Cone beam computed tomographic findings in refractory chronic suppurative osteomyelitis of the mandible

Cemento-Osseous Dysplasia: A Detailed Comparison of the 2005 and 2017 WHO Classifications and Case Analysis

The WHO substantially redefined cemento-osseous dysplasia (COD) in 2017. The descriptions of COD in the 2005 and 2017 WHO classifications are quite different. In this study, we compared the difference in COD description between the 2005 and 2017 editions of the WHO classifications in detail. There are remarkable differences in the terminology, definition, synonyms, epidemiology, classifications, clinical features, radiation/pathology, prognosis, and predictive factors of COD between the two versions. At present, the surgical treatment of COD is less defined, and there is no clear guidance for the treatment of sclerotic bone. In this study, we extracted the affected teeth without removing the sclerotic bone when the bone absorption line can be only found between the root and the lesion, and we extracted the teeth as well as the lesion and curetted the granulation tissue when a bone absorption line could be seen between the lesion and the alveolar bone. According to our observation, the position of the bone absorption line can be used as a reference for the selection of sclerotic bone treatment. Sclerotic bone preservation did not increase its volume and density after tooth extraction. Sclerotic bone was composed of highly mineralized tissue with less blood vessels and cells. The position of the bone resorption line can be used as a basis for treatment selection. The high mineralization of the lesion may weaken its anti-infection ability.

Radiologic findings of osteonecrosis, osteoradionecrosis, osteomyelitis and jaw metastatic disease with cone beam CT

PURPOSE

The purpose of this study was to assess CBCT scans of patients with medication related osteonecrosis of the jaws (MRONJ), osteoradionecrosis (ORN), osteomyelitis (OM) and jaw metastatic disease (JM), evaluate the presence and extent of radiologic findings, identify radiologic parameters that may distinguish the four entities and last, introduce a new modified radiographic index (CRIm), in order to contribute to the diagnosis of these conditions.

METHODS

Τwo major databases were retrospectively searched for fully documented and diagnosed CBCT scans of MRONJ, ORN, OM and JM from 2006 to 2019. 335 CBCT scans met the inclusion criteria and were assessed under standardized viewing conditions blindly by 2 observers. The CRIm index proposed in this study evaluates: lytic changes, sclerosis, periosteal bone formation, sequestration, non-healing extraction sockets and other findings which included: sinus implication, inferior alveolar canal implication and jaw fracture. Lytic changes, sclerosis, periosteal bone formation, sequestration and non-healing extraction sockets were scored as: absent (0), localized/single (1) and extensive/multiple (2). Each one of other findings were scored individually as: absent (0) and present (1). For statistical analysis t-test, Pearson's r correlation coefficient, one-way ANOVA and Bonferonni were performed.

RESULTS

Extensive lytic changes were the most common finding, especially for ORN, where it occurred in all CBCT scans (100%). The mean value of the CRIm index differs significantly between CBCT scans with MRONJ and JM, as well as between those with OM and JM (Bonferroni p < 0.001).

CONCLUSIONS

The new modified Composite Radiographic Index introduced in this study, appears to have improved an objective approach to the previously used Composite Radiographic Index by means of cumulative radiologic features. Τhe predominance of certain radiologic features in one or more of these entities may lead the diagnostician towards the correct diagnosis.

Assessing the optimal imaging modality in the diagnosis of jaw osteomyelitis. A meta-analysis

Osteomyelitis is an inflammatory infectious disease that affects bone and bone marrow. Histopathology remains the gold standard method for diagnosis, but imaging modalities also play an important role. We systematically reviewed five articles with comparative studies on plain films, computed tomography (CT) scan, magnetic resonance imaging (MRI), cone beam computed tomography (CBCT), positron emission tomography (PET), single photon-emission computed tomography (SPECT), scintigraphy, and SPECT/CT. Scintigraphy and SPECT/CT has the highest sensitivity of 100%. PET is only to be used in cases of follow up. Orthopantomography (OPG) is the most common initial diagnostic tool despite its low sensitivity. CT provides the necessary specificity needed for radionuclide imaging, which has the highest negative predictive value of 100% and a positive predictive value >95%. SPECT/CT with 100% sensitivity and 85% specificity can be considered as the imaging modality of choice for initial diagnosis and follow up.

