Lysosome-targeted ruthenium(II) complex encapsulated with pluronic® F-127 induces oncosis in A549 cells.

Transition metal complexes with characteristics of unique packaging in nanoparticles and remarkable cancer cell cytotoxicity have emerged as potential alternatives to platinum-based antitumor drugs. Here we report the synthesis, characterization, and antitumor activities of three new Ruthenium complexes that introduce 5-fluorouracil-derived ligands. Notably, encapsulation of one such metal complex, Ru3, within pluronic® F-127 micelles (Ru3-M) significantly enhanced Ru3 cytotoxicity toward A549 cells by a factor of four. To determine the mechanisms underlying Ru3-M cytotoxicity, additional in vitro experiments were conducted that revealed A549 cell treatment with lysosome-targeting Ru3-M triggered oxidative stress, induced mitochondrial membrane potential depolarization, and drastically reduced intracellular ATP levels. Taken together, these results demonstrated that Ru3-M killed cells mainly via a non-apoptotic pathway known as oncosis, as evidenced by observed Ru3-M-induced cellular morphological changes including cytosolic flushing, cell swelling, and cytoplasmic vacuolation. In turn, these changes together caused cytoskeletal collapse and activation of porimin and calpain1 proteins with known oncotic functions that distinguished this oncotic process from other cell death processes. In summary, Ru3-M is a potential anticancer agent that kills A549 cells via a novel mechanism involving Ru(II) complex triggering of cell death via oncosis.

PD-L1 siRNA hitched polyethyleneimine-elastase constituting nanovesicle induces tumor immunogenicity and PD-L1 silencing for synergistic antitumor immunotherapy.

BACKGROUND: PD-1/PD-L1 blockade has become a powerful method to treat malignant tumors. However, a large proportion of patients still do not benefit from this treatment, due to low tumor immunogenicity and low tumor penetration of the agents. Recently, neutrophil elastase has been shown to induce robust tumor immunogenicity, while the insufficient enzyme activity at the tumor site restricted its anti-tumor application. Here, we designed polyethyleneimine-modified neutrophil elastase (PEI-elastase) loaded with PD-L1small interfering RNA (PD-L1 siRNA) for improving enzymatic activity and delivering siRNA to tumor, which was expected to solve the above-mentioned problems. RESULTS: We first demonstrated that PEI-elastase possessed high enzymatic activity, which was also identified as an excellent gene-delivery material. Then, we synthesized anti-tumor lipopolymer (P-E/S Lip) by encapsulating PEI-elastase and PD-L1siRNA with pH-responsive anionic liposomes. The P-E/S Lip could be rapidly cleaved in tumor acidic environment, leading to exposure of the PEI-elastase/PD-L1 siRNA. Consequently, PEI-elastase induced powerful tumor immunogenicity upon direct tumor killing with minimal toxicity to normal cells. In parallel, PEI-elastase delivered PD-L1siRNA into the tumor and reduced PD-L1 expression. Orthotopic tumor administration of P-E/S Lip not only attenuated primary tumor growth, but also produced systemic anti-tumor immune response to inhibit growth of distant tumors and metastasis. Moreover, intravenous administration of P-E/S Lip into mice bearing subcutaneous tumors leaded to an effective inhibition of established B16-F10 tumor and 4T1 tumor, with histological analyses indicating an absence of detectable toxicity. CONCLUSIONS: In our study, a protease-based nanoplatform was used to cooperatively provoke robust tumor immunogenicity and down-regulate PD-L1 expression, which exhibited great potential as a combination therapy for precisely treating solid tumors.

Detection and characterization of the accessory mental foramen using cone-beam computed tomography.

