Chairs:
jennifer christensen
spyros damaskos

7: COMPARISON OF THE AERODYNAMIC CHARACTERISTICS OF THE UPPER AIRWAY BETWEEN CHINESE AND DUTCH OBSTRUCTIVE SLEEP APNEA PATIENTS

H. Chen1, X. Shi2,3, D. Zhou4, F. Lobbezoo3, P. van der Stelt2, S. Ge5, G. Aarab3

1Shandong University, Department of orthodontics, Jinan, China, 2Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Department of Oral Radiology, Amsterdam, Netherlands, 3Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Department of Orofacial Pain and Dysfunction, Amsterdam, Netherlands, 4Shandong University, School of Chemistry and Chemical Engineering,, Jinan, China, 5Shandong University, Department of Periodontics, Jinan, China

Aims: The primary aim is to compare the aerodynamic characteristics of the upper airway, such as airway resistance (R) between Chinese and Dutch OSA patients.

Methods: In China, the participants were recruited from the sleep center of dental school of Shandong University. In The Netherlands, the participants were recruited from OLVG in Amsterdam. The diagnosis of OSA patients was based on an overnight polysomnographic recording. NewTom5G cone beam computed tomography (CBCT) scans were obtained from both Chinese and Dutch OSA patients. Computational models of the oropharynx were reconstructed based on CBCT images. The aerodynamic characteristics of the oropharynx were calculated based on these computational models.

Results: A total of 27 Dutch adults (mean age ± SD of 46.0 ± 14.1 years, body mass index [BMI] of 26.8 ± 3.5 kg/m2, and apnea-hypopnea index [AHI] of 15.8 ± 7.2 events/h) and 24 Chinese adults (age 41.5 ± 13.0 years, BMI 26.8 ± 3.5 kg/m2, and AHI 16.8 ± 8.0 events/h). There were no significant differences in AHI, age, BMI, and sex between the two groups (P = 0.18–0.99). There was no significant difference in the aerodynamic characteristics of the upper airway of both groups was not significantly different (P = 0.16-0.96).

Conclusion: Within the limitations of this study, no significant difference was found in the aerodynamic characteristics of the upper airway between Dutch and Chinese patients with mild to moderate OSA. The race plays similar role in the aerodynamic characteristics of the upper airway between Dutch and Chinese OSA patients.

18: UNVEILING OROPHARYNGEAL AIRWAY CHARACTERISTICS IN ORAL SUBMUCOUS FIBROSIS : A CROSS-SECTIONAL STUDY EMPLOYING THREE-DIMENSIONAL VOLUMETRIC ANALYSIS

A.B. George1, K. Agarwal1

1SCB Dental College and Hospital, Oral Medicine and Maxillofacial Radiology, Cuttack, India

Aim: Oropharyngeal airway is compromised in Oral Submucous Fibrosis (OSMF) patients resulting from submucosal fibrosis involving the faucillar pillars, pharynx and the pyriform fossae. An assessment and correlation of oropharyngeal airway space dimensions in varying stages of OSMF patients based on semiautomatic segmentation of DICOM data obtained from CBCT volumetric scans could assist surgeon’s assessment prior to surgical procedures.

Materials and Methods: Patients were categorized into varying groups as per the OSMF clinical staging criteria according to Haider et al. CBCT data sets for volumetric airway assessment were obtained for the cases. For the semi-automatic segmentation process, image segmentation was performed using ITK-SNAP, employing an interactive threshold technique assisted by a region-growing algorithm. The assessment of intra- and inter-examiner variability was conducted using Bland-Altman analysis. The data were subjected to further statistical analysis like ANOVA correlation tests and Regression analysis were performed on the data.

Results: Concerning interrater variability, the Bland-Altman- Analysis showed that there were no variations between the estimation of pharyngeal volumes by the examiners. Data analysis showed significant decreasing volumes of airway with increasing severity grades of OSMF.

Conclusion: A novel method of approximating the pharyngeal airway volume can be advocated using data obtained from CBCT scans of OSMF patients This can provide us with a noninvasive tool for pre-anesthetic evaluation and also for estimation of risks of obstructive sleep apneas in OSMF patients.

23: FEASIBILITY OF FROZEN SOFT TISSUES TO SIMULATE FRESH SOFT TISSUE CONDITIONS IN FOUR CONE BEAM COMPUTED TOMOGRAPHY (CBCT) UNITS

M.L. Oliveira1,2, M.M. Bornstein2, D. Dagassan-Berndt2,3

1Piracicaba Dental School, University of Campinas, Oral Diagnosis, Piracicaba, Brazil, 2University Center for Dental Medicine Basel UZB, University of Basel, Oral Health & Medicine, Basel, Switzerland, 3University Center for Dental Medicine Basel UZB, University of Basel, Center for Dental Imaging, Basel, Switzerland

Aim: To assess and compare the feasibility of using frozen soft tissues to simulate fresh soft tissues in pig mandibles across four cone beam computed tomography (CBCT) units.

