Urinary fluoride parameters in spot urine samples from children exposed to fluoridated water and toothpastes

• Grant number: 19/11159-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2019
• End date: July 31, 2020
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Marília Afonso Rabelo Buzalaf
• Grantee: Isabela Eduarda Pelegati
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

Worldwide fluoridation schemes are designed to achieve optimal fluoride (F) ingestion given the customary F intake from diet and toothbrushing at a community level. However, even short-term excessive systemic F ingestion during tooth formation can increase the risk of dental fluorosis. Since urine is the main elimination route for systemically absorbed F (i.e. bioavailable F), the aim of this randomized cross-over study is to assess the validity of urinary F concentration (UFC), urinary F/specific-gravity ratio (FC/SG) and urinary F/creatinine ratio (FC/CR) in 24-hour (gold-standart method) and spot (alternative method) urine samples collected from children exposed to fluoridated toothpaste associated to fluoridated water. Thirty 4 to 6 year old children living in a water-fluoridation area (Bauru/SP) will provide the urine samples in two sessions, with an interval of approximately one week: Session A: 4 spot urine samples will be collected as follows: (1) 3 hours after breakfast on Day 1, (2) 3 hours after lunch on Day 1, (3) last void of urine before going to bed on Day 1, and (4) fasting, i.e. first voided urine in the morning on Day 2; Session B: 24-hour urine sample over four continuous intervals post-breakfast (PB) will be collected: (1) 0-3h PB, (2) 3-6h PB, (3) 6-12h PB on Day 1 plus (4) nocturnal and first voided urine on Day 2. A dietary questionnaire (food consumption 24 hours/day) will be obtained from each child. All urine samples will be analyzed using a F-ion-selective electrode, a chemical analyzer and a digital refractometer for assessment of UFC, UF/CR and UF/SG, respectively. The measurements derived from the both methods of urine collection will be examined by Pearson correlation coefficients and will be compared to identify optimum time-points for spot samples.