RDFNet: A Fast Caries Detection Method Incorporating Transformer Mechanism.

Dental caries is a prevalent disease of the human oral cavity. Given the lack of research on digital images for caries detection, we construct a caries detection dataset based on the caries images annotated by professional dentists and propose RDFNet, a fast caries detection method for the requirement of detecting caries on portable devices. The method incorporates the transformer mechanism in the backbone network for feature extraction, which improves the accuracy of caries detection and uses the FReLU activation function for activating visual-spatial information to improve the speed of caries detection. The experimental results on the image dataset constructed in this study show that the accuracy and speed of the method for caries detection are improved compared with the existing methods, achieving a good balance in accuracy and speed of caries detection, which can be applied to smart portable devices to facilitate human dental health management.

Imaging modalities to inform the detection and diagnosis of early caries.

BACKGROUND: The detection and diagnosis of caries at the earliest opportunity is fundamental to the preservation of tooth tissue and maintenance of oral health. Radiographs have traditionally been used to supplement the conventional visual-tactile clinical examination. Accurate, timely detection and diagnosis of early signs of disease could afford patients the opportunity of less invasive treatment with less destruction of tooth tissue, reduce the need for treatment with aerosol-generating procedures, and potentially result in a reduced cost of care to the patient and to healthcare services. OBJECTIVES: To determine the diagnostic accuracy of different dental imaging methods to inform the detection and diagnosis of non-cavitated enamel only coronal dental caries. SEARCH METHODS: Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 31 December 2018); Embase Ovid (1980 to 31 December 2018); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 31 December 2018); and the World Health Organization International Clinical Trials Registry Platform (to 31 December 2018). We studied reference lists as well as published systematic review articles. SELECTION CRITERIA: We included diagnostic accuracy study designs that compared a dental imaging method with a reference standard (histology, excavation, enhanced visual examination), studies that evaluated the diagnostic accuracy of single index tests, and studies that directly compared two or more index tests. Studies reporting at both the patient or tooth surface level were included. In vitro and in vivo studies were eligible for inclusion. Studies that explicitly recruited participants with more advanced lesions that were obviously into dentine or frankly cavitated were excluded. We also excluded studies that artificially created carious lesions and those that used an index test during the excavation of dental caries to ascertain the optimum depth of excavation. DATA COLLECTION AND ANALYSIS: Two review authors extracted data independently and in duplicate using a standardised data extraction form and quality assessment based on QUADAS-2 specific to the clinical context. Estimates of diagnostic accuracy were determined using the bivariate hierarchical method to produce summary points of sensitivity and specificity with 95% confidence regions. Comparative accuracy of different radiograph methods was conducted based on indirect and direct comparisons between methods. Potential sources of heterogeneity were pre-specified and explored visually and more formally through meta-regression. MAIN RESULTS: We included 104 datasets from 77 studies reporting a total of 15,518 tooth sites or surfaces. The most frequently reported imaging methods were analogue radiographs (55 datasets from 51 studies) and digital radiographs (42 datasets from 40 studies) followed by cone beam computed tomography (CBCT) (7 datasets from 7 studies). Only 17 studies were of an in vivo study design, carried out in a clinical setting. No studies were considered to be at low risk of bias across all four domains but 16 studies were judged to have low concern for applicability across all domains. The patient selection domain had the largest number of studies judged to be at high risk of bias (43 studies); the index test, reference standard, and flow and timing domains were judged to be at high risk of bias in 30, 12, and 7 studies respectively. Studies were synthesised using a hierarchical bivariate method for meta-analysis. There was substantial variability in the results of the individual studies, with sensitivities that ranged from 0 to 0.96 and specificities from 0 to 1.00. For all imaging methods the estimated summary sensitivity and specificity point was 0.47 (95% confidence interval (CI) 0.40 to 0.53) and 0.88 (95% CI 0.84 to 0.92), respectively. In a cohort of 1000 tooth surfaces with a prevalence of enamel caries of 63%, this would result in 337 tooth surfaces being classified as disease free when enamel caries was truly present (false negatives), and 43 tooth surfaces being classified as diseased in the absence of enamel caries (false positives). Meta-regression indicated that measures of accuracy differed according to the imaging method (Chi2(4) = 32.44, P < 0.001), with the highest sensitivity observed for CBCT, and the highest specificity observed for analogue radiographs. None of the specified potential sources of heterogeneity were able to explain the variability in results. No studies included restored teeth in their sample or reported the inclusion of sealants. We rated the certainty of the evidence as low for sensitivity and specificity and downgraded two levels in total for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the in vitro studies, and the observed inconsistency of the results. AUTHORS' CONCLUSIONS: The design and conduct of studies to determine the diagnostic accuracy of methods to detect and diagnose caries in situ are particularly challenging. Low-certainty evidence suggests that imaging for the detection or diagnosis of early caries may have poor sensitivity but acceptable specificity, resulting in a relatively high number of false-negative results with the potential for early disease to progress. If left untreated, the opportunity to provide professional or self-care practices to arrest or reverse early caries lesions will be missed. The specificity of lesion detection is however relatively high, and one could argue that initiation of non-invasive management (such as the use of topical fluoride), is probably of low risk. CBCT showed superior sensitivity to analogue or digital radiographs but has very limited applicability to the general dental practitioner. However, given the high-radiation dose, and potential for caries-like artefacts from existing restorations, its use cannot be justified in routine caries detection. Nonetheless, if early incidental carious lesions are detected in CBCT scans taken for other purposes, these should be reported. CBCT has the potential to be used as a reference standard in diagnostic studies of this type. Despite the robust methodology applied in this comprehensive review, the results should be interpreted with some caution due to shortcomings in the design and execution of many of the included studies. Future research should evaluate the comparative accuracy of different methods, be undertaken in a clinical setting, and focus on minimising bias arising from the use of imperfect reference standards in clinical studies.

Morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces.

PURPOSE: The prolonged change in the head posture alters the morphological characteristics of cervical vertebrae. The difference in the head posture among subjects with short, normal, and long anterior facial heights might have a significant influence on the morphological characteristics of cervical vertebrae. Thus, the present study was conducted to evaluate the morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces. METHODS: Based on Frankfort mandibular plane angle (FMA) on lateral cephalograms, 135 subjects were equally divided into three groups, i.e. Group I [Short face], II [Normal face], and III [Long face]. The angular variables like Atlas-dens angle (ADA), Pars interarticularis-dens angle (PDA), Pars interarticularis-vertebrae angle of C3 vertebrae (PVA3), Pars interarticularis-vertebrae angle of C4 vertebrae (PVA4), Lamina-Pars interarticularis angle of C2 vertebrae (LP2), Lamina-Pars interarticularis angle of C3 vertebrae (LP3), and Lamina-Pars interarticularis angle of C4 vertebrae (LP4) in the first four cervical vertebrae were measured, analyzed, and compared. Descriptive statistics, analysis of variance, Bonferroni, and Pearson's correlation coefficient tests were used. The P value of 0.05 was considered as the level of significance. RESULTS: All parameters except PDA and PVA3 were comparable among the groups. The PDA was 54.350 ± 1.870, 57.890 ± 1.550, and 60.290 ± 2.830 in Group I, II, and III, respectively; these differences were statistically significant [P < 0.001]. The PVA3 was 42.700 ± 5.640 in Group I, 45.850 ± 3.820 in Group II, and 45.590 ± 5.530 in Group III subjects that were also statistically significant [P < 0.01]. A fairly strong positive correlation was observed between FMA and PDA. CONCLUSION: A significant difference was found in the PDA among subjects with short, normal, and long faces. The vertical height of the face had a strong correlation with the morphology of axis vertebra.

