Eficiencia Masticatoria Kapur JPD 92-2

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CLASSIC ARTICLE

Masticatory performance and efficiency in denture wearers

Krishan K. Kapur, DMD, MS,a and Sham D. Soman, BDS, MSb

Tufts University School of Dental Medicine, Boston, Mass

In dental literature, the terms masticatory perfor-mance and masticatory efficiency have been usedinterchangeably. Manly and Braley1 have suggested animportant distinction between these two terms. Theydefined masticatory performance in terms of thepercentage particle size distribution of food whenchewed for a given number of strokes. This ratioprovides a measurement of performance of a dentition,but it fails to disclose the degree of impairment.

Manly and Braley

1

went one step further to ascertainthe degree of impairment by defining masticatoryefficiency in terms of the number of extra chewingstrokes required by an impaired dentition in order toachieve the same degree of food pulverization as a norm.The norm in their study represents the average valueobtained from a group of subjects who had lost thirdmolars, but no other teeth, from their dentitions.Manly2 devised a table from which masticatory efficiencycould be determined for any given chewing performanceratio. This table applies only when peanuts are used asthe test food.

It is illogical to compare the masticatory process ofdenture wearers with that of subjects with natural teeth.As shown in an earlier study,3 mastication in denturewearers is a random process lacking the preferentialgrinding of coarser food particles which is observed indentitions. Furthermore, the degree ofpulverization offood by dentures is greatly diminished.3

Previous trials4 demonstrated that the use of carrotsas a test food would detect differences in the chewingability of denture wearers whose denture design hadbeen altered in several ways. The purpose of thisinvestigation was to develop standards or norms bywhich functional impairment in denture wearers could

be evaluated.

PROCEDURE

The procedure used for evaluating masticatoryperformance in denture wearers has been described indetail.3 Briefly, the method consists of a subject chewinga measured portion of test food for a specified number ofstrokes (20 strokes for peanuts and 40 strokes forcarrots). The test food is then recovered and strainedthrough a standard mesh sieve (10 mesh for peanuts and5 mesh for carrots). The volume of food remaining on

the sieve and that passing through the sieve aredetermined. The masticatory performance ratio isdefined as the volume of food passing through the sievedivided by the total volume of test food recovered,expressed as a per cent.

The 140 test subjects came from three sources: (1)Tufts Dental Clinics and Clinical Research area, (2) anold age center, and (3) referrals from private dentists.Patients from the first source had dentures constructedby undergraduate and graduate students, generally bya similar technique. Patients from the other two sourceshad dentures representing a variety of techniques,

designs, and functional qualities.

RESULTS

Table I summarizes the performance data of the 140test subjects by groups. Mean performance ratios, theirrange and standard deviations, are given for carrots andpeanuts.

Figures 1 and 2 are histograms which show thedistribution of chewing performance ratios of 140subjects for carrots and peanuts, respectively. The threehistograms in each figure represent the 3 sources of testsubjects listed above. Each vertical line represents

a determination of one subjects half dentition. Whenmore than one subject showed the same performanceratio, each additional determination was plotted witha dot above the vertical line. For example, in Figures 2, 5subjects in group B showed a performance of 30% withpeanuts. The histograms demonstrate a wide range ofchewing performance among test subjects, with eitherpeanuts or carrots as the test food. Obviously, indeterminations of chewing performance, the samesubjects should be used in the same test series. Thewide range in chewing performance ratios, from 2.0 to63.0 for carrots and from 2.9 to 57.9 for peanuts,

showed that subjects vary greatly in their ability to chew

Presented at a meeting of the International Association for DentalResearch in Pittsburgh, Pa.

This investigation was aided in full by grants D-1067 and D-1611from the National Institutes of health.

aFormer Associate Professor, Department of Dental Science. Pres-ently Director of Research, University of Detroit School ofDentistry.

bResearch Associate, Department of Dental Science.Reprinted with permission from J Prosthet Dent 1964;14:687-94.

J Prosthet Dent 2004;92:107-11.

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carrots and peanuts. It is apparent that some subjectshave little difficulty in chewing carrots and peanuts whileothers are barely able to pulverize these foods at all.

Frequency polygons were drawn for the peanuts andcarrots data for all of the 140 subjects with the use of

a class interval width of 7 performance ratio units (Figs.3 and 4). The mean performance values of 27.2% forcarrots and 24.5% for peanuts have fallen in the modalclass frequency (peak of polygon), suggesting that thisdistribution of performance is close to normal.Thirty-nine subjects show performances between theranges of 20.5 to 34.5 for carrots, whereas 52 subjectshave fallen between the same range for peanuts. Theremaining subjects seems to be about equally distrib-uted between the high and low values; 52.6 and 55.5%of the subjects using peanuts and carrots, respectively, asthe test food showed performance ratios less than the

mean. This indicates that the carrot data show a slightskewness to the right, and relatively few subjects withhigh performance ratios.

