Antibacterial Efficacy and Discoloration Potential of Endodontic Topical Antibiotics

Injectable Hydrogel as Intracanal Medication for Root Canal Disinfection

Due to the complex anatomical structures of the root canal, thorough intracanal disinfection has always been challenging in endodontic treatment. Existing intracanal medicaments exhibit limitations such as low permeability and suboptimal antibacterial performance. Thus, an intracanal medicament that combines excellent operating performance with potent antibacterial properties is required. Therefore, we designed an injectable hydrogel loaded with modified triple antibiotic drugs (mTAD) through a Schiff base reaction of carboxymethyl chitosan (CMCS) and polyethylene glycol aldehyde (OHC-PEG-CHO), mTAD/CMCS/OHC-PEG-CHO (mTCP). We subsequently evaluated the characteristics of mTCP. Moreover, the antibacterial capacity of the hydrogels was assessed in vitro. The effects of mTCP on the cell biocompatibility and odonto-/osteogenic differentiation of stem cells from the apical papilla (SCAPs) were also examined. Furthermore, we established a periapical inflammation model in the young permanent teeth of a Beagle dog and explored the effects of mTCP on root canal disinfection and root development. Our findings revealed that mTCP exhibited excellent operability, fluidity, and ease of removal from the root canal. mTCP presented outstanding antibacterial efficacy both in vitro and in vivo, attributed to its exceptional permeability and sustained release of mTAD. The odonto-/osteogenic differentiation of SCAPs was augmented by adding mTCP. Moreover, mTCP facilitated root elongation, dentinal wall thickening, and apical closure in the Beagle dog model. mTCP exhibited a pronounced effect on promoting periapical tissue healing and root development. In conclusion, mTCP hydrogel has promising potential for root canal disinfection in endodontic therapy.

Visual Antimicrobial Gold Nanocluster Hydrogel with Inflammation-Responsive and Time-Regulated Swelling/Degradation for Regenerative Endodontic Procedures

Regenerative endodontic procedures (REPs) have become the primary therapy for immature permanent teeth. Double antibiotic (DA, ciprofloxacin, and metronidazole) is recommended as the intracanal medicament in REPs. However, it has several limitations, such as toxicity to stem cells, short-term antibacterial efficacy, and inability to be visualized radiographically. In this study, a method is induced to construct an antimicrobial gold nanocluster (Au NC) hydrogel loading DA (DA@Au NCs) via electrostatic interactions and disulfide bond generation for REPs. As exposed to interstitial fluid from root canal infection, DA@Au NCs can swell and fill the canal to thoroughly contact with bacteria in its biofilm. The increasing interstitial fluid and its internal protease can trigger the degradation of DA@Au NC hydrogel to release DA, and it has been found that the cross-linking time of hydrogel can regulate its degradation time because of the positive correlation between them. Au NC hydrogel has the characteristics of radiographical visualization to track the drug location and release dynamics. These properties can improve the antimicrobial efficiency, achieve long-term antibacterial effects, and reduce cells toxicity. Moreover, the hydrogel can also kill planktonic bacteria and biofilm, even penetrating dentin tubules. Attributed to the introduction of Au NCs, it also supports stem cell proliferation, migration, adhesion, and mineralization by regulating the expression of alkaline phosphatase (ALP). The in vivo experiments also verified that the multiple properties of DA@Au NC hydrogel offer a solution to address the problem of REPs.

Comparative Evaluation of Cytotoxicity, Anti-inflammatory, and Drug Release Profiles of Allicin-incorporated GO-AgNP Hydrogel: An In Vitro Study

AIM

This study evaluates the cytotoxicity, anti-inflammatory effects, and drug release profiles of an allicin-incorporated graphene oxide-silver nanoparticle (GO-AgNP) hydrogel as an intracanal medicament.

MATERIALS AND METHODS

The allicin-incorporated GO-AgNP hydrogel was synthesized and characterized using transmission electron microscopy. Human periodontal ligament (PDL) fibroblasts were used for 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assays, assessing cell viability at 10, 25, 50, and 100 µg/mL concentrations over 24, 48, and 72 hours. Anti-inflammatory effects were evaluated by analyzing interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α expression in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells via quantitative polymerase chain reaction at 24 hours and 7 days. Drug release was assessed using ultraviolet-visible spectrophotometry over 168 hours in root canal-treated teeth.

