Concentration-dependent Effect of Sodium Hypochlorite on Stem Cells of Apical Papilla Survival and Differentiation

Regenerative Endodontic Procedures in Immature Permanent Teeth With Dental Trauma: Current Approaches and Challenges

After dental trauma to immature permanent teeth (IPT), there can be pulpitis, necrotic, and periapical periodontitis, which will halt further root development. Traditional endodontic root canal treatments and apexification cannot revitalize the necrotic pulp to revitalize the tooth to promote further root development. As a consequence, IPT with thin dentinal walls can be prone to fracture and if a fracture occurs, the patient will likely suffer the loss of the tooth. In an attempt to save IPT, there has been a growing interest among dentists to use regenerative endodontic procedures (REPs) to revitalize a replace dental pulp to continue root development and strengthen the dentinal walls to help prevent a subsequent loss of the tooth. However, the effectiveness of REPs and the precise methods to successfully accomplish REPs are controversial. Therefore, the objective of this review is to compare the different approaches to REPs in case reports by highlighting their advantages and limitations.

Impact of sodium hypochlorite on organic tissue dissolution in the periapical region of immature permanent teeth: an ex vivo study

INTRODUCTION

To evaluate the impact of different sodium hypochlorite irrigation protocols on organic tissue dissolution in the periapical region of simulated immature permanent teeth.

METHODS

Eight single-rooted premolars and 48 samples of porcine palatal mucosa were used. Acrylic resin prototypes were constructed, placing the tissue in close contact with the dental apices. Specimens were then divided into six groups (n=8): two control groups, of saline irrigation with (NS/WA) or without (NS/NA) ultrasonic activation, and four experimental groups, of 1.5% and 2.5% sodium hypochlorite irrigation, with (NaOCl 1.5%/WA and NaOCl 2.5%/WA) or without (NaOCl 1.5%/NA and NaOCl 2.5%/NA) activation. Root canals were irrigated with 20 mL of the solution for 5 minutes, distributed over four irrigation cycles. In each cycle, after irrigation, the solution was either kept stagnant or activated for 30 seconds and then replaced. Specimens were weighed on a precision balance before and after the irrigation protocols. Tissue dissolution was measured by the difference between the initial and final weights. One-way ANOVA was applied, followed by Tukey's HSD test (α=0.05).

RESULTS

The NS/NA and NS/WA groups had mean weight reductions similar to the 1.5% NaOCl/NA group (p>0.05) and lower than the others (p<0.05). The 2.5% NaOCl/NA and 2.5% NaOCl/WA groups had the highest mean weight loss (p<0.05), while the 1.5% NaOCl/WA group had intermediate values (p<0.05).

CONCLUSIONS

Periapical tissue dissolution occurred in all groups, with greater impact observed with 2.5% NaOCl, with or without ultrasonic activation.

Comparative evaluation of bioglass nanofiber, dexamethasone-coated bioglass nanofiber, and platelet-rich fibrin, as scaffolds in regenerative endodontic treatment of immature necrotic teeth: A randomized controlled trial

Aim

The aim of this study was to evaluate and compare the regenerative endodontic potential of dexamethasone-coated bioglass nanofiber (Dex-BGnf), bioglass nanofiber (BGnf), and platelet-rich fibrin (PRF) for inducing regeneration in necrotic immature permanent teeth.

Materials and Methods

A total of 36 (n = 12) immature necrotic teeth with or without evidence of periapical lesion were included in the study. Patients were randomly allocated into three groups, based on the scaffolds used: Group I (PRF), II (BGnf), and III (Dex-BGnf). The clinical (electric pulp test) and radiographic evaluations (percentage increase in apical diameter, root length, root dentin thickness, and periapical healing) were compared at 6 and 12 months after the procedure with baseline records.

Statistical Analysis

One-way ANOVA, post hoc Tukey analysis, and Kruskal-Wallis test were used for evaluating the data. A 6- and 12-month improvement analysis was done using paired t-test and Friedman test.

Results

Clinically, all the 36 teeth were asymptomatic, but none gave a positive response to Electric Pulp Test (EPT) in time interval of 12 months. Dex-BGnf showed a statistically significant improvement in terms of increase in root length (P = 0.020) and root dentinal thickness (P = 0.001) when compared to PRF after 12 months.

Conclusion

The study has shown that Dex-BGnf yielded significantly better results than PRF for inducing apexogenesis in necrotic immature teeth.

Patient centered outcomes among a cohort receiving regenerative endodontic procedures or apexification treatments

INTRODUCTION

This multi-centered cohort study evaluated factors associated with patient-centered outcomes of immature permanent teeth that received regenerative endodontic procedures (REPs) or apexification treatment (APEX).

METHODS

A record review identified teeth treated with REPs or APEX between September 2005-December 2014. Data regarding treatment and patient-centered outcomes were extracted from records with a 3-month minimum recall. When possible, participants presented for an in-person prospective research visit. Patient-centered success was defined as an asymptomatic, functional tooth, not requiring further endodontic or surgical intervention following completion of the original treatment during the study observation. Risk ratios and adjusted and unadjusted Cox proportional hazard ratios were calculated.

RESULTS

The analytic cohort of 187 individuals included 211 teeth (93 REPs; 118 APEX) with an average follow-up of 32 months. Most cases were successful (81% REPs; 92% APEX) and survived the observation period (96% REPs; 97% APEX). The success rate of REPs was lower than APEX and decreased more rapidly over time. Cox regression analysis demonstrated that when controlling for other variables, the association between treatment type and outcome is not significant. Preoperative infection, teeth with more immature roots, and REPs treatment are potentially important predictors. Among teeth receiving REPs, a lower failure rate was observed for teeth that received multi-antibiotic paste (3/43) compared to calcium hydroxide (11/45).

CONCLUSIONS

Teeth receiving REPs required clinical intervention earlier than teeth that received APEX treatment, although preoperative abscess and more immature root also affected this outcome. Using multi-antibiotic paste versus calcium hydroxide in REPs may improve success.

Decision-Making and Management of Immature Permanent Teeth with Crown Fractures in Small Animals-A Review

Immature permanent teeth with crown fractures present a unique challenge in human and animal patients. Immature permanent teeth have not yet developed completely, often presenting with thin dentin walls, incomplete apical formation, and increased crown-to-root ratios. Loss of pulp function at this stage has devastating long-term implications for these teeth. Ideally, attempts should be made to preserve pulp vitality in immature permanent teeth to allow for continued dental development. The range of treatment options for vital teeth includes odontoplasty with bonding and sealing +/- restoration, indirect pulp capping, and direct pulp capping/vital pulp therapy. These treatments have long been established in human and veterinary medicine, and cases have been reported in dogs and cats. Apexification using calcium hydroxide is a well-established treatment for nonvital immature teeth. The advent of mineral trioxide aggregate and other bioceramic materials for use in vital pulp therapy and apexification has reduced treatment sessions and improved outcomes. Recent developments in the field of regenerative endodontic therapy further expand treatment options and provide the possibility for continued development of a formerly nonvital tooth. Selecting the appropriate treatment based on the severity of tooth fracture and status of pulp vitality can avoid a lifetime of poor structure and function for the affected tooth. This article provides multiple step-by-step protocols for the management of immature permanent teeth with crown fractures in small animals.

