HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Pera, P. Articles by Carossa, S. Search for Related Content PubMed PubMed Citation Articles by Pera, P. Articles by Carossa, S.

Influence of Mastication on Gastric Emptying

¹ Cattedra di Protesi Dentaria, Dipartimento di Scienze e Tecnologie Biofisiche Mediche e Odontostomatologiche, School of Dentistry, Università di Genova, Dental Clinic Pad 4, Largo R. Benzi, 10-16132 GENOA, Italy;
² Dipartimento di Scienze Biomediche e Oncologia Umana, Università di Torino;
³ Dipartimento di Medicina Interna, Cattedra di Gastroenterologia, Università di Genova; and
⁴ Cattedra di Malattie Odontostomatologiche, Università di Foggia;

*corresponding author, p.pera{at}isiline.it

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

 
The role of mastication on digestion efficiency remains to be demonstrated. This study investigates whether masticatory function influences gastric emptying rate. Twelve normal volunteers were studied on two occasions after ingestion of the same test meal containing ham cubes, crackers, and egg (mixed with ¹³C-octanoic acid), chewed, in random order, either with 50 masticatory cycles or with 25 cycles, swallowing ham cubes whole. Lag phase (T_lag) and gastric half-emptying time (T) were measured by means of the ¹³C-octanoic acid breath test. Trituration performance was assessed by the sieve test, and was expressed as the percentage of ham particles 1 mm after 50 masticatory cycles. T_lag and T were significantly shorter when the meal was chewed with 50 cycles than with 25 cycles (T_lag 25.9 ± 3.8 vs. 36.4 ± 4.1 min, p = 0.017; T 49.1 ± 5.7 vs. 62.5 ± 6 min, p = 0.009). Trituration performance was inversely related to both T_lag (r = 0.621, p = 0.031) and T (r = 0.699, p = 0.012). Comminution of food influences significantly gastric emptying rates.

KEY WORDS: chewing • digestion • trituration

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

 
The role of mastication in the digestive process, although recognized since the Roman age (prima digestio fit in ore—that is, early digestion is in the mouth), has received little interest in both dental and medical literature. Most published papers deal with the relationship between chewing efficiency and dentition (Helkimo et al., 1978; Gunne and Wall, 1985; Slagter et al., 1993; Boretti et al., 1995; Pera et al., 1998), and the few that examine the influence of mastication on the digestive process give contrasting results. An epidemiological study (Mercier and Poitras, 1992) on 142 subjects with inadequate chewing observed a 60% prevalence of current digestive complaints, such as burning sensation, bloating, cramps, constipation, or diarrhea; the disorders improved in 85% of the patients after correction of the masticatory dysfunction. By contrast, a study on edentulous subjects wearing dentures (Poitras et al., 1995) found that gastric trituration and the emptying of solid foods are not facilitated by prior mastication.

The aim of the present study was to evaluate whether, in subjects with natural healthy dentition, the gastric emptying rate of solid food changes in relation to the number of masticatory cycles and is related to the degree of food trituration.

	MATERIALS & METHODS

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

 
Study Subjects
The study was performed on 12 healthy non-smoking dental students, nine men and three women, with ages ranging from 18 to 35 yrs, and a body weight within 10% of their ideal value. All the subjects had a complete natural healthy dentition with no subjective or clinical disorders in the masticatory or digestive system. The protocol of the study was approved by a local ethics committee, and informed consent was obtained by each study subject.

Study Protocol
The subjects were examined on two separate occasions, one week apart, in the morning after overnight fasting, when they consumed the same test meal, divided into five equal portions. The meal had a total caloric value of 250 kcal and consisted of one egg cooked with butter (10 g), whose yolk was dosed with 100 mg ¹³C-octanoic acid (CORTEXITALIA Corsico, Milan, Italy), ham (21 g) cut into 5-mm cubes, crackers (25 g), and 500 mL of water. The subjects consumed the test meal in the sitting position over a period of no more than 10 min, with their usual chewing pattern, but on one session they chewed all the foods with 50 masticatory cycles, while on the other session they chewed only the egg and crackers for 25 cycles, and swallowed ham cubes whole. The order of the tests was randomized.

