Publications by authors named "Michael M Bornstein"

245 Publications

Ausgedehnte polyostotische Form einer fibrösen Dysplasie mit Befall der rechten Maxilla und Mandibula.

Swiss Dent J 2021 Feb;131(2):160-161

Oral and Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

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February 2021

Early Loading of Posterior Nonsubmerged Titanium Implants with a Modified Sandblasted and Acid-Etched Surface: A Prospective Case Series with Up to 149 Months of Follow-up.

Int J Periodontics Restorative Dent 2021 Jan-Feb;41(1):51-59

The purpose of this prospective study was to evaluate the success rates and prosthetic complications of implants with a modified sandblasted and acid-etched (SLA) surface inserted for posterior single-implant crown restorations. Final crowns were placed 3 to 4 weeks after surgery, and patient follow-up spanned 10 years in a private practice setting. A total of 22 patients (8 women, 14 men) with 25 posterior implants placed (16 mandible, 9 maxilla) were selected, including only implants for posterior single-implant crowns with insertion torque values of ≥ 35 Ncm at placement. Twenty-one implants passed the reverse torque test at 3 to 4 weeks after implant placement, and final restorations were placed. Three patients (4 implants) had "spinners," and there was one patient dropout after completion of the final restoration. All patients were recalled for clinical exams, digital periapical radiographs, and clinical photos at short-term (≤ 5 years) and long-term (> 5 years) follow-up appointments. The Community Periodontal Index of Treatment Needs was also determined at the initial and follow-up visits. Crestal bone level was measured at crown placement (T1), short-term follow-up (T2; mean: 29.4 months), and long-term follow-up appointments (T3; mean: 114.4 months). Twenty patients (23 implants) returned for examination at T2, and 15 (18 implants) were available at T3. For the 17 implants available at all evaluations, statistically significant bone loss was found from T1 to T2 (0.23 ± 0.30 mm), and the mean crestal bone level appeared stable from T2 to T3. Based on clinical and radiographic findings, the success rate for the implants and restorations at T2 and T3 was graded as 100%. Therefore, it can be stated that an early loading protocol of 3 to 4 weeks using a modified SLA surface at premolar/molar single-tooth locations can result in favorable clinical and radiographic long-term results.
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http://dx.doi.org/10.11607/prd.4703DOI Listing
February 2021

Attitudes of dental students towards treating elderly patients. Dental students’ attitudes on geriatric patients

Swiss Dent J 2021 01 21;131(2). Epub 2021 Jan 21.

Clinic of General, Special Care and Geriatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.

The purpose of this questionnaire-based survey was to evaluate the attitudes of the undergraduate dental students towards elders. The 14-item Geriatric attitudes scale (GAS) questionnaire, along with a 9-item questionnaire with specific questions on the current geriatric dental curriculum, confidence, and preference in treating the elderly patients were administered to the undergraduate dental students (3rd bachelor, 1st master, and 2nd master) in the four Swiss university dental schools. Mean GAS scores were calculated and inter- and intra-group differences were analyzed with ANOVA and post hoc tests (level of significance set at α=0.05). Responses to the 9-item questionnaire were reported descriptively. Further analyses were performed to evaluate the effect of demographic factors on the GAS scores. 305 students (meanage: 25.8±4.0y) participated in this study. The mean overall GAS score of the students was 3.5±0.4. There were no significant differences in the GAS scores between the centers [F(3, 300)=2.266, p=0.081] or between the year of training [F(2, 301)=1.884, p=0.154]. Demographic factors did not influence the GAS scores. Students considered geriatric dentistry as an important part of their dental undergraduate education. The current geriatric curriculum was perceived to be on an adequate level. Hands-on experience in treating geriatric patients in the undergraduate curriculum was positively opinionated, and mobile dental services for elders with limited access to care was considered a good solution. In conclusion, the attitudes of the Swiss undergraduate dental students towards an elderly patient seem acceptable but could still be improved.
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January 2021

The bifid mandibular canal in three-dimensional radiography: morphologic and quantitative characteristics.

Swiss Dent J 2021 01 16;131(1):10-28. Epub 2020 Dec 16.

Department of Oral Health & Medicine, University Center for Dental Medicine Basel UZB, University of Basel, Basel, Switzerland.

The mandibular canal is a prominent anatomical structure and it is of great clinical importance since it contains the inferior alveolar nerve. The clinician is advised to proceed cautiously in the vicinity of the mandibular canal to avoid any damage to its neurovascular content. Based on observations in dry mandibles, in panoramic radiographs, and recently in three-dimensional radiography, various anatomical variations of the mandibular canals have been described. One such variant is the so-called bifid mandibular canal (BMC). Embryologically, multiple canals develop and subsequently fuse to form a single mandibular canal; however, occasionally fusion fails or is incomplete resulting in one or multiple BMCs. Clinically relevant issues with regard to the BMCs include hemorrhagic or neurological disorders following damage to these aberrant canals. This literature review presents morphological and quantitative data about BMCs from studies using three-dimensional radiography, i.e. CT and/or CBCT. The reported frequencies of BMCs per patient ranged from 9.8 - 66.5% and per mandibular side from 7.7 - 46.5%. Gender, age or side predilection is currently inconclusive with regard to the occurrence of BMCs. Various types of BMCs have been described in the literature, such as retromolar, dental, forward, or buccolingual canals. BMCs may originate from the mandibular canal along its entire course, but bifurcation appears to be more frequent in the posterior compared to the anterior canal portions. Mean BMC length was reported to range from 10.2 - 16.9 mm, and mean BMC diameter from 0.9 - 2.3 mm. In conclusion, the presence of a BMC must be taken into consideration for treatment planning and anesthetic, endodontic, or surgical interventions in the mandible.
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January 2021

2021 - 50 years of and hopefully the beginning of the end of the COVID-19 crisis.

