Assessing current clinical eruption stage of mandibular third molars by dental panoramic radiography

OBJECTIVE

We examined whether dental panoramic radiography (PAN) can be used to identify the clinical stage of eruption of mandibular third molars at the time of radiological examination.

MATERIALS AND METHODS

Cross-sectional data included records from clinical oral examination and PANs of university students. In the retrospective analysis of 345 mandibular third molars in 189 participants (20% men, 80% women; mean age 20.7 years; standard deviation [SD] ± 0.6), clinical stages of eruption were compared with their radiographic depth in bone, inclination, and root development. Statistics included χ2, Mann-Whitney U tests, and logistic regression.

RESULTS

Significant (p < 0.001) predictor variables for assessing the clinical stage of eruption were radiographic depth in bone and inclination. All teeth radiologically at a depth of the cementoenamel (CE) junction of the neighbouring second molar or deeper were clinically unerupted. Above the CE junction, 80% of vertical and 97% of distoangular teeth were connected to the oral cavity, and 82% of mesioangular and 69% of horizontal teeth were clinically unerupted.

CONCLUSION

All teeth below or at the CE junction are clinically unerupted. Above the CE junction, stage of eruption should be assessed together with the inclination, but horizontally inclined teeth are recommended to be verified clinically.

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.

Is the third molar erupting at a younger age than before?

OBJECTIVES

The aim of this study was to update the much-cited knowledge, published over half a century ago, of the age of eruption of the third molar in the Finnish population.

METHODS

The study followed a retrospective and cross-sectional protocol and included 710 digital panoramic radiographs of patients (49.3% men, 50.7% women) aged 15-23 years visiting the public oral health care services of the City of Helsinki in 2015. Age and sex of the subjects were recorded. The radiographs were examined for inclination of the third molars in both jaws and vertically located teeth were further classified into four stages of eruption: (A) in bone, (B) alveolar emergence, (C) gingival emergence, and (D) complete emergence. Statistics included chi-squared, Mann-Whitney U, and median tests.

RESULTS

Of altogether 2502 third molars, 53.0% (n = 1325) were in vertical position. The median age of gingival emergence (stage C) of the third molar varied between 19.8 and 20.8 years, and the median age of reaching the occlusal level (stage D) between 20.8 and 21.8 years depending on sex and the jaw.

CONCLUSION

The median ages for the third molar to pierce the gum were lower than reported over half a century ago.

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.

Dental cone beam CT: An updated review

Cone beam computed tomography (CBCT) is a diverse 3D x-ray imaging technique that has gained significant popularity in dental radiology in the last two decades. CBCT overcomes the limitations of traditional two-dimensional dental imaging and enables accurate depiction of multiplanar details of maxillofacial bony structures and surrounding soft tissues. In this review article, we provide an updated status on dental CBCT imaging and summarise the technical features of currently used CBCT scanner models, extending to recent developments in scanner technology, clinical aspects, and regulatory perspectives on dose optimisation, dosimetry, and diagnostic reference levels. We also consider the outlook of potential techniques along with issues that should be resolved in providing clinically more effective CBCT examinations that are optimised for the benefit of the patient.

The Impact of the Renin-Angiotensin-Aldosterone System on Inflammation, Coagulation, and Atherothrombotic Complications, and to Aggravated COVID-19

