[Osteoporosis detection using cone-beam computed tomography]. / Osteoporoseerkennung mittels digitaler Volumentomographie.

BACKGROUND: Osteoporosis is still underdiagnosed in Germany. OBJECTIVES: Is it possible to detect osteoporosis on the basis of a cone-beam computed tomography image of the mandible and several measuring methods? MATERIALS AND METHODS: Sixteen cone-beam computed tomography (CBCT) images from patients of the dental clinic at the University of Ulm were reinvestigated. When the CBCT images were processed the subjects were at least 55 years old, and the mandible was completely mapped on the image. Furthermore, a dual-energy X­ray absorptiometry scan or a CT bone mineral density test was required for every subject. The subjects were divided into an osteoporosis group and a control group. The computed tomography mental index (CTMI), the computed tomography mandibular index superior (CTI[S]) and the computed tomography mandibular index inferior (CTI[I]) were deployed for comparison of the groups. In the first instance a comparison of the osteoporosis and control groups was made for both male and female subjects. Subsequently, only the images of the female subjects were compared to each other. RESULTS: A possibility for osteoporosis can be expressed at CTMI values located < 3.0 mm. As well for CTI(S) < 0.18 and CTI(I) < 0.23. There arises a 66.7 % sensitivity and 70 % specificity for the mixed subject group and an 80 % sensitivity and 57.1 % specificity for the female subject group for CTMI and CTI(S). Furthermore, there are 50.0 % sensitivity and 70 % specificity for the mixed subject group and 60.0 % sensitivity and 57.1 % specificity for the female subject group for the CTI(I). CONCLUSION: CTMI, CTI(S) and CTI(I) are only suitable for osteoporosis detection to a limited extent.

Assessment of apical periodontitis by MRI: a feasibility study.

PURPOSE: The purpose of this clinical feasibility study was to evaluate the applicability of magnetic resonance imaging (MRI) for the assessment of apical periodontitis in direct comparison with cone beam CT (CBCT). MATERIALS AND METHODS: 19 consecutive patients (average age 43 ±â€Š13 years) with 34 lesions in total (13 molars, 14 premolars and 7 front teeth) were enrolled in this feasibility study. Periapical lesions were defined as periapical radiolucencies (CBCT) or structural changes in the spongy bone signal (MRI), which were connected with the apical part of a root and with at least twice the width of the periodontal ligament space. The location and dimension of the lesions were compared between MRI and CBCT. RESULTS: While mainly mineralized tissue components such as teeth and bone were visible with CBCT, complimentary information of the soft tissue components was assessable with MRI. The MRI images provided sufficient diagnostic detail for the assessment of the main structures of interest. Heterogeneous contrast was observed within the lesion, with often a clear enhancement close to the apical foramen and the periodontal gap.  No difference for lesion visibility was observed between MRI and CBCT. The lesion dimensions corresponded well, but were slightly but significantly overestimated with MRI. A heterogeneous lesion appearance was observed in several patients. Four patients presented with a well circumscribed hyperintense signal in the vicinity of the apical foramen. CONCLUSION: The MRI capability of soft tissue characterization may facilitate detailed analysis of periapical lesions. This clinical study confirms the applicability of multi-contrast MRI for the identification of periapical lesions. KEY POINTS: MRI can be applied for the identification of periapical lesions without ionizing radiation exposure. MRI might facilitate more detailed characterization of periapical lesions. MRI might provide more accurate lesion dimensions as X-ray-based methods.

Intraoral radiology in general dental practices - a comparison of digital and film-based X-ray systems with regard to radiation protection and dose reduction.

