International Poster Journal of Dentistry and Oral Medicine, 03/1999

Objective: Common practice in the statistical comparison of imaging instruments with limited reproducibility consists in the seperate estimation of the instruments' reliabilities. However, as soon as one of the imaging methods under consideration underlies item-specific bias (which has to be expected for many clinical imaging procedures), this approach will end in severe errors in reliability computation and the corresponding erroneous clinical conclusions. This paper seeks to point out this effects and to illustrate a more appropriate model for the comparison of instrumental reliabilities. Material and Methods: A reliability model is adjusted for item--specific bias. Its application is illustrated by the comparison of twice repeated x-ray based cephalometry versus twice repeated non-ivasive orthodontic video imaging in 50 children; the posterior face height is used for illustration. Results: The proposed model allows to detect remarkable inferiority of the video-based imaging system as compared to the x-ray based standard. Analysis using seperate estimation would result in even adverse conclusions and falsely establish video imaging as a more reliable and thus superior diagnostic method. Conclusion: The reliabilities of clinical imaging methods have to be adjusted for possible item-specific bias to avoid the result of erroneous superiority of a diagnostic novum. Parole chiave: digital dental radiography, CCD sensor, storage phosphor, dose reduction

Organotypic cultures have been used to study epithelial cell behavior for many years. Although current techniques produce multicellular epithelium that is able to differentiate, they lack properly organized basement membrane zone (BMZ). The aim of this study was to develop an organotypic culture method that better mimics the three dimensional morphology of interdigitating rete ridges and connective tissue (CT) papillae and conserves the BMZ. Bovine tongue mucosa was chosen for the raft donor and incubated with cold 1 M sodium chloride solutions for 4 days to separate the epithelial tissue from the BMZ and underlying CT matrix. Level of separation was studied by immunohistochemical staining of beta 1 and beta 4 integrins, laminin-1 and -5, type IV and VII collagen, tenascin, fibronectin, and heparan sulfate proteoglycan. After the separation, integrins were found exclusively at the basal cells of separated epithelium while other components of the BMZ were localized in the CT side suggesting that the separation occurs at the level of the lamina lucida. Rafts were rinsed several times with cell culture medium and used for growth organotypic cultures of human keratinocytes. Keratinocytes were cultured submerged in keratinocyte growth medium for 6 days after which the cultures were raised to air-liquid interface for up to 30 days. Cultures were terminated first after 5 days and weekly thereafter. Frozen sections were prepared and used for routine histology and immunohistochemistry (IHC). Stratification of keratinocytes was evident already after 5 days although the number of cell layers increased with time. Often more than 15 cell layers resembling normal epithelial histology were present. Keratinocytes in these raft cultures were found to express beta 4 integrins against the preexisting basement membrane components. In addition, human keratinocytes deposited their own basement membrane molecules, particularly laminin-1 and -5, on the preexisting bovine matrix. This culture model seems to mimic normal epithelium including the BMZ and is potentially useful for multiple applications for studies on epithelial cell behavior in vitro. Parole chiave: cell-culture, organotypic, HaCat, basement membrane, differentiation

The usage of gloves in dentistry has increased greatly over the last ten years and this highlighted certain problems when they have been worn extensively. While skin irritations and allergies caused by latex proteins and accelerators have been the main focus of attention, dental materials such as disinfectants have also become known as a source of skin reactions. This study was performed to evaluate the permeability of various gloves by ethanol. The tip of the middle finger of ten glove brands (natural latex gloves (NLG) powdered or unpowdered, powdered vinyl and synthetic elastomer) was exposed to 5 ml of a hand disinfectant (Desderman TM). After a penetration time ranging from 2 minutes to 8 hours the permeation of Desderman was detected with a gas chromatograph (F45, Perkin-Elmer). Only one component of the disinfectant (ethanol) could be detected to have gone through the gloves. After only 2 minutes the vinyl glove and after 10 minutes all glove types were permeated. Natural latex gloves of a higher price showed a tendency to a lower rate of leakage and the synthetic elastomer (Biogel Neotech TM) was the only one with a significantly lower penetration after even 2-8 hours. Parole chiave: digital dental radiography, CCD sensor, storage phosphor, dose reduction

Multiresistant pathogens cause increasing problems in the therapy of nosocomial infections and post-surgical. A rational and restricted use of peri-operative antiinfective prophylaxis is recommended. In a prospective study in 260 patients who underwent surgery at the head and neck at the university hospital Mainz from July to Oktober 1998 the incidence and severity of post-surgical infections was analysed. Adequate microbiological procedures were performed. The diagnosis of an infection was defined clinically and was compared to the microbiologic findings. Laboratory findings were documented to identify systemic infections (eg. SIRS, Sepsis) from localised wound infections. In nearly all cases an antiinfective prophylaxis with a ß-lactam, cephalosporin or clindamycin was administered. 65 out of 260 patients (25%) showed clinical signs of infection. 12 of 260 (5%) were classified as nosocomial infections. Clinically documented infections: 1) Abszesses 50 of 50 (100%), 2) combined intra- and extraoral tumor resections 10 of 49 (20%) 3) dental surgical procedures 6 of 68 (9%), 4) non-contaminated extraoral procedures 1 of 15 (7%) 5) trauma patients 1/47 (2%) 6) malformations of the head and neck (cleft lip palate n=17, orthognatic surgery n=14) no infections. In only 50% of the patients with abszesses a pathogen was isolated, in the other groups the rate of microbiologically documented infections was above 80%. In all the groups nearly half of the isolated pathogens were Gram negative. The results show, that for certain surgical procedures of the head and neck (Trauma, orthodontic surgery, cleft lip palate) routine prophylaxis should not exceed a single dose administration. In contrast patients with risk factors (cancer patients) should receive a broad spectrum antiinfective prophylaxis to prevent nosocomial infections in this group. Parole chiave: digital dental radiography, CCD sensor, storage phosphor, dose reduction