Three-dimensional replica of the temporal bone in the teaching of human anatomy.

PURPOSE: The current study proposes the comparison of the visualization and identification of anatomical details between natural human temporal bone, its respective copy from three-dimensional printing, and the virtual model obtained from CBCT. METHODS: The sample consisted of undergraduate students in Dentistry (Group UE, n = 22), Postgraduate students in Radiology and Imaging (Group P-RI, n = 20), and Postgraduate students in Forensic Odontology (Group P-FO, n = 24). All participants attended a theoretical class on specialized anatomy of the temporal bone and subsequently performed the markings of 10 determined structures. RESULTS: The number of correct identifications was similar in natural bone and printed three-dimensional models in all groups (p > 0.05). The virtual model showed a significantly lower number of correct structures (p < 0.05) in the 3 groups. In general, there were significantly higher percentages of accurate answers among postgraduate students compared to undergraduate students. Most graduate students believed that the printed three-dimensional model could be used to teach anatomy in place of natural bone, while undergraduate students disagreed or were unsure (p < 0.05). Regarding the virtual tomographic image, in all groups, students disagreed or were not sure that its use would be beneficial in replacing natural bone. CONCLUSION: Three-dimensional and virtual models can be used as auxiliary tools in teaching anatomy, complementing practical learning with natural bones.

Influence of surgeon experience on implant placement in guided surgeries: A systematic review and meta-analysis of randomized clinical trials.

STATEMENT OF PROBLEM: Guided surgical techniques in implant dentistry use virtual planning to accurately position implants. Understanding the effect of a surgeon's experience on guided surgery is essential to ensure successful outcomes. PURPOSE: The purpose of this systematic review and meta-analysis of randomized clinical trials was to evaluate the influence of a surgeon's experience on the accuracy of implant positioning in guided surgery for completely or partially edentulous patients. MATERIAL AND METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, searches were conducted in the PubMed, Scopus, Web of Science, EMBASE, Cochrane Library, SciELO, and nonpeer-reviewed literature databases. Studies that met the population, intervention, control, and outcome (PICO) strategy were included: a completely or partially edentulous maxilla or mandible, guided surgery performed by experienced and inexperienced surgeons, and assessing implant positioning accuracy. A random-effects meta-analysis with a 95% confidence interval was conducted using Stata 15.1. The risk of bias was assessed with the Cochrane risk-of-bias tool for randomized trials (RoB2), and evidence certainty was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42022302288). RESULTS: Three articles from 2017 to 2020 encompassing 43 participants (22 men and 21 women) with a mean age of 61.2 years and a total of 150 implants were included. No significant difference was found between experienced and inexperienced surgeons in terms of angular, cervical, or apical deviations of the implants (95% confidence interval, P<.05). The difference between surgeons regarding positioning accuracy was less than 0.01 degrees for angular deviation, 0.35 mm for apical deviation, and 0.16 mm for cervical deviation. Low heterogeneity was observed for angular deviations (Q P=.021, I2=34%, and t2<.001) and cervical deviations (Q P=.18, I2=45%, and t2=.064). High heterogeneity was observed for apical deviations (Q P<.001, I2=87% and t2=.522). The overall bias risk was moderate, with the evidence certainty ranging from low to moderate. CONCLUSIONS: In guided surgery, the surgeon's experience did not significantly impact the occurrence of deviations in implant positioning.

Influence of CBCT-derived panoramic curve variability in the measurements for dental implant planning.

