Healing after regenerative procedures with and without pulpal infection

Success Rate of Single Versus Two-Visit Regenerative Treatment Protocol in Non-Vital Mature Anterior Teeth (A Preliminary Randomised Clinical Trial)

This study compared the success rate following single-visit versus two-visit regenerative endodontic procedures of non-vital mature anterior teeth with periapical lesion. Thirty-two patients were randomly assigned into two groups: group A: single visit and group B: two visit. All assigned teeth were chemo-mechanically prepared. For group A, platelet rich fibrin was placed into the root canal followed by the placement of Biodentine and final restoration. For group B, calcium hydroxide was placed for 3 weeks, followed by the same regenerative procedures in the second visit. Follow-up visits were at 3, 6, 9 and 12 months, and periapical lesion was assessed by CBCT at the beginning and 12 months after treatment. There was no statistical difference between the success rate of group A (28.6%) and group B (64.3%). Regenerative endodontic procedure can be a promising treatment for mature non-vital teeth with further investigations needed for the single-visit protocol. Trial Registration: Registered at www.clinicaltrials.com NCT03717337.

Biological and mechanical challenges in the endodontic treatment of immature teeth with pulp necrosis: insights based on a Series of Atypical Clinical Cases

Over the past two decades, dental pulp regeneration has become a major focus in endodontology. The currently applied clinical strategies are referred to as 'revitalisation' procedures. These biology-based treatment strategies aim at regenerating lost pulp tissues in necrotic teeth, in the absence or even more in the presence of periapical bone lesion, clinical signs and symptoms. Such approaches are generally - but not exclusively - used in immature teeth to promote root maturation, both in length and in thickness, ultimately to reduce their risk of fracture. A growing body of evidence has led to increased understanding and reliability of these treatment strategies, which are now considered as a valid alternative treatment option besides conventional ones, mainly the apical plug technique. However, all systematic reviews evaluating clinical outcomes concluded that there is a lack of robust long-term studies on the subject; most published cases of revitalisation having a relatively short-term follow-up, usually under 2 years. In this context, several major challenges remain to be addressed to better understand the promises and limitations of revitalisation procedures as compared to other treatment options, mainly the placement of an apical plug made of hydraulic calcium silicate cement. The purpose of this paper was therefore to identify some of the important remaining challenges related to such procedures, which can be broadly categorised into biological and mechanical ones, affecting treatment success and tooth survival. Meeting these challenges requires close collaboration between both researchers and clinicians, to establish guidelines, evaluate and understand treatment outcomes, and update guidelines accordingly. However, it is not always easy for researchers to understand the clinical reality faced by practitioners. In order to facilitate their mutual understanding, the aforementioned challenges were illustrated by providing clinical context through a series of atypical clinical cases with long-term follow-up (4-8 years).

Comparative Evaluation of the Effects of Calcium Hydroxide Intracanal Medicament and Antibiotic Paste on Dentin Microhardness: A Systematic Review

An infectious environment is reported to hinder the process of pulp tissue regeneration by damaging the cells responsible for tissue formation, including stem cells in the periapical tissues. Therefore, a sterile environment is critical for pulp tissue regeneration, which can be achieved by copious irrigation and intracanal medicament (ICM) placement. This systematic review compares the effect of calcium hydroxide (Ca(OH)2) and various antibiotic pastes, such as triple antibiotic paste (TAP), modified triple antibiotic paste (MTAP), and double antibiotic paste (DAP), on dentin microhardness when used as ICMs. MeSH terms and specific keywords were used to search Scopus, EBSCOhost, Cochrane Library, and PubMed. In vitro studies that compared the impact of Ca(OH)2 and antibiotic pastes, such as TAP, MTAP, and DAP, on dentin microhardness were included. Data from the included articles were extracted, and their quality was assessed using the revised Quality Assessment Tool for In Vitro Studies (QUIN) tool. Seven articles were included for the qualitative synthesis, and data were extracted from each. Within the scope of this systematic review, Ca(OH)2, an alternative ICM recommended by the American Association of Endodontics Glossary of Endodontic Terms for REPs, showed a lesser reduction in microhardness than TAP. DAP and MTAP caused a reduction in dentin microhardness compared to that of Ca(OH)2.

