Improving oral health of older adults for healthy ageing.

The objective of this article is to discuss the importance of oral health in achieving healthy ageing and the role of all stakeholders in improving oral health for older adults. The World Health Organization defined healthy ageing as the process of developing and maintaining the functional ability that enables well-being in older age. It recognized healthy ageing as an important goal and the key to turn population ageing from a challenge to an opportunity. Healthy ageing has positive impacts on individual older adults, their families and societies. It enhances quality of life of older adults, strengthen family bonding of families and reduce resource demand of the societies. Maintaining oral health and function is essential in healthy ageing. Oral health affects systemic health, cognitive health and psychological health. Oral functions such as eating ensure nutritional health in older adults. Most oral diseases are preventable and oral function decline can be recovered by intervention. Unfortunately, oral diseases remain prevalent and oral function decline is being neglected in older adults. Policy makers, national dental associations, academics and healthcare professionals should collaborate to provide a patient-centred, comprehensive and integrated care to older adults. Health policy reforms are needed to reduce the global oral health inequalities in older adults. Population-wide prevention should be accessible, affordable and available to older adults. Universal oral health coverage is crucial for integration of oral health into general health care.

Tooth Wear in Older Adults: A Review of Clinical Studies.

INTRODUCTION: Tooth wear is a prevalent dental condition among older adults, leading to pain and adversely affecting aesthetics, functionality, and their overall quality of life. This review aims to update the information on tooth wear in older adults from the past five years and to provide guidance on the clinical management of tooth wear in older adults. METHODS: A literature search was conducted in three electronic databases, Scopus, Pubmed, and Embase, for English publications from January 2019 to December 2023 on clinical studies with participants aged 65 or above on tooth wear. A total of 307 articles were retrieved and 14 articles were finally included as references for this study. RESULTS: This review highlights the common causes of tooth wear and various risk factors, such as medical conditions, hyposalivation, dietary habits, oral hygiene practices, parafunctional habits, and occlusal factors, associated with tooth wear. It is crucial for oral health care professionals to diagnose and manage tooth wear at an early stage through a risk assessment and a clinical examination to avoid complex restorative procedures. Tooth wear management should prioritize prevention, aiming to control etiological and risk factors while employing non-restorative treatments. Restorative intervention, if indicated, should be simple, minimally invasive, and cost-effective. Tooth wear progression should be monitored regularly to determine if a further intervention is needed. CONCLUSION: Since the clinical studies on tooth wear in older adults over the past five years are limited and mainly cross-sectional, more interventional clinical studies are warranted to provide more clinical guidance on tooth wear management in older adults.

Influencing factors of examiner: Examples from certificated orthodontists board examination.

BACKGROUND: The rating result reflects not only the performance of the candidate but some extent of the examiner's preference. Examiner bias could be objective, which means it can't be changed by the examiner like gender, age, race, educational level, or professional experience. No study about examiner bias was performed in the dental education realm, especially in the orthodontic field. Therefore, this study aimed to figure out possible influencing factors in examiners from examples of the Taiwan Board of Orthodontist examination. METHODS: The examiner groups comprised 29 males and 21 females selected from the certificated Taiwan Board of Orthodontists. Every examiner would receive a series of lectures about rating standards before the exam. The score data were collected from 2009 to 2019. RESULTS: As for the univariate regression model of the Taiwan Board of Orthodontist examination, the experienced examiner with a certification of more than 15 years tends to rate more leniently, but female examiners tend to rate harsher. The scores would increase with the examiner's age in both the univariate regression model of self-prepared and assigned cases. CONCLUSION: As for the multivariate model of self-prepared exams, the elder and the examiner who work in private practice clinics tend to rate more leniently. As for the multivariate model of the assigned case exam, the score would be only affected by age. However, further studies are necessary to determine the direct relation among these factors.

Sirtuin 6 ameliorates arthritis through modulating cyclic AMP-responsive element binding protein/CCN1/cyclooxygenase 2 pathway in osteoblasts.