[Imaging features of osteomyelitis of the jaws with different diagnostic methods. A review]

Osteomyelitis of the jaws (OM) is an infectious pathology involving the bone marrow. It is due to various etiologies, the main one being odontogenic. The diagnosis of OM is a challenge for dentists, who must rely on clinical and imaging examinations. Panoramic radiography is the most frequently used imaging test, but it has some limitations that have improved with the incorporation of new imaging methods such as computed tomography, cone beam computed tomography, magnetic resonance imaging, and bone scintigraphy with radionuclides. The purpose of this review was to describe the imaging characteristics of OM of the jaws according to the radiological diagnostic methods available in the literature in order to provide radiologisst with greater knowledge and improve reporting in daily practice.

Prognosis of medication-related osteonecrosis of the jaws in metastatic prostate cancer patients

OBJECTIVES

The aim of this study was to find out the prognosis of medication-related osteonecrosis of the jaws (MRONJ) in prostate cancer patients who received two different types of antiresorptive agents for bone metastasis.

MATERIALS AND METHODS

We retrospectively surveyed a cohort of 95 metastatic prostate cancer patients with 122 MRONJ lesions treated in a single medical center. Treatment outcomes and prognostic factors were investigated. The cumulative complete response rate was calculated with the Kaplan-Meier method, and significance was examined with the log-rank and Breslow tests. Cox regression was used for the univariate and multivariate analyses of prognostic factors.

RESULTS

The cumulative complete response rate of all patients at 12 months was 37.8%, and that of patients treated with zoledronic acid and denosumab was 22.9% and 70.5%, respectively. Denosumab, pretreatment C-terminal telopeptide of collagen I (CTX) level > 150 pg/ml, and anemia were identified as independent prognostic factors in a multivariate analysis with adjusted hazard ratios of 3.18 (95% confidence interval [CI], 1.24-8.11), 3.24 (95% CI, 1.39-7.53), and 0.42 (95% CI, 0.19-0.93), respectively.

CONCLUSION

A higher pretreatment level of CTX, using denosumab as the antiresorptive agent and without anemia, indicates a better treatment outcome of MRONJ in prostate cancer patients.

Osteomyelitis, osteoradionecrosis, or medication-related osteonecrosis of the jaws? Can CBCT enhance radiographic diagnosis?

OBJECTIVE

To attempt defining differential radiographic diagnostic characteristics for osteonecrotic lesions using 2D as opposed to 3D images.

MATERIALS AND METHODS

This was a cross-sectional study. Subjects presenting mandibular osteonecrotic lesions (osteomyelitis, osteoradionecrosis, and medication-related osteonecrosis of the jaws) were selected and compared to a group of age- and gender-matched controls, all having both cone-beam computed tomographic images (CBCT) and panoramic radiographs (PANO). Both imaging modalities (predictor variables) were evaluated by two radiologists that scored lesion presence, eight additional radiological features, and a composite severity index (outcome variables). For each pathologic condition, characteristic features were assessed in PANO and CBCT by the Wilcoxon signed-rank test. Regression tree analysis revealed the predictive value of PANO and CBCT (α = 5%).

RESULTS

Overall, the predictive value of PANO reached 74%, while for CBCT it became 90%. Regarding the composite severity index, CBCT enabled to detect more subtle lesions. Also, CBCT imaging allowed showing more distinct radiographic diagnostic features as compared to PANO imaging, more specifically when distinguishing osteomyelitis from both other lesions.

CONCLUSIONS

Cone-beam computed tomography enabled showing more differences in radiological features between distinct osteonecrosis disease entities. CBCT imaging might be a better contributor for the detection of early lesions and to monitor further pathological developments in the mandible.