Regenerative Treatment of Mature Teeth with Pulp Necrosis and Apical Periodontitis Using Biodentine Compared with MTA: Randomized Controlled Clinical Trial

OBJECTIVE

The purpose of this randomized, controlled study was to evaluate the effectiveness of Biodentine compared with MTA used as a pulp space barrier in healing periapical lesions and regaining pulp sensitivity after regenerative treatment in mature single-canal permanent teeth with pulp necrosis and apical periodontitis.

METHODS

The study involved 36 patients with mature teeth with necrotic pulp and apical periodontitis. The patient underwent a regenerative treatment that utilized the blood clot technique. Teeth were randomly allocated to either the intervention, Biodentine, group (n=18) or the control, MTA, group (n=18). The healing of periapical lesions and tooth sensibility were evaluated throughout follow-up visits for up to 18 months.

RESULTS

The study analyzed 31 patients; two patients within the biodentine group and three in the MTA group were lost to follow-up. After 18 months, both groups showed effective healing of periradicular lesions; 21 out of 31 patients (67.7%) were healed, ten patients (32.3%) were healing, and no failure cases occurred. There were no significant differences between the groups (p=1.00). More than 70% (22 out of 31 patients) regained their sensibility in their teeth, and the groups had no statistically significant difference (p=0.703).

CONCLUSION

Regenerative treatment using blood clots with either MTA or Biodentine effectively resolved periapical lesions and regained the sensibility of mature teeth.

Effect of Novel and Traditional Intracanal Medicaments on Biofilm Viability and Composition

INTRODUCTION

The aim of this study was to test the hypothesis that a combination of D-amino acids (DAAs) and trans-cinnamaldehyde (TC) demonstrates superior antibiofilm activity to calcium hydroxide (CH) and untreated controls.

METHODS

In this 3-part in vitro study, the concentration of DAAs (D-methionine, D-leucine, D-tyrosine, and D-tryptophan) that would significantly decrease Enterococcus faecalis and Actinomyces naeslundii biofilm biomass was first determined. Then, the effect of TC + selected DAAs on polymicrobial biofilms was characterized by quantifying the biomass and biofilm viability. Finally, the antibiofilm effects of TC + DAA was compared with CH and untreated controls by (i) determining bacterial viability and (ii) quantifying biofilm matrix composition using selective fluorescence-binding analysis. Statistical analysis was performed using one-way ANOVA and appropriate multiple comparisons test, with P < .05 considered as statistically significant.

RESULTS

TC (0.06%) + D-tyrosine (1 mM) + D-tryptophan (25 mM) significantly reduced the biomass and biofilm viability compared to the control (P < .05). While no significant difference was observed between TC + DAA and CH in the cultivable bacterial counts (P > .05), confocal microscopy demonstrated a significantly greater percentage of dead bacteria in TC + DAA-treated biofilms compared to CH and the control (P < .05). TC + DAA significantly decreased the biovolume and all the examined components of the biofilm matrix quantity compared to the control, while CH significantly reduced only the exopolysaccharide quantity (P < .05).

CONCLUSION

The combination of TC + D-tyrosine + D-tryptophan demonstrated superior antibiofilm activity (biofilm bacterial killing and reduction of matrix quantity) to CH and has potential to be developed as an intracanal medicament.

A Potential Intracanal Medicament, 2-Hydroxyisocaproic Acid (HICA): Cytotoxicity, Genotoxicity, and Its Effect on SCAP Differentiation