CHEWING EFFICIENCY NORMS FORDENTURE WEARERS

A. Norm for carrots

A series of performance tests were run on 10 subjects,specifying 5, 10, 20, 40, 60, 80, and 100 chewingstrokes. In Fig. 5, performance ratios for carrots (5 mesh

sieve) are plotted against the number of chewing strokes

for the 10 subjects. Except for one subject, theperformance ratios are well clustered for a specifiednumber of chewing strokes, providing a linear relation-ship.

The ratios of all test subjects (One subject who

showed extreme deviation was deleted.) were averagedfor each specified number of chewing strokes. Theseaverages are shown in Fig. 5, and are connected by thestriated line. The performance tests made earlier anddepicted in Fig. 4 showed a 95th percentile chewingperformance ratio of 52.5%. Since the 52.5% perfor-mance ratio was close to the highest observed in denturewearers using 40 chewing strokes, this value wasarbitrarily taken as the 100% limit of the efficiency normunder development. The norm was established as shownin Figure 6 by drawing a line through the intercept of52.5% performance and 40 chewing strokes, and parallel

to the average of the values (depicted by the striated line)shown in Figure 5.

Figure 6 also shows how this norm is used indetermining chewing efficiency. For example, a perfor-mance ratio of 30% is plotted by a circle in Figure 6. Abroken line is drawn through this point parallel to thenorm until it intersects a perpendicular line drawn at52.5% performance point. This intercept gives on thevertical scale the number of chewing strokes required bythis subject (with a 30% chewing performance ratio) topulverize food to the 52.5% performance level.

The chewing efficiency then equals the number of

chewing strokes utilized for the masticatory perfor-

Table I. Masticatory performance data of 140 test subjects

Masticatory performance ratios

Mean Standard deviation Range

Carrots Peanuts

Subject source No. of subjects Carrots Peanuts Carrots Peanuts Low High Low High

A 64 28.1% 25.8 15.1 11.7 2 58 5 54

B 52 27.4 24.7 17.6 11.4 2 63 5 58

C 24 24.5 20.8 11.8 10.4 9 44 3 43

Fig. 1. Masticatory performance ratios of 140 denturewearers with carrots as test food. Histograms A, B, and Crepresent 3 source categories from which subjects weredrawn.

Fig. 2. Masticatory performance ratios, with peanuts as testfood, of 140 denture wearers drawn from 3 source categoriesA, B, and C.

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mance test (40 strokes) divided by the number of strokesrequired for 52.5% performance; this ratio is expressedas a percent.

In the illustration shown in Figure 6, the efficiencyequals 40/67 times 100, or 59.7%. Chewing efficiencymay be calculated directly from the formula:

Chewing efficiency40

103 1:2P3100:

Where P is equal to performance ratio, 103 is a constant,and 1.2 equals the slope of the norm. The abovecalculations obviously do not apply for zero perfor-

mance ratios.

B. Norm for peanuts

The norm for peanuts as a test food was calculated inthe same manner as that just described for carrots.However, the average performance ratios plottedagainst the number of chewing strokes demonstratelinearity from the lower limit up to performance ratios of55% at 10 mesh and 90% at 5 mesh (Fig. 7). The datahere are plotted on a log probability scale to obtain

linearity. The 95th percentile performance ratio (Fig. 3)

Fig. 3. Frequency polygon shows fairly normal distribution ofmasticatory performance ratios (peanuts) of 140 test subjectswhen arranged on 7% class interval.

Fig. 6. Denture norm for predicting masticatory efficiency formasticatory performance ratios with carrots as test food.Dotted lines show procedure to predict number of strokesrequired by a subject with 30% performance to achieve samedegree of pulverization as denture wearer with 52.5%performance.

Fig. 4. Frequency polygon shows slightly skewed distributionof masticatory performance ratios (carrots) of 140 test subjectswhen arranged on 7% class interval.

Fig. 5. Masticatory performance with carrots versus numberof strokes for each of 10 test subjects. Performance is linearlyrelated to number of chewing strokes used by subject, exceptin one subject who has shown a marked deviation.