Effect of Different Root Canal Irrigant Solutions on the Release of Dentin-Growth Factors: A Systematic Review and Meta-Analysis

Irrigant solutions are used to promote dentin-growth factors (GF) release for regenerative endodontics. This review aimed to evaluate the reports comparing the release of GFs using different root canal irrigant solutions. Eligible studies compared the in vitro GF release in human teeth after the use of at least two distinct solutions. A search was conducted on Pubmed, Scopus, Web of Science, and Lilacs on 11 August 2021. Risk of bias was assessed using SciRAP. Study characteristics and quantitative data were extracted, and meta-analyses were performed for the mean difference (95% confidence interval) of the release of transforming growth factors Beta 1 (TGF-β1) by EDTA compared to other irrigants. Of sixteen eligible studies, eight were included in quantitative analysis. ELISA assays showed higher TGF-β1 release from 10% EDTA compared to 10% citric acid (p < 0.00001). Immunogold assays showed higher levels of TGF-β1 for 17% EDTA (p < 0.00001) compared to 10% citric acid. GRADE identified a low to very low certainty of evidence. These results point to an increased release of TGF-β1 in dentin treated with EDTA. The high heterogeneity and very low certainty of the evidence demand further studies before EDTA indication as a better irrigant for regenerative endodontics. Registration: CRD42020160871 (PROSPERO).

The cytotoxic effects of various endodontic irrigants on the viability of dental mesenchymal stem cells

This study aimed to evaluate cytotoxic effects of various irrigation solutions used in regenerative endodontic treatments (RETs) on mesenchymal stem cells, and further examine the long-term effect of hypochlorous acid (HOCl) on the cell viability and alkaline phosphatase (ALP) activity. Stem cells were exposed to various concentrations of NaOCl, EDTA, chlorhexidine (CHX), etidronic acid (HEDP)/NaOCl combination and HOCl. HOCl was tested for its effects on ALP activity up to 21 days. Additionally, cell viability was measured fluorescently using calcein AM. The most cytotoxic irrigant was CHX even with the lowest concentration. NaOCl and HEDP/NaOCl with 1:100 dilution decreased viability to around 40%. HOCl showed the lowest cytotoxicity among all tested irrigants. HOCl also showed no significant reduction in ALP activity compared with the controls. The cytotoxicity of endodontic irrigants was time and concentration dependent. HOCl demonstrated promising results regarding viability and ALP activity, since RETs require host stem cell survival.

Examining the Effect of Gravity on Different Irrigation Systems: An In vitro Study

Background

Periapical extrusion is frequently observed during endodontic therapy. It can lead to acute injury of periapical tissues, resulting in interappointment pain or swelling. The effect is pronounced in teeth with immature apex, which are more susceptible to the extrusion of irrigant. The aim of this study was to evaluate the effect of gravity on the apical extrusion of irrigating solution with different irrigation protocols in single-rooted premolars.

Methodology

A total number of 80 permanent single-rooted teeth (premolars) with same working length (WL) were divided into two main groups: Group A: Penetration depth of irrigation syringe to 2 mm from the WL and Group B: Penetration depth of irrigation syringe to 4 mm from the WL. Each group was subdivided into four subgroups. (n = 10). The extruded debris and irrigants were weighed, and the data were statistically analyzed by the analysis of variance and the Tukey test.

Results

Irrespective of the irrigation technique used, the amount of irrigant extruded from the apex showed a statistically significant difference related to the effect of gravity (P < 0.05). There was no statistically significant difference observed between irrigation methods (P > 0.05).

Conclusion

The degree of apical extrusion of irrigant was dependent on the type of irrigation technique and gravity. Greater caution should be taken during irrigation to prevent postoperative pain.

Exploiting dentine matrix proteins in cell-free approaches for periradicular tissue engineering

The recent discovery of mesenchymal stem cells within periapical lesions (PL-MSC) has presented novel opportunities for managing periradicular diseases in adult teeth by way of enhancing tissue regeneration. This discovery coincides with the current paradigm shift toward biologically driven treatment strategies in endodontics, which have typically been reserved for non-vital immature permanent teeth. One such approach that shows promise is utilizing local endogenous non-collagenous dentine extracellular matrix components (dECM) to recruit and upregulate the intrinsic regenerative capacity of PL-MSCs in situ. At picogram levels, these morphogens have demonstrated tremendous ability to enhance the cellular activities in in vitro and in vivo animal studies that would otherwise be necessary for periradicular regeneration. Briefly, these include proliferation, viability, migration, differentiation, and mineralization. Therefore, topical application of dECMs during ortho- or retrograde root canal treatment could potentially enhance and sustain the regenerative mechanisms within diseased periapical tissues that are responsible for attaining favorable clinical and radiographic outcomes. This would provide many advantages when compared with conventional antimicrobial-only therapies for apical periodontitis (AP), which do not directly stimulate healing and have had stagnant success rates over the past five decades despite significant advances in operative techniques. The aim of this narrative review was to present the novel concept of exploiting endogenous dECMs as clinical tools for treating AP in mature permanent teeth. A large scope of literature was summarized to discuss the issues associated with conventional treatment modalities; current knowledge surrounding PL-MSCs; composition of the dECM; inductive potentials of dECM morphogens in other odontogenic stem cell niches; how treatment protocols can be adapted to take advantage of dECMs and PL-MSCs; and finally, the challenges currently impeding successful clinical translation alongside directions for future research.

Clinical and Radiographic Outcomes of Regenerative Endodontic Procedures in Traumatized Immature Permanent Teeth: Interappointment Dressing or Single-Visit?

INTRODUCTION

More data are needed before affirming that single-visit approaches are effective and safe for regenerative endodontic procedures (REPs). This study compared clinical and radiographic outcomes of REPs between interappointment dressing or single-visit protocols.

METHODS

Twenty young patients presenting traumatized immature teeth with pulp necrosis were divided into 2 groups. Teeth were submitted to 6% sodium hypochlorite and 2% chlorhexidine irrigation and to 17% EDTA use before blood clot induction. In the interappointment dressing group (n = 11), calcium hydroxide was used with 2% chlorhexidine gel for 21 days before scaffold induction. In the single-visit group (n = 9), the scaffold was induced during the only appointment. Patients were followed up for 24 months. Primary, secondary, and tertiary outcomes were assessed by 3 independent evaluators. Preoperative and follow-up radiographs were assessed for quantitative measurements of the apical diameter, root width, root length, and cervical barrier placement and compared between groups using the t test or Mann-Whitney U test. Categoric variables were assessed with the G test and the Fisher exact test and continuous variables with the Mann-Whitney U test. Statistical significance was set at 5%.

RESULTS

One tooth showed persistence of infection. No difference was observed in cervical barrier placement (P > .05); between groups regarding primary, secondary, and tertiary outcomes (P > .05); and in parameters of quantitative radiographic outcomes (P > .05).

CONCLUSIONS

Completing REPs with an interappointment dressing or a single-visit protocol presented similar clinical and radiographic outcomes. A single-visit protocol of REPs using 6% sodium hypochlorite, 2% chlorhexidine, and 17% EDTA permitted satisfactory outcomes in necrotic immature permanent teeth.