Intracanal medicaments with maximal antimicrobial efficacy and minimal damage to resident stem cells are essential for successful regenerative endodontic procedures. 2-Hydroxyisocaproic acid (HICA) could have the attributes of a potential intracanal medicament. This study evaluates its cytotoxicity, genotoxicity, and effects on the odontogenic and osteogenic differentiation of the stem cells of the apical papilla (SCAP). Cytotoxicity and cell viability assays were performed on cells treated for 24, 48, and 72 h with varying concentrations of HICA and compared to the standard intracanal medicament, calcium hydroxide. The genotoxicity was assessed via immunofluorescence for two markers of DNA double-strand breaks: phosphorylated γH2AX and 53BP1. The SCAP differentiation was evaluated based on the alkaline phosphatase activity, Alizarin Red staining, and expression of odontogenic and osteogenic genes (DSPP1, BSP1, OCN, RUNX2) in the presence of selected HICA concentrations. HICA was not cytotoxic at concentrations up to 10 mg/mL, regardless of the exposure time, although it was cytostatic at all tested concentrations. HICA was not genotoxic at concentrations below 5 mg/mL. No difference in cytotoxicity or genotoxicity was found between HICA and calcium hydroxide at 1 mg/mL. HICA retained about 70% of the osteogenic differentiation potential at 1 mg/mL. Within the limitations of this in vitro study, we show that HICA at 1 mg/mL could be a potential intracanal medicament for REPs.

Assessing the Contact Angle Between Dentin Treated With Irrigation and Calcium Hydroxide and Root Canal Sealers

Background

The long-term use of calcium hydroxide, or Ca(OH)2, on dentin has been established in the literature. However, scarce data is available on dentin wettability with Ca(OH)2.

Aim

The present study was conducted to assess the outcomes of Ca(OH)2 use on the wettability of dentin following two and four weeks of using sealers of bioceramic (BC) and Tubli-Seal™ in the root canal.

Methods

In this study, 168 specimens were divided into 12 groups of 14 specimens each and were numbered from G1 to G12. G1-G6 groups were tested with Tubli-Seal. Sterile water irrigation was reserved for G1 for two weeks (14 days) followed by two minutes treatment with 6% sodium hypochlorite (NaOCl) chemical irrigation and 17% EDTA (10 ml). G2 and G3 were subjected to Ca(OH)2 (0.1 ml of UltraCal) for two weeks followed by 10ml sterile water irrigation for two minutes with chemical irrigation. G4 to G6 were given similar treatment for four weeks. G7-G12 were assessed for BC sealer similarly to G1-G6. Two and four weeks of incubation with sterile water or Ca(OH)2 was done in 100% humidity at 37°C. SEM and EDX were done to evaluate the surface morphology of G1 and G6, and results were formed. 

Results

Significantly smaller contact angles were seen for Tubli-Seal (G1 to G6) compared to BC (G7 to G12) with p<0.05. Application of water irrigants and Ca(OH)2 (in G2, G5, and G11) showed a smaller (p<0.05, statistically significant) contact angle compared to the use of chemical irrigation agents and Ca(OH)2 (in G3, G6, and G12) except for G8 and G9. Based on EDX and SEM, compared to the use of chemical irrigation with Ca(OH)2, higher remnants of Ca(OH)2 were seen in the water irrigation, whereas, no remnant was seen with chemical irrigants. 

Conclusion

Better dentin wettability is seen with Tubli-seal compared to BC sealer. A smaller contact angle between root canal sealers and dentin is seen in the remaining calcium hydroxide samples. Also, calcium hydroxide can be removed from the polished dentin surface with two minutes of irrigation with 17% EDTA and 6% NaOCl.

Effect of hydrogel-based antibiotic intracanal medicaments on crown discoloration

Objectives

This study evaluated the effects of low and moderate concentrations of triple antibiotic paste (TAP) and double antibiotic paste (DAP) loaded into a hydrogel system on crown discoloration and explored whether application of an adhesive bonding agent prevented crown discoloration.

Materials and Methods

Intact human molars (n = 160) were horizontally sectioned 1 mm apical to the cementoenamel junction. The crowns were randomized into 8 experimental groups (calcium hydroxide, Ca[OH]₂; 1, 10, and 1,000 mg/mL TAP and DAP; and no medicament. The pulp chambers in half of the samples were coated with an adhesive bonding agent before receiving the intracanal medicament. Color changes (ΔE) were detected by spectrophotometry after 1 day, 1 week, and 4 weeks, and after 5,000 thermal cycles, with ΔE = 3.7 as a perceptible threshold. The 1-sample t-test was used to determine the significance of color changes relative to 3.7. Analysis of variance was used to evaluate the effects of treatment, adhesive, and time on color change, and the level of significance was p < 0.05.

