Present status and future directions:Apexification

The success rate of apexification is primarily determined by multiple factors,including the material used,the size of the open apex compared to the length of the root,and the technique used in each case.The main objective of this review was to provide an update on the present management of open apex to identify factors and circumstances that may influence the success of apexification using different materials and techniques.Future research on apexification should focus on how to treat open apices with wide periapical lesions without surgery.Previously,the predictability of these parameters with non-surgical procedures was uncertain,but now,with the use of a dental operating microscope,it has become more predictable.Another reason could be that extra visits are no longer required due to major advances in the armamentarium and materials used for apexification.

Recent advances in imaging technologies in dentistry

Dentistry has witnessed tremendous advances in all its branches over the past three decades. With these advances, the need for more precise diagnostic tools,specially imaging methods, have become mandatory.From the simple intra-oral periapical X-rays, advanced imaging techniques like computed tomography, cone beam computed tomography, magnetic resonance imaging and ultrasound have also found place in modern dentistry. Changing from analogue to digital radiography has not only made the process simpler and faster but also made image storage, manipulation(brightness/contrast, image cropping, etc.) and retrieval easier. The three-dimensional imaging has made the complex cranio-facial structures more accessible for examination and early and accurate diagnosis of deep seated lesions. This paper is to review current advances in imaging technology and their uses in different disciplines of dentistry.

A multi-platform analysis of human gingival crevicular fluid reveals ferroptosis as a relevant regulated cell death mechanism during the clinical progression of periodontitis

Ferroptosis is implicated in the pathogenesis of numerous chronic-inflammatory diseases,yet its association with progressive periodontitis remains unexplored.To investigate the involvement and significance of ferroptosis in periodontitis progression,we assessed sixteen periodontitis-diagnosed patients.Disease progression was clinically monitored over twelve weeks via weekly clinical evaluations and gingival crevicular fluid(GCF)collection was performed for further analyses.Clinical metrics,proteomic data,in silico methods,and bioinformatics tools were combined to identify protein profiles linked to periodontitis progression and to explore their potential connection with ferroptosis.Subsequent western blot analyses validated key findings.Finally,a single-cell RNA sequencing(scRNA-seq)dataset(GSE164241)for gingival tissues was analyzed to elucidate cellular dynamics during periodontitis progression.Periodontitis progression was identified as occurring at a faster rate than traditionally thought.GCF samples from progressing and non-progressing periodontal sites showed quantitative and qualitatively distinct proteomic profiles.In addition,specific biological processes and molecular functions during progressive periodontitis were revealed and a set of hub proteins,including SNCA,CA1,HBB,SLC4A1,and ANK1 was strongly associated with the clinical progression status of periodontitis.Moreover,we found specific proteins-drivers or suppressors-associated with ferroptosis(SNCA,FTH1,HSPB1,CD44,and GCLC),revealing the co-occurrence of this specific type of regulated cell death during the clinical progression of periodontitis.Additionally,the integration of quantitative proteomic data with scRNA-seq analysis suggested the susceptibility of fibroblasts to ferroptosis.Our analyses reveal proteins and processes linked to ferroptosis for the first time in periodontal patients,which offer new insights into the molecular mechanisms of progressive periodontal disease.These findings may lead to novel diagnostic and therapeutic strategies.

Expert consensus on endodontic therapy for patients withsystemic conditions

The overall health condition of patients significantly affects the diagnosis, treatment, and prognosis of endodontic diseases. Asystemic consideration of the patient’s overall health along with oral conditions holds the utmost importance in determining thenecessity and feasibility of endodontic therapy, as well as selecting appropriate therapeutic approaches. This expert consensus is acollaborative effort by specialists from endodontics and clinical physicians across the nation based on the current clinical evidence,aiming to provide general guidance on clinical procedures, improve patient safety and enhance clinical outcomes of endodontictherapy in patients with compromised overall health.

Magnification:The game changer in dentistry

During dental examinations and treatments,many dentists are using magni-fication to improve their vision.The dental operating microscope serves as the most effective tool for this purpose,enhancing the quality,longevity,and outcome of clinical work.This review will explore the latest research and data on the importance of magnification devices in dentistry,including diagnostic methods,treatment options and ergonomics in specialities such as restorative dentistry,endodontics,pedodontics,periodontics,and prosthodontics.This review aims to provide insights into the optimal magnification for different clinical situations,the specific benefits of dental operating microscopes for each dental branch,and their limitations.

