Comparative Evaluation of Hair, Fingernails, and Toenails as Biomarkers of Fluoride Exposure: A Cross-Sectional Study

Prenatal fluoride exposure, offspring visual acuity and autonomic nervous system function in 6-month-old infants

BACKGROUND

Prenatal fluoride exposure can have adverse effects on children's development; however, associations with visual and cardiac autonomic nervous system functioning are unknown. We examined associations between prenatal fluoride exposure and visual acuity and heart rate variability (HRV) in 6-month-old infants.

METHODS

We used data from Canadian mother-infant pairs participating in the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort. We estimated prenatal fluoride exposure using: i) fluoride concentration in drinking water (mg/L), ii) maternal urinary fluoride adjusted for specific gravity (MUFSG; mg/L) and averaged across pregnancy, and iii) maternal fluoride intake (µg/kg/day) from consumption of water, tea, and coffee, adjusted for maternal body weight (kg). We used multivariable linear regression to examine associations between each measure of fluoride exposure and Teller Acuity Card visual acuity scores (n = 435) and assessed HRV (n = 400) using two measures: root mean square of successive differences (RMSSD) and the standard deviation of N-N intervals (SDNN) measured at 6-months of age.

RESULTS

Median (IQR) values for water fluoride, MUFSG, and daily fluoride intake were 0.20 (IQR: 0.13-0.56) mg/L; 0.44 (0.28-0.70) mg/L and 4.82 (2.58-10.83) µg/kg/day, respectively. After adjustment for confounding variables, water fluoride concentration was associated with poorer infant visual acuity (B = -1.51; 95 % CI: -2.14,-0.88) and HRV as indicated by lower RMSSD (B = -1.60; 95 % CI: -2.74,-0.46) but not SDNN. Maternal fluoride intake was also associated with poorer visual acuity (B = -0.82; 95 % CI: -1.35,-0.29) and lower RMSSD (B = -1.22; 95 % CI: -2.15,-0.30). No significant associations were observed between MUFSG and visual acuity or HRV.

CONCLUSION

Fluoride in drinking water was associated with reduced visual acuity and alterations in cardiac autonomic function in infancy, adding to the growing body of evidence suggesting fluoride's developmental neurotoxicity.

Fingernail form as a post-extraction guide for selecting the maxillary central incisor tooth form in the Saudi Arabian population: A novel application of CAD software

Background

Human teeth and nails have demonstrated similar factors genetically, embryologically, and morphologically. The fingernail form may be used as a post-extraction guide for selecting the tooth form.

Aim

To evaluate the correlation between the maxillary left central incisor tooth form with the left index, middle, and ring fingernails in the Saudi Arabian population.

Materials and Methods

A descriptive cross-sectional study with purposive sampling was done among 200 Saudi participants. The maxillary left central incisor and the left index, middle, and ring fingernail were scanned using an intraoral scanner. The 3D digital images were converted to 3D models. The tooth form (tooth length, tooth width, and tooth shape) and nail form (nail length, nail width, and nail shape) were measured using the CAD software. Pearson's correlation coefficient and T-test were used for statistical analysis (P < 0.05).

Result

A significant correlation exists between tooth length and nail length, with a maximum correlation toward index nail length (P = 0.015). A significant correlation exists between tooth width and nail width, with a maximum correlation toward ring nail width (P = 0.002). A significant correlation exists between tooth length and nail length in females with a maximum correlation toward index nail length in females (P = 0.001). The mean percentage of similarity between tooth and nail shape (index, middle, and ring) in males and females shows a highly significant difference between them (P = 0.001). The results indicate that the tooth and nail shape are similar (70 to 90%) based on the criteria set by the software.

Conclusion

A definite correlation exists between maxillary central incisor tooth form and fingernail form. The fingernail form may be used as a post-extraction guide for selecting the maxillary central incisor tooth form in the Saudi Arabian population.

Evaluation of Age, Chief Complaint, Diagnosis, and Treatment Done during the First Dental Visit among Children in an Academic Dental Institution in Southern Kerala, India

Context

A regular and timely first dental visit plays a cardinal role in the future oral health of the child. It is used to begin preventive and corrective interventions in dental care.

Aim

To evaluate the age, chief complaint, diagnosis, and treatment done during the first dental visit among children in an academic dental institution in southern Kerala, India.

Materials and Methods

A descriptive cross sectional retrospective survey was conducted between January and June 2022 among children in an academic dental institution in southern Kerala, India. The hospital records at the Pushpagiri College of Dental Sciences were examined to obtain the child's age, chief complaint, diagnosis, and treatment done during the first dental visit among children. Statistical Analysis: The data were expressed in frequencies and percentages.

Results

The records of 1000 children (680 male and 320 female) were examined. Most children (40%) who came for their first dental visit were aged between 4 and 6 years. Only 16% of children aged 0-3 years came for their first dental visit. Pain and sensitivity (50%) and tooth decay (17%) were the most common chief complaints among children. Dental caries (45%) and pulpal pathology (38%) were the most common diagnoses among children. The most common treatments done were glass ionomer cement restorations (32%), followed by prescribing medications (29%). No treatment was required for 16% of the children. Only a minority (3%) of the children received preventive treatments.

Conclusions

The first dental visit was delayed, and most children sought treatment only during apparent acute symptoms. There is a high prevalence of oral disease burden and underutilization of preventive dental care among children. Education of parents on the value of first dental visits and the usage of preventative dental care in children is crucial.