[Effect of different cleaning methods on bond strength and surface wettability of high translucency zirconia].

PURPOSE: To study the effect of different cleaning methods on the shear bond strength of self-adhesive resin cement to saliva-contaminated high translucency zirconia and surface wettability. METHODS: Eighty zirconia specimens were randomly divided into 5 groups (n=16), i.e., control group(not contaminated), 75% ethanol group,cleaning paste group,airborne-particle abrasion group, and atmospheric pressure cold plasma group. The contact angles was measured, shear bond strength were examined, and fracture types were determined. SPSS 26.0 software package was used for statistical analysis of the data. RESULTS: The atmospheric pressure cold plasma group produced the lowest contact angle(P＜0.05). The shear bond strength of the airborne-particle abrasion group, the cleaning paste group and the atmospheric pressure cold plasma group respectively were similar to the control group without significant difference(P＞0.05), while those were significantly higher than 75% ethanol group(P＜0.05). The mixed fracture mode of the atmospheric pressure cold plasma group evidently increased. CONCLUSIONS: Airborne-particle abrasion, cleaning paste and atmospheric pressure cold plasma overcome the effects of saliva contamination, producing the shear bond strength to zirconia similar to the control group. The atmospheric pressure cold plasma improves hydrophilicity of high translucency zirconia significantly.

Increasing prevalence and influencing factors of childhood asthma: a cross-sectional study in Shanghai, China.

BACKGROUND: Asthma has been a global problem, especially in children. We aim to evaluate the contemporary prevalence and influencing factors of asthma among children aged 3-7 years in Shanghai, China. METHODS: A random sample of preschool children was included in this study. The International Study of Asthma and Allergies in Childhood questionnaire was adopted to assess the childhood asthma. Multivariable logistic regression models were used to evaluate the associations between independent variables and childhood asthma. RESULTS: Of 6389 preschool children who were invited to take part in this study, 6163 (response rate: 96.5%) completed the questionnaire and were included in the analysis. The overall prevalence of asthma was 14.6% which increased more than six folds from 2.1% in 1990. Being male, younger age, preterm delivery, being born in spring or autumn, being delivered by elective cesarean section without indication, miscarriage, high socioeconomic status, having allergy history, and exposure to passive smoking, latex paint, and dust were potential risk factors for childhood asthma. Spending more time outdoors (> 30 min/day), having indoor plants, and cleaning rooms more frequently were potential protective factors. CONCLUSIONS: The prevalence of childhood asthma in Shanghai has increased dramatically during the past three decades. The findings about risk and protective factors of childhood asthma could be used to develop appropriate strategies to prevent and control childhood asthma in Shanghai and in other similar metropolitan cities.

Time-dependent reactive oxygen species inhibit Streptococcus mutans growth on zirconia after a helium cold atmospheric plasma treatment.

As an efficient strategy for the modification of material surfaces, cold atmospheric plasma (CAP) has been used in dentistry to improve hard and soft tissue integration of dental implant materials. We previously found the Streptococcus mutans growth was inhibited on the surface of zirconia implant abutment after a 60-second helium cold atmospheric plasma treatment. However, the mechanism of bacterial growth inhibition on CAP-treated zirconia has not been fully understood. The duration of bacterial inhibition effectiveness on CAP-treated zirconia has also been insufficiently examined. In this work, we assume that reactive oxygen species (ROS) are the primary cause of bacterial inhibition on CAP-treated zirconia. The ROS staining and an ROS scavenger were utilized to evaluate the bacterial intracellular ROS level, and to determine the role of ROS in bacterial growth inhibition when seeded on CAP-treated zirconia. The time-dependent effectiveness of CAP treatment was determined by changes in surface characteristics and antibacterial efficacy of zirconia with different storage times after CAP treatment. This study confirmed that the presence of reactive oxygen species on the zirconia surface after CAP treatment inhibits the growth of Streptococcus mutans on the material surface. Although the antibacterial efficacy of the 60-second CAP-treated zirconia decreased over time, there were fewer bacteria on the treated surface than those on the untreated surface after 14 days.

