Influences of Masticatory Function Recovery Combined with Health Guidance on Body Composition and Metabolic Parameters

1. INTRODUCTION

The World Health Organization (WHO) categorizes diseases that can be prevented by improving lifestyle habits as Non-Communicable Diseases (NCDs). NCDs, including cancer, diabetes, cardiovascular disease, and respiratory disease, are the leading cause of death worldwide [1].

The habit of eating high-calorie low-nutrient meals such as those included in high carbohydrate diets and high-fat diets is thought to induce NCDs [2, 3]. These dietary habits seem to be related to masticatory function and health behavior, and the amount of tooth loss due to caries and periodontitis is related to masticatory performance [4, 5].

Impaired eating habits may also be caused by malocclusion due to various reasons such as skeletal deformity of the jaws, misshapen teeth, or temporomandibular joint disorder. Isola et al. [6], stated that up to 93% of patients with Juvenile Idiopathic Arthritis (JIA) may present with early inflammatory findings indicating temporomandibular joint disorder, and that their quality of life, including eating, smiling, oral hygiene, and daily activities, may deteriorate. The masticatory function of these patients decreases during the process of orthodontic treatment. Isola et al. [7] also stated that biologically active substances such as inflammatory cytokines are expressed in response to the consecutive mechanical stress caused by the application of an orthodontic force. Thus, a prosthodontic treatment that restores masticatory function, as well as orthodontic and aesthetic treatments, should be promoted with consideration of the relationship with comprehensive metabolism and nutritional status.

Tooth loss significantly impairs masticatory performance and causes the intake of sufficient nutrition difficult. Individuals with tooth loss frequently consume soft meals with high carbohydrate content (high-calorie, low-nutrient meals) [8]. As they are easy to swallow, these types of food tend to induce fast eating, overeating, and postprandial hyperglycemia, which may trigger a deterioration of carbohydrate metabolism and metabolic syndrome [9, 10].

These individuals also tend to avoid vegetables and meat that require masticatory ability. As a result, they may develop Protein-Energy Malnutrition (PEM); this can happen even with sufficient calorie intake. PEM may lead to chronic hypoalbuminemia (3.4 mg/dl or less), sarcopenia (decrease of skeletal muscle mass), or a long-term decrease in bone mass [11]. In the elderly, sarcopenia is a factor that contributes to the deterioration of an individual’s quality of life, eventually shortening his or her lifespan [12].

It has been reported that improvement in NCDs is promoted by optimizing nutrition intake and preventing an increase in the Glycemic Load (GL) [13, 14]. However, when the masticatory performance of a patient with NCDs is low, it is difficult for him or her to consume adequate nutrition and become disease-free [8]. Improving masticatory function through prosthodontic treatment seems to be the first step needed to improve the status of NCDs. Therefore, restoration of masticatory function through prosthodontic intervention seems to favorably affect the prevention of NCD onset and the deterioration of health.

Meanwhile, even when the masticatory function is normal or has been restored through dental treatment, ideal eating habits cannot always be obtained [15]; this is because we use gustation to sort out food [16, 17]. Moreover, the reasons for tooth loss include patients’ inadequate eating habits and health behaviors. Therefore, it seems that behavior modification through health guidance, which should be carried out simultaneously with the recovery of masticatory function, is necessary for patients with masticatory dysfunction to acquire ideal dietary habits.

The main goal of prosthodontics and orthodontics is aesthetic recovery and improvement in masticatory function [18]. However, this goal must include primary prevention of NCDs through improvement in nutritional intake, body composition, and metabolism. This broad approach including a range of goals requires tailor-made health guidance for patients in addition to the restoration of masticatory function.

It is important to quantitatively evaluate whether the recovery of masticatory function can contribute to the prevention of onset and deterioration of NCDs.

This case report is a preliminary study of three subjects with molar tooth loss, the most common cause of masticatory dysfunction. This study aims to observe and evaluate the influence of recovery of masticatory performance through prosthodontic treatment, combined with the improvement of eating habits through proper health guidance, on health-status indicators.

2. MATERIALS AND METHODS

Data were collected from three subjects, two males and one female, between the ages of 67 and 82 years; two subjects were obese and had molar loss, and one was edentulous and malnourished. The inclusion criteria were molar loss and a body type that deviated from the subjective standard. Exclusion criteria were subjects classified as Eichner classification A (occlusal support exists on both sides), and subjects with a Body Mass Index (BMI) within the reference of 20 to 26. In addition, as a confounding factor affecting carbohydrate metabolism and body composition, we confirmed that the subjects included in the study were not taking any supplements or prescribed medications.

