Dentine-bonded resin composite (Retroplast) for root-end filling: a prospective clinical and radiographic study with a mean follow-up period of 8 years.

AIM: To evaluate treatment outcome after using a resin composite (Retroplast, RP) in combination with a dentine-bonding agent (GLUMA) as root-end filling material after 1 year as well as after more than 5 years (final examination). Also, the influence of various pre-, intra- and postoperative factors on the treatment outcome was studied. METHODOLOGY: All patients (87) undergoing root-end resection consecutively treated by root-end filling with RP on an incisor, canine, pre-molar, or first molar (87 teeth, 118 roots) were initially enrolled in the study. RP was applied on the entire resected surface that was prepared to a slightly concave shape and after conditioning with EDTA and GLUMA. The treatment outcome involving subjective, clinical and radiographic parameters was evaluated after 1 year and at the final examination. A total of 27 patients (36 roots) were excluded from the study because of unavailability of follow-up (19) and extraction of the operated tooth for reasons other than failed surgery (8). Consequently, 60 patients (82 roots) were included in the final material. The mean follow-up period at the final examination was 8 years (range: 6.5-9 years). RESULTS: The radiographic evaluation at the final examination revealed that 77%, 5%, 7% and 11% of the treated roots were characterized by complete, incomplete, uncertain and unsatisfactory healing, respectively. A total of 95% of the roots classified as completely healed at the 1-year control were also completely healed at the final examination. Two roots (5%) showing complete healing at the 1-year control revealed unsatisfactory healing at the final examination because of displaced or lost RP-filling. Moreover, 60% of the roots with uncertain healing at the 1-year control demonstrated complete or incomplete healing at the final examination. The classification according to subjective, clinical and radiographic parameters revealed that 78% of the teeth were characterized by a successful treatment outcome at the final examination. Evaluation of the influence of various pre-, intra- and postoperative factors on the treatment outcome revealed that the radiographic classification at the final examination was exclusively influenced by the radiographic classification at the 1-year control (P < 0.001). CONCLUSIONS: The present long-term study indicates that RP can be used for root-end filling with a successful treatment outcome.

A prospective, randomized, comparative clinical study of resin composite and glass ionomer cement for retrograde root filling.

OBJECTIVE: To compare the clinical and radiographic treatment outcome of retrograde root filling with either dentin-bonded resin composite (Retroplast, RP) or glass ionomer cement (Chelon-Silver, CS). STUDY DESIGN: A prospective, randomized clinical study of 134 consecutive patients with indication of retrograde root filling of an incisor, canine, premolar, or first molar. Either RP or CS was chosen at random as retrograde filling material. Either material was applied onto the entire resection surface after prepared slightly concave. This preparation technique makes a sealing of the entire resection surface possible and prevents marginal contraction gaps during polymerization. A total of 122 patients were available for 1-year follow-up. RESULTS: After 1 year the proportion of successful cases was significantly higher in the RP group (73%) than in the CS group (31%) (p<0.001). Doubtful healing with a need for a longer observation period was seen in 17% of the RP cases and 19% of the CS cases. The proportion of failures in the RP group (10%) was significantly lower than that in the CS group (50%) (p<0.001). Most of the unsuccessful CS cases failed due to loosening of the retrograde filling. CONCLUSIONS: Dentin-bonded RP applied onto the entire, slightly concave resection surface is a predictable apical sealant characterized by a high success rate. In contrast, retrograde root filling with CS results in an unacceptably high failure rate due to insufficient bonding strength to the concave resection surface.

[Health consequences of the Chernobyl accident]. / Helbredsmaessige konsekvenser af reaktorulykken i Tjernobyl.

The Chernobyl accident in 1986 has been and still is the subject of great interest. Journalistic reports often contain exaggerations and undocumented statements and much uncertainty about the true consequences of the accident prevails in the population. This article reviews the current literature with the focus on reports from official commissions and documentation in the form of controlled studies. The fatal deterministic consequences comprise about 30 victims. The most important outcome is a marked increase in the incidence of thyroid cancer in children and adolescents in the most heavily contaminated area. Furthermore, pronounced psychosocial problems are dominant in the population of the contaminated area. Other significant and documented health consequences are not seen.

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.

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.

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.

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.

Marginal tissue response adjacent to Astra Dental Implants supporting overdentures in the mandible.

