Frieda Gijbels

The subjective image quality of direct digital and conventional panoramic radiography.

Abstract One of the main advantages of digital imaging is the possibility of altering display options for improved image interpretation. The aim of the present study was to evaluate the subjective image quality of direct digital panoramic images and compare the results with those obtained from conventional images. Furthermore, the effect of various filter settings on image interpretation was assessed. Panoramic images were obtained with three different types of panoramic equipment (one direct digital and two conventional units) from three groups of 54 patients with a natural dentition in all quadrants. The first series of panoramic images consisted of 54 unprocessed digital images; conventional film images (n=108) comprised the second and third series. A final series consisted of the digital images treated with three different filters (”smoothening,””sharpening,” and ”contrast enhancement”). All images were scored randomly by four experts in oral radiology on a 4-point rating scale. The results showed a statistically significant difference in scorings between the conventional and digital panoramic units. The main reason for poor image quality appeared to be a combination of blurring and overlapping in the panoramic image. The premolar region in the upper jaw was the region where most additional radiographs were needed.

A split-mouth comparative study up to 16 years of two screw-shaped titanium implant systems.

INTRODUCTION Many studies have dealt with the clinical outcome of oral implants, yet none applied a randomized split-mouth design for a long-term follow-up of similar implant systems. AIM To evaluate two oral implant systems with different surface characteristics in a randomized split-mouth design and to radiologically analyse peri-implant bone level and density over an up to 16-year period. MATERIALS AND METHODS The study comprised clinical and radiographic records of 18 partially edentulous patients treated with both implant types randomly placed in either left or right jaw sides. Outcome was evaluated over time. RESULTS Clinical and radiographic parameters showed no significant differences over time for both systems. Ten years after implant placement, a significantly increasing peri-implant bone density was noted, while Periotest values were found to be significantly decreasing. Fifteen years after implant loading, mean bone loss was 0.02 mm (range -1.15 to 1.51; SD 0.45) for Astra Tech® implants (n=24) and 0.31 mm (range -0.98 to 2.31; SD 0.69) for Brånemark® implants (n=23). CONCLUSIONS The study failed to demonstrate significant differences in the outcome of the peri-implant bone for two implant systems with different surface characteristics. The marginal bone level around oral implants changed <0.5 mm after 15 years of loading.

Radiation doses of indirect and direct digital cephalometric radiography

Aim The aim of this study was to measure organ doses and calculate the effective dose for indirect and direct digital cephalometric exposures.Material and methods Indirect digital cephalometric exposures were made of a Rando® phantom head using a Cranex Tome® multipurpose unit with storage phosphor plates from Agfa and the direct digital (Charge Coupled Device, CCD) exposures were made with a Proline Ceph CM® unit. Exposure settings were 70 kV and 4 mAs for indirect digital exposures. Direct digital exposures were made with 70 kV, 10 mA and a total scanning time of 23 s. TLD700® dosemeters were used to measure organ doses, and the effective doses were calculated with (effective dosesal) and without inclusion of the salivary glands. A pilot study was carried out to compare diagnostic image quality of both imaging modalities.Results Effective doses were 1.7 μSv for direct digital and 1.6 μSv for indirect digital cephalometric imaging. When salivary glands were included in the calculation, effective dosessal were 3.4 μSv and 2.2 μSv respectively. Organ doses were higher for direct digital imaging, except for the thyroid gland, where the organ doses were comparable. Diagnostic image quality of indirect and direct digital cephalometric images seemed comparable.Conclusion Effective dose and effective dosesal were higher for direct digital cephalometric exposure compared with indirect digital exposure. Organ doses were higher for direct digital cephalography. From preliminary data, it may be presumed that diagnostic image quality of indirect and direct digital cephalometric images are comparable.

Is there a relation between local bone quality as assessed on panoramic radiographs and alveolar bone level

The aim was to explore the relation between radiographic bone quality on panoramic radiographs and relative alveolar bone level. Digital panoramic radiographs of 94 female patients were analysed (mean age, 44.5; range, 35–74). Radiographic density of the alveolar bone in the premolar region was determined using Agfa Musica® software. Alveolar bone level and bone quality index (BQI) were also assessed. Relationships between bone density and BQI on one hand and the relative loss of alveolar bone level on the other were assessed. Mandibular bone density and loss of alveolar bone level were weakly but significantly negatively correlated for the lower premolar area (r = -.27). The BQI did not show a statistically significant relation to alveolar bone level. Radiographic mandibular bone density on panoramic radiographs shows a weak but significant relation to alveolar bone level, with more periodontal breakdown for less dense alveolar bone.

Subjective image quality of digital panoramic radiographs displayed on monitor and printed on various hardcopy media.

The subjective image quality of panoramic radiographs shown on a diagnostic computer monitor were compared with professional direct thermal prints and with common inkjet prints on different paper qualities. Indirect digital panoramic radiographs were obtained from 15 patients. The images were printed with a direct thermal printer in their original format. Afterwards, these were loaded in an imaging software programme (Microsoft Photo Editor) and assessed both on computer monitor and inkjet prints on transparency, glossy, satin and regular paper. Five observers assessed subjective image quality for different regions and anatomical landmarks on a 5-point rating scale. Data were statistically analysed and inter- and intra-observer performances were calculated. Best image quality was obtained with direct thermal prints, followed in descending order by panoramic images viewed on the monitor, inkjet prints on transparencies, glossy paper, satin paper and finally regular paper. The differences were significant except for monitor images versus direct thermal prints, inkjet-transparencies and inkjet-glossy images and inkjet-satin versus inkjet-glossy images. The subjective image quality of indirect digital panoramic images is different for images shown on the computer monitor and for printed images depending on both the printer and paper type used.