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PubMed1998

Dental materials: 1996 literature review. Part 2.

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. 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, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.

Ceramics↗

PubMed2000

Clinical application of laser-induced breakdown spectroscopy to the analysis of teeth and dental materials.

OBJECTIVES: The luminous plasma generated during laser ablation of dental tissue and dental materials has been analyzed to determine qualitative and quantitative elemental composition. BACKGROUND DATA: The use of pulsed lasers for controlled material ablation now is frequently suggested as an alternative to mechanical drilling for the removal of caries and in tooth modification. Spectral analysis of the ablated plasma can be exploited to monitor precisely the laser drilling process in vivo and in real time. METHODS: Teeth samples and dental materials were ablated using pulses from a Nd:YAG laser. The line positions and intensities in the spectra, recorded in real time, were used to identify elements and to determine their relative concentrations. RESULTS: From the spectra of horizontally and vertically cut tooth slices, profiles of elemental distribution were determined; these were used in a range of monitoring applications. We showed that the transition from caries to healthy tooth material could be identified through the decrease in calcium (Ca) and phosphorus (P) concentrations, whereas nonmineralizing elements and organic materials increased in concentration. We also could relate the spatial distribution of elements to their migration or accumulation over time, for example, the migration of aluminium (Al) from dental restorative materials to the tooth matrix. CONCLUSIONS: The plasma existing during laser ablation (in vitro/in vivo) can be analyzed spectrally in real time. From the spectra, one can pinpoint high/low levels of element concentrations within the tooth matrix. Thus, this analysis could be used to monitor the ablation of material during laser dental treatment.

Adult↗

PubMed1992

In vitro vibrational wear under small displacements of dental materials opposed to annealed chromium-steel counterbodies.

In vitro vibrational wear tests were performed on 17 composites and one amalgam with human enamel as a reference. The specimens were fixed on a computer-controlled X-Y translation table that generated an oscillatory movement under small displacements. The dental material specimens were in permanent contact with an annealed chromium-steel counterbody. The tests were performed in ambient air of normal humidity at room temperature under non-lubricated sliding conditions. The friction between the counterbody and each of the various materials was measured on-line. After completion of the tests, the wear volumes were determined by contactless profilometry, and the wear pattern was studied with SEM. The simple vibrational test used in this study allowed a fast classification of different dental materials in terms of the relative wear on either the specimen or the counterbody material. The ratio of the wear volume of the counterbody versus the wear volume of the dental material specimen was used to accurately classify the materials according to their in vitro wear behavior, especially when this ratio was related to the total wear volume of the dental material specimen and the counterbody. From an analysis of the wear behavior of the both contacting materials, it became obvious that neither the wear of the dental materials nor of the chromium-steel counterbody appears to correlate with either the inorganic filler hardness, the intrinsic surface roughness, the surface hardness or the Young's modulus of the dental materials.

Chromium Alloys↗

PubMed1998

Dental materials: 1996 literature review.

Dental Alloys↗

PubMed2007

Comparison of the clinical and preclinical biocompatibility testing of dental materials: are the ISO usage tests meaningful?

International Organization for Standardization (ISO 10993 and 7405) guidelines recommends the preclinical screening of dental materials using non-human primates. The literature contains no comparisons of responses to dental materials. To test the accuracy of preclinical screening tests for predicting human clinical responses, 106 class V pulp exposed cavities were prepared in human and non-human primate teeth. Teeth were restored with calcium hydroxide and amalgam, zinc oxide eugenol or resin-modified glass ionomer. Teeth were extracted after 10-163 days and prepared for histological analysis. Pulp cell numbers were compared and their reactionary dentin activity measured in response to cavity preparation. Pulp inflammatory activity was categorized according to ISO standards. There were no statistically significant differences between human and non-human primate teeth in terms of pulp reactions to dental materials. The use of non-human primates for preclinical biocompatibility investigation provided an accurate method of evaluating clinical responses to dental materials.

Adolescent↗

PubMed2002

Endocrine disruptors and dental materials: health implications associated with their use in Brazil.

This study analyzes international historical trends in the use of different types of materials in dental practice. The author describes the chemical properties of their ingredients and the potential and observed adverse effects in patients and dental technicians resulting from clinical or occupational exposure to various metals like beryllium, used to produce metal alloys. The growing use of various products (resin cements, ionomer cements, aesthetic restorative materials, resins, endodontal cements, and others) based on the compound bisphenol-A, whose chemical structure is similar to that of estrogen. Considering the demographic and contemporary work force characteristics of those involved in dental practice in the Brazil, the study highlights the possible effect of the use of these materials in both male and female patients and all age strata, as well as in health professionals with occupational exposure to products containing bisphenol-A.

