cd 007517

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Adhesively bonded versus non-bonded amalgam restorations

for dental caries (Review)

Fedorowicz Z, Nasser M, Wilson N

This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published inThe Cochrane Library

2009, Issue 4

http://www.thecochranelibrary.com

Adhesively bonded versus non-bonded amalgam restorations for dental caries (Review)

Copyright 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
http://www.thecochranelibrary.com/http://www.thecochranelibrary.com/

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T A B L E O F C O N T E N T S

1HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8AUTHORS CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14ADDITIONAL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17INDEX TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

iAdhesively bonded versus non-bonded amalgam restorations for dental caries (Review)


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[Intervention Review]

Adhesively bonded versus non-bonded amalgam restorationsfor dental caries

Zbys Fedorowicz1, Mona Nasser2, Nairn Wilson3

1UKCC (Bahrain Branch), Ministry of Health, Bahrain, Awali, Bahrain. 2Department of Health Information, Institute for Quality

and Efficiency in Health care, Cologne, Germany. 3 Kings College London Dental Institute at Guys, Kings College and St Thomas

Hospitals, London, UK

Contact address: Zbys Fedorowicz, UKCC (Bahrain Branch), Ministry of Health, Bahrain, Box 25438, Awali, Bahrain.

[email protected].

Editorial group:Cochrane Oral Health Group.

Publication status and date:New, published in Issue 4, 2009.

Review content assessed as up-to-date: 23 July 2009.

Citation: Fedorowicz Z, Nasser M, Wilson N. Adhesively bonded versus non-bonded amalgam restorations for dental caries.CochraneDatabase of Systematic Reviews2009, Issue 4. Art. No.: CD007517. DOI: 10.1002/14651858.CD007517.pub2.


A B S T R A C T

Background

Dental caries (tooth decay) is one of the commonest diseases which afflicts mankind, and has been estimated to affect up to 80% of

people in high-income countries. Caries adversely affects and progressively destroys the tissues of the tooth, including the dental pulp

(nerve), leaving teeth unsightly, weakened and with impaired function. The treatment of lesions of dental caries, which are progressing

through dentine and have caused the formation of a cavity, involves the provision of dental restorations (fillings).

Objectives

To assess the effects of adhesive bonding on the in-service performance and longevity of restorations of dental amalgam.

Search methods

Databases searched July 2009: the Cochrane Oral Health Groups Trials Register; CENTRAL (The Cochrane Library2009, Issue 3);

MEDLINE (1950 to July 2009); and EMBASE (1980 to July 2009).

Selection criteria

Randomised controlled trials comparing adhesively bonded versus traditional non-bonded amalgam restorations in conventional

preparations utilising deliberate retention, in adults with permanent molar and premolar teeth suitable for Class I and II amalgam

restorations only.

Data collection and analysis

Two review authors independently screened papers, extracted trial details and assessed the risk of bias in the included study.

Main results

One trial with 31 patients who received 113 restorations was included. At 2 years only 3 out of 53 restorations in the non-bonded group

were lost, which was attributed to a lack of retention, and 55 of 60 bonded restorations survived with five unaccounted for at follow-

up. Post-insertion sensitivity was not significantly different (P > 0.05) at baseline or 2-year follow-up. No fractures of tooth tissue were

reported and there was no significant difference between the groups or matched pairs of restorations in their marginal adaptation (P >

0.05).

1Adhesively bonded versus non-bonded amalgam restorations for dental caries (Review)

mailto:[email protected]:[email protected]

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Authors conclusions

There is no evidence to either claim or refute a difference in survival between bonded and non-bonded amalgam restorations. This

review only found one methodologically sound but somewhat under-reported trial. This trial did not find any significant difference in

the in-service performance of moderately sized adhesively bonded amalgam restorations, in terms of their survival rate and marginal

integrity, in comparison to non-bonded amalgam restorations over a 2-year period. In view of the lack of evidence on the additional

benefit of adhesively bonding amalgam in comparison with non-bonded amalgam, it is important that clinicians are mindful of theadditional costs that may be incurred.

P L A I N L A N G U A G E S U M M A R Y

Adhesively or non-adhesively bonded amalgam restorations for dental caries

Tooth decay is a common problem affecting both children and adults. Cavities form in the teeth by the action of acid producing

bacteria present in dental plaque.

A number of techniques and a variety of materials can be used to restore teeth and one of the most commonly used and comparatively

cheap filling material is dental amalgam (a mixture of mercury and metal alloy particles). The review authors sought to evaluate the

added benefit of using an adhesive to bond amalgam to tooth structure to see if bonded fillings would last longer.

Only one study, which provided limited data, showed that for medium sized fillings there was no difference in sensitivity between the

bonded and non-bonded fillings after their placement and that bonding of amalgam to tooth did not have any effect on the survival

of the filling over a 2-year period and thus the time taken for the additional step in addition to the cost of bonding material cannot be

justified.

