BACKGROUND: External Inflammatory Root Resorption (EIRR) is a significant complication that can occur following traumatic dental injuries, with a prevalence of approximately 18%. Most cases occur during the early stage of the mixed dentition. Specifically, EIRR occurs in approximately 5-8% of luxation injuries, 30% of replanted teeth following avulsion, and 38% of intruded teeth. Conventional methods for addressing EIRR in immature teeth pose several challenges. This often requires numerous dental visits where Ledermix® and calcium hydroxide are used, which may significantly prolong the treatment. Additionally, the effect of prolonged use of calcium hydroxide medication in the root canal is debatable. Recent publications have highlighted the ability of regenerative endodontic treatment (RET) to effectively stop and repair external inflammatory root resorption (EIRR) in a relatively brief time, yielding impressive results. Nevertheless, the underlying mechanism responsible for this effect remains unclear.
METHODS: A hypothesis is proposed and drawn from existing data, explaining the mechanism by which RET triggers alterations in the root dimensions of necrotic immature teeth, facilitating continuous root maturation. The hypothesis suggests that bioactive molecules, including growth factors, might be able to penetrate the denuded dentin, reach the resorbed area, and attract stem cells from the surrounding periodontal ligament (PDL) and adjacent bone, leading to the arrest of the resorption process.
RESULTS: This recruitment may trigger repair mechanisms, ultimately resulting in the coverage of the denuded dentin with a new layer of PDL, cementoid, and cementum.
CONCLUSIONS: A hypothesis of the potential mechanism in which RET may arrest EIRR is presented along with a case report.

BACKGROUND: Regenerative endodontic procedures (REPs) are innovative treatments aimed at restoring damaged dental structures. However, the effect of orthodontic movement on REP-treated teeth is not well understood and may have significant long-term consequences. This study aimed to evaluate the impact of orthodontic movement on a mature permanent tooth associated with dens invaginatus that has undergone a regenerative endodontic procedure (REP).
METHODS: This report describes the case of a 13-year-old healthy male who presented with pulp necrosis and a chronic apical abscess (tooth number 2.2). Following REP according to the American Association of Endodontists\' guidelines, the patient began non-extraction orthodontic treatment with fixed appliances after a 9-month healing period, which lasted 17 months in the upper arch. Subsequent follow-ups at 24, 36 and 48 months post-REP revealed an asymptomatic state with minimal cervical discoloration and diminished cold sensitivity. Radiographic analyses revealed periapical healing, mild apical remodeling on tooth 2.2, and moderate apical remodeling on other maxillary incisors. The treated tooth displayed a positive response to both REP and orthodontic treatment, yet further research is required to determine the long-term effects of orthodontics on REP-treated teeth.
CONCLUSIONS: Orthodontic movement following REPs in mature permanent teeth is feasible and do not seem to prone teeth to orthodontic tooth resorption. Our experience indicates that a 9-month healing period allows successful orthodontic outcomes following REPs. Nonetheless, the predictability of outcomes and the ideal healing period before orthodontic movement is initiated remain to be established.