Cone Beam Computed Tomography in Oral and Maxillofacial Surgery: An Evidence-Based Review

Cone Beam Computed Tomography (CBCT) is a valuable imaging technique in oral and maxillofacial surgery (OMS) that can help direct a surgeon’s approach to a variety of conditions. A 3-dimensional analysis of head and neck anatomy allows practitioners to plan appropriately, operate with confidence, and assess results post-operatively. CBCT imaging has clear indications and limitations. CBCT offers the clinician 3-dimensional and multi-planar views for a more accurate diagnosis and treatment without the financial burden and radiation exposure of conventional computed tomography (CT) scans. Furthermore, CBCT overcomes certain limitations of 2-dimensional imaging, such as distortion, magnification, and superimposition. However, CBCT lacks the detailed depiction of soft tissue conditions for evaluation of pathologic conditions, head and neck infections, and temporomandibular joint (TMJ) disc evaluation. This review evaluates the evidence-based research supporting the application of CBCT in the various fields of oral and maxillofacial surgery, including dentoalveolar surgery, dental implants, TMJ, orthognathic surgery, trauma, and pathology, and will assess the value of CBCT in pre-operative assessment, surgical planning, and post-operative analysis when applicable. Additionally, the significant limitations of CBCT and potential areas for future research will be discussed.

Comparative evaluation of SPECT/CT and CBCT in patients with mandibular osteomyelitis and osteonecrosis

OBJECTIVES

Therapy of osteomyelitis and osteonecrosis very often requires surgery. Proper preoperative radiological evaluation of a lesion's localization and extent is a key in planning surgical bone resection. This study aims to assess the differences between single-photon emission computed tomography and cone beam computed tomography when detecting an osteomyelitis/osteonecrosis lesion as well as the lesion's qualitative parameters, extent, and localization.

MATERIAL AND METHODS

Identification of candidates was performed retrospectively following a search for patients with histologically or clinically confirmed osteomyelitis or osteonecrosis. They were matched with a list of patients whose disease extent and localization had been evaluated using single-photon emission computed tomography and cone beam computed tomography in the context of clinical investigations. Subsequently, two experienced examiners for each imaging technique separately performed de novo readings. Detection rate, localization, extent, and qualitative parameters of a lesion were then compared.

RESULTS

Twenty-one patients with mandibular osteomyelitis and osteonecrotic lesions were included. Cone beam computed tomography detected more lesions than single-photon emission computed tomography (25 vs. 23; 100% vs. 92%). Cone beam computed tomography showed significantly greater depth, area, and volume, whereas length and width did not differ statistically between the two groups.

CONCLUSION

Both single-photon emission computed tomography and cone beam computed tomography could sensitively detect osteomyelitis/osteonecrosis lesions. Only single-photon emission computed tomography showed metabolic changes, whereas cone beam computed tomography seemed to display anatomic morphological reactions more accurately. The selection of the most adequate three-dimensional imaging and the correct interpretation of preoperative imaging remains challenging for clinicians.

CLINICAL RELEVANCE

In daily clinical practice, three-dimensional imaging is an important tool for evaluation of osteomyelitis/osteonecrosis lesions. In this context, clinicians should be aware of differences between single-photon emission computed tomography and cone beam computed tomography when detecting and assessing an osteomyelitis/osteonecrosis lesion, especially if a surgical bone resection is planned.

Mandibular blastomycosis: A case report and review of the literature

Introduction

Blastomycosis is an endemic mycosis in the United States known to primarily cause pneumonia. However, dissemination to different organs including the musculoskeletal system has been described.

Case report

We report a case of mandibular blastomycosis in a healthy patient with no evidence of lung involvement. A 28 year-old female presented with recurrent right mandibular osteomyelitis despite courses of antibiotics and surgical debridement. She eventually underwent right hemimandibulectomy. Budding yeasts visualized on Gomori Methenamine-Silver (GMS) and Periodic acid-Schiff (PAS) were morphologically consistent with Blastomyces dermatitidis, and intra-operative cultures showed growth of mold identified as B. dermatitidis by DNA probe. She was placed on a prolonged course of itraconazole with clinical improvement. We also reviewed the literature and found 5 cases of similar presentation which we briefly summarized in this present case report.

