Subtraction radiography for the diagnosis of periodontal bone lesions

Subtraction radiography permits reduction of structured noise from sequentially obtained images containing changes of diagnostic interest. It is particularly well suited for the detection of small periodontal changes, because the teeth provide stable bases for standardization of projection geometry from one exposure to the next and because structured noise is prevalent in unprocessed images of the periodontium. Multiple lesions were selectively induced in the tooth-supporting bone of dry mandibles. A significant improvement was unequivocally demonstrated in the visual detectability of the resulting changes after digital subtraction of pre- and postinduction standardized radiographs. The data indicate a significant increase in diagnostic accuracy as a result of the digital subtraction process used in this study. Hence, further application of this technique is warranted in controlled clinical trials.     

Subtraction radiography for the diagnosis of periapical bone lesions

Abstract Subtraction and conventional radiography were evaluated for the diagnostic potential to assess periapical bone lesions. The periapical region of dry human mandibles was radio-graphically examined, subjectively evaluated and measured by ¹²⁵I absorptiometry before and after the creation of bone defects. Both conventional radiographs and subtraction images made from the conventional radiographs after digitization were interpreted by 10 dentists. Receiver operating characteristic (ROC) analysis technique was used to compare the two techniques. There was a higher diagnostic accuracy using subtraction technique. For a lesion depth corresponding to < 2 mm of compact bone, there was a clear difference between the techniques, but for deeper lesions the conventional technique gained force. The subtraction technique was significantly superior for lesions confined to cancellous bone. The statistical difference in the diagnostic utility of subtraction compared with conventional technique was found to be less for lesions of the cortical bone. Therefore, the conclusion is that subtraction radiography improves the detection of small lesions in the periapical bone area.     

Diagnosis of bone lesions by subtraction radiography

Examiner diagnostic accuracy and response times were compared using subtraction and conventional radiography in a dog model. Osseous lesions were induced interproximally and through the mandibular buccal bone interradicularly and radicularly. Standardized preoperative and postoperative conventional radiographs of the induced lesions were compared to subtraction images of the same sites by 11 dentists. Examiners using the subtraction technique demonstrated improved diagnostic performance (P less than 0.001) and response times (P less than 0.001). Additionally, this method yielded a 30% reduction in equivocal diagnostic decisions. Data from this study suggest that subtraction radiography is a sensitive and accurate method to detect osseous lesions associated with periodontal diseases.     

Effects of hibernation on interradicular alveolar bone.

The interradicular alveolar bones of the nonhibernating and hibernating ground squirrels were compared using light and transmission electron microscopy. During hibernation changes occurring in the bone suggest osteocytic osteolysis. Minerals may be mobilized from bone for utilization elsewhere in the body to maintain a minimal metabolic level for survival.     

Direct digital radiography for the detection of periodontal bone lesions.

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.     

The fate of vital and devitalized bone grafts in the healing of interradicular lesions

The fate of vital and devitalized grafts of mature concellous bone from the jaws were studied in interradicular lesions in monkeys. 98 bifurcation defects were produced in premolars and molars and maintained by periodontal dressing inserted for four weeks. Ten to 15 weeks later fresh cancellous bone was transplanted into 32 defects. Other cancellous bone grafts were divitalized by boiling and transplanted into 34 bifurcations. The remaining 32 defects received no grafts. The animals were sacrificed to yield observation periods from 0 to 90 days. After decalcification of the specimens and embedding in paraffin, serial sections were cut at 8 microns and stained. The fate of viable and dead transplants were similar during the healing of the interradicular lesions. Except for a few osteocytes which seemed to survive transplantation in the fresh cancellous bone, the osteocyte lacunae were devoid of cells in both types of transplants after 1 week. The deepest located bone grafts became incorporated in new bone developed from the interradicular septum. The more superficially located grafts were rejected or were surrounded by a cementum-like substans. The influence of the grafts on bone regeneration was small and based solely on their osteoconductive effect.     

Kielbone® in healing interradicular lesions in monkeys

The purpose of this investigation was, to compare the histological features of Kielbone and autogenous jaw bone following transplantation into periodontal interradicular lesions in monkeys. Bifurcation defects were produced on mandibular molars and premolars. Kielbone was transplanted into 40 bifurcations while another 30 bifurcations received fresh autogenous cancellous jaw bone. The animals were sacrificed according to a schedule yielding observation periods up to 16 weeks. Before sacrifice the animals were perfused with a mixture of india ink and serum (3:1) by cannulization of the carotid arteries. The specimens were decalcified in a formic acid/sodium citrate solution. Cleared specimens 100μ of thickness were prepared from one half of each specimen. The other half of the specimen was cut into serial sections 8μ thick and stained with hematoxylin and eosin or Mallory's connective tissue stain. During healing of the treated defects Kielbone grafts and grafts of fresh autogenous bone from the jaws displayed similar histological features. In the bifurcation defects, Kielbone as well as autogenous bone grafts occured as isolated bone particles surrounded by a cementum-like substance. It is suggested that Kielbone may constitute a suitable substitute for autogenous bone grafts in the treatment of periodontal intrabony defects. However, it should be emphasized that neither autogenous jaw bone nor Kielbone did favour bone regeneration in the bifurcation defects.     

