[Effects of tensile strain on the expression of Runx2/Cbfalpha1 in osteoblasts cultivated with inflammatory stimulus].

OBJECTIVE: To determine the effects of tensile strain on the expression of core binding factor alpha1 (Runx2/Cbfalpha1) in osteoblasts cultivated in Pg-LPS stimulated RAW264.7 culture supernatant. METHODS: Osteoblasts MC3T3-E1 were cultivated in LPS stimulated monocyte culture supernatant for 24 h. Then, a four-point bending device was used to perform a single period of tensile strain (1000 microm strain, 3000 microm strain respectively) on osteoblasts for 0 h, 0.5 h, 1 h, 2 h, 3 h, 6 h. Non-inflammatory stimuli were set up as control. The expression of Runxr2/Cbfalpha1 mRNA in MC3T3-E1 cells was examined by real-time RT-PCR. RESULTS: With the mechanical loading, the expression of Runx2/Cbfalpha1 mRNA increased in both inflammatory and non-inflammatory groups of osteoblasts and reached the peak after 6 h. The inflammatory group had lower expression of Runx2/Cbfalpha1 mRNA than that of the non-inflammatory group (P<0.05). The varied strain level did not change the expression of Runx2/Cbfalpha1 mRNA within 3 hours. But after 6 hours, the 3000 microm strain induced higher expression of Runx2/Cbfalpha1 mRNA than the 1000 microm strain. CONCLUSION: Inflammation inhibits the tensile strain induced expression of Runx2/Cbfalpha1 in osteoblasts. Precaution needs to be paid to orthodontic treatment on patients with quiescent periodontitis.

[Cone-beam CT evaluation of volume and surface area changes of impacted upper central incisors before and after orthodontic treatment].

PURPOSE: The purpose of this study was to quantitatively evaluate root resorption by cone-beam computer tomography (CBCT) after orthodontic treatment of impacted upper central incisors. METHODS: Ten patients (12 impacted incisors and 8 contralateral corresponding teeth) were included in this study. With self-designed modified nance arch and straight wire arch, the impacted incisors were treated by combined orthodontics and surgery approach. CBCT images of all patients were taken before and immediately after the treatment. Mimics software was used to build three-dimensional images. The upper central incisors were isolated. Volumes of teeth and superficial area were calculated. The difference between pre- and post- treatment was statistically evaluated with paired samples t test using SPSS13.0 software package. RESULTS: Significant difference in volume and superficial area was found between pre- and post- treatment (P<0.05). The average whole dental volume increase was (9.67±10.86) mm3, and the superficial area increase was (28.97±14.36)mm2. Statistical significance was achieved among 12 impacted incisors. The average whole dental volume increase of the control group was（12.38±10.22）mm3, and the superficial area increase was（30.64±16.74）mm2. There was no significant difference between the impacted and the control group in dental volume and superficial area before and after treatment (P>0.05). CONCLUSIONS: The treatment by combined orthodontics and surgery approach could promote tooth development for impacted incisors without causing root absorption, which can be safely performed.

Baicalein enhances the osteogenic differentiation of human periodontal ligament cells by activating the Wnt/ß-catenin signaling pathway.

OBJECTIVE: Periodontium regeneration is one of the most important processes for periodontitis therapy. Human periodontal ligament cells (hPDLCs) play a vital role in the repair and regeneration of periodontal tissues. Our study aimed to investigated the mechanisms underlying the promotion of hPLDCs osteogenic differentiation by baicalein. DESIGN: hPDLCs were obtained from periodontal ligament (PDL) tissues by primary culture. The MTT assay was used to determine the growth curves of hPDLCs treated with different concentrations of baicalein (1.25, 2.5, 5, or 10µM). Alkaline phosphatase (ALP) staining and Alizarin red S staining were performed to assess osteogenic differentiation of hPDLCs administered baicalein. Osteogenic differentiation-related gene and protein expression levels and Wnt/ß-catenin pathway signal changes were assessed by qRT-PCR and Western blotting analysis. RESULTS: The results showed that baicalein decreased the growth of hPDLCs slightly and increased ALP activity and calcium deposition in a dose-dependent manner. The expression of runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2), Osterix (OSX) and osteocalcin (OCN) were elevated after baicalein administration. Moreover, baicalein strongly activated the Wnt/ß-catenin pathway and up-regulated the expression of ß-catenin, lymphoid enhancer factor 1 (LEF1) and Cyclin D1. Dickkopf-related protein 1 (DKK-1) significantly reversed the effects of baicalein on hPDLCs. CONCLUSIONS: Our findings indicated that baicalein enhanced the osteogenic differentiation of hPDLCs via the activation of the Wnt/ß-catenin signaling pathway, which may represent a potential candidate for periodontitis therapy.

