Abstract
Objective
To quantitatively determine whether the pulp response to resin-modified glass ionomer cements placed in deep cavities differs from that generated by calcium hydroxide cement.
Sources
Five databases were searched for articles up to 31 May 2009.
Study selection
Inclusion criteria: titles/abstracts relevant to topic; published in English; two-arm longitudinal in vivo trial; containing computable dichotomous datasets for test and control group. Exclusion criteria: not all entered subjects accounted for at the end of the trial; subjects of both groups not followed up in the same way; trial on animal tissue.
Data
One randomized and five non-randomized control trials, reporting on 1 and 17 datasets, respectively, were accepted. From non-randomized trials, the Relative Risk with 95% Confidence Interval of 13 datasets showed no statistically significant differences ( p > 0.05) and 4 showed a statistically significant difference between both materials. Meta-analysis of datasets from these trials found no difference between the inflammatory cell response after 30 days (0.87; 95%CI 0.59–1.26; p = 0.46); 38% less inflammatory cell response with calcium hydroxide after 60 days (0.62; 95%CI 0.50–0.76; p < 0.00001); higher number of intact odontoblasts beneath restored cavities after 381 days (0.56; 95%CI 0.38–0.82; p = 0.0008). The results from the randomized control trial (1.40; 95%CI 0.92–2.14; p = 0.11) indicated no difference in clinically identifiable pulp symptoms after two years. All trials showed limited internal validity due to selection bias.
Conclusion
No conclusive statement about the superiority of either type of material can yet be made. Further high-quality randomized control trials are needed.
1
Introduction
Management of deep carious lesions and the associated histopathological pulpal changes is important for caries management in operative dentistry. The pulp requires protection from further bacterial invasion from the carious process, thermal/electrical conduction (depending on the conductivity of the restorative material placed upon it) and chemical protection from the overlying restorative materials. An important function of a therapeutic lining material is to stimulate the pulp odontoblasts to lay down reparative dentin and promote remineralization of existing dentin; thus encouraging the dentin–pulp complex and eventually, the carious lesion, to heal . For many years, the material of choice beneath an amalgam restoration has been calcium hydroxide cement, placed as a thin layer on the cavity surface closest to the pulp. Much research has been carried out investigating its value in the above roles , indicating its relative merits along with its simplicity of use. However, concerns exist regarding the long-term solubility of calcium hydroxide cements, their lack of chemical or mechanical adhesiveness, and their potential accelerated degradation after being acid-etched during the adhesive bonding process, thus leading to a reduced area on the cavity surface for material adhesion . With the development of the principles of minimally invasive dentistry, the rationale of potentially leaving caries-affected dentin within the depths of a cavity and then sealing the lesion with an adhesive restorative material has been suggested . As the intrinsic qualities of restorative materials have improved over the last decade, there is now a serious need to establish whether a separate “lining” stage is needed in the restorative process, as adhesive materials such as conventional glass ionomer cements (GIC) have been suggested to have biomimetic properties . In contrast, resin-modified glass ionomer cements (RM-GIC) have been reported to be more harmful to the pulp . This has been explained on basis of the HEMA (hydroxyethylmethacrylate) content in RM-GIC, which may diffuse through dentin and cause inflammation of the pulp . So far, the volume of scientific articles on the topic of RM-GIC-related biocompatibility and pulp response has been discussed, via a number of narrative reviews with conflicting findings . However, no systematic review has been attempted.
Therefore, this systematic review sought to quantitatively answer the question as to whether resin-modified glass ionomer cements (RM-GIC) placed in deep cavities generate a pulp response different from that of calcium hydroxide cement as comparison.
2
Materials and methods
2.1
Data collection
Five databases: Biomed Central, Cochrane Library, Directory of Open Access Journals, PubMed and Science-Direct were systematically searched for articles reporting on clinical trials up to 31 May 2009. The string of MeSH/text search terms, with boolean operators: “ Dental Pulp” OR “Dental Pulp Necrosis” OR “Dental Pulp Devitalizatio” AND “Glass Ionomer Cements AND “Calcium Hydroxide” , was used to search all databases. From the search results, articles were selected for review on the basis of their compliance with the following inclusion criteria:
- 1.
Titles/abstracts relevant to topic.
- 2.
Published in English.
- 3.
Two-arm (progressive) longitudinal clinical trial (randomized control trial, non-randomized clinical control trial).
- 4.
Containing computable dichotomous data for both test and control group.
Where a relevant title without a listed abstract was available, a full copy of the article was assessed for inclusion. References of accepted articles were checked for additional studies suitable for inclusion.
2.2
Article review
Only articles that complied with the inclusion criteria were reviewed further. Full copies of articles were reviewed independently by two reviewers (VY and SM), to determine whether the exclusion criteria applied :
- 1.
Not all entered subjects accounted for at the end of the trial.
- 2.
Subjects of both groups not followed up the same way.
- 3.
Trial conducted on animal tissue.
Where several articles had reported on the same trial over similar time periods, the article covering the trial most comprehensively in accordance with the exclusion criteria was accepted. Disagreements between reviewers were resolved by discussion and consensus.
