Accuracy of digital and film panoramic radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies

OBJECTIVES

To compare the accuracy of digital and film panoramic radiographs for determining (1) the position and morphology of mandibular third molars before surgical removal and (2) the prevalence of dental anomalies and pathologies.

METHODS

Three hundred and eighty-eight third mandibular molars were available for examination. Position and morphology of third molars observed on film radiographs and on digital panoramic images from five systems (DenOptix, DigiDent, Digora, Dimax2 and Orthophos Plus) were recorded by two observers and were compared with surgeons' findings at the time of the operation (gold standard). One observer further recorded the prevalence of dental anomalies and pathologies on both imaging modalities.

RESULTS

Few differences were found between the digital and film-based panoramic systems in the assessment of accuracy of position and morphology of mandibular third molars. The prevalence of dental anomalies and pathologies determined with the two modalities was roughly similar.

CONCLUSION

The five digital panoramic systems evaluated in this study were equally as useful for third molar treatment planning and diagnosis of dental anomalies and pathologies as conventional film-based panoramic radiographs.

Potencies of estrogenic compounds in in vitro screening assays and in life cycle tests with zebrafish in vivo

The objective of this study was to compare the estrogenic potency of environmental estrogens at two testing tiers: at the initial level of in vitro screening assays, and at the level of definitive fish reproduction tests in vivo. The in vitro tests included a recombinant yeast estrogen receptor (ER) assay, a competitive radioreceptor assay using the hepatic ER of carp (Cyprinus carpio), and assays on vitellogenin induction in cultured hepatocytes of rainbow trout (Oncorhynchus mykiss) and carp. In vivo, full life cycle tests with zebrafish (Danio rerio) were performed, using fertilization success as estrogen-sensitive reproductive endpoint. The test compounds included the natural estrogen 17beta-estradiol (E2) (only applied in the in vitro assays); the synthetic estrogen ethynylestradiol (EE2); and two xenoestrogens, 4-tert-octylphenol (OP) and bisphenol A (BPA). Among the in vitro assays, differences were observed in the relative ranking of the test substances, and in the absolute sensitivity (EC50 values), although the interassay differences of EC50 values were within one order of magnitude. The in vivo activity of the test compounds was not accurately predicted by the in vitro assays, with respect to neither sensitivity nor ranking. The in vitro assays tended to overestimate the relative potency of the xenoestrogens; i.e. the ratio between the activity of the reference compound, EE2, and that of the test compound. The best prediction of the in vivo fish test results was obtained from the recombinant yeast assay.

Prevalence of generalized anxiety at eight weeks postpartum

OBJECTIVE

This study investigated the prevalence and nature of generalized anxiety symptoms in women who were eight weeks postpartum.

METHOD

A community-based sample of 68 postpartum women completed an interview assessing generalized anxiety disorder and depression and a self-report measure of worry associated with concerns relevant to postpartum women.

RESULTS

Three women (4.4%) met DSM-IV criteria for generalized anxiety disorder, and an additional 19 women (27.9%) endorsed subsyndromal difficulties with generalized anxiety. Approximately one third of these women endorsed symptoms of depression. In contrast, only two woman met criteria for major depressive disorder.

CONCLUSION

Postpartum generalized anxiety has a higher prevalence than postpartum depression.

Why study rod cell death in retinal degenerations and how?

Age-related macular degeneration (AMD) is a main causes of severe visual impairment in the elderly in industrialized countries. The pathogenesis of this complex diseases is largely unknown, even though clinical characteristics and histopathology are well described. Because several aging changes are identical to those observed in AMD, there appears to exist an unknown switch mechanism from normal ageing to disease. Recent anatomical studies using elegant innovative techniques reveal that there is a 30% rod loss in normal ageing, which is increased in early AMD. Those and other observations by Curcio and co-workers indicate that early rod loss is an important denominator of AMD (Curcio CA. Eye 2001; 15:376). As in retinitis pigmentosa (RP), rods appear to die by apoptosis. Thus it seems mandatory to study the regulation of rod cell death in animal models to unravel possible mechanisms of rod loss in AMD. Our laboratory investigates signal transduction pathways and gene regulation of rod death in our model of light-induced apoptosis. The transcription factor AP1 is essential, whereas other classical pro- and antiapoptotic genes appear to be less important in our model system. Caspase-1 gene expression is distinctly upregulated after light exposure and there are several factors which completely protect against light-induced cell death, such as the anesthetic halothane, dexamethasone and the absence of bleachable rhodopsin during light exposure. A fast rhodopsin regeneration rate increased damage susceptibility. Our data indicate that rhodopsin is essential for the initiation of light-induced rod loss. Following photon absorption, there may be the generation of photochemically active molecules wich then induce the apoptotic death cascade.

Image quality of two solid-state and three photostimulable phosphor plate digital panoramic systems, and treatment planning of mandibular third molar removal

OBJECTIVES

The purpose was to evaluate image quality of two solid-state (charge-coupled device (CCD)) and three photostimulable phosphor (PSP) plate digital panoramic systems, and to assess their utility for treatment planning before mandibular third molar removal.

METHODS

433 patients were randomly allocated to five digital systems: Dimax2 and Orthophos Plus (both CCD systems) and DenOptix, DigiDent and Digora (all PSP systems). Image quality was evaluated in six regions on a 4-point scale by three independent observers. In addition, an oral surgeon evaluated image quality in the mandibular third molar region only as well as the utility of the image for treatment planning before removal of that molar.

RESULTS

Images from the DenOptix and DigiDent systems had a significantly lower overall quality than images from the Digora, Dimax2 and Orthophos Plus systems (P < 0.005). The oral surgeon's assessment of image utility resulted in rejection rates of 0% for Orthophos Plus, 2% for Digora, 8% for Dimax2, 12% for DigiDent and 14% for DenOptix images. The rates for the DigiDent and DenOptix images were significantly higher than those for the other systems (P < 0.001), and the rate for Dimax2 was significantly higher than that for Orthophos Plus (P = 0.002).

CONCLUSIONS

The quality of DenOptix and DigiDent digital panoramic images was found to be inferior to the quality found in images obtained with the Digora, Dimax2 and Orthophos Plus systems. Images from the Digora and Orthophos Plus systems were regarded to be the most useful for treatment planning before mandibular third molar removal.

Light damage susceptibility and RPE65 in rats

A sequence variation in the pigment epithelial protein RPE65 has been shown to correlate with RPE65 protein levels, rhodopsin regeneration kinetics and light damage susceptibility in different mouse strains. Here, we tested whether such a correlation can also be found in rats. We examined four rat strains for RPE65 protein levels and the Rpe65 gene sequence. In two strains, we additionally determined Rpe65 mRNA levels, rhodopsin regeneration and light damage susceptibility (LDS).RPE65 protein levels were higher in Lewis and Brown Norway rats compared to Wistar and Long Evans. The albino strains Wistar and Lewis were investigated further. Lewis had higher Rpe65 mRNA levels than Wistar. Sequence analysis of the coding region of the Rpe65 cDNA revealed no relevant sequence variations in the two strains. Content and regeneration of rhodopsin were comparable in both strains. However, Wistar rats were more susceptible to light damage than Lewis. We conclude that lower RPE65 protein levels in Wistar may have been caused by decreased gene expression and not by a sequence variation as suggested for mice. In rats, RPE65 may not be a limiting factor for rhodopsin regeneration. Since LDS in rats did not directly correlate with RPE65 protein levels and rhodopsin regeneration, other yet unidentified (genetic) factors may account for the susceptibility differences observed in rats.

[Transcatheter occlusion of the persisting arterial duct]

BACKGROUND

Transcatheter occlusion of the persisting arterial duct (PDA) is feasible using different techniques like coil-embolization (CE), Rashkind PDA occluder (Rash), Amplatzer Duct Occluder (ADO). Comparative studies with this devices in relation to the size of the PDA and the device are missing. Aim of this study was to evaluate the different systems at the own patient population.

PATIENTS AND METHODS

From 1993 to 12/2001 transcatheter occlusion was attempted in 92 patients aged 4,13 years (range 0,07 to 14,39 years) using CE, Rash or ADO. All patients received echocardiographic examinations 24 hours before and after intervention, after 3, 6, and 12 months and than yearly.

