Stainless-steel crowns in children: Norwegian and Finnish dentists' knowledge, practice and challenges.

BACKGROUND: Stainless-steel crowns (SSCs) are recommended for restorative treatment of young teeth severely affected by caries, fractures or dental developmental disorders (DDDs). However, despite recommendations and clinical evidence, SSCs are not widely used by general dentists, who favour extraction and more conventional restorations. The present study aimed to investigate the views of and use of SSCs among Norwegian and Finnish dentists. METHODS: The present study was a cross-sectional survey among Norwegian and Finnish dentists. An electronic questionnaire was sent to Norwegian and Finnish dentists asking whether they used SSCs and on which indications. In addition, the questionnaire assessed reasons for non-use and dentists' perceptions regarding advantages and challenges in the use of SSCs, as well as the need for additional training. Distributions of background characteristics, use of and views on SSCs were calculated, and statistical significance of the associations between respondents' background and their answers were evaluated. RESULTS: Of the 574 Norwegian and 765 Finnish respondents, only 12.0% and 12.9% reported to use SSCs, respectively. The most frequently reported barrier reported by those who did not use SSCs was lack of practical training. The most frequent challenge reported by those using SSCs was difficulties in crown adjustment followed by aesthetic issues, and the most frequently reported advantage was that SSCs maintain the function and occlusion. The majority of respondents reported a need for more information and practical training in the use of SSCs, with hands-on course as their most frequently preferred education type. CONCLUSION: Although the value of SSCs for restoring young molars is recognized by Norwegian and Finnish dentists, SSCs are rarely used by general dentists. The majority of the respondents reported lack of training and materials and was interested in receiving more information and education.

Characterization and toxicity evaluation of air-borne particles released by grinding from two dental resin composites in vitro.

OBJECTIVE: The project aims to evaluate whether inhalation of particles released upon grinding of dental composites may pose a health hazard to dentists. The main objective of the study was to characterize the dust from polymer-based dental composites ground with different grain sized burs and investigate particle uptake and the potential cytotoxic effects in human bronchial cells. METHODS: Polymerized blocks of two dental composites, Filtek™ Z250 and Filtek™ Z500 from 3M™ ESPE, were ground with super coarse (black) and fine (red) burs inside a glass chamber. Ultrafine airborne dust concentration and particle size distribution was measured real-time during grinding with a scanning mobility particle sizer (SMPS). Filter-collected airborne particles were characterized with dynamic light scattering (DLS) and scanning electron microscopy (SEM). Human bronchial epithelial cells (HBEC-3KT) were exposed to the dusts in dose-effect experiments. Toxicity was measured with lactate dehydrogenase (LDH) assay and cell counting kit-8 (CCK8). Cellular uptake was observed with transmission electron microscopy (TEM). RESULTS: Airborne ultrafine particles showed that most particles were in the size range 15-35 nm (SMPS). SEM analysis proved that more than 80% of the particles have a minimum Feret diameter less than 1 µm. In solution (DLS), the particles have larger diameters and tend to agglomerate. Cell toxicity (LDH, CCK8) is shown after 48 h and 72 h exposure times and at the highest doses. TEM showed presence of the particles within the cell cytoplasm. SIGNIFICANCE: Prolonged and frequent exposure through inhalation may have negative health implications for dentists.

Restorative material choices for extensive carious lesions and hypomineralisation defects in children: a questionnaire survey among Finnish dentists.

AIM: This survey assessed Finnish dentists' treatment decisions and choices of restorative materials in selected paediatric dental patient cases, with special emphasis on stainless steel crowns (SSCs). METHODS: A questionnaire with patient descriptions and tooth photographs was e-mailed to members of Finnish Dental Society (n=3,747). The respondents were asked to choose their preferred treatment in cases describing 1) extensive occlusal carious lesion in a primary molar of a cooperative child; 2) an identical lesion, treated under dental general anaesthesia (DGA); and 3) a symptomatic first permanent molar with enamel hypomineralisation (consistent with Molar-Incisor Hypomineralization, MIH) and post-eruptive breakdown. Only responses from dentist treating children were included (final n=765). RESULTS: The majority (47.3%) would have preferred restoration of the extensive primary tooth caries in a normal setting using resin-modified glassionomer cement, and 4.3% by using SSC. The preference of SSC as treatment choice increased to 25.4% upon implementation of DGA. The majority would treat the symptomatic permanent MIH molar with a resin composite restoration (45.0%), while 10.5% suggested SSC. Compared to general dentists, paediatric dentists had a stronger preference for SSCs. CONCLUSIONS: Although the respondents emphasised patient cooperation, but also tooth prognosis and material strength behind their treatment decisions, SSC was an uncommon choice.

