Hong et al.

Int Chin J Dent 2010; 10: 29-34.

Comparison of their recognition about the denture cleansers
among Japanese, Chinese, and Indonesian dentists
Guang Hong, DDS, PhD,a Ying-Ai Li, DDS, PhD,b Yun-Min Lian, DDS,c Shinsuke
Sadamori, DDS, PhD,b Taizo Hamada, DDS, PhD,a and Hiroshi Murata, DDS, PhDda

Department of Oral Health Care Promotion, Graduate School of Dentistry, Tohoku University, Sendai,b
Japan, Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Hiroshimac
University, Hiroshima, Japan, Department of Prosthetic Dentistry, The Second Hospital of HebeidMedical University, Shijiazhuang, P. R. China, and Department of Prosthetic Dentistry, Graduate
School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
Purpose: The purpose of this study was to investigate knowledge about denture cleansers of dentists in Japan,
China, and Indonesia.
Materials and Methods: Forty-three dentists from Japan (Hiroshima University), 26 dentists from China (Hebei
Medical University and Wuhan University) and 62 dentists from Indonesia (Airlangga University) weresurveyed by questionnaire about their knowledge and understanding of denture cleansers in this study.
Results: The response rate was 91.6%. Significant differences among the three countries were found for ten
questions. For the question “Have you heard of denture cleansers?”, 100% of Japanese dentists answered “Yes”,
whereas 19.2% of Chinese dentists and 14.5% of Indonesian dentists answered “No”. For the question “Haveyou ever seen denture cleansers in the clinic?”, more than 90% of subjects in Japan answered with “often” or“occasionally”, whereas 69.2% of Chinese dentists and 54.1% of Indonesian dentists answered “No”. For thequestion “Do you think the use of denture cleanser is more effective than a clinical intervention?”, over 90% of
the subjects in Japan answered “Yes”; however, over 55% of subjects in China and over 65% of Indonesian
subjects answered “No”.
Conclusion: The results suggest that dental professionals in China and Indonesia have little knowledge about
denture cleansers. The study confirms that there is a difference in the interest and knowledge about denturecleansers among the three countries of Japan, China, and Indonesia. (Int Chin J Dent 2010; 10: 29-34.)
Key Words: China, dentist, denture cleanser, Indonesia, Japan, questionnaire

Introduction
Denture cleansers have been widely used in prosthodontics to prevent colonization of Candida albicans andrelated Candida species and formation of denture plaque.1-5 However, daily use of denture cleansers can affectthe physical and mechanical properties of denture base materials.6-11
Budtz-Jorgensen12 reported that approximately 65% of the denture wearers in Denmark exhibit signs ofdenture stomatitis. Jagger et al.13 reported that 35% of denture wearers used, or had used, denture cleansers daily.
Gornitsky et al.14 reported that the use of denture cleansers significantly reduced the number of microorganisms
on dentures in a hospitalized geriatric population. Although denture cleansers would be a useful adjunct toremoving stain and reducing biofilm formation on the surface irregularities of dentures, Murdoch-Kinch15 noted
the occurrence of oral mucosal injury caused by denture cleansers.

In addition, denture cleansers causesignificant deterioration of the physical and mechanical properties of denture base materials if not correctly
used.8,10,11
Denture wearers would benefit greatly from a dental professional’s guidance regarding the use of denturecleansers. However, little is known about dentists’ knowledge and experience of denture cleansers. Furthermore,
the knowledge, experience and attitudes towards denture cleansers of dentists in Japan, China, and Indonesia
remain unclear. The purpose of this study was to investigate the interest and knowledge about denture cleansers
of dentists in Japan, China and Indonesia.

29

Hong et al.

Int Chin J Dent 2010; 10: 29-34.

