Usefulness of the masticatory score by occlusal support

Abstract

This study aimed to clarify the usefulness of masticatory score by occlusal support. A total of 605 adults were classified into four groups (A1, A2A3, B, and C) according to the Eichner classification, and the relationship between the amount of glucose eluted and masticatory score was investigated in each group. A significant correlation between the glucose eluted and masticatory score was observed in groups A2A3, B, and C, but not in A1, suggesting that the masticatory score is useful for evaluating the masticatory performance of complete denture wearers, but not adults with natural dentition.

Introduction

Masticatory performance can be evaluated using both subjective and objective measures, both of which are widely applied clinically.

To subjectively evaluate masticatory performance, attempts have been made to investigate food intake ability using food intake questionnaires. Recently, a questionnaire investigating the ability to eat 20 or 25 different types of food has been widely used to evaluate masticatory performance [1,2,3,4,5,6,7].

Measuring the amount of glucose eluted after chewing gummy jelly containing glucose has been proposed as an objective method for evaluating masticatory performance [8]. This method has been widely used because it can be easily measured and its usefulness has been confirmed. Masticatory performance is affected by occlusal support and is significantly reduced even if one molar is missing [9].

Although it is reasonable to use objective rather than subjective examinations to assess masticatory performance, objective methods require an analytical device. In contrast, a subjective examination can be performed without a special device. It has also been reported that a subjective examination can be substituted for an objective examination, because there is a significant positive correlation between subjective and objective masticatory performances.

The masticatory score has been used mainly for removable denture wearers, but recently it has been used for elderly adults including those with natural dentition, and a positive correlation between masticatory score and objective masticatory performance has been reported [4,6]. These findings suggest that the masticatory score may be useful for evaluating masticatory performance even in adults with natural dentition. However, in order to clarify this, it is necessary to investigate the relationship between the masticatory score and objective masticatory performance for each occlusal support.

Therefore, this study assessed the relationship between masticatory score (subjective masticatory performance) and amount of glucose eluted (objective masticatory performance) in adults to clarify the usefulness of the masticatory score by occlusal support.

Material and Methods

Ethics statement

This study was approved by the Ethics Committee of The Nippon Dental University School of Life Dentistry (approval number: NDU-T2020-31). Informed consent was obtained from all participants after the purpose of the study was explained.

Participants

In total, 605 healthy adults (242 males and 363 females) participated in this study. The participants included adults who had participated in the Kita Ward Food Education Fair sponsored by Kita Ward, Tokyo, as well as the staff and students of The Nippon Dental University.

The selection criteria were as follows: 1) independent living; 2) adequate cognitive function; and 3) no clinical abnormalities in the masticatory system. A dentist with more than 10 years of clinical experience conducted interviews and intraoral examinations, and selected participants who were not dissatisfied with their occlusion and whose degree of tooth mobility was 1 or less (Miller's classification of tooth mobility).

Objective masticatory performance

Before the experiment, the participants were asked to freely chew a gummy jelly, and to indicate the side that was easier to chew on in order to identify the habitual chewing side.

The participants were asked to chew a gummy jelly (Glucolumn, GC Inc., Tokyo, Japan) on their habitual chewing side for 20 s. Thereafter, they were asked to hold 10 mL of water in their mouth, and then spit the water into a cup with a filter. The filtrate in the cup was collected as a test sample, and the amount of glucose eluted was measured using a glucose-measuring device (GS-II, GC Inc.). The measured value was used as a parameter of objective masticatory performance.

Subjective masticatory performance

After asking the participants about their intake of 20 or 25 types of food, mastication score 1 (MS1) was calculated using the method described by Sato et al. [1], and MS2 was calculated using the method described by Koshino et al. [2].

Based on mastication difficulty, 20 foods classified into 5 classes of 4 foods each were selected for MS1, and 25 foods classified into 5 classes of 5 foods each were selected for MS2 (Table 1).

MS1 is the value obtained by multiplying the number of foods with ○ (“can eat easily”) responses out of the 20 foods by 5.

For MS2, of the 25 foods, 2 points were given to foods with “can be eaten normally” responses, 1 point was given to “can be eaten but with difficultly” and 0 points for “cannot be eaten”. Next, after excluding the foods with responses such as “I don’t like it, or I haven’t eaten it” and responses that were left blank, the average score (A-E) was calculated using the following formula: MS2 = (A + 1.06B + 1.22C + 1.39D + 2.23E) / 13.8 × 100.