BACKGROUND: Recognizing the necessity of novel disinfection strategies for improved bacterial control to ultimately favor tissue regeneration, this study developed and characterized antibiotics-laden silk fibroin methacrylated (SilkMA) scaffolds for regenerative endodontics.
METHODS: SilkMA-based solutions (10% w/v) containing Clindamycin (CLI) or Tinidazole (TIN) (0 - control; 5, 10, or 15% w/w) or the combination of both drugs (BiMix CLI/TIN 10%) were electrospun and photocrosslinked. Morphology and composition were assessed using scanning electron microscopy and Fourier-transform infrared spectroscopy. Additionally, swelling and degradation profiles were also determined. Cytotoxicity was evaluated in stem cells from apical papilla. Antibacterial efficacy was tested using direct and indirect contact assays against Aggregatibacter actinomycetemcomitans/Aa, Actinomyces naeslundii/An, Enterococcus faecalis/Ef, and Fusobacterium nucleatum/Fn. E. faecalis biofilm inhibition on dentin discs was specifically evaluated for BiMix-laden scaffolds. Data were statistically analyzed with a significance level of 5%.
RESULTS: Scanning electron microscopy revealed that all scaffolds had similar characteristics, including fiber morphology and bead absence. Fourier-transform infrared spectroscopy showed the incorporation of CLI and TIN into the fibers and in BiMix scaffolds. Antibiotic-laden scaffolds exhibited lower swelling capacity than the control and were degraded entirely after 45 days. Scaffolds laden with CLI, TIN, or BiMix throughout all time points did not reduce stem cells from apical papilla\'s viability. CLI-laden scaffolds inhibited the growth of Aa, An, and Ef, while TIN-laden scaffolds inhibited Fn growth. BiMix-laden scaffolds significantly inhibited Aa, An, Ef, and Fn in direct contact, and their aliquots inhibited An and Fn through indirect contact, with additional biofilm inhibition against Ef.
CONCLUSIONS: BiMix-laden SilkMA scaffolds are cytocompatible and exhibit antimicrobial effects against endodontic pathogens, indicating their therapeutic potential as a drug delivery system for regenerative endodontics.

OBJECTIVE: To synthesize casein enzymatic hydrolysate (CEH)-laden gelatin methacryloyl (GelMA) fibrous scaffolds and evaluate the cytocompatibility and anti-inflammatory effects on dental pulp stem cells (DPSCs).
METHODS: GelMA fibrous scaffolds with 10%, 20%, and 30% CEH (w/w) and without CEH (control) were obtained via electrospinning. Chemo-morphological, degradation, and mechanical analyses were conducted to evaluate the morphology and composition of the fibers, mass loss, and mechanical properties, respectively. Adhesion/spreading and viability of DPSCs seeded on the scaffolds were also assessed. The anti-inflammatory potential on DPSCs was tested after the chronic challenge of cells with lipopolysaccharides (LPS), followed by treatment with extracts obtained after immersing the scaffolds in α-MEM. The synthesis of the pro-inflammatory cytokines IL-6, IL-1α, and TNF-α was measured by ELISA. Data were analyzed by ANOVA/post-hoc tests (α = 5%).
RESULTS: CEH-laden electrospun fibers had a larger diameter than pure GelMA (p ≤ 0.036). GelMA scaffolds laden with 20% and 30% CEH had a greater mass loss. Tensile strength was reduced for the 10% CEH fibers (p = 0.0052), whereas no difference was observed for the 20% and 30% fibers (p ≥ 0.6736) compared to the control. Young\'s modulus decreased with CEH (p < 0.0001). Elongation at break increased for the 20% and 30% CEH scaffolds (p ≤ 0.0038). Over time, DPSCs viability increased across all groups, indicating cytocompatibility, with CEH-laden scaffolds exhibiting greater cell viability after seven days (p ≤ 0.0166). Also, 10% CEH-GelMA scaffolds decreased the IL-6, IL-1α, and TNF-α synthesis (p ≤ 0.035).
CONCLUSIONS: CEH-laden GelMA scaffolds facilitated both adhesion and proliferation of DPSCs, and 10% CEH provided anti-inflammatory potential after chronic LPS challenge.
CONCLUSIONS: CEH incorporated in GelMA fibrous scaffolds demonstrated the potential to be used as a cytocompatible and anti-inflammatory biomaterial for vital pulp therapy.

This study aimed to perform clinical and radiographic investigations of the effect of regenerative endodontic procedures (REPs) with and without concentrated growth factor (CGF). Fifty-six non-vital and immature teeth from 56 patients were randomly categorized into two groups. Following chemical and mechanical preparation, REPs with and without CGF as a scaffold was induced in the blood clot (BLC) group and the CGF group. All patients were clinically and radiographically evaluated at 6-month and 12-month intervals to monitor their progress and treatment outcomes. When considering the total number of patients, the follow-up rate was 96.4% (54 out of 56 patients) over a 12-month period. Favorable clinical and radiographic outcomes were observed in 92.6% of patients (25 out of 27) in both the CGF and BLC groups; there were no significant differences between the two groups in these respects (p > 0.05). Notable differences were, however, observed in radiographic measurements relating to the development of root length and radiographic root area when compared between the CGF and BLC groups at both the 6-month and 12-month follow-up intervals (p < 0.05). REPs have been proven to represent a conservative and effective approach for promoting maturogenesis in non-vital and immature teeth. Furthermore, the incorporation of CGF as scaffolds holds promising potential for enhancing the desired biological outcomes of this regenerative technique. These findings highlight the clinical significance and potential benefits of CGF supplementation in REPs, further supporting its application in the field of endodontics.

