Metals in paints on chopsticks: Solubilization in simulated saliva, gastric, and food solutions and implication for human health.

Paints are often used on chopsticks, however, a paucity of studies has assessed metals in the paints and the associated health risk. In this study, total Pb, Cd, Cr, Co, and Ni concentrations in paints were assessed for 72 wood and 29 stainless steel chopsticks with different colors while metal solubilization from paints in simulated saliva, 0.07 M HCl, and 1% citric acid solutions was measured for 9 samples having total Pb > 90 mg kg-1, representing exposure scenarios of mouthing, incidental paint ingestion, and metal migration in food. Results showed that Pb (0.12-500,000 mg kg-1), Cd (0.002-120,000 mg kg-1), Cr (2.2-8400 mg kg-1), Co (0.004-2600 mg kg-1), and Ni (0.10-150,000 mg kg-1) concentrations varied considerably among paint samples. Most samples showed low metal concentrations, however, high metal concentrations were observed in red and green paints on stainless steel chopsticks, while paints on wood chopsticks showed lower metal concentrations. Estimation of daily metal intakes incorporating metal solubilization data in saliva, 0.07 M HCl, and 1% citric acid solutions suggested that the health risk via saliva contact was negligible, while unacceptable health risk was observed for Pb and Cd via their solubilization in 0.07 M HCl and 1% citric acid solutions from paints with high Pb and Cd concentrations. To avoid Pb and Cd exposure, use of metal-based paints on chopsticks should be banned, particularly in countries where food is regularly consumed with chopsticks.

Physical properties and hydration behavior of a fast-setting bioceramic endodontic material.

BACKGROUND: To investigate the physical properties and the hydration behaviour of the fast-setting bioceramic iRoot FS Fast Set Root Repair Material (iRoot FS) and three other endodontic cements. METHODS: iRoot FS, Endosequence Root Repair Material Putty (ERRM Putty), gray and white mineral trioxide aggregate (G-MTA & W-MTA), and intermediate restorative material (IRM) were evaluated. The setting time was measured using ANSI/ADA standards. Microhardness was evaluated using the Vickers indentation test. Compressive strength and porosity were investigated at 7 and 28 days. Differential scanning calorimetry (DSC) was employed for the hydration test. RESULTS: iRoot FS had the shortest setting time of the four bioceramic cements (p < .001). The microhardness values of iRoot FS, ERRM Putty and MTA increased at different rates over the 28 days period. At day one, ERRM Putty had the lowest microhardness of the bioceramic cements (p < .001), but reached the same level as MTA at 4, 7 and 28 days. The microhardness of iRoot FS was lower than that of W-MTA at 7 and 28 days (p < .05). The porosity of the materials did not change after 7 days (p < .05). The compressive strength values at 28 days were significantly greater for all bioceramic groups compared to those at 7 days (p < .01). ERRM Putty had the highest compressive strength and the lowest porosity of the evaluated bioceramic cements (p < .05), followed by iRoot FS, W-MTA, and G-MTA, respectively. DSC showed that iRoot FS hydrated fastest, inducing an intense exothermic reaction. The ERRM Putty did not demonstrate a clear exothermic peak during the isothermal calorimetry test. CONCLUSIONS: iRoot FS had a faster setting time and hydrating process than the other bioceramic cements tested. The mechanical properties of iRoot FS, G-MTA and W-MTA were relatively similar.

A generalizable sensing platform based on molecularly imprinted polymer-aptamer double recognition and nanoenzyme assisted photoelectrochemical-colorimetric dual-mode detection.

Developing highly sensitive and selective methods that incorporate specific recognition elements is crucial for detecting small molecules because of the limited availability of small molecule antibodies and the challenges in obtaining sensitive signals. In this study, a generalizable photoelectrochemical-colorimetric dual-mode sensing platform was constructed based on the synergistic effects of a molecularly imprinted polymer (MIP)-aptamer sandwich structure and nanoenzymes. The MIP functionalized peroxidase-like Fe3O4 (Fe3O4@MIPs) and alkaline phosphatase mimic Zr-MOF labeled aptamer (Zr-mof@Apt) were used as the recognition elements. By selectively accumulating dibutyl phthalate (DBP), a small molecule target model, on Fe3O4@MIPs, the formation of Zr-MOF@Apt-DBP- Fe3O4@MIPs sandwich structure was triggered. Fe3O4@MIPs oxidized TMB to form blue-colored oxTMB. However, upon selective accumulation of DBP, the catalytic activity of Fe3O4@MIPs was inhibited, resulting in a lighter color that was detectable by the colorimetric method. Additionally, Zr-mof@Apt effectively catalyzed the hydrolysis of L-Ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AAPS), generating ascorbic acid (AA) that could neutralize the photogenerated holes to decrease the photocurrent signals for PEC sensing and reduce oxTMB for colorimetric testing. The dual-mode platform showed strong linearity for different concentrations of DBP from 1.0 pM to 10 µM (PEC) and 0.1 nM to 0.5 µM (colorimetry). The detection limits were 0.263 nM (PEC) and 30.1 nM (colorimetry) (S/N = 3), respectively. The integration of dual-signal measurement mode and sandwich recognition strategy provided a sensitive and accurate platform for the detection of small molecules.

Recent advances in the pathogenesis and prevention strategies of dental calculus.

Dental calculus severely affects the oral health of humans and animal pets. Calculus deposition affects the gingival appearance and causes inflammation. Failure to remove dental calculus from the dentition results in oral diseases such as periodontitis. Apart from adversely affecting oral health, some systemic diseases are closely related to dental calculus deposition. Hence, identifying the mechanisms of dental calculus formation helps protect oral and systemic health. A