The degree of conversion (DC) is a measurement of the curing of a resin-based material. Fourier Transform Infrared spectroscopy (FTIR) may be used to determine the DC. The method calculates the conversion of reactive methacrylate groups in the material. The calculation is based on ratios of area or height of specific peaks in the FTIR spectrum of the material.

A recent study performed at NIOM showed that a modified design of the crown margin gave stronger crowns without jeopardizing the aesthetics.

The bond strength between the different materials is crucial for the longevity of a restoration.

A recent master thesis at NIOM aimed to study the change in the physical and toxic properties of experimental dental composites with varying monomer-composition.

NIOM’s programme for the quality evaluation of dental products has been enlarged with three new product groups.

Does the shift in high cost of noble alloys and new methods for fabrication have an implication on patient safety?

When combined, GC/MS and LC/MS allow for analysis of the whole spectrum of leaching components.

The overall topic of NIOM’s presentation at the Norwegian Dental Association’s annual meeting and Swedental in 2015 was Materials for indirect restorations; both metals and all-ceramic materials.

Polymer-based composites are often the material of choice in restorative dentistry. Composites consist of two main phases; the filler, usually silica particles of various sizes, and the matrix that in general is a mixture of methacrylate monomers.

A contagion effect of caries on tooth surfaces in contact with each other has previously been demonstrated; the presence of a caries lesion on an approximal tooth surface increases the risk of developing caries in a sound contact surface on the adjacent tooth. Will this increased risk for caries development be eliminated when restoring the decayed surface with a restoration? A recent publication by the NIOM scientist Dr Kopperud has elucidated the question.

Several studies have been performed in order to assess the effect of different preparation designs for all-ceramic crowns, but the results are ambiguous. Most trials have found no or little effect of different design of the cervical finish line. The new method for clinically relevant testing of all-ceramic crowns developed at NIOM and the University of Bergen in 2012, and published in Dental Materials in 2013, has now been applied to assess one essential parameter of margin design: the curvature of the cervical margin over the gingival papilla.

All but one patient reported side effects of over-the-counter (OTC) bleaching products, while their teeth became noticeably whiter. Two OTC bleaching products with concentrations of 16% and 22% carbamide peroxide gave the same painful but satisfactory bleaching result. The patients found that the easier the products were to handle, the more satisfied they were with the bleaching treatment.

NIOM has recently employed a new scientist and is excited to apply organic synthesis to research and development and analysis of biomaterials for dentistry.

On 29 June 2015, the International Organization for Standardization, ISO, published a revised version of ISO 12836, the standard for assessing the precision of the scanning devices used in dentistry to create digital impressions for prosthetics. By precision we mean that a scanning device delivers the same digitized geometrical model of a test object every time within a given uncertainty in dimensions. Precision is the manufacturer’s responsibility.

NIOM’s experts are strongly involved in standardization activities enhancing the quality of medical devices used in dentistry (ISO/TC 106; CEN/TC 55 Dentistry) and in the development of standards for safety evaluation of medical devices (ISO/TC 194; CEN/TC 206 Biological evaluation of medical devices). NIOM also participates in quality management and corresponding general aspects for medical devices (ISO/TC 210; CEN-CLC/TC 3). New work has recently started in ISO/TC 210/WG 6: Application of post market surveillance systems to medical devices.

In 2011 an electronical questionnaire study was performed by one of the researchers currently working at NIOM. The survey was distributed to all public dental health-employed dentists in Norway to investigate their opinions, knowledge and diagnosis of dental erosive wear. A response rate of 60% was achieved after two reminders. The questionnaire included a patient case where the dentists were asked which clinical advice they would give the patient and which treatment they recommended.

Questionnaires are often used for data collection in epidemiological studies and are a relatively inexpensive way to collect information for research purposes. The aim of a questionnaire is to generalize replies from a small sample to a larger population. If people do not reply to the questionnaires (so called “non-responders”), the research results will tend to be less accurate. Non-responders reduce the effective sample size and can introduce bias. Thus, when performing questionnaires a crucial point is to obtain a sufficiently high response rate. Some ways to obtain that are presented here. First, the odds of response are almost doubled if the respondents are paid for their participation. However, some more inexpensive factors can be easily adjusted to attract the respondents’ interest.

For some dental clinics, intra-oral scanning to create a digital rather than physical impression of a patient’s dentition is but the first stage of an in-house production of a crown, bridge or inlay. While many dentists send the digital impression to a dental technician with a purchase order for the required prosthesis, chairside manufacture offers the advantage of one-session treatment and the close involvement of the dentist in producing the prosthesis.

Positions as visiting scientist in the field of dental biomaterials research are offered at the Nordic Institute of Dental Materials, NIOM, in Oslo, Norway. The purpose of NIOM’s visiting scientist programme is to enhance Nordic collaboration on dental biomaterials research. Positions are available during 2016 for periods between 3 and 6 months.

The Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) is a committee within the European Commission for Risk Assessment. SCENIHR has recently published an opinion on the use of bisphenol A (BPA) in medical devices. Contribution to the opinion was given by SCENIHR members and external experts including Prof. A Hensten, UiT The Arctic University of Norway, and Dr H. Molvig Kopperud from NIOM.