The aim of this study was to evaluate the marginal tissue response adjacent to implant supported overdentures. Twenty edentulous patients had 2 Astra Dental Implants placed in the canine region of the lower jaw. New overdentures were retained by individual ball attachments in 11 patients and by a bar attachment in 9 patients. Periodontal registrations were recorded 0 months, 6 months, 12 months and 24 months after the overdentures were inserted. One of the 40 fixtures was lost at the stage of abutment connection. No fixtures were lost during the 2- to 4-year observation period and no fixtures showed any periodontal signs of failure. At the 2-year examination, no pocket depths adjacent to the implants exceeded 4 mm and no bone loss exceeded 3 mm. The mean annual bone loss was less than 0.2 mm during the first 2 years. The preliminary results from this limited study were promising and showed that two osseointegrated Astra Dental Implants could successfully retain an overdenture in the lower jaw. However, long-term observation is needed for a definitive evaluation of this treatment concept.

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.

Identification of dental implants on radiographs.

In the future, dentists will more frequently encounter patients who have dental implants. To use radiographs to identify implants that were previously inserted by other dentists, dentists have to be familiar with the detailed morphology of different products and types of fixtures as well as with the principles for formation of their radiographic images. In the present study, radiographic images of ten common dental implants were analyzed. Images varied with viewing angles. The influences of surface structures, such as threads, cuts, holes, perforations, and flutes, are demonstrated.

[A comparison of two methods for pre-operative radiographic examination in treatment with oral implants in the anterior mandibular area]. / En sammenligning af to metoder til praeoperativ røntgenundersøgelse ved behandling med osseointegrerede implantater i underkaebens frontregion.

Insertion of osseointegrated implants in the anterior mandibular region for retaining a removable denture represents a treatment, which is cheap for the patient and surgically uncomplicated. Bone height measures from two radiographic examinations 1) panoramic radiographs and 2) lateral tangential views, were compared. Radiographs from 20 patients were analyzed. The vertical height of the mandible was measured in the midline as well as in the cuspid region on the panoramic radiographs and the tangential views ("maximum" bone heights). The mean maximum bone heights were higher on tangential views in both regions. On the tangential views the inclinations of the future implants were estimated and the part of the alveolar ridge having a width less than 5 mm, which is the minimum width for housing an implant, was compiled. The resulting height ("effective bone height") was calculated. In 10% of the cases the effective bone height was equal to the maximum height, and in 90% it was smaller. The over-estimation varied between 0 mm and 15.3 mm. It is concluded that panoramic radiographs are unreliable for evaluating bone height in planning insertion of oral implants in the anterior mandibular region. They give no information about form and width of the bone. Tangential views reveal the true morphology of the mandible as seen in a cross-section, and offer an opportunity for calculating the effective bone height at disposal for oral implants.

Radiographic image characteristics of Brånemark titanium fixtures.

In the interpretation of radiographs showing oral implants a thorough knowledge of their radiographic image is essential. The purpose of the present study was to describe the radiographic image of the Brånemark titanium standard fixture, and to analyze the influence of rotation of fixture in the jawbone as well as angulation of central X-ray beam in relation to longitudinal fixture axis. Especially the influence upon the radiographic image of the thread system, the apical cylindrical perforation, and the four apical vertical cuts is considered.

[Depiction of oral implants on radiographs]. / Fremstilling af orale implantater på røntgenbilleder.

An enormous number of products and types of oral implants exists. In identification of implants previously inserted by other dentists radiography is essential. The radiographic images of 14 fixtures were analyzed and explained based on experimental exposures under standardized circumstances. In particular was the influence of different viewing angles due to rotational position of the fixture described. It is concluded that any of the metallic fixtures studied possesses macrostructures which will lead to a unique radiographic image making it possible to recognize it on radiographs. On the other hand the images will vary widely depending on rotational stage of the fixture why a thorough knowledge of the detailed architecture of the implants is necessary.

[Tangential projection for depiction of the anterior regions of the jaws performed with the dental X-ray set]. / Tangentielle røntgenoptagelser af front-regionen udført med dentalrøntgenapparat.

