Odontology DOI 10.1007/s10266-014-0170-5
SHORT COMMUNICATION
Relationship between masticatory performance using a gummy jelly and food intake ability in Japanese complete denture wearers Hiroshi Shiga • Ayano Ishikawa • Kunihisa Nakajima Akira Tanaka
•
Received: 11 March 2014 / Accepted: 11 July 2014 Ó The Society of The Nippon Dental University 2014
Abstract Twenty patients wearing complete dentures were asked to chew a gummy jelly, and their glucose extraction was measured. Two types of masticatory scores (MS1 and MS2) were calculated using a food intake questionnaire. The relationship between masticatory scores and glucose extraction was investigated. The values of masticatory scores were large when the amount of glucose extraction was also large, and there were significantly positive correlations between the two. There was also a positive correlation between MS1 and MS2. It was suggested that the food intake ability was high when the masticatory performance using a gummy jelly was high. Keywords Complete dentures Gummy jelly Glucose extraction Masticatory performance Masticatory score
Introduction Masticatory performance is an important indicator in the evaluation of masticatory function. As the subjective method of evaluating masticatory performance, the attempt to investigate food intake ability using a food intake questionnaire has been long established [1–4]. The attempt to replace the results of the questionnaire with actual values has been made, and results have shown that high values indicate that food intake ability is high.
On the other hand, the attempt to objectively evaluate masticatory performance has also been made. The sieve method wherein a certain quantity of test food is chewed specific number of times and then retrieved and measured with sieves of various mesh sizes is used as the standard method of evaluating masticatory performance [5]. However, in recent years, because this method is complicated and time consuming, other relatively simpler methods using silicone impression materials, chewing gum, paraffin wax, and gummy jelly have been used [6– 15]. Of these methods, the measurement of glucose extraction during the chewing of gummy jelly has received much attention for several reasons. It is easy to use and is hygienic, and the shape and characteristics of gummy jelly can be easily standardized. A positive correlation has been reported between masticatory performance measured by the amount of glucose extraction and that measured by the sieve method [9]. However, it has not been clarified whether an individual’s ability to masticate a gummy jelly, representing a relatively soft food item, successfully results in the ability to masticate many types of foods. Therefore, in this study, the relationship between masticatory performance and food intake ability in complete denture wearers who were sufficiently satisfied with their dentures was investigated.
Methods
H. Shiga (&) A. Ishikawa K. Nakajima A. Tanaka Department of Partial and Complete Denture, The Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda, Tokyo 102-8159, Japan e-mail: [email protected]
All experimental procedures were approved by the Ethics Committee of Nippon Dental University School of Life Dentistry at Tokyo (NDU-T2013-14). Informed consent was obtained from all participants after they were provided with an explanation about the general nature of the study.
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Odontology
Subjects Twenty patients (10 males and 10 females, 65–88 years of age; average, 74.4 years) wearing complete dentures were selected as study subjects. The following selection criteria were applied. Participants had to have the ability to recognize their habitual chewing side, they had to wear a denture with a proper flange and occlusal contact for over 3 months, and they had to be sufficiently satisfied with their dentures as assessed by a subjective assessment scale (total assessment as to esthetics, speech, eating ability, and stability). When the degree of satisfaction of the denture was measured by a 10-cm visual analog scale (VAS, 10 = optimal), the result was 9.0 or above for all subjects.
chew’’, and ‘‘impossible to chew.’’ The 20 foods were categorized into 5 grades according to masticatory difficulty. The percentage of ‘‘easy to chew’’ foods was then calculated as the masticatory score (MS1) (Table 1). Method of calculating MS2 The subjects were asked to assign the state of intake (2–0, 4, h) for each of the 25 foods, categorized into 5 grades according to masticatory difficulty. Average scores for 5 foods in each grade, except for foods marked ‘‘4’’ or ‘‘h’’,
Table 1 Calculation of the masticatory score 1
Test food
Group
Foods
The test food was a cylindrically shaped gummy jelly with a diameter of 14 mm, height of 10 mm, and weight of 2.3 g.