Results

Ca(OH)₂ and 1 and 10 mg/mL DAP did not cause clinically perceivable tooth discoloration. Adhesive agent use significantly decreased tooth discoloration in the 1,000 mg/mL TAP group up to 4 weeks. However, adhesive use did not significantly improve coronal discoloration after thermocycling when 1,000 mg/mL TAP was used.

Conclusions

Ca(OH)₂ and 1 and 10 mg/mL DAP showed no clinical discoloration. Using an adhesive significantly improved coronal discoloration up to 4 weeks with 1,000 mg/mL TAP.

Antibacterial and Antifungal Efficacy of Platelet-Rich Fibrin and Platelet-Rich Fibrin Matrix against Root Canal Microflora

Background:

Binding of such proteins with a developing fibrin mesh or to the extracellular matrix has the ability to create chemotactic gradients aiding the recruitment of stem cells, thereby, stimulating cell migration and differentiation this may promotes repair and regeneration. There is a unique concept in platelet concentrates called platelet-rich fibrin matrix (PRFM) which is processed using higher attraction without the utilization of bovine thrombin.

Aim and Objectives:

The aim of this study is to evaluate the antibacterial and antifungal effects of platelet-rich fibrin (PRF) and PRFM against root canal microflora.

Materials and Methods:

Blood samples were taken from 20 adults, age ranging from 20 to 40 years who were systemically healthy, nonsmokers with no symptoms of infection, or on antibiotics at least 3 months before experiments. The procedures and the protocols involved in the study were accepted by the Institutional Ethical Committee. Written informed consent was obtained from the donors and patients. Approximately 10 ml of blood was collected from each donor. 5 ml of blood was used for the preparation of PRF and 5 ml for PRFM.

Results:

The antifungal scores among the groups. The highest antifungal scores were seen in metapex followed by PRF and PRFM group. Kruskal–Wallis test was applied to check the statistical difference among the groups, and there was a statistically significant difference seen among the groups (P = 0.00). The antibacterial scores among the groups. The highest antibacterial scores were seen in Metapex followed by PRF group and PRFM group Kruskal–Wallis test was applied to check the statistical difference among the groups, and there was a statistically significant difference seen among the groups.

Conclusion:

PRF demonstrated antibacterial activity against passage isolates but had no antifungal efficacy. This antibacterial property may be a valuable adjunct when using PRF for regenerative procedures in endodontics. Both PRF and PRFM have to be analyzed for antimicrobial properties for extended duration and various other clinical strains with larger sample size.

Study of antibacterial and antifungal efficacy of platelet-rich fibrin and platelet-rich fibrin matrix

Background:

Platelet concentrates are extensively utilized in the medical and dental field to promote tissue regeneration. The profusion of endogenous growth factors in platelets α-granules transmit their use for enhanced wound healing. However, little attention has been given to study their antimicrobial potential. This study was conducted to assess the antibacterial and antifungal property of platelet-rich fibrin (PRF) and PRF matrix (PRFM).

Materials and Methodology:

Blood samples were obtained from 16 participants, PRF and PRFM were processed as per the protocol prescribed by Choukroun et al. and Lucarelli et al., respectively. The susceptibility test against microbiota in the root canal and Candida albicans was assessed through minimum inhibition zone by agar diffusion technique.

Results:

PRF showed an effective antibacterial property, however, did not perform well against C. albicans strains. PRFM did not show any antibacterial or antifungal properties.

Conclusions:

The antibacterial efficacy of PRF may prove beneficial when used in the revascularization procedure of immature necrotic teeth.

Influence of Tooth Pigmentation on H2O2 Diffusion and Its Cytotoxicity After In-office Tooth Bleaching

Clinical Relevance

Pigments in tooth structures affect the diffusion of H2O2 through enamel and dentin. The bleaching methodology can be impacted.

