Towards an improved dental pulp-capping therapy

SUMMARY. A recent Delphi survey on the future of restorative dentistry for the next 20 years identified maintenance of the pulp vitality as of the highest importance [1]. The authors rated bioactivity toward the pulp-dentin complex as key property for future tooth-restorative materials. This need to develop bioactive restorative materials was also the conclusion drawn on a workshop ('Future innovation and research in dental restorative materials') of the International Association for Dental Research (2012) in response to the decision taken by WHO to globally phase-down the use of (dental) mercury (amalgam restorations). Both 'maintenance of pulp vitality' and 'bioactivity toward the pulp-dentin complex' imply a need for the restorative material to be also therapeutically active in the form of biologic interaction with tooth-pulp cells. The two processes targeted are reactionary and reparative dentinogenesis [2]. Reactionary dentinogenesis refers to the stimulation of healthy odontoblasts to produce tertiary dentin to serve as barrier against external irritants that may endanger the pulp's vitality('indirect' pulp capping). Reparative dentinogenesis requires recruitment of new cells thatdifferentiate into new odontoblasts-like (dentin-forming) cells in the event the pulp is severely injured with loss/destruction of the original odontoblasts. This 'direct' pulp capping is typically employed to treat pulpal exposures, accidentally caused by trauma or by the dentist when bur excavating aries very close to the pulp. The ultimate goal is to avoid an often technically demanding and costly root-canal treatment that would definitely undermine the tooth's lifetime; a pulpless tooth is weaker, may discolor, and often requires more invasive restorative procedures like the preparation of a root-canal post. Vital pulp therapy involves the placement of a bioactive medicament directly over the exposed pulp with the objective of maintaining the pulp's vitality [3]. Primary requirements for a successful therapy are an uninflamed pulp, adequate arrest of pulpal bleeding (hemorraghe control), a bacteria-tight seal, and the use of a capping material that is not only tolerated by the pulp, but also bio-activates the pulp [4]. A more invasive form, commonly applied to deciduous teeth of children, is a pulpotomy; this involves removal of the inflamed pulp tissue to the level of healthy coronal or even root pulp, followed by application of the pulp-capping agent. Historically, Calcium hydroxide (CaOH) has been the standard pulp-capping agent [5]. The mechanism of action has been attributed to its disinfection potential and simultaneous induction of dentinal bridge formation (12). The mild irritation provoked to the pulp initiates an inflammatory response that, in absence of bacteria, will heal by forming a dentin bridge'. While the actual repair mechanism is still not fully understood, the induced release of bioactive molecules, including bone morphogenetic proteins (BMP) and transforming growth factor beta (TBF-ß) has been demonstrated to be involved [6,7]. Major shortcomings of CaOH are inferior physico-mechanical properties (disintegrates over time) and limited sealing potential against external bacterial ingress. CaOH does not self-adhere to dentin and a dentin bridge formed beneath CaOH often contains 'tunnel defects', still enabling bacterial penetration. Throughout the years, alternative materials, like zinc oxide eugenol, glass-ionomers, resin-based adhesives, and more recently a bioactive cement, known as 'mineral trioxide aggregate' (MTA), have been advocated for vital pulp therapy [3,8]. Much dispute arose within the research community regarding the use of resin-based adhesives; while they possess a better sealing ability, they lack antibacterial properties(with some exceptions) and they are most of all disliked for their (alleged) toxicity, in particular when applied directly to exposed pulpal tissue [9,10]. MTA (alkaline material based on calcium silicate technology) stimulates dentinal bridging; it is today frequently employed in clinical practice as pulp-capping material, yet long-term clinical success needs to be demonstrated [8]. The primary reaction product of MTA with water is calcium hydroxide, so its principal mechanism of action largely follows that of CaOH. Besides for (in)direct pulp capping (and pulpotomy), MTA serves a more versatile application area, in particular as root canal repair material (root perforation, ex-/internal resorption, apexification, apexogenesis, revascularisation); it is often used as ultimate remedy to preserve the tooth that otherwise would be extracted. While setting within a moist environment and providing some dentinal sealing, reported disadvantages of MTA are its prolonged setting time, long-term solubility, potential discoloration of the tooth due to iron (grey formulation), its less user-friendly handling and relatively high cost. OBJECTIVES. Maintaining the pulp vital has been identified as a major future role of tooth-restorative treatment, thereby emphasizing the importance/impact of this research project, in particular as the restoration of teeth accounts for the major part of everyday dental practice and nearly the whole population may be in need of a tooth restoration sooner or later. The OVERALL PROJECT AIM is to contribute to a better understanding of biomaterial-pulp interactions and yet to explore the mechanisms of pulpal repair following 'direct' pulp capping, which today remain insufficiently understood [2,11]. Since the current pulp-capping agents fall somewhat short of several properties, such as overall pulp survival, sealing ability, physicomechanical properties, and clinical handling, the more SPECIFIC PROJECT OBJECTIVE is to develop a clinically more effective and predictable pulp-capping material/technique. 1. Seemann et al. Restorative dentistry and restorative materials over the next 20 years: A Delphi survey. Dent Mater 2014 doi:10.1016/j.dental.2014.01.013. 2. Ferracane et al. Can interaction of materials with the dentin-pulp complex contribute to dentin regeneration? Odontology 2010;98:2-14. 3. Hilton TJ. Keys to clinical success with pulp capping: a review of the literature. Oper Dent 2009;34:615-25. 4. Swift et al. Vital pulp therapy for the mature tooth - can it work? Endodontic Topics 2003;5:49- 56. 5. Stanley and Pameijer. Dentistry's friend: calcium hydroxide. Oper Dent 1997;22:1-3. 6. Graham et al. The effect of calcium hydroxide on solubilisation of bio-active dentine matrix components. Biomaterials 2006;27:2865-73. 7. Cooper et al. Inflammation-regeneration interplay in the dentine-pulp complex. J Dent 2010;38:687-97. (NWP). 8. Comparison of Ca(OH)2 with MTA for direct pulp capping: a PBRN randomized clinical trial. J Dent Res 2013;92:16S-22S. 9. Goldberg M. Biocompatibility or cytotoxic effects of dental composites. 2009: Coxmoor publishing; ISBN: 978-1-901892-34-5. 10. Van Landuyt, ..., Van Meerbeek. How much do resin-based dental materials release? A metaanalytical approach. Dent Mater 2011;27:723-47. 11. Niu et al. A review of the bioactivity of hydraulic calcium silicate cements. J Dent 2014; doi: 10.1016/j.jdent.2013.12.015. 12. Yoshida, Van Meerbeek et al. Evidence of chemical bonding at biomaterial-hard tissue interfaces. J Dent Res 2000;79:709-14.status: publishe