Treatment decisions regarding caries and dental developmental defects in children - a questionnaire-based study among Norwegian dentists.

BACKGROUND: Current knowledge on treatment strategies and choice of restorative materials when treating deep caries or severe dental developmental defects (DDDs) in young individuals is scarce. Therefore, the aim was to investigate Norwegian dentists´ treatment decisions and reasons for treatment choice when treating deep caries in primary teeth and severe DDDs in permanent teeth in children. METHODS: A pre-coded questionnaire was sent electronically to all dentists employed in the Public Dental Service (PDS) in Norway (n = 1294). The clinicians were asked about their background characteristics and how often they registered DDDs. Three clinical cases were presented to the dentists and asked to prioritize treatment options and reasons for their choice. RESULTS: After three reminders, 45.8% of the dentists answered. Most clinicians were general practitioners (96.3%), females (77.9%), under 41 year-olds (59.4%), graduated in 2001 or later (61.1%), and representing all regions of Norway. The respondents registered molar incisor hypomineralisation (MIH), other DDDs and dental fluorosis (DF) frequently, 523 (91.1%), 257 (44.8%) and 158 (27.5%), respectively. In case 1a with severe dental caries in a primary molar, the preferred treatment was resin-modified glass ionomer cement (RMGIC) (58.3%), followed by glass ionomer cement (GIC) (17.9%) and zinc oxide-eugenol (ZOE) (13.2%). Extraction, compomer or stainless steel crowns (SSC) were preferred by 0.9, 0.7 and 0.4%, respectively. In case 1b, which was identical to case 1a, but treated under general anaesthesia, the preferred treatment alternatives were RMGIC (37.1%), resin composite (RC) (17.6%) and GIC (17.2%). Extraction and SSC were chosen by 15.1 and 7.2%, respectively. In case 2, showing a severely hypomineralised and symptomatic first permanent molar, the dentists preferred RC (38.4%), followed by RMGIC (26.6%) and GIC (19.0%). Extraction and SSC were chosen by 8.7 and 5.4%, respectively. The treatment choices were not significantly affected by the dentists' background characteristics. The reasons for dentists' treatment decisions varied for each patient case; patient cooperation, prognosis of the tooth and own experience were the dominant reasons. CONCLUSIONS: A notable disparity in treatment choices was shown indicating that Norwegian dentists evaluate each case individually and base their decisions on what they consider best for the individual patient.

Dosimetric discrepancies caused by differing MLC parameters for dynamic IMRT.

Radiotherapy patients will from time to time be treated on another linac than originally planned due to service or logistical challenges. For patients treated with dynamic intensity modulated radiotherapy (IMRT), extra care should be taken to make sure the delivered dose remains as planned. Four linacs with the same type of dynamic multileaf collimator (MLC) were compared to find a general prediction of the potential dosimetric error caused by treating IMRT patients on another linac without recalculating the treatment plan. The MLC parameters, transmission and dosimetric leaf separation (DLS) were measured for all four linacs. The dynamic fields that were measured to find the DLS value were imported into the treatment planning system to compare the calculated and measured doses. Measured values of transmission and DLS were used directly in the calculations to obtain dose differences of less than 1% between the calculated and measured doses at the reference setup. The dosimetric discrepancy between the linacs was acceptable for all but one linac. Recalculation of the treatment plan therefore remains as standard procedure for this linac when a planned patient must switch linac during the course of treatment. The depth and field size dependences of the MLC parameters were also tested, finding dose differences of up to 4%.

Dosimetric verification of a dedicated 3D treatment planning system for episcleral plaque therapy.

PURPOSE: Episcleral plaque therapy (EPT) is applied in the management of some malignant ocular tumors. A customized configuration of typically 4 to 20 radioactive seeds is fixed in a gold plaque, and the plaque is sutured to the scleral surface corresponding to the basis of the intraocular tumor, allowing for a localized radiation dose delivery to the tumor. Minimum target doses as high as 100 Gy are directed at malignant tumor sites close to critical normal tissues (e.g., optic disc and macula). Precise dosimetry is therefore fundamental for judging both the risk for normal tissue toxicity and tumor dose prescription. This paper describes the dosimetric verification of a commercially available dedicated treatment planning system (TPS) for EPT when realistic multiple-seed configurations are applied. MATERIALS AND METHODS: The TPS Bebig Plaque Simulator is used to plan EPT at our institution. Relative dose distributions in a water phantom, including central axis depth dose and off-axis dose profiles for three different plaques, the University of Southern California (USC) #9 and the Collaborative Ocular Melanoma Study (COMS) 12-mm and 20-mm plaques, were measured with a diode detector. Each plaque was arranged with realistic multiple 125I seed configurations. The measured dose distributions were compared to the corresponding dose profiles calculated with the TPS. All measurements were corrected for the angular sensitivity variation of the diode. RESULTS: Single-seed dose distributions measured with our dosimetry setup agreed with previously published data within 3%. For the three multiple-seed plaque configurations, the measured and calculated dose distributions were in good agreement. For the central axis depth doses, the agreement was within 4%, whereas deviations up to 11% were observed in single points far off-axis. CONCLUSIONS: The Bebig Plaque Simulator is a reliable TPS for calculating relative dose distributions around realistic multiple 125I seed configurations in EPT.