B A C K G R O U N D

Dentalcaries (toothdecay) is oneof thecommonest diseases which

afflicts mankind, and has been estimated to affect up to 80% of

people in high-income countries (Chadwick 2001). Caries is a

term used to denote both lesions of caries and the carious process,

the demineralisation of enamel, dentine and cementum caused by

organic acids produced by acidogenic bacteria in dental plaque.

Across the world the incidence and severity of caries is strongly

associated with social deprivation, with a focus in children and, in-

creasingly, older people who have retained a number of their natu-

ral teeth (WHO 2005). Despite caries being preventable through,

in particular, effective oral hygiene, dietary control and the use of

anticariogenic agents, notably fluoride in toothpastes and when

administered systemically, it is anticipated to remain a commondisease for the foreseeable future, with the prevalence being great-

est in many of the developing countries (Yee 2002) .

Consequences of caries

Caries adversely affects and progressively destroys the tissues of the

tooth, including the dental pulp (nerve), leaving teeth unsightly,

weakened and with impaired function, subsequent to the disease

process causing parts of the teeth to cavitate and fracture under

loading. Carious teeth can becomepainful when advancing lesions

of caries cause pulpal inflammation. If untreated pulpal inflam-

mation becomes irreversible and the pulp dies, with the possibility

of infection passing out of the tooth to cause a dental abscess.

Caries is an opportunistic, infectious disease responsible for a great

deal of human suffering. Where dental healthcare systems exist,

caries is responsible for a substantial financial burden which in-

creases with recurrence of the disease process (Burke 2001;Yee

2002).

Treatment

The treatment of lesions of dental caries, which are progressing

through dentine andhavecaused theformation of a cavity, involves

the provision of dental restorations (fillings). Restorations can be

of many different forms and various materials, with variations in

technique sensitivity and durability.



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Dental amalgam

Despite many important developments in dental materials and

minimally interventive techniques, in many parts of the world

most restorations tend to continue to be of a traditional form and

of the material most widely used in dentistry over at least the last

100 years i.e. dental amalgam (Berry 1998). This material, a com-bination of mercury and alloy particles of different compositions

and form is cost effective in the management of dental caries, but

lacking many of the features of an ideal dental filling material

(Downer 1999;Mackert 2004).

A major limitation of dental amalgam, other than its poor appear-

ance, is itsinability to bond to remaining tooth tissues, andthereby

form a seal between restoration and tooth. This limitation is to a

variable extent countered by dental amalgam corrosion products

building up in the restoration/tooth interface, and thereby help-

ing to limit the negative effects of the interfacial percolation of

oral fluids, including cariogenic bacteria and their food substrate

of fermentable carbohydrates (Ben-Amar 1995).

Bonding

With the development of systems to bond tooth-coloured dental

filling materials to calcified tooth tissues (enamel and dentine),

there were investigations to determine if bonding systems could

be applied to dental amalgams, and thereby address certain limi-

tations in the use of such metallic materials (Turner 1995). These

investigations, which included a small number of short duration

clinical studies were considered, at the turn of the century, to in-

dicate that there was evidence accruing clinically that the bonding

of dental amalgams could be used, despite its technique sensitivity

and technical difficulties, to extend the range of usage of dentalamalgam to non-retentive conservative preparations and, toward

the other extreme, as an adjunct to other forms of retention in

large compound (complex) restorations (Setcos 2000) thereby of-

fering opportunity to conserve sound tooth structure.

Given the above and the recognition that dental amalgams will,

for the foreseeable future, remain the material of choice for certain

restorations in posterior teeth, including the replacement therapy

for existing amalgam fillings (SCENIHR 2007), it is considered

important to undertake a systematic review of recent clinical find-

ings on adhesively bonded versus non-bonded amalgam restora-

tionsin themanagementof dentalcaries.Thisreview buildson ear-

lier non-Cochrane reviews which assessed the longevity of routine

dental restorations (Chadwick 2001;Downer 1999), and whilstthere are differing views over the point at which restorations may

require replacement there is a consensus that the survival time for

amalgam fillings is within a range of 10 to 20 years.

O B J E C T I V E S

To assess the effects of adhesive bonding on the in-service perfor-

mance and longevity of dental amalgam restorations.

M E T H O D S

Criteria for considering studies for this review

Types of studies

Randomised controlled clinical trials (RCTs) to include paired

tooth and split-mouth study designs, with a minimum length of

follow-up of 2 years. The unit of randomisation considered was

either at the level of the tooth or the individual patient.

Only studies thatassessed the in-serviceperformance andlongevityof restorations using clearly defined criteria e.g. United States Pub-

lic Health Service (USPHS) or any recognised modifications to

these criteria were included in the review (Hickel 2007).

Types of participants

Adults and adolescents with permanent posterior molar and pre-

molar teeth suitable for Class I andII, butexcluding Class V, amal-

gam restorations.

Types of interventions

Adhesively bonded versus traditional non-bonded amalgam

restorations in conventional preparations utilising deliberate re-

tention. All types of bonding agents were considered.

