MyD88 exacerbates inflammation-induced bone loss by modulating dynamic equilibrium between Th17/Treg cells and subgingival microbiota dysbiosis.

BACKGROUND: This study aimed to investigate the contribution of myeloid differentiation primary-response gene 88 (MyD88) on the differentiation of T helper type 17 (Th17) and regulatory T (Treg) cells and the emerging subgingival microbiota dysbiosis in Porphyromonas gingivalis-induced experimental periodontitis. METHODS: Alveolar bone loss, infiltrated inflammatory cells, immunostained cells for tartrate-resistant acid phosphatase (TRAP), the receptor activator of nuclear factor-kB ligand (RANKL), and osteoprotegerin (OPG) were quantified by microcomputerized tomography and histological staining between age- and sex-matched homozygous littermates (wild-type [WT, Myd88+/+] and Myd88-/- on C57BL/6 background). The frequencies of Th17 and Treg cells in cervical lymph nodes (CLNs) and spleen were determined by flow cytometry. Cytokine expression in gingival tissues, CLNs, and spleens were studied by quantitative polymerase chain reaction (qPCR). Analysis of the composition of the subgingival microbiome and functional annotation of prokaryotic taxa (FAPROTAX) analysis were performed. RESULTS: P. gingivalis-infected Myd88-/- mice showed alleviated bone loss, TRAP+ osteoclasts, and RANKL/OPG ratio compared to WT mice. A significantly higher percentage of Foxp3+CD4+ T cells in infected Myd88-/- CLNs and a higher frequency of RORγt+CD4+ T cells in infected WT mice was noted. Increased IL-10 and IL-17a expressions in gingival tissue at D14-D28 then declined in WT mice, whereas an opposite pattern was observed in Myd88-/- mice. The Myd88-/- mice exhibited characteristic increases in gram-positive species and species having probiotic properties, while gram-negative, anaerobic species were noted in WT mice. FAPROTAX analysis revealed increased aerobic chemoheterotrophy in Myd88-/- mice, whereas anaerobic chemoheterotrophy was noted in WT mice after P. gingivalis infection. CONCLUSIONS: MyD88 plays an important role in inflammation-induced bone loss by modulating the dynamic equilibrium between Th17/Treg cells and dysbiosis in P. gingivalis-induced experimental periodontitis.

Modulating the sEH/EETs Axis Restrains Specialized Proresolving Mediator Impairment and Regulates T Cell Imbalance in Experimental Periodontitis.

Epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids are short-acting lipids involved in resolution of inflammation. Their short half-life, due to its metabolism by soluble epoxide hydrolase (sEH), limits their effects. Specialized proresolving mediators (SPMs) are endogenous regulatory lipids insufficiently synthesized in uncontrolled and chronic inflammation. Using an experimental periodontitis model, we pharmacologically inhibited sEH, examining its impact on T cell activation and systemic SPM production. In humans, we analyzed sEH in the gingival tissue of periodontitis patients. Mice were treated with sEH inhibitor (sEHi) and/or EETs before ligature placement and treated for 14 d. Bone parameters were assessed by microcomputed tomography and methylene blue staining. Blood plasma metabololipidomics were carried out to quantify SPM levels. We also determined T cell activation by reverse transcription-quantitative PCR and flow cytometry in cervical lymph nodes. Human gingival samples were collected to analyze sEH using ELISA and electrophoresis. Data reveal that pharmacological sEHi abrogated bone resorption and preserved bone architecture. Metabololipidomics revealed that sEHi enhances lipoxin A4, lipoxin B4, resolvin E2, and resolvin D6. An increased percentage of regulatory T cells over Th17 was noted in sEHi-treated mice. Lastly, inflamed human gingival tissues presented higher levels and expression of sEH than did healthy gingivae, being positively correlated with periodontitis severity. Our findings indicate that sEHi preserves bone architecture and stimulates SPM production, associated with regulatory actions on T cells favoring resolution of inflammation. Because sEH is enhanced in human gingivae from patients with periodontitis and connected with disease severity, inhibition may prove to be an attractive target for managing osteolytic inflammatory diseases.

Soluble epoxide hydrolase inhibition enhances production of specialized pro-resolving lipid mediator and promotes macrophage plasticity.

