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.

Effects of Camphorquinone on Cytotoxicity, Cell Cycle Regulation and Prostaglandin E2 Production of Dental Pulp Cells: Role of ROS, ATM/Chk2, MEK/ERK and Hemeoxygenase-1.

Camphorquinone (CQ) is a popularly-used photosensitizer in composite resin restoration. In this study, the effects of CQ on cytotoxicity and inflammation-related genes and proteins expression of pulp cells were investigated. The role of reactive oxygen species (ROS), ATM/Chk2/p53 and hemeoxygenase-1 (HO-1) and MEK/ERK signaling was also evaluated. We found that ROS and free radicals may play important role in CQ toxicity. CQ (1 and 2 mM) decreased the viability of pulp cells to about 70% and 50% of control, respectively. CQ also induced G2/M cell cycle arrest and apoptosis of pulp cells. The expression of type I collagen, cdc2, cyclin B, and cdc25C was inhibited, while p21, HO-1 and cyclooxygenase-2 (COX-2) were stimulated by CQ. CQ also activated ATM, Chk2, and p53 phosphorylation and GADD45α expression. Besides, exposure to CQ increased cellular ROS level and 8-isoprostane production. CQ also stimulated COX-2 expression and PGE2 production of pulp cells. The reduction of cell viability caused by CQ can be attenuated by N-acetyl-L-cysteine (NAC), catalase and superoxide dismutase (SOD), but can be promoted by Zinc protoporphyin (ZnPP). CQ stimulated ERK1/2 phosphorylation, and U0126 prevented the CQ-induced COX-2 expression and prostaglandin E2 (PGE2) production. These results indicate that CQ may cause cytotoxicity, cell cycle arrest, apoptosis, and PGE2 production of pulp cells. These events could be due to stimulation of ROS and 8-isoprostane production, ATM/Chk2/p53 signaling, HO-1, COX-2 and p21 expression, as well as the inhibition of cdc2, cdc25C and cyclin B1. These results are important for understanding the role of ROS in pathogenesis of pulp necrosis and pulpal inflammation after clinical composite resin filling.

Effect of interleukin-1ß on ICAM-1 expression of dental pulp cells: role of PI3K/Akt, MEK/ERK, and cyclooxygenase.

OBJECTIVE: Interleukin-1ß (IL-1ß) is an important inflammatory mediator of the dental pulp. IL-1ß stimulates cyclooxygenase-2 (COX-2) expression and prostanoid production of pulp cells and affects the inflammatory and healing processes of the dental pulp. There are two interleukin-1 (IL-1) receptors, IL-1RI and IL-1RII, with opposing effect after activation. However, the expression of IL-1Rs, the effects of IL-1ß on intercellular adhesion molecule-1 (ICAM-1) of dental pulp cells, and its relation to protein kinase B (Akt) signaling and COX activation are not clear. METHOD: Human dental pulp cells were treated with IL-1ß with/without pretreatment and co-incubation by LY294002 (a PI3K/Akt inhibitor), U0126 [a mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) inhibitor], aspirin (a COX inhibitor), or eugenol (a COX inhibitor) for different time periods. The expression of ICAM-1, IL-1RI, and IL-1RII messenger RNA (mRNA) was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR). ICAM-1 protein expression was examined by western blotting. Soluble ICAM-1 (sICAM-1) level in the culture medium was determined by enzyme-linked immunosorbent assay (ELISA). Activation of Akt and ERK by IL-1ß was measured by Pathscan p-Akt ELISA or western blot. Viable cell number was evaluated by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. RESULTS: Dental pulp cells expressed IL-1RI, but little IL-1RII. IL-1ß stimulated COX-2 and ICAM-1 mRNA and protein expression as well as sICAM-1 production of pulp cells. Aspirin and eugenol enhanced the IL-1ß-induced sICAM-1 production and ICAM-1 expression. IL-1ß rapidly activated Akt and ERK. LY294002 and U0126 attenuated IL-1ß-induced ICAM-1 expression and sICAM-1 production. CONCLUSIONS: These results reveal that IL-1ß may be involved in the pulpal inflammatory processes by stimulating ICAM-1 expression and secretion. These events are associated with IL-1RI expression and differential activation of PI3K/Akt and MEK/ERK and COX. CLINICAL RELEVANCE: Pharmacological inhibition of IL-1ß, IL-1RI, COX-2, ICAM-1, and related signaling pathways (MEK/ERK and PI3K/Akt) may be useful for the control of pulpal inflammation.

