The effect of optimum, indication-specific imaging fields on the radiation exposure from CBCT examinations of impacted maxillary canines and mandibular third molars.

OBJECTIVE: Indication-specific optimum field-of-views (FOVs) have been assessed for CBCT scans of impacted maxillary canines and mandibular third molars, as 40∅ × 35 mm and 35∅ × 35 mm, respectively. The objective was to investigate possible changes in absorbed organs and effective doses, for these two imaging indications, performing CBCT examinations with optimum FOV sizes instead of commonly used FOVs. Additionally, radiation exposure-induced cancer risk was calculated for both imaging indications with optimum FOVs. METHODS: An adult female head phantom (ATOM 702-D, CIRS, Norfolk, VA, USA) was scanned using Planmeca Viso G7 CBCT-device (Planmeca, Helsinki, Finland). Scanning factors, different FOV sizes, dose-area product (DAP) values and anatomical FOV locations were used for Monte Carlo PCXMC-simulation and ImpactMC software. In the PCXMC- simulation, 10-year-old child and 30-year-old adult phantoms were used to estimating effective and absorbed organ doses. RESULTS: The effective dose varied from 58 µSv to 284 µSv for impacted maxillary canines, and from 38 µSv to 122 µSv for mandibular third molars, the lowest dose value for each corresponding to optimum FOV. Effective dose reduction between the optimum FOV and the smallest common FOV of 50∅ × 50 mm, maintaining other scanning factors constant, was 33% for impacted maxillary canines, and 45% for mandibular third molars. At all examinations, the highest absorbed organ doses were in salivary glands or in oral mucosa. CONCLUSIONS: Optimum FOVs, 40∅ × 35 mm for impacted maxillary canine and 35∅ × 35 mm for mandibular third molar, could decrease effective doses received by young patients, and improve radiation safety in these common CBCT imaging procedures.

Minimum size and positioning of imaging field for CBCT-scans of impacted lower third molars: a retrospective study.

BACKGROUND: Cone-beam Computed Tomography (CBCT) is widely used for preoperative 3D imaging of lower third molars. Hence, for this imaging indication, the present study aimed to define the minimum field-of-view (FOV) size and its optimum placement, to decrease radiation exposure, and highlight the need of computer-assisted FOV centering technique for dental CBCT devices. To facilitate proper placement of image field, lower second molar was chosen as reference. METHODS: The retrospective study included 50 CBCT-scans of 46 patients with mean age of 34 years. Based on the lower second molar, a three-dimensional coordinate was formed and the location of mandibular canal (MC) and the dimensions and locations of the lower third molars, and possible associated pathological findings were assessed. Accordingly, the FOV size and position for third-molar imaging were optimized, while ensuring encompassment of all relevant structures. RESULTS: The minimum cylindrical volume, covering lower third molars and MC, was 32.1 (diameter) × 31.6 (height) mm, placed in relation to the second molar crown, top 2.2 mm above cusp tips, anterior edge 6.7 mm in the front of the most distal point of the crown, and lingual edge 7.9 mm on the medial side of the lingual wall. CONCLUSIONS: The optimized FOV for lower third molars was smaller than common standard small FOVs. We recommend using FOV volume 3.5∅ × 3.5 cm for third molars without associated pathology. Accurate FOV protocols are essential for development of new CBCT-devices with computer-assisted and indication-specific FOV placement.

Minimum size and positioning of imaging field for CBCT scans of impacted maxillary canines.

OBJECTIVES: In children and adolescents, cone-beam computed tomography (CBCT) is frequently used for localization of unerupted or impacted teeth in the anterior maxilla. CBCT causes a higher radiation dose than conventional intraoral and panoramic imaging. The objective was to analyze the location of impacted canines in a three-dimensional coordinate and thereby optimize the CBCT field-of-view (FOV), for radiation dose reduction. MATERIALS AND METHODS: Location of 50 impacted maxillary canines of children under 17 years was retrospectively evaluated from CBCT scans. The minimum and maximum distances of any part of the right- and left-side canines to three anatomic reference planes were measured to assess the adequate size and position of a cylindrical image volume. RESULTS: A cylinder sized 39.0 (diameter)×33.2 (height) mm, with its top situated 13.8 mm above the hard palate, its medial edge 8.4 mm across the midline, and anterior edge 2.5 mm in front of the labial surface of maxillary central incisors fitted all the analyzed canines. CONCLUSIONS: In this sample, the FOV required for imaging maxillary impacted canines was smaller than the smallest FOV offered by common CBCT devices. We encourage development of indication-specific CBCT imaging programs and aids to facilitate optimum patient positioning. CLINICAL RELEVANCE: An impacted maxillary canine is a common dental problem and a frequent indication for 3D imaging particularly in growing individuals. This article focuses on the optimization of CBCT of impacted canines. Our recommendation of a reduced FOV promotes radiation safety.

