The Efficacy of Fluoride Rinse on Caries Increment, Plaque Occurrence and Gingival Status in Children Undergoing Orthodontic Treatment. A Randomized Controlled Clinical Trial with Results after 6- and 12 Months

Research Article

J Dent & Oral Disord. 2023; 9(1): 1178.

The Efficacy of Fluoride Rinse on Caries Increment, Plaque Occurrence and Gingival Status in Children Undergoing Orthodontic Treatment. A Randomized Controlled Clinical Trial with Results after 6- and 12 Months

Ekstrand KR1*; Tronier-Knowlton J2; Mikkjalsdóttir R2; Fedders SB2; Heidke R2; Sonnesen L2

1Section of Cariology, and Endodontics Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark

2Postgraduate Education in Orthodontics Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark

*Corresponding author: Kim Rud Ekstrand Section of Cariology, and Endodontics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark, Nørre Alle 20, 2200 Copenhagen N. Denmark. Tel: +4524431177 Email: kek@sund.ku.dk

Received: September 16, 2023 Accepted: October 11, 2023 Published: October 18, 2023

Abstract

This triple blinded RCT two arms study determines the efficacy of fluoride rinse (0.32% NaF-solution) for a period of 6 and 12 months (6m,12m) on the caries increment, plaque occurrence and gingival conditions in 10-15 year old Danes undergoing orthodontic treatment. Estimations showed that 24 subjects were required in the Test Group (TG) as well as in the Control Group (CG) at the end of the study. A total of 61 subjects were randomly assigned to TG (n=30) and the CG(n=31). Participants rinsed twice a week with 10 ml NaF solution (TG) or 10 ml of a placebo solution (CG). One assessor recorded at baseline, after 6-and 12 months caries (ICDAS index) and plaque and gingival status (Løe index). Four participants in each group dropped out during the study period. At patient level 27% in TG and 59% in CG showed caries progression during 12 month (p<0.05). Parametric tests confirmed that CG-participants had significant higher progression rate than TG-participants from 0m to 12m (p=0.014). The preventive fraction was 77% in favour of the TG-participants. Similar calculations from baseline to 6 months after, there were no significant caries increment difference between TG and CG. At 0m and 12m there was no significant difference in the plaque index and the gingival index between the two groups (p-values>0.05). The study conclusion was that rinsing twice a week with a 0.32% NaF solution during orthodontic treatment with fixed appliance had a significant effect on caries progression in children and adolescents during a treatment period of 12 months.

Keywords: Caries; Orthodontic treatment; Prevention; White spot lesions; Fluoride rinsing

Introduction

Denmark is known for that children and young people has a very low caries experience [1, 2]). This is, among other things, due to that in Denmark there is a focus on brushing teeth with fluoride-containing toothpaste, from the emergence of the 1st primary tooth and that Denmark has for the last 50 years had a Public Dental Health Care System free of charge covering the group of 0 to 18 years of age. The scheme also applies to orthodontic treatment for those approximately 25% of the child and youth population, who has the most severe functional disorders in their dentition. The literature shows that a combination of using fluoride toothpaste every day and fluoride rinses every day (low concentration, ≤250 ppm F-) or a few times a week (high concentration, ≥900 ppm F-) has a greater preventive effect than using fluoride toothpaste alone, in patients with moderate to high caries risk [3].

It is well known that orthodontic treatment increases the risk of developing caries, especially the cosmetically disfiguring facial lesions that develop due to the artificial plaque stagnation areas around bands and brackets [4-6]. These lesions can be difficult to mask after the orthodontic treatment [5,6].

Data from a review study [7] indicated that cementation materials containing fluoride, and low fluoride containing solutions for rinsing have a caries reducing effect on patients, who were under orthodontic treatment. However, bias was a prominent feature in the studies that have been conducted up to 2005 [7]. A Dutch RCT study [5] testing the effect of a low fluoride containing solution compared to a placebo solution showed a significant effect in reducing the increment of white spot lesions on patients under orthodontic treatment. In a Swedish RCT study [8], where the testing product was a fluoride containing varnish versus a placebo varnish applied every 6 weeks, during the orthodontic treatment an 14% less caries increment was noted (p> 0.05) in the test group compared to the control group. When expressed at the severity level the difference became significant in favor for the fluoride containing product.

There is no information about the incidence of caries in children and young people in Denmark as a consequence of receiving orthodontic treatment and no information whether a high concentrated fluoride rinses during the orthodontic treatment, twice a week, could reduce the incidence of caries. Further, it is important to mentioned that it is not legal in Denmark to use fluoridated toothpaste with > than 1500 ppm fluoride below the age of 16.

This study investigates whether fluoride rinses, twice a week, with a solution containing 0.32% Sodium Fluoride (NaF) ~1450 ppm fluoride effects on the caries increment, the plaque accumulation and gingival status in patients during the first year of orthodontic treatment with fixed appliances.

Thus, the primary outcome was to test any difference between test- and control group in increment of caries, at patient level and on group level, related to teeth with fixed appliances from baseline (0m) during 6 months (6m)- and 12 months (12m).

The two secondary outcomes were to test any difference between test- and control group in plaque occurrence and gingival status on 12 index teeth at baseline (0m) during 6m and 12m with orthodontic treatment.

Benson et al. stated in 2005 [7] that new studies in the present field of research should follow a protocol focusing on controlling for bias. There are several types of bias where the majority can be controlled for constituting a problem, if the study is planned well. We have taken the liberty to discuss the different types of bias used in Cochrane reviews of RCT-studies [see for example 3] related to the present study.

Material and Methods

The project has been approved by the Danish Ethics Committee (H-19062827) and by the Data Protection Authority (514-0446/19-3000).

Duration

The first participant got the baseline clinical examination December 20. 2019 and all participants had their baseline clinical examination finalized October 26. 2020. The data for the last 12 month clinical examination was November 4. 2021.

Location

The study took place at the School of Dentistry in Copenhagen at the Department of Orthodontics.

Trial Design

Triple blind randomized clinical trial with two parallel arms.

Products

The test products contain a 0.32% NaF-solution in bottles of 500 ml. The placebo was a liquid consisting only of water, but also in 500 ml bottles.

Inclusion Criteria

Medically healthy/or with minor disabilities aged 10-15 years, who need orthodontic treatment with fixed appliances.

Exclusion Criteria

Patients with chronic diseases who receive poly-pharmacy.

Sample Size

Based on β of 80% and a of 5% and an average difference of 2.5 lesions with a spread of 3 lesions, the Quick form shows 16/(2.5/3)² = 24 patients in each group [9]. As it was estimated that 5 patients will drop out during the study period, the aim was to allocate 30 patients in each group.

Randomization

The sample frame was 10-15 year olds in great Copenhagen area who were offered orthodontic treatment with fixed appliances in the local Child Dental Health surface and referred to the orthodontic department of the Dental School in Copenhagen, University of Copenhagen. A total of 68 candidates were addressed and from these 61 children/adolescents were interested in participating in the study, and both parents signed the consent form (Table 1).