[Periodontal status of labially inversely impacted maxillary central incisor in mixed dentition after orthodontic treatment].

PURPOSE: To study the periodontal status of labially inversely impacted maxillary central incisor in mixed dentition after orthodontic treatment. METHODS: Sixteen patients with labially inversely impacted maxillary central incisor in mixed dentition and treated by guided rod appliance and conventional fixed appliance were enrolled in this study. Periodontal examinations were performed and cone-beam CT (CBCT) was taken approximately 2 years post treatment. Central incisors were divided into impacted and contralateral incisor groups. Clinical examinations included plaque index (PLI), gingival index (GI), probing depth (PD), width of attached gingiva (AW) and clinical crown length (CL); Mimics 16.0 software was used to measure the length of alveolar bone around the root (ha and fc), the length from the alveolar bone crest to cemento-enamel junction(CEJ) (ab and cd) on both the labial and palatal side of the central incisors as well as the labial and palatal bone support proportion (LBP and PBP) of the root and tipping of central incisor (U1-SN). The data were analyzed using paired sample t tests with SPSS 17.0 software package. RESULTS: There was no significant difference in PLI, GI, PD, U1-SN; the value of AW, ha,fc, LBP, PBP was significantly smaller in impacted groups(P<0.01); the value of CL, ab and cd was significantly larger in impacted groups (P<0.01). CONCLUSIONS: The periodontal status of the impacted central incisor was on good condition without teeth mobility and inflammation, although a little worse than the contralateral homonymous teeth. There may be a need for periodontal bone grafting and gingival surgery in the future for the asymmetric morphology of gingiva.

Endogenous hydrogen sulfide is involved in osteogenic differentiation in human periodontal ligament cells.

OBJECTIVE: Endogenous hydrogen sulfide (H2S) has recently emerged as an important intracellular gaseous signaling molecule within cellular systems. Endogenous H2S is synthesized from l-cysteine via cystathionine ß-synthase and cystathionine γ-lyase and it regulates multiple signaling pathways in mammalian cells. Indeed, aberrant H2S levels have been linked to defects in bone formation in experimental mice. The aim of this study was to examine the potential production mechanism and function of endogenous H2S within primary human periodontal ligament cells (PDLCs). DESIGN: Primary human PDLCs were obtained from donor molars with volunteer permission. Immunofluorescent labeling determined expression of the H2S synthetase enzymes. These enzymes were inhibited with D,L-propargylglycine or hydroxylamine to examine the effects of H2S signaling upon the osteogenic differentiation of PDLCs. Gene and protein expression levels of osteogenic markers in conjunction with ALP staining and activity and alizarin red S staining of calcium deposition were used to assay the progression of osteogenesis under different treatment conditions. Cultures were exposed to Wnt3a treatment to assess downstream signaling mechanisms. RESULTS: In this study, we show that H2S is produced by human PDLCs via the cystathionine ß-synthase/cystathionine γ-lyase pathway to promote their osteogenic differentiation. These levels must be carefully maintained as excessive or deficient H2S levels temper the observed osteogenic effect by inhibiting Wnt/ß-catenin signaling. CONCLUSIONS: These results demonstrate that optimal concentrations of endogenous H2S must be maintained within PDLCs to promote osteogenic differentiation by activating the Wnt/ß-catenin signaling cascade.

[The effect of modified Nance arch on treating maxillary impacted canine transposed with first premolar].