I
Whole apple, chewing gum, dried shell ligament, dried cuttlefish
II
Fresh ear shell, hard pickled radish, hard cracker, hard biscuit
Recording method
III
Pickled radish, peanuts, beef steak, rice-cake cubes
IV
Burdock, potato chips, boiled fish paste (kamaboko), artificially grown soybean
V
Boiled carrot, boiled potato, boiled eggplant, bean cured (toufu)
Masticatory performance Subjects were asked to sit in a dental chair with the Frankfort plane parallel to the floor with their heads not fixed but in a relaxed state, and were asked to chew gummy jelly on their habitual chewing side for 20 s. After chewing, the subjects were asked to hold 10 ml of distilled water in their mouths for a moment and to spit into a cup. The cup containing the gummy jelly and the saliva was then filtered, and the filtrate was collected. For the evaluation of masticatory performance, the glucose concentration in the filtrate was measured as glucose extraction by means of a glucose testing device (GS-1Ò; Fujita, Tokyo, Japan). The recording of chewing was done two times and their average was used for analysis. Masticatory score Two types of masticatory scores were measured using a food intake questionnaire. Subjects were asked the state of intake for 20 foods selected by Sato et al. [1] and 25 foods selected by Koshino et al. [2]. The masticatory score was then calculated as MS1 according to the method of Sato et al. [1] and as MS2 according to the method of Koshino et al. [2]. Method of calculating MS1 The subjects were asked to assign the state of intake for each of the 20 foods as ‘‘easy to chew’’, ‘‘difficult to
123
Check as follows s: easy to chew, 4: difficult to chew, 9: Impossible to chew Masticatory score = number of s/20 9 100 (%)
Table 2 Calculation of the masticatory score 2 Difficulty grade
Difficulty ratio
Average pointa
Foods
I
1.00
A
Bananas, boiled cabbage, boiled carrots, boiled taro, boiled onions
II
1.06
B
Strawberries, ham, boiled fish paste, konnyaku, boiled kombu
III
1.22
C
Fried chicken, roast chicken, apples, pickled eggplants, raw cabbage
IV
1.39
D
Roast pork, pickled radish, rice cakes, peanuts, sliced raw cuttlefish
V
2.23
E
Raw carrots, takuwan, vinegared octopus, raw abalone, dried cuttlefish
Check as follows 2: easily eaten, 1: eaten with difficulty, 0: cannot be eaten, 4: do not eat because of dislike, h: have not eaten since starting to wear dentures Masticatory 13.8 9 100 (%) a
score = (A ? 1.06B ? 1.22C ? 1.39D ? 2.23E)/
Average point = average points for 5 foods expect for foods marked ‘‘4’’ or ‘‘h’’ in each grade
Odontology Fig. 1 The relationship between masticatory scores and glucose extraction
were calculated. Average scores (A–E) in each grade were multiplied by a corresponding coefficient (difficulty ratio). Finally, the total score was determined as the masticatory score (MS2) according to the following formula: MS2 = (A ? 1.06B ? 1.22C ? 1.39D ? 2.23E)/ 13.8 9 100 (Table 2), where ‘‘2’’ = easy eaten, ‘‘1’’ = eaten with difficulty, ‘‘0’’ = cannot be eaten, ‘‘4’’ = do not eat because of dislike, and ‘‘h’’ = have not eaten since I started wearing dentures.
Method of analysis Data were analyzed using a statistical software (SPSS for Windows 10.0J, SPSS; Chicago, IL, USA). P values \0.05 were considered to be significant. First, the relationship between masticatory scores (MS1 and MS2) and glucose extraction was investigated. Next, the relationship between MS1 and MS2 was investigated. Pearson’s correlation coefficient test was used.