INTRODUCTION: CCN1 is an immediate-early gene product pivotal for arthritis progression. We have previously shown that sirtuin 6 (SIRT6) inhibited hypoxia-induced CCN1 expression in osteoblasts. Herein we examined the contribution of cyclic AMP-responsive element binding protein (CREB)/CRE to this suppressive action and the influence of CCN1 on cyclooxygenase (COX) 2 synthesis. MATERIALS AND METHODS: MC3T3-E1 murine osteoblasts were cultured under normoxia (21% oxygen) or hypoxia (2% oxygen). Expressions of CCN1, phospho-CREB (Ser133), COX2 and relevant kinases were assessed by Western blot. SIRT6 was overexpressed in cultured osteoblasts and arthritic joints by a lentiviral-based technique. Activities of CCN1 gene promoter constructs were examined by luciferase reporter assay. Interaction between CREB and CCN1 promoter was assessed by chromatin immunoprecipitation (ChIP). Collagen-induced arthritis (CIA) was established in 20 rats to evaluate the effects of SIRT6 therapy on osteoblastic expressions of phospho-CREB, CCN1 and COX2. RESULTS: SIRT6 suppressed hypoxia-enhanced CCN1 expression and CREB phosphorylation. Attenuation of calcium/calmodulin-dependent protein kinase II (CaMKII) may be responsible for SIRT6-induced CREB inhibition. CRE at - 286 bp upstream of the ATG start codon was essential for CCN1 expression under hypoxia and SIRT6 reduced hypoxia-stimulated CREB/CRE interaction. Forced expression of CREB rescued SIRT6-suppressed CCN1 synthesis. CCN1 induced COX2 expression in osteoblasts. In rat CIA, the therapeutic effect of SIRT6 was accompanied by decreases in osteoblastic expressions of phospho-CREB, CCN1 and COX2. CONCLUSION: Our study indicated that the benefits of SIRT6 to inflammatory arthritis and bone resorption are at least partially derived from its modulation of CREB/CCN1/COX2 pathway in osteoblasts.

Metformin Reduces Bone Resorption in Apical Periodontitis Through Regulation of Osteoblast and Osteoclast Differentiation.

INTRODUCTION: We have previously demonstrated that auxiliary metformin therapy promotes healing of apical periodontitis. Here we aimed to investigate the effects of metformin on osteoblast differentiation and osteoclast formation in cultured cells and rat apical periodontitis. METHODS: Murine pre-osteoblasts MC3T3-E1 and macrophages RAW264.7 were cultured under hypoxia (2% oxygen) or normoxia (21% oxygen) and stimulated with receptor activator of nuclear factor-κB ligand (RANKL) when indicated. Metformin was added to the cultures to evaluate its anti-hypoxic effects. Expressions of osteoblast differentiation regulator runt-related transcription factor 2 (RUNX2), RANKL, and osteoclast marker tartrate-resistant acid phosphatase (TRAP) were assessed by Western blot. Apical periodontitis was induced in mandibular first molars of 10 Sprague-Dawley rats. Root canal therapy with or without metformin supplement was performed. Periapical bone resorption was measured by micro-computed tomography. Immunohistochemistry was used to examine RUNX2, RANKL, and TRAP expressions. RESULTS: Hypoxia suppressed RUNX2 expression and enhanced RANKL synthesis in pre-osteoblasts. TRAP production increased in macrophages after hypoxia and/or RANKL stimulation. Metformin reversed hypoxia-induced RUNX2 suppression and RANKL synthesis in pre-osteoblasts. Metformin also inhibited hypoxia and RANKL-enhanced TRAP synthesis in macrophages. Intracanal metformin diminished bone loss in rat apical periodontitis. Comparing with vehicle control, cells lining bone surfaces in metformin-treated lesions had significantly stronger expression of RUNX2 and decreased synthesis of RANKL and TRAP. CONCLUSIONS: Alleviation of bone resorption by intracanal metformin was associated with enhanced osteoblast differentiation and diminished osteoclast formation in rat apical periodontitis. Our results endorsed the role of metformin as an effective medicament for inflammatory bone diseases.

Questionnaire survey on the satisfaction of SimEx dental education system.