BACKGROUND: Regenerative endodontics involves the use of various root canal medicaments and scaffolds, which may cause crown discoloration.
OBJECTIVE: This study aimed to investigate the combined crown discoloration of scaffolds [platelet-rich fibrin (PRF) and blood clot] applied after administration of different medicaments [modified triple antibiotic paste including doxycycline (mTAPd), modified double antibiotic paste (mDAP), calcium hydroxide (CH), and propolis].
METHODS: In total, 100 human mandibular premolar teeth were selected and prepared. The teeth were apically resected to simulate immature teeth. The positive and negative control groups (n = 10) consisted solely of blood-only and serum-only samples. The remaining 80 teeth were used for the experimental groups with four different medicaments. Three weeks later, either blood or PRF was applied as a scaffold after removing the medicaments (n = 10). Color changes were assessed before medication placement and at the end of the first, second, and third weeks, as well as on days 0, 1, 30, 60, and 90 after scaffold application. Analysis was carried out using repeated measures of variance, Friedman, one-way ANOVA, Kruskal-Wallis, the dependent paired t-test, and Wilcoxon test.
RESULTS: Statistical significance was determined at P = 0.05. All groups including blood and the group including propolis and PRF combination, resulted in a significant increase in discoloration (P < 0.05) and discoloration exceeding clinically acceptable thresholds.
CONCLUSIONS: CH and the modified versions of TAP (mTAPd) and DAP (mDAP) demonstrated an acceptable level of discoloration when used with a combination of PRF at day 90.

Regenerative endodontics aims to restore pulp tissues, thus preserving the vitality of the tooth. One promising approach involves the utilization of decellularized human dental pulp (DHDP) as a scaffold repopulated with Wharton\'s Jelly mesenchymal stem cells (WJMSCs). This study aimed to regenerate pulp tissues using DHDP and WJMSCs following pulpectomy in mature canine teeth of a feline animal model and to investigate the histological features of the regenerated pulp. A 12-month-old male domestic shorthaired felines were used as subjects. Teeth were categorized into untreated (Group 1), pulpectomy with mineral trioxide aggregate (MTA) (Group 2), and pulpectomy with DHDP-repopulated scaffold and MTA (Group 3). The animals were sacrificed six weeks post-intervention. H&E and immunohistochemistry using anti-collagen type 1 and laminin antibodies were used to stain the tissue sections. Histological examinations presented pulp-like tissues in Group 3, with tissue components similar to the structures found in Group 1. Immunohistochemical analysis demonstrated the presence of collagen type I and laminin within the regenerated tissues. The root canals of teeth in Group 2 were devoid of pulpal tissue. DHDP with WJMSCs can potentially be used for pulp regeneration, supporting the modality for developing new clinical protocols in stem cell therapy.

