Accuracy of four different digital intraoral scanners: effects of the presence of orthodontic brackets and wire.

OBJECTIVE: The objective of this study was to compare the accuracy of four different digital intraoral scanners and the effects of buccal brackets and orthodontic wire. METHODS: For this study, three sets of models (Control model, BKT model with buccal bracket, and WBKT model with buccal bracket and orthodontic wire) were scanned using four different types of intraoral scanners: E4D dentist, iTero, Trios, and Zfx IntraScan. The mesiodistal width of the teeth, intercanine width, and intermolar width measured by four scanners were compared. Three-dimensional (3D) images of the brackets were taken using the four scanners. Data were analyzed with one-way ANOVA, independent t test, and post-hoc Tukey test at a significance level of P < 0.05. RESULTS: When comparing the 3D images with manual measurements using a traditional caliper, iTero and Trios showed the highest accuracy in horizontal measurements.iTero had the lowest values in Devmax-min of maxillary intermolar and intercanine widths (0.16 mm and 0.20 mm, respectively), whereas Trios had the lowest values in Devmax-min of mandibular intermolar and intercanine widths (0.36 mm and 0.14 mm, respectively). The horizontal variables were barely affected by the presence of buccal brackets and orthodontic wire. Comparison of 3D bracket images scanned by the four scanners showed differences in image distortion among the scanners. Bracket characteristics did not affect the 3D bracket images. CONCLUSIONS: The four intraoral scanners used in this study differed in accuracy. However, the results acquired by iTero and Trios were more reliable. Effects of buccal brackets and orthodontic wire on the 3D images taken by intraoral scanners were not clinically significant.

Changes in views on digital intraoral scanners among dental hygienists after training in digital impression taking.

BACKGROUNDS: Despite the rapid development of digital dentistry, the use of digital intraoral scanners remains limited. The aim of this study was to evaluate the changes in views on intraoral scanners among dental hygienists after training. METHODS: Thirty-four dental hygienists with >3 years of clinical experience participated and were divided into 2 groups : iTero and Trios groups. Participants of each group practiced the usage of both intraoral scanners, for total 12 times over 4 sessions, Questionnaires were given to participants at two different times; prior to and after the completion of the training sessions. The parameters of questionnaires included on difficulty of use, patient discomfort, awareness, preference, and clinical usefulness of intraoral scanners and comparison of two types of scanners. RESULTS: Upon the completion of the training, both iTero and Trios groups gave positive feedback on anticipated accuracy, efficiency, and clinical usefulness. More participants of the iTero group responded that the level of difficulty of use and patient discomfort was greater than Trios. Both groups preferred Trios for its clinical usefulness. CONCLUSIONS: The perceptions of dental hygienists on usage of intraoral scanner and digital impression improved positively with the training. The participants favored Trios over iTero in terms of difficulty of use , patient comfort, and clinical usefulness. This study showed that appropriate training could change the views on the efficiency of intraoral scanners positively among dental hygienists.

Effects of 3 endodontic bioactive cements on osteogenic differentiation in mesenchymal stem cells.

INTRODUCTION: Because a root-end filling material comes into contact with the surrounding cells or tissues, understanding the cell-material interfacial activity is important. Thus, the purpose of this study was to assess the biocompatibility of 3 endodontic bioactive cements (MTA [Dentsply, Tulsa, OK], Bioaggregate [BA; Innovative Bioceramix, Vancouver, BC, Canada], and Biodentine [BD; Septodont, St Maur des Fosses, France]) and to investigate the effect of cements on the differentiation of mesenchymal stem cells. METHODS: Cell viability, mineralization, and differentiation were evaluated using an 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) assay and alkaline phosphatase (ALP) staining. The expressions of ALP, osteocalcin, and bone sialoprotein at the gene level were detected by reverse-transcription polymerase chain reaction and real-time polymerase chain reaction. RESULTS: Cell viability of BD in concentrations of 1, 1/2, and 1/4 was significantly lower than MTA and BA (P < .05). There was no statistically significant difference in cell viability between materials in concentrations of 1/10 and 1/50 (P < .05). The messenger RNA level of osteogenic genes increased significantly in the MTA and BA groups compared with controls (P < .05). However, although the messenger RNA level of osteogenic genes increased in the BD group, there was no statistically significant difference compared with controls. MTA, BA, and BD led to an increase in ALP staining compared with controls. CONCLUSIONS: In conclusion, MTA, BA, and BD have effects on osteoblast differentiation in mesenchymal stem cells, suggesting that these cements may be useful for root-end filling material.

