Quantitative analysis of apical root resorption by means of digital subtraction radiography

Influence of radiographic acquisition methods and visualization software programs on the detection of misfits at the implant-abutment interface: An ex vivo study

STATEMENT OF PROBLEM

Misfits at the implant-prosthesis interface may compromise implant-supported prostheses. Periapical radiographs are frequently used to detect misfit and can be obtained by using digital or film-based systems; however, which radiographic acquisition method and visualization software program provides the greatest accuracy is unclear.

PURPOSE

The purpose of this ex vivo study was to evaluate the influence of 3 radiographic acquisition methods (complementary metal oxide semiconductor [CMOS] sensor, phosphor plates, and radiographic films) and 2 visualization software programs (proprietary and third-party) on the detection of misfits at the implant-prosthesis interface.

MATERIAL AND METHODS

Thirty-two dental implants were placed in dry human mandibles. Misfits were simulated by inserting a 50-μm polyester strip at the implant-prosthesis interface; prosthetic crowns installed directly over the implant platforms were considered as controls. Standard parallel periapical radiographs were obtained by using a CMOS sensor, a phosphor plate, and radiographic films. Five dentists assessed the digital radiographs for the presence or absence of misfits at the implant-prosthesis interface by using the proprietary software program and a third-party software program; film-based radiographs were evaluated on a light box. The area under the receiver operating characteristic curves (Az values) were compared (α=.05); sensitivity, specificity, accuracy, positive predictive value, and negative predictive values were also estimated.

RESULTS

All diagnostic and Az values were higher for the phosphor plate than for the CMOS sensor and the film-based methods (P<.05), regardless of the viewing software program used (proprietary or third-party) (P>.05).

CONCLUSIONS

The use of phosphor plates positively influenced the diagnostic accuracy for the detection of misfits at the implant-prosthesis interface, irrespective of the viewing software program used.

Morphologic evaluation of root resorption after miniscrew assisted en mass retraction in adult bialveolar protrusion patients

Background

Bialveolar protrusion is one of the most common chief complaints from the Asian orthodontic patients. Typical orthodontic treatment includes extraction of the bimaxillary premolars and en mass retraction of anterior tooth with maximum anchorage by placing miniscrews. However, excessive pursuit of profile improvement by retraction and intrusion of anterior teeth may result in root resorption, alveolar bone loss, even dehiscence. Thus this retrospective, analytical study was to evaluate the root resorption of anterior teeth after miniscrew assisted en mass retraction in adult bialveolar protrusion patients.

Materials and methods

Thirty six adult patients with bimaxillary protrusion had four first premolars extracted, and then miniscrews were placed to provide anchorage. CBCT scans were performed before (T1) and posttreatment (T2). A new improvement project introduced for 3D CBCT registration assessment of root morphology. The paired t-test was used to compare changes from T1 to T2. The relationship between the root resorption and the movement of anterior teeth were assessed by Pearson correlation coefficient analysis.

Results

The significant differences were only found in apical third of root and the largest resorption in apical third of the root is always noted in the palatal and distal sectors. Significant correlations were observed in the loss of root in distal and palatal sectors, the root length and volume decrease with the amount of anterior teeth retraction and intrusion.

Conclusion

The new 3D registration assessment of root morphology will be helpful for the clinicians. Pursuit of large retraction and intrusion leads to obvious anterior teeth root resorption.

Assessment of three methods of geometric image reconstruction for digital subtraction radiography

OBJECTIVES

To evaluate three methods of geometric image reconstruction for digital subtraction radiography (DSR).

METHODS

Digital periapical radiographs were acquired of 24 teeth with the X-ray tube at 6 different geometric configurations of vertical (V) and horizontal (H) angles: V0°H0°, V0°H10°, V10°H0°, V10°H10°, V20°H0° and V20°H10°. All 144 images were registered in pairs (Group V0°H0° + 1 of the 6 groups) 3 times by using the Emago(®) (Oral Diagnostic Systems, Amsterdam, Netherlands) with manual selection and Regeemy with manual and automatic selections. After geometric reconstruction on the two software applications under different modes of selection, all images were subtracted and the standard deviation of grey values was obtained as a measure of image noise. All measurements were repeated after 15 days to evaluate the method error. Values of image noise were statistically analyzed by one-way ANOVA for differences between methods and between projection angles, followed by Tukey's test at a level of significance of 5%.