Evaluation of Newly Developed Double-layer Composite Resin Teeth for Crown Preparation Training.

OBJECTIVE: To evaluate and compare the crown preparation performance of preclinical dental students training with conventional composite resin teeth and newly developed double-layer composite resin teeth. METHODS: The newly developed composite resin teeth consisted of two layers with different colours and hardnesses. Twenty third-year undergraduate dental students (8 men, 12 women) were randomly assigned to the control group (Group 1, using conventional composite resin teeth; n = 10) or the experimental group (Group 2, using double-layer composite resin teeth; n = 10) to prepare metal-ceramic crowns. To practice, each student prepared one tooth per day for 2 days. For the baseline test and final test before and after the practice period, both groups used traditional teeth. The operation time was recorded and the prepared teeth were scored blindly by two experienced instructors. The time and scores were compared within and between groups to determine the difference (α = 0.05). RESULTS: Students in both groups spent less time (P < 0.05) and achieved better scores (P < 0.001) on the final test than the baseline test (P < 0.01). In the final test, no significant difference in operating time was found between the two groups (P > 0.05), but Group 2 yielded significantly higher scores (P < 0.05). CONCLUSION: Training with the double-layer composite resin teeth enabled students to progress more quickly in terms of operating time and achieve higher scores. Use of this newly-developed tooth in crown preparation teaching practice therefore yields highly promising results.

[Study on the correlation between the mandibular masticatory muscle movement and sleep tooth wear].

OBJECTIVE: To investigate the correlation between the clinical diagnostic criteria of sleep bruxism and the frequency of mandibular movements during sleep. METHODS: Video polysomnography was used to record 20 healthy adults with at least one of the following clinical symptoms and signs: 1) report of frequent tooth grinding; 2) tooth wear and dentin exposure with at least three occlusal surfaces; 3) masticatory muscle symptoms in the morning; 4) masseter muscle hypertrophy. The rhythmic masticatory muscle activity (RMMA) and isolated tonic activity were scored to compare the correlations with clinical symptoms and signs. Finally, the incidence of temporomandibular disorders (TMD) was investigated in patients with isolated tonic and RMMA subjects. RESULTS: Among the 20 subjects, RMMA events were observed (5.8±3.1) times·h⁻¹ and isolated tonic episodes were observed (2.1±0.9) times·h⁻¹. The frequency of RMMA events was significantly greater in the patients with acoustic molars than in those without (P<0.05). Similarly, the frequency of RMMA events was significantly greater in the patients with tooth attrition than in those without (P<0.05). However, no difference was observed between the occurrence of RMMA and the symptoms of masticatory muscles or masseter hypertrophy in the morning. The incidence of TMD was significantly higher in the patients with RMMA than in the isolated tonic patients. CONCLUSIONS: The clinical symptoms and signs often used to diagnose sleep bruxism are different clinical and physiological mandibular movements during sleep. RMMA during sleep can reflect the occurrence of tooth attrition and the high risk of TMD.

Inhibition of bacterial growth on zirconia abutment with a helium cold atmospheric plasma jet treatment.

OBJECTIVES: This study presents a surface modification method to treat the zirconia implant abutment materials using a helium cold atmospheric plasma (CAP) jet in order to evaluate its efficacy on oral bacteria adhesion and growth. MATERIALS AND METHODS: Yttrium-Stabilized Zirconia disks were subjected to helium CAP treatment; after the treatment, zirconia surface was evaluated using scanning electron microscopy, a contact angle measuring device, X-ray photoelectron spectroscopy for surface characteristics. The response of Streptococcus mutans and Porphyromonas gingivalis on treated surface was evaluated by a scanning electron microscopy, MTT assay, and LIVE/DEAD staining. The biofilm formation was analyzed using a crystal violet assay. RESULTS: After the helium CAP jet treatment, the zirconia surface chemistry has been changed while the surface topography remains unchanged, the bacterial growth was inhibited, and the biofilm forming decreased. As the treatment time increases, the zirconia abutment showed a better bacterial inhibition efficacy. CONCLUSIONS: The helium CAP jet surface modification approach can eliminate bacterial growth on zirconia surface with surface chemistry change, while surface topography remained. CLINICAL RELEVANCE: Soft tissue seal around dental implant abutment plays a crucial role in maintaining long-term success. However, it is weaker than periodontal barriers and vulnerable to bacterial invasion. CAP has a potential prospect for improving soft tissue seal around the zirconia abutment, therefore providing better esthetics and most of all, prevent peri-implant lesions from happening.