Regenerative endodontics (REP) is a new clinical modality aiming to regenerate damaged soft and hard dental tissues, allowing for root completion in young adults\' teeth. Effective disinfection is crucial for REP success, but commonly used antimicrobials often harm the niche dental pulp stem cells (DPSCs). To our knowledge, this is the first study to explore the biocompatibility and antimicrobial potential of pectin as a potential natural intracanal medicament for REPs. Low methoxyl commercial citrus pectin (LM) (pectin CU701, Herbstreith&Fox.de) was used in all experiments. The pectin\'s antibacterial activity against single species biofilms (E. faecalis and F. nucleatum) was assessed using growth curves. The pectin\'s antimicrobial effect against mature dual-species biofilm was also evaluated using confocal laser scanning microscopy (CLSM) after 30 min and 7 days of treatment. The DPSC biocompatibility with 2% and 4% w/v of the pectin coatings was evaluated using live/dead staining, LDH, and WST-1 assays. Pectin showed a concentration-dependent inhibitory effect against single-species biofilms (E. faecalis and F. nucleatum) but failed to disrupt dual-species biofilm. Pectin at 2% w/v concentration proved to be biocompatible with the HDPSCs. However, 4% w/v pectin reduced both the viability and proliferation of the DPSCs. Low concentration (2% w/v) pectin was biocompatible with the DPSCs and showed an antimicrobial effect against single-species biofilms. This suggests the potential for using pectin as an injectable hydrogel for clinical applications in regenerative endodontics.

BACKGROUND: This study investigated the biocompatibility and antibacterial efficacy of chitosan-gelatin (CH-G) scaffolds loaded with slow-releasing antibiotic formulations used in regeneration endodontic procedures (REPs).
METHODS: Scaffolds were fabricated using freeze drying and loaded with varying concentrations of augmentin or modified triple antibiotic paste (mTAP). High-resolution scanning electron microscopy (SEM) was used to characterize the scaffold, while drug release was monitored via UV-Vis spectrophotometry. Immortalized human mesenchymal stem cells (hMSCs) were cultured on CH-G scaffolds alone (control), either 0.1 mg/mL or 1 mg/mL of augmentin or mTAP, and 10 mg/mL calcium hydroxide (Ca(OH)2). Cell viability and proliferation were assessed using the Alamar Blue assay and SEM, respectively, and live/dead staining further corroborated cell viability. Antibacterial activity against Enterococcus faecalis was evaluated using the MTT assay and confocal laser scanning microscopy (CLSM).
RESULTS: Augmentin at 0.1 mg/mL appeared to promote better cell growth and attachment within the scaffolds than all other formulations, exhibiting acceptable viability. SEM revealed improved cell attachment in augmentin and mTAP groups compared to the Ca(OH)2 group. Augmentin at 1 mg/mL and mTAP groups significantly reduced viable bacteria compared to controls. Augmentin groups and mTAP at 1 mg/mL were highly effective in eliminating E. faecalis biofilms, with mTAP potentially causing more cell death within the remaining biofilm structures.
CONCLUSIONS: This study suggests that CH-G scaffolds loaded with augmentin and mTAP, particularly at a concentration of 1 mg/mL, offer promising advantages for REPs due to their biocompatibility, antibacterial efficacy, and ability to promote cell attachment. Further research may explore the long-term effects in clinical settings.

Background: Antibiotic pastes used as intracanal medication in cases of revascularization therapy might cause negative effects on tooth properties, such as a reduction in dentin microhardness. This in vitro study investigated dentin microhardness in three different locations distancing from the canal lumen after 20 days of treatment with a tri-antibiotic paste (ciprofloxacin, metronidazole, and minocycline), and with a double-antibiotic paste (ciprofloxacin and metronidazole), with calcium hydroxide [Ca(OH)2] UltracalTM XS-treated dentin as comparison. Material and Methods: Human mandibular premolars (n = 48) had the root canals cleaned and shaped and were used to produce dentin slices. Dentin slices remained immersed in the medications for 20 days. The Knoop microhardness (KHN) test was performed before (baseline/Day-0) and after treatment (Day-20) with the medications. Indentations were made at 25 µm, 50 µm, and 100 µm distances from the root canal lumen. The KHN was compared intra-group using Wilcoxon\'s test. Independent groups were compared using Mann-Whitney\'s and Kruskal-Wallis\' tests, at α = 5%. Results: The microhardness in all the tested groups was reduced at Day-20 in comparison with Day-0 (p < 0.001) (intra-group comparison/same distances). The Day-0 values were similar, and the Day-20 values were higher for the Ca(OH)2 group (p < 0.05) (comparison between groups/same distances). Conclusions: Calcium hydroxide for 20 days would be preferred rather than antibiotic pastes to minimize the expected reduction in dentin microhardness during regenerative procedures.