Stimulation phosphatidylinositol 3-kinase/protein kinase B signaling by Porphyromonas gingivalis lipopolysacch aride mediates interleukin-6 and interleukin-8 mRNA/protein expression in pulpal inflammation.

BACKGROUND/PURPOSE: The signaling mechanisms for Porphyromonas gingivalis lipopolysaccharide (PgLPS)-induced inflammation in human dental pulp cells are not fully clarified. This in vitro study aimed to evaluate the involvement of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in PgLPS-induced pulpal inflammation. METHODS: Human dental pulp cells (HDPCs) were challenged with PgLPS with or without pretreatment and coincubation with a PI3K/Akt inhibitor (LY294002). The gene or protein levels of PI3K, Akt, interleukin (IL)-6, IL-8, alkaline phosphatase (ALP), osteocalcin and osteonectin were analyzed by reverse transcription polymerase chain reaction (PCR), real-time PCR, western blotting, and immunofluorescent staining. In addition, an enzyme-linked immunosorbent assay was used to analyze IL-6 and IL-8 levels in culture medium. RESULTS: In response to 5 µg/ml PgLPS, IL-6, IL-8, and PI3K, but not Akt mRNA expression of HDPCs, was upregulated. IL-6, IL-8, PI3K, and p-Akt protein levels were stimulated by 10-50 µg/ml of PgLPS in HDPCs. PgLPS also induced IL-6 and IL-8 secretion at concentrations higher than 5 µg/ml. Pretreatment and co-incubation by LY294002 attenuated PgLPS-induced IL-6 and IL-8 mRNA expression in HDPCs. The mRNA expression of ALP, but not osteocalcin and osteonectin, was inhibited by higher concentrations of PgLPS in HDPCs. CONCLUSION: P. gingivalis contributes to pulpal inflammation in HDPCs by dysregulating PI3K/Akt signaling pathway to stimulate IL-6 and IL-8 mRNA/protein expression and secretion. These results are useful for understanding the pulpal inflammation and possible biomarkers of inflamed pulp diagnosis and treatment.

Effect of butyrate, a bacterial by-product, on the viability and ICAM-1 expression/production of human vascular endothelial cells: Role in infectious pulpal/periapical diseases.

AIM: To investigate the effects of butyric acid (BA), a metabolic product generated by pulp and root canal pathogens, on the viability and intercellular adhesion molecule-1 (ICAM-1) production of endothelial cells, which are crucial to angiogenesis and pulpal/periapical wound healing. METHODOLOGY: Endothelial cells were exposed to butyrate with/without inhibitors. Cell viability, apoptosis and reactive oxygen species (ROS) were evaluated using an MTT assay, PI/annexin V and DCF fluorescence flow cytometry respectively. RNA and protein expression was determined using a polymerase chain reaction assay and Western blotting or immunofluorescent staining. Soluble ICAM-1 (sICAM-1) was measured using an enzyme-linked immunosorbent assay. The quantitative results were expressed as mean ± standard error (SE) of the mean. The data were analysed using a paired Student's t-test where necessary. A p-value ≤0.05 was considered to indicate a statistically significant difference between groups. RESULTS: Butyrate (>4 mM) inhibited cell viability and induced cellular apoptosis and necrosis. It inhibited cyclin B1 but stimulated p21 and p27 expression. Butyrate stimulated ROS production and hemeoxygenase-1 (HO-1) expression as well as activated the Ac-H3, p-ATM, p-ATR, p-Chk1, p-Chk2, p-p38 and p-Akt expression of endothelial cells. Butyrate stimulated ICAM-1 mRNA/protein expression and significant sICAM-1 production (p < .05). Superoxide dismutase, 5z-7oxozeaenol, SB203580 and compound C (p <  .05), but not ZnPP, CGK733, AZD7762 or LY294002, attenuated butyrate cytotoxicity to endothelial cells. Notably, little effect on butyrate-stimulated sICAM-1 secretion was found. Valproic acid, phenylbutyrate and trichostatin (three histone deacetylase inhibitors) significantly induced sICAM-1 production (p < .05). CONCLUSION: Butyric acid inhibited proliferation, induced apoptosis, stimulated ROS and HO-1 production and increased ICAM-1 mRNA expression and protein synthesis in endothelial cells. Cell viability affected by BA was diminished by some inhibitors; however, the increased sICAM-1 secretion by BA was not affected by any of the tested inhibitors. These results facilitate understanding of the pathogenesis, prevention and treatment of pulpal/periapical diseases.