Background/purpose: The SimEx is dental training system that applies new technology in a computerized dental simulator. The purpose of this study was to understand the usability satisfaction of the SimEx dental education and evaluation system by dental students and dentists at Tohoku University. Materials and methods: In this study, the Tohoku University IRB execution number was 2020-3-33. The number of subjects accepted was 59 at Tohoku University and divided into 4 groups based on years of clinical experience (Group A: 0 years; Group B: 1-2 years; Group C: 2-5 years; Group D: at least 5 years), and a total of 58 usability questionnaires were collected. Subjects completed the SimEx Usability Satisfaction Questionnaire after operating the SimEx (EPED Inc., Kaohsiung, Taiwan) course, which contained 16 questions. Results: Among the 58 questionnaires collected by Tohoku University, there were 19 undergraduate students (4th∼6th grade), 12 post-graduate students, 14 residents, and 13 dentists. Significant differences between Group A and Group B, and between Group A and Group D were found (P < 0.05). The same results were obtained for the "experience satisfaction index". In the items where significant differences were found, longer clinical experience tended to result in lower scores. Conclusion: From these results, we can conclude that the SimEx education and evaluation system facilitates students' self-learning, and this system is very useful for continued study and clinical skill training for dentists, especially for students and junior dentists with high usability satisfaction.

Restoration of a wide edentulous posterior site with two small-diameter implants: Biologically-driven alternative treatment.

BACKGROUND/PURPOSE: Crestal bone stability, implant rigidity and occlusal loading are issues with small-diameter implants. This article demonstrates the use of two small-diameter implants replacing a missing wide edentulous site and discusses factors that may affect bone changes. METHODS: Patients who wanted to restore an edentulous space measuring from 12 to 14 mm wide in the posterior region were offered an alternative treatment option, using two narrow or regular-diameter implants instead of one wide implant. In the study, the crestal bone stability of 12 implants in 6 edentulous sites was assessed by cone beam CTs and periapical radiographs in follow-up visits for up to 4 years. RESULTS: The bone level of all the implants was stable at buccal, lingual, mesial and distal sites, with mean values < 1 mm. The average buccal bone thickness was 1.15 ± 1.07 mm and lingual was 1.86 ± 0.89 mm, meaning that implants were surrounded by a sufficient amount of bone. The good treatment outcome may be attributed to the capability of fabricating better emergence profiles, angles (Mean: 20.67 ± 7.82° at the mesial and 20.25 ± 8.23° at the distal site) and cleansable embrasures of prostheses which are key to maintaining good oral hygiene and implant health. CONCLUSION: Using two narrow or regular-diameter implants to replace a single edentulous site measured around 12-14 mm wide in posterior region seemed to be a feasible treatment option. It is especially suitable for sites with ridge atrophy and/or patients suffering from systemic diseases.

Retrospective evaluation of gingival thickness and tissue stability after connective tissue grafting in Asian populations: 1 month to 3.5 years.

BACKGROUND/PURPOSE: The objectives of this retrospective study are to analyze post-surgical gingival thickness after connective tissue grafting in the Asian population and to assess its tissue stability for up to approximately 3.5 years. METHODS: A total of 111 grafted teeth and 57 nearby nongrafted teeth in 28 Asian patients who had undergone connective tissue grafting surgery were selected. Gingival thickness was measured by transgingival probing. The mean gingival thickness of the grafted teeth was compared with adjacent nongrafted teeth in the same individuals. The mean gingival thickness of the grafted teeth in different tooth types and at various time intervals were statistically analyzed. RESULTS: The average gingival thickness following connective tissue grafting is 1.99 ± 0.62 mm compared to 0.96 ± 0.40 mm with nongrafted teeth (P < .0001). The maxillary premolar is the tooth type that underwent connective tissue grafting most frequently in our study. Among different tooth types, mandibular molars showed the thickest gingival tissues whereas mandibular incisors presented the thinnest tissues. No statistically significant difference in the mean tissue thickness at different time intervals was observed. CONCLUSION: Connective tissue grafting is a predictable treatment modality for gingival phenotype conversion, even in Asians, achieving nearly 2 mm of gingival thickness on average, post-operation. Tissue stability after connective tissue grafting has been presented in our study. This quantitative assessment of the gingival thickness in Asians may encourage clinicians to deal with soft tissue architecture ahead of main surgical, restorative and orthodontic treatments in order to achieve pleasing treatment outcomes.

