acta med nicomedia Acta Medica Nicomedia 2717-8994 2717-8994 Kocaeli Üniversitesi 10.53446/actamednicomedia.1850118 Radiobiology Radyobiyoloji İNSAN DENTAL SERT DOKULARINDA TEK FRAKSİYONLU FOTON IŞINLAMASININ MİKRO-YAPISAL ETKİLERİ: YÜKSEK ÇÖZÜNÜRLÜKLÜ MİKRO-BT ÇALIŞMASI MICROSTRUCTURAL EFFECTS OF SINGLE-FRACTION PHOTON IRRADIATION ON HUMAN DENTAL HARD TISSUES: A HIGH-RESOLUTION MICRO-CT STUDY https://orcid.org/0000-0001-6423-8956 Ceylan Cemile MedikalPark İstanbul Onkoloji Hastanesi https://orcid.org/0000-0002-0106-7683 Çağlar Mustafa İSTANBUL MEDİPOL ÜNİVERSİTESİ, SAĞLIK BİLİMLERİ YÜKSEKOKULU https://orcid.org/0000-0003-3284-6169 Demirkan İrem BAHCESEHIR UNIVERSITY, FACULTY OF ENGINEERING https://orcid.org/0009-0008-6268-466X Kara İlkay İSTANBUL MEDİPOL ÜNİVERSİTESİ, SAĞLIK BİLİMLERİ YÜKSEKOKULU https://orcid.org/0000-0002-8723-885X Türe Osman Artunç MedikalPark İstanbul Onkoloji Hastanesi https://orcid.org/0009-0007-5213-8625 Serdengeçti Safiye ISTANBUL MEDIPOL UNIVERSITY, RESEARCH CENTER FOR HEALTH SCIENCES AND TECHNOLOGIES https://orcid.org/0000-0003-1545-5588 Özçakır Ceyda YEDİTEPE ÜNİVERSİTESİ, DİŞ HEKİMLİĞİ FAKÜLTESİ 03 06 2026 9 1 9 12 27 2025 01 19 2026 Copyright © 2020, Acta Medica Nicomedia 2020 Acta Medica Nicomedia

Amaç: Bu çalışmanın amacı, tek fraksiyonlu ışınlama sonrası insan diş sert dokularında meydana gelen mikro-yapısal değişiklikleri yüksek çözünürlüklü mikro-bilgisayarlı tomografi (mikro-BT) kullanarak incelemek ve düzleştirilmiş (flattening filter, FF) ve düzleştirme filtresiz (flattening filter-free, FFF) foton ışınları arasında olası farkları değerlendirmektir. Yöntem: Çalışmaya çürüksüz ve restorasyonsuz 16 adet çekilmiş insan üçüncü molar dişi dahil edildi. Tüm örnekler ışınlama öncesinde başlangıç mikro-BT görüntülemesine tabi tutuldu. Dişler daha sonra tek fraksiyonda 20 Gy doz alacak şekilde 6 MV FF (600 cGy/MU) veya 6 MV FFF (1400 cGy/MU) foton ışınları ile ışınlandı. Işınlama sonrası mikro-BT görüntüleri aynı görüntüleme parametreleri kullanılarak elde edildi. Kemik hacmi (BV), toplam hacim (TV), kemik hacim oranı (BV/TV), kemik yüzeyi (BS), özgül kemik yüzeyi (BS/BV), kemik mineral yoğunluğu (BMD), trabeküler kalınlık (Tb.Th) ve trabeküler ayrım (Tb.Sp) ışınlama öncesi ve sonrası karşılaştırıldı. Bulgular: Işınlama sonrası BV/TV oranında anlamlı azalma ve BS ile BS/BV parametrelerinde anlamlı artış saptandı (p < 0.05). Buna karşın BV, TV, BMD, Tb.Th ve Tb.Sp parametrelerinde anlamlı değişiklik gözlenmedi. FF ve FFF ışınları arasında hiçbir mikro-BT parametresi açısından istatistiksel olarak anlamlı fark bulunmadı. Sonuç: Tek fraksiyon 20 Gy ışınlama, diş sert dokularında hacim kaybından ziyade yüzey ve mikro-mimari düzeyde erken değişikliklere yol açmaktadır. FF ve FFF foton ışınları arasındaki doz hızı farkı, eşdeğer doz koşullarında mikro-BT ile saptanabilir ek bir etki oluşturmamıştır. Bu bulgular, klinikte FFF ışınlarının güvenli kullanımını desteklemektedir.