Evaluación radiográfica de la frecuencia y distribución de los nódulos pulpares / Radiographic evaluation of the frequency and distribution of pulp nodules

Objetivos: Estimar la prevalencia de nódulos pulpares y agujas cálcicas en pacientes atendidos en la Cátedra de Endodoncia, Facultad de Odontología, Universidad de Buenos Aires (CEFOUBA). Se analizaron radiografías de 1866 piezas dentarias, con ápices maduros, de pacientes de ambos géneros, mayores de 15 años, tratados en CEFOUBA, en el período comprendido entre junio-noviembre de 2018. Género, edad, grupo dentario, condición del diente, presencia de patología sistémica, y ubicación anatómica, fueron las variables registradas. Se calcularon intervalos de confianza 95%, método score de Wilson. Se utilizó test z para diferencias de proporciones. El porcentaje de piezas con calcificaciones superó significativamente a piezas sin calcificaciones (z= 6,076; P<0,05). Porcentaje de piezas en mujeres fue significativamente mayor al de hombres (z=24,31; P<0,05). Porcentaje de piezas de las cuartas y quitas décadas de la vida (61%) superó significativamente a las demás décadas (39%) (z=9,88; P<0,05). El porcentaje de piezas con caries fue significativamente mayor al resto de las piezas con otras condiciones (41%) (z= 8,074; P<0,05). El porcentaje de piezas en pacientes sanos (77%) fue significativamente mayor al resto de las condiciones (23%) (z=24,310; P<0,05). El porcentaje de calcificaciones en cámara (78%) fue significativamente mayor a las del conducto (22%) (z=25,21; P<0,05). En conclusión, la presencia de este tipo de calcificaciones es frecuente en molares de pacientes femeninos y edad adulta. Es importante detectarlos radiográficamente porque complican la realización del tratamiento endodóntico, especialmente si están adheridos y obliteran la entrada de los conductos (AU)

Novel methodology for measuring intraoral wear in enamel and dental restorative materials.

OBJECTIVES: To test the hypotheses that (a) the chairside/handheld dental scanner combined with a metrology software will measure clinical wear in vivo in agreement with measurements from X-ray computed microtomography and; (b) polished monolithic zirconia does not cause accelerated wear of opposing enamel. MATERIALS AND METHODS: Thirty single crowns were randomized to receive a monolithic zirconia or metal-ceramic crown. Two non-restored opposing teeth in the same quadrants were identified to serve as enamel controls. After cementation, quadrants were scanned using an intraoral dental scanner. Patients were recalled at 6-months and 1-year for re-scanning. Scanned images were compared using a metrology software to determine maximum vertical wear of teeth. The accuracy of the scanning measurements from this new method was compared with X-ray computed microtomography (micro-CT) measurements. Statistical analysis was performed using Mann-Whitney U test to determine significant differences between wear of enamel against zirconia, metal-ceramic or enamel. Linear regression analysis determined agreement between measurements obtained using intraoral scanning and micro-CT. RESULTS: Regression analysis demonstrated that there is a quantitative agreement between depth and volume measurements produced using intraoral scanning and the micro-CT methodologies. There was no significant difference between the wear of enamel against polished monolithic zirconia crowns and enamel against enamel. CONCLUSIONS: Intraoral scanning combined with a matching software can accurately quantify clinical wear to verify that monolithic zirconia exhibited comparable wear of enamel compared with metal-ceramic crowns and control enamel. Agreement between the intraoral scanner and the micro-CT was 99.8%. Clinical Trials.gov NCT02289781.

DENTAL INTRAORAL EXPOSURES IN PORTUGAL: FROM 1990 TO 2018.

Data from dental intraoral radiography quality controls was gathered from 1201 units (22% of the licensed X-ray units existing in Portugal), using film and digital image systems, between 2016 and 2018. The median incident air KERMA for standard superior molar tooth was evaluated in 0.9 mGy with the value of 1.3 mGy as the upper quartile. Comparisons with a 1990 published survey from dental exposures in Portugal were made. A 85% reduction for incident air KERMA per exposure was observed (6.0 mGy for the 1990 survey), which can be attributed to technical advances in the X-ray image receptors, as well as the implementation of legal requirements for technical acceptability of radiological units. It was also observed an increase of X-ray exams, which is related to an increase of dental practitioners, available radiological equipment and the level of dental healthcare.