Results The average values for MS1, MS2, and amount of glucose extraction were 63.3 % (SD, 17.3 %), 75.5 % (SD, 16.0 %), and 180.3 mg/dl (SD, 36.8 mg/dl), respectively. The value of masticatory scores was high when the amount of glucose extraction was large, and there was a significantly positive correlation between the two (MS1, r = 0.759; P \ 0.01, MS2, r = 0.667; P \ 0.01) (Fig. 1). There was also a positive correlation between MS1 and MS2 (r = 0.886; P \ 0.01).
**
**
Discussion Because food preferences differ with countries, each country uses its own foods while examining food intake ability using a food intake questionnaire. In Japan, Yamamoto’s method of examination has been the long-time method of choice. However, from the numerous types of foods available, Sato et al. [1] selected 20 and Koshino et al. [2] selected 25 food items for evaluation. From the intake conditions of these foods, masticatory scores were calculated, and quantitative evaluations of masticatory performance by food intake ability were attempted. These were indicated to be very useful. Therefore, in this study, the relationship between masticatory scores and glucose extraction was investigated. It was found that the masticatory score was high when the glucose extraction was high, and there were significantly positive correlations. These results may indicate that many types of foods can be masticated when the value of masticatory performance recorded with a gummy jelly was large. Koshino et al. [2] confirmed that there was a significant correlation between the masticatory score and the masticatory performance when the sieving method was used. Jeong et al. [4] reported that there was a moderate correlation between subjective food intake ability and objective masticatory performance. From these reports and our results, it could be hypothesized that food intake ability was high when the value of masticatory performance was high, although only a single food was used for the evaluation of masticatory performance. The finding of a highly significant positive correlation between the masticatory score (MS1) of Sato et al. [1] and that (MS2) of Koshino et al. is interesting. Although Sato et al. [1] used 20 and Koshino et al. [2] used 25 types of
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Odontology
food, common foods were not used. What was common to both, however, was that both classified the foods into 5 different grades of chewing difficulty; Sato et al. [1] chose 4 types of food from each grade, and Koshino et al. [2] chose 5 types of food. From these facts, it could be inferred that even if the selections of food were different, if one selected equally from easy-to-chew foods and more difficult-to-chew foods, then one can probably evaluate masticatory performance fairly. To calculate the masticatory score, Koshino et al. [2] used their own formula, though the basis for the coefficient used in the formula was not mentioned in the article. However, from the fact that the more difficult-to-chew food had a larger coefficient, it can be surmised that the formula was set so that the score would be large if the more difficult-to-chew food can be chewed. To summarize this study, in the measurement of masticatory performance based on the amount of glucose extraction during the chewing of gummy jelly, a high extraction value means that the individual’s food intake ability is high and that many types of foods can be masticated.
Conflict of interest exist.
The authors declare that no competing interests
References 1. Sato Y, Minagi S, Akagawa Y, Nagasawa T. An evaluation of chewing function of complete denture wearers. J Prosthet Dent. 1989;62:50–3. 2. Koshino H, Hirai T, Toyoshita Y, Yokoyama Y, Tanaka M, Iwasaki K, Hosoi T. Development of new food intake questionnaire method for evaluating the ability of mastication in complete denture wearers. Prosthodont Res Pract. 2008;7:12–8.