OBJECTIVE: This study aimed to investigate the frequency and characteristics of accessory mental foramina (AMFs) and their bony canals in a selected Chinese population using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Reconstructed CBCT images of the mandible in 784 Chinese patients (305 males and 479 females) were retrospectively analysed to identify the AMF. The presence, dimension and location of the AMF as well as the origin and course of the associated bony canal were evaluated and classified. Variations in these characteristics were analysed according to gender, side and age. RESULTS: A total of 66 AMFs were found in 57 (7.3%) of the 784 patients. The frequency of AMFs was significantly influenced by gender and side of the mandible (p < .05). Most AMFs were located apically between apices of the first and second premolars. The high-position AMFs (above the mental foramen) accounted for 54.5% of the total. The mean horizontal and vertical diameters of the AMF were 1.38 ± 0.47 and 1.23 ± 0.37 mm, respectively. Two typical types of the bony canal leading to the AMF were identified according to their bifurcation site from the mandibular canal. Most bony canals originated from the anterior loop of the mental canal (56.1%) and coursed posterosuperiorly (36.3%). The mean length of the bony canals was 5.78 ± 2.31 mm. CONCLUSIONS: This study presents a considerable frequency of AMFs in a Chinese population. The high-position AMF and the associated bony canal coursing in the oblique upward direction appear frequently. Thus, clinicians should be alert to the presence of the AMF to avoid neurovascular complications especially when dental procedures require periosteum detachment and implant insertion in the mental region.

Analysis of the Morphology of Maxillary Sinus Septa on Reconstructed Cone-Beam Computed Tomography Images.

PURPOSE: Preoperative assessment of maxillary sinus anatomy can prevent complications associated with sinus grafting or implant procedures. The purpose of this study was to measure the frequency, numbers, locations, orientations, and heights of maxillary sinus septa. MATERIALS AND METHODS: Reconstructed cone-beam computed tomographic images of 1,012 sinuses were analyzed using NewTom VG software (NNT 2.21, ImageWorks, Elmsford, NY). This cross-sectional study included patients who underwent radiography at the department of radiology. The presence, numbers, locations, orientations, and heights of septa were analyzed. To establish multiple predictors in this study, groups were defined according to different radiographic features of the septa. Differences between male and female groups and between edentulous and dentulous groups were tested with χ(2) tests and the level of significance was set at 5%. RESULTS: The sample consisted of 506 patients (168 men and 338 women; average age, 35.1 yr). A significantly (P < .05) greater occurrence rate of 57.4% was observed in the edentulous group compared with the rate of 39.7% observed in the dentulous group. CONCLUSIONS: The difference in the prevalence of maxillary sinus septa between the edentulous and dentulous groups was statistically significant (P < .05), and the septa exhibited variable characteristics. It is essential and effective to analyze computed tomographic images of sinuses to evaluate the characteristics of septa before performing surgical procedures.

Exploring sustainable food packaging: Nanocellulose composite films with enhanced mechanical strength, antibacterial performance, and biodegradability.

Food packaging films play a vital role in preserving and protecting food. However, due to their non-biodegradability, conventional packaging materials have led to significant environmental pollution. To overcome this hurdle, we have developed safe, innovative, sustainable and biodegradable packaging materials that can effectively extend the shelf life of food. In this study, two types of cellulose materials cellulose nanofibers (CNF) and carboxymethyl cellulose (CMC) with complementary roles were combined to prepare nanocellulose composite films with high transparency (90.3 %) of a certain thickness (30 ± 0.019 µm) by solution casting method, and their mechanical properties were further optimized by the addition of plasticizer-glycerol (Gly) and cross-linking agent-glutaraldehyde (GA), so as to maintain the strong tensile strength (≈112.60 MPa) and better malleability (4.12 %). In addition, we loaded the natural active agent tea polyphenols (TPs) with different concentrations to study the inhibition effect on E.coli and S.aureus and to simulate food packaging. Finally, we also found that the synthesized nanocellulose composite films can also achieve rapid degradation in a short time through soil burial, water flushing and immersion. The excellent performance demonstrated in this study provides reference value for further replacing petroleum-based materials with biomass materials in the field of food packaging.

Superhydrophobic Cellulose Nanofiber Aerogels for Efficient Hemostasis with Minimal Blood Loss.

