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RESEARCH REPORT |
Center to Address Disparities in Childrens Oral Health and Comprehensive Oral Health Research Center of Discovery, University of California, San Francisco School of Dentistry, 3333 California Street, Suite 495, San Francisco, CA 94143-1361, USA
* corresponding author, Jane.Weintraub{at}ucsf.edu
| ABSTRACT |
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KEY WORDS: dental caries prevention fluorides preschool child randomized controlled trial
| INTRODUCTION |
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1 decayed, extracted, or filled primary maxillary incisor) was 14% among all preschool children, but higher in children from low-income families enrolled in Head Start programs: 44% among Asians and 39% among Latinos. Fluoride varnish is a concentrated topical fluoride with a resin or synthetic base. At least 19 fluoride varnish reviews (Weintraub, 2003), including a systematic review (Bader et al., 2001) and three meta-analyses (Helfenstein and Steiner, 1994; Strohmenger and Brambilla, 2001; Marinho et al., 2002) have been published in English. Most studies examined fluoride varnish efficacy in the permanent teeth of school-aged children. Consensus statements (NIH, 2001) regarding fluoride varnish differed for permanent and primary teeth. They stated, "The evidence for the benefit of applying fluoride varnish to permanent teeth is generally positive. In contrast, the evidence for the effectiveness of fluoride varnish applied to primary teeth is incomplete and inconsistent."
The objective of this two-year randomized controlled trial was to determine the efficacy of different fluoride varnish application frequencies with parental/caregiver oral health counseling vs. counseling alone in preventing early childhood caries incidence in young, initially caries-free children.
| MATERIALS & METHODS |
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Participants
This trial occurred at two public health centers, the Family Dental Center at San Francisco General Hospital (SFGH), and the San Francisco Department of Public Healths Chinatown Public Health Center (CPHC), serving primarily low-income, underserved Hispanic and Chinese populations, respectively. San Francisco has been optimally fluoridated (~ 1 ppm) since 1952.
Inclusion criteria for children at enrollment were: four erupted maxillary incisors; all primary teeth caries-free without demineralized, white spots; age 644 months; born in San Francisco or a fluoridated community in the San Francisco Bay Area and planning to reside in San Francisco for at least two years (eliminating water fluoridation as a potential confounder and demonstrating geographic stability); and a parent providing informed consent in English, Spanish, or Chinese. Children were excluded from the study if they had: medical problems or medications possibly affecting oral health; cleft lip/palate; developmental disabilities; transient residence; or another household member participating.
Recruitment and Follow-up
Between October, 2000, and August, 2002, families were recruited primarily from Well Child Clinics, Women, Infants and Children Supplemental Nutrition Programs, and dental clinics. Follow-up was completed in August, 2004.
Randomization
Children with parental consent were randomly assigned to one of three arms: parental counseling plus fluoride varnish twice/year (baseline, 6, 12, and 18 months) with four intended applications (4FV); parental counseling plus fluoride varnish once/year (baseline and 12 months) with two intended applications (2FV); or counseling only, with no fluoride varnish (0FV). The study teams biostatisticians conducted the computer-generated random assignment of participants, stratified by center, using permuted blocks of various sizes unknown to the clinicians. Assignment was concealed in sealed, opaque, labeled envelopes, unopened until time for treatment by the clinician.
Intervention and Measurements
Dental Examinations
Dental examinations, without radiographs, were conducted three times: at baseline prior to the intervention, and one and two years post-intervention. Older childrens examinations were conducted in a dental office; very young children had a knee to-knee examination (Ramos-Gomez et al., 2002). Universal infection control procedures were followed. Childrens saliva samples were collected during dental examinations, before any fluoride varnish application, for the assessment of salivary mutans streptococci (MS), lactobacilli (LB), and fluoride concentrations. Salivary assay results will be reported separately.
Parental Interview
The Project Director trained and calibrated staff in conducting interviews. Questionnaires were translated into Spanish and Cantonese, back translated into English for the assessment accuracy, and revised if necessary. The family member/caregiver was interviewed about factors associated with early childhood caries or dental caries, potential confounders, and effect modifiers, including sociodemographic, biologic, and behavioral factors, including questions about bottle use, diet, and dental utilization.
Parental Counseling
The annual counseling protocol followed the American Academy of Pediatric Dentistrys (AAPD) anticipatory guidance recommendations (Nowak and Casamassimo, 1995; Nowak, 1998). Thus, it was inappropriate for the control group to receive an examination without counseling or education having been provided. Individualized counseling visits followed these age-specific recommendations (612 months, 1224 months, 25 years), in the parents preferred language, by a trained team member.
Fluoride Varnish Application
Duraphat® (Colgate Oral Pharmaceuticals, New York, NY, USA) fluoride varnish was used with 0.1 mL (1 drop) applied per arch. Parents/caregivers were asked to refrain from brushing their childrens teeth with a fluoride dentifrice the day of varnish treatment, to minimize total fluoride exposure that day. Teeth were dried with gauze, and varnish was brushed onto all surfaces of the maxillary and mandibular anterior teeth, and the proximal and occlusal surfaces of the posteriors. One dentist (BJ) who spoke English, Spanish, and Cantonese provided clinical interventions at both sites. Masking accompanying caregivers to the control group assignment was attempted. The control groups tray set-up was the same. For children in this group, fluoride varnish was placed on gauze, which was then folded. The dry area was used to wipe the childs teeth, and no fluoride varnish was applied.
