Study on intention to quit smoking and influencing factors among current smokers aged 15 to 69 years in Gansu Province / 中华疾病控制杂志

Objective To understand the intention to quit smoking and its influencing factors among current smokers in Gansu Province, so as to provide scientific basis for tobacco control. Methods A multi-stage sampling method was used to extract current smokers aged 15-69 years, and a face-to-face survey was conducted using the questionnaire on smoking among residents in China. Intention to quit smoking between current smokers with different characteristics was analyzed. Logistic regression was used to explore influencing factors of intention to quit smoking. Results The intention of current smokers to quit smoking in Gansu Province was 16.4% (95% CI:15.5%-17.3%). Multivariate logistic regression analysis showed that current smokers who were in rural areas (OR=1.199, 95% CI:1.022-1.408, P=0.026); family smoking prohibited (OR=1.767, 95% CI: 1.273-2.454, P=0.001), medical staff discouraged smoking within 12 months (OR=1.599, 95% CI:1.359-1.842, P<0.001), visited smoking clinics (OR=3.089, 95% CI:2.031-4.698, P＜001), higher educational level of junior high school, senior high school and college or above (OR=1.383, 95% CI:1.101-1.736; OR=1.627, 95% CI:1.252-2.116; OR=1.374, 95% CI:1.009-1.873, all P<0.05), tobacco hazards knowledge with higher scores of 1-, 3- and 5-6 (OR=1.248, 95% CI:1.030-1.514; OR=1.574, 95% CI:1.289-1.922; OR=2.288, 95% CI:1.879-2.786, all P<0.05) were more likely to quit smoking; furthermore, smokers aged 20-, 30- years or smoking 20-, 30- years had a lower chance of quit smoking (all P<0.05). Conclusions The intention of current smokers to quit smoking in Gansu province is generally not high. In the future, knowledge of tobacco hazards should be further promoted, medical staff should provide more smoking cessation services during the treatment process, and more smoking cessation clinics should be established.

Accuracy evaluation of a new three-dimensional reproduction method of edentulous dental casts, and wax occlusion rims with jaw relation / 国际口腔科学杂志·英文版

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.

Effects of fluence and scanning velocity on the ablation efficiency of dentin and enamel by femtosecond laser / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To measure the effect of laser fluence and scanning velocity on ablation efficiency of enamel and dentin.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSIONS</b>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.</p>

Preliminary evaluation of clinical effect of computer aided design and computer aided manufacture zirconia crown / 中华口腔医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>In all the prosthesis we evaluated during the 24 months, no fracture was found. Contact wear of crowns varies according to different antagonist teeth.</p><p><b>CONCLUSIONS</b>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.</p>

Initial evolution research for design and process accuracy of one type of domestic computer aided design soft and computer aided manufacture / 中华口腔医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>The design and machining precision of this domestic CAD/CAM system is at the same level of those comparable foreign products.</p>

Femtosecond pulsed laser ablation of dental hard tissues with numerical control: a roughness and morphology study / 中华口腔医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

A computer aided design approach of all-ceramics abutment for maxilla central incisor / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish the computer aided design (CAD) software platform of individualized abutment for the maxilla central incisor.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>The software platform was basically set up according to the requests of the dental clinic.</p>

Computer aided design and rapid manufacturing of removable partial denture frameworks / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To introduce a method of digital modeling and fabricating removable partial denture (RPD) frameworks using self-developed software for RPD design and rapid manufacturing system.</p><p><b>METHODS</b>The three-dimensional data of two partially dentate dental casts were obtained using a three-dimensional crossing section scanner. Self-developed software package for RPD design was used to decide the path of insertion and to design different components of RPD frameworks. The components included occlusal rest, clasp, lingual bar, polymeric retention framework and maxillary major connector. The design procedure for the components was as following: first, determine the outline of the component. Second, build the tissue surface of the component using the scanned data within the outline. Third, preset cross section was used to produce the polished surface. Finally, different RPD components were modeled respectively and connected by minor connectors to form an integrated RPD framework. The finished data were imported into a self-developed selective laser melting (SLM) machine and metal frameworks were fabricated directly.</p><p><b>RESULTS</b>RPD frameworks for the two scanned dental casts were modeled with this self-developed program and metal RPD frameworks were successfully fabricated using SLM method. The finished metal frameworks fit well on the plaster models.</p><p><b>CONCLUSIONS</b>The self-developed computer aided design and computer aided manufacture (CAD-CAM) system for RPD design and fabrication has completely independent intellectual property rights. It provides a new method of manufacturing metal RPD frameworks.</p>