Reducing unnecessary blood loss in hemostasis is a major challenge for traditional hemostatic materials due to uncontrolled blood absorption. Tuning the hydrophilic and hydrophobic properties of hemostatic materials provides a road to reduce blood loss. Here, we developed a superhydrophobic aerogel that enabled remarkably reduced blood loss. The aerogel was fabricated with polydopamine-coated and fluoroalkyl chain-modified bacterial cellulose via a directional freeze-drying method. Primarily, the hydrophobic feature prevented blood from uncontrolled absorption by the material and overflowing laterally. Additionally, the aerogel had a dense network of channels that allowed it to absorb water from blood due to the capillary effect, and fluoroalkyl chains trapped the blood cells entering the channels to form a compact barrier via hydrophobic interaction at the bottom of the aerogel, causing quick fibrin generation and blood coagulation. The animal experiments reveal that the aerogel reduced the hemostatic time by 68% and blood loss by 87 wt % compared with QuikClot combat gauze. The study demonstrates the superiority of superhydrophobic aerogels for hemostasis and provides new insights into the development of hemostatic materials.

[Accuracy evaluation of static guided implant placement using an intraoral scan method].

PURPOSE: To evaluate the accuracy of static guided implant placement with intraoral scanning technology and to analyze the influencing factors of guided surgery. METHODS: Totally 27 cases were included in this retrospective study. The implant designs were made in 3Shape Implant Studio and then guided implant surgeries were performed with CAD-CAM templates. Postoperative implant positions were detected with an intraoral scanner (3Shape TRIOS) and deviation of implantation was evaluated using established CAD/CAM based evaluation method. SAS 9.4 software package was used for data analysis. RESULTS: The mean deviation of entrance point and apical point was (1.182±0.609) mm and (1.658±0.741) mm, respectively. Angular deviation was (5.712±3.347)°. Implant quadrant, location of the implant site, guidance degree, supporting type and implant size influenced direction deviation, while angular deviation was mainly affected by guidance degree and number of missing teeth. CONCLUSIONS: Accuracy of static guided implant placement can be influenced by many factors. More research is needed to improve the accuracy of static guided implantation.

[Study on cushioning and energy absorption of sports mouthguard].

PURPOSE: Using impact test to study cushioning and energy absorption of sports mouthguard of different thickness, material and combination. METHODS: According to the thickness, material and combination, the mouthguards were divided into 7 groups with 6 testing pieces in each group. A pendulum device was used to apply impact energy to the mouthguard and dentition model, and the magnitude of the impact energy was measured by changing the release height of the pendulum. The force sensor and the laser vibrometer were respectively connected to the data acquisition and signal analyzer to obtain the incident speed, rebound speed, maximum collision force, collision start time and collision end time of the hammer head. Collision time, energy absorption and energy absorption ratio of the mouthguard were calculated, which reflected different mouthguard cushioning and energy absorption characteristics. One-way analysis of variance and t test in SPSS 22.0 software package was used to analyze the difference between different groups. RESULTS: No matter what type of mouthguard was worn by the dentition model, the impact force was significantly reduced than without mouthguards. At the same height, there was significant difference between the average maximum collision force and the average collision time among soft mouthguards with thicknesses of 2, 3, 4, and 5 mm(P<0.05); among which the average maximum collision force of the 5 mm was the smallest and the average collision time was the shortest. There was no significant difference in the average energy absorption and the average energy absorption ratio among these 4 groups. There was significant difference in the average maximum collision force, average collision time, average energy absorption and average energy absorption ratio between the two groups of mouthguards with the same thickness of splints and different materials(P<0.05). Among them, the average maximum impact force of the 4 mm soft mouthguard was smaller and the average collision time was longer. CONCLUSIONS: Wearing sports mouthguard can reduce the risk of tooth fracture during collision. Soft mouthguard has the best cushioning performance and it is positively related to thickness. Locally strengthening hard materials can enhance energy absorption and provide better protection.

[Experimental study of laparoscopical lumbar interbody fusion with polyporus composite phosphate calcium and rhBMP-2 compounds in sheep].