Long-term observation of the mineral trioxide aggregate extrusion into the periapical lesion:a case series

One-step apexification using mineral trioxide aggregate(MTA) has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide for teeth with open apex.However,orthograde placement of MTA is a challenging procedure in terms of length control.This case series describes the sequence of events following apical extrusion of MTA into the periapical area during a one-step apexification procedure for maxillary central incisor with an infected immature apex.Detailed long-term observation revealed complete resolution of the periapical radiolucent lesion around the extruded MTA.These cases revealed that direct contact with MTA had no negative effects on healing of the periapical tissues.However,intentional MTA overfilling into the periapical lesion is not to be recommended.

Long-term follow-ups of revascularized immature necrotic teeth:three case reports

Revascularization of immature necrotic teeth is a reliable treatment alternative to conventional apexogenesis or apexification. In case 1, a 12-year-old boy had his necrotic, immature mandibular left second premolar treated with a revascularization technique. At a 24-month follow-up, periapical radiolucency had disappeared and thickening of the root wall was observed. In cases 2 and 3, a lO-year-old boy had his necrotic, immature, bilateral mandibular second premolars treated with the same modality. At 48-month （in case 2） and 42-month （in case 3） follow-ups, loss of periapical radiolucencies and increases in the root wall thickness were also observed.

Antimicrobial effect of alexidine and chlorhexidine against Enterococcus faecalis infection

A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine.The aim of this study was to compare the antimicrobial activity of 1%alexidine with that of 2%chlorhexidine using Enterococcus faecalis-infected dentin blocks.Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each.E.faecalis was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2%chlorhexidine or 1%alexidine solutions for 5 and 10 min,respectively.Sterile saline was used as a control.The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope.Significantly fewer bacteria were observed in the 2%chlorhexidine-or 1%alexidine-soaked groups than in the control group(P<0.05).However,there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups(P>0.05).Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups.In conclusion,10-min soaking with 1%alexidine or 2%chlorhexidine can be effective against E.faecalis infection.

Caffeic acid phenethyl ester protects against oxidative stress and dampens inflammation via heme oxygenase 1

Periodontal disease is associated with chronic oxidative stress and inflammation. Caffeic acid phenethyl ester(CAPE), which is a potent inducer of heme oxygenase 1(HO1), is a central active component of propolis, and the application of propolis improves periodontal status in diabetic patients. Here, primary murine macrophages were exposed to CAPE. Target gene expression was assessed by whole-genome microarray, RT-PCR and Western blotting. The antioxidative and anti-inflammatory activities of CAPE were examined by exposure of the cells to hydrogen peroxide, saliva and periodontal pathogens. The involvement of HO1 was investigated with the HO1 inhibitor tin protoporphyrin(SnPP) and knockout mice for Nrf2, which is a transcription factor for detoxifying enzymes. CAPE increased HO1 and other heat shock proteins in murine macrophages. A p38 MAPK inhibitor and Nrf2 knockout attenuated CAPE-induced HO1 expression in macrophages. CAPE exerted strong antioxidative activity. Additionally, CAPE reduced the inflammatory response to saliva and periodontal pathogens. Blocking HO1 decreased the antioxidative activity and attenuated the anti-inflammatory activity of CAPE. In conclusion, CAPE exerted its antioxidative effects through the Nrf2-mediated HO1 pathway and its anti-inflammatory effects through NF-κB inhibition. However, preclinical models evaluating the use of CAPE in periodontal inflammation are necessary in future studies.

Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

All-trans retinoic acid（ATRA） inhibits matrix metalloproteinase（MMP）-2 and MMP-9 in synovial fibroblasts, skin fibroblasts,bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells（HDPCs）. The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA（mRNA） expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction（PCR）, respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol？L21ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs,which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

Maxillary first molar with an O-shaped root morphology:report of a case

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography （CBCT） were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root.

Dental pulp stem cells-derived schwann cells for peripheral nerve injury regeneration

The peripheral nervous system（PNS）has an intrinsic ability for repair and regeneration even after severe injury.Peripheral nerve injury is followed by the normal rapid progression of Wallerian degeneration（anterograde or orthograde degeneration）.During this process,the distal detached nerve segment degenerates.