Measurement of Gastric Emptying Rate
Gastric emptying was measured by means of the ¹³C-octanoic acid breath test (Ghoos et al., 1993; Choi et al., 1997; Cheng and Lee, 1999). Octanoic acid is a medium-chain fatty acid, rapidly absorbed in the duodenum, whose oxidation in the liver results in excretion of labeled carbon dioxide (¹³CO₂) into breath. ¹³CO₂ can easily be measured in expired air, by means of isotope ratio mass spectrometry. Breath samples were collected at baseline before subjects ate the test meal (2 samples) and, after meal ingestion, every 15 min for the first hour (4 samples) and every 30 min for the following 3 hrs (6 samples). Breath samples were collected from subjects blowing directly into special pipettes impermeable to CO₂ (Vacutainer System, Franklin Lakes, NJ, USA), using a straw to blow into the bottom of the tube. ¹³CO₂ was measured by means of a mass spectrometer (Breath-mat, Finningan Mat, Brema, Germany) operated by a technician who was blinded to the experimental conditions. The ¹³CO₂ recovered in breath was expressed as percentage per hr of the administered amount.

From the ¹³CO₂ excretion curve, the following parameters of gastric-emptying rate were calculated, according to the formulae suggested by Ghoos et al. (1993): (1) the lag phase (T_lag), that is, the initial delay of the ¹³CO₂ excretion curve, representing the time needed for antral contractions to grind solid particles to a diameter small enough to pass through the pylorus (equal to or lower than 1 mm); and (2) the half-emptying time (T_1/2), that is, the time required for half of the gastric contents to transit through the pylorus.

Measurement of Trituration Performance
The degree of trituration was estimated with the use of sieves (Olthoff et al., 1984). For this test, only ham could be used, since both egg and crackers may stuff the sieve holes, thus blocking the passage of other food particles. Each subject was invited to chew 21 g of 5-mm ham cubes for 50 cycles and then to spit the masticated ham into three sieves stacked on top of each other, with holes progressively decreasing in size from top to bottom (2 mm, 1 mm, and 0.6 mm), under a water stream flowing at constant pressure of 1 atmosphere for 30 sec.

The material held by each sieve was collected, dried, and weighted. The quantity filtered by each sieve was expressed as the percentage of the total filtered test food. Trituration performance was expressed as the percentage of particles equal to or below 1 mm recovered after subjects chewed. Actually, 1 mm is the maximum diameter for solid particles to pass through the pylorus.

Statistical Analysis
The Student's t test for paired data was used to compare the gastric emptying rates obtained with 50 and 25 chewing cycles. Pearson's linear correlation test was used to evaluate the relationship between trituration performance (percentage of ham particles 1 mm) and both T_lag and T_1/2 obtained with 50 chewing cycles. For each test, a P level below 0.05 was considered statistically significant.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

 
All the subjects had values of gastric emptying rates within the range found in normal subjects (Ghoos et al., 1993), that is, 32 ± 20 min for T_lag and 72 ± 22 min for T_1/2. The comparison between the two mastication patterns showed that both T_lag and T_1/2 were significantly shorter when the meal was chewed for 50 cycles than when it was chewed for 25 cycles and ham cubes were swallowed whole: The T_lag decreased from 36.4 ± 4.1 min to 25.9 ± 3.8 min, p = 0.017; the T decreased from 62.5 ± 6 min to 49.1 ± 5.7 min, p = 0.009 (Table).

View larger version (13K): [in this window] [in a new window]   Figure. Scatter plot of the trituration performance (percentage of particles equal to or below 1 mm) against the two gastric emptying rates, Tlag (panel A) and T (panel B), with regression line. Trituration performance was significantly (P < 0.05) inversely related to both gastric emptying rates.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

In contrast to our findings, in Poitras' study (Poitras et al., 1995), gastric emptying was not influenced by mastication. This might depend on the fact that subjects wore complete dentures for edentulism, and dentures cannot provide a masticatory function as efficient as that of natural dentition (Kapur et al., 1964; Helkimo et al., 1978; Jemt, 1981). In this study, gastric emptying was measured by traditional scintigraphy. The present study used ¹³C-octanoic acid breath test as a measure of gastric emptying rate. This method of breath microanalysis has given results similar to those obtained by scintigraphy (Choi et al., 1997; Galmiche et al., 1998), with the advantage of the use of a stable isotope (¹³C) and the need for only inexpensive equipment (Cheng and Lee, 1999). Unfortunately, the ¹³C-octanoic acid breath test is influenced by interindividual differences in intestinal absorption, liver oxidation, and breath excretion (Maes et al., 1995; Choi et al., 1997). However, these factors might not be relevant in our study, since each subject was his/her own control. Also, food composition should not influence gastric emptying (Weiner et al., 1982) in the present study, since the meal was identical for the two sessions, the only substantial difference being ham mastication.

