Papers by Kristina Hellén-Halme
Aktuel nordisk odontologi, Apr 15, 2009
Medicina-lithuania, Oct 12, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Aims: The overall aim was to establish the degree of artifacts made by orthodontic appliances in ... more Aims: The overall aim was to establish the degree of artifacts made by orthodontic appliances in MRI. Specific aim was to investigate if any sequences applied at the investigation could improve the images quality. Materials and Methods: Twelve frequently used orthodontic appliances were tested. The appliances were cemented/bonded on twelve study casts placed in translucent plastic boxes filled with water and contrast. The MRI expositions were performed in a 1.5 Tesla and 3 Tesla scanners respectively (1.5 T: MAGNETOM AvantoFit, 3 T: MAGNETOM Trio, Siemens Healthcare, Erlangen, Germany). The used imaging sequences to reduce the artifacts were 1) turbo spin echo (TSE), 2) TSE combined with view angle tilting (VAT), and 3) TSE with both VAT and slice encoding for metal artifact correction (SEMAC). Results: After the MR imaging and the artifacts reduce imaging sequences technique (TSE, TSE combined with VAT and TSE with VAT and SEMANC) the Orto-pro nickel free brackets showed the largest amount of image artifacts, while the gold chain, titanium brackets and buccal mini-screws showed smallest artifact. TSE with both VAT and SEMAC artifact reduction imaging sequences were the best sequence to improve MRI quality. Conclusion: Titanium brackets showed the smallest artifact compared to conventional and nickel free brackets. TSE with both VAT and SEMAC imaging sequence to reduce the artifacts was superior in improving image quality than the TES and TES combined with VAT
Dentomaxillofacial Radiology, Sep 1, 2020
Objective: Evaluation of cone beam CT (CBCT) examination with a low-dose scanning protocol for as... more Objective: Evaluation of cone beam CT (CBCT) examination with a low-dose scanning protocol for assessment of the temporomandibular joint (TMJ). Methods: 34 adult patients referred for CBCT imaging of the TMJ underwent two examinations with two scanning protocols, a manufacturer-recommended protocol (default) and a lowdose protocol where the tube current was reduced to 20% of the default protocol. Three image stacks were reconstructed: default protocol, low-dose protocol, and processed (using a noise reduction algorithm) low-dose protocol. Four radiologists evaluated the images. The Sign test was used to evaluate visibility of TMJ anatomic structures and image quality. Receiver operating characteristic analyzes were performed to assess the diagnostic accuracy. κ values were used to evaluate intraobserver agreement. Results: With the low-dose and processed protocols, visibility of the TMJ anatomical structures and overall image quality were comparable to the default protocol. No significant differences in radiographic findings were found for the two low-dose protocols compared to the default protocol. The area under the curves (A z) averaged for the low-dose and processed protocols, according to all observers, were 0.931 and 0.941, respectively. Intraobserver agreement was good to very good. conclusion: For the CBCT unit used in this study, the low-dose CBCT protocol for TMJ examination was diagnostically comparable to the manufacturer-recommended protocol, but delivered a five times lower radiation dose. There is an urgent need to evaluate protocols for CBCT examinations of TMJ in order to optimize them for a radiation dose as low as diagnostically acceptable (the as low as diagnostically acceptable principle recommended by NCRP).
Journal of Dental Applications, 2021
Background: The aim of this study was to investigate whether a complementary Cone-Beam Computed T... more Background: The aim of this study was to investigate whether a complementary Cone-Beam Computed Tomography (CBCT) in patients with Cleft Lip and Palate (CLP) after alveolar bone-grafting to clefts gave substantial additional information, and particularly whether such new information had any implications for the further care of the patients. Methods: Seventeen children, with complete CLP, 10 unilateral and seven bilateral clefts, in all 24 clefts, were evaluated six months after secondary alveolar bone-grafting with two-dimensional intra-oral radiographs complemented with CBCT. The mean age at bone-grafting was 8.8 years. Three different examiners evaluated the radiographic documentation. Results: The mean pre-operative cleft width was 5.8mm. In 15 of the 24 clefts the same interpretation was made on both two-dimensional radiographs and CBCT. In the remaining nine clefts, CBCT added important information to the treatment decision. Conclusions: For the evaluation six months post-opera...
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Acta Odontologica Scandinavica
Evaluation of low-dose multislice computed tomography, on image quality, in a group of orthognath... more Evaluation of low-dose multislice computed tomography, on image quality, in a group of orthognathic patients
Dentomaxillofacial Radiology, 2012
Objectives: This study investigated how ambient light affects the diagnostic accuracy of dental c... more Objectives: This study investigated how ambient light affects the diagnostic accuracy of dental carious lesions on monitors used in dental practice. Specifically, the aim was to evaluate whether a monitor hood for blocking excess ambient light increases practitioners' ability to accurately diagnose carious lesions on digital radiographs under bright ambient light conditions. Methods: 7 observers evaluated approximal carious lesions on standardized digital radiographs of 100 teeth under 3 ambient light conditions: bright light (. 1000 lx) and dim light (, 50 lx) with no monitor hood; and bright light with a hooded monitor. Receiver operating characteristic curves were plotted for all observations. The criterion standard was a histological examination of the teeth. A paired t-test compared the effects of the three lighting conditions. The level of significance was set to p , 0.05. Weighted kappa statistics estimated intraobserver agreement. Results: The diagnostic accuracy for dentine lesions was significantly higher in ambient light , 50 lx than on monitors with and without a hood in ambient light. 1000 lx. For all observers, diagnostic accuracy of dentine lesions under bright light was higher on a hooded monitor than on a monitor without a hood, but this difference was not significant. Intraobserver agreement varied from moderate to good. Conclusion: Diagnostic accuracy of those carious lesions that reached into the dentine was significantly higher in ambient light , 50 lx than in ambient light. 1000 lx. A hooded monitor in bright light was not as effective as a monitor without a hood in dim light.