BACKGROUND AND PURPOSE: Epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFA) are lipid mediators that are rapidly inactivated by soluble epoxide hydrolase (sEH). Uncontrolled and chronic inflammatory disorders fail to sufficiently activate endogenous regulatory pathways, including the production of specialized pro-resolving mediators (SPMs). Here, we addressed the relationship between SPMs and the EET/sEH axis and explored the effects of sEH inhibition on resolving macrophage phenotype. EXPERIMENTAL APPROACH: Mice were treated with a sEH inhibitor, EETs, or sEH inhibitor + EETs (combination) before ligature placement to induce experimental periodontitis. Using RT-qPCR, gingival samples were used to examine SPM receptors and osteolytic and inflammatory biomarkers. Maxillary alveolar bone loss was quantified by micro-CT and methylene blue staining. SPM levels were analysed by salivary metabolo-lipidomics. Gingival macrophage phenotype plasticity was determined by RT-qPCR and flow cytometry. Effects of sEH inhibition on macrophage polarization and SPM production were assessed with bone marrow-derived macrophages (BMDMs). KEY RESULTS: Pharmacological inhibition of sEH suppressed bone resorption and the inflammatory cytokine storm in experimental periodontitis. Lipidomic analysis revealed that sEH inhibition augmented levels of LXA4, RvE1, RvE2, and 4-HDoHE, concomitant with up-regulation of LTB4R1, CMKLR1/ChemR23, and ALX/FPR2 SPM receptors. Notably, there is an impact on gingival macrophage plasticity was affected suggesting an inflammation resolving phenotype with sEH inhibition. In BMDMs, sEH inhibition reduced inflammatory macrophage activation, and resolving macrophages were triggered to produce SPMs. CONCLUSION AND IMPLICATIONS: Pharmacological sEH inhibition increased SPM synthesis associated with resolving macrophages, suggesting a potential target to control osteolytic inflammatory disorders.

Effectiveness of different root-end filling materials in modern surgical endodontic treatment: A systematic review and network meta-analysis.

Background/purpose: There is controversial evidence on the best choice for root-end filling materials in follow-up periods and treatment protocols. The purpose of this study was to evaluate the effectiveness of different root-end filling materials in modern surgical endodontic treatment. Materials and methods: A total of 16 studies with a minimum follow-up of 12-months were qualified to be reviewed, involving randomized control trials and observational studies in PubMed, Cochrane library and Scopus until September 1, 2021. The outcome of modern surgical endodontic treatment was assessed based on clinical and radiographic success. Direct comparisons were combined to estimate indirect comparisons, and the estimated effect size was analyzed using the odds ratio (OR). The comparative effectiveness of all materials for target outcomes were shown as P-score. Results: Within this network meta-analysis, mineral trioxide aggregate (MTA) had superior effects among all root-end filling materials at 12-months follow-up. (MTA: OR, 2.03; 95% CI, 0.84-4.91; P-score, 0.86; reference material, gutta-percha). In further sensitivity analyses, MTA, calcium silicate-based root repair material (RRM) and super EBA cement (Super EBA) were associated with significantly higher success rates at 12-months follow-up. (MTA: OR, 5.62; 95% CI, 1.58-19.99; P-score, 0.88; RRM: OR, 5.23; 95% CI, 1.05-25.98; P-score, 0.74; Super EBA: OR, 3.99; 95% CI, 1.06-15.04; P-score, 0.54; reference material, gutta-percha). Conclusion: MTA remains the best choice for root-end filling materials of modern surgical endodontic treatment at the 12-month follow-up. Comparative randomized clinical trials in the long-term follow-up are warranted in future investigations.

Corrigendum: RvE1 Impacts the Gingival Inflammatory Infiltrate by Inhibiting the T Cell Response in Experimental Periodontitis.

[This corrects the article DOI: 10.3389/fimmu.2021.664756.].

RvE1 Impacts the Gingival Inflammatory Infiltrate by Inhibiting the T Cell Response in Experimental Periodontitis.

