Arne Hensten-Pettersen

NICKEL ALLERGY IN ADOLESCENTS IN RELATION TO ORTHODONTIC TREATMENT AND PIERCING OF EARS

The aim of this study was to investigate the frequency of nickel hypersensitivity in adolescents in relation to sex, onset, duration and type of orthodontic treatment, and the age at which ears were pierced. The subjects were 700 Finnish adolescents, from 14 to 18 years of age, of which 476 (68%) had a history of orthodontic treatment with metallic appliances. The study consisted of patch-testing for a nickel allergy and a patient history obtained by a questionnaire and from patient record. The frequency of nickel sensitization in the whole group was 19%. Nickel allergy was significantly more often found in girls (30%) than in boys (3%) and in subjects with pierced ears (31%) than in those with no piercing of ears (2%). Orthodontic treatment did not seem to affect the prevalence of nickel sensitization. None of the girls who were treated with fixed orthodontic appliances before ear piercing showed hypersensitivity to nickel, whereas 35% of the girls who had experienced ear piercing before the onset of orthodontic treatment were sensitized to nickel. The results suggest that orthodontic treatment does not seem to increase the risk for nickel hypersensitivity. Rather, the data suggests that treatment with nickel-containing metallic orthodontic appliances before sensitization to nickel (ear piercing) may have reduced the frequency of nickel hypersensitivity.

Composition and in vitro corrosion of orthodontic appliances

The high incidence of nickel allergy and the increasing use of nickel-containing dental biomaterials has been of growing concern. The purpose of this investigation was to analyze different types of alloys used in orthodontics, and to study whether nickel and chromium will be released from these alloys when stored in physiologic saline. Face-bows, brackets, molar bands, and arch wires were analyzed. Most of the different parts in the face-bows, brackets, and molar bands were similar to conventional 18/8 stainless steel. Except the wires, most appliances included a variable amount of silver solder, the greatest in face-bows. After 14 days in 0.9% sodium chloride (NaCl), the largest amount of nickel and chromium were leached out from the face-bows and the least amount from the arch wires. Soldered stainless steel face-bows seemed to be very susceptible to corrosion. The release of nickel seemed to be related to both the composition and the method of manufacture of the appliances, but the release was not proportional to the nickel content.

Salivary nickel and chromium in subjects with different types of fixed orthodontic appliances

The aim was to investigate nickel and chromium concentrations in saliva of patients with different types of fixed appliances. Saliva samples were collected from 47 orthodontic patients, ages 8 to 30 years. Four samples from each subject were collected: (1) before insertion of the appliance, (2) 1 to 2 days after, (3) 1 week after, and (4) 1 month after insertion of the appliance. A considerable variation in the concentrations of both nickel and chromium was observed. No significant differences were found between the no-appliance samples and the samples obtained after insertion of the appliances. The results suggest that nickel and chromium concentrations of saliva are not significantly affected by fixed orthodontic appliances during the first month of treatment.

The cytotoxic effect of denture base polymers

The cytotoxic potential of autopolymerized pour and dough type resins and heat cured resins was studied by in vitro cell culture techniques. Human epithelial cells (NCTC 2544) were grown in Eagles minimal essential medium on the surface of the polymer disks. The cell multiplication on the surface of the specimens was measured. One heat cured resin and one pour type resin demonstrated a slight cytotoxic effect. The other polymers gave a moderate cytotoxic effect. The study did not indicate any difference in the cytotoxicity of the polymers when manufactured by alternate processing methods.

Health hazards associated with curing light in the dental clinic

The assessment of side effects of substances encountered in odontology by patients and the dental team must include the direct and indirect effects of irradiation emitted from polymerisation devices. The eyes of the lamp operators are at risk from acute and cumulative effects, mainly due to back-reflection of the blue light. Furthermore, phototoxic and photoallergic reactions originating from absorbed radiation in endogenous or exogenous substances accumulated in the operators’ eyes and skin (hands) as well as the patients’ oral mucosa must also be taken into consideration. Preventive measures include reading the manufacturers’ operating instructions for curing devices and using radiation-filtering protection goggles.

