Assessment of the Binding of Pseudallecin A to Human Serum Albumin with Multi-Spectroscopic Analysis, Molecular Docking and Molecular Dynamic Simulation.

The binding of pseudallecin A (PA), a potential antibiotic with strong inhibitory activities against Gram-positive Escherichia coli and Gram-negative Staphylococcus aureus, to human serum albumin (HSA) was explored. The interaction between them was assessed by multi-spectroscopic analysis, binding site competitive analysis, molecular docking and molecular dynamic simulation, showing the results as follows: PA effectively quenched the innate fluorescence of HSA by a static quenching process, formed a complex at a molar ratio of approximately 1 : 1 and performed an effective non-radiative energy transfer; the binding of PA to HSA was a spontaneous exothermic reaction driven by enthalpy with strong affinity and had a slight effect on the conformation of HSA; PA bound at site III of HSA and hydrogen bonds were the major binding forces to maintain the stability of the PA-HSA complex. Molecular dynamic simulation was performed to calculate the root mean square deviation (RMSD), root mean square fluctuation (RMSF) and radius of gyration (Rg) for this complex and effectively supported the spectroscopic outcome. These results meant that the delivery and distribution of PA as a water-insoluble molecule can be efficiently accomplished via HSA in human blood and, it has a good potential for future drug application and pharmacological development.

A novel antibacterial tyroscherin derivative with a natural unprecedented morpholine-2, 3-dione structural unit from the fungus Pseudallescheria boydii.

A novel tyroscherin derivative named pseudallecin A (1) with a natural unprecedented morpholine-2, 3-dione structural unit, and a new biogenic synthesis related organic acid named pseudallecin B (2) were purified from a symbiotic fungus Pseudallescheria boydii derived from Pomacea canaliculata. Their structures were elucidated via spectroscopic analyses and ECD calculation. Pseudallecin A exhibited strong inhibitory activities against both Gram-positive Escherichia coli and Gram-negative Staphylococcus aureus.

A cone-beam computed tomographic study evaluating the efficacy of incisor movement with clear aligners: Assessment of incisor pure tipping, controlled tipping, translation, and torque.

INTRODUCTION: This retrospective clinical study aimed to evaluate the efficacy of different types of incisor movements with clear aligners in the sagittal plane. METHODS: Pretreatment and posttreatment cone-beam computed tomography (CBCT) scans were collected from 69 patients who underwent nonextraction treatment with clear aligners (Invisalign; Align Technology, San Jose, Calif). Integrated 3-dimensional models of the virtual incisor position (ClinCheck; Align Technology) and the posttreatment incisor position (from posttreatment CBCT scans) were superimposed over the pretreatment position (from pretreatment CBCT scans) using Mimics software (Materialise, Leuven, Belgium). On the basis of the location of the rotation center, incisors showing pure tipping (>10°), controlled tipping (>10°), translation (>1 mm), or torque (>10°) movements were selected. Efficacy was determined by comparing the predicted and achieved incisor movement, and differences with efficacy were analyzed using Kruskal-Wallis and Shapiro-Wilk tests (α = 0.05). RESULTS: In measurements for 231 incisors, the mean efficacy of incisor movements in the sagittal plane was 55.58%. The most and least predictable movements were pure tipping (72.48%) and torque (35.21%), respectively. Labial root movement was significantly more predictable than lingual root movement, and labial movement of the mandibular incisors was significantly easier than that of the maxillary incisors. The type of tooth movement achieved was different from the type designed. CONCLUSIONS: The efficacy of incisor movement in the sagittal plane using clear aligners varies with designed movement type, and labial root movement appears to be more accurate than the lingual root movement. The biomechanics of clear aligners remains to be further elucidated to achieve more predictable treatment results.

[Effects of lyophilized on the biological activities of lentiviral vector of bone morphogenetic protein 2].

