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Biomedical subjects

J M Navia

Publications and source records attributed to J M Navia.

At least 19 recordsLinked to original sources
PubMed1998

Dr. Robert S. Harris: nutritionist, oral science researcher, and visionary MIT educator.

Efforts in dental research and training have received the contribution of individuals who had no formal training in dentistry, yet they understood the dental field and the educational needs of those who would be engaged in dental research, teaching, and service in industry and academia. Dr. Robert S. Harris (1904-1983) was such a man. What follows is a personal remembrance of his character, his research accomplishments, and his successful educational endeavors in the dental field.

Dental Caries↗
PubMed1998

The relationship of dental calculus to caries, gingivitis, and selected salivary factors in 11- to 13-year-old children in Chiang Mai, Thailand.

Thai children have been shown to accumulate large amounts of dental calculus. The purpose of this study was to examine the relationship of calculus to caries and gingivitis, and salivary conditions which may contribute to calculus accumulation. Four-hundred and thirty-nine (439) children from 18 schools in Chiang Mai were selected for this study. The children were given oral examinations to determine calculus index (CI); decayed, missing, and filled surfaces (DMFS); decayed, missing, and filled teeth (DMFT); gingival index (GI); and plaque index (PI). Children with mean CI scores > or =1 (206) were assigned to the calculus group; the 233 children with mean CI scores of <1 to the noncalculus group. Saliva was collected from 60 randomly-selected children in each group. Unstimulated and stimulated whole saliva and stimulated parotid saliva were assessed for flow rate, pH, and buffer capacity using 2 methods. Results showed that calculus status was not significantly associated with caries, but that there was a high association between gingivitis and plaque status with calculus accumulation (P < 0.001). There were no significant differences in saliva flow rate, pH, or buffer capacity between calculus and noncalculus groups. The lack of association between calculus status and caries indicated these 2 conditions have different etiologies and suggests the importance of plaque and calculus prevention programs, in addition to caries control efforts, to maintain oral health of Thai children.

Adolescent↗
PubMed1996

Caries experience in deciduous dentition of rural Chinese children 3-5 years old in relation to the presence or absence of enamel hypoplasia.

The association of enamel hypoplasia (EHP) with dental caries of the deciduous dentition was determined in 1,344 rural Chinese children aged 3-5 years. The degree of EHP was determined using a modified DDE Index. Number of decayed, missing, and filled teeth and tooth surfaces were determined for all subjects. Anthropometric assessment of body weight and height was done as an indirect measure of the nutritional status of the children. Results from the study showed that the prevalence of EHP was 22.3% in the total study population. The prevalence of dental caries was 82.3%. There was no difference in the caries experience between males and females. Significantly greater caries experience was observed among the children living in a low socioeconomic county and children with low height for age. Children with low birth weight showed a slightly higher percentage of caries than those born with normal birth weight. Children with enamel hypoplasia demonstrated a significantly higher caries experience than those who did not have such defects. The results of this study consistently support previous studies that found nutritional deficiency to have an important impact on tooth development and susceptibility to dental diseases. This study also indicates that the presence of enamel hypoplasia may be a predisposing factor for initiation and progression of dental caries, and a predictor of high caries susceptibility in a community, particularly if fluoride programs are not implemented.

Birth Weight↗
PubMed1996

Prevalence of developmental enamel defects and dental caries in rural pre-school Thai children.

The prevalence of developmental enamel defects and dental caries was assessed in 344 Karen children aged 1-4 years who were chronically (70 per cent) and acutely malnourished (9.3 per cent) The teeth were cleaned with gauze to facilitate detection of hypoplastic lesions on labial surfaces of maxillary incisors. At least one tooth with defective enamel was seen in 31.9 per cent of children, while enamel hypoplasia was present in 22.7 per cent of children. Enamel defects were found in 21.2 per cent of teeth, with hypoplasia and opacities occurring in 14.6 and 6.6 per cent of teeth, respectively. Gender did not alter the prevalence of defects. The upper central incisors were affected more than lateral incisors. The prevalence of dental caries was 31.9 per cent with a mean dt of 1.1. The prevalence of caries associated with enamel hypoplasia was significantly greater than that associated with opacities and sound enamel (P < 0.0005).

Acute Disease↗
PubMed1995

A new perspective for nutrition: the health connection.