PURPOSE: The purpose of this study was to gain insight into the distribution and application of digital intraoral radiographic techniques within general dental practices and to compare these with film-based systems in terms of patient dose reduction. MATERIALS AND METHODS: 1100 questionnaires were handed out to general dental practitioners. Data was analyzed with respect to the type of system by using descriptive statistics and nonparametric tests, i.e. Kruskal-Wallis, Mann-Whitney and chi-square test (SPSS 20). RESULTS: 64% of the questioned dentists still use film-based radiology, 23% utilize storage phosphor plate (SPP) systems and 13% use a charge-coupled device (CCD). A strong correlation between the number of dentists working in a practice and the use of digital dental imaging was observed. Almost 3/4 of the film users work with E- or F-speed film. 45% of them refuse to change to a digital system. The use of lead aprons was popular, while only a minority preferred thyroid shields and rectangular collimators. A fourfold reduction of exposure time from D-speed film to CCD systems was observed. Due to detector size and positioning errors, users of CCD systems take significantly more single-tooth radiographs in total. Considering the number of radiographs per patient, there is only a slight tendency towards more X-rays with CCD systems. Up to image generation, digital systems seem to be as or even more difficult to handle than film-based systems, while their handling was favored after radiographic exposure. CONCLUSION: Despite a slight increase of radiographs taken with CCD systems, there is a significant dosage reduction. Corresponding to the decrease in exposure time, the patient dose for SPP systems is reduced to one half compared to film. The main issues in CCD technology are positioning errors and the size of the X-ray detectors which are difficult to eliminate. The usage of radiation protection measures still needs to be improved. KEY POINTS: ► Responsible use of digital intraoral radiology results in a significant dose reduction in everyday practice. ► The ALARA principle is only achieved by strict implementation of dose-reducing methods. ► The efforts to use dose-reducing devices must be increased.

Assessment of the effective doses from two dental cone beam CT devices.

OBJECTIVES: This study compares the effective dose for different fields of view (FOVs), resolutions and X-ray parameters from two cone beam CT units: the KaVo 3D (three-dimensional) eXam and the KaVo Pan eXam Plus 3D (KaVo Dental, Biberach, Germany). METHODS: Measurements were made using thermoluminescent dosemeter chips in a radiation analog dosimetry head and neck phantom. The calculations of effective doses are based on the ICRP 60 and ICRP 103 recommendations of the International Commission on Radiological Protection. RESULTS: Effective doses from the 3D eXam ranged between 32.8 µSv and 169.8 µSv, and for the Pan eXam Plus effective doses ranged between 40.2 µSv and 183.7 µSv; these were measured using ICRP 103 weighting factors in each case. The increase in effective dose between ICRP 60 and ICRP 103 recommendations averaged 157% for all measurements. CONCLUSIONS: Effective doses can be reduced significantly with the choice of lower resolutions and mAs settings as well as smaller FOVs to avoid tissues sensitive to radiation being inside the direct beam. Larger FOVs do not necessarily lead to higher effective doses.

Ultrashort echo time (UTE) MRI for the assessment of caries lesions.

OBJECTIVE: Direct in vivo MRI of dental hard tissues by applying ultrashort echo time (UTE) MRI techniques has recently been reported. The objective of the presented study is to clinically evaluate the applicability of UTE MRI for the identification of caries lesions. METHODS: 40 randomly selected patients (mean age 41 ± 15 years) were enrolled in this study. 39 patients underwent a conventional clinical assessment, dental bitewing X-ray and a dental MRI investigation comprising a conventional turbo-spin echo (TSE) and a dedicated UTE scan. One patient had to be excluded owing to claustrophobia. In four patients, the clinical treatment of the lesions was documented by intraoral pictures, and the resulting volume of the cavity after excavation was documented by dental imprints and compared with the MRI findings. RESULTS: In total, 161 lesions were identified. 157 (97%) were visible in the UTE images, 27 (17%) in the conventional TSE images and 137 (85%) in the X-ray images. In total, 14 teeth could not be analysed by MR owing to artefacts caused by dental fillings. All lesions appear significantly larger in the UTE images as compared with the X-ray and TSE images. In situ measurements confirm the accuracy of the lesion dimensions as observed in the UTE images. CONCLUSION: The presented data provide evidence that UTE MR imaging can be applied for the identification of caries lesions. Although the current data suggest an even higher sensitivity of UTE MRI, some limitations must be expected from dental fillings.

Quality assurance in digital dental radiography--justification and dose reduction in dental and maxillofacial radiology.