RESULTS

The allicin-incorporated GO-AgNP hydrogel exhibited concentration-dependent cytotoxicity, with cell viability exceeding 90% at 10-20 µg/mL but decreasing significantly at 50-100 µg/mL (p < 0.05). The half-maximal inhibitory concentration was approximately 45 µg/mL. Anti-inflammatory assays showed a reduction in IL-6 (45%), IL-8 (38%), and TNF-α (42%) compared with the LPS-treated control (p < 0.05). Drug release analysis revealed a sustained release pattern, with the 20 µg/mL hydrogel demonstrating a higher cumulative release than the 10 µg/mL hydrogel.

CONCLUSION

The allicin-incorporated GO-AgNP hydrogel demonstrates potential as a biocompatible intracanal medicament with anti-inflammatory properties and controlled drug release. Further optimization is required for clinical application.

CLINICAL SIGNIFICANCE

This allicin-incorporated GO-AgNP hydrogel shows promise as an intracanal medicament due to its biocompatibility, anti-inflammatory properties, and controlled drug release. By modulating the inflammatory response, it may contribute to reduced postoperative discomfort and improved periapical healing. Additionally, its bioactive properties may support tissue repair and regeneration, making it a potential candidate for regenerative endodontic procedures. How to cite this article: Piriyanga R, Ranjan M, Bathla S, et al. Comparative Evaluation of Cytotoxicity, Anti-inflammatory, and Drug Release Profiles of Allicin-incorporated GO-AgNP Hydrogel: An In Vitro Study. J Contemp Dent Pract 2025;26(1):71-76.

In vitro analysis of compressive strength of root dentin on application of intracanal medicaments for different time periods

Background

Extended application of intracanal medicaments such as calcium hydroxide (CH) and triple antibiotic paste (TAP) is documented to reduce dentin's resistance to fracture.

Aim

This study intended to evaluate the resistance to fracture of root dentin treated with different medicaments - CH, TAP, CH with chlorhexidine (CHX) and lycopene (LP), and chitosan acetate (CA) - over 7, 14, and 42 days.

Materials and Methods

Seventy-five single-rooted human mandibular premolars were biomechanically prepared and categorized into five groups based on the medicament used, with further subdivision based on application duration. Fracture resistance was tested after each time interval.

Statistical Analysis

Within-group comparisons were analyzed using repeated measures analysis of variance (ANOVA), while inter-group comparisons used a one-way ANOVA test at a 5% significance level.

Results

At 7 days, no statistically notable differences were found among the groups. However, by day 14 and day 42, the groups treated with CH and TAP exhibited significantly reduced fracture resistance compared to the other groups.

Conclusion

Combining LP with CH and CHX, or using CA, did not reduce radicular dentin fracture resistance, unlike TAP and CH. These findings suggest LP and CA as viable alternatives, potentially minimizing the adverse effects of traditional treatments.

Antibiofilm efficacy of a calcium silicate-based intracanal medicament against Fusobacterium nucleatum strains

This study evaluated the antibiofilm efficacy of a calcium silicate-based intracanal medicament (Bio-C Temp) against Fusobacterium nucleatum (F. nucleatum). Dentin slices (n = 88) were inoculated with F. nucleatum biofilms and divided into experimental groups (n = 24 each) treated with Bio-C Temp, triple antibiotic paste (TAP), or Ca(OH)2 for 1 or 2 weeks. Untreated dentin slices exposed to saline served as a positive control, while sterile dentin slices incubated anaerobically served as a negative control. Bacterial viability was assessed using confocal laser scanning microscopy after staining with LIVE/DEAD® BacLight™ dye. Samples treated with TAP demonstrated the highest percentage of dead bacteria (95%). The antibiofilm effect of TAP and Bio-C Temp significantly increased from Week 1 to Week 2. At Week 2, samples treated with Bio-C Temp showed a significantly higher percentage of dead bacteria (75.25%) than those treated with Ca(OH)2 (58.65%). TAP showed superior efficacy against F. nucleatum biofilms. After an application time of 2 weeks, the antibiofilm efficacy of Bio-C Temp was superior to that of Ca(OH)2.

Dimethylaminododecyl Methacrylate-Incorporated Dental Materials Could Be the First Line of Defense against Helicobacter pylori