Types of outcome measures

The main outcome of interest was the longevity/survival of the

restorations as assessed by clinical examination and defined by the

USPHScriteria,Ryge criteriaor modifications of these scales(Ryge

1981). Longevity represents the survival rate of the restorations

at specified time points or at completion of the study. Failure

is defined as the total mechanical failure of the restoration i.e.

mobility, fracture, missing in part or in total or the death of the

pulp and/or catastrophic failure leading to the extraction of the

tooth.

Although we intended categorising outcome data at defined time

points, in order that we capture data on early failures there was no

minimum follow-up.



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Primary outcomes

The nature of the primary outcome data (survival/failure) sought

in this review was principally dichotomous.

1. Survival of the restoration: longevity/survival to defined

time points yearly up to a maximum of 10 years and if available:

time-to-first-event and failure-free survival presented as theproportion of restorations placed that survived after a designated

period of time of 1, 2, 5 and 10 years.

Secondary outcomes

1. Post-insertion sensitivity or pain assessed by a validated

pain scale.

2. Secondary caries, as diagnosed clinically.

3. Marginal deterioration of the restoration and fracture of the

remaining tooth tissue.

4. Economic data: direct costs of materials and any reported

associated indirect costs.

5. Adverse effects: any event for which the causal relationshipbetween the event and the amalgam restoration is at least a

reasonable possibility.

Search methods for identification of studies

Electronic searches

For the identification of studies included or considered for this

review, detailed search strategies were developed for each database

to be searched. These were based on the search strategy developed

for MEDLINE (Appendix 1) but revised appropriately for eachdatabase.

For the MEDLINE search, we ran the subject search with the

Cochrane Highly Sensitive Search Strategy (CHSSS) for identify-

ing randomised trials in MEDLINE: sensitivity maximising ver-

sion(2008 revision)as referenced in Chapter 6.4.11.1 and detailed

in box 6.4.c of the Cochrane Handbook for Systematic Reviews of

Interventions5.0.1 (updated September 2008) (Higgins 2008).

We searched the following databases on 22nd July 2009:

the Cochrane Oral Health Groups Trials Register;

the Cochrane Central Register of Controlled Trials

(CENTRAL) (The Cochrane Library2009, Issue 3);

MEDLINE (1950 to 2009); and

EMBASE (1980 to 2009).

For the detailed search strategies applied to each of the databases

seeAppendix 2;Appendix 3andAppendix 4.

Searching other resources

We examined the reference lists of relevant articles and contacted

the investigators of the included study by electronic mail to ask

for details of additional published and unpublished trials. We did

not handsearch any journals.

Language

There was no language restriction on included studies and we

identified one potentially relevant study in the Chinese language

which was translated into English.

Data collection and analysis

Selection of studies

Two review authors (Zbys Fedorowicz (ZF) and Nairn Wilson

(NW)) independently assessed the abstracts of studies resulting

from the searches. We obtained full copies of all relevant and

potentially relevant studies, those appearing to meet the inclusion

criteria, and for which there were insufficient data in the title andabstract to make a clear decision. The full text papers were assessed

independently by the two review authors andany disagreement on

the eligibility of included studies was resolved through discussion

and consensus or if necessary through a third party (Mona Nasser

(MN)). We excluded all irrelevant records and noted details of the

studies and the reasons for their exclusion in the Characteristics

of excluded studiestable in RevMan 5 (RevMan 2008).

Data extraction and management

We entered study details into the Characteristics of included

studies table in RevMan 5 and collected outcome data using a pre-

determined form designed for this purpose.Data were extracted independently and in duplicate by two review

authors (ZF and MN) and only included if there was a consensus.

The following details were extracted.

1. Trial methods: (a) method of allocation; (b) masking of

participants, trialists and outcome assessors; (c) exclusion of

participants after randomisation and proportion and reasons for

losses at follow -up.

2. Participants: (a) country of origin and location: private

clinic or academic institute; (b) sample size; (c) age; (d) sex; (e)

inclusion and exclusion criteria; (f) location and type of cavity

(Class I or II); (g) cavity size.

3. Intervention: (a) type, amalgam alloy and bonding material

and method of cure; (b) length of time in follow-up; (c) failure

and reasons for failure if reported.

4. Control: (a) type of amalgam alloy; (b) length of time in

follow-up; (c) failure and reasons for failure if reported.

5. Outcomes: (a) primary and secondary outcomes mentioned

in theTypes of outcome measuressection of this review.

If stated, the sourcesof funding of any of the included studies were

recorded.



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The review authors used this information to help them assess het-

erogeneity and the external validity of any included trials.

Assessment of risk of bias in included studies

Each review author graded the selected trial using a simple contin-gency form and followed the domain-based evaluation described

in Chapter 8 of the Cochrane Handbook for Systematic Reviews of

Interventions5.0.1 (Higgins 2008). The evaluations were com-

pared and any inconsistencies between the review authors were

discussed and resolved.