A point-of-care test of active matrix metalloproteinase-8 predicts triggering receptor expressed on myeloid cells-1 (TREM-1) levels in saliva.

BACKGROUND: This cross-sectional study aims to investigate if a point-of-care (PoC) test of active matrix metalloproteinase-8 (aMMP-8) predicts levels of inflammation amplifier triggering receptor expressed on myeloid cells-1 (TREM-1) and its putative ligand the neutrophil peptidoglycan recognition protein 1 (PGLYRP1) in saliva. METHODS: Forty-seven adolescents, aged 15 to 17 years, were tested with aMMP-8 PoC test, which was followed by a full-mouth clinical examination of the assessment of periodontal, mucosal, and oral health. TREM-1 and PGLYRP1 levels were analyzed by ELISA. The immunofluorometric assay (IFMA) specific for aMMP-8 was used as the reference method. RESULTS: Fourteen saliva samples out of a total of 47 showed positivity for aMMP-8 PoC test. Both the TREM-1 and the aMMP-8 (IFMA) levels were significantly elevated among the aMMP-8 PoC test positives compared with the PoC test negatives (P < 0.05). Moreover, aMMP-8 levels assessed by IFMA showed a strong positive correlation with TREM-1 levels in saliva (r = 0.777, P < 0.001). The number of sites with a probing depth of ≥4 mm was significantly lower among the adolescents that had a negative aMMP-8 PoC test result, and TREM-1 levels < 75 pg/mL (P < 0.05). In contrast, adolescents with a positive aMMP-8 PoC test result (i.e., elevated aMMP-8 levels) together with elevated TREM-1 levels had a significantly higher number of periodontal pockets with ≥4 mm (P < 0.001). CONCLUSION: The present study validated usability of aMMP-8 PoC test for predicting "proinflammatory" salivary profile and periodontal health status in adolescents.

Low reproducibility between oral radiologists and general dentists with regards to radiographic diagnosis of caries.

AIM: Early clinical and radiological diagnosis of dental caries is one of the fundamental objectives of clinical dentistry because of the high frequency of the disease and severe complications if caries remains untreated, especially among the elderly and patients with immunodeficiency. Dental panoramic tomography (DPT) is a common radiographic method for evaluating dentition when indicated, especially in an adult population. The aim of this study was to assess the reproducibility of diagnosis between specialists in oral radiology and general dentists with regards to caries lesions based on DPTs of adults. MATERIAL AND METHODS: One-hundred DPTs taken from adult patients (average age 35) and then analyzed and reported on by 42 general dentists were then analyzed independently by two specialists in oral radiology with respect to caries lesions in the premolar and molar areas using radiographic criteria established for caries diagnosis. The general dentists versus oral radiologists were not calibrated before. Level of agreement between specialists and general dentists was measured using Cohen's kappa. RESULTS: Comparison between observations of general dentists and specialists in oral radiology showed that 61% of the caries lesions on proximal surfaces of premolars and molars observed by specialists went unobserved by general dentists. Cohen's kappa value for specialists was 0.85 (p < .001) and for each specialist and general dentists 0.48 (p < .001) and 0.44 (p < .001). CONCLUSIONS: The reproducibility between specialists in oral radiology and general dentists for detecting caries in DPTs was low.

Periodontal Initial Radiological Findings of Genetically Predisposed Finnish Adolescents.