OBJECTIVE: To study the efficacy of polyporus composite phosphate calcium and rhBMP-2 compounds with laparoscopical lumbar interbody fusion in sheep. METHODS: Fourteen uniform-weight adult sheep were randomly divided into three groups for LA-5 interbody fusion with titanium mesh. Autogenous bone and titanium mesh was applied with open anterior technique in group 1 (n=4). In group 2, 4 sheep were operated with laparoscope technique for LA-5 interbody fusion with composite phosphate calcium (CPC) and titanium mesh. In group 3, 6 sheep underwent laparoscopical L4-5 interbody fusion with titanium mesh as well as polyporus composite phosphate calcium and rhBMP-2 compounds. At Weeks 6 and 12 post-operation, the sheep were sacrificed for imaging, biomechanic and morphological examinations. RESULTS: Although there was no statistical difference between open and laparoscopical interbody fusion group when comparing the remaining disc and endplate decorticated, bone fusion occurred in 3 groups after 3 months. A much larger amount of bony callus was observed earlier in laparoscopical L4-5 interbody fusion group with titanium mesh as well as polyporus composite phosphate calcium and rhBMP-2 compounds than two other groups. CONCLUSION: Polyporus composite phosphate calcium and rhBMP-2 compounds are suitable prosthetic materials for clinical trials. When these materials are utilized with a laparoscopical technique, satisfactory interbody fusion may be achieved.

[Study of the timing of tooth movement after repair of alveolar bone defects by rabbit BMSCs combined with beta-TCP].

PURPOSE: To investigate the effect of tooth movement at different time after repair of alveolar bone defects with tissue engineering bone constructed by rabbit bone marrow mesenchymal stem cells (BMSCs) and beta-tricalcium phosphate (ß-TCP). METHODS: Alveolar bone defect (6 mm×4 mm×8 mm) was made on the right side of 40 New Zealand rabbits, which was filled with tissue engineering bone constructed by BMSCs and ß-TCP as experimental sides. Tooth extraction on the other side was performed as control. The mandibular second molars in both sides were moved mesially 2, 4, 8 and 12 weeks after surgery. The specimens were taken 4 weeks after exertion. The distance of mandibular second molar moved was measured. The periodontal tissues were observed after H-E staining. TRAP staining was performed and osteoclasts were counted in the periodontal tissues on the pressure side. BMP-2 immunohistochemical staining was used to observe the average optical density of periodontal tissue on tension side. The results were analyzed with SAS 8.0 software package. RESULTS: The distance of tooth movement, the amount of TRAP positive cells and the optical density of BMP-2 in the experimental side of the 2-week and 4-week groups were all significantly lower than those in the control side, while there was no significant difference between the 8-week and 12-week groups. CONCLUSIONS: Eight weeks after repair of alveolar bone defect with rabbit BMSCs and ß-TCP is an appropriate time for orthodontic tooth movement.

[Study on periodontal responses on the compression side during early tooth movement into alveolar defect regenerated by a tissue engineering bone].

PURPOSE: To explore periodontal responses on the compression side during early tooth movement into alveolar defect regenerated by bone marrow mesenchymal stem cells (BMSCs) and porous granulated beta-tricalcium phosphate（ß-TCP） scaffolds. METHODS: Thirty New Zealand rabbits were used to establish bilateral mandibular defective alveolar bone model by extracting the mandibular first molars and expanding the sockets. The right mandibular alveolar defects were filled with a construct of ß-TCP scaffolds combined with BMSCs as experimental group. The left alveolar defects were repaired by ß-TCP scaffolds alone as control group. Eight weeks later, 6 rabbits were sacrificed to evaluate osteogenesis effect. The other rabbits were loaded orthodontic force to move the bilateral second molars forward for 4 weeks. Six rabbits in each group were sacrificed at 1, 2, 3, and 4 week after orthodontic tooth movement (OTM). The distance of OTM was measured, and the status of periodontal tissues was observed by H-E staining. The number of osteoclasts on the compression side of tooth was counted by tartrate-resistant acid phosphatase histochemistry. The results were compared between groups using SPSS 19.0 software package. RESULTS: After 8 weeks of bone grafting, the osteogenesis effect of the experimental group was better than the control group. The OTM distance in the experimental area was higher than that in the control area. At 2, 3 and 4 week of OTM, the number of osteoclasts in the experimental group was significantly higher than that in the control group. CONCLUSIONS: A tissue-engineered complex with ß-TCP scaffolds and BMSCs could well repair the alveolar bone defect. When the adjacent tooth moved into regenerated area, the new periodontal tissue had an active response, promoting to accelerate tooth movement.

