Denosumab is a potent RANKL inhibitor used for osteoporosis, yet its impact on root canal treatment (RCT) outcomes remains less understood compared to bisphosphonates. This study evaluated the periapical healing outcomes of RCT in patients receiving denosumab and identified clinical variables influencing treatment success. This retrospective case-control study included 20 patients with osteoporosis receiving denosumab who underwent RCT at a major tertiary hospital between July 2014 and June 2024 (group D), along with 20 age- and sex-matched systemically healthy controls (group C). Among 116 denosumab-treated patients screened, 20 met the strict selection criteria and were enrolled as the study group. Periapical healing was assessed using the Periapical Index (PAI) at a minimum follow-up of 3 months after treatment. Various clinical and radiographic factors, including initial PAI scores and sealer extrusion, were analyzed using logistic regression to determine their impact on healing rates. The median follow-up period was 534 (287–956) days for group D and 421 (235–1045) days for group C. The overall periapical healing rates were 75.0.

AIMS:Periodontal diseases pose significant challenges to oral health, making the regeneration of periodontal tissues a critical therapeutic goal. The goal is to restore dental function by repairing damaged tissue and reconstructing the healthy connective structure between the teeth and the alveolar bone. This study aimed to investigate the effects of selcopintide (SCPT) on the differentiation of periodontal ligament cells (PDLCs), cementoblasts, and osteoblasts in vitro, as well as the regeneration of periodontal tissue using a periodontal tissue defect model in dogs in vivo. METHODS:The expression of periodontal tissue marker genes, including periostin (POSTN), cementum attachment protein (CAP), dentin matrix protein 1 (DMP1), and bone sialoprotein (BSP), was investigated in vitro. Chronic one-wall intrabony defects were created in a total of 12 beagle dogs (n = 6 at 6 and 12 weeks, respectively), and the surgical sites were treated with no treatment, guided tissue regeneration (GTR), GTR with SCPT 50 μg/0.1 mL, 100 μg/0.1 mL, and 250 μg/0.1 mL. The effects of SCPT on the regeneration of periodontal tissues, such as periodontal ligament (PDL), cementum, and bone, were analyzed in vivo. RESULTS:SCPT influenced the proliferation and differentiation of cementoblasts and PDLCs. Real-time polymerase chain reaction analysis showed that SCPT upregulated the expression of POSTN, CAP, DMP1, and BSP compared to the control. In the periodontal defect model, SCPT regenerated the periodontal complex. Additionally, the arrangement of the newly formed PDL-like fibers was perpendicular to the newly formed cementum and alveolar bone, similar to Sharpey's fibers in natural teeth, compared with the control. CONCLUSION:In this preclinical study, histological and immunohistochemical analyses suggest that GTR with SCPT might be associated with increased periodontal ligament attachment and enhanced cementum and alveolar bone formation. Additional research with a larger sample size is needed to establish the optimal therapeutic protocols and validate the regenerative potential of SCPT.

In situ regeneration in restorative dentistry targets the repair of tissues directly at the injury site by utilizing engineered biomaterials to guide endogenous cell activity. This approach aims to simplify treatment procedures and achieve more predictable outcomes, thus to supports the regeneration of damaged tissues and potentially restores tooth vitality, reducing the need for more invasive treatments. This study explores the potential of poly(ε-caprolactone) fibers (PCLF) functionalized with a hypoxia-inducible factor 1-alpha (HIF-1α) stabilizing small molecule dimethyloxalylglycine (DMOG) for in situ regeneration in the context of dental root repair in developing immature teeth. PCLF functionalized with DMOG (PCLF/DMOG) was applied to regenerative endodontic procedure (REP) treatment of infected developing dental roots, and its biologic properties and therapeutic potential were investigated through both in vitro studies and in vivo experiments, focusing on their capacity to promote in situ regeneration. In vivo application demonstrated the effectiveness of PCLF/DMOG in promoting root development, apical closure, and improving infectious lesions, contrasting with contemporary REP treatment controls that showed unpredictable outcomes. Mechanistically, the sustained release of DMOG from PCLF/DMOG significantly enhanced the expression of HIF-1α and upregulated expression of genes associated with angiogenesis and neurogenesis, including VEGF-α and NGF. The PCLF/DMOG upregulated antimicrobial peptides, facilitated efferocytic activities, promoted macrophage polarization to the M2 phenotype, and mobilized mesenchymal stem cells. Taken together, PCLF/DMOG could enhance innate immune responses and foster favorable microenvironment to guide cellular differentiation, promoting in situ regeneration of dental roots in the inflammatory microenvironments.