ESTIMATION OF EFFECTIVE DOSE OF DENTAL X-RAY DEVICES.

This study aims to estimate the effective doses of dental X-ray devices under common scanning protocols. After putting TLDs in the Alderson Radiation Therapy Phantom, we exposed the phantom under common scanning protocols of three dental X-ray devices, namely CBCT, dental panoramic machine and intraoral round cone device. Then effective doses were calculated using the measured absorbed doses of organs and tissues. Tissue weighting factors recommended by the ICRP were adopted in the calculation. Effective doses under common scanning protocols of three Dental X-ray devices were obtained. The effective dose of dental CT was 0.20 mSv, and that of dental panoramic machine and intraoral radiography were 0.013 and 0.0050 mSv, respectively. The tissue absorbed doses of dental CT scan were 0.63 mGy of brain, 7.7 mGy of salivary glands, 8.7 mGy of thyroid and 4.0 mGy of the lens of the eye. The tissue absorbed doses from dental panoramic machine are 0.62 mGy of salivary glands and 0.25 mGy of thyroid. And finally the tissue absorbed dose of intraoral radiography was 0.80 mGy of salivary gland. Among the three dental X-ray devices studied, dental CBCT scan can cause much higher effective dose than the other two. Brain, salivary glands, thyroid and the lens of the eye are tissues receiving relatively higher absorbed doses.

Accuracy of Cone-beam Computed Tomographic Image Interpretation by Endodontists and Endodontic Residents.

INTRODUCTION: Limited field cone-beam computed tomography (CBCT) imaging has become a modality frequently used by endodontists to evaluate the teeth and surrounding tissues of their patients. Accurate image interpretation is vital to obtain needed treatment information as well as to discern coincidental findings that could be present. The goal of this study was to determine the accuracy of CBCT volume interpretation when performed by endodontists and endodontic residents. METHODS: Eighteen deidentified limited field CBCT scans were obtained and evaluated by an oral and maxillofacial radiologist and an endodontist experienced in reading CBCT images. Their collective findings were combined as the "gold standard" of interpretation for this investigation. Using standard CBCT software, 4 practicing endodontists and 5 second-year endodontic residents evaluated each scan and recorded any notable findings and whether or not each scan warranted referral to a radiology specialist. Their interpretations were then compared with the gold standard to determine accuracy and any significant differences among the groups. RESULTS: The overall accuracy was 58.3% for endodontists and 64.3% for residents. Paired t tests showed no statistically significant differences in accuracy between the 2 groups for findings in teeth or in bone, but residents were significantly better for maxillary sinus findings. Endodontists agreed with the gold standard 38.9% of the time and residents 49.8% of the time on necessity of referral. The Cohen kappa coefficient showed moderate agreement between the groups. CONCLUSIONS: Endodontists and residents had similar accuracy in CBCT scan evaluation. More training and experience are warranted for both groups in order to maximize image assessment accuracy.

[Evaluation of dental X-ray apparatus in terms of patient exposure to ionizing radiation]. / Ocena rentgenowskich aparatów stomatologicznych pod katem narazenia pacjentów na promieniowanie jonizujace.

BACKGROUND: The use of X-ray in dental procedures causes exposure of the patient to ionizing radiation. This exposure depends primarily on the parameters used in tooth examination. The aim of the study was to determine the patients exposure and to assess the technical condition of X-ray tubes. MATERIAL AND METHODS: Seventeen hundred dental offices were covered by the questionnaire survey and 740 questionnaires were sent back. Direct measurements were performed in 100 units by using the thermoluminescent detectors and X-ray films. RESULTS: The results showed that the most commonly used exposure time is 0.22±0.16 s. The average entrance dose for the parameters used most commonly by dentists is 1.7±1.4 mGy. The average efficiency of X-ray tube estimated on the basis of exposures is 46.5±23.7 µGy/mAs. CONCLUSIONS: The study results indicate that the vast majority of X-ray tubes meet the requirements specified in the binding regulations. Med Pr 2017;67(4):491-496.