Electronic surveying of digital partially dentate casts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To develop a method of surveying the digitalized partially dentate cast in order to accomplish computer aided design (CAD) of removable partial denture (RPD) frameworks.</p><p><b>METHODS</b>The stone cast of a partially dentate patient was scanned using a three-dimensional laser scanner. Points on the surface of the digitalized cast, termed as a "point cloud", were obtained. The point cloud was then imported into self-developed Tanglong software to sample and uniform. New module of identifying the surveying lines was specially written in Tanglong using C++. A straight line was created in the center of the cloud point. Then the cloud point surrounding the straight line was divided into many parts. Local coordinates were established to indicate the information of angle and distance of every point to the straight line. Surveying lines were produced step by step electronically by identifying the closest and farthest points relative to the straight line and then connected together. Different surveying lines were obtained by adjusting the angle of the straight line. After the surveying lines were decided, the undercut areas could be marked and the depth of undercut was calculated automatically. The blockout of the undercuts could also be achieved by moving the location of the point cloud in undercut area.</p><p><b>RESULTS</b>Survey lines of digitalized partially dentate casts were generated in computer. The undercut area and its depth were identified and the undercut could be blocked out. The shape of survey lines on the digitalized casts was similar to that on the physical casts drawn using traditional method.</p><p><b>CONCLUSIONS</b>The new module in Tanglong software was developed specifically for surveying partially dentate casts. It had a user-friendly interface with the easy-to-understand menus. The success of surveying dental casts digitally would make it possible to CAD of RPD frameworks.</p>

Experimental study on bond strength of machinable composite resin and dentin with three kinds of resin cements / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the shear and microtensile bond strength between a newly developed dental machinable composite resin (polymethylmetacrylate/nano SiO2-ZrO2, PNSZ) and dentin cemented using three resin luting systems and to select the most suitable one.</p><p><b>METHODS</b>The shear and microtensile bond strength between the machinable composite resin and dentin cemented using three resin luting systems (Group A:RelyX ARC, Group B:Panavia-F,Group C:Variolink II) were tested. The broken specimens were observed with a stereomicroscope (x 50) to compare their failure modes. RESULTS; In the shear tests, no significant difference was found in bond strength among Group A [ (14. 07 +/- 4. 67) MPa] ,Group B[ (13.17 +/- 4. 63) MPa] and Group C [ ( 12. 10 +/- 2.18) MPa] (P > 0.05) . In the microtensile tests, no significant difference was found in bond strength among Group A [(11.49 +/- 4.90) MPa],Group B[(9.66 +/- 4.15) MPa].and Group C[(10.11 +/- 4.20) MPa](P > 0. 05).The failure modes of all the three resin cements were predominantly adhesive failures at the dentin/cement interface.</p><p><b>CONCLUSIONS</b>The three types of resin cements showed similar results in bond strength between the dental machinable composite resin and dentin. Bonding at the resin/cement interface was stronger than that at the dentin/cement interface.</p>

The identification of electronic surveying lines on 3-D digital models of dentition defects / 中华口腔医学杂志

<p><b>OBJECTIVES</b>To develop a mathematical algorithm and a software package for the process of electronically surveying a scanned point cloud cast. To provide a principal premise to the subsequent computer aided design and computer aided manufacture (CAD/CAM) of removable partial denture framework, and to provide a method to improve quality control in the dental laboratory.</p><p><b>METHODS</b>Point cloud data of a partially edentulous cast, a mandibular Kennedy Class II Modification 2 arch, was captured using an optical scanning system with projective grating and high-resolution digital camera. Using commercial CAD/CAM software system (Geomagic Studio 6), this point cloud data was processed and the 3-D digital model of partially edentulous cast was reconstructed. From a suggested surveying angle the contour points of height were identified, and then the digital surveying lines were traced using Projection and Contour Extraction software package. The depth of undercut was measured and defined to determine the clasp termination of retainer.</p><p><b>RESULTS</b>Electronic surveying line of 3-D digital dentition defect model was achieved. Digital surveying line defined the cast into undercut and non-undercut areas. Different virtualized paths of insertion could be automatically suggested when the cast was surveyed and analyzed from different angles. The depth of undercut was automatically measured and the retentive clasp termination was determined.</p><p><b>CONCLUSIONS</b>The mathematical algorithm and the software package in this study can be used to survey and analyze 3-D digital models of dentition defects, and to identify an electronic surveying line.</p>