OBJECTIVE: To investigate whether the curve markings performed prior to panoramic and cross-sectional reconstructions can influence the planning of oral implants. METHODS: Twenty oral radiologists landmarked the reference panoramic curves in 25 CBCT scans of the mandible. Bone height was measured on the resulting cross-sectional slices in the edentulous region of the lower first molar. The following data were recorded: (1) number of landmarks used to build each reference curve; (2) shape of the reference curve (inverted "U", inverted "V" or "horseshoe"); and (3) measurement in the first molar region. The data were assessed for variability based on the number of landmarks, the shape of the reference curve, and the measurements obtained. RESULTS: The number of landmarks used to guide the panoramic reconstruction varied among radiologists (p < 0.05), but most of them draw curves in inverted "U" shape (68-100%). The reproducibility of the measurements taken in the edentulous mandibular first molar region was excellent (84.7%). The number of landmarks and the shape of the curve did not have a significant influence on the reproducibility of the measurements (p > 0.05). CONCLUSION: Variations of the operator-dependent steps during the panoramic reconstructions occur but do not play a significant part changing the measurements taken for oral implant planning.

Prevalence and Characterization of External Cervical Resorption Using Cone Beam Computed Tomography.

INTRODUCTION: The aim of this study was to assess the prevalence of external cervical resorption (ECR) and characterize the cases of ECR using cone beam computed tomography (CBCT). METHODS: High-resolution CBCT scans of 6216 patients (2280 males and 3936 females), consecutively acquired during the period July 2021 to March 2022, were analyzed. Identified cases of ECR were characterized by 3 evaluators regarding lesion height, circumferential spread, portal of entry proximity to root canal, stage, location, and width. RESULTS: In a total of 38 patients and 40 teeth, ECR cases demonstrated an incidence of 0.61%. The median age of the patients was 39 years. Prevalence of ERC was 0.78% among males and 0.50% among females. The most affected teeth were the maxillary incisors and canines. The most frequent characteristics of the lesion were: extension up to the cervical third (47.5%), more than 270° circumferential spread (42.55%), probable pulpal involvement (57.5%), progressive stage (65%), supracrestal (52.1%) and mesial (34.7%) localization of >1 mm in size (52.1%) portals of entry. Cases with greater longitudinal involvement also showed greater circumferential progression (P = .008). There was no association between portal of entry location and bone crest or ECR reparative phase (P = .42). Inter-rater agreement ranged from good to very good. No association between portal of entry and ECR progression was observed. CONCLUSIONS: ECR showed low prevalence in the Brazilian population, affecting mostly anterior maxillary teeth of patients within a wide age range. CBCT allowed characterization of ECR lesions with good interobserver agreement.

Panoramic Radiography vs. CBCT in the Evaluation of the Maxillary Third Molar Roots.

Background and Objectives: A comprehensive understanding of the position of third molar roots and adjacent structures, such as the maxillary sinus (MS), is essential for safe extractions. Diagnostic imaging plays a fundamental role in achieving accurate treatment planning. This study aimed to compare panoramic radiography (PR) and cone-beam computed tomography (CBCT) for the evaluation of maxillary third molar roots and their relationship with the MS. Materials and Methods: Two trained radiologists evaluated third molar images. The number of roots, morphology (fused/conical, divergent, dilacerated, or atypical), and their relationship with the MS in PR and CBCT were registered. Descriptive and inferential statistics were performed using the weighted Kappa test. Results: Regarding the number and morphology of the roots, Kappa values showed moderate (κ = 0.42) and fair agreement (κ = 0.38), respectively. Regarding the proximity with the MS, most of the roots showed close contact (30.6%), or 1/3 of root superimposition (35%), in PR evaluation, while in CBCT, the third molars were in contact with the MS floor (32%), and with alveolar domes (27.2%). Conclusions: PR is a moderately reliable image technique to identify the number of roots and root morphology of maxillary third molars. PR, however, does not provide any radiographic signs that clearly indicate the anatomical relationship between the maxillary third molar roots and the maxillary sinus detected in CBCT images.

Effect of cone-beam computed tomography metal artefact reduction on incomplete subtle vertical root fractures.