Assessing Bone Type of Implant Recipient Sites by Stereomicroscopic Observation of Bone Core Specimens: A Comparison With the Assessment Using Dental Radiography.

BACKGROUND: The aim of the study is to determine if bone quality evaluation of surgically obtained bone core specimens using a stereomicroscope is reliable for determining bone quality at implant recipient sites. METHODS: Bone quality was presurgically assessed in 122 edentulous ridges obtained from 62 patients using periapical radiographs and categorized according to the Lekholm and Zarb classification. During surgery, bone specimens were trephined, and bone types were immediately classified using a stereomicroscope. Microarchitectural characteristics of bone cores were evaluated after being scanned using microcomputed tomography (micro-CT). RESULTS: Bone types of implant sites categorized from radiography and stereomicroscope had statistically similar distribution but poor interrater agreement. Using micro-CT, maxillae and mandibles showed significant differences in microarchitectural characteristics of bone cores. Bone volume (BV), total volume (TV), and trabecular thickness (Tb.Th) increased, whereas bone surface density (BS/BV) and open porosity (Po.[Op]) decreased in mandibular bone cores compared with those in maxillary bone cores. Moreover, micro-CT values of BV/TV and Po.(Op) statistically correlated with bone types assessed by stereomicroscopy, particularly in mandibles (adjusted means of BV/TV of Type 2 to 4 versus Type 1 decreasing from -9.88%, -15.09%, -29.31%; those of Po.(Op) ranged from 9.77%, 15.06%, 29.52% in an upward trend). However, such correlations were not found in maxillae or when bone types were classified using periapical radiographs. CONCLUSIONS: Caution is needed when using presurgical periapical radiographs to predict bone quality at implant recipient sites. Surgically preserved bone core specimens, whenever obtainable, might offer additional information to accurately assess bone quality, particularly at mandibular implant sites.

[Frequency and doses of diagnostic and interventional X­ray applications : Trends between 2007 and 2014]. / Häufigkeit und Dosis diagnostischer und interventioneller Röntgenanwendungen : Trends zwischen 2007 und 2014.

BACKGROUND: In Germany, approximately 95% of man-made radiation exposure of the population results from diagnostic and interventional X­ray procedures. Thus, radiation protection of patients in this field of application is of great importance. OBJECTIVE: Quantification and evaluation of current data on the frequency and doses of X­ray procedures as well as temporal trends for the years 2007-2014. MATERIAL AND METHODS: For outpatients the frequency of X­ray procedures was estimated using reimbursement data from health insurances and for inpatients by means of hospital statistics. For the years under review, representative values for the effective dose per X­ray application were determined mainly from data reported by X­ray departments to the competent authorities. RESULTS: In 2014 approximately 140 million X­ray procedures were performed in Germany with some 40% from dental examinations. On average 1.7 procedures per inhabitant and year were almost constantly carried out between 2007 and 2014. Besides dental diagnostics, X­ray examinations of the skeleton and thorax were performed most frequently. The number of computed tomography (CT) examinations increased by approximately 40%. The increase in magnetic resonance imaging (MRI) was even more pronounced with approximately 55% but overall CT examinations were still performed more often than MRI. The doses per X­ray procedure were only slightly reduced, despite the various dose reduction approaches established in recent years; therefore, the mean effective dose per inhabitant increased from approximately 1.4 mSv in 2007 to 1.6 mSv in 2014, mainly due to the increasing frequency of CT examinations. CONCLUSION: The principles of justification and optimization of radiological procedures are to be consistently applied in each individual instance, especially in the case of CT examinations.

Incidental Findings in Small Field of View Cone-beam Computed Tomography Scans.