BMC Oral Health
Background Preterm birth has been shown to cause various long-term health issues. Children who we... more Background Preterm birth has been shown to cause various long-term health issues. Children who were born preterm have also been observed to have more dental behaviour management problems (DBMP) during dental examinations and treatment than children born full term. It is known that dental radiographic examinations can be uncomfortable and cause anxiety in paediatric patients. Thus, our aims were to retrospectively compare dental care related examinations and treatments carried out in three different age intervals (3–6 years, 7–12 years, and 13–19 years) among preterm- and full-term born children and adolescents. Methods The present study included 311 patient files: 122 very preterm–born and 33 extremely preterm–born children and adolescents (< 32 gestational weeks). A matched control group of 156 full term–born children and adolescents (≥ 37 gestational weeks) was analysed for comparison. Various factors, including DBMP, missed appointments, dental caries, and radiographic examina...
Journal of Oral Rehabilitation, 2018
OBJECTIVES Osseous changes in temporomandibular joint disorders (TMD) are common indications for ... more OBJECTIVES Osseous changes in temporomandibular joint disorders (TMD) are common indications for cone beam computed tomography (CBCT). The number of such cases is increasing while a number of qualified oral radiologists is limited. This study investigated the usefulness of a training programme for general dental practitioners (GDPs) regarding temporomandibular joint (TMJ) osseous changes detection in CBCT images. METHODS We selected CBCT images of 35 TMD cases and chose 5 of them to use in training 7 GDPs on detecting osseous changes in the TMJ. In evaluation directly following training, GDPs assessed the 30 remaining cases. Three qualified radiologists served as reference standard. A 2-month follow-up of training comprising evaluation of the same cases. The cases are assessed according to Ahmad et al (Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 107, 2009, 844) protocol of TMJ osseous changes in CBCT images. RESULTS Sensitivity and specificity of the CBCT protocol were high, except for some criteria that did not appear in the cases. Average observer sensitivity was 65% while specificity was 87%. Average correct individual response rate was 84%. Mean agreement among the GDPs was 73%. Observer performance had improved at the 2-month follow-up. CONCLUSION The present educational programme could be a helpful material on recognising possible osseous changes of TMJ and it can be used as a part of a training programme for GDP and for specialist candidates.
Background: Preterm birth has been shown to cause various long-term health issues. Children who w... more Background: Preterm birth has been shown to cause various long-term health issues. Children who were born preterm have also been observed to have more behaviour management problems (BMP) during dental examinations and treatment than children born full term. It is known that dental radiographic examinations can be uncomfortable and cause anxiety in paediatric patients. Our aims were to compare a matched control group of full term-born children and adolescents with preterm–born children and adolescents concerning oral health outcomes, such as prevalence of BMP, missed appointments, caries, treatment needs, including the need for a dental radiographic examination, and experience of orthodontic treatment.Methods: The present study included 311 patient files: 122 very preterm–born and 33 extremely preterm–born children and adolescents (<32 gestational week). A matched control group of 156 full term–born children and adolescents (≥ 37 gestational week) was analysed for comparison. Vari...
BMC Medical Imaging, 2021
Background Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms... more Background Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms. The study investigates the aerodynamic characteristics within the upper airway (UA) by means of computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios. Methods This retrospective study included thirty-five patients aged 9–15 years having both lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. The cases were divided into two subgroups according to the AN ratios measured on the lateral cephalograms: Group 1 with an AN ratio
Swedish dental journal, 2016
OBJECTIVE This study investigated the diagnostic accuracy of digital dental radiograpny for detec... more OBJECTIVE This study investigated the diagnostic accuracy of digital dental radiograpny for detecting carious lesions on approximal surfaces before and after optimization of the environ- ment, and after joint training on evaluation and review of x-rays. A further aim was to evaluate differences in diagnostic accuracy between general dental practitioners (GDPs) and dental hygienists (DHs). MATERIALS AND METHODS One hundred extracted teeth (premolars and molars) underwent standardized radiography. Eleven participants (seven GDPs and four DHs) evaluated digital images for approximal carious lesions in three sessions: (1) at current conditions with no optimization or further training, (2) under optimized viewing conditions, and (3) under optimized viewing conditions after a short educational session. Receiver operating characteristic curves were,used to evaluate the results. Histological evaluation was made and served as a cri- terion standard for differentiating sound teeth and teeth w...