RESULTS

Significant differences were found between most of the projection angles for the three reconstruction methods. Image subtraction after manual selection-based reconstruction on Regeemy presented the lowest values of image noise, except on group V0°H0°. The groups V10°H0° and V20°H0° were not significantly different between the manual selection-based reconstruction in Regeemy and automatic selection-based reconstruction in Regeemy methods.

CONCLUSIONS

The Regeemy software on manual mode revealed better quality of geometric image reconstruction for DSR than the Regeemy on automatic mode and the Emago on manual mode, when the radiographic images were obtained at V and H angles used in the present investigation.

A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

Purpose

Materials and Methods

Results

Conclusion

A retrospective study of digital subtraction technique to detect sclerotic changes in alveolar bone on intraoral radiographs of bisphosphonate-treated patients

OBJECTIVES

Several reports have suggested that sclerotic changes in cancellous bone of the jaw and thickening of the lamina dura are characteristic radiographic changes of an early silent stage of bisphosphonate (BP)-related osteonecrosis of the jaw. No quantitative evaluation has been reported to support this hypothesis. Emago(®) software (Oral Diagnostic Systems, Amsterdam, Netherlands) can perform digital subtraction on intraoral radiographs even if they were obtained by non-standardized radiography, provided the dimensional error is within a certain limit. The purpose of this study was to evaluate whether sclerotic changes of alveolar bone or thickening of lamina dura in patients using BP can be detected using the subtraction function of Emago.

METHODS

The authors selected 46 pairs of intraoral radiographs of the mandibular molar area in dental patients. All radiographs were obtained at intervals of 6 months or more. Among the 46 pairs, 7 pairs were from patients who were being treated with BP (study subjects), and 39 pairs were from patients who had not been using BP (controls). All pairs of radiographs underwent digital subtraction by Emago. The number of pixels of the sclerotic areas was counted and compared between subjects and controls.

RESULTS

The sclerotic changes were significantly distinguishable in two of the seven subjects (28.6%) using BP.

CONCLUSIONS

Digital subtraction function of Emago was able to detect sclerotic changes in alveolar bone. Therefore, it is suggested that the subtraction function of Emago is a useful tool for quantitatively detecting sclerotic changes that are observed at an early, silent stage of BP-related osteonecrosis of the jaw.

Root resorption diagnosed with cone beam computed tomography after 6 months of orthodontic treatment with fixed appliance and the relation to risk factors

OBJECTIVES

To investigate root resorption after 6 months of active orthodontic treatment and its relation to possible risk factors.

MATERIALS AND METHODS

Ninety-seven patients (10-18 years) with a Class I malocclusion and crowding treated with fixed appliance and premolar extractions were examined with cone beam computed tomography before and after 6 months of active treatment. The exposure covered all teeth from first molar to first molar in both jaws. The Malmgren index was used to evaluate the degree of root resorption. Irregular root contour (score 1) was seen in most teeth already before active treatment, and therefore resorptions were registered only as score 2 (<2 mm, minor resorption) or higher.

RESULTS

Minor root resorption was noted in 10% of the patients and severe root resorption, >2 mm (score 3) was found in four patients. Root resorption was more frequently seen in the upper jaw, especially the incisors. There was no statistically significant correlation of root resorption with any of the selected risk factors.

CONCLUSIONS

After 6 months of treatment, clinically significant resorption was diagnosed in 4% of the patients, ie, in 96% of the patients the radiographic examination did not reveal any significant information. The selected risk factors did not have any impact on the amount of resorption after 6 months of active treatment.

Three-dimensional morphology of root and alveolar trabecular bone during tooth movement using micro-computed tomography

OBJECTIVE

To investigate the effects of force magnitude on three-dimensional alveolar trabecular bone structure and root resorption.