Dentomaxillofac Radiol 2021 Jan;50(1):20219001

Department of Oral Health & Medicine, University Center of Dental Medicine Basel UZB, Basel, Switzerland.

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http://dx.doi.org/10.1259/dmfr.20219001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7780833PMC
January 2021

Anteroposterior length of the maxillary complex and its relationship with the anterior cranial base.

Angle Orthod 2021 01;91(1):88-97

Objectives: To use both absolute anteroposterior maxillary complex length (APMCL) and relative APMCL to investigate the relationship between the maxillary complex, its individual bony segments, and their association to the anterior cranial base. In addition, the relationship between length and position of the maxillary complex was analyzed.

Materials And Methods: Sixty human skulls were analyzed using cone beam computed tomography. The maxillary complex length was measured between anterior and posterior nasal spine (ans-pns), and the average was used as the cut-off to identify a high- and a low-length group based on absolute APMCL. The length ratio between the maxillary complex and the anterior cranial base (ans-pns/SN) was used to identify the two groups based on relative APMCL. The anterior cranial base length and the lengths of the maxillary complex bones were compared between the high- and low-length groups.

Results: Based on absolute APMCL, individuals with shorter maxillary complex had shorter anterior cranial base (P = .003), representing normal proportions. Based on relative APMCL, individuals with shorter maxillary complex had longer anterior cranial base and vice versa (P = .014), indicating disproportions. Individuals with shorter maxillary complex exhibited shorter maxilla (Δ = -1.5 mm, P = .014).

Conclusions: When skeletal deformity of the midface is suspected, individual disproportions in the anteroposterior length of the maxillary complex in relation to the anterior cranial base (relative measurements) should be assessed through radiological imaging. A shorter maxillary complex may be associated with a shorter maxilla, and not with a shorter premaxilla or palatine bone.
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http://dx.doi.org/10.2319/020520-82.1DOI Listing
January 2021

Outcome of first-time surgical closures of oroantral communications due to tooth extractions. A retrospective analysis of 162 cases.

Swiss Dent J 2020 Dec;130(12):972-982

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

The objective of this study was to analyze the outcome of first-time surgical closures of oroantral communications (OAC) after tooth extractions. Using a billing software, all patients treated in a surgery department were filtered for interventions of the maxillary sinus indicative of OAC therapy. Out of 221 initially eligible cases, the charts of 162 cases fulfilling the inclusion criteria were retrospectively evaluated for the outcome in terms of symptom-free OAC closure as well as possibly influencing patient and treatment factors. The analyzed cohort included 98 males (60.5%) and 64 females (39.5%) with a mean age of 48.6 years (range 17 to 86 years). The maxillary 1st molar (38.3%) was the most common site requiring OAC closure. In 60.5% of the cases, surgical OAC closure was performed immediately after tooth extraction. The Rehrmann flap (72.2%) was the most frequently used technique for surgical OAC closure. 94.4% of surgical OAC closures were successful. Gender and age did not influence the outcome. In contrast, the site of OAC and the time interval from tooth extraction to OAC closure affected the results. Furthermore, the Rehrmann flap, alone or in combination with biomaterials, was superior to the mere suturing (with or without biomaterials) of the OAC site. In conclusion, the Rehrmann flap alone or in combination with biomaterials provided high success rates for first-time surgical OAC closure. With regard to the study parameters, an OAC in the 3rd molar area and an extended interval from tooth extraction to OAC closure negatively influenced the resolution of OAC. However, results must be interpreted cautiously considering the retrospective study design and the limited number of cases.
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December 2020

A retrospective analysis of autotransplanted teeth including an evaluation of a novel surgical technique.

Clin Oral Investig 2020 Dec 2. Epub 2020 Dec 2.

Department of Oral Surgery & Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.

Objectives: To assess survival rates and frequency of complications for immature and mature autotransplanted teeth after at least 1 year in function.

Materials And Methods: All consecutive patients who had undergone tooth autotransplantation between 2000 and 2018 were invited to a clinical and radiographic follow-up examination. First, survival rates were calculated on the basis of a phone inquiry. A clinical follow-up examination allowed for the calculation of the success rate, i.e., absence of any potentially adverse clinical and radiographic findings of the autotransplanted teeth. Moreover, the effect of demographic, dental, and surgical variables on survival/success was analyzed statistically.

Results: Thirty-eight teeth in 35 patients were transplanted during the study period. Three teeth in 3 patients were excluded due to missing records. All other patients were successfully contacted and interviewed by phone. Out of these 35 transplants, 32 were still in function, and 3 had been extracted, yielding a 91.4% survival probability after a median follow-up of 3.4 years. Of the 32 teeth qualifying for the success analysis, 20 (62.5%) showed absence of potentially adverse findings, while 3 (9.4%) required root canal treatment (RCT). Out of the 9 mature, root-end resected transplants, 4 exhibited ongoing pulp canal obliteration, all with a single root canal. Postoperative and potentially adverse findings or failures were found more frequently in the group of mature transplants (55.6%) than immature transplants (30.4%) and for molars (72.7%) than premolars (17.6%) or canines (25%). None of the potential predictors had a statistically significant effect on survival or success.

Conclusion: Autotransplanted teeth yielded a satisfying midterm survival rate regardless of their stage of development. An additional, extraoral root-end resection of mature transplants may lead to rates of revascularization and postoperative pulp canal obliteration higher than the data reported on unmodified mature transplants.