Oral cavity is an essential reservoir for H. pylori. We aimed to investigate the antibacterial effects of dimethylaminododecyl methacrylate (DMADDM) against H. pylori. Modified giomers were prepared by introducing 0%, 1.25% and 2.5% DMADDM monomers. Broth microdilution assay, spot assay, Alamer Blue assay, PMA-qPCR, crystal violet staining, scanning electron microscopy observation and live/dead bacterial staining were performed to evaluate the antibacterial and antibiofilm effects of DMADDM and modified giomers in vitro. Urease assay, qPCR, hematoxylin-eosin staining and ELISA were performed to evaluate the inflammation levels and colonization of H. pylori in vivo. In vitro experiments indicated that the minimum inhibitory concentration and minimum bactericidal concentration of DMADDM were 6.25 μg/mL and 25 μg/mL, respectively. It inhibited H. pylori in a dose- and time-dependent manner, and significantly reduced the expression of cagA, vacA, flaA and ureB. DMADDM-modified giomers inhibited the formation of H. pylori biofilm and reduced live cells within it. In vivo experiments confirmed that the pretreatment with DMADDM-modified dental resin effectively reduced the gastric colonization of oral-derived H. pylori, suppressed systemic and local gastric inflammation. DMADDM monomers and DMADDM-modified giomers possessed excellent antibacterial and antibiofilm effects on H. pylori. Pretreatment with DMADDM-modified giomers significantly inhibited the gastric infection by H. pylori.

Outcome of Regenerative Endodontic Procedures in Non-Vital Immature Permanent Teeth Using Two Intracanal Medications: A Prospective Randomized Clinical Study

INTRODUCTION

This randomized clinical trial aimed to assess and compare the long-term clinical and radiographic outcomes of Regenerative Endodontic Procedures (REP) in treating non-vital immature permanent teeth using two intra-canal medicaments.

METHODS

Forty-five patients yielding a total of 50 anterior and posterior non-vital immature teeth were randomly divided into 2 groups. REP utilizing either non-setting calcium hydroxide (Ca(OH)₂) (n=25) or modified triple antibiotic paste (TAP) (n=25), as intra-canal medicaments were performed. NeoMTA Plus (Avalon Biomed Inc™, Houston, Texas, USA) was applied for coronal sealing. Cases were followed up clinically and radiographically for 36 months. Survival rate, success rate, and clinical outcome measures were analyzed. Preoperative and recall radiographs were evaluated for dimensional changes in root length, dentin thickness, apical diameter, and periapical radiolucency.

RESULTS

At 36 months follow up, success and survival rates were 81.6%, and 100% respectively, in which 79.4% of cases showed complete resolution of periapical radiolucency, with no significant difference between non-setting Ca(OH)2 and modified TAP groups (P>0.050). The cumulative changes in root length, root dentin thickness and apical diameter, throughout the study period, were observed in 47.9%, 77.1%, and 89.6 %, of cases respectively, with no significant differences between both groups (P≥ 0.39). Intra-canal calcifications were detected in 60% of cases with no significant difference between both groups (P=0.77).

CONCLUSIONS

REP, using either non-setting Ca(OH)₂ or modified TAP as intra-canal medicament, exhibited high success and survival rates, over a follow up period of 36 months, with equally favorable clinical and radiographic outcome data.

Applications of Hydrogels in Drug Delivery for Oral and Maxillofacial Diseases

Oral and maxillofacial diseases have an important impact on local function, facial appearance, and general health. As a multifunctional platform, hydrogels are widely used in the biomedical field due to their excellent physicochemical properties. In recent years, a large number of studies have been conducted to adapt hydrogels to the complex oral and maxillofacial environment by modulating their pore size, swelling, degradability, stimulus-response properties, etc. Meanwhile, many studies have attempted to use hydrogels as drug delivery carriers to load drugs, cytokines, and stem cells for antibacterial, anticancer, and tissue regeneration applications in oral and maxillofacial regions. This paper reviews the application and research progress of hydrogel-based drug delivery systems in the treatment of oral and maxillofacial diseases such as caries, endodontic diseases, periodontal diseases, maxillofacial bone diseases, mucosal diseases, oral cancer, etc. The characteristics and applications of hydrogels and drug-delivery systems employed for the treatment of different diseases are discussed in order to provide a reference for further research on hydrogel drug-delivery systems in the future.

Antimicrobial potential of new diclofenac hydrogels for disinfection in regenerative endodontics: An in vitro and ex vivo study

AIM

There is a need to explore new alternatives for root canal disinfection in regenerative endodontics, since the current strategies are far from ideal. Currently, the potential use of diclofenac (DC) is being investigated for controlling root canal infections. The objective was to evaluate the antimicrobial efficacy of novel DC-based hydrogels (DCHs) against polymicrobial biofilms grown in radicular dentine and root canals and to compare results with triantibiotic (TAH) and diantibiotic (DAH) hydrogels, and calcium hydroxide (Ca[OH]₂ ).