Periodontitis is a chronic inflammatory disease associated with the formation of dysbiotic plaque biofilms and characterized by the progressive destruction of the alveolar bone. The transition from health to disease is characterized by a shift in periodontal immune cell composition, from mostly innate (neutrophils) to adaptive (T lymphocytes) immune responses. Resolvin E1 (RvE1) is a specialized pro-resolution mediator (SPMs), produced in response to inflammation, to enhance its resolution. Previous studies have indicated the therapeutic potential of RvE1 in periodontal disease; however, the impact of RvE1 in the microbial-elicited osteoclastogenic immune response remains uncharacterized in vivo. In the present study, we studied the impact of RvE1 on the gingival inflammatory infiltrate formation during periodontitis in a mouse model. First, we characterized the temporal-dependent changes of the main immune cells infiltrating the gingiva by flow cytometry. Then, we evaluated the impact of early or delayed RvE1 administration on the gingival immune infiltration and cervical lymph nodes composition. We observed a consistent inhibitory outcome on T cells -particularly effector T cells- and a protective effect on regulatory T cells (Tregs). Our data further demonstrated the wide range of actions of RvE1, its preventive role in the establishment of the adaptive immune response during inflammation, and bone protective capacity.

Effect of selected sampling media, flow rate, and time on the sampling efficiency of a liquid impinger packed with glass beads for the collection of airborne viruses.

The liquid impingers can be used for sampling of viral aerosols, such as COVID-19 virus, influenza, and measles. However, the lowest cutoff diameter of commercially available liquid impingers was about 0.3 µm, and the physical collection efficiency for nano-bioaerosol is only about 10-20%. Here, we enhanced the impinger's collection efficiency and recovery of viable viral aerosols by using packed glass beads and selected sampling media (1% peptone and lysogeny broth, LB). Single-stranded RNA (ssRNA) MS2 bacteriophage with uranine (as a physical tracer) was used as model viral aerosols. The effects of different sampling flow rates (4, 6, and 12.5 L per minute) and different sampling time (10, 20, and 30 min) on the collection efficiency and recovery of MS2 aerosols were also tested. Collection efficiency and recovery of viable viral aerosols were analyzed as a function of sampling media, flow rate, and sampling time and packed glass beads by using a general linear model. Although the packed glass beads considerably enhanced the collection efficiency of the liquid impinger for MS2 aerosols, the recovery of viable MS2 becomes lower due to the higher pressure drop across the impinger. Using peptone or LB as sampling media, reducing sampling flow rate, and decreasing sampling time was proven to improve the recovery of viable MS2. Conclusively, this study provides some practical methods to improve the collection efficiency of liquid impinger for viral aerosols and preserve their viability.

LOXL2 promotes aggrecan and gender-specific anabolic differences to TMJ cartilage.

In the United States, 5-12% of adults have at least one symptom of temporomandibular joint (TMJ) disorders, including TMJ osteoarthritis (TMJ-OA). However, there is no chondroprotective agent that is approved for clinical application. We showed that LOXL2 is elevated in the regenerative response during fracture healing in mice and has a critical role in chondrogenic differentiation. Indeed, LOXL2 is an anabolic effector that attenuates pro-inflammatory signaling in OA cartilage of the TMJ and knee joint, induces chondroprotective and regenerative responses, and attenuates NF-kB signaling. The specific goal of the study was to evaluate if adenoviral delivery of LOXL2 is anabolic to human and mouse TMJ condylar cartilage in vivo and evaluate the protective and anabolic effect on cartilage-specific factors. We employed two different models to assess TMJ-OA. In one model, clinical TMJ-OA cartilage from 5 different samples in TMJ-OA cartilage plugs were implanted subcutaneously in nude mice. Adenovirus LOXL2 -treated implants showed higher mRNA levels of LOXL2, ACAN, and other anabolic genes compared to the adenovirus-Empty-treated implants. Further characterization by RNA-seq analysis showed LOXL2 promotes proteoglycan networks and extracellular matrix in human TMJ-OA cartilage implants in vivo. In order to evaluate if LOXL2-induced functional and sex-linked differences, both male and female four-month-old chondrodysplasia (Cho/+) mice, which develop progressive TMJ-OA due to a point mutation in the Col11a1 gene, were subjected to intraperitoneal injection with Adv-RFP-LOXL2 every 2 weeks for 12 weeks. The data showed that adenovirus delivery of LOXL2 upregulated LOXL2 and aggrecan (Acan), whereas MMP13 expression was slightly downregulated. The fold change expression of Acan and Runx2 induced by Adv-RFP-LOXL2 was higher in females compared to males. Interestingly, Adv-RFP-LOXL2 injection significantly increased Rankl expression in male but there was no change in females, whereas VegfB gene expression was increased in females, but not in males, as compared to those injected with Adv-RFP-Empty in respective groups. Our findings indicate that LOXL2 can induce specifically the expression of Acan and other anabolic genes in two preclinical models in vivo. Further, LOXL2 has beneficial functions in human TMJ-OA cartilage implants and promotes gender-specific anabolic responses in Cho/+ mice with progressive TMJ-OA, suggesting its merit for further study as an anabolic therapy for TMJ-OA.