Cracked teeth: Distribution and survival at 6 months, 1 year and 2 years after treatment.

BACKGROUND/PURPOSE: The unpredictable condition of cracked teeth warrants further investigation and clinical experiences. The purpose of this study was to collect and record data on demographics, clinical characteristics, different treatment modalities and survival of cracked teeth at 6-month, 1-year and 2-year recalls. METHODS: 77 cracked teeth from 65 patients were included. Data on demographics, clinical parameters, treatment modalities and recall were collected. Binomial, multinomial and chi square tests were used for statistical analysis. RESULTS: Most cracked teeth occurred in patients greater than 40 years old (p < 0.01). Cracked teeth themselves were most often molars (79.22%; p < 0.01), a non-terminal tooth in the arch (62.34%; p < 0.05) and nonendodontically-treated teeth (94.81%; p < 0.01). Cracked teeth exhibited pain to percussion (63.64%, p < 0.05) or biting (74.03%; p < 0.01), and no or only positive mobility (76.62%; p < 0.01). Cracks were most often oriented in the mesiodistal direction (68.83%; p < 0.01). Higher survival rates were noted in cracked teeth lacking pre-operative pain to palpation or spontaneous pain, and with no or only positive mobility at 6-month and 1-year recalls. In vital cracked teeth, higher survival rates were noted in teeth lacking pre-operative pain to palpation and with no or only positive mobility at 2-year recalls. CONCLUSION: The absence of pre-operative palpation discomfort, spontaneous pain and minimal mobility, as well as the presence of pulp vitality were associated with higher survival rates of cracked teeth at all recall times. Results are useful for diagnosis and outcomes-based treatment planning of cracked teeth.

Characterization of Phosphorus Species in Human Dentin by Solid-State NMR.

The rat has been considered as an appropriate animal model for the study of the mineralization process in humans. In this work, we found that the phosphorus species in human dentin characterized by solid-state NMR spectroscopy consist mainly of orthophosphate and hydrogen phosphate. Some orthophosphates are found in a disordered phase, where the phosphate ions are hydrogen-bonded to structural water, some present a stoichiometric apatite structure, and some a hydroxyl-depleted apatite structure. The results of this study are largely the same as those previously obtained for rat dentin. However, the relative amounts of the various phosphorus species in human and rat dentin are dramatically different. In particular, stoichiometric apatite is more abundant in human dentin than in rat dentin, whereas the converse is true for disordered-phase orthophosphates. Furthermore, spatial proximity among all phosphorus species in human dentin is identical within experimental error, in contrast to what observed for rat dentin. Although it is not clear how these spectroscopic data could relate to the hierarchical structure or the mechanical properties of teeth, our data reveal that the molecular structures of human and rat dentin at different growth stages are not exactly the same.

Outcome assessment of apical surgery: A study of 234 teeth.