To assess the effect of indirect ultrasonic activation on the root canal obturation with a premixed calcium silicate cement (CSC). Twenty-six single-rooted premolars were sectioned to the length of 11 mm. All the roots were instrumented using ProTaper Next instruments and randomly assigned to either the control (n = 4) or experimental (n = 22) groups according to root canal obturation methods. Root specimens allocated to experimental groups were obturated with Endocem MTA, with (group EMU) or without (group EM) indirect ultrasonic activation (n = 11/group). Root specimens obturated with gutta-percha served as positive and negative (after nail varnish coating) controls. Intraoral radiograph images were used to assess the presence or absence of voids in the coronal, middle, and apical thirds of each specimen. The specimens were connected to a nanoscale fluid filtration device to measure quantitative leakage data. Data was statistically analyzed with a significance level of 0.05. There was no significant difference in the voids formation between the two groups (p > 0.05), but specimens in group EMU presented significantly higher quantitative leakage than those in group EM (p < 0.05). Within the limitation of this study, indirect ultrasonic activation of premixed CSC did not affect the void formation but presented higher quantitative leakage. Future research incorporating micro-CT imaging would enable a more precise and comprehensive analysis, providing valuable insights into the root canal obturation with premixed CSCs.

Dentin hypersensitivity is characterized by transient, sharp pain resulting from dentin exposure due to enamel or cementum loss. Current treatments, which primarily focus on superficial tubule occlusion or nerve desensitization, provide only temporary relief. Copine7 (CPNE7) induces odontoblast differentiation and physiologic dentin regeneration, enabling biological dentin sealing and presenting a novel therapeutic approach. This study reports the first-in-human results of a randomized, double-blind, dose-escalation phase 1/2a clinical trial evaluating the safety, tolerability, preliminary efficacy, and pharmacokinetics of the CPNE7-derived functional peptide (selcopintide) in patients with dentin hypersensitivity. In Part A (Single Ascending Dose, SAD), 24 participants received a single topical application of selcopintide at ascending doses (2.5, 5, and 10 μg/tooth) in a 6:2 randomization ratio (treatment: placebo). In Part B (Multiple Ascending Dose, MAD), 16 participants received three topical applications (5 and 10 μg/tooth) over 15 days (day 1, 8, and 15; visits 2-4) with the same randomization ratio. Efficacy endpoints were assessed by changes in cold water, evaporative air, and tactile sensitivity. In Part B, the 10 μg selcopintide group demonstrated statistically significant reductions from the baseline across all three measures (p < 0.05), with a mean decrease of -23.2 ± 19.4 mm in VAS, the primary efficacy endpoint. All doses were well tolerated, with no serious adverse events and no detectable systemic absorption of selcopintide. These findings support the safety, tolerability, and preliminary efficacy of selcopintide as a novel therapeutic candidate for the treatment of dentin hypersensitivity.

