for Nordic dental health
Nordisk institutt for odontologiske materialer (Nordic institute of dental materials) is a Nordic collaborative body within dentistry that is incorporated as a Norwegian state-owned enterprise. NIOM’s purpose is to ensure that medical materials and devices used in dentistry in the Nordic countries meet the health and technical requirements taking into account the development in the area.
Today, NIOM is primarily financed by The Nordic Council of Ministers (Nordic abbreviation, NMR) and Norwegian health authorities. NMR and NIOM have a contractual agreement specifying the tasks to be covered by the NMR support. These include information services, research into biomaterials and our visiting scientist programme. NIOM realised early that common international requirements for materials quality were necessary. NIOM soon engaged strongly in international and European standardisation activities to ensure that requirements for materials quality are high and relevant. Patient safety guides our research. In addition to clinical projects, NIOM conducts research projects in toxicology, microbiology and into the technical and chemical properties of materials. Our goal is to ensure that the patients in the Nordic countries are treated with the best possible materials.
Vision and values
NIOM’s vision is to ensure dental biomaterials in general and particularly in the Nordic countries are safe and effective. All activity is founded on NIOM’s three values: knowledge, innovation and quality.
NIOM’s purpose was, and still is, to ensure that medical devices used in dentistry in the Nordic countries meet health and technical requirements, taking into account new scientific and clinical developments. Much has changed as a consequence of the developments within Europe. From our founding in 1972 until 1998, dental materials for the Nordic market were tested and certified by NIOM. Eachyear, NIOM published overviews of certified products and the authorities in the Nordic countries either required or recommended dentists to use NIOM certified products. From 1998 common European regulations for approval of dental materials in accordance with the Medical Device Directive were introduced, and regional certification schemes like NIOM’s certification were prohibited.
Today, NIOM has two major sources of funding, the Nordic Council of Ministers (NMR) and the Norwegian health authorities. The Nordic Council of Ministers (NMR) and NIOM have a contractual agreement covering the tasks to be funded by NMR’s grant. These include information activities, research into biomaterials, and our visiting scientist programme. Each year, 24 months in salaries are earmarked for visiting scientists from Nordic countries who work at NIOM for shorter or longer periods. Table 1 shows the numbers of visiting scientists from each country. The purpose of the visiting scientist programme is to increase Nordic cooperation within biomaterials research.
Figure 2. Laboratory: One of NIOM’s research laboratories for biological analyses. Photo: NIOM.
The Norwegian health authorities finance rental costs and instrumentation, standardization activities, research and information activities. Several research positions are earmarked for cooperation with the competence centres for dentistry in Norway and corresponding institutions in the other Nordic countries. NIOM has well equipped premises with comprehensive instrumentation for physical, chemical and biological research (Figure 2).
Table 1. Overview of the origin of the visiting scientists in the period 1979–2016. In total, 76 man-labour years divided among 96 visiting scientists were financed by NIOM.
|Visiting scientists at NIOM|
Jon E. Dahl, Managing Director,
dr. odont, DSc,
NIOM – Nordisk institutt for odontologiske materialer AS, Oslo, Norway
First published in Tandlægebladet 2016;
120; No 11
NIOM’s information programme, research portfolio and research collaboration are all geared towards Nordic activities and the Nordic countries. The visiting scientist programme, in which scientists from the Nordic countries get paid for their period at NIOM, is a central part of this activity. A number of NIOM’s research projects have been and continue to be of Nordic character. The research results are published in recognized international journals which are read by other Nordic scientists and benefit their further research. Nordic dentists are informed about NIOM’s research results and advisory reports in lectures at the dentists’ annual meetings, by publication in Nordic dental magazines and via NIOM’s home page (www.niom.no). NIOM publishes a monthly newsletter which particularly focuses on the clinical relevance of our research. NIOM also answers numerous inquiries from Nordic dentists regarding the use and choice of materials.
Use of standards and testing of materials
NIOM become convinced at an early stage that common international requirements for materials quality were necessary. The best way this could be achieved was through international standardization. Researchers from NIOM participate actively in the work ISO (International Standardization Organization) does to develop quality requirements for dental products. With both the results from NIOM’s research and its experience with test methods NIOM has had and still has considerable influence on the requirements and test methods included in the standards for dental biomaterials. Our goal is to lay down requirements that are relevant for patient safety, and do not favour particular manufacturers. International standards have long been used in NIOM quality assessment for dental materials. Today, NIOM tests materials for manufacturers who want independent documentation for use in the approval of their product (e.g. CE marking) and for their in-house quality assurance (Figure 3). NIOM also assists health authorities who need to check on products in the market.
Figure 3: Laboratory: Temperature- and humidity-controlled laboratory for testing of materials. Photo: NIOM.
