Design of the xylitol for adult caries trial (X-ACT)

A Predictive Model for Root Caries Incidence

This study aimed to find the set of risk indicators best able to predict root caries (RC) incidence in caries-active adults utilizing data from the Xylitol for Adult Caries Trial (X-ACT). Five logistic regression models were compared with respect to their predictive performance for incident RC using data from placebo-control participants with exposed root surfaces at baseline and from two study centers with ancillary data collection (n = 155). Prediction performance was assessed from baseline variables and after including ancillary variables [smoking, diet, use of removable partial dentures (RPD), toothbrush use, income, education, and dental insurance]. A sensitivity analysis added treatment to the models for both the control and treatment participants (n = 301) to predict RC for the control participants. Forty-nine percent of the control participants had incident RC. The model including the number of follow-up years at risk, the number of root surfaces at risk, RC index, gender, race, age, and smoking resulted in the best prediction performance, having the highest AUC and lowest Brier score. The sensitivity analysis supported the primary analysis and gave slightly better performance summary measures. The set of risk indicators best able to predict RC incidence included an increased number of root surfaces at risk and increased RC index at baseline, followed by white race and nonsmoking, which were strong nonsignificant predictors. Gender, age, and increased number of follow-up years at risk, while included in the model, were also not statistically significant. The inclusion of health, diet, RPD use, toothbrush use, income, education, and dental insurance variables did not improve the prediction performance.

The dynamic behavior of the early dental caries lesion in caries-active adults and implications

OBJECTIVE

To describe the full range of behavior of the visible, noncavitated, early caries lesion in caries-active adults with substantial fluoride exposure, and to consider implications.

METHODS

The data were from the Xylitol for Adult Caries Trial (X-ACT) collected annually for 33 months using condensed ICDAS caries threshold criteria. Individual tooth surfaces having a noncavitated caries lesion were included, and the patterns of transition to each subsequent annual clinical examination to sound, noncavitated or cavitated, filled or crowned were determined. The resulting sets of patterns for an individual tooth surface, looking forward from its first appearance as a noncavitated lesion, were combined into one of four behavior profiles classified as reversing, stable, oscillating, or continuously progressing, or were excluded if not part of the caries continuum. The distributions of profile types were assessed using the Rao-Scott chi-square test, which adjusts for clustering of tooth surfaces within teeth.

RESULTS

Inter- and intra-examiner kappa scores demonstrated acceptable calibration at baseline and annually. 8084 tooth surfaces from 543 subjects were included. The distribution of profile types differed significantly between coronal and root surfaces. Overall, two-thirds of all coronal noncavitated lesions were first seen at baseline, half reversed, over a fifth were stable, 15% oscillated, and only 8.3% progressed to cavitation, filled, or crowned in 33 months or less (6.3% consistently Progressed plus 2.0% inconsistently, a subset of oscillating, which oscillated before progressing to cavitation). Approximal, smooth, and occlusal coronal surfaces each were significantly different in their individual distributions of profile types. Xylitol showed no significant and consistent effect on this distribution by tooth surface type. This was in keeping with the X-ACT's lack of effect of xylitol at the noncavitated plus cavitated lesion thresholds combined.

CONCLUSIONS

This study demonstrated the full dynamic range of early caries lesion behavior. The great majority were not progressive, and few (8.3%) became cavitated over 33 months in caries-active adults using fluorides. Important caries management implications favoring recorded longitudinal monitoring, prevention of active risks, and minimal restoration only after direct visual determination of cavitation are discussed.

Xylitol-containing products for preventing dental caries in children and adults

BACKGROUND

Dental caries is a highly prevalent chronic disease which affects the majority of people. It has been postulated that the consumption of xylitol could help to prevent caries. The evidence on the effects of xylitol products is not clear and therefore it is important to summarise the available evidence to determine its effectiveness and safety.