METHODOLOGY

The in vitro antimicrobial activity of intracanal medicaments was evaluated against 3-week-old polymicrobial root canal biofilms grown on human radicular dentine. Dentine samples were obtained and randomly divided into the study groups (n = 4/group): (1) 1 mg/ml TAH; (2) 1 mg/ml DAH; (3) 5% diclofenac (DCH); (4) 2.5% DCH; (5) 1.25% DCH; (6) 1 mg/ml DAH + 5% DCH; (7) Ca(OH)₂ paste; (8) positive control. The microbial viability, in terms of percentage of intact cell membranes, was assessed after 7 days by confocal scanning laser microscopy (CSLM). The ex vivo efficacy of intracanal medications was evaluated in root canals infected with a polymicrobial suspension. Intracanal microbiological samples at baseline (S1) and 7 days post-treatment (S2) were taken; microbial quantification and cell viability were assessed by quantitative polymerase chain reaction (qPCR) and flow cytometry (FC). The mean Log₁₀ of bacterial DNA copies in root canal samples before (S1) and the Log₁₀ reduction of DNA copies S1-S2 in qPCR were recorded. The absolute value of total cells stained, and the percentage reduction of intact membrane cells after treatment (S1-S2), were analysed by FC. Global comparison was done using the Kruskal-Wallis test, whilst the Mann-Whitney U test was used for pair-by-pair comparison.

RESULTS

Confocal scanning laser microscopy analysis indicated that the greatest effectiveness was obtained with 5% DCH, showing significant differences with respect to the other groups (p < .001). In root canals, the highest Log₁₀ DNA reduction S1-S2 was obtained with 5% DCH and TAH, with no differences between them. The results of FC showed that only 5% DCH proved significantly superior to the other treatments.

CONCLUSIONS

Sodium DC hydrogels demonstrate antimicrobial efficacy against endodontic biofilms.

Silver Nanoparticles Alone or in Combination with Calcium Hydroxide Modulate the Viability, Attachment, Migration, and Osteogenic Differentiation of Human Mesenchymal Stem Cells

This study aimed to evaluate the effect of silver nanoparticles (AgNPs) alone or in combination with calcium hydroxide (Ca(OH)2) on the proliferation, viability, attachment, migration, and osteogenic differentiation of human mesenchymal stem cells (hMSCs). Different concentrations of AgNPs alone or mixed with Ca(OH)2 were prepared. Cell proliferation was measured using AlamarBlue, and hMSCs attachment to dentin disks was evaluated using scanning electron microscopy. Live-dead imaging was performed to assess apoptosis. Wound healing ability was determined using the scratch-migration assay. To evaluate osteogenic differentiation, the expression of Runt-related transcription factor (RUNX2), Transforming growth factor beta-1 (TGF-β1), Alkaline Phosphatase (ALP), and Osteocalcin (OCN) were measured using real-time reverse transcriptase polymerase chain reaction. ALP staining and activity were also performed as indicators of osteogenic differentiation. AgNPs alone seemed to favor cell attachment. Lower concentrations of AgNPs enhanced cell proliferation. AgNP groups showed markedly less apoptosis. None of the medicaments had adverse effects on wound closure. The expression of TGF-β1 was significantly upregulated in all groups, and OCN was highly expressed in the AgNP groups. AgNPs 0.06% showed the most enhanced ALP gene expression levels, activity, and marked cytochemical staining. In conclusion, AgNPs positively affect hMSCs, making them a potential biomaterial for various clinical applications.

Histological Evaluation of Restylane Lyft Used as a Scaffold for Dental Pulp Regeneration in Non-Infected Immature Teeth in Dogs

Commercially available hyaluronic acid dermal fillers used as a scaffold in regenerative endodontic procedures (REPs) have demonstrated attractive potentials. This study aimed to histologically evaluate the outcome of REPs using Restylane Lyft (HA) as a scaffold. REPs were performed on pulpless, immature roots in dogs (n = 69). The roots were divided into four groups: blood clot (BC), Restylane Lyft (BC + HA), negative control, and positive control. At 13 weeks postoperatively, hard tissue formation, vascularization, the presence of vascularized soft connective tissue and collagen fibers, the degree of inflammation within pulp spaces and/or periapical tissues, and apical closure were evaluated histologically. The vascularization and formation of loosely arranged collagen fibers within the regenerated soft connective tissues were observed significantly more in the BC+HA group (85% and 40%, respectively; p < 0.05) compared to the BC group (54.6% and 9.1%, respectively; p < 0.05). The degree of inflammation was significantly higher in the HA group than in the BC group; moderate to severe inflammatory cell infiltration was seen in 45% and 13.6% of the cases, respectively. The results of the present study suggest that Restylane Lyft combined with a blood clot used as a scaffold may improve the outcomes of REPs in non-infected, pulpless, immature teeth in dogs.