Benzhydryl Compounds↗

PubMed1990

Vinyl polysiloxane impression materials: a status report. Council on Dental Materials, Instruments, and Equipment.

Results of investigations of vinyl polysiloxanes indicate that they produce highly accurate impressions, have excellent elastic recovery, minimal permanent deformation, and adequate tear strength. A number of vinyl polysiloxanes are certified by the American Dental Association. All of these materials provide clinically acceptable results. Advantages of using the vinyl polysiloxanes include the ability of the impression to be poured up after 1 hour or 1 day, or for some products, after 1 week without significant loss of accuracy; the possibility of repouring the impression a second time and producing an accurate cast; the impression materials are available in several viscosities allowing flexibility in choosing an impression technique; and they can be immersed in recommended disinfectants without affecting the accuracy of the impression. The disadvantages of using the vinyl polysiloxanes include a difficulty in lengthening the working time of products without retarders and a high surface tension making it difficult to wet the impression when pouring up a stone cast. Hydrophilic materials appear to facilitate the casting of the impressions with stone. The automixing devices seem to provide convenience without sacrificing the quality of the impression and are currently available for several products. As with all elastomeric impression materials, proper handling is necessary to ensure the best results. The vinyl polysiloxanes seem to be an excellent choice of impression materials for many clinical situations.

American Dental Association↗

PubMed2002

Biocompatibility of dental materials in two human cell lines.

It was the aim of this study to investigate the biocompatibility of metallic (titan, gold, amalgam) and ceramic dental materials in contact with gingival (GF) and epithelial tumour cells (EpiCa). The cells were incubated with the test specimens (5 mg/piece) over a period of six days. Cellular proliferation rate, protein synthesis, and prostaglandin release (PGE2) served as parameters to determine the biocompatibility of the materials. - The investigations showed that the protein values were subject to slight variations following contact with the dental materials. Incubation of the cells with the test materials resulted in material dependent increases in PGE2-values (GF/EpiCa: titan: 187.4%, 131.0%; ceramic: 151.5%, 176.4%; gold: 114.5%, 123.8%; amalgam 150.6%, 159.8%). A comparison of control cells and cells of the test series (GF/EpiCa) after cell stimulation with 10-5M arachidonic acid (AA) showed the following changes in PGE2 on contact with titan (110.0%, 167.5%), ceramic (98.7%, 188.9%), gold (119.5%, 153.1%), and amalgam (68.9%, 179.5%). - Measurement of the proliferation rate (24 hours) further demonstrated that the dental materials used exerted an influence on the growth rates. While amalgam was associated with a marked reduction in the proliferation rate, titan, gold and ceramic induced only slight changes in the growth rate. - The results of the present study demonstrate that the cell culture systems used represent suitable in vitro models for the investigation of the biocompatibility of dental materials. The level of cell irritation was shown to be lowest for titan, closely followed by ceramic and gold. Cell culture; prostaglandin release; titan; ceramic; amalgam

Adult↗

PubMed2000

Detection of bisphenol-A in dental materials by gas chromatography-mass spectrometry.

The xenoestrogenic substance bisphenol-A is widely used as a synthetic precursor of resin monomers, such as bisphenol-A diglycidyl methacrylate. Reports describing the release of bisphenol-A from polymerized resin into saliva have aroused considerable concern regarding exposure to xenoestrogen by dental treatment. The purpose of the present study was to demonstrate a reliable methodology of detecting the trace amounts of bisphenol-A in dental materials. Bisphenol-A was separable from bisphenol-A diglycidyl methacrylate, which is often employed as the principal dimethacrylate monomer, by selective extraction with a Sep-Pak C18 cartridge. Using this extraction method in combination with a gas-chromatography mass-spectrometry, we have obtained evidence that all unpolymerized materials used in this study were contaminated with bisphenol-A. Quantitative analysis using a deuterium-labeled compound as an internal standard revealed bisphenol-A contents in commercial dental materials ranging from < 1 microgram/g material to about 20 micrograms/g material. The polymerized dental materials released up to 91.4 ng bisphenol-A/g material into phosphate buffered saline during 24-h incubation. These results indicate that bisphenol-A can be released from dental materials, however the leachable amount would be less than 1/1000 of the reported dose (2 micrograms/kg body weight/day) required for xenoestrogenisity in vivo.

