Changes in mental health and quality of life with dental implants as evaluated by General Health Questionnaire (GHQ) and Health Utilities Index (HUI)

In order to properly evaluate the outcome of a medical intervention, it is very important to measure the quality of life (QOL). More attention tends to be paid to the evaluation of medical interventions which are more often associated with life-threatening illnesses than with those that have primarily aesthetic and nutritional function. The use of a systemic evaluation index to assess the effects of dental treatment impacting on the improvement of life function, from a conventional viewpoint, of the elderly has been an uncommon practice. Missing teeth have traditionally been replaced with dentures or bridges. The first dental implant first successfully placed and reported by Brånemark in 1965 [1]. Since then, implant treatment has become increasingly applied for tooth replacement worldwide. Titanium implants have the advantage of binding with bone (osseointegration) and are inserted directly into the bone at the site of tooth loss to serve as an artificial tooth root. The general condition of the patient and both the quantity and quality of bone at the implant site must be assessed before the procedure is undertaken. The ability or inability to ingest food orally has a large impact on the general health condition of an individual, both physically and mentally, especially in the elderly, who frequently have missing teeth. However, the systemic effects of dental treatment have not been adequately evaluated, and these effects are now considered to be significant as ways are being sought to improve the QOL of the elderly. Although improvements in QOL as a result of dental care or implant therapy have been reported [2‐5], few scientific studies have used health utility to investigate the effect of oral health on the state of general health of dental patients.

Health-related QOL (HRQOL) measures can be used to assess the effectiveness and quality of medical care, and either disease-specific or generic instruments are used to measure HRQOL, depending on the specific aim of the study. Disease-specific instruments have been developed to evaluate the changes in each specific aspect of a disease, such as specific symptoms, treatment, and medical outcomes. Conversely, generic instruments are used for the quantitative evaluation of a wide range of health statuses, not only those related to disease but also those that give a sense of general health, such as physical functioning in daily life, mental health, social engagement, and social life functions of a patient. This enables generic instruments to be applied in local health surveys, and the results obtained can be compared across various realms of related treatments and conditions, or applied to a variety of diseases. Among the generic instruments used are the Health Utilities Index (HUI) [6], EuroQol (EQ 5D) [7], and MOS 6-Item Short-Form Health Survey (SF-6D) [8], and these are known to be useful in the calculation of quality-adjusted life years (QALYS) [9]. QALYs are outcomes that are necessary to perform cost utility analyses (CUA) [10]. HUI is an instrument for health utility measurement that was developed by G. Torrance and colleagues at McMaster University, Ontario, Canada. The Japanese version has been validated in several studies [11]. HUI assesses eight attributable aspects of QOL, producing one simple value of a multi-attribute utility score for use as an indicator of health status. It is based on the utility theory of von Neumann–Morgenstern [12, 13], with states of being that are worse than death indicated by negative utility values [14]. Scoring functions are based on a direct method of utility measurement, such as time-trade-off or standard gambling method. It contains a questionnaire that is simple to answer and is useful in studies with multiple subjects. This standardized simple questionnaire method has become popular in recent utility measurement studies [15].

Investigations of the validity and utility of these generic instruments have indicated that health utility and other studies of medical economics studies should be conducted in each country [16]. Uemura et al. [17] reported on the construct validity of the Japanese HUI3, while O’Brien [18], Luo et al. [19], and Naglie et al. [20] reported on the reliability of the HUI.

The General Health Questionnaire (GHQ) is one of the most common mental health tools in use. The GHQ is a measure of current mental health and has been extensively used in different settings and cultures since its development by D.P. Goldberg in the 1970s [21‐25]. The questionnaire was originally developed as a 60-item instrument, but shortened versions, including the GHQ30, GHQ28, GHQ20, and GHQ12, are now available. Each item is rated on a four-point scale that indicates whether the respondent has recently experienced a particular symptom or behavior: less than usual, no more than usual, slightly more than usual, and much more than usual. For example, the GHQ12 gives a total score of 36 or 12 based on the scoring method selected. The most common scoring methods are bimodal (0-0-1-1) and Likert scoring style (0-1-2-3).

The aim of this study was to assess the improvement of oral and systemic conditions and HRQOL in patients with missing teeth who were treated by receiving dental implants or by more conventional treatments.

The characteristics of subjects in both groups at baseline were examined using the chi-square test to clarify statistical differences.

No significant differences were observed between males and females in the implant group and conventional group (p = 0.67). However, significant differences were found between the two treatments when patients aged 30–59 years were compared with those aged >60 years (p = 0.014). No significant differences were observed in FD and PD among the two treatments (p = 0.40) (Table 1).

The subjects in the older age group requested implants more often than those in the younger age group. Although the cost of dental treatment is covered by health insurance in Japan, implant treatments are not covered. Thus, our observation that older patients more often requested implant treatment is likely based purely on economic reasons.