INTRODUCTION: The use of cone-beam computed tomography (CBCT) in endodontics has increased in recent years. In clinical application of small field of view (FOV) CBCTs, these scans are not reviewed routinely by a radiologist. Studies of large FOV CBCT scans show the prevalence of incidental findings to be greater than 90%. The purpose of this study was to evaluate the prevalence of missed findings by endodontic residents as compared with a radiologist on small FOV CBCT scans. METHODS: Two hundred three small FOV CBCTs obtained for endodontic purposes were analyzed by an endodontic resident and a medical radiologist. The reported findings of each practitioner were compared to evaluate for missed incidental findings by the endodontic resident. RESULTS: The radiologist reported abnormalities in 176 of the 203 subjects (87%), with a total of 310 abnormalities reported. The endodontic resident reported abnormalities in 102 of the 203 subjects (50%), with a total of 126 abnormalities reported. The percentage of scans with any abnormality reported by the radiologist was significantly greater than the endodontic resident (P < .001). There was no significant difference between jaw locations in percentage of missed findings for the 3 most common types of finding-rarefying osteitis, sinusitis/mucosal lining thickening, and excess restorative material in the periapical area. Rarefying osteitis was missed significantly less than the other 2 types of findings (P < .001). CONCLUSIONS: A radiologist is significantly more likely to identify incidental findings in small FOV CBCT scans than an endodontic resident. Scan location had no significant association with the rate of missed findings.

Diagnostic services in Australia: service rates and characteristics of patients.

BACKGROUND: Diagnostic services are the most common area of dental service in Australia. The objective was to investigate differences in services per visit for examinations and radiographs in relation to the characteristics of patients receiving these services in terms of age and gender, aspects of visiting such as dental insurance and reasons for visit, and oral health such as number of teeth and presence of decay. METHODS: A random sample of Australian dentists was surveyed in 2009-2010. Data on diagnostic services and patient characteristics were collected from a service log. RESULTS: A total of 1148 dentists responded (response rate = 67%). Models adjusted for age and gender of patients showed that rates [Rate Ratio, 95% CI] of examinations were higher for insured patients [1.13; 1.06-1.21], while rates of radiographs were higher for emergency visits [1.25; 1.11-1.48]. Patients with 20 or more teeth had higher rates for examinations [1.15; 1.01-1.32] and radiographs [1.28; 1.02-1.60]. Decayed teeth were associated with lower examination rates [0.70; 0.65-0.76] but higher rates of radiographs [1.34; 1.16-1.55]. CONCLUSIONS: The finding that number of teeth was associated with higher rates of examinations and radiographs suggests that retention of teeth could be influencing the increasing rates of diagnostic services in Australia.

Oral Health Status of Patients Undergoing Treatment for Head and Neck Oncology in Northern Ireland.

This study aimed to collect data on the oral health status of patients undergoing treatment for head and neck oncology across Northern Ireland. Data were collected on all patients referred to the Northern Ireland Multidisciplinary Head and Neck Oncology Team for discussion and treatment planning. Each patient underwent pre-treatment dental assessment in the Centre for Dentistry, Queen's University Belfast, between June 2013 and November 2014. Data were collected from clinical oral examinations supplemented with intra-oral radiographs. During the course of the study 96 patients were assessed and the levels of dental disease observed in this cohort were high. On clinical examination 43% were diagnosed with caries and 46% with periodontal disease. Ten patients were completely edentate. The disease profile of this patient group presents significant challenges to dental services tasked with rendering patients dentally fit prior to undergoing oncology treatment.

Occupational radiation procedures and doses in South Korean dentists.