[Characteristics of Aerosol Particulate Concentrations and Their Climate Background in Shanghai During 2007-2016].

We use daily aerosol particulate matter<10 µm (PM10) concentration data from 2006 to 2016 in Shanghai along with meteorological elements (wind and temperature), atmospheric stability, temperature inversion, and upper atmosphere circulation data, to analyze the variation characteristics of the PM10 concentrations and differences of the winter climate background. We establish a multivariate linear stepwise regression equation, and also compare and analyze differences in the upper atmospheric circulation by selecting the years with the highest and lowest PM10 concentrations. The results showed an oscillating downward trend in the annual average concentrations of PM10 in Shanghai, whereas seasonally, PM10 concentrations were relatively high in winter and showed two peaks with a low in between. PM10 concentrations were negatively correlated with the daily average wind speed and the daily mixing layer height at 20:00, and positively correlated with the frequency of northwest wind, the mean daily temperature, and the frequency of stable weathers and thermal inversion at 20:00. When the 500 hPa height field in the northern part of China was a positive anomaly in winter, a warm winter prevailed and led to high PM10 concentrations. When the 500 hPa height field was a negative anomaly, cold air frequently moved southward to result in relatively low temperatures, which caused relatively low PM10 concentrations. When the wind field at 850 hPa was easterly, the wind speed was relatively large and resulted in relatively low PM10 concentrations.

Effect of Provisional Restorations with Ovate Pontics on Preservation of the Ridge after Tooth Extraction: Case Series.

OBJECTIVE: To evaluate the effect of provisional restorations using ovate pontics on the hard and soft tissues of the alveolar ridge after tooth extraction. METHODS: Patients with intact buccal bone after extraction of a maxillary incisor underwent a series of treatments. The protocol included tooth extraction and provisional restoration using ovate pontics. The outcomes were assessed 1, 3 and 6 months after the procedure, regarding changes in bone volume and soft tissue dimension. RESULTS: A total of 11 patients (6 female and 5 male) were treated using an ovate pontic provisional restoration after tooth extraction. After 6 months, bone loss at level 1, 3 and 5 mm below the most coronal section of the bone crest was 2.28 ± 0.53 mm, 1.51 ± 0.30 mm and 1.46 ± 0.41 mm, respectively. Changes in bone volume of these three levels were significantly lower (P < 0.01) than changes previously reported in the literature. The mesial and distal papillae recessed 0.47 ± 0.24 mm and 0.88 ± 0.57 mm, respectively, whereas the midfacial shrinkage was 0.86 ± 0.44 mm. The dimension of the ridge contour around the socket reduced mostly at 3 and 5 mm below the coronal section and the gingival mucosa, with values of 1.68 ± 0.48 mm and 1.61 ± 0.48 mm, respectively. CONCLUSION: Using a provisional restoration with ovate pontics after tooth extraction may preserve the alveolar ridge by sustaining the soft tissue, in particular the gingival papilla.

Effects of a modified cold atmospheric plasma jet treatment on resin-dentin bonding.

The radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma is a novel cold atmospheric plasma (CAP) source, which has low energy characteristic. This study investigated the effect of RF-APGD plasma on the mechanical properties of dentin collagen and resin-dentin bonding. The scanning electron microscopy analysis was performed before and after a novel RF-APGD plasma and a conventional CAP treatment and a tensile test was carried out for the stiffness of dentin collagen. The microtensile resin-dentin bond strength was tested either immediately or after a 50,000-cycle thermocycling process. Dentin collagen maintained an intact structure after a 45-s RF-APGD plasma treatment, whereas even a 10-s treatment with the conventional CAP collapsed the collagen scaffold. When compared with control groups, the RF-APGD plasma treatment showed: (i) an improved stiffness of dentin collagen; (ii) a significant improvement in the bonding strength before/after artificial aging. Thus, RF-APGD plasma treatment has excellent prospects as a resin-dentin bonding protocol.