RESULTS

91/92 PDAs could be successfully closed by 97 interventions. There were 63 CE, 25 Rash and 9 ADO performed. Primary closure rate was 75 % for Rash, 80 % for ADO and 80,8 % for CE (n. s.) and after 6 months 88 % for Rash, 92,3 % for CE and 100 % for ADO (p < 0,001), although the size of the PDA increased significantly from CE (2,14 + 1,1 min) to Rash (3,2 +/- 1,3 min) to ADO (4,9 +/- 1,9 min) (p < 0.05). In 6/7 pts with residual shunts complete occlusion could be achieved by second intervention.

CONCLUSION

In dependency of the size of the PDA and the right choice of the occluder almost all PDAs are closable with transcatheter techniques.

Guided tissue regeneration in intrabony defects using an experimental bioresorbable polydioxanon (PDS) membrane. A 24-month split-mouth study

AIM

The comparison of the clinical, radiographic, and microbiological healing results in deep intrabony defects following GTR therapy with two different bioresorbable membranes in a prospective split-mouth design.

MATERIAL AND METHODS

31 pairs of contralateral intrabony defects were randomly treated with either an experimental Polydioxanon (PDS) membrane or a Polylactic acid (PLA) matrix barrier. After 6, 12 and 24 months, healing results were assessed using clinical examinations (REC, PPD, CAL, vertical relative attachment gain V-rAG), quantitative digital subtraction radiography (amount and area of bone density changes), and microbiological analysis.

RESULTS

Postoperative membrane exposures occurred in 14 PDS and 2 PLA treated sites. 6, 12 and 24 months p.o., both membranes provided a significant gain in CAL [median values: 6 months (PDS vs. PLA: 3.0 vs. 3.0 mm); 12 and 24 months (PDS vs. PLA: 4.0 vs. 4.0 mm)], which corresponded to a V-rAG of 57.1% (PDS) vs. 62.5% (PLA) after 24 months. PDS and PLA treated sites revealed significant bone density gain 6, 12 and 24 months after surgery. 38.8% (PDS) vs. 41.8% (PLA) of the initial defect areas showed bone density gain. While the gain in bone density was significantly greater in PDS than in PLA sites, neither CAL gain nor the area of bone density changes revealed significant differences. Microbiological culture revealed similar bacterial loads in PDS and PLA sites during the first 12 months.

CONCLUSION

This 24-month study indicates that the PDS and PLA membranes can provide similar favorable regeneration results in deep intrabony periodontal defects, although considerably more postoperative membrane exposures have to be expected in PDS treated sites.

Accuracy of caries detection with four storage phosphor systems and E-speed radiographs

OBJECTIVE

To evaluate the accuracy of caries detection using four intra-oral storage phosphor plate systems exposed with two different exposure times and one film system.

METHODS

Under in vitro and standardised conditions 365 approximal and 159 occlusal surfaces were radiographed using four storage phosphor plate systems: DenOptix, Cd-dent, Digora (blue and white plates) and one film system: Ektaspeed Plus. The plates were exposed twice with 10% and 25% of the time needed for the film. Four observers recorded approximal enamel/dentine and occlusal dentine caries using a five-point confidence scale. Caries presence was validated histologically and diagnostic accuracy of the systems by using ROC curve areas (Az).

RESULTS

The shorter exposure time for approximal caries, Digora(white)(Az=0.68) and Ekta Plus (Az=0.69) were significantly more accurate than the other systems (Az=0.64-0.65). For occlusal caries using the same exposure time, no significant difference was found between the digital systems (Az=0.76-0.77), which all showed to be significantly less accurate than Ekta Plus (Az=0.81). Using the longer exposure time for approximal caries, no significant difference was found between DenOptix (Az=0.68), Digora(blue) (Az=0.69), Digora(white) (Az=0.69) and Ekta Plus (Az=0.69) which were all significantly more accurate than Cd-dent (Az=0.65). For occlusal caries using the same exposure time, Digora(blue) (Az=0.81) was the most significantly accurate of the digital systems. When approximal caries was the diagnostic task, the longer exposure time resulted in significantly higher accuracy with the DenOptix and Digora(blue) systems but not with the Cd-dent and Digora(white) systems. For occlusal caries, the longer exposure time resulted in a significant improvement only with the Digora(blue) system.

CONCLUSION

For approximal caries using the longer exposure time, no significant difference in diagnostic accuracy was found between DenOptix, Digora(blue), Digora(white) and Ekta Plus which were all significantly more accurate than the Cd-dent. For occlusal caries using the longer exposure time, Digora(blue) was found to be the most accurate of the digital systems. The exposure time had an influence on the diagnostic accuracy with the DenOptix and Digora(blue) systems for approximal and with the Digora(blue) system for occlusal caries detection.

Evaluation of effect of 3D video glasses on perceived pain and unpleasantness induced by restorative dental treatment

Previous studies on modulation of anxiety, pain and unpleasantness have documented a positive effect of video glasses (I-Glasses, Virtual i-O, Seattle, USA) on the perceived pain and unpleasantness under different laboratory and clinical conditions. The aim of this study was to evaluate whether distraction induced by video glasses also had an effect on the perceived intensity of pain and unpleasantness during dental treatment. Pain and unpleasantness was evoked by the preparation (drilling) of a minor dental cavity (class I). Twenty-three patients (17 female and six male, age range 20-49 years) with a need for an occlusal dental restoration in two homologous teeth participated in the study. In this split-mouth design, the patient received the dental treatment wearing 3D video glasses and without video glasses (control situation) in a randomized order. The tooth cavities were prepared in accordance with conventional techniques after mounting the video glasses. The patient rated the intensity of pain and unpleasantness on 100 mm visual analogue scales (VASs) after preparation of the first cavity; immediately after, the opposite tooth was prepared and again the volunteer rated the intensity of pain and unpleasantness. The cavities were then filled using a routine composite technique. Eventually, the patient indicated whether she would prefer video glasses or not if she were to have another filling and what the expectations of the effect had been. Differences in VAS ratings in the video and control situation were tested by Student's t-test. There was no statistically significant effect on the perceived pain (p=0.90) or unpleasantness (p=0.39), but the majority (74%) of the patients would still prefer to wear video glasses if they were to have another dental filling, and 73% had expected a positive effect of the video glasses. These findings suggest that perceived intensity of dental pain is resistant to a simple distraction technique.

The effect of a new type of video glasses on the perceived intensity of pain and unpleasantness evoked by a cold pressor test

The aim of the study was to evaluate whether distraction induced by a new generation of video glasses (I-Glasses, Virtual i-O, Seattle, WA) has an effect on the perceived intensity of pain and unpleasantness. The effects of three-dimensional video, two-dimensional video, and no video glasses (control) were compared in two groups of healthy volunteers (13 males and 11 females) in a randomized, controlled trial. A cold pressor stimulus (1-2 degrees C chilled water) was used to induce experimental pain, and the volunteers rated the intensity of pain and unpleasantness on 100-mm visual analogue scales. The ratings were statistically compared using the Wilcoxon signed-rank test. Between the groups (males and females), there was a significant difference (P < .01) in the rating of unpleasantness in the three-dimensional video condition, while there were no significant differences between the genders in the other conditions (two-dimensional, control). Three-dimensional video provided a significant reduction in both pain and unpleasantness (P < .01) compared with the control condition in the male group. However, in the female group, there was a significant reduction in unpleasantness with two-dimensional video compared with the control (P < .05). This suggests that the use of distraction by means of video glasses is able to reduce the perceived intensity of pain and unpleasantness.

Influence of the validation method on diagnostic accuracy for caries. A comparison of six digital and two conventional radiographic systems

OBJECTIVE

To evaluate the influence of the validation method on the diagnostic accuracy and the relative comparison of eight radiographic systems for caries detection.