Three-dimensional computer aided design for individualized post-and-core restoration / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To develop a method of three-dimensional computer aided design (CAD) of post-and-core restoration.</p><p><b>METHODS</b>Two plaster casts with extracted natural teeth were used in this study. The extracted teeth were prepared and scanned using tomography method to obtain three-dimensional digitalized models. According to the basic rules of post-and-core design, posts, cores and cavity surfaces of the teeth were designed using the tools for processing point clouds, curves and surfaces on the forward engineering software of Tanglong prosthodontic system. Then three-dimensional figures of the final restorations were corrected according to the configurations of anterior teeth, premolars and molars respectively.</p><p><b>RESULTS</b>Computer aided design of 14 post-and-core restorations were finished, and good fitness between the restoration and the three-dimensional digital models were obtained. Appropriate retention forms and enough spaces for the full crown restorations can be obtained through this method.</p><p><b>CONCLUSIONS</b>The CAD of three-dimensional figures of the post-and-core restorations can fulfill clinical requirements. Therefore they can be used in computer-aided manufacture (CAM) of post-and-core restorations.</p>

Microstructure and mechanical properties of laser melted rapidly solidified forming pure titanium specimens / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the microstructure and mechanical properties of pure titanium specimens fabricated using laser melted rapidly solidified forming (LMRSF) and casting, and to provide scientific evidence for the new method of laser rapid forming in prosthodontic field.</p><p><b>METHODS</b>Six pure titanium specimens were fabricated from pure titanium powder using LMRSF technology, and six pure titanium casting specimens were used as the controls. The tensile strength was measured and the microstructures and natural fracture surface of the pure titanium specimens made in two different ways were observed.</p><p><b>RESULTS</b>Compared to that in the casting specimen, the microstructure of the LMRSF titanium specimens was denser and acicular structure distributed more uniformly. The tensile strength and the microhardness of the pure titanium specimens were (510.0 +/- 21.2) MPa and (201.4 +/- 14.5) MPa respectively, which were much higher than those of the dental pure titanium castings [(425.0 +/- 35.1) MPa and (186.5 +/- 9.5) MPa] (P < 0.01).</p><p><b>CONCLUSIONS</b>The microstructure and mechanical properties of the pure titanium specimens fabricated using LMRSF are better than that of the pure titanium castings. Therefore, the LMRSF will provide titanium framework with better quality for removable dental restoration.</p>

Research and development of computer aided design and rapid prototyping technology for complete denture / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explore a computer aided design (CAD) and rapid prototyping (RP) approach for fabrication of complete denture and to develop relevant programs for implementing it.</p><p><b>METHODS</b>Automatic crossing section scanner was used to scan artificial teeth and 3D graphic database of artificial teeth that could be aligned with parameters was established. A 3D laser scanner was used to scan upper and lower edentulous jaw casts and rims made in clinic. The vertical and horizontal relations were recorded before scanning with a patient instrument. Based on Imageware 11, tooth-arrangement curves, coordinate system, and landmark points for positioning were created, and construction cure and shape-controlling curve for base plate were constructed as well. Three-dimensional integrated design of complete denture, including artificial tooth automatic arrangement, aesthetic and individualized design of base plate, and artificial gingival, were finished. The programs were developed following the approach and the CAD platform was established. The virtual molds of complete dentures were constructed according to the above data in design and RP technology was used to make the plaster molds. Finally, the teeth were inserted and the complete denture was finished by dental technician.</p><p><b>RESULTS</b>The approach for the complete denture CAD/RP was confirmed and the CAD software platform was developed. A complete denture was manufactured.</p><p><b>CONCLUSIONS</b>The rules for complete denture in textbooks were expressed in design process with the CAD program developed by researcher. The 3D data of rims were utilized in design so that the digital, intelligentized and individualized design and manufacture process for complete denture was implemented.</p>

Computer aided design for fixed partial denture framework based on reverse engineering technology / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explore a computer aided design (CAD) route for the framework of domestic fixed partial denture (FPD) and confirm the suitable method of 3-D CAD.</p><p><b>METHODS</b>The working area of a dentition model was scanned with a 3-D mechanical scanner. Using the reverse engineering (RE) software, margin and border curves were extracted and several reference curves were created to ensure the dimension and location of pontic framework that was taken from the standard database. The shoulder parts of the retainers were created after axial surfaces constructed. The connecting areas, axial line and curving surface of the framework connector were finally created.</p><p><b>RESULTS</b>The framework of a three-unit FPD was designed with RE technology, which showed smooth surfaces and continuous contours.</p><p><b>CONCLUSIONS</b>The design route is practical. The result of this study is significant in theory and practice, which will provide a reference for establishing the computer aided design/computer aided manufacture (CAD/CAM) system of domestic FPD.</p>