PURPOSE: To explore the effect of modified Nance arch on treating maxillary canine-first premolar transposition cases, in which the anchorage and force direction were discussed. METHODS: Modified Nance arch was applied to 5 cases with maxillary impacted canine-first premolar transposition. First, a lingual knot button was bonded on the surface of the canine crown. Modified Nance arch was decorated with a hook that moved horizontally and buccally. Then the location of the hook was gradually adjusted in order to move the canine cross the root of the first premolar and move the canine to the right position. At last the canine was moved downward by straight wire appliance. RESULTS: Five maxillary transposed canines were fully erupted in their right position, with normal pulp activity and gingival morphology. No obvious root resorption was detected. The mean treatment time was 30 months. CONCLUSIONS: Modified Nance arch has advantages in treating canine-first premolar transposition.

[Effects of LPS-stimulated monocyte culture supernatant on the OPG/RANKL of osteoblastic cells].

PURPOSE: To investigate the influence of Pg-LPS stimulated monocyte (RAW264.7) culture supernatant on the OPG/RANKL expression of osteoblastic cells (MC3T3-E1). METHODS: The culture supernatant of monocytes stimulated with Pg-LPS was applied to osteoblasts MC3T3-E1 with different diluted concentrations (10%, 20%, 30%, 40% and 50%) simultaneously for 24h, then RT-PCR was used to detect the expression changes of OPG/RANKL mRNA. Western blot was used to detect the expression changes of OPG/RANKL protein. The data was analyzed by ANOVA using SPSS 17.0 software package. RESULTS: After stimulation of different concentrations of inflammatory supernatant, the expressions of OPGmRNA and protein significantly decreased (P<0.05), whereas the expressions of RANKLmRNA and protein significantly increased(P<0.05), both of them were in a concentration-dependent manner. CONCLUSIONS: These results indicate that Pg-LPS stimulated RAW264.7 culture supernatant can inhibit the osteogenesis and differentiation of the osteoblasts through inhibiting the expression of OPGmRNA and protein of osteoblastic cells, while increasing the expression of RANKLmRNA and protein in a concentration-dependent manner.

[Effect of tensile strain on perlecan expression of human periodontal ligament cells].

PURPOSE: To investigate the perlecan expression of human periodontal ligament cells (hPDLCs) under cyclic tensile strain in vitro, and learn the molecular mechanism of periodontal remolding during tooth movement. METHODS: hPDLCs isolated by enzyme digestion were loaded with 12% elongation, 1 Hz of uniaxial tensile strain for 12, 24 and 48 h. The unloaded cells were used as control. Real-time PCR and enzyme-linked immune sorbent assay (ELISA) were applied to analyze the mRNA and protein expression of perlecen in each sample respectively. The data was analyzed with SPSS 19.0 software package. RESULTS: Within 12 h, mRNA expression was transiently elevated, but no significant difference was detected compared with the control. After 12 h, the mRNA expression was significantly decreased. It would decreased to (0.28±0.049) at lowest level of control at lowest level at 48 h (P<0.05). The protein expression of perlecan was time-dependently decreased. Specifically, it was downregulated from (14.03±0.71) pg/mL (control) to (11.06±0.15) pg/mL at lowest level at 48 h (P<0.05). CONCLUSIONS: Tensile strain time-dependently down-regulates perlecan expression, indicating perlecan may play a pivot role in PDLCS responding to mechanical loading in vitro.

[Imaging classification of maxillary impacted central incisors].

