Longevity of materials for pit and fissure sealing—Results from a meta-analysis

Abstract

Objective

This meta-analysis investigates the clinical retention of pit and fissure sealants in relation to observation time and material type.

Data, sources and study selection

A search in the MEDLINE, EMBASE and CENTRAL databases identified 2944 abstracts (published prior to 9/30/2011), of which 485 clinical publications were analyzed in detail. A total of 146 articles included information about sealant retention, with a minimum observation time of 2 years. These publications were analyzed to determine the retention rates of the various materials studied (UV-light-, light- and auto-polymerizing resin-based sealants, fluoride-releasing materials, compomers, flowable composites and glass-ionomer-cement-based sealants). The meta-analysis used random effects models for longitudinal logistic regression and Bayesian statistics.

Results

As part of the systematic review, 98 clinical reports and 12 field trial reports were identified. Auto-polymerizing sealants had the longest observation time (up to 20 years) and were found to have a 5-year retention rate of 64.7% (95%CI = 57.1–73.1%), which was estimated from the meta-analysis model. Resin-based light-polymerizing sealants and fluoride-releasing products showed similar 5-year retention rates (83.8%, 95%CI = 54.9–94.7% and 69.9%, 95%CI = 51.5–86.5%, respectively) for completely retained sealants. In contrast to these high retention rates, poor retention rates were documented for UV-light-polymerizing materials, compomers and glass-ionomer-cement-based sealants (5-year retention rates were <19.3%). Retention rates for UV-light-polymerizing materials, compomers and glass-ionomer-cement-based sealants were classified as inferior.

Conclusions versus Significance

The results of this meta-analysis suggested that resin-based sealants can be recommended for clinical use. The faster and less error-prone clinical application of light-polymerizing materials, however, makes them the preferred choice for daily dental practice.

Introduction

After the introduction of the adhesive bonding technique with resin-based dental materials and the first description of pit and fissure sealing , half-mouth studies to assess the effectiveness of sealants in preventing caries were common until the end of the 1970s . In the half-mouth studies, sealed teeth were compared with untreated controls. However, once the protective effect of pit and fissure sealants had been proven in the 1980s, half-mouth studies became unethical. Since the 1980s, an assessment of the ability of pit and fissure sealants to protect pits and fissures and a quantification of the clinical longevity of various sealing materials has mainly been accomplished via studies that use sealant retention rate as the relevant endpoint. The retention rates of sealants are typically classified according to the following categories: “intact sealant”, “partial loss of material” and “complete loss of material”. Because optimum protection is only guaranteed if the sealant completely covers all of the pits and fissures , the clinical adequacy of a sealing material and/or application technique may only be assumed if it falls into the “intact sealant” category, which is the leading criterion today.

While several systematic reviews have confirmed the caries-protective effect of pit and fissure sealing , studies have not conclusively demonstrated which sealant materials are the most effective. Therefore, the present meta-analysis of the literature investigated the prior clinical studies that have provided data on retention rates in relation to the sealant material and the observation time. Based on this evaluation, the present meta-analysis provided evidence-based recommendations for clinical practice.

Methods

Systematic literature review

The basis for this systematic review was a classification of the scientific literature (available prior to 9/30/2011) that documented pit and fissure sealing. The following study types were considered relevant for the analysis: clinical trials and field trials. Only studies that ran 2 years or longer were considered in this analysis. Case reports and in vitro studies were not used because the analysis was restricted to studies with clear clinical relevance.

The first step of the analysis involved searching the MEDLINE, EMBASE and CENTRAL (Cochrane Central Register of Controlled Trials) databases using the keywords (“fiss*” and “seal*”), title, abstract and considerations about suitability. For the above-mentioned period until 09/30/2011, 2944 primary citations matching the search terms and inclusion criteria were identified. If information relevant to the inclusion criteria was not available in the abstract or if the title was relevant but the abstract was not available, the full text of the report was obtained. After reviewing the abstracts, 485 remaining publications were considered relevant and were used for a more detailed analysis.

For all of the studies with potential relevance for the meta-analysis ( n = 485), the full texts were obtained from local libraries, online sources and/or by directly contacting the author(s). Requested articles that were not available in full by 9/30/2011 were not considered. In the end, 110 clinical reports were included in the meta-analysis.

Standardized evaluation of the reference material

The chosen publications were assessed in a standardized manner to systematically record the relevant details. The following parameters were documented: the study design, the observation time, the number of subjects, the number of primarily sealed molars (premolars were excluded from the analysis), the type of sealant material, the number of completely retained sealants in relation to the observation time and the overall number of sealants in relation to the observation time. The number of sealants was recorded as an absolute number. If studies for which only percentages were published, each rate was calculated based on the available data. Missing numerical values were recorded as “not reported”. The documented findings were summarized in tables for each type of material (see the additional online content ).