The effect of different intracanal medicaments on the dislodgement resistance of mineral trioxide aggregate

BACKGROUND

This study aimed to assess the effect of different commercially used calcium hydroxide [Ca(OH)₂], the mixture of Ca(OH)₂ + silver nanoparticles (AgNPs), and other intracanal medicaments on dislodgement resistance of mineral trioxide aggregate (MTA) to root canal dentin in short- and long-term application.

METHODS

Forty-six human single-rooted maxillary teeth were sectioned horizontally at mid-root into 1 mm thick slices. The lumen of the slices was standardized using #2-#5 Gates Glidden drills to a standard diameter of 1.3 mm in all samples. After smear layer removal, the samples were randomly divided into eight groups (n = 20) and treated with the following medicaments; Ca(OH)₂ paste, Calcipex, Metapex, chlorhexidine (CHX), Ca(OH)₂/CHX paste, Ca(OH)₂/AgNPs, triple antibiotic paste and control group (normal saline). The samples were then incubated at 37 °C with 100% humidity for 1 week. Next, half of the teeth in each group (n = 10) were removed from the incubator and washed in an ultrasonic bath. ProRoot MTA was placed in the canal lumen and the samples were incubated at 37 °C and 100% humidity for 48 h to allow complete setting of MTA. The remaining half in each group (n = 10) was subjected to the same process after 1 month of application of medicaments. The dislodgement resistance of MTA to root dentin was measured. The data were analysed using two-way ANOVA and Tukey's post hoc test.

RESULTS

No significant difference was noted in dislodgement resistance of samples after 1 week and 1 month in any group (P > 0.05). The only significant difference was noted between the control and CHX groups and the higher dislodgement resistance was recorded in the CHX group (P = 0.006). No other significant differences were noted between the groups (P > 0.05).

CONCLUSION

Duration of application and the type of intracanal medicament do not affect the dislodgement resistance of MTA to root dentin. Although there was no statistically significant difference in the dislodgment resistance of MTA between the medicaments, CHX had a promising effect.

Regenerative Endodontic Treatment Using Periapical Blood or Circulating Blood as Scaffold: A Volumetric Analysis

INTRODUCTION

Circulating blood is a readily available scaffold when enough bleeding cannot be induced from periapical tissues during regenerative endodontic treatments (RET). The aim of this investigation was to compare the radiographic outcome, linear and 3-dimensional volumetric, of RET using periapical blood or circulating blood as scaffolds in sheep immature mandibular incisors.

METHODS

Thirty-two immature sheep mandibular central incisors were randomly assigned to the following groups (n=8)- Positive control: the pulps were removed without any treatment; Periapical blood: RET was performed using periapical blood as scaffold; Circulating blood: RET was performed using circulating blood as scaffold; Negative control: intact teeth without any treatment. After 8 months micro computed tomography images of mandibular blocks were taken to assess the followings: root length; root thickness at mid-root and CEJ levels; and incidence of apical closure. Root structures were segmented, and root volumes were calculated and analyzed statistically.

RESULTS

RET using periapical blood and circulating blood resulted in increase in root length, root wall thickness at mid-root and CEJ levels, incidence of apical closure, and root volume (P<.05). There were no significant differences between RET groups and negative control group regarding linear measurements (i.e., root length, root thickness, and apical closure) (P>.05). Root volumes of the two RET groups were similar (P>.05) and were less than those observed in negative control group (P<.05).

CONCLUSIONS

There were no significant radiographic differences between RET groups using periapical blood and circulating blood as scaffolds. RET resulted in less root volume compared to normal root development.

Engineering of Injectable Antibiotic-laden Fibrous Microparticles Gelatin Methacryloyl Hydrogel for Endodontic Infection Ablation

This study aimed at engineering cytocompatible and injectable antibiotic-laden fibrous microparticles gelatin methacryloyl (GelMA) hydrogels for endodontic infection ablation. Clindamycin (CLIN) or metronidazole (MET) was added to a polymer solution and electrospun into fibrous mats, which were processed via cryomilling to obtain CLIN- or MET-laden fibrous microparticles. Then, GelMA was modified with CLIN- or MET-laden microparticles or by using equal amounts of each set of fibrous microparticles. Morphological characterization of electrospun fibers and cryomilled particles was performed via scanning electron microscopy (SEM). The experimental hydrogels were further examined for swelling, degradation, and toxicity to dental stem cells, as well as antimicrobial action against endodontic pathogens (agar diffusion) and biofilm inhibition, evaluated both quantitatively (CFU/mL) and qualitatively via confocal laser scanning microscopy (CLSM) and SEM. Data were analyzed using ANOVA and Tukey's test (α = 0.05). The modification of GelMA with antibiotic-laden fibrous microparticles increased the hydrogel swelling ratio and degradation rate. Cell viability was slightly reduced, although without any significant toxicity (cell viability > 50%). All hydrogels containing antibiotic-laden fibrous microparticles displayed antibiofilm effects, with the dentin substrate showing nearly complete elimination of viable bacteria. Altogether, our findings suggest that the engineered injectable antibiotic-laden fibrous microparticles hydrogels hold clinical prospects for endodontic infection ablation.

