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    Determination and classification of intraoral phosphor storage plate artifacts and errors
    (Korean Acad Oral & Maxillofacial Radiology, 2019) Deniz, Yesim; Kaya, Seher
    Purpose: The aim of this study was to determine the reasons and solutions for intraoral phosphor storage plate (PSP) image artifacts and errors, and to develop an appropriate classification of the artifacts. Materials and Methods: This study involved the retrospective examination of 5,000 intraoral images that had been obtained using a phosphor plate system. Image artifacts were examined on the radiographs and classified according to possible causative factors. Results: Artifacts were observed in 1,822 of the 5,000 images. After examination of the images, the errors were divided into 6 groups based on their causes, as follows: images with operator errors, superposition of undesirable structures, ambient light errors, plate artifacts (physical deformations and contamination), scanner artifacts, and software artifacts. The groups were then re-examined and divided into 45 subheadings. Conclusion: Identification of image artifacts can help to improve the quality of the radiographic image and control the radiation dose. Knowledge of the basic physics and technology of PSP systems could aid to reduce the need for repeated radiography.
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    Evaluation of the Effectiveness of Polyether Silicone-based and Polyvinyl Siloxane Dental Impression Materials for Shielding Scattered Radiation During Radiotherapy
    (Galenos Publ House, 2023) Deniz, Yesim; Aktas, Cagatay; Acar, Ezgi Isiktas
    Objective: Radiation-induced oral mucositis is a major problem associated with radiotherapy. This study aimed to investigate the effectiveness of polyether silicone-based (PE) and polyvinyl siloxane (PVS) impression materials in protecting adjacent tissues from radiation scattered from dental materials.Materials and Methods: Amalgam, zirconium, and titanium dental material specimens were covered with 5 mm PE and PVS in the study group. The dental materials were placed in a linear accelerator device at a distance of 100 cm from the radiation source and coincided with a field size of 15x15 mm. Samples placed perpendicular to the central beam were irradiated with 6 MV photons at a fractional daily therapeutic radiation dose of 2 Gy. Thermoluminescent dosimeters (TLD-100) placed 90 degrees lateral to the specimens were used to record the scattered dose data. In the control group, uncovered dental materials were irradiated, and scattered doses were measured by TLD. The TLD data of the study and control groups were compared by independent t-test to analyze the shielding effect of PE and PVS. In addition, the photon stopper properties of PE and PVS were compared. The photon interaction parameters and effective atomic numbers of dental materials were calculated.Results: It was calculated that the PE and PVS significantly prevent the dose enhancement caused by dental materials (p<0.05). There was no difference between impression materials in the photon-stopping properties (p>0.05).Conclusion: PE and PVS can be used as scatter dose shields for the 2 Gy daily fractional dose. This study demonstrates the radiation-shielding properties of PE for the first time.
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    Investigation of Dosage Distributions of Polyvinyl Siloxane Dental Impression Shields for Head and Neck Radiotherapy with Thermoluminances Dosimeters
    (Marmara Univ, Inst Health Sciences, 2023) Ulusoy, Habibe Ozturk; Deniz, Yesim; Aktas, Cagatay; Aygun, Esma Basak Gull
    Objective: This study aimed to assess the effects of denture materials on dose distribution on a head and neck radiotherapy-appropriate model and calculate the thickness of a stent by polyvinyl siloxane dental impression material for shielding scattered radiation from dental restorations. Methods: In the first step of the study, 5mm diameter and 5mm height of cylindrical dental material of titanium, zirconia lithium disilicate were irradiated with 6-Megavoltage photons from a clinical linear accelerator. In the second step, dental materials at the center of polyvinyl siloxane thicknesses of 5, 10, and 20mm were irradiated with 2 Gray and 10 Gray fractional doses. Measurements were made using three thermoluminescent dosimeters positioned laterally. The percentage backscattered dose and percentage dose decrease values were calculated Results: According to the result, dosages scattered from dental materials increased for samples irradiated with 2Gy; a decreased dose was reported for samples irradiated with a 10Gy. 5mm PVS samples provided higher dose attenuation than others. Regardless of dental material, it is seen that the attenuation intensities calculated from TLD-100 dosimeters ranged from 22.7 to 38,62 for 2Gy, and 10.01 to 38,87 for 10Gy. Conclusion: Dental material alters the scattered radiation. In irradiated head and neck cancer patients, a 5mm thick guard is sufficient to prevent radiation diffused from dental materials in clinical usage.