Atherosclerosis is considered a disease caused by a chronic inflammation, associated with endothelial dysfunction, and several mediators of inflammation are up-regulated in subjects with atherosclerotic disease. Healthy, intact endothelium exhibits an antithrombotic, protective surface between the vascular lumen and vascular smooth muscle cells in the vessel wall. Oxidative stress is an imbalance between anti- and prooxidants, with a subsequent increase of reactive oxygen species, leading to tissue damage. The renin-angiotensin-aldosterone system is of vital importance in the pathobiology of vascular disease. Convincing data indicate that angiotensin II accelerates hypertension and augments the production of reactive oxygen species. This leads to the generation of a proinflammatory phenotype in human endothelial and vascular smooth muscle cells by the up-regulation of adhesion molecules, chemokines and cytokines. In addition, angiotensin II also seems to increase thrombin generation, possibly via a direct impact on tissue factor. However, the mechanism of cross-talk between inflammation and haemostasis can also contribute to prothrombotic states in inflammatory environments. Thus, blocking of the renin-angiotensin-aldosterone system might be an approach to reduce both inflammatory and thrombotic complications in high-risk patients. During COVID-19, the renin-angiotensin-aldosterone system may be activated. The levels of angiotensin II could contribute to the ongoing inflammation, which might result in a cytokine storm, a complication that significantly impairs prognosis. At the outbreak of COVID-19 concerns were raised about the use of angiotensin converting enzyme inhibitors and angiotensin receptor blocker drugs in patients with COVID-19 and hypertension or other cardiovascular comorbidities. However, the present evidence is in favor of continuing to use of these drugs. Based on experimental evidence, blocking the renin-angiotensin-aldosterone system might even exert a potentially protective influence in the setting of COVID-19.

Is dental panoramic tomography appropriate for all young adults because of third molars?

OBJECTIVE

The purpose of this study was to determine, if a dental panoramic tomograph (DPT) is appropriate for every young adult due to third molars.

MATERIALS AND METHODS

The study sample consisted of 217 university students (20% men and 80% women; mean age 20.7 years; SD ± 0.6 years) and included a questionnaire about symptoms caused by third molars, clinical oral examination of third molars, and a DPT. Subjects were divided into the following groups: subjects with a clinical indication for a DPT and subjects without such indication. The DPTs were then examined for findings regarding third molars.

RESULTS

Clinical indication for a DPT was observed in 64% of the subjects. Radiography revealed an additional 1.4% of the subjects with ≥1 radiographic signs of disease in relation to their third molars. Also, an additional 27% of the subjects had ≥1 other radiographic findings in relation to third molars that may have affected the clinical decision making.

CONCLUSIONS

In our study population, clinically undetectable pathology cannot be considered as an indication for a DPT. However, if prevailing clinical practice supports preventive removals and detecting or monitoring of unerupted third molars, a referral to DPT can be considered as good clinical practice.

The role of magnetic order in VOCl

VOCl and other transition metal oxychlorides are candidate materials for next-generation rechargeable batteries. We have investigated the influence of the underlying magnetic order on the crystallographic and electronic structure by means of density functional theory. Our study shows that antiferromagnetic ordering explains the observed low-temperature monoclinic distortion of the lattice, which leads to a decreased distance between antiferromagnetically coupled V-V nearest neighbors. We also show that the existence of a local magnetic moment removes the previously suggested degeneracy of the occupied levels, in agreement with experiments. To describe the electronic structure, it turns out crucial to take the correct magnetic ordering into account, especially at elevated temperature.

Abstract P1-16-09: Low-dose chemotherapy (CT) + bevacizumab (Bev) combined with unchanged endocrine treatment (ET) in patients with recurrent luminal breast cancer progressing during ET – Effect determined by standard imaging and changes in ctDNA and CTC during treatment

Background: Several mechanisms are involved in the development of endocrine resistance, such as mutations in the ESR1, PIK3CA, and TP53 genes and/or up-regulation of tyrosine kinase receptors such as the endothelial growth factor (VEGF) receptor. Preclinical data have revealed that sensitivity to endocrine therapy may be restored if these pathways are blocked.

Aims: To investigate the progression-free survival (PFS), overall response rate (ORR), and the toxicity of the study treatment. To use circulating tumor cells (CTC) and circulating tumor DNA (ct-DNA) at base-line and during treatment for next generation sequencing (NGS) to investigate whether changes in tumor mutations or in levels of CTC/ct-DNA correlate to treatment efficacy.

Patients and methods: Thirty-two patients aged 46-77 years with confirmed advanced breast cancer (ABC) progressing during ET were included. Treatment consisted of unchanged ET with the addition of cyclophosphamide 50mg x 1 and capecitabine 500mg x 3 daily + bevacizumab 15mg/kg iv. every third week (q21). Blood samples for analysis of CTC and ctDNA were collected at base-line, after the 1st and 2nd course, and at progression. CTC were isolated by use of an immune-magnetic selection (ADNA-test) and sequenced by NGS. ctDNA were analysed by the SiMSen-Seq (Simple Multiplexed PCR-based barcoding of DNA for Sensitive mutation detection using Sequencing) that allows mutant frequencies &lt; 0.1% to be detected.