METHODS

Three hundred and thirty-eight approximal and 145 occlusal surfaces were radiographed under standardised conditions using six CCD-based sensor systems: MPDx (Dental/Medical Diagnostic Systems Inc., Woodland Hills, CA, USA), Dixi (Planmeca, Helsinki, Finland), Sidexis (Sirona, Bensheim, Germany), RVG(old) (Trophy, Paris, France, 1994 model), RVG(new) (Trophy, Paris, France, 2000 model) and Visualix (Gendex, Milan, Italy) and two film systems: Ektaspeed Plus and Insight (Eastman Kodak, Rochester, NY, USA). Four observers examined the radiographs for approximal and occlusal caries using a five-point confidence scale. The presence of caries was validated histologically and radiographically. Diagnostic accuracy was evaluated using ROC curve areas (A(z)).

RESULTS

For both approximal and occlusal caries the mean A(z) of the eight radiographic systems was significantly higher using radiographic than histological validation (P<0.001). Using histological validation for approximal caries, Dixi (A(z)=0.71) and Ektaspeed Plus (A(z)=0.7) were not significantly different, but Dixi was significantly more accurate than the other digital systems and the Insight film. Using radiographic validation for approximal caries, Ektaspeed Plus (A(z)=0.87) was significantly more accurate than Dixi (A(z)=0.82). Dixi was significantly more accurate than MPDx (A(z)=0.74), RVG(old) (A(z)=0.77), RVG(new) (A(z)=0.77) and Visualix (A(z)=0.76). Corresponding variations were found for occlusal caries depending on the validation method. Using histological validation, MPDx (A(z)=0.76) was significantly less accurate than Dixi (A(z)=0.81), Sidexis (A(z)=0.8), Ektaspeed Plus (A(z)=0.82) and Insight (A(z)=0.81). Using radiographic validation, MPDx (A(z)=0.83) was also significantly less accurate than RVG(old) (A(z)=0.89) and RVG(new) (A(z)=0.9).

CONCLUSION

A(z) obtained from radiographic validation was significantly higher than A(z) obtained from histological validation. Comparison of the diagnostic efficacy for caries of the eight radiographic systems was strongly influenced by the validation method. DOI: 10.1038/sj/dmfr/4600645

A comparison of the quality of root canal treatment in two Danish subpopulations examined 1974-75 and 1997-98

AIM

The aim of this study was to compare the quality of root canal treatment in two Danish subpopulations.

METHODOLOGY

Group 1 (358 patients) was examined 1974-75 and group 2 (244 patients) 1997-98. All patients were more than 20 years old. All had undergone a full-mouth radiographic survey. In root-filled teeth the following parameters were assessed: the quality of the coronal restoration or crown, the lateral seal of the root filling, the length of the root filling, and the periapical status. Chi-squared tests were used for the evaluation of differences between the groups.

RESULTS

In group 1 there were 975 endodontically treated teeth, in group 2 there were 753. In group 1 the majority of root-filled teeth were premolars, in group 2 the majority were molars (P < 0.001). The quality of coronal restorations (P = 0.35) and crowns (P = 0.68) did not differ significantly between the groups. In group 2 more teeth had adequately sealed root canals (P < 0.001) and adequate length of root filling (P < 0.001). More root-filled molar teeth had apical periodontitis (AP) than root-filled premolar and anterior teeth (P < 0.001).

CONCLUSIONS

Whilst the technical quality of endodontic treatment had improved during the last 24 years, basic differences between the populations prevented assessment of the impact of this change on disease frequencies. The study indicates that great care should be taken when comparing different patient populations, in particular more emphasis should be placed on the selection and description of study groups.

Impact of conventional tomography on prediction of the appropriate implant size

AIM

The purpose of this study was to evaluate the efficacy of conventional cross-sectional tomography in predicting the appropriate implant size.

METHODS

The implant length and width of 46 patients referred for single tooth implant treatment were determined presurgically by periapical + panoramic images (record 1) and after surgery by periapical + panoramic images + tomograms (record 2). These dimensions were compared with the dimensions of the implants actually installed (record 3), as well as the dimensions assessed to be the "appropriate" ones according to defined criteria for success (record 4).

RESULTS

In 70% of the cases, the implant length or width, or both, was changed after the tomogram was available. The implant dimensions determined with tomography were maintained at surgery in 87% of the cases. In only 33% of the cases did the implant size predicted without tomography correspond with the size of the installed implants. The agreement between records 2 and 3 was significantly higher than between records 1 and 3 (P < .001). Similarly, the agreement between records 2 and 4 was significantly higher than between records 1 and 4 (P < .001).

CONCLUSIONS

This study demonstrated that the use of tomograms increases the efficacy of periapical + panoramic images, with respect to the prediction of appropriate implant size, by a factor of 2.5. Therefore, conventional cross-sectional tomography is recommended for treatment planning before installation of single tooth implants.

New views on RPE65 deficiency: the rod system is the source of vision in a mouse model of Leber congenital amaurosis

Leber congenital amaurosis (LCA) is the most serious form of the autosomal recessive childhood-onset retinal dystrophies. Mutations in the gene encoding RPE65, a protein vital for regeneration of the visual pigment rhodopsin in the retinal pigment epithelium, account for 10-15% of LCA cases. Whereas previous studies of RPE65 deficiency in both animal models and patients attributed remaining visual function to cones, we show here that light-evoked retinal responses in fact originate from rods. For this purpose, we selectively impaired either rod or cone function in Rpe65-/- mice by generating double- mutant mice with models of pure cone function (rhodopsin-deficient mice; Rho-/-) and pure rod function (cyclic nucleotide-gated channel alpha3-deficient mice; Cnga3-/-). The electroretinograms (ERGs) of Rpe65-/- and Rpe65-/-Cnga3-/- mice were almost identical, whereas there was no assessable response in Rpe65-/-Rho-/- mice. Thus, we conclude that the rod system is the source of vision in RPE65 deficiency. Furthermore, we found that lack of RPE65 enables rods to mimic cone function by responding under normally cone-isolating lighting conditions. We propose as a mechanism decreased rod sensitivity due to a reduction in rhodopsin content to less than 1%. In general, the dissection of pathophysiological processes in animal models through the introduction of additional, selective mutations is a promising concept in functional genetics.

Predisposition to vasovagal syncope in subjects with blood/injury phobia

BACKGROUND

Most subjects with blood/injury phobia experience syncope or presyncope as part of the phobic response. We tested the hypothesis that these subjects have a constitutional autonomic dysregulation that predisposes them to vasovagal syncope during head-up tilt.

METHODS AND RESULTS

We studied 11 subjects (9 females, 2 males) who had a history of syncope or presyncope only in response to a blood or injury stimulus and 11 healthy matched controls (10 females, 1 male) without a history of syncope. Blood pressure (BP) and heart rate (HR) were measured during a 15-minute baseline period with subjects in the supine position and then during 45 minutes of head-up tilt to 70 degrees. Measurements at rest did not differ between the blood phobic and control subjects. During tilt, 9 (82%) of the 11 blood phobic subjects experienced presyncope or syncope, leading to termination of the study after 22+/-17 minutes of tilt. Only 1 (9%) of the 11 control subjects experienced presyncope (chi(2)=11.7, P=0.001). Hemodynamic responses to tilt were consistent with a vasovagal mechanism in the blood phobic subjects, with simultaneous decreases in BP and HR during tilt. During tilt, systolic BP fell by 21+/-15 mm Hg (P=0.001), and HR fell by 22+/-25 bpm (P=0.01). By contrast, BP and HR were very stable in the control group.

CONCLUSIONS

Subjects with syncope related to blood/injury phobia have an underlying autonomic dysregulation predisposing them to neurally mediated syncope, even in the absence of any blood or injury stimulus. Fainting related to these stimuli may in large part be due to dysfunction in neural circulatory control, which may secondarily lead to the phobia because of repeated syncopal events.