Clinical Relevance: Extraoral root-end resection of mature teeth shows promising outcomes for transplants especially with a single root canal and uncomplicated root morphology.
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http://dx.doi.org/10.1007/s00784-020-03673-yDOI Listing
December 2020

Occurrence of Vertical Root Fractures after Apical Surgery: A Retrospective Analysis.

J Endod 2021 Feb 22;47(2):239-246. Epub 2020 Oct 22.

Department of Oral Health and Medicine, University Center for Dental Medicine Basel UZB, University of Basel, Basel, Switzerland.

Introduction: Vertical root fractures (VRFs) are among the most frequent causes of tooth loss, mainly of endodontically treated teeth. However, very few data is available about the occurrence of VRFs following apical surgery.

Methods: Patient charts from 864 patients with 1058 teeth treated with apical surgery (September 1999 to December 2018) were retrospectively evaluated, if a VRF had occurred after surgery. The following, possibly influencing factors were analyzed: sex and age, type of treated tooth, primary versus resurgery, technique of root-end preparation, and timepoint of VRF diagnosis. Endpoints were either tooth extraction or the last follow-up.

Results: The study cohort (55% women, 45% men) had a mean age of 52.00 ± 13.97 years (range 9-93 years). The overall rate of VRFs after apical surgery was 4% (42 of 1058 teeth). Among these 42 teeth, 33.3% were mandibular first molars and 26.2% were maxillary second premolars. The most frequently affected root was the mesial root of mandibular first molars (28.6%). With regard to the study parameters, significant differences of VRF rates were observed only for the type of tooth treated.

Conclusions: A low VRF rate of 4% was observed in this study. VRFs commonly occurred in maxillary premolars and mandibular molars, with the mesial root of mandibular first molars affected most frequently. This is in line with previous reports about VRFs in endodontically treated teeth without additional apical surgery.
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http://dx.doi.org/10.1016/j.joen.2020.10.012DOI Listing
February 2021

Ausgedehnte odontogene Keratozyste im posterioren Unterkiefer links. Differenzialdiagnose osteolytischer Prozesse.

Swiss Dent J 2020 10;130(10):802-803

Oral and Maxillofacial Surgery, Faculty of Dentistry, The Uni-versity of Hong Kong, Hong Kong SAR, China.

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October 2020

Extraoral anatomy in CBCT – a literature review. Part 4: Pharyngocervical region

Swiss Dent J 2020 10;130(10):768-784

Oral and Maxillofacial Radiol-ogy, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The Uni-versity of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China

This review about extraoral anatomy depicted in cone beam computed tomography describes the pharyngocervical region. Large (≥ 8 × 8 cm) field of views of the maxilla and/or mandible will inevita-bly depict the pharyngocervical region that com-prises the posterior upper airway, the pharyngeal part of the digestive tract, as well as the cervical segment of the spine. The latter consists of seven cervical vertebrae (C1-C7) with corresponding distinctive features, i.e., the atlas (C1) and the axis (C2). In addition, cervical vertebrae serve as ref-erences for the vertical position of anatomical structures. For instance, C4 is a typical landmark since it generally denotes the level of the chin, of the body of the hyoid bone, of the base of the epiglottis, and of the bifurcation of the common carotid artery, respectively. The pharynx, which is functionally involved in respiration, deglutition, and vocalization, extends from the lower aspect of the skull base to the esophagus. Anatomically, the pharynx is divided into three segments, i.e. the nasopharynx, the oropharynx, and the laryn-gopharynx. All communicate anteriorly with cor-responding cavities, i.e. the nasal cavities, the oral cavity, and the larynx. Although not directly located within the pharyngocervical region, the hyoid bone and the styloid process are also dis-cussed in this review, since both structures are commonly visible on CBCT images of this region.
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October 2020

Mandibular Radiomorphometric Indices and Tooth Loss as Predictors for the Risk of Osteoporosis using Panoramic Radiographs.

Oral Health Prev Dent 2020 Sep 4;18(1):773-782. Epub 2020 Sep 4.

Purpose: To assess the mandibular cortical width (MCW) and morphology of the mandibular inferior cortex (MIC) on panoramic views from a large sample of males and females in various age groups by using an automated morphometric grading system for assisting osteoporosis screening. Furthermore, possible predictors and concrete cut-off values to identify the risk for osteoporosis were evaluated.

Materials And Methods: MCW, MIC, tooth loss (TL), and alveolar bone loss (ABL) were retrospectively evaluated in 700 panoramic images from dental patients in Hong Kong using commercially available software. To estimate possible predictors for identifying the risk of osteoporosis, age, TL, and ABL were evaluated with the receiver operating characteristic (ROC) curves for each gender separately.

Results: The age groups 60s (sixties), 70s and 80s showed statistically significant gender differences. For example, a smaller MCW and more MIC Class 3 were found in females. Furthermore, females exhibited a statistically significant increase in TL in the age groups 50 years and above. In males, age, TL or ABL did not correlate with MCW, whereas in females it statistically significantly did. Meanwhile, the correlation between ABL and MCW and MIC was weak for both genders. Concrete cut-off values to identify patients at risk of osteoporosis were 60.15 years and 3.5 missing teeth in females, and 72.55 years in males.

Conclusion: Age and tooth loss were related to MCW and MIC in the population investigated. An age of ≥60 as well as more than 3.5 teeth lost seem to be indicators for a risk of osteoporosis in Chinese females based on panoramic views using artificial-intelligence-based software.
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http://dx.doi.org/10.3290/j.ohpd.a45081DOI Listing
September 2020

A Systematic Review of WTA-WTP Disparity for Dental Interventions and Implications for Cost-Effectiveness Analysis.

Healthcare (Basel) 2020 Aug 26;8(3). Epub 2020 Aug 26.

