To carry out the present bibliographic review, taking into account the non-clinical nature of the studies, the following research PICO question was applied: In teeth or samples, silicate-based cements have better properties of discoloration, sealing, radiodensity and solubility compared to conventional cements based on epoxy resin? (Figure). The bibliographic search was carried out in the databases of Medline via PubMed and the Wiley Online Library via Cochrane Library. The search was performed by combining MeSH (Medical Subject Headings) terms with free terms, in a simple or multiple way and using Boolean operators. In vitro studies published between 2015 and 2021 were included. The last search was conducted on January 31, 2021. Studies evaluating cements that were not marketed or modified in the composition of marketed cements were excluded. Also excluded were those studies that compared obturation modifications of physical or technical properties. The search equations used in English are described in Table 1. In addition, a manual electronic search was conducted in the Journal of Endodontics, International Journal of Endodontics, Australian Endodontic Journal and Iranian Endodontic Journal.
A preliminary selection of the articles was made by the title and the summary. Duplicate articles were discarded. Then, the full text of the articles was obtained, excluding the articles that did not meet the established criteria. Manually selected articles were added and those that did not meet the criteria were excluded. The selected articles were grouped according to the analysed property. Those articles that analysed more than one property were identified and included in the corresponding groups. Taking into account the nature of the review, the characteristics of the studies were summarized in a descriptive way.

The flow chart that was used for the selection of the articles can be seen in the Figure. A total of 224 studies were identified in the initial search. No duplicate articles were found. After evaluating the titles and summaries of the studies obtained in the initial search, 204 studies were excluded because they did not meet the inclusion and exclusion criteria. Therefore, 20 studies were selected to read the full text, to which four more studies were added that were obtained by an electronic manual search. After reviewing the full text of the 24 studies, two were excluded because they did not include a comparative group of epoxy resin23,24.
Therefore, the final number of articles included in the bibliographic review to carry out the data extraction was of 22. The studies were grouped according to the analysed property (Table 2): 2 discoloration (A); 4 sealing capacity (B); 11 radiodensity (C); 9 setting time (D); and 12 solubility (E). 9 articles analysed several properties.

The selected articles evaluated different physical properties of the new silicate-based sealing cements.
In order to evaluate the properties of the different cements, it is essential to establish standardized methodologies, so that the results can be reproduced and perform a reliable comparison of the data¹⁹.
Discoloration of dental tissue Studies that analysed the discoloration evaluated the same resin-based cement, the AH PlusTM7,¹⁴ sealant cement. However, different silicate-based cements were evaluated, being EndosealTM¹⁴, MTA FillapexTM and iRootTM SP⁷ the evaluated cements. Between both studies the discoloration of a total of 100 teeth was evaluated, including both bovine teeth¹⁴ and human teeth⁷. The technique used in the discoloration evaluation was spectrophotometry for both studies, using the CIELAB system. However, different evaluation periods were applied, 0-2 months14 and 0-6 months⁷.
The results obtained in the two selected studies did not find significant differences regarding discoloration between the analysed cements and the resin-based AH PlusTM. However, Forghani et al.,⁷ observed a progressive discoloration of all cements during the first three months after the cement application, with a tendency to decrease during the second quarter and up to the sixth month of the evaluation.