Statistical analysis

In addition to the descriptive analysis of the recorded retention rates, we followed recommendations on the execution of meta-analyses for observational studies . The heterogeneity between studies was assessed using random effects models . To compensate for aspects that were not explicitly coded, study-specific random effects were used. We modeled the time courses for the retention rates of each group of materials based on the following formula:

<SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='logit(retentionrateattimet)=c0,mat+c1,mat×t.’>logit(retentionrateattimet)=c0,mat+c1,mat×t.logit(retentionrateattimet)=c0,mat+c1,mat×t.
logit ( retention rate at time t ) = c 0 , mat + c 1 , mat × t .

The c 0,mat coefficient includes a random effect that expresses the study-specific initial success rate. The c 1,mat coefficient defines the decrease of the retention rate over time and also includes a random effect that expresses the study-specific decrease. Therefore, we could calculate a population-based curve for the retention rate of each material as a function of time.

Current methods for meta-analyses have a number of unresolved issues, such as the choice between fixed- and random-effects models, the choice of population distribution in a random-effects analysis, the treatment of small studies and outliers, and the incorporation of study-specific covariates. These problems influence our systematic review and cannot be objectively or unambiguously solved. Smith et al. described how a full Bayesian analysis examines the necessary assumptions behind a model as a whole, and Bayesian analyses are now well-established and commonly used . Bayesian analyses are generally available using the WinBUGS implementation of Markov chain Monte Carlo numerical integration techniques. These last mentioned methods are of special interest when the lack of homogeneity between trials prevents a practical summarization into one figure. Therefore, the principles of Bayesian statistics were used in the present meta-analysis to estimate the model parameters. The Bayesian calculation uses noninformative priors, and the credibility intervals (CI) can consequently be interpreted as confidence intervals for the corresponding maximum likelihood estimates. A wide 95%CI (which is similar to the confidence interval) for the retention rate reflects the general uncertainty that exists for the overall effect of interest, whereas a narrow 95%CI represents a high certainty. The calculation was performed using WinBUGS V1.4 (WinBUGS—The BUGS Project: 2007, WinBUGS 1.4.3.edn, which is available at www.mrc-bsu.cam.ac.uk/bugs/winbugs/contents.shtml ).

Methods

Systematic literature review

The basis for this systematic review was a classification of the scientific literature (available prior to 9/30/2011) that documented pit and fissure sealing. The following study types were considered relevant for the analysis: clinical trials and field trials. Only studies that ran 2 years or longer were considered in this analysis. Case reports and in vitro studies were not used because the analysis was restricted to studies with clear clinical relevance.

The first step of the analysis involved searching the MEDLINE, EMBASE and CENTRAL (Cochrane Central Register of Controlled Trials) databases using the keywords (“fiss*” and “seal*”), title, abstract and considerations about suitability. For the above-mentioned period until 09/30/2011, 2944 primary citations matching the search terms and inclusion criteria were identified. If information relevant to the inclusion criteria was not available in the abstract or if the title was relevant but the abstract was not available, the full text of the report was obtained. After reviewing the abstracts, 485 remaining publications were considered relevant and were used for a more detailed analysis.

For all of the studies with potential relevance for the meta-analysis ( n = 485), the full texts were obtained from local libraries, online sources and/or by directly contacting the author(s). Requested articles that were not available in full by 9/30/2011 were not considered. In the end, 110 clinical reports were included in the meta-analysis.

Standardized evaluation of the reference material

The chosen publications were assessed in a standardized manner to systematically record the relevant details. The following parameters were documented: the study design, the observation time, the number of subjects, the number of primarily sealed molars (premolars were excluded from the analysis), the type of sealant material, the number of completely retained sealants in relation to the observation time and the overall number of sealants in relation to the observation time. The number of sealants was recorded as an absolute number. If studies for which only percentages were published, each rate was calculated based on the available data. Missing numerical values were recorded as “not reported”. The documented findings were summarized in tables for each type of material (see the additional online content ).

Statistical analysis

In addition to the descriptive analysis of the recorded retention rates, we followed recommendations on the execution of meta-analyses for observational studies . The heterogeneity between studies was assessed using random effects models . To compensate for aspects that were not explicitly coded, study-specific random effects were used. We modeled the time courses for the retention rates of each group of materials based on the following formula:

<SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='logit(retentionrateattimet)=c0,mat+c1,mat×t.’>logit(retentionrateattimet)=c0,mat+c1,mat×t.logit(retentionrateattimet)=c0,mat+c1,mat×t.
logit ( retention rate at time t ) = c 0 , mat + c 1 , mat × t .
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Nov 28, 2017 | Posted by in Dental Materials | Comments Off on Longevity of materials for pit and fissure sealing—Results from a meta-analysis
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