Effect of x-ray angulation on radiographic periodontal ligament space width.

The aim of this study was to set up a model for quantitating a change in radiographic PDL width on variation of x-ray angulation within anticipated clinical limits. Four incisor and 4 molar sites of 6 human skulls were radiographed at varying angulation. Horizontal angulation changes were made over a 12 degrees range, in 3 degrees increments. Vertical angulation change was in one 10 degrees increment. Baseline radiographs were taken with the x-ray beam perpendicular to a buccal tooth surface in a horizontal direction and perpendicular or 10 degrees off the perpendicular in a vertical direction. The radiographs were converted to digitized images and PDL width measurements made utilizing a mouse-driven computer program. The mean PDL width differences between all possible horizontal and vertical combinations (n = 45) were compared with the mean of those obtained from differences observed in PDL width measurements on replicate baseline radiographs. Mean PDL width differences for incisor locations were statistically different from the mean baseline PDL width difference; posterior PDL width difference showed no statistical variation from the mean baseline PDL width difference. For radiographs taken within the range expected under clinical conditions, a significant change in PDL width may be observed in incisor locations. Posterior sites may not exhibit this significant change due to the anatomy of the region which may reduce the clarity of the radiographic image.     

Vertical angulation of the X-ray beam and radiographic diagnosis of secondary caries

The purpose of this study was to assess to what extent angulation of an X-ray beam could affect the quality of diagnoses of caries adjacent to restorations with different radiopacities. Amalgam and composite class II restorations with and without secondary caries were done in extracted teeth. The teeth were radiographed using four different vertical angulations -0, 5, 10, and 15 degrees. Eight dentists diagnosed caries lesions on these radiographs. The best diagnostic outcome was found for the composite restorations radiographed at 10 degrees vertical angulation. Diagnosis was generally better for lesions marginal to composites compared to amalgams. The quality of secondary caries diagnosis in connection with amalgam was not significantly affected by variations in vertical angulation from 0 up to 15 degrees.     

Effect of x-ray beam vertical angulation on radiographic alveolar crest level measurement

Utilizing intraoral radiographs of human skulls taken at known vertical angulation, we have demonstrated that expression of the crest level as a distance between cej and the crest is as accurate as a ratio of bone height to root length. The degree of inaccuracy of either of these measures is related to the magnitude of the angular deviation of the x-ray beam from 90 degrees. Angular deviation can be estimated from calculation of a cusp height score (ratio of lingual cusp height to buccal cusp height x 100). Based on the analysis of cusp height scores it was determined that the x-ray beam angulation for posterior bitewings ranged between 90 degrees and 80 degrees whereas for posterior periapicals the angulation range was between 90 degrees and 70 degrees. Therefore, it is recommended that, for longitudinal studies of bone height, measurements of the crest to cej distance, particularly in the region of the molars, be made utilizing bitewing radiographs. For the premolar and incisor regions, deviation of the vertical angulation of an x-ray of up to 20 degrees from a 90 degrees baseline resulted in little, if any, change in crest level by either one of the two measures used. An appendix is provided for the theoretical modeling of the types and magnitude of change in crest level observed for projection images of different anatomical configurations.     

The effect of alterations in horizontal X-ray beam angulation and bucco-lingual cavity width on the radiographic depth of approximal cavities

The effects of changes in horizontal X-ray beam angulation and different cavity shape on images of approximal cavities on bite-wing radiographs were examined using a laboratory model. Cylindrical-, rectangular- and cone-shaped bur cut cavities were prepared in the approximal surfaces of 108 teeth and their depth determined using silicone putty impressions. Spatial relationships were controlled by fixing specimens into perspex blocks. Standardized radiographs were taken at baseline (0 degree) and then using pre-angled wedges to imitate horizontal X-ray beam movements of 5, 10 and 15 degrees in both mesial and distal directions. Radiographic cavity depth to the nearest 0.1 mm was measured. Over the range of X-ray beam movements, more than 72% of cavities deepened compared to baseline. As bucco-lingual cavity width increased the magnitude of the depth change increased. For some cylindrical cavities increases equating to 200% over baseline were seen; in some rectangular cavities increases of up to 400% over baseline occurred. The present study suggests that changes in irradiation geometry from baseline are likely to result in a cavity appearing to deepen. In a clinical context over-treatment is therefore the most likely outcome.     