Prospective cohort study of regenerative potential of non vital immature permanent maxillary central incisors using platelet rich fibrin scaffold

Regenerative endodontic procedures have gained momentum as a treatment modality of young immature permanent teeth. Literature reports reveal that platelet-rich fibrin (PRF) stimulates growth factors and induces regeneration. This study was undertaken to assess the regenerative potential of non-vital immature permanent maxillary central incisors using PRF with a follow-up for 2 yrs. 19 patients in the age group of 9–25 yrs with immature, non-vital permanent maxillary central incisors (n = 23) with/without signs and/or symptoms of periapical pathosis and open apex were included in this study. In the first appointment, access opening, canal disinfection and triple antibiotic paste placement were done. In the subsequent visit, PRF was prepared and placed inside the canal. Access was sealed with Mineral trioxide aggregate plug and composite. The patient was reviewed up to 24 mths. The mean difference was statistically analyzed using Friedman test followed by Dunn post hoc test and adjusted by Bonferroni correction (p < 0.05). As per AAE guidelines, the primary and secondary goals were achieved. A significant (p < 0.001) gradual increase in the root length, thickness of dentinal walls and decrease in apical diameter were observed. Within the limitations of this study, PRF placement was clinically and radiographically effective in inducing regeneration of non-vital immature permanent teeth.

Antibacterial Effect and Bioactivity of Innovative and Currently Used Intracanal Medicaments in Regenerative Endodontics

INTRODUCTION

The purpose of this study was to determine the antibacterial effect and bioactivity of triple antibiotic paste (TAP), calcium hydroxide (Ca[OH]₂), and calcium hypochlorite (Ca[OCl]₂).

METHODS

Root canals were infected with 3-week-old Enterococcus faecalis biofilm and then medicated for 7 days with TAP, Ca(OH)₂, or Ca(OCl)₂ (n = 10/group). Untreated and uninfected canals were used as positive and negative controls. The antibacterial effect was determined using colony-forming units and a Live/Dead bacterial viability kit. Dental pulp stem cells were seeded on medicated dentin surfaces for 7 days. Sodium thiosulfate and various concentrations of ascorbic acid (1%, 5%, and 10%) were also used to neutralize the samples treated with Ca(OCl)₂ before cell seeding (n = 3 in triplicate). Cell viability and morphology were evaluated using a viability assay and Live/Dead cell analysis. Alkaline phosphatase (ALP) activity was also measured to determine the cells' mineralization activity.

RESULTS

All medicaments decreased the initial bacterial load (P < .05). The highest bacterial reduction in the main canal and dentinal tubules was observed in the Ca(OCl)₂ group (P < .05). TAP- or Ca(OH)₂-treated dentin surface improved cell viability and ALP activity compared with the untreated dentin surface (P < .05), whereas Ca(OCl)₂ decreased cell viability and ALP activity (P < .05). Ten percent ascorbic acid neutralized the effect of Ca(OCl)₂ on the treated dentin surface, showing higher cell viability (P < .05) and similar ALP activity with the untreated dentin surface and the other groups (P > .05).

CONCLUSIONS

Ca(OCl)₂ medication improved root canal disinfection against E. faecalis biofilm compared with TAP and Ca(OH)₂. The adverse effects caused by Ca(OCl)₂ on cell viability and mineralization activity can be neutralized with 10% ascorbic acid.

Regenerative Endodontic Therapy using a New Antibacterial Root Canal Cleanser in necrotic immature permanent teeth: Report of two cases treated in a single appointment

A case of regenerative endodontics: (a) before treatment; (b) post-treatment Xray; (c) follow-up at 6 months; (d) follow-up at 12 months.

Conceptual combination of disinfection in regenerative endodontics: Conventional versus laser-assisted disinfection

Background:

Successful regeneration depends on four key elements of tissue engineering such as stem cells, growth factors, scaffold and sterile environment. Therefore, regenerative endodontic therapy requires higher degree of disinfection for successful outcomes.

Aims and Objective:

To evaluate the clinical and radiographic outcome using conventional and laser assisted disinfection in regenerative endodontics at 1, 3 and 6 months.

Materials and Methods:

18 children with necrotic young permanent teeth were selected for the study. In Group A, in the first appointment AAE (American Association of Endodontics, Clinical Consideration for Regenerative Endodontic Procedure - 2016) disinfection protocol was employed. In Group B laser assisted disinfection (810 nm diode laser, 1 W, 20 ms Pulse length and 20 ms interval duration) was performed. Microbial samples were obtained before and after disinfection to check the level of disinfection. The cases were followed up at 1 month, 3 months and 6 months interval and evaluated for clinical outcome, periapical healing and apical response. Data were statistically analyzed with level of significance set 1% or 5% accordingly (P<0.01 or P<0.05)

Results:

On intragroup comparison there was significant reduction in bacterial count before and after disinfection with respect to laser assisted disinfection group. (P value = 0.007) There was no significant change in the clinical outcome score in laser group at 1,3- and 6-months interval. Periapical healing score showed statistically significant results in laser group when followed from 3 months to 6 months (P value = 0.04).

Conclusion:

Along with AAE 2016 protocol, use of laser assisted disinfection resulted in improved quality of disinfection and an expeditious clinical outcome and periapical healing in necrotic young permanent teeth. Keywords: Disinfection; laser; regenerative endodontics; sodium hypochlorite; tooth apex

Use of electromagnetic stimulation on an Enterococcus faecalis biofilm on root canal treated teeth in vitro

Root canal disinfection is of utmost importance in the success of the treatment, thus, a novel method for achieving root canal disinfection by electromagnetic waves, creating a synergistic reaction via electric and thermal energy, was created. To study electromagnetic stimulation (EMS) for the disinfection of root canal in vitro, single rooted teeth were instrumented with a 45.05 Wave One Gold reciprocating file. Specimens were sterilized and inoculated with Enterococcus faecalis ATCC 29,212, which grew for 15 days to form an established biofilm. Samples were treated with 6% sodium hypochlorite (NaOCl), 1.5% NaOCl 1.5% NaOCl with EMS, 0.9% saline with EMS or 0.9% saline. After treatments, the colony forming units (CFU) was determined. Data was analyzed by Wilcoxon Rank Sums Test (α = 0.05). One sample per group was scored and split for confocal laser scanning microscopy imaging. There was a significant effect with the use of NaOCl with or without EMS versus 0.9% saline with or without EMS (p = 0.012 and 0.003, respectively). CFUs were lower when using 0.9% saline with EMS versus 0.9% saline alone (p = 0.002). Confocal imaging confirmed CFU findings. EMS with saline has an antibiofilm effect against E. faecalis and can potentially be applied for endodontic disinfection.

Clinical and Radiographic Outcomes of Immature Teeth Treated with Different Treatment Protocols of Regenerative Endodontic Procedures: A Retrospective Cohort Study

Regenerative endodontic procedure (REP) is a progressive treatment modality for immature permanent teeth with necrotic pulp. The ambiguousness about the predictability of REP outcome in relation to complete disinfection of the root canal system and the occurrence of discoloration still exists. The aim of this retrospective study was to analyze two treatment protocols on clinical success rate, radiographic root development and the occurrence of discoloration. Eighteen patients were treated by a single operator by either treatment protocol according to the American Association of Endodontists (AAEP, n = 9) or a modified protocol (MP, n = 9) with the use of 5% sodium hypochlorite and sandblasting. Patients were followed up after 3, 6, 9, 12, 18 and 24 months and clinical success, radiographic root development and the occurrence of discoloration were assessed. The clinical success of MP was significantly higher in two years follow-up (p = 0.015), but the change in radiographic root area was higher for AAEP (p = 0.017) and the occurrence of discoloration was higher in AAEP (p = 0.029). The use of 5% sodium hypochlorite for a longer period of time leads to a higher success rate. The sandblasting of the access cavity reduces the occurrence of discoloration.