Mechanical properties describe a material’s response when exposed to various mechanical impacts such as tension, pressure or deflection or even temperature change. As such they are crucial in evaluating the quality of a dental material or indeed any material.

Secondary caries is the primary reason for replacement of composite fillings, and clinical studies report more secondary caries when composites are used compared to amalgam in high-risk caries groups. This highlights the need for development of materials that will reduce or inhibit biofilm formation on dental materials.

The oral cavity is one of the human habitats with the highest diversity of bacterial species. It is estimated to be over 700 bacterial species that are capable of residing in this habitat. Bacteria were long thought of living as free floating, planktonic cells. However, it has become clear that the preferred form of living is in a biofilm.

Overseas and Norwegian-made dental crowns – does the delivery meet the ordered specifications?

Scientists from NIOM participated when 40 delegates from academic institutions, research institutes and industry gathered to decide guidelines on light curing to be given to dental personnel. The meeting was held at Dalhousie University, Halifax, Canada in the spring of 2014 and guidelines were published a few months later.

An important criteria for a long-lasting restoration of a polymer-based material, is a proper curing throughout the entire restoration. To achieve this, an effective polymerization is crucial so that the polymer network will extend throughout the material.

NIOM scientists were invited to the national dental conventions in Sweden and Norway this autumn. Head of Laboratory Hilde M. Kopperud, researcher Simen E. Kopperud and guest-researcher Frode Staxrud from NIOM interacted in the two-hour lecture which presented data from both clinical and laboratory studies, and was entitled: Tooth-coloured restorations – choice of materials, procedures and longevity.

As the rise in antibiotic resistant bacteria worldwide accelerates, there is a great need for alternative antibiotic treatments like antimicrobial photodynamic therapy (aPDT).

Information on altered expression of toxicologically relevant genes is important when analyzing the underlying mechanism of toxic responses in cells. Western blotting is a common method to identify and quantify level-changes of proteins in tissues and cells exposed to possible toxic compounds.

Repairing and extending composite restorations are common and well-accepted procedures for the dental practitioner. Evaluation of the repair strength has great research focus by using tensile and shear bond strength measurements. The present collaborative study from NIOM has assessed the effect of surface treatments and bonding systems on the repair bond strength between composite materials after 1 and 12 months of storage, using a tensile test method.

A new research group is established at NIOM, focusing on clinical research. The group consists of four scientists, Simen E. Kopperud, Håkon Valen, Rune Becher and Jon E. Dahl, with a broad and diverse scientific background. They have extensive knowledge from toxicology, dental materials, epidemiology, environmental science and microbiology. This experience and knowledge is giving an initiative and opportunity for inter-disciplinary research.

Fractures during clinical function have been reported as one of the major causes for failure associated with all-ceramic dental restorations. Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available.

NIOM has the pleasure of inviting you to a seminar to introduce our new programme NIOM TESTED. The NIOM TESTED programme is a system of quality evaluation of dental products that will give your product the advantage necessary to increase sales.

In oral and orthopaedic surgery, composites can be used as implants or bone grafts. Their functions are to direct, supplement or replace living tissues. The greatest synergy of every constituent of the composite is to combine different material properties. In fact, the properties of functional composites can be customized to match those of the target tissues.

The delightful combination of a coffee and an ice cream sets the parameters for one of the most used test protocols for dental materials. The international standard for testing dental adhesives stipulates an ageing procedure in which test specimens are held repeatedly first in 5 °C cold water and then in 55 °C hot water for a large number of cycles. The result of subsequent testing invariably shows degradation in adhesive strength. It is important that this loss of bonding is limited.

Oral diseases such as periodontitis and gingivitis are inflammatory processes induced by bacterial biofilms. The bacterial factor lipopolysaccharide (LPS) is an important virulence factor of gram-negative bacteria, and plays an essential role in triggering periodontal inflammation. LPS activates macrophages and causes an inflammatory response including synthesis and release of cytokines – an important strategy utilized by the host to resist periodontal bacteria.

The Colony-Forming Unit (CFU) method can be used for identification of microorganisms and for testing the effect of antimicrobial substances and techniques. It is a sensitive and widely accepted method within microbiology. In this method, the number of living cells (cells able to reproduce) present in a suspension is counted on a nutrient agar surface.

The deterioration in dental health that occurs when elderly people move into institutional care can be dramatic. Good, life-long habits of dental hygiene are broken, either because the move is associated with significant new health problems, or because daily routines have been upset. Regardless of the reason, rapid development of caries and other dental problems are observed in institutionalized patients.

Dental materials are subject repeatedly to masticatory forces, both directly on an occlusal surface, and indirectly through interactions with an abutment or via a connecting unit.

Glass-ionomer cements (GIC) adheres to tooth substance but the strength of the GIC is lower than other filling materials. Even though traditional GIC products have been used for Class II restorations in pediatric patients, the longevity of the restoration is often regarded as inferior to other materials.