Morphometric measurement of the cervical spine for minimally invasive pedicle screw fixation using reverse engineering and three-dimensional reconstruction.

BACKGROUND: Percutaneous cervical pedicle screw fixation has been proven to be an effective method of cervical screw instrumentation, which has the advantages of less invasiveness and low blood loss. Emerging evidence has indicated that the cervical spinous process plays an important role in percutaneous spine surgery. However, there is a limited amount of information on the fundamental research of pedicle and its associated imaging parameter measurement. The purpose of this study was to measure the anatomic data of the pedicle screw channel (PSC) using reverse engineering and three-dimensional reconstruction, and also to discuss the three-dimensional relationship between the cervical spinous process and the pedicle screw channel. METHODS: Twenty adult subjects (10 males, 10 females, age range 19-46 years) were studied using the method of three-dimensional CT reconstruction and reverse engineering. The centrum was divided into 10 equal parts from front to back. The bisectors were defined as borderline depths of the centrum, from front to back, 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 0% of borderline depths were presented. Then, a 3D coordinate system was constructed to measure all the data, including the radius of the inscribed circle, the length of the PSC, the insertion angle, the distances from entry point to cervical spinous process and skin depth. All the indexes were measured from 70% to 90% borderline depth. RESULTS: The radius of the inscribed circles from C3 to C7 at 90% borderline depth were 2.94 ± 0.55 mm, 3.04 ± 0.40 mm, 3.15 ± 0.36 mm, 3.28 ± 0.47 mm, 3.89 ± 0.54 mm, respectively. The lengths of the PSC were between 25 and 32 mm. The insertion angles for 70% to 90% borderline depth were 28.33°, 34.28°, 37.92°, respectively. The relationship between the PSC and spinous process was measured as the distance from the entry point to the end of the spinous process, which were, respectively, 26.91 mm, 28.18 mm, 30.03 mm, 35.67 mm, 41.99 mm from C3 to C7 .The distance from the skin to the entry point of C3-7 increased gradually. CONCLUSIONS: The measurements of this study could provide detailed information for percutaneous cervical screw fixation. The data of the relationship between the cervical spinous process and the pedicle screw channel present valuable technical information for the design, optimization and clinical application of the aiming device for percutaneous cervical pedicle screw fixation. Copyright © 2016 John Wiley & Sons, Ltd.

[Stability of phonetics to determine the horizontal jaw relation in healthy adults].

OBJECTIVE: The aim of this study was to compare the mandibular position when speaking with the intercuspal position and to check the stability of phonetics when determining the horizontal jaw relation in healthy adults. METHODS: A total of 19 healthy volunteers were recruited. Seven Chinese letters, namely, /xi/, /er/, /yi/, /ci/, /mi/, /ni/, and /ri/, were chosen in the test. O-bite was used to record the mandibular position when speaking these letters. A full-adjusted articulator was used to find the mandibular position during speech, and the mandibular position was measured using a vernier caliper. The mandibular position during speech with intercuspal position was compared in both anterior-posterior and left-right directions of the horizontal plane. Multi-factor analysis of variance was conducted for the statistical analysis of the effect of objects and letters on the mandibular position. RESULTS: 1) The mandibular position was in front of the intercuspal occlusion position when speaking all seven letters, and almost no deviation was observed in the left and right directions (the mandibular position value of 82% was in the range of 0.5 mm). 2) Different objects had different mandibular positions during speech, whereas different letters did not. The distance between the centric relation position and the intercuspal position had a positive correlation with the range of the mandibular position during speech. CONCLUSION: The mandibular position was in front of the intercuspal position when speaking all seven words in the test. In the same object, the mandibular position was stable during speech.