The science of nutrition has undergone a major transformation in its objectives and approaches because of the influence of new understanding in epidemiology of oral diseases in technically developed countries, as well as in developing countries with different environmental circumstances. Recent findings of biochemical, immunological, and molecular biology investigations related to oral tissues have also added a new health dimension to this understanding. The major challenge ahead is not only to continue to expand the available scientific information, but to recognize the role that nutrition has for oral tissues, which is no different than the one it has for other tissues and organ systems. Investigators in other fields have been incorporating these new concepts about nutrition in the planning of their research during the past decade, but this emphasis has been lacking in dental research and this needs to be corrected. Still, we have one more challenge ahead, and that is to transfer to the general public the information generated by research in our laboratories and clinics in a prudent and effective way. This will ensure that consumers will take advantage of nutrition information alongside oral health concepts to maintain good general health while preventing and controlling oral diseases. There is much work ahead to be done, but the following papers have already started to set up research guidelines for the future.

Dental Caries↗
PubMed1995

Nutritional role of sugars in oral health.

The dental risk of dietary sugars is dependent mainly on the frequency of intake, but the prevalence of caries in a population is strongly modified by other dietary, social, and behavioral factors independent from intake of sugars. Regarding dietary factors, it must be remembered that hidden sugars in fruit as well as polysaccharides are cariogenic. The most important of the other factors is regular tooth brushing, which results in the removal of the bacterial plaque that causes caries and periodontal diseases and makes fluoride (which is contained in every advanced toothpaste) available for maintenance of the hard dental tissues and for remineralization wherever demineralization has occurred. This explains why in most highly developed countries caries prevalence has decreased markedly during the past 20 y although consumption of sugars remained high.

Dental Caries↗
PubMed1995

Prevalence and distribution of developmental enamel defects in primary dentition of Chinese children 3-5 years old.

A total of 1344 children, 3-5 yr old, from two rural counties, Haidian and Miyun, close to Beijing, China, were examined in 1992. A modified DDE Index was employed in this study, and a pre-designed formula was used to calculate an enamel defect score (EDS) for each individual in the study. Oral examination was performed by one dentist under natural light using a standard mouth mirror and dental probe. Developmental enamel lesions were diagnosed without drying or cleaning the teeth prior to examination. Results from this study showed that primary teeth with defective enamel were seen in 23.9% of the children examined, opacity in 1.6%, and hypoplasia in 22.2%. Among the teeth, maxillary central and lateral incisors were affected by enamel hypoplasia most often (40.8% and 39.2%), followed by maxillary canines (25.7%), maxillary 1st molars (22.1%), and mandibular 1st molars (18.5%). The enamel defects occurred more frequently on the buccal surfaces of teeth than on any other surface. The study did not find a significant association of the children's age, family socioeconomic status, and anthropometric measurements with the distribution of enamel defects. However, there was a significantly higher prevalence of teeth with defects in males compared to females (P < 0.001), as well as mean tooth surfaces with defects (P < 0.05), and mean EDS (P < 0.05). Children born prematurely were shown to have four times more enamel lesions than children who were full term (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1995

Effects of protein deficiency and diet consistency on the parotid gland and parotid saliva of rats.

Protein deficiency results in an increased susceptibility to dental caries, suggesting that oral host-defense properties are compromised. An important component of oral host defense is salivary gland function, which is affected by both protein deficiency and diet consistency. This study describes the effects on rat parotid gland growth and secretory function induced by feeding rats diets of normal (20%) or moderately low (7%) protein content, provided in either a powdered or solid form. In addition, since protein deficiency may result in a secondary zinc deficiency which, in turn, may affect salivary gland function, the effects of these diets on liver zinc concentration were also measured. From 22 to 47 days of age, rats (18/group) were fed the following diets: normal protein, powdered; normal protein, solid; low protein, powdered; and low protein, solid. With each diet consistency, liver zinc was higher for the normal protein group. Within each protein level, liver zinc was higher for the solid diet. This latter observation suggests that food mastication and the resultant stimulation of salivary gland function may also play a role in zinc metabolism. With the normal-protein diet, parotid gland weight was higher for the solid diet; with the low-protein diet, parotid gland weight was similar for both consistencies and did not differ from that of the group fed the "normal protein, powdered" diet. For both consistencies, parotid saliva protein concentration was greater for malnourished rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Colonization by mutans streptococci in the mouths of 3- and 4-year-old Chinese children with or without enamel hypoplasia.