OBJECTIVES: Dentistry is among the occupations involving chronic exposure to ionizing radiation. Although several cohort studies on medical radiation workers have been conducted in some countries, only a few epidemiological studies on dentists have been performed to examine occupational radiation exposure worldwide. The aim of this study was to investigate occupational characteristics and radiation exposures in South Korean dentists. METHODS: A total of 658 dentists were surveyed from April 2012 to May 2013, and survey data were linked with dosimetry data from the National Dose Registry. Multiple linear regression analysis was used to identify the relationship between demographic or occupational factors and individual radiation doses. RESULTS: Of the dentists sampled, 78% were men, 51% were younger than age 40, and 61% began employment after 2000. The most frequent procedures performed by dentists were panoramic radiography, followed by intraoral and portable dental radiography. Male dentists were more frequently involved in radiation procedures, and a higher proportion of male than female dentists wore a lead apron for diagnostic radiology. The average annual effective dose was 0.18 mSv for male and 0.13 mSv for female dentists. Female dentists working in provincial areas had significantly higher average annual and cumulative effective doses than those in metropolitan areas. The cumulative effective doses were significantly greater for older dentists, those who entered the field in the 1990s, and those with longer employment duration. CONCLUSIONS: Our findings provided detailed information on work practices, number of procedures performed on a weekly basis, and occupational radiation doses, which enabled in-depth evaluation of occupational radiation exposure and work status among dentists.

High-quality slab-based intermixing method for fusion rendering of multiple medical objects.

The visualization of multiple 3D objects has been increasingly required for recent applications in medical fields. Due to the heterogeneity in data representation or data configuration, it is difficult to efficiently render multiple medical objects in high quality. In this paper, we present a novel intermixing scheme for fusion rendering of multiple medical objects while preserving the real-time performance. First, we present an in-slab visibility interpolation method for the representation of subdivided slabs. Second, we introduce virtual zSlab, which extends an infinitely thin boundary (such as polygonal objects) into a slab with a finite thickness. Finally, based on virtual zSlab and in-slab visibility interpolation, we propose a slab-based visibility intermixing method with the newly proposed rendering pipeline. Experimental results demonstrate that the proposed method delivers more effective multiple-object renderings in terms of rendering quality, compared to conventional approaches. And proposed intermixing scheme provides high-quality intermixing results for the visualization of intersecting and overlapping surfaces by resolving aliasing and z-fighting problems. Moreover, two case studies are presented that apply the proposed method to the real clinical applications. These case studies manifest that the proposed method has the outstanding advantages of the rendering independency and reusability.

Ex vivo evaluation of new 2D and 3D dental radiographic technology for detecting caries.

OBJECTIVES: Proximal dental caries remains a prevalent disease with only modest detection rates by current diagnostic systems. Many new systems are available without controlled validation of diagnostic efficacy. The objective of this study was to evaluate the diagnostic efficacy of three potentially promising new imaging systems. METHODS: This study evaluated the caries detection efficacy of Schick 33 (Sirona Dental, Salzburg, Austria) intraoral digital detector images employing an advanced sharpening filter, Planmeca ProMax(®) (Planmeca Inc., Helsinki, Finland) extraoral "panoramic bitewing" images and Sirona Orthophos XG3D (Sirona Dental) CBCT images with advanced artefact reduction. Conventional photostimulable phosphor images served as the control modality. An ex vivo study design using extracted human teeth, ten expert observers and micro-CT ground truth was employed. RESULTS: Receiver operating characteristic analysis indicated similar diagnostic efficacy of all systems (ANOVA p > 0.05). The sensitivity of the Schick 33 images (0.48) was significantly lower than the other modalities (0.53-0.62). The specificity of the Planmeca images (0.86) was significantly lower than Schick 33 (0.96) and XG3D (0.97). The XG3D showed significantly better cavitation detection sensitivity (0.62) than the other modalities (0.48-0.57). CONCLUSIONS: The Schick 33 images demonstrated reduced caries sensitivity, whereas the Planmeca panoramic bitewing images demonstrated reduced specificity. XG3D with artefact reduction demonstrated elevated sensitivity and specificity for caries detection, improved depth accuracy and substantially improved cavitation detection. Care must be taken to recognize potential false-positive caries lesions with Planmeca panoramic bitewing images. Use of CBCT for caries detection must be carefully balanced with the presence of metal artefacts, time commitment, financial cost and radiation dose.