Effect of Optimized Irrigation With Photon-Induced Photoacoustic Streaming on Smear Layer Removal, Dentin Microhardness, Attachment Morphology, and Survival of the Stem Cells of Apical Papilla

BACKGROUND AND OBJECTIVES

This study aimed to evaluate the effect of optimized irrigation with photon-induced photoacoustic streaming (PIPS) activation of different irrigants (distilled water or ethylenediaminetetraacetic acid [EDTA]) on smear layer removal, dentin microhardness, attachment morphology, and survival of stem cells of the apical papilla (SCAP) in an organotypic root canal model.

STUDY DESIGN/MATERIALS AND METHODS

A total of 144 standardized root segments were randomly allocated into 6 groups for irrigation: (i) NaOCl group, (ii) NaOCl + EDTA group, (iii) NaOCl + PIPS (distilled water) group, (iv) NaOCl + PIPS (EDTA) group, (v) NaOCl + EDTA + PIPS (distilled water) group, and (vi) NaOCl + EDTA + PIPS (EDTA) group. Each group was divided into four subgroups for assessment: (i) dentin cleanliness; (ii) dentin microhardness; (iii) cell attachment morphology; and (iv) viable SCAP quantification.

RESULTS

Compared with the control groups, the NaOCl + EDTA + PIPS (EDTA) group showed higher efficiency in smear layer removal and in increasing SCAP viability with more stretched cellular morphology. There were no statistically significant differences in either smear layer removal effect, dentin microhardness, attachment morphology, or survival of SCAP among the other groups when optimized with PIPS (distilled water or EDTA) (P > 0.05).

CONCLUSIONS

Our findings indicated that irrigation optimized with PIPS activation of EDTA for 40 seconds was conducive to smear layer removal without additional dentin microhardness decrease. Additionally, this irrigation created more cell-friendly dentin conditioning than other approaches, which was beneficial for the attachment and survival of SCAP. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Isolation and Characterization of Buccal Fat Pad and Dental Pulp MSCs from the Same Donor

Mesenchymal stem cells (MSCs) can be harvested from different sites in the oral cavity, representing a reservoir of cells useful for regenerative purposes. As direct comparisons between at least two types of MSCs deriving from the same patient are surprisingly rare in scientific literature, we isolated and investigated the osteoinductive potential of dental pulp stem cells (DPSCs) and buccal fat pad stem cells (BFPSCs). MSCs were isolated from the third molar dental pulp and buccal fat pads of 12 patients. The number of viable cells was quantified through manual count. Proliferation and osteodifferentiation assays, flow cytometry analysis of cell phenotypes, and osteocalcin release in vitro were performed. The isolation of BFPSCs and DPSCs was successful in 7 out of 12 (58%) and 3 out of 12 (25%) of retrieved samples, respectively. The yield of cells expressing typical stem cell markers and the level of proliferation were higher in BFPSCs than in DPSCs. Both BFP-SCs and DPSCs differentiated into osteoblast-like cells and were able to release a mineralized matrix. The release of osteocalcin, albeit greater for BFPSCs, did not show any significant difference between BFPSCs and DPSCs. The yield of MSCs depends on their site of origin as well as on the protocol adopted for their isolation. Our data show that BFP is a valuable source for the derivation of MSCs that can be used for regenerative treatments.

Different Approaches to the Regeneration of Dental Tissues in Regenerative Endodontics

(1) Background: The regenerative procedure has established a new approach to root canal therapy, to preserve the vital pulp of the tooth. This present review aimed to describe and sum up the different approaches to regenerative endodontic treatment conducted in the last 10 years; (2) Methods: A literature search was performed in the PubMed and Cochrane Library electronic databases, supplemented by a manual search. The search strategy included the following terms: “regenerative endodontic protocol”, “regenerative endodontic treatment”, and “regenerative endodontics” combined with “pulp revascularization”. Only studies on humans, published in the last 10 years and written in English were included; (3) Results: Three hundred and eighty-six potentially significant articles were identified. After exclusion of duplicates, and meticulous analysis, 36 case reports were selected; (4) Conclusions: The pulp revascularization procedure may bring a favorable outcome, however, the prognosis of regenerative endodontics (RET) is unpredictable. Permanent immature teeth showed greater potential for positive outcomes after the regenerative procedure. Further controlled clinical studies are required to fully understand the process of the dentin–pulp complex regeneration, and the predictability of the procedure.

Effect of Natural and Artificial Dentin Conditioners on the Release of Vascular Endothelial Growth Factor

INTRODUCTION

The purpose of this study was to observe the release of vascular endothelial growth factor (VEGF) after conditioning with etidronic acid (also known as 1-hydroxyethylidene-1 and 1-bisphosphonate [HEDP]) and phytic acid (inositol hexakisphosphate [IP6]) in comparison with EDTA on human dentin disks and cylinders.

METHODS

Human dentin disks were disinfected and prepared by the standardized method. Seventeen percent EDTA, 9% HEDP, 1% IP6, and distilled water (5 minutes) were used to immerse dentin disks. The dentin cylinders were prepared by following disinfection and the standardized preparation method to achieve a truncated cone-shaped canal with a 1-mm open apex. The dentin cylinder samples were irrigated with sodium hypochlorite (5 mL/5 minutes) and then rinsed with 17% EDTA, 9% HEDP, 1% IP6 and distilled water (5 mL/5 min). Enzyme-linked immunosorbent essay was performed to measure VEGF release. One-way analysis of variance was used to compare the mean release of VEGF between study groups and controls at a significance level of .05. A post hoc Tukey test was used for multiple comparisons between study groups.

RESULTS

Among conditioners, HEDP released more VEGF from both disks and cylinders. In cylinders, VEGF release by HEDP was significantly greater than the other conditioners, whereas in disks the release of VEGF was similar with all conditioners.

CONCLUSIONS

The release of VEGF by 9% HEDP and 1% IP6 was comparable with 17% EDTA from dentin disks; however, HEDP demonstrated more release from dentin cylinders than EDTA and IP6.

What is the best long-term treatment modality for immature permanent teeth with pulp necrosis and apical periodontitis?

PURPOSE

To evaluate and assess the current knowledge about apexification and regenerative techniques as a meaningful treatment modality and to map the scientific evidence for the efficacy of both methods for the management of traumatised immature teeth with pulp necrosis and apical periodontitis.

METHODS

This systematic review searched five databases: PubMed, Web of Science, Cochrane Library, Ovid (Medline), and Embase. Published articles written in English were considered for inclusion. The following keywords were used: Regenerative endodontic treatment OR regenerat* OR revital* OR endodontic regeneration OR regenerative endodontics OR pulp revascularization OR revasculari* OR 'traumatized immature teeth'. Only peer-reviewed studies with a study size of at least 20 cases followed up for 24 months were included. Eligibility assessment was performed independently in a blinded manner by three reviewers and disagreements were resolved by consensus. Subgroup analyses were performed on three clinical outcomes: survival, success, and continued root development.

RESULTS

Seven full texts out of 1359 citations were included and conventional content analysis was performed. Most of the identified citations were case reports and case series.

CONCLUSIONS

In the present systematic review, the qualitative analysis revealed that both regenerative and apexification techniques had equal rates of success and survival and proved to be effective in the treatment of immature necrotic permanent teeth. Endodontic regenerative techniques appear to be superior to apexification techniques in terms of stimulation of root maturation, i.e. root wall thickening and root lengthening. Knowledge gaps were identified regarding the treatment and follow-up protocols for both techniques.