Introduction To develop a calcium silicate (CaSi)-based cement containing dimethyl sulfoxide (DMSO) and cement deliver device for new root canal filling technique, and to assess the flow behavior, leakage, and root canal filling quality of CaSi containing DMSO.Methods CaSi containing DMSO (CSC-DMSO) and CaSi containing PEG (CSC-PEG) were prepared, and the flow characteristics of both cements were compared in gypsum and resin channels using a high-speed camera. Eight root canals were obturated by CSC-DMSO or CSC-PEG using a cement delivery device, and root canal filling quality was assessed in terms of filling length using periapical radiographs. The filling length was evaluated by 'apico-coronal extension,' measuring length in reference to apical constriction. Microleakage was measured for thirty human molars that were randomly filled with CSC-DMSO, CSC-PEG, or gutta-percha and AH plus. Preliminary obturation of CSC-DMSO with cement delivery device in human teeth was analyzed in terms of filling length and void, using periapical radiographs. Statistical analysis was performed with the Kruskal Wallis test for simulated root canal fillings and one-way ANOVA for leakage test.Results The flow speed of CSC-DMSO reduced in gypsum channels compared to resin channels, but CSC-PEG did not exhibit significant differences in the channels. The median absolute value of apico-coronal extension was significantly lower in CSC-DMSO compared to CSC-PEG (p < 0.05). Microleakage did not statistically differ between the groups (p > 0.05). In the preliminary obturation, the mean apico-coronal extension of CSC-DMSO was -0.297 +/- 0.724 mm, while CSC-PEG was not feasible due to excess apical extrusions.Conclusions CSC-DMSO could be considered as an alternative filling material for root canal obturation.

Abstract A reverse-transcriptase-subunit of telomerase (hTERT) derived peptide has been identified as a cell-penetrating peptide (CPP) in our previous study. This hTERT derived CPP was delivered into a variety of cells including various cancer cell lines and primary blood cells. Moreover, the CPP was predominantly located in the cytoplasm of the cells, while a significantly higher proportion of TAT peptide was localized in the nucleus. In order to reduce adverse non-specific toxic side effects of current anticancer drug, we developed cancer-specific anticancer drug delivery system using hTERT derived CPP. The cell penetrating activity was Pep 98, a specific hTERT derived CPP, was evaluated in head and neck cancer cells. The permeability of specific telomerase derived Pep 98-FITC into cancer cells was 20-300 fold higher than control peptide groups in head and neck cancer cells. These result suggest that pep98 can be used to reduce the side effects and increase the efficacy of cancer therapy through the use of specific anticancer drug delivery system.We conjugated Pep 98 with STAT 3 inhibitor (NSC74859) which has been presented as a molecular therapeutic target for head and neck cancer and evaluated concentration of NSC74589 for anti-cancer activity in head and neck cancer cell line. The result showed that the concentration of Pep-98 conjugated NSC74589 could be reduced up to 1/10-20 dose level compared with NSC74589 alone in head and neck cancer cells. Pep 98-NSC74859 conjugates were found to be capable of specific killing head and neck cancer cells without affecting normal fibroblast cells.We have confirmed the possibility of developing a new head neck cancer anticancer drug with improved therapeutic efficacy through the conjugation of the STAT3 inhibitor with hTERT derived peptide. Citation Format: Yoon Seon Lee, Myung Jin Lee, Won Jun Shon. Identification of cancer-specific CPP from human telomerase peptide library and its drug delivery potential in anti-cancer strategy [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A029.

AIM:To evaluate the efficacy of a novel ultrasonic irrigation device, remotely-generated irrigation with a non-invasive sound field enhancement (RINSE) system, in removing biofilm-mimicking hydrogel from a simulated isthmus model and compare it with sonically- and ultrasonically-activated irrigation systems. METHODOLOGY:A polycarbonate root canal model containing two standardized root canals (apical diameter of 0.20 mm, 4% taper, 18 mm long with a coronal reservoir) connected by three isthmuses (0.40 mm deep, 2 mm high, 4 mm long) was used as the test model. The isthmuses were filled with a hydroxyapatite powder-containing hydrogel. The canals were filled with irrigant, and the models were randomly assigned to the following activation groups (n = 15): EndoActivator (EA), ultrasonically activated irrigation (UAI), and RINSE system (RS). Syringe irrigation (SI) with a 30G needle served as the control. Standardized images of the isthmuses were taken before and after irrigation, and the amount of hydrogel removed was determined using image analysis software and compared across groups using anova (p < .05). RESULTS:Hydrogel removal was significantly higher with the RS (83.7%) than with UAI, EA, or SI (p ≤ .01). UAI (69.2%) removed significantly more hydrogel than SI and EA (p < .05), while there was no significant difference between SI (24.3%) and EA (25.7%) (p = .978). CONCLUSIONS:RINSE system resulted in the most hydrogel removal, performing better than UAI or EA. The effect of RS was also not reliant on the insert or tip entering the pulp chamber or root canal, making it particularly useful in conservative endodontics.