Three-phase treatment concept for skeletal Class III growing patients with severe space deficiency: A report of three cases with skeletally anchored maxillary protraction.

This report provides three-phase concept for treating skeletal Class III growing patients with severe space deficiency. Three cases are presented. All had received miniplate-anchored facemask treatment and followed till near completion of growth. Infrazygomatic miniplates were used for both facemask protraction and distalization of the dentition to relieve crowding. With the aid of bone-anchored facemask, maxillary protraction may be continued independent of the orthodontic tooth movement even in late postpubertal growth peak stage. With cephalometric superimpositions using the structural method, we have demonstrated how vertical dental change could affect the skeletal changes and overall clinical outcomes. The persistent mandibular growth during pubertal growth spurt plays a main role in decreasing the effects of maxillary protraction. To keep up with the mandibular growth, we recommend using skeletally anchored facemask long-term till the end of growth spurt. Applying maxillary protraction from infrazygomatic miniplates exposed at the molar area has the merits that it avoids unwanted palatal rotation and that the miniplates maybe used as orthodontic anchorage when indicated. We emphasize the importance of planning the treatment contemplating the skeletal developmental stage and the completion of dental arches. This prolonged orthopedic treatment may contribute to greater long-term effects and stability.

Intracanal Metformin Promotes Healing of Apical Periodontitis via Suppressing Inducible Nitric Oxide Synthase Expression and Monocyte Recruitment.

INTRODUCTION: We have previously shown that intracanal metformin ameliorates apical periodontitis, partially by modulation of osteoblast apoptosis. The action of metformin on other cell types pertinent to the development of apical periodontitis needs to be examined. In the present study, we aimed to analyze whether its effects on the expression of inducible nitric oxide synthase (iNOS) and monocyte recruitment contribute to the therapeutic effect on apical periodontitis. METHODS: Lipopolysaccharide (LPS)-induced expression of iNOS in a human monocytic cell line, Mono-Mac-6, was assessed by Western blot. The amount of nitrite in culture medium was assessed to quantify nitric oxide (NO) production. C-C motif chemokine ligand-2 (CCL-2) synthesis was measured by enzyme-linked immunosorbent assay. Experimental apical periodontitis in rats was treated with root canal debridement with or without intracanal metformin medication. Lesion progression was assessed by conventional radiography and micro-computed tomographic imaging. Cellular expression of iNOS and the number of monocytes/macrophages were assessed by immunohistochemistry. RESULTS: Metformin suppressed LPS-induced iNOS and NO production by monocytes. More importantly, metformin inhibited LPS-enhanced CCL-2 synthesis through modulation of the iNOS/NO pathway. Intracanal metformin reduced bone resorption associated with apical periodontitis and suppressed iNOS expression and monocyte recruitment. CONCLUSIONS: Our results confirmed the therapeutic efficacy of intracanal metformin for apical periodontitis. Suppression of monocyte recruitment through modulation of iNOS expression and NO production is an important mechanism underlying the beneficial effect of metformin.

Staged orthodontic treatment in preparation for immediate implant placement: A clinical report with a 5-year follow-up.

Anterior implant restoration is one of the most challenging restorative procedures, especially for sites with vertical and/or horizontal hard and soft tissue deformities. Orthodontic extrusion before implant placement may be the best means of overcoming vertical deficiencies. This article describes a modification to the standard technique, involving staged orthodontic extrusion and buccal root torque. The main advantage of this modification is that it encourages bone and soft tissue development, thereby allowing the patient to receive immediate or early implant treatment. A clinical procedure is presented to illustrate the modified technique that resulted in an esthetically pleasing and stable 5-year outcome.

Metformin Ameliorates Periapical Lesions through Suppression of Hypoxia-induced Apoptosis of Osteoblasts.