Purpose: This study compared the accuracy of detection of incomplete vertical root fractures (VRFs) in filled and unfilled teeth on cone-beam computed tomography images with and without a metal artefact reduction (MAR) algorithm. Materials and Methods: Forty single-rooted maxillary premolars were selected and, after endodontic instrumentation, were categorized as unfilled teeth without fractures, filled teeth without fractures, unfilled teeth with fractures, or filled teeth with fractures. Each VRF was artificially created and confirmed by operative microscopy. The teeth were randomly arranged, and images were acquired with and without the MAR algorithm. The images were evaluated with OnDemand software (Cybermed Inc., Seoul, Korea). After training, 2 blinded observers each assessed the images for the presence and absence of VRFs 2 times separated by a 1-week interval. P-values<0.05 were considered to indicate significance. Results: Of the 4 protocols, unfilled teeth analysed with the MAR algorithm had the highest accuracy of incomplete VRF diagnosis (0.65), while unfilled teeth reviewed without MAR were associated with the least accurate diagnosis (0.55). With MAR, an unfilled tooth with an incomplete VRF was 4 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition, while without MAR, an unfilled tooth with an incomplete VRF was 2.28 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition. Conclusion: The use of the MAR algorithm increased the diagnostic accuracy in the detection of incomplete VRF on images of unfilled teeth.

Prevalence of orofacial alterations in patients with sickle-cell disease: Systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to identify the prevalence of orofacial alterations in sickle-cell disease (SCD) and to compare it with the general population. STUDY DESIGN: This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. The search was conducted on PubMed, Embase, Scientific Electronic Library Online, Web of Science, Cochrane Library, gray literature, and references of the included articles. RESULTS: A total of 770 records were found, and 28 studies were selected. In SCD, the prevalence of decreased bone density was 57% (95% CI: 35%-80%), with Q: P < .01 and I2 = 95%; for stepladder pattern was 30% (IC: 13%-47%), Q: P < .01 and I²: 93%; for delayed eruption was 20% (95% CI: 6%-34%), with Q: P < .01 and I2 = 86, Q: P < .01 and I2 = 99%; and for malocclusion, 66% (95% CI: 39%-92%), Q: P < .01 and I2 = 98%. A high risk of bias was observed in relation to the sample size of the studies. A limited number of articles compared the prevalence of orofacial alterations in patients with SCD and healthy individuals. CONCLUSIONS: Decreased bone density, malocclusion, orofacial pain, tooth necrosis, eruption delay, periodontal disease, and neuropathies may be present in patients with SCD with variable prevalence.

Radiographic dental age estimation applying and comparing Demirjian's seven (1973) and four (1976) teeth methods.

To apply Demirjian's seven (1973, D7) and four (1976, D4) teeth methods in a sample of Brazilian children and compare their performances for age estimation. Panoramic radiographs of 1200 children (600 females and 600 males) were collected from Southeast Brazil. The children were equally distributed (n = 60 females and 60 males) between age intervals of 1 year between 6 and 15.9 (mean age = 10.9; standard deviation [SD]: 2.9) years. D7 and D4 dental age estimation methods were applied by two observers and were compared based on their error rates (error = estimated age-chronological age). Both methods overestimated the chronological age (p < 0.0001). D7 led to overestimations of 0.71 (p < 0.0001) in females and 0.83 (p < 0.0001) in males, while the overestimations with D4 were 0.14 (p = 0.0067) and 0.73 (p < 0.0001) for females and males, respectively. The mean age estimated by D7 was 11.7 (SD: 3.1) years, while for D4, it was 11.3 (SD: 3.3) years. Intra- and interobserver agreement was ≥ 0.98. D4 optimized the performance of radiographic dental age estimation compared to D7. Improvements were reflected in the total sample and separately for female and male children from Southeast Brazil.

Assessment of cone beam computed tomography for determining position and prognosis of interradicular mini-implants.