Materials and Methods
In this study, 131 subjects were asked to complete and return a structured questionnaire (Table 1). The
subjects were selected at random from dentists in Japan (Hiroshima University, Hiroshima), China (Hebei
Medical University, Shijiazhuang; Wuhan University, Wuhan) and Indonesia (Airlangga University, Surabaya).
They included 43 Japanese dentists (men, 27; women, 16; mean age: 30.8 years), 26 Chinese dentists (men, 12;
women, 14; mean age: 27.0 years), and 62 Indonesian dentists (men, 30; women, 32; mean age: 38.6 years). The
distribution and collection of the questionnaire was instituted by the members of the survey team in Japan, China,
and Indonesia from 2006 to 2007. This questionnaire was administered after explaining the aim of the survey tothe subjects and gaining their consent.
Table 1. Questionnaire items and percentage distributions of answers by dentists in Japan, China and Indonesia.
Category score

Item descriptions

2

Q 1. Have you heard of denture cleansers?

Q 2. Do you know what the function of a denture cleanser is?

Q 3. Do you know of any disadvantages of denture cleansers?

Q 4. How many imported brands of denture cleanser do you know?

Q 5. How many domestic brands of denture cleanser do you know?

Q 6. Have you ever been taught about denture cleansers?

Q 7. Have you ever seen denture cleansers in books or lecture meetings?

Q 8. Have you ever seen any TV commercials about denture cleansers?

Q 9. Do you know any alternatives to denture cleansers?

Q10. Have you ever seen denture cleansers in the clinic?

Q11. Do you think the use of denture cleanser is more effective than aclinical intervention?

1

χ2 test

0

JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND
JPD
CND
IND

20
1
7
26
1
15
11
1
2
9
0
4
24
0
0
12
0
0
8
1
0
19
0
0
4
0
4
20
0
4

23
20
46
17
20
39
21
5
22
5
3
15
12
1
5
23
8
24
28
4
38
23
0
11
14
0
32
20
8
24

0
5
9
0
5
8
11
20
38
29
23
41
7
24
52
8
18
38
7
21
24
1
26
51
25
26
26
3
18
33

A

C

*

JPD

21

19

3

A

NS

CND
IND

0
11

10
9

13
40

**

A

**

A

**

B

**

B

**

C

**

C

**

C

**

A

**

A 2:Yes, very much, 1:Yes, but only a little, 0:No B 2:Three or more, 1:Less than three, 0:None
C 2:Yes, often, 1:Yes, occasionally, 0:No *: p<0.01 **: p<0.001 NS: Not significant

The questionnaire was written in Japanese and then translated into Chinese and Indonesian. After discussion

30

Hong et al.

Int Chin J Dent 2010; 10: 29-34.

with the staff in Japan, China, and Indonesia, it was decided to retain the same estimation criterion. The
questionnaire consists of 11 questions: five questions about knowledge and comprehension, four questions about
education, and two questions about clinical practice. Each question had three response options; “No” or “None”(score 0), “Yes, but only a little” or “Yes, occasionally” (score 1), and “Yes, very much” or “Yes, often” (score
2).
Chi-square tests were used to examine the differences in the responses for each item on the questionnaire
among the three groups. Then, two stepwise logistic regression analyses were carried out on the dependent
variable (between Japan and China; between Japan and Indonesia; and between China and Indonesia). The Waldstatistic was used to test the null hypothesis that the regression coefficients were zero. The Negelkerke R2statistic was used to discriminate how well the model was able to distinguish between the interest and knowledgeof Japanese, Chinese, and Indonesian dentists. All analyses were computed with SPSS for Windows operating
system (SPSS 16, SPSS Japan Inc., Tokyo, Japan).