The tangential projection represents an extraoral projection which with success can be performed with the dental X-ray set. The film is placed lateral to the angle of the mouth in a vertical position level with either the maxilla or the mandible. If a view of the midline is wanted the film is placed parallel with the sagittal plane; if e.g. the canine region is of interest the film is angulated. The central X-ray is directed horizontally and perpendicularly to the film passing (as a tangent) the anterior surface of either the maxilla or mandible. The beam area used for periapical projections is ideal also for this projection. The tangential projection is indicated as a supplemental projection for three-dimensional localization of e.g. supernumerary teeth in the maxillary anterior region and for the buccolingual position of an impacted canine. It is also very useful in combination with frontal projections in the planning of insertion of dental implants. According to the Danish legislation it is not allowed to use the dental X-ray set for extraoral projections unless intensifying screens are used. However, the Danish Institute of Radiation Hygiene has accepted tangential projections using dental X-ray films and omitting intensifying screens in edentulous patients due to their better resolution, which is of particular importance in the planning of implant insertion.

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.

[Leaded screens for protection of the body against scattered radiation in intraoral radiography]. / Brug af hageskaerm til beskyttelse af kroppen mod spredt stråling ved intraorale röntgenoptagelser.

The use of a protective leaded shield as an alternative to leaded aprons and leaded neck collars for reduction of body doses originating from scattered radiation in intraoral radiography is discussed. The shield is stiff and has a U-shaped form fitting the neck of the patients and is kept in position by the patient himself. During exposure the shield is pressed against the patient's neck and kept in close contact with the inferior border of the mandible in a horizontal position. Three products of shields are described, all having lead equivalents of 0.5 mm. The protection of the thyroid gland is of maximum efficiency. Measurements of absorbed doses have shown the shield to have a protective effect equal to leaded aprons in cranial body regions, while gonadal doses are a little higher. Upper extremities are always protected by a shield, while many patients keep their hands and arms upon and not under an apron. Shields are easy to handle for the staff, hygienic, and cheaper than an apron. They can hardly be damaged and leaks following handling will not occur as for aprons. Leaded shields have recently been accepted as alternative to leaded aprons by the Danish National Institute of Radiation Hygiene.

Sources of noise in digital subtraction radiography.

In 17 patients, three identical radiographic examinations were performed for the lower premolar-molar region, by two examiners at one visit and by one examiner again approximately 3 months later. Recordings were performed with a newly developed device. The radiographs were converted to digital images in the following way: (1) video camera recording of the radiograph obtained at first visit by the first examiner (A), (2) copying of the numeric image of this radiograph (B), (3) repeated video recording of this radiograph (C), (4) video recording of the radiograph obtained at first visit by the second examiner (D), and (5) video recording of the radiograph obtained after 3 months (E). Subtractions were performed between the images: B - A, C - A, D - A, and E - A. The standard deviation of the histogram for the distribution of gray shades in the subtraction images was used to evaluate noise in the image. The standard deviation was 1.3 between B - A, 2.8 between C - A, 4.0 between D - A, and 4.1 between E - A. Physical noise originating from the video camera and the analog-to-digital conversion process thus constituted the major part of noise seen in subtraction images performed between radiographs recorded with a time interval. This indicates that reproducible recordings could be performed with the present device, which, in combination with a subtraction program able to correct for some geometry and density differences, may aid the use of subtraction radiography in clinical trials.

Performance for obtaining maximal gain from a program for digital subtraction radiography.

The aim of this study was to evaluate the effect on subtraction image quality of number of a) gray shades sampled during camera recording, and b) reference points positioned in the two images to be subtracted. Intraoral radiographs were obtained in each of 12 patients, one at 0 degrees and one at 15 degrees horizontal angulation in a standardized recording procedure. The radiographs were videorecorded twice sampling 1) 160-180 and 2) 200-220 shades of gray. The 0 degrees radiographic image was digitally copied. Subtractions were performed between the identical (0 degrees/0 degrees) and the non-identical (0 degrees/15 degrees) radiographs from both gray shade samples after positioning 5, 10, 15, and 20 reference points, respectively, in each of the images to be subtracted. The standard deviation in the subtraction image histogram was used as the test parameter for image quality. No differences existed between image quality obtained from the radiographs sampled using 160-180 and 200-220 shades of gray (P greater than 0.05). The standard deviation fell continuously, the more reference points were positioned in the images. For the 0 degrees/0 degrees images the difference was statistically significant between the 5 and 10 point images (P = 0.045) while for the 0 degrees/15 degrees images differences existed between 5 and 10 point images (P = 0.077) and the 10 and 15 point images (P = 0.048). The precision of reference point positioning as evaluated in the two identical images was satisfactory, the divergence being on average 1.4 pixels.(ABSTRACT TRUNCATED AT 250 WORDS)

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.