Results: One patient did not start treatment and 2 were not evaluable. Palliative chemotherapy (1-2 lines) had been delivered before inclusion to 28% and &gt; 1 line of palliative ET to 58% of the patients. A total of 72% (n=21) of the patients had visceral disease (of whom 7 had liver metastases), and 28% (n=8) patients bone-only disease. Median PFS was 9.1 months (range 2.1-59.3 months). Best responses were: 1 patient (3%) received complete remission; 7 patients (24%) partial response; 16 patients (55%) SD (of whom 12 had CB, defined as SD &gt; 24 weeks), and 5 (17%) had progressive disease. The ORR (defined as CR, PR, or CB) was 69%. The most common toxicity was hypertension (62%), that resulted in termination in 2 patients, and 1 patient stopped treatment due to thrombocytopenia. Other side-effects were proteinuria grade 1-3 (24%); hand-foot-syndrome grade 1-2 (45%); mucositis grade 1 (14%); nausea grade 1 (14%) and diarrhea grade 1-3 (10%). CTC was isolated in 12 patients (37%). Three out of the 5 patients with PD at 12 weeks had detectable CTCs at base-line. Base-line ESR1, PIK3CA and TP53 mutations were found in CTC from 2 patients (17%), 7 patients (58%), and 5 patients (42%), respectively, but did not correlate to response.

Conclusion: The treatment was well tolerated with an ORR of 69%, which is considered very good in this setting. CTCs were only isolated in 37% of the patients which is comparable to previously reported results in metastatic luminal breast cancer and thus not a feasible method for monitoring treatment effect. Results on levels of consecutive ctDNA, as well as mutation pattern in relation treatment effect will be presented.

Citation Format: Linderholm BK, Ekholm M, Wännstig A-K, Lundstedt D, Carlsson L, Tzikas A-K, Svensson J, Kristiansson H, Filges S, Ståhlberg A. Low-dose chemotherapy (CT) + bevacizumab (Bev) combined with unchanged endocrine treatment (ET) in patients with recurrent luminal breast cancer progressing during ET – Effect determined by standard imaging and changes in ctDNA and CTC during treatment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-16-09.

Abstract P4-14-10: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Ekholm M, Bendahl P-O, Fernö M, Nordenskjöld B, Stål O, Rydén L. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-14-10.

Abstract OT3-06-03: ABC-SE, Advanced Breast Cancer – Statins and Endocrine treatment

Full Title: A randomized, open-label, multi-center, phase II study to compare the efficacy and tolerability of atorvastatin 40 mg in addition to endocrine treatment in patients with estrogen receptor (ER) positive advanced breast cancer with focus on mechanisms of resistance.

Background: The majority of metastatic breast cancer patients progress during endocrine therapy and eventually become resistant to treatment. Understanding how metastatic cancer cells adapt to different therapies is key for the development of improved treatment regimens. The effectiveness of endocrine therapy in ER+ tumors may be influenced by cholesterol through the cholesterol metabolite oxysterol 27-hydroxycholesterol, which acts as an ER ligand, harboring the ability to regulate ER-dependent tumor growth. Statin-mediated inhibition of the cholesterol pathway has been demonstrated to induce anti-neoplastic effects in both breast cancer cells and human breast cancer. Hence the goal of this study is to both understand the mechanisms of resistance to endocrine treatment and test the hypothesis that addition of statins will enhance the efficacy of endocrine treatment.

Trial Design: A multi-center randomized, open-labelled, phase II trial in the first and second line metastatic treatment setting, comparing standard endocrine treatment (letrozole) with letrozole +/- atorvastatin (1:1). Upon progression in the first line setting, and as part of the translational studies of mechanisms of resistance to endocrine therapy, the patients receive second line endocrine treatment using fulvestrant.