Department of Oral Health and Medicine, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

Cost-effectiveness analysis is widely adopted as an analytical framework to evaluate whether health care interventions represent value for money, and its use in dentistry is increasing. Traditionally, in cost-effectiveness analysis, one assumes that the decision maker's maximum willingness to pay (WTP) for health gain is equivalent to his minimum willingness to accept (WTA) monetary compensation for health loss. It has been documented in the literature that losses are weighted higher than equivalent gains, i.e., that WTA exceeds WTP for the same health condition, resulting in a WTA/WTP ratio greater than 1. There is a knowledge gap of published WTA/WTP ratios for dental interventions in the literature. We therefore conducted a (i) systematic review of published WTA-WTP estimates in dentistry (MEDLINE, Web of Science, Cochrane Library, London, UK) and (ii) a patient-level analysis of WTA/WTP ratios of included studies, and (iii) we demonstrate the impact of a WTA-WTP disparity on cost-effectiveness analysis. Out of 55 eligible studies, two studies were included in our review. The WTA/WTP ratio ranged from 2.58 for discontinuing water fluoridation to 5.12 for mandibular implant overdentures, indicating a higher disparity for implant rehabilitations than for dental public health interventions. A WTA-WTP disparity inflates the cost-effectiveness of dental interventions when there is a substantial risk of both lower costs and health outcomes. We therefore recommend that in these cases the results of cost-effectiveness analyses are reported using different WTA/WTP ratios in a sensitivity analysis.
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http://dx.doi.org/10.3390/healthcare8030301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7550993PMC
August 2020

Do different cone beam computed tomography exposure protocols influence subjective image quality prior to and after root canal treatment?

Clin Oral Investig 2020 Aug 25. Epub 2020 Aug 25.

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

Objectives: The current study aimed to evaluate different CBCT exposure protocols and influencing factors affecting the subjective image quality of scans taken for endodontic indications.

Materials And Methods: Twelve extracted teeth, comprising of two sets of maxillary molars, premolars, canines and incisors, mandibular premolars, and molars, were endodontically treated, and either received a fiber or metal post. The teeth were scanned by CBCT imaging before and after root canal treatment, and after post insertion. Each scan was performed thrice, using an ultra low dose (ULD), standard (SM), and high-resolution mode (HR), respectively. Twelve observers-4 endodontists, 4 periodontists, and 4 radiologists-assessed the subjective image quality using visual analogue scales (VAS). Potential influencing factors were evaluated including acquisition mode, observer specialty, stage of treatment, type of post, and type of tooth, using one-way ANOVA and T test.

Results: Teeth scanned with the ULD had the highest average VAS score (72.5), followed by HR (70.2), and SM (69.0) for values pooled from all teeth and observers. CBCT acquisition mode was not a significant influencing factor on the VAS scores. Observer specialty, stage of treatment, type of post, and type of tooth were significant influencing factors.

Conclusions: Based on the present in vitro data, a low-dose CBCT mode seems not to negatively affect the perception of image quality.

Clinical Relevance: The findings from this in vitro study demonstrate that a low-dose CBCT mode might have potential for diagnostics prior to or following endodontic treatment.
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http://dx.doi.org/10.1007/s00784-020-03524-wDOI Listing
August 2020

Perforation of the maxillary sinus floor during apical surgery of maxillary molars: A retrospective analysis using cone beam computed tomography.

Aust Endod J 2020 Aug 7;46(2):176-183. Epub 2020 Jul 7.

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China.

This retrospective analysis assessed a possible correlation of perforation of the maxillary sinus floor during apical surgery of maxillary molars and the distances from the treated apices/periapical radiolucencies to the sinus floor. The material included 168 apical surgeries of maxillary first or second molars performed from 1999 to 2016. In 22 (out of 33) perforation cases, a preoperative cone beam computed tomography (CBCT) was available. These cases were defined as the test group. From the pool of operated cases without sinus floor perforation, matching cases - that is, same treated tooth, similar age and same gender - were selected as a control group (N = 26). Mean linear distances from root apices or radiolucencies to sinus floor were significantly shorter in the test group compared to the control group. In conclusion, perforation cases were significantly closer to the sinus floor than cases without perforation.
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http://dx.doi.org/10.1111/aej.12413DOI Listing
August 2020

Real-time evaluation of swallowing in patients with oral cancers by using cine-magnetic resonance imaging based on T2-weighted sequences.

Oral Surg Oral Med Oral Pathol Oral Radiol 2020 Nov 26;130(5):583-592. Epub 2020 May 26.

Division of Oral and Maxillofacial Radiology, Kyushu Dental University, Kitakyushu, Fukuoka, Japan. Electronic address:

Objective: The aim of this study was to evaluate whether a new cine-magnetic resonance imaging (CMRI) technique might be useful for evaluating swallowing function in patients with different types of oral cancers by assessing 12 CMRI-related parameters.

Study Design: In total, 111 patients with oral cancers were evaluated. We examined whether visualization of fluid flow and determination of flow direction to the trachea or the esophagus were possible with CMRI. We evaluated the correlations between CMRI-related parameters and self-reported dysphagia scores as the status of dysphagia, T classification groups as tumor staging for preoperative patients, alterations in CMRI-related parameters between pre- and postoperative patients, and the degree of invasiveness of oral cancer surgery.

Results: We could judge the flow direction to the esophagus on CMRI in all 111 patients. Six CMRI-related parameters showed significant correlations with dysphagia status. Increases in CMRI-related parameters were significantly related to deterioration of swallowing status, as shown by a decrease in self-reported dysphagia scores, advances in the T classification, and degree of invasiveness of oral cancer surgery.