INTRODUCTION: Intramuscular injection of metformin has been shown to inhibit the progression of periapical lesions in rats by decreasing the number of receptor activator of nuclear factor-κß ligand- and tartrate-resistant acid phosphatase-positive cells. In this study, we investigated the effect of metformin on hypoxia-induced apoptosis of osteoblasts and the therapeutic activity of intracanal metformin in induced periapical lesions in rats. METHODS: The influence of metformin on hypoxia-induced mitochondrial superoxide production in human osteoblasts was examined by using MitoSOX (Invitrogen, Carlsbad, CA) fluorescence dye signaling. The release of cytochrome c from mitochondria and the cleavage of procaspase-9 and poly(adenosine diphosphate-ribose) polymerase were evaluated by Western blot analysis. Apoptotic cell fraction was assessed by DNA content flow cytometry. In a rat model of induced periapical lesions, the effect of intracanal metformin on disease progression was appraised by 2-dimensional radiography and micro-computed tomographic imaging. Oxidative lesions and apoptotic activity of osteoblasts in vivo were estimated, respectively, by 8-hydroxy-2'-deoxyguanosine staining and terminal deoxynucleotidyl transferase dUTP nick end labeling. RESULTS: Metformin inhibited hypoxia-enhanced mitochondrial superoxide production in osteoblasts. Metformin suppressed hypoxia-induced cytochrome c release from mitochondria and the cleavage of procaspase-9 and poly(adenosine diphosphate-ribose) polymerase. Metformin repressed hypoxia-augmented apoptotic cell fraction. In a rat model, intracanal metformin diminished the size of periapical lesions and the oxidative damage and apoptotic activity in osteoblasts. CONCLUSIONS: Hypoxia increased oxidative stress in osteoblasts and enhanced cell death through activation of the mitochondrial pathway of apoptosis. Metformin attenuated the oxidative and cytotoxic action of hypoxia. The therapeutic effect of metformin on periapical lesions is partially caused by its antioxidative activity.

Airway increase after open bite closure with temporary anchorage devices for intrusion of the upper posteriors: Evidence from 2D cephalometric measurements and 3D magnetic resonance imaging.

OBJECTIVE: The aim of this study was to analyse morphological changes in the upper airways in patients with anterior open bite treated with temporary anchorage devices for intrusion of upper posterior teeth. MATERIALS AND METHODS: Twelve nonobese (body mass index: <25) anterior open bite patients between the ages of 19 and 44 years (mean age: 22.83 ± 8.19 years) were recruited for this study. Cephalometric radiographs and magnetic resonance imaging (MRI) scans before and after anterior bite closure without bracketing on anterior teeth were used to measure the upper airway, which was divided into retropalatal and retroglossal regions. RESULTS: The mandibular plane angle and lower facial height were significantly reduced by intrusion of the upper posteriors and autorotation of the mandible. The retroglossal airway width (AW2) and retroglossal area (RG area) measured on cephalometric radiographs both increased significantly after treatment. Retroglossal volume increased and the retroglossal width/length ratio decreased significantly in MRI analysis. All other measurements were not significantly changed. However, no statistically significant correlations were observed between all measurements in 2D and 3D images, with the exception of the AW2 linear measurement in 2D images correlating with the AP length in MRI axial view images (r = 0.56, P = 0.0430). CONCLUSION: Counterclockwise rotation of the mandible after anterior open bite closed using orthodontic treatment changed the airway morphology. Retroglossal volume significantly increased and the airway shape became less elliptical after bite closure.

Increased Expression of Glutaminase in Osteoblasts Promotes Macrophage Recruitment in Periapical Lesions.

INTRODUCTION: Recently, we have shown that tissue hypoxia stimulates the progression of periapical lesions by up-regulating glycolysis-dependent apoptosis of osteoblasts. Other facets of hypoxia-induced metabolic reprogramming in disease pathogenesis require further investigation. In this study, we examined the connection between hypoxia-augmented glutamine catabolism in osteoblasts and the development of periapical lesions. METHODS: Primary human osteoblasts were cultured under hypoxia. The expression of glutaminase 1 (GLS1) was examined using Western blot analysis. The production of glutamate was measured by colorimetric assay. Knockdown of GLS1 was performed with small interfering RNA technology. C-C motif chemokine ligand 2 (CCL2) secretion and chemotaxis of J774 macrophages were examined by enzyme-linked immunosorbent assay and transwell migration assay, respectively. In a rat model of induced periapical lesions, the relations between disease progression and osteoblastic expression of GLS1 or macrophage recruitment were studied. RESULTS: Hypoxia enhanced GLS1 expression and subsequent glutamate production in osteoblasts. Glutamate induced chemoattraction of macrophages by osteoblasts through up-regulation of CCL2 synthesis. Hypoxia promoted CCL2 secretion and macrophage recruitment through augmentation of glutaminolysis. Knockdown of GLS1 abolished hypoxia-induced effects. In rat periapical lesions, progressive bone resorption was significantly related to elevated GLS1 expression in osteoblasts and increased macrophage recruitment. CONCLUSIONS: In addition to the rise in glycolytic activity, the progression of periapical lesions is also associated with enhanced glutamine catabolism in osteoblasts. GLS1 may be a potential therapeutic target in the management of periapical lesions.