2.3
Data extraction from accepted trials
Outcome measures related to pulp tissue response to cavity restorations with either material were assessed. Two reviewers (VY and SM) independently extracted data from the accepted articles. Individual dichotomous datasets for the control and test group were extracted from each article. Where possible, missing data were calculated from information given in the text or tables. In addition, authors of articles were contacted in order to obtain missing information. Disagreements between reviewers during data extraction were resolved through discussion and consensus.
2.4
Quality of studies
The quality assessment of the accepted trials followed Cochrane guidelines and was undertaken independently by two reviewers (VY and SM). Trials not included in this review were used to pilot the process. Subsequently quality assessment rating scored by both reviewers was derived by consensus. The following criteria were used in the scoring of randomized control trials (RCTs) and non-randomized clinical control trials:
Randomized control trials (RCTs):
- (1)
Generation of randomization sequence (allocation), recorded as:
- (A)
Adequate – e.g. computer-generated random numbers, table of random numbers.
- (B)
Unclear – not reported.
- (C)
Inadequate – e.g. case record number, date of birth, date of administration, alternation.
- (A)
- (2)
Allocation concealment, recorded as:
- (A)
Adequate – e.g. central randomization, sequentially numbered sealed opaque envelopes.
- (B)
Unclear – not reported.
- (C)
Inadequate – e.g. open allocation schedule, unsealed or non-opaque envelopes.
- (A)
- (3)
Blind outcome assessment, recorded as:
- (A)
Adequate – yes.
- (B)
Unclear – no information given whether assessment was blinded.
- (C)
Inadequate – reported in text that assessment was not blinded.
- (D)
Not possible.
- (A)
Non-randomized clinical control trials:
- (1)
Test and control groups matching:
- (A)
Adequate – clear statement in text that both groups were matched.
- (B)
Unclear – no statement in text that both groups were matched.
- (C)
Inadequate – baseline data differ significantly between groups ( p < 0.05).
- (A)
- (2)
Accounting of confounders and/or statistical adjustment:
- (A)
Adequate – confounders are accounted for and have either no significant impact or are statistically adjusted, e.g. using analysis of co-variances (ANCOVA).
- (B)
Unclear – no information about confounders reported.
- (C)
Inadequate – confounders with significant impact are accounted for but have not been statistically adjusted.
- (A)
- (3)
Blind outcome assessment, recorded as:
- (A)
Adequate – yes.
- (B)
Unclear – no information given as to whether assessment was blinded.
- (C)
Inadequate – reported in text that assessment was not blinded.
- (D)
Not possible.
- (A)
Clinical control trials lacking randomization were considered to have lower internal validity and evidence strength than RCTs .
2.5
Statistical analysis
A random effects model in RevMan Version 4.2 statistical software, developed by The Nordic Cochrane Centre, The Cochrane Collaboration (Copenhagen; 2003), was used. Differences in treatment groups were computed on the basis of Relative Risk (RR) with 95% Confidence Intervals (CI). Datasets extracted from the accepted articles were assessed for their clinical and methodological heterogeneity, following Cochrane guidelines . Datasets were considered to be heterogeneous if they differed regarding: study type, outcome measure aspect and definition, the pulp proximity, cavity floor size, exposure duration, dentition type, cavity type and location, caries presence or absence and type of pulp assessment method. The percentage of total variations across datasets ( I 2 ) was used in assessing statistical heterogeneity . Only identified homogeneous datasets were pooled for meta-analysis. Pooled datasets were assigned a Mantel–Haenszel weight directly proportionate to their sample sizes.
2
Materials and methods
2.1
Data collection
Five databases: Biomed Central, Cochrane Library, Directory of Open Access Journals, PubMed and Science-Direct were systematically searched for articles reporting on clinical trials up to 31 May 2009. The string of MeSH/text search terms, with boolean operators: “ Dental Pulp” OR “Dental Pulp Necrosis” OR “Dental Pulp Devitalizatio” AND “Glass Ionomer Cements AND “Calcium Hydroxide” , was used to search all databases. From the search results, articles were selected for review on the basis of their compliance with the following inclusion criteria:
- 1.
Titles/abstracts relevant to topic.
- 2.
Published in English.
- 3.
Two-arm (progressive) longitudinal clinical trial (randomized control trial, non-randomized clinical control trial).
- 4.
Containing computable dichotomous data for both test and control group.
Where a relevant title without a listed abstract was available, a full copy of the article was assessed for inclusion. References of accepted articles were checked for additional studies suitable for inclusion.
2.2
Article review
Only articles that complied with the inclusion criteria were reviewed further. Full copies of articles were reviewed independently by two reviewers (VY and SM), to determine whether the exclusion criteria applied :
- 1.
Not all entered subjects accounted for at the end of the trial.
- 2.
Subjects of both groups not followed up the same way.
- 3.
Trial conducted on animal tissue.
Where several articles had reported on the same trial over similar time periods, the article covering the trial most comprehensively in accordance with the exclusion criteria was accepted. Disagreements between reviewers were resolved by discussion and consensus.
