Dental Hypotheses

REVIEW
Year
: 2019  |  Volume : 10  |  Issue : 1  |  Page : 4--8

Prevention of Tooth Discoloration Due to Calcium-Silicate Cements: A Review


Naghmeh Meraji, Behnam Bolhari, Maryam Rezazadeh Sefideh, Soheil Niavarzi 
 Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran

Correspondence Address:
Maryam Rezazadeh Sefideh
Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, North Kargar st., Tehran
Iran

Abstract

Introduction: Mineral trioxide aggregate (MTA) and other calcium silicate cement similar to that are widely used in endodontic treatments. One of the widely emphasized disadvantages of these cements are the induction of tooth discoloration. The purpose of this study was to investigate the mechanisms of tooth discoloration caused by MTA and MTA-like cements and debate different methods suggested for preventing it. Methods: An electronic search was performed using databases such as Google Scholar, PubMed, PubMed Central, Science Direct, and Scopus by using keywords such as “mineral trioxide aggregate”, “calcium-silicate”, “tooth discoloration”, and “prevention”. Results: Several methods for preventing tooth discoloration caused by MTA and MTA-like cements have been proposed including the application of dentin bonding agents on dentinal walls, use of cements containing radiopacifying agents other than bismuth oxide, and addition of zinc oxide to those cements containing bismuth oxide. Conclusion: Most studies have shown that none of these methods can completely inhibit tooth discoloration but can decrease it to some length.



How to cite this article:
Meraji N, Bolhari B, Sefideh MR, Niavarzi S. Prevention of Tooth Discoloration Due to Calcium-Silicate Cements: A Review.Dent Hypotheses 2019;10:4-8


How to cite this URL:
Meraji N, Bolhari B, Sefideh MR, Niavarzi S. Prevention of Tooth Discoloration Due to Calcium-Silicate Cements: A Review. Dent Hypotheses [serial online] 2019 [cited 2019 Aug 17 ];10:4-8
Available from: http://www.dentalhypotheses.com/text.asp?2019/10/1/4/260576


Full Text



 Introduction



Mineral trioxide aggregate (MTA) is a type of hydrophilic calcium silicate cement first introduced by Torabinejad et al. in 1993[1] and approved by the Food and Drug Administration to be used in the United States in 1997. It is widely used in endodontics and some of this cement’s applications include root end filling, repair of root perforations, vital pulp therapy, as an apical barrier, and as a coronal barrier.[2] Various in vitro studies have shown this cement to have various advantages and appropriate properties such as good biocompatibility and sealing ability,[3] antibacterial properties,[4] and setting in aqueous environments.[5] Promising clinical outcomes have also been reported for the use of MTA in these clinical applications.[6],[7],[8] However, some disadvantages have been reported for this cement including having a long setting time,[9] difficult handling,[10] causing tooth discoloration,[11] and being influenced by environmental conditions.[5],[12],[13],[14]

To overcome these disadvantages, other calcium silicate cements similar to MTA have been introduced over the years [Table 1].{Table 1}

As the use of these cements in clinical cases have increased overtime, many have encountered the tooth discoloration caused by these cements which is usually associated with patient dissatisfaction. This has caused wide emphasis on this subject in such a way that the American Association of Endodontists[15] and the European Society of Endodontology[16] have discussed this matter in the position statement for regenerative endodontic treatment. Considering that the patient’s needs and preferences are one of the three critical important components of an evidence-based approach for clinical treatments,[17] evaluating methods for preventing tooth discoloration in cases requiring the use of calcium silicate cements is of significance. The aim of this review article was to investigate the mechanisms of tooth discoloration caused by calcium silicate cements and discuss different methods suggested for preventing it.

 Methods



An electronic search was performed using databases such as Google Scholar, PubMed, PubMed Central, Science Direct, and Scopus by using keywords such as (“mineral trioxide aggregate” OR “calcium-silicate” OR the name of all calcium silicate cements available) AND (“discoloration” OR “staining potential” OR “color” OR “colour”) AND (“tooth” OR “teeth”) AND/OR “prevention”. The last search was performed on March 2019.

The inclusion criteria were all in vitro, ex vivo, clinical studies, case reports or series, and review articles that evaluated tooth discoloration induced by different calcium silicate-based cements and/or its prevention in peer-reviewed journals published in English. Exclusion criteria included studies published in a language other than English, abstracts from congress.

The articles were selected to address the following research question: How can the discoloration due to calcium silicate-based cements be prevented?

 Result



A total of 427 articles were identified after elimination of duplicates by our search strategy. After evaluation of the titles, abstracts, and full texts, 71 references were included for review and evaluation. Among these articles, nine were review articles regarding discoloration caused by calcium silicate cement, three were clinical trials, and five were case reports/series. Only seven articles were related to tooth discoloration prevention.

