Sara Rezapour , Mehrab Deylami, Marjan Kazeminia,
Volume 82, Issue 7 (October 2024)
Abstract
Background: The mandibular first molar teeth are the most common teeth that undergo endodontic treatment and are anatomically very challenging. Adequate knowledge of the danger zone in the mesial root of the first mandibular molars helps reduce the risk of misdiagnosis of perforation during treatment. The aim of this study was to compare the dentin thickness of the danger zone in the mesial canals of the mandibular first molar in CBCT(Cone Beam Coomputed Tomography) images at intervals of 3, 4, 5 mm below the orifice canal.
Methods: In this study, CBCT images of 144 mandibular first molars from 74 patients aged 18 to 66 years were examined. Mean orifice to Furcation was calculated and mean distal dentin thickness of mesiobuccal and mesiolingual canals was measured at 3, 4 and 5 mm below the orifice. The mean thickness of the distal dentin was examined in terms of age, sex and maxillary side.
Results: The lowest mean distal wall thickness of mesiobuccal and mesiolingual canals was 5 mm below the orifice of the canal. The mean distal wall thickness of mesiobuccal and mesiolingual canals were higher in men than women (P <0.05). The mean distal wall thickness did not show a significant relationship with age. (P=0.745) except in the area of 3 and 5 mm below the orifice in the mesiobuccal canal which was significantly associated with age (P=0.01). No statistically significant difference was observed between the two mandibular sides (P=0.543) except in the 4 mm area below the orifice in the mesiolingual canal (P <0.05).
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Conclusion: The present study showed that the danger zone is observed in the distal dentin of the mesiobuccal and mesiolingual canals of the mandibular first molar teeth in men and women 5 mm below the orifice of the canal. The mean dentin thickness of the distal wall was lower in women than in men.
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Reza Ghalehtaki, Mahdieh Razmkhah, Ali Kazemian, Mostafa Farzin, Samaneh Salarvand, Kasra Kolahdouzan, Ehsan Saraee,
Volume 82, Issue 10 (January 2025)
Abstract
Background: Gliomas are the most common primary brain tumors in adults, with low-grade gliomas making up 15% of cases. These slow-growing tumors often occur in young adults. Radiotherapy is one of the treatment options. New radiotherapy techniques like IMRT may reduce complications by sparing normal tissue. The study aims to determine which tumors benefit most from IMRT based on tumor location and size.
Methods: Patients diagnosed with low-grade glioma who were referred for treatment at the Cancer Institute of Imam Khomeini Hospital between September 2017 and September 2020 were included in this study. All patients underwent CT simulation with a thermoplastic mask for immobilization. A diagnostic MRI (performed within two weeks prior) was fused with the planning CT to define the target volume (GTV/CTV), with contours verified by a neuroradiologist. A doctor outlines the treatment volume and critical organs for both 3D and IMRT techniques. Radiotherapy physics experts design treatment plans using both techniques, which are then approved by a radiation oncologist. The treatment volume coverage and doses to critical organs are compared between the two techniques.
Results: Among 25 patients, 14 patients (56%) with single-lobe involvement, 7 (28%) with two lobes, and 4 (16%) with multifocal disease. Right-side brain involvement was seen in 32%, with the frontal lobe most affected. IMRT significantly reduced the mean and maximum cochlear dose on the treatment side in all patients. It also lowered the mean chiasma dose in those with both lobes involved and reduced cochlear dose on the opposite side in frontal lobe cases. No significant difference was found between the techniques for patients with multiple lobe involvement.
Conclusion: According to our study on 25 patients with low-grade glioma, it was shown that there is no clear difference between the two techniques. Given the young age and long survival of LGG patients, IMRT may be preferred when hearing preservation is a priority. Further studies with larger cohorts are needed to confirm these findings.