Antibacterial efficacy of nisin, calcium hydroxide, and triple antibiotic paste in combination with chitosan as an intracanal medicament against Enterococcus faecalis - An in vitro study

Aims

Evaluate and compare antibacterial efficacy of nisin, calcium hydroxide (Ca (OH)₂), and Triple antibiotic paste (TAP) mixed with distilled water and chitosan as an intracanal medicament on Enterococcus faecalis after 1^st and 7^th day.

Settings and Design

Experimental in vitro study.

Materials and Methods

One hundred and twenty Decoronated single-rooted premolars were prepared and autoclaved. Specimens were placed in brain heart infusion (BHI) broth of a 24 h old E. faecalis (ATCC 29212) suspension. The canal was infected for 21 days, followed by grouping as-Group 1: Nisin + distilled water; Group 2: Nisin + 2% chitosan; Group 3: Ca (OH)₂ + distilled water; Group 4: Ca (OH)₂ + 2% chitosan; Group 5: TAP + distilled water; Group 6: TAP + 2% chitosan and were incubated for 1 and 7 days. Dentin scrapings from 10 specimens at each time interval were transferred into BHI broth and incubated, Serially diluted and colony-forming unit (CFU) count was assessed after 1^st and 7^th day.

Statistical Analysis Used

Kruskal-Wallis test to compare mean CFUs after day 1 and day 7. Mann-Whitney post hoc Analysis to estimate significance. Wilcoxon Signed-Rank Test to compare mean CFUs between day 1 and day 7.

Results

After 1 day, Group 6 showed least CFUs than other groups and highest CFUs was with Group 3. There was no difference statistically when Group 5 and Group 2 were compared. After 7 days, Group 6 showed least CFUs than other groups with no significant difference between Group 1 and Group 5 as well as no significant difference between Group 2, Group 5 and Group 6.

Conclusions

TAP with chitosan can be the medicament of choice for 1-day placement and was equivalent to nisin with chitosan combination after 7 days.

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.

Determination of crown discoloration and fluorescence induced by different medications used in regenerative endodontic procedures: An ex vivo study

Background

Crown discoloration is an undesirable side effect of the use of triple antibiotic paste (TAP) in regenerative endodontic procedures (REPs). The aim of this ex vivo study was to assess the potential for tooth discoloration and induction of fluorescence associated with the use of TAP containing either doxycycline (DOX) or clindamycin (CLIN), and of calcium hydroxide (Ca(OH)2), by spectrophotometric analysis and confocal laser scanning microscopy (CLSM).

Material and Methods

A total of forty single-rooted human teeth extracted by therapeutic indication were used. The root canals were enlarged using the step-back technique up to a K #80 file and were randomly divided into four experimental groups (10 specimens each): i)Ca(OH)2 group, ii)TAP with DOX group, iii) TAP with CLIN group, iv) Control group (no treatment). To quantify the change of color of the different groups of teeth included, the Vita Easyshade advance 4.0 spectrophotometer was used. CLSM was used to determine fluorescence.

Results

After 28 days of action inside the root canal, no extreme discoloration was visible, to the naked eye, in any of the teeth included in the study. Under the conditions of this ex vivo study, TAP with DOX induced the highest crown discoloration among the medicaments tested. In contrast, Ca(OH)2 and TAP with CLIN did not induce crown discoloration after 28 days. The TAP with DOX group presented the highest fluorescence measurements.

Conclusions

Considering the discoloration potential and fluorescence changes in TAP with DOX or other tetracyclines, and the cytotoxic effect of TAPs, we recommend the use of Ca(OH)2 for REPs.

Key words:Discoloration, doxycycline, clinadamycin, calcium hydroxide, endodontics.

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.