Effect of different irrigation protocols for applications in regenerative endodontics on mechanical properties of root dentin

The objective of this study was to evaluate the effect of different concentrations of NaOCl with and without passive ultrasonic irrigation (PUI) on mechanical properties of human dentin for applications in regenerative endodontics (RE). Sixty single-rooted teeth were sectioned into 2 halves (n = 120). Dentin bars were produced from one half for flexural strength and the other half was used for microhardness. Specimens were randomly assigned into 10 groups: G1 and G2 (control): distilled water for 30 and 60 min, respectively; G3: 1.5%NaOCl for 30 min; G4:1.5%NaOCl for 60 min; G5: 1.5%NaOCl + PUI for 30 min; G6: 1.5%NaOCl + PUI for 60 min; G7: 5.25%NaOCl for 30 min; G8: 5.25%NaOCl for 60 min; G9: 5.25%NaOCl + PUI for 30 min; G10: 5.25%NaOCl + PUI for 60 min. An increase in NaOCl concentration showed highly significant reduction in mechanical properties. There was no significant difference between 1.5% NaOCl and control group except for specimens treated with PUI for 60 min. NaOCl in concentrations recommended for RE did not have a significant effect on mechanical properties of dentin. However, PUI with increased irrigation time might have an effect even with low NaOCl concentration.

Regenerative Endodontic Procedures, Disinfectants and Outcomes: A Systematic Review

AIMS

This systematic review aims to identify and synthesise available evidence to determine the clinical and radiographic outcomes of REP involving any disinfection irrigant together with a non-antibiotic intracanal medicament.

METHODS

Experimental and observational studies evaluating the outcomes of REP in immature non-vital permanent teeth in 6-16 year olds, where the protocol used any type of disinfectant irrigant together with a non-antibiotic intracanal medicament (non-setting calcium hydroxide) were included. Data was narratively synthesised and presented in respect to the primary outcome (elimination of symptoms and infection) and secondary outcomes (increase in root length/width; positive response to vitality testing; patient-reported outcomes; adverse effects).

MAIN FINDINGS

1628 studies were identified, of which five met the eligibility criteria for inclusion in the review. Studies included one randomised control trial and four observational studies. All five studies showed an absence of clinical signs and symptoms for all teeth postoperatively with radiographic resolution or absence of pathology following the disinfection stages of the REP used. Choice of secondary outcomes were inconsistent but included further root development, coronal discolouration and root canal calcifications postoperatively. There was a high risk of bias in all five studies and subsequently the quality of the evidence base was judged to be low.

PRINCIPLE CONCLUSIONS

REP using a non-antibiotic disinfectant approach appears capable of providing satisfactory outcomes for a non-vital immature permanent tooth. Further high-quality research is required before solid recommendations towards clinical practice guidelines for the disinfection portion of REP can be implemented.

Advanced Biomaterials and Techniques for Oral Tissue Engineering and Regeneration-A Review

The reconstruction or repair of oral and maxillofacial functionalities and aesthetics is a priority for patients affected by tooth loss, congenital defects, trauma deformities, or various dental diseases. Therefore, in dental medicine, tissue reconstruction represents a major interest in oral and maxillofacial surgery, periodontics, orthodontics, endodontics, and even daily clinical practice. The current clinical approaches involve a vast array of techniques ranging from the traditional use of tissue grafts to the most innovative regenerative procedures, such as tissue engineering. In recent decades, a wide range of both artificial and natural biomaterials and scaffolds, genes, stem cells isolated from the mouth area (dental follicle, deciduous teeth, periodontal ligament, dental pulp, salivary glands, and adipose tissue), and various growth factors have been tested in tissue engineering approaches in dentistry, with many being proven successful. However, to fully eliminate the problems of traditional bone and tissue reconstruction in dentistry, continuous research is needed. Based on a recent literature review, this paper creates a picture of current innovative strategies applying dental stem cells for tissue regeneration in different dental fields and maxillofacial surgery, and offers detailed information regarding the available scientific data and practical applications.

Cytotoxic, migration, and angiogenic effects of intracanal irrigants on cells involved in revascularization of immature teeth

OBJECTIVE

To evaluate protocols of root canal irrigation and dentin pretreatment in a cell culture model simulating immature teeth. Cytotoxic, migration, and angiogenic effects of Sodium hypochlorite associated with EDTA (NaOCl/EDTA), NaOCl associated with Smear Clear (NaOCl/SC), and QMix were compared.

DESIGN

Three roots of mandibular first premolars had their length and root canal diameter standardized. Root canals were irrigated, and the resulting solutions were diluted in culture medium. Sulforhodamine B (SRB) assay was performed with apical papilla cells and with endothelial cells (HUVECs) to assess cytotoxicity. Polarity index and migration assays of apical papilla cells and sprouting of HUVECs were evaluated. Data were analyzed by ANOVA and Tukey post-hoc tests (p < .05).

RESULTS

In apical papilla cells, NaOCl/SC and QMix promoted higher cytotoxicity, decreased fraction of elongated cells, and had lower migration speed and shorter migration distance of cells compared to NaOCl/EDTA. Also, HUVECs treated with NaOCl/SC and QMix showed decreased tubule formation in comparison with NaOCl/EDTA.

CONCLUSIONS

NaOCl/SC and QMix showed unfavorable biological responses of cells involved in revascularization in comparison to NaOCl/EDTA. Further studies with other intracanal irrigants should be performed to improve the balance of root canal disinfection with biological responses.

Dentin-Pulp Tissue Regeneration Approaches in Dentistry: An Overview and Current Trends

Conventional treatment approaches in irreversible pulpitis and apical periodontitis include the disinfection of the pulp space followed by filling with various materials, which is commonly known as the root canal treatment. Disadvantages including the loss of tooth vitality and defense mechanism against carious lesions, susceptibility to fractures, discoloration and microleakage led to the development of regenerative therapies for the dentin pulp-complex. The goal of dentin-pulp tissue regeneration is to reestablish the physiological pulp function such as pulp sensibility, pulp repair capability by mineralization and pulp immunity. Recent dentin-pulp tissue regeneration approaches can be divided into cell homing and cell transplantation. Cell based approaches include a suitable scaffold for the delivery of potent stem cells with or without bioactive molecules into the root canal system while cell homing is based on the recruitment of host endogenous stem cells from the resident tissue including periapical region or dental pulp. This review discusses the recent treatment modalities in dentin-pulp tissue regeneration through tissue engineering and current challenges and trends in this field of research.

Cytotoxic, Migration, and Angiogenic Effects of Photodynamic Therapy and Photobiomodulation Associated with a Revascularization Protocol

INTRODUCTION

This study evaluated photodynamic therapy (PDT) and photobiomodulation therapy (PBM) as adjuncts to pulp revascularization using cultures of apical papilla cells (APCs) and endothelial cells (HUVECs).

METHODS

The root canal and apical foramen of 2 mandibular first premolars were enlarged to simulate immature teeth. The canal of 1 tooth was filled with 1 mL 0.005% methylene blue (MB). After that, the canals of both teeth were irrigated with 20 mL 1.5% sodium hypochlorite (NaOCl) and 20 mL 17% EDTA. The resulting solutions were diluted in cell culture media at a concentration of 0.5% (0.5% MB + NaOCl + EDTA and 0.5% NaOCl + EDTA). After PDT (0.5% MB + NaOCl + EDTA + PDT) and PBM (0.5% NaOCl + EDTA + PBM) applications, the effects were evaluated to determine cytotoxicity, polarity index, APC migration, and HUVEC sprouting, and results were compared with those of their controls (solutions without laser application). Cell culture media (CT) was also used as a control. Data were analyzed using 1-way analysis of variance and the Tukey post hoc test (P ≤ .05).