PURPOSE: To investigate the influence of lyophilization on the biological activity of recombinant lentiviral vectors of bone morphogenetic protein 2(BMP-2). METHODS: Recombinant lenti-BMP-2 was constructed. lenti-BMP-2 was transfected with rat bone marrow stromal cells (BMSCs) by multiplicity infection (MOI) of 10, 25, 50, 100, 200. The infection efficiency was observed by X-gal staining. Under suitable conditions, the lenti-BMP-2 and 10% trehalose ratio of lyophilized protective agent was mixed into the lyophilization form. Before and after lyophilization, the effect of lenti-BMP-2 on the proliferation of BMSCs was evaluated by MTS assay. The expression of BMP-2 protein in the cells of lyophilized lenti-BMP-2 was detected by ELISA method. The expression of Runx-2, OCN, Col1 and OPN in BMSCs was detected by real-time PCR after transfection of lyophilized lenti-BMP-2. SPSS13.0 software package was used for statistical analysis. RESULTS: X-gal staining showed an MOI of 100 pfu/cell, and stable transfection efficiency. Before and after lyophilization, no significant change was observed in regard to the effect of lyophilized lenti-BMP-2 on BMSCs proliferation (P>0.05). ELISA method showed that BMSCs transfected by lyophilized lenti-BMP-2 could express BMP-2 protein continuously and stably at a high level. Before and after lyophilization, the result of real-time PCR showed that no significant difference in the expression of OPN,Col1,OCN and Runx-2 in BMSCs (P>0.05). CONCLUSIONS: Lyophilized lenti-BMP-2 with trehalose can maintain high activity for a long time as an effective and reliable storage method.

A Method of Three-Dimensional Recording of Mandibular Movement Based on Two-Dimensional Image Feature Extraction.

BACKGROUND AND OBJECTIVE: To develop a real-time recording system based on computer binocular vision and two-dimensional image feature extraction to accurately record mandibular movement in three dimensions. METHODS: A computer-based binocular vision device with two digital cameras was used in conjunction with a fixed head retention bracket to track occlusal movement. Software was developed for extracting target spatial coordinates in real time based on two-dimensional image feature recognition. A plaster model of a subject's upper and lower dentition were made using conventional methods. A mandibular occlusal splint was made on the plaster model, and then the occlusal surface was removed. Temporal denture base resin was used to make a 3-cm handle extending outside the mouth connecting the anterior labial surface of the occlusal splint with a detection target with intersecting lines designed for spatial coordinate extraction. The subject's head was firmly fixed in place, and the occlusal splint was fully seated on the mandibular dentition. The subject was then asked to make various mouth movements while the mandibular movement target locus point set was recorded. Comparisons between the coordinate values and the actual values of the 30 intersections on the detection target were then analyzed using paired t-tests. RESULTS: The three-dimensional trajectory curve shapes of the mandibular movements were consistent with the respective subject movements. Mean XYZ coordinate values and paired t-test results were as follows: X axis: -0.0037 ± 0.02953, P = 0.502; Y axis: 0.0037 ± 0.05242, P = 0.704; and Z axis: 0.0007 ± 0.06040, P = 0.952. The t-test result showed that the coordinate values of the 30 cross points were considered statistically no significant. (P<0.05). CONCLUSIONS: Use of a real-time recording system of three-dimensional mandibular movement based on computer binocular vision and two-dimensional image feature recognition technology produced a recording accuracy of approximately ± 0.1 mm, and is therefore suitable for clinical application. Certainly, further research is necessary to confirm the clinical applications of the method.

Surface roughness and wettability of dentin ablated with ultrashort pulsed laser.

The aim of this study was to evaluate the surface roughness and wettability of dentin following ultrashort pulsed laser ablation with different levels of fluence and pulse overlap (PO). Twenty-five extracted human teeth crowns were cut longitudinally into slices of approximately 1.5-mm thick and randomly divided into nine groups of five. Samples in groups 1 to 8 were ablated with an ultrashort pulsed laser through a galvanometric scanning system. Samples in group 9 were prepared using a mechanical rotary instrument. The surface roughness of samples from each group was then measured using a three-dimensional profile measurement laser microscope, and wettability was evaluated by measuring the contact angle of a drop of water on the prepared dentin surface using an optical contact angle measuring device. The results showed that both laser fluence and PO had an effect on dentin surface roughness. Specifically, a higher PO decreased dentin surface roughness and reduced the effect of high-laser fluence on decreasing the surface roughness in some groups. Furthermore, all ablated dentin showed a contact angle of approximately 0 deg, meaning that laser ablation significantly improved wettability. Adjustment of ultrashort pulsed laser parameters can, therefore,significantly alter dentin surface roughness and wettability.

Correction of a skeletal Class II malocclusion with severe crowding by a specially designed rapid maxillary expander.