The following domains were assessed as Yes (i.e. low risk of bias),

Unclear (i.e. uncertain risk of bias) or No (i.e. high risk of bias):

1. sequence generation;

2. allocation concealment;

3. blinding (of participants, personnel and outcome assessors);

4. incomplete outcome data;

5. selective outcome reporting;

6. free of other bias.Risk of bias in any included studies was categorised according to

the following:

Low risk of bias (plausible bias unlikely to seriously alter the

results) if all criteria were met;

Unclear risk of bias (plausible bias that raises some doubt

about the results) if one or more criteria were assessed as unclear;

or

High risk of bias (plausible bias that seriously weakens

confidence in the results) if one or more criteria were not met.

These assessments are reported in the Risk of bias in included

studiestable.

As one of the review authors (NW) was an investigator in the only

included study he did not participate in either the assessment ofrisk of bias or in data extraction.

Assessment of heterogeneity

A lack of included studies precluded any assessment of hetero-

geneity but if further trials are identified the following methods

will be used.

We will assess clinical heterogeneity by examining the characteris-

tics of the studies, the similarity between the types of participants,

the interventions and the outcomes as specified in the criteria for

included studies. Statistical heterogeneity will be assessed using a

Chi2 test and the I2 statistic where I2 values over 50% indicate

moderate to high heterogeneity. We will consider heterogeneity to

be significant when the P value is less than 0.10 ( Higgins 2003).

Assessment of reporting biases

If further trials are identified for inclusion in this review, publi-

cation bias will be assessed according to the recommendations on

testing for funnel plot asymmetry (Egger 1997) as described in

section 10.4.3.1 of theCochrane Handbook for Systematic Reviews

of Interventions5.0.1 (Higgins 2008), and if asymmetry is iden-

tified, we will try to assess other possible causes and these will be

explored in the discussion if appropriate.

Data synthesis

As only one study was included in this review, data synthesis was

not feasible but if further studies are identified for inclusion in this

review, the following methods will be used.

Two review authors (ZF and MN) will analyse the data and re-

port them as specified in Chapter 9 of theCochrane Handbook for

Systematic Reviews of Interventions5.0.1 (Higgins 2008). Analysis

will be conducted at the same level as the allocation.

Choice of summary statistic and estimate of overalleffect

We will transform longevity/survival data to dichotomous out-comes (failure/not). Risk ratios and their95% confidence intervals

will be calculated for all dichotomous data. The mean difference

and 95% confidence intervals will be calculated for continuous

data.

As it is likely that the timing of outcome assessment will vary

between studies we will consider grouping the data according to

the following time points: 1, 2, 5 and 10 years.

Pooling of data to provide estimates of the efficacy of the inter-

ventions would only be undertaken if the included studies have

similar interventions received by similar participants. In the event

of substantial clinical heterogeneity between the studies we intend

using the random-effects model with studies grouped by action.

Subgroup analyses

Subgroup analyses will be conducted for any of the following:

different bonding agents, the type of cavity (Class I or II) and

its location (premolar or molar tooth), only if there are sufficient

numbers of included trials with appropriate data.

Sensitivity analyses

If sufficient studies are included we plan to conduct sensitivity

analyses to assess the robustness of our review results by repeating

the analysis with the following adjustments: exclusion of studieswith unclear or inadequate allocation concealment, unclear or in-

adequate blinding of outcomes assessment and completeness of

follow-up.

R E S U L T S



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of (selection) bias for the outcomes of interest in addition to the

incompleteness of its data as a result of the large number of with-

drawals. We eliminated the Mach 2002 study from this review

because it included teeth with lesions other than Class II, as well

as the lack of clarity and consistency in the reporting of the inter-

ventions participants received as well as in the presentation of theoutcome data.SeeCharacteristics of excluded studiestable.

Risk of bias in included studies

We were successful in contacting another one of the study inves-

tigators by email who was able to clarify some missing trial details

which enabled a change in both the assessment of concealed ran-

domisation and blinded assessment of outcomes from unclear to

yes to be made for this study.

As all of the criteria used in the assessment of risk of bias were met,

this trial was assessed as low risk of bias (plausible bias unlikely to

seriously alter the results). Further details of these assessments areavailable in theRisk of bias in included studies table.

Effects of interventions

The single included trial provided a limited amount of data rele-

vant to some of the primary and secondary outcomes of this re-

view and therefore we have not entered these into the RevMan

analysis but present these data in the Additional tables section of

this review together with a descriptive summary. In addition, we

note that although the data analysis in this trial failed to take into

account the clustering of matched pairs of teeth it was considered

that this would have a limited impact on the overall results.

Primary outcomes

(1) Survival of the restoration: longevity/survival to defined

time points yearly up to a maximum of 10 years

Only three restorations (non-bonded) were reported as lost at 4,

7 and 24 months, and in all three the loss of proximal boxes was

attributed to a lack of retention (AdditionalTable 1). It was un-

clear how many, if any, of the five bonded restorations which were

unavailable at the 24-month recall could be classified as failures.Although this study had a large percentage follow-up at 24 months,

which permitted an assessment of 105/113 (93%) of the restora-

tions placed, the number of failures proved to be very small, and

therefore we did not conduct a survival analysis.