123
3. Ueno M, Yanagisawa T, Shinada K, Ohara S, Kawaguchi Y. Masticatory ability and functional tooth units in Japanese adults. J Oral Rehabil. 2008;35:337–44. 4. Jeong SH, Kang SM, Ryu JH, Kwon HK, Kim BI. Subjective food intake ability in relation to the Mixing Ability Index in Korean adults. J Oral Rehabil. 2010;37:242–7. 5. Manly RS, Braley LC. Masticatory performance and efficiency. J Dent Res. 1950;29:448–62. 6. Van der Bilt A, Van der Glas HW, Olthoff LW, Bosman F. The effect of particle size reduction on the jaw gape in human mastication. J Dent Res. 1991;70:931–7. 7. Anastassiadou V, Heath MR. The development of a simple objective test of mastication suitable for older people, using chewing gums. Gerodontology. 2001;18:79–86. 8. Shiga H, Kobayashi Y, Arakawa I, Yokoyama M, Unno M. Validation of a portable blood glucose testing device in measuring masticatory performance. Prosthodont Res Pract. 2006;5:15–20. 9. Kobayashi Y, Shiga H, Arakawa I, Yokoyama M. The effectiveness of measuring glucose extraction for estimating masticatory performance. Prosthodont Res Pract. 2006;5:104–8. 10. Ikebe K, Matsuda K, Morii K, Furuya-Yoshinaka M, Nokubi T, Renner RP. Association of masticatory performance with age, posterior occlusal contacts, occlusal force, and salivary flow in older adults. Int J Prosthodont. 2006;19:475–81. 11. Lepley CR, Throckmorton GS, Ceen RF, Buschang PH. Relative contributions of occlusion, maximum bite force, and chewing cycle kinematics to masticatory performance. Am J Orthod Dentofacial Orthop. 2011;139:606–13. 12. Toman M, Toksavul S, Saracoglu A, Cura C, Hatipoglu A. Masticatory performance and mandibular movement patterns of patients with natural dentitions, complete dentures, and implantsupported overdentures. Int J Prosthodont. 2012;25:135–7. 13. Gonc¸alves TM, Campos CH, Gonc¸alves GM, de Moraes M, Rodrigues Garcia RC. Mastication improvement after partial implant-supported prosthesis use. J Dent Res. 2013;92:189S–94S. 14. Piancino MG, Frongia G, Dalessandri D, Bracco P, Ramieri G. Reverse cycle chewing before and after orthodontic-surgical correction in class III patients. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;115:328–31. 15. Endo T, Komatsuzaki A, Kurokawa H, Tanaka S, Kobayashi Y, Kojima K. A two-colored chewing gum test for assessing masticatory performance: a preliminary study. Odontology. 2014;102:68–75.
SHORT COMMUNICATION
Relationship between masticatory performance using a gummy jelly and food intake ability in Japanese complete denture wearers Hiroshi Shiga • Ayano Ishikawa • Kunihisa Nakajima Akira Tanaka
•
Received: 11 March 2014 / Accepted: 11 July 2014 Ó The Society of The Nippon Dental University 2014
Abstract Twenty patients wearing complete dentures were asked to chew a gummy jelly, and their glucose extraction was measured. Two types of masticatory scores (MS1 and MS2) were calculated using a food intake questionnaire. The relationship between masticatory scores and glucose extraction was investigated. The values of masticatory scores were large when the amount of glucose extraction was also large, and there were significantly positive correlations between the two. There was also a positive correlation between MS1 and MS2. It was suggested that the food intake ability was high when the masticatory performance using a gummy jelly was high. Keywords Complete dentures Gummy jelly Glucose extraction Masticatory performance Masticatory score
Introduction Masticatory performance is an important indicator in the evaluation of masticatory function. As the subjective method of evaluating masticatory performance, the attempt to investigate food intake ability using a food intake questionnaire has been long established [1–4]. The attempt to replace the results of the questionnaire with actual values has been made, and results have shown that high values indicate that food intake ability is high.
On the other hand, the attempt to objectively evaluate masticatory performance has also been made. The sieve method wherein a certain quantity of test food is chewed specific number of times and then retrieved and measured with sieves of various mesh sizes is used as the standard method of evaluating masticatory performance [5]. However, in recent years, because this method is complicated and time consuming, other relatively simpler methods using silicone impression materials, chewing gum, paraffin wax, and gummy jelly have been used [6– 15]. Of these methods, the measurement of glucose extraction during the chewing of gummy jelly has received much attention for several reasons. It is easy to use and is hygienic, and the shape and characteristics of gummy jelly can be easily standardized. A positive correlation has been reported between masticatory performance measured by the amount of glucose extraction and that measured by the sieve method [9]. However, it has not been clarified whether an individual’s ability to masticate a gummy jelly, representing a relatively soft food item, successfully results in the ability to masticate many types of foods. Therefore, in this study, the relationship between masticatory performance and food intake ability in complete denture wearers who were sufficiently satisfied with their dentures was investigated.
