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Base de datos Cochrane de Revisiones Sistemáticas Protocolo - Intervención

Dental filling materials for managing carious lesions in the primary dentition

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Versión publicada: 05 septiembre 2016 Historial de versiones

https://doi.org/10.1002/14651858.CD012338
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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects of different direct filling materials for managing carious lesions in the primary dentition.

Background

Description of the condition

Dental caries (more commonly known as tooth decay) develops when bacteria from food debris and sugar in the mouth release acids that demineralise and soften the tooth surface (Marsh 2006). The condition initially appears as white spot lesions of demineralised enamel. If the demineralisation process is not interrupted or reversed, carious lesions can progress further into the tooth structure and form cavities. Ultimately, untreated caries can lead to infection and tooth loss. Children who require extraction of decayed primary teeth also face an increased risk of developing orthodontic problems due to premature primary dentition loss (Law 2013).

Dental caries is a chronic disease that is almost entirely preventable, and usually manifests from a combination of the following risk factors: poor oral hygiene, frequent sugar consumption, and lack of exposure to topical sources of fluoride, which is understood to have a cariostatic effect (Rošin‐Grget 2013; Rugg‐Gunn 2013; WHO 2010).

Untreated caries in the primary dentition is the 10th most prevalent health condition worldwide, and is estimated to affect 621 million children (Kassebaum 2015). The World Health Organization's (WHO) geographical estimation of disease burden indicates that children in the Southeast Asian region suffered the greatest burden of caries in 2012 (36% of the total global caries disability‐adjusted life years (DALYs) burden from birth to 14 years), followed by children in the Western Pacific (19%) and African regions (18%), and to a lesser extent by children in the Eastern Mediterranean region (11%), the Americas (9%), and the European region (7%; WHO 2014a).

According to the WHO's estimation of disease burden by World Bank region, children from high‐income countries collectively accounted for only 6% of the total global caries DALYs burden in 2012. Of the six low‐ and middle‐income World Bank regions, children in South Asia suffered the greatest DALYs burden of caries in 2012 (35% of global total), followed by East Asia and Pacific (25%), Sub‐Saharan Africa (19%), Latin America and the Caribbean (7%), the Middle East and North Africa (5%), and Europe and Central Asia (3%; WHO 2014b).

Despite the fact that the European region suffered the lowest burden of disease from dental caries, 28% of children in the UK suffered from tooth decay at the age of five (Public Health England 2012), and dental caries was the most common cause of hospital admissions for children aged five to nine years (Royal College of Surgeons of England 2015). In low‐income countries, the problem of caries among children is of even greater concern, due to the combination of high prevalence and limited resources that present substantial access barriers to oral healthcare services. Consequently, it is clear that this chronic disease presents a significant global burden for health service resources (Rugg‐Gunn 2013).

Dental caries can have a substantial impact on children's quality of life (QoL); not only causing pain and difficulties with eating, but also affecting school attendance and disrupting sleep patterns, potentially affecting growth and educational performance (Finucane 2012; Guarnizo‐Herreño 2012).

The prevalence of dental caries is strongly associated with deprivation, whereby children from low‐income families suffer a greater burden of caries than children from more affluent backgrounds (Schwendicke 2015; Thomson 2012). This trend of social inequality continues into adulthood, and independent of deprivation level, children who suffer from caries are at increased risk of developing carious lesions as adults (Thomson 2004; Thomson 2012).

Description of the intervention

Once carious lesions are identified in the primary dentition, dentists and dental auxiliaries have a range of options available to restore the decayed tooth's structure.

Direct restorations allow dental professionals to place and shape a malleable filling material, which then hardens, during a single appointment. Depending on the choice of filling material, liners may be used to protect the pulp, or the use of enamel etching, adhesives, and light curing may be required (American Dental Assocation 2002). This review will not assess effectiveness of preformed metal crowns or cavity liners, as they are addressed by other Cochrane reviews (Innes 2015; Schenkel 2013).

Direct filling materials can be categorised as non‐aesthetic or aesthetic. Non‐aesthetic filling materials are constructed from a combination of metal alloys (known as amalgam) and are perceived to provide dental professionals with a strong, well‐retained, and cost‐effective option (American Dental Assocation 2002; Rasines Alcaraz 2014; WHO 2010). It should be acknowledged that there has been a global decline in the use of amalgam as a dental filling material over the past decade as a result of the Minamata Convention, due to (largely environmental) concerns over toxicity relating to potential mercury release (American Academy of Pediatric Dentistry 2014; Rodríguez‐Farre 2016; United Nations Environment Programme 2013).