To correct an Angle Class II malocclusion or to create spaces in the maxillary arch by nonextraction treatment, distal movement of the maxillary molars is required. Various modalities for distalizing the buccal segment have been reported. Conventional extraoral appliances can be used to obtain maximum anchorage. However, many patients reject headgear wear because of social and esthetic concerns, and the success of this treatment depends on patient compliance. Intraoral appliances, such as repelling magnets, nickel-titanium coils, pendulum appliance, Jones jig appliance, distal jet appliance, and modified Nance appliance, have been introduced to distalize the molars with little or no patient cooperation. However, intraoral appliances can result in anchorage loss of the anterior teeth and distal tipping of the maxillary molars. In this case report, we introduce a diversified rapid maxillary expansion appliance that was custom designed and fabricated for the treatment of a growing girl with a skeletal Class II malocclusion and severe crowding from a totally lingually positioned lateral incisor. The appliance concomitantly expanded the maxilla transversely and retracted the buccal segment sagittally, distalizing the maxillary molars to reach a Class I relationship and creating the spaces to displace the malpositioned lateral incisor. The uniqueness of this special diversified rapid maxillary expansion appliance was highlighted by a series of reconstructions and modifications at different stages of the treatment to reinforce the anchorage.

Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency.

The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm3∕J when the laser fluence was set at 6.51 J∕cm2. For enamel, the maximum ablation efficiency was 0.009 mm3∕J at a fluence of 7.59 J∕cm2.Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value.

Wettability of dentin after Yb:KYW thin-disk femtosecond ablation.

The aim of this study was to quantitatively evaluate the wettability of dentin after Yb:KYW thin-disk femtosecond-pulsed laser ablation by measuring the contact angle. Different laser parameters were used including different fluences (F), scanning speeds, and scanning line spacings. Crowns of 15 extracted human teeth were cut longitudinally into slices approximately 1.5-mm thick with a cutting instrument. The samples were randomly divided into ten groups (n = 3/group). Samples in groups 1-8 were irradiated with a femtosecond-pulsed laser. The dentin samples were fixed on a stage at the focal plane, and the laser beam irradiated the samples through a galvanometric scanning system so rectangular movement could be achieved. Samples in groups 9 and 10 were prepared with grinding instruments. Following ablation and preparation, the samples were examined for contact angle with an optical contact angle measuring instrument. The results showed that scanning speed and scanning line spacing had little influence on the wettability of dentin following femtosecond-pulsed laser ablation, except when F = 6 J/cm(2). For six out of the eight laser ablation groups, when a lower fluence was used, the dentin contact angle was higher and vice versa. Most of the dentin which had been ablated using the femtosecond-pulsed laser had improved wettability compared to samples prepared with the grinding instruments. This study showed that various laser fluences, scanning speeds, and scanning line spacings can alter dentin wettability. Therefore, adequate parameters should be chosen to achieve proper therapeutic benefits.

[Study of the mandibular growth phases and quantities in Shanghai adolescents].

PURPOSE: To study the growth phases and quantities of mandible in Shanghai adolescents. METHODS: The samples included 480 Shanghai adolescents from 8-20 years of age, 240 were male and 240 were female. Both male and female groups were divided into 6 consecutive developmental periods according to cervical vertebral maturation stages. Their cephalometric radiographs were measured and analyzed. Independent-sample t test was conducted by SPSS 15.0 software package. RESULTS: The total mandibular length (Co-Gn) increased significantly from CVMS1 to CVMS2 and CVMS3 to CVMS4 in both male and female group. For male the maximum increase was from CVMS3 to CVMS4 (P<0.01,average 9.54 mm), while female was from CVMS1 to CVMS2(P<0.01,average 9.09 mm). The height of mandibular ramus (Co-Go) increased continuously from CVMS2 to CVMS5 in male group, the significant increase was observed from CVMS2 to CVMS3 (P<0.01, average 8.80 mm). The significant increase in female group was observed from CVMS1 to CVMS2 (P<0.01, average 6.51 mm). In male group, the greatest increase of the mandibular base length (Go-Pog) appeared from CVMS3 to CVMS4 (P<0.01, average 7.55 mm), while in female group, it occurred from CVMS1 to CVMS2 (P<0.01, average 5.73 mm). CONCLUSIONS: The growth amounts of total mandibular length (Co-Gn), mandibular base length (Go-Pog) and ramus length are different at every CVM stages in male and female groups. The present finding will help to make reasonable diagnosis and treatment planning.