OBJECTIVE: To investigate the influence of dynamic visualization of cone beam computed tomography (CBCT) scans on orthodontist's assessment of positioning status and prognosis of interradicular mini-implants (MI). METHODS: Three MI positions were virtually simulated in thirty CBCT volumes: (1) MI 1 mm from the lamina dura (LD), (2) MI touching the LD and (3) MI overlapping the LD. Each position was exposed to orthodontists (n = 35) as panoramic reconstruction, sagittal reconstruction and a sequence of axial slices. Each orthodontist evaluated the MI position (relationship with the LD) and scored the prognosis using a four-point scale (the higher the score, the better the prognosis). Kappa, Friedman and Nemenyi statistics were used. RESULTS: Statistically significant associations were detected between the prognosis scores and the type of image visualized (p<0.05). The dynamic visualization of the CBCT volume (axial slices) was associated with higher scores for prognosis and more reliable evaluation of MI positioning. Inconsistent outcomes were more frequently associated with panoramic and sagittal reconstructions. CONCLUSION: The dynamic visualization of axial slices allowed orthodontists to perform better assessment of MI position and considerably affected prognosis judgment.

Effect of decompression and online transmission on the dimensional changes of .stl files generated by intra-oral scanning.

Intraoral scans became part of the virtual planning in Dentistry. In the new scenario of digital workflows, dental clinics and laboratories had to establish an online communication that requires the compression, decompression, and transmission of 3D files. Knowledge about the effects of these procedures on the dimensional properties of the files is fundamental to ensure a more realistic virtual planning. The aim of this study was to assess the influence of 3D file compression, decompression, and online transmission on the dimensional properties of dental models from intraoral scanning. Intraoral scan files in.stl format of 50 patients were selected from the database of a dental radiology clinic, with 25 of these patients with mixed dentition and 25 with permanent dentition. The maxilla and mandible scans of each patient were included in the study, generating a total of 100 files. A folder with the 100 files was created and replicated six times with different labels (A, B, C, D, E, F), totaling a sample number of 600 files. Folder A was compressed by WinZip and then decompressed. Folder B went through the same process, but the step of compression and decompression by WinZip was repeated 10 times. The folders C, D, E, F were sent, respectively, through the platforms WeTransfer, Dropbox, Google Drive, and OneDrive, then each of them was downloaded in their respective platforms. After the six folders went through the compression process and were sent by the platforms, each file in the folder was compared with its original file by superimposing the 3D images and identifying the dimensional deviation in the compressed file in relation to the original file. We observed that there were no differences between the six groups regarding dimensional changes from the compression, decompression and online transmission processes. The lack of dimensional changes was observed for the sets of permanent and deciduous. teeth We concluded that it is possible to compress, decompress, and transfer.stl format files online without causing dimensional distortions in the 3D model.

Two-dimensional radiographs versus cone-beam computed tomography in planning mini-implant placement: A systematic review.

Background: This study aimed to compare two-dimensional radiographs and cone beam computed tomography (CBCT) images for mini-implant planning. Material and Methods: A search was performed in PubMed, Embase, Web of Science, Cochrane Library and Google Scholar electronic databases according to PIRD strategy, on September 11, 2021. In vivo studies that compared two-dimensional imaging with CBCT for mini-implant planning were selected. The methodological quality of each study was assessed using the QUADAS-2 tool. Results: The initial search identified 441 papers. Five studies were added following a manual research. Of the total 446 studies, 40 were selected after title evaluation, 29 remained after abstract evaluation, and 11 were left after full-text analysis. Final screening yielded a total of four studies that composed the narrative synthesis of this systematic review. When comparing the imaging systems for palatal mini-implants, lateral radiographs (LRs) showed approximately the same measurements of bone quantity as those of CBCT, hence bearing no influence on placement site selection. In determining image suitability for interradicular mini-implants, two-dimensional radiographs underestimated the available space. Conclusions: Lateral radiography is sufficient to quantify the available bone for planning mini-implants installed on the palate, in the median region of upper first premolars. CBCT enhances interradicular mini-implant planning by aiding in implantation site selection, and improving the installation success rate. Key words:Systematic Review, Cone beam computed tomography, Radiography, Orthodontic mini-implant, Dental planning.