BACKGROUND/PURPOSE: Apical surgery is an option for management of endodontically-treated tooth with persistent periapical lesions or symptom and sign. The objective of this study was to investigate the correlation between the demography, preoperative, postoperative factors and healed rate of apical surgery. METHODS: Subjects were retrospectively collected from patients who received apical surgery/apicoectomy at the Endodontic Department, National Taiwan University Hospital from January 2013 to June 2015. The standard apical surgery procedures were performed. The demography, preoperative clinical and radiographic examination data as well as postoperative variables were collected. The outcome assessment was carried out after surgery. Statistical analysis was performed by chi square test to evaluate the potential outcome predictors. RESULTS: Total 187 patients and 234 teeth receiving apical surgery were included. 53 male and 134 female patients were collected. The age was ranged between 17 and 89 years old and the mean age was 43.64 years old. Better healed rate with significant differences were observed in female patient (p < 0.05), age ≤60 years old (p < 0.01), preoperative root canal filling material >2 mm short of apex (p < 0.01), lesion size from ≤2 mm to ≤12 mm (p < 0.05) and follow-up period â‰§12 months (p < 0.01) groups. CONCLUSION: Gender, age, preoperative root canal filling material extent, lesion size and follow-up period may affect the outcome of apical surgery. Tooth type, post, prosthesis, and lesion area showed no marked effect on apical healing. These results provide more detailed information for the clinical practitioners to make treatment plans and are important for clinical endodontic practices.

Effects of surface treatments of bioactive tricalcium silicate-based restorative material on the bond strength to resin composite.

OBJECTIVES: This study aimed to enhance the bond strength between Biodentine™ (BD), a bioactive tricalcium silicate (C3S) based material, and resin composite through various surface treatments. METHODOLOGY: BD samples were immersed in either double distilled water or Hank's Balanced Salt Solution and analyzed using X-ray Diffraction (XRD). Shear bond strength (SBS) evaluations of BD were performed using Prime & Bond™ NT (PNT), Single Bond Universal (SBU), Xeno V (Xeno), and glass ionomer cement (GIC) following various etching durations (0 s/ 15 s/ 30 s/ 60 s with 37.5% phosphoric acid). Two primers, RelyX™ Ceramic Primer (RCP) and Monobond ™ Plus (MBP), were chosen to prime BD for SBS enhancement. Fractography and bonding interfaces were examined with energy dispersive X-ray spectroscopy (EDS)/ scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). RESULTS: XRD confirmed BD's main compositions as C3S, Ca(OH)2, CaCO3 and ZrO2 after 14 days crystal maturation. Etched BD did not improve SBS. GIC exhibited the lowest SBS (p < 0.05) among all adhesives, regardless of the etching mode (all < 1 MPa). The highest SBS (17.5 ± 3.6 MPa, p < 0.05) was achieved when BD primed with MBP followed by SBU application. FTIR and EDS showed γ-MPTS and10-MDP within the MBP primer interacted with C3S and ZrO2 of BD, achieving enhanced SBS. Most specimens exhibited mixed or cohesive failure modes. Significance BD's subpar mechanical properties and texture may contribute to its poor adhesion to resin composite. Pretreating BD with MBP primer, followed by SBU adhesive is recommended for improving bond strength.

Surgical repair of external cervical resorption - Prognosis and prognostic factors.

Background/purpose: External cervical resorption (ECR) is an aggressive form of root resorption, which etiology is unclear and its prognosis remains unpredictable. The purpose of this study was to investigate the prognosis and potential prognostic factors of ECR-affected teeth after surgical intervention for external repair with/without root canal treatment. Materials and methods: Treated ECR cases from 2009 to 2019 were collected retrospectively. The survival of the teeth and the status of root resorption were assessed during the follow-up period. Potential prognostic factors were analyzed with log-rank test and Kaplan-Meier statistics. Results: A total of 42 treated ECR-affected teeth were enrolled. The two-year survival rate was 71.20% [54.16%, 93.59%]. Persistent root resorption was the main complication after treatment. Patients with multiple ECR-affected teeth had greater recurrent potential than patients with solitary ECR-affected teeth. Prolonged calcium hydroxide dressing may contribute to a more favorable clinical outcome. Gender, age, tooth position and the need for root canal treatment did not show statistically significant effect on the prognosis. Conclusion: The current surgical method was able to arrest ECR in most cases. However, the case type (the number of ECR-affected teeth per patient) could highly affect the prognosis of the teeth. Clinicians should consider long-term calcium hydroxide dressing in case of pulp involvement to achieve better results.