OBJECTIVE: To evaluate the implementation of quality assurance requirements for digital dental radiography in routine clinical practice. The results should be discussed by radiation protection authorities in the context of the relevant legal requirements and current debates on radiation protection. MATERIALS AND METHODS: Two hundred digital dental radiographs were randomly selected from the digital database of the Department of Dentistry's Dental and Maxillofacial Surgery Clinic, Ulm University, and evaluated for various aspects of image quality and compliance with radiographic documentation requirements. The dental films were prepared by different radiology assistants (RAs) using one of two digital intraoral radiographic systems: Sirona Heliodent DS, 60 kV, focal spot size: 0.7 mm (group A) or KaVo Gendex 765 DC, 65 kV, focal spot size: 0.4 mm (group B). RESULTS: Radiographic justification was documented in 70.5% of cases, and the radiographic findings in 76.5%. Both variables were documented in the patient records as well as in the software in 14% of cases. Clinical documentation of the required information (name of the responsible dentist and radiology assistant, date, patient name, department, tube voltage, tube current, exposure time, type of radiograph, film size, department and serial number of the dental radiograph) was 100% complete in all cases. Moreover, the department certified according to DIN ISO 9001:2008 specifications demonstrated complete clinical documentation of radiographic justifications and radiographic findings. The entire dentition was visible on 83% of the digital films. The visible area corresponded to the target region on 85.7% of the digital dental radiographs. Seven to 8.5% of the images were classified as "hypometric" or "hypermetric". CONCLUSIONS: This study indicates that improvements in radiology training and continuing education fordentists and dental staff performing x-ray examinations are needed to ensure consistent high quality of digital dental radiography. Implementation of internal radiological quality assurance programs, as required by public law in Germany since 2010 (SGB V), would appear prudent.

Comparison of cone beam computed tomography scans with and without simulation of head motion.

PURPOSE: To test for differences in image quality between 3D volumetric datasets acquired by cone beam computed tomography (CBCT) with and without simulation of head motion by visual analysis of individual image sections and by comparison of scan-based distance and Hounsfield unit (HU) measurements. MATERIALS AND METHODS: A total of 200 volumetric datasets were acquired with and without remote-controlled, simulated movement of a human cadaver head using the KaVo 3D eXam CBCT system. RESULTS: The "Landscape 8 x 8 cm Slide" mode provided a sufficient field of view at a low radiation dose. All datasets showed reproducible results. Our analysis showed that the level of image quality and image detail increased with increasing resolution. Linear distance measurements and HU measurements in the cone beam CT scans acquired without simulation of head motion were absolutely comparable to those obtained with head motion simulation. CONCLUSIONS: There is no practical difference in image quality between CBCT scans acquired with and without head motion if no long-term change in head position occurs during the acquisition process. Slight head movement has no clinically relevant effect on the geometric accuracy or visual image quality of cone beam CT scans.

Antibiotic resistance testing of the total implant-associated micro-flora and its pure isolates.

OBJECTIVE: The aim of the present study was to examine antibiotic resistant strains among the implant-associated microorganisms in vitro, first as mixed cultures and again as pure isolates for resistance to one of five antibiotics. METHODS: Samples were taken with sterile paper points from the deepest pocket of one implant per patient (n = 24) to culture the total oral micro-flora. The samples were streaked on agar (Schaedler or BHI) and incubated for 7 d in an anaerobic atmosphere. All colonies were rinsed off the plates, aliquots were added to top-agar. Susceptibility against antibiotics (ampicillin, ampicillin + sulbactam, azithromycin and penicillin, moxifloxacin) was determined using the Etest. Resistant strains were picked, purified and characterized, and the Etests were repeated with a selection of the pure isolates. RESULT: The majority of the mixed cultures (67 - 100 %) showed complete antibiotic resistance. No association with clinical parameters like pocket depth, bleeding on probing or insertion of implants into transplanted bone could be found. Smoking and the surface of the implant also had no influence. 23 % of the 597 resistant colonies contained only yeasts, mostly isolated from irradiated tumour patients. Of the 458 resistant bacteria, the majority were Gram-positive cocci or rods. Staphylococci and M. micros were detected occasionally. The resistance for the 138 selected pure isolates was in most cases lower than for the total micro-flora, irrespective of the antibiotic. CONCLUSIONS: The higher resistance of the total flora might be explained by synergistic interactions between its members.

Development of a new micro-endoscope for odontological application.

PURPOSE: Development and introduction of a new micro-endoscope called Visio Scope for multidiscipline use in dentistry. METHODS: During the development of the new micro-endoscope called Visio Scope testings in the following dental disciplines were performed: endodontics, periodontology, implantology, periapical surgery, prosthodontics, and laser treatment. In this first report, flexible micro-endoscopes with an external diameter of 1.0 mm as well as of 0.34 mm were used. RESULTS: There is a significant improvement in all tested disciplines concerning handling and flexibility, verification of radiologically not detectable findings. In this context, the endoscope has proved itself clearly superior to conventional optical aids, above all the surgical microscope. The working canal facilitates specific application of medication and irrigation solutions. CONCLUSIONS: The Visio Scope allows visual control of the extent of the bone defect and enables optical control after removal of concrements and granulation tissue, before possible regenerative measures. Root fractures and furcation invasion can be reliably documented. Optical control guarantees preoperative and postoperative success of treatment.