Table 1 Foods used for the food intake questionnaire

Grade	I	II	III	IV	V
MS 1	boiled carrot	burdock	pickled radish	fresh ear shell	whole apple
	boiled potato	potato chips	peanuts	hard pickled radish	chewing gum
	boiled eggplant	boiled fish-paste (kamaboko)	beef steak	hard cracker	dried shell ligament
	bean curd (tofu)	artificially-grown soybean	rice-cake cubes	hard biscuit	dried cuttlefish
MS 2	bananas	strawberries	fried chicken	roast pork	takuwan
	boiled carrots	ham	roast chicken	pickled radish	raw carrots
	boiled taro	fishpaste patty	pickled eggplants	rice cakes	vinegared octopus
	boiled onions	konnyaku	apples	peanuts	dried cuttlefish
	boiled cabbage	boiled kombu	raw cabbage	sliced raw cuttlefish	raw abalone

Statistical analysis

The occlusal support status of all the participants was classified into groups A, B, and C according to the Eichner classification. Group A was further divided into A1 (without missing teeth) and A2A3 (with missing teeth). The relationship between the masticatory score and amount of glucose eluted in each group was then assessed. Spearman’s correlation coefficient was used to evaluate the correlations. All data were analyzed using the Statistical Package for the Social Sciences (Windows 27.0; IBM Corp., Armonk, NY, USA). Statistical significance was set at P < 0.05.

Results

The values of MS1, MS2, and amount of glucose eluted were highest in the A1 group and decreased consistently in groups A2A3, B, and C (Table 2).

A significant correlation was observed between amount of glucose eluted and MS1, between amount of glucose eluted and MS2 in the A2A3, B, and C groups; however, no significant correlation was observed in the A1 group (Fig. 1).

Table 2 Participant information, number of molar occlusal supports, masticatory score, and amount of glucose eluted

	A1	A2A3	B	C
Number of participants	221	104	167	113
Number of participantswith denture	0	0	144	113
Range of age (years)	20-85	31-89	55-89	36-92
Mean ± SD of age (years)	49.9 ± 16.8	61.8 ± 14.3	74.1 ± 7.0	77.3 ± 7.9
Mean ± SD of MOSN (number)	8	6.5 ± 0.9	2.9 ± 2.0	0
Mean ± SD of MS1 (score)	97.1 ± 5.7	93.4 ± 10.4	83.4 ± 18.4	66.3 ± 20.1
Mean ± SD of MS2 (score)	99.6 ± 1.4	97.7 ± 5.4	91.2 ± 12.7	78.3 ± 17.8
Mean ± SD of AGE (mg/dL)	211.7 ± 38.5	195.3 ± 47.3	151.9 ± 46.7	118.9 ± 44.0

SD, standard deviation; MOSN, number of molar occlusal supports; MS, masticatory score; AGE, amount of glucose eluted

Fig. 1

Correlation coefficient between the amount of glucose eluted and masticatory score in the A1, A2A3, B, and C groups

Discussion

Several studies have investigated the relationship between subjective and objective masticatory performances in patients with removable dentures. However, this study is the first to investigate the relationship between the two by occlusal support in adults, including those with complete natural dentition (A1).

If the relationship between the masticatory score (subjective masticatory performance) and objective masticatory performance is significant, it is considered that the masticatory score can be substituted for an objective masticatory performance test or used as a screening test for masticatory performance.

Correlation coefficients showing the relationship between subjective and objective masticatory performances have been reported to be 0.62-0.759 [2,3] for complete denture wearers and 0.48-0.580 [5,7] for complete denture wearers and partial denture wearers. The results of the present study also showed that the correlation coefficients between MS1 and MS2 were 0.569 and 0.601 in Group C, where many participants wore complete dentures, and 0.361 and 0.324 in Group B, where many participants wore partial dentures, which is almost consistent with the results of previous studies. Thus, it may be said that the masticatory score is useful for the evaluation of masticatory performance in removable denture wearers. The correlation coefficients for complete denture wearers and partial denture wearers [5,7] are smaller than that of only complete denture wearers [2,3], and the correlation coefficient in group B, which did not include complete denture wearers, was even smaller. Based on these findings, it is unclear whether the masticatory score is useful for evaluating masticatory performance in partial denture wearers.

