Patients With Head and Neck Cancer Treated by Radiotherapy: The Impact of Fixed Dentures on Wellbeing and Oral Health Related Quality of Life
Phase: NA
Conditions: Head and Neck Neoplasms, Dental Prosthesis, Dentures, Quality of Life
Sponsor: Region Jönköping County

 
1 
05/09/2017 
 
 
 
Patients with head and neck cancer treated by radiotherapy: The 
impact of fixed dentures on wellbeing and oral health related 
quality of life. 

 
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Introduction 
Head and neck neoplasms are defined as tumours in the upper aerodigestive tract. The 
tumours origin from different tissues such as the carcinomas arising from the 
epithelium, and sarcomas from bone, cartilage, fat, muscle, vascular, or hematopoietic 
tissues. Lymphomas are tumours in the lymphoid system, and melanomas arise from 
melanocytes, melanin-producing cells in the skin. The sites affected by the tumour are 
the lips, oral cavity, pharynx, larynx, and cervical oesophagus, the nose and paranasal 
sinuses, salivary glands, thyroid gland and parathyroid glands, and melanoma and non-
melanoma skin cancers of the head and neck (1). Head and neck cancer is the fifth most 
common cancer worldwide with an estimated global incidence of more than 500 000 
cases per year (2). Tobacco use and alcohol consumption are the most important risk 
factors for these cancers, while a subgroup is caused by viral infections. Patients with 
early-stage disease are treated by surgery or radiotherapy, whereas patients in 
advanced stages receive a combination of these modalities or concurrent chemotherapy 
and localized radiation. The five-year survival rate after treatment is around 40-50 % 
(3). 
Patients with head and neck cancer treated by radiotherapy suffer from acute and 
long-term oral side effects. Oral mucositis, pain, dysphagia, and superficial opportunistic 
infections are common acute side effects that in most cases cease within one month after 
radiotherapy has been completed. However, long-term side effects like hyposalivation, 
impaired taste, and trismus may be life long conditions. Moreover, altered 
microbiological flora of the mouth, attenuated tooth enamel, and hyposalivation are risk 
factors for dental caries (4-6). Other hard tissue damages caused by radiotherapy are 
periodontitis, and more severely osteoradionecrosis of the jaws (7). The latter condition 

 
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is caused by poor vasculated bone. Teeth with poor prognosis should be extracted 
before radiotherapy begins, leading to impaired occlusion including dysfunctional 
aesthetics and mastication. The Swedish National Board of Health and Welfare 
regulations compensate extracted teeth with removable dental prostheses/dentures (8). 
However, using removable dentures in patients with hyposalivation after radiotherapy 
is complicated. Removable dentures retain poorly, or chafe the oral mucosa leading to 
pain in function. Also, there may be problems maintaining good dental and denture 
hygiene leading to dental caries and periodontitis.  
 
To date, the impact of dental occlusion on these patients’ quality of life is sparsely 
investigated. In one study, implant-retained mandibular overdentures in patients 
treated for oral cancers were followed over five years (9). Overall, the survivors’ oral 
function and patient satisfaction were high and did not change. Impaired global health 
and quality of life were associated with concurrent comorbidity. Malnutrition, 
associated with increased morbidity and mortality, in patients treated for 
oral/oropharyngeal cancers was shown to impair physical functioning and hence quality 
of life (10). In this study dental status was poorly described, although dry mouth, pain in 
the mouth, and problems with social contact correlated well to malnutrition and fatigue. 
Speech after surgery was more impaired in patients with oral cancers than with 
oropharyngeal cancers because of loss of anatomically important articulatory structures 
leading to decreased quality of life. However, there are no prospective studies 
supporting better speech outcome after radiotherapy alone compared with surgery 
(11).  
 