Better patient safety is a guideline for NIOM’s research. In addition to clinical projects, NIOM has projects in toxicology, microbiology and materials science and technology. Our goal is to obtain results that can ensure that patients in the Nordic countries are treated with the best possible materials. Issues related to polymer materials, ceramics or alloys are all relevant. The results from our research are communicated to the scientific community in research publications, and to dental practitioners through courses, lectures, articles in dental journals and NIOM’s newsletter. In the period 2011–2015 90 articles related to NIOM’s research have appeared in international and Nordic journals. Through interdisciplinary and Nordic collaborative projects, our visiting scientists and other partners have made important contributions to these publications. NIOM’s research activity has increased in recent years as NIOM has grown and been able to hire talented young scientists. NIOM’s research is concentrated on the materials’ biocompatibility. A biocompatible material is one that neither affects the patient negatively nor is its quality and properties degraded by the patient. In the following, a short overview of some published results from such studies is given.
Corrosion and degradation are the causes of patient exposure to substances from dental materials. Leakage from polymer-based materials and alloys have been shown in a number of laboratory studies at NIOM (1–5). However, measurements on saliva from patients after dental treatment with polymer-based materials show low and short-term concentrations of leachables (6, 7).
Cellular biological studies
Methacrylates, which are part of polymer-based dental materials, are toxic for laboratory-grown cells. Observed cell death is apparently caused by oxidative damage (8). Concentrations of methacrylates that do not cause acute cell death can nonetheless affect cells, i.e. by changing cell growth pattern. Direct bonding to cellular proteins or DNA damage has also been observed (9–12). Cells that are isolated from animals used for experimental purposes (primary cells) and exposed to methacrylates die at much lower concentrations than cells from established cell lines(13). A possible explanation may be that primary cells have a greater ability to transform foreign substances and, in the case of methacrylates, to more toxic substances. Laboratory tests have shown that methacrylates interfere with the production and release of inflammatory substances (14). The same effect has been observed when the cells are exposed to particles that are used in dental restorative materials (15, 16). Increased cell mortality is seen after co-exposure to methacrylates and blue light compared to exposure to each agent separately (17). This observation was linked to a methacrylate-induced weakening of the antioxidant defence of the cells, which makes them more vulnerable to the reactive oxygen compounds that are created by absorption of light (18).
Bacteria and biofilm
An antibacterial method based on a formulated light-absorbing substance in combination with visible light is under development. Complete extermination of several different strains of bacteria has been demonstrated in vitro with several light-absorbing substances and formulations (19–22). Adsorption of liposomes to dental restorative materials has been studied with a view to possible inhibition of biofilm formation and sealing of the margin of restorations (23).
The risk of fracture of all-ceramic crowns is affected by the design of the margin and the restoration itself. High approximal curvature increases the risk of fracture (24). For zirconia crowns with veneering ceramic, the risk of fracture is reduced if the cervical connection is designed in zirconia and not veneer (25). NIOM has investigated whether imported and Norwegian-produced dental crowns fulfil the requirements of the Medical Devices Directive (93/42/EEC) (26). Discrepancies between ordered and supplied alloys were particularly prominent for the imported crowns, but were also observed in the Norwegian-manufactured techicial work. Much of the work was supplied without the mandatory compliance statement. The significance of the curing time (5, 10, or 20 sec.) with LED lamps for material properties (27) has been investigated. The surface properties of the materials, measured as degree of conversion at the surface and resistance to wear, are not influenced by short curing times. Short curing time leads to poorer material properties including low curing depth and increased consentration of unreacted monomers. Tensile and shear bond testing are used to find improved methods for the repair and extension of composite fillings. Use of enamel–dentine bonding agents and silanisation of the existing filling has been shown to improve the bonding between the old and new composite (28–30).
An in vitro study has shown that the bleaching effect of hydrogen-peroxide bleaching agents is not enhanced by irradiation with blue light, and that the blue light can give side effects (31). A Scandinavian practice-based study pointed out that adverse side effects occur frequently in tooth bleaching, regardless of whether an at-home or in-office procedure has been followed (32). For both types of treatment, about 50% of the patients reported increased sensitivity and pain in the teeth. Ulseration of the gingiva was observed in 14% of at-home bleaching and in 35% for in-office bleaching (Figure 4). Over-the-counter bleaching products gave even more frequent side effects (33).
Figure 4: Bleaching damage: Whitish corrosive damage to gingiva after in-office bleaching. ©Photo: Senior dentist Ulla Pallesen.
NIOM has studied how well different protective glasses and shields protect the eyes from the blue light used in curing polymer materials (34, 35). The European rules for individually adjusted medical equipment have been reviewed in order to develop guidelines for dentists who acquire their own CAD/CAM system for fabrication of crowns and bridges. The conclusion is that European clinics, as opposed to American clinics, have a responsibility for the quality that cannot be transferred to the manufacturer of the CAD/CAM system (36).
NIOM – Nordisk institutt for odontologiske materialer (Nordic institute of dental materials) was established in 1972 as a joint Nordic institute located in the greater Oslo area. At the time, NIOM’s owners were the Nordic countries which exercised governance through grants from The Nordic Council of Ministers (NMR). In 2009 The Nordic Council of Ministers decided that NIOM should be a Nordic collaborative agency with Norwegian owners. UniRand AS, a company owned by the University of Oslo, and The Ministry of Health and Care Services became the owners of NIOM.
Figure 1: NIOM’s premises: Concurrent with the transformation to a Nordic collaborative body, NIOM moved into new premises by Ullevål Stadium in Oslo. NIOM rents more than 2,000 square metres for laboratories and offices. Photo: NIOM.