AP-1 mediated retinal photoreceptor apoptosis is independent of N-terminal phosphorylation of c-Jun

Apoptosis is essential for retinal development but it is also a major mode of cell loss in many human retinal dystrophies. High levels of visible light induce retinal apoptosis in mice and rats. This process is dependent on the induction of the transcription factor AP-1, a dimeric complex composed of c-Fos and c-Jun/JunD phosphoproteins. While c-Fos is essential, JunD is dispensable for light-induced photoreceptor apoptosis. Here we show that N-terminal phosphorylation of c-Jun, the other main partner of c-Fos in induced AP-1 complexes is not required for programmed cell death during retinal development in vivo and is also dispensable for photoreceptor apoptosis induced by the exogenous stimuli "excessive light" and N-nitroso-N-methylurea (MNU). Mice expressing a mutant c-Jun protein (JunAA) that cannot be phosphorylated at its N-terminus are apoptosis competent and their retina is not distinguishable from wild-type mice. Accordingly, Jun kinase, responsible for phosphorylation of wild-type c-Jun protein is at best only marginally induced by the apoptotic stimuli "light" and MNU. Complex composition of light-induced AP-1 complexes is similar in wild-type and JunAA mice. This shows that the mutant c-Jun protein can be part of the DNA binding complex AP-1 and demonstrates that induction of the DNA binding activity of AP-1 after light insult does not depend on N-terminal phosphorylation of c-Jun. Our results suggest that transactivation of target genes by phosphorylated c-jun/AP-1 is not required for MNU- or light-induced apoptosis of photoreceptor cells.

Experience of Norwegian general dental practitioners with solid state and storage phosphor detectors

OBJECTIVES

To evaluate the opinions of Norwegian dental practitioners regarding the use of solid state sensor and storage phosphor (SP) detectors for intra-oral radiography.

METHODS

A questionnaire received from 2199 dentists 309 (219 male, 86 female, four unknown) confirmed the use of digital radiography in their practices.

RESULTS

Sixty-one per cent of dentists used a SP and 35% a sensor system; four (1.3%) used both. Approximately 50% of dentists had experienced technical problems and 33% had needed repairs. Almost all dentists stored their images on the hard disk (>97%) and 81% made a daily back-up. More sensor than SP users found difficulty with the positioning holder. Two-thirds of dentists reported digital image quality was the same or better than film. More Digora (Soredex, Helsinki, Finland) users reported better image quality than Denoptix (Gendex, Milan, Italy) or Digident (Digident, Nesher, Israel) users. Mean reduction in exposure time was 55% (range 2-90%), although 17 dentists stated that no reduction was achieved. Approximately half of the sensor users also used film and 38% of the SP users. Film was used more often for bitewing examination by the sensor users (27%) than by the SP users (4%). Mean time saved by the sensor users was 36 min/day (range 10-120) and by the SP users 25 min/day (range 5-120).

CONCLUSIONS

The majority of dentists felt that digital image quality was the same or better than film and exposure and examination times were reduced. However, technical problems and repairs were common.

Decision criteria and characteristics of Norwegian general dental practitioners selecting digital radiography

OBJECTIVES

To evaluate Norwegian general dental practitioners' decision criteria and characteristics for choosing digital radiographic equipment.

METHODS

A questionnaire was sent to all dental practitioners in Norway (n = 3940). They were categorised on the basis of their responses as either a 'digital radiography' (DR) or 'non-digital radiography' (non-DR) dentist. Demographic, clinical, and electronic technology variables were recorded. Dentists ranked on a six-point scale their reasons for choosing or not choosing digital radiography. Their responses were analysed by logistic regression.

RESULTS

Two thousand, one hundred and ninety-nine dentists (56%) replied. Three hundred and nine (14%), (219 men, 86 women and four not stated) had chosen to use digital radiography. The logistic regression analysis revealed that gender, age and years in dentistry were not significant factors in determining their decision, whereas working in a private or group practice was. The number of computers in the practice was the most important of the electronic technology variables. The non-DR dentists strongly agreed that 'digital radiography is too expensive' and were 'satisfied with film'. The DR dentists strongly agreed that the 'use of chemicals can be avoided', 'patient dose is reduced', and 'archiving is facilitated'.

CONCLUSION

Working in a private or group practice or using multiple computers were significant factors in choosing digital radiography.

Prevention of photoreceptor apoptosis by activation of the glucocorticoid receptor

PURPOSE

Evidence has accumulated that excessive light exposure may promote age-related and inherited retinal degeneration, in which photoreceptor death by apoptosis leads to loss of vision. In the current study, the effect of elevated corticosteroid levels on light-induced apoptosis of photoreceptors was determined.

METHODS

Photoreceptor apoptosis was induced in retinas of BALB/c mice by exposure to diffuse white light. High levels of corticosteroids were induced, either endogenously (fasting-mediated stress) or by a single intraperitoneal injection of dexamethasone (DEX). Photoreceptor damage was assessed morphologically and by electroretinography. Glucocorticoid receptor (GR) and activator protein (AP)-1 activities were shown by Western blot analysis and electrophoretic mobility shift assay (EMSA) of retinal nuclear extracts.

RESULTS

Fasting and injection of DEX led to an activation of GR in the retina, as judged by its translocation to the nucleus of retinal cells. On induction of GR activity before light exposure, AP-1 activity, normally induced by damaging doses of light, remained at basal levels. Both treatments completely prevented photoreceptor apoptosis and preserved retinal function.

CONCLUSIONS

Activity of the transcription factor AP-1 is associated with light-induced apoptosis. In the current study, pharmacologic suppression of AP-1 activity protected against light damage. Inhibition of AP-1 activity may have occurred by the protein-protein interaction of GR and AP-1.

Frequency and distribution of endodontically treated teeth and apical periodontitis in an urban Danish population

AIM

The aim of this study was to investigate the prevalence of endodontically treated teeth and apical periodontitis (AP) in a Danish population.

METHODOLOGY

From Aarhus County 614 individuals were radiographically examined, and the frequency of endodontic treatment and periapical status of all teeth were assessed. The year of birth of the subjects ranged from 1935 to 1975. The chi-squared test was used to determine the significance of differences between males and females and amongst age and tooth groups for the following parameters: AP, the number of endodontically treated teeth, and the number of endodontically treated teeth with AP.

RESULTS

A total of 15 984 teeth were examined; of these 538 (3.4%) had AP and 773 (4.8%) had been endodontically treated. Of the endodontically treated teeth, 404 (52.2%) had AP. Females had more endodontically treated teeth than males; otherwise, no effect of gender was observed. Significantly more molars (P < 0.01) had been endodontically treated (8.1%) compared to premolars (5.4%) and anterior teeth (2.5%). The prevalence of AP in connection with molars was significantly (P < 0.01) higher (7.0%) than premolars (2.8%) and anterior teeth (1.5%). The prevalence of endodontically treated teeth and of teeth with AP gradually increased with age.

CONCLUSIONS

The average number of teeth, the number of teeth with AP and the number of teeth with endodontic treatment in Danish adults were comparable to findings in other European countries. The frequency of endodontically treated teeth with AP was found to be high compared to that demonstrated in other epidemiological studies.

Protective effect of halothane anesthesia on retinal light damage: inhibition of metabolic rhodopsin regeneration

PURPOSE

To determine whether the volatile anesthetic halothane protects against light-induced photoreceptor degeneration in the rodent retina.

METHODS

Albino mice and rats were anesthetized with halothane and exposed to high levels of white or blue light. Nonanesthetized animals served as controls. Retinal morphology was assessed by light microscopy, and apoptosis of photoreceptor cells was verified by detection of fragmented genomic DNA and in situ staining of apoptotic nuclei (TUNEL assay). Rhodopsin regeneration after bleaching was determined by measuring rhodopsin levels in retinas of mice or rats at different time points in darkness.

RESULTS

Halothane anesthesia reversibly inhibited metabolic rhodopsin regeneration and thus prevented rhodopsin from absorbing high numbers of photons during light exposure. Consequently, photoreceptors of mice and rats anesthetized with halothane were completely protected against degeneration induced by white light. In remarkable contrast, however, halothane anesthesia did not protect against blue-light-induced photoreceptor cell death.

CONCLUSIONS

After the initial bleach, halothane impeded photon absorption by rhodopsin by inhibiting metabolic rhodopsin regeneration. Apparently, the rhodopsin-mediated uptake of the critical number of photons to initiate white light-induced retinal degeneration was prevented. In contrast, halothane did not protect the retina against blue light. Blue light can efficiently restore functional rhodopsin from bleaching intermediates through a process termed photoreversal of bleaching. This process does not depend on the visual cycle via the pigment epithelium but nevertheless enables rhodopsin molecules to absorb the critical number of photons required to induce retinal degeneration.

Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching

PURPOSE

Acute white-light damage to rods depends on the amount of rhodopsin available for bleaching during light exposure. Bleached rhodopsin is metabolically regenerated through the visual cycle involving the pigment epithelium, or photochemically by deep blue light through photoreversal of bleaching. Because photoreversal is faster than metabolic regeneration of rhodopsin by several orders of magnitude, the photon catch capacity of the retina is significantly augmented during blue-light illumination, which may explain the greater susceptibility of the retina to blue light than to green light. However, blue light can also affect function of several blue-light-absorbing enzymes that may lead to the induction of retinal damage. Therefore, this study was conducted to test whether rhodopsin and its bleaching intermediates play a role in blue-light-induced retinal degeneration.

METHODS

Eyes of anesthetized rats and mice that did or did not contain rhodopsin were exposed to green (550 +/- 10 nm) or deep blue (403 +/- 10 nm) light for up to 2 hours. Rats with nearly rhodopsinless retinas were obtained by bleaching rhodopsin in animals with inhibited metabolic rhodopsin regeneration-that is, under halothane anesthesia. In addition, Rpe65(-/-) mice that are completely without rhodopsin were used to test the susceptibility to blue-light damage of a rodent retina completely devoid of the visual pigment. Effects of illumination on photoreceptor morphology were assessed 24 hours or 10 days thereafter by morphologic and biochemical methods.

RESULTS

Exposure to blue light resulted in severe retinal damage and activation of the transcription factor AP-1 in rats. In contrast, green light had no effect. When rhodopsin was almost completely bleached by short-term green-light exposure while metabolic regeneration (but not photoreversal) was prevented by halothane anesthesia, blue-light exposure induced distinct lesions in rat retinas. When both metabolic rhodopsin regeneration and photoreversal of bleaching were almost completely inhibited, blue-light exposure caused only very moderate lesions. When mice without rhodopsin were exposed to blue light, no damage occurred, in contrast to wild-type control mice.

CONCLUSIONS

Short time exposure to blue light has deleterious effects on retinal morphology. Because damage was observed only in the presence of the visual pigment, blue-light-induced retinal degeneration is rhodopsin mediated. Absorption of blue light by other proteins is not sufficient to induce light damage. Photoreversal of bleaching, which occurs only in blue but not in green light, increases the photon-catch capacity of the retina and may thus account for the difference in the damage potential between blue and green light.

The Rpe65 Leu450Met variation increases retinal resistance against light-induced degeneration by slowing rhodopsin regeneration

Excessive light can cause retinal degeneration and may be an environmental cofactor accelerating retinal dystrophies and age-related diseases. In rodent models, the light damage susceptibility (LDS) of the retina is determined genetically. In two mouse strains, with different degrees of LDS, a Leu450Met variation in the pigment epithelial protein RPE65 was shown recently to cosegregate with low LDS. Because light damage is rhodopsin-mediated, and RPE65 is essential for the regeneration of rhodopsin in the visual cycle, we analyzed this variation regarding rhodopsin metabolism and LDS in four mouse strains. We found that, in contrast to previous assertions, LDS does not correlate with the maximal retinal content of rhodopsin present after dark adaptation. Instead, LDS correlated positively with the kinetics of rhodopsin regeneration, which determine rhodopsin availability during light exposure. Light damage occurred after absorption of a threshold dose of photons and thus fast regeneration, as observed in those two strains having Leu at position 450 of RPE65, was correlated with the occurrence of photoreceptor apoptosis after short exposure. In contrast, mice with the Leu450Met variation of Rpe65 regenerated rhodopsin with slow kinetics and showed an increased resistance to light-induced retinal degeneration. In these mice, RPE65 protein levels were reduced by a post-transcriptional mechanism. F(1) hybrid mice, carrying one normal and one variant Rpe65 gene, had intermediate levels of the corresponding protein and showed intermediate rhodopsin regeneration kinetics and an intermediate LDS. Thus, none of the two variants of Rpe65 had a dominant effect.

Computer-automated caries detection in digital bitewings: consistency of a program and its influence on observer agreement

The aim of this study was to evaluate a decision-support, caries detection program and its influence on observer agreement in caries diagnosis. 130 patients were examined by digital bitewing radiography (RVG XL sensor, Trophy Radiologie Inc.). Fifty-four approximal surfaces (27 in premolars and 27 in molars) were selected by the author: 24 surfaces (9 in molars and 15 in premolars) scored as sound, 16 surfaces (9 in molars and 7 in premolars) scored as carious in enamel, and 14 surfaces (9 in molars and 5 in premolars) scored as carious in dentine. The Logicon Caries Detector (LCD) program (Logicon Inc., USA) was assessed by repeating the automated analysis ten times for each surface. The two most varying outcomes for lesion probability (Lp(min) and Lp(max)) were saved. Five observers scored the 54 surfaces independently as sound, caries in enamel or caries in dentine before and after the use of LCD. In more than one third of all surfaces the program indicated different lesion probability, from sound at Lp(min) to the presence of a carious lesion at Lp(max). The 5 observers changed their caries score after the use of LCD in a total of 31 surfaces (only 2 of these were in the same surface). Mean kappa value for inter-observer agreement for caries scores before the use of LCD was 0.47 (range 0. 39-0.61) and after LCD 0.48 (range 0.37-0.69). It was concluded that the automated caries detection program was not very consistent and provided different opinions on the caries status in a surface. Inter-observer agreement in caries diagnosis did not improve using the program.

Age-related macular degeneration. The lipofusion component N-retinyl-N-retinylidene ethanolamine detaches proapoptotic proteins from mitochondria and induces apoptosis in mammalian retinal pigment epithelial cells

10-20% of individuals over the age of 65 suffer from age-related macular degeneration (AMD), the leading cause of severe visual impairment in humans living in developed countries. The pathogenesis of this complex disease is poorly understood, and no efficient therapy or prevention exists to date. A precondition for AMD appears to be the accumulation of the age pigment lipofuscin in lysosomes of retinal pigment epithelial (RPE) cells. In AMD, these cells seem to die by apoptosis with subsequent death of photoreceptor cells, and light may accelerate the disease process. Intracellular factors leading to cell death are not known. Here we show that the lipophilic cation N-retinyl-N-retinylidene ethanolamine (A2E), a lipofuscin component, induces apoptosis in RPE and other cells at concentrations found in human retina. Apoptosis is accompanied by the appearance of the proapoptotic proteins cytochrome c and apoptosis-inducing factor in the cytoplasm and the nucleus. Biochemical examinations show that A2E specifically targets cytochrome oxidase (COX). With both isolated mitochondria and purified COX, A2E inhibits oxygen consumption synergistically with light. Inhibition is reversed by the addition of cytochrome c or cardiolipin, a negatively charged phospholipid that facilitates the binding of cytochrome c to membranes. Succinate dehydrogenase activity is not altered by A2E. We suggest that A2E can act as a proapoptotic molecule via a mitochondria-related mechanism, possibly through site-specific targeting of this cation to COX. Loss of RPE cell viability through inhibition of mitochondrial function might constitute a pivotal step toward the progressive degeneration of the central retina.

Gene expression in the mouse retina: the effect of damaging light

PURPOSE

High levels of visible light induce apoptotic cell death of photoreceptors, a process depending on the activation of the transcription factor AP-1. This suggests that regulation of gene expression might be important for light-induced photoreceptor cell death. We measured expression of AP-1 family members and of several apoptosis-related genes to test their potential involvement in photoreceptor apoptosis.

METHODS

Wildtype and c-fos-/- mice were exposed to low (roomlight) or high levels of visible light for up to two hours. Total RNA was prepared from isolated retinas during and after light exposure. Relative mRNA levels were determined semiquantitatively using either competitive or exponential RT-PCR.

RESULTS

Expression of c-fos-/- was upregulated by intense light as early as 15 min after lights on. Highest levels (6-fold induction) were detected at 2 h after lights off declining thereafter to basal levels 20 h after the end of exposure. c-jun mRNA was induced at 30 min after lights on and high expression levels (fourfold induction) persisted at least for 8 h. Similarly, expression of caspase-1 was six to 9-fold increased at 6 to 8 h after light exposure in wildtype but not in c-fos knockout mice. The latter mice are protected against light-induced photoreceptor apoptosis. Expression of other apoptosis-related genes (bcl-2, bcl-XL, bax, bad, caspase-3) was not affected by light exposure or the lack of c-Fos in knockout mice.