Enhanced Biological Behavior of In Vitro Human Gingival Fibroblasts on Cold Plasma-Treated Zirconia.

OBJECTIVE: To evaluate whether atmospheric-pressure dielectric-barrier-discharge plasma treatment of zirconia enhances its biocompatibility with human gingival fibroblasts. MATERIALS AND METHODS: The zirconia disks were divided into four groups and treated using helium atmospheric-pressure dielectric-barrier-discharge plasmas for 30, 60 or 90 s or left untreated. The surface morphology, wettability and chemical elements were analyzed. Fibroblasts density, morphology, morphometry and attachment-related genes expression were measured at different time points from 3 to 72 h. RESULTS: After plasma treatment, the surface morphology and roughness remained the same, while the contact angle decreased from 78.31° to 43.71°, and the surface C/O ratio decreased from 3.17 to 0.89. The surficial areas and perimeters of HGFs were increased two-fold in the treated groups at 3 h. Fibroblasts density increased on treated disks at all time points, especially the ones treated for 60 s. Attachment-related genes in the groups treated for 30 and 60 s were significantly higher at 3 and 24 h. CONCLUSION: The helium atmospheric-pressure dielectric-barrier-discharge plasma treatment enhances the biological behavior of fibroblasts on zirconia by increasing the expression of attachment-related genes within 24 h and promoting the cell density during longer culture times. Wettability of zirconia, an important physicochemical property, has a vital influence on the cell behaviors.

Impact of temperature on mortality in three major Chinese cities.

OBJECTIVE: To study the relation between temperature and mortality by estimating the temperature-related mortality in Beijing, Shanghai, and Guangzhou. METHODS: Data of daily mortality, weather and air pollution in the three cities were collected. A distributed lag nonlinear model was established and used in analyzing the effects of temperature on mortality. Current and future net temperature-related mortality was estimated. RESULTS: The association between temperature and mortality was J-shaped, with an increased death risk of both hot and cold temperature in these cities. The effects of cold temperature on health lasted longer than those of hot temperature. The projected temperature-related mortality increased with the decreased cold-related mortality. The mortality was higher in Guangzhou than in Beijing and Shanghai. CONCLUSION: The impact of temperature on health varies in the 3 cities of China, which may have implications for climate policy making in China.

[Coverage errors of five shade guide systems to vital natural teeth].

OBJECTIVE: To compare the coverage errors (CE) of five different shade guides in anterio vital natural teeth of selected people. METHODS: Anterior vital natural teeth were measured with Crystaleye spectrophotometer, color coordinates of the teeth and five shade guides A (VITA Classical), B (VITA 3D-Master), C (Chromascop), D (Shofu Vintage Halo NCC) and E (Noritake)were analyzed with the supporting software. The CE of the five shade guide systems to natural teeth were evaluated in cervical, body and incisal regions, and difference in CE among shade guides was determined. RESULTS: In the cervical region, shade guide A had the maximal CE value (3.09 ± 0.97) and shade guide D had the minimal CE value (1.62 ± 0.75).In the body region, CE of shade guide B (1.65 ± 0.64) and shade guide D (1.52 ± 0.74) were lower than those of shade guides A (2.04 ± 0.80), C (2.04 ± 0.90) and E (2.02 ± 0.84) (P < 0.05).In the incisal part, all CE were below 2.00, and again shade guide A had the maximal CE value (1.81 ± 0.86) and shade guide D had the minimal CE value (1.28 ± 0.55). CONCLUSIONS: Within the limitation of the study, shade guide D had better color coverage of natural teeth in cervical, body and incisal regions.

[Precision and accuracy of a dental spectrophotometer in gingival color measurement of maxillary anterior gingival].