We conducted prosthodontic treatment to restore the masticatory function and provided personal health guidance to improve subjects’ eating habits. Among the variables related to NCDs, we focused on carbohydrate metabolism, lipid metabolism, and body composition, as these reflect the influence of dietary habits.

The same intervention protocol was followed for all subjects (Fig. 1).

2.1. Baseline Interview and Inspection

The following interview and inspection were conducted before treatment intervention.

2.1.1. Lifestyle Questionnaire

We conducted a face-to-face interview using a questionnaire to elicit information on the subjects’ medical history, dietary habits, physical activities, lifestyle habits, family composition, socio-economic conditions, etc. (Table 1).

2.1.2. Masticatory Function Test

The subjects’ masticatory function was measured before and after prosthodontic treatment. The subjects chewed a gummy jelly containing glucose for 20 s, then rinsed lightly with 10 ml of water. The concentration of glucose eluted from the gummy jelly in the water was measured with a glucose measuring device, the Gluco-Sensor GS-II (GC Corporation, Tokyo, Japan) [19]. The average of the values measured three times on each subject’s deficient side was considered the level of masticatory ability, and Standard Deviation (SD) was calculated accordingly.

Table 1.

Have you ever had any of the following illnesses?	Hypertension/diabetes/periodontal disease/stomach or duodenal ulcer/stroke/cerebral infarction/intracranial hemorrhage/hyperlipidemia/liver disease/cancer/angina/myocardial infarction/none
Do you currently take any medicines?	Yes (number of medicines: …..)/No
What time do you get up and sleep?	Get up at about …../Sleep at about……
What time do you have each meal of the day?	Breakfast at about ……./No breakfast Lunch at about ……./No lunch Dinner at about ……./No dinner Midnight snack at about ……./No midnight snack
How often do you eat out? (including take-out food)	Every day/Sometimes (….. times a week)/ No eating out
Do you pay attention to sugar intake?	Yes, very much/Sometimes/No
Do you pay attention to the order of eating (i.e., vegetables first)?	Yes, very much/Sometimes/No
How do you eat your meal every day?	Eat until full/Finish before getting full/Eat small
How do you drink water every day?	1 – 2ℓ consciously/When thirsty/Rarely
Do you take any nutritional supplements?	Yes (number of supplements:……)/No
How do you sleep at night?	Sufficient/Not enough/Not at all
When do you go to bed?	More than 2 hours after dinner/1-2 hours after dinner/Within an hour after dinner
What do you think of your body type?	Fat/Thin/Standard
Do you think you lack exercise?	Yes/No
Do you feel a decrease in muscle strength?	Yes/No
Do you continue exercise of more than 30 minutes more than twice a week for more than a year?	Yes/Yes, but for less than a year/No such exercise
Do you feel stress in daily living?	Not at all/Sometimes/Yes, on a daily basis
Is there a lot of trouble?	Not at all/Sometimes/Yes, on a daily basis
Do you smoke?	Yes (….. tobaccos a day/for ….. years)/No/I used to, but I quit …...years ago
How many times do you drink alcohol?	Every day/….times a week/….. times a month/ Rarely/I used to, but I quit

2.1.3. Food Frequency Questionnaire (FFQ)

Surveys on food intake and frequency per week were conducted using questionnaires on 29 food groups and 10 different cooking methods. From the results of the questionnaires, habitual nutrient intake per day was estimated and evaluated. Nutrients such as protein, vitamin B1, B6, C, folic acid, calcium, and zinc were evaluated for sufficiency rates against the adult general intake standard based on the Dietary Reference Intakes for Japanese (2015) by Ministry of Health, Labor and Welfare in Japan [20]. Food Intake Frequency Survey FFQ Ver. 3.5 (Kenpakusha, Tokyo, Japan) was used for data analysis.

2.1.4. Anthropometric Measurements

Body composition was determined with bioelectrical impedance analysis (BIA) (ITO-InBody 370: InBody Japan Co., Ltd., Tokyo, Japan) [21, 22]; the values of body weight, BMI, basal metabolism standard value, body-fat percentage, and visceral-fat level were used for analysis.