Secondary outcomes

(1) Post-insertion sensitivity or pain assessed by a validated

pain scale

Only the modified USPHS criteria were used to rate post-inser-

tion temperature sensitivity at both baseline and at the 24-month

assessment. Although the investigators indicated that there was no

significant difference in sensitivity between the two groups (P >0.05), this conclusion appeared to be based on the assessments

made solely at these two time points. However, because such or-

dinal ratings of severity are unlikely to be sufficiently sensitive in

providing a discriminative assessment of post-operative sensitivity

when compared with a validated VAS we have not reported these

data.

(2) Secondary caries, as diagnosed clinically

The report provided no data for this outcome.

(3) Marginal deterioration of the restoration and fracture of

the remaining tooth tissue

No fractures of remaining tooth tissue were reported in either of

the intervention groups. The marginal deterioration of restora-

tions was assessed at the occlusal and proximal surfaces, and the

investigators reported that there was no significant difference be-

tween the groups or the matched pairs of restorations intheir mar-

ginal adaptation (P > 0.05), and that these provided comparable

Alpha rating scores at both baseline and 24 months. SeeAdditional

Table 2.

Although not discussed by the investigators, the apparentimprove-

ment in Alpha scores (88% to 91%) in the proximal assessment

in the bonded group at 24 months may reflect the subsequent

replacement of the three failed non-bonded restorations with ad-hesively bonded restorations and is consistent with their survival

at the 24-month recall.

(4) Economic data: direct costs of materials and any

reported associated indirect costs

No data were reported.

(5) Adverse effects

The investigators did not report any adverse effects.

For further details of this trial seetheCharacteristics of included

studiestable.

D I S C U S S I O N

The paucity of high quality trials evaluating the effects of adhesive

bonding on the in-service performance and longevity of restora-

tions of dental amalgam proved to be somewhat disappointing



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more especially because of the availability and usage, by clinicians,

of a wide range of bonding agents that have been developed over

a number of years.

The single randomised controlled trial, albeit only of short du-

ration, which was included in this review would appear to con-

firm some of the findings of several other studies in that moder-ately sized adhesively bonded amalgam restorations have a similar

survival profile and clinical performance to non-bonded restora-

tions. However, whilst attempts were made in this study to ensure

that the preparations for bonded restorations had limited reten-

tive form compared to conventional preparations utilising delib-

erate retention, such that assessment could be made of the added

value of bonding, there can be no certainty that this is reflected

by the similarity of survival data in both treatment groups chiefly

because of the difficulties of eliminating all potential sources of

retention. Although these similarities may suggest that there is re-

liable evidence for the effectiveness of bonding agents they also

indicate that adhesive bonding of dental amalgam restorations has

neither beneficial nor detrimental effects on clinical performance,as assessed by modified USPHS over periods of up to 2 years after

placement, and therefore calls into question the additional cost of

materials and time expended on bonding.

Whilst recognising some of the complexities of assessing post-op-

erative sensitivity for these interventions, the apparent lack of tem-

perature sensitivity in the two groups may be potentially mislead-

ing. The absence of temperature sensitivity at the 24-month recall

could in any event be indicative of post-operative loss of vitality

and in particular if there was immediate post-insertion hypersen-

sitivity. This lack of detailed information about any immediate

post-insertion sensitivity or pain and in particular its duration and

intensity due to any stimulus as assessed with a VAS was a further,small but not insignificant, limitation of this study.

Even though the clinical trial that was included in this systematic

review satisfied our inclusion criteria, the generalisability of its

results are likelyto be compromised by several factors: theselection

of patients from a university dental hospital environment, which

could be considered unrepresentative of the population at large, as

well as the comparative freedom from some of the constraints, e.g.

time and cost of materials, which might apply in general dental

practice.

A U T H O R S C O N C L U S I O N S

Implications for practice

Thereis noevidence to eitherclaimor refutea difference insurvival

between bonded and non-bonded amalgam restorations. This re-

view only found one methodologically sound but somewhat un-

der-reported trial. This trial did not find any significant differ-

ence in the in-service performance of moderately sized adhesively

bonded amalgam restorations, in terms of their survival rate and

marginal integrity, in comparison to non bonded amalgam restora-

tions over a two year period. In view of the lack of evidence onthe additional benefit of adhesively bonding amalgam in compar-

ison with non bonded amalgam, it is important that clinicians are

mindful of the additional costs that may be incurred.

Implications for research

Following the realisation that dental amalgam may be adhesively

bonded to enamel and dentine, there was a need to investigate

the clinical performance of bonded amalgams, in particular, in

cavities in which no effort had been made to introduce retention

features. With subsequent developments in respect of, in particu-

lar, minimal interventive dentistry and enhanced durability and,

in turn, longevity of tooth-coloured alternatives to dental amal-

gam, the need for further investigations of the efficacy of adhe-sively bonded restorations of dental amalgam has diminished. In-

deed, further clinical investigations on adhesively bonded den-

tal amalgams would be difficult to justify. A further deterrent to

considerations to plan further clinical investigations of adhesively

bonded restorations of dental amalgam is the cost consideration

of the bonding process. Notwithstanding the not inconsiderable

cost of the adhesive materials, the adhesive bonding of restora-

tions of dental amalgams adds greatly to the placement time of

such restorations. Extended treatment times, let alone additional

cost, which add little, if anything to clinical outcomes cannot be

supported.