Material and Methods: Two fresh pig mandibles with soft tissues, each containing two tubes filled with a radiopaque homogeneous solution, were scanned using two field-of-view sizes and four CBCT units: 3D Accuitomo 170 (Morita, Kyoto, Japan), Axeos (Dentsply Sirona, Charlotte, North Carolina, USA), ProMax 3D Max (Planmeca, Helsinki, Finland), and X800 (Morita). Subsequently, the pig mandibles were deep-frozen and scanned again. Three cross sections were exported from each CBCT volume and grouped into pairs, with one cross-section representing a fresh mandible and the other a frozen mandible. Three radiologists compared the pairs and assigned scores to assess the relative image quality using a 5-point scale. Mean gray values and standard deviation were obtained from homogeneous areas in the tubes and subjected to Pearson correlation analysis between fresh and frozen physical states per CBCT unit.

Results: All CBCT units revealed similarity of the CBCT image quality between fresh and frozen states. In general, the distribution of mean gray values and noise was similar between fresh and frozen states irrespective of the CBCT unit. Mean gray values exhibited positive and strong correlations between fresh and frozen states. Additionally, in general, noise values exhibited positive and moderate correlations.

Conclusion: The freezing of pig mandibles with soft tissues may serve as a method to extend their usability and durability, regardless of the CBCT unit.

50: INFLUENCE OF CBCT FILTERS AND CONTRAST ADJUSTMENTS ON PERI-IMPLANT BUCCAL BONE THICKNESS MEASUREMENT AND BLOOMING EXPRESSION

S. Lins de-Azevedo-Vaz1, H. Nogueira Mello1, E. Alberti Bonadiman1, G. Lozer Bruneli1, G. Azevedo Pitol1, T.C. Rangel Pereira1

1Federal University of Espírito Santo, Vitória, Brazil

Aim: To assess whether filter and contrast adjustments can improve the accuracy of CBCT in measuring the buccal bone thickness (BBT) adjacent to dental implants by reducing blooming artefacts.

Material and Methods: Homogeneous bone blocks with peri-implant BBT of 0.3 mm, 0.5 mm, and 1 mm were imaged (Orthophos SL, Sirona). Three dentists measured the BBT in 234 CBCT scans under different settings of contrast adjustments and ‚Sharpen‘ filter activation; implant diameter was also measured to assess blooming artefact expression. The differences between tomographic and actual measurements were subjected to repeated measures ANOVA (α = 5%).

Results: The group with the thinnest BBT (0.3 mm) had the greatest deviation between tomographic and actual measurements (79.9% ± 29.0%). Conversely, the 0.5 mm (36.1% ± 38.4%) and 1 mm (29.4% ± 12.3%) groups exhibited lower deviation (p<0.05). ‹Sharpen› filter activation resulted in lower deviation for implant diameter (p<0.05) but did not influence BBT measurements (p>0.05). BBT and implant diameter measurements were not influenced by the contrast settings used (p>0.05).

Conclusion: Filter and contrast adjustments did not improve the accuracy of CBCT in measuring peri-implant BBT, while actual BBT influenced this task. Blooming artefacts were reduced using filter but not influenced by contrast adjustments.

58: DOES SUPPLEMENTAL INFORMATION FROM CONE BEAM CT CHANGE EXPECTED LONG-TERM PROGNOSIS FOR TEETH WITH EXTERNAL CERVICAL RESORPTION?

J. Suhr Villefrance1, A. Wenzel1, L.-L. Kirkevang1, M. Væth2, L.H. Matzen1

1Aarhus University, Department of Dentistry and Oral Health, Section for Oral Radiology and Endodontics, Aarhus C, Denmark, 2Aarhus University, Department of Public Health, Aarhus C, Denmark

Aim: To evaluate whether supplemental information from CBCT changes expected long-term prognosis for teeth with external cervical resorption (ECR) compared to intraoral images.

Materials and Methods: 194 patients (mean age 41.2 (range 13-81)) having 244 teeth with ECR were included. An initial expected long-term prognosis was established based on intraoral images (good/poor). Afterwards, the patients underwent CBCT, and the final expected long-term prognosis was decided. From the intraoral images and CBCT, ECR using Heithersay’s classification system (H-class 1/2/3/4; higher number indicates more severe ECR) and pulp involvement (yes/no) was assessed. Descriptive statistics evaluated changes in expected long-term prognosis after CBCT.

Results: Based on CBCT, the expected long-term prognosis was assessed to be poor for 173 teeth and good for 71 teeth. The long-term prognosis changed in 31.1% of the teeth after CBCT; 2.0% changed from a poor to a good long-term prognosis, and 29% changed from a good to a poor long-term prognosis. In 81 (33.2%) teeth H-class increased, and in ten teeth H-class decreased in CBCT. In 70 (28.7%) teeth, there was a change from no pulp involvement to involvement of the pulp after CBCT; eight teeth changed in the opposite direction. H-class 4, pulp involvement, ECR in the oral 1/3 of the root seen in CBCT, more than two surface lesions significantly influenced a poor long-term prognosis (p<0.05).

Conclusion: Supplemental information from CBCT changed expected long-term prognosis in almost one third of teeth with ECR. In most cases, the expected long-term prognosis changed from good to poor.