Conclusions: The results of the present study suggest that CMRI can be used to directly visualize swallowing dynamics and objectively evaluate the swallowing complaints of patients with oral cancer.
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http://dx.doi.org/10.1016/j.oooo.2020.05.009DOI Listing
November 2020

Current Applications, Opportunities, and Limitations of AI for 3D Imaging in Dental Research and Practice.

Int J Environ Res Public Health 2020 06 19;17(12). Epub 2020 Jun 19.

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong 999077, China.

The increasing use of three-dimensional (3D) imaging techniques in dental medicine has boosted the development and use of artificial intelligence (AI) systems for various clinical problems. Cone beam computed tomography (CBCT) and intraoral/facial scans are potential sources of image data to develop 3D image-based AI systems for automated diagnosis, treatment planning, and prediction of treatment outcome. This review focuses on current developments and performance of AI for 3D imaging in dentomaxillofacial radiology (DMFR) as well as intraoral and facial scanning. In DMFR, machine learning-based algorithms proposed in the literature focus on three main applications, including automated diagnosis of dental and maxillofacial diseases, localization of anatomical landmarks for orthodontic and orthognathic treatment planning, and general improvement of image quality. Automatic recognition of teeth and diagnosis of facial deformations using AI systems based on intraoral and facial scanning will very likely be a field of increased interest in the future. The review is aimed at providing dental practitioners and interested colleagues in healthcare with a comprehensive understanding of the current trend of AI developments in the field of 3D imaging in dental medicine.
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http://dx.doi.org/10.3390/ijerph17124424DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7345758PMC
June 2020

Image retake rates of cone beam computed tomography in a dental institution.

Clin Oral Investig 2020 Dec 2;24(12):4501-4510. Epub 2020 Jun 2.

Oral and Maxillofacial Radiology, Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

Objectives: To investigate the frequency and reasons for retaking cone beam computed tomography (CBCT) scans in an oral and maxillofacial radiology imaging clinic in a dental institution.

Materials And Methods: A retrospective cohort chart audit of the patient image database was performed for 1737 patients attending the Diagnostic Imaging clinic at the Prince Philip Dental Hospital from February 2016 to May 2019, and the rate of, and reasons for, CBCT image re-exposure was tallied. Patient demographics (age and gender) and CBCT acquisition parameters (CBCT unit, field-of-view (FOV), scanned region of interest, and exposure time) were recorded and correlated to retake analysis.

Results: The retake rate was 4.6% (80/1737). The most common reasons for re-exposure were incomplete FOV coverage (57.5%) and motion artifacts (27.5%). Patients under 12 years of age had a significantly higher risk for motion artifacts. CBCT for the temporomandibular joint (TMJ) had a significantly higher risk for incomplete FOV coverage.

Conclusions: Children (less than 12 years of age) demonstrate a higher frequency of retakes, principally due to motion artifacts. TMJ CBCT examinations have a higher frequency of retakes due to an incomplete FOV coverage.

Clinical Relevance: Information regarding the frequency and reasons for CBCT retakes is beneficial to identify procedures, practices, or patients susceptible to additional radiation exposure and implement appropriate and specific quality control protocols.
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http://dx.doi.org/10.1007/s00784-020-03315-3DOI Listing
December 2020

Awareness and practice of 2D and 3D diagnostic imaging among dentists in Hong Kong.

Br Dent J 2020 05;228(9):701-709

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR, China; Department of Oral Health & Medicine, University Centre for Dental Medicine Basel UZB, University of Basel, Basel, Switzerland.

Aims To investigate the awareness and practice of 2D and 3D diagnostic imaging, including respective equipment, specifications, number of images acquired, indications for CBCT scans, preference between 2D and 3D imaging, and the confidence in acquiring and interpreting radiographic images among dentists in Hong Kong.Materials and methods A citywide survey was performed with an online questionnaire that was sent via the local dental association to registered dentists in Hong Kong. The anonymous survey focused on: their dental background; number, type and age of their intra-oral, panoramic devices; CBCT indications, field-of-view and consideration of low-dose protocols; and their confidence in taking and interpreting these images.Results From the feedback collected, 65% of dentists used digital intra-oral systems. Around 70% of respondents who perform CBCTs utilised low-dose protocols to reduce radiation dose. Age and years of practising dentistry were significant influencing factors in determining dentists' utilisation of low-dose protocols for CBCT devices. Male dentists and dentists with higher qualifications generally reported being more confident in taking and interpreting CBCT images. Dentists who were older and had more years of practising dentistry were generally more confident in interpreting CBCT images.Conclusion Only half of the dentists feel confident in taking and interpreting CBCT images, and there seems to be a limited knowledge of radiation dose-related risks. Therefore, continuous professional education should specifically focus on the potential of digital imaging and training in CBCT modalities, radiation dose protection and image interpretation.
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http://dx.doi.org/10.1038/s41415-020-1451-8DOI Listing
May 2020

Bioceramic root repair material (BCRRM) for root-end obturation in apical surgery. An analysis of 174 teeth after 1 year.

Swiss Dent J 2020 05 8;130(5):390-396. Epub 2020 Apr 8.

Oral and Maxillofacial Radiology, Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China.