OBJECTIVE: To explore a gingival shade matching method and to evaluate the precision and accuracy of a dental spectrophotometer modified to be used in gingival color measurement. METHODS: Crystaleye, a dental spectrophotometer (Olympus, Tokyo, Japan) with a custom shading cover was tested. For precision assessment, two experienced experimenters measured anterior maxillary incisors five times for each tooth. A total of 20 healthy gingival sites (attached gingiva, free gingiva and medial gingival papilla in anterior maxillary region) were measured,the Commission Internationale de I' Eclairage (CIE) color parameters (CIE L*a*b*) of which were analyzed using the supporting software. For accuracy assessment, a rectangular area of approximately 3 mm×3 mm was chosen in the attached gingival portion for spectral analysis. PR715 (SpectraScan;Photo Research Inc.,California, USA), a spectroradiometer, was utilized as standard control. Average color differences (ΔE) between the values from PR715 and Crystaleye were calculated. RESULTS: In precision assessment,ΔL* between the values in all the test sites and average values were from(0.28±0.16)to(0.78±0.57), with Δa*and Δb* from(0.28±0.15)to (0.87±0.65),from(0.19±0.09)to( 0.58±0.78), respectively. Average ΔE between values in all test sites and average values were from (0.62 ± 0.17) to (1.25 ± 0.98) CIELAB units, with a total average ΔE(0.90 ± 0.18). In accuracy assessment, ΔL* with control device were from(0.58±0.50)to(2.22±1.89),with Δa*and Δb* from(1.03±0.67)to(2.99±1.32),from(0.68±0.78)to(1.26±0.83), respectively. Average ΔE with the control device were from (2.44±0.82) to (3.51±1.03) CIELAB units, with a total average ΔE (2.96 ± 1.08). CONCLUSION: With appropriate modification, Crystaleye, the spectrophotometer, has demonstrated relative minor color variations that can be useful in gingival color measurement.

[Effect of Shofu gingival matrices which simulate the gingival color on spectrophotometric tooth color measurement].

OBJECTIVE: To investigate the effect of gingival color on spectrophotometric color measurement in a standardized model. METHODS: Shofu gingival matrices were used to simulate the soft tissue and VITA Classical shade tabs were fixed into them. Both the gingival matrices and shade tabs were measured with Crystaleye spectrophotometer in a black box. Regions of the shade tabs, gingival color and their combinated effect on measurements were analyzed, Pearson correlation analysis was used to identify the correlation of the gingival color difference with the shade tabs color difference. RESULTS: The ranges of color difference were 1.01-2.26 in the cervical, 0.93-1.27 in the body and 1.67-2.97 in the incisal regions, respectively. Statistical analysis revealed that there was significant difference among all the gingival groups in the cervical region. Color differences were similar in the body and the incisal regions. The color measurement with Crystaleye was influenced by the regions of the shade tabs, the gingival color and their combination (P<0.001). Pearson Correlation Coefficient was 0.646 in the cervical, 0.386 in the body and 0.217 in the incisal regions respectively(P<0.001). CONCLUSION: The color measurement in the cervical region with the spectrophotometer was influenced by the color of the simulated gingiva. Such influence was not obvious in the body and incisal regions. Color coordinates changed regularly with the gingival color.

An internet evaluation of Chinese public preferences for asymmetrically altered incisor angulations.

OBJECTIVE: To evaluate the Chinese public preferences for asymmetrically altered incisor angulations, with the goal of linking preferences to gender. METHODS: Five variations of 5 separate digital smiling photographs were used in this survey. The alterations included discrepancy between the dental and facial midlines, inclination of dental midline and two central incisors, inclination of left central incisor (mesially or distally) and occlusal cant. The raters used a 100-point visual analogue scale to evaluate each image on a web page. RESULTS: Overall 1,022 raters joined the evaluation and they were reliable (intraclass correlation coefficient = 0.76-0.80). Raters identified range of approval for several smile characteristics. A 2 mm dental to facial midlines discrepancy was the maximum acceptable deviation for females and 3 mm was the maximum for males. Females could accept a 4-degree occlusal cant and males could accept a 6-degree cant. These two characteristics were related to gender. The dental midline and relevant two central incisors with a 5-degree slope or less were generally acceptable. The approval of a left central incisor inclination was 5 degrees mesially and 10 degrees distally. These three characteristics were unrelated to gender. CONCLUSION: The approval for five smile characteristics could be identified reliably. The ranges of acceptability were large and slight changes in the angulations of incisors did not influence the smile attractiveness.

