Effects of 3-Dimensional Conformal or Intensity-modulated Radiotherapy on Dental Pulp Sensitivity during and after the Treatment of Oral or Oropharyngeal Malignancies Simony H. Kataoka, DDS, MDS,* Frank C. Setzer, DMD, PhD, MS, † Eduardo R. Fregnani, DDS, ‡ Oscar F. Pessoa, DDS, § Eudes Gondim, Jr, DDS, MDS, PhD, † and Celso L. Caldeira, DDS* Abstract Introduction: Radiation therapy (RT) of malignant tumors in the head and neck area may have damaging effects on surrounding tissues. The aim of this inves- tigation was to evaluate the effects of RT delivered by 3-dimensional conformal radiotherapy (3D-RT) or intensity-modulated radiotherapy (IMRT) on dental pulp sensitivity. Methods: Twenty patients with oral or oropharyngeal cancer receiving RT with 3D-RT or IMRT underwent cold thermal pulp sensitivity testing (PST) of 2 teeth each at 4 time points: before RT (TP1), the beginning of RT with doses between 30 and 35 Gy (TP2), the end of RT with doses between 60 and 70 Gy (TP3), and 4 to 5 months after the start of RT (TP4). Results: All 40 teeth showed positive responses to PST at TP1 (100%) and 9 at TP2 (22.5%; 3/16 [18.8%] for 3D-RT and 6/24 [25.0%] for IMRT). No tooth responded to PST at TP3 and TP4 (0%). A statistically significant difference existed in the number of positive pulp responses between different time points (TP1 through TP4) for all patients receiving RT (P # .05), IMRT (P # .05), and 3D-RT (P # .05). No statistically significant differences in positive sensitivity responses were found between 3D-RT and IMRT at any time point (TP1, TP3, TP4, P = 1.0; TP2, P = .74). A statistically significant correlation existed between the location of the tumor and PST at TP2 for IMRT (P # .05) but not for 3D-RT (P = .14). Conclusions: RT decreased the number of teeth responding to PST after doses greater than 30 to 35 Gy. The type of RT (3D-RT or IMRT) had no influence on the pulp responses to PST after the conclusion of RT. (J Endod 2012;38:148–152) Key Words Intensity-modulated radiotherapy, oral cancer, oropharyngeal cancer, pulp sensitivity, 3-dimensional conformal radiotherapy R adiation therapy (RT) is part of the treatment of malignant tumors because of the ability of ionizing radiation to control cell growth. However, to reach target cells, radiation will have to pass through healthy tissues, which may damage the DNA of normal cells. Various techniques have been developed to minimize harmful effects, ranging from altered fractionation RT to more recent techniques that were made avail- able with advances in computer hardware and software. These include 3-dimensional (3D) radiation treatment planning or computer-controlled RT delivery systems (1–3). Compared with conventional 2-dimensional RT, 3D conformal radiotherapy (3D- RT) and intensity-modulated radiotherapy (IMRT), a form of 3D-RT based on the use of optimized, nonuniform radiation beam intensities targeting the field of focus (4–6), have shown an improvement in dose distribution (7, 8). Commonly, radiation beams have a uniform intensity across the field or are passed through fluence- modifying devices to reduce the intensity, such as compensating filters or wedges (4). 3D-RT aims to adjust the spatial distribution of the radiation dose to a 3D target volume (4). This volume contains the cancerous cells plus a surrounding margin of healthy tissue, which is included to compensate for spatial uncertainties, effectively minimizing the dose to the encircling healthy structures outside the target area (4). IMRT has been shown to be advantageous over 2-dimensional RT and also conventional 3D-RT because it provides a more homogeneous dose distribution within the target volume and decreases the radiation dose in the surrounding tissues (8). As other forms of cancer, the treatment of head and neck tumors commonly includes RT, which can be responsible for significant changes in the oral cavity, causing direct or indirect effects on teeth and soft tissues in the mouth (9–13). Using IMRT, vital, healthy organs close to the target area during head and neck RT (eg, the salivary glands) were shown to be safer from adverse effects of the treatment (14, 15). Several studies also suggested that IMRT results in low rates of radiation- related xerostomia (16–18), that it has a reduced morbidity compared with 3D-RT (19), and that it results in good locoregional control and survival rates (19–22). Teeth are a common structure in the pathway of radiation during head and neck cancer treatment. Inside a tooth, the dental pulp is a specialized, loose connective tissue From the *Discipline of Endodontics, Department of Esthetic Dentistry, School of Dentistry, Universidade de S~ ao Paulo, S~ ao Paulo, S~ ao Paulo, Brazil; † Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; ‡ Department of Oral Medicine, S  ırio Liban^ es Hospital, S~ ao Paulo, S~ ao Paulo, Brazil; and § Discipline of Endodontics, School of Dentistry, Centro Universit ario do Par a, Bel em, Par a, Brazil. Address requests for reprints to Dr Frank C. Setzer, Department of Endodontics, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Philadelphia, PA 19104. E-mail address: fsetzer@dental.upenn.edu 0099-2399/$ - see front matter Copyright ª 2012 American Association of Endodontists. doi:10.1016/j.joen.2011.09.022 Clinical Research 148 Kataoka et al. JOE — Volume 38, Number 2, February 2012