CONCLUSIONS

Expression of c-fos and c-jun mRNA is transiently induced by exposure to damaging light. Induced expression of c-jun persists longer than expression of c-fos. Among the apoptosis-related genes, only caspase-1 expression was upregulated by light exposure and Caspase-1 might therefore be involved in light-induced retinal degeneration.

Efficacy of interpersonal psychotherapy for postpartum depression

BACKGROUND

Postpartum depression causes women great suffering and has negative consequences for their social relationships and for the development of their infants. Research is needed to evaluate the efficacy of psychotherapy for postpartum depression.

METHODS

A total of 120 postpartum women meeting DSM-IV criteria for major depression were recruited from the community and randomly assigned to 12 weeks of interpersonal psychotherapy (IPT) or to a waiting list condition (WLC) control group. Subjects completed interview and self-report assessments of depressive symptoms and social adjustment every 4 weeks.

RESULTS

Ninety-nine of the 120 patients completed the protocol. Hamilton Rating Scale for Depression (HRSD) scores of women receiving IPT declined from 19.4 to 8.3, a significantly greater decrease than occurred in the WLC group (19.8 to 16.8). The Beck Depression Inventory (BDI) scores of women who received IPT declined from 23.6 to 10.6 over 12 weeks, a significantly greater decrease than occurred in the WLC group (23.0 to 19.2). A significantly greater proportion of women who received IPT recovered from their depressive episode based on HRSD scores of 6 or lower (37. 5%) and BDI scores of 9 or lower (43.8%) compared with women in the WLC group (13.7% and 13.7%, respectively). Women receiving IPT also had significant improvement on the Postpartum Adjustment Questionnaire and the Social Adjustment Scale-Self-Report relative to women in the WLC group.

CONCLUSIONS

These findings suggest that IPT is an efficacious treatment for postpartum depression. Interpersonal psychotherapy reduced depressive symptoms and improved social adjustment, and represents an alternative to pharmacotherapy, particularly for women who are breastfeeding.

Periapical status and quality of root fillings and coronal restorations in a Danish population

AIM

The aim of this study was to investigate the quality of endodontic and coronal restorations and the association with periapical status in a Danish population.

METHODOLOGY

A total of 614 randomly selected individuals (20-60+ years of age) from Aarhus County had a full-mouth radiographic examination. The quality of endodontic and coronal restorations and the periapical status of endodontically treated teeth were assessed by radiographic criteria. Root fillings were categorized as 'adequate' or 'inadequate' with regard to root filling length and lateral seal. Coronal restorations were categorized into 'adequate' and 'inadequate', defined by the absence or presence of radiographic signs of overhangs or open margins. Results were analysed statistically using the chi-squared test.

RESULTS

The total number of endodontically treated teeth was 773, and 52.3% had apical periodontitis (AP). Root-filled teeth with an adequate lateral seal had a lower incidence of AP than teeth with an inadequate seal (44.3% vs. 57.8%), and teeth with an adequate root filling length were associated with a better periapical status than teeth with inadequate length of the root filling (42.0% vs. 67.6%). Similarly, adequate coronal restorations were associated with better periapical status than inadequate restorations (48.0% vs. 63.9%). When both root filling and coronal restoration quality were assessed, the incidence of AP ranged from 31.2% (optimal quality) to 78.3% (all parameters scored as inadequate).

CONCLUSIONS

Inadequate root canal and coronal restorations were associated with an increased incidence of AP.

Reliability of visual examination, fibre-optic transillumination, and bite-wing radiography, and reproducibility of direct visual examination following tooth separation for the identification of cavitated carious lesions in contacting approximal surfaces

The aim of this study was to evaluate the diagnostic accuracy of visual, fibreoptic transillumination (FOTI), and bite-wing radiographic examination performed by 4 observers for the identification of cavitated carious lesions in contacting approximal surfaces, and to assess the inter-observer agreement with these methods and with direct visual examination conducted after tooth separation, the method used as validation for definitive determination of cavitation. A total of 338 unrestored approximal surfaces in 53 students were examined independently by 4 dentists using the diagnostic methods under study. The results from the diagnostic methods were compared with the results from the validation method for each observer. The sensitivities for identification of cavitated lesions using visual examination ranged from 0.12 to 0.50. For FOTI and radiography, the sensitivities ranged from 0.00 to 0.08 and from 0.56 to 0.69, respectively. The specificities exceeded 0.90 for all observers with all methods. Kappa values expressing inter-observer reproducibility were lowest for FOTI, followed by visual and radiographic examination. On the basis of these results, it was concluded that FOTI was the least reliable of the diagnostic methods tested. For the validation method, the inter-observer agreement was only 'substantial'. This implies that the method cannot be used as a validation for other diagnostic methods applied for the identification of cavitated carious lesions in contacting approximal surfaces. However, visual inspection after tooth separation may serve as a supplementary diagnostic tool to conventional visual and radiographic examination for clinical management of aproximal carious lesions.

Accuracy of radiographic detection of residual caries in connection with tunnel restorations

The aim of this study was to evaluate the diagnostic accuracy of radiographic examination for the detection of residual caries after tunnel preparation and filling with glass ionomer cement. Further, two different radiographic modalities were compared. Forty-five extracted human premolars and molars with clinical signs of approximal caries were selected for the study. The teeth were radiographed in order to identify surfaces with dentinal lesions suitable for tunnel preparation. Seventeen of the teeth had lesions that were as a minimum through the enamel and as a maximum into the outer half of the dentin (14 teeth = 1 lesion, 3 teeth = 2 lesions). Seventeen surgically removed third molars were thereafter included. These teeth were sound with respect to caries. The teeth were arranged in blocks with approximal contacts and radiographed using two image receptors: Ektaspeed Plus film (E) and the Digora (D) digital storage phosphor plate system. The 20 carious surfaces and 20 surfaces of the impacted teeth were prepared following the guidelines for the class II tunnel technique and filled with glass ionomer cement. The radiographic examination was repeated with both modalities after filling, and the approximal surfaces scored on the radiographs by 5 observers using the criteria: 0 = no filling, 1 = filling with residual caries, 2 = filling with no adjacent caries. All teeth except the unerupted third molars were sectioned, and the sections examined under the microscope. Residual caries was observed in 8 surfaces. On average, sensitivity was 0.25 for E and 0.32 for D, specificity 0.83 for E and 0.76 for D, positive predictive value 0.38 for E and 0.32 for D, and negative predictive value 0.75 for E and 0.77 for D. The differences between the two modalities were not statistically significant (p > 0.3). Based on the relatively small number of lesions in this study, it is suggested that radiography immediately after tunnel restoration cannot be recommended, as the diagnostic benefit from this examination seems to be minuscule.

Derivation of predicted No-effect concentrations for lindane, 3, 4-dichloroaniline, atrazine, and copper

Environmental risk assessment is a key feature of regulations controlling the placing of new, and the maintenance of existing, chemicals products in the market place. For example, European Commission Directive 93/67/EC on Risk Assessment for New Notified Substances and Commission Regulation (EC) No. 1488/94 on Risk Assessment for Existing Substances requires that risk assessments be carried out for new and existing substances in the European Community. The process of environmental risk assessment seeks to determine the balance of probability of species and communities being damaged by chemical releases. The process relies upon a valid estimation of a predicted environmental concentration (PEC) in relevant environmental compartments and a predicted no effect concentration (PNEC) below which the organisms present in that compartment are unlikely to be significantly affected. If the PEC exceeds the PNEC there is a potential for damaging effects to occur. This article focuses on the determination of PNECs for risk assessment. Methods for determining a PNEC described in OECD Monograph 26 (1989, Report of the OECD Workshop on Ecological Effect Assessment, Paris, France, have been applied to data derived for the four chemicals lindane, 3,4-dichloroaniline, atrazine, and copper in a series of collaborative research projects funded by the European Commission.