Therefore, the aim of this project was to evaluate the effect and cost effectiveness 
of prosthodontic rehabilitation on oral health related quality of life, general wellbeing, 
and nutrition in patients treated by radiotherapy, with or without combination of 

 
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chemotherapy or surgery against head and neck cancer.  
Methods  
Design and setting 
In this project, an interventional case-control study will be undertaken in four middle 
sized counties in the south of Sweden. Based on the case control sample also a 
methodological study will be realized in order to test the measurements’ validity and 
reliability, but also a descriptive qualitative content analysis study will be accomplished. 
All these measurements – called triangulation – are done in order to strengthen the 
case-control study as a power calculation is not relevant to do due to the restricted 
eligible/consecutive sample as well as the restricted time schedule. Finally, based on all 
available data, a cost-effectiveness analysis will be undertaken with the use of a decision 
analytic model. 
Intervention 
Standard treatment 
In order to replace extracted teeth after radiotherapy, the standard treatment is 
temporary removable dental prostheses/dentures (partial or complete). Depending on 
the teeth remaining, those may be completely tooth or tissue supported, or tissue and 
tooth supported. Temporary partial dentures are completely out of acrylic. Efforts are 
made to design a self-cleansing partial denture that preserves the remaining teeth and 
oral structures. The chewing forces are distributed evenly over the entire remaining 
teeth and soft tissues. Oral health related quality of life in healthy patients wearing 
removable dentures has previously been shown (12). 

 
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Fixed dentures 
The special treatment is to within a year after completed radiotherapy replace 
removable dentures with tooth- or implant-supported dentures. The special treatment 
will begin six months after completed radiotherapy, or later depending on the severity 
of the side effects. Tooth- and implant-supported dentures are accepted modalities in 
patients with total or partial edentulous (13, 14). Patients with head and neck cancers 
usually follow the dental implant protocol valid for healthy individuals (15, 16). 
However, the fixture installation will be within a year after finished radiotherapy, when 
the jaws are still well supplied.  
Participants 
The study will take place in four middle sized counties in the south of Sweden. The 
intervention will include 30 patients with head and neck cancer recruited from a 
Department of Maxillofacial and Oral Surgery (the City of Jönköping, Jönköping County 
Council), and from the Department of Orofacial Medicine (the City of Stockholm, 
Stockholm County Council). Another 30 patients with the same disease will be matched 
controls recruited from another Department of Maxillofacial and Oral Surgery (the City 
of Linköping, County Council of Östergötland) and from five Departments of Orofacial 
Medicine (the Cities of Kalmar, Oskarshamn, and Västervik, Kalmar County Council; the 
Cities of Ljungby, and Växjö, Kronoberg County Council). If possible but not necessary, 
those controls may be prosthodontically rehabilitated with temporary removable 
dentures. The retest described in data collection study one will include ten patients 
diagnosed with head and neck tumor. All patients in the retest will be residents in the 
County of Jönköping. 

 
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The inclusion criteria are patients with head and neck tumours considered to receive 
radiotherapy, with or without combination of chemotherapy or surgery, good 
oncological prognosis at baseline (≤T2). After referral from an ENT-specialist, those 
patients being diagnosed with dental infections and therapy planned for dental 
extraction(s) will be included. 
The following general exclusion criteria will be applied: any communication problems; 
any comorbidity with poor prognosis; poor oncological prognosis (TNM-classification 
>T2) at baseline; imminent risk of recurrence; any technical, biological, or any other 
reasonable obstacle of treating patients with fixed dentures; and finally patients in the 
matched control group financing fixed oral prosthesis themselves.  
Background data like sex, age, diagnosis, TNM-classification, hyposalivation, vertical jaw 
mobility, dysphagia, number and sites of extracted teeth, and weight will be 
investigated. 
Study one – quantitative approach 
Instruments 
SF-36v2 
SF-36v2 is a well established psychometric instrument with 36 items measuring eight 
domains of health-related quality of life: Physical function, physical role function, bodily 
pain, general health, vitality, social function, emotional role function, mental health. The 
two comprehensive indices – physical health and mental health - can be estimated for. 
The instrument is translated and validated into Swedish (17-19).  
EQ-5D 

 
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EQ-5D is an instrument containing five items measuring mobility, self-care, pain, role 
function, and anxiety/depression. There is also one item considering change of health 
condition and a VAS scale for general health. This instrument is also translated and 
validated into Swedish (20-22). 
Oral health impact profile (OHIP) 
OHIP-14 is an instrument consisting of 14 items (23). It was designed to provide a 
comprehensive measure of the dysfunction, discomfort and disability attributed to oral 
conditions. Validated Swedish versions of the OHIP-14 are available (24, 25).  
 