PURPOSE: To investigate the classification of maxillary impacted central incisors through three-dimensional images. METHODS: Based on the original Dicom data of the spiral computed tomography of 103 patients with maxillary impacted central incisors, the three-dimensional images of maxillary impacted central incisors were reconstructed by Mimics 10.0 software, and the characteristics were analyzed and a classification was proposed. RESULTS: There were 106 teeth included in this study, 74 teeth were located labially, including 33 inverted impacted teeth, 28 horizontally impacted teeth, and 13 inclined teeth. 20 teeth were located in the palatal side, including 11 inclined teeth and 9 horizontally impacted teeth. 12 teeth were within the bone, which can be divided into three categories based on the position of the crown and in accordance with the vertical, far to near, and horizontal direction. Type I was labially impacted incisor, including 3 subdivisions: labially inclined impacted, labially horizontal impacted and labially inverted impacted. Type II was palatally impacted incisor, including 2 subdivisions: palatally inclined impacted and palatally horizontal impacted. Type III was vertically impacted incisor. CONCLUSIONS: The maxillary impacted incisors can be divided into 3 categories based on three-dimensional directions, and subdivisions can be created in each group including labially (inclined, horizontal, inverted) impacted incisors, palatally (inclined, horizontal) impacted incisor and vertically impacted incisors.

[The effect of orthodontic treatment on facial profile of patients with Class II division 1 malocclusions].

PURPOSE: The purpose of this study was to determine the effect of orthodontic treatment on facial esthetic changes of Class II division 1 malocclusions through visual analogue scale(VAS) scores before and after treatment. METHODS: Reference photographs were selected first. 40 males and 40 females were randomly selected from the patients treated in our hospital. A set of photographs of each patient were shown to a panel .Then each face profile was rated on a VAS. Means and standard deviations (SD) were calculated for each set of photographs. One male and one female's photographs with an average aesthetic score close to the median value and lower SD were then selected to serve as reference photographs. Forty Class II division 1 malocclusion patients were randomly selected. A set of standardized photographs together with a set of reference photographs of the same gender were placed in random order to show to the panel.Facial aesthetics of the experimental subjects were scored on a VAS. Then the VAS scores both pretreatment and posttreatment were compared and analyzed using SPSS11.0 software package by one sample t test and paired t test. RESULTS: Two sets of reference photographs of one male and one female were selected. The mean of the patients prior to treatment was 43.839, and 48.328 after treatment. When the population mean was supposed to be 50,significant difference was noted prior to treatment with one sample t Test(P<0.05),while no significant difference was found after treatment(P>0.05). Paired t test showed that post-treatment scores were significantly higher than pre-treatment(P<0.01). CONCLUSION: The facial esthetic of Class II division 1 malocclusions were worse than the average, but can be improved through orthodontic treatment to approach an level.

[A comparative study of split-root and medial resistance removal in extraction of medially impacted tooth].

PURPOSE: To compare the operating time, root fracture and postoperative complications between split-root extraction and medial resistance removal in extraction of mandibular small-angle impacted third molars, to evaluate the advantages of split-root extraction in medially impacted tooth extraction. METHODS: Forty male patients with bilaterally mandibular medial small-angle impacted third molars, having multiple roots in panoramic films, were selected. The impacted teeth on one side were extracted by using split-root method, while the similar impacted teeth on the other side were extracted by using medial resistance removal method. The operating time, root fracture, postoperative pain, facial edema, and mouth opening were recorded. SPSS11.5 software package was used and paired t test was performed to analyze the data. RESULTS: There were significant differences in operating time and root fracture between the two methods (P<0.05). In the split-root group, the operating time was shorter and root fracture were less. After 24 hours, facial edema, limited mouth opening, and pain of the split-root group was less severe than that of the medial resistance removal group, differences were significant(P<0.05). After 72 hours, limited mouth opening of the split-root group was milder than that of the resistance removal group, the difference was significant (P<0.05). After 120 hours, there was no significant difference of any complications between the two groups. CONCLUSIONS: In extraction of mandibular medial small-angle impacted third molars with multiple roots, the operating time of split-root extraction is shorter. The root fracture possibility of split-root extraction is smaller, and postoperative complications are less common.

[Root and alveolar bone status of maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment].