Given the available evidence and the diminishing use of den-tal amalgam internationally, there is conceivably limited justifica-

tion for further clinical investigations on the adhesive bonding of

restorations of dental amalgam.

A C K N O W L E D G E M E N T S

The review authors would like to thank the Cochrane Oral Health

Group and the peer reviewers and referees for their help in con-

ducting this systematic review. We would also like to thank Profes-

sor Jin Xuejuan of the Shanghai Institute of Cardiovascular Dis-

eases who very kindly obtained a full text copy of one of the trials,

to Dr Edwin Chan Shih-Yen the Director of the Singapore Branch

of the Australasian Cochrane Centre for carrying out the transla-

tion of this paper and Dr Bruce Manzer of The College of Health

Sciences at the Ministry of Health Bahrain for help with editing

earlier drafts of this review.



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R E F E R E N C E S

References to studies included in this review

Setcos 1999 {published data only}

Setcos JC, Staninec M, Wilson NH. A two-year

randomized, controlled clinical evaluation of bonded

amalgam restorations. Journal of Adhesive Dentistry1999;1

(4):32331.

References to studies excluded from this review

Browning 2000 {published data only}

Browning WD, Johnson WW, Gregory PN. Clinical

performance of bonded amalgam restorations at 42 months.

Journal of the American Dental Association2000;131(5):

60711.

Mach 2002 {published data only}

Mach Z, Regent J, Staninec M, Mrklas L, Setcos JC.

The integrity of bonded amalgam restorations: a clinical

evaluation after five years. Journal of the American DentalAssociation2002;133(4):4607.

Mahler 1996 {published data only}

Mahler DB, Engle JH, Simms LE, Terkla LG. One-year

clinical evaluation of bonded amalgam restorations. Journal

of the American Dental Association1996;127(3):3459.

McEvoy 1992 {published data only}

McEvoy SA, Richards ND, McConnell TA, Mitchell RJ.

Lesion size and retention of dentin-bonded restorations.

Journal of Dental Research. 1992; Vol. 71:139 (Abs No

266).

McEvoy 1993 {published data only}

McEvoy SA, Richards ND, McConnell TA, Mitchell RJ.

Age, lesion size and retention of dentin-bonded restorations.Journal of Dental Research. 1993; Vol. 72:380 (Abs No

2216).

Xia 2002 {published data only}

Xia SL, Liu JB, Li TL. Clinical study of amalgam restoration

with resin multi-purpose adhesive agent. Bulletin of Hunan

Medical University2002;27(3):238.

Additional references

Ben-Amar 1995

Ben-Amar A, Cardash HS, Judes H. The sealing of the

tooth/amalgam interface by corrosion products. Journal of

Oral Rehabilitation1995;22(2):1014.

Berry 1998Berry TG, Summitt JB, Chung AK, Osborne JW. Amalgam

at the new millennium. Journal of the American Dental

Association1998;129(11):154756.

Burke 2001

Burke FJ, Wilson NH, Cheung SW, Mjor IA. Influence of

patient factors on age of restorations at failure and reasons

for their placement and replacement. Journal of Dentistry

2001;29(5):31724.

Chadwick 2001

Chadwick BL, Dummer PMH, Dunstan F, Gilmour A,

Jones R, et al.A systematic review of the longevity of dental

restorations. NHS Centre for Reviews and Dissemination,

University of York 2001; Vol. Report number 19.

Downer 1999

Downer MC, Azli NA, Bedi R, Moles DR, Setchell DJ.

How long do routine dental restorations last? A systematic

review. British Dental Journal1999;187(8):4329.

Egger 1997

Egger M, Davey-Smith G, Schneider M, Minder C. Bias

in meta-analysis detected by a simple, graphical test. BMJ

1997;315:62934.

Hickel 2007

Hickel R, Roulet JF, Bayne S, Heintze SD, Mjor IA, Peters

M, et al.Recommendations for conducting controlled

clinical studies of dental restorative materials. Clinical Oral

Investigations2007;11(1):533.Higgins 2003

Higgins JP, Thompson SG, Deeks JJ, Altman DG.

Measuring inconsistency in meta-analyses. BMJ2003;327

(7414):55760.

Higgins 2008

Higgins JPT, Green S (editors). Cochrane Handbook for

Systematic Reviews of Interventions Version 5.0.1 [updated

September 2008] The Cochrane Collaboration, 2008.

Available from www.cochrane-handbook.org.

Mackert 2004

Mackert JR, Wahl MJ. Are there acceptable alternatives to

amalgam?.Journal of the California Dental Association2004;

32(7):60110.RevMan 2008

The Nordic Cochrane Centre, The Cochrane Collaboration.