Primary Outcome Measures
The primary outcome was any caries incidence. We used the NIDCR diagnostic criteria for dental caries (USDHHS, 1991) for assessing cavitated, decayed (d2+), and filled surfaces on primary teeth (d2+fs). We used supplemental criteria (Drury et al., 1999) to diagnosis pre-cavitated lesions (d1). One pediatric dentist (FRG), masked to treatment group, conducted all dental examinations. Intra-examiner reliability, from repeat examinations of 21 children, yielded a kappa statistic of 0.96, indicating excellent agreement. Two years of follow-up were planned unless caries was detected at the one-year follow-up examination, in which case children were considered treatment failures and were referred for dental care.
Sample Size
We planned a sample size of 384 participants (128/study arm) (alpha = 0.05, power = 90%, 50% attrition,
2 test) to detect caries incidence differences, based on caries incidence in the literature (20% to 50% over two years). A similar study (Weinstein et al., 1994) reported 53% attrition in six months.
Data Analysis
For primary analysis, we used the intention-to-treat (ITT) approach (Fisher et al., 1990). Protocol-compatible analyses used number of actual active fluoride varnish applications. Analyses used data from all children with a follow-up dental examination. Primary analysis tested two-year caries incidence among treatment groups, with a two-degree-of-freedom (d.f.) non-parametric extended Mantel-Haenszel (EMH) test stratifying on center (Koch and Edwards, 1988). A priori step-down comparisons (Koch and Gansky, 1996) of each varnish group vs. control were performed, each at p
0.05: (1) 4FV vs. 0FV and (2) 2FV vs. 0FV; step (2) was performed only if step (1) was significant. A 1 d.f. EMH test, stratifying on center, tested trends across intended and actual number of applications. Logistic regression tested treatment group differences in incidence, with adjustment for covariates and treatment x center homogeneity. Supplemental analyses used linear regression to compare log (d2+fs +1) and log (d1+fs +1) among groups, adjusted for covariates (since dn+fs is skewed). Confounders were defined as changing model treatment coefficients by
20%. Since 96 children had no follow-up examination, multiple imputation (Schafer, 1997) with the Markov Chain Monte Carlo estimation (20 imputations) used center, assigned group, number of actual fluoride varnish applications, factors related to loss-to-follow-up (mothers age, dental pain barrier, dental fear barrier, and fluoride toothpaste use), and salivary measures (log10MS and log10LB) to impute log (d2+fs +1) scores.
| RESULTS |
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Clinical Outcomes
Primary analysis showed a statistically significant reduced percentage of children with any caries incidence (any decayed or filled surfaces at the last follow-up examination), when children in groups with any intended fluoride (2 or 4 treatments) were compared with the control group (Fig. 2
) (2 d.f. EMH p < 0.001; 1 d.f. step-down 4FV vs. 0FV and 2FV vs. 0FV both p < 0.003; multiple imputation 2 d.f. p < 0.034), or actual active applications vs. none (3 d.f. EMH p < 0.001; multiple imputation 3.d.f. p < 0.001). The percentage of children with caries decreased with increasing numbers of intended or actual active applications linearly (both p < 0.001).
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| DISCUSSION |
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The Cochrane collaboration meta-analysis (Marinho et al., 2002) obtained a pooled d(e/m)fs prevented fraction of 33% (95% CI, 1948%) based on three clinical trials. In our study, it ranged from 52 to 92%, by treatment group. The systematic review (Rozier, 2001) for the NIH Consensus Conference compared seven studies of fluoride varnish showing mixed effectiveness on primary teeth. Some were not randomized clinical trials, and none included children as young as those in our study (see APPENDIX).
The Cochrane reviewers (Marinho et al., 2002) recommended that fluoride varnish studies include reports of adverse events or safety concerns. At each visit, families were asked about adverse events; only 1 adverse event was noted for a child in the four-fluoride-varnish group, with "ulcer on the cheek" at the 18-month visit having onset 2 months after the last fluoride varnish application, which was "fluoride-free". The ulcer was gone at the 24-month visit. Some concerns about applying fluoride varnish to asthmatic children have been noted (Blinkhorn and Davies, 1998). However, from parental report, of the 21 children with asthma, none of the fluoride varnish recipients had adverse events. A 95% upper bound on adverse event incidence in asthmatic children was 0.14 (Hanley and Lippman-Hand, 1983).
Many children with caries at the screening examination were ineligible. This study was intended to determine the success of preventing caries incidence, not increment. It did not address fluoride varnish efficacy for children with extant caries.
An important lesson in efficacy trials is always to test the presence and quantity of the products active ingredient prior to and during study implementation, and to implement quality control measures to identify and correct protocol deviations as soon as possible. Most studies non-compliance/non-adherence is participant-generated. In this study, only the entry time was related to number of active treatments, making results more generalizable. This study provides support for the conduct of future caries-prevention clinical research in community health centers serving vulnerable and minority populations. Because the study occurred at these sites, findings are more generalizable to settings serving many high-caries-risk children than other potential locations. Similar results from the two clinical sites with different populations increase generalizability of the findings. Fluoride varnish and parental counseling should be recommended as part of caries prevention programs targeting infants and toddlers.
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Received April 4, 2005; Last revision August 30, 2005; Accepted October 6, 2005
| REFERENCES |
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