RESULTS

PDT and PBM promoted greater APC viability than their controls, and PDT had greater cell viability than CT (P < .05). All protocols reduced APC migration when compared with CT (P < .05). HUVEC sprouts grown out of spheroids in PBM had a greater ratio area than their control (P ≤ .01), and the PDT ratio of the spheroid area was similar to that of its control (P > .05).

CONCLUSIONS

PBM and PDT seem to be potentially effective adjuncts to revascularization in nonvital immature teeth.

Effectiveness of Autologous Platelet Concentrates in Management of Young Immature Necrotic Permanent Teeth-A Systematic Review and Meta-Analysis

The use of autologous platelet concentrates (APCs) in regenerative endodontic procedures is inconsistent and unclear. The aim of this meta-analysis was to evaluate the effectiveness of autologous platelet concentrates compared to traditional blood-clot regeneration for the management of young, immature, necrotic, permanent teeth. The digital databases MEDLINE, SCOPUS, CENTRAL, Web of Science, and EMBASE were searched to identify ten randomized clinical trials. The outcomes at postoperative follow-up, such as dentinal wall thickness (DWT), increase in root length (RL), calcific barrier formation (CB), apical closure (AC), vitality response (VR), and success rate (SR), were subjected to both qualitative synthesis and quantitative meta-analysis. The meta-analysis showed that APCs significantly improved apical closure (risk ratio (RR) = 1.17; 95% CI: 1.01, 1.37; p = 0.04) and response to vitality pulp tests (RR = 1.61; 95% CI: 1.03, 2.52; p = 0.04), whereas no significant effect was observed on root lengthening, dentin wall thickness, or success rate of immature, necrotic teeth treated with regenerative endodontics. APCs could be beneficial when treating young, immature, necrotic, permanent teeth regarding better apical closure and improved response to vitality tests.

The effect of electromagnetic fields on survival and proliferation rate of dental pulp stem cells

Aims: Extremely low-frequency electromagnetic fields (ELF-EMF) can affect biological systems and alter some cell functions like proliferation rate. Dental pulp tissue is known as a source of multipotent stromal stem cells (MSCs), which can be obtained by a less invasive and more available process compared to bone marrow-derived stem cells (BMSCs). This study aimed to consider the effect of ELF-EMF on proliferation rates of human dental pulp stem cells (hDPSCs).Material and methods: ELF-EMF was generated by a system including autotransformer, multi-meter, solenoid coils, teslameter and its probe. The effect of ELF-EMF with the intensity of 0.5 and 1 mT and 50 Hz on the proliferation rate of hDPSCs was assessed in 20 and 40 min per day for 7 days. MTT assay and DAPI test were used to determine the growth and proliferation of DPSCs.Results: Based on MTT, ELF-EMF has maximum effect with the intensity of 1 mT for 20 min/day on the proliferation of hDPSCs. The survival and proliferation rate in all exposure groups were significantly higher than the control group. Based on the data obtained from MTT and DAPI assay, the number of viable cells in the group exposed to 1 mT for 20 min/day was higher than other groups (p < .05).Conclusions: Regarding to the results of this study, 0.5 and 1 mT ELF-EMF can enhance survival and proliferation rates of hDPSCs.

Evaluation of the regenerative potential of dentin conditioning and naturally derived scaffold for necrotic immature permanent teeth in a dog model

This study evaluated the outcome of partial exposure of dentin matrix to ethylenediaminetetraacetic acid (EDTA) and application of platelet-rich fibrin (PRF) scaffold on regeneration of necrotic immature permanent teeth in a dog model. The present study was carried out on 216 permanent immature roots in nine mongrel dogs aged 6-9 months. Pulp necrosis and periapical pathosis were induced in 180 roots. These roots were divided into five equal groups (36 roots each) according to the treatment protocol: group I: blood clot; group II: 17% EDTA solution and blood clot; group III: PRF; group IV: 17% EDTA solution and PRF; and group V: without treatment (positive control). The negative control group (group VI) represented 36 untouched normal roots for normal maturation. The groups were followed up for 1, 2 and 3 months (subgroups). Maturation of the roots was monitored by radiography and histopathology. All data were statistically analysed. Group IV exhibited the highest increase in root length and thickness, decrease in apical diameter, the highest score of vital tissue infiltration and least inflammatory scores. There was a significant difference regarding the increase in root length and thickness and decrease in apical diameter in all subgroups of the experimental and negative control groups (P ≤ .05). PRF has a better regenerative potential than the blood clot during treatment of immature permanent teeth with necrotic pulp. Inclusion of 17% EDTA solution as a final irrigation enhances the regenerative potential of both PRF and blood clot.

Antibacterial efficacy and discolouration potential of antibiotic pastes with macrogol for regenerative endodontic therapy

This study aimed to evaluate the antibacterial efficacy and discolouration potential of antibiotic pastes containing macrogol. Seventy single-rooted teeth were contaminated with a culture of Enterococcus faecalis for 30 days. Double (DAP) and triple antibiotic pastes (TAP) containing propylene glycol or macrogol as vehicles were applied. After 15 days, bacterial viability was compared. Change in teeth coronal colour was measured by a spectrophotometer. Statistical analysis was performed using anova and Tukey's test (P < 0.05). TAP containing clindamycin and propylene glycol was the only medicament that led to the presence of contamination, while the same combination of antibiotics containing macrogol did not result in bacterial growth (P < 0.05). Only the pastes containing minocycline in formulation resulted in coronal discolouration (P < 0.05). Both DAPs evaluated and the TAP containing clindamycin and macrogol showed to be the preferable options for regenerative endodontic therapy, as they were effective against E. faecalis biofilm and did not promote tooth discolouration.

Regenerative Endodontics: A Paradigm Shift in Clinical Endodontics

Preserving the natural dentition in its normal form and function is one of the major goals of endodontic treatment. Re-establishing the lost vitality and development of root maturation in immature permanent teeth with pulp necrosis/apical periodontitis is quiet challenging clinically. The very basis of regenerative endodontics relies on the concept of tissue engineering using stem cells, biomimetic scaffold, and bioactive growth factors to regenerate the pulp tissue damaged by microbial infection, injury, or developmental defects. In clinical endodontics, this approach is referred to as a “paradigm shift.” Even though repair instead of true regeneration is achieved with current protocols, it is hoped that further research in the area of stem-cell-based tissue engineering will allow for true regeneration and improved treatment outcomes. The aim of this review is to discuss about the various aspects of regenerative endodontics, current clinical protocols, and the future of pulp regeneration techniques.

Effect of Gravity on Periapical Extrusion of Irrigating Solution With Different Irrigation Protocols in Immature Anterior Teeth

Objective:

Periapical extrusion is frequently observed during endodontic therapy. It can lead to acute injury of periapical tissues, resulting in interappointment pain or swelling. The effect is pronounced in teeth with immature teeth which are more susceptible to the extrusion of irrigant. The aim of this study was to evaluate the effect of gravity on apical extrusion of irrigating solution with different irrigation protocols in immature anterior teeth.

Methods:

An extracted maxillary central incisor was modified to simulate an open apex with an apical diameter of 1.3 mm and parallel canal walls. The tooth was subjected to a cone-beam computed tomographic scan, and the image data set was utilized to prepare 30 resin tooth models with a 3D printer. These resin teeth were used to form an open-ended Myers and Montgomery extrusion models. These were then randomly divided into two groups to simulate their orientation in the jaw during endodontic therapy, i.e., group I (maxillary arch, n=15) models fixed at 45° inclined plane and group II (mandibular arch, n=15) models placed at a plane parallel to the floor. Five models from each group (n=5) were tested by three different irrigation protocols: positive pressure (PP) Irrigation, passive ultrasonic irrigation (PUI), and negative pressure (NP) irrigation. The extruded irrigating solution was collected in glass vials, and the volume was measured.

