[Application and exploration of artificial intelligence for caries management].

With the advent of big data era and improvement of computer performance, the artificial intelligence (AI) technology has rapidly boosted in the field of stomatology. Dental caries is one of the cutting-edge research domains in stomatology. The application of AI in dental caries is expected to promote intelligent, precise and high-efficient diagnosis and treatment of caries. This article focuses on the application of AI in medical-aided diagnosis, treatment and risk prediction of caries and discusses their challenges.

[Research progress in the pathogenesis mechanism of dental fluorosis].

Dental fluorosis is a developmental disturbance of dental enamel caused by excessive fluoride intake during tooth development, leading to the changes in morphology, structure and function of tooth enamel, which can affect the aesthetics and function of teeth. There are many factors which may account for the occurrence of dental fluorosis. However, the pathogenesis mechanism underlying dental fluorosis has not been fully clarified.In recent years, researches in the fields of fluoride-induced stress response pathways, signaling pathways and apoptosis at the molecular and genetic level had provided extensive knowledge of dental fluorosis. This article focuses on the latest research progress in the mechanism of dental fluorosis, which include the effects of fluoride on ameloblasts and enamel matrix proteins, genetic polymorphism and dietary nutrients, in order to provide new references for the targeted prevention and treatment of dental fluorosis.

[Applications of digital medical techniques for dental dysplasia].

Dental dysplasia are abnormalities in teeth structure, morphology, number and eruption caused by genetic and environmental factors during dental development. Digital medical techniques, as the current hot spot of medical research, bring great challenges and opportunities to modern stomatology. The applications of digital techniques, such as digital diagnosis method, digital virtual simulated design, three-dimensional printing, static and dynamic guidance and artificial intelligence, can provide a more accurate, efficient, automatic and intelligent modern concepts and patterns for epidemiology, diagnosis, multidisciplinary treatment and outcome assessment of dental developmental anomalies.

[Application and prospect of static/dynamic guided endodontics for managing pulpal and periapical diseases].

Root canal therapy and endodontic surgery are conventional treatments for pulpal and periapical diseases. Compared with naked-eye operations, the application of dental operating microscope has enhanced the procedural accuracy and prognosis efficiently. However, root canals with pulp calcification/obliteration, apical lesions with thick cortical bone or adjacent to important anatomic structures are even challenging for experienced operators to achieve predictable clinical outcomes. Recently, with the advances in the field of digitalized information sciences, the above mentioned complicated endodontic cases can be solved under static and dynamic guidance. Before the treatment begins, virtual path is designed from data collected by cone-beam CT and oral image scanning using guidance software. Afterwards, root canal therapy and endodontic surgery can be performed precisely under the assistance of three-dimensional printed guide or dynamic guidance system. The present review describes the classification, features and clinical applications of the guided endodontics.

[Development strategies and progress of composite resin filling material].

Composite resin filling material is the first choice for tooth direct bonding restoration. Its good performance can meet the requirements of clinical tooth repair treatment. It is used to restore the structure, aesthetic and function of defected teeth with a way of minimally invasive intervention. To further improve its clinical efficacy, the fundamental strategy is to ameliorate the limitation of material properties. Based on the summary of current research progress, this article focuses on the property of improved composite resin material, and the progress of developing novel resin material including antibacterial composite resin, bioactive remineralizing resin as well as self-healing resin, so as to provide innovative ideas for the future research of new composite resin filling materials.

[Etiology, diagnosis, prevention and treatment of dental fluorosis].

Dental fluorosis is the most common and prominent symptom in the early stage of chronic fluorosis, which is caused by excessive fluorine intake during tooth development. In severe cases, it may be accompanied by skeletal fluorosis. There are also systemic damages to the nervous system, cardiovascular system, endocrine system and so on. The pathogenesis of dental fluorosis is not totally clear, which may be a complex pathological process involving both genetic and environmental factors. The prevalence of dental fluorosis has an upward trend arround the world, thus certain public prevention and treatment strategies need to be taken. This article focuses on the prevalence, etiology, diagnosis and scoring system, as well as the public prevention and treatment strategies, of dental fluorosis, so that to provide reference for the research and prevention of the disease.

[Contemporary concept and clinical perspective of direct pulp capping therapy].