The objective of this paper was the analysis of the 1-year outcome of teeth treated with apical surgery and a recently introduced bioceramic root repair material (BCRRM) for root-end filling. Patients were consecutively enrolled from 2015 to 2017. Apical surgery included the modern technique, i.e. the use of a surgical microscope, ultrasonic preparation of a root-end cavity, and retrofilling with BCRRM. The cohort comprised 150 patients with 174 treated teeth. Patients were recalled one year after surgery for a clinical and radiographic re-examination. Three experienced observers evaluated the periapical radiographs with regard to periapical healing utilizing the healing criteria established by Rud et al. (1972) and Molven et al. (1987). Based on the clinical findings and the radiographic assessment, healing was judged as successful, uncertain, or failed. Study parameters included gender, age, type of treated tooth, and type of BCRRM (regular vs. fast set putty). At the 1-year follow-up, 170 teeth could be reexamined (drop-out rate 2.3%). Healing outcome was categorized as successful in 94.1%, uncertain in 4.1%, and failed in 1.8%. No significant differences were observed when comparing the success rates among the different subcategories of study parameters. The lowest success rate was noted in mandibular premolars (86.7%) but without reaching statistical significance. In conclusion, BCRRM appears to be a biocompatible root-end filling material showing excellent 1-year results. The success rate was similar to recently reported success rates for BCRRM in apical surgery.
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May 2020

Dry Skulls and Cone Beam Computed Tomography (CBCT) for Teaching Orofacial Bone Anatomy to Undergraduate Dental Students.

Anat Sci Educ 2021 Jan 21;14(1):62-70. Epub 2020 Apr 21.

Dental Materials Science, Division of Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, People's Republic of China.

Learning bone anatomy of the skull is a complex topic involving three-dimensional information. The impact of the use of human dry skulls and cone beam computed tomography (CBCT) imaging was investigated in the teaching of undergraduate dental students. Sixty-four first-year students in the University of Hong Kong were randomly divided into eight groups. Four teaching methods were tested: (1) CBCT followed by standard lecture, (2) CBCT followed by lecture with skulls, (3) standard lecture followed by CBCT, and (4) lecture with skulls followed by CBCT. After each, students were given a multiple-choice questionnaire to assess their objective learning outcome (20 questions) and a questionnaire for their subjective satisfaction (10 statements). Surveys were assessed with Cronbach's alpha, Kendall's tau-b, and principal components analysis. Data were analyzed with Student's t-test and a one-way ANOVA (significance α = 0.05). Standard lecture followed by CBCT showed the highest learning outcome score (81.6% ± 14.1%), but no significant difference was present among four teaching methods. Cone beam computed tomography followed by lecture with skulls scored the highest overall subjective satisfaction (4.9 ± 0.8 out of 6), but no significant difference was present among teaching methods. Nevertheless, students' perception of learning was positively influenced by the use of skulls (P = 0.018). The timing of administration of the CBCT did not affect students' subjective satisfaction or objective learning outcome. Students perceived to learn more by using skulls, but their objective learning outcomes were not significantly affected. A discrepancy seems to exist between students' perception of learning and their effective performance.
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http://dx.doi.org/10.1002/ase.1961DOI Listing
January 2021

Recent Trends and Future Direction of Dental Research in the Digital Era.

Int J Environ Res Public Health 2020 03 18;17(6). Epub 2020 Mar 18.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

The digital transformation in dental medicine, based on electronic health data information, is recognized as one of the major game-changers of the 21st century to tackle present and upcoming challenges in dental and oral healthcare. This opinion letter focuses on the estimated top five trends and innovations of this new digital era, with potential to decisively influence the direction of dental research: (1) rapid prototyping (RP), (2) augmented and virtual reality (AR/VR), (3) artificial intelligence (AI) and machine learning (ML), (4) personalized (dental) medicine, and (5) tele-healthcare. Digital dentistry requires managing expectations pragmatically and ensuring transparency for all stakeholders: patients, healthcare providers, university and research institutions, the medtech industry, insurance, public media, and state policy. It should not be claimed or implied that digital smart data technologies will replace humans providing dental expertise and the capacity for patient empathy. The dental team that controls digital applications remains the key and will continue to play the central role in treating patients. In this context, the latest trend word is created: augmented intelligence, e.g., the meaningful combination of digital applications paired with human qualities and abilities in order to achieve improved dental and oral healthcare, ensuring quality of life.
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http://dx.doi.org/10.3390/ijerph17061987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7143449PMC
March 2020

Extraoral anatomy in CBCT – a literature review. Part 3: Retromaxillary region

Swiss Dent J 2020 Mar;130(3):216-228

Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China

In this review about extraoral anatomy as depicted by cone beam computed tomography, the retromaxillary region is discussed. A medium-sized (6 x 6 cm) or large (≥ 8 x 8 cm) field of view of the maxilla will inevitably depict the retromaxillary region that can be considered a «transition» zone between the viscerocranium and the neurocranium. Major structures of the region include the sphenoid bone and the pterygopalatine fossae. The sphenoid bone is a single but complex bone located between the maxilla and the brain. It is composed of a central body, bilateral greater and lesser wings, and pterygoid processes. Important neurovascular structures pass through the sphenoid bone: the optic nerve and the ophthalmic artery via the optic canal, the maxillary nerve via the foramen rotundum, and the pterygoid nerve via the Vidian canal. The central body of the sphenoid bone also contains the highly variable sphenoid sinus that is the most posteriorly located paranasal sinus. The bilateral pterygopalatine fossae behind the maxillary sinuses contain several important neurovascular structures that supply the maxilla and the midface.
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March 2020

Effects of Dimensions of Root-End Fillings and Peripheral Root Dentine on the Healing Outcome of Apical Surgery.

Eur Endod J 2019 18;4(2):49-56. Epub 2019 Jul 18.

Department of Applied Oral Sciences Oral and Maxillofacial Radiology, University of Hong Kong, China.

Objective: The objective of this study was to assess dimensions of root-end fillings (REFs), as well as peripheral root dentine (PRD) and their effects on the healing outcome of apical surgery.