Results:

The volume of extruded irrigating solution in groups I and II was compared using Mann–Whitney U-test. The median values for PP, PUI, and NP irrigation protocols were 0.6, 1, and 0 ml and 10, 10, and 0.5 ml for groups I and II, respectively. PP and PUI protocols were associated with significantly less extrusion in group I when compared to group II (P=0.004). There was no statistically significant difference in the volume of irrigating solution extruded in groups I and II (P=0.007) for NP irrigation protocol.

Conclusion:

Gravitation force has an influence on periapical extrusion of irrigant in immature permanent teeth irrespective of the irrigant system used. NP performed better when compared to PP or PUI irrigation protocol irrespective of the tooth orientation.

Effect of benzalkonium chloride addition to EDTA on attachment and proliferation of dental pulp stem cells on dentin and on transforming growth factor-β1 release

To investigate the effect of benzalkonium chloride (BAC) addition to ethylenediaminetetraacetic acid (EDTA) on transforming growth factor-β1 (TGF-β1) release, as well as attachment and proliferation of dental pulp stem cells (DPSCs) on dentin. A total of standard 268 human dentin disks were prepared and immersed in 1.5% sodium hypochlorite (NaOCl) for 5 min. The disks were rinsed with distilled water and randomly divided into seven groups. In control group, the disks received no further treatment. The remaining disks were immersed in following solutions: 17% EDTA or 17% EDTA + 0.008% BAC for 1, 5 or 10 min and rinsed with distilled water. DPSCs were seeded in part of the disks since the TGF-β1 release assay was performed with disks with and without cells. The attachment and proliferation of DPSCs on dentin disks were analyzed using lactate dehydrogenase activity and WST-1 assays, respectively. The cell morphology was observed by scanning electron microscopy. The release of TGF-β1 was quantified using ELISA. Data were analyzed using three- and two-way analysis of variance with Bonferroni corrections. Both EDTA solutions increased the attachment and proliferation of DPSCs (p < .05) while there was no significant difference between them (p > .05). The exposure time of both EDTA solutions had no influence on cell attachment, proliferation and TGF-β1 release (p > .05). There was no significant difference in TGF-β1 release between the control and experimental groups (p > .05). The amount of released TGF-β1 from dentin disks was similar whether or not they were seeded with cells (p > .05). Dentin treatment with either of the EDTA solutions had no effect on the amount of TGF-β1 release while both EDTA solutions improved cell attachment and proliferation on dentin surface regardless of exposure time.

Sodium Hypochlorite Reduces Postoperative Discomfort and Painful Early Failure after Carious Exposure and Direct Pulp Capping-Initial Findings of a Randomized Controlled Trial

In this randomized controlled single-center clinical trial on 96 adult patients with parallel experimental groups (n = 48), the effects of washing a dentin/pulp wound in non-symptomatic teeth with extremely deep caries and pulpal exposure were compared between a 2.5% sodium hypochlorite (NaOCl) solution and a chemically-inert physiological saline control solution. After the allocated wound lavage, the pulps were capped with a mineral trioxide aggregate, covered by a glass-ionomer/resin liner, and the teeth were immediately restored with a resin-bonded-composite. In this first report, the early events were analyzed: postoperative discomfort (on an NRS-11 scale) at day-3 and -7 after intervention, and the occurrence of unbearable pain causing patients to contact the principal investigator to perform a root canal treatment (pulpectomy) during the first three months. The NaOCl solution caused a highly significant reduction in post-operative discomfort (p = 0.0010 day 3; p = 0.0007 day 7) and early painful failures (p = 0.0008) compared with the control. These novel findings highlight the importance of infection control in teeth with extremely deep carious lesions. Based on these observations, the use of an NaOCl solution to wash the exposed dentin/pulp wound in the vital pulp treatment is highly recommended in order to reduce pain and early failure.

Biomimetic Aspects of Restorative Dentistry Biomaterials

Biomimetic has emerged as a multi-disciplinary science in several biomedical subjects in recent decades, including biomaterials and dentistry. In restorative dentistry, biomimetic approaches have been applied for a range of applications, such as restoring tooth defects using bioinspired peptides to achieve remineralization, bioactive and biomimetic biomaterials, and tissue engineering for regeneration. Advancements in the modern adhesive restorative materials, understanding of biomaterial-tissue interaction at the nano and microscale further enhanced the restorative materials' properties (such as color, morphology, and strength) to mimic natural teeth. In addition, the tissue-engineering approaches resulted in regeneration of lost or damaged dental tissues mimicking their natural counterpart. The aim of the present article is to review various biomimetic approaches used to replace lost or damaged dental tissues using restorative biomaterials and tissue-engineering techniques. In addition, tooth structure, and various biomimetic properties of dental restorative materials and tissue-engineering scaffold materials, are discussed.

Surface and structural changes in root dentine by various chelating solutions used in regenerative endodontics

AIM

To evaluate the effects of the prolonged use of various irrigant solutions used during regenerative endodontic procedures on the physical and chemical structure of root canal dentine in extracted human teeth.

METHODOLOGY

Sixtyroot dentine samples from extracted, single-rooted, human teeth were assigned to 10 groups. Eight groups were irrigated with 1.5% NaOCl for 5 min, followed by 3%, 10%, 17% EDTA or 10% citric acid (CA) for 5 or 10 min. One group received only NaOCl irrigation, and samples with only distilled water irrigation were used as a control group. The changes in microhardness and flexural strength were determined using Vickers and 3-point flexural tester, respectively. Molecular and elemental compositions were recorded using FTIR and EDS spectroscopy. Data were analysed using one-way anova, Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

The application of 1.5% NaOCl for 5 min did not affect the mineral content or microhardness of dentine (P > 0.05). However, it significantly decreased the dentine collagen peak values (P < 0.05), which was similar to the control group after the use of chelating agents (EDTA and 10% of CA) (P > 0.05). The effect of EDTA on the inorganic content was not concentration and time dependent (P > 0.05). CA resulted in a significantly greater reduction in the inorganic contents compared with the control and EDTA groups (P < 0.05). Regardless of the time, EDTA and CA significantly decreased dentine microhardness compared to the control (P < 0.05) with the greatest reduction in the CA groups (P < 0.05). NaOCl alone was associated with the lowest flexural strength, while none of the other irrigation regimens significantly decreased the flexural strength compared to the control group (P> 0.05).

CONCLUSIONS

Use of 1.5% NaOCl for 5 min decreased the collagen content of samples of human dentine from extracted teeth while EDTA and 10% citric acid mostly affected the inorganic content and microhardness of dentine surfaces. None of the irrigant solutions significantly decreased the mechanical properties of the entire dentine specimen.