CBCT study on the prevalence, morphology and position of the mandibular incisive canal in a North-Brazilian population.

Background: The mandibular incisive canal (MIC) is an anatomic structure to be considered in treatment planning for surgeries in the anterior region of the mandible. Awareness of the MIC increased with the use of 3D imaging for treatment planning, such as cone beam computed tomography (CBCT). This study aimed to use CBCT to assess the prevalence, morphology and position of the MIC among North-Brazilians. Material and Methods: The sample consisted of CBCT scans of 100 hemi-mandibles (50 individuals) that were assessed for the absolute (n) and relative frequency of the MIC. The morphological component of this study was the diameter (mm) of the detected MIC in five anatomic sites between the mental foramen and the midline. Within the interformainal region, the position of the MIC was assessed by measuring (mm) the distances between the MIC and the basal, vestibular and lingual cortical bone surfaces. Results: The prevalence of the MIC was >76% considering the different anatomic regions screened in CBCT. The mean diameter of the MIC progressively reduced from 1.29 mm to 0.86 throughout the five anatomic regions measured. The position of the MIC showed a downward trajectory away from the lingual cortical bone surface. Conclusions: MIC was a highly prevalent anatomic structure in the studied sample. The funnel-shaped outline of the MIC and its trajectory into the interforaminal region highlighted a major risk of damage to the neurovascular bundle in surgeries (e.g. implant placement) that are close to the mental foramen and the vestibular cortical bone. Key words:Anatomy, cone beam computed tomography, imaging, mandibular incisive canal, oral radiology.

Evaluation of the dosimetry and centralization of scout-view function in CBCT.

This study evaluated the centralization of the region of interest (ROI) in acquisition of the CBCT images, when the freely positionable scout-view (SV) function is applied. Additionally, the dosimetry of the acquired images was assessed in the SV function alone as well as in complete tomographic image in two different fields of view (FOV) (50x50 and 78x150mm). A three-location device was created to accommodate the dosimeters and the specimens, in the right, middle and left location during image acquisition. For dose assessment, thermoluminescent dosimeters were irradiated within the FOV and analyzed in a portable reader. For ROI evaluation, three specimens of gutta-percha stick were placed on the same device and the CT scans were acquired (CBCT OP 300 Maxio device, 90kV, 13mA, 85 µm voxel size, FOV of 50X50mm), with and without the SV, in three positions (3-9, 1-7 and 5-11 o'clock), simulating different regions of the mouth. Two image evaluations were performed, an objective and subjective. There was a slight percentage increase (1.36% to 1.40%) of the radiation dose with the use of SV. The distances were significantly greater in the images acquired without SV (p < 0.05). Every image obtained with SV was classified as being at the FOV's center. In conclusion, the results demonstrated that SVs function is effective to centralize the ROI in the FOV, increasing the scan precision and avoiding repetitions due to positioning errors.

Evaluation of the dosimetry and centralization of scout-view function in CBCT

Abstract This study evaluated the centralization of the region of interest (ROI) in acquisition of the CBCT images, when the freely positionable scout-view (SV) function is applied. Additionally, the dosimetry of the acquired images was assessed in the SV function alone as well as in complete tomographic image in two different fields of view (FOV) (50x50 and 78x150mm). A three-location device was created to accommodate the dosimeters and the specimens, in the right, middle and left location during image acquisition. For dose assessment, thermoluminescent dosimeters were irradiated within the FOV and analyzed in a portable reader. For ROI evaluation, three specimens of gutta-percha stick were placed on the same device and the CT scans were acquired (CBCT OP 300 Maxio device, 90kV, 13mA, 85 µm voxel size, FOV of 50X50mm), with and without the SV, in three positions (3-9, 1-7 and 5-11 o'clock), simulating different regions of the mouth. Two image evaluations were performed, an objective and subjective. There was a slight percentage increase (1.36% to 1.40%) of the radiation dose with the use of SV. The distances were significantly greater in the images acquired without SV (p < 0.05). Every image obtained with SV was classified as being at the FOV's center. In conclusion, the results demonstrated that SVs function is effective to centralize the ROI in the FOV, increasing the scan precision and avoiding repetitions due to positioning errors.

