Biomedical subjects

I P Sewerin

Publications and source records attributed to I P Sewerin.

11 recordsLinked to original sources

PubMed1997

Accuracy of radiographic diagnosis of peri-implant radiolucencies--an in vitro experiment.

The absence of a peri-implant radiolucency on radiographs is used as a criterion for implant success. The purpose of the present study was to evaluate the accuracy of diagnosing peri-implant radiolucencies using an experimental model. Astra Tech fixtures were inserted into 20 bony specimens. Later, the fixtures were removed and the prepared cavities were enlarged in 2 steps. The specimens were radiographed under strictly standardized circumstances in the 3 stages ("press-fit" = simulated osseointegration, and "0.1 mm space" and "0.175 mm space" = simulated connective tissue layer). All specimens were radiographed with 2 vertical angulations (0 degree and 15 degrees). Ten observers read the radiographs and evaluated bone-implant relationship on a 5-point scale. The interobserver agreement was low. Specificity was remarkably low, and sensitivity was moderate. A significant difference in diagnostic accuracy was found for 0.175 mm peri-implant-space compared to 0.1 mm space. The diagnostic accuracy was found to be highest for 0.175 mm peri-implant space specimens. It is concluded, that radiography seems to be an unreliable method for diagnosing peri-implant spaces, although accuracy improved at increasing space widths. Strict orthogonal projection angles did not improve diagnostic accuracy.

Alveolar Bone Loss↗

PubMed1997

Base and fog densities of fresh Ektaspeed Plus dental X-ray films.

Previous findings with regard to base and fog density of Ektaspeed Plus dental X-ray films have shown increased values compared with Ektaspeed and Ultra-Speed films, but the results are contradictory. The purpose of the present study was to measure base density, using 10 different fixing solutions, and fog density, using 10 different developing solutions at temperatures varying from 16 to 30 degrees C. The 10 developers tested were intended for manual (three), semiautomatic (three), and automatic (four) processing. Base densities were nearly identical for all fixing products (range, 0.190-0.192). One group of six developers showed quite stable fog values for all temperatures (range, 0.190-0.259), whereas another group (four developers) showed increased values at increasing temperatures (range, 0.395-0.438 at 30 degrees C). It is concluded that base density is within the limits of ISO standards for most fixing products but that some developers result in fog densities that are above ISO standard limits at high temperatures.

Automation↗

PubMed1995

Artefacts due to static electricity in a dental school.

The diagnostic usefulness of radiographs is diminished by errors of film handling, and retakes mean increased radiation doses. Avoiding artefacts due to static electricity is part of a quality assurance programme. The number of types of artefacts originating from static electricity in the Department of Radiology, School of Dentistry, Copenhagen, were recorded over a five-week period with low temperatures and low air humidity. During the period 3137 intra-oral and 638 extra-oral films were processed by seven assistants and a number of trainees. A total of 48 artefacts on 47 extra-oral films was observed. The artefacts were classified into four types. Only one case of classical 'lightning' was found, while nine were of a hitherto undescribed type ('animals' or 'cactus flowers'). The most common type appeared as dots arranged in straight lines; their origin was obscure, but it was suspected that they were caused by the processing machine. The one typical 'lightning' case occurred on a Status-X film, consistent with the theory that friction may be a causative factor. Although individual frequencies varied, all the radiography assistants and trainees were associated with the artefacts recorded.

Artifacts↗

PubMed1994

Clinical testing of the Ultra-Vision screen-film system for maxillofacial radiography.

The Ultra-Vision screen (Du Pont, Towanda, Pa.) contains a yttrium tantalate phosphor-emitting ultraviolet light and eliminates the crossover effect. Increased resolution has been proven in vitro and the purpose of the present study was to test these findings in a clinical situation. Fifteen pairs of skull radiographs were produced with the use of Du Pont Ultra-Vision Rapid screens and Kodak Lanex (Eastman Kodak, Rochester, N.Y.) screens both belonging to speed class 400. Objects were a cadaver head, a 3M phantom head (3M Corp., St. Paul, Minn.), and patients who were serially radiographed as controls in a dental implant study. The radiographs had identical densities, but contrast was varied deliberately. Twelve observers judged the radiographs blindly. Ninety-two percent of the ratings with respect to resolution favored the Ultra-Vision system. However, great doubt was expressed regarding contrast. The agreement between the observers was tested by a Cochran's Q test. The results confirm that the Ultra-Vision system exhibits an improved resolution compared with the Lanex system. Ultra-Vision is recommended whether improved resolution of the radiographs or an expected reduced patient dose is preferred.

Dental Implants↗

PubMed1993

Prototype system for archiving and transmitting digitized radiographs.

A prototype system for archiving and transmitting digitized dental radiographs is described. The system uses a CCD video camera, IBM compatible personal computer with a frame-grabber and a high resolution VGA monitor. All archived images were compressed lossless by a factor of about 3. Digitized radiographs were archived together with their exposure data and assembled in an examination with a unique identifier and date of examination, together with the patient's history and reason for radiological examination. A radiological report with a list of differential diagnoses could be attached. Each examination could contain 50 digitized radiographs which could be converted to a tagged image file (TIFF) and printed halftone with a laser printer. Users of the system could receive examinations from the network-server and share the images in a local area network.