In conclusion, the results of this study demonstrate that mastication has a significant influence on the digestive process. Maldigestion might be the consequence of inadequate mastication, and the assessment of chewing efficiency should be included in the diagnostic work-up of digestive disorders.

	ACKNOWLEDGMENTS

 
This investigation was supported by a grant from the Italian Ministry of University and Scientific Technological Research.

Received August 3, 2001; Last revision January 10, 2002; Accepted January 16, 2002

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS & METHODS RESULTS DISCUSSION REFERENCES

 
Boretti G, Bickel M, Geering AH (1995). A review of masticatory ability and efficiency. J Prosthet Dent 74:400-403.[Medline]

Cheng WH, Lee WJ (1999). Technology development in breath microanalysis for clinical diagnosis. J Lab Clin Med 133:218-228.[Medline]

Choi MG, Camilleri M, Burton DD, Zinsmeister AR, Forstrom LA, Nair KS (1997). ¹³C octanoic acid breath test for gastric emptying of solids: accuracy, reproducibility and comparison with scintigraphy. Gastroenterology 112:1155-1162.[Medline]

Galmiche JP, Delbende B, Perri F, Andriulli A (1998). ¹³C octanoic acid breath test. Gut 43(Suppl 3):S28-30.[Free Full Text]

Ghoos YF, Maes BD, Geypens BJ, Mys G, Hiele MI, Rutgeerts PJ, et al. (1993). Measurements of gastric emptying rate of solids by means of a carbon-labeled octanoic acid breath test. Gastroenterology 104:1640-1647.[Medline]

Gunne HS (1985). Masticatory efficiency and dental state. A comparison between two methods. Acta Odontol Scand 43:139-146.[Medline]

Gunne HS, Wall AK (1985). The effect of new complete dentures on mastication and dietary intake. Acta Odontol Scand 43:257-268.[Medline]

Helkimo E, Carlsson GE, Helkimo M (1978). Chewing efficiency and state of dentition: a methodologic study. Acta Odontol Scand 36:33-41.[Medline]

Jemt T (1981). Chewing patterns in dentate and complete denture wearers recorded by light-emitting diodes. Swed Dent J 5:199-205.[Medline]

Kapur K, Soman S, Yurkstas A (1964). Test foods for measuring masticatory performance of denture wearers. J Prosthet Dent 14:483-491.

Maes BD, Ghoos YF, Geypens BJ, Hiele MI, Rutgeersts PJ (1995). Relation between gastric emptying rate and energy intake in children compared with adults. Gut 36:183-188.[Abstract/Free Full Text]

Mercier P, Poitras P (1992). Gastrointestinal symptoms and masticatory dysfunction. J Gastroenterol Hepatol 7:61-65.[Medline]

Olthoff LW, van der Bilt A, Bosman F, Kleizhen HH (1984). Distribution of particle sizes in food comminuted by human mastication. Arch Oral Biol 29:899-903.[Medline]

Pera P, Bassi F, Schierano G, Appendino P, Preti G (1998). Implant anchored complete mandibular denture: evaluation of masticatory efficiency, oral function and degree of satisfaction. J Oral Rehabil 25:462-467.[Medline]

Poitras P, Boivin M, Morais J, Picard M, Mercier P (1995). Gastric emptying of solid food in edentulous patients. Digestion 56:483-487.[Medline]

Slagter AP, Bosman F, Van Der Bilt A (1993). Comminution of two artificial test foods by dentate and edentulous subjects. J Oral Rehabil 20:159-176.[Medline]

Weiner K, Graham LS, Reedy T, Elashoff J, Meyer JH (1982). Simultaneous gastric emptying of two solid foods. Gastroenterology 81:257-266.[Medline]

This article has been cited by other articles:

				D. Remond, M. Machebeuf, C. Yven, C. Buffiere, L. Mioche, L. Mosoni, and P. P. Mirand Postprandial whole-body protein metabolism after a meat meal is influenced by chewing efficiency in elderly subjects Am. J. Clinical Nutrition, May 1, 2007; 85(5): 1286 - 1292. [Abstract] [Full Text] [PDF]

				M. Lorber Duodenal motor effects of simulated mastication FASEB J, April 1, 2007; 21(6): A1326 - A1326.

				A. Toro, P. H. Buschang, G. Throckmorton, and S. Roldan Masticatory performance in children and adolescents with Class I and II malocclusions Eur J Orthod, April 1, 2006; 28(2): 112 - 119. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Pera, P. Articles by Carossa, S. Search for Related Content PubMed PubMed Citation Articles by Pera, P. Articles by Carossa, S.