Regenerative dentistry has rapidly progressed since the advancement of stem cell biology and material science. However, more emphasis has been placed on the success of tissue formation than on how well the newly generated tissue retains the original structure and function. Once dentin is lost, tertiary dentinogenesis can be induced by new odontoblastic differentiation or re-activation of existing odontoblasts. The characteristic morphology of odontoblasts generates the tubular nature of dentin, which is a reservoir of fluid, ions, and a number of growth factors, and protects the inner pulp tissue. Therefore, understanding the dynamic but delicate process of new dentin formation by odontoblasts, or odontoblast-like cells, following dentinal defects is crucial. In this regard, various efforts have been conducted to identify novel molecules and materials that can promote the regeneration of dentin with strength and longevity. In this review, we focus on recent progress in dentin regeneration research with biological molecules identified, and discuss its potential in future clinical applications.

Once tooth development is complete, odontoblasts and their progenitor cells in the dental pulp play a major role in protecting tooth vitality from external stresses. Hence, understanding the homeostasis of the mature pulp populations is just as crucial as understanding that of the young, developing ones for managing age-related dentinal damage. Here, it is shown that loss of Cpne7 accelerates cellular senescence in odontoblasts due to oxidative stress and DNA damage accumulation. Thus, in Cpne7-null dental pulp, odontoblast survival is impaired, and aberrant dentin is extensively formed. Intraperitoneal or topical application of CPNE7-derived functional peptide, however, alleviates the DNA damage accumulation and rescues the pathologic dentin phenotype. Notably, a healthy dentin-pulp complex lined with metabolically active odontoblasts is observed in 23-month-old Cpne7-overexpressing transgenic mice. Furthermore, physiologic dentin was regenerated in artificial dentinal defects of Cpne7-overexpressing transgenic mice. Taken together, Cpne7 is indispensable for the maintenance and homeostasis of odontoblasts, while promoting odontoblastic differentiation of the progenitor cells. This research thereby introduces its potential in oral disease-targeted applications, especially age-related dental diseases involving dentinal loss.

Post-operative sensitivity (POS) is the most common clinical dental complaint after tooth preparation and resin-based composite restoration. In our previous study, copine 7 (CPNE7) and CPNE7-derived peptide (CPNE7-DP) induced in vitro odontoblast differentiation and in vivo dentin formation. Here, we incorporated CPNE7-DP into All-Bond Universal (ABU) adhesive, developing ABU/CPNE7-DP. This study aimed to investigate the possibility of reducing POS using ABU/CPNE7-DP. We first determined the stability of CPNE7-DP under low pH. Furthermore, we evaluated its dentinal tubule penetration, in vitro odontogenic differentiation potential, in vivo tertiary dentin formation and its effects on bonding performance. CPNE7-DP was stable at pH 1.2, even lower than ABU's pH of 3.2. ABU/CPNE7-DP can penetrate dentinal tubules, stimulate odontoblast differentiation in vitro and generate tertiary dentin with tubular structure in vivo without interfering with bonding performance. Therefore, ABU/CPNE7-DP may serve as a novel bioactive adhesive for reducing POS.