Normal values of M mode echocardiographic measurements of more than 2000 healthy infants and children in central Europe

OBJECTIVE

To obtain normal M mode (one dimensional) echocardiographic values in a substantial sample of normal infants and children.

DESIGN

Data were obtained over three years from a single centre in central Europe.

PATIENTS

2036 healthy infants and children aged one day to 18 years.

METHODS

In line with recommendations for standardising measurements from M mode echocardiograms, and using digital echocardiographic equipment, measurements were obtained of the following: right ventricular anterior wall thickness at end diastole, right ventricular end diastolic dimension, thickness of interventricular septum at end diastole and end systole, thickness of posterior wall of the left ventricle at end diastole and end systole, left ventricular dimension at end diastole and end systole, pulmonary and aortic valve diameter, and left atrial dimension.

RESULTS

Measurements are presented graphically on centile charts with respect to body surface area, and as tables with mean and 2 SD values for newborns in relation to body weight, and for infants and children in relation to body surface area. Best fitting regression equations are given for each measured variable, using the 50th centile values.

CONCLUSION

In comparison with previously published normal values, the presented charts and tables make it possible to judge echocardiographic measurements of a particular patient as normal or abnormal.

Reproducibility in the assessment of caries lesion behaviour: a comparison between conventional film and subtraction radiography

The purpose of this study was to compare reproducibility in the assessment of caries lesion behaviour in digital subtraction images and conventional radiographs. Ninety-seven pairs of conventional film bite-wings were included. The radiographs had been taken with a Kwik-Bite filmholder without further standardisation. The selection criterion was that at least one surface imaged in a bite-wing pair should show progresssion of a caries lesion from the first exposure to the second. The time interval between the bite-wings was 1-2 years. The radiographs were scanned into a personal computer and the two images from the same patient subtracted. Seven observers scored the subtraction images and the conventional films. The scale was based on no change/ change in surface appearance scored in the following categories: 0 = no change; 1 = development of a new caries lesion in enamel; 2 = development of caries lesion in enamel and dentine/progression of an existing enamel lesion into dentine/progression of a dentinal lesion further into dentine; 3 = development of secondary caries; 4 = new filling/change of filling/extension of filling. Cohen's kappa coefficients were calculated for intra- and inter-observer agreement for the two radiographic methods separately. The kappa value served as the statistical sampling unit for testing differences between the two methods (Wilcoxon's test for ranked pairs). The average intra-observer kappa value was 0.875 (range 0.775-0.958) for the subtraction images and 0.758 (range 0.560-0.890) for the conventional radiographs. The difference was statistically significant (p<0.05). For inter-observer agreement, the kappa values were lower than for intra-observer agreement. The average value was 0.678 (range 0.485-0.754) for the subtraction images and 0.701 (range 0.497-0.817) for the conventional radiographs (p>0.1). This study suggests a new way of comparing reproducibility in terms of kappa values between diagnostic methods in clinical studies where accuracy cannot be evaluated. The subtraction method may be useful in the assessment of caries lesion behaviour in the clinic.

Protection of Rpe65-deficient mice identifies rhodopsin as a mediator of light-induced retinal degeneration

Light-induced apoptosis of photoreceptors represents an animal model for retinal degeneration. Major human diseases that affect vision, such as age-related macular degeneration (AMD) and some forms of retinitis pigmentosa (RP), may be promoted by light. The receptor mediating light damage, however, has not yet been conclusively identified; candidate molecules include prostaglandin synthase, cytochrome oxidase, rhodopsin, and opsins of the cones and the retinal pigment epithelium (PE). We exposed to bright light two groups of genetically altered mice that lack the visual pigment rhodopsin (Rpe65-/- and Rho-/-). The gene Rpe65 is specifically expressed in the PE and essential for the re-isomerization of all-trans retinol in the visual cycle and thus for the regeneration of rhodopsin after bleaching. Rho-/- mice do not express the apoprotein opsin in photoreceptors, which, consequently, do not contain rhodopsin. We show that photoreceptors lacking rhodopsin in these mice are completely protected against light-induced apoptosis. The transcription factor AP-1, a central element in the apoptotic response to light, is not activated in the absence of rhodopsin, indicating that rhodopsin is essential for the generation or transduction of the intracellular death signal induced by light.

Digital imaging for dental caries

Laboratory studies show that digital intraoral radiography systems are as accurate as dental film for the detection of caries when a good-quality image is obtained, although more re-takes might be necessary because of positioning errors with the digital systems, particularly the charge-coupled device sensors. The phosphor plate is more comfortable for the patient than nondigital systems, and the dose can be further reduced with the storage phosphors. Cross-contamination does not pose a problem with digital systems if simple hygiene procedures are observed.

The retina of c-fos-/- mice: electrophysiologic, morphologic and biochemical aspects

PURPOSE

Mice without a functional c-Fos protein (c-fos-/- mice) do not exhibit light-induced apoptotic cell death of rods in contrast to their wild-type littermates (c-fos+/+ mice). To analyze the consequences of the absence of c-fos in the retina, we investigated whether the retinas of c-fos-/- mice have a reduced capacity to absorb and transduce light compared with c-fos+/+ mice.

METHODS

Retinal function was evaluated in dark-adapted mice by full-field electroretinograms (ERGs) over more than 6 log units of intensity. Retinal morphology was studied by light- and electron microscopy. Arrestin and the heat shock protein 70 (Hsp70) were detected by Western blot analysis. The rhodopsin content and the kinetics of rhodopsin regeneration were determined in retinal extracts.

RESULTS

Although the configuration of the ERGs was comparable in both groups of mice, c-fos-/- mice showed a marked variability in all quantitative ERG-measures with lower mean amplitudes, longer latencies, and a 0.9-log-unit lower b-wave sensitivity on average. Morphometry showed that c-fos-/- mice have 23% fewer rods on average, whereas the number of cones was comparable among c-fos+/+ and c-fos-/- mice. Arrestin levels appeared slightly reduced in c-fos-/- mice when compared with c-fos+/+ mice, whereas Hsp70 levels were comparable in both genotypes. The kinetics of rhodopsin regeneration were similar, but c-fos-/- mice had a 25% lower rhodopsin content on average.

CONCLUSIONS

Compared with c-fos+/+ mice, retinal function in c-fos-/- mice is attenuated to a variable but marked degree, which may be, at least in part, related to the reduced number of rods and the reduced rhodopsin content. However, c-fos does not appear to be essential for the ability to absorb photons, nor for phototransduction or the function of second-order neurons. The resistance to light-induced apoptosis of photoreceptor cells in c-fos-/- mice may result from the acute deficit of c-fos in the apoptotic cascade rather than from developmental deficits affecting rod photoreceptor function.

Development of methods for evaluating toxicity to freshwater ecosystems

This article presents a summary of a collaborative research program involving five European research groups, that was partly funded by the European Commission under its Environmental Research Program. The objective of the program was to develop aquatic toxicity tests that could be used to obtain data for inclusion at Level 2 of the Risk Evaluation Scheme for the Notification of Substances as required by the 7th Amendment to EC Directive 79/831/EEC. Currently only a very limited number of test methods have been described that can be used for this purpose and these are based on an even smaller number of test species. Tests based upon algae (Chlamydomonas reinhardi, Scenedesmus subspicatus, and Euglena gracilis), protozoa (Tetrahymena pyriformis), rotifera (Brachionus calyciflorus), crustacea (Gammarus pulex), and diptera (Chironomus riparius) were developed. The tests encompassed a range of end points and were evaluated against four reference chemicals: lindane, 3, 4-dichloroaniline (DCA), atrazine, and copper. The capacity of the tests to identify concentrations that are chronically toxic in the field was addressed by comparing the effects threshold concentrations determined in the laboratory tests with those determined for similar and/or related species and end points in stream and pond mesocosm studies. The lowest no-observed-effect concentrations (NOEC), EC(x), or LC(x) values obtained for lindane, atrazine, and copper were comparable with the lowest values obtained in the mesocosms. The lowest chronic NOEC determined for DCA using the laboratory tests was approximately 200 times higher than the lowest NOEC in the mesocosms.

[Therapeutic strategies in RP (retinitis pigmentosa): light at the end of the tunnel?]

