In Japan, the number of elderly people with missing teeth has been decreasing. However, the number of patients wearing complete denture has not decreased. Therefore, suitable complete denture adjustment for the elderly people is important. The chair time and treatment contents (medical interview, medical examination, fitting, occlusion, adjustment, denture cleaning, patient’s instruction, polishing, postoperative instruction, denture score, blank time) involved in complete denture adjustment were investigated and it is confirmed that there was a lot of patient’s and blank time. The blank time is defined as “time not engaged in treatment” for the dentist, “observation time” for the assistant, and “time sitting in the chair doing nothing” for the patient. This research aimed to clarify a treatment procedure that allows for effective use of the blank time to provide appropriate treatment to each patient. The participants included 31 patients with complete dentures, 14 dentists, and 12 less experienced dentists. Treatment timetables were created using video data. Analyses were carried out to develop a more effective treatment protocol by changing treatment procedures and contents. Issues associated with treatment were also investigated. Treatment activities and chair time during denture adjustment (57 participants) were investigated to do treatment smoothly. As a result there were 22 out of 31 patients (deficiency of the denture cleaning etc.) whose treatment activities should be improved. The results suggested that treatment procedures that allow for effective use of patient’s and less experienced dentist’s blank time to provide appreciate treatment to each patient can be clarified.

Kawata D, Sato Y, Kitagawa N, Shichita T, Isshiki Y, et al. (2016) Improving the Efficiency of Complete Denture Treatment. JSM Dent 4(3): 1069.

•    Complete denture
•    Chair time
•    Blank time
•    Analysis 

In Japan, the average number of teeth lost per person, has been decreasing owing to the 1989 implementation of the 8020 campaign [1]. However, 5.2% of the randomly sampled 3718 participants in the 2011 Survey of Dental Diseases [2] were wearing complete dentures. This suggests that 6.6 million people in Japan are wearing complete dentures [3]. So denture education and researches are considered to be very important.

There are several clinical researches related to complete denture treatment such as “the influence of the dentist’s skill level on the patient’s satisfaction level” [4] and “the patient’s chair time differences based on the dentist’s skill level” [5,6]. In addition, Sato et al., and Shichita et al., reported dentist’s awareness survey about the time required for complete denture treatment [7,8]. Further, other researchers reported the chewing ability of patients who had undergone complete denture treatment [9,10]. Thus, a lot of clinical research regarding complete denture treatment has been conducted to provide patients with highquality treatment. However, few researches have been conducted to evaluate treatment (whether necessary treatment is lacking or not, whether chair time is appropriate or not).

Isshiki et al., conducted a survey of the time required for and the content (treatment procedure, satisfaction of the patient for the treatment) of complete denture adjustment [11]. Their research revealed that dentist’s blank time is only 2.3 min (8.2% of the chair time) during the chair time (28.8 min). However, patient’s blank time was 13.2 min (47.2%) and assistant’s blank time was 12.6 min (45%). The blank time is defined as “time not engaged in treatment” for the dentist, “observation time” for the assistant, and “time sitting in the chair doing nothing” for the patient. More effective use of patient’s and assistant’s blank time can prevent the omission of required treatment procedures. Further, such improvements are able to allow dentists to provide more efficient and appropriate dental treatment for patients. The necessary treatment might be lacked owing to the unclearness of treatment procedure during denture adjustment. So the number of emergency cases which go to the hospital was not few. Therefore it is necessary to clarify the treatment procedure during denture adjustment to prevent this. This research’s purpose is to clarify a treatment procedure that enhances the effective use of patient’s and assistant’s blank time by applying questionnaires and by doing Analyses based on complete denture treatment data. Therefore the provision of appropriate treatment for patients will become possible.

Participants

The participants included 31 patients with complete dentures, 14 dentists, and 12 less experienced dentists. The participants of this research were 31 patients (12 men, 19 women, average age: 81.7) who underwent complete denture adjustment for missing teeth at the Department of Geriatric Dentistry, Showa University Dental Hospital and were provided with a sufficient explanation of this research and whose consents were obtained.