Resumo Este estudo avaliou a centralização da região de interesse (ROI) na aquisição das imagens de TCFC, quando a função scout-view (SV) posicionável livremente é aplicada. Adicionalmente, a dosimetria das imagens adquiridas foi avaliada isoladamente na presença da função SV, bem como após aquisição de imagem tomográfica completa em dois diferentes campos de visão (FOV) (50x50 e 78x150mm). Um dispositivo de três localizações foi criado para acomodar os dosímetros e os espécimes, na localização direita, central e esquerda, durante a aquisição das imagens. Para avaliação da dose, dosímetros termoluminescentes foram irradiados dentro dos campos de visão e analisados em leitor portátil. Para avaliação da ROI, três espécimes de guta percha foram colocados no mesmo aparelho e as tomografias foram adquiridas (CBCT OP 300 Maxio, 90kV, 13mA, 85 μm tamanho de voxel, FOV de 50X50mm), com e sem a SV, em três posições (3-9, 1-7 e 5-11 horas), simulando diferentes regiões da boca. Foram realizadas duas avaliações de imagem, uma objetiva e outra subjetiva. Houve um leve aumento percentual (1,36% para 1,40%) da dose de radiação com o uso de SV. As distâncias foram significativamente maiores nas imagens adquiridas sem SV (p < 0,05). Todas as imagens obtidas com SV foram classificadas como sendo do centro do FOV. Em conclusão, os resultados do presente estudo demonstraram que a função scout view é eficaz para centralizar a ROI no FOV, aumentando a precisão do escaneamento e evitando repetições devido a erros de posicionamento.

A large sample-sized study on dental development of children treated at the Central Dental Clinic (OCEx) of the Brazilian Army.

OBJECTIVES: To test and compare the performance of two radiographic methods for dental age estimation on a large sample of Brazilian boys and girls. MATERIAL AND METHODS: The sample consisted of 1.990 panoramic radiographs of Brazilian children (age: 3-15.9 years) equally balanced based on sex. The sample was distributed into ten age categories, each with up to 200 children. Age estimation was performed with Willems' (2001) and Demirjian's (1973) methods. Estimated (EA) and chronological (CA) ages were compared. The performances of the methods were quantified based on sex and age category. RESULTS: The overall differences between CA and EA for Willems' method in boys and girls were 0.06 and - 0.02, respectively. For Demirjian's method, the differences were 0.60 and 0.74, respectively. The overestimations of Demirjian's method were statistically significant (p < 0.001). Willems' method reached the best outcomes among children between 3 and 12 years, while Demirjian's best performances were between the ages of 7 and 10 years. CONCLUSION: Willems' method led to differences between CA and AE that were acceptable for clinical and forensic practice. CLINICAL RELEVANCE: Age estimation may guide clinical decisions based on treatment timing. Validating international tools is necessary to promote evidence-based practice and country-specific application. This study overcame the limitations of previous research to provide a more realistic perspective of the performance of age estimation methods in Brazilian children. Willems' method had a superior performance compared to Demirjian's method and led to outcomes that were better than most studies with the Brazilian population.