Characteristics of intrabony nerve canals in mandibular interforaminal region by using cone-beam computed tomography and a recommendation of safe zone for implant and bone harvesting.

BACKGROUND: Cone-beam computed tomography can accurately show anatomic structure of intrabony nerve canals in mandibular interforaminal region. PURPOSE: The aim was to evaluate the characteristics of intrabony nerve canals in mandibular interforaminal region by using cone-beam computed tomography (CBCT) and determine a safe zone for implant and bone harvesting. MATERIALS AND METHODS: Hemimandibles (824) CBCT images were obtained. The length of the anterior loop (AL), the length and diameter of the mandibular incisive canal (MIC) and its spatial distance in various landmarks were measured. RESULTS: The prevalence of the AL was 93.57%, and the MIC was 97.33%. The mean lengths of the anterior extension of the anterior loop (aAL), caudal extension of the anterior loop (cAL) and the MIC were 2.53 ± 1.27 mm, 6.04 ± 1.66 mm, 9.97 ± 5.15 mm, respectively. The MIC was closer to buccal border and inferior margin of mandible. The length of the AL and diameter of the MIC varied with gender. CONCLUSIONS: The safe zone recommended for implant surgery is 4 mm anterior and 8 mm inferior to the mental foramen, and 10 mm above the inferior margin of mandible. The chin bone should be harvested at least 10 mm below the tooth apices along with a limited depth of 4 mm.

An Analysis of the Proximity of Maxillary Posterior Teeth to the Maxillary Sinus Using Cone-beam Computed Tomography.

INTRODUCTION: It is known that the level of the maxillary sinus floor varies with age. Because few studies have investigated whether the position of the posterior roots relative to the maxillary sinus varied with the variation of the sinus floor or not, the present study assessed the position according to age. METHODS: Cone-beam computed tomographic images of 848 patients were reconstructed to evaluate the position of the posterior roots relative to the sinus floor, which were divided into 3 types, and quantify the distances between posterior root apexes and the adjacent border of the sinus floor. Measurements were taken for each root, and data were correlated with age, which was divided into 4 groups (≤20 years, 21-40 years, 41-60 years, and >60 years). RESULTS: A total of 3063 premolars and 3095 molars were evaluated. The mean distances from the root tips to the border of the maxillary sinus floor increased with increasing age. From the first and second premolar roots, the mean distances ranged from 3.6 ± 4.1 mm to 8.9 ± 4.6 mm and from 0.7 ± 3.3 mm to 5.3 ± 3.9 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the first molars, the mean distances were -0.4 ± 2.8 mm to 4.6 ± 4.0 mm, -0.3 ± 2.4 mm to 4.4 ± 3.8 mm, and -0.4 ± 3.5 mm to 3.9 ± 4.1 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the second molars, the mean distances were -0.5 ± 2.2 mm to 3.4 ± 3.5 mm, 0.3 ± 2.2 mm to 3.9 ± 3.7 mm, and 1.1 ± 3.2 mm to 4.6 ± 4.5 mm, respectively. The frequency of type IS decreased with increasing age. It was very low in first premolars (0%-8.13%) and higher in second premolars (0%-25.68%), first molars (0%-44.75%), and second molars (0%-32.89%). Age significantly influenced the mean distances to the sinus floor and the frequencies of type IS (inside). CONCLUSIONS: Cone-beam computed tomographic imaging is an effective method to study the position of the posterior roots to the maxillary sinus floor. Variation in proximity measurements was found by age, with those under the age of 40 showing a greater likelihood of the position of maxillary roots above/inside the sinus floor.

Analysis of the Root and Canal Morphologies in Maxillary First and Second Molars in a Chinese Population Using Cone-beam Computed Tomography.