MATERIALS AND METHODS

Twenty-two 11-week-old Sprague Dawley rats were randomly assigned to two groups that received a mesially directed orthodontic force to the upper right first molars at different magnitudes of force, 30 g or 100 g, for 2 weeks. The contralateral molars served as controls. The teeth and alveolar bone around the teeth were dissected from the sacrificed animals and were scanned with micro-computed tomography (CT). Structural properties of the trabecular bone and resorption crater volume on the mesial roots of the maxillary first molars were analyzed.

RESULTS

The bone volume fraction of the 30 g group and the 100 g group increased significantly in both groups, and trabecular separation of the 100 g group decreased significantly compared with controls (P < .05). The total root resorption volume in all experimental groups and the resorption volume of the lower distal surface in the 100 g group increased significantly compared with controls (P < .01). The volume of the upper mesial root surface in the 30 g group increased significantly compared with the 100 g group and controls (P < .05).

CONCLUSION

The alveolar trabecular bone was denser after orthodontic force was applied for 14 days. The effects of 30 g and 100 g orthodontic forces on root resorption were different at the upper mesial and lower distal surfaces of the mesial roots of maxillary first molars.

In vitro evaluation of a method for obtaining periapical radiographs for diagnosis of external apical root resorption

This in vitro study was conducted to evaluate a method to obtain reproducible periapical radiographs, using individualized positioning devices, of upper central incisors submitted to simulated orthodontic movement. Linear measurements of tooth length were carried out on 29 extracted human central incisors. The teeth were radiographed in a tissue simulator, at different inclinations in the bucco-lingual direction (0 initial, 0 control, -10, -5, +5, and +10 degrees). The radiographs were digitized and quantitative analysis of tooth length was carried out using an electronic ruler. The linear measurements of tooth length were reproducible (r = 0.99) for repeated measurements as well as in the comparison of the initial and control images at 0 degree, where measurements did not differ significantly (analysis of variance, P = 0.827) in radiographs with different angulations. These results show that the method proposed for obtaining in vitro periapical radiographs results in reproducible images of tooth length, even when orthodontic movement is simulated by inclination of the tooth up to 20 degrees in the bucco-lingual direction.

Diagnosis of artificially induced external root resorption using conventional intraoral film radiography, CCD, and PSP: an ex vivo study

OBJECTIVE

To compare diagnosis of artificially induced external root resorption cavities using conventional intraoral film radiography (Kodak Insight), CCD sensor (Sopix wireless) and PSP sensor (Orex Digident).

STUDY DESIGN

Two mandibles were obtained from cadavers and teeth extracted from their alveolus. Artificial external root resorptions were simulated using ISO 0.5 mm, 0.8 mm, and 1.2 mm diameter round burs by drilling to the entire depth in different locations at the cervical, middle, and apical thirds of the proximal and buccal root surfaces of 6 teeth in increasing order. Conventional and digital radiographs were obtained from 3 different views of each tooth in 3 steps (small = 0.5 mm; medium = 0.8 mm; and large = 1.2 mm diameter round burs). Three observers examined all images for the presence of resorption cavities. In the first session, each image was evaluated separately; in the second, examiners had access to all views. Data were statistically analyzed using 4-way analysis of variance. Pair-wise comparison between receptors, projection views, size, and location were made by Tukey test.

RESULTS

Higher proportions of correct readings were obtained with the conventional film (Kodak Insight) and CCD receptor compared with the PSP receptor used in this study (PSP < CCD <or= Film; P < .001). Best results were obtained when examiners had access to all views. Most difficult locations in determining true diagnosis were the apical regions. Highest correct readings were obtained at the proximal cervical regions.

CONCLUSION

Conventional intraoral film and CCD sensor produced similar results in diagnosing simulated external root resorption.

Density value means in the evaluation of external apical root resorption: anin vitrostudy for early detection in orthodontic case simulations

OBJECTIVES

The purpose of this study was to develop an alternative diagnostic tool for the early detection of external apical root resorption (EARR).