Correction to: Gamma synuclein is a novel nicotine responsive protein in oral cancer malignancy.

[This corrects the article DOI: 10.1186/s12935-020-01401-w.].

Association between the presence of distolingual root in mandibular first molars and the presence of C-shaped mandibular second molars: a CBCT study in a Taiwanese population.

OBJECTIVES: The purpose of this study was to assess the prevalence of C-shaped canals in permanent mandibular second molars (SMs) and to determine whether its appearance was associated with the presence of distolingual root (DLR) in permanent mandibular first molars (FMs). METHOD AND MATERIALS: Three hundred and eighty patients were qualified for evaluation of their FMs and SMs using cone beam computed tomography. The prevalence, distribution pattern, external root morphology, and the internal root canal anatomy of the examined molars were recorded and analyzed. Furthermore, the association between the root canal configurations of SMs and the appearance of DLR in FMs was also assessed. RESULTS: The prevalence of SMs with C-shaped root canals was 44.7%. The most common root canal configuration type of the one-rooted SMs with C-shaped anatomy was C3 (45.6%), followed by C2 and C1. The frequency of C-shaped canals in SMs was 45.4% in Non-DLR group, 52.8% in unilateral DLR group, and 33.9% in bilateral DLR group, respectively. Moreover, the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was significantly lowered. CONCLUSION: The association between the presence of DLR in FMs and C-shaped canal configurations in neighboring SMs was surveyed, and the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was found to be significantly lowered.

Gamma synuclein is a novel nicotine responsive protein in oral cancer malignancy.

BACKGROUND: The mechanisms of neuronal protein γ-synuclein (SNCG) in the malignancy of oral squamous cell carcinoma (OSCC) are not clear. This study tested the hypothesis that SNCG is involved in nicotine-induced malignant behaviors of OSCC. The effect of nicotine on SNCG expression and epithelial-to-mesenchymal transition (EMT) markers were examined. METHODS: Short hairpin RNA (shRNA) and an antagonist specific for α7-nicotine acetylcholine receptors (α7-nAChRs) were used to examine the role of α7-nAChRs in mediating the effects of nicotine. Knockdown of SNCG in nicotine-treated cells was performed to investigate the role of SNCG in cancer malignancy. The in vivo effect of nicotine was examined using a nude mouse xenotransplantation model. RESULTS: Nicotine increased SNCG expression in a time- and dose-dependent manner. Nicotine treatment also increased E-cadherin and ZO-1 and decreased fibronectin and vimentin expression. After specific knockdown of α7-nAChRs and inhibition of the PI3/AKT signal, the effect of nicotine on SNCG expression was attenuated. Silencing of SNCG abolished nicotine-induced invasion and migration of OSCC cells. The xenotransplantation model revealed that nicotine augmented tumor growth and SNCG expression. CONCLUSION: Nicotine upregulated SNCG expression by activating the α7-nAChRs/PI3/AKT signaling that are participated in nicotine-induced oral cancer malignancy.

α7-Nicotine acetylcholine receptor mediated nicotine induced cell survival and cisplatin resistance in oral cancer.