Resin-based dental composites have been developed to restore decayed teeth or modify tooth color due to their excellent physical and chemical properties. Such composites may have intrinsic toxicity due to components released into the mouth during the early stage of polymerization, and afterward as a result of erosion or material decomposition. In addition, resin-based dental composites have potential environmental pollutant by elution of monomers and degradation. Since certain monomers of resin matrices are synthesized from bisphenol A (BPA), which acts as an estrogenic endocrine disruptor, these resin matrices may have estrogenic activity. Therefore, the estrogenic endocrine-disrupting activity of various dental composites should be evaluated. In this study, we evaluated the estrogenic endocrine-disrupting activity of 10 resin composites by using a BRET-based estrogen receptor (ER)α and ERβ dimerization assays and ER transactivation assay. BPA, BisDMA, BisGMA, BisEMA, TEGDMA, HMBP, and DMPA mediated ERα dimerization, and BPA, BisDMA, and DMPA also mediated ERβ dimerization. Except for UDMA and CQ, all the compounds were identified as estrogen agonists or antagonists. In-depth information for the safe use of dental composites was acquired, and it was confirmed how the component of dental composites acts in the ER signaling pathway. Further studies on the low-dose and long-term release of these compounds are needed to ensure the safe use of these resin-based dental composites.

To evaluate the efficacy of a novel ultrasonic irrigation device, remotely-generated irrigation with a non-invasive sound field enhancement (RINSE) system, in removing biofilm-mimicking hydrogel from a simulated isthmus model and compare it with sonically- and ultrasonically-activated irrigation systems. A polycarbonate root canal model containing two standardized root canals (apical diameter of 0.20 mm, 4% taper, 18 mm long with a coronal reservoir) connected by three isthmuses (0.40 mm deep, 2 mm high, 4 mm long) was used as the test model. The isthmuses were filled with a hydroxyapatite powder-containing hydrogel. The canals were filled with irrigant, and the models were randomly assigned to the following activation groups ( n  = 15): EndoActivator (EA), ultrasonically activated irrigation (UAI), and RINSE system (RS). Syringe irrigation (SI) with a 30G needle served as the control. Standardized images of the isthmuses were taken before and after irrigation, and the amount of hydrogel removed was determined using image analysis software and compared across groups using anova ( p  < .05). Hydrogel removal was significantly higher with the RS (83.7%) than with UAI, EA, or SI ( p  ≤ .01). UAI (69.2%) removed significantly more hydrogel than SI and EA ( p  < .05), while there was no significant difference between SI (24.3%) and EA (25.7%) ( p  = .978). RINSE system resulted in the most hydrogel removal, performing better than UAI or EA. The effect of RS was also not reliant on the insert or tip entering the pulp chamber or root canal, making it particularly useful in conservative endodontics.

Root canal treatment is performed to remove the bacteria proliferating in the root canals of a tooth. Many conventional root canal irrigation methods use an instrument inserted into the root canals. However, bacteria removal is often incomplete in the apical region of the root canal, and the treatment carries clinical risks, such as instrument fracture and extrusion of irrigation liquid through the canal apex. We here suggest a novel, remotely generated high-intensity ultrasound irrigation system that exhibits better irrigation performance and a reduced clinical risk. Our device employs powerful ultrasonic waves generated by a transducer placed outside a target tooth. The generated ultrasonic waves are guided to travel into the root canals. In the root canals of the target tooth, acoustic cavitation occurs, and vapor bubbles are created. The dynamic motions of vapor bubbles create remarkable cleaning effects. Using root canal models, we tested the cleaning performance of the proposed system and compared it with other conventional irrigation methods. The results revealed that biofilm in the apical region of the root canal models can be removed exclusively using the proposed system, thus demonstrating an improvement in cleaning performance. We also measured pressure at the apex of the root canals of an extracted tooth while operating the proposed system. Our system exhibited a smaller pressure compared to the syringe irrigation method, thus suggesting a reduced risk of apical extrusion of the irrigation liquid. Since the proposed system operates without inserting instruments into the root canal, it can clean multiple root canals in a tooth simultaneously with a single treatment. The proposed device would be a breakthrough in root canal treatment in terms of irrigation performance, clinical safety, and ease of treatment.

