Micromorphology of the Dental Pulp Is Highly Preserved in Cancer Patients Who Underwent Head and Neck Radiotherapy Karina Morais Faria, DDS, MSc,* Thais Bianca Brand~ ao, DDS, MSc, † Ana Carolina Prado Ribeiro, DDS, PhD, † Adriele Ferreira Gouv^ ea Vasconcellos, DDS, PhD, † Icaro Thiago de Carvalho, MD, ‡ Fernando Freire de Arruda, MD, ‡ Gilberto Castro Junior, MD, PhD, § Vanessa Cristina Gross, DDS,* Oslei Paes Almeida, DDS, PhD,* Marcio Ajudarte Lopes, DDS, PhD,* and Alan Roger Santos-Silva, DDS, PhD* Abstract Introduction: Teeth are often included in the radiation field during head and neck radiotherapy, and recent clin- ical evidence suggests that dental pulp is negatively affected by the direct effects of radiation, leading to impaired sensitivity of the dental pulp. Therefore, this study aimed to investigate the direct effects of radiation on the microvasculature, innervation, and extracellular matrix of the dental pulp of patients who have under- gone head and neck radiotherapy. Methods: Twenty- three samples of dental pulp from patients who finished head and neck radiotherapy were analyzed. Samples were histologically processed and stained with hematoxylin-eosin for morphologic evaluation of the microvasculature, innervation, and extracellular matrix. Subsequently, immunohistochemical analysis of proteins related to vascularization (CD34 and smooth muscle actin), innervation (S-100, NCAM/CD56, and neurofila- ment), and extracellular matrix (vimentin) of the dental pulp was performed. Results: The morphologic study identified preservation of the microvasculature, nerve bundles, and components of the extracellular matrix in all studied samples. The immunohistochemical analysis confirmed the morphologic findings and showed a normal pattern of expression for the studied proteins in all sam- ples. Conclusions: Direct effects of radiotherapy are not able to generate morphologic changes in the microvascu- lature, innervation, and extracellular matrix components of the dental pulp in head and neck cancer patients. (J En- dod 2014;-:1–7) Key Words Cancer, dental pulp, radiation caries, radiotherapy, side effects H ead and neck squamous cell carcinoma (HNSCC) is one of the most common types of cancer in many parts of the world and has a significant impact on the quality of life of affected patients (1). Because of its local and regional pattern of growth, HNSCC is mainly treated by the combination of surgery, radiotherapy, and chemotherapy (1). In addition to the high rates of tumor control, head and neck radiotherapy (HNR) is asso- ciated with a series of severe oral toxicities. The main acute side effects of HNR are mu- cositis, hyposalivation, dysphagia, and dysgeusia, whereas the main chronic side effects of HNR include hyposalivation, trismus, osteoradionecrosis, and radiation-related caries (2). During the medical planning of HNR, both tumor volume and normal anatomic structures of the maxillofacial region are included in the primary field of radiation (3). Thus, teeth often receive high doses of radiation during HNSCC treatment (4). Several in vitro studies analyzed the direct effects of radiation on the enamel and dentin and showed contradictory results regarding the negative impact of radiation on enamel dissolution, dentin collagen breakdown, and dentin bond strength (5–8). However, only a few previous studies attempted to investigate the direct effects of radiation on the dental pulp, most of which were based on animal experimental models and obsolete radiation techniques (5, 7, 9). Hence, there is great diversity of results when it comes to the ability of radiation to directly affect the dental pulp components (10–12) and to further impair pulp vascularization and innervation, leading to clinically detectable teeth sensitivity changes (13, 14). Additionally, recent studies suggested that radiogenic destruction of the dental pulp would be an important event for the etiology of radiation-related caries (13). Remarkably, there is recent clinical evidence that HNR is able to reduce innervation and vascularization of the dental pulp by decreasing the levels of oxygen saturation, eventually decreasing pulpal sensitivity and responses to thermal and electrical stim- uli (13, 14). Considering the fact that responses of the dental pulp to thermal and electrical stimuli are directly related to the mechanisms of inflammation, microvascularization, and innervation of the dental pulp and given the scarce number of previous studies that explored the morphology of dental pulp in HNSCC patients, the current study tested the null hypothesis that the direct effects of radiotherapy would not be able to generate From the*Oral Diagnosis Department, Semiology and Pathology Areas, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Sao Paulo, Brazil; and † Dental Oncology Service, ‡ Radiotherapy Service, and § Clinical Oncology Service, Instituto do C^ ancer do Estado de S~ ao Paulo (ICESP), Faculdade de Medicina da Universidade de S~ ao Paulo, S~ ao Paulo, Brazil. Address requests for reprints to Dr Alan Roger Santos-Silva, Av Limeira, 901, Bairro Are~ ao, Piracicaba, CEP 13414-903, Department of Oral Diagnosis, Semiology Area, Piracicaba Dental School University of Campinas, Sao Paulo, Brazil. E-mail address: alanroger@fop.unicamp.br 0099-2399/$ - see front matter Copyright ª 2014 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2014.07.006 Clinical Research JOE — Volume -, Number -, - 2014 Micromorphology of the Dental Pulp and HNR 1