Regeneration of the Pulp Tissue: Cell Homing versus Cell Transplantation Approach: A Systematic Review

Background: The main objective of this systematic review was to compare the apical healing, root maturation and histological characteristics of teeth treated with cell-based versus cell-free techniques. Methods: The methodology of this review was based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 August 2021. Articles written in languages other than English were excluded. Two researchers independently selected the studies and extracted the data. As no randomized clinical trials were available, animal studies were included. Results: In total, 26 studies were included in the systematic review: 22 articles only researched the cell-free technique, 3 articles compared the cell-based to the cell-free technique, and 1 article compared the cell-based technique to apexification. In terms of apical healing, qualitative analysis of the data suggested that there seems to be no significant difference between cell-free and cell-based techniques. The results regarding tooth maturation are contradictory. The main difference between the cell-free and the cell-based techniques seems to be the histology of the treated tooth. The cell-free technique seems to result in cementum-like, bone-like or periodontal ligament-like tissue. One study, on the other hand, found that the cell-based technique resulted in regeneration of the whole pulp with an odontoblast layer, connective tissue, blood vessels and neuronal tissue. Conclusions: Currently, the number of randomized clinical trials on this topic are very scarce. This is probably due to the limited infrastructure and lack of resources to apply the cell-based technique. Even though both techniques seem to be promising for clinical application, long-term data need to be provided regarding the healing and reparative patterns

Cytotoxicity and Bioactivity of Dental Pulp-Capping Agents towards Human Tooth-Pulp Cells: A Systematic Review of In-Vitro Studies and Meta-Analysis of Randomized and Controlled Clinical Trials