There are several trends in contemporary endodontics such as development of minimally invasive biologically based therapies, preservation of dental pulp in a healthy status with sustained vitality, prevention of apical periodontitis and improvement of long-term survival rates of teeth with pulpal disorders. As for the vital pulp therapy, direct pulp capping is a less invasive approach to keep the exposed dental pulp intact, which may improve the long-term treatment outcome employing a minimally invasive biologically strategy. With the recent progress in pulp biology, improvement of treatment modality and development of bioactive dental cements, great advancements have been achieved in direct pulp capping therapy. This review article focuses on the transition of indications, prognostic factors and future perspectives of direct pulp capping therapy, attempting to provide evidence and practical guidance for minimally invasive biologically based therapies of teeth with injured pulp.

[State of the art and perspective of pulp regeneration].

Recently, various levels of success have been achieved in dental pulp and dentin regeneration using latest techniques such as pulp revascularization, stem cell transplantation and cell homing. These cutting-edge technologies utilize stem cell mobilization, homing and directional differentiation, stem cell sub-population isolation, expansion and transplantation, modification and optimization of biomaterials and/or synergetic effects of biological cues. The objective of this review is to identify approaches for clinical translation and improve the success rates of pulp regeneration. We will focus on either basic and clinical research progress of dental pulp revascularization, or translational challenges and strategies of stem cell transplantation and cell homing in dental pulp regeneration.

[Naked cuticle homolog 2 positively regulates the osteogenic differentiation of rat dental follicle cells].

Objective: To examine the expression of naked cuticle homolog 2 (Nkd2) in the process of root development and osteogenic differentiation of dental follicle cells of rat (rDFC), in order to explore the molecular mechanisms of Nkd2 on the osteoblast differentiation of rDFCs. Methods: Immunohistochemical analysis was used to detect the expression of Nkd2 in the base dental follicle of the mandibular first molar of rat at 1, 3, 5, 7, 9, 11 and 13 days postnatal. Mineralization nodule formation of rDFCs was detected by alizarin red staining and cetylpyridine. The change of Nkd2 during osteogenic differentiation of rDFCs was evaluated by Western blotting and the associations between Nkd2 and osteogenic cytokines of alkaline phosphatase (ALP), Runt-related transcription factor-2 (RUNX2) and osteocalcin (OCN) were examined. The rDFCs were transfected with small interfering RNA (siRNA) to knock down the expression of Nkd2 and Western blotting and quantitative real-time PCR (qPCR) were adopted to explore the effects of Nkd2 on osteogenic differentiation by detecting variations of Nkd2 and osteogenic factors ALP, RUNX2, OCN among silencing group (Si), negative control RNA group (Nc) and mock control group (Mock), respectively. Results: The expression of Nkd2 in the base dental follicle of the mandibular first molar of rat was time dependent. Mineralization nodules of rDFCs and absorbance of cetylpyridine after osteogenic induction increased gradually (the absorbances of cetylpyridine were 0 week: 0.017±0.005, 1 week: 0.702±0.044, 2 weeks: 1.812±0.531, 3 weeks: 2.767±0.253, respectively). Results of Western blotting showed that Nkd2 (1.60±0.23) of mineralization group was significantly higher than that of control group (1) (P<0.05) at the early stage of osteogenic differentiation along with the expression of other osteogenic factors. The protein and mRNA of Nkd2 and osteogenic factors were significantly decreased in Si group compared with Nc and Mock groups (P<0.05), and no changes between Nc and Mock groups were observed. The changes of protein in Si, Nc and Mock groups were Nkd2: 0.42±0.10, 1.12±0.07, 1, ALP: 0.70±0.15, 1.11±0.14, 1, RUNX2: 0.58±0.08, 0.93±0.08, 1 and OCN: 0.64±0.06, 0.99±0.02, 1, respectively. The mRNA variances in Si, Nc and Mock groups were Nkd2: 0.39±0.05, 0.96±0.10, 1, ALP: 0.15±0.13, 1.01±0.07, 1, RUNX2: 0.39±0.31, 0.97±0.13, 1, OCN: 0.17±0.08, 1.08±0.21, 1, respectively. Conclusions: Nkd2 participates in the root development process in rat and may acts as a positive role in the early stage of osteogenic differentiation of rDFCs in rat.

[Formulation of guidelines for microscopic endodontics suitable for the situation of China].

In order to promote the use of dental operating microscope in endodontics, Society of Cariology and Endodontology of Chinese Stomatological Association formulated these guidelines, after extensive consultation with related authorities and careful reference to the available published materials and literatures. It is hoped that these guidelines will be useful for dental practitioners embarking on microscopic endodontics.