Tomografia computadorizada de Cone Beam no diagnóstico de reabsorções radiculares externas / Cone Beam computed tomography in diagnosis of root resorption are external

Reabsorção é o termo utilizado na literatura médica e odontológica, para definir o processo pelo qual, tecidos mineralizados do organismo são destruídos e eliminados pela ação de células especializadas. As reabsorções dentárias podem ser classificadas de acordo com a superfície dentária afetada (interna, externa, interna-externa), a evolução do processo (transitória ou progressiva) e a natureza biológica do processo (inflamatória ou por substituição). Os traumatismos dentários representam a causa mais frequente de reabsorções radiculares externas na dentição permanente e resultam em um dano irreversível que pode levar à perda do elemento dental. Considerando-se que as reabsorções radiculares, na maioria das vezes, são eventos assintomáticos, os exames de imagem se tornam essenciais na fase de diagnóstico desta patologia. Tradicionalmente estes exames complementares eram realizados através de radiografias convencionais e posteriormente digitais. Entretanto, imagens fornecidas através de radiografias apresentam algumas limitações, como sobreposições, distorções e a formação de uma imagem bidimensional de uma estrutura tridimensional. Para suprir tais limitações, as imagens multiplanares têm sido amplamente utilizadas, destacando-se entre elas, a tomografia computadorizada de cone beam. Sendo assim, a proposta do presente trabalho foi, através do levantamento bibliográfico, avaliar o emprego da tomografia computadorizada de cone beam no diagnóstico das reabsorções radiculares externas. A literatura pesquisa demonstra a superioridade das TCCB para o diagnóstico das RRE, quando comparadas à radiografia periapical. Quanto menor o tamanho do voxel maior a acurácia do exame, principalmente para identificação de pequenas cavidades na região apical. Entretanto a literatura pertinente é dominada por estudos realizados ex vivo e não faz distinção entre os diferentes tipos de RR

Resorption is the term used in medical and dental literature to define the process which mineralized tissues are destroyed and eliminated by aclastic cells. Dental resorptions can be classified according to the affected dental surface (internal, external, internal-external), process evolution (transient or progressive) and the biological nature of the process (inflammatory or replacement). Dental trauma represents the most frequent cause of progressive external root resorption in the permanent dentition not rare resulting in irreversible loss of dental tissue that can lead to tooth loss. Considering that root resorptions are asymptomatic events, imaging procedures are essential in the diagnosis of such pathologies. Traditionally, these complementary examinations were performed through conventional and later digital radiographs. However, images provided through radiographs present some limitations, such as overlaps, distortions and a two-dimensional image of a three-dimensional structure. In order to overcome these limitations, the multiplanar images have been widely used, among them the computerized tomography of cone beam. Therefore, the present study aimed to review the use of CBCT to improve diagnosis and treatment planning of external root resorption. CBCT imaging appears to provide a superior validity and reliability in the detection of inflammatory external root resorption. The superior accuracy of CBCT imaging may result in the early detection of IERR and may help to determine their exact locations and extents. The smaller the voxel size the greater the accuracy of the exam, being important to identify small cavities in the apical region. However, literature is dominated by ex vivo studies and does not distinguish between different types of RER

Fast and Accurate Semiautomatic Segmentation of Individual Teeth from Dental CT Images.

In this paper, we propose a fast and accurate semiautomatic method to effectively distinguish individual teeth from the sockets of teeth in dental CT images. Parameter values of thresholding and shapes of the teeth are propagated to the neighboring slice, based on the separated teeth from reference images. After the propagation of threshold values and shapes of the teeth, the histogram of the current slice was analyzed. The individual teeth are automatically separated and segmented by using seeded region growing. Then, the newly generated separation information is iteratively propagated to the neighboring slice. Our method was validated by ten sets of dental CT scans, and the results were compared with the manually segmented result and conventional methods. The average error of absolute value of volume measurement was 2.29 ± 0.56%, which was more accurate than conventional methods. Boosting up the speed with the multicore processors was shown to be 2.4 times faster than a single core processor. The proposed method identified the individual teeth accurately, demonstrating that it can give dentists substantial assistance during dental surgery.