Revitalizing previously treated teeth with open apices: A case report and a literature review

Revitalizing the root canals of previously treated teeth with open apices is appealing to clinicians and patients. However, there are fundamental differences in the microbiome and the microenvironment between a canal with a primary endodontic infection and a canal with a persistent endodontic infection. The aims of this report are to report a case where a previously treated tooth with an open apex and a large apical radiolucency was treated successfully using regenerative endodontic treatment (RET) and to review and critically appraise the literature on procedures and outcomes of RET that result in revitalization of canal(s) in previously treated teeth with open apices. A maxillary central incisor with poor-quality root filling, a large apical radiolucency and an open apex was retreated using RET using platelet-rich fibrin as the scaffold. After 24 months, there was complete healing of the periapical lesion and obvious radiographic signs of apical root closure. Electronic searches were performed in MEDLINE, Scopus and Embase, and the baseline, procedural and outcome data of qualified articles were collected. An assessment tool was developed to rate the quality of evidence reported in these case report/series. Nine articles, three case series and six case reports, with a total of 17 teeth of all types, were included in the reports identified. The age of patients ranged from 7 to 48 years (mean: 19.4 years). The recall period ranged from 12 to 72 months (mean: 29 months). All 17 teeth survived and were functional with healing/healed outcomes. "Apical closure" was the most common radiographic finding regarding root development. The quality of evidence using the new assessment tool was rated "Excellent" in three case reports but only "Fair" in the other six articles. The present case report, as well as the review of the literature, suggests that revitalizing the root canal system of teeth with open apices and post-treatment disease using RET is a potentially valid treatment option. However, more clinical studies with higher levels of evidence and higher quality of evidence are required to confirm the viability of this treatment approach.

Antimicrobial Therapeutics in Regenerative Endodontics: A Scoping Review

INTRODUCTION

This review aimed to provide a critical appraisal of alternative antimicrobial strategies in lieu of traditional triple antibiotic paste (TAP).

METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The literature search was performed in 8 databases (PubMed/Medline, Embase, LILACS, Web of Science, Scopus, BVS, SciELO, and the Cochrane Library), selecting clinical, in vitro, in vivo, and in situ studies that evaluated antimicrobial alternatives to TAP in regenerative endodontics. Studies lacking an experimental TAP group were excluded.

RESULTS

A total of 1705 potentially relevant records were initially identified. From the 38 studies retrieved for full-text reading, 16 fulfilled all selection criteria and were included in the qualitative analysis. According to the study design, 11 studies were solely in vitro, 1 study was both in vitro and in vivo (animal model), 2 studies were solely animal experiments, and 2 studies were clinical trials. The alternative antimicrobial agents to TAP consisted of modified TAP formulations (eg, a combination of TAP with chitosan); TAP-eluting nanofibers; propolis; chlorhexidine (CHX) gels/solutions; double antibiotic pastes composed of distinct combinations of antibiotics; Ca(OH)2-based formulations; and sodium hypochlorite. Overall, most of the alternative agents performed similarly to TAP, although some strategies (eg, Ca(OH)2- and CHX-based formulations) seemed to present dubious importance in the control of infection.

CONCLUSIONS

TAP still remains an excellent option in terms of the complete elimination of microorganisms. This review points to the use of electrospun fibers as a drug delivery system to offer a controlled release of the antimicrobial agent, as well as the use of natural compounds, deserving future investigation.

An Innovative Drug Delivery System Loaded with a Modified Combination of Triple Antibiotics for Use in Endodontic Applications

The objective of the current study was to introduce "Polylactic co-Glycolic Acid- (PLGA-) Coated Ceramic Microparticles" as an innovative drug delivery system, loaded with a new combination of triple antibiotics (penicillin G, metronidazole, and ciprofloxacin (PMC)) for use in endodontic treatments. Ceramic microparticles were made from β-tricalcium phosphate and hydroxyapatite and examined by "Scanning Electronic Microscope (SEM)." Then, fixed amounts of the selected antibiotics were added to a prepared PLGA solution and stirred thoroughly. Next, the prepared ceramic microparticles were dispersed completely in the drugs solution. The deposited "PMC-loaded PLGA-coated ceramic microspheres (PPCMs)" were dried and incubated in phosphate buffer saline (PBS) for 21 days. The drug release from PPCMs was quantified by a UV spectrophotometer. The antimicrobial activity of PPCMs was investigated using the "Agar Plate Diffusion Test (ADT)," "Minimum Inhibitory Concentration (MIC)," and "Minimum Bactericidal Concentration (MBC)" against Enterococcus faecalis (E. faecalis) and Aggregatibacter actinomycetemcomitans (A.a). The cell viability test (MTT) was conducted for cytotoxicity against human gingival fibroblasts. SEM micrographs of PPCMs showed spherical-like ceramic microparticles with smooth surfaces. Crystal-like antibiotic particles (chunks) were also found on PPCMs. Initial burst of antibiotics (31 µg/mL, 160 µg/mL, and 18 µg/mL for ciprofloxacin, metronidazole, and penicillin G, respectively, in the first 4 days) followed by gradual and sustained release was observed within a period of 21 days. PPCMs demonstrated pH close to normal physiological environment and antibacterial activity against E. faecalis and A.a in the first 2 days. MTT showed cell viability of more than 70% for PPCMs after 24 h and 72 h of exposure. In conclusion, PPCMs demonstrated satisfactory release of antibiotics, antibacterial activity against the selected microorganisms, and biocompatibility. Thus, PPCMs may be used to deliver modified triple antibiotics to the root canal system for use in endodontic applications.