METHODS

Mandibular incisors (n=36) with and without simulated EARR lesions were used. 18 teeth with facial and proximal windows, each with a range of 2 sizes, were placed in 6 N hydrochloric acid (HCl) baths for 10 min. A sample of the acid solution was analysed for calcium concentration by atomic absorption spectrophotometry. Incisors were imaged at 80 degrees, 90 degrees and 100 degrees under 3 test conditions (bracketed, non-bracketed and with subtraction registration templates (SRTs)). The images were reconstructed and subtracted to determine the accuracy and sensitivity of the method. Quantified histograms for each subtracted image were constructed.

RESULTS

At either an angle of 80 degrees or 100 degrees, the bracketed group had the largest mean standard deviation of the subtraction histograms while the SRT group had the smallest. Density values as a function of total calcium removed were plotted indicating a linear relationship between subtraction density units and calcium loss.

CONCLUSION

The use of the SRTs was significantly more accurate than the use of the brackets alone for digital subtraction radiography reconstructions. This model shows promise for detecting EARR prior to a noticeable decrease in root length. It may be useful for early detection of resorptive lesions during routine orthodontic treatment.

Physical properties of root cementum: Part 8. Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces: A microcomputed tomography scan study

INTRODUCTION

Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent.

METHODS

Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 x 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements.

RESULTS

The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.

Clinical efficacy of a new software developed for dental digital subtraction radiography

OBJECTIVES

The aim of this study was to test and compare the efficacy of software developed recently for digital subtraction radiography (DSR) in vivo.

METHODS

An algorithm performing both manual and automated image reconstructions and contrast correction was developed for the manipulation of radiographic images. Pre- and post-operative radiographic images of ten patients were obtained and the automated subtraction analyses were performed using four different softwares (new software, Emago, Photoshop 8.0 and Paintshop Pro 9). Ten experienced dental specialists evaluated the clinical efficacy of each program and scored the softwares by using visual analogue scales (VAS). The results were statistically analysed and alpha was set as 0.05.

RESULTS

The newly developed algorithm received higher scores than the others (new software =67.89, Emago = 64.26, Paintshop Pro 9 = 33.41 and Photoshop 8.0 = 27.24, respectively). The clinical efficacies of the new software and Emago were not significantly different (P = 0.720); likewise, Photoshop 8.0 and Paintshop Pro 9 performed comparably (P = 0.295).

CONCLUSIONS

Considering this study, the new software and Emago would be suggested for DSR in dental practice.

Reproducibility of and file format effect on digital subtraction radiography of simulated external root resorptions

OBJECTIVE

To evaluate, in simulated external root resorptions (ERR), two factors that may affect results of digital subtraction radiography (DSR): (1) intraobserver and interobserver reproducibility and (2) effects of digital file formats (TIFF, BMP and JPEG) on the estimation of mineral loss.

METHODS

Eleven incisors were radiographed three times (NR, no resorption; SR, small--#1/4 round bur; and LR, large--#2 round bur) on standardized projections. The resulting images were reproduced and saved as TIFF, JPEG and BMP file formats. The pairs of TIFF images (NR x SR and NR x LR) were subtracted three times at 1 week intervals by three observers. One observer subtracted pairs of images (NR x SR and NR x LR) for all file formats. For each subtraction the resorption area was selected and mean pixel density values were calculated.

RESULTS

Analysis of variance (ANOVA) (P = 0.05) showed no statistical differences for intraobserver and interobserver values. Mean pixel density values were: observer A, 121.60 +/- 2.56 (NR x SR) and 111.84 +/- 4.04 (NR x LR); observer B, 121.86 +/- 2.50 (NR x SR) and 110.92 +/- 3.36 (NR x LR); and observer C, 121.70 +/- 2.39 (NR x SR) and 111.10 +/- 2.67 (NR x LR). Also, no statistical differences were found between file formats for LR (TIFF, 110.88 +/- 2.79; JPEG, 111.35 +/- 3.35; BMP, 111.00 +/- 2.70) and for SR between TIFF (121.30 +/- 2.34) and JPEG (120.46 +/- 1.51) or BMP (121.67 +/- 2.18) file formats. Differences were found between the JPEG and BMP groups.