Review Manager (RevMan). 5.0. Copenhagen: The Nordic

Cochrane Centre, The Cochrane Collaboration, 2008.

Ryge 1981

Ryge G. Clinical criteria. International Dental Journal1981;

30(4):34758.

SCENIHR 2007

Scientific Committee on Emerging and Newly Identified

Health Risks (SCENIHR). The safety of dental amalgam

and alternative dental restoration materials for patients and

users. Available at: http://ec.europa.eu/health/ph_risk/

committees/04_scenihr/scenihr_cons_07_en.htm [Accessed

28 March 2008].Setcos 2000

Setcos JC, Staninec M, Wilson NH. Bonding of amalgam

restorations: existing knowledge and future prospects.

Operative Dentistry2000;25(2):1219.

Turner 1995

Turner EW, St Germain HA, Meiers JC. Microleakage

of dentin-amalgam bonding agents. American Journal of

Dentistry1995;8(4):1916.



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C H A R A C T E R I S T I C S O F S T U D I E S

Characteristics of included studies [ordered by study ID]

Setcos 1999

Methods 2-year randomised controlled trial, no details of the setting or date of the trial were

reported

Participants 31 (21 males, 10 females, no age specified).

Inclusion criteria: no contraindication to routine dental treatment, routine radiographs

taken, attempts made to find contralateral pairs of teeth

Class II restorations [mo, do or mod] in vital posterior teeth

Interventions N = 113 restorations. Size, location and number per participant were unreported but 35

matched pairs were compared and analysed

No deliberate provision of undercuts or retention in any preparationsGroup 1: 60 adhesively bonded amalgam restorations. Dycal (LD Caulk) liner; ED

primer (Kuraray); Panavia 21TC (Kuraray); Oxyguard II gel (Kuraray); Dispersalloy

amalgam (Dentsply)

Group 2: 53 non-bonded amalgam restorations. Dycal (LD Caulk) liner; Dispersalloy

amalgam (Dentsply)

Outcomes Clinical assessments: baseline (< 1 month post-intervention) and at 2 years, util ising

modified USPHS criteria. Failure not clearly defined, appears to refer to total or partial

loss of the box part of the restoration

Assessment of post-interventionsensitivity at baseline and at 2 years using USPHS criteria

Notes The study was supported by Kuraray Co Ltd, Japan, the manufacturer of the adhesive

materials used in this study

Risk of bias

Item Authors judgement Description

Adequate sequence generation? Yes Quote (from report): By random assign-

ment.., and At this stage, the operators

were shown the random selection for the

method of filling

Comment: Unclear how and by whom the

random sequence was generated

Quote (from correspondence): This was

done by a specially prepared random allo-

cation of adhesive/non-adhesivetreatments

which was followed through sequentially

Comment: Probably done.

Allocation concealment? Yes Comment: Nothing reported.

Quote (from correspondence): The ran-

dom allocation was prepared by the statis-



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Setcos 1999 (Continued)

tical support unit at Manchester University

Dental Hospital

Comment: Central allocation by a third

party.

Blinding?

All outcomes

Yes Participants: No information available, but

most likely blinded to the interventions

Healthcare providers: Impossible to blind

operators to the interventions

Outcome assessors and data analysts:

Quote (from report): Clinical evalua-

tion by two dentists, experienced in rat-

ing restorations, was performed at baseline

(within one month of placement), and at

two years following placement

Quote (after correspondence): the personwho placed the restorations not being in-

volved in the recall assessments

Comment: Probably done.

Patient reported outcomes: Only post-op-

erative sensitivity, and most probable if par-

ticipants blinded to interventions

Incomplete outcome data addressed?

All outcomes

Yes Losses to follow-up at 2-year assessment

were accounted for.

Adhesively bonded: 5/60 (0.08%); partic-

ipants not available for assessment and un-

clear whether these restorations had failed.

Non-bonded: 3/53 (0.06%); losses at 4months, 7 months and 24 months.

Missing data proportionately balanced

across intervention groups

Free of selective reporting? Yes Although the study protocol was not avail-

able, the report appears to include all pre-

specified and expected outcomes

Free of other bias? Yes The study was supported by the manu-

facturer of a relevant dentalproduct butap-

pears to be free of other sources of bias



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(Continued)

6. ((dental or tooth or teeth or fill$ or restor$) and amalgam$).ti,ab

7. or/5-6

8. (adhesiv$ or bonded or non-bonded or bonding or non-bonding).ti,ab

9. DENTAL BONDING/

10. or/8-9

11. 4 and 7 and 10

Cochrane search filter for MEDLINE via OVID:

Cochrane Highly Sensitive Search Strategy (CHSSS) for identifying randomised trials in MEDLINE: sensitivity maximising version

(2008 revision) as referenced in Chapter 6.4.11.1 and detailed in box 6.4.c of the Cochrane Handbook for Systematic Reviews of

InterventionsVersion 5.0.1(updated September 2008):1. randomized controlled trial.pt.

2. controlled clinical trial.pt.

3. randomized.ab.

4. placebo.ab.

