Commensal oral microbiota impacts ulcerative oral mucositis clinical course in allogeneic stem cell transplant recipients.

Oral mucositis (OM) is a complex acute cytotoxicity of antineoplastic treatment that affects 40-85% of patients undergoing hematopoietic stem-cell transplantation. OM is associated with prolonged hospitalization, increased extensive pharmacotherapy, need for parenteral nutrition, and elevated treatment costs. As OM onset relates to the mucosal microenvironment status, with a particular role for microbiota-driven inflammation, we aimed to investigate whether the oral mucosa microbiota was associated with the clinical course of OM in patients undergoing allogeneic hematopoietic stem-cell transplantation. We collected oral mucosa samples from 30 patients and analyzed the oral mucosa microbiota by 16S rRNA sequencing. A total of 13 patients (43%) developed ulcerative OM. We observed that specific taxa were associated with oral mucositis grade and time to oral mucositis healing. Porphyromonas relative abundance at preconditioning was positively correlated with ulcerative OM grade (Spearman ρ = 0.61, P = 0.028) and higher Lactobacillus relative abundance at ulcerative OM onset was associated with shortened ulcerative OM duration (P = 0.032). Additionally, we generated a machine-learning-based bacterial signature that uses pre-treatment microbial profiles to predict whether a patient will develop OM during treatment. Our findings suggest that further research should focus on host-microbiome interactions to better prevent and treat OM.

Digital Workflow for Producing Oral Positioning Radiotherapy Stents for Head and Neck Cancer.

Oral positioning radiotherapy stents are devices that protect healthy structures adjacent to the target volume of head and neck radiotherapy treatment, leading to reduced acute and chronic side effects. This study describes a digital workflow to produce an oral positioning radiotherapy stent and analyze its efficacy by measuring dosimetric variations with and without this stent. An oral positioning radiotherapy stent was created according to a digital workflow that included intraoral scanning, digital design, and 3D printing for a patient with squamous cell carcinoma of the tongue. The patient underwent computed tomography to evaluate radiotherapy treatment by intensity-modulated radiation therapy with and without the use of the 3D-printed oral stent. The use of a 3D-printed oral positioning radiotherapy stent is a feasible and reproducible technique that reduced the planning target volume and radiation doses delivered to the hard palate, right parotid gland, and left parotid gland by 42%, 21%, and 8.5%, respectively.

Extensive Oral Mucormycosis in a Transplanted Patient.

Mucormycosis is an invasive fungal disease caused by fungi from the Mucorales order that are found in the soil and decaying organic debris. Mucormycosis has been reported to be the third most common fungal disease in stem cell transplanted patients. The fungi have a tendency for vascular invasion, resulting in thrombi development, which decreases blood supply and leads to extensive tissue necrosis. Here, the authors present a patient of mucormycosis affecting the soft palate, oropharynx, and hypopharynx in a type II diabetic male patient who underwent allogeneic stem cell transplantation, and the authors further review the literature on oral mucormycosis for the last 10 years.

Mandibular destructive radiolucent lesion: The first sign of multiple myeloma.

The occurrence of a mandibular lesion as the first sign of multiple myeloma (MM) is uncommon. This report describes a case of MM diagnosed because of a mandibular lesion. A 62-year-old woman presented a destructive radiolucent lesion in the right mandibular ramus. The lesion caused rupture of the anterior cortical bone and extended from the retromolar area to the coronoid process. An incisional biopsy was performed. Histopathological examination revealed numerous pleomorphic plasma cells, some with binucleated nuclei. The tumor cells showed kappa light-chain restriction. Bone marrow biopsy showed findings of massive infiltration of neoplastic plasma cells, besides lesions in the vertebrae. The diagnosis of MM was established. The patient underwent autologous hematopoietic stem-cell transplantation. Currently, the patient is under regular follow up after 40 months of initial treatment. In conclusion, MM should be considered in the differential diagnosis of destructive mandibular lesions. Key words:Mandible, multiple myeloma, radiolucent lesion.

IMRT delivers lower radiation doses to dental structures than 3DRT in head and neck cancer patients.