Treatment outcome of the teeth with cemental tears.

INTRODUCTION: A cemental tear is a special type of surface root fracture noted in combination with periodontal and/or periapical bony destruction. We hypothesized that clinical characteristics and treatment techniques may affect the prognosis of teeth with cemental tears. METHODS: Treatment outcome for the teeth with a cemental tear was assessed in a multicenter cemental tear study project. Of the 71 teeth with cemental tears, 38 teeth (53.5%) were extracted. The remaining 33 teeth (46.5%) were examined for a treatment outcome of healed, questionable, or failed. RESULTS: Outcome assessment found that 51.5% (17/33), 42.4% (14/33), and 6.1% (2/33) of teeth were classified as healed, questionable, and failed, respectively. Additive bivariate analysis indicated a significant difference between treatment outcome and the length (P = .01) and apicocoronal location (P = .02) of the separated root fragments. Logistic regression analysis found that treatment technique and apicocoronal location of cemental tears may affect the treatment outcome. The percentage of healed cemental tear cases located in the apical, middle, and cervical third of roots was 11.1%, 66.7%, and 60.0%, respectively. By surgical management, 57.7% of cemental tears were healed, whereas only 28.6% cases were healed after nonsurgical treatment. CONCLUSIONS: Most teeth with cemental tears can be retained to function by nonsurgical and surgical periodontal and endodontic treatment. Clinical diagnosis and treatment of cemental tears should also consider the apicocoronal location and the type of treatment technique to improve outcomes.

Analysis of the width of vertical root fracture in endodontically treated teeth by 2 micro-computed tomography systems.

INTRODUCTION: Early detection of vertical root fracture (VRF) is important for clinical endodontic practice. The purpose of this study was to measure the fracture width (distance between 2 sides of the fracture) of VRF teeth in vitro by using 2 micro-computed tomography (µ-CT) systems with different spatial resolution and voxel size. METHODS: Thirty-seven endodontically treated teeth with VRF were scanned by 80-µm pixel size µ-CT. Fifteen teeth with no obvious fracture line, blurred image, or fracture space less than 100 µm were scanned by 9-µm pixel size µ-CT. RESULTS: Presence of 2 VRF lines was more common in premolars (82%) than in molars (53%). In 7 premolars (32%) and 9 molars (60%), the VRF lines extended to within the apical 3 mm of the root. All fracture lines were detected by 9-µm pixel size µ-CT, but only 22 of 37 VRF teeth had vertical fracture identified by 80-µm µ-CT. From µ-CT examination, none of the fracture lines showed consistent and uniform fracture space. If 2 fracture lines were present, they were typically in opposite (not linear) directions. There was a significant correlation between 2 fracture lines or fracture lines extending within the 3 mm of the apex and fracture width greater than 100 µm. CONCLUSIONS: Application of 9-µm µ-CT can be accurately used for early detection of VRF. Fracture characteristics (eg, number of fracture lines, extension of fracture line) may affect the fracture width. Appropriate use of µ-CT technology can be helpful for early diagnosis of VRF.

Clinical fracture site, morphologic and histopathologic characteristics of cemental tear: role in endodontic lesions.

INTRODUCTION: Clinical research regarding the clinical and histopathologic characteristics of cemental tear is limited in the endodontic literature. The objective of this study was to evaluate the morphology, apicocoronal location, and the histologic characteristics of cemental tear. METHODS: The material was collected during 1987-2009 and consisted of 54 teeth that were presented with cemental tears by histologic examination. To investigate the atypical prospects among the groups of each variable, a series of the Poisson χ(2) goodness-of-fit tests were conducted to test for a fit of a discrete, uniform distribution. RESULTS: Cemental tear occurred mainly in incisors (74.1%), proximal root surfaces (79.6%), male patients (74.1%), and patients older than 60 years (72.3%). They were noted often in the middle third of root (45.3%), but 41.5% of cemental tears were noted over the apical region. The morphology of cemental tear was either small/thin piece-shaped (77.4% cases) involving 1 root surface or U-shaped (22.6%) involving >1 root surface. The size of cemental tear had an average length of 3.8 mm, width of 2.2 mm, and thickness of 0.9 mm. The separations of cemental tears occurred at cementodentinal junction (77.6%) relative to cementum (22.4%). The adhered soft tissue was either granulation tissue (92.3%) or cyst (7.7%). CONCLUSIONS: Cemental tear mainly occurs in incisors of male and older persons. It is also popularly noted in the apical region mimicking an endodontic lesion and some with cystic change. Clinically, endodontists should know this disease entity, make accurate early diagnosis, and totally remove the cemental tear during apical surgery to improve the prognosis.