Methods
H. Shiga (&) A. Ishikawa K. Nakajima A. Tanaka Department of Partial and Complete Denture, The Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda, Tokyo 102-8159, Japan e-mail: [email protected]
All experimental procedures were approved by the Ethics Committee of Nippon Dental University School of Life Dentistry at Tokyo (NDU-T2013-14). Informed consent was obtained from all participants after they were provided with an explanation about the general nature of the study.
123
Odontology
Subjects Twenty patients (10 males and 10 females, 65–88 years of age; average, 74.4 years) wearing complete dentures were selected as study subjects. The following selection criteria were applied. Participants had to have the ability to recognize their habitual chewing side, they had to wear a denture with a proper flange and occlusal contact for over 3 months, and they had to be sufficiently satisfied with their dentures as assessed by a subjective assessment scale (total assessment as to esthetics, speech, eating ability, and stability). When the degree of satisfaction of the denture was measured by a 10-cm visual analog scale (VAS, 10 = optimal), the result was 9.0 or above for all subjects.
chew’’, and ‘‘impossible to chew.’’ The 20 foods were categorized into 5 grades according to masticatory difficulty. The percentage of ‘‘easy to chew’’ foods was then calculated as the masticatory score (MS1) (Table 1). Method of calculating MS2 The subjects were asked to assign the state of intake (2–0, 4, h) for each of the 25 foods, categorized into 5 grades according to masticatory difficulty. Average scores for 5 foods in each grade, except for foods marked ‘‘4’’ or ‘‘h’’,
Table 1 Calculation of the masticatory score 1
Test food
Group
Foods
The test food was a cylindrically shaped gummy jelly with a diameter of 14 mm, height of 10 mm, and weight of 2.3 g.
I
Whole apple, chewing gum, dried shell ligament, dried cuttlefish
II
Fresh ear shell, hard pickled radish, hard cracker, hard biscuit
Recording method
III
Pickled radish, peanuts, beef steak, rice-cake cubes
IV
Burdock, potato chips, boiled fish paste (kamaboko), artificially grown soybean
V
Boiled carrot, boiled potato, boiled eggplant, bean cured (toufu)
Masticatory performance Subjects were asked to sit in a dental chair with the Frankfort plane parallel to the floor with their heads not fixed but in a relaxed state, and were asked to chew gummy jelly on their habitual chewing side for 20 s. After chewing, the subjects were asked to hold 10 ml of distilled water in their mouths for a moment and to spit into a cup. The cup containing the gummy jelly and the saliva was then filtered, and the filtrate was collected. For the evaluation of masticatory performance, the glucose concentration in the filtrate was measured as glucose extraction by means of a glucose testing device (GS-1Ò; Fujita, Tokyo, Japan). The recording of chewing was done two times and their average was used for analysis. Masticatory score Two types of masticatory scores were measured using a food intake questionnaire. Subjects were asked the state of intake for 20 foods selected by Sato et al. [1] and 25 foods selected by Koshino et al. [2]. The masticatory score was then calculated as MS1 according to the method of Sato et al. [1] and as MS2 according to the method of Koshino et al. [2]. Method of calculating MS1 The subjects were asked to assign the state of intake for each of the 20 foods as ‘‘easy to chew’’, ‘‘difficult to
123
Check as follows s: easy to chew, 4: difficult to chew, 9: Impossible to chew Masticatory score = number of s/20 9 100 (%)
Table 2 Calculation of the masticatory score 2 Difficulty grade
Difficulty ratio
Average pointa
Foods
I
1.00
A
Bananas, boiled cabbage, boiled carrots, boiled taro, boiled onions
II
1.06
B
Strawberries, ham, boiled fish paste, konnyaku, boiled kombu
III
1.22
C
Fried chicken, roast chicken, apples, pickled eggplants, raw cabbage
IV
1.39
D
Roast pork, pickled radish, rice cakes, peanuts, sliced raw cuttlefish
V
2.23
E
Raw carrots, takuwan, vinegared octopus, raw abalone, dried cuttlefish
Check as follows 2: easily eaten, 1: eaten with difficulty, 0: cannot be eaten, 4: do not eat because of dislike, h: have not eaten since starting to wear dentures Masticatory 13.8 9 100 (%) a
score = (A ? 1.06B ? 1.22C ? 1.39D ? 2.23E)/
Average point = average points for 5 foods expect for foods marked ‘‘4’’ or ‘‘h’’ in each grade
