Limitation of mouth opening after radiotherapy for head and neck

Objective To evaluate the ability to open the mouth in patients undergoing radiotherapy for head and neck and the variables related to this limitation. Methods 32 patients were evaluated six months after completion of radiotherapy sessions to treat cancer in the head and neck. The maximum mouth opening was measured using digital calipers and its association with gender, age, smoking, alcohol consumption, tumor location, chemotherapy and surgery were analyzed using the Mann-Whitney and Kruskal-Wallis tests at a level of significance of 95%. Results The mean age of patients was 60.44 years; 87.5% were male; 81.2% were smokers; 65.6% regularly consumed alcohol. The average mouth opening was 43.17 mm and seven (21.9%) patients had trismus. The most common locations of the tumors were the tongue (31.3%) followed by the larynx and vocal folds with five (15.6%) each. No association was found between limited mouth opening and the other variables. Conclusion In this sample, 21.9% of patients had trismus six months after completing radiotherapy. The variables gender, age, smoking habits and alcohol consumption, tumor location, previous surgery and adjunctive chemotherapy were not associated with limited mouth opening. Indexing terms: Head and neck neoplasms. Mouth. Radiotherapy.


Limitação de abertura bucal pós-radioterapia de cabeça e pescoço
Rafael da Silva CAETANO1 Paula Gabrielle de CASTRO 2 Paulo Henrique de Souza CASTRO 2 Alexandre Meireles BORBA 1 Álvaro Henrique BORGES 1 Luiz Evaristo Ricci VOLPATO 1 Limitation of mouth opening after radiotherapy for head and neck collected in respect of age, the social habits of smoking and alcohol consumption, tumor location, performance of adjunctive treatment (chemotherapy and/or surgery) and the measurement of the mouth opening.
The mouth opening capacity was checked using digital calipers (Pantec -São Paulo, Brazil).In those patients who still have their teeth, the distance was measured between the incisal edge of the upper and lower incisors (11, 41); patients with an edentulous lower arch and without the use of a prosthesis, the distance between the incisal edge of tooth 11 and the lower alveolar ridge (region of tooth 41); patients with an edentulous upper arch and without the use of a prosthesis, the distance between the incisal edge of tooth 41 and the alveolar ridge (region of tooth 11); edentulous patients using prostheses, the distance between the upper and lower dentures was measured, or if the patient had no prosthesis, the maximum distance between the two alveolar ridges (location of teeth 11 and 41) was measured, as described by Dijkstra et al. 7 A patient was deemed to be suffering from trismus when his/her maximum mouth opening was less than 35 mm 7 .
The data were stored using Microsoft Excel and the subsequent statistical analysis was conducted using the IBM SPSS 20.0 software application.The Mann-Whitney U test was used to analyze two independent samples.For the analysis of more than two samples, the Kruskal-Wallis test was applied.The level of significance employed was 95%.
The research project was approved by the Research Ethics Committee at the University of Cuiabá (UNIC), Cuiabá, Mato Grosso, Brazil, opinion no.378.314.

INTRODUCTION
Amongst the malign neoplasms of the head and neck, tumors occurring in the oral cavity account for 40% of cases, followed by those of the larynx (25%) and pharynx (15%).The remaining neoplasms are located in the saliva and thyroid glands 1 .
Radiotherapy is a mode of treatment that is often used for malign neoplasms of the head and neck and has a significant cure rate, although it is associated with various oral complications 2 .
The chewing muscles or the temporomandibular joint (TMJ), when they are enclosed in a radiation field, may lead to the formation of tissue fibrosis, muscle spasms and restricted mouth opening, or trismus 3 .
Trismus manifests itself slowly and can evolve into an inability to open the mouth and prevent normal function 4 , harming an individual's quality of life as it hampers the proper digestion of food, chewing and oral hygiene.Trismus also makes dental treatment extremely difficult [5][6] .
Thus, the aim of the present study was to evaluate, in a subpopulation, the mouth-opening ability of patients subjected to radiotherapy treatment in the area of the head and neck.