Objective: This study aimed to investigate microstructural changes in human dental hard tissues following single-fraction irradiation using high-resolution micro-computed tomography (micro-CT), with particular emphasis on potential differences between flattening filter (FF) and flattening filter-free (FFF) photon beam modalities. Methods: Sixteen extracted, non-carious human third molar teeth were included. All samples underwent baseline micro-CT imaging prior to irradiation. Teeth were then irradiated with 20 Gy in a single fraction using either 6 MV FF (600 cGy/MU) or 6 MV FFF (1400 cGy/MU) photon beams. Micro-CT images following irradiation were obtained with identical imaging conditions. Changes in bone volume (BV), total volume (TV), bone volume fraction (BV/TV), bone surface (BS), specific bone surface (BS/BV), bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were measured before and after irradiation. Results: Irradiation resulted in a substantial decrease in BV/TV and increases in BS and BS/BV (p < 0.05), suggesting micro-architectural remodeling and enhanced surface irregularity. No significant changes were detected in BV, TV, BMD, Tb.Th, or Tb.Sp. Comparison between FF and FFF beam modalities revealed no statistically significant differences in any micro-CT-derived parameter. Conclusion: Single-fraction 20 Gy irradiation induces early microstructural alterations in dental hard tissues characterized by changes in surface-related parameters rather than bulk mineral loss. Dose-rate differences between FF and FFF photon beams did not result in detectable micro-CT differences, supporting the clinical use of FFF beams at equivalent doses.

 Micro-computed tomography Dental hard tissues Radiotherapy Mikro-bilgisayarlı tomografi Diş Sert Dokusu Radyoterapi Karaca Y, Beauvois S, Paesmans M, et al. Retrospective study evaluating dental side effects of radiotherapy in patients treated for head and neck cancer. J Stomatol Oral Maxillofac Surg. 2024;125(3). doi:10.1016/j.jormas.2024.101858 Gupta N, Pal M, Rawat S, et al. Radiation-induced dental caries, prevention and treatment - A systematic review. Natl J Maxillofac Surg. 2015;6(2):160. doi:10.4103/0975-5950.183870 Goh EZ, Beech N, Johnson NR, Batstone M. The dental management of patients irradiated for head and neck cancer. Br Dent J. 2023;234(11):800-804. doi:10.1038/s41415-023-5864-z Sroussi HY, Epstein JB, Bensadoun RJ, et al. Common oral complications of head and neck cancer radiation therapy: mucositis, infections, saliva change, fibrosis, sensory dysfunctions, dental caries, periodontal disease, and osteoradionecrosis. Cancer Med.Blackwell Publishing Ltd. 2017;6(12):2918-2931. doi:10.1002/cam4.1221 Tamahara T, Kouketsu A. Direct radiation damage to human tooth under IMRT for head and neck cancer: physicochemical evidence supporting a non-salivary mechanism for radiation-related caries. Radiat Environ Biophys. Published online 2025. doi:10.1007/s00411-025-01180-w Bhandari S, Soni BW, Jamwal A, Ghoshal S. Oral and dental care before radiotherapy: Guidelines and development of a time-bound protocol. Indian J Cancer.Wolters Kluwer Medknow Publications. 2022;59(2):159-169. doi:10.4103/ijc.IJC_871_20 Tham JLM, Ng SP, Khor R, et al. Stereotactic Body Radiotherapy in Recurrent and Oligometastatic Head and Neck Tumours. J Clin Med.Multidisciplinary Digital Publishing Institute (MDPI). 2024;13(11). doi:10.3390/jcm13113020 Patel RA, Lock D, Kim T, et al. Single Fraction Stereotactic Radiosurgery for Retreatment of Skull Base Recurrent Head and Neck Malignancies. Cureus. Published online May 1, 2017. doi:10.7759/cureus.1206 Santos TT, Mattos VS, Molena KF, et al. The effects of re-irradiation on the chemical and morphological properties of permanent teeth. Preprint posted online November 17, 2023. doi:10.21203/rs.3.rs-3613368/v1 Padala SR, Asikainen P, Ruotsalainen T, et al. Effects of irradiation in the mandibular bone loaded with dental implants. An experimental study with a canine model. Ultrastruct Pathol. 