The use of Bioceramics as root-end filling materials in periradicular surgery: a literature review

Introduction: Periradicular surgery involves the placement of a root-end filling following root-end resection, to provide an apical seal to the root canal system. Historically several materials have been used in order to achieve this seal. Recently a class of materials known as Bioceramics have been adopted. The aim of this article is to provide a review of the outcomes of periradicular surgery when Bioceramic root-end filling materials are used on human permanent teeth in comparison to “traditional” materials. Methods & results: An electronic literature search was performed in the databases of Web of Science, PubMed and Google Scholar, between 2006 and 2017, to collect clinical studies where Bioceramic materials were utilised as retrograde filling materials, and to compare such materials with traditional materials. In this search, 1 systematic review and 14 clinical studies were identified. Of these, 8 reported the success rates of retrograde Bioceramics, and 6 compared treatment outcomes of mineral trioxide aggregate (MTA) and traditional cements when used as root-end filling materials. Conclusion: Bioceramic root-end filling materials are shown to have success rates of 86.4–95.6% (over 1–5 years). Bioceramics has significantly higher success rates than amalgam, but they were statistically similar to intermediate restorative material (IRM) and Super ethoxybenzoic acid (Super EBA) when used as retrograde filling materials in apical surgery. However, it seems that the high success rates were not solely attributable to the type of the root-end filling materials. The surgical/microsurgical techniques and tooth prognostic factors may significantly affect treatment outcome

The endodontic biofilm: effects of chitosan as a novel antimicrobial agent

Background and objectives: Endodontic infection or root canal infection, as it is commonly referred to, is a biofilm disease that is difficult to completely irradicate with current treatment protocols, and as such, persistent microorganisms may lead to ongoing or recurrent disease. Root canal treatment is founded on the ability to eradicate microbial infection and prevent reinfection of the highly complex root canal space. There is a growing realisation that endodontic infections are polymicrobial and may contain Candida spp. Despite this understanding, the development of new endodontic therapeutics and models of pathogenesis remains limited to mono-species biofilm models, which are bacterially focused. The main aims of this thesis were firstly to develop and optimise an interkingdom endodontic biofilm model comprised of microbial species frequently identified in endodontic infections and to use this model to test antibiofilm actives. Secondly, to evaluate the antibiofilm efficacy of Mineral Trioxide Aggregate and Biodentine™ calcium silicate cements, used in the management of endodontic diseases, and how modification with chitosan may impact on their antimicrobial properties. Thirdly, to investigate the effect of chitosan incorporation on some of the physico mechanical and biological properties of Biodentine. Materials and methods: Biofilms containing Fusobacterium nucleatum (ATCC 10953), Porphyromonas gingivalis (ATCC 33277), Streptococcus gordonii (ATCC 35105) and Candida albicans (SC5314) were established. Biofilms were optimised in different growth conditions, using quantitative polymerase chain reaction and qualitative microbiology techniques. The in vitro biofilm model was treated with chlorhexidine, ethylenediaminetetraacetic acid and chitosan solutions. This was reaffirmed on a biological substrate (bovine dentine), to further validate this model and the antimicrobial effectiveness of chitosan. To evaluate the antibiofilm efficacy of calcium silicate materials, the regrowth of mono-species (C. albicans), three multispecies (F. nucleatum, P. gingivalis and S. gordonii) and four multispecies (F. nucleatum, P. gingivalis, S. gordonii and C. albicans) biofilms on ProRoot MTA and Biodentine discs were explored using livedead qPCR. These were compared to regrowth on bovine dentine discs. The effect on regrowth of biofilms was assessed following the addition of 2.5 wt% and 5 wt% of chitosan medium molecular weight powder to each calcium silicate cement. Subsequently, the setting time, disintegration, radiopacity, compressive strength, microhardness and biocompatibility of the new composite of Biodentine modified with chitosan were assessed. Next, the regrowth of the four multispecies (F. nucleatum, P. gingivalis, S. gordonii and C. albicans) biofilms on Biodentine discs were explored following the addition of 0.5 wt% and 1 wt% of chitosan powder of either high, medium or low molecular weights. This was compared to regrowth on the unmodified formula of Biodentine. Finally, the physico-mechanical and biological properties of the new composite of Biodentine modified with chitosan low molecular weight were evaluated. Results: Assessment of antimicrobial activity of CHX, EDTA and solubilised chitosan showed significant effectiveness of each antimicrobial agent. Chitosan was similarly effective at preventing biofilm regrowth on bovine dentine. In comparison to a dentine substrate, ProRoot MTA and Biodentine did not show an ability to inhibit biofilm regrowth. The addition of chitosan powder to MTA imparted no antimicrobial enhancement. In contrast, a dose dependent reduction in multispecies biofilm regrowth was determined upon the addition of chitosan to Biodentine. Interestingly, the antibiofilm effect of chitosan increases with the decreased chitosan molecular weight. Importantly, interkingdom interactions were noted, whereby the inclusion of C. albicans to the biofilm enhanced bacterial tolerance in the presence of chitosan and conversely bacterial presence reduced C. albicans tolerance. However, incorporation of 2.5 wt% and 5 wt% chitosan MMw compromises most of the material properties of Biodentine. In contrast, the addition of 0.5 wt% and 1 wt% chitosan LMw showed no detrimental effects on physical and biological properties of Biodentine material, however, significant reductions were noted in mechanical properties of Biodentine when chitosan was incorporated. Nevertheless, the new composite would still be applicable where other root filling materials might be considered, when the material strength and hardness are not critical issues. Conclusion: This thesis describes a robust and reproducible multispecies interkingdom biofilm model that can be employed to assess efficacy of novel endodontic therapeutics. This work demonstrates the potential to enhance the antimicrobial properties of Biodentine, when modified with chitosan microparticles, opening the door for exploration of antimicrobial strategies for prevention and management of endodontic infections. The findings also highlight the importance of using appropriate biofilm model systems when exploring antimicrobial properties of materials in vitro, so that interspecies and interkingdom interactions that modify tolerance are not overlooked