Influence of heat treatment on cyclic fatigue and cutting efficiency of ProTaper Universal F2 instruments.

BACKGROUND/PURPOSE: Heat pretreatment can improve the cyclic fatigue life of nickel-titanium (NiTi) instruments. This study evaluated the effects of two different heat treatments on the cyclic fatigue resistance and cutting efficiency of ProTaper Universal F2 files. MATERIALS AND METHODS: The files were divided into three groups: no treatment (control), heat treatment at 400°C (HT400) and heat treatment at 600°C (HT600). The phase transformation of the files was evaluated by differential scanning calorimetry. In cyclic fatigue tests, the differences in file performance in four simulated canals among the three groups were assessed. The cutting efficiency was tested at four cutting portions (3 mm, 6 mm, 9 mm, and 12 mm) from the tip of the file. RESULTS: Differential scanning calorimetry showed a prolonged phase transformation of the files only after 600°C treatment. At 3 mm cutting portion, 400°C heat-treated files had significantly better cutting ability than those in the control group. However, the files in the HT600 group had significantly lower cutting efficiency than those in the other two groups at the four tested positions. In the cyclic fatigue test, fatigue lives of the files after 400°C and 600°C treatment were prolonged from 2.1 to 2.8 times and from 1.7 to 5.5 times, respectively. CONCLUSION: Although 600°C treatment increased resistance to cyclic fatigue, it reduced the cutting efficiency of the files. The 400°C treatment maintained the cutting ability and prolonged the cyclic fatigue life of the files. Therefore, for clinical use of ProTaper Universal F2 files, 400°C pretreatment is a better choice than 600°C pretreatment.

Polishing mechanism of light-initiated dental composite: Geometric optics approach.

BACKGROUND/PURPOSE: For light-initiated dental hybrid composites, reinforcing particles are much stiffer than the matrix, which makes the surface rugged after inadequate polish and favors bacterial adhesion and biofilm redevelopment. The aim of the study was to investigate the polishing mechanism via the geometric optics approach. METHODS: We defined the polishing abilities of six instruments using the obtained gloss values through the geometric optics approach (micro-Tri-gloss with 20°, 60°, and 85° measurement angles). The surface texture was validated using a field emission scanning electron microscope (FE-SEM). Based on the gloss values, we sorted polishing tools into three abrasive levels, and proposed polishing sequences to test the hypothesis that similar abrasive levels would leave equivalent gloss levels on dental composites. RESULTS: The three proposed, tested polishing sequences included: S1, Sof-Lex XT coarse disc, Sof-Lex XT fine disc, and OccluBrush; S2, Sof-Lex XT coarse disc, Prisma Gloss polishing paste, and OccluBrush; and S3, Sof-Lex XT coarse disc, Enhance finishing cups, and OccluBrush. S1 demonstrated significantly higher surface gloss than the other procedures (p < 0.05). The surface textures (FE-SEM micrographs) correlated well with the obtained gloss values. CONCLUSION: Nominally similar abrasive abilities did not result in equivalent polish levels, indicating that the polishing tools must be evaluated and cannot be judged based on their compositions or abrasive sizes. The geometric optic approach is an efficient and nondestructive method to characterize the polished surface of dental composites.

NADPH oxidase 4 is involved in the triethylene glycol dimethacrylate-induced reactive oxygen species and apoptosis in human embryonic palatal mesenchymal and dental pulp cells.