A Roughness Study of Ytterbium-Doped Potassium Yttrium Tungstate (YB: KYW) Thin-Disk Femtosecond Ablated Dentin.

INTRODUCTION: The aim of this study was to evaluate the morphological changes and quantitatively assess the roughness of dentin after the ablation with a Ytterbium-Doped Potassium Yttrium Tungstate (YB: KYW) thin-disk femtosecond pulsed laser of different fluences, scanning speeds and scanning distances. METHOD: Twelve extracted human premolars were sectioned into crowns and roots along the cementum-enamel junction, and then the crowns were cut longitudinally into sheets about 1.5 mm thick with a cutting machine. The dentin samples were fixed on a stage at focus plane. The laser beam was irradiated onto the samples through a galvanometric scanning system, so rectangular movement could be achieved. After ablation, the samples were examined with a scanning electron microscope and laser three-dimensional profile measurement microscope for morphology and roughness study.With increasing laser fluence, dentin samples exhibited more melting and resolidification of dentin as well as debris-like structure and occluded parts of dentinal tubules. RESULTS: When at the scanning speed of 2400mm/s and scanning distance of 24µm, the surface roughness of dentin ablated with femtosecond pulsed laser decreased significantly and varied between values of dentin surface roughness grinded with two kinds of diamond burs with different grits. When at the scanning speed of 1200mm/s and scanning distance of 12µm, the surface roughness decreased slightly, and the surface roughness of dentin ablated with femtosecond pulsed laser was almost equal to that grinded with a low grit diamond bur. CONCLUSION: This study showed that increased laser influence may lead to more collateral damage and lower dentin surface roughness, while scanning speed and scanning distance were also negatively correlated with surface roughness. Adequate parameters should be chosen to achieve therapeutic benefits, and different parameters can result in diverse ablation results.

[Initial evolution research for design and process accuracy of one type of domestic computer aided design soft and computer aided manufacture].

OBJECTIVE: To evaluate the design and manufacture accuracy of a domestic computer aided design (CAD) and computer aided manufacture (CAM) system, and to compare it with similar foreign products. METHODS: Thirty models of posterior-teeth-single-crown preparations were collected, and STL data of these preparations was collected by Denmark 3Shape scanner. Three copings were made for each preparation, the one designed and manufactured using commercial CAD/CAM system (3Shape CAD software and Wieland T1 CAM equipment) was assigned into control group T0, the one designed and manufactured using domestic CAD software (developed by Peking University School and Hospital of Stomatology and Nanjing University of Aeronautics and Astronautics) and Wieland T1 CAM equipment was assigned into experimental group TCAD for design accuracy evaluation, and the one designed and manufactured using 3Shape CAD software and domestic CAM equipment (developed by Peking University School and Hospital of Stomatology, Tsinghua University and ShanDong XinHua Incorporated Company of medical apparatus and instruments) was assigned into experimental group TCAM for manufacture accuracy evaluation. Finally, the marginal fitness were compared and evaluated by using 3D & Profile measurement microscope laser. RESULTS: The marginal fitness of TCAD was 27.98 (19.10, 46.57) µm in buccal, 32.67 (20.65, 50.82) µm in lingual, 27.38 (22.53, 52.61) µm in mesial, 29.50 (22.68, 53.65) µm in distal; of TCAM was 21.69 (15.87, 30.21) µm in buccal, 18.51 (13.50, 22.51) µm in lingual, 19.15 (15.42, 26.89) µm in mesial, 22.77 (18.58, 32.15) µm in distal; and there were no statistical differences compared with T0 [20.16 (17.16, 48.00) µm in buccal, 21.51 (17.05, 28.31) µm in lingual, 23.54 (17.89, 30.04) µm in mesial and 23.94 (17.93, 28.19) µm in distal] except lingual data of TCAD. CONCLUSIONS: The design and machining precision of this domestic CAD/CAM system is at the same level of those comparable foreign products.

[Preliminary evaluation of clinical effect of computer aided design and computer aided manufacture zirconia crown].