5. drug therapy.fs.

6. randomly.ab.

7. trial.ab.

8. groups.ab.

9. or/1-8

10. animals.sh. not (humans.sh. and animals.sh.)

11. 9 not 10

Appendix 2. Cochrane Oral Health Groups Trials Register search strategy

((caries or carious or decay or lesion or demineral* or remineral*) AND (amalgam* or fill* or restor*) AND (dental bonding or

adhesiv* or bonding or non-bonding or bonded or non-bonded))

Appendix 3. CENTRAL search strategy

#1 MeSH descriptor DENTAL RESTORATION, PERMANENT this term only

#2 MeSH descriptor DENTAL RESTORATION, TEMPORARY this term only

#3 ((tooth in Title, Abstract or Keywords or teeth in Title, Abstract or Keywords or dental* in Title, Abstract or Keywords

or molar* in Title, Abstract or Keywords or biscupid* in Title, Abstract or Keywords or third-molar* in Title, Abstract or

Keywords) and (restor* in Title, Abstract or Keywords or fill* in Title, Abstract or Keywords))

#4 (#1 in Title, Abstract or Keywords or #2 in Title, Abstract or Keywords or #3 in Title, Abstract or Keywords)



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(Continued)

#5 MeSH descriptor DENTAL AMALGAM this term only

#6 ((dental in Title, Abstract or Keywords or tooth in Title, Abstract or Keywords or teeth in Title, Abstract or Keywords or fill*in Title, Abstract or Keywords or restor* in Title, Abstract or Keywords) and amalgam* in Title, Abstract or Keywords)

#7 (#5 in Title, Abstract or Keywords or #6 in Title, Abstract or Keywords)

#8 (adhesiv* in Title, Abstractor Keywords or bondedin Title,Abstract or Keywords or non-bonded in Title, Abstract or Keywords

or bonding in Title, Abstract or Keywords or non-bonding in Title, Abstract or Keywords)

#9 MeSH descriptor DENTAL BONDING this term only

#10 (#8 in Title, Abstract or Keywords or #9 in Title, Abstract or Keywords)

#11 (#4 in Title, Abstract or Keywords and #7 in Title, Abstract or Keywords and #10 in Title, Abstract or Keywords)

Appendix 4. EMBASE (OVID) search strategy

1. DENTAL RESTORATION, PERMANENT/

2. DENTAL RESTORATION, TEMPORARY/

3. ((tooth or teeth or dental$ or molar$ or bicuspid$ or third-molar$) and (restor$ or fill$)).ti,ab

4. or/1-3

5. DENTAL AMALGAM/

6. ((dental or tooth or teeth or fill$ or restor$) and amalgam$).ti,ab

7. or/5-6

8. (adhesiv$ or bonded or non-bonded or bonding or non-bonding).ti,ab

9. DENTAL BONDING/

10. or/8-9

11. 4 and 7 and 10

Filter for EMBASE via OVID:

1. random$.ti,ab.

2. factorial$.ti,ab.

3. (crossover$ or cross over$ or cross-over$).ti,ab.

4. placebo$.ti,ab.



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5. (doubl$ adj blind$).ti,ab.

6. (singl$ adj blind$).ti,ab.

7. assign$.ti,ab.

8. allocat$.ti,ab.

9. volunteer$.ti,ab.

10. CROSSOVER PROCEDURE.sh.11. DOUBLE-BLIND PROCEDURE.sh.

12. RANDOMIZED CONTROLLED TRIAL.sh.

13. SINGLE BLIND PROCEDURE.sh.

14. or/1-13

15. ANIMAL/ or NONHUMAN/ or ANIMAL EXPERIMENT/

16. HUMAN/

17. 16 and 15

18. 15 not 17

19. 14 not 18

H I S T O R Y

Protocol first published: Issue 1, 2009

Review first published: Issue 4, 2009

C O N T R I B U T I O N S O F A U T H O R S

Zbys Fedorowicz (ZF), Nairn Wilson (NW), and Mona Nasser (MN) were responsible for: organising the retrieval of papers; writing

to authors of papers for additional information; screening search results; screening retrieved papers against inclusion criteria; appraising

the quality of papers; data collection for the review; extracting data from papers; obtaining and screening data on unpublished studies.

ZF and MN entered the data into RevMan and were responsible for analysis and interpretation of the data.

All review authors contributed to writing the review.

All review authors were responsible for designing and co-ordinating the review and for data management for the review.

NW and ZF conceived the idea for the review and are the guarantors for the review.

D E C L A R A T I O N S O F I N T E R E S T

There are no financial conflicts of interest and the review authors declare that, other than Nairn Wilson who is an investigator in

potentially eligible studies, they do not have any associations with any parties who may have vested interests in the results of this review.

I N D E X T E R M S



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Medical Subject Headings (MeSH)

Dental Restoration Failure; Dental Amalgam [therapeutic use]; Dental Bonding [methods]; Dental Caries [therapy]; Dental

Restoration, Permanent [methods]

MeSH check words

Adult; Humans



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