SUMMARY

Objective: The aim of this study was to evaluate the influence of the presence of pigments in tooth structures on the trans-enamel and trans-dentin diffusion of hydrogen peroxide (H2O2) and its cytotoxicity after carrying out an in-office bleaching therapy.

Methods and Materials: A bleaching gel with 35% H2O2 was applied for 45 minutes (three times for 15 minutes) on enamel and dentin discs (n=6), either previously submitted to the intrinsic pigmentation protocol with a concentrated solution of black tea, or not, defining the following groups: G1, unbleached untreated discs (control 1); G2, unbleached pigmented discs (control 2); G3, bleached untreated discs; G4, bleached pigmented discs. The discs were adapted to artificial pulp chambers, which were placed in wells of 24-well plates containing 1 mL culture medium (Dulbecco’s modified Eagle’s medium [DMEM]). After applying the bleaching gel on enamel, the extracts (DMEM + components of bleaching gel that diffused through the discs) were collected and then applied on the cultured MDPC-23 odontoblast-like cells. Cell viability (methyl tetrazolium assay and Live & Dead, Calcein AM, and ethidium homodimer-1 [EthD-1] probes), the amount of H2O2 that diffused through enamel and dentin (leuco-crystal violet product), and the H2O2-mediated oxidative cell stress (SOx) and components of degradation were assessed (analysis of variance/Tukey; α=0.05).

Results: There was no significant difference between the groups G1 and G2 for all the parameters tested (p&gt;0.05). Reduction in the trans-enamel and trans-dentin diffusion of H2O2 occurred for G4 in comparison with G3. Significantly lower cell viability associated with greater oxidative stress was observed for G3 (p&lt;0.05). Therefore, in-office tooth bleaching therapy performed in pigmented samples caused lower cytotoxic effects compared with untreated samples submitted to the same esthetic procedure (p&lt;0.05).

Conclusion: According to the methodology used in this investigation, the authors concluded that the presence of pigments in hard tooth structures decreases the trans-enamel and trans-dentin diffusion of H2O2 and the toxicity to pulp cells of an in-office bleaching gel with 35% H2O2.

Observation of an extracted premolar 2.5 years after mineral trioxide aggregate apexification using micro-computed tomography

Although numerous studies have been conducted on apexification using mineral trioxide aggregate (MTA), direct observation of extracted human teeth after the procedure has been rarely reported. This case report describes a mandibular premolar treated 2.5 years ago and extracted recently for orthodontic treatment. The tubercle of the right mandibular premolar of a 12-year-old boy with dens evaginatus was fractured and the pulp was exposed. The tooth was diagnosed with pulp necrosis and asymptomatic periapical abscess. During the first visit, copious irrigation was performed with 2.5% sodium hypochlorite. Calcium hydroxide paste was placed as an intracanal medicament. The sinus tract had disappeared at the second visit after 3 weeks. MTA was applied on to the bleeding point as a 4-mm-thick layer, followed by a 3-mm-thick gutta-percha filling and resin core build-up. After 2.5 years, the tooth and three other premolars were extracted for orthodontic treatment. The right and left mandibular premolars were scanned with micro-computed tomography to determine the root shape and canal anatomy. Irregular root growth was observed and the root outline of the right mandibular premolar differed from that of the contralateral tooth. Apexification with MTA leads to the formation of roots with irregular morphology, without any pulpal space.

Evaluation of the Bactericidal Activity of a Hyaluronic Acid-Vehicled Clarithromycin Antibiotic Mixture by Confocal Laser Scanning Microscopy