INTRODUCTION: Periodontitis is a multifactorial infectious disease of the supporting tissues of teeth in which bacterial, genetic and lifestyle factors such as smoking have an important role. AIM: The aim was to examine if Bleeding On Probing (BOP ≥ 20%) and ≥ 4 mm deep pockets correlated with any suspicion of initial radiological findings of periodontitis and bone loss. We also investigated whether any pro-inflammatory-related candidate Single Nucleotide Polymorphisms (SNPs) were associated with any suspicion of radiological findings. MATERIALS AND METHODS: Altogether 47 generally healthy adolescent patients of one birth cohort had given their approval for their saliva samples to be used for DNA analysis. One participant was excluded after discrepant gender check. An oral radiologist analysed right and left bitewing radiographs of 47 patients. Clinical parameters such as BOP ≥ 20%, ≥ 4 mm pockets, Visible Plaque Index of all teeth (VPI%), as well as smoking habits were recorded. DNA was extracted and 71 SNPs from candidate genes for initial periodontitis were genotyped. The association between ≥ 4 mm pockets and BOP ≥ 20% with radiological findings and selected SNPs was modelled using logistic regression. RESULTS: Variants in Toll-Like Receptors 4 (TLR4) gene (rs498670) (OR=5.8, {CI95% 1.6-20.7}, p=0.02, FDR q-value=0.13) and TNFSF11 gene (rs2277438, OR=0.3 {CI95% 0.1-0.9}, p=0.002, FDR q-value=0.56) were associated with any suspicious radiological findings; however the significance vanished after False Discovery Rate analysis (FDR). The association between BOP ≥ 20% and any radiographic signs of periodontitis was found to be statistically significant, OR=1.6, CI 95% 1.0-2.4, p=0.04. CONCLUSION: Only TLR4 (rs498670) and TNFSF11 (rs2277438) genes were found to have a positive correlation with radiological findings suggestive of initial periodontitis after adjustment for smoking and visible plaque.

Pilot Study on the Genetic Background of an Active Matrix Metalloproteinase-8 Test in Finnish Adolescents.

BACKGROUND: In periodontitis, genetics and smoking play important roles in host immune system response. The aim of this study is to determine whether the genetic background of initial periodontitis and caries could be detected using an active matrix metalloproteinase (aMMP)-8 chairside test in Finnish adolescents. METHODS: Forty-seven participants gave approval for analysis of both oral fluid collection and DNA. An aMMP-8 chairside test was performed on participants (adolescents aged 15 to 17 years), and full-mouth clinical parameters of oral health were assessed including periodontal, oral mucosal, and caries status in Eastern Finland from 2014 to 2015. DNA was extracted from oral fluid samples and genotyped for 71 polymorphisms in 29 candidate genes for periodontitis. Results were analyzed using a logistic regression model. P values were corrected for multiple testing using false discovery rate (<0.05). RESULTS: aMMP-8 chairside test positivity and three or more ≥4 mm pockets were associated with vitamin D receptor (VDR) (rs2228570, P = 0.002, q = 0.04) and MMP3 (rs520540, rs639752, rs679620, P = 0.0009, 0.003, 0.003, q = 0.04, respectively). None of the other single-nucleotide polymorphisms studied showed a significant association with the aMMP-8 chairside test and at least one caries lesion positivity. CONCLUSION: Genetic polymorphisms of MMP3 and VDR are linked to initial periodontitis in Finnish adolescents, and the aMMP-8 chairside test can eventually detect initial periodontitis in young patients with predisposing genetic background.

Application of segmented dental panoramic tomography among children: positive effect of continuing education in radiation protection.

OBJECTIVES:: Dental panoramic tomography is the most frequent examination among 7-12-year olds, according to the Radiation Safety and Nuclear Authority of Finland. At those ages, dental panoramic tomographs (DPTs) are mostly obtained for orthodontic reasons. Children's dose reduction by trimming the field size to the area of interest is important because of their high radiosensitivity. Yet, the majority of DPTs in this age group are still taken by using an adult programme and never by using a segmented programme. The purpose of the present study was to raise the awareness of dental staff with respect to children's radiation safety, to increase the application of segmented and child DPT programmes by further educating the whole dental team and to evaluate the outcome of the educational intervention. METHODS:: A five-step intervention programme, focusing on DPT field limitation possibilities, was carried out in community-based dental care as a part of mandatory continuing education in radiation protection. Application of segmented and child DPT programmes was thereafter prospectively followed up during a 1-year period and compared with our similar data from 2010 using a logistic regression analysis. RESULTS:: Application of the child programme increased by 9% and the segmented programme by 2%, reaching statistical significance (odds ratios 1.68; 95% confidence interval 1.23-2.30; p-value < 0.001). The number of repeated exposures remained at an acceptable level. The segmented DPTs were most frequently taken from the maxillary lateral incisor-canine area. CONCLUSIONS:: The educational intervention resulted in improvement of radiological practice in respect to radiation safety of children during dental panoramic tomography. Segmented and child DPT programmes can be applied successfully in dental practice for children.