OBJECTIVE: To investigate the effect of nicotine on cell survival and cisplatin resistance in oral cancer and the possible involvement of α7-nicotinic acetylcholine receptors (α7-nAChRs). DESIGN: The effects of nicotine on cell survival and cisplatin-induced apoptosis were assessed. Knockdown of α7-nAChRs by short hairpin RNA and the specific antagonist methyllycaconitine (MLA) was used to examine the involvement of α7-nAChRs in modulating the effects of nicotine. Apoptosis signal molecules were examined in nicotine- and cisplatin-treated cells. RESULTS: Nicotine increased the survival of the oral cancer cells YD8 and OEC-M1 in a dose- and time-dependent manner. Nicotine treatment accelerated cell cycle progression in the oral cancer cells, and significantly reduced cisplatin-induced cell apoptosis. In the α7-nAChR-silenced cells, the prosurvival effect of nicotine in the cisplatin-treated cells was attenuated. Co-treatment of cisplatin and nicotine attenuated the effect of cisplatin on Bcl-2 expression. In addition, the effect of nicotine on cell survival under cisplatin treatment was attenuated with the addition of the Bcl-2 inhibitor ABT-737. CONCLUSIONS: Treating oral cancer cells with nicotine increased cell survival and cisplatin resistance, in which α7-nAChRs were involved.

Effective disinfection of airborne microbial contamination in hospital wards using a zero-valent nano-silver/TiO2 -chitosan composite.

A novel antimicrobial composite of zero-valent silver nanoparticles (AgNPs), titania (TiO2 ), and chitosan (CS) was prepared via photochemical deposition of AgNPs on a CS-TiO2 matrix (AgNPs@CS-TiO2 ). Electron microscopy showed that the AgNPs were well dispersed on the CS-TiO2 , with diameters of 6.69-8.84 nm. X-ray photoelectron spectra indicated that most of the AgNPs were reduced to metallic Ag. Fourier-transform infrared spectroscopy indicated that some AgNPs formed a chelate with CS through coordination of Ag+ with the CS amide II groups. The zones of inhibition of AgNPs@CS-TiO2 for bacteria (Escherichia coli and Staphylococcus epidermidis) and fungi (Aspergillus niger and Penicillium spinulosum) were 6.72-11.08 and 5.45-5.77 mm, respectively, and the minimum (critical) concentrations of AgNPs required to inhibit the growth of bacteria and fungi were 7.57 and 16.51 µg-Ag/mm2 , respectively. The removal efficiency of a AgNPs@TiO2 -CS bed filter for bioaerosols (η) increased with the packing depth, and the optimal filter quality (qF) occurred for packing depths of 2-4 cm (qF = 0.0285-0.103 Pa-1 ; η = 57.6%-98.2%). When AgNPs@TiO2 -CS bed filters were installed in the ventilation systems of hospital wards, up to 88% of bacteria and 97% of fungi were removed within 30 minutes. Consequently, AgNPs@TiO2 -CS has promising potentials in bioaerosol purification.

Detection and location of second mesiobuccal canal in permanent maxillary teeth: A cone-beam computed tomography analysis in a Taiwanese population.

OBJECTIVES: The aim of this study was to analyze the incidence, symmetry, concurrence of second mesiobuccal canal (MB2) and determine geometric relationships between each orifice of maxillary first and second molars by cone-beam computed tomography (CBCT) analysis. METHODS: A total of 216 qualified individuals' (503 teeth) CBCT image were enrolled in the present study. The consistency of bilateral symmetry and concurrent appearance of MB2 canals were analyzed among individuals with contralateral and adjacent molar teeth. The inter-orifice distances and angulations of first and second molars were also measured. RESULTS: The overall incidence of MB2 canal of maxillary molars was 39.2%, in which 45.9% and 32.3% in the first and second molars, respectively. The distribution of MB2 canal in contralateral molar teeth has significant gender difference in second molars (p = 0.024) while analyzing the frequency of MB2 canal appearing in contralateral molar pairs. The simultaneous occurrence of MB2 canal was 22.4% for contralateral molars, and the prevalence of concurrent appearance of MB2 canal in the adjacent molars was 43.4%. After adjusting for gender, age, and tooth type, the inter-orifice distances of mesiobuccal to palatal (odds ratios = 1.891) and to distobuccal (odds ratios = 1.448) canals, demonstrated significant differences between molars with and without MB2 canals. CONCLUSIONS: The clinical significance of the results presents critical information on the geometric features, including inter-orifice distances and angulations between each orifice in maxillary molar teeth. Further studies should be conducted to investigate the exact anatomic coordination between each orifice and its impact on access preparation and external crown morphology.