Conclusion

Blastomycosis should be considered in patients with recurrent or persistent mandibular osteomyelitis even in immunocompetent individuals.

Prevalence of radiographic findings on jaws exposed to antiresorptive therapy: a meta-analysis

OBJECTIVES:

Determine the prevalence of radiographic findings (RF) on both jaws among patients receiving antiresorptive bone therapy.

METHODS:

Six electronic databases and partial grey literature were searched. Data was collected based on predetermined criteria. The key features from the included studies were extracted. The MAStARI tool assessed the potential risk of bias (RoB) among the studies, while the GRADE approach determined the level of evidence.

RESULTS:

29 studies were identified and included in the qualitative analysis, totalling 1133 patients. 27 studies had sufficient data to be included in a series of meta-analysis reporting 12 types of radiographic findings, and were split in two groups based on their study design. G1 comprised descriptive observational studies and G2 analytical cross-sectional studies. Two studies presented a high RoB, 16 had a moderate RoB, and 11 had low RoB. The overall level of evidence identified was very low. The most frequent RF were mixed lytic-sclerotic areas (73.88%), followed by osteolytic changes (66.18%), osteosclerosis (65.75%), cortical bone erosion (50.83%), persisting alveolar socket (45.77%), periodontal ligament (PDL) widening (44.69%), and inferior alveolar canal (IAC) involvement (43.40%). Less frequent, but equally important, were the periosteal reaction (34.27%), lamina dura thickening (32.97%), sequestrum (29.94%), pathologic fracture (20.90%), and density confluence of cortical and cancellous bone (16.61%). 20 patients reported no signs.

CONCLUSIONS:

RF prevalence was high and mainly included mixed lytic-sclerotic areas, osteolysis, osteosclerosis, cortical bone erosion, persisting alveolar socket, PDL-widening, IAC-involvement. Due to the very low level of evidence (GRADE) caution should be exercised when considering these findings.

Cone beam computed tomography: basics and applications in dentistry

The introduction of cone beam computed tomography (CBCT) devices, changed the way oral and maxillofacial radiology is practiced. CBCT was embraced into the dental settings very rapidly due to its compact size, low cost, low ionizing radiation exposure when compared to medical computed tomography. Alike medical CT, 3 dimensional evaluation of the maxillofacial region with minimal distortion is offered by the CBCT. This article provides an overview of basics of CBCT technology and reviews the specific application of CBCT technology to oral and maxillofacial region with few illustrations.

Florid Cemento-Osseous Dysplasia Simultaneous the Chronic Suppurative Osteomyelitis in Mandible

INTRODUCTION

The florid cemento-osseous dysplasia is an uncommon condition nonneoplastic, of unknown cause with higher prevalence in melanodermic women, limited the maxillary bones, is characterized by the presence of dispersed and diffuse radiopaque calcifications, constituted of bone and dense cemento; however, when the bone is infected it induces the suppuration and formation of osseous sequestra, thus resulting in an osteomyelitis frame.

CLINICAL REPORT

The patient was attended in a Dental Specialties Center in the state of Alagoas, Brazil, presenting on clinical examination edema and extra oral fistula with pus drainage in hemiface submandibular of the right side. Radiographically it was possible to observe area of sclerosis and osseous sequestra involving the right side region of the mandible body, and it increases zones of the bone density. In association with clinical data and complementary diagnosis examinations, the option of treatment adopted was the complete removal of the bone fragment, followed by adaptation and plate fixation and titanium screws to reduce the risk of mandibular fracture.

OBJECTIVE

The aim of the present paper was to relate a clinical patient of florid cemento-osseous dysplasia simultaneous the chronic suppurative osteomyelitis, highlighting their clinical, radiographic, and histological characteristics, as well as their diagnosis and treatment.