OBJECTIVES

To assess the effects of different xylitol-containing products for the prevention of dental caries in children and adults.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group Trials Register (to 14 August 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2014, Issue 7), MEDLINE via OVID (1946 to 14 August 2014), EMBASE via OVID (1980 to 14 August 2014), CINAHL via EBSCO (1980 to 14 August 2014), Web of Science Conference Proceedings (1990 to 14 August 2014), Proquest Dissertations and Theses (1861 to 14 August 2014). We searched the US National Institutes of Health Trials Register (http://clinicaltrials.gov) and the WHO Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of xylitol products on dental caries in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias of the included studies. We attempted to contact study authors for missing data or clarification where feasible. For continuous outcomes, we used means and standard deviations to obtain the mean difference and 95% confidence interval (CI). We used the continuous data to calculate prevented fractions (PF) and 95% CIs to summarise the percentage reduction in caries. For dichotomous outcomes, we reported risk ratios (RR) and 95% CIs. As there were less than four studies included in the meta-analysis, we used a fixed-effect model. We planned to use a random-effects model in the event that there were four or more studies in a meta-analysis.

MAIN RESULTS

We included 10 studies that analysed a total of 5903 participants. One study was assessed as being at low risk of bias, two were assessed as being at unclear risk of bias, with the remaining seven being at high risk of bias.The main finding of the review was that, over 2.5 to 3 years of use, a fluoride toothpaste containing 10% xylitol may reduce caries by 13% when compared to a fluoride-only toothpaste (PF -0.13, 95% CI -0.18 to -0.08, 4216 children analysed, low-quality evidence).The remaining evidence on children, from small single studies with risk of bias issues and great uncertainty associated with the effect estimates, was insufficient to determine a benefit from xylitol products. One study reported that xylitol syrup (8 g per day) reduced caries by 58% (95% CI 33% to 83%, 94 infants analysed, low quality evidence) when compared to a low-dose xylitol syrup (2.67 g per day) consumed for 1 year.The following results had 95% CIs that were compatible with both a reduction and an increase in caries associated with xylitol: xylitol lozenges versus no treatment in children (very low quality body of evidence); xylitol sucking tablets versus no treatment in infants (very low quality body of evidence); xylitol tablets versus control (sorbitol) tablets in infants (very low quality body of evidence); xylitol wipes versus control wipes in infants (low quality body of evidence).There was only one study investigating the effects of xylitol lozenges, when compared to control lozenges, in adults (low quality body of evidence). The effect estimate had a 95% CI that was compatible with both a reduction and an increase in caries associated with xylitol.Four studies reported that there were no adverse effects from any of the interventions. Two studies reported similar rates of adverse effects between study arms. The remaining studies either mentioned adverse effects but did not report any usable data, or did not mention them at all. Adverse effects include sores in the mouth, cramps, bloating, constipation, flatulence, and loose stool or diarrhoea.

AUTHORS' CONCLUSIONS

We found some low quality evidence to suggest that fluoride toothpaste containing xylitol may be more effective than fluoride-only toothpaste for preventing caries in the permanent teeth of children, and that there are no associated adverse-effects from such toothpastes. The effect estimate should be interpreted with caution due to high risk of bias and the fact that it results from two studies that were carried out by the same authors in the same population. The remaining evidence we found is of low to very low quality and is insufficient to determine whether any other xylitol-containing products can prevent caries in infants, older children, or adults.

Visual scoring of non cavitated caries lesions and clinical trial efficiency, testing xylitol in caries-active adults

OBJECTIVES

To better understand the effectiveness of xylitol in caries prevention in adults and to attempt improved clinical trial efficiency.

METHODS

As part of the Xylitol for Adult Caries Trial (X-ACT), non cavitated and cavitated caries lesions were assessed in subjects who were experiencing the disease. The trial was a test of the effectiveness of 5 g/day of xylitol, consumed by dissolving in the mouth five 1 g lozenges spaced across each day, compared with a sucralose placebo. For this analysis, seeking trial efficiency, 538 subjects aged 21-80, with complete data for four dental examinations, were selected from the 691 randomized into the 3-year trial, conducted at three sites. Acceptable inter- and intra-examiner reliability before and during the trial was quantified using the kappa statistic.