Eligibility criteria: 1) Patients diagnosed with ER positive/HER2 negative metastatic breast cancer, including locally advanced stage IV disease, requiring systemic endocrine treatment. 2) No Previous treatment for metastatic breast cancer, unless being considered for direct entry to the second part of the study with fulvestrant.

Specific aims: To test the clinical efficacy of adding statins to endocrine treatment in advanced breast cancer. Primary endpoint: Clinical benefit rate, defined as the proportion of all randomly assigned patients who have the best overall response; complete response, partial response, or stable disease for at least 24 weeks following first-line letrozole treatment alone or in combination with atorvastatin. Translational endpoint: To elucidate mechanisms of resistance to endocrine treatment alone or in combination with statins in ER+ metastatic breast cancer.

Statistical Methods:The primary endpoint of clinical benefit rate will be compared in the two groups using a logistic regression model where the odds ratios and associated 95% CIs and p-values will be reported. The secondary endpoint, progression-free-survival, will be analyzed in crude analysis using the Kaplan-Meier and Log-Rank test as well as the Cox regression hazards analysis with the latter allowing for confounder-controlled multivariate analysis.

Present accrual and target accrual: The trial started recruiting as of October 10, 2016. The target accrual is 126 patients, whereof 17 are presently included in the trial.

Contact information for people with a specific interest in the trial:

Signe.Borgquist@med.lu.se

Citation Format: Borgquist S, Ekholm M, Feldt M, Schyman T, Zackrisson S, Bosch A. ABC-SE, Advanced Breast Cancer – Statins and Endocrine treatment [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-06-03.

Timing of dental development in osteogenesis imperfecta patients with and without bisphosphonate treatment

Bisphosphonates have established their role as medical therapy for pediatric osteogenesis imperfecta (OI) patients. Since bisphosphonates have also been shown to delay tooth development in animal models, we aimed to assess whether the medication has a similar effect on children with OI. In this cross-sectional study, bisphosphonate-treated OI patients of whom dental panoramic tomograph was taken between 3 and 16years of age formed the study group. The patients, 22 in total, had been treated with pamidronate, zoledronic acid or risedronate for at least one year before the radiography. Developmental stage of the permanent teeth, resorption of the deciduous teeth, and number of the erupted permanent teeth were radiographically assessed in the left mandibular quadrant. Dental panoramic tomographs of 50 OI patients, naïve to bisphosphonates, and of 50 healthy individuals of the same age were used as controls. The dental development was statistically significantly accelerated in the OI group naïve to bisphosphonates showing median advancement of dental age by 0.63years from chronological age and median increase in the number of erupted teeth by 0.31 as compared to Finnish norms. Bisphosphonate-treated OI patients displayed, however, age-appropriate dental development. The OI patients not treated with bisphosphonates also showed statistically significantly faster resorption of the deciduous teeth than the treated ones, and displayed an altered interrelationship between the resorption stage of an individual primary tooth and the developmental stage of the succedaneous permanent tooth, unlike the OI patients treated with bisphosphonate. No correlation between either cumulative bisphosphonate dose or between treatment length and any measured component of the dental development was found. To conclude, OI itself was found to lead to advanced dental development. Bisphosphonate treatment had a delaying effect in all the three aspects studied, resulting in a rate of dental development indistinguishable from normal.

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.

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.

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.

Radiation exposure to foetus and breasts from dental X-ray examinations: effect of lead shields

OBJECTIVES

Dental radiography may involve situations where the patient is known to be pregnant or the pregnancy is noticed after the X-ray procedure. In such cases, the radiation dose to the foetus, though low, needs to be estimated. Uniform and widely used guidance on dental X-ray procedures during pregnancy are presently lacking, the usefulness of lead shields is unclear and practices vary.

METHODS

Upper estimates of radiation doses to the foetus and breasts of the pregnant patient were estimated with an anthropomorphic female phantom in intraoral, panoramic, cephalometric and CBCT dental modalities with and without lead shields.