Results
The response rate was 91.6%. The response rate of the Japanese dentists was 100% (n=43), that of theChinese dentists was 84.6% (n=22), that of the Indonesian dentists was 88.7% (n=55). Table 1 shows thequestionnaire items and the percentage distributions of the responses. Significant differences among the threegroups were found for ten questions. For the question “Have you heard of denture cleansers?”, 0% of Japanesedentists answered “No”, whereas 19.2% of Chinese dentists and 14.5% of Indonesian dentists answered “No”.
Almost 50% of Japanese subjects (20 people) answered “Yes, very much”. For the question “Do you know what
the function of a denture cleanser is?”, 60.5% of Japanese dentists answered “Yes, very much”, whereas 19.2%
of Chinese dentists and 12.9% Indonesian dentists answered “No”. For the question “Do you know of any
disadvantages of denture cleansers?”, 74.4% of Japanese dentists answered “Yes, very much” or “Yes, but only alittle”, whereas 76.9% of Chinese dentists and 61.3% of Indonesian dentists answered “No”. For the question“How many imported brands of denture cleanser do you know?”, most respondents (67.4% of Japanese; 88.5%
of Chinese and 68.3% of Indonesian) answered “None”. For the question “How many domestic brands ofdenture cleanser do you know?”, 83.7% of Japanese dentists answered “Three or more” or “Less than three”,
whereas 96.0% of Chinese dentists and 91.3% of Indonesian dentists answered “None”. For the questions “Haveyou ever been taught about denture cleansers?”, 69.2% of Chinese dentists and 61.3% of Indonesian dentists
answered “No”. For the questions “Have you ever seen denture cleansers in books or lecture meetings?”, 83.7%
of Japanese dentists and 61.3% of Indonesian dentists answered “Yes”, whereas 80.8% of Chinese dentists
answered “No”. For the question “Have you ever seen any TV commercials about denture cleansers?”, 100% of
Chinese dentists and 82.3% of Indonesian dentists answered “No”. For the question “Have you ever seen
denture cleansers in the clinic?”, 93.0% of Japanese dentists answered “Yes”, whereas 69.2% of Chinese dentists
and 54.1% of Indonesian dentists answered “No”.
Table 2 shows the estimated coefficients and related statistics from the logistic regression model that predicts
group membership (between Japan and Indonesia). The model contained two variables using a forward stepwise
method (P<0.01); Q8 (TV commercials of DC) and Q10 (Seen DC in the clinic); and three variables using a
backward stepwise method (P<0.05); Q5 (Domestic brands of DC), Q8 (TV commercials of DC) and Q10 (Seen
DC in the clinic). Table 3 shows the estimated coefficients and related statistics from the logistic regression

31

Hong et al.

Int Chin J Dent 2010; 10: 29-34.

model that predicts group membership (between China and Indonesia). The model contained two variables
using a backward stepwise method (P<0.1); Q4 (Imported brands of DC) and Q7 (Seen DC in books or lecture
meetings).
Table 2. Results of binary logistic regression analysis using two Wald methods between Japan and Indonesia.
Item No.
Forward stepwise (Wald)
Q 8: TV commercials of DC*
Q10: Seen DC* in the clinic
Backward stepwise (Wald)
Q 5: Domestic brands of DC*
Q 8: TV commercials of DC*
Q10: Seen DC* in the clinic

B

S.E.

Wald
chi-square

FreedomP

Exp (B)

-4.55
-1.87

1.12
0.69

16.44
7.49

1
1

0.000
0.006

0.01
0.15

-2.11
-3.53
-1.66

0.99
1.22
0.79

1.58
8.31
4.40

1
1
1

0.032
0.040
0.036

0.12
0.03
0.19

*denture cleanser. For the forward stepwise method, variables were entered in step 1 to 2：Q8, Q10 in that order.
For the backward stepwise method, variables were removed in steps 1 to 8：Q4, Q5, Q8, Q9, Q10 in that order.

Table 3. Results of binary logistic regression analysis using two Wald methods between China and Indonesia.
Item No.
Backward stepwise (Wald)
Q 4: Imported brands of DC*
Q 7: Seen DC* in books or lecture meetings

B

S.E.

Wald
chi-square

FreedomP

Exp (B)

1.51
1.13

0.84
0.61

3.24
3.38

1
1

0.072
0.066

4.51
3.09

*denture cleanser. For the backward stepwise method, variables were removed in steps 1 to 11：Q4, Q7, Q9 in that order.

Table 4. Observed and predicted group membership using two Wald methods between Japan and China.
Predicted countryGroup
Forward Stepwise (Wald)
Japan
China
Total
Backward Stepwise (Wald)
Japan
China
Total

Japan

China

Percentage correct

42
0

1
22

97.7
100.0
98.5

42
0

1
22

97.7
100.0
98.5

2

The cut value is 0.50. Negalkerke R =0.948 (forward stepwise), 0.948 (backward stepwise).
*Four Chinese dentists were deleted because they did not give complete answers in the questionnaire.

