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Purpose: Computer algorithms are often used for cardiac rhythm interpretation and are subsequently corrected by an overreading physician. The purpose of this study was to assess the incidence and clinical consequences of misdiagnosis of atrial fibrillation based on a 12-lead electrocardiogram (ECG)., Methods: We retrieved 2298 ECGs with the computerized interpretation of atrial fibrillation from 1085 patients. The ECGs were reinterpreted to determine the accuracy of the interpretation. In patients in whom the interpretation was incorrect, we reviewed the medical records to assess the clinical consequences resulting from misdiagnosis., Results: We found that 442 ECGs (19%) from 382 (35%) of the 1085 patients had been incorrectly interpreted as atrial fibrillation by the computer algorithm. In 92 patients (24%), the physician ordering the ECG had failed to correct the inaccurate interpretation, resulting in change in management and initiation of inappropriate treatment, including antiarrhythmic medications and anticoagulation in 39 patients (10%), as well as unnecessary additional diagnostic testing in 90 patients (24%). A final diagnosis of paroxysmal atrial fibrillation based on the initial incorrect interpretation of the ECGs was generated in 43 patients (11%)., Conclusion: Incorrect computerized interpretation of atrial fibrillation, combined with the failure of the ordering physician to correct the erroneous interpretation, can result in the initiation of unnecessary, potentially harmful medical treatment as well as inappropriate use of medical resources. Greater efforts should be directed toward educating physicians about the electrocardiographic appearance of atrial dysrhythmias and in the recognition of confounding artifacts.

The accuracy of surgical drilling guides was assessed for placement of zygoma implants. Six zygoma fixtures of length 45 mm (Nobel Biocare, Göteborg, Sweden) were placed in three formalin-fixed human cadavers using surgical drilling guides. The fabrication of these custom-made drilling guides was based on three-dimensional computerized tomography (3D-CT) data for the maxillary-zygomatic complex. The installation of the implants was simulated preoperatively using an adopted 3D-CT planning system. In addition, anatomical measurements of the zygomatic bone were performed on the 3D images. The preoperative CT images were then matched with postoperative ones in order to assess the deviation between the planned and installed implants. The angle between the planned and actually placed implants was < 3 degrees in four out of six cases. The largest deviation found at the exit point of one of the six implants was 2.7 mm. The present study showed that the use of surgical drilling guides should be encouraged for zygoma implant placement because of the lengths of the implants involved and the anatomical intricacies of the region.

Aim: To assess the accuracy of panoramic radiography and spiral or computed tomography for the localisation of the mental foramen., Materials and Methods: The distance from the alveolar crest to the mental foramen was measured from panoramic radiographs, spiral tomograms and CT scans. The same distance was measured during implant surgery using a specially designed caliper., Results: Panoramic radiography showed more deviation (+0.6 mm) from the perioperative measurements than either spiral or computed tomography (+0.4 and -0.3 mm respectively). The difference was significant (P<0.05). In general, distances were overestimated on the panoramic radiographs., Conclusions: Cross-sectional imaging techniques are recommended for the pre-operative planning of implants in the posterior mandible.

Objectives: To determine if slight variations in exposure will affect diagnostic image quality and absorbed radiation doses for digital and analogue panoramic radiography., Methods: Thermoluminescent dosimeters were placed in the thyroid gland, eyes, submandibular glands, parotid glands and skin of two human cadaver heads. Three different exposure settings were used: 70 kV, 120 mAs; 77 kV, 75 mAs; and 81 kV, 60 mAs. Subjective image quality was assessed using a phantom head. Storage phosphor (SP) images were printed on film and both analogue and SP images were assessed for their subjective image quality on a five-point rating scale. The results were statistically analysed using logistic regression analysis and chi(2) tests., Results: Highest organ doses were measured for the submandibular glands, followed by the parotid glands. Salivary gland doses tended to be higher at lower kV settings. Image quality was not statistically different for the different exposure settings. Imaging technique did not seem to influence diagnostic image quality, except for the periapical status of upper premolars where SP was better. The main reason for any differences appeared to be interobserver variation., Conclusions: Analogue and SP panoramic radiography performed equally well for subjective diagnostic image quality. No significant differences could be found at the exposure settings used in this study. Radiation doses were highest for the salivary glands, especially at lower kV settings.

For certain surgical procedures (e.g. placement of implants), an accurate localisation of the mandibular canal is of utmost importance to avoid injuries to the neurovascular bundle. The aim of the present study was to evaluate, on human fresh cadavers (n = 6), the accuracy of conventional spiral tomography for the localisation of the mandibular canal. By means of the Cranex TOME multifunctional unit (Orion Corporation Soredex, Helsinki, Finland), tomographic slices were taken at 3 different locations in the left posterior mandible (distal to the mental foramen). The mandibles were then sectioned at these 3 sites with a microtome. With a digital sliding caliper, the following 3 measurements were performed both on the tomograms and the bone sections at the three sites: 1) distance from the crest to mandibular canal, 2) overall bone height and 3) bone width. Overestimations of the distance to the mandibular canal (8/18) ranged from 1.05 to 0.10 mm and underestimations from 0.30 to 1.36 mm. The same number of over- and underestimations occurred for the bone height (1.14 to 0.14 mm and 0.15 to 1.40 mm, respectively). The bone width scored more overestimations (10/18), ranging from 1.40 to 0.12 mm, while underestimations ranged from 0.25 to 1.35 mm. From the present results, it is concluded that spiral tomography using the Cranex TOME multifunctional X-ray unit provides accurate information and sufficient detail for preoperative planning of implant placement in the posterior mandible.