This case-control study compared the prevalence and concentration of mutans streptococci (MS) in saliva between children with and without enamel hypoplasia (EHP). A total of 486 3- or 4-year-old Chinese children were initially screened for EHP, then distributed into two groups: 234 children diagnosed as having EHP were assigned to the case group; 252 who were free of EHP were included in the control group. The concentration of MS in saliva was assayed for each child. Nutritional status was deduced from body height and weight. Birth weight, prematurity, and nursing history were also determined. MS were found in 94.7% of the study population. The differences in MS concentrations were not associated with low birth weight, prematurity, length of breast feeding, or body height and weight. A statistically significant association existed between the presence of EHP and high counts of MS (p < 0.001). High MS counts were correlated with severity of enamel defects (p < 0.001). When the caries status of the children was controlled as the confounding factor in statistical analyses, the association between EHP and MS decreased but still remained significant (p = 0.025). This study shows that high MS counts are correlated with EHP, suggesting that irregularities in enamel surfaces could be a contributing factor that fosters the increased colonization of MS in the mouths of children.

Analysis of Variance↗
PubMed1994

Carbohydrates and dental health.

Carbohydrates, together with fats and proteins, provide the necessary energy needs for humans, and constitute, therefore, an integral part of a normal diet. An etiological model for caries that considers local and host factors is presented, highlighting the interaction of bacteria, saliva, minerals, and trace elements with food residues and with other intrinsic environmental and behavioral characteristics of the host. Consideration of this complex multifactorial etiology precludes the identification of any one factor as the only one to be singled out in prevention and management of oral disease. Sugar is, unquestionably, a risk factor for caries, and, therefore, its total substitution with energetic or nonenergetic sweeteners has been found useful. However, partial substitutions of fermentable sugars may have limited practical value in controlling caries prevalence. Caries preventive programs that take into consideration not one, but several etiologic factors, will be effective and beneficial to the general population.

Dental Caries↗
PubMed1993

A longitudinal study of dental caries in the primary teeth of children who suffered from infant malnutrition.

A prospective, four-year longitudinal study of 209 Peruvian children was conducted to evaluate the effect of a single malnutrition episode occurring at infancy (i.e., < 1 year of age) on dental caries in the primary teeth. Children were recruited into the study at age 6-11 months after they had suffered from a malnutrition episode and were thus classified by anthropometry as either: (1) Normal; (2) Wasted (low weight for height); (3) Stunted (low height for age); or (4) Stunted and Wasted (S and W). Eruption of the primary teeth was significantly delayed in all malnourished children; however, the effect of stunting--that is, retarded linear growth--was more pronounced and lasted longer than that of wasting or acute malnutrition (i.e., 2.5 vs. 1.5 years, respectively). By age 4 years, children from group 4 (S and W) showed a significantly higher caries experience in the primary teeth than did those in any of the other three groups. In summary, this longitudinal study has confirmed previous studies in animals and indirect epidemiological evidence which had suggested a cause-effect relationship between early malnutrition and increased dental caries.

Analysis of Variance↗
PubMed1990

Evaluation of alveolar bone in relation to nutritional status during pregnancy.

Demand for nutrients necessary for the formation of mineralized tissues increases dramatically during pregnancy to meet fetal requirements. The purpose of this clinical study was to identify short-term effects of pregnancy and dietary intakes of calcium, phosphorus, protein, and vitamin C on radiographic density and alveolar crest morphology of the mandible. Seventy-six subjects between ten and 20 weeks' gestational age were recruited from the Jefferson County, Alabama, Department of Health maternity clinic. Initially, an evaluation of their diet was done, and a single periapical radiograph was taken in the canine-premolar region of the mandible. A final evaluation of the diet and a periapical radiograph of the same teeth were obtained at a time as close to the expected date of delivery as possible. Dietary evaluation consisted of a 24-hour recall history and a food-frequency history at the two visits. Radiographs were made with a bite-block film-holding system with occlusal registration in acrylic for reproduction of projection geometry at the two visits. An aluminum stepwedge was incorporated for densitometric standardization. Measurements of plaque, and bleeding and pocket-depth probing were recorded for control of local effects on alveolar change. Standard statistical procedures of regression determined correlation of 12 nutrients and periodontal variables with bone density change and with alveolar crest morphology change. Vitamin C intakes (24-hour recall) showed a positive correlation (p = 0.033) with bone density change, and calcium intakes (24-hour recall) showed a negative, but not significant, correlation (p = 0.058) with bone density change, contributed particularly by subjects with the highest calcium intakes. The strongest relation with alveolar crest morphology change was the interproximal pocket-depth change (p = 0.086).

Adult↗
PubMed1990

The effect of nutritional status on the age distribution of dental caries in the primary teeth.