Calcium Hydroxide Removal in Curved Root Canals with Apical Transportation In Vitro

Calcium hydroxide（CH） is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files（K file, pre-curved K file, EndoActivator, Ultrasonic file, pre-curved ultrasonic file, F file and needle irrigation alone） with apical transportation. Standardized models of curved canal with such apical transportation or not were set up before applying CH to root canal for 7 days. Seven techniques described above were used for its removal. Then the roots were disassembled and digital photos were taken. The ratio of residual CH in the overall canal surface was calculated using the image analyzer image pro plus 6.0. The data were analyzed using one-way ANOVA with post hoc Tukey test. Results revealed that CH was effectively removed（P〈0.05） by using all 6 mechanical methods except irrigation alone. In curved root canals with apical transportation, EndoActivator, pre-curved ultrasonic file and F file were found to be more effective in removing CH than the other four file（P〈0.001）, while there was no significant difference among EndoActivator, pre-curved ultrasonic file and F file groups（P〉0.05）. The percentage of residual CH in the canal with apical transportation was higher than that in the canal without apical transportation（P〈0.05）. In conclusion, CH can be hardly removed completely. Canal with apical transportation will result in insufficient CH removal. EndoActivator, pre-curved ultrasonic file and F file are more effective in the curved root canal with apical transportation.

Antibacterial activity of nanostructured Ti-45S5 bioglass-Ag composite against Streptococcus mutans and Staphylococcus aureus

Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.

Role of the CXCR4-SDF1-HMGB1 pathway in the directional migration of cells and regeneration of affected organs

In recent years,several studies have reported positive outcomes of cell-based therapies despite insufficient engraftment of transplanted cells.These findings have created a huge interest in the regenerative potential of paracrine factors released from transplanted stem or progenitor cells.Interestingly,this notion has also led scientists to question the role of proteins in the secretome produced by cells,tissues or organisms under certain conditions or at a particular time of regenerative therapy.Further studies have revealed that the secretomes derived from different cell types contain paracrine factors that could help to prevent apoptosis and induce proliferation of cells residing within the tissues of affected organs.This could also facilitate the migration of immune,progenitor and stem cells within the body to the site of inflammation.Of these different paracrine factors present within the secretome,researchers have given proper consideration to stromal cell-derived factor-1(SDF1)that plays a vital role in tissue-specific migration of the cells needed for regeneration.Recently researchers recognized that SDF1 could facilitate site-specific migration of cells by regulating SDF1-CXCR4 and/or HMGB1-SDF1-CXCR4 pathways which is vital for tissue regeneration.Hence in this study,we have attempted to describe the role of different types of cells within the body in facilitating regeneration while emphasizing the HMGB1-SDF1-CXCR4 pathway that orchestrates the migration of cells to the site where regeneration is needed.

Microscopic removal of type Ⅲ dens invaginatus and preparation of apical barrier with mineral trioxide aggregate in a maxillary lateral incisor:A case report and review of literature

BACKGROUND Invaginated teeth pose greater challenges in clinical management because of their complex configuration.With advancements in equipment and materials,such as the dental operation microscope,cone-beam computed tomography and mineral trioxide aggregate,the preservation rate of type Ⅲ dens invaginatus could be greatly increased.CASE SUMMARY This case report presented a 31-year-old woman with complaints of spontaneous swelling and pain in the right maxillary lateral tooth.With the aid of cone-beam computed tomography,type Ⅲ dens invaginatus with apical periodontitis was diagnosed and confirmed.Three-visit endodontic treatment was performed.In the first visit,the invagination was carefully removed under the dental operation microscope,and chemomechanical preparation was done.In the second visit,mineral trioxide aggregate apical barrier surgery was performed in this tooth.In the third visit,the canal was finally obturated with thermoplastic gutta-percha to recover the crown morphology.A 26-mo follow-up revealed a satisfied outcome both in the radiographic and oral examinations.CONCLUSION In this case,removal of the entire abnormal structure provided great convenience for the follow-up treatment.When confronted with the same clinical case in the future,we can take a similar approach to address it.