CONCLUSIONS

DSR is reproducible in simulated ERR, and JPEG or BMP file formats do not affect results.

Quantitative analysis of errors in alveolar crest level caused by discrepant projection geometry in digital subtraction radiography: An in vivo study

OBJECTIVE

This study compared the difference between 3 intraoral radiographic techniques on digital subtraction radiography (DSR) in vivo that are commonly used in a clinical setting.

STUDY DESIGN

We evaluated and statistically analyzed the errors in the DSR image in 6 regions with 3 radiographic techniques: paralleling technique with a bite block attached to XCP, paralleling technique using XCP, and bisecting-angle technique.

RESULTS

The amount of error using the bisecting-angle technique was too large for DSR, compared to that of the paralleling technique with a bite block attached to XCP. In the mandibular anterior region, the paralleling technique using XCP was not different from paralleling technique with a bite block attached to XCP. The lowest degree of error was present in the anterior region whereas the highest was present in the molar region.

CONCLUSION

Bisecting-angle technique should be avoided, and paralleling technique using XCP can be used in the mandibular anterior region for DSR.

Development and evaluation of digital subtraction radiography computer program

OBJECTIVE

We developed a new program for digital subtraction radiography (DSR) having useful functions to get the DSR image more accurately and efficiently. The purpose of this study was to evaluate the accuracy of the DSR image acquired using the new program as compared with the ready-made program.

STUDY DESIGN

Four observers performed the DSR process using our program and the ready-made program for digital intraoral radiographs taken from incisor, premolar, and molar regions. The statistical difference was evaluated between the programs, between the observers, and between the regions.

RESULTS

The DSR image using our program was superior to that with the ready-made program in all the observers and all the radiographed regions. Also, there was the statistical difference among the observers, especially in our program.

CONCLUSION

The DSR image using the new program was very accurate compared with ready-made program, so the program was useful to get an accurate DSR image.

Exploring the third dimension in root resorption

OBJECTIVE

To review and investigate the validity of various 2D quantitative measurement techniques, and to explore the third dimension of root resorption.

DESIGN

A review of the literature involving various quantitative evaluation of root resorption.

RESULTS

Quantitative evaluation of resorption using radiographs has proven to be highly inaccurate because of magnification errors and their inability to be readily repeated and reproduced. Studies using histology sections of samples have proven to be laborious and technique sensitive. Inherent parallax errors and loss of material in data transfer have denied the true understanding of this 3D event.

CONCLUSION

With the evolution in computing technology and digital imaging, the vision of evaluating the extent of root resorption in 3D has materialized. It was demonstrated that 3D volumetric quantitative evaluation of root resorption craters was feasible and its accuracy and repeatability was high.

Image processing and enhancement provided by commercial dental software programs

OBJECTIVES

To identify and analyse methods/algorithms for image processing provided by various commercial software programs used in direct digital dental imaging and to map them onto a standardized nomenclature.

METHODS

Twelve programs presented at the 28th International Dental-Show, March, 2001, Cologne, Germany and the Emago advanced software were included in this study. An artificial test image, comprised of gray scale ramps, step wedges, fields with Gaussian-distributed noise, and salt and pepper noise, was synthesized and imported to all programs to classify algorithms for display; linear, non-linear and histogram-based point processing; pseudo-coloration; linear and non-linear spatial filtering; frequency domain filtering; measurements; image analysis; and annotations.

RESULTS

The 13 programs were found to possess a great variety of image processing and enhancement facilities. All programs offer gray-scale image display with interactive brightness and contrast adjustment and gray-scale inversion as well as calibration and length measurements. While Emago enables arbitrary spatial filtering with user-defined masks up to 7x7 pixels in size, most programs sparsely include filters and tools for image analysis and comparison. Moreover, the naming and implementation of provided functions differ. Some functions inappropriately use standardized image processing terms to describe their operations.

CONCLUSIONS

Image processing and enhancement functions are rarely incorporated in commercial software for direct digital imaging in dental radiology. Until now, comparison of software was limited by the arbitrary naming used in each system. Standardized terminology and increased functionality of image processing should be offered to the dental profession.