Our results suggest that aesthetics-related issues were improved both by implants and conventional treatment in the Young PD group and that this group expressed concern about the improvement in the appearance of their teeth. Sense and chewing ability are significantly improved by conventional treatment. It follows, therefore, that the oral function and the stability of the missing mandible molar teeth of middle-aged patients can be recovered satisfactorily with PD. In addition, conventional treatments for elderly persons can contribute to an improvement in QOL, based on the improvement of HUI global score. These improvements were not seen with an implant treatment. One possible explanation has been proposed by Takenaka et al. [29], who reported that implants resulted in significantly more physical discomfort than the requested conventional dentures. Pain was significantly improved by implants in the Old PD group, possibly because the area of mucous membranes was freed from considerable stress by the loss of the denture base. Shimada et al. [3] reported that the function, presence/absence of pain, and level of satisfaction with oral health are related to general health and mental health and that these factors greatly affect QOL. We also believe that the improvement of pain after treatment by implants in Old PD is related to an improvement in the GHQ12 score at this time. Using the Oral Health Impact Profile (OHIP-14) and GHQ12, Smith et al. estimated the mental health and QOL of patients treated with implants and observed decreased stress and improved QOL [4].

The improvement in aspects of mental health was seen more with implants than with dentures in both age groups. It is thought that this improvement was due to a decrease in the feeling of looseness in the dentures with the change from FD without anchors to FD with implant anchors. Suzuki et al. [5] surveyed QOL in oral impairment and oral satisfaction in full denture and in implant denture patients and reported that there was no difference in the QOL after the procedure and that treatment satisfaction was similar. However, satisfaction with the oral cavity and daily living was higher in the implant patients. Moreover, Heydecke et al. [30] reported that oral health QOL was improved with implants over dentures, along with a simultaneous improvement in HRQOL. In addition, as a result of the stability of the dentures provided by implant anchors, there was an improvement in the lifestyle of the elderly people in terms of sleep and oral global assessment.

The results of our study suggest that implants have a positive influence on a change in the mentality of people who still have some teeth and in elderly persons, with the exception of middle-aged persons still with some teeth. In this regard, Matsuoka et al. [31] reported that subjective happiness was high and a tendency towards dejection was low; therefore, the high intra-oral satisfaction and the number of surviving teeth is related to the physical balance and function in elderly persons. Naito et al. [32] reported that the maintenance of the oral cavity function contributes to physical QOL, as observed from their findings that the greater the number of residual teeth, the higher the physical QOL; as bite and tooth alignment worsen, physical QOL decreases and the degree of intraoral health will show a decline together with a decline in mental health. According to these reports it is thought that the number of remaining teeth is related to aging of the oral mucosa and the aging of the whole body in elderly persons and that mental health aspects were improved significantly in GHQ12 for elderly persons with residual teeth still in place.

One of the key issues of this survey is whether dental implants contribute to the improvement of QOL. Patient satisfaction is an important factor in dental treatment, as it is expected to contribute to an improved standard of living and a prolonged life-expectancy. The acceptability of the risk of medical intervention differs depending on individual patients, as choice of the preferred medical treatment also varies from patient to patient. Health service providers must properly consider the patient’s preference during treatment planning in various clinical situations. In our study, significant differences in HUI3 were observed for the HUI global score and pain in the Old PD group. One explanation for this result is that dental treatment does not have a direct effect on vision and hearing. However, a few reports do state that oral condition may affect the eyes [33] or hearing [34], among other conditions. In our study we also used the HUI as an indicator of health status, but this index was originally used to calculate QALYs and CUA. These medical economic analyses are more useful for diseases with a poor prognosis, such as cerebrovascular disease, cancer and rheumatic disease. We considered measuring the health utility score as an important outcome assessment of implant treatment. Heydecke et al. [30] reported that patient satisfaction and cost effectiveness were acceptable in implant treatment rather than conventional treatment, although initial costs are more expensive in the former. These findings are meaningful to studies performed in Japan where although most dental treatments are covered by insurance, implants are excluded. Therefore, measurement of QOL using HUI3 will show the effects of treatment, and we believe this preliminary result suggests the effectiveness of dental therapy.

One of the limitations of this study is that due to the limited number of cases available, it was difficult to randomly assign two different treatments, while comparing every prosthesis of the implant, including differences between genders. Another limitation is the simplicity of the mental health condition test. The 12-item GHQ is a rather crude tool to measure the subtleties of mental health.

In conclusion, the recovery of oral function and the stability in middle-aged people treated without implants were possible with PD. However, the results suggest that implant treatment in middle-aged people in edentulous denture cases and in elderly people in partial and edentulous denture cases improves mental health and may exert a positive impact on QOL.

This is the first study to use both GHQ and HUI to evaluate changes in the oral condition before and after dental implant therapy from a systemic viewpoint. The sample size in this study was small, and it will be necessary to conduct further studies with a larger number of subjects involving more dentists to ascertain the validity of our findings and the efficacy of this new intervention. A greater number of health professionals are expected to focus increasing attention to dental implant therapy, which will improve not only oral function but also produce systemic effects.