An in vitro study of the influence of X-ray beam angulation on the adiographic images of the amelocemental junction and simulated alveolar crest

The aim of this in vitro study was to determine the effect of X-ray beam angulation on the radiographic images and relative positions of the amelocemental junction and alveolar crest. Using an artificial model to represent the tooth/bone relationship, radiographs were taken of a total of 15 extracted premolar teeth which had been divided into three distinct groups on the basis of the contour (configuration) of their approximal amelocemental junction. Radiographs of the tooth/bone units were taken at baseline and with a range of horizontal and vertical X-ray beam angulations from 5 degrees to 20 degrees. Analysis of the radiographs revealed that when using the ideal horizontal angulation the radiographic image of the amelocemental junction was dependent upon its contour and was not always represented by its mid-point bucco-lingually. Changing the horizontal angulation of the X-ray beam altered substantially that part of the junction visible on the film regardless of contour. Variation in the vertical angulation of the X-ray beam had little influence on the distance between the radiographic images of the amelocemental junction and a point representative of the approximal crest of the alveolar bone. It is concluded that the contour of the approximal amelocemental junction has an influence on its radiographic appearance and that films taken with an inappropriate horizontal angulation never provide an image of its mid-point bucco-lingually.     

Radiographic amelocemental junction and alveolar crest: effect of X-ray beam angulation

summary The effect of X-ray beam angulation on the radiographic images of the amelocemental junction (ACJ) and alveolar crest (AC) and their positions relative to one another were assessed using a new laboratory model for radiographic studies. A total of 39 teeth with 62 usable approximal surfaces were included in the investigation. When all tooth types were combined, changes in vertical or horizontal angulation from baseline through 20° had no significant effect on the distance between the marked (true) ACJ and marked (true) AC. However, the distance between the apparent (radiographic) ACJ and apparent (radiographic) AC was significantly reduced by varying the beam angulation in either a vertical or horizontal direction. Results for individual tooth types were qualitatively similar but larger discrepancies were found in molars followed by premolars and incisors. The results emphasize the importance of maintaining the ideal X-ray beam, tooth, bone, film relationship when taking radiographs for the assessment of periodontal destruction.     

Influence of maxillomandibular positioning in cone beam computed tomography for implant planning

The aim of this study was to evaluate the influence of changes in maxillomandibular positioning during cone beam computed tomography (CBCT) imaging on the planning of dental implants. Ten skulls were marked bilaterally with metal spheres in four regions: incisors, canine, premolars, and molars. CBCT scans were obtained in seven positions: standard position (SP), displacements of 10° and 20° above and below the SP, and lateral displacements of 10° and 20° from the SP. Subsequently, bilateral measurements of the height and width of the maxilla and mandible were performed on all images. The results showed that the position with a displacement of 20° above the SP presented the greatest differences in the measurements of bone height and width. In the bilateral comparisons, the maxillary bone width showed the greatest differences, especially for the regions of the premolars and molars. It is concluded that alterations of positioning during the acquisition of CBCT images can lead to alterations in the measurements of bone height and width, which may result in errors in implant planning and cause damage to anatomical structures.     

Estimating the validity of radiographic measurements of marginal bone height changes around osseointegrated implants.

The accuracy of determining marginal bone height changes around osseointegrated implants depends on the validity of comparing serial films and the reliability of the measurements. X-ray beam orientation changes can alter the validity of serial films. A human dry mandible containing a Br?nemark implant was irradiated +/- 12 degrees in the vertical plane at 1-degree intervals to the perpendicular to the long axis of the fixture. The thread width was recorded on both sides of each fixture image using a computer. Twenty-five randomized unclassified images were remeasured and the vertical angle of the x-ray beam was estimated from the previous measurements to test for validity of comparing images. The reliability of measurements with altered image magnification and penumbra were calculated. The reliability of 24 repeated thread width measurements was a SD of 0.01 mm. Of the 25 unknown beam angulations, 32 percent matched correctly, 20 percent +/- 1 degree, 16 percent +/- 2 degrees, or 68 percent < or = +/- 2 degrees. Alteration from a short to a long cone technique was estimated to produce magnification errors similar to the reliability SD of 0.01 mm. Similarly the penumbra varied from 0.057 mm to 0.032 mm with short to long cones using a 1.0-mm focal spot. With a 0.6-mm focal spot, the smallest penumbra of 0.19 mm was twice the measurement reliability. This method demonstrated x-ray beam angulation and validity for comparing serial films can be estimated for the extreme variations but not accurately for +9 to -6 degrees from a tangent to the fixture.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of off-axis projection geometry in dental panoramic radiography