OBJECTIVE: To study the alveolar bone surrounding situation and the length of the root of the maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment. METHODS: Fourteen cases with maxillary labial inverted impacted incisor in mixed dentition were collected. Modified Nance arch and conventional appliance were used. Cone-bean CT (CBCT) was taken after the treatment. Simplant13.0 three-dimensional reconstruction and multi-planer reconstruction (MPR) method were used to observe the labial and lingual alveolar bone crest morphology, besides, the labial and lingual length from the alveolar bone crest to cemento-enamel junction (CEJ) of the impacted incisor and the homonym tooth after treatment, along with their root length and their labial and lingual length ratio of the root surrounded by the alveolar bone to the total root length were measured. The idependent samples t-test were used to analyze the variable differences. RESULTS: The labial and lingual alveolar bone of fourteen cases crest of the diseased tooth after treatment presented general symmetry U shape from qualitative observation through the three-dimensional reconstruction. The labial and the lingual length of the diseased incisor from alveolar bone crest to CEJ [(2.47 ± 1.35) and (1.47 ± 0.84) mm] was significant increased than those of the homonym incisor [(1.03 ± 0.35) and (0.90 ± 0.37) mm] (P < 0.05); the length of the diseased incisor's post-treatment root [(9.82 ± 2.82) mm] was no statistically significant decreased than that of the homonym incisor root [(10.28 ± 1.38) mm, P = 0.59]; the labial and the lingual length ratio of the impacted tooth's root surrounded by the alveolar bone to the total root length [(72.83 ± 17.16)% and (85.32 ± 5.98)%] was statistically significant decrease than those of homonym teeth[(89.66 ± 3.98)% and (90.84 ± 4.61)%] (P < 0.05). CONCLUSIONS: The diseased tooth's root had gotten enough length after the treatment. The labial and lingual alveolar bone of the maxillary labial inverted impacted incisor in mixed dentition can't offer sufficient adaptive hyperplasia after treatment, of which labial alveolar bone is more apparent, prompting careful protection when they were used.

[Study of the crestal bone height and root length technique change of impacted canines treated by modified Nance arch technique].

PURPOSE: The purpose of this study was to evaluate the crestal bone height and root length change after orthodontic treatment of impacted canines with modified Nance arch technique. METHODS: 8 maxillary impacted canines were treated with modified Nance arch technique. The canines of other side which were naturally erupted were used for self-control. Pre-treatment and post-treatment panoramic radiographs were measured and the following data was collected: (1)The distance of the impacted canine migration and the angle change of the impacted canine; (2)Crestal bone height and root length between previously impacted canines and adjacent lateral incisors and premolars(experimental)and contralateral control teeth. The crestal bone height and root length were compared using a paired t test with SPSS11.0 software package. RESULTS: The mean distance of the impacted canine migration was 18.43 mm and the mean angle change on the panoramic radiograph was 32.7 degrees. No difference was found in the crestal bone height and the root length between the adjacent lateral incisors and premolars(experimental) and the contralateral control teeth(P>0.05). CONCLUSION: The combination of modified Nance arch with straight wire arch technique is a valid method to treat maxillary impacted canines.

[Obstructive site of the upper airway in patients with obstructive sleep apnea hypopnea syndrome: analysis of dynamic MRI].

OBJECTIVE: To investigate the obstructive site and the dynamic change of the upper airway in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) during sleep and wakefulness. METHODS: After being deprived of sleeping for 20 hours, sequential midline sagittal images of the upper airway were obtained in 21 patients during sleep and wakefulness with dynamic MRI. The obstructive state was studied according to hypopnea (< 10 s) and apnea (> or = 10 s). The length of obstruction site was measured and the dynamic characteristics of obstruction was observed. Statistical analysis was performed with paired t-test. RESULTS: The obstruction at the level of the palatopharynx in patients with hypopnea during wakefulness was similar to that in patients with apnea during sleep. The maximal length [(6.61 +/- 1.23) cm], the minimal length [(0.95 +/- 0.22) cm] and maximal length difference [(5.66 +/- 1.27) cm] related to apnea during sleep were longer than those correlated with hypopnea [(2.99 +/- 0.51) cm, (0.72 +/- 0.23) cm, (2.27 +/- 0.67) cm, respectively] in wakefulness. (P < 0.01). CONCLUSIONS: The obstruction of upper airway during sleep is dynamic and multilevel in patients with OSAHS. To a certain degree, hypopnea during wakefulness can give a clue to the obstructive state during sleep.