2.3
Data extraction from accepted trials
Outcome measures related to pulp tissue response to cavity restorations with either material were assessed. Two reviewers (VY and SM) independently extracted data from the accepted articles. Individual dichotomous datasets for the control and test group were extracted from each article. Where possible, missing data were calculated from information given in the text or tables. In addition, authors of articles were contacted in order to obtain missing information. Disagreements between reviewers during data extraction were resolved through discussion and consensus.
2.4
Quality of studies
The quality assessment of the accepted trials followed Cochrane guidelines and was undertaken independently by two reviewers (VY and SM). Trials not included in this review were used to pilot the process. Subsequently quality assessment rating scored by both reviewers was derived by consensus. The following criteria were used in the scoring of randomized control trials (RCTs) and non-randomized clinical control trials:
Randomized control trials (RCTs):
- (1)
Generation of randomization sequence (allocation), recorded as:
- (A)
Adequate – e.g. computer-generated random numbers, table of random numbers.
- (B)
Unclear – not reported.
- (C)
Inadequate – e.g. case record number, date of birth, date of administration, alternation.
- (A)
- (2)
Allocation concealment, recorded as:
- (A)
Adequate – e.g. central randomization, sequentially numbered sealed opaque envelopes.
- (B)
Unclear – not reported.
- (C)
Inadequate – e.g. open allocation schedule, unsealed or non-opaque envelopes.
- (A)
- (3)
Blind outcome assessment, recorded as:
- (A)
Adequate – yes.
- (B)
Unclear – no information given whether assessment was blinded.
- (C)
Inadequate – reported in text that assessment was not blinded.
- (D)
Not possible.
- (A)
Non-randomized clinical control trials:
- (1)
Test and control groups matching:
- (A)
Adequate – clear statement in text that both groups were matched.
- (B)
Unclear – no statement in text that both groups were matched.
- (C)
Inadequate – baseline data differ significantly between groups ( p < 0.05).
- (A)
- (2)
Accounting of confounders and/or statistical adjustment:
- (A)
Adequate – confounders are accounted for and have either no significant impact or are statistically adjusted, e.g. using analysis of co-variances (ANCOVA).
- (B)
Unclear – no information about confounders reported.
- (C)
Inadequate – confounders with significant impact are accounted for but have not been statistically adjusted.
- (A)
- (3)
Blind outcome assessment, recorded as:
- (A)
Adequate – yes.
- (B)
Unclear – no information given as to whether assessment was blinded.
- (C)
Inadequate – reported in text that assessment was not blinded.
- (D)
Not possible.
- (A)
Clinical control trials lacking randomization were considered to have lower internal validity and evidence strength than RCTs .
2.5
Statistical analysis
A random effects model in RevMan Version 4.2 statistical software, developed by The Nordic Cochrane Centre, The Cochrane Collaboration (Copenhagen; 2003), was used. Differences in treatment groups were computed on the basis of Relative Risk (RR) with 95% Confidence Intervals (CI). Datasets extracted from the accepted articles were assessed for their clinical and methodological heterogeneity, following Cochrane guidelines . Datasets were considered to be heterogeneous if they differed regarding: study type, outcome measure aspect and definition, the pulp proximity, cavity floor size, exposure duration, dentition type, cavity type and location, caries presence or absence and type of pulp assessment method. The percentage of total variations across datasets ( I 2 ) was used in assessing statistical heterogeneity . Only identified homogeneous datasets were pooled for meta-analysis. Pooled datasets were assigned a Mantel–Haenszel weight directly proportionate to their sample sizes.
3
Results
An initial search of PubMed resulted in 31 articles, 11 of which complied with the inclusion criteria and were selected for review. During the subsequent search of the four other databases, no further articles were identified as suitable for selection. From the 11 selected articles, 5 were excluded, as these covered animal trials . One randomized control trial and five non-randomized clinical control trials were accepted for data extraction . Assessment of histomorphometric outcome measures in the non-randomized clinical control trials was possible, as this included extraction of the studied teeth for orthodontic reasons. Table 1 provides information about the quality aspects assessed for the accepted RCT and for the clinical control trials. Owing to the visible material characteristics of the compared materials, (resin-modified glass ionomer and calcium hydroxide), blinding of outcome assessment was rated “D” (not possible) in all trials. For the RCT , random allocation of subjects and concealment of random allocation were rated “B” (unclear), since no information about both was given in the text. Group matching and confounder assessment were rated as “B” (unclear) in all clinical control trials , owing to lack of information in the text.
| Article | Selection bias | Detection bias | |
|---|---|---|---|
| Random allocation | Allocation concealment | Evaluator blinding | |
| Randomized control trial | |||
| Marchi et al. | B | B | D |
| Article | Selection bias | Performance bias | Detection bias |
|---|---|---|---|
| Groups are matched | Confounders accounted for | Evaluator blinding | |
| Non-randomized control trial | |||
| Costa et al. | B | B | D |
| Murray et al. | B | B | D |
| Mousavinasab et al. | B | B | D |
| About et al. | B | B | D |
| Murray et al. | B | B | D |
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