INTRODUCTION: We analyzed and characterized the root and canal morphologies in maxillary first and second molars in a large sample of Chinese patients using reconstructed cone-beam computed tomographic (CBCT) imaging. METHODS: Maxillary first (n = 1558) and second (n = 1539) molars were collected from Chinese patients (N = 844) who had undergone in vivo CBCT imaging. The root canal number and morphology were determined according to Vertucci's classification. RESULTS: A single root was found in 0.06% of first molars, which showed type I canal systems. However, second molars with a single root (4.2%) showed widely varied canal systems. The buccal roots of first molars with 2 separate roots showed type I, II, or III canal systems, whereas those of 2-rooted second molars showed widely varied canal systems. The incidence of fused roots was 1.38% for first molars and 23.9% for second molars, whereas canal fusion within fused roots was observed in 4.5% of first molars and 10.6% of second molars. Additional canals were observed in 67.8% and 29.7% of mesiobuccal roots, 1.8% and 0.7% of distobuccal roots, and 0.7% and 0.3% of palatal roots in 1523 and 1017 first and second molars with 3 separate roots, respectively. The mesiobuccal root canal number showed bilateral symmetry between 79% of first molars and 82.3% of second molars, with a concurrence rate of 59.8% between adjacent molars. CONCLUSIONS: We reported the root and canal morphologic variations in maxillary first and second molars, which have not been reported for Chinese populations. Further studies should focus on canals in fused roots and mesiobuccal roots.

[Soft tissue angle evaluation of fixed Twin-Block appliance treatment and tooth extraction treatment in skeletal Class II malocclusion].

PURPOSE: This cephalometric study was designed to evaluate the soft tissue profile effects of Twin-Block combined with straight wire appliances in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals by angulation. METHODS: The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, which were divided into 2 groups. One group (18 patients) was treated with fixed Twin-Block combined with fixed appliance， the other group (13 patients) was only treated with fixed appliance after tooth extraction. Pretreatment and posttreatment lateral cephalograms were taken before and after Twin-Block treatment and after all the fixed appliance treatment. Angular cephalometric measurements of soft tissue were analyzed statistically. Intragroup and intergroup changes of the 2 groups were evaluated by Student's t test using SPSS 15.0 software package. RESULTS: Significant difference of FH-N'Pg', G-Pn-Pg', LiSi-SN and SnLs-SiLi were discovered in both groups (P<0.05). With Twin-Block combined with fixed appliance, N'-Sn-Pg', Sn-N'-Si and Si-N'-S changed significantly, while LsSn-SN and Z angle differed significantly before and after treatment with extraction and fixed appliance. After treatment of Twin-Block combined with fixed appliance, Sn-N'-Si decreased significantly, and the difference between the change of the 2 groups was significant. Meanwhile LsSn-SN was stable in combined treatment group while it decreased greatly after extraction. CONCLUSIONS: Compared with extraction with fixed appliance treatment, Twin-Block combined with fixed appliance treatment is more favorable in promoting lower facial profile in growing skeletal Class II individuals with mandibular retrognathia.

[Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

PURPOSE: To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. METHODS: Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. RESULTS: Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. CONCLUSIONS: According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

[Soft tissue linear evaluation of fixed Twin-block appliance treatment and tooth extraction in skeletal Class II malocclusion].

PURPOSE: This cephalometric study was designed to evaluate the soft tissue profile effects of Twin-block combined with straight wire appliances to treat growing adolescents with skeletal Class II malocclusion and mandibular retrognathia. METHODS: The samples comprised 31 growing individuals with skeletal Class II and mandibular retrognathia. They were divided into 2 groups. The study group (18 patients) was treated with fixed Twin-block combined with fixed appliance, while the control group (13 patients) was only treated with fixed appliance after tooth extraction. Pretreatment and posttreatment lateral cephalograms were taken before and after Twin-block treatment and after all the fixed appliance treatment. Linear cephalometric measurements of soft tissue were analyzed statistically. Intragroup and intergroup changes of the 2 groups were evaluated using SPSS 15.0 software package. RESULTS: Significant changes of G'-Pg', Li-1, Si-B and Ls-E line between before and after treatment were found in the study group, while Li-1, Ls-E line and Li-E line changed significantly in control group. The change of Li-E line was different between the 2 groups. CONCLUSIONS: Twin-block combined with fixed appliance treatment is better than extraction with fixed appliance treatment in promoting lower facial profile in cases of skeletal Class II malocclusion and mandibular retrognathia with growth potentials.