RESULTS

The mean annualized noncavitated plus cavitated lesion transition scores in coronal and root surfaces, from sound to carious favoured xylitol over placebo, during the three cumulative periods of 12, 24, and 33 months, but these clinically and statistically nonsignificant differences declined in magnitude over time. Restricting the present assessment to those subjects with a higher baseline lifetime caries experience showed possible but inconsistent benefit.

CONCLUSIONS

There was no clear and clinically relevant preventive effect of xylitol on caries in adults with adequate fluoride exposure when non cavitated plus cavitated lesions were assessed. This conformed to the X-ACT trial result assessing cavitated lesions. Including non cavitated lesion assessment in this full-scale, placebo-controlled, multisite, randomized, double-blinded clinical trial in adults experiencing dental caries did not achieve added trial efficiency or demonstrate practical benefit of xylitol.

TRIAL REGISTRATION

ClinicalTrials.Gov NCT00393055.

Visual-tactile versus radiographic caries detection agreement in caries-active adults

OBJECTIVES

The study aims to determine a) the extent of agreement between visual-tactile caries examination (VTE) and radiographic examination (RE) in detecting presumptive caries lesions on occlusal and proximal surfaces of posterior teeth of UNC Xylitol for Adult Caries Trial participants; and b) the additional caries diagnostic yield obtained by adding RE to VTE.

METHODS

Data consisted of surface-level visual-tactile and radiographic classification of disease (cavitated and noncavitated caries lesions) or nondisease (sound surfaces). Participants (n = 114, adults with ≥12 erupted teeth and 1-10 caries lesions) received baseline VTE by a trained and calibrated examiner, and had interproximal radiographs obtained within 7 months before or after the VTE. Radiographs were assessed independently by two trained and calibrated examiners masked with respect to VTE results. The diagnostic threshold was surface-level disease/nondisease status. Kappa statistics provided an estimate of VTE-RE agreement on diseased surfaces. The additional diagnostic yield of the RE over VTE was calculated as the additional lesions detected radiographically as a percentage of the total number of lesions detected by VTE.

RESULTS

Four-hundred ninety-four (51 occlusal, 433 proximal) lesions were detected; of these, 81 (2 occlusal, 79 proximal) lesions were detected by both VTE and RE. Kappa statistics were 0.18 (all surfaces), 0.04 (occlusal), and 0.18 (proximal). The additional diagnostic yield was 69 percent (all surfaces), 55 percent (occlusal), and 71 percent (proximal).

CONCLUSIONS

There is poor agreement between VTE and RE to detect caries in posterior teeth of caries-active adults. However, an RE performed within 7 months of a VTE adds caries diagnostic yield in a clinical trial, especially on proximal surfaces.

Tooth-surface-specific effects of xylitol: randomized trial results

The Xylitol for Adult Caries Trial was a three-year, double-blind, multi-center, randomized clinical trial that evaluated the effectiveness of xylitol vs. placebo lozenges in the prevention of dental caries in caries-active adults. The purpose of this secondary analysis was to investigate whether xylitol lozenges had a differential effect on cumulative caries increments on different tooth surfaces. Participants (ages 21-80 yrs) with at least one follow-up visit (n = 620) were examined at baseline, 12, 24, and 33 months. Negative binomial and zero-inflated negative binomial regression models were used to estimate incidence rate ratios (IRR) for xylitol's differential effect on cumulative caries increments on root and coronal surfaces and, among coronal surfaces, on smooth (buccal and lingual), occlusal, and proximal surfaces. Participants in the xylitol arm developed 40% fewer root caries lesions (0.23 D2FS/year) than those in the placebo arm (0.38 D2FS/year; IRR = 0.60; 95% CI [0.44, 0.81]; p < .001). There was no statistically significant difference between xylitol and control participants in the incidence of smooth-surface caries (p = .100), occlusal-surface caries (p = .408), or proximal-surface caries (p = .159). Among these caries-active adults, xylitol appears to have a caries-preventive effect on root surfaces (ClinicalTrials.gov NCT00393055).