Benzhydryl Compounds↗

PubMed1984

Allergy and corrosion of dental materials in patients with oral lichen planus.

Patients with histologically verified oral lichen planus (OLP) were studied regarding allergic reactions to substances in dental materials, presence of clinical corrosion orally and factors influencing corrosion, such as mixed gold and amalgam therapy, non-precious pin-constructions or complete dentures. The material consisted of 48 OLP patients (33 female, 15 male) and the results were compared with those of a control group (40 patients) and/or general population samples. When patch tested, 39% of the OLP patients reacted to one or more components in dental materials. Reaction to mercury was most common, being noted in 26%. Clinical signs of corrosion were significantly more frequent in the OLP group (72%) than in the control cases (28%). Patients with atrophic-erosive OLP exhibited a significantly higher frequency of corrosion (83%) than those with reticular type (46%). Mixed gold and amalgam therapy and screwposts were equally present in both the OLP and control group and the frequency of complete dentures corresponded to that reported for general populations. A change of dental materials in 8 patients with positive patch tests led to marked oral improvement in 6 cases, 2 of which became completely cured. The frequencies recorded for allergic reactions and corrosion as well as the result of treatment indicate that substances in dental materials may be of significance in cases of OLP.

Adult↗

PubMed1989

[Antimicrobial action of dental materials used in operative dentistry: a review].

This is a review of the literature about the antimicrobial action of dental materials used in operative dentistry. There are referred to the usefulness of the antimicrobial action of dental materials, and to the methods used by the investigators for the study of the antimicrobial properties. The methods used were: the examination of the in vitro antimicrobial action of the materials against several microbes, The in vivo antimicrobial action of the materials against the microbes that are enclosed underneath them in dental cavities, where some carious material was left on the floor of the cavities. Some other methods, as so as the adsorption of microbes on the experimental materials, in vivo and in vitro. There are presented the results of a lot of investigators for the antimicrobial action of dental amalgams, composite resins, silicate cements, glass-ionomer cements, zinc-phosphate, zinc oxide-eugenol and polycarboxylate cements, calcium hydroxide bases and also for varnishes and liners, since the time of Miller (1890) up to now. From these researches we can come to the following conclusions: 1) All dental materials have some antibacterial activities against several microbes when they are freshly mixed. Their action reduces with the past of time. 2) The responsible antibacterial factors are unknown. May be more than one factors. 3) In clinical practice it is not known what material is better, because the conditions are different from tooth to tooth and from mouth to mouth. 4) More researchers are necessary for this purpose because the antibacterial properties must be regarded as a part of the other biological properties of dental materials and the recurrent caries may be inhibited because of the antibacterial properties of filling and base materials.

Anti-Infective Agents↗

PubMed2006

Application of HS-SPME in the determination of potentially toxic organic compounds emitted from resin-based dental materials.

Leaching of volatile substances from resin-based dental materials may have a potential impact on the biocompatibility as well as safety of these materials. Information from manufacturers on ingredients in the materials is very often incomplete. Patients and dentists may be in contact with components emitted from cured dental fillings or from substrates applied in their preparation. Therefore, determination of the components of these materials is necessary for better prevention from possible harmful effects caused by dental fillings. The aim of this work was the isolation and identification of organic compounds evolved from four commercial resin-modified glass-ionomer cements (resin-based dental materials applied in dentistry) by using an alternative method of volatile compounds analysis-HS-SPME (headspace-solid phase microextraction). Dental materials were heated in closed vial at various temperatures and volatile substances released into the headspace phase above the sample were isolated on a thin polymeric fibre placed in SPME syringe. Identification was performed by using the GC-MS (gas chromatography-mass spectrometry) technique. Almost 50 RMGIC (resin-modified glass-ionomer cement) components (monomers and additives) were identified. The main identified leachables were: iodobenzene (DPICls-diphenyliodonium chloride degradation product), camphorquinone (photo-initiator), tert-butyl-p-hydroxyanisole (inhibitor), 4-(dimethylamino)ethyl benzoate (co-initiator), ethylene glycol dimethacrylate (monomer).

Compomers↗

PubMed1972