Axl Involved in Mineral Trioxide Aggregate Induces Macrophage Polarization.

INTRODUCTION: In this study, we examined the effect of mineral trioxide aggregate (MTA) on macrophage polarization and the potential involvement of Axl/nuclear factor kappa B (NF-κB) signaling in mediating the effect of MTA. METHODS: The human monocyte cell line THP-1 was cultured with MTA solution for 1, 2, or 3 days, and the population change of M2 macrophages was analyzed by flow cytometry. Expression of M2 cytokines was examined by enzyme-linked immunosorbent assay. Phagocytosis and angiogenesis-induction ability were also assayed. The involvement of Axl/NF-κB signaling in MTA-treated cells was examined by analyzing phosphorylation status of Axl, Akt, IKKα/ß, and IκBα. Specific inhibitors for Axl/Akt/NF-κB signaling were added to MTA-treated THP-1 cells, and their cytokine expression change was examined. RESULTS: Flow cytometry analysis showed that MTA treatment increased CD206＋ cells in a time-dependent way. After MTA treatment, the expression of M2-related cytokines was up-regulated. MTA also enhanced phagocytic ability and the ability of THP-1 cells to induce angiogenesis. Treatment of MTA led to activate Axl/Akt/NF-kB signal axis by phosphorylation of Axl, Akt, IKKα/ß, IκBα, and p65. In addition, MTA-induced interleukin 10, transforming growth factor beta, and vascular endothelial growth factor expression was suppressed as specific inhibitors were added. CONCLUSIONS: Our findings indicate that MTA is able to induce macrophage polarization toward the M2 phenotype, with up-regulation of interleukin 10, transforming growth factor beta, and vascular endothelial growth factor, and that Axl/Akt/NF-κB signaling participates in this process. These results provide the cellular and molecular basis of MTA's anti-inflammatory action in clinical applications.

Relationship of the Incidence of C-shaped Root Canal Configurations of Mandibular First Premolars with Distolingual Roots in Mandibular First Molars in a Taiwanese Population: A Cone-beam Computed Tomographic Study.

INTRODUCTION: The aim of this study was to determine the prevalence of C-shaped canal configurations (CSs) and radicular grooves (RGs) in permanent mandibular first premolars (MPs) and to investigate the relevance of such complexities with the presence of distolingual roots (DLRs) in permanent mandibular first molars (MMs). METHODS: A total of 800 pairs of MPs and MMs were investigated using a cone-beam computed tomographic system (NewTom 5G; QR srl, Verona, Italy). The frequency and symmetry of DLRs in MMs along with the occurrence of RGs and CSs in examined MPs were evaluated. Multivariable logistic regression analysis was applied to examine the correlation between the CSs of MPs with the appearance of DLRs in MMs. RESULTS: In the examined teeth, 23.0% of MMs had a DLR, whereas 16.6% of MPs had RGs and 12.5% of MPs had C-shaped canals. Although the most common canal configuration in MPs is the single canal (74.1%), the other 25.9% still possess complicated root canals. Of these MPs that have different canal configurations, 54.6% had 2 canals, whereas 44.4% had CSs. Specifically, the CS showed a high prevalence of C3 morphologies at 98.9% followed by C1 at 1.1%. A corresponding and increasing frequency was noted in CSs and RGs of MPs and MMs with DLRs (P < .001). After adjusting for related categoric variables, the adjusted odds ratios for CSs of MPs in the bilateral DLR group compared with the non-DLR group was 3.294 (P < .001). CONCLUSIONS: This study showed an increased appearance of CSs in MPs when DLRs were present in MMs in the Taiwanese population.

Increasing prominence of implantology research: a chronological trend analysis of 100 top-cited articles in periodontal journals.