Table 5. Observed and predicted group membership using two Wald methods between Japan and Indonesia.
Group
Forward Stepwise (Wald)Japan
Indonesia
Total
Backward Stepwise (Wald)Japan
Indonesia
Total

Japan

Predicted country
Indonesia

Percentage correct

41
6

2
49

95.3
89.1
91.8

41
2

2
53

95.3
96.4
95.9

2

The cut value is 0.50. Negalkerke R =0.804 (forward stepwise), 0.861 (backward stepwise).
*Seven Indonesian dentists were deleted because they did not give complete answers in the questionnaire.

Table 4 shows that 42 Japanese dentists (97.7%) were correctly predicted using the forward stepwise method.
Similarly, 22 Chinese dentists (100%) were correctly predicted. The Nagelkerke R2 statistic was 0.948; that is,32

Hong et al.

Int Chin J Dent 2010; 10: 29-34.

94.8% of the variation in the outcome variable was explained by the logistic regression model.
Table 5 shows that 41 Japanese dentists (95.3%) were correctly predicted using the forward stepwise method.
Similarly, 49 Indonesian dentists (89.1%) were correctly predicted. The Nagelkerke R2 statistic was 0.804; thatis, 80.4% of the variation in the outcome variable was explained by the logistic regression model.
Table 6 shows that 15 Chinese dentists (68.2%) were correctly predicted using the forward stepwise method.
Similarly, 47 Indonesian dentists (85.5%) were correctly predicted. The Nagelkerke R2 statistic was 0.518; thatis, 51.8% of the variation in the outcome variable was explained by the logistic regression model.
Table 6. Observed and predicted group membership using two Wald methods between China and Indonesia.
Group

China

Forward Stepwise (Wald)
China
Indonesia
Total
Backward Stepwise (Wald)
China
Indonesia
Total

Predicted country
Indonesia

Percentage correct

0
0

22
55

0.0
100.0
71.4

15
8

7
47

68.2
85.5
80.5

2

The cut value is 0.50. Negalkerke R =0.393 (forward stepwise), 0.518 (backward stepwise). *Four Chinese dentists and sevenIndonesia dentists were deleted because they did not give complete answers in the questionnaire.

Discussion
Denture cleansers are widely used by denture wearers to remove plaque, stain and calculus form the surface ofdentures.1-5 In the clinic, patients would benefit greatly from a dentist’s guidance in the use of denture cleansers.
This study was designed to survey the knowledge, understanding and level of education about denture cleansers
among Japanese, Chinese, and Indonesian dentists.
More than 76% of Chinese dentists and more than 62% of dentists in Indonesia said that they had heard only alittle about denture cleansers and that they knew only a little of the function of denture cleansers. Furthermore,
more than 76% of dentists in China and more than 61% of Indonesian dentists answered that they did not knowof any disadvantages of denture cleansers. It is important for dentists to be familiar with the disadvantages ofdenture cleansers; in particular, the risk of deterioration of the physical and mechanical properties of denturebase materials and oral mucosal injury caused by inappropriate use of denture cleansers.15

Professional

education about denture cleansers is therefore necessary. Almost none of the dentists in China and Indonesia
knew of any domestic brands of denture cleanser. In China and Indonesia, there are practically no domestic
manufacturers of denture cleansers, and denture cleansers are mainly imported. This may be why so many
dentists in China and Indonesia did not know of any domestic brands.
Over 61% of dentists in China and Indonesia responded that they had never been taught about denturecleansers, and between 80% and 100% of Chinese dentists had never encountered denture cleansers in books,
lecture meetings or on television. Information about denture cleansers often comes from textbooks and lectures,but dentists often encounter this information only in technical journals and specialty books. In China andIndonesia, there have been few reports about problems caused by denture cleansers. Therefore, problems arisingfrom the improper use of denture cleansers, such as deterioration of the physical and mechanical properties ofdenture base materials and oral mucosal injury, may be prevented by raising dental professionals’ awareness and33

Hong et al.
knowledge of denture cleansers.

Int Chin J Dent 2010; 10: 29-34.
We suggest that it is particularly important to teach dentists about theadvantages and disadvantages of denture cleansers in professional continuing education and training.
Over 69% of the dentists in Chinese and over 54% of the Indonesian dentists stated that they had never seen
denture cleansers in the clinic. There are various environmental differences among the three countries. These
differences could affect dental treatment, and could affect the use of denture cleansers.
Some limitations can be identified in this study.

