treatment presents a challenge to randomized clinical trials attempting to answer questions in a timely, unbiased, and economically feasible fashion. Further adding complexity to the different scenarios is the varied implant designs and related bone response, area of implantation, implant bulk material, restoration, abutments and related screws, fixation mode (screwed, fixed, or a combination), and horizontal implant-abutment matching geometry. This article critically appraises the most common mechanical testing methods used to characterize the implant-prostheses complex. It attempts to provide insight into the process of construction of an informed database of clinically relevant questions regarding preclinical evaluation of implant biomechanics and failure mechanisms. The use of single load to failure, fatigue life, fatigue limit, and step-stress accelerated life testing is discussed with emphasis on their deliverables, weaknesses, and strengths. Fractographic analysis and challenges in the correlation between laboratory- and in-service-produced failures of dental ceramics, resin composites, and titanium are introduced. In addition, examples are presented of mechanical characterization studies used in our laboratory to assess some implant-supported rehabilitation variables.
Topics: Biomechanical Phenomena; Dental Implants; Dental Materials; Dental Prosthesis Design; Dental Restoration Failure; Dental Stress Analysis; Humans; In Vitro Techniques; Materials Testing; Stress, Mechanical; Time Factors
PubMed: 26927484
DOI: 10.1177/0022034515624445