Specific Aspects of Endodontic Medication in Chronic Apical Periodontitis

This article presents specific aspects regarding the role of endodontic medication in the conservative treatment in chronic apical periodontitis. Starting from the bacterial microflora, the etiological factor of the periapical lesions, we discuss about the modalities of identification by the means of in vivo and in vitro tests of the microorganisms present inside the root canal. The characteristics of these methods of microbiological evaluations, as well as their clinical relevance, are reviewed. The general characteristics of endodontic antimicrobial medication are presented, as well as the causes of endodontic failures in treatment in chronic apical periodontitis. It is underlined the essential importance of the rigorous biomechanical treatment, in association with endodontic lavage, which makes the antibacterial medication only have a subordinate role in the treatment of chronic apical lesions.

Cytotoxicity Evaluation of Minimum Antibacterial Values of Different Medicaments Used in Endodontic Regenerative Procedures

OBJECTIVES

 This study aimed to evaluate the cytotoxicity of minimum antibacterial values of medicaments used in endodontic regeneration on stem cells.

MATERIALS AND METHODS

 "Minimum inhibitory concentration," "minimum bactericidal concentration," and "minimum biofilm inhibitory concentration" of triple and double antibiotic paste, a modified triple antibiotic paste (minocycline replaced by clindamycin), Augmentin, and calcium hydroxide were determined using Enterococcus faecalis (ATCC 29212) by microtiter plate method. Direct cytotoxic effects of drugs were evaluated by lactate dehydrogenase and water-soluble tetrazolium salt-1 assays using stem cells of apical papilla obtained from immature third molars via enzymatic digestion.

STATISTICAL ANALYSIS

 Data were analyzed using IBM SPSS Statistics 24, one-way analysis of variance and post hoc comparisons. The statistical power was set at p < 0.05.

RESULTS

 All medicaments caused similar cytotoxicity and cell proliferation at "minimum inhibitory concentration" (p > 0.05) except Augmentin which was significantly more toxic than others (p < 0.05). At "minimum bactericidal concentration," calcium hydroxide was more toxic than other drugs (p < 0.001), but its adverse effect on cell proliferation was the same as Augmentin (p > 0.05). Triple and double antibiotic paste revealed similar favorable effects in terms of toxicity and proliferation rate at most of the tested concentrations (p > 0.05). At "minimum biofilm inhibitory concentration" both the modified paste and Augmentin caused less proliferation rate than triple and double antibiotic paste (p < 0.001and p < 0.05, respectively) and Augmentin induced more cytotoxicity (p < 0.05).

CONCLUSIONS

 Considering the antimicrobial potency, triple antibiotic paste seems to be the safest drug for the stem cells of apical papilla, while Augmentin may have some adverse effects.

Microbiological aspects of traumatic injuries

After traumatic injuries to teeth, microorganisms may invade the compromised pulp tissue and initiate pulp infection and periapical inflammation. In addition to bone resorption that typically accompanies pulp necrosis, root resorption frequently occurs. Root resorption has several variants that may occur shortly after the trauma or at a later stage. The pathological changes seen after traumatic injuries to teeth are invariably linked to the presence of microbial irritants. The presence of bacterial biofilms in the dental pulp space can be treated with regenerative or therapeutic endodontic procedures. However, necrosis of periodontal ligament is usually terminal for the tooth involved. In this review, the sources of bacteria after traumatic injuries are discussed. The types and role of microorganisms involved in the pathogenesis of endodontic pathosis after traumatic injuries are presented, and contemporary approaches for the management of these conditions are reviewed. Contemporary antimicrobial strategies are discussed. The rationale for the use of systemic and topical antimicrobials is presented. Finally, novel approaches to the use of antimicrobial therapies, particularly in regenerative procedures, are reviewed.