[Overall digitalization: leading innovation of endodontics in big data era].

In big data era, digital technologies bring great challenges and opportunities to modern stomatology. The applications of digital technologies, such as cone-beam CT(CBCT), computer aided design,(CAD)and computer aided manufacture(CAM), 3D printing and digital approaches for education , provide new concepts and patterns to the treatment and study of endodontic diseases. This review provides an overview of the application and prospect of commonly used digital technologies in the development of endodontics.

Cetylpyridinium chloride suppresses gene expression associated with halitosis.

OBJECTIVE: Halitosis is a common complaint affecting the majority of the population. Mouthrinses containing cetylpyridinium chloride (CPC) have been used as oral hygiene aids to suppress oral malodor. Although the clinical efficacy of these mouthrinses has been well-documented, the mechanism whereby CPC reduces malodor is less-well-understood. We hypothesized that CPC suppresses expression of the genes (mgl and cdl) and enzymes responsible for methyl mercaptan (CH3SH) and hydrogen sulfide (H2S) production by oral anaerobes associated with halitosis. In this study, the mgl and cdl expression of Porphyromonas gingivalis and Fusobacterium nucleatum in the presence of CPC was investigated. MATERIALS AND METHODS: We used a microdilution method to determine the growth and production of volatile sulfur compounds (VSCs) by P. gingivalis W83 and F. nucleatum ATCC 10953 in respective media containing CPC (0.5 µg/mL to 1.5 µg/mL). For metabolic activity, we used an XTT {2,3-bis(2-methyloxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide} reduction assay. We used real-time RT-PCR and Western blotting to evaluate the effect of CPC at sub-MIC levels on mgl and cdl expression at the transcriptional and enzymatic levels. RESULTS: CPC inhibited the growth of P. gingivalis and F. nucleatum at MICs of 3 µg/mL and 2 µg/mL, and at MBCs of 6 µg/mL and 3 µg/mL, respectively. Compared with untreated controls, CPC at 1.5 µg/mL suppressed CH3SH production of P. gingivalis by 69.84%±2.88% and H2S production of F. nucleatum by 82.55%±8.36% (p<0.05) without affecting metabolic activity. Inhibition of mgl mRNA (81.58%±20.33%) and protein (39.15%±6.65%) expression in P. gingivalis and inhibition of cdl mRNA (61.76%±13.75%) and protein (64.34%±1.62%) expression in F. nucleatum were also noted (p<0.05). CONCLUSION: CPC represents an effective agent for halitosis reduction by inhibiting the growth and suppressing the expression of specific genes related to VSC production in anaerobic periodontal pathogens.

p38a MAPK is involved in BMP-2-induced odontoblastic differentiation of human dental pulp cells.

AIM: To investigate whether the p38α mitogen-activated protein kinases (MAPK) is involved in bone morphogenetic protein (BMP)-2-induced odontoblastic differentiation of human dental pulp cells (HDPCs). METHODOLOGY: Recombinant retrovirus encoding shRNA against p38α MAPK was constructed to investigate the role of p38α MAPK on BMP-2-induced odontoblastic differentiation of HDPCs. HDPCs were transfected with retrovirus expressing sh-p38α. Activation of p38α MAPK was detected by Western blot. The effects of p38α MAPK on BMP-2-induced odontoblastic differentiation of HDPCs were measured by alkaline phosphatase (ALP) activity, and the expression of odontoblastic markers was identified by quantitative real-time polymerase chain reaction analysis. The effect of SD-282, a p38a-specific inhibitor, on BMP-2-induced odontoblastic differentiation was also investigated. RESULTS: BMP-2 dose- and time-dependently upregulated phosphorylation of p38α of HDPCs. Compared with BMP-2-treatment group, gene knock-down of p38α MAPK significantly inhibited ALP activity and the formation of mineralized nodules in HDPCs. Moreover, suppression of p38α MAPK repressed the odontoblastic differentiation in HDPCs. Consistently, inhibition of p38α by SD-282 also decreased odontoblastic differentiation. CONCLUSIONS: p38α MAPK is involved in BMP-2-induced odontoblastic differentiation of HDPCs.

Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals.