Odontology Fig. 1 The relationship between masticatory scores and glucose extraction
were calculated. Average scores (A–E) in each grade were multiplied by a corresponding coefficient (difficulty ratio). Finally, the total score was determined as the masticatory score (MS2) according to the following formula: MS2 = (A ? 1.06B ? 1.22C ? 1.39D ? 2.23E)/ 13.8 9 100 (Table 2), where ‘‘2’’ = easy eaten, ‘‘1’’ = eaten with difficulty, ‘‘0’’ = cannot be eaten, ‘‘4’’ = do not eat because of dislike, and ‘‘h’’ = have not eaten since I started wearing dentures.
Method of analysis Data were analyzed using a statistical software (SPSS for Windows 10.0J, SPSS; Chicago, IL, USA). P values \0.05 were considered to be significant. First, the relationship between masticatory scores (MS1 and MS2) and glucose extraction was investigated. Next, the relationship between MS1 and MS2 was investigated. Pearson’s correlation coefficient test was used.
Results The average values for MS1, MS2, and amount of glucose extraction were 63.3 % (SD, 17.3 %), 75.5 % (SD, 16.0 %), and 180.3 mg/dl (SD, 36.8 mg/dl), respectively. The value of masticatory scores was high when the amount of glucose extraction was large, and there was a significantly positive correlation between the two (MS1, r = 0.759; P \ 0.01, MS2, r = 0.667; P \ 0.01) (Fig. 1). There was also a positive correlation between MS1 and MS2 (r = 0.886; P \ 0.01).
**
**
Discussion Because food preferences differ with countries, each country uses its own foods while examining food intake ability using a food intake questionnaire. In Japan, Yamamoto’s method of examination has been the long-time method of choice. However, from the numerous types of foods available, Sato et al. [1] selected 20 and Koshino et al. [2] selected 25 food items for evaluation. From the intake conditions of these foods, masticatory scores were calculated, and quantitative evaluations of masticatory performance by food intake ability were attempted. These were indicated to be very useful. Therefore, in this study, the relationship between masticatory scores and glucose extraction was investigated. It was found that the masticatory score was high when the glucose extraction was high, and there were significantly positive correlations. These results may indicate that many types of foods can be masticated when the value of masticatory performance recorded with a gummy jelly was large. Koshino et al. [2] confirmed that there was a significant correlation between the masticatory score and the masticatory performance when the sieving method was used. Jeong et al. [4] reported that there was a moderate correlation between subjective food intake ability and objective masticatory performance. From these reports and our results, it could be hypothesized that food intake ability was high when the value of masticatory performance was high, although only a single food was used for the evaluation of masticatory performance. The finding of a highly significant positive correlation between the masticatory score (MS1) of Sato et al. [1] and that (MS2) of Koshino et al. is interesting. Although Sato et al. [1] used 20 and Koshino et al. [2] used 25 types of
123
Odontology
food, common foods were not used. What was common to both, however, was that both classified the foods into 5 different grades of chewing difficulty; Sato et al. [1] chose 4 types of food from each grade, and Koshino et al. [2] chose 5 types of food. From these facts, it could be inferred that even if the selections of food were different, if one selected equally from easy-to-chew foods and more difficult-to-chew foods, then one can probably evaluate masticatory performance fairly. To calculate the masticatory score, Koshino et al. [2] used their own formula, though the basis for the coefficient used in the formula was not mentioned in the article. However, from the fact that the more difficult-to-chew food had a larger coefficient, it can be surmised that the formula was set so that the score would be large if the more difficult-to-chew food can be chewed. To summarize this study, in the measurement of masticatory performance based on the amount of glucose extraction during the chewing of gummy jelly, a high extraction value means that the individual’s food intake ability is high and that many types of foods can be masticated.