Adapting the waterproof BMS-96 diode array for isodose determination of dynamic beams.

We report the application of the Schuster BMS-96 waterproof linear diode array for isodose determination of dynamic beams. The array recorded beam profiles correctly, while depth dose distributions of dynamic beams with large variations in dose rate were registered erroneously. The deviations could be eliminated by appropriate software modifications. Until the software is revised, true isodoses can be obtained by rescaling each individual profile to the depth dose curve as measured with a single ionization chamber. After the corrections presented in the paper, isodoses interpolated from these corrected data sets agreed with ionization chamber measurements within 1-2%.

Partially wedged radiation beams.

To increase dose homogeneity within certain radiotherapy targets, we defined a partially wedged radiation beam as a beam with wedge modification in one part of the field only. Partially wedged beams may be beneficial in cases with curved surfaces inside parts of the beam only, where they may compensate for missing tissue and/or for variations in depth to the target region. Possible sites suitable for partially wedged beams include urinary bladder and tangential breast irradiation. Customized partially wedged beams were delivered applying dynamic collimation techniques. Two different linear detector arrays, a semiconductor diode array and an ionization chamber array, were used independently in the same standard water tank to verify that the partially wedged beams were delivered according to the definition. Dose calculations of partial wedge fields were implemented in our treatment planning system and compared with the measured dose distributions. We re-planned a representative treatment plan for both advanced urinary bladder cancer and tangential breast irradiation using partially wedged beams. For both patients the target dose homogeneity was improved, and the doses to surrounding critical normal tissues were reduced.

Effects of high and low single dose irradiation on glioma spheroid invasion into normal rat brain tissue in vitro.

The effects of radiation on direction on directional migration in monolayer cultures and brain tissue invasion by two glioblastoma cell lines (D-54 MG, D-247 MG) were investigated. The Leksell Gamma Unit was the radiation source and invasion was registered in an in vitro invasion assay developed in our laboratory. As tumor spheroids and brain tissue aggregates were treated simultaneously in cocultures; the effects of radiation on the interaction between the two tissues could be investigated. Tumor spheroids from both cell lines retained their ability to invade and destroy normal brain tissue, even after irradiation with 47.6 Gy. However, while the D-54 MG tumor spheroids showed a dose-dependent reduction of invasion, tumor spheroids from the D-247 MG cell line did not. In addition, radiation produced a dose dependent inhibition of directional migration of cells from D-54 MG spheroids. A similar significant inhibition of directional migration was found in D-247 MG, but it was not dose-dependent. Transmission electron microscopy revealed a loosening of the neuropil in the brain tissue of irradiated cocultures. However, this structural change did not seem to affect the invasiveness of the tumor. In this preliminary study, irradiation could not prevent invasion of two different glioblastoma cell lines into fetal rat brain tissue. Further studies using the same technique may help to understand the influence of ionizing radiation upon the invasion process in gliomas.

Psychophysiological studies of a geographically defined population.

In the Berlevag project attemps have been made at using psycho-physiological and cognitive measures as indexes of psychiatric morbidity.--With skin conductance response, psychotics and neurotics showed signs of autonomic inhibition compared with conduct disorders and normal controls. All groups except psychotics showed cognitive effects in conditioning. No differences between the groups could be established for stereotype indexes, but the Berlevag sample appeared to have unusual high stereotypy indexes. With word associations the patient groups were markedly different from controls, with most deviations in psychotics and least deviations in conduct disorders.--A comparison of word associations in samples of the Oslo and the Berlevag populations suggested that the associative network was very similar in the two populations. There are differences with regard to verbal fluency, response types and reaction times.--It is unresolved whether these differences measure psychiatric morbidity or reflect a culture-dependent character of the word association test.