A cross-sectional study of dental caries in the primary teeth as a function of nutritional status was conducted on 1481 children one to 13 years old in Lima, Perú. Forty-one percent of the children were found to be chronically malnourished (stunted), 3% were acutely malnourished (wasted), and 5% were both stunted and wasted. A plot of decayed, extracted, and filled teeth (deft) vs. age resulted in a bell-shaped curve that was shifted to the right by 2.5 years for malnourished groups, compared with normal children (p less than 0.01). The shift to the right of the age distribution of caries was associated with a delay in both the eruption and exfoliation of the primary teeth in malnourished children. Peak caries activity was significantly higher in wasted and in stunted and wasted children, when compared with normal controls. It is concluded that malnutrition delayed tooth development, affected the age distribution of dental caries, and resulted in increased caries experience in the primary teeth.

Acute Disease↗
PubMed1989

Nutritional status, tooth eruption, and dental caries: a review.

Animal studies have shown that early malnutrition affects tooth structure, delays tooth eruption, and results in increased dental caries. However, epidemiologic evidence in support of these findings has been elusive. Cross-sectional surveys show that populations with a higher prevalence of caries in their deciduous teeth also show a lower prevalence of caries in their permanent teeth. However, longitudinal data from individuals show exactly the opposite. Caries development is also delayed as a consequence of a delayed tooth eruption and thus the bell-shaped curve that results from plotting deciduous caries prevalence vs age is shifted to the right in malnourished children. This effect will result in an apparently negative association between caries in deciduous and permanent teeth when cross-sectional surveys are compared. Once the effect on tooth eruption is taken into account, the contribution of malnutrition to increased caries susceptibility may be observed, as demonstrated by a recent cross-sectional study involving Peruvian children.

Adolescent↗
PubMed1988

Chronic malnutrition, dental caries, and tooth exfoliation in Peruvian children aged 3-9 years.

A cross-sectional evaluation of dental caries in primary teeth and nutritional status was conducted involving 285 Peruvian children from low socioeconomic conditions aged 3-9 y. Forty-nine percent of the children were found to be chronically malnourished (stunted) whereas acute malnutrition (wasting) was infrequent (2%). Stunted children showed a delayed exfoliation of primary teeth. The caries prevalence curve as a function of age (ie, a plot of decayed, extracted, and filled teeth vs age) was found to be shifted to the right by approximately 15 mo in stunted children as compared with well-nourished children. Children aged 7-9 y with stunted growth showed a significantly higher percentage of carious teeth than did well-nourished children of the same age (40 and 29%, respectively; p less than 0.005). Nutritional deficits that lead to chronic malnutrition not only may affect tooth exfoliation but also appear to render the primary teeth more susceptible to caries attack later in life.

Child↗
PubMed1988

Sulcal plaque pH and remineralization of sulcal caries in rats exposed to dietary and water fluoride.

After being inoculated with Streptococcus (mutans) sobrinus 6715 and fed a mildly caries-promoting diet for 14 days, sulcal plaque pH response to topical application of a 10% sucrose solution was measured in two groups of rats. The first group (experimental) was then fed diet and drinking water to which 1 mmol (20 ppm) fluoride had been added (0.5 mmol for 7 days and 1 mmol for 14 days) and pH measurements were repeated. The second group was held as a control and a third group was sacrificed to provide baseline caries scores. There was no difference in the fall in pH after topical application of 10% sucrose solution between the control and experimental group, nor between the pre- and postfluoride measurements for the experimental group. Sulcal caries incidence in the experimental group was significantly lower than in the control group. The results of this experiment emphasize the importance of a cariostatic mechanism of action for fluoride based on remineralization of enamel lesions and do not support the in vivo adaptation to fluoride by oral microorganisms.

Animals↗
PubMed1988

A method to assay fluoride in foods, beverages, and diets.

Foods and beverages containing sugars, frequently consumed as snacks between meals, contribute to dental caries in different proportions depending on a number of intrinsic factors, including carbohydrate content, textural properties, and mineral composition, such as calcium, phosphate, and fluoride concentration. A method to assay fluoride in foods and beverages is described which involves [1] an acid hydrolysis at 110 degrees C in a closed vial with a valve for dispensing reagents and [2] estimation of total acid-hydrolyzed fluoride using a specific ion electrode. A number of foods, beverages, and diets were analyzed for acid-hydrolyzable and free fluoride. The simplicity of the method eliminates fluoride contamination, making the procedure accurate and reproducible in determining fluoride in foods and beverages.

Beverages↗