Conflict of interest exist.
The authors declare that no competing interests
References 1. Sato Y, Minagi S, Akagawa Y, Nagasawa T. An evaluation of chewing function of complete denture wearers. J Prosthet Dent. 1989;62:50–3. 2. Koshino H, Hirai T, Toyoshita Y, Yokoyama Y, Tanaka M, Iwasaki K, Hosoi T. Development of new food intake questionnaire method for evaluating the ability of mastication in complete denture wearers. Prosthodont Res Pract. 2008;7:12–8.
123
3. Ueno M, Yanagisawa T, Shinada K, Ohara S, Kawaguchi Y. Masticatory ability and functional tooth units in Japanese adults. J Oral Rehabil. 2008;35:337–44. 4. Jeong SH, Kang SM, Ryu JH, Kwon HK, Kim BI. Subjective food intake ability in relation to the Mixing Ability Index in Korean adults. J Oral Rehabil. 2010;37:242–7. 5. Manly RS, Braley LC. Masticatory performance and efficiency. J Dent Res. 1950;29:448–62. 6. Van der Bilt A, Van der Glas HW, Olthoff LW, Bosman F. The effect of particle size reduction on the jaw gape in human mastication. J Dent Res. 1991;70:931–7. 7. Anastassiadou V, Heath MR. The development of a simple objective test of mastication suitable for older people, using chewing gums. Gerodontology. 2001;18:79–86. 8. Shiga H, Kobayashi Y, Arakawa I, Yokoyama M, Unno M. Validation of a portable blood glucose testing device in measuring masticatory performance. Prosthodont Res Pract. 2006;5:15–20. 9. Kobayashi Y, Shiga H, Arakawa I, Yokoyama M. The effectiveness of measuring glucose extraction for estimating masticatory performance. Prosthodont Res Pract. 2006;5:104–8. 10. Ikebe K, Matsuda K, Morii K, Furuya-Yoshinaka M, Nokubi T, Renner RP. Association of masticatory performance with age, posterior occlusal contacts, occlusal force, and salivary flow in older adults. Int J Prosthodont. 2006;19:475–81. 11. Lepley CR, Throckmorton GS, Ceen RF, Buschang PH. Relative contributions of occlusion, maximum bite force, and chewing cycle kinematics to masticatory performance. Am J Orthod Dentofacial Orthop. 2011;139:606–13. 12. Toman M, Toksavul S, Saracoglu A, Cura C, Hatipoglu A. Masticatory performance and mandibular movement patterns of patients with natural dentitions, complete dentures, and implantsupported overdentures. Int J Prosthodont. 2012;25:135–7. 13. Gonc¸alves TM, Campos CH, Gonc¸alves GM, de Moraes M, Rodrigues Garcia RC. Mastication improvement after partial implant-supported prosthesis use. J Dent Res. 2013;92:189S–94S. 14. Piancino MG, Frongia G, Dalessandri D, Bracco P, Ramieri G. Reverse cycle chewing before and after orthodontic-surgical correction in class III patients. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;115:328–31. 15. Endo T, Komatsuzaki A, Kurokawa H, Tanaka S, Kobayashi Y, Kojima K. A two-colored chewing gum test for assessing masticatory performance: a preliminary study. Odontology. 2014;102:68–75.