Methods: Cone beam computed tomography (CBCT) scans were utilized to measure the REF length and width and the PRD thickness in 61 roots of 53 teeth 1 year after apical surgery. Measurements were taken in the mesio-distal as well as bucco-lingual directions. The REF alignment with respect to the root axis was also evaluated. In addition, the dimensions of REF and PRD were assessed for possible correlations with the healing outcome. Criteria for determining the healing outcome included clinical and radiographic parameters.

Results: The mean REF length was 2.02±0.52 mm. No significant differences were observed with regard to tooth groups, but one-canal roots had a significantly longer mean REF than two-canal roots (P=0.006). The mean REF widths were 1.14±0.24 mm mesio-distally and 2.61±1.24 mm bucco-lingually. Roots with two canals presented a significantly wider REF (P<0.001) in the bucco-lingual dimension but had a significantly narrower REF in the mesio-distal direction (P<0.001) compared to roots with single canals. PRD measured on average 1.19±0.23 mm at the resection level and 1.44±0.27 mm at the coronal end of the REF. Almost all REFs were perfectly aligned with the longitudinal axis of the roots. With regard to healing outcomes, no correlations were found with REF and PRD values, respectively.

Conclusion: The mean REF length was 2.02 mm. On average, a thickness >1 mm of peripheral root dentine was maintained. The REF or PRD dimensions had no statistical effect on the healing outcome.
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http://dx.doi.org/10.14744/eej.2019.76376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7006549PMC
July 2019

Cone beam computed tomography artefacts around dental implants with different materials influencing the detection of peri-implant bone defects.

Clin Oral Implants Res 2020 Jul 23;31(7):595-606. Epub 2020 Mar 23.

Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.

Objectives: To investigate the diagnostic accuracy of cone beam computed tomography (CBCT) for the diagnosis of peri-implant bone defects of titanium (Ti), zirconium dioxide (ZrO ) or titanium-zirconium (Ti-Zr) alloy implants.

Materials And Methods: Ti, Ti-Zr or ZrO implants with two diameters (3.3 mm, 4.1 mm) and one length (10 mm) were inserted in the angle of the mandible of six fresh defrosted pig jaws. Out of the 12 implants inserted, 6 served in the test group with standardized buccal peri-implant bone defects, whereas 6 served as control without bone defects. CBCTs were performed with three acquisition protocols (standard, high and low dose) using two devices. Four observers analysed CBCTs as follows: (a) presence of a peri-implant defect; (b) presence of peri-implant artefacts and impact on defect diagnosis; and (c) linear measurements of buccal peri-implant defect including height and width (in mm).

Results: CBCT device, CBCT settings, implant material, implant diameter and observer background did not significantly influence diagnostic accuracy. The sensitivity and specificity values were high for defect detection. ZrO led to a lower than average diagnostic accuracy (0.781). The linear measurements of peri-implant defect were underestimated by <1 mm on average. The subjective impact of artefacts on defect diagnosis was significantly affected by implant material and observer background.

Conclusions: CBCT showed high diagnostic accuracy for peri-implant bone defect detection regardless of the device, imaging setting or implant material used. If CBCT is indicated to assess peri-implant bone disease, low dose protocols could be a promising imaging modality.
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http://dx.doi.org/10.1111/clr.13596DOI Listing
July 2020

A comparison of visual identification of dental radiographic and nonradiographic images using eye tracking technology.

Clin Exp Dent Res 2020 02 18;6(1):59-68. Epub 2019 Oct 18.

Centralized Research Laboratories, Faculty of Dentistry, The University of Hong Kong, Hong Kong, SAR, China.

Objectives: Eye tracking has been used in medical radiology to understand observers' gaze patterns during radiological diagnosis. This study examines the visual identification ability of junior hospital dental officers (JHDOs) and dental surgery assistants (DSAs) in radiographic and nonradiographic images using eye tracking technology and examines if there is a correlation.

Material And Methods: Nine JHDOs and nine DSAs examined six radiographic images and 16 nonradiographic images using eye tracking. The areas of interest (AOIs) of the radiographic images were rated as easy, medium, and hard, and the nonradiographic images were categorized as pattern recognition, face recognition, and image comparison. The participants were required to identify and locate the AOIs. Data analysis of the two domains, entire slide and AOI, was conducted by evaluating the eye tracking metrics (ETM) and the performance outcomes. ETM consisted of six parameters, and performance outcomes consisted of four parameters.

Results: No significant differences were observed for ETMs for JHDOs and DSAs for both radiographic and nonradiographic images. The JHDOs showed significantly higher percentage in identifying AOIs than DSAs for all the radiographic images (72.7% vs. 36.4%, p = .004) and for the easy categorization of radiographic AOIs (85.7% vs. 42.9%, p = .012). JHDOs with higher correct identification percentage in face recognition had a shorter dwell time in AOIs.

Conclusions: Although no significant relation was observed between radiographic and nonradiographic images, there were some evidence that visual recognition skills may impact certain attributes of the visual search pattern in radiographic images.
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http://dx.doi.org/10.1002/cre2.249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7025973PMC
February 2020

Unique air inclusions within the nasopalatine duct indicating its presence radiographically: a case presentation.

Surg Radiol Anat 2020 Jul 10;42(7):817-821. Epub 2020 Feb 10.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, 3010, Bern, Switzerland.