Clinical evidence for polyol efficacy

Xylitol is a safe dental caries preventive when incorporated into chewing gum or confections used habitually. The goal of this paper is to identify and assess the work on xylitol and other polyols and dental caries since 2008. Xylitol is effective when used by the mother prenatally or after delivery to prevent mutans transmission and subsequent dental caries in the offspring. One new completed trial confirmed that children of mothers who used xylitol lozenges after delivery had less dental caries than a comparison group. A similar study confirmed that the use of xylitol gum by the mother either prevented or postponed MS transmission to the offspring. Xylitol use among schoolchildren delivered via a gummy bear confection reduced S. mutans levels, but a once per day use of xylitol-containing toothpaste did not. Randomized trials, with caries outcomes, assessing xylitol-containing lozenges in adults and xylitol-containing gummy bears in children will release results in the coming year. Other studies are ongoing but are not systematic and will fail to answer important questions about how xylitol, or other polyols, can address the global dental caries problem.

Results from the Xylitol for Adult Caries Trial (X-ACT)

BACKGROUND

Although caries is prevalent in adults, investigators have tested few preventive therapies in adult populations. In a randomized controlled trial, the authors evaluated the effectiveness of xylitol lozenges in preventing caries in adults at elevated risk of developing caries.

METHODS

The Xylitol for Adult Caries Trial (X-ACT) was a three-site placebo-controlled randomized trial. Participants (n = 691) aged 21 through 80 years consumed five 1.0-gram xylitol or placebo lozenges daily for 33 months. They underwent clinical examinations at baseline and at 12, 24 and 33 months.

RESULTS

Xylitol lozenges reduced the caries increment 10 percent. This reduction, which represented less than one-third of a surface per year, was not statistically significant. There was no indication of a dose-response effect.

CONCLUSIONS

Daily use of xylitol lozenges did not result in a statistically or clinically significant reduction in 33-month caries increment among adults at an elevated risk of developing caries.

CLINICAL IMPLICATIONS

These results suggest that xylitol used as a supplement in adults does not reduce their caries experience significantly.

Risk indicators for the presence and extent of root caries among caries-active adults enrolled in the Xylitol for Adult Caries Trial (X-ACT)

OBJECTIVE

This paper uses baseline data from a randomized clinical trial to evaluate cross-sectional indicators of root caries in caries-active adults.

MATERIALS AND METHODS

Adults (21-80 years) having at least 12 erupted teeth and between one and ten caries lesions were enrolled. Participants (n = 437) received caries exams by trained, calibrated examiners and responded to baseline demographic and medical-dental questionnaires. We examined associations between baseline characteristics and (1) the presence of any root caries using Mantel-Haenszel hypothesis tests and odds ratio (OR) estimators and (2) the number of root surfaces with caries among study participants with exposed root surfaces (n = 349) using Mantel-Haenszel mean score tests and Mann-Whitney estimators.

RESULTS/CONCLUSIONS

Adjusting for study site and age, male gender [OR, 1.72; 95% confidence interval (CI), 1.08, 2.78], white race (OR, 2.39; 95% CI, 1.43, 3.98), recent dental visit (OR, 1.98; 95% CI, 1.07, 3.66), poor self-described oral health (OR, 2.65; 95% CI, 1.10, 6.39), and recent professional fluoride treatment (OR, 1.85; 95% CI, 1.06, 3.25) were significantly associated with increased odds to have any root caries, and study participants with exposed root surfaces characterized by male gender [Mann-Whitney probability estimate (MW) = 0.57; 95% CI, 0.51, 0.63), white race (MW, 0.61; 0.55, 0.68), recent dental visit (MW, 0.58; 0.50, 0.67), poor self-described oral health (MW, 0.61; 0.53, 0.69), and flossing at least once per day (MW, 0.57; 95% CI, 0.51, 0.62) were significantly more likely to have a greater number of root surfaces with caries than a randomly selected study participant from their respective complementary subgroups (female gender, non-white, etc.).

CLINICAL RELEVANCE

Our findings may help identify individuals at higher root caries risk.