At one end of the aesthetic restoration spectrum, resin composites (RC), which are made from a mix of plastic resin and powdered glass, are strong and resemble the natural colour of teeth, but they are more expensive to produce than amalgam, and require more time and greater expertise to fit (for example, ensuring moisture control; American Academy of Pediatric Dentistry 2014; DeRouen 2006; WHO 2010).

An alternative is glass ionomer cement (GIC), which is made from a combination of acid and powdered glass. GIC also resembles tooth colour (although the appearance is reduced because it is more translucent than RC), but is more biocompatible as a material and claims to be able to release fluoride for up to a year after placement, although this is disputed (American Academy of Pediatric Dentistry 2014; American Dental Assocation 2002; Dionysopoulos 2014; WHO 2010). It is thought that the GIC fluoride‐release function also provides a mechanism whereby use of topical fluoride 'recharges' the GIC to maintain ongoing fluoride release (Dionysopoulos 2014; Gururaj 2013).

Other chemical classifications of aesthetic filling materials are found along the spectrum between RC and GIC (WHO 2010). Polyacid‐modified RC ((PAMRC), also known as compomer) is a variation of RC that combines some of the acidic properties of GIC to release a smaller dose of fluoride (Nicholson 2007). Resin‐modified GIC (RMGIC) is a modification of GIC whereby resin is introduced to provide increased strength (Sidhu 2010).

Different filling materials require different techniques for restoration placement and retention: amalgam requires preparation of retentive undercuts (known as macro‐retention) to mitigate the material's inability to adhere; RC use an adhesive system to forge a micro‐retentive bond with the tooth's structure, although the choice of bonding agent may require additional tooth surface pretreatment before placement; and GIC’s chemical adhesion bonds the material to the tooth structure without requiring additional adhesive or cavity pretreatment (Da Silva 2011).

How the intervention might work

Cavitated carious lesions in primary teeth are frequently managed by placement of dental fillings. This treatment aims to replace missing dental tissue in order to aid plaque control, restore tooth function, and protect the pulp‐dentine complex by sealing the cavity (Schwendicke 2016a). The clinical success of such an intervention is dependent on the properties of the filling material and its integrity in the restored cavity, amongst other factors (Schwendicke 2016b). A number of different dental filling materials are available for the restoration of carious lesions in primary teeth, as outlined above.

Amalgam has been widely used as a dental filling material for several decades. This material combines favourable mechanical properties with ease of placement (low technique sensitivity); however, as amalgams are not able to chemically or adhesively bond to the tooth structure, retentive undercuts have to be prepared and result in higher loss of tooth substance compared to other materials (Fuks 2015).

Resin‐based materials, such as compomers and composites, are frequently used as an alternative to amalgams. As these materials bond to the tooth structure by use of an adhesive system, they allow for minimally‐invasive cavity preparation; however, placement of resin‐based fillings is more technique sensitive and requires a longer placement time, as these materials are susceptible to moisture contamination due to their hydrophobic character (Dhar 2015; Tobi 1999). At the other end of the aesthetic restoration spectrum, GIC and RMGIC chemically bond to the tooth structure, and are less susceptible to moisture contamination compared to resin‐based materials; however, these materials show lower fracture resistance compared to resin‐based materials and amalgam (Mount 1998).

Although the performance of these different materials has been assessed in different investigations, it is still unclear which filling material is preferable in terms of clinical success for placement in cavitated carious lesions in primary teeth.

Why it is important to do this review

Cochrane Oral Health undertook an extensive prioritisation exercise in 2014 to identify a core portfolio of review titles that were the most clinically important reviews to maintain in the Cochrane Library (Worthington 2015). This topic was identified as a priority title by the paediatric dentistry expert panel (Cochrane Oral Health priority review portfolio). The scope of a previous Cochrane review required expansion (Yengopal 2009), therefore we have developed this new protocol and updated the methods in line with current Cochrane standards.

Objectives

To assess the effects of different direct filling materials for managing carious lesions in the primary dentition.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials (RCTs) with either a parallel group or a split‐mouth design. They must have a minimum of six months follow‐up.

The following units of randomisation may be included: individual, group (e.g. school or class), tooth, or tooth pair.

Types of participants

We will include children with cavitated carious lesions in the primary dentition. All classes of cavity may be included.

Types of interventions

We will include all types of direct filling materials (irrespective of cavity preparation technique or tooth vitality); regardless of whether they are placed by dentists or dental auxiliaries (e.g. dental therapists).

We will group types of filling materials by chemical classification (regardless of curing properties). We will include studies that evaluate one type of filling material compared with an alternative type of filling material:

  • amalgam;

  • resin composites (RC);

  • polyacid‐modified resin‐based composites (PAMRC), alternatively known as compomers;

  • conventional glass ionomer cements (GIC);

  • resin‐modified GIC (RMGIC).