Orphan nuclear receptor chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) protein negatively regulates bone morphogenetic protein 2-induced osteoblast differentiation through suppressing runt-related gene 2 (Runx2) activity.

Chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) is an orphan nuclear receptor of the steroid-thyroid hormone receptor superfamily. COUP-TFII is widely expressed in multiple tissues and organs throughout embryonic development and has been shown to regulate cellular growth, differentiation, and organ development. However, the role of COUP-TFII in osteoblast differentiation has not been systematically evaluated. In the present study, COUP-TFII was strongly expressed in multipotential mesenchymal cells, and the endogenous expression level decreased during osteoblast differentiation. Overexpression of COUP-TFII inhibited bone morphogenetic protein 2 (BMP2)-induced osteoblastic gene expression. The results of alkaline phosphatase, Alizarin Red staining, and osteocalcin production assay showed that COUP-TFII overexpression blocks BMP2-induced osteoblast differentiation. In contrast, the down-regulation of COUP-TFII synergistically induced the expression of BMP2-induced osteoblastic genes and osteoblast differentiation. Furthermore, the immunoprecipitation assay showed that COUP-TFII and Runx2 physically interacted and COUP-TFII significantly impaired the Runx2-dependent activation of the osteocalcin promoter. From the ChIP assay, we found that COUP-TFII repressed DNA binding of Runx2 to the osteocalcin gene, whereas Runx2 inhibited COUP-TFII expression via direct binding to the COUP-TFII promoter. Taken together, these findings demonstrate that COUP-TFII negatively regulates osteoblast differentiation via interaction with Runx2, and during the differentiation state, BMP2-induced Runx2 represses COUP-TFII expression and promotes osteoblast differentiation.

Metformin induces osteoblast differentiation via orphan nuclear receptor SHP-mediated transactivation of Runx2.

Metformin is an oral anti-diabetic drug of the biguanide class that is commonly used to treat type 2 diabetes mellitus. This study examined the molecular mechanism for the action of metformin on osteoblast differentiation. Metformin-induced mRNA expression of the osteogenic genes and small heterodimer partner (SHP) in MC3T3E1 cells were determined by RT-PCR and real-time PCR. Metformin increased significantly the expression of the key osteogenic genes, such as alkaline phosphatase (ALP), osteocalcin (OC) and bone sialoprotein (BSP) as well as SHP. Transient transfection assays were performed in MC3T3E1 cells to confirm the effects of metformin on SHP, OC and Runx2 promoter activities. Metformin increased the transcription of the SHP and OC genes, and the metformin effect was inhibited by dominant negative form of AMPK (DN-AMPK) or compound C (an inhibitor of AMPK). The adenoviral overexpression of SHP increased significantly the level of ALP staining and OC production. However, metformin did not have any significant effect on osteogenic gene expression, ALP staining and activity, and OC production in SHP null (SHP-/-) primary calvarial cells. Moreover, upstream stimulatory factor-1 (USF-1) specifically mediated metformin-induced SHP gene expression. In addition, metformin-induced AMPK activation increased the level of Runx2 mRNA and protein. However, USF-1 and SHP were not involved in metformin-induced Runx2 expression. Transient transfection and chromatin immunoprecipitation assays confirmed that metformin-induced SHP interacts physically and forms a complex with Runx2 on the osteocalcin gene promoter in MC3T3E1 cells. These results suggest that metformin may stimulate osteoblast differentiation through the transactivation of Runx2 via AMPK/USF-1/SHP regulatory cascade in mouse calvaria-derived cells.

AMP-activated protein kinase (AMPK) positively regulates osteoblast differentiation via induction of Dlx5-dependent Runx2 expression in MC3T3E1 cells.

This study examined the role of AMPK activation in osteoblast differentiation and the underlining mechanism. An AMPK activator (AICAR or metformin) stimulated osteoblast differentiation with increases in ALP and OC protein production as well as the induction of AMPK phosphorylation in MC3T3E1 cells. In addition, metformin induced the phosphorylation of Smad1/5/8 and expression of Dlx5 and Runx2, whereas compound C or dominant negative AMPK inhibited these effects. Transient transfection studies also showed that metformin increased the BRE-Luc and Runx2-Luc activities, which were inhibited by DN-AMPK or compound C. Down-regulation of Dlx5 expression by siRNA suppressed metformin-induced Runx2 expression. These results suggest that the activation of AMPK stimulates osteoblast differentiation via the regulation of Smad1/5/8-Dlx5-Runx2 signaling pathway.