RESULTS

The upper estimates of foetal doses varied from 0.009 to 6.9 μGy, and doses at the breast level varied from 0.602 to 75.4 μGy. With lead shields, the foetal doses varied from 0.005 to 2.1 μGy, and breast doses varied from 0.002 to 10.4 μGy.

CONCLUSIONS

The foetal dose levels without lead shielding were <1% of the annual dose limit of 1 mSv for a member of the public. Albeit the relative shielding effect, the exposure-induced increase in the risk of breast cancer death for the pregnant patient (based on the breast dose only) and the exposure-induced increase in the risk of childhood cancer death for the unborn child are minimal, and therefore, need for foetal and breast lead shielding was considered irrelevant. Most important is that pregnancy is never a reason to avoid or to postpone a clinically justified dental radiographic examination.

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.

Quality assurance in digital dental imaging: a systematic review

OBJECTIVES

Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance.

MATERIALS AND METHODS

The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms.

RESULTS

Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance.

CONCLUSIONS

In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice.

Abstract P2-11-15: Immunohistochemical assessment of Ki67 with the antibodies SP6 and MIB1 - A comparison of prognostic information and reproducibility

Background

Proliferation is a key feature in breast cancer and also a clinical important factor for prognosis and treatment prediction. In the St Gallen Consensus of 2011, immunohistochemically analysed Ki67 was adopted as a surrogate marker to distinguish the “luminal A” from the “luminal B” subtype, in order to select patients with estrogen receptor positive disease expected to benefit from adjuvant chemotherapy. The mouse monoclonal antibody MIB1 is the generally accepted antibody for assessment of Ki67. However, other antibodies have been developed, e.g. the rabbit monoclonal antibody SP6. The assessment of Ki67 with MIB1 is unfortunately associated with a considerable lack of reproducibility. Rabbit monoclonal antibodies generally tend to have higher specificity without loss of sensitivity, compared to corresponding mouse monoclonal antibodies. SP6 has also been found to have reduced background staining compared to MIB1. According to these advantages, SP6 may be an alternative to MIB1 for routine staining of Ki67. Any methodological modification should, according to international recommendations, be compared against a clinically validated assay and demonstrate acceptable concordance before being introduced in clinical routine. The analysis of Ki67 with SP6 therefore needs to be evaluated and compared to MIB1 in a cohort of breast cancer patients with clinical follow-up.

Aims

To compare the antibodies SP6 and MIB1 for immunohistochemical assessment of Ki67 in primary breast cancer regarding prognostic strength and reproducibility of the evaluation.

Methods

Tissue microarray from a cohort of 237 premenopausal women with node-negative breast cancer was used for assessment of Ki67, with both SP6 and MIB1, by three different investigators. The 7th decile was applied for defining cut-off. Distant disease-free survival (DDFS) was used as endpoint and the follow-up was restricted to 5 years.

Results

Ninety per cent of the samples were classified into the same group, either high or low Ki67, irrespective of antibody used. Ki67 (high vs. low), analysed with both antibodies was associated to DDFS (34 events) in the univariable analyses (SP6: HR 2.6, 95% CI 1.3-5.2, p = 0.01 and MIB1: HR 2.8, 95% CI 1.4-5.7 p = 0.004) and showed borderline significance for DDFS in the multivariable analyses, also including HER2, age, and tumour size (SP6: HR 2.0, 95% CI 0.93-4.5, p = 0.074 and MIB1: HR 2.2, 95% CI 0.97-4.8, p = 0.058). The agreement between different assessors was somewhat higher for MIB1 than for SP6 (kappa-values 0.83-0.88 vs. 0.72-0.77).

Conclusions

SP6 was not superior to MIB1 and the two antibodies were comparable in the assessment of Ki67 for prognostic considerations in primary breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-11-15.

Hyperfine splitting and room-temperature ferromagnetism of Ni at multimegabar pressure

Magnetic and elastic properties of Ni metal have been studied up to 260 GPa by nuclear forward scattering of synchrotron radiation with the 67.4 keV Mössbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the ferromagnetic state of Ni up to 260 GPa, the highest pressure where magnetism in any material has been observed so far. Ab initio calculations reveal that the pressure evolution of the hyperfine field, which features a maximum in the range of 100 to 225 GPa, is a relativistic effect. The Debye energy obtained from the Lamb-Mössbauer factor increases from 33 meV at ambient pressure to 60 meV at 100 GPa. The change of this energy over volume compression is well described by a Grüneisen parameter of 2.09.

Elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys studied by the combinatorial thin film approach and ab initio calculations

The elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys with additions of up to 8 at.% X were studied by combinatorial thin film growth and characterization and by ab initio calculations using the disordered local moments (DLM) approach. The lattice parameter and Young's modulus values change only marginally with X. The calculations and experiments are in good agreement. We demonstrate that the elastic properties of transition metal alloyed Fe-Mn can be predicted by the DLM model.

Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

We discover that hcp phases of Fe and Fe(0.9)Ni(0.1) undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio, and Mössbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.

Effect of varying displays and room illuminance on caries diagnostic accuracy in digital dental radiographs

In clinical practice, digital radiographs taken for caries diagnostics are viewed on varying types of displays and usually in relatively high ambient lighting (room illuminance) conditions. Our purpose was to assess the effect of room illuminance and varying display types on caries diagnostic accuracy in digital dental radiographs. Previous studies have shown that the diagnostic accuracy of caries detection is significantly better in reduced lighting conditions. Our hypothesis was that higher display luminance could compensate for this in higher ambient lighting conditions. Extracted human teeth with approximal surfaces clinically ranging from sound to demineralized were radiographed and evaluated by 3 observers who detected carious lesions on 3 different types of displays in 3 different room illuminance settings ranging from low illumination, i.e. what is recommended for diagnostic viewing, to higher illumination levels corresponding to those found in an average dental office. Sectioning and microscopy of the teeth validated the presence or absence of a carious lesion. Sensitivity, specificity and accuracy were calculated for each modality and observer. Differences were estimated by analyzing the binary data assuming the added effects of observer and modality in a generalized linear model. The observers obtained higher sensitivities in lower illuminance settings than in higher illuminance settings. However, this was related to a reduction in specificity, which meant that there was no significant difference in overall accuracy. Contrary to our hypothesis, there were no significant differences between the accuracy of different display types. Therefore, different displays and room illuminance levels did not affect the overall accuracy of radiographic caries detection.

Prevalence and natural course of craniocervical junction anomalies during growth in patients with osteogenesis imperfecta

Pathology in the craniocervical junction is a serious complication of osteogenesis imperfecta (OI). Our aim was to analyze the prevalence and natural course of craniocervical junction anomalies in patients with OI during growth. In a one-center retrospective study, we analyzed lateral skull radiographs and midsagittal magnetic resonance images of 76 patients with either type I, III, or IV OI. The material included longitudinal series of 31 patients. In total, 150 patient images taken at ages 0 to 39 years were analyzed and compared with age-matched control data. Craniocervical anomalies were observed in 37% of patients and in all OI types studied. Of the three types of anomalies, basilar invagination was seen in 13%, basilar impression in 15%, and platybasia in 29% of the patients. From those with an abnormal finding, 44% displayed more than one type of anomaly. At a group level, we found no evidence of progression of craniocervical junction pathology with age. We provide longitudinal and cross-sectional data on craniocervical junction dimensions in growing patients with OI and, based on those, suggest a radiological management strategy for diagnosis of cranial base pathology. A higher risk of having any of the pathological conditions was associated with a lower height Z-score. Careful follow-up of cranial base anomalies particularly in subjects with OI and severe growth failure is warranted.

The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys

We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Néel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

Influence of the magnetic state on the chemical order-disorder transition temperature in Fe-Ni permalloy

In magnetic alloys, the effect of finite temperature magnetic excitations on phase stability below the Curie temperature is poorly investigated, although many systems undergo phase transitions in this temperature range. We consider random Ni-rich Fe-Ni alloys, which undergo chemical order-disorder transition approximately 100 K below their Curie temperature, to demonstrate from ab initio calculations that deviations of the global magnetic state from ideal ferromagnetic order due to temperature induced magnetization reduction have a crucial effect on the chemical transition temperature. We propose a scheme where the magnetic state is described by partially disordered local magnetic moments, which in combination with Heisenberg Monte Carlo simulations of the magnetization allows us to reproduce the transition temperature in good agreement with experimental data.