Confocal laser scanning microscopy (CLSM) was used to evaluate the antibacterial effect and depth of action of a novel clarithromycin-containing triple antibiotic mixture, which was proposed for root canal disinfection in dental pulp regeneration. A previous study reported that this mixture had no tooth discoloration effects in vitro. After infection with Enterococcus faecalis for 3 weeks, the dentinal tubules in the cylindrical root specimens were exposed to different antibiotic mixtures: ciprofloxacin, metronidazole and minocycline (3-MIX); ciprofloxacin, metronidazole and clarithromycin (3-MIXC) and ciprofloxacin and metronidazole (2-MIX). Each antibiotic formulation was mixed with macrogol (MG) or hyaluronic acid (HA) vehicles. CLSM and viability staining were used to quantitatively analyze the mean depth of the antibacterial effect and the proportions of dead and live bacteria inside the dentinal tubules. The 3-MIX and 3-MIXC demonstrated a similar depth of action. The mean proportion of dead bacteria was similar in the 3-MIX and 3-MIXC groups, and both were statistically higher than that of 2-MIX (p = 0.014). Each antibiotic mixture showed a higher bactericidal efficacy if conveyed with HA, compared to MG (3-MIX, p = 0.019; 3-MIXC, p = 0.013 and 2-MIX, p = 0.0125). The depth of action and the antibacterial efficacy of 3-MIXC seemed comparable with 3-MIX.

Autologous platelet-rich-fibrin-induced revascularization sequelae: Two case reports

BACKGROUND

A key requirement for biomimetic regeneration of tissues is a 3D scaffold. The gold standard scaffold for revascularization is the blood clot, however, an adequate blood clot cannot always be achieved in narrow canals or mature roots. Hereby, we document the effects of platelet-rich fibrin (PRF) for the regenerative endodontic treatment (RET) of two immature permanent teeth with necrotic pulps for up to 48 mo.

CASES SUMMARY

The first patient was a 22-year-old female with history of trauma in tooth #9 with a sinus tract and a large periapical lesion. The second was a 9-year-old male presenting with a badly decayed tooth #14. Both cases were treated with RET and PRF prepared from the patients’ blood. PRF and its extract were used as a scaffold for RET. Patients were followed-up to 9 and 48 mo (4 years), respectively. Both patients, were asymptomatic after treatment. At the 9-mo-follow-up of case #1, there was radiographic evidence of periapical bone healing, however, the root apex was still open. In case #2, the roots exhibited apical closure and normal periapical bone architecture at 12-mo follow-up, while no root lengthening was observed. After 48 mo, case #2 showed extensive intracanal calcification in all root canals that complicated conventional root canal treatment.

CONCLUSION

RET with PRF and its extract could be used in revascularization of immature permanent teeth. However, proper case selection to comply with long-term follow-up is necessary and adverse events such as calcification and canal obliteration should be planned for.

Autologous transplantation of deciduous tooth pulp into necrotic young permanent teeth for pulp regeneration in a dog model

Objectives

To investigate the potential for pulpal regeneration via autologous transplantation of deciduous tooth pulp into immature necrotic permanent teeth using an experimental dog model.

Methods

Experimental apical periodontitis was induced in 60 teeth of six Beagle dogs. Following canal disinfection and pulpotomy, autologous deciduous pulp tissue was transplanted into the root canals (n = 30); as controls, contralateral teeth were treated in accordance with the recommendations of the American Association of Endodontists. Radiographic examinations were performed immediately before transplant, as well as 3 and 6 months after transplant. At the 6-month examination, root samples were collected and histological and immunohistochemical analyses were used to examine tissue regeneration.

Results

Radiographic analysis showed no significant differences in most histopathological parameters examined; however, apical diameter reduction was greater in the experimental group. Histological and immunohistochemical analyses showed that the canal walls of the experimental group had newly formed dentin-like tissue with dentinal tubules, while the control group had cementum-like deposits along the canal wall and apical foramina.

Conclusions

Autologous transplantation may be useful for regeneration of dental pulp in necrotic young permanent teeth.

Clinical Evidence for Regenerative Endodontic Procedures: Immediate versus Delayed Induction?