Retinitis pigmentosa (RP) is a hereditary retinal dystrophy which leads to severe visual impairment or blindness and affects about 3.5/1000 of individuals in the industrial world. During the past decades, numerous animal models carrying mutations analogous to mutations in human RP have been studied to elucidate the molecular mechanisms leading to apoptotic photoreceptor cell death in this disease. Up to date, there is no effective treatment to influence the fatal outcome of RP. Recent progress in basic research promotes the development of new therapeutic strategies. In order to restore visual function in blind individuals, the development of electronic photoreceptor prosthesis is being investigated by several researchgroups. Other promising approaches are somatic gene therapy, the application of growth factors and/or pharmacological agents and the inhibition of photoreceptor cell death by interfering with the apoptotic pathway. However, a better understanding of the molecular events leading to cell loss due to photoreceptor apoptosis will be essential for the development of effective treatment.

c-fos controls the "private pathway" of light-induced apoptosis of retinal photoreceptors

White light (5 klux for 2 hr) induces apoptosis of rod photoreceptors in wild-type mice (c-fos(+/+)) within 24 hr, whereas rods of c-fos knock-out mice (c-fos(-/-)) are protected (). The range of this protection was tested by analyzing retinas of c-fos(+/+) and c-fos(-/-) mice up to 10 d after exposure to threefold increased light intensities (15 klux for 2 hr). In c-fos(-/-) mice, rods were unaffected, whereas they were destroyed in c-fos(+/+) mice. After light exposure, mitochondrial damage in rods was observed exclusively in c-fos(+/+) mice. Electroretinograms recorded 48 hr after exposure revealed a decrease of all components in c-fos(+/+) mice but indicated no light-induced loss of function in c-fos(-/-) mice. Thus, in c-fos(-/-) mice, light-induced apoptosis is blocked or its threshold is elevated more than threefold. Increased activity of the transcription factor activator protein-1 (AP-1) in retinas of light-exposed c-fos(+/+) mice indicated an acute contribution of AP-1 to apoptosis induction. AP-1 activity increased already during exposure and peaked approximately 6 hr thereafter, coinciding with the appearance of major morphological signs of apoptosis. Activated AP-1 mainly consisted of c-Fos/Jun heterodimers. In c-fos(-/-) mice, AP-1 activity remained unchanged, indicating that no other Jun- or Fos-family member could substitute for c-Fos. Like damaging light, N-methyl-N-nitrosourea (MNU) induced AP-1 containing c-Fos in c-fos(+/+) mice and did not induce AP-1 in c-fos(-/-) mice. In contrast to light, however, MNU induced apoptosis in rods of c-fos(-/-) mice. Thus, c-Fos is essential for a specific premitochondrial "private apoptotic pathway" induced by light but not for the execution of apoptosis induced by other stimuli.

The hypoalgesic effect of 3-D video glasses on cold pressor pain: reproducibility and importance of information

The first aim of the study was to evaluate whether it was possible to manipulate the distraction effect induced by 3-D video glasses on the perceived pain and unpleasantness of the subjects by giving them different information about the expected effect. Second, the study aimed to determine the reproducibility of the effect. Forty-five students enrolled, 39 students participated in the study (24 women and 15 men, median age 23 years, range 19-28 years) because 6 did not show up for the first trial, and 37 completed the study because 2 subjects did not show up for the second trial. The subjects were randomized into 3 groups, balanced with respect to age and sex, that received different information about the effect of 3-D video on pain and unpleasantness: the first group received positive information, the second group received neutral information, and the third group received negative information. Once assigned to a group, there were no crossovers between the groups. A cold pressor stimulus was used to induce experimental pain, and the volunteers rated the intensity of pain and unpleasantness on 100-mm visual analogue scales. A new generation of video glasses were used in the study. Each volunteer was exposed to the cold pressor test in 2 randomized trials (video and control) after the information was given, and the 2 trials were repeated in a second session after 4 weeks. There was no significant difference in the effect of video glasses on perceived pain (P = .74) nor on the perceived unpleasantness (P = .84) among the 3 information groups. The data were therefore pooled. The results of the pooled data showed a significant effect of 3-D video on perceived pain (P = .03) but not on unpleasantness (P = .18). After 4 weeks, the study was repeated, and there were no significant changes in the effect of video glasses. The median visual analogue scale scores were reduced in both the video and the control trials compared with the first session.

Long-term stability of jaw bone tuberosities formed by "guided tissue regeneration"

The aim of the present study was to evaluate whether bone tuberosities produced by GTR on the lateral surface of the mandibular ramus in rats are stable on a long-term basis. Thirty male 6-month-old albino rats of the Wistar strain were used in the study. Tissue flaps were elevated on the lateral aspect of the mandibular ramus. The periosteum was preserved (P+) on one side of the jaw while the bone was denuded (P-) on the other. A rigid, non-porous oval-shaped teflon capsule was placed on both sides with its opening facing the ramus. Six months following surgery, 10 rats were sacrificed and prepared for histology while the remaining 20 rats were subjected to a second operation during which the capsules were removed. Standardized radiographs, taken immediately before and after removal of the capsule and after 3, 6, 9 and 12 months, were subjected to planimetric measurements and subtraction radiography. Ten animals were sacrificed and prepared for histological analysis after 6 months following removal of the capsules and the remaining 10 animals after 12 months. Histology revealed that at 6 months after the placement of the capsules, 17 were completely filled with new bone. The remaining 3 capsules which were displaced exhibited only partial bone fill. The radiographic analysis revealed that after 6 months 98.6 +/- 7.6% (mean +/- SD) in average of the cross-sectional area created by the capsules was filled with new bone. Within 3 months after removal of the capsules a slight resorption of the new bone had occurred, thereby reducing the area of the bone tuberosities by 4 to 8%. No further resorption of the bone tuberosities took place from 3 to 12 months. These observations indicating that new bone produced by GTR is stable on a long-term basis, may question the general belief that non-functional bone will resorb over time.

Dot probe performance in two specific phobias

OBJECTIVES

The present study applied MacLeod, Mathews & Tata's (1986) dot probe attentional deployment methodology to individuals with specific phobias.

DESIGN

Attentional deployment towards spider-related, blood-related, positive, negative, and neutral words was examined.

METHOD

Individuals with either spider phobia (N = 13) or blood/injury phobia (N = 14) and non-anxious controls (N = 14) completed the dot probe attentional deployment task.

RESULTS

Individuals with specific phobias did not demonstrate an attentional bias towards phobia-related stimuli relevant to their particular fears.

CONCLUSION

Semantic-based information processing paradigms may not be sufficiently potent to demonstrate biased performance towards threatening stimuli in individuals with mild specific phobias who are otherwise healthy.

Behaviour of approximal carious lesions assessed by clinical examination after tooth separation and radiography: a 2.5-year longitudinal study in young adults

This study aimed to record and monitor over a 2.5-year period the occurrence of cavitation and lesion depth progression in approximal surfaces with radiographic caries at baseline. In total, 66 approximal sites (in 29 students), where at least one of the contacting surfaces had radiographic caries, were selected to take part in the study. A clinical examination undertaken before and after tooth separation in order to assess the presence/absence of cavitation was repeated every sixth month. To monitor lesion progression bite-wing radiographs were taken every sixth month, too. After each series of examinations, surfaces judged to be prone for disease progression were referred to operative caries treatment. In surfaces with radiographic dentinal caries at baseline the cavitation prevalence following tooth separation found at the various recall examinations ranged from 20 to 44%. In surfaces with radiographic enamel caries at baseline this prevalence ranged from 4 to 8% at the various recall examinations. In dentinal lesions found with an intact surface at baseline, the risk of cavitation development during the first 1.5-year period was assessed to be up to 22%. After this period no new cavitations were found in previously intact dentinal lesions. In intact enamel lesions the risk of cavitation formation was found to be 3% during the first 1-year period. After this period no new cavitations developed in previously intact enamel lesions. Three of 7 lesions, which showed radiographic caries progression from the outer one third to the inner two thirds of the dentine during the observation period, had intact surfaces at baseline. On the basis of these results it is recommended to re-examine carefully intact, dentinal lesions by repeated clinical examination after tooth separation and by radiography about 1-1.5 years after baseline.