Ab initio lattice stability of fcc and hcp Fe-Mn random alloys

We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe-Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its Néel temperature) as well as their complete disorder, corresponding to paramagnetic fcc and hcp alloys. For both cases, the results are consistent with our thermodynamic calculations, obtained within the Calphad approach. For the room temperature magnetic configuration, the cross-over of the total energies of the hcp phase and the fcc phase of Fe-Mn alloys is at the expected Mn content, whereas for the magnetic configuration above the fcc Néel temperature, the hcp lattice is more stable within the whole composition range studied. The increase of the total energy difference between hcp and antiferromagnetic fcc due to additions of Mn as well as the stabilizing effect of antiferromagnetic ordering on the fcc phase are well displayed. These results are of relevance for understanding the deformation mechanisms of these random alloys.

A histological and immunohistochemical study of tissue reactions to solid poly(ortho ester) in rabbits

In many cases only the temporary presence of a biomaterial is needed in tissue support, augmentation or replacement. In such cases biodegradable materials are better alternatives than biostable ones. At present, biodegradable polymers are widely used in the field of maxillofacial surgery as sutures, fracture fixation devices and as absorbable membranes. The most often used polymers are aliphatic polyesters, such as polyglycolic acid (PGA) and polylactic acid (PLA). Poly(ortho ester) is a surface eroding polymer, which has been under development since 1970, but is used mostly in drug delivery systems in semisolid form. The aim of this study was to evaluate the tissue reactions of solid poly(ortho ester) (POE), histologically and immunohistochemically. Resorption times and the effect of 2 different sterilization methods (gamma radiation and ethylene oxide) upon resorption were also evaluated. Material was implanted into the tibia and subcutaneously into the mandibular ramus area of 24 rabbits. Follow-up times were 1-10, 14 and 24 weeks. Histological studies showed that POE induces a moderate inflammation in soft tissue and in bone. At 24 week follow-up, inflammation was mild in soft tissue and moderate in bone. In immunohistochemical studies, no highly fluorescent layer of tenascin or fibronectin was found adjacent to the implant. Resorption of gamma-sterilized rods was faster than ethylene oxide-sterilized rods. The total resorption time was more than 24 weeks in both groups. Clinically the healing was uneventful and the implants the well tolerated by the living tissue. This encourages these authors to continue studies with this interesting new material to search for the ideal material for bone filling and fracture fixation.

The copolymer of epsilon-caprolactone-lactide and tricalcium phosphate does not enhance bone growth in mandibular defect of sheep

In the field of craniomaxillofacial and orthopaedic surgery there is a constant need for bone or bone substitute. At the present, the most effective way to enhance bone healing clinically is to use autogenous bone grafts. The problems associated with the use of these autografts are donor site morbidity, limited supply and need for a second operative site. Currently there are several different synthetic products commercially available in the market; nevertheless, none of them is ideal for filling bone defects. Therefore, search for new synthetic materials for bone replacement is necessary. A mixture of tricalcium phosphate (TCP) and epsilon-caprolactone-lactide copolymer P(epsilon -CL/DL-LA) was prepared and implanted in critical size mandibular bone defects in twelve sheep. Contralateral side was used as a control. Follow-up times for histological and radiological studies were 9, 14, 24 and 52 weeks. We found that the implanted material did not enhance bone formation compared to control site. We also confirmed that defect size was of critical size, since there was no complete healing of the control site either. The results do not encourage us to continue our studies with the mixture of TCP and P(epsilon-CL/DL-LA) as a filling material for bone defects. Therefore the search for the ideal material is still ongoing.