根尖片数字减影对牙槽骨微小病损检测能力的评价

目的评价根尖片数字减影处理系统对微小病损检出的准确率。方法于干燥下颌骨牙槽嵴区制作０．２ｍｍ３～１．９ｍｍ３微小病损共７２个，在制作病损前后摄定位根尖片，分别用数字减影方法与直接读片法对这些随机分布的微小病损进行检测。结果对于０．２ｍｍ３～０．５ｍｍ３的微小病损两种方法的检出率均低于５０．０％。对于０．７ｍｍ３病损直接读片法检出率为３８．７％，而ＤＳＲ法为５７．５％（Ｐ＜０．０１），对于０．９ｍｍ３病损，ＤＳＲ法和直接读片法的检测准确率分别为８９．３％和５７．３％（Ｐ＜０．０１）。结论ＤＳＲ系统对微小骨病损的检测能力明显优于直接读片法。     

Quantitative evaluation of bone repair of periapical lesions using digital subtraction radiography

The standardized radiographic device for digital subtraction radiography (DSR) was developed to detect bone repair of periapical lesions after root canal filling. The radiographic reproducibility of the device was examined over a period of 6 months. The detectability of DSR, and the quantitative accuracy of bone changes were investigated. Results were obtained as follows: the angulation error of this instrument was limited to ±1° in the vertical and horizontal directions over a period of 6 months, which indicated that this instrument was adequate for clinical use in DSR. The accuracy of the quantitative evaluation of bone change was within ±10%.     

Histometric analysis of interradicular bone in protein deficient animals

A histometric analysis of bone density was made in the interradicular bone of rats fed either a powdered protein free diet, pair-fed with an isocaloric 27 % casein diet or fed control diets, ad libitum, of either soft or hard consistencies. A marked osteoporosis was found in the two nutritionally restricted groups. The pair fed animals showed a greater osteoporosis than the protein deficient animals. These results were statistically significant (p = 0.001).     

CBCT测量根间间隙区颊侧皮质骨厚度

目的:通过CBCT测量临床上微螺钉通常植入的根间间隙区颊侧皮质骨的厚度. 方法:收集200例锥束CT(CBCT)图像(上下颌各100例). 在距牙槽嵴下方6 mm水平,测量自尖牙到第一磨牙根间间隙区近中、中点和远中皮质骨厚度. 结果:邻牙间中点的皮质骨厚度明显小于牙旁的皮质骨厚度(P<0.001). 皮质骨厚度<1 mm比例最高的位置(20%)在下颌尖牙和第一前磨牙间中点.皮质骨厚度>1.5 mm比例最高的位置(50%)在下颌邻近第一磨牙(第二前磨牙和第一磨牙间中点的远中). 结论:邻牙间中点位置的皮质骨厚度明显小于邻近牙根区域皮质骨厚度.     

Histometric study of age changes in interradicular bone of Wistar rats

Age changes in the interradicular bone of rat first molars were studied in mesio-distal sections by means of a histometric technique based on an integration method with a points system. The lower jaw showed a gradual increase in density while the upper jaw showed an initial increase, a plateau and a reduction in density with age.     

Subtraction radiography and computer assisted densitometric analyses of standardized radiographs

A standardized radiographic series of incrementally increasing alveolar crestal defects in skulls were subjected to analyses by subtraction radiography and computer assisted quantitative densitometric analysis. Subjects were able to detect change using subtraction radiography in alveolar bone defects with bone loss in the range of 1–5 percent as measured by ¹²⁵I absorptiometry. Quantitative densitometric analyses utilizing radiographic pairs adjusted for differences in contrast (gamma corrected) can be used to follow longitudinal changes at a particular alveolar bone site. Such measurements correlate with change observed by ¹²⁵I absorptiometry (r= 0.82–0.94).     

Detectability of experimental peri-implant cancellous bone lesions using conventional and direct digital radiography

BACKGROUND: The aim of this study was to compare the diagnostic performance obtained from direct digital radiographic images (in their original form and after applying a grey-scale inversion) and conventional film in the detection of artificial peri-implant cancellous bone lesions. METHODS: Four titanium implants were placed into the cancellous bone of a dry mandible and increasingly larger bone defects were created in their approximal sites. Radiographs were taken using conventional film and a digital charge-coupled device sensor. Twelve observers estimated three series of images (conventional, digital original, digital inverse) on a 5-point confidence scale. Data were evaluated statistically by analysis of variance and the sensitivity, specificity and accuracy of the three imaging modalities were calculated. RESULTS: Total mean observer confidence scores increased as the size of the defect also increased. No statistically significant differences were found among the three images for the absence of defect and the defect that corresponds to the smallest bur size. Significant differences were found for larger bur sizes between the conventional image and the two digital images and for the largest bur size between the digital inverse and the other two images. Specificity was high and sensitivity relatively low. CONCLUSIONS: Peri-implant bone lesions must exceed a certain size to be confidently detected but the lesion absence is detected equally well with all three imaging modalities.     

Digital subtraction radiography for diagnosis of periodontal bone lesions with simulated high-speed systems

Standardized radiographs were obtained of the molar and premolar areas of dry human mandibles before and after small lesions were induced in the alveolar bone crest. The radiographs were digitized, and various amounts of random noise were added to simulate images produced by more efficient, low-radiation-dose systems. Subtraction images were produced from these noise-degraded radiographs. The diagnostic performance of human observers from these images was then compared with that obtained from both subtraction images made from nondegraded radiographs and from the original, conventional images. The diagnostic accuracy obtained with subtraction images, even if they were made from severely noise-degraded images, was equal or superior to that obtained with the conventional radiographs. This indicates that structured noise, which is reduced by the subtraction procedure, is a predominant, limiting factor in the diagnosis of small periodontal bone lesions. It also suggests that the application of a subtraction technique for the detection of such changes occurring over a period of time can make possible the use of significantly faster imaging systems than those currently employed.