Journal of Oral Rehabilitation, 2020
OBJECTIVES To develop and evaluate an educational web-based program for temporomandibular joint (... more OBJECTIVES To develop and evaluate an educational web-based program for temporomandibular joint (TMJ) assessment using cone-beam computed tomography (CBCT). METHODS A web-based educational program was designed for TMJ assessment using CBCT images. Fifteen CBCT cases of the TMJ (three-dimensional reconstructed volumes) and an assessment module based on image analysis criteria in the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were added to the program. Thirty-six undergraduate dental students were invited to test the program by assessing all cases twice: before and after 2 months of training. Participants submitted written subjective evaluations of the program. RESULTS The web-based program can be accessed on Malmö University webpage (www.cbct-tmj.mau.se). Despite limited CBCT learning in their undergraduate training and not using the program in the 2-month interval, the students were able to correctly diagnose 80% of the cases at the second assessment. Their diagnoses, however, did not differ significantly from the first assessment. Overall, the students were satisfied with the program and considered it user friendly. CONCLUSION The web-based educational program that was developed in the present study and tested by dental students could be a useful educational tool for TMJ assessment using CBCT.
Clinical Oral Investigations, 2021
Objectives To query the experience of oral surgeons concerning referral routines and preferences ... more Objectives To query the experience of oral surgeons concerning referral routines and preferences for radiographic imaging modality before surgical removal of mandibular third molars and investigate factors that influence imaging modality preferences. Materials and methods Members of the Swedish Association of Oral and Maxillofacial Surgeons (n = 280) were invited to participate in a web-based digital survey concerning their experiences and use of three imaging modalities in pre-surgical assessment of mandibular third molar removal. The survey comprised multiple-choice questions and four cases depicted in images; respondents reported whether they would supplement the cases with other images and, if so, from which modality. Results The response rate was 64%. Panoramic radiographs were most commonly used in pre-surgical planning (response options: always or often), significant difference between professions (p = 0.039), and considered to facilitate treatment planning (87%), as was CBCT...
Journal of Clinical Pediatric Dentistry, 2021
Objectives The present study evaluated the effect of rapid maxillary expansion (RME) on the morph... more Objectives The present study evaluated the effect of rapid maxillary expansion (RME) on the morphology of the upper airway (UA) by calculating cross-sectional areas and volumes and comparing the effect in patients with a normal-sized adenoid with the effect in patients with an enlarged adenoid. Study design: Seventeen patients met the inclusion criteria. We constructed 3D models of the UA on cone-beam computed tomography images to calculate cross-sectional areas and volumes at the levels of the nasopharyngeal, retropalatal, and retroglossal airways. Patients were divided into two groups: group 1 was comprised of patients with an adenoidal nasopharyngeal (AN) ratio < 0.6 and group 2 with an AN ratio ≥ 0.6. Paired samples t-tests assessed any area and volumetric changes of the UA after RME. Changes in degree of nasal obstruction, calculated as the AN ratio, was then compared for the two groups. An independent samples t-test compared volumetric changes in the nasopharynx between the...
Background: The lateral cephalogram is a common imaging diagnostic test for adenoid hypertrophy (... more Background: The lateral cephalogram is a common imaging diagnostic test for adenoid hypertrophy (AH) in clinics. The study aims to investigate the aerodynamic characteristics within the upper airway (UA) by employing a computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios.Methods: This retrospective study included thirty-five cases involving individuals aged 9-15 years who fulfilled the inclusion criteria of having both a lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. Based on the three-dimensional (3D) models of the UA segmented from the CBCT images, the aerodynamic characteristics at inspiration and expiration were simulated by the CFD method. The studied aerodynamic parameters were pressure drop (△P), maximum midsagittal velocity (Vms), maximum wall shear stress (Pws), and minimum wall static pressure (Pw). The cases were di...
Clinical Oral Implants Research, 2019
Dentomaxillofacial Radiology, 2013
This study investigated the effect of different monitor calibration modes under various ambient l... more This study investigated the effect of different monitor calibration modes under various ambient lighting conditions on the ability of observers to recognize proximal carious lesions of varying depths. 7 observers evaluated 100 teeth for proximal carious lesions on standardized digital radiographs using 3 set-ups: (1) pre-calibrated monitor for high ambient light (higher than 1000 lux), (2) pre-calibrated monitor for low ambient light (less than 50 lux) and (3) Barten calibration (Digital Imaging and Communication in Medicine) on the monitor in dimmed ambient light (less than 50 lux). Receiver operating characteristic curves were plotted for all observations. The criterion standard was histological examination of the teeth. The effects of three conditions were compared using a paired t-test. The level of significance was set to p &lt; 0.05. No significant difference was found in diagnostic accuracy for the detection of any type of proximal carious lesions between the different calibration modes of the monitor according to different ambient light levels. There is no evidence that any difference between ambient light levels affects the ability to detect carious lesions in digital radiographs as long as the monitor was calibrated in accordance with the surrounding light level.
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Papers by Kristina Hellén-Halme