PURPOSE: To identify 100 top-cited articles published in periodontal journals and analyse the research trends by using citation analysis. MATERIALS AND METHODS: 100 top-cited articles published in periodontal journals were retrieved by searching the database of the ISI Web of Science and Journal Citation reports. For each article, the following principal bibliometric parameters: authorship, geographic and institute origin, manuscript type, study design, scope of study, and citation count of each time period were analysed from 1965 to 2015. RESULTS: The identified 100 top-cited articles were retrieved from five periodontal journals and citation counts were recorded between 262 and 1,693 times. For the institute of origin, the most productive institute, in terms of the number of 100 top-cited articles published, was the University of Gothenburg (Sweden) (n = 19), followed by the Forsyth Dental Center (USA) (n = 15). Most manuscripts were original research (n = 74), and the inflammatory periodontal disease (n = 59) was the most frequent topic studied. Interestingly, the trend of increase average citation reached significance for implantology (ß = 26.75, P = 0.003) and systemic interactions (ß = 29.83, P = 0.005), but not for inflammatory disease (ß = -10.30, P = 0.248) and tissue regeneration (ß = 9.04, P = 0.081). By using multivariable linear regression in a generalised linear model, suitable published journal (Journal of Clinical Periodontology), geographic regions (Europe), more intense international collaboration, adequate manuscript type (review article) and study design (systematic review) could be attributed to escalating average citation counts in implantology (all P < 0.05). However, for systemic interactions, only geographic region and study design were significantly associated with the increasing citation trend. CONCLUSIONS: These principal bibliometric characteristics revealed escalated trends in average citation count in implantology throughout time.

The Presence of Distolingual Root in Mandibular First Molars Is Correlated with Complicated Root Canal Morphology of Mandibular Central Incisors: A Cone-beam Computed Tomographic Study in a Taiwanese Population.

INTRODUCTION: The aim of this study was to assess the prevalence of complicated root canals in permanent mandibular central incisors (PMCIs) and its correlation with the presence of a distolingual root (DLR) in permanent mandibular first molars (PMFMs) using cone-beam computed tomographic imaging in a Taiwanese population. METHODS: A total of 400 patients (800 pairs of PMCIs and PMFMs) were qualified for further analysis. The prevalence of DLRs in PMFMs along with root canal configurations of PMCIs were assessed at subject and tooth levels. Multivariable logistic regression analysis was used to evaluate the correlation between the root canal configurations of PMCIs with the existence of DLRs in PMFMs. RESULTS: The prevalence of PMFMs with DLRs and complicated root canal configurations in PMCIs was 23.0% and 15.6%, respectively. A significant difference in age (<50 years vs ≥50 years) was found for complicated root canal configurations in PMCIs. The most prevalent root canal system in PMCIs was Vertucci type I (84.4%) followed by type III (13.5%). A positive correlation between the presence of DLRs in PMFMs and complicated root canal configurations in PMCIs was noted. After adjusting for categoric variables including sex, age, and side, the odds ratios for the occurrence of complicated root canal configurations of PMCIs in the unilateral DLR group and the bilateral DLR group compared with the non-DLR group were 2.13 and 2.53, respectively. CONCLUSIONS: The concurrent appearance of DLRs in PMFMs and complicated root canal morphology in PMCIs is prominent in Taiwanese individuals.

The prevalence and distribution of radiopaque, calcified pulp stones: A cone-beam computed tomography study in a northern Taiwanese population.

BACKGROUND/PURPOSE: Presence of pulp stones increase the difficulty of locating canal orifice during endodontic treatment. This study aims to determine the prevalence of pulp stones in a northern Taiwanese population through analysis of cone beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 144 patients and 2554 teeth were used in the present study which were collected from a CBCT image archive. To determine the presence of pulp stones, images of pulp chamber and root canals were analyzed in the sagittal, axial and coronal planes and from the occlusal to apical direction. Correlations between pulp stones and gender, age, tooth type, dental arch or side were also examined. RESULTS: Of the 144 patients, 120 patients (83.3%) and 800 (31.3%) teeth were found to have one or more pulp stones through CBCT examination. Prevalence of pulp stones between dental arches and tooth types were significantly different (P < 0.001). Pulp stones were found to be the most prevalent in first molars (50.0%) and most scarce in first premolars (18.8%). There was no significant correlation between pulp stones and gender, increasing age, or dental sides. CONCLUSION: Pulp stones are more frequent in maxillary teeth compared to mandibular teeth. Pulp stones in molar teeth were significantly more common than premolars and incisors. CBCT could be a sensitive tool to detect pulp stones, especially simplifying identification of pulp stones in radicular pulp. Knowledge of pulp stones distribution can aid dentists in clinical endodontic treatment.