Types of outcome measures

Primary outcomes

  • Need to retreat invasively (including filling material failure such as loss or gross fracture, tooth fracture, extraction, replacement, secondary caries, pain). Presented as dichotomous data, VAS data, or as time‐to‐event or relevant count data

Secondary outcomes

  • Minor failures, including repair (requiring additional restorative material), refurbishment (correction without additional restorative material) or systematic monitoring (filling material deterioration observed without clinical disadvantage from not treating). Presented as dichotomous data, or as time‐to‐event or relevant count data

  • Adverse events (including tooth fracture at placement, subjective impact, future participant co‐operation and allergies)

  • Oral health‐related quality of life (OHQoL), as measured by self report (child only, or child with parent or carer) using OHQoL measures validated for use with children

  • Efficiency (e.g. placement procedure duration)

  • Cost

Search methods for identification of studies

Cochrane Oral Health’s Information Specialist will conduct systematic searches for randomised controlled trials and controlled clinical trials.

Electronic searches

We will search the following databases:

  • Cochrane Oral Health’s Trials Register;

  • the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library;

  • MEDLINE Ovid (from 1946 onwards);

  • Embase Ovid (from 1980 onwards).

The subject strategies for databases will be modelled on the search strategy designed for MEDLINE Ovid in Appendix 1. This will be combined with subject strategy adaptations of the highly sensitive search strategy designed by Cochrane for identifying randomised controlled trials and controlled clinical trials (as described in the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0, Box 6.4.c. (Lefebvre 2011). The Embase subject search will be linked to an adapted version of the Cochrane Embase Project filter for identifying RCTs in Embase Ovid (see the Cochrane Library for information).

Searching other resources

We will search the following trials registries:

We will check the bibliographies of included studies and any relevant systematic reviews identified for further references to relevant trials.

We will not perform a separate search for adverse effects of interventions used, we will consider adverse effects described in included studies only.

Data collection and analysis

Selection of studies

Two review authors will independently screen the titles, keywords and abstracts of retrieved search records' content to determine whether studies may be potentially relevant. We will retrieve the full‐text paper for studies that appear to meet the inclusion criteria, or for which there are insufficient data in the record to make a clear decision.

Two review authors will independently assess the eligibility of each full‐text paper for inclusion, and disagreements will be resolved by discussion with a third review author. We will also scrutinise each study paper for multiple publications originating from the same trial's data.

After consideration of the full‐text paper, we will exclude any studies that do not fulfill the inclusion criteria and state the rationale for their exclusion in 'Characteristics of excluded studies' tables.

Data extraction and management

Two review authors will independently extract study details and outcome data from included studies using a piloted extraction form designed for this review. We will extract the following data:

  • methods (study design; clinical setting and location; recruitment period; number of participants randomised; participant attrition; allocation method and concealment attempts; blinding procedures for participants, clinical operators, and outcome assessors);

  • participants (age; sex; demographics; inclusion and exclusion criteria; pulp health status);

  • comparisons (filling materials; details of preparatory and adjunctive materials (e.g. technique, adhesives or lining materials); use of pain relief or sedation);

  • outcomes (outcomes of interest to this review (as defined under Types of outcome measures); other clinical investigations undertaken; duration of follow‐up; observation timepoints).

We will also record other salient information, where available, to inform our assessment of included studies (e.g. source of funding; conflict of interests).

We will resolve discrepancies between different review authors' data extraction by discussion with a third review author.

Assessment of risk of bias in included studies

As indicated in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a), two review authors will independently assess the risk of bias within individual included studies by evaluating seven key domains:

  • sequence generation (selection bias);

  • allocation concealment (selection bias);

  • blinding of participants and personnel (performance bias);

  • blinding of outcome assessors (detection bias);

  • incomplete outcome data (attrition bias);

  • selective outcome reporting (reporting bias);

  • other bias.

We will categorise each individual study's 'Risk of bias' domains as being at:

  • low risk of bias (a plausible bias considered unlikely to seriously alter results);

  • high risk of bias (a plausible bias that seriously weakens confidence in results); or

  • unclear risk of bias (a plausible bias that raises some doubt about the results).

We will compare and discuss the independent assessments of risk of bias with a third review author to resolve any disagreements. Once consensus is found, we will report assessments for each included study in the study's corresponding 'Risk of bias' table (under 'Characteristics of included studies' tables).

We will categorise the overall risk of bias for an individual study as:

  • low, where all domains are categorised as low risk;

  • unclear, where one or more domains is considered to be at an unclear risk; or,

  • high, where one or more domains is categorised as high risk.

Measures of treatment effect

We will express estimates of effect for dichotomous outcomes as risk ratios (RR), along with 95% confidence intervals (CIs). Where we find time‐to‐event data (e.g. loss, gross fracture, or extraction), we will present these effect estimates also as hazard ratios (HR).