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    Students' Perceptions About the Instructors' Competence in Technology-supported Courses at Dental Faculty: A Cross-sectional Study
    (Galenos Publ House, 2023) Genc, Cigdem Cetin; Deniz, Yesim; Genc, Celal; Degirmenci, Alpin; Tosun, Ilgi
    Objective: The pandemic has highlighted the importance of technology-supported courses throughout the world. Evaluating the perceptions of students attending these courses is important to provide high-quality education Materials and Methods: This study was carried out on 1st, 2nd, and 3rd-grade dentistry students. The Student Perceptions Scale Regarding the Knowledge of Instructors in Technology - Supported Classrooms was applied to 207 dentistry students. This scale consists of four sub-dimensions: subject matter knowledge (SMK), technological knowledge (TK), knowledge of students' understanding (KSU), and technological pedagogical content knowledge (TPCK). Results: SMK, KSU, and TPCK sub-dimension scores did not significantly differ by gender (p>0.05). However, the mean TK score of females (3.55 +/- 0.47) was found to be significantly higher than that of males (3.28 +/- 0.59) (p=0.001). There was no statistically significant difference among the SMK, TK, KSU, and TPCK sub-dimension mean scores by age (p>0.05). There was a statistically significant difference in the mean scores of the SMK and KSU sub-dimensions by grade (p-values are p<0.001 and p=0.015 respectively). The mean TK and TPCK sub-dimension scores yielded no significant difference by grade (p-values are p=0.368 and p=0.050 respectively). Conclusion: Measuring the quality of technology-assisted teaching and the instructor's TPCK from the student's perspective and determining student perceptions will provide accurate data on the long-term quality of education.
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    The impact of remineralization agents on dental bleaching efficacy and mineral loss in bleached enamel
    (Wiley, 2022) Misilli, Tugba; Carikcioglu, Burak; Deniz, Yesim; Aktas, Cagatay
    This study evaluated the effect of remineralization agents on bleaching efficiency, enamel mineral changes, and post-bleaching color stability. A total of 112 enamel-dentin blocks were prepared from bovine teeth. Following initial color measurements, separate treatment regimens were carried out as follows: negative control (no treatment); positive control (bleaching only); bleaching, then NaF; bleaching + NaF (mix); bleaching, then CPP-ACPF; bleaching + CPP-ACPF (mix); bleaching, then nHAP+F; bleaching + nHAP+F (mix). Color measurements were repeated after immersion in distilled water for 7 days, and again after staining with coffee solution for 14 days. The CIELAB-based whiteness index was used to evaluate bleaching efficiency, and the CIEDE2000 color difference formula for color stability. Chemical investigation was performed using scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analyses. The experimental groups showed significant increases in whiteness compared to the negative control, and the staining after bleaching did not result in statistically significant differences between the groups. Energy dispersive spectroscopic analysis revealed that bleaching protocols had no impact on elemental levels as well as the ratio of Ca/P. The combined use of bleaching agents with remineralization agents did not affect bleaching effectiveness but also did not provide an additional contribution.
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    The usefulness of ultrasonography as a dynamic measurement system for visualizing root canal working length: an in vivo study
    (BMC, 2024) Eren, Irem; Deniz, Yesim
    ObjectiveAlthough apex locators are generally effective tools for determining root canal working length, they may produce inaccurate results in some cases. The present study aimed to evaluate the efficacy of ultrasonography as an alternative method for measuring root canal length.Materials and methodsForty-seven anterior teeth with apical lesions were selected for the study. Initially, an electronic apex locator was used to measure the working length. Subsequently, ultrasonography was employed to visualize the root apex and determine the working length. During ultrasound imaging, a K-file No. 15 was inserted into the root canal until its tip was visible on the ultrasound monitor. Measurements obtained from both methods were compared using an independent sample t-test. Correlations were assessed with the Pearson correlation coefficient, and agreement was determined using the Bland-Altman plot.ResultsThe mean working canal length was 19.9 mm for the apex locator and 20.6 mm for the ultrasonography-guided method. No significant differences were observed between the data obtained using the apex locator method and the data obtained using the ultrasonography guidance method. Furthermore, a high level of agreement was identified between the two techniques.ConclusionUltrasonography can be used to visualize the apex effectively and determine canal length, especially when canal length determination is uncertain for various reasons.