2.1.5. Measurement of Blood Pressure

Blood pressure was measured using a digital automatic sphygmomanometer (HEM-7070: OMRON Corporation, Kyoto, Japan) by winding the manchette around the upper arm.

2.1.6. Blood Test

Blood samples were collected from the median cubital vein in the morning after fasting for more than 12 h; data were collected on the level of Hemoglobin A1c (HbA1c) as a glucose metabolism index and the Levels of Albumin (Alb), Total Protein (TP), HDL-Cholesterol (HDL-C), LDL-Cholesterol (LDL-C), and Triglyceride (TG) as the parameters for nutritional status. The investigation was entrusted to a clinical laboratory testing company (SRL, Inc., Tokyo, Japan).

3. CASE REPORTS

3.2. Case 2: 71-Year-Old Female Subject

3.2.1. Baseline Oral Condition and Prosthodontic Intervention

Teeth from 3 to 6 in the upper right quadrant and 5 to 7 in the lower left quadrant were missing (Eichner classification B3) (Fig. 3a). The subject complained of pain caused by the partial dentures she was wearing. She experienced difficulty and stress during mastication.

We conducted periodontal treatment to control chronic inflammation and restored masticatory function with dental implants (Platon Japan Co., Ltd., Tokyo, Japan) according to conventional procedures (Fig. 3b).

Table 2.

Nutrition and meal intake	Meals regularly taken three times a day and finished before getting full
	Types of carbohydrates and blood glucose level monitored
	Staple foods replaced with low GI carbohydrates(like whole grain bread or millet)
	Types and intake frequency of lipids monitored
	Difference between saturated fatty acids and unsaturated fatty acids discussed
	Trans-fatty acids avoided
	Recommendations given for intake of omega-3 polyunsaturated fatty acids
	Intake of meat, fish, and vegetables increased after recovery of masticatory function
	Vegetables discussed as a source of vitamins, minerals, and dietary fiber
	Discussion regarding failure of calorie restriction diets without considering nutrition
	Target basal metabolic rate calculated from thebasal metabolism standard value for each age and sex
Understanding of basal metabolism and exercise guidance	Target amount of exercise suitable for the subjects set basedon the criterion of physical activity for those over 65 years of age(10 METs*-hours/week, regardless of exercise intensity) [23]
	Physical activities planned according to each subject’s lifestyle (combiningaerobic exercise and anoxic exercise, sports, and daily activities)
	Influence on the body of lack of physical activities discussed
	Relationship between muscle mass, basal metabolism, and anti-aging effects discussed
Diet therapy of charting daily weight ** [24]	1) Body weight measured twice, in the morning and at night
	2) Subject filled in measured weight on a 100 g scale chart and drew a line graph
	3) When the graph increased or decreased, they wrote the reason in the comment field
	4) The target weight change was 50 to 100 g per day
Understanding on sleep	Sleep and stress control, circadian rhythm, etc. discussed
Smoking and drinking	None of the subjects smoked Low-carb alcoholic beverages were recommended

Table 3a.

Eating habits of swallowing and fasting

Habit of frequent eating out

Frequent intake of fried foods (omega-6 fat) Imbalance of fatty acids due to excessive intake of omega-6 and inadequate intake of fish (omega-3)

High intake of white rice and sweet bread

High intake of salt (9.6 g/day)

Drinking habits

Obesity

Metabolic disorders (hypertension and dyslipidemia) Common use of drugs for dyslipidemia

Physical activity: 5 METs*-hour/week (commuting by walk)

Exercise: 3.5 METs-hour/week (playing golf twice a month)

Table 3b.

Parameters of Body Condition and Metabolism	Before Intervention	After Intervention	Items in which Favorable Change was Found (+)
Level of masticatory ability (right jaw, mg/dl)	136 (SD ± 15)	237 (SD ± 34.6)	+
Body Mass Index	29.5	25.2	+
Body weight (kg)	91.95	78.55	+
Basal metabolism standard value (kcal/kg/day)	19.6	21.6	+
Body-fat percentage (%)	30.3	25.3	+
Visceral-fat level	18	14	+
Systolic/diastolic blood pressure (mmHg)	150/95	135/85	+
Hemoglobin A1c (HbA1c) (%)	5.7	5.3	+
Albumin (g/dl)	N/A	N/A	N/A
HDL-Cholesterol (mg/dl)	N/A	N/A	N/A
LDL-Cholesterol (mg/dl)	N/A	N/A	N/A
LDL-Cholesterol/HDL-Cholesterol	N/A	N/A	N/A
Triglyceride (mg/dl)	N/A	N/A	N/A
Protein sufficiency rate (%)	70	87.4	+
Vitamin B1 sufficiency rate (%)	72	78	+
Vitamin B6 sufficiency rate (%)	97	93	N/A
Vitamin C sufficiency rate (%)	66	120	+
Folic acid sufficiency rate (%)	105	155	+
Calcium sufficiency rate (%)	74	103	+
Zinc sufficiency rate (%)	75	78	+