METHODS
In order to carry out this study, a convenience sample was employed consisting of 32 patients subjected to radiotherapy treatment in the area of the head and neck, both with and without associated chemotherapy and surgery, between the months of January and June 2012.The patients were selected by undergoing a preradiotherapy oral examination in the Dental Department of the Mato Grosso Cancer Hospital (known locally as the DOHC), all of whom gave their consent by signing a Free and Informed Consent form.
The patient analyses were performed, by a single researcher, six months after the conclusion of the radiotherapy sessions.During the evaluation, data were (31.3%), followed by the larynx and the vocal fold, each with 5 (15.6%) (Table 2).
With regard to the location of the tumor, the region most affected was the tongue, with 10 cases

Tumor location n (%)
Floor of mouth The average mouth opening of the patients was 43.17 mm (±12.17).In a comparison of the mouth opening of the patients by sex, alcohol and smoking habits, tumor location and adjunctive treatment with surgery or chemotherapy, no statistical difference was found between the groups (Table 3).

Limitation of mouth opening after radiotherapy for head and neck
The average mouth opening of the patients analyzed was 43.17 mm (±12.17),close to that observed by Jager-Wittenaar et al. 5 , in a study that analyzed the mouth opening of 120 patients (40.1 mm ±11.5), and far higher than that found by Scott et al. 10 , in a study which analyzed the mouth opening of 100 patients, observing an average mouth opening of 32 mm.
Seven (21.9%) of the thirty-two participants in this study presented with trismus.This percentage is considered high, more than one fifth of the patients, although it is less than that found by Lee et al. 11 , where 79% of patients had trismus six months after the conclusion of radiotherapy, and

DISCUSSION
As found in other studies, the mean age of the sample was over 60 years 5,[8][9][10] , the dominant sex is male and the location most affected by tumors is the tongue 5,[7][8] .
With regard to social habits, around 81.3% of patients declared themselves to be smokers while 65.6% were regular alcohol drinkers.The study conducted by Bragante et al. 9 obtained a sample of 26 volunteers in which 100% were smokers and 73.1% stated they were regular alcohol drinkers, with results close to those obtained in this study.
NB.The Mann-Whitney U test was used to analyze the variables of sex, alcohol consumption and smoking.The Kruskal-Wallis test was used for the location of the tumor.by Pauli et al. 12 , where 38% of the 75 patients presented with trismus.

Variable
In the study by Lee et al. 11 it was noted that patients who were regular consumers of alcohol have a lower chance of the occurrence of restricted mouth opening, possibly due to the intoxication which could reduce the sensation of pain during movement of the jaw, leading to a wider opening of the mouth than amongst those who do not use alcohol.In the present study, there was no statistical difference between mouth opening patients who were drinkers compared with those who did not drink.
In this study, the adjunctive treatments, such as chemotherapy and surgery, had no influence on the mouth opening of the volunteers, just as with the study by Lindblom et al. 13 which showed no connection between surgery and mouth opening limitations.With regard to chemotherapy, Bragante et al. 9 noted no variation in mouth opening measurements.
Despite the fact that this study did not find any statistical differences in patients with and without trismus, it is important to stress that more than one fifth of patients who underwent radiotherapy in the region of the head and neck still presented with limited mouth opening six months after the conclusion of treatment, similar to the study by Jager-Wittenaar et al. 5 who found no significant difference in the maximum mouth opening in patients with or without trismus.
Santos et al. 14 underline the importance of the dental surgeon in minimizing or even avoiding these alterations, thereby providing the individual with a better quality of life, given that not only trismus but also other reactions caused by radiotherapy may be prejudicial to the patient.
Epstein et al. 15 stress that active/passive exercises should be commenced after surgery and radiotherapy in the region of the head and neck, when the muscles responsible for the movement of the lower jaw lie within the radiation field, as once a limitation on mouth opening is established, mobility is impaired.According to Ren et al. 16 , the TheraBite ® , a tool used for mouth opening exercises, may be employed, or even other simple devices such as tongue depressors and corkscrews that are used in clinical practice to help with mouth opening.

CONCLUSION
In the sample studied, 21.9% of patients presented with a maximum mouth opening of less than 35 mm six months after the conclusion of radiotherapy treatment.The variables of sex, drinking and smoking habits, tumor location, previous surgery and adjunctive chemotherapy were not associated with mouth opening limitations.

Table 1 .
Distribution of patients evaluated according to the variables of sex, alcohol and smoking habits and the presence of trismus.Cuiabá (MT), 2014.

Table 3 .
Analysis of the mouth opening of patients by sex, alcohol and smoking habits and tumor location.Cuiabá (MT), 2014.