Background. In the era of biology-driven endodontics, vital pulp therapies are regaining popularity as a valid clinical option to postpone root-canal treatment. In this sense, many different materials are available in the market for pulp-capping purposes. Objectives. The main aim of this systematic review and meta-analysis was to examine literature regarding cytotoxicity and bioactivity of pulp-capping agents by exposure of human dental pulp cells of primary origin to these materials. A secondary objective was to evaluate the inflammatory reaction and reparative dentin-bridge formation induced by the different pulp-capping agents on human pulp tissue. Data sources. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 May 2020. No filters or language restrictions were initially applied. Two researchers independently selected the studies and extracted the data. Study selectionincludedeligibility criteria, participants and interventions,study appraisal and synthesis methods. In vitro studies were included when human dental pulp cells of primary origin were (in)directly exposed to pulp-capping agents. Parallel or split-mouth randomized or controlled clinical trials (RCT or CCT) were selected to investigate the effects of different pulp-capping agents on the inflammation and reparative bridge-formation capacity of human pulp tissue. Data were synthesized via odds ratios (95% confidence interval) with fixed or random effects models, depending on the homogeneity of the studies. The relativerisks (95% confidence interval) were presented for the sake of interpretation. Results. In total, 26 in vitro and 30 in vivo studies were included in the systematic review and meta-analysis, respectively. The qualitative analysis of in vitro data suggested that resin-free hydraulic calcium-silicate cements promote cell viability and bioactivity towards human dental pulp cells better than resin-based calcium-silicate cements, glass ionomers and calcium-hydroxide cements. The meta-analysis of the in vivo studies indicated that calcium-hydroxide powder/saline promotes reparative bridge formation better than the popular commercial resin-free calcium-silicate cement Pro-Root MTA (Dentsply-Sirona), although the difference was borderline non-significant (p = 0.06), and better than calcium-hydroxide cements (p < 0.0001). Moreover, resin-free pulp-capping agents fostered the formation of a complete reparative bridge better than resin-based materials (p < 0.001). On the other hand, no difference was found among the different materials tested regarding the inflammatory effect provoked at human pulp tissue. Conclusions. Calcium-hydroxide (CH) powder and Pro-Root MTA (Dentsply-Sirona) have shown excellent biocompatibility in vitro and in vivo when tested on human cells and teeth. Their use after many years of research and clinical experience seems safe and proven for vital pulp therapy in healthy individuals, given that an aseptic environment (rubber dam isolation) is provided. Although in vitro evidence suggests that most modern hydraulic calcium-silicate cements promote bioactivity when exposed to human dental pulp cells, care should be taken when these new materials are clinically applied in patients, as small changes in their composition might have big consequences on their clinical efficacy. Key findings (clinical significance). Pure calcium-hydroxide powder/saline and the commercial resin-free hydraulic calcium-silicate cement Pro-Root MTA (Dentsply-Sirona) are the best options to provide a complete reparative bridge upon vital pulp therapy. Systematic review registration number.PROSPERO registration number: CRD42020164374.status: publishe

Survival of human dental pulp cells after 4-week culture in human tooth model

International audienceObjectives: This study aimed to validate the human tooth model by investigating the growth efficiency, expression of mesenchymal stem cell (MSC) markers and differentiation ability of human dental pulp cells (hDPCs) harvested from extracted immature third molars and cultured for different periods. Moreover, the effect of exposure and capping with a hydraulic calcium-silicate cement on pulp tissue after 4-week culture in the tooth model was investigated.Methods: Primary hDPCs were collected from 18 molars from six individuals (15-19 years). One tooth of each patient was immediately cultured (control), while the other teeth were exposed to culture medium for 1, 2 or 4 weeks. After different culture periods, cells were harvested using the explant method, upon which cells were evaluated for cell-doubling time, colony-forming efficiency and expression of cell surface markers. The osteo-genic, adipogenic and chondrogenic differentiation efficacy was also determined. Two teeth from three different patients (n = 6) were used for the pulp-capping assay. Three teeth were capped with ProRoot MTA (Dentsply Sirona), while three other exposed teeth remained uncapped (control).Results: Cells were found to grow, express MSC markers and showed osteogenic, adipogenic and chondrogenic differentiation potential at all time periods. Histology of the teeth subjected to the pulp-capping assay showed the formation of mineralized tissue after 4-week exposure to ProRoot MTA (Dentsply Sirona) and normal his-tological features in the control teeth.Conclusions: This study confirmed that hDPCs of teeth cultured for up to 4 weeks in a human tooth model are viable, express MSC markers and show differentiation ability. Clinical Significance: The human tooth model can be seen as an advanced cell-culture model that makes use of the original 3D pulp-chamber structure. It can serve as a screening tool to evaluate new pulp-capping formulations in a relatively cheap and fast manner