The multi-factor analysis of computer-based test scores in objective structured clinical examination of clerkship in school of dentistry, National Taiwan University.

Background/purpose: The objective structured clinical examination (OSCE) is a test designed to test technical, clinical, and practical competency in medicine teaching. This study tried to evaluate the influencing factors of the computer-based tests (CBT) results for dental students. Materials and methods: The 32 5th-year dental students of the dental school of National Taiwan University (NTU) joined preclinical CBT. The contents of CBT included clinical knowledge and practical skills of nine dental specialties. Twenty single-choice questions were played with the PowerPoint 2016 on a desktop, and the playing time for each question was 30 s. Several factors including the gender, age, and dental student admission ways (with or without the skill tests) were evaluated. Also, the comparison between the clerk's grade and CBT scores of nine dental specialties was performed. The students also filled the feedback questionnaire about the examination questions and suggestions for the CBT. Results: There were no significant differences in the mean CBT scores between male and female dental students, between two groups of dental students with or without the skill tests in the admission process, and among three different age groups of dental students. The clerk's scores were not directly related to the CBT scores. Conclusion: The CBT has been well-intentioned in dental education since 2022 in Taiwan. The CBT results revealed that the conjunction of knowledge from the textbook and clinical observation should be enhanced. The guideline should be established to integrate CBT into preclinical education and promote the performance of clinical work of dental students.

The analysis and feedback from the performance of pre-clinical operation skills tests for clerkship in School of Dentistry, National Taiwan University in 2022.

Background/purpose: The simulated pre-clinical operation skill test (PCOST) is part of the objective structured clinical examination (OSCE) and designed for clinical practice using manikins, physical typodonts, and instruments in the laboratory. This study tried to evaluate the influencing factors of the PCOST results for dental students. Materials and methods: The 32 5th-year dental students of the dental school of National Taiwan University (NTU) joined the PCOST. The contents of PCOST included two specialties: operative dentistry (OD) and prosthodontics (PS). The examination content of OD was tooth 36 mesio-occluso-distal (MOD) cavity preparation, and that of PS was crown preparation and temporary crown fabrication of tooth 11. Several factors including the gender, age, and dental student admission ways (with or without the skill tests) were evaluated. Each scoring item was calculated. The students also filled the feedback questionnaire about the examination questions and suggestions for the PCOST. Results: For both OD and PS, there were no significant differences in the mean PCOST scores between male and female dental students, between two groups of dental students with or without the skill tests in the admission process, and among three different age groups of dental students. According to the feedback questionnaire from the participated dental students, they were satisfied with the PCOST. Conclusion: The PCOST is a good simulated examination in clinical practice. However, we still need to collect more PCOST data and feedback to revise the guideline of the PCOST, and to promote the performance of clinical works of dental students.

Cytotoxicity and genotoxicity of DMABEE, a co-photoinitiator of resin polymerization, on CHO-K1 cells: Role of redox and carboxylesterase.

The 4-dimethylaminobenzoic acid ethyl ester (DMABEE) is an important co-initiator for resin polymerization in dental resinous materials. As a radical forming chemical with high lipophilicity, the genotoxicity and cytotoxicity of DMABEE deserve prudent investigation. In this study, we found that DMABEE reduced the viability and proliferation of Chinese hamster ovary (CHO-K1) cells in a dose-dependent manner, and altered cell morphology at higher concentrations. G0/G1 cell cycle arrest was induced by DMABEE at 0.25-0.75 mM, and cell proportion of sub-G0/G1 phase was significantly elevated at 1 mM while cell apoptosis was observed. Genotoxic effect was noted when cells were treated by 0.1 mM DMABEE, as revealed by increase of micronucleus formation. Reactive oxygen species overproduction was observed as cells treated with 0.75 and 1 mM, while elevation of intracellular glutathione was noticeable since 0.1 mM. Contrary to our expectation, pretreatment by N-acetyl-l-cysteine enhanced the toxicity of DMABEE on CHO-K1 cells. Catalase mildly reduced the toxic effect and carboxylesterase showed obvious ability to reverse the toxicity of DMABEE. These findings highlight the mechanism of DMABEE toxicity and provide clues for safety improvement of its application in clinical dental treatment.