BACKGROUND: Radiotherapy (RT) is frequently used in the treatment of head and neck cancer, but different side-effects are frequently reported, including a higher frequency of radiation-related caries, what may be consequence of direct radiation to dental tissue. The intensity-modulated radiotherapy (IMRT) was developed to improve tumor control and decrease patient's morbidity by delivering radiation beams only to tumor shapes and sparing normal tissue. However, teeth are usually not included in IMRT plannings and the real efficacy of IMRT in the dental context has not been addressed. Therefore, the aim of this study is to assess whether IMRT delivers lower radiation doses to dental structures than conformal 3D radiotherapy (3DRT). MATERIAL AND METHODS: Radiation dose delivery to dental structures of 80 patients treated for head and neck cancers (oral cavity, tongue, nasopharynx and oropharynx) with IMRT (40 patients) and 3DRT (40 patients) were assessed by individually contouring tooth crowns on patients' treatment plans. Clinicopathological data were retrieved from patients' medical files. RESULTS: The average dose of radiation to teeth delivered by IMRT was significantly lower than with 3DRT (p = 0.007); however, only patients affected by nasopharynx and oral cavity cancers demonstrated significantly lower doses with IMRT (p = 0.012 and p = 0.011, respectively). Molars received more radiation with both 3DRT and IMRT, but the latter delivered significantly lower radiation in this group of teeth (p < 0.001), whereas no significant difference was found for the other dental groups. Maxillary teeth received lower doses than mandibular teeth, but only IMRT delivered significantly lower doses (p = 0.011 and p = 0.003). Ipsilateral teeth received higher doses than contralateral teeth with both techniques and IMRT delivered significantly lower radiation than 3DRT for contralateral dental structures (p < 0.001). CONCLUSION: IMRT delivered lower radiation doses to teeth than 3DRT, but only for some groups of patients and teeth, suggesting that this decrease was more likely due to the protection of other high risk organs, and was not enough to remove teeth from the zone of high risk for radiogenic disturbance (>30Gy).

Radiation dose distribution in the teeth, maxilla, and mandible of patients with oropharyngeal and nasopharyngeal tumors who were treated with intensity-modulated radiotherapy.

BACKGROUND: The purpose of this study was to evaluate the distribution of the intensity-modulated radiotherapy (IMRT) dose delivered to the teeth, maxilla, and mandible. METHODS: The mean dose (Dmean) and maximum dose (Dmax) of radiation for the maxilla, mandible, and teeth of 63 patients with oropharyngeal (n = 44) or nasopharyngeal (n = 19) tumors were retrospectively evaluated. RESULTS: The posterior regions of the mandible received the highest doses, and the teeth received lower doses than the bones (maximum dose, p < .001; average dose, p < .001). The Dmax (p < .001) and Dmean (p < .001) depended on primary tumor location. The superior bones and teeth of patients with nasopharyngeal tumors received more radiation than those of patients with oropharyngeal tumors. CONCLUSION: A dose distribution map was generated based on the estimated doses received, which could allow prediction of the areas most affected by radiation and facilitate further correlations with dental complications after radiotherapy. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.

The Effects of Ionizing Radiation on the Oral Cavity.

AIM: The aim of this study is to present a literature review on the effects of the ionizing radiation from radiotherapy treatment on dental tissues. BACKGROUND: Among the effects of increasing global life expectancy and longevity of the teeth in the oral cavity, increasing rates of neoplastic diseases have been observed. One of the important treatment modalities for head and neck neoplastic diseases is radiotherapy, which uses ionizing radiation as the main mechanism of action. Therefore, it is essential for dentists to be aware of the changes in oral and dental tissues caused by ionizing radiation, and to develop treatment and prevention strategies. RESULTS: In general, there is still controversy about the effects of ionizing radiation on dental structures. However, qualitative and quantitative changes in saliva and oral microbiota, presence of oral mucositis and radiation-related caries are expected, as they represent the well-known side effects of treatment with ionizing radiation. Points that still remain unclear are the effects of radiotherapy on enamel and dentin, and on their mechanisms of bonding to contemporary adhesive materials. CONCLUSION: Ionizing radiation has shown important interaction with organic tissues, since more deleterious effects have been shown on the oral mucosa, salivary glands and dentin, than on enamel. CLINICAL SIGNIFICANCE: With the increasing number of patients with cancer seeking dental treatment before and after head and neck radiotherapy, it is important for dentists to be aware of the effects of ionizing radiation on the oral cavity.