Tissue reactions of subcutaneously implanted mixture of epsilon-caprolactone-lactide copolymer and tricalcium phosphate. An electron microscopic evaluation in sheep

Biodegradable polymers, mainly derivates of alpha-hydroxy acids, are widely used today in oral- and maxillofacial surgery, orthopedics, and other fields of surgery. These biomaterials are well tolerated by living tissue and fracture fixation devices made of polylactic or polyglycolic acid are clinically widely used today. Still, there are some problems in application of biodegradable polymers. Abacterial inflammatory reactions have been noticed after the clinical introduction of these devices. Both swelling and pain at the site of implantation have also been reported. The etiology of this inflammatory reaction is still unknown, despite the numerous studies. Therefore, the aim of the present study was to further characterize this inflammatory reaction in detail, by electronmicroscopy. We prepared a mixture of epsilon-caprolactone-lactide copolymer and tricalcium phosphate and placed it in the dermis in 12 sheep. Follow-up times were 9, 14, 24, and 52 weeks. We found that the mixture caused a mild inflammatory reaction. There were no signs of cell damage. Fibroblasts, macrophages, and eosinophils were found adjacent to the copolymer. The mixture is easy to handle and can be moulded into different shapes in room temperature. The results encourage us to continue our studies to develop a filling material for bone defects.

Histological study of tissue reactions to epsilon-caprolactone-lactide copolymer in paste form

In previous studies, epsilon-caprolactone-lactide copolymer in solid form has been used in experimental animals as suture material, and as a biodegradable nerve guide. The aim of the study reported here was to assess tissue reactions to epsilon-caprolactone-lactide copolymer in paste form, histologically, and to compare bone healing at the sites of implantation versus that at control sites. The other purpose of the study was to evaluate the properties of the implanted material as a filling material for bone defects. Resorption time and intensity of inflammatory reaction were also evaluated. Material was implanted into the abdominal walls and femurs of 34 rats. Follow-up times were from 2 weeks to 1 year. The results showed that epsilon-caprolactone-lactide copolymer in paste form induces a severe inflammatory reaction when placed in muscle, and moderate inflammation when implanted into bone. The resorption time was more than 1 year. Bone healing at sites of implantation was slower than at control sites.

Mixture of epsilon-caprolactone-lactide copolymer and tricalcium phosphate: a histological and immunohistochemical study of tissue reactions

In cranio-maxillofacial surgery, bone transplantation is needed for treatment of bony defects. An autograft, allograft or biomaterial can be used. Autogenous bone grafts are considered to be the best materials available, but there are some disadvantages in their use including donorsite morbidity, need for a second operative site and limited graft supply. A search for new bone-graft materials therefore remains necessary. We prepared a mixture of tricalcium phosphate (TCP), which is a resorbable, non-toxic, osteoconductive ceramic material and epsilon-caprolactone-lactide copolymer P(epsilon-CL/DL-LA), a resorbable polymer, and placed it in the dermis and in mandibular bone defects in 13 rabbits. Follow-up times were two, three, seven, eight, 12, 15 and 18 weeks, tissue reactions were assessed, histologically and immunohistochemically. Times of resorption of the material from tissues were reported. We found that the mixture caused a mild inflammatory reaction when placed in bone and severe inflammation when placed in dermis. No highly fluorescent layer of tenascin or fibronectin was found surrounding the implant area. The mixture was excellent to handle and very easy to place into bone defects. The results are promising and have led us to continue development of the mixture.

Biocompatibility of solid poly (ortho ester)

In previous studies poly (ortho ester) (POE) has shown promise as a resorbable device, a hemostatic sealant and as a carrier for drugs in bone surgery. The aim of this study was to evaluate the tissue reactions of solid poly (ortho ester) implanted into both tibiae of 17 rabbits. One half of the rods were sterilized by gamma radiation and the other half by ethylene oxide. The follow-up times were from 1 week to 21 weeks, after which the animals were killed and the bony specimens examined histologically. The connective tissue samples were examined immunohistochemically in order to study the occurrences of two extracellular matrix glycoproteins, tenascin and fibronectin. The results showed that solid poly (ortho ester)s induce a moderate inflammatory reaction for 9 weeks. Tenascin and fibronectin were present in samples from 1 week up to 4 weeks. It was also found that gamma sterilized POE was resorbed at week 7 and ethylene oxide sterilized POE at week 13.