Denture adhesives: Cytotoxicity, microbial contamination, and formaldehyde content

Denture adhesives are extensively used to enhance retention of dentures. Denture adhesives and their leachable components are ingested, but reports on the biologic aspects of denture adhesives are scarce. This study investigated some biological properties of 19 commercially available denture adhesives. The adhesives were assessed by the agar overlay technique and analyzed for microbial contamination and formaldehyde content. In the agar overlay test, all of the materials caused severe cytotoxic effects. Sabouraud dextrose agar was used for cultivation of fungi and tryptone soya broth for cultivation of aerobes, including fungi. Most of the samples tested showed microbial growth. The formaldehyde test revealed the presence of substantial amounts in four products and minor amounts in two products.

Proliferation of nickel-sensitive human lymphocytes by corrosion products of orthodontic appliances

Lymphocyte transformation tests were performed on peripheral blood taken from individuals with a history of contact dermatitis who also presented with a positive patch test to nickel sulphate, and from individuals with no history of contact dermatitis. The results implied that nickel leached out from metallic orthodontic appliances in sufficient amounts and of a chemical nature adequate to stimulate proliferation of lymphocytes from some of the nickel-sensitive subjects.

Tooth colored dental restorative materials: Porosities and surface topography in relation to bacterial adhesion

The present investigation was carried out to determine whether differences in initial bacterial accumulation on dental restorations could be explained by differences in surface topography, particularly porosities, of the materials. A point counting method was used to determine the number and the size of the porosities in 15 materials. The results demonstrated great variation among the materials in the number of porosities. However, in vitro bacterial adhesion tests failed to show any relationship between porosities in the materials and the number of bacteria adhering to them. Nor were differences in surface topography, as measured profilometrically, associated with differences in bacterial adhesion. It is concluded that variations in surface topography including porosities do not suffice to explain differences in initial bacterial accumulation on silicate cements and composite dental restoratives.

Some chemical characteristics of human minor salivary gland secretions

The minor salivary glands contribute to the composition of whole saliva, but little information has been available about their chemical constituents. Pilocarpine-stimulated labial and palatine secretion from 4 human subjects was investigated by paper and disc electrophoresis, immunochemical analysis, and for content of carbohydrates, amino acids, lipids, hexuronic acids and sulphate. No significant differences were noted between the labial and palatine secretions by any of the methods employed. The minor gland secretions appeared to consist mainly of mucosubstances, possibly with blood group specificity. In addition, three water-soluble components with the characteristics of albumin, alpha-amylase and secretory IgA were seen. The minor gland secretions had an amino acid profile different from those of the major salivary glands and contained higher proportions of carbohydrate. Only one lipid component, with the characteristics of a polar lipid, was seen. Hexuronic acids were not detected in either secretion, whereas both contained sulphate. It would appear that the minor mucous glands contribute to the content of mucosubstances in whole saliva, whereas their content of water-soluble material is negligible in this respect.

Tissue reactions to implanted orthodontic wires in rabbits.

Tissue response to a Fe-Cr-Ni and a Co-Cr-Ni orthodontic wire, in the as-received state and with silver soldered joints, was investigated. Specimens with polytetrafluoroethylene (PTFE) as a reference material were implanted in the subcutaneous tissue of rabbits. Six rabbits were sensitized to nickel, four animals were sham-sensitized, and two were left untreated. The results showed that the as-received wires gave no tissue response relative to the PTFE control. In soldered specimens that were moderate to extreme reactions adjacent to the soldered joint and around the wire portion as well. The soldered Co-Cr-Ni wire elicited the most severe reactions, most pronounced in the nickel-sensitized animals. The agar overlay cell culture test of some retrieved implants showed pronounced cytotoxicity of the soldered specimens. Leachable toxic components of the silver solder seemed to be of major importance in the observed cell culture and tissue response to the soldered specimens.