Invasive Cervical Resorption-Distribution, Potential Predisposing Factors, and Clinical Characteristics.

INTRODUCTION: The purpose of this study was to investigate the distribution, predisposing factors, and clinical characteristics of invasive cervical resorption (ICR). METHODS: Cases with ICR from 2009-2019 were collected. Clinical records and radiographs were reviewed. Descriptive analysis was performed in combination with univariate analysis and the Fisher exact test. RESULTS: A total of 63 ICR teeth from 31 patients (14 men and 17 women) were found. The patients' ages ranged from 18-81 years, with a mean age of 45.77 years. Most patients had a single ICR lesion. Among the 63 ICR teeth, maxillary anterior teeth (47.62%) were the most commonly affected followed by maxillary premolars (20.63%). Maxillary teeth (76.19%) were more prone to ICR than mandibular teeth (23.81%). Most patients denied all major systemic diseases. The most common dental-related factors were dental/orofacial trauma (33.33%), periodontal treatment (26.98%), restoration/crown (17.46%), and orthodontic treatment (15.87%). Most teeth showed no percussion/palpation pain, probing depth >3 mm, abscess formation, sinus tracts, or periapical lesions. The pulp status was mainly vital (73.02%). The presence of percussion pain and probing depth differed significantly among Heithersay ICR classification groups. CONCLUSIONS: ICR showed no difference in sex or age. Maxillary anterior teeth were the most affected in a Taiwanese population. Traumatic injury, periodontal treatment, and orthodontic treatment were the significant predisposing factors. Furthermore, affected teeth typically lacked clinical signs and symptoms. Radiographic examination is critical for early diagnosis. In advanced cases, deep pockets and abscess formation were seen. These results are helpful for the diagnosis of ICR and further effective treatment.

Regulation of the regenerative activity of dental pulp stem cells from exfoliated deciduous teeth (SHED) of children by TGF-ß1 is associated with ALK5/Smad2, TAK1, p38 and MEK/ERK signaling.

Transforming growth factor-ß1 (TGF-ß1) regulates wound healing/regeneration and aging processes. Dental pulp stem cells from human exfoliated deciduous teeth (SHED) are cell sources for treatment of age-related disorders. We studied the effect of TGF-ß1 on SHED and related signaling. SHED were treated with TGF-ß1 with/without pretreatment/co-incubation by SB431542, U0126, 5Z-7-oxozeaenol or SB203580. Sircol collagen assay, 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyl tetrazolium bromide (MTT) assay, alkaline phosphatase (ALP) assay, RT-PCR, western blotting and PathScan phospho-ELISA were used to measure the effects. We found that SHED expressed ALK1, ALK3, ALK5, TGF-RII, betaglycan and endoglin mRNA. TGF-ß1 stimulated p-Smad2, p-TAK1, p-ERK, p-p38 and cyclooxygenase-2 (COX-2) protein expression. It enhanced proliferation and collagen content of SHED that were attenuated by SB431542, 5Z-7-oxozeaenol and SB203580, but not U0126. TGF-ß1 (0.5-1 ng/ml) stimulated ALP of SHED, whereas 5-10 ng/ml TGF-ß1 suppressed ALP. SB431542 reversed the effects of TGF-ß1. However, 5Z-7-oxozeaenol, SB203580 and U0126 only reversed the stimulatory effect of TGF-ß1 on ALP. Four inhibitors attenuated TGF-ß1-induced COX-2 expression. TGF-ß1-stimulated TIMP-1 and N-cadherin was inhibited by SB431542 and 5Z-7-oxozeaenol. These results indicate that TGF-ß1 affects SHED by differential regulation of ALK5/Smad2/3, TAK1, p38 and MEK/ERK. TGF-ß1 and SHED could potentially be used for tissue engineering/regeneration and treatment of age-related diseases.