Osteoradionecrosis and medication-related osteonecrosis of the jaw: similarities and differences

The purpose of this study was to compare medication-related osteonecrosis of the jaw (MRONJ) with osteoradionecrosis (ORN). Group 1 comprised 74 MRONJ patients (93 lesions) and group 2 comprised 59 ORN patients (69 lesions). Patient characteristics, clinical presentation of the lesions, the presence of complications, and the relationship with previous dental extractions were analyzed for both groups. Significant differences were found between the groups with regard to the characteristics of the patient populations, extraction as the precipitating event, the type of initial complaint, the prevalence of pain, and the location of the lesions. In the ORN group, significantly more patients complained of pain (P=0.0108) compared with the MRONJ group. Furthermore, significantly more pathological fractures (P<0.0001) and skin fistulae (P<0.0001) occurred in the ORN group. The treatment was more often conservative in the MRONJ group than in the ORN group (61.3% vs. 36.2%). Despite similarities in terms of imaging, risk factors, prevention, and treatment, MRONJ and ORN are two distinct pathological entities, as highlighted by the differences in patient characteristics, the initial clinical presentation, course of the disease, and outcome.

Oral Rehabilitation of an Osteopetrosis Patient with Osteomyelitis

Osteopetrosis is a congenital disorder characterized by increasing osteoclastic function resulting in osteomyelitis in the jaws. Orofacial findings in osteopetrosis patients are unerupted, malformed, or delayed teeth and many dental caries due to vulnerable enamel and dentin and osteomyelitis. Many reports have described that maxilla is an uncommon site of occurrence for osteomyelitis due to cortical bone morphology and collateral circulation. This report aims to discuss clinical features and prosthodontic management of a patient with clinical features of adult form of osteopetrosis and osteomyelitis in both jaws. The patient has reported better masticatory and speech efficiency with removable dentures in maxillary and mandibular jaw and also self-esteem improvement and family interaction.

Clinical management of suppurative osteomyelitis, bisphosphonate-related osteonecrosis, and osteoradionecrosis: report of three cases and review of the literature

In the past, osteomyelitis was frequent and characterized by a prolonged course, treatment response uncertainty, and occasional disfigurement. Today, the disease is less common; it is believed that the decline in prevalence may be attributed to increased availability of antibiotics and improvement of overall health patterns. Currently, more common osteomyelitis variants are seen, namely, osteoradionecrosis (ORN) and bisphosphonate-related osteonecrosis of the jaws (BRONJ). Osteomyelitis, ORN, and BRONJ can present with similar symptoms, signs, and radiographic findings. However, each condition is a separate entity, with different treatment approaches. Thus, accurate diagnosis is essential for adequate management and improved patient prognosis. The aim of this paper is to report three cases of inflammatory lesions of the jaws—osteomyelitis, ORN, and BRONJ—and to discuss their etiology, clinical aspects, radiographic findings, histopathological features, treatment options, and preventive measures.

Factors predicting the prognosis of oral alendronate-related osteonecrosis of the jaws: a 4-year cohort study

BACKGROUND

Studies concerning prognostic factors specific for alendronate-related osteonecrosis of the jaws (ONJ) are rare.

METHODS

We surveyed a cohort of 100 osteoporotic patients with 111 alendronate-related ONJ lesions treated during a 4-year period. Prognostic values of clinical variables and serum markers of bone turnover were assessed by univariate and multivariate analyses.

RESULTS

The cumulative complete response rate at 6 months was 48.65%. Serum bone-specific alkaline phosphatase (BSAP) level >10 μg/L, lesion depth ≦ 10 mm, and lesions in anterior regions denoted a better chance of healing within 6 months and the adjusted hazard ratios were 2.48 (95% confidence interval [CI], 1.41-4.37), 2.71 (95% CI, 1.57-4.70), and 3.94 (95% CI, 1.87-8.30), respectively.

CONCLUSIONS

Early discovery of lesions and prevention of their deeper extension are crucial for improving the prognosis of alendronate-related ONJ. A higher pretreatment level of BSAP indicates a better prognosis.