3.2.2. Baseline General Condition (Table 4a)

The subject started a trial of improving dietary habits by herself, one year before the start of health-guidance intervention. Her body weight was reduced by 3 kg in one year; it was difficult for her to completely refrain from eating sweets because of the stress caused by being her husband’s sole nursing-care provider at home. As her lack of exercise had been inhibiting weight loss, the target value for basal metabolism was raised. She was provided information regarding Metabolic Equivalents (METs) and directed to practice higher intensity physical activities to increase fat-combustion efficiency.

3.2.3. Results (Table 4b)

The masticatory ability recovered from 70 mg/dl (SD ± 49.1) to 179 mg/dl (SD ± 10.6) and from 127 mg/dl (SD ± 7.2) to 163 mg/dl (SD ± 31.3) in the right and left jaws, respectively, after prosthodontic treatment.

After prosthodontic treatment and health guidance, BMI, body-fat percentage, visceral-fat level, and blood pressure improved, and HbA1c improved remarkably. Lifestyle habits also improved, and physical activity increased. As for nutrient intake, the rates of calcium and zinc intake improved.

Table 4a.

Excessive intake of free sugars due to eating between meals

Meat and egg intakes were half of the required amount

Excessive food intake at dinner

Obesity

Metabolic syndrome/history of diabetes (HbA1c: 7.0%)

Physical activity: 3 METs*-hour/week (dog-walking)

No habit of exercise

Table 4b.

Parameters of Body Condition and Metabolism	Before Intervention	After Intervention	Items in which Favorable Change was found (+)
Level of masticatory ability (right jaw, mg/dl)	70 (SD ± 49.1)	179 (SD ± 10.6)	+
Level of masticatory ability (left jaw, mg/dl)	127 (SD ± 7.2)	163 (SD ± 31.3)	+
Body mass index	41.5	36.1	+
Body weight (kg)	87.15	75.9	+
Basal metabolism standard value (kcal/kg/day)	13.7	15.5	+
Body-fat percentage (%)	59.7	50.7	+
Visceral-fat level	18	16	+
Systolic/diastolic blood pressure (mmHg)	131/63	119/58	+
Hemoglobin A1c (%)	9.5	7.5	+
Albumin (Alb) (g/dl)	4.2	4.1	-
HDL-Cholesterol (mg/dl)	50	55	+
LDL-Cholesterol (mg/dl)	167	137	+
LDL-Cholesterol/HDL-Cholesterol	3.3	2.5	+
Triglyceride (mg/dl)	273	149	+
Protein sufficiency rate (%)	85.8	87	+
Vitamin B1 sufficiency rate (%)	163	135	-
Vitamin B6 sufficiency rate (%)	95	86	-
Vitamin C sufficiency rate (%)	107	78	-
Folic acid sufficiency rate (%)	102	78	-
Calcium sufficiency rate (%)	69	89	+
Zinc sufficiency rate (%)	69	76	+

4. DISCUSSION

In this case report, the masticatory function of all subjects improved with dental prosthodontic treatment (Figs. 4a-4d). Due to prosthodontic treatment and health guidance, improvements were also confirmed in a wide range of items, including body composition (Fig. 4a), metabolism (Figs. 4b-4c), and nutrient sufficient rates (Fig. 4d).

There are two important features of this case report. First, recovery of masticatory function was achieved through the simultaneous use of prosthodontic treatment and health guidance. Second, we defined numerical variations in nutritional status, body composition, and metabolic parameters as the end points of prosthodontic treatment.