Filling the void: an optimized polymicrobial interkingdom biofilm model for assessing novel antimicrobial agents in endodontic infection

There is a growing realization that endodontic infections are often polymicrobial, and may contain Candida spp. Despite this understanding, the development of new endodontic irrigants and models of pathogenesis remains limited to mono-species biofilm models and is bacterially focused. The purpose of this study was to develop and optimize an interkingdom biofilm model of endodontic infection and use this to test suitable anti-biofilm actives. Biofilms containing Streptococcus gordonii, Fusobacterium nucleatum, Porphyromonas gingivalis, and Candida albicans were established from ontological analysis. Biofilms were optimized in different media and atmospheric conditions, prior to quantification and imaging, and subsequently treated with chlorhexidine, EDTA, and chitosan. These studies demonstrated that either media supplemented with serum were equally optimal for biofilm growth, which were dominated by S. gordonii, followed by C. albicans. Assessment of antimicrobial activity showed significant effectiveness of each antimicrobial, irrespective of serum. Chitosan was most effective (3 log reduction), and preferentially targeted C. albicans in both biofilm treatment and inhibition models. Chitosan was similarly effective at preventing biofilm growth on a dentine substrate. This study has shown that a reproducible and robust complex interkingdom model, which when tested with the antifungal chitosan, supports the notion of C. albicans as a key structural component

The effect of chitosan incorporation on physico-mechanical and biological characteristics of a calcium silicate filling material

Objectives: A tricalcium silicate-based cement, Biodentine™, has displayed antibiofilm activity when mixed with chitosan powder. This study aimed to assess the effect of chitosan incorporation on the physico-mechanical and biological properties of Biodentine™. Methods: In this study, medium molecular weight chitosan powder was incorporated into Biodentine™ in varying proportions (2.5 wt%, 5 wt%, 10 wt%, and 20 wt%). The setting time was determined using a Vicat apparatus, solubility was assessed by calculating weight variation after water immersion, radiopacity was evaluated and expressed in millimeters of aluminum, the compressive strength was evaluated using an Instron testing machine, and the microhardness was measured with a Vickers microhardness tester. In addition, surface topography of specimens was analyzed using scanning electron microscopy, and the effect of chitosan on the viability of human embryonic kidney (HEK 293) cells was measured by a colorimetric MTT assay. Results: Incorporation of 2.5 wt% and 5 wt% chitosan powder delivered an advantage by speeding up the setting time of Biodentine material. However, the incorporation of chitosan compromised all other material properties and the crystalline structure in a dose-dependent manner. The chitosan-modified material also showed significant decreases in the proliferation of the HEK 293 cells, signifying decreased biocompatibility. Significance: Chitosan incorporation into calcium silicate materials adversely affects the physical and biological properties of the material. Despite the increased antimicrobial activity of the modified material, the diminution in these properties is likely to reduce its clinical value

Detection, treatment and prevention of endodontic biofilm infections: what's new in 2020?

Endodontic disease, a biofilm infection of the root canal space, is a significant cause of dental morbidity worldwide. Endodontic treatment, or root canal treatment, as it is commonly known is founded on the ability to eradicate microbial biofilm infection and prevent re-infection of the highly complex root canal space. Despite many “advances” in clinical endodontics we have seen little improvement in outcomes. The aim of this critical review paper is to provide a contemporary view of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease

Chitosan enhances the anti-biofilm activity of biodentine against an interkingdom biofilm model

Endodontic infection is a biofilm disease that is difficult to irradicate with current treatment protocols, and as such, persistent micro-organisms may lead to ongoing or recurrent disease. The potential for the use of enhanced filling materials to modify biofilm regrowth is a promising strategy. This current study aimed to evaluate the anti-biofilm efficacy of calcium silicate cements modified with chitosan. The development of mono-species and multi-species biofilms on ProRoot MTA, Biodentine and bovine dentine discs were explored using quantitative microbiology analysis. The effect on regrowth of biofilms was assessed following the addition of chitosan to each cement. In comparison to a dentine substrate, both materials did not show the ability to inhibit biofilm regrowth. Biodentine incorporated with chitosan displayed a dose-dependent reduction in multi-species biofilm regrowth, unlike MTA. Notably, interkingdom biofilms were shown to enhance bacterial tolerance in the presence of chitosan. This study demonstrates the potential to enhance the antimicrobial properties of Biodentine. The findings highlight the need for appropriate model systems when exploring antimicrobial properties of materials in vitro so that interspecies and interkingdom interactions that modify tolerance are not overlooked while still supporting the development of innovative materials

Investigating the role of Candida albicans as a universal substrate for oral bacteria using a transcriptomic approach : implications for interkingdom biofilm control?

FUNDING INFORMATION We would like to acknowledge the funding support from the GlaxoSmithKline BBSRC Industrial CASE PhD studentship for CD (BB/P504567/1).Peer reviewedPublisher PD