Cone beam computed tomography and intraoral radiography for diagnosis of dental abnormalities in dogs and cats

The development of veterinary dentistry has substantially improved the ability to diagnose canine and feline dental abnormalities. Consequently, examinations previously performed only on humans are now available for small animals, thus improving the diagnostic quality. This has increased the need for technical qualification of veterinary professionals and increased technological investments. This study evaluated the use of cone beam computed tomography and intraoral radiography as complementary exams for diagnosing dental abnormalities in dogs and cats. Cone beam computed tomography was provided faster image acquisition with high image quality, was associated with low ionizing radiation levels, enabled image editing, and reduced the exam duration. Our results showed that radiography was an effective method for dental radiographic examination with low cost and fast execution times, and can be performed during surgical procedures.

Use of cone-beam computerized tomography for evaluation of bisphosphonate-associated osteonecrosis of the jaws in an experimental rat model

BACKGROUND

Bisphosphonate-induced osteonecrosis of the jaw (BONJ) is a frequently reported complication. The aim of this study was to investigate the clinical and histopathological presentation of BONJ with the Hounsfield score and to evaluate the reliability of the score for determining necrosis in an animal model.

MATERIAL/METHODS

Eighty rats were prospectively and randomly divided into two groups of 40 each: a control group and an experimental group. Half of the animals from each group underwent extraction of the left mandibular molars, and the other half underwent extraction of the left maxillary molars under pentobarbital-induced general anesthesia. All animals were euthanized 28 days after tooth extraction. Maxillae and mandibles were extracted, cone beam computed tomography (CBCT) was performed, and Hounsfield scores were evaluated.

RESULTS

The Hounsfield scores of the experimental group were found to be compatible with chronic osteomyelitis and periosteal reactions. The Hounsfield scores of the control group were compatible with a healthy healing period.

CONCLUSION

In light of these results, both cone beam computed tomography (CBCT) and the Hounsfield Units (HU) evaluations together are thought to be efficient in the diagnosis of BONJ.

Bisphosphonate-Related Osteonecrosis of the Jaw Bone: Radiological Pattern and the Potential Role of CBCT in Early Diagnosis

Objectives

To systematize the clinico-radiological symptoms and course of bisphosphonate-related osteonecrosis of jaw bone and toevaluate the diagnostic potential of various radiological techniques to detect mild osteonecrosis in each stage of the disease.

Material and Methods

The sample consisted of 22 patients previously diagnosed with extraoral malignant disease. Diagnosis was based on a clinical examination in conjunction to digital panoramic radiography and cone beam computed tomography (CBCT). Two dentomaxillofacial radiologists reviewed all images.

Results

Twenty patients showed mandibular involvement clinically, while two others had a maxillary involvement. Four stages of the disease were proposed based on the clinico-radiological findings. Subclinical cortical and lamina dura thickening was detected with only three-dimensional CBCT and periapical images, while ulceration and cortical bone thickening was detected only by three-dimensional CBCT. Mixed sclerotic, lytic bone destruction involving alveolar and basal bone with or without encroachment on the mandibular canal, pathological mandibular fractures were detected by two-dimensional panoramic and three-dimensional CBCT images. Other findings are non healing extraction sockets, periapical radiolucencies, osteolysis, sequestra, oroantral fistula, and periosteal new bone formation.

Conclusions

The present study showed that bisphosphonate-related osteonecrosis of jaw bone occurs in four distinct clinico-radiological stages. For mild cases, panoramic image diagnosis was much less obvious, whereas cone beam computed tomography was able to fully characterise the bony lesions and describe their extent and involvement of neighbouring structures in all cases. Thus cone beam computed tomography might better contribute to the prevention of bisphosphonate-related osteonecrosis of jaw bone as well to the disease management.

Modern dental imaging: a review of the current technology and clinical applications in dental practice

A review of modern imaging techniques commonly used in dental practice and their clinical applications is presented. The current dental examinations consist of intraoral imaging with digital indirect and direct receptors, while extraoral imaging is divided into traditional tomographic/panoramic imaging and the more recently introduced cone beam computed tomography. Applications, limitations and current trends of these dental "in-office" radiographic techniques are discussed.