OBJECTIVES: Triethylene glycol dimethacrylate (TEGDMA) is a common component of resin-based dental composites and endodontic sealers. TEGDMA induces apoptosis in several types of cells. However, the mechanisms are not completely understood. The aim of this study was to investigate the mechanisms underlying TEGDMA-induced apoptosis in human embryonic palatal mesenchymal (HEPM) pre-osteoblasts and primary human dental pulp (HDP) cells. MATERIAL AND METHODS: Cell viability was examined after TEGDMA treatment. Cell cycle progression was checked by flow cytometry. Apoptotic cells were evaluated using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay and visualized by fluorescence microscopy. Western blot analyses were performed to determine expressions of apoptosis-related proteins. The production of reactive oxygen species (ROS) was detected using flow cytometry. NADPH oxidase 4 (NOX4) expression levels were investigated using real-time quantitative polymerase chain reaction and Western blot analyses. RESULTS: TEGDMA increased cytosol cytochrome c levels and activated caspase-9 in HEPM and HDP cells. TEGDMA decreased the expression of anti-apoptotic protein Bcl-XL. TEGDMA-induced apoptosis was inhibited by caspase-9-specific inhibitor, anti-oxidants, NOX inhibitor, NOX4 inhibitor, and NOX4 small interfering RNA (siRNA). TEGDMA increased ROS production and upregulated NOX4 mRNA and protein expression. TEGDMA-induced intracellular ROS production was inhibited by NOX inhibitor and NOX4 inhibitor. CONCLUSIONS: We demonstrate significant involvement of NOX4 in the TEGDMA-induced ROS. NOX4-derived ROS subsequently induces mitochondrial cytochrome c release leading to apoptosis through activation of the intrinsic apoptotic pathway. CLINICAL RELEVANCE: NOX4 may be a potential target for strategies to prevent or ameliorate the TEGDMA-induced toxicity in HEPM and HDP cells.

Simvastatin suppresses osteoblastic expression of Cyr61 and progression of apical periodontitis through enhancement of the transcription factor Forkhead/winged helix box protein O3a.

INTRODUCTION: In this study, the role of transcription factor Forkhead/winged helix box protein O3a (FoxO3a) in Cyr61 expression and its modulation by simvastatin were investigated in cultured murine osteoblasts and a rat model of induced apical periodontitis. We also examined the effects of simvastatin on the synthesis of chemokine CCL2 and chemotaxis of macrophages in vitro. METHODS: We assessed tumor necrosis factor (TNF)-α-stimulated expression of Cyr61 and phosphorylated inactive FoxO3a (p-FoxO3a) in MC3T3-E1 murine osteoblasts by Western analysis. Forced expression of FoxO3a by lentiviral-based gene transduction was performed, and its effect on Cyr61 expression was evaluated. The modulation of CCL2 secretion and macrophage chemotaxis by simvastatin were examined by enzyme-linked immunosorbent assay and transwell migration assay, respectively. In a rat model of induced apical periodontitis, the relation between disease progression and osteoblastic expression of Cyr61, p-FoxO3a, and CCL2 and macrophage recruitment were studied by radiographic and immunohistochemistry analyses. RESULTS: Western blot analysis showed enhanced expression of Cyr61 and p-FoxO3a after TNF-α treatment in a time-dependent manner. Simvastatin significantly counteracted the actions of TNF-α. Forced expression of FoxO3a reduced TNF-α-stimulated Cyr61 synthesis. Simvastatin and FoxO3a diminished TNF-α-induced CCL2 secretion and macrophage recruitment, whereas Cyr61 partially restored the stimulating action. In rat periapical lesions, simvastatin significantly attenuated bone resorption, reduced osteoblastic expressions of Cyr61, p-FoxO3a, and CCL2, and suppressed macrophage recruitment. CONCLUSIONS: Simvastatin may alleviate periapical lesions by enhancing FoxO3a activity to suppress the synthesis of Cyr61 in osteoblasts. Moreover, the downstream effector mechanism of Cyr61 may involve CCL2 production and macrophage recruitment.

Simvastatin inhibits cysteine-rich protein 61 expression in rheumatoid arthritis synovial fibroblasts through the regulation of sirtuin-1/FoxO3a signaling.