Survival of human dental pulp cells after 4-week culture in human tooth model

OBJECTIVES: This study aimed to validate the human tooth model by investigating the growth efficiency, expression of mesenchymal stem cell (MSC) markers and differentiation ability of human dental pulp cells (hDPCs) harvested from extracted immature third molars and cultured for different periods. Moreover, the effect of exposure and capping with a hydraulic calcium-silicate cement on pulp tissue after 4-week culture in the tooth model was investigated. METHODS: Primary hDPCs were collected from 18 molars from six individuals (15-19 years). One tooth of each patient was immediately cultured (control), while the other teeth were exposed to culture medium for 1, 2 or 4 weeks. After different culture periods, cells were harvested using the explant method, upon which cells were evaluated for cell-doubling time, colony-forming efficiency and expression of cell surface markers. The osteogenic, adipogenic and chondrogenic differentiation efficacy was also determined. Two teeth from three different patients (n = 6) were used for the pulp-capping assay. Three teeth were capped with ProRoot MTA (Dentsply Sirona), while three other exposed teeth remained uncapped (control). RESULTS: Cells were found to grow, express MSC markers and showed osteogenic, adipogenic and chondrogenic differentiation potential at all time periods. Histology of the teeth subjected to the pulp-capping assay showed the formation of mineralized tissue after 4-week exposure to ProRoot MTA (Dentsply Sirona) and normal histological features in the control teeth. CONCLUSIONS: This study confirmed that hDPCs of teeth cultured for up to 4 weeks in a human tooth model are viable, express MSC markers and show differentiation ability. CLINICAL SIGNIFICANCE: The human tooth model can be seen as an advanced cell-culture model that makes use of the original 3D pulp-chamber structure. It can serve as a screening tool to evaluate new pulp-capping formulations in a relatively cheap and fast manner.status: publishe

Mesiobuccal Root Canal Morphology of Maxillary First Molars in a Brazilian Sub-Population - A Micro-CT Study

Objective: This study aimed to investigate the root canal system morphology of maxillary first molar mesiobuccal (MB) roots in a Brazilian sub-population using micro-computed tomography. Methods: Ninety-six MB roots were scanned with a micro-CT (Skyscan 1173, Bruker). Three-dimensional images were analyzed regarding the number of pulp chamber orifices, the number and classification of the canals, the presence of accessory canals in different thirds of the root as well as the number and type of apical foramina. Results: A single entrance orifice was found in 53.0% of the samples, two in 43.9% and only 3.1% had three orifices. The second mesiobuccal root canal (MB2) was present at some portion of the root in 87.5% of the specimens. A single apical foramen was present in 16.7%, two in 22.9%, and three or more foramina in 60.4% of the roots. Only 55.3% and 76.1% of the root canals could be arranged by Weine's and Vertucci's classifications, respectively. Conclusion: The number of orifices at the pulp chamber level could not work as a predictor of the MB2 presence. The most prevalent canal configuration was Weine type IV / Vertucci type V. The anatomical complexity of the MB root could not be entirely classified by the current most accepted classifications.status: publishe

Injectable phosphopullulan-functionalized calcium-silicate cement for pulp-tissue engineering: An in-vivo and ex-vivo study

OBJECTIVE: To evaluate, by means of an ex-vivo human tooth-culture model and in-vivo minipig animal study, the pulpal inflammatory reaction and reparative dentin-formation capacity of an injectable phosphopullulan-based calcium-silicate cement (GC, Tokyo, Japan) upon pulp capping, this in comparison with the commercial reference material Biodentine (Septodont). METHODS: For the ex-vivo tooth model, 9 freshly-extracted teeth from 3 different patients were pulp-capped with the experimental biomaterial (n = 3), Biodentine (n = 3) or left uncapped (control; n = 3). The teeth were kept in fresh culture medium for 4 weeks and, upon fixation three-dimensional Micro-CT and histology were performed. For the in-vivo animal study, 40 teeth from 3 minipigs were exposed and pulp capped with the experimental biomaterial containing phosphopullulan (n = 24) or Biodentine (n = 16) for 7 or 70 days. The inflammatory reaction and the tissue-regenerative potential was qualitatively and semi-quantitatively characterized using three-dimensional micro-CT and histology. RESULTS: Ex vivo, the treatment with the experimental phosphopullulan-based calcium-silicate cement and Biodentine stimulated the formation of fibrous tissue and mineralized foci. In vivo, early inflammatory reaction and regeneration of the pulp-tissue interface was promoted by both bioceramic materials after 7 and 70 days, respectively. SIGNIFICANCE: Our findings bring new insights into calcium-silicate-mediated dental pulp repair and regeneration. The novel ready-to-use and self-adhering functionalized calcium-silicate cement revealed effective pulpal repair potential.status: publishe