Tomografia computadorizada de feixe cônico na odontologia veterinária: descrição e padronização da técnica

Onze cães e quatro gatos, portadores de alterações buco-dentárias e atendidos no Centro Veterinário do Gama, em Brasília, DF, foram submetidos à tomografia computadorizada de feixe cônico. Os exames foram realizados em um tomógrafo i-CAT, utilizando para aquisição das imagens, altura de seis centímetros, tempo de 40 segundos, 0,2 voxel, 120 kilovolts e 46,72 miliampéres por segundo. O melhor posicionamento dos animais para realização do exame foi definido neste estudo. Esse é um fator fundamental para a realização do exame, que necessitou um protocolo anestésico simples e seguro, em função do tempo mínimo necessário à obtenção das imagens. Várias alterações e enfermidades foram identificadas, com extrema acurácia, credenciando a tomografia computadorizada de feixe cônico como um exame seguro, acessível e exeqüível e que pode ser incorporado à rotina odontológica das clínicas de pequenos animais.

Cone-beam imaging in dentistry

Cone-beam imaging has gained broad acceptance in dentistry in the last 5 years. The purpose of this review is to describe the use in dentistry and consider issues requiring further development. Cone-beam machines emit an x-ray beam shaped liked a cone rather than a fan as in conventional computed tomography (CT) machines. After this beam passes through the patient the remnant beam is captured on an amorphous silicon flat panel or image intensifier/charge-coupled device (CCD) detector. The beam diameter ranges from 4 to 30 cm and exposes the head in one pass around the patient capturing from 160 to 599 basis images. These images are used to compute a volume from which planar or curved reconstructions can be extracted in any orientation. Voxels are isotropic and can be as small as 0.125 mm. 3-D images of bone or soft tissue surfaces can also be generated. In dentistry the most common indications for cone-beam imaging are assessment of the jaws for placement of dental implants, evaluation of the temporomandibular joints for osseous degenerative changes, examination of teeth and facial structures for orthodontic treatment planning, evaluation of the proximity of lower wisdom teeth to the mandibular nerve prior to extraction, and evaluation of teeth and bone for signs of infections, cysts, or tumors. Cone-beam images have largely replaced conventional tomography for these tasks. The effective dose from cone-beam imaging ranges from 6 to 477 microSv. The cost of the equipment is relatively low, about $150,000 to $300,000. Issues to be considered are the training of individuals making and interpreting cone-beam images, as well as means to further reduce patient exposure.

Comparison of cone beam computed tomography imaging with physical measures

OBJECTIVES

The goal of this study was to determine the accuracy of measuring linear distances between landmarks commonly used in orthodontic analysis on a human skull using two cone beam CT (CBCT) systems.

METHODS

Measurements of length were taken using volumetric data from two CBCT systems and were compared with physical measures using a calliper applied to one human adult skull. Landmarks were identified with chromium steel balls embedded at 32 cranial and 33 mandibular landmarks and the linear measures were taken with a digital calliper. The skull was then scanned with two different CBCT systems: the NewTom QR DVT 9000 (Aperio Inc, Sarasota, FL) and the Hitachi MercuRay (Hitachi Medico Technology, Tokyo, Japan). CT data including the landmark point data were threshold segmented using CyberMed's CB Works software (CB Works 1.0, CyberMed Inc., Seoul, Korea). The resulting segmentations were exported from CB Works as VRML (WRL) files to Amira software (Amira 3.1, Mercury Computer Systems GmbH, Berlin, Germany).

RESULTS

The error was small compared with the gold standard of the physical calliper measures for both the NewTom (0.07+/-0.41 mm) and CB MercuRay (0.00+/-0.22 mm) generated data. Absolute error to the gold standard was slightly positive, indicating minor compression relative to the calliper measurement. The error was slightly smaller in the CB MercuRay than in the NewTom, probably related to a broader greyscale range for describing beam attenuation in 12-bit vs 8-bit data.

CONCLUSIONS

The volumetric data rendered with both CBCT systems provided highly accurate data compared with the gold standard of physical measures directly from the skulls, with less than 1% relative error.