New electronic imaging capabilities afforded by the use of linear charged-couple device arrays allow acquisition of three-dimensional information through simultaneous recordings from multiple sensors situated at different fixed angles. In theory, the resulting data can be processed to yield images tailored to specific diagnostic tasks that can be produced and manipulated on demand after exposure. The first step to determine the practical potential of such a system in panoramic radiography is to demonstrate the degree to which specific changes in projection geometry can be used to improve performance of selected diagnostic tasks of clinical interest in dentistry. Hence, the purpose of this investigation was to explore the potential to reduce proximal overlap that exist in current panoramic radiographs and also to displace the blurred image of the spine from areas of diagnostic interest through the use of off-axis projection geometry of the slit beam of radiation. As the off-axis angulation increased, more embrasures in the different areas of the dental arches of skull specimens were opened; the effects of beam angulation in the number of open embrasures was statistically significant (ANOVA, p < 0.05). A hypothetical multibeam system significantly improved the projection geometry toward the creation of images that contain little, if any, proximal overlap when compared with the conventional bilaterally symmetrical projection geometry system (t test, p < 0.001). At 6 degrees off-axis projection angle, the system was able to clear completely the anterior area from the superimposing shadow of the spinal column. The results show that multibeam alternatives to the single beam projection can significantly improve diagnostic quality in panoramic radiographs.     

Errors in radiographic assessment of marginal bone height around osseointegrated implants

Abstract – 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° angulation) to 4.8 mm (width 13 mm and angulation 20°). 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.     

Radiographic assessment of proximal infrabony pocket topography.

A method for determining the topography of interproximal infrabony pocket lesions has been presented, utilizing three intraoral radiographys. Three periapical films for the urea to be examined should be taken in a standard manner, one with the central beam angulation horizontal, another at -20degrees and the third at +20degrees. Following processing, the dried films should be examined, commencing with the -0degrees film and comparing the width of the transitional zone with that of the -20degrees film and then the film exposed with the central beam angulation at +20degrees. Following this sequence, if the transitional zone decreases in width between the 0degree and -20degrees film, then the bony destruction is greater for the buccal plate. Should the transitional zone increase in width when the above sequence of examining the film is undertaken, the bone destruction is greater for the lingual plate of bone. In each case the third film will confirm the diagnosis. In the case of horizontal bone destruction in a buccolingual direction, the transitional zone will be absent or of minimal width on the 0degree film when compared with the film exposed at +20degrees and -20degrees.     

Radiographic control of fixture-abutment connection in Brånemark implant technique

Abstract— 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°. 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.     

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" to ± 15" with a set of reference radiographs. Out of 620 recordings, 29% were right, and 71% differed by ≥ 1". The observers distinguished with great accuracy between negative and positive angulations. 81% of the recordings differed by 2" 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.     

Oblique lateral cephalometric radiographs of the mandible in implantology: usefulness and accuracy of the technique in height measurements of mandibular bone in vivo

Various radiographic techniques are used for longitudinal studies of changes in the height of the mandible with implants. Advantages and disadvantages of panoramic radiographs, lateral cephalometric radiographs, periapical films and modern CT- and MRI-techniques are briefly discussed. In this study, the usefulness of a conventional radiographic technique for measuring the height of the mandible, i.e. oblique lateral cephalometric radiography (OLCR) is evaluated in vivo. In 16 patients with permucosal implants in the anterior mandible OLCRs were repeated the same day. The mean total error for the radiographic procedure and analysis was 0.38 mm. The intra-observer error for the determination of the mandibular height by means of the image analysis procedure was 0.16 mm (analysis error). In 12 other patients pairs of radiographs of the same area of the mandible were made using both a "standard" horizontal X-ray beam direction and an individually determined "optimal" horizontal X-ray beam direction; the maximum difference between these two angulations was plus or minus 7.5 degrees. The effect of this different angulation on the height measurements is comparable to the above-mentioned total error of the measurement procedure (positioning error). An accurate positioning of the patient seems important for reliable measurements. The described radiographic (OLCR) and analysis (IBAS) technique can be used relatively simply for clinical studies. The described methods appear to be useful for measuring the mandibular height in longitudinal studies in patients with or without implants.     

Influence of X-ray beam angulation in the detection of proximal caries: Interobserver agreement in the CCD system

The aim of this study was to assess the influence of changes in horizontal and vertical X-ray beam angulation on interobserver agreement in the diagnosis of approximal caries using a charge coupled device-based digital dental imaging system (digital system) in comparison with a conventional film-based radiography (film system). A total of 40 teeth were radiographed. Projection angles were varied within a range of±20° in the horizontal and vertical direction using both systems. The resulting radiographs of approximal surfaces were observed by six radiologists, and the presence and absence of caries and the depth of any caries they found were evaluated. Results were analyzed by comparing Cohen's kappa values. The overall kappa values in both systems belonged to the same category of agreement strength for any horizontal or vertical beam angle. The deviation of the horizontal angulation, if anything, reduced the kappa values in the digital system, except for score 2 based on rating score for caries depth. On the other hand, the influence of vertical angulation was smaller than that of horizontal angulation at scores 0, 1 and overall. The results of the presentin vitro study, in which there was no apparent discrepancy in the influence of beam angulation on interobserver agreement of the diagnostic abilities, suggest that the digital system plays a useful role in clinical caries diagnosis.     