Radicular cyst with actinomycotic infection in an upper anterior tooth.

Actinomycosis is an infection caused by filamentous, branching, Gram-positive anaerobic bacteria. It rarely infects the jawbone. This case report describes a patient with a left maxillary central incisor with an apical lesion and actinomycotic infection. A 23-year-old male patient underwent conventional root canal treatment of tooth 21, in a local dental clinic for about 1 year. However, percussion pain and a sinus tract that originated from tooth 21 were still present after treatment. Nonsurgical root canal treatment of tooth 21 was performed again but failed to relieve the symptoms. Therefore, apicoectomy and retrograde filling of the apical root canal with mineral trioxide aggregate were carried out. Periradicular bony defect was grafted by biocompatible material, and postoperative antibiotics (250 mg amoxicillin) were given three times daily for 5 days. Pathological examination of the removed periapical tissue showed a radicular cyst with actinomycosis. At the 9-month postoperative recall, the sinus tract had disappeared and radiographic examination showed healing of the apical lesion. Periradicular actinomycosis is one important reason for failure of nonsurgical endodontic treatment. Clinically, if the tooth shows a recurrent sinus tract and poor response to conventional root canal treatment combined with antibiotic control, apical actinomycotic infection should be highly suspected, and an alternative endodontic surgical approach is needed for successful treatment.

Thrombin activates Ras-CREB/ATF-1 signaling and stimulates c-fos, c-jun, and c-myc expression in human gingival fibroblasts.

BACKGROUND: Protease-activated receptors (PARs) can be stimulated by thrombin and other proteases generated by periodontal pathogens. Activation of PARs in gingival fibroblasts (GFs) can modulate wound healing and inflammatory responses in gingival tissues. METHODS: The mRNA expression of PARs and early responsive genes in GFs and other oral cells was studied by reverse transcription-polymerase chain reaction. Western blotting was used to study the activation of p38 and cAMP responsive element binding protein (CREB)/activating transcription factor (ATF)-1 as well as Ras. RESULTS: GFs, dental pulp cells, and buccal mucosal fibroblasts expressed PAR-1 and -3 receptors, whereas gingival keratinocytes expressed PAR-1 and -2 receptors. Stimulation of GFs by thrombin rapidly activated Ras signaling and the phosphorylation of CREB/ATF-1 and p38. Thrombin also stimulated the expression of c-fos in GFs within 1 hour of exposure. Stimulation of c-jun mRNA expression showed biphasic responses with two peaks after 1 and 8 hours of exposure. Elevated c-myc expression in GFs by thrombin was noted after 2 hours of exposure. Moreover, the stimulation of c-fos and c-myc mRNA expression by thrombin can be attenuated by D-Phe-Pro-ArgCH(2)Cl, a serine-proteinase inhibitor. CONCLUSIONS: PAR activation during gingival wounding or inflammation may stimulate Ras-CREB/ATF-1 signaling and c-fos, c-jun, and c-myc expression. This might be due to the proteinase activity of thrombin. These signaling events are important for wound healing and inflammatory responses in gingival tissues.

Effects of TGF-ß1 on plasminogen activation in human dental pulp cells: Role of ALK5/Smad2, TAK1 and MEK/ERK signalling.