OBJECTIVE: To evaluate clinical effects of computer aided design and computer aided manufacturing (CAD/CAM) milled zirconia crown in three aspects: aesthetic, contact wear and fracture. METHODS: Sixty patients were divided into two groups.In one group, 35 full contour CAD/CAM zirconia crown were made on molars of 30 patients. The manufacturing process of zirconia crown was as follow. First, the three dimensional(3-D) data of working models, antagonist impression and check records were acquired by 3-D laser scanning Dental wings S50. Then full contour zirconia crowns, which had functional occlusal contacts with antagonistic teeth, and appropriate contact with adjacent teeth were designed with Zeno-CAD(V4.2.5.5.12919) software. ZENOSTAR Zr pure zirconia material was milled in digital controlled machine WIELAND 4030 M1.In the end, the zirconia crown were completed with the method of second sintering and polishing. After clinical try-in, the crown was cemented.In the control group, thirty gold alloy full crown were made and cemented on molars of 30 patients. According to the modified U S Public Health Service Criteria(USPHS) evaluation standard, all crowns were evaluated on the same day, at three months, half a year, one year and two years following delivery. There were three aspects we were focusing on in the evaluation: aesthetic, contact wear(restoration and antagonist), and fracture. RESULTS: In all the prosthesis we evaluated during the 24 months, no fracture was found. Contact wear of crowns varies according to different antagonist teeth. CONCLUSIONS: The zirconia crowns show privilege in aesthesis, toughness and anti-wearing.However, there is contact wear on antagonistic natural teeth. Thus it is a good choice when full zirconia crowns are indicated on two antagonistic teeth in both jaws.

[Effects of fluence and scanning velocity on the ablation efficiency of dentin and enamel by femtosecond laser].

OBJECTIVE: To measure the effect of laser fluence and scanning velocity on ablation efficiency of enamel and dentin. METHODS: Two extracted human incisors and two molars were cut transversely along the axial plane with a diamond saw to obtain dentin and enamel slices with thickness of about 1 mm. Samples were fixed on a motorized translation stage, the linear reciprocating movement in the plane perpendicular to the direction of laser incident was programmed by the controller, and the laser focused on the tooth surface, then 36 ablation lines on enamel and 48 ablation lines on dentin were produced. A femtosecond laser system with wavelength of 800 nm, pulse width 30 fs, repetition frequency 1000 Hz was used, and the diameter of the focused spot was approximately 25 µm. A group of different fluence (1.33, 1.77, 2.21, 4.42, 8.85, 17.69 J/cm(2) for enamel and 0.44, 0.66, 0.88, 1.33, 1.77, 2.21, 4.42, 6.63 J/cm(2) for dentin) and two scanning velocity (10 mm/s and 20 mm/s) were tested. Confocal laser scanning microscope was used to measure the ablation volume.Ablation efficiency for enamel and dentin was then calculated. RESULTS: Under the fluence of 8.85 J/cm(2) there was the highest ablation efficiency for enamel, 18.703×10(-3) mm(3)/J (20 mm/s), and the highest ablation efficiency for dentin was found under the fluence of 2.21 J/cm(2), ie.223.458×10(-3) mm(3)/J (20 mm/s). CONCLUSIONS: Fluence and scanning speed of this femtosecond laser can affect ablation efficiency for both enamel and dentin, and this suggests that with appropriate choice of fluence and scanning speed we can improve the ablation efficiency for enamel and dentin.

Accuracy evaluation of a new three-dimensional reproduction method of edentulous dental casts, and wax occlusion rims with jaw relation.

The article introduces a new method for three-dimensional reproduction of edentulous dental casts, and wax occlusion rims with jaw relation by using a commercial high-speed line laser scanner and reverse engineering software and evaluates the method's accuracy in vitro. The method comprises three main steps: (i) acquisition of the three-dimensional stereolithography data of maxillary and mandibular edentulous dental casts and wax occlusion rims; (ii) acquisition of the three-dimensional stereolithography data of jaw relations; and (iii) registration of these data with the reverse engineering software and completing reconstruction. To evaluate the accuracy of this method, dental casts and wax occlusion rims of 10 edentulous patients were used. The lengths of eight lines between common anatomic landmarks were measured directly on the casts and occlusion rims by using a vernier caliper and on the three-dimensional computerized images by using the software measurement tool. The direct data were considered as the true values. The paired-samples t-test was used for statistical analysis. The mean differences between the direct and the computerized measurements were mostly less than 0.04 mm and were not significant (P>0.05). Statistical significance among 10 patients was assessed using one-way analysis of variance (P<0.05). The result showed that the 10 patients were considered statistically no significant. Therefore, accurate three-dimensional reproduction of the edentulous dental casts, wax occlusion rims, and jaw relations was achieved. The proposed method enables the visualization of occlusion from different views and would help to meet the demand for the computer-aided design of removable complete dentures.