[H(2)O(2) treatment improves the bond strength between glass fiber posts and resin cement].

OBJECTIVE: To evaluate the effect of etching with H2O2 on the bond strength between epoxy-based glass fiber posts and resin cement. METHODS: Sixteen epoxy-based glass fiber posts were randomly divided into 4 groups (4 posts in each group) for different surface treatments. Group 1, no surface treatment (Control group); Group 2, treated with silane coupling agent for 60 s; Group 3, immersed in 10% H2O2 for 10 min then treated with silane coupling agent for 60 s; Group 4, immersed in 30% H2O2 for 10 min then treated with silane coupling agent for 60 s. Resin cement was used for the post cementation to form resin slabs which were then sectioned and trimmed into dumbbell shape to obtain microtensile specimens. Microtensile bond strengths were tested and the failure modes were examined with a stereomicroscope. Statistical analysis of microtensile bond strengths was performed with Kruskal-Wallis test. RESULTS: The microtensile bond strengths (standard deviation) were 18.81 (4.04) MPa for Group 1, 26.70 (9.63) MPa for Group 2, 39.07 (6.47) MPa for Group 3, 46.05 (5.97) MPa for Group 4. CONCLUSION: Etching with H2O2 followed by silanization could significantly improve the bond strength between epoxy-based glass fiber posts and resin cement.

Anatomical study to the vessels of the lower limb by using CT scan and 3D reconstructions of the injected material.

PURPOSE: To find out the advantages and insufficiency of the 3D reconstruction and traditional anatomy by comparing them with each other. METHODS: 1. Infused with the radio-opaque material from the arteries and veins, respectively, fresh lower extremity specimens were subjected to spiral CT scanning and then 3D reconstruction was conducted to obtain 3D vessels. 2. Anatomizing the specimens to show the vessel system. 3. Comparing the images of 3D reconstruction and photos of the dissected specimens. RESULTS: 3D software could dissect and reconstruct the bones, vessels, skin and muscles, and the reconstructed photos could be shown, respectively or combinedly. On the other hand, the course, distribution, and anastomoses of the vessels could be viewed from different aspects and different layers, but the results were not completely correct, so they were not suitable for data acquisition. While the vessel systems could be observed clearly on the dissected specimens, so could the origin, course, distribution and the anastomoses of any vessel. The data acquisition could be conducted. CONCLUSIONS: The method of angiography with 3D reconstruction is very good and has considerable advantages for observing the 3D state of human blood vessels, and their distribution at different angles and different levels, but it cannot totally represent or replace the traditional dissected specimens.

Effect of multiple coatings of one-step self-etching adhesive on microtensile bond strength to primary dentin.

OBJECTIVE: To investigate the effect of multiple coatings of the one-step self-etching adhesive on immediate microtensile bond strength to primary dentin. METHODS: Twelve caries-free human primary molars were randomly divided into 2 groups with 6 teeth each. In group 1, each tooth was hemisected into two halves. One half was assigned to control subgroup 1, which was bonded with a single-step self-etching adhesive according to the manufacturer's instructions; the other half was assigned to experimental subgroup 1 in which the adhesive was applied three times before light curing. In group 2, the teeth were also hemisected into two halves. One half was assigned to control subgroup 2, which was bonded with the single-step self-etching adhesive according to the manufacturer's instructions; the other half was assigned to experimental subgroup 2 in which three layers of adhesive were applied with light curing each successive layer. Microtensile bond strength was immediately tested after specimen preparation. RESULTS: When the adhesive was applied three times before light curing, the bond strength of the experimental subgroup 1 (n=33, 57.49 +/-11.61 MPa) was higher than that of the control subgroup 1 (n=31, 49.71 +/-11.43 MPa, P<0.05). When using the technique of applying multiple layers of adhesive with light curing each successive layer, no difference of immediate bond strength was observed between the control subgroup 2 and the experimental subgroup 2 (P>0.05). CONCLUSION: strength to primary dentin when using the technique of light-curing after applying three layers of adhesive.