| Sign In to gain access to subscriptions and/or personal tools. |
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; Correspondence: *corresponding author, p.pera{at}isiline.it
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 (Tlag) 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. Tlag and T were significantly shorter when the meal was chewed with 50 cycles than with 25 cycles (Tlag 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 Tlag (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
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.
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
Measurement of Gastric Emptying Rate 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 (Tlag), 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 (T1/2), that is, the time required for half of the gastric contents to transit through the pylorus.
Measurement of Trituration Performance 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
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 Tlag and 72 ± 22 min for T1/2. The comparison between the two mastication patterns showed that both Tlag and T1/2 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 Tlag 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 ).
The results of the sieve test showed that trituration performance (percentage of ham particles 1 mm after 50 chewing cycles) was inversely related to both Tlag (r = 0.621, p = 0.031) and T (r = 0.699, p = 0.012) (Fig.).
The results of this study indicate that gastric emptying rate is significantly influenced by masticatory efficiency. In fact, both Tlag and T1/2 were significantly shorter when the test meal was chewed for 50 cycles than when egg and crackers were chewed for 25 cycles only and ham cubes were swallowed whole. This means that adequate mastication shortened the time needed by the stomach to comminute food particles to a diameter small enough to pass through the pylorus. The shortening of gastric emptying produced by adequate chewing was consistent, about 10 min for Tlag and 13 min for T1/2. This difference is relevant, considering that the test meal was composed of a small quantity of soft and easily masticable ingredients. It is presumed that with an abundant meal containing hard foods, the influence of mastication on gastric emptying would have been much greater. The results of the sieve test further support the hypothesis that adequate food trituration shortens gastric emptying. In fact, the percentage of ham particles 1 mm observed after 50 chewing cycles was closely inversely related with both Tlag and T1/2. 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.
This investigation was supported by a grant from the Italian Ministry of University and Scientific Technological Research. Received for publication August 3, 2001. Revision received January 10, 2002. Accepted for publication January 16, 2002.
Journal of Dental Research, Vol. 81, No. 3,
179-181 (2002) This article has been cited by other articles:
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
|
 |
|
Sign In to gain access to subscriptions and/or personal tools.
TOP
ABSTRACT
INTRODUCTION