Bacterial entombment by intratubular mineralization following orthograde mineral trioxide aggregate obturation: a scanning electron microscopy study

The time domain entombment of bacteria by intratubular mineralization following orthograde canal obturation with mineral trioxide aggregate（MTA） was studied by scanning electron microscopy（SEM）. Single-rooted human premolars（n560） were instrumented to an apical size #50/0.06 using ProF ile and treated as follows： Group 1（n510） was filled with phosphate buffered saline（PBS）; Group 2（n510） was incubated with Enterococcus faecalis for 3 weeks, and then filled with PBS; Group 3（n520） was obturated orthograde with a paste of OrthoM TA（BioM TA, Seoul, Korea） and PBS; and Group 4（n520） was incubated with E. faecalis for 3 weeks and then obturated with OrthoM TA–PBS paste. Following their treatments, the coronal openings were sealed with PBS-soaked cotton and intermediate restorative material（IRM）, and the roots were then stored in PBS for 1, 2, 4, 8 or 16 weeks. After each incubation period, the roots were split and their dentin/MTA interfaces examined in both longitudinal and horizontal directions by SEM. There appeared to be an increase in intratubular mineralization over time in the OrthoM TA-filled roots（Groups 3 and 4）. Furthermore, there was a gradual entombment of bacteria within the dentinal tubules in the E. faecalis inoculated MTA-filled roots（Group 4）. Therefore, the orthograde obturation of root canals with OrthoM TA mixed with PBS may create a favorable environment for bacterial entombment by intratubular mineralization.

Antibacterial activity of calcium hydroxide combined with chitosan solutions and the outcomes on the bond strength of RealSeal sealer to radicular dentin

The purpose of this study was to investigate the antibacterial activity of calcium hydroxide [Ca（OH）2] combined with chitosan solutions against Enterococcus faecalis-infected root canal dentin and the effect of this new intraca- nal medicament on the bond strength of RealSeal sealer to radicular dentin. An experimental intracanal medicament was prepared by mixing different concentrations of chitosan solution （25%, 50%, and 100%, W/V） to Ca（OH）2 powder. Antibacterial activity was evaluated and the total numbers of colony forming units were determined. Bonding ability of RealSeal sealer to radicular dentin was evaluated using push-out bond strength test. Data were analyzed using one-way analysis of variance （ANOVA） and Tukey＇s multiple comparison tests. We found that Ca（OH）2 combined with different concentrations of chitosan solutions showed better antibacterial activity than Ca（OH）2 mixed with saline, without significantly affecting the bond strength of RealSeal sealer to radicular dentin （P 〉 0.05）. The findings suggest that Ca（OH）2 combined with chitosan is a promising intracanal medicament and may be effective in endodontic therapy.

Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin （1 mm below the dentine-enamel junction）, deep dentin （1 mm above the highest pulp horn） and cervical dentin （0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction）. Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mrn/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin （P 〈 0.001）. Micro-ten- sile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions （P 〈 0.001）. Immediate ＂micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements （P 〈 0.001）. It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

Comparison of the rheological properties of four root canal sealers

The flowability of a root canal sealer is clinically important because it improves the penetration of the sealer into the complex root canal system. The purpose of this study was to compare the flowabilities of four root canal sealers, measured using the simple press method （ISO 6876）, and their viscosities, measured using a strain-controlled rheometer. A newly developed, calcium phosphate-based root canal sealer （Capseal） and three commercial root canal sealers （AH Plus, Sealapex and Pulp Canal Sealer EWT） were used in this study. The flowabilities of the four root canal sealers were measured using the simple press method （n= 5） and their viscosities were measured using a strain-controlled rheometer （n=5）. The correlation between these two values was statistically analysed using Spearman＇s correlation test. The flow diameters and the viscosities of the root canal sealers were strongly negatively correlated （p= -0.8618）. The viscosity of Pulp Canal Sealer EWT was the lowest and increased in the following order： AH Plus〈Sealapex〈Capseal （P〈0.05）. All of the tested root canal sealers showed characteristic time- and temperature-dependent changes in their rheological properties. The viscosities measured using the strain-controlled rheometer were more precise than the flowabilities measured using the simple press method, suggesting that the rheometer can accurately measure the rheological properties of root canal sealers.