Transforming growth factor-ß1 (TGF-ß1) plays an important role in the pulpal repair and dentinogenesis. Plasminogen activation (PA) system regulates extracellular matrix turnover. In this study, we investigated the effects of TGF-ß1 on PA system of dental pulp cells and its signalling pathways. Dental pulp cells were treated with different concentrations of TGF-ß1. MTT assay, reverse transcription-polymerase chain reaction, Western blotting and enzyme-linked immunosorbant assay (ELISA) were used to detect the effect of TGF-ß1 on cell viability, mRNA and protein expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1) as well as their secretion. The phosphorylation of Smad2 and TAK1 was analysed by Pathscan ELISA or Western blotting. Cells were pretreated with SB431542 (ALK5/Smad2/3 inhibitor), 5z-7-oxozeaenol (TAK1 inhibitor) and U0126 (MEK/ERK inhibitor) for examining the related signalling. TGF-ß1 slightly inhibited cell growth that was reversed by SB431542. TGF-ß1 upregulated both RNA and protein expression of PAI-1 and uPAR, whereas it downregulated uPA expression. Accordingly, TGF-ß1 stimulated PAI-1 and soluble uPAR (suPAR) secretion of pulp cells, whereas uPA secretion was inhibited. TGF-ß1 induced the phosphorylation of Smad2 and TAK1. In addition, SB431542, 5z-7-oxozeaenol and U0126 attenuated the TGF-ß1-induced secretion of PAI-1 and suPAR. These results indicate that TGF-ß1 is possibly involved in the repair/regeneration and inflammatory processes of dental pulp via regulation of PAI-1, uPA and uPAR. These effects of TGF-ß1 are related to activation of ALK5/Smad2, TAK1 and MEK/ERK signalling pathways. Clarifying the signal transduction for the effects of TGF-ß1 is helpful for pulpo-dentin regeneration and tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Clinical and Radiographic Characteristics of Vertical Root Fractures in Endodontically and Nonendodontically Treated Teeth.

INTRODUCTION: A vertical root fracture (VRF) is a root fracture extending along the longitudinal axis of roots and is often noted in endodontically treated teeth. However, the clinical and radiographic characteristics of VRFs are not completely known. METHODS: A total of 65 teeth with 68 vertical fractured roots in 58 Chinese patients were investigated. The clinical examination records and radiographic images were reviewed in detail. RESULTS: A total of 24 male (41.38%) and 34 female (58.62%) patients aged 25-90 years (average = 57 years) were included; 51 (87.93%) and 7 (12.07%) patients exhibited 1 tooth and 2 teeth with VRFs, respectively, in the dentition. VRFs occurred mainly in the mesial root (20 roots, 57.14%) of the mandibular molars (29 teeth, 44.62%). Clinically, teeth with VRFs usually presented a periodontal probing depth >5 mm (44 teeth, 91.67%, P < .001) with a prosthesis (55 teeth, 84.62%, P < .001) and a relatively intact dentition (42 patients exhibited <4 missing teeth in the dentition, 77.78%, P < .001). Most of the nonendodontically treated VRFs exhibited attrited occlusal surfaces. Radiographic characteristics of the teeth with VRFs were typically associated with prior root canal treatment (56 teeth, 86.15%, P < .001), periodontal bone loss (62 teeth, 95.38%, P < .001), apical bone loss (52 teeth, 80.00%, P < .001), and periodontal ligament widening (61 teeth, 93.85%, P < .001). The mesial roots of the mandibular molars were most susceptible to VRFs in both endodontically and nonendodontically treated teeth. CONCLUSIONS: These results elucidated some clinical and radiographic and diagnostic features that facilitate VRF identification.

Treatment of pulp floor and stripping perforation by mineral trioxide aggregate.