The participants were the patients whose dentures were fitted more than one month before and stable based on their dentist’s judgment. The number of dentists are 14 (years of clinical experience: 2-28, average years of clinical experience: 9.0), less experienced dentists are 12 dentists (years of clinical experience: 1-2, average years of clinical experience: 1.3). The less experienced dentists do only treatment assistance. The dentists performed treatment procedures such as denture adjustment.

Survey duration

The survey duration was the time required only for denture adjustment. However, patients who were undergoing tissue conditioning or who required denture repairs or new dentures were excluded.

Ascertaining of denture adjustment procedure

Scenes of the complete denture adjustment for edentulous patients undergoing adjustment were recorded using a video camera. This research was conducted with the approval of the Showa School of Dentistry ethics committee (Approval No. 2011- 004). Treatment activities were broadly divided into 16 categories (medical interview, medical examination, denture examination (fitting, occlusion), adjustment, denture cleaning, oral care, patient’s instructions, polishing, postoperative instructions, preparation of instruments and clean up, medical records entry, denture score, observation, blank time, others) based on the treatment data obtained from the recordings (Table 1). The blank time is defined as “time not engaged in treatment” for the dentist, “observation time” for the less experienced dentist, and “time sitting in the chair doing nothing” for the patient. Using these categorized activities, timetables (30 seconds interval) were created for the dentists, patients, and less experienced dentists (Figure 1).

Analysis to change the timetable

Analyses of changing timetable were conducted and their impact on treatment activities and chair time was evaluated. The Analysis is to clarify the ideal treatment procedure by changing the treatment contents of the timetable.

Analysis to shorten the chair time (Step 1): A concrete example of Analysis (Step 1) designed to shorten the treatment time is shown in Figure (2). Chair time was reduced by allotting the “treatment tasks that could also be done by the less experienced dentist” (denture cleaning, oral care, patients’ instructions, polishing, postoperative instructions, preparation of instruments and clean up, medical records entry, denture score) to the less experienced dentist.

Analysis to utilize the chair time effectively (Step2): The main purpose of this research is to utilize the blank time effectively and to improve the quality of treatment for patients. A concrete example of the Analysis (Step 2) designed to improve the effective use of the time is shown in Figure (3). Questionnaires (denture satisfaction questionnaire, chewing function questionnaire, denture usage questionnaire, daily life questionnaire) were planned to do for the effective use of the blank time. According to the previous research, the necessary time of the questionnaire is denture satisfaction questionnaire 1.8 minutes, chewing function questionnaire 2.0 minutes, denture usage questionnaire 1.8 minutes, daily life questionnaire 4.0 minutes [12]. This questionnaire was done in case that patients and less experienced dentists have at least 1.8 minutes blank time at the same timing during treatment.

The questionnaire using the denture score

a. Denture satisfaction questionnaire: This questionnaire Figure (4) allowed the patient’s denture satisfaction level to be converted to numerical values, and revealed the change of satisfaction between before and after treatment [13].

b. Chewing function questionnaire: This questionnaire Figure (5) revealed the change in the patient’s food intake status between before and after treatment [14].

c. Denture usage questionnaire: This survey Figure (6) allowed the dentists to easily check each patient’s current denture handling and could be used as a guide when providing instructions to the patient.

d. Daily life questionnaire: By doing this Table (2) it becomes possible to guide the patients the relation of each patient’s denture status and their mood, sense of fulfillment, fatigue, personal relations, dietary habits, etc [15],

The survey method of the questionnaire using the denture score

Not all patients were able to complete the 4 kinds of questionnaires using the denture score during the patient’s and less experienced dentist’s blank time. Therefore the questionnaire order in this research was as follows,

1. Denture satisfaction

2. Chewing function

3. Denture usage

4. Daily life

Treatment Issues

Treatment issues such as omitting required treatments occur, because the procedures involved in denture adjustment are not clearly defined. Therefore, the issues were assessed using a series of questions (“Did you wash the dentures?” “Did you conduct the medical interview?” “Did you conduct the intraoral inspection?” “Did you perform the fitting test?” “Did you perform the occlusion test?” “Did you follow the treatment order?” “Did you explain the treatment?”) throughout the treatment.

Statistical Analysis

The change of the average chair time between before and after of the timetable change was analyzed using a t-test. The change of the blank time for the dentists, patients, and less experienced dentists was analyzed using one-way ANOVA and Bonferroni test. All statistical analyses were performed using statistical processing software (SPAW Statistics Base®, ver. 18, IBM, and Tokyo, Japan).