Ameloblastoma Differential Radiographic Findings in Children and Adolescents

ABSTRACT: The aim of this research was to investigate the radiographic, clinical, and histological features of cases of ameloblastoma from a period of 17 years in a Brazilian center and to explore potential differences in children and adolescen ts in relation to adults. Seventy-five patients diagnosed with ameloblastoma from 2001 to 2018 were included. Data from each patient including gender, age, histologic type, location, and radiographic characteristics were reviewed and analyzed retrospectively. The association between the clinical, radiographic, and histologic findings was investigated. No differences regarding the histological pattern of the lesions were observed between groups. Children and adolescents presented well- defined lesions associated with an unerupted tooth compared to adults (p<0.05). The presence of an unerupted tooth was associated with cortical erosion and expansion and MC displacement (p<0.05). Despite similar histologic characteristics, differential radiographic appearance was observed between young patients and adults.

RESUMEN: El objetivo de este trabajo fue investigar las características radiográficas, clínicas e histológicas de casos de ameloblastoma en un período de 17 años, en un centro brasileño y explorar las posibles diferencias en niños y adolescentes en relación con los adultos. Se incluyeron 75 pacientes diagnosticados con ameloblastoma desde 2001 hasta 2018. Los datos de cada paciente, incluyendo el sexo, la edad, el tipo histológico, la ubicación y las características radiográficas, se revisaron y analizaron retrospectivamente. Se investigó la asociación entre los hallazgos clínicos, radiográficos e histológicos. No se observaron diferencias en cuanto al patrón histológico de las lesiones entre los grupos. Los niños y adolescentes presentaron lesiones bien definidas asociadas a un diente no erupcionado en comparación con los adultos (p<0,05). La presencia de un diente no erupcionado se asoció con erosión y expansión cortical y desplazamiento de MC (p<0,05). A pesar de las características histológicas similares, se observó una apariencia radiográfica diferente entre pacientes jóvenes y adultos.

Assessment of cone beam computed tomography for determining position and prognosis of interradicular mini-implants

ABSTRACT Objective: To investigate the influence of dynamic visualization of cone beam computed tomography (CBCT) scans on orthodontist's assessment of positioning status and prognosis of interradicular mini-implants (MI). Methods: Three MI positions were virtually simulated in thirty CBCT volumes: (1) MI 1 mm from the lamina dura (LD), (2) MI touching the LD and (3) MI overlapping the LD. Each position was exposed to orthodontists (n = 35) as panoramic reconstruction, sagittal reconstruction and a sequence of axial slices. Each orthodontist evaluated the MI position (relationship with the LD) and scored the prognosis using a four-point scale (the higher the score, the better the prognosis). Kappa, Friedman and Nemenyi statistics were used. Results: Statistically significant associations were detected between the prognosis scores and the type of image visualized (p<0.05). The dynamic visualization of the CBCT volume (axial slices) was associated with higher scores for prognosis and more reliable evaluation of MI positioning. Inconsistent outcomes were more frequently associated with panoramic and sagittal reconstructions. Conclusion: The dynamic visualization of axial slices allowed orthodontists to perform better assessment of MI position and considerably affected prognosis judgment.

RESUMO Objetivo: Analisar se a avaliação dinâmica de volumes de tomografia computadorizada de feixe cônico (TCFC) influencia a percepção de ortodontistas quanto à determinação da posição e do prognóstico de mini-implantes (MIs) inter-radiculares. Material e Métodos: Foram selecionados 30 volumes de TCFC, nos quais foram simuladas três formas de instalação de MIs: 1) MI a 1 mm de distância da lâmina dura (LD); 2) MI tocando a LD; e 3) MI sobreposto à LD. As imagens foram examinadas por 35 ortodontistas na forma de reconstruções panorâmicas, reconstruções sagitais e uma sequência de reconstruções axiais. Os examinadores avaliaram a relação entre o MI e a LD, e indicaram o prognóstico dos MIs instalados, usando uma escala de 4 pontos (quanto maior o escore, mais favorável o prognóstico). Os dados foram submetidos à análise estatística, por meio dos testes de Kappa, Friedman e Nemenyi. Resultados: Houve associação significativa entre o prognóstico, os tipos de imagem e as três formas de inserção dos MIs (p<0,05). A visualização dinâmica dos volumes de TCFC (reconstruções axiais) foi associada a maiores escores para o prognóstico e a avaliações mais confiáveis da posição dos MIs. Escores mais inconsistentes e discordantes foram mais associados às reconstruções panorâmicas e sagitais. Conclusão: A análise do volume tomográfico em reconstruções axiais pode melhorar a avaliação do ortodontista quanto à posição dos MIs inter-radiculares, apresentando impacto significativo na determinação do prognóstico do caso.