OBJECTIVE: To examine the role of sirtuin-1 (SIRT-1)/FoxO3a in the expression of cysteine-rich protein 61 (CYR-61) in rheumatoid arthritis synovial fibroblasts (RASFs) and the influence of simvastatin on this pathway, and to determine the relationship between disease progression and FoxO3a/CYR-61 signaling in synovial fibroblasts in vivo using a rat model of collagen-induced arthritis (CIA). METHODS: In RASFs, the expression of CYR-61 and SIRT-1, the localization of FoxO3a in the nucleus/cytoplasm, and the phosphorylation/acetylation of FoxO3a were examined by Western blotting. Secretion of CCL20 was assessed by enzyme-linked immunosorbent assay. Promoter activity of the Cyr61 gene was evaluated by luciferase assay, with or without forced expression of FoxO3a and SIRT-1 by lentiviral transduction. FoxO3a-Cyr61 promoter interaction was examined by chromatin immunoprecipitation. In rats with CIA, the expression of CYR-61 and phosphorylated FoxO3a in synovial fibroblasts was examined by immunohistochemistry. RESULTS: In RASFs, simvastatin suppressed the tumor necrosis factor α (TNFα)-induced production of CYR-61 and CCL20. Nuclear levels of FoxO3a were decreased after TNFα stimulation of RASFs, and forced expression of FoxO3a reversed the inductive effects of TNFα on CYR-61. Simvastatin inhibited the nuclear export, phosphorylation, and acetylation of FoxO3a and maintained its binding to the Cyr61 promoter. Forced expression of SIRT-1 in RASFs led to decreased levels of CYR-61 and deacetylation of FoxO3a. Following treatment with simvastatin, the expression of SIRT-1 was up-regulated and SIRT-1/FoxO3a binding was enhanced in RASFs. In rats with CIA, intraarticular injection of simvastatin alleviated arthritis and suppressed CYR-61 expression and FoxO3a phosphorylation in synovial fibroblasts. CONCLUSION: CYR-61 is important in the pathogenesis of RA, and SIRT-1/FoxO3a signaling is crucial to induction of CYR-61 in RASFs. Simvastatin plays a beneficial role in inflammatory arthritis through its up-regulation of SIRT-1/FoxO3a signaling in synovial fibroblasts. Continued study of the pathways linking sirtuins, FoxO proteins, and the inflammatory responses of RASFs may provide new insights into the pathophysiology of RA.

Effect of simulated debracketing on enamel damage.

BACKGROUND/PURPOSE: A smooth enamel surface after the removal of a bracket from a tooth is essential for both esthetic demands and the prevention of plaque accumulation. The purpose of this study was to evaluate enamel damage caused by three standardized debracketing techniques. METHODS: We established three standardized test devices based on the principles of the squeezing, shearing, and tensile testing methods, which were simulated using a How Plier (TASK 60-306), a Direct Bond Bracket Remover (TASK 60-335 T), and a Lift-Off Debracketing Instrument (3 M-Unitek 444-761), respectively. Thirty teeth in each group were evaluated after debracketing. An optical stereomicroscope and a CCD camera with a computerized image analysis system were used to ascertain the proportion of remnant adhesive area (RAE) on the enamel surface. Fractography was analyzed using a scanning electron microscope. RESULTS: The squeezing debracketing method exhibited the highest debonding force (54.3 ± 7.0 N) and the least damage to the enamel surface (RAE = 99.5% ± 2.4%). The tensile debracketing method preserved most of the adhesive on the enamel surface (RAE = 98.7% ± 3.3%) and required the least debonding force (6.8 ± 1.2 N). However, the shearing debracketing method exhibited a significantly higher debonding force (32.0 ± 8.2 N) and smaller RAE (77.3% ± 33.5%) compared to the tensile debracketing method (p < 0.05). Three specimens appeared to have vertical fractures on their enamel prisms when using the shearing method. CONCLUSION: With the proposed method, we conclude that the squeezing and tensile methods are acceptable for clinical use when debracketing, whereas the Direct Bond Bracket Remover may cause shearing failure, leading to a risk for enamel damage.