[Femtosecond pulsed laser ablation of dental hard tissues with numerical control: a roughness and morphology study].

OBJECTIVE: To establish the femtosecond laser experimental platform in vitro for numerical controlled cavity preparation, and to evaluate the roughness quantitatively and observe the microscopic morphology of the cutting surface. METHODS: Enamel and dentin planes were prepared on human third molars. A universal motion controller was used to control the samples to do rectangle wave motion perpendicular to the incident direction of the laser at focus. The surface roughness was observed with confocal laser scanning microscope. RESULTS: Precise ablation of the dental hard tissues can be achieved with the established femtosecond laser numerical control platform. For enamel, the surface roughness of the cavity inside laser scanning line was 7.173 µm at the bottom and 2.675 µm on the wall of the cavity. The surface roughness of the cavity between laser scanning lines was 13.667 µm at the bottom and 33.927 µm on the wall. For dentin, the surface roughness of the cavity bottom was 51.182 µm and 25.629 µm for the wall. Scanning electron microscope images showed no micro-cracks or carbonization on enamel, while carbonization, cracks and a small amount of crystalline particles were observed on dentin. CONCLUSIONS: Precise tooth preparation can be achieved with femtosecond laser numerical control flatform. The surface roughness of cavity wall was less than that of the bottom and can meet the clinical needs. Suitable femtosecond laser output power should be set for different cutting objects, otherwise it may result in tissue damages.

An acoustic emission study on interfacial debonding in composite restorations.

OBJECTIVE: This paper studied in vitro the effect of the C-factor on interfacial debonding during curing of composite restorations using the acoustic emission (AE) technique. Finite element (FE) analyzes were also carried out to evaluate the interfacial stresses caused by shrinkage of the composite resin in restorations with different C-factors. MATERIALS AND METHODS: Twenty extracted third molars were divided into 4 groups of 5. They were cut to form Class-I (Groups 1 and 2) and Class-II (Groups 3 and 4) cavities with different C-factors. The average C-factors of the four groups were 3.37, 2.88, 2.00, and 1.79, respectively. The cavities were then applied with an adhesive and restored with a composite, which was cured by a halogen light for 40 s. A 2-channel AE system was used to monitor the interfacial debonding, caused by shrinkage stress, between the tooth and restoration through an AE sensor attached to the surface of the specimen. Recording of the AE started at the same time as curing of the composite and lasted 10 min. Simplified FE models were used to evaluate the interfacial stresses in restorations with different C-factors, with a thermal load (temperature decrease) being applied to the composite resin to simulate its shrinkage. RESULTS: The mean and standard deviation of the total number of AE events for the four groups were 29.6±15.7, 10.0±5.8, 2.6±1.5, and 2.2±1.3, i.e. the number of AE events increased with an increase in the C-factor. The FE results also showed that, the higher the C-factor of the restoration, the higher the interfacial tensile stress between the tooth and restoration. SIGNIFICANCE: From the results of the AE tests and FE simulations, it can be concluded that, the higher the C-factor, the higher the shrinkage stress and the more likely is interfacial debonding.

[A computer aided design approach of all-ceramics abutment for maxilla central incisor].

OBJECTIVE: To establish the computer aided design (CAD) software platform of individualized abutment for the maxilla central incisor. METHODS: Three-dimentional data of the incisor was collected by scanning and geometric transformation. Data mainly included the occlusal part of the healing abutment, the location carinae of the bedpiece, the occlusal 1/3 part of the artificial gingiva's inner surface, and so on. The all-ceramic crown designed in advanced was "virtual cutback" to get the original data of the abutment's supragingival part. The abutment's in-gum part was designed to simulate the individual natural tooth root. The functions such as "data offset", "bi-rail sweep surface" and "loft surface" were used in the process of CAD. RESULTS: The CAD route of the individualized all-ceramic abutment was set up. The functions and application methods were decided and the complete CAD process was realized. CONCLUSIONS: The software platform was basically set up according to the requests of the dental clinic.