This study aimed to investigate in vitro biologic properties of mineral trioxide aggregate (MTA) mixed with 3% PVA (MTA-3% PVA) and in vivo dental pulp responses to direct capping in comparison with MTA mixed with distilled water (MTA-DW). Cell proliferation and osteogenic differentiation in culture of human dental pulp cells (hDPCs), and pH changes were evaluated. Pulps in 24 mandibular premolars of four 9-month-old beagle dogs were mechanically exposed and direct pulp capping was performed. Histological specimens were scored according to the degree of mineralization. MTA-3% PVA showed similar cell proliferation and similar or superior osteogenic differentiation of hDPCs compared with MTA-DW. All specimens were associated with calcified bridge formation and there were no significant differences in mineralization scores between the groups (p>0.05). The results suggested that MTA-3% PVA exhibited favorable biocompatibility and osteogenic differentiation in vitro compared with MTA-DW. Furthermore, both groups demonstrated similar results when used as pulp-capping agents in vivo.

Objective: CPNE7-derived functional peptide (CPNE7-DP) has been introduced as a bioactive therapeutics for dentin diseases. CPNE7-DP regenerates tubular dentin on the pulpal side and occlude dentinal tubules. CPNE7-DP was capable to treat dentin hypersensitivity typically associated with dentinal wear at the neck of the tooth. However, the role of CPNE7-DP in another common dentin disease, dental caries, remains uninvestigated. In this study, we evaluated the potential application of CPNE7-DP in dentin caries using an experimental dentin caries model in rats. Design: The stability of CPNE7-DP in caries-like environments including pathologic bacteria of caries or low pH was tested. We established a nutrition-time/hyposalivation-based dental caries rat model by inoculating caries -inducing bacteria and diet for sufficient time. Glycopyrrolate has been treated to induce reversible hypo -salivation for accelerating caries progression. Then the tubular dentin regeneration was investigated with his-tologic methods. Also, modulation of inflammation or autophagy by CPNE7-DP was investigated with marker gene expression in human dental pulp cells (hDPCs) and immunohistochemistry. Results: CPNE7-DP was stable with caries-inducing bacteria and low pH. Establishment of dentin caries was confirmed with radiographic and histologic evaluation. CPNE7-DP regenerated a substantial amount of tubular tertiary dentin and alleviated the pulp inflammation of dentin caries. Under inflammatory conditions, CPNE7-DP reduced the expression of inflammatory cytokines. These phenomena could be the consequence of the modu-lation of autophagy by CPNE7-DP, which reactivates inflamed odontoblasts. Conclusions: Overall, CPNE7-DP, which repairs caries through physiological dentin regeneration, might help overcoming the limitations of current restorative caries treatments.

The dynamic actions of cavitation bubbles in ultrasonic fields can clean surfaces. Gas and vapor cavitation bubbles exhibit different dynamic behaviors in ultrasonic fields, yet little attention has been given to the distinctive cleaning effects of gas and vapor bubbles. We present an experimental investigation of surface cleaning by gas and vapor bubbles in an ultrasonic field. Using high-speed videography, we found that the primary motions of gas and vapor bubbles responsible for surface cleaning differ. Our cleaning tests under different contamination conditions in terms of contaminant adhesion strength and surface wettability reveal that vapor and gas bubbles are more effective at removing contaminants with strong and weak adhesion, respectively, and furthermore that hydrophobic substrates are better cleaned by vapor bubbles. Our study not only provides a better physical understanding of the ultrasonic cleaning process, but also proposes novel techniques to improve ultrasonic cleaning by selectively employing gas and vapor bubbles depending on the characteristics of the surface to be cleaned.