Sealing capability
The studies that evaluated the sealing of the new silicatebased sealants were^45,15,25,26. Regarding the selected silicate cements, one study evaluated BioRootTM RCS⁵, two studies analysed EndoSequenceTM BC Sealer^15,25 cement and one study iRootTM SP²⁶ cement. All studies were based on the AH PlusTM resin cement.
In three of the selected studies^5,15,26 there were no differences in sealing capacity between silicate-based cement and epoxy resin-based cement. On the other hand, in one of the studies²⁶, a better seal was obtained with EndosequenceTM BC Sealer silicate cement than with epoxy resin cement. Radiodensity
Eleven studies^{9,16,17,19,20,27-32} were selected that evaluated the radiodensity of silicate-based cements, comparing them with epoxy resin-based cements. The silicate-based cements analysed in the studies were: EndoSequenceTM BC Sealer¹⁶, EndoSealTM MTA^16,28, TotalFillTM BC Sealer^9,30, BioRootTM RCS^20,29,31, MTA FillapexTM^16,20,31,32, Sealer PlusTM BC^17,19,27 and BioCTM Sealer⁹. All studies evaluated cement based on epoxy resin AH PlusTM. In addition, two studies also included epoxy resin-based cements ADSEALTM, Radic-SealerTM¹⁶ and Sealer PlusTM³².
The American National Standards Institute and the American Dental Association (ADA) in their specification number 57 of the year 2000 establish a minimum radiodensity equivalent to 3.00 mm AI³³. The standard established by the International Organization for Standardization (ISO) 6878 also specifies that the radiodensity must be equal to or greater than 3 mm AI³¹. All the cements evaluated presented radiodensity values within the recommended ISO standards.
In most studies AH PlusTM cement presented higher radiodensity values than BioRootTM RCS^29,31, TotalFillTM BC^9,30, Bio-CTM Sealer⁹, EndosequenceTM BC Sealer¹⁶, Sealer PlusTM BC^17,19,27, MTA FillapexTM^9,30,32 and EndosealTM²⁸. How ever, in other studies, there were no significant differences between AH PlusTM and
BioRootTM RC, MTA FillapexTM²⁰ and EndoSealTM MTA¹⁶ cements. In studies that also analysed other resinbased cements, radiodensity results with respect to silica-based cements were similar. The MTA FillapexTM cement showed lower radiodensity than the resin cements Sealer PlusTM⁹, Pulp Canal SealerTM31, RadicSealerTM and AD SealTM¹⁶.
Similarly, BioRootTM RCS cement showed a lower radiodensity compared to the Pulp Canal SealerTM³¹ resin cement. On the other hand, the EndosequenceTM BC Sealer cement also presented a lower radiodensity compared to Radic SealerTM cement. However, the EndosequenceTM BC Sealer cement presented a higher radiodensity than the AD SEALTM¹⁶ resin cement.
When evaluating the radiodensity differences between silicate-based cements, the results differ between the studies and depending on the analysed cements.
One study observed greater radiodensity with MTA FillapexTM compared to BioRootTM RCS³¹. However, in another study, no differences were obtained between the two cements²⁰, nor between the cements BioCTM Sealer and TotalFillTM BC Sealer⁹. The only study that analysed three silicate-based cements¹⁶ showed different radiodensity values between cements, with EndoSealTM MTA cement being the largest, followed by EndosequenceTM BC Sealer and MTA FillapexTM. The differences in radiodensity could be caused by the presence of different radiopacifying agents in the composition of the cements¹⁶.
Setting time
The 9 selected studies^{9,17-20,27,29,30,32} evaluated the setting time through needles that were introduced in the cement models, as established in IS0 687619 ANSI/ ADA 5727 standard.
The following silicate-based cements were evaluated: BioRootTM RCS^20,29; Sealer PlusTM^17,18,27; TotalFillTM BC Sealer, Bio-CTM Sealer^9,18,30; and MTA FillapexTM^20,32. In all studies, the setting time results of silicate-based cements were compared with AH PlusTM epoxy resin cement. One study also analysed Sealer PlusTM³² cement.
Two studies analysed the setting time of the BioRootTM RCS^20,29 cement. Both observed that BioRootTM RCS had a setting time lower than that of the resin-based cement AH PlusTM^20,29. In one of the two studies²⁰, they also evaluated the setting time of the MTA FillapexTM cement, which was completed in one week, the evaluation period established in the study. In another study, MTA FillapexTM had a higher setting time than AH PlusTM and PlusTM³² Sealer cements.