In cases 1 and 2, the levels of masticatory ability significantly increased after prosthodontic rehabilitation with dental implants. Even with complete dentures in case 3, the level was increased. In cases 1 and 2 with a high carbohydrate diet, HbA1c levels improved after intervention (case 1: 5.7% to 5.3%; case 2: 9.5% to 7.5%). The improvement was especially significant in case 2, although the subject was more obese than the subject in case 1. These results seem to be due to a decrease in carbohydrate intake and an increase in the intake of low-GI foods.

In cases 1 and 2, blood-pressure levels improved (case 1: 150/95 mmHg to 135/85 mmHg; case 2: 131/63 mmHg to 119/58 mmHg) and the risk of cardiovascular diseases decreased. Regarding nutrient intake, the sufficient rates of calcium and zinc improved in all cases.

Improvement in body composition was observed in all cases. In case 1, the amount of physical activity before health guidance was below the standard criterion for subjects 65 years of age and older (10 METs-hour/week). However, after guidance, the amount of activity exceeded the standard criterion for subjects 64 years of age and younger (23 METs-hour/week). In case 2, the amount of physical activity before guidance was also less than the standard criterion for subjects 65 years of age and older. However, after guidance, the subject achieved her target amount of activity of 12 METs-hour/week. Visceral-fat levels of the subjects in cases 1 and 2 gradually decreased (case 1: 18 to 14; case 2: 18 to 16). Due to the establishment of the habit of exercise as well as an improvement in eating habits, subjects were able to burn fat, maintain muscle mass, and prevent rebound.

Due to difficulties with food intake, the subject in case 3 was in a state of malnutrition with a baseline BMI of 12.8. Prosthodontic treatment made it possible for him to consume various foods, and as a result of prioritizing calorie intake, he showed an increase in BMI (17.3), muscle mass (27.7 kg to 33.6 kg), and body fat percentage (5% to 14.6%). His nutritional status also improved. Moreover, although the prescribed exercise was minimal, he started walking and no longer required his wheelchair; he also demonstrated outstanding improvement in his activity of daily living. These results indicate that, although our focus would have usually been on the nutritional problems concerning the prevention or improvement of sarcopenia and frailty, recovery of masticatory function is equally important.

The subject of case 3 was not in the habit of exercising and had an increase in visceral-fat level (1 to 8; baseline value was too low) and HbA1c (5.5% to 6.1%). There was also a rise in systolic blood pressure (106 mmHg to 151 mmHg). We assume that his acquired habit of exercise will make HbA1c and visceral-fat levels approach proper values.

These findings suggest a correlation between masticatory dysfunction, PEM, and an increase in glycemic load, as well as a correlation among masticatory dysfunction [25], PEM, and decrease in muscle mass (Figs. 4a-4d).

It seems that the evaluation method employed in this study, showing the results of health behavior in numerical values, helped raise the subjects’ awareness of health promotion. In the future, organization of a medical care system for the rehabilitation of masticatory function to promote health and improve NCDs is needed.

The issue remaining to be addressed is how to help patients recognize their own physical conditions at an early stage, understand that tooth loss or masticatory dysfunction will lead to serious health hazards; and move to action.

The main objective of orthodontic and prosthodontic treatment as well as the treatment of temporomandibular disorders has been esthetic improvement and recovery of masticatory function. Moreover, it has been reported that patient satisfaction greatly increases with expansion of the therapeutic effect; this may include an improvement in general health condition, the short-term disappearance of inflammatory response, a shortened treatment period, an improvement in quality of life, better aesthetic results, as well as an improvement in body composition and metabolism [6, 7, 25].

For stronger evidence, we should increase the number of cases, selected randomly, and make a significant difference test. This case report was a preliminary study focusing on three interesting cases; in our future research, we will examine patient satisfaction using a visual analogue scale. In addition, we will classify the selected subjects into the following groups: masticatory-function recovery, health guidance only, and non-intervention. We will examine by correlation analysis the relationships among the groups.

Treatment intervention to recover masticatory function combined with appropriate health guidance according to patients’ conditions may contribute to the prevention of onset or deterioration of NCDs through an improvement in nutritional status and body composition.

CONCLUSION

Short-term goals for the treatment of individuals with masticatory dysfunction include recovery of masticatory function, aesthetic restoration, and inflammation control. The final goal, however, seems to be health promotion and prevention of the onset or deterioration of NCDs. It is considered that an inclusive medical care system combining dental prosthetic treatment with personal health guidance is effective for expansion of the treatment effect.

REFERENCES