Comparative evaluation of low-level laser therapy on proliferation of long-term cryopreserved human dental pulp cells isolated from deciduous and permanent teeth

The aim of the current study was to evaluate the proliferative effect of low-level laser therapy on long-term cryopreserved dental pulp stem cells (DPSC_S) and stem cells from human exfoliated deciduous teeth (SHED_S). The DPSC_S and SHED_S were divided into 2 main groups according to gallium aluminum arsenide (GaAIAs) diode laser irradiation densities as 5 J/cm² and 7 J/cm². Each main group was further divided into 4 groups according to laser irradiation periods as 0, 24, 48, 72 h groups. During the incubation periods, cells received laser irradiation in every 24 h according to their groups and were put into incubator after irradiation. Cell groups that were not subjected to laser irradiation were served as control groups. Viabilities of cells were determined via MTT assay at the end of all incubation periods, and data were statistically analyzed. Laser irradiation demonstrated significant effects on proliferation rate of DPSCs and SHEDs in comparison with control. Intragroup comparison data of DPSC_S revealed that repetitive laser irradiation for long term (72 h) increased the cellular viability significantly in comparison with all other treatment groups; however, no significant differences were found when energy densities were compared within each time interval, except for 48 h group at which irradiation with 7 J/cm² provided significantly higher cell viability rates of SHED_S. DPSCs showed significantly higher cellular viability than SHEDs only for the 7 J/cm² energy density in 72 h. Longer term (72 h) repetitive laser irradiation with energy densities of 5 and 7 J/cm² (wavelength of 980 nm) may be recommended to induce the proliferative effect on long-term cryopreserved DPSC_S and SHED_S.

The Effects of Intracanal Irrigants and Medicaments on Dental-Derived Stem Cells Fate in Regenerative Endodontics: An update

Regenerative endodontics is a biologically based treatment designed for immature permanent teeth with necrotic pulp to replace dentin and root structures, as well as dental pulp cells. This procedure has become a part of novel modality in endodontics therapeutic manner, and it is considered as an alternative to apexification. In the last decade, numerous case reports, which describe this procedure, have been published. This therapeutic approach succeeded due to its lower financial cost and ease of performance. Although the clinical protocol of this procedure is not standardized and the effects of irrigants and medicaments on dental stem cells fate remain somewhat ambiguous, however when successful, it is an improvement of endodontics treatment protocols which leads to continued root development, increased dentinal wall thickness, and apical closure of immature teeth. To ensure a successful regenerative procedure, it is essential to investigate the appropriate disinfection protocols and the use of biocompatible molecules in order to control the release of growth factors and the differentiation of stem cells. This is the first review in the literature to summarize the present knowledge regarding the effect of intracanal irrigants and medicaments on the dental derived stem cells fate in regenerative endodontic procedures.

The effect of platelet-rich plasma as a scaffold in regeneration/revitalization endodontics of immature permanent teeth assessed using 2-dimensional radiographs and cone beam computed tomography: a randomized controlled trial

AIM

To assess the outcomes of platelet-rich plasma as a scaffold in regenerative/revitalization endodontics (RET) using cone beam computed tomography (CBCT) and 2-dimensional radiographs.

METHODOLOGY

Twenty-six healthy patients with mean age of 12.66 ± 4.47, and immature permanent anterior teeth with necrotic pulps, were randomly allocated to two groups, whereby RET was performed using platelet-rich plasma (PRP, test group) and blood clot (BLC, control group). Changes in root length (RL), root dentinal thickness (RDT), apical foramen width (AFW) and radiographic root area (RRA), were assessed using both radiographic methods, whilst changes in periapical area diameter (PAD) were assessed using CBCT, over a period of 12 months. T-test and chi-square/Fisher's exact tests were used to compare continuous and categorical data between BLC and PRP groups, respectively. Changes in RL, RDT, AFW, RRA and PAD were examined by comparing the two groups (PRP versus BLC) using multilevel modelling, considering the clustering effect of repeated measures of several teeth originating from the same participant.

RESULTS

Changes in RL, RDT, AFW, RRA and PAD, over time, were found to be significant for both groups. There was, however, no difference between the RET techniques (PRP versus BLC), using both radiographic and CBCT methods. The results of both assessment techniques (CBCT and 2-dimensional radiographic methods) were highly consistent (overall ICC ranged between 0.80 and 0.94). In addition, a significant effect of baseline PAD was found on RL, RRA and AD at 12 months (RL effect = -0.68, P < 0.001; RRA effect = -1.91, P = 0.025; AD effect = 0.08, P = 0.024).

CONCLUSION

The current study highlights successful and comparable clinical and radiographic outcomes of RET techniques using PRP and BLC. Standardized and calibrated 2-dimensional radiographic assessment was as effective as CBCT in assessing RET outcomes; therefore, the routine use of CBCT in RET is not recommended. Although an effect of baseline periapical lesion diameter on root development outcomes, at 12 months, were observed, more studies are recommended in order to assess such an effect.

Potential for residual contamination by Streptococcus equi subspp equi of endoscopes and twitches used in diagnosis of carriers of strangles

BACKGROUND

Endoscopic examinations are essential for diagnosis and treatment of strangles (S equi infection) in horses. However, even after disinfection, endoscopes may retain viable bacteria or bacterial DNA. Twitches are commonly used during endoscopic examinations and can thus also potentially transmit the organism to other horses.

OBJECTIVES

To evaluate the efficacy of different disinfectant methods to eliminate S equi from experimentally contaminated endoscopes and twitches and the effectiveness of field disinfection of endoscopes used in sampling carriers of S equi.

STUDY DESIGN

Experimental contamination and observational field study.

METHODS

One endoscope and 30 twitches were contaminated with standardised S equi broth solutions. The endoscope was disinfected following three protocols using various disinfectants for manual disinfection. A fourth protocol used an automated endoscope reprocessor (AER). The twitches (n = 30) were disinfected following eight different disinfecting protocols. Three endoscopes used in sampling for silent carriers were disinfected following a field-based protocol. After each protocol the endoscopes and twitches were sampled for S equi by culture and qPCR.

RESULTS

Following experimental contamination all endoscope disinfection protocols, apart from 1/6 of the ethanol protocol were S equi culture negative. However, no endoscope disinfection protocol completely eliminated retention of S equi DNA. Field disinfection of endoscopes after sampling carriers yielded no culture positives and all but one (13/14) were qPCR negative. All twitches disinfected following experimental contamination were culture negative but sodium hypochlorite was the only disinfectant that completely eliminated detection of S equi DNA.

MAIN LIMITATIONS

Experimental contamination may not reflect the numbers of S equi transferred to endoscopes or twitches during use on silent carriers and purulent secretions from infected horses may influence survival of S equi.

CONCLUSIONS

While most disinfection methods appear to ensure removal of cultivable S equi, residual DNA can remain on both endoscopes and twitches.

Hand-held bioprinting for de novo vascular formation applicable to dental pulp regeneration

Aim of the study: Deep carious lesions may cause irreversible pulpitis and the current endodontic treatment typically removes the whole dental pulp tissue, which finally reduces lifespan of the teeth. Nowadays, the most frequent treatment is based on removing the infected tissue and filling the root canal with inert synthetic materials. Tissue engineering approaches are important alternatives to the current treatment, because they can potentially maintain the biological function of the tooth instead of sacrificing it.Materials and Methods: In this study, we propose a tissue engineering approach based on a hand-held in situ bioprinting strategy. Our approach enabled bioprinting of cell-loaded collagen-based bioinks with suitable rheological, structural and biological properties, which allowed for vasculogenesis in the root canal.Results: The rheological properties of the bioprintable bioink were measured by oscillatory amplitude sweep testing and were corroborated by macroscopic evaluation after in vitro culture, in which printed bioinks maintained their original form without contraction. Moreover, we showed evidence for successful vasculogenesis in bioprintable bioinks with comparable quality and quantity to control fibrin and collagen non-bioprintable hydrogels.Conclusions: We conclude that hand-held bioprinting holds potential for in situ treatment of dental diseases with successful evidence for vascular tube formation, as an asset for maintenance of the biological function of the tooth.