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for peanuts is 43 per cent. This value is within the linearrange shown in Figure 7. Thus, any lack of linearity inthe efficiency was well above the 100% mark. As in thecase of carrots, a line was drawn parallel to the 10 meshperformance line (Fig. 7), passing through the interceptof 43% performance and 20 chewing strokes. This normis shown in Figure 8. Its use is the same as described forcarrots in Fig. 6. For example, the broken line shown inFigure 8 starts at the intercept of 20 chewing strokesutilized for the performance test and a chewing perfor-mance ratio of 30% (marked on graph by a circle). The

broken line is drawn through this circle parallel to the

line of the norm until it intersects a line perpendicular tothe performance axis at the 43% point. This latterintercept gives on the vertical scale the number ofchewing strokes required by the subject (with a 30%chewing performance ratio) to chew the peanuts to the43 performance level. The chewing efficiency hereequals the number of chewing strokes utilized (20strokes) divided by the number required for 43%performance expressed as a percent.

Chewing efficiency

20 chewing strokes utilized3100

37chewing strokes required for 43 per cent performance

54%

Because the log probability scale was used incalculating the norm for peanuts, no simple equationcan be derived for direct calculations of chewingefficiency. Column 2 of Table II shows chewingefficiencies for various performance ratios for peanuts.

Efficiency levels for peanuts may be read directly fromthis table.

DISCUSSION AND SUMMARY

Chewing performance in 140 denture wearers hasbeen measured. Norms for calculating the chewingefficiency of denture wearers have been developed forpeanuts and carrots as test foods (Figs. 6 and 8).

Table II shows the efficiency values obtained from theuse of norms developed for denture wearers described inthis article and the use of the Manly dentition norm.2At

all chewing performance ratios, the chewing efficiency of

Fig. 7. Relationship between average masticatory perfor-mance ratios with peanuts and chewing strokes for 10

subjects. Probability function of performance is linearlyrelated to logarithm of number of chewing strokes specifiedfor the test.

Fig. 8. Denture norm for predicting masticatory efficiency formasticatory performance ratios with peanuts as test food.

Dotted lines show procedure to depict chewing strokesrequired by a subject with 30% performance to achieve samedegree of pulverization as denture wearer with 43%performance (selected for 100% efficiency).

Table II. Chewing efficiency values derived for masticatoryperformance ratios with peanuts using denture and dentitionnorms

Masticatory performanceratio peanuts 20 strokes

(5 mesh sieve) (%)

Predicted efficiencyusing denture norm

(%)

Predicted efficiencyusing dentition norm*

(%)

5 19 5

10 20 7

15 23 1020 29 13

25 40 16

30 59 20

35 69 23

40 89 28

43 100 30

45 119 33

50 157 39

55 205 45

60 267 53

*Table from Manly RS. J Dent Res 1951;30:882.2

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denture wearers is inordinately lower when the dentitionnorm is utilized. For example, a masticatory perfor-mance ratio of 15% for a denture wearer has a chewingefficiency of 10% according to the dentition norm, butone of 23% according to the norm for denture wearers. Adenture wearer with a 40% performance ratio shows

chewing efficiencies of 28% and 89% according todentition and denture norms, respectively.Obviously, there is a disparity in efficiency increases

for increases in chewing performance of natural teethversus dentures. This disparity is due to the generallypoor chewing performance of denture wearers and theresultant decrease in the 95 percentile performance ratioselected for developing the norm for dentures.

This difference in mastication between denturewearers and subjects with (complete) dentitionsbecomes even greater, when one realizes that theManly norm2 is based upon the average performanceof natural teeth (dentitions). However, the denturenorm is based upon 95 percentile performance. Whena denture wearer has a masticatory performance ratio of43%, he has a chewing efficiency of 100% according tothe denture norm. However, his chewing efficiency bythe dentition norm (based on average performance) isonly 30%.

CONCLUSIONS

If the appropriate corrections are made for differentperformance levels and norms, the chewing efficiency ofthe denture wearer is less than one-sixth that of thesubject with a dentition. This substantiates the earlierstatement that the chewing process of denture wearers

should not be compared with that of people withdentitions. Obviously, dentures provide poor functionalreplacements for (complete) dentitions.

REFERENCES

1. Manly RS, Braley LC. Masticatory performance and efficiency. J Dent Res1950;29:448.

2. Manly RS. Factors affecting masticatory performance and efficiencyamong young adults. J Dent Res 1951;30:874.

3. Kapur K, Soman S, Yurkstas A. Test foods for measuring masticatoryperformance of denture wearers. J Prosthet Dent 1964;14:483.

4. Soman, S. Kapur, K. Influence of the location of occlusal platform on t hemasticatory efficiency of dentures, IADR abstract, 41st meeting, Pittsburg,

1963.

0022-3913/$30.00

Copyright 2004 by The Editorial Council of The Journal of ProstheticDentistry

doi:10.1016/j.prosdent.2004.03.026

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Eficiencia Masticatoria Kapur JPD 92-2