December 2006

Objectives: Examine the relationship between (1) DMFS and community fluorosis index (CFI) scores, and (2) between individual DMFS and NIDR/Dean Index fluorosis scores. Design: Population-based, cross-sectional study. Setting: Public and private schools of Puerto Rico. Subjects: 1,435, 12-year old students. Method: A probabilistic stratified sample was selected from 11 regions of Puerto Rico, according to type of school (public and private), and setting (urban and rural). Children were examined using NIDR criteria for DMFS and fluorosis. Regressions examined the relationship between DMFS means and CFI scores. Individual level DMFS was regressed on NIDR/Dean Index scores to test for linear and deviation from linear trends. Results: (1) There was no statistically significant relationship between regional DMFS and CFI scores, and (2) individual level fluorosis scores when dichotomized as 0-2 as the referent level to level 3-4 demonstrated a statistical significant higher DMFS with the higher fluorosis level. Gender and school setting were statistically significant in all models: females and public school attendance were associated with increased DMFS. Conclusion: No ecological relationship between CFI and DMFS scores was found in 12-year-old children in Puerto Rico. Moderate and severe fluorosis were associated with higher DMFS levels relative to lower fluorosis scores, though this finding may be associated with restorations placed for cosmetic reasons. While controlling severe fluorosis is desirable, this will have little impact on overall high caries in Puerto Rican children. These findings suggest caution when interpreting caries experience using the DMFS index in populations with differing fluorosis levels. Key words: children, cross-sectional study, Dean Index, dental caries, dental fluorosis,, DMFS, Puerto Rico, 12 year olds Introduction The introduction of fluoride in its multiple forms as an anticariogenic agent has produced a marked reduction of caries in the United States and internationally. Decreasing caries levels reported in countries without systemic fluoridation programmes may be attributed to fluoridated dentifrices and the implementation of supervised programmes such as fluoridated mouthwashes and topical application of fluoride gel. Additionally, fluoride incorporated in food and drink products produced in fluoridated areas may, through their importation, add to the population exposure of fluoride in non-fluoridated communities (Levy et al., 1995). In the United States and other countries with developed market economies, the difference in the prevalence of caries among communities with optimally fluoridated water relative to areas having water fluoride deficiencies has been documented (Burt, 1994; NIDR, 1989; Mandel, 1996). Fluoride may have a greater dental caries preventive impact in lower socioeconomic communities, underscoring its continuing public health importance (Reisine & Psoter, 2001). The reported prevalence of dental fluorosis has ranged from 2.9 to 41.8 percent in non-fluoridated communities (Clark, 1994; Pendrys et al., 1996) and from 45 to 81 percent in areas with optimal water fluoridation programs (Clark, 1994; Williams & Zwemer, 1990). Several authors have reported an increase in the prevalence of dental fluorosis, mainly in the mild categories, concomitant with the reduction of dental caries (Pendrys et al., 1996; Szpunar & Burt, 1987; Williams & Zwemer, 1990). Investigators have also reported that in individuals with very mild or mild fluorosis, there is less risk for dental caries relative to individuals having no fluorosis. This has been observed both in communities with and without fluoridation programmes (El-Nadeef & Honkala, 1998; Hawley et al., 1996; Songpaisan & Davies, 1989). In 1997 the P.R. Health Department reported natural water fluoride levels in the ≤ 0.2 ppm range with rare instances of 0.4 and 0.5 ppm. Water fluoridation was instituted in Puerto Rico during the years 1953 and 1954. However, during the latter part of the 1980’s, water fluoridation was discontinued due to budgetary constrains. Dental caries levels in Puerto Rico are among the highest in the Caribbean, with a national 12 year-old DMFS of 6.4 (Elías-Boneta et al., 2003). The contemporary relationship between caries and dental fluorosis in Puerto Rico is unknown. Understanding the relationship between dental caries and dental fluorosis in Puerto Ricans is important for the design and implementation of primary dental caries prevention programmes on the Island. The specific aims of the present analysis of 12-yearold Puerto Ricans were two-fold: 1. to examine the ecological correlation between DMFS prevalence and community dental fluorosis index (CFI) 2. to examine the relationship between individual DMFS and a modified Dean Index score for dental fluorosis. Correspondence to: Professor Augusto R. Elías-Boneta DMD, MSD, University of Puerto Rico Medical Sciences Campus, School of Dentistry Research Center, P O Box 365067 San Juan, Puerto Rico 00936-5067. E-mail: [email protected]