Three studies evaluated Sealer PlusTM BC17,19,27 silicate cement. Similar to the results observed with BioRootTM RCS cement, Sealer PlusTM BC also presented a lower setting time than AH PlusTM17,19,27 epoxy resin cement. In two studies18,30 TotalFillTM BC Sealer cement was analysed. In both, the setting time of silicate-based cement was lower than that of AH PlusTM. However, the two studies that analyse Bio-CTM Sealer cement presented differences in the results from each other.
In one study AH PlusTM cement had a shorter working time compared to Bio-CTM Sealer9, while in the other study¹⁸, epoxy resin-based cement AH PlusTM had a longer setting time lower than Bio-CTM Sealer.
When analysing the setting time of silicate cements, in one study²⁰ there were no differences observed between BioRootTM RCS and MTA FillapexTM cements, while two studies observed a shorter setting time of Bio-CTM Sealer cement compared to TotalFillTM BC Sealer^9,18. This cement in one of the 18 studies did not set after the 25 days established in the study conditions.
Solubility
Twelve articles evaluated the solubility of the sealants cements by comparing it with the solubility of the epoxy resin cements^{5,9,17,19,20,27,28,30,34-37}.
The selected studies analysed silicate-based cements: BioRootTM RCS^20,34,37; MTA FillapexTM^20,32,34-37; TotalFillTM BC Sealer^9,30,34; Sealer PlusTM BC^17,19,27,33; Bio-CTM Sealer⁹; and EndosealTM²⁸. All articles used as control group the AH PlusTM resin cement. Two articles, in addition to the AH PlusTM cement, analysed the properties of the ObturysTM³⁴ and Sealer PlusTM³² cements.
Differences were observed, both between the different silicate-based cements as between the evaluation periods, in relation to resin-based cements. The BioRootTM RCS cement presented higher solubility than the AH PlusTM^20,34,37 and ObturysTM³⁴ resin cements. The Bio-CTM Sealer cement also showed higher solubility than the AH PlusTM9 cement.
Similarly, TotalFillTM BC Sealer cement obtained greater solubility than AH PlusTM resin cement in most of the analytical periods in the different studies^9,30,34.
However, in the first evaluation period of a study³⁴, no significant differences were observed between BioRootTM RCS and AH PlusTM and ObturysTM resinbased cements. On the other hand, in most studies and periods analysed of the MTA FillapexTM cement, a higher solubility was observed compared to resin cements^{20,32,34,35,37}. However, one study observed greater solubility of MTA FillapexTM compared to AH PlusTM at two hours of evaluation²⁰. On the other hand, different studies did not show any differences regarding solubility between the two cements during the first minute of evaluation²⁰, at 24 hours34 and after a week^34,36. However, studies that analysed longer evaluation periods, the solubility of MTA FillapexTM cement was superior to that of resin cement^32,35,37.
On the other hand, the silicate cement Sealer PlusTM BC obtained contradictory results. In one study¹⁹ presented greater solubility than AH PlusTM, while in two studies there were no differences between both^17,27.
Similarly, the only study that analysed the EndosealTM²⁸ cement did not obtain solubility differences with respect to AH PlusTM resin cement in the analysed period.
When evaluating the solubility between the different silicate-based cements different results were observed between the different evaluation periods. Bio-CTM Sealer cement presented higher solubility than the TotalFillTM BC Sealer⁹ cement. On the other hand, in one study there were no significant differences in the different periods between TotalFillTM BC Sealer, MTA FillapexTM and BioRootTM RCS cements, except in the first evaluation period (24 hours), in which, the BioRootTM RCS cement presented higher solubility than the MTA FillapexTM³⁴. However, the solubility of both cements differs between studies, since greater solubility can be observed of MTA FillapexTM compared to BioRootTM RCS²⁰, as greater solubility of BioRootTM RCS cement compared to MTA FillapexTM³⁷. Further research would be needed to analyse the solubility of both cements in the long term.

Taking into account the lack of long-term clinical studies and the limitations of in vitro studies, the physical properties of new silicate-based sealants can guide the dentist in the selection of the sealing cement.
There were no differences in tooth discoloration between silicate-based and epoxy resin-based cements. Neither were differences observed between both types of cements, regarding sealing, in most of the studies selected in the present work.
Both epoxy resin-based cement and silicate-based cements presented radiodensity values within the recommended ISO standards. The setting time of silicate-based cements, compared with resin cements, varied depending on the type of cement. Although solubility varied according to the cement type and the evaluation period, some of the silicate-based cements showed higher solubility than resin-based cements.