Average chair time

The average chair time was reduced 2.4 minutes (8.3%) by introducing the changes suggested by the Analysis (Step 1); the change of the chair time was little (Figure 7).

Changes in dentists, patient’s, and less experienced dentist’s blank time

The dentist’s blank time during denture adjustment was reduced by the Analysis (Step 2) (Figure 8). Patient’s blank time was 13.2 min (47.2%) and less experienced dentist’s blank time was 12.6 min (45%). Patient’s and less experienced dentist’s blank time was reduced by the Analysis (Step 2) (p < 0.05).

Treatment Issues

Treatment activities and chair time during denture adjustment (31 patients) were investigated to do treatment smoothly. As a result there were 22 out of 31 patients (deficiency of the denture cleaning etc.) whose treatment activities should be improved (Table 3).

In order to clarify the treatment procedure that is this research’s purpose, participant and assessment period were standardized.

Patients with remaining teeth are susceptible to periodontal disease. Therefore the standardization of the treatment conditions will be difficult. The status of patients who wear complete denture is various. The participants were the patients whose dentures were fitted more than one month before and stable based on their dentist’s judgment.

In university hospitals, it is difficult for dental hygienists to act as assistants for one dentist. When the assistants are students, there are many procedures (postoperative instruction etc.) that they cannot perform and there is a high risk that they will interfere with a treatment. Therefore, in this research all the assistants were unified to trained dentists. In addition, the dentists who were acting as assistants were limited to providing only treatment assistance, and were not allowed to perform treatments instead of the attending dentist. Therefore, similar results would be expected if dental hygienists were acting as the assistants.

Since the difficulty associated with fitting dentures, taking impressions, and maxillary and mandibular registrations differs greatly between patients (due to alveolar ridge instability or jaw position), the denture adjustment period easy to unify the conditions was defined as assessment period.

When the Analyses (Step.1, Step2) on the timetable were done, it was thought that the average chair time will decrease. However, the results of this research demonstrated that even after implementing timetable changes, the average chair time didn’t decrease. According to the study [16] conducted by the Japan Association for Dental Science, the average chair time for denture adjustment in university hospitals is 25.6 minutes. In this research, the average chair time for complete denture adjustment was 28.8 minutes. It is thought that this was derived from two factors. Two factors are that this research’s average chair time for complete denture adjustment is appropriate and there are little blank time during the procedure performed by the dentist. It became clear that the blank time of the patients and less experienced dentists after the Analyses decreased. This was made possible by conducting “denture score” during the time of the less experienced dentist’s “observation”. It is thought that this improved the treatment of the patients and less experienced dentists.

In this research, 22 of the 31 patients should be improved during their complete denture adjustment. It is though that it is caused by the fact that the treatment procedure of denture adjustment is not clear. There were not few emergency patients who go to the hospital due to lacking necessary treatments, because the treatment procedure of complete denture adjustment was not clear. The comprehensive survey of living conditions [17] in Japan shows the rate of dental diseases outpatients is the 3rd place for man and the 5th place for woman. The rate of dental diseases outpatients is very high in Japan. Therefore it is necessary to clarify the treatment procedures in order to reduce the rate of outpatients. Based on the result of this research, treatment procedure for the effective use of the patient’s and assistant’s blank time is shown in Figure (9). According to this treatment procedure, several dentists did treatment.

Analyses (Step 1 and Step 2) were implemented. As a result the chair time was shortened a little (8.3%). And implementing Step 2 could reduce patients and less experienced dentist’s blank time. Based on these results, new treatment procedures that enabled patient’s and assistant’s blank time to use effectively was clarified. And treatment activities during denture adjustment have many issues to be improved. By doing the treatment according to the treatment procedure which can use the blank time efficiently based on the questionnaires, it is suggested that the provision of appropriate treatment to each patient becomes possible.

We thank the patients, dentists, and less experienced dentists for their participation in this study and the Professors of Geriatric Dentistry at Showa University for their kind assistance. This study was partly supported by a 2011 Grant-in-Aid for Scientific Research C from the Ministry of Education, Culture, Sports, Science and Technology (No. 22592160).

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