Cemental tear: clinical characteristics and its predisposing factors.

INTRODUCTION: Cemental tears often show characteristics mimicking a periapical or periodontal lesion. This leads to difficulty in the early diagnosis of cemental tears. METHODS: In this multicenter study, 71 teeth with cemental tears being confirmed by direct inspection or histological examination were included. For each case, demographic data, dental history, clinical and radiographic findings, and the results of exploratory surgery were recorded and analyzed. RESULTS: Maxillary or mandibular incisors (76.1%) were most frequently affected by cemental tears. Univariate analysis of predisposing factors found that teeth with cemental tears occurred more commonly in men (77.5%) and patients older than 60 years of age (73.2%). Analysis of clinical characteristics showed that teeth with cemental tears were prone to have abscess formation (66.2%), a deep pocket >6 mm (73.2%), positive vitality test (65.3%), healthy antagonist teeth (84.3%), and moderate to severe attrition (77.9%). About 56.3% of cemental tears could be detected on preoperative radiographs. Further analysis of radiographic findings showed that teeth with cemental tears were more likely to have periodontal bone destruction (85.9%) or periapical bone destruction (64.8%). CONCLUSIONS: Endodontists and dentists may avoid misdiagnosis and unnecessary treatment of teeth with cemental tears if they can properly evaluate the radiographs and pulp vitality of teeth as well as know the predisposing factors and clinical characteristics of teeth with cemental tears in advance.

Transforming growth factor ß1 down-regulates Runx-2 and alkaline phosphatase activity of human dental pulp cells via ALK5/Smad2/3 signaling.

OBJECTIVE: Transforming growth factor ß1 (TGF-ß1) plays a role in repair and dentinogenesis in dental pulp. The purpose of this study was to study how TGF-ß1 affects 2 differentiation markers, Runt-related transcription factor 2 (Runx-2) and ALP, in dental pulp cells. STUDY DESIGN: Primary-cultured human dental pulp cells were treated with TGF-ß1 with or without pretreatment and coincubation with 1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto)butadiene (U0126, a mitogen-induced extracellular kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitor), Noggin (a bone morphogenetic protein inhibitor), or 4-(5-benzol[1,3]dioxol-5-yl-4-pyrldin-2-yl-1H-imidazol-2-yl)-benzamide hydrate (SB431542, an activin receptor-like kinase (ALK) 5/Smad2/3 inhibitor). The differentiation status of pulp cells was evaluated by ALP staining and quantitative ALP activity assay. Changes in ALP and Runx-2 mRNA expression were determined by reverse-transcription polymerase chain reaction. RESULTS: Cells under the treatment of TGF-ß1 (5 and 10 ng/mL) showed a decrease in ALP activity and gene expression of ALP and Runx-2. Pretreatment by U0126 and Noggin was not effective to prevent the TGF-ß1-induced decline of ALP activity. Interestingly, SB431542 prevented the TGF-ß1-induced decline of ALP activity and ALP and Runx-2 gene expression. CONCLUSION: TGF-ß1 down-regulates Runx-2 and ALP in human dental pulp cells via ALK5/Smad2/3 signaling. These events may play important roles at specific stages of pulpal repair and dentinogenesis.

The role of reactive oxygen species and hemeoxygenase-1 expression in the cytotoxicity, cell cycle alteration and apoptosis of dental pulp cells induced by BisGMA.

Biocompatibility of dentin bonding agents (DBAs) and resin composite is important to preserve the pulp vitality after operative restoration. Bisphenol-glycidyl-methacrylate (BisGMA) is one common monomer adding into DBAs and resin. In this study, we found that exposure of human dental pulp cells to BisGMA (>0.1 mM) led to cytotoxicity, G2/M cell cycle arrest and apoptosis as analyzed by propidium iodide (PI) and PI/annexin V dual fluorescent flow cytometry. These events were associated with a decline of cdc2, cdc25C and cyclinB1 expression at both mRNA and protein levels. BisGMA also induced the expression of hemeoxygenase-1 (HO-1), an oxidative stress responsive gene, in pulp cells. Catalase could prevent the BisGMA-induced alteration of cell cycle-related genes (cdc2, cdc25C, cyclinB1) and HO-1 expression in dental pulp cells. Interestingly, Zn-protoporphyrin (2.5-5 microM), a HO inhibitor, enhanced the BisGMA-induced reactive oxygen species (ROS) production and cytotoxicity. These results suggest that exposure to higher concentrations of BisGMA may stimulate ROS production, cell cycle arrest, apoptosis and cell death. Inducing the expression of HO-1 in dental pulp cells by BisGMA is mediated by ROS production and important to protect dental pulp against the toxicity by monomers present in composite resin and DBAs.