Humans↗

PubMed1990

Errors in radiographic assessment of marginal bone height around osseointegrated implants.

Radiographic assessment of marginal bone height is included in longitudinal control of osseointegrated implants. Previous studies have revealed a mean annual loss of less than 0.1 mm. The purpose of the present study was by means of an experimental model to analyze the influence upon alveolar bone height measures around osseointegrated implants of buccolingual bone dimensions as well as angulations of fixture axis to central X-ray beam. Brånemark titanium implants were inserted into acrylic test blocks simulating alveolar ridges of various widths. 0.2 mm steel wires visualized buccal and lingual bone margins. Standardized radiographs were obtained by stepwise variation of projection angles. Separation of the wire images varied from 0.1 mm (buccolingual width 5 mm and 1 degree angulation) to 4.8 mm (width 13 mm and angulation 20 degrees). In clinical cases distortion of buccal and lingual bone margins may result in overestimation of bone heights. The degree of overestimation is influenced by the buccolingual position of the fixture. Strict parallelism between fixture axes and film plane is essential to obtain valid results using single films.

Alveolar Process↗

PubMed1989

Radiographic control of fixture-abutment connection in Brånemark implant technique.

In the treatment with osseointegrated implants ad modum Brånemark a radiographic control of the fixture-abutment connection is recommended. The purpose of the present study was to analyze the possibilities of detecting incomplete connection by radiography using the recommended technique. In an experimental model the influence of film density, orientation of the fixture hexagon, angulation between film plane and fixture axis, leakage width, and partial connection were analyzed. Slits of 0.05 mm were detectable under optimum projection conditions. On the other hand, slits of 0.1 mm were obscured even at deviations of 5 degrees. A number of factors, e.g. low density level and "unfavorable" orientation of the hexagon in relation to the X-ray beam, reduce the possibilities of detecting slits. It is concluded that in clinical cases a demonstration of incomplete fixture-abutment connection by the use of the recommended radiographic technique radiography to some extent is fortuitous, and that radiographic control has certain limitations.

Dental Abutments↗

PubMed1987

Mechanically induced images on dental x-ray film.

The appearance on processed x-ray film of images due to mechanical manipulation (bending, pressure, biting, etc.), as well as the influence of a number of other factors (degree and direction of bending, protective effect of film packet, etc.), was studied. A variety of very dissimilar images was produced. Some appeared as plus density artifacts, others as minus density artifacts. A critical influence on the nature of the image was observed with manipulation of film that was unexposed or was exposed before or after manipulation. The emulsions on the two sides of the film base responded differently to different types of manipulation. Forces exerted on the unprotected film (in the darkroom) induced images different than corresponding forces exerted through the film packet.

Pressure↗

PubMed1987

Radiology in the management of impacted teeth.

Radiographic examination is of principal importance in the diagnosis and management of impacted teeth. The examination has several purposes: verification, analysis of anatomy, inclinations, relation to adjacent structures etc., and assessment of complications. Fundamental radiographic methods are projections at right angles, horizontally or vertically angulated views, and stereoscopy. A detailed interpretation in three dimensions is essential for proper diagnosis and prognosis as well as for planning surgical interventions.

Adult↗

PubMedDate not supplied

Estimation of angulation of Brånemark titanium fixtures from radiographic thread images.

Identity of film positioning and of X-ray beam angulation is essential for valid comparisons of marginal bone height around osseointegrated implants. The purpose of the present study was to analyze the possibilities of estimating fixture angulation in relation to film plane from the threads of Brånemark fixtures. 10 observers compared 62 images of fixtures with angulations ranging from 0 degrees to +/- 15 degrees with a set of reference radiographs. Out of 620 recordings, 29% were right, and 71% differed by greater than or equal to 1 degree. The observers distinguished with great accuracy between negative and positive angulations. 81% of the recordings differed by 2 degrees or less. It is concluded that the threads of Brånemark fixtures are helpful in controlling the identity of serial radiographs of implants. The test circumstances were ideal compared to clinical cases, and it is possible that accuracy will be less in patient cases.

Dental Implantation, Endosseous↗

PubMedDate not supplied

Comparison of radiographic image characteristics of Brånemark and IMZ implants.

A Brånemark standard titanium implant and an IMZ plasma flame spray-coated implant were radiographed experimentally under standardized circumstances. Angulations in relation to film plane and central X-ray as well as rotations around the implant's longitudinal axis were varied. The influence of implant architecture on image density and image pattern was analyzed and images of the two types of implants were compared. The Brånemark implant is asymmetric and exhibits only radiographic burnout in its apical area. The 4 vertical apical cuts cause very distracting images and leave the impression that the implant is conical. It is possible to evaluate angulations with great accuracy from the thread profile, but there are limited possibilities for estimation of rotational stages. The IMZ implant shows symmetric images in any projection. The 4 vertical slits cause a disturbing burnout in the central part of the implant in certain views, and radiographic images are very inconstant. Possibilities of estimating angulation and rotation are varying. Differences in radiographic image characteristics are supposed to influence diagnostic yield as they affect the possibilities of identifying osseointegration radiographically and of controlling image identity in serial radiography.

Acrylic Resins↗