Clinicians face many challenges when treating immature permanent teeth in young patients. Immediate blood clot induction can be a successful option as described by some case reports. No experimental studies or clinical trials have addressed this question. We have designed a clinical trial in which we hypothesized that there is no difference in success between immediate or delayed induction protocols. After confirmation of pulpal necrosis, patients were randomized. In the delayed group, 15 teeth were treated following the American Association of Endodontists guidelines, and calcium hydroxide was used as the intracanal medication. In the immediate group, 13 teeth had a blood clot inducted at the first appointment. The teeth were evaluated after 1, 3, and 12 months. Three independent evaluators assessed the periapical healing. The Pearson chi-square test or the Fisher exact test was used to compare the success rates between the 2 groups. Currently, of the 25 recruited patients (28 teeth), 19 have completed their 12-month follow-up. The group with delayed induction had a 71% success rate, and the group with immediate induction had a 33% success rate. In most cases (79%), trauma was the etiology. All successful cases started at stage 9 of root development (Nolla), and the majority showed healing type 2. Determination of the stage of root formation and etiology are possible critical factors for any therapeutic decision. In summary, it is early to conclude or suggest any of the protocols. Clearly, much more data are needed before sample size requirements can be met.

Direct and indirect antibacterial effects of various concentrations of triple antibiotic pastes loaded in a methylcellulose system

We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin blocks (n = 60) and treated with clinically used TAP (1,000 mg/mL), low concentrations of methylcellulose-based TAP (100, 10, and 1 mg/mL), placebo paste, or 1.5% NaOCl (n = 10). The pastes were then removed, and biofilm disruption assays were performed. Additional dentin blocks (n = 120) were pretreated with the same experimental groups (n = 20). The pastes were rinsed off, and the samples were immersed independently in phosphate-buffered saline for 2 and 4 weeks (n = 10). E.faecalis was then grown on the dentin blocks, and biofilm disruption assays were performed. Fisher's Exact and Wilcoxon rank sum tests were used for statistical analyses. With regard to direct antibacterial effects, all treatment groups demonstrated complete eradication of biofilms in comparison to placebo paste, while 10 mg/mL of TAP or higher provided substantial residual antibacterial effects. However, dentin treated with 1 mg/mL of TAP or 1.5% NaOCl did not provide substantial residual antibacterial effects. Dentin pretreated with 10 mg/mL of TAP or higher exhibited extended residual antibacterial effects and can thus be used during endodontic regeneration.(J Oral Sci 58, 575-582, 2016).

Isolation, Characterization, and Differentiation of Dental Pulp Stem Cells in Ferrets

INTRODUCTION

The ferret canine tooth has been introduced as a suitable model for studying dental pulp regeneration. The aim of this study was to isolate and characterize ferret dental pulp stem cells (fDPSCs) and their differentiation potential.

METHODS

Dental pulp stem cells were isolated from freshly extracted ferret canine teeth. The cells were examined for the expression of stem cell markers STRO-1, CD90, CD105, and CD146. The osteo/odontogenic and adipogenic differentiation potential of fDPSCs was evaluated. Osteogenic and odontogenic marker genes were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR) on days 1, 4, and 8 after osteo/odontogenic induction of fDPSCs including dentin sialophosphoprotein (DSPP), dentin matrix protein-1, osteopontin, and alkaline phosphatase. Human dental pulp cells were used as the control. The results were analyzed using 3-way analysis of variance.

RESULTS

fDPSCs were positive for STRO1, CD90, and CD105 and negative for CD146 markers with immunohistochemistry. fDPSCs showed strong osteogenic and weak adipogenic potential. The overall expression of DSPP was not significantly different between fDPSCs and human dental pulp cells. The expression of DSPP in osteo/odontogenic media was significantly higher in fDPSCs on day 4 (P < .01). The overall expression of dentin matrix protein-1, osteopontin, and alkaline phosphatase was significantly higher in fDPSCs (P = .0005).

CONCLUSIONS

fDPSCs were positive for several markers of dental pulp stem cells resembling human DPSCs and appeared to show a stronger potential to differentiate to osteoblastic rather than odontoblastic lineage.

Time-dependent effectiveness of the intracanal medicaments used for pulp revascularization on the dislocation resistance of MTA

BACKGROUND

The aim of the present study was to evaluate the time-dependent effectiveness of the intracanal medicaments used in pulp revascularization on the dislocation resistance of mineral trioxide aggregate (MTA).