Mineral trioxide aggregate (MTA) has been widely used to repair various kinds of tooth perforations, but its use for obturation of the entire root canal has not been reported. We report two cases of tooth perforation successfully repaired with MTA. The first patient was a 78-year-old male with calcified canal and pulp floor perforation in the left maxillary first premolar. After bypass of the calcified palatal canal, both buccal and palatal canals were filled with gutta percha, and the pulp floor perforation was repaired with MTA. Clinical success with no evident radicular lesion was found at the 18-month follow-up. The second patient was a 51-year-old female with a stripping perforation in a C-shaped root canal of the right mandibular second molar detected after removal of a post. Following root canal debridement and calcium hydroxide therapy to control inflammation at the stripping perforation site, apical and furcation bone healing were observed by radiographic examination. The stripping perforation was repaired by obturation of the entire C-shaped root canal with MTA. Observation at the 9-month follow-up revealed bone healing without any clinical symptoms and signs. These cases suggest that MTA is an alternative root canal obturation material for treatment of stripping perforation in a C-shaped root canal and for repair of pulp floor perforation.

IL-1ß-induced MCP-1 expression and secretion of human dental pulp cells is related to TAK1, MEK/ERK, and PI3K/Akt signaling pathways.

OBJECTIVE: Interleukin-1ß (IL-1ß) is an inflammatory molecule of the dental pulp. IL-1ß stimulates cyclooxygenase-2 (COX-2) and prostaglandins production of pulp cells and affects the pulpal inflammation and repair. However, the effects of IL-1ß on Monocyte Chemotactic Factor-1 (MCP-1) of dental pulp cells and its relation to transforming growth factor ß-activated kinase-1 (TAK1), PI3K/Akt, and MEK/ERK signaling and COX activation are not fully clear. DESIGN: Human dental pulp cells were exposed to IL-1ß with/without pretreatment and co-incubation by aspirin (a COX inhibitor), 5z-7-oxozeaenol (a TAK1 inhibitor), LY294002 (a PI3K/Akt inhibitor) or U0126 (a MEK/ERK inhibitor). Viable cell number was evaluated by MTT assay. MCP-1 mRNA expression was tested by reverse transcriptase-polymerase chain reaction (RT-PCR). MCP-1 and COX-2 protein expression was studied by western blot. MCP-1 in the culture medium was measure by ELISA. RESULTS: IL-1ß showed little cytotoxicity to pulp cells. It stimulated MCP-1 mRNA and protein expression and MCP-1 secretion. Aspirin, U0126, LY294002 and 5z-7-oxozeaenol attenuated the IL-1ß-induced MCP-1 expression. In addition, 5z-7-oxozeaenol, LY294002, U0126 and aspirin prevented the IL-1ß-induced MCP-1 secretion of pulp cells. CONCLUSION: These results indicate that IL-1ß may be involved in the pulpal inflammatory and healing processes by inducing MCP-1 expression and secretion. These events are related to differential activation of TAK1, PI3K/Akt and MEK/ERK 1/2 signaling and COX activation. These results are important for future pharmacologic intervention of pulpal inflammatory diseases.

In vitro study of DP-bioglass paste for treatment of dentin hypersensitivity.

Sealing of exposed dentinal tubules is generally considered the most effective strategy to treat dentin hypersensitivity. On this account, we fabricated a DP-bioglass paste that created a homogeneous blockage on open dentinal tubules and formed a deep precipitate within dentinal tubules. DP-bioglass paste was prepared by mixing 20% to 60% phosphoric acid and DP-bioglass to treat dentin surfaces. CO2 laser irradiation was used to melt the DP-bioglass paste. The results demonstrated that 30% phosphoric acid was the optimum concentration to produce homogeneous occlusion on exposed dentinal tubules and 60 microm of sealing depth. CO2 laser irradiation could melt the DP-bioglass paste and create about 10 microm of sealing depth. Moreover, temperature rise during CO2 laser irradiation was only 4.86 +/- 0.47 degrees C. The results presented in this work suggested that DP-bioglass paste could produce considerable sealing depth in dentinal tubules with the potential of prolonging the therapeutic effect efficaciously.