Objectives: To compare the clinical efficacy of digital and conventional cephalometric imaging., Methods: Conventional and photostimulable phosphor cephalometric radiographs were obtained from three human cadavers at nine different exposure settings. Subjective image quality was assessed by six observers who evaluated six cephalometric landmarks. Organ doses were measured with TLDs and effective doses calculated., Results: Compared with conventional cephalometric images, digital images had a consistently better subjective image quality for all exposure settings which was significant (P<0.05) for all but two. Organ doses were comparable. Higher kV and lower mAs settings yielded the lowest effective dose, which was highly dependent on the position of the thyroid gland in the beam., Conclusion: Relatively small variations in exposure settings do not influence subjective diagnostic image quality of digital cephalometric radiographs. Higher kV and lower mAs settings have the lowest effective dose and should therefore be preferred.

The head of a human cadaver was positioned in a Cranex TOME multifunctional unit (Orion Corporation Soredex, Helsinki, Finland) to measure the organ radiation doses after tomographic examinations of the upper and lower edentulous jaw bone. Five consecutive examinations were carried out in the upper and lower anterior jaw regions to cover the entire frontal area, 2 in the upper and lower left premolar regions, and 3 and 4 in the upper and lower left molar regions, respectively. Each examination consisted of 4 slices with a 2 mm slice thickness. Thermoluminescent dosimeter chips were placed in the thyroid gland and bilaterally in the parotid and submandibular glands. Dosimetric measurements were repeated for the different tomographic examinations mentioned above. For spiral tomography in the maxilla, organ doses for both parotid glands were most elevated, while those for the thyroid glands were the lowest. Average doses per examination reached levels of 0.27 mGy for the right (OS) parotid gland with frontal tomography, and 3.89 mGy and 1.67 mGy for the parotid gland at tube-side (TS) for premolar and molar tomography. For the thyroid gland, a minimal dose of < or = 0.004 mGy was noticed for all examinations. For spiral tomography of the frontal area in the mandible, the OS parotid gland received the highest dose (0.77 mGy), while for an analysis of the premolar and molar areas, doses were more elevated for the TS parotid gland (1.22 mGy and 1.72 mGy, respectively). For the TS submandibular gland, organ doses were also raised, with values of 0.39 mGy for frontal, 1.31 mGy for premolar and 1.61 mGy for molar tomography. This study thus indicates that for conventional spiral tomographic examinations in the maxilla and the mandible, radiation doses for the TS submandibular and parotid glands were significantly more elevated than those to the thyroid gland. These values remain however below the organ doses previously reported for spiral CT involving both a full upper or lower jaw.

When planning to place implants in the posterior region of the maxilla, the location of the maxillary sinus floor is influencing the available bone height and the implant length chosen. The aim of the present study was to evaluate in vitro the spiral tomographic technique that could be used for pre-operative implant planning. Tomographs were taken of 6 dry human skulls using the Cranex Tome multifunctional unit (Orion Corporation Soredex, Helsinki, Finland). Three sites were selected in the left posterior maxilla and marked with gutta percha meaning a total of 18 sites (6 x 3 = 18) for interpretation. Bone height and width were measured on the tomographs and after sectioning also on the skulls. The values obtained from the measurements on tomographs were divided by an enlargement factor of 1.5 (as defined by the manufacturer) and then compared with those from the real measurements on the skulls. Real measurements were on average 0.24 mm (SD 0.19) lower than the tomographic measurements (P < 0.05). From the present results it could be concluded that spiral tomography using the recently developed Cranex Tome reveals sufficient information and detail for pre-operative planning of a limited edentulous region.

Stereognosis is the ability to recognise and discriminate forms. Oral stereognostic ability has been studied in different reports. The experimental design of the test is of primary importance as both the method used and the material applied may influence the results dramatically. The form, size and surface characteristics of the test piece, the presentation order, subject-related factors and the method of scoring all have their effect on the results. With regard to subject-related factors, ageing has a negative influence on stereognostic ability; gender is considered of no importance. Another influencing factor is dental status. A healthy natural dentition offers a very good oral stereognostic ability. Edentulous subjects usually show a decreased oral stereognostic ability, depending on the rehabilitation form. A number of questions have been addressed, especially with regard to the perception itself. Receptors mainly involved in oral stereognostic ability are located in various oral structures and form perception results from an association of more than one group of receptors. The following review tries to deal with these questions and attempts to provide clear guidelines for further research on oral stereognosis.

A stereognostic ability test was performed in 60 patients. Forty patients were rehabilitated by means of osseointegrated implants. One group consisted of 20 patients with fixed prostheses on implants in both the upper and lower jaws. The other 20 patients had a maxillary denture while in the mandible an overdenture was retained by means of two implants connected by a bar. They were compared to a group of 20 subjects (controls) with a non-restored natural dentition. For the stereognostic ability test, subjects had to recognise ten different test pieces by manipulating them with two antagonistic incisor teeth, avoiding any contact with other oral structures. Both response time and percentage accuracy of recognition were evaluated. The present findings indicated that subjects with an overdenture on implants did not score significantly different from those with an implant-supported fixed prosthesis. In contrast, subjects with teeth had a significantly better stereognostic ability. The percentage of correct responses was 52% for overdentures, 56% for fixed prostheses on implants and 75% for natural dentitions. From these results, it could be concluded that the stereognostic ability is impaired in subjects rehabilitated with osseointegrated implants by about one-third to one-quarter compared to subjects with natural teeth.