In vitro study into the influence of X-ray beam angulation on the detection of artificial caries defects on bitewing radiographs

Little is known about the influence of errors in angulation of the X-ray beam on the correct diagnosis of interproximal caries defects from bitewing radiographs. In this study radiographs were made of 10 artificial lesions resembling initial interproximal caries defects in mandibular teeth at different projection angles within a range of +/- 15 degrees in horizontal and in vertical direction and presented in a random order to 25 dentists. The result show that the best angle for lesion detection was site-specific with about a 7 degrees tolerance range. On the average, best detection performance was achieved with horizontal angulation perpendicular to the tooth surfaces, and vertical angulation with a positive or negative tilt of 12-15 degrees relative to the perpendicular. Deviations from the best horizontal angle resulted mainly in loss of sensitivity, while vertical misangulations caused mainly a drop of the specificity. The classification of lesions with an actual depth less than halfway into the enamel is influenced to a larger extent than that of deeper lesions.     

Influence of X-ray beam angulation upon the radiographic image of proximal carious lesions

Abstract Twenty-two extracted human molars and premolars with a total of34 initial proximal carious lesions were radiographed in 16 different views varying the horizontal angulation of the X-ray beam in steps of 2.5° The radiographs were read simultaneously by three observers. Clinical and radiographic diagnoses were compared. When utilizing all 16 views the concordance was 95%. All proximal surfaces were scored using four scoring classes. Surfaces without radiolucencies were scored 0, and carious surfaces were scored according to the extent of the radiolucencies. Nine sound and 12 carious surfaces were assigned identical scores in all 16 views, while 22 (65%) of the carious surfaces were assigned two, three or four different scores. Deviations from a direction of the X-ray beam tangential to the proximal surface eliciting a radiographic image belonging to a different score were measured. In 71% of the cases a deviation of 7.5° or less elicited a different score. Projectional circumstances should be taken into consideration in interpreting proximal radiolucencies.     

Influence of projection angles upon position of cementoenamel junction on radiographs

The CEJ on radiographs is often used as a reference point in the assessment of alveolar bone loss. The aim of the present study was to test the stability of the radiographic CEJ ("RCEJ") in relation to the alveolar crest under varying angulations of the central X-ray beam. In an experimental model four types of extracted teeth were radiographed at 0 degree and 20 degrees vertical angulation and at 15 horizontal angulations varying from a 17.5 degrees mesial view to a 17.5 degrees distal view. The buccal alveolar bone margin was simulated by a steel needle. RCEJ-"crest" distances were read at a X 10 magnification. Changing the vertical angulation from 0 degree to 20 degrees reduced the RCEJ-"crest" distances for all tooth types (range of average reduction 2.2-4.1 mm). Horizontal angulations without concomitant vertical angulation had a significant effect but were without clinical significance. Horizontal angulations in combination with a 20 degrees vertical angulation had a considerable influence; in a mesial view, mesial RCEJ-"crest" distances decreased and distal ones increased, and vice versa in a distal view. The deviations from the true CEJ-crest distance demonstrated may be of clinical significance, and a critical attitude to alveolar bone loss measures on radiographs using the RCEJ as reference point is recommended.     

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. Br?nemark 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.     

The effects of positioning variations in transcranial radiographs of the temporomandibular joint: a laboratory study

The relationship of the mandibular condyle to the articular fossa and eminence as seen on transcranial oblique lateral (TOL) radiographs of the temporomandibular joint is used by some clinicians as an important diagnostic sign and indicator of treatment. The literature is divided on the validity of this. The aim of this study was to consider the effects of variations in both the position of the joint and the X-ray beam orientation on the image seen on TOL radiographs. TOL radiography of a mounted block specimen of a human temporomandibular joint and associated tissues was carried out using a range of specimen rotations (+20 degrees to -20 degrees with respect to the sagittal plane) and X-ray beam angulations (20 degrees, 25 degrees, 30 degrees). Analysis of tracings of the joint images showed that most of the parameters measured varied by statistically significant amounts with changes in either specimen rotation or beam angulation. It is concluded that any convention which purports to evaluate the position of the mandibular condyle in relation to the articular fossa from TOL radiographs is invalid when the orientation of the condyle to coronal and horizontal planes is unknown.