Cemental tear on a mandibular second molar: a case report.

A cemental tear is a special kind of root fracture that may cause rapid and localized periodontal destruction. Most cemental tears have been reported on bicuspids and incisors. Here we present a case of cemental tears on both the right mandibular first and second molars. The patient was a 72-year-old man who showed gingival swelling and a deep pocket over his right mandibular second molar as well as a deep periodontal pocket on the distolingual aspect of the first molar. During exploratory flap surgery, a detached root fragment on the mesial side of the second molar and a small root fragment on the lingual surface of the first molar were found and removed for biopsy. After histopathological examination, both root fragments were confirmed to be cemental tears. The periodontal defects were treated by osseous grafting and guided tissue regeneration. A postoperative probing depth of 4 mm on the second molar was recorded at 3 months and remained stable for 5 years. Where marked periapical and periodontal bony destruction are present, a cemental tear should be considered as a possible diagnosis, even in the molar teeth, for early treatment to improve prognosis.

The mechanisms of cytotoxicity of urethane dimethacrylate to Chinese hamster ovary cells.

Monomers released from resin-containing products may cause various adverse effects. Urethane dimethacrylate (UDMA) is a principal resin monomer and also a major component released from various dental resin materials. Thus the toxic effects and mechanisms should be elucidated for improving of its safety use. Here we investigated the effects of UDMA on the growth, cell cycle progression, reactive oxygen species (ROS) production and glutathione (GSH) alteration in CHO-K1 cells, and the preventive effects by antioxidants (NAC and catalase) were also evaluated. UDMA elicited growth inhibition (>0.025 mm) of CHO-K1 cells in a clearly dose-dependent manner. Cell cycle perturbation and ROS overproduction were also observed. A 0.1 mm UDMA-induced S-phase cell cycle arrest and ROS accumulation. Cell apoptosis and necrosis became significant when UDMA concentration was 0.25 mm. GSH depletion occurred at cells treated with 0.25 mm UDMA, a highly cytotoxic concentration at which point myriad cells were under apoptosis or necrosis. Thus GSH depletion can be crucial for the death of CHO-K1 cells. Furthermore NAC (0.5-10 mm) and catalase (250-1000 U/ml) obviously attenuated the UDMA-induced toxicity by reducing ROS generation and cell cycle disturbance, and the effects were dose-related. These results suggest that UDMA toxicity is associated with ROS production, GSH depletion, cell cycle disturbance and cell apoptosis/necrosis.

The effect of BisGMA on cyclooxygenase-2 expression, PGE2 production and cytotoxicity via reactive oxygen species- and MEK/ERK-dependent and -independent pathways.

After operative restoration, some monomers released from dentin bonding agents or composite resin may induce tissue inflammation and affect the vitality of dental pulp. Whether BisGMA, a major monomer of composite resin, may induce prostaglandin release and cytotoxicity to pulp cells and their mechanisms awaits investigation. We found that BisGMA induced cytotoxicity to human dental pulp cells at concentrations higher than 0.075 mm as analyzed by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. BisGMA (0.1 mm) also stimulated ERK phosphorylation, PGE(2) production, COX-2 mRNA and protein expression as well as ROS production (as indicated by an increase in cellular DCF fluorescence) in dental pulp cells. Catalase (500 and 1000 U/ml) and U0126 (10 and 20 microm, a MEK inhibitor) effectively prevented the BisGMA-induced ERK activation, PGE(2) production and COX-2 expression. Moreover, catalase can protect the pulp cells from BisGMA cytotoxicity, whereas aspirin and U0126 lacked of this protective activity. These results suggest that BisGMA released from composite resin may potentially affect the vitality of dental pulp and induce pulpal inflammation via stimulation of ROS production, MEK/ERK1/2 activation and subsequent COX-2 gene expression and PGE(2) production. Cytotoxicity of BisGMA to dental pulp cells is related to ROS production, but not directly mediated by MEK activation and PGE(2) production.