COMP-Ang1, a variant of angiopoietin 1, inhibits serum-deprived apoptosis of mesenchymal cells via PI3K/Akt and mitogen-activated protein kinase pathways.

BACKGROUND/AIMS: Cartilage oligomeric matrix protein (COMP)-angiopoietin 1 (Ang1) is a soluble and stable form of Ang1 which plays important roles in vessel formation and the survival of endothelial cells, neurons and cardiomyocytes. However, the effects of COMP-Ang1 on the survival of mesenchymal cells are unknown. Mesenchymal cells have been transplanted with some scaffolds for bone tissue regeneration, but they occasionally underwent cell death due to a lack of nutrient supply. This study examined the effects of COMP-Ang1 on the survival of mesenchymal cells under nutrient-deprived conditions. METHODS: Primary and C3H10T1/2 mesenchymal cells were cultured under serum deprivation with or without COMP-Ang1. The effects of COMP-Ang1 on mesenchymal cell survival and its molecular mechanism were determined using a viability test, RT-PCR, Western blotting and fluorescence-activated cell sorting analysis. RESULTS AND CONCLUSION: COMP-Ang1 inhibited the nutrient-deprived apoptotic cell death of mesenchymal cells through the Akt, p38 and extracellular-signal-regulated kinase (ERK) pathways. In addition, COMP-Ang1 reversed the nutrient-deprived suppression of cyclin D1 mRNA expression. These results suggest that COMP-Ang1 has a protective role in the survival of nutrient-deprived mesenchymal cells. The use of COMP-Ang1 with some scaffolds might be useful for bone tissue engineering.

COMP-Ang1, a chimeric form of Angiopoietin 1, enhances BMP2-induced osteoblast differentiation and bone formation.

INTRODUCTION: Angiogenesis is closely associated with bone formation, especially endochondral ossification. Angiopoietin 1 (Ang1) is a specific growth factor functioning to generate a stable and matured vasculature through the Tie2 receptor/PI3K/AKT pathway. Recently cartilage oligomeric matrix protein (COMP)-Ang1, an Ang1 variant which is more potent than native Ang1 in phosphorylating Tie2 receptor and AKT, was developed. This study was designed to examine the effects of angiogenic COMP-Ang1 on BMP2-induced osteoblast differentiation and bone formation. METHODS: Expression of endogenous Ang-1 and its binding receptor Tie 2 mRNA was examined in osteoblast-like cells and primary mouse calvarial cells by RT-PCR analysis, and was also monitored during osteoblast differentiation induced by BMP-2 and/or ascorbic acid and beta-glycerophosphate. Effects of COMP-Ang-1 on osteoblast differentiation and mineralization were evaluated by alkaline phosphatase (ALP) activity and osteocalcin (OC) production, and Alizarin red stain. For a molecular mechanism, Western blot and OG2 and 6xOSE promoter assays were done. For in vivo evaluation, adenoviral (Ad) vectors containing COMP-Ang-1 or BMP-2 gene were administered into thigh muscle of mice, and after 2 weeks bone formation was analyzed by micro-computed tomography and histology. Angiogenic event of COMP-Ang1 was confirmed by immunofluorescence analysis with anti-CD31 antibody. RESULTS: Expression of Tie2 receptor was significantly increased in the course of osteoblast differentiation. Treatment or overexpression of COMP-Ang1 enhanced BMP2-induced ALP activity, OC production, and mineral deposition in a dose-dependent manner. In addition, COMP-Ang1 synergistically increased OG2 and 6xOSE promoter activities of BMP2, and sustained p38, Smad and AKT phosphorylation of BMP2. Notably, in vivo intramuscular injection of COMP-Ang1 dose-dependently enhanced BMP2-induced ectopic bone formation with increases in CD31 reactivity. CONCLUSIONS: These results suggest that COMP-Ang1 synergistically enhanced osteoblast differentiation and bone formation through potentiating BMP2 signaling pathways and angiogenesis. Combination of BMP2 and COMP-Ang1 should be clinically useful for therapeutic application to fracture and destructive bone diseases.