General oral health assessment index (GOHAI) 
GOHAI is a 12-item instrument originally developed for use with older adult 
populations, although more recently it has been used with populations of younger 
adults. It measures oral functional problems and also assesses the psychosocial impacts 
associated with oral disease (26). A Swedish version has been validated (27). 
The Jaw Functional Limitation Scale (JFLS-8) 
The JFLS-8 was developed for assessing limitations in mastication, jaw mobility, and 
verbal and emotional expression. It is recommended for clinical and research use in 
patient groups with varying functional limitations of the jaw. The instrument has been 
tested for reliability and validity (28, 29).  
 
The Orofacial Aesthetic Scale (OAS) 
The OAS consists of seven separate aesthetic aspects of the face, teeth, lips, and mouth 
— devoid of psychosocial aspects. These seven items create the OAS summary score. 
There is also an eight item, global assessment of overall impact. A Swedish version has 

 
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been validated (28, 30, 31). 
Data collection 
The written consent among with the instruments will be distributed to the patients at 
the clinic at baseline (before any treatment), appendix 4.  The completed documents will 
be returned to a research coordinator/dental assistant at the Department of 
Maxillofacial and Oral Surgery (the City of Jönköping, Jönköping County Council). 
Measurements and administration of the instruments after baseline follow the study 
protocol, appendix 13. The study protocol after completed radiotherapy states 
measurements at approximately 6 and 12 months respectively, or in severe cases after 
the prostheses have been used for one month. Those patients who receive the 
instruments by mail, will be requested to immediately respond to the instruments and 
return them to the research coordinator in attached envelopes (prepaid postage). A 
reminder is sent to the patient after one and two weeks if not responding. If necessary 
after another week, the patient will be contacted by telephone by the research 
coordinator. The patients weight will be recorded at the clinic, or self-reported by mail. 
Data analysis 
Parametric as well as non-parametric methods will be used in the statistical inference 
testing. Thus, for comparison between two groups the Student t-test and the Mann-
Whitney U-test and between three groups or more Two-Way Analysis of Variance the 
Kruskal–Wallis One-Way Anova will be applied. For comparison of proportions between 
groups the Chi-square-test including standardized residual are to be used. For analysing 
changes over time the paired t-test or the Wilcoxon Signed Rank Test (for continuous 
variables) or the McNemar Test (for dichotomised variables) will be applied. For 
estimating relation between two continuous variables the Pearson test or Spearman 

 
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Rank Order Correlation will be used. For prediction, multiple and logistic regression are 
to be used and in order to adjust for confounding variables such as age logistic 
regressions also are to be used. The pre-chosen level of significance will be p<0.05 in all 
analyses. 
Study two – qualitative approach 
Interviews 
A dental assistant experienced in methodological or subject experiences will interview 
the patients during approximately one hour twice. The dialogue will start with questions 
on general wellbeing, and then approaching oral health related quality of life. All the 
interviews will start with the question “How do you feel with regard to your health?”, 
followed by “Can you tell me more?”.  Eventually the dental assistant asks, “How do you 
feel with regard to your mouth?” The interview will result in a detailed and exhaustive 
story from different point of views. All interviews will be recorded on minidiscs. 
Data collection 
The first interview will take place approximately six months after completed 
radiotherapy, and the second one after approximately 12 months.  
Data analysis 
Qualitative content analysis described by Hsieh and Shannon (32) will be used in 
analysing the interviews. Each interview will be listened to in order to gain a general 
understanding of the content. Any content relevant to the aim will be analyzed. The text 
will be condensed and labelled using codes, being careful not to change the core of the 
meaning units based on the aims. The codes will be matched and grouped into 