Ultrasonographic localization of the thyroid gland for its optimal shielding prior to lateral cephalometric radiography: a pilot study.

OBJECTIVES: Lateral cephalometric radiography is a common radiographic examination technique in children. The exclusion of the thyroid gland from the primary X-ray beam is important especially with children. However, patient treatment might require displaying the four most cranial cervical vertebrae (C1-C4) for the assessment of cervical vertebral maturation. Our aim was to present a safe way to display C1-C4 and exclude the thyroid gland from the X-ray beam during lateral cephalometric radiography. METHODS: The thyroid glands of 25, 7- to 12-year-old patients were localized by ultrasound examination and shielded prior to lateral cephalometric radiography. A roentgen-positive mark was taped on the patient's skin at the level of most cranial level of the thyroid gland in the midsagittal plane. After exposure, each lateral cephalometric radiograph (LCR) was analyzed for the visibility of the cervical vertebrae. The distance between the ear post and the highest edge of the thyroid shield (TS) at the lateral part of the neck was measured and compared with the distance between the centre of the radiological external auditory meatus, and a roentgen-positive mark was made on the LCR. RESULTS: 68% of the LCRs displayed C1-C4, and the rest of them displayed C1-C3. In all of the patients, the highest edge of the TS in the lateral parts of the neck was located in a higher position than the actual most cranial level of the thyroid gland. CONCLUSIONS: Despite localizing the thyroid gland prior to lateral cephalometric radiography, simultaneous visualization of C1-C4 and exclusion of the thyroid gland from the primary X-ray beam during lateral cephalometric radiography might not be completely possible in children because of the design and poor fitness of the TS.

Are children's dental panoramic tomographs and lateral cephalometric radiographs sufficiently optimized?

OBJECTIVES: Children are especially vulnerable to harmful effects of ionizing radiation. Cutting down the dimensions of the X-ray beam is the most effective way to reduce the patient dose. We evaluated the appropriateness of field-size in the most frequent radiographs, dental panoramic tomographs (DPTs) and lateral cephalometric radiographs (LCRs) among 7- to 12-year-olds. MATERIALS AND METHODS: The image field-size of 241 DPTs and 118 LCRs was analysed. The image field was considered appropriate when it did not include anatomic structures beyond the area of clinical interest. The image field was compared with factors such as the age of the patient, the radiographic equipment used and the programme selected. Moreover, we assessed the use of thyroid shield in LCR. RESULTS: The field-size was too large in 70% of the DPTs horizontally and in 96% vertically. None of the DPTs were segmented. Every LCR showed appropriate limitation anteriorly, but the image field was too large in 54% posteriorly, in 86% superiorly, and in 76% inferiorly. A thyroid shield had been used in only 71% of cases. CONCLUSION: Most DPTs and LCRs had been performed sub-optimally. An abundancy of DPTs had been taken using an adult programme, and the field-size had not been sufficiently adjusted in LCRs, possibly for technical reasons. To facilitate adherence to radiological best practice the equipment used for DPTs and LCRs should facilitate the adjustment of field-size in both the vertical and horizontal planes. In addition, those involved in taking radiographs should maintain their skills through regular update courses.

Type and location of findings in dental panoramic tomographs in 7-12-year-old orthodontic patients.