This study aimed to investigate effects of caries activity on composition of mutans streptococci in saliva-induced biofilms formed on bracket materials. Three bracket materials were used as specimens: ceramic, metal, and plastic. After saliva was collected using a spitting method from caries-active (CA, decayed, missing, filled teeth (DMFT) score ≥ 10) and caries-free (CF, DMFT score = 0) subjects, saliva was mixed with growth media in a proportion of 1:10. The saliva solution was then incubated with each bracket material. After a saliva-induced biofilm was developed on the surface of the bracket material, the amounts of total bacteria and mutans streptococci were determined using real-time polymerase chain reaction. The results showed that biofilms from CA saliva contained more mutans streptococci but less total bacteria than biofilms from CF saliva, regardless of material type. Adhesion of total bacteria to ceramic was higher than to plastic, regardless of caries activity. Mutans streptococci adhered more to ceramic than to metal and plastic in both biofilms from CA and CF saliva, but there was a difference in adhesion between Streptococcus mutans and Streptococcus sobrinus. The amount of S. mutans was higher than that of S. sobrinus in biofilms from CA saliva despite similar amounts of the two strains in biofilms from CF saliva. The stronger adhesion of S. mutans to ceramic than to metal and plastic was more evident in biofilms from CA saliva than in biofilms from CF saliva. This study suggests that caries activity and material type significantly influenced composition of mutans streptococci in biofilms formed on bracket materials.

To obtain radicular measurements of two separate mesiobuccal (MB) root canals in maxillary first molars using micro-computed tomography (μCT) with customized software. Human maxillary first molar MB roots (N = 36) with two separate canals (MB1, MB2) and apical foramina were scanned by μCT and analyzed with Kappa2 software to reconstruct three-dimensional (3D) surface models of roots and canals. These models were sectioned at 0.1 mm intervals perpendicular to the central axis of each canal. Canal widths, 3D curvatures, and surrounding dentine thicknesses were measured concurrently on each section. Dentine thicknesses were analyzed statistically for differences between each direction and the different levels of both canals. Dentine walls around MB1 were thicker than MB2 (p < 0.05). Thinnest dentine was most often located at disto-inside direction in both canals. Canal widths were significantly smaller in MB2 than MB1 (p < 0.01). Apical constrictions were smaller (p < 0.05) and further (p < 0.05) from the apex in MB2 than MB1. Canal curvatures were greatest in the apical third of both canals (p < 0.001), and they were greater in MB2 than MB1 (p < 0.05). MB2 canals had shorter lengths, smaller widths, and more severe curvatures and were surrounded by thinner dentine walls. In MB2, apical constrictions were between 1 and 2 mm from the apex, compared to about 1 mm for MB1. These detailed measurements and in-depth 3D analyses of maxillary first molar MB roots with two separate canals and apical foramina provide morphologic references for root canal therapy.

Biofilm communities are tolerant to antimicrobials and difficult to eradicate. This study aimed to investigate the effect of melittin, an antimicrobial peptide, either alone or in combination with deoxyribonuclease (DNase), an inhibitor of extracellular deoxyribonucleic acid (eDNA), against Enterococcus faecalis (E. faecalis) biofilms, and biofilm susceptibility to sodium hypochlorite (NaOCl). Biofilms of E. faecalis were developed in root canals of bovine teeth. The biofilms were treated with distilled water (control), melittin, DNase, or DNase+melittin. The antibiofilm effects of the treatments were analyzed using colony forming unit (CFU) assay, crystal violet staining, confocal laser scanning microscopy (CLSM), and field emission scanning electron microscope (FE-SEM). The susceptibility of DNase+melittin-treated biofilms to NaOCl (0%, 2.5% and 5%) was investigated by the CFU assay. The data were statistically analyzed using one-way analysis of variance, followed by Tukey's test. A p-value of <0.05 was considered significant. Specimens treated with DNase+melittin showed a more significant decrease in the CFUs, eDNA level, and biofilm formation rate than those treated only with melittin or DNase (p < 0.05). CLSM analysis showed DNase+melittin treatment significantly reduced the volume of biofilms and extracellular polymeric substance compared to either treatment alone (p < 0.05). FE-SEM images showed a high degree of biofilm disruption in specimens that received DNase+melittin. 2.5% NaOCl in specimens pretreated with DNase+melittin showed higher antibacterial activity than those treated only with 5% NaOCl (p < 0.05). This study highlighted that DNase improved the antibiofilm effects of melittin. Moreover, DNase+melittin treatment increased the susceptibility of biofilms to NaOCl. Thus, the complex could be a clinical strategy for safer use of NaOCl by reducing the concentration.