The correlation coefficients of MS1 and MS2 in the A2A3 group were 0.230 and 0.204, respectively, indicating a significant positive correlation. However, no significant correlation was observed between the two in the A1 group. Furthermore, in the A2A3 group, the correlation coefficient was even smaller than that in the B group. A previous study [4] that investigated the relationship between masticatory score (MS2) and objective masticatory performance (amount of glucose eluted) in the elderly reported a weak but significant correlation (r = 0.388) between the two. In a study [6] of dentate adults and denture wearers, the correlation coefficient between subjective and objective masticatory performances was 0.515; however, masticatory scores differed significantly according to the number of remaining teeth. Notably, the group with eight or more natural teeth had the highest mastication score. This report suggests that the correlation between subjective and objective masticatory performances is related to the number of remaining teeth and the masticatory score.

The masticatory scores (MS1 and MS2) had a ceiling effect with mean values (standard deviation) of 97.1 (5.7) and 99.6 (1.4) in the A1 group and 93.4 (10.4) and 97.7 (5.4) in the A2A3 group. In group B, the values were 83.4 (18.4) and 91.2 (12.7), which indicated a similar ceiling effect. A lack of correlation between the two methods in the A1 group with complete natural dentition was observed because masticatory performance could not be evaluated owing to the ceiling effect of the masticatory score when there were many remaining teeth. In addition, it should be noted that the masticatory performance could not be evaluated in the A2A3 and B groups due to the ceiling effect. On the other hand, regarding the amount of glucose eluted, after chewing 2 g (2,000 mg) of gummy jelly containing 5% (100 mg) of glucose, participants were asked to hold 10 mL (0.1 dL) of water and spit it out; thus, the calculated upper limit is 1,000 mg/dL. However, even in group A1, which had the highest value, the amount of glucose eluted was 211.7 ± 38.5 mg/dL, indicating the absence of the ceiling effect.

These findings suggest that the masticatory score was useful for evaluating the masticatory performance of complete denture wearers, but not adults with natural dentition. Thus, the evaluation should be performed with caution when occlusal support is present.

Conflict of Interest

The authors declare that they have no conflict of interest.

References

• 1.  Sato Y, Minagi S, Akagawa Y, Nagasawa T (1989) An evaluation of chewing function of complete denture wearers. J Prosthet Dent 62, 50-53.
• 2.  Koshino H, Hirai T, Toyoshita Y, Yokoyama Y, Tanaka M, Iwasaki K et al. (2008) Development of new food intake questionnaire method for evaluating the ability of mastication in complete denture wearers. Prosthodont Res Pract 7, 12-18.
• 3.  Shiga H, Ishikawa A, Nakajima K, Tanaka A (2015) Relationship between masticatory performance using a gummy jelly and food intake ability in Japanese complete denture wearers. Odontology 103, 356-359.
• 4.  Fujimoto K, Suito H, Nagao K, Ichikawa T (2020) Does masticatory ability contribute to nutritional status in older individuals? Int J Environ Res Public Health 17, 7373.
• 5.  Suwanarpa K, Hasegawa Y, Salazar S, Kikuchi S, Yoshimoto T, Paphangkorakit J et al. (2021) Can masticatory performance be predicted by using food acceptance questionnaire in elderly patients with removable dentures? J Oral Rehabil 48, 582-591.
• 6.  Fan Y, Shu X, Lo ECM, Leung KCM (2021) Development and validation of a chewing function questionnaire for Chinese older adults. J Dent 104, 103520.
• 7.  Yokoyama M, Shiga H, Uesugi H, Sano M, Nakajima K (2023) Usefulness of newly devised food intake score in removable denture wearers. J Oral Rehabil, Feb 18, doi: 10.1111/joor.13436.
• 8.  Shiga H, Nakajima K, Uesugi H, Komino M, Sano M, Arai S (2022) Reference value of masticatory performance by measuring the amount of glucose extraction from chewing gummy jelly. J Prosthodont Res 66, 618-622.
• 9.  Tanaka Y, Shiga H (2018) Masticatory performance of the elderly as seen from differences in occlusal support of residual teeth. J Prosthodont Res 62, 375-378.