Dosimetric evaluation for temporomandibular joint cone beam computed tomography exams using different field of view.

Objectives.To optimize the absorbed organ dose in relation to the field of view for temporomandibular joint examinations in four cone beam computed tomography devices.Methods.An anthropomorphic adult head and neck phantom, and 192 LiF dosimeters (TLD-100) were used. The dosimeters were placed in the region corresponding to the lens, parotid glands, submandibular glands, and thyroid. Small, medium and large FOVs were selected on Orthopantomograph OP300 Maxio, PaX-i3D Smart, ORTHOPHOS XG, and i-CAT Next Generation device when it was possible.Results.A wide range of absorbed dose values was recorded for all organs due to the different exposure parameters of each device. The radiosensitive organ with the highest dose was the parotid glands. The devices with 5 × 5 cm FOV recorded a lower dose in this protocol, while for the device without a small FOV (≤5 × 5 cm), the lowest dose was observed with the large FOV (6 × 16 cm).Conclusions.We recommend a double exposure with an FOV of 5 × 5 cm in the OP300 Maxio, PaX-i3D Smart, and ORTHOPHOS XG device, while in the i-CAT Next Generation device, a single exposure FOV of 6 × 16 cm is indicated.

Biosafety devices to control the spread of potentially contaminated dispersion particles. New associated strategies for health environments.

Dental procedures produce a large amount of spatter and aerosols that create concern for the transmission of airborne diseases, such as Covid-19. This study established a methodology with the objective of evaluating new associated strategies to reduce the risk of cross-transmission in a health environment by simulating spread of potentially contaminated dispersion particles (PCDP) in the environment. This crossover study, was conducted in a school clinic environment (4 clinics containing 12 dental chairs each). As a positive control group (without barriers), 12 professionals activated at the same time the turbine of dental drill, for one minute, with a bacterial solution (Lactobacillus casei Shirota, 1.5x108 CFU/mL), which had been added in the cooling reservoir of the dental equipment. In the experimental groups, the professionals made use of; a) an individual biosafety barrier in dentistry (IBBD) which consists of a metal support covered by a disposable PVC film barrier; b) a Mobile Unit of Disinfection by Ultraviolet-C, consisting of 8 UV lamps-C of 95W, of 304µW/cm2 of irradiance each, connected for 15 minutes (UV-C) and; c) the association between the two methods (IBBD + UV-C). In each clinic, 56 Petri dishes containing MRS agar were positioned on the lamps, benches and on the floor. In addition, plates were placed prior to each test (negative control group) and plates were also placed in the corridor that connects the four clinics. In the groups without barrier and IBBD + UV-C the passive air microorganisms in Petri dishes was also evaluated at times of 30, 60, 90 and 120 minutes after the end of the dental's drill activation. The mean (standard deviation) of CFU of L. casei Shirota for the positive control group was 3905 (1521), while in the experimental groups the mean using the IBBD was 940 (466) CFU, establishing a reduction on average, of 75% (p<0.0001). For the UV-C group, the mean was 260 (309) CFU and the association of the use of IBBD + UV-C promoted an overall average count of 152 (257) CFU, establishing a reduction on average of 93% and 96%, respectively (p<0.0001). Considering these results and the study model used, the individual biosafety barrier associated with UV-C technology showed to be efficient strategies to reduce the dispersion of bioaerosols generated in an environment with high rate of PCDP generation and may be an alternative for the improvement of biosafety in different healthy environment.