[Efficacy evaluation of fixed Twin-block appliance and tooth extraction in skeletal Class II malocclusion].

PURPOSE: To evaluate the skeletal and dentoalveolar effects of Twin-Block combined with straight wire appliances and tooth extraction in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals. METHODS: The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, divided into 2 groups. One group (18 patients) was treated with fixed Twin-block combined with fixed appliance; the other group (13 patients) was only treated with fixed appliance after tooth extraction. Lateral cephalograms pretreatment and posttreatment were taken before and after Twin-block treatment and after all fixed appliance treatment. Pancherz's cephalometric measurements were analyzed statistically. Intragroup and intergroup changes of the two groups were evaluated by test using SPSS 15.0 software package. RESULTS: According to Pancherz's analysis, mandibular length increased, point Pg, mandibular incisors and first molars moved forward, maxillary incisors moved backward, overjet decreased (P<0.05) after treatment with Twin-block and fixed appliance. Within the rectification of anterior overjet, proportion of dentofacial factor was 39.5%, skeletal factor was 60.5%. Within the rectification of posterior relationship, proportion of dentofacial factor was 44.9%, skeletal factor was 55.1%. CONCLUSIONS: Twin-block combined with fixed appliance treatment can efficiently promote mandibular growth, restrict forward growth of maxilla to some extent, correct incisor and molar relationship and improve skeletal profile in growing skeletal Class II individuals with mandibular retrognathia.

[Application of the pin-hole marker measurement of the irregular silicone impression accuracy].

PURPOSE: To investigate the feasibility of the pin-hole marker measurement of the irregular silicone dental impression accuracy. METHODS: The metal model simulating abutment preparations had triangle-formed circular needles on the surface. Two silicone impressions were made by the metal model with the corresponding pin-hole markers. The dimensional change of the markers was evaluated by stereomicroscope. The records were output by the software which could simulate the centre of a circle to measure the displacement and dimensional accuracy. RESULTS: The outline of pin-hole marker was clear and shape was stable. Values of center coordinates were repeated well. The percentage of linear dimensional change of two impression samples was 0.023% and 0.042% at 48h respectively. Between two abutment preparations, the percentage of linear dimensional change of Zhermeck silicone impression increased 0.214% (45.1µm) at 1h and decreased 0.019% (4.0µm) at 48h while 3M silicone impression increased 0.087%(18.2µm) at 1h and decreased 0.09% (18.8µm) at 48h. CONCLUSION: The pin-hole marker measurement of the irregular silicone impression accuracy was feasible.

[Clinical analysis of two-phase treatment of 35 cases with Angle Class II division 1 malocclusion].

PURPOSE: To evaluate the clinical value of the two-phase treatment of Angle Class II division 1 malocclusion. METHODS: Thirty five cases with Class II division 1 malocclusion were treated with two-phase treatment(Twin-block functional appliance and fixed appliance).Lateral cephalograms were taken before and after treatment for each patient. The results were analyzed with paired t test using SPSS11.0 software package. RESULTS: After treatment ,the bite relation of molars ,the overbite and overjet and soft tissue profile were improved. ANB angle,U1-SN,OB,OJ,UL-E,ULP were decreased respectively(P<0.01). SNB, C(o)-G(o),G(o)-G(n),C(o)-G(n) were increased respectively(P<0.01). L1-Mp and FH-MP were increased, too(P<0.05). CONCLUSIONS: Twin-block functional appliance possesses the orthopedic effects on Angle Class II division 1 malocclusion.It limits the maxillary growth forward and promotes the mandibular growth by repositioning the mandible forward.These may contribute to a harmonious relationship of upper and lower jaws and a better profile.