METHODS

One hundred ninety-two extracted human maxillary incisor teeth were sectioned apically 12 mm below and coronally 2 mm above the cemento-enamel junction. Roots were enlarged to size 40 (Protaper F4). Next, Peeso reamers from #1 to #5 were used sequentially. Sodium hypochlorite (2.5 %), EDTA (17 %), and distilled water were used in final irrigation. The specimens were randomly divided into four groups (n = 48): Group 1, in which triple antibiotic paste (TAP) (ciprofloxacin + metronidazole + minocycline) was prepared and delivered into the canals using a lentulo spiral; Group 2, in which double antibiotic paste (DAP) (ciprofloxacin + metronidazole) was placed into the canals; Group 3, in which calcium hydroxide paste (CH) (calcium hydroxide + distilled water) was introduced into the roots; and Group 4 (control), in which no medicament was applied into the root canals. Then, the samples were kept in saline solution for 2, 4, and 12 weeks, after which time 16 roots were selected randomly from each group, representing the samples of each time point. After removal of the medicaments, MTA was placed into the coronal third of the roots, and the samples were incubated for 7 days. A push-out test was used to measure the dislocation resistance (DR) of MTA. The data were analyzed using a two-way ANOVA followed by Tukey's pairwise comparisons (p = 0.05).

RESULTS

The time factor displayed a significant effect on the DR of MTA (p < 0.05). All medicaments resulted in significantly smaller DR values after 12 weeks compared to after 1 week (p < 0.05). A significant unfavorable effect of TAP and DAP was observed as early as 2 weeks after the application, while 2 and 4 weeks after the application of CH there was no effect on the DR of MTA. No significant differences were found between the time points in the control group (p > 0.05).

CONCLUSION

The type and the intracanal duration of medicaments used for pulp revascularization should be chosen carefully to provide maximum antimicrobial effect while creating a favorable environment both for stem cell attachment and MTA adhesion.

Cytotoxicity and osteogenic potential of silicate calcium cements as potential protective materials for pulpal revascularization

OBJECTIVES

In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchymal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus.

METHODS

Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogenic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05.

RESULTS

The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracellular mineralization better than the positive control (zinc oxide-eugenol-based cement).

SIGNIFICANCE

A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularization. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs.

Indirect cytocompatibility of a low-concentration hydrogen peroxide bleaching gel to odontoblast-like cells

AIM

To assess the initial cytotoxicity and the late phenotype marker expression of odontoblast-like cells (MDPC-23) subjected to less aggressive in-office bleaching therapies.

METHODOLOGY

A 17.5% hydrogen peroxide (H2O2) gel was applied for 45, 15 or 5 min to enamel/dentine discs adapted to trans-wells positioned over cultured MDPC-23 cells. No treatment was performed on the negative control. Immediately after bleaching, the cell viability, gene expression of inflammatory mediators and quantification of H2O2 diffusion were evaluated. The ALP activity, DSPP and DMP-1 gene expression and mineralized nodule deposition (MND) were assessed at 7, 14 or 21 days post-bleaching and analysed statistically with Mann-Whitney U-tests (α = 5%).

RESULTS

H2O2 diffusion, proportional to treatment time, was observed in all bleached groups. Reductions of approximately 31%, 21% and 13% in cell viability were observed for the 45-, 15- and 5-min groups, respectively. This reduction was significant (P < 0.05) for the 45- and 15-min groups, which also presented significant (P < 0.05) over-expression of inflammatory mediators. The 45-min group was associated with significant (P < 0.05) reductions in DMP-1/DSPP expression at all periods, relative to control. The ALP activity and MND were reduced only in initial periods. The 15-min group had less intense reduction of all markers, with no difference to control at 21 days.

CONCLUSIONS

The 17.5% H2O2 applied to tooth specimens for 5 min caused no alteration in the odontoblast-like cells. When this gel was applied for 45 or 15 min, a slight cytotoxicity, associated with alterations in phenotypic markers, was observed. However, cells were able to recover their functions up to 21 days post-bleaching.