AIM: To evaluate the efficacy of the ProTaper Universal rotary retreatment system for gutta-percha (GP) removal from root canals. METHODOLOGY: Root canals of 60 extracted human maxillary anterior teeth were prepared and filled with laterally condensed GP and AH Plus sealer. Teeth were divided into three groups: group A--GP removal completed with the ProTaper Universal rotary retreatment system and with further canal repreparation accomplished with ProTaper Universal rotary instruments; group B--GP removal was completed using Gates Glidden drills and Hedström files with chloroform as a solvent, followed with further canal repreparation with ProTaper Universal rotary instruments; group C--the same as group B for GP removal with further canal preparation with stainless steel K-flex files (Kerr). The operating time was recorded. Teeth were rendered transparent for the evaluation of the area of remaining GP/sealer in bucco-lingual and mesial-distal directions. Statistical analysis was performed by using repeated measures analysis of variance and anova. Results The ProTaper Universal technique (group A) resulted in a smaller percentage of canal area covered by residual GP/sealer than in groups B and C, with a significant difference between groups A and C (P < 0.05). Mean operating time for group A was 6.73 min, which was significantly shorter (P < 0.05) than group B (10.86 min) and group C (13.52 min). CONCLUSIONS: In this laboratory study all test techniques left GP/sealer remnants within the root canal. The ProTaper Universal rotary retreatment system proved to be an efficient method of removing GP and sealer from maxillary anterior teeth.

[Preliminary clinical study of endodontic antiseptic in monotithic type chlorhexidine controlled release delivery system]

The purpose of clinical study was to assess the bacteriological status of the root canal after disinfection with the monotithic type chlorhexidine enrolled release delivery system (CCROS).In experiments the monotithic type CCRDS was found to be more effective than the reservoir type CCRDS.The root canals of 24 teeth with apical periodontitis were completely instrumented and irrigated with sodium hypochloride.After the instrumentations,12 teeth were treated with the monotitihic type CCRDS,12 teeth were treated with formocresol.Bacterological samples from the root canals were taken after 5 days using an anaerobic technique.The results indicated that monotithic type CCRDS was more effective than formocresol in obtaining bacteria-free root canals(Chi-square test P<0.05).The advantages of an antiseptic with along lasting effect for the elimination of bacteria form the root canal and for the prevention of reinfection were emphasized.

[Experimental study on the interaction of fibronectin with oral Streptococci].

Interaction of fibronectin (Fn) with Streptococcus mutans, S. sorbrinus, and S. milleri is demonstrated by an enzyme-linked immunosorbent assay (ELISA). The results show that the three strains are able to adhere to Fn. The interaction may be strengthened while the concentration of Fn increases (q test P < 0.01). The ability of adherence among S. mutans, S. sorbrinus and S. milleri is different in Fn high concentration (q test P < 0.01). It is speculated the free Fn in saliva may serve as an agglution for elimination of the organisms from the oral cavity, or as a receptor when immobilized on the tooth surface for cariogenic streptococci to form plaque. A balance between these two functions of Fn may play a role in modulating the microbial ecological environment of the oral cavity.

[Detection of DNA G+C mol% in taxonomy of Streptococcus mutans by means of high performance liquid chromatography].

In the present study, DNA G+C mol% of 9 strains of bacteria (including 7 international standard strain, Ingbritt, and 2 other strains extracted in our Lab) were detected with application of High Performance Liquid Chromatograph. The results showed that DNA G+C content of S. mutans was 35-40%, S. sobrinus was 45-46%, S. cricetus was 38%, and S. rattus was 41%. The difference between S sobrinus and S. mutans was higher than 5%, which suggested that S. sobrinus should be identified as an independent classification unit of bacterial species from S. mutans.

[A study on resorbable local metronidazol delivery devices]

A local metronidazol (MTZ) delivery using resorbable base material was studied. In vitro MTZ was almost completely released within 24 hrs from the hydroxypropylmethyl cellullouse(HPMC) strips.In vivo,release of the drug strips was also measured in six patients who had deep pockets of more than 5mm.MTZ-containing HPMC strip was inserted in the pocket.The average amount of MTZ in the gingival crevicalar fluid(GCF) 24 hrs after insertion of strip was 40microg/ml.(much higher than the reported MIC of some microorganisms associated with adult periodontitis).In vitro there were significant inhibitory effects of MTZ containing strips on the microorganisms associated with periodontal disease.The prevalence of spirochetes and motil rods,and gingival index(GI) was remarkably reduced in the MTZ administered pockets,It is suggest that this new direct drug delivery system with HPMC used as base material could be used to treat periodontal disease.