The anterior maxilla is characterized by the nasopalatine canal that originates bilaterally from the anterior nasal floor, subsequently fuses, and terminates at the incisive foramen in the anterior palate. Embryologically, this structure forms within the primary palate, and contains the neurovascular bundle, but also continuous epithelialized bands. The latter, termed nasopalatine ducts, usually degenerate and/or obliterate before birth. However, in some individuals, the ducts may remain partially or completely patent. The present case report describes for the first time in the literature a rare finding of air inclusions within the anatomical area of the nasopalatine canal indicating the presence of a nasopalatine duct as visualized with cone beam computed tomography. The patient was asymptomatic and the radiographic findings were seen incidentally. An endoscopic inspection of the anterior nasal cavities confirmed the presence of the nasal openings of the partially patent nasopalatine ducts.
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http://dx.doi.org/10.1007/s00276-020-02428-4DOI Listing
July 2020

Extraoral anatomy in CBCT – a literature review. Part 2: Zygomatico-orbital region

Swiss Dent J 2020 Feb;130(2):126-138

Oral and Maxillofacial Radiology, Applied Oral Sciences, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China

This second article about extraoral anatomy as seen in cone beam computed tomography (CBCT) images presents a literature review of the zygomatico-orbital region. The latter bounds the maxillary sinus superiorly and laterally. Since pathologic changes of the maxillary sinus are a frequent indication for three-dimensional radiography, the contiguous orbital cavity and the zygomatic bone may become visible on CBCT scans. The zygomatic bone forms the cheek prominence and has large contact areas with the maxilla through the zygomaticomaxillary suture in the infraorbital region as well as with the sphenoid bone along the lateral orbital wall. Each of the three surfaces of the zygomatic bone displays foramina that transmit neurovascular structures. The orbital cavity is located immediately above the maxillary sinus from which it is separated only by a thin bony plate simultaneously serving as the orbital floor and the roof of the maxillary sinus. Several openings, such as the superior and inferior orbital fissures, the ethmoidal and cranio-orbital foramina, and the optic and infraorbital canals, connect the orbit to the anterior and middle cranial fossae as well as to the infratemporal and pterygopalatine fossae.
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February 2020

Sinus floor elevation or referral for further diagnosis and therapy: A comparison of maxillary sinus assessment by ENT specialists and dentists using cone beam computed tomography.

Clin Oral Implants Res 2020 May 12;31(5):463-475. Epub 2020 Feb 12.

Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

Objectives: To compare ear, nose, and throat (ENT) specialists and dentists assessing health or pathology of maxillary sinuses using cone beam computed tomography (CBCT).

Material And Methods: Two ENT specialists and two oral surgeons assessed 100 CBCT datasets of healthy patients referred for dental implant placement in the posterior maxilla and decided on the possibility of sinus floor elevation or the necessity for further diagnostic examinations based solely on radiographic findings. Inter-rater agreements within the same specialty were calculated with Cohen's kappa and overall agreements with Fleiss kappa, and factors influencing the decisions taken were evaluated using regression analyses.

Results: The correlation between all four raters was generally fair to moderate. The intra-specialty comparison showed a lower correlation between dentists than between ENT specialists. Absence of membrane thickening and total or subtotal sinus opacification showed the highest predictive value for a consensus in favor of sinus floor elevation and ENT referral, respectively. Flat membrane thickening with an irregular surface morphology was associated with disagreement between the examiners. Dome-shaped membrane thickenings were often considered as to be referred by dentists but not by ENTs.

Conclusion: The assessment of maxillary sinuses using CBCT imaging exhibited unsatisfactory agreement between ENT specialists and oral surgeons. Referral guidelines based on accidental CBCT findings that aim to diagnose relevant sinus pathologies early and avoid unnecessary diagnostics and/or therapies are needed, and an initial proposal for such recommendations is provided. Further research on correct interpretation of sinus findings and a validation of the present recommendations are required.
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http://dx.doi.org/10.1111/clr.13582DOI Listing
May 2020

Nasopalatine canal and periapical radiolucency fusion following dentoalveolar trauma: A CBCT-based case-control study.

Dent Traumatol 2020 Aug 6;36(4):438-445. Epub 2020 Feb 6.

OMFS-IMPATH Research Group, Department of Imaging & Pathology, Faculty of Medicine, KU Leuven & Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium.

Background/aim: There is a lack of evidence regarding the radiological characteristics of a periapical radiolucency (PRL) fusion with the nasopalatine canal (NPC) following dentoalveolar trauma. The aim of this study was to assess the NPC enlargement resulting from fusion with a PRL and its relationship with the surrounding anatomical structures.

Material And Methods: A total of 100 patients was retrospectively recruited and divided into two groups: case group and control group. The case group consisted of 50 cone-beam computed tomography scans of the maxilla of patients (32 males, 18 females; age range: 11-83 years) with a known history of dentoalveolar trauma in the maxillary anterior region and the presence of an undiagnosed and/or asymptomatic NPC and PRL fusion. An age- and gender-matched control group of 50 patients (32 males, 18 females; age range: 11-82 years) without trauma history to the upper anterior teeth, demonstrating normal maxillary scans, was recruited. A subjective scoring criterion was established for assessing the characteristics of the fused lesion and its relationship with the buccal/palatal alveolar cortex, nasal cavity cortex, NPC cortical border, and maxillary sinus floor.

Results: The fused NPC and PRL was mainly lobular in appearance (88%) with non-corticated well-defined margins (80%). Male patients showed larger (68%) dimensions compared with female patients (32%). The NPC cortical bone was the most commonly perforated structure in relation to fusion (72%), whereas maxillary sinus cortical bone was the least effected (2%). A statistically significant difference was observed between the NPC dimensions in the control and test groups, with fused lesions having larger mesiolateral, craniocaudal, and buccopalatal dimensions (P < .001).

Conclusions: Periapical radiolucencies should be treated as soon as possible before they fuse with NPC. In case of fusion, surgical enucleation should be considered as the treatment of choice.
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http://dx.doi.org/10.1111/edt.12545DOI Listing
August 2020