OBJECTIVE: The Radiation and Nuclear Safety Authority in Finland has paid attention to the large numbers of dental panoramic tomographs (DPTs), particularly in 7-12-year-old children. The majority of these radiographs are taken for orthodontic reasons. Because of the high radiosensitivity of children, the size of the irradiated field should be carefully chosen to yield the necessary diagnostic information at the lowest possible dose. The purpose of the present study was, therefore, to assess the outcome of DPTs within this age group in terms of type and location of pathological findings. It was also hypothesized that DPTs of orthodontic patients rarely display unrestored caries. MATERIALS AND METHODS: Four hundred and forty-one DPTs, taken of 7-12-year-old children in 2010-2014, were randomly sampled. The 413 of them (94%) that had been taken for orthodontic reasons were analysed. RESULTS: All pathologic findings were restricted to the tooth-bearing area and there was no pathology in the bone structure or any incidental findings in the region of temporomandibular joint. Unlike hypothesized, 27% of the orthodontic DPTs showed caries in deciduous teeth and 16% in permanent teeth. A sub-sample of 229 DPTs, analysed for developmental dental and occlusal problems, most commonly displayed crowding (50%), positional anomalies and local problems with tooth eruption (32%), as well as hyperodontia (15%). CONCLUSION: Inclusion of only the actual area of interest in the image field should be considered case-specifically as a means to reduce the radiation dose.

Quality assessment of orthodontic radiography in children.

OBJECTIVES: Numbers of dental panoramic tomographs (DPTs) and lateral cephalometric radiographs (LCRs) outweigh other radiographic examinations in 7- to 12-year-old Finns. Orthodontists and general practitioners (GPs) involved in orthodontics hold therefore the highest responsibility of the exposure of children to ionising radiation with its risks. Against this background, lack of reports on the quality of orthodontic radiography is surprising. The purpose of our study was to shed some light and draw the awareness of the orthodontic community on the subject by analyzing the quality of orthodontic radiography in Oral Healthcare Department of City of Helsinki, in the capital of Finland. MATERIALS AND METHODS: We analyzed randomly selected 241 patient files with DPTs and 118 patient files with LCRs of 7- to 12-year-olds for the indications of radiography, quality of referrals, status of interpretation, and number of failed radiographs. RESULTS: The majority of DPTs (95%) and all LCRs had been ordered for orthodontic reasons. Of the DPTs, 60% were ordered by GPs, and of the LCRs, 64% by orthodontists. The referrals were adequate for most DPTs (78%) and LCRs (73%), orthodontists being responsible for the majority of inadequate referrals. Of the DPTs, 80% had been interpreted. Of the LCRs, 65% lacked interpretation, but 67% had been analysed cephalometrically. Failed radiographs, leading to repeated exposure, were found in 2-3%. CONCLUSION: The quality assessment revealed that orthodontic radiography may not completely fulfill the criteria of good practice. Our results stress further need of continuing education in radiation protection among both orthodontists and GPs involved in orthodontics.

Dentomaxillofacial imaging with panoramic views and cone beam CT.

Panoramic and intraoral radiographs are the basic imaging modalities used in dentistry. Often they are the only imaging techniques required for delineation of dental anatomy or pathology. Panoramic radiography produces a single image of the maxilla, mandible, teeth, temporomandibular joints and maxillary sinuses. During the exposure the x-ray source and detector rotate synchronously around the patient producing a curved surface tomography. It can be supplemented with intraoral radiographs. However, these techniques give only a two-dimensional view of complicated three-dimensional (3D) structures. As in the other fields of imaging also dentomaxillofacial imaging has moved towards 3D imaging. Since the late 1990s cone beam computed tomography (CBCT) devices have been designed specifically for dentomaxillofacial imaging, allowing accurate 3D imaging of hard tissues with a lower radiation dose, lower cost and easier availability for dentists when compared with multislice CT. Panoramic and intraoral radiographies are still the basic imaging methods in dentistry. CBCT should be used in more demanding cases. In this review the anatomy with the panoramic view will be presented as well as the benefits of the CBCT technique in comparison to the panoramic technique with some examples. Also the basics as well as common errors and pitfalls of these techniques will be discussed. Teaching Points • Panoramic and intraoral radiographs are the basic imaging methods in dentomaxillofacial radiology.• CBCT imaging allows accurate 3D imaging of hard tissues.• CBCT offers lower costs and a smaller size and radiation dose compared with MSCT.• The disadvantages of CBCT imaging are poor soft tissue contrast and artefacts.• The Sedentexct project has developed evidence-based guidelines on the use of CBCT in dentistry.