We will express continuous outcomes as mean differences (MD) with 95% CIs. In the event that included studies assess a common continuous outcome using different measures or scales, we will estimate the standardised mean difference (SMD) as a summary statistic.

Unit of analysis issues

In parallel RCTs, the unit of randomisation will be at an individual level (patient or tooth); however, in split‐mouth RCTs, as different teeth will have been randomly assigned to different interventions in each individual participant, our unit of analysis will be the tooth pair within an individual. For split‐mouth studies treating more than one pair of teeth per child, we will attempt to analyse the paired data on a per child level where possible.

Where cluster‐RCTs are identified for inclusion and their respective publication does not account for the clustering effect, we will analyse those data at an individual level while also properly accounting for the cluster design (as the data from those studies cannot be assumed to be independent) by using an intraclass correlation coefficient (ICC) of 0.05 (ICC level used by two other Cochrane reviews on caries (Marinho 2013; Riley 2015)) to estimate the design effect, following appropriate methods detailed in section 16.3.4 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b).

Dealing with missing data

We will attempt to contact trial authors to obtain missing data where necessary.

Where we find instances of missing standard deviations, we will use the methods detailed in section 7.7.3 of the Cochrane Handbook for Systematic Reviews of Interventions to impute them (Higgins 2011c).

Assessment of heterogeneity

We will consider clinical diversity of participants, interventions and outcomes prior to combining studies in meta‐analyses to ensure studies are sufficiently homogenous to estimate a meaningful summary effect.

In meta‐analyses containing a sufficient number of studies, we will initially assess statistical heterogeneity by visual inspection of point estimates (and their respective CIs) in forest plots, followed by a Chi² test assessment (using a P value of 0.10 to determine statistical heterogeneity), and then quantified by the I² statistic.

In accordance with methods detailed in section 9.5.2 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011), the I² statistic will roughly be interpreted as:

  • 0% to 40%: might not be important;

  • 30% to 60%: may represent moderate heterogeneity;

  • 50% to 90%: may represent substantial heterogeneity;

  • 75% to 100%: represents considerable heterogeneity.

We will assess the heterogeneity of values that fall across these rough thresholds by the direction and magnitude of effects, and by strength of evidence for heterogeneity (e.g. Chi² test P value and I² CI; Deeks 2011)

Assessment of reporting biases

Where we are able to include a sufficient number of studies (10 or more) within a meta‐analysis, we will investigate publication bias by evaluating funnel plot asymmetry (Egger 1997). Where asymmetry is identified, we will investigate possible causes.

Data synthesis

We will group and analyse studies of similar comparisons, according to their chemical classification of filling material (see Types of interventions), for the most clinically‐relevant observations (short term: 12 months or less; medium term: between 12 and 36 months; long term: longer than 36 months).

Generally, we will apply a random‐effects model to pooled data, as the CI of the average intervention effect will be wider than that obtained from a fixed‐effect model, and will consequently lead to a more conservative interpretation.

Subgroup analysis and investigation of heterogeneity

Where data allow, we will explore potential sources of heterogeneity in the overall treatment effect in the following subgroup analyses:

  • participant age (six years or younger; older than six years);

  • study design (parallel; split‐mouth);

  • restoration location (anterior; posterior), restoration size (number of surfaces involved), Black cavity classification (Classes I‐V), depending upon how it is reported in the included studies.

Sensitivity analysis

Where there are a sufficient number of studies included in any meta‐analyses, we will undertake sensitivity analyses to assess the robustness of results by excluding studies judged to have an unclear or high risk of bias overall.

In the event that any meta‐analyses combine a single large study with several smaller trials, we will undertake sensitivity analyses to compare effect estimates produced by the fixed‐effect and random‐effects models. If these estimates lead to different interpretations of the data, we will report both models and attempt to investigate the difference.

Summary of findings

In accordance with the methods detailed in Chapter 12 of the Cochrane Handbook for Systematic Reviews of Interventions (Schünemann 2011), we will evaluate the quality of the evidence from this review using GRADE methods (GRADE 2004) and the corresponding GRADEpro software (GRADEpro) by assessing:

  • overall risk of bias of included studies;

  • directness of the evidence;

  • consistency of the results;

  • precision of the estimates; and

  • risk of publication bias

We will classify the quality of the body of evidence for each comparison and outcome in the review as high, moderate, low, or very low.

We will summarise each comparison's body of evidence (the magnitude of effect from interventions examined, the sum of available data for the review's primary and secondary outcomes, and the overall quality of the evidence) in a 'Summary of findings' (SoF) table. In the footnotes of each SoF table, we will provide a rationale for the assumed risk of each outcome, and cite the source of the assumed risk figure.