Computer aided design and computer aided manufacture of sacrificial pattern of removable partial denture framework / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To introduce a method applied in computer aided design and computer aided manufacture (CAD-CAM) of removable partial denture framework for rehabilitating edentulous arch of Kennedy Class II and found a basis for this project.</p><p><b>METHODS</b>Point cloud data of dental stone model was obtained by laser scanning. The following processes were made: drawing framework outline on the reconstructed triangle mesh model, picking up and processing its inner side data as the data of tissue surface, shelling it for 3-D model of framework, and transferring the data to rapid prototyping equipment for manufacture.</p><p><b>RESULTS</b>3-D model of the removable partial denture framework was preliminarily accomplished. The resin framework used as a sacrificial pattern was manufactured with the rapid prototyping equipment. The fit between resin framework and plaster model was good.</p><p><b>CONCLUSIONS</b>This method, as an integrated procedure including data acquisition, 3-D computer modeling and fabrication by rapid prototyping, is feasible to implement CAD-CAM of removable partial denture framework.</p>

The measurement of cutting forces in full crown preparation with three-dimensional transducer unit / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To measure the cutting forces applied by clinicians during preparing full crown and to provide basic data for the training of dentistry in a virtual reality.</p><p><b>METHODS</b>Each of six prosthodontists and six dental students prepared three extracted maxillary premolars. The cutting forces were measured with a three-dimensional transducer unit. Differences in cutting time and forces between groups were analyzed with independent-samples t-test.</p><p><b>RESULTS</b>The cutting forces varied in the range from 0.10 N to 4.90 N. The average cutting force (1.71 N) of four axial surfaces was higher than that (0.45 N) of occlusal surface (including functional cusp inclines) (P < 0.01). The cutting time by prosthodontists was shorter than that by the students (P < 0.05). Moreover, the vertical component of the cutting force was higher than the horizontal one (P < 0.01).</p><p><b>CONCLUSIONS</b>The magnitude of cutting forces could be greatly influenced by the motion direction and tendency of the handpiece. The data on cutting forces might serve as the foundation of cutting simulation algorithm for training in a virtual reality.</p>

Application of functionally generated path technique in computer-aided-design modeling of occlusal surface of full crown / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To apply the functionally generated path (FGP) technique for modeling the occlusal surface of a computer-aided-design (CAD) posterior full crown to obtain anatomic morphology.</p><p><b>METHODS</b>A patient with defected left mandibular first molar was employed. After tooth preparation and impression making, the gypsum working cast and die were scanned with a digitized mechanical scanner and the surface data was acquired. The interocclusal records at intercuspal position (ICP) and FGP were made in the patient's mouth. These records were placed on the working cast and their surfaces were scanned. In the process of the computer-aided designing full crown, the cusps and fossae of the occlusal surfaces were accurately modified according to the digitized information of ICP and FGP interocclusal records.</p><p><b>RESULTS</b>A full crown was designed and the occlusal morphology of the restoration was adapted to dynamic occlusion as well as static occlusion.</p><p><b>CONCLUSIONS</b>The FGP technique was practical for the CAD of full crown and could avoid potential occlusal interferences with opposing teeth during function.</p>

Establishment of artificial-tooth three-dimensional coordinates based on dental anatomic concepts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish a three-dimensional (3-D) descartes coordinates of artificial teeth based on concepts of dental anatomy and to obtain their geometric parameters.</p><p><b>METHODS</b>Using the 3-D reverse engineering software, artificial-tooth coordinates were defined based on their anatomic concepts which included long axis, mesiodistal and buccolingual directions, and occlusal plane. Some geometric parameters, such as mesiodistal and buccolingual dimensions, height and obliquity of dental cusp, were measured.</p><p><b>RESULTS</b>The 3-D coordinates of 28 artificial teeth were established and geometric parameters in coordinates were obtained.</p><p><b>CONCLUSIONS</b>The definition of artificial-tooth coordinates can be made using mathematic language based on dental anatomic concepts, which is the basal work of complete denture computer-aided design (CAD).</p>

The inlay computer aided design based on reverse engineering technology / 中华口腔医学杂志

<p><b>OBJECTIVE</b>This study was to explore a CAD method for constructing occlusal and proximal surfaces of inlays using reverse engineering (RE) software and to develop a CAD software for the inlay fabrication.</p><p><b>METHODS</b>The dentition model of a volunteer with individual normal occlusion was scanned with a 3D mechanical scanner. The scanned objects were prepared teeth with G. V. Black class I, class II and class VI (MOD) cavities, neighbor teeth, intercuspal position (ICP) record, and functional bite record (or functional generate path, FGP). Inlays were constructed based on RE technology using the database of Chinese normal teeth.</p><p><b>RESULTS</b>The technique guideline of inlay CAD was developed based on RE softwares. Inlays designed with CAD technique showed smooth and continuous contours. The occlusal and proximal contacts of inlay met physiologic demands.</p><p><b>CONCLUSIONS</b>It is a feasible method to develop a CAD software for inlay fabrication based on RE software.</p>