Firstly, indirect translation of the questionnaire fromJapanese to Chinese and Indonesian might have influenced the results. Secondly, the sample sizes were small.
Thirdly, there were significant differences in age among the three groups of subjects. It is unknown whether the
results can be generalized to other samples; therefore, it is necessary to conduct future research over morediverse samples. Although caution should be exercised in making generalizations based on the results of thisstudy, the questionnaire is a starting point for investigating the awareness and knowledge of dentists in Japan,
China, and Indonesia about denture cleansers. These methods may be useful for comparing awareness ofdenture cleansers among other groups, and may further contribute to the evaluation of denture cleansers.
Acknowledgment
This research was supported in part by a Grant-in-Aid for Scientific Research (21791899) from the Ministry of Education,
Culture, Sports, Science and Technology, Japan.

References
1.
2.
3.
4.

David H, Anthony DMD, Paul Gibbons BS. The nature and behavior of denture cleansers. J Prosthet Dent 1958; 8: 796-810.
David CA. Denture plaque and denture cleansers. J Prosthet Dent 1981; 45: 376-9.
Koopmans AS, Kippuw N, de Graaff J. Bacterial involvement in denture-induced stomatitis. J Dent Res 1988; 67: 1246-50.
Nikawa H, Hamada T, Yamamoto T, Kumagai H. Effects of salivary or serum pellicles on the Candida albicans growth andbiofilm formation on soft lining materials in vitro. J Oral Rehabil 1997; 24: 594-604.
5. Nikawa H, Hamada T, Yamashiro H, Kumagai H. A review of in vitro and in vivo methods to evaluate the efficacy of denturecleansers. Int J Prosthodont 1999; 12: 153-9.
6. Backenstose WM, Wells JG. Side effects of immersion-type cleansers on the metal components of dentures. J Prosthet Dent
1977; 37: 615-21.
7. Purnaveja S, Fletcher AM, Ritchie GM, Amin WM, Moradians S, Dodd AW. Compatibility of denture cleansers with some new
self curing denture base materials. Biomaterials 1982; 3: 251-2.
8. Nikawa H, Iwanaga H, Hamada T, Yuhta S. Effects of denture cleansers on direct soft denture lining materials. J Prosthet
Dent 1994; 72: 657-62.
9. Rodrigues Garcia RCM, Léon BLT, Oliveira VMB, Del Bel Cury AA. Effect of a denture cleanser on weight, surface roughness,and tensile bond strength of two resilient denture liners. J Prosthet Dent 2003; 89: 489-94.
10. Hong G, Murata H, Li YA, Sadamori S, Hamada T. Influence of denture cleansers on the color stability of three types ofdenture base acrylic resin. J Prosthet Dent 2009; 101: 205-13.
11. Amanda P, Letícia RD, Nathália de QR, Raphael Freitas de S, Cláudia Helena Lovato da S, Helena de FOP. Effect of denturecleansers on physical properties of heat-polymerized acrylic resin. J Prosthodont Res 2010; 54: 78-83.
12. Budtz-Jorgensen E. Clinical aspects of Candida infection in denture wearers. J Am Dent Assoc 1978; 96: 474.
13. Jagger DC, Harrison A. Denture cleansing—the best approach. Br Dent J 1995; 178: 413-7.
14. Gornitsky M, Paradis I, Landaverde G, Malo AM, Velly AM. A clinical and microbiological evaluation of denture cleansers for
geriatric patients in long-term care institutions. J Can Dent Assoc 2002; 68: 39-45.
15. Murdoch-Kinch CA, Mallattn ME, Miles DA. Oral mucosal injury caused by denture cleanser tablets—A case report. Oral Surg
Oral Med Oral Pathol Oral Radiol Endod 1995; 80: 756-8.

Correspondence to:
Dr. Guang Hong
Department of Oral Health Care Promotion, Graduate School of Dentistry, Tohoku University
4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
Fax: +81-22-717-8345 E-mail: hong@m.tains.tohoku.ac.jp
Accepted June 7, 2010.

Copyright ©2010 by the International Chinese Journal of Dentistry.

34