 Discussion



Tooth discoloration caused by calcium silicate cements

The first type of MTA introduced was gray MTA. This formulation caused obvious tooth discoloration. As the color of this cement was gray, tooth discoloration was initially considered resultant of its color which was due to the presence of FeO, MgO, and Al2O3 in its composition.[1] Therefore, these metallic oxides were eliminated from its formulation and tooth colored/white MTA (WMTA) was introduced; however, this formulation also caused some degrees of tooth discoloration.[26],[27]

Overall, reasons for the tooth discoloration caused by WMTA are as follows:Presence of 9% iron oxide in WMTA[28] attributed to the calcium aluminoferrite phase of its powder.Presence of bismuth oxide as a radiopacifier in its composition[29],[30] that can interact with strong oxidizing agents,[31] that is, sodium hypochlorite commonly used as an irrigating solution, during endodontic treatments resulting in the production of carbonate bismuth[29],[30] or interact with collagen in tooth dentin, forming a black precipitate.[29]Penetration of erythrocytes from environmental blood into porosities of unset MTA and consequently tooth discoloration due to both discoloration of the MTA bulk and accumulation of hemoglobin or other forms of hematin molecules in dentin.[24],[32]

Preventing tooth discoloration caused by calcium silicate cements

Based on these mechanisms for causing tooth discoloration, several strategies have been introduced to prevent this discoloration, which are as follows:Using calcium silicate cements containing alternative radiopacifying agents such as zirconium oxide and calcium tungstate.[33],[34]Sealing the dentinal tubules of pulp chamber prior to the application of calcium silicate cements using dentin bonding agents.[35]Placing MTA below the cementoenamel junction.[36]Adding zinc oxide (ZnO)[37] or aluminum fluoride (AlF3)[38] to the powder of WMTA.

Studies have shown that the methods described above cannot completely inhibit tooth discoloration but can decrease it to some extent [Table 2].{Table 2}

In the case of using calcium silicate cements containing alternative radiopacifying agents, studies have shown different outcomes. For instance, most studies reported less tooth discoloration when Biodentine, a calcium silicate cement lacking bismuth oxide and containing zirconium oxide as its radiopacifying agent, was applied.[18],[33],[39] However, Ramos et al.[40] showed significantly higher levels of tooth discoloration 12 months after the application of this cement. These levels were similar to the levels reported for WMTA in other studies.[19],[20] BioAggregate is another calcium silicate cement lacking bismuth oxide. This cement contains tantalum peroxide as the radiopacifying agent. Yoldaş et al.[34] have shown that this cement causes lower levels of tooth discoloration compared to ProRoot MTA; however, it caused higher levels of tooth discoloration compared to Biodentine. This was attributed to higher porosity and higher fluid uptake in BioAggregate. Marconyak et al.[39] showed that Endo Sequence Root Repair, a calcium silicate cement containing zirconium oxide and tantalum oxide, and Biodentine did not cause significant tooth discoloration.

Although the use of cements with radiopacifying agents other than bismuth oxide may cause less tooth discoloration, these cement are less radiopaque.[41] Increasing the amount of radiopacifying agents in their formulation causes adverse effects on physical and chemical properties of these cement.[29]

Regarding the use of dentin bonding agents prior to the application of calcium silicate cements, the few available studies performed up to now have shown that this approach can decrease tooth discoloration caused by these cements.[35],[42] The dentin bonding acts as barrier preventing cement accumulation in the access cavity and its contact with dentin collagen. The use of multiple layers of dentin bonding have been suggested for better coverage.

Another approach for preventing tooth discoloration was proposed by Marciano et al.[37],[38] They suggested adding ZnO or AlF3 to white MTA Angelus. They reported that Zn and AlF3 molecules interact with the bismuth oxide, stabilizing it and preventing the interact of bismuth oxide with strong oxidizing agents.[37],[38] They concluded that addition of 5% ZnO to white MTA Angelus inhibited tooth discoloration and increased calcium release from this cement, not affecting its other properties,[37] whereas addition of 5% and 15% AlF3 increased the pH and calcium ion release of the cement.[38] More research is required.

Overall, the majority of articles on this topic of tooth discoloration caused by calcium silicate cements are in vitro or ex vivo studies. These in vitro or ex vivo cannot completely simulate all clinical conditions such as the effect of temperature changes in the oral environment on discoloration and its prevention. Among the few clinical studies including clinical trials and case reports/series, all only reported the occurrence of discoloration and none quantified and compared its intensity. Very few articles have evaluated methods for prevention of tooth discoloration. It seems that although prevention is always better than treatment, this topic requires more attention and research.

 Conclusion



Although strategies have been proposed to prevent tooth discoloration caused by calcium silicate cement, up to now, none were able to completely inhibit it.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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