2021;45(4-5):276-285. doi:10.1080/01913123.2021.1962467 Kachelrieß M. Micro-CT. Mulder L, Koolstra JH, Van Eijden TMGJ. Accuracy of microCT in the quantitative determination of the degree and distribution of mineralization in developing bone. Acta radiol. 2004;45(7):769-777. doi:10.1080/02841850410008171 Erpaçal B, Adıgüzel Ö, Cangül S. The use of micro-computed tomography in dental applications. International Dental Research. 2019;9(2):78-91. doi:10.5577/intdentres.2019.vol9.no2.7 Nascimento BL, Soares P, Rached RN, Couto Souza PH, Alanis LRA, Souza EM. Microstructural and chemical characterization of radiation-induced carious dentin of teeth submitted to ionizing radiation as a head and neck cancer therapy. PLoS One. 2025;20(12 December). doi:10.1371/journal.pone.0337062 Gonçalves LMN, Palma-Dibb RG, Paula-Silva FWG, et al. Radiation therapy alters microhardness and microstructure of enamel and dentin of permanent human teeth. J Dent. 2014;42(8):986-992. doi:10.1016/j.jdent.2014.05.011 Gonçalves LMN, Palma-Dibb RG, Paula-Silva FWG, et al. Radiation therapy alters microhardness and microstructure of enamel and dentin of permanent human teeth. J Dent. 2014;42(8):986-992. doi:10.1016/j.jdent.2014.05.011 Kulchar R, Florin E, Celine M, Steven T S, Francis K M. Impact of topical fluoride agents on radiation-induced dentin hardness alterations: a laboratory study. Swiss Dent J. 2025;135(3):16-28. doi:10.61872/sdj-2025-03-02 Lieshout HFJ, Bots CP. The effect of radiotherapy on dental hard tissue-a systematic review. Clin Oral Investig. 2014;18(1):17-24. doi:10.1007/s00784-013-1034-z Schweyen R, Stang A, Wienke A, Eckert A, Kuhnt T, Hey J. The influence of dental treatment on the development of osteoradionecrosis after radiotherapy by modern irradiation techniques. Clin Oral Investig. 2017;21(8):2499-2508. doi:10.1007/s00784-017-2048-8 Timchenko E V., Timchenko PE, Volova LT, Rosenbaum AY, Kulabukhova AY. Analysis of tooth tissues using Raman spectroscopy. In: Journal of Physics: Conference Series. Vol 769. Institute of Physics Publishing; 2016. doi:10.1088/1742-6596/769/1/012047 Lu H, Zhao Q, Guo J, et al. Direct radiation-induced effects on dental hard tissue. Radiation Oncology. 2019;14(1). doi:10.1186/s13014-019-1208-1 Demirkan I, Yaprak G, Ceylan C, et al. Acoustic diagnosis of elastic properties of human tooth by 320 MHz scanning acoustic microscopy after radiotherapy treatment for head and neck cancer. Radiation Oncology. 2020;15(1). doi:10.1186/s13014-020-01486-7 Baz Çifci ŞB, Aras S, Hacımustafaoğlu F, Erdem E, Kheradmand N, Çağlar M. Early radiobiological effects of flattening filter (FF) and flattening filter-free (FFF) beams and the radioprotective role of melatonin in rat brain: a preclinical study. J Radiat Res. Published online December 23, 2025. doi:10.1093/jrr/rraf078 Yao L, Li Y, Fu D, et al. The damage and remineralization strategies of dental hard tissues following radiotherapy. BMC Oral Health. 2024;24(1). doi:10.1186/s12903-024-04561-7 dos Santos TT, Mattos VS, Molena KF, et al. The effects of re-irradiation on the chemical and morphological properties of permanent teeth. Radiat Environ Biophys. 2024;63(2):283-295. doi:10.1007/s00411-024-01068-1 Vissink, A.; Jansma, J.; Spijkervet, F.K.; Burlage, F.R.; Coppes, R.P. Oral sequelae of head and neck radiotherapy. Crit. Rev. Oral Biol. Med. 2003, 14, 199–212. Kulchar R, Florin E, Celine M, Steven T S, Francis K M. Impact of topical fluoride agents on radiation-induced dentin hardness alterations: a laboratory study. Swiss Dent J. 2025;135(3):16-28. doi:10.61872/sdj-2025-03-02 Buchanan GD, Gamieldien MY, Tredoux S, Uys A, Swanepoel NJ. Complications of head and neck radiotherapy: A dental perspective. Arch Oncol. 2019;25(2):19-21. doi:10.2298/AOO190320002B Chitapanarux I, Iamaroon A. Salivary glands and dental complications after radiotherapy for nasopharyngeal carcinoma. Annals of Nasopharynx Cancer. 2020;4:7-7. doi:10.21037/anpc-20-17