Preclinical effectiveness of an experimental tricalcium silicate cement on pulpal repair

International audienc

Preclinical effectiveness of an experimental tricalcium silicate cement on pulpal repair

OBJECTIVES: To investigate the pulpal repair potential of an experimental zirconium-oxide containing tricalcium-silicate cement, referred to as 'TCS 50'. MATERIALS AND METHODS: The effect of TCS 50 on viability, proliferation, migration, and odontoblastic differentiation of human dental pulp cells (HDPCs) was assessed using XTT assay, in-vitro wound healing assay and RT-PCR, respectively. Additionally, the pulp-capping potential was evaluated using a vital human tooth model. Statistical analysis was performed using non-parametric Kruskal-Wallis test and post-hoc test (Mann-Whitney U test). The tests were performed at a significance level of α = 0.05. RESULTS: The effect of TCS 50 towards HDPCs was dose dependent. Undiluted TCS 50 extract showed no immediate adverse impact on cell viability (p > .05); however, it significantly inhibited proliferation and migration of HDPCs (p  .05), and it significantly enhanced odontoblastic differentiation of HDPCs (p < .05). In pulps capped with TCS 50 for both 2 and 4 weeks, H&E staining revealed a normal morphology of pulp tissue; mineralized foci with cellular components entrapped in the matrix were formed underneath the exposure site. Collagen I expression was weak within the matrix of mineralized foci, while the expression of nestin was positive for entrapped cellular components within the mineralized foci, indicating that the formed mineralized foci corresponded to an initial form of reparative dentin formation. CONCLUSION: TCS 50 is capable of generating an early pulp-healing reaction and therefore could serve as a promising pulp-capping agent.status: publishe

Phosphopullulan-based pulp-capping material stimulates reparative dentin formation.

Objectives: To evaluate the inflammatory reaction and reparative dentin formation of a recently developed phosphopullulan-based (PPL) hydraulic calcium-silicate cement (hCSC) employed for pulp capping. Any discoloration of the hard dental tissues due to the material was also evaluated. Methods: After approval by the KU Leuven Ethical Commission for Animal Research, 44 permanent teeth from 3 minipigs (33-36 months old) were included in this study. The teeth were allocated to 2 time periods (7 and 70 days) and 2 different materials: experimental PPL-based hCSC (n=28) and Biodentine (Septodont; n=16), the latter serving as a commercially available control material. Briefly, after anesthesia at day 1, the teeth on?at the left side of the animals were ultrasonically cleaned, polished and finally disinfected using 10% iodine povidone. A 1-mm pulp exposure was immediately prepared with a sterile bur under copious saline water irrigation following the ISO 7045-2008 standard. After the bleeding was controlled, the pulp-capping materials were applied and the cavity closed using a glass-ionomer (Fuji II, GC) with a composite (G-aenial Posterior, GC) bonded (G-Premio Bond, GC) on top. Sixty-three days after the first procedure, the same operative treatment was carried out at the other side of the animals. On day 70, tooth discoloration was examined visually by two independent researchers. After perfusion under terminal anesthesia the teeth were harvested and fixed in 4% formaldehyde for 2 weeks. Micro-CT analysis (SkyScan 1172, Bruker) was performed and the degree of soft-tissue inflammation and mineralized tissue formation assessed histologically. Results: No significant difference in inflammation degree and mineralized tissue formation was observed for both hCSCs (p≥0.05). However, Biodentine induced significantly less tooth discoloration than the experimental hCSC containing PPL (p<0.05). Conclusions: The PPL-based hCSC was able to generate reparative dentin at a similar extent as the commercially available reference hCSC. Student Presenter This abstract is based on research that was funded entirely or partially by an outside source: FWO - Research Foundation Flanders (11B4318N) Disclosure Statement: The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONEstatus: Published onlin