 
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categories in accordance with similarities and dissimilarities. The categories will be 
scrutinised for underlying meanings, which will generate a number of sub-themes that 
reflect the content. The sub-themes will eventually be grouped under a few 
comprehensive themes.  
Study three – validity and reliability test 
Data collection 
Eight patients with head and neck cancer from the Department of Maxillofacial and Oral 
Surgery (City of Jönköping), and eight healthy controls from the Public Dental Service 
Clinic (City of Jönköping) from study one will be recruited consecutively. The 
instruments described in study one will be completed at baseline. After 1-2 weeks, those 
patients (n=16) will complete the same instruments to evaluate test-retest reliability 
and validity. 
Data analysis 
Reliability  
Homogenity: Cronbach’s alpha assesses internal consistency. According to Bland & 
Altman, Cronbach alphas of 0.70 to 0.80 are satisfactory for comparisons between 
groups, while an alpha of 0.90 is needed for clinical use. 
Stability: Intraclass correlation coefficients (ICCs) with 95% confidence intervals are 
calculated per Shrout & Fleiss’s ICC method based on a one-way analysis of variance 
(ANOVA). The concordance correlation coefficient (CCC) assesses reproducibility 
(temporal stability). 
 
Validity  

 
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Content validity: Patients are asked, “Do you think the questions on aesthetics reflect the 
concerns you have with your mouth, your teeth and your tooth replacements 
(prostheses, crowns, bridges, and implants)?” They respond on a 0–10 VAS-scale with 
the anchors “very dissatisfied” and “very satisfied”. 
Discriminative validity: Comparisons are made of OHIP-14 and GOHAI summary scores 
of each patient group with control groups and between patient groups. Relevant and 
statistically significant differences using t-tests and ANOVA are expected.  
Convergent validity: Spearman rank order correlations (rho), assess convergent validity 
between (i) OHIP summary scores and self-reported health and (ii) OHIP subscale 
scores and subscale scores of the SF-36 and EQ-5D.  
Study four – Cost-effectiveness analysis 
Background 
In order for a method in health- and dental care to be considered cost-effective, it has to 
be a decent relation between its extra costs and effects (no exact threshold value exist in 
Sweden). A cost-effectiveness analysis estimates the incremental cost-effectiveness ratio 
(ICER) of a method in comparison with the best option (33). The outcome measure can 
be of any (relevant) kind, but usually it is recommended to use quality-adjusted life-
years (QALYs) which also is preferred by the Swedish Dental and Pharmaceutical 
Benefits Agency (34). QALY combines preferences for health states (QALY-weight) with 
the number of years of that health state.  
In order to capture the full consequences of a treatment, it is often necessary to model 
future costs and effects into a longer time horizon. Even though these models cannot be 
seen as evidence, they can provide the most accurate estimate on the long-term cost-

 
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effectiveness and they can furthermore handle uncertainty in order to provide a 
decision-maker with relevant information (35). 
Data collection 
Costs and effects of different prosthodontic rehabilitations, fixed and removable 
dentures, will be compared with costs and effects of radiotherapy of patients with head 
and neck cancer. Data on resource use will be gathered in the intervention and 
translated into costs, representing their best alternative use. Productivity loss of 
patients unable to work will be estimated using the human capital approach. The main 
outcome measure in the analysis will be QALY. QALY-weights are derived indirectly 
from the instruments EQ-5D and SF-6D, and directly from the EQ-VAS, all of which are 
analysed in Study one in this project. Other outcome measures that are more directly 
derived from oral health related quality of life will be used too in order to examine their 
relevance. 
Data analysis 

 
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A decision analytic model will be created that simulates the costs and effects of a long 
time horizon. In order to take into account the uncertainty in the parameter estimates 
derived from the intervention study, the model is run probabilistic. This means that the 
analysis is repeated 1,000 times, and each time the parameters are selected randomly 
from the distribution of the uncertainty surrounding the parameters. In this way, the 
total statistical uncertainty is illustrated. The results will be presented with and without 
including productivity losses.  
Ethics   
Ethical approval for the study was obtained from the Regional Ethical Committee (EPN) 
at Linköping University (2012/200-31; 2013/66-32).  
Relevance of the project 
The relevance of the project will be increased knowledge about the impact of 
replacement of extracted teeth with fixed dentures on oral health-related quality of life 
and general wellbeing, in patients with head and neck cancer after radiotherapy. 
Patients’ recovery after disease in terms of wellbeing and oral health related quality of 
life may improve by fixed teeth. Professionals will benefit since this is an evaluation of 
the treatment outcomes. The society will also find the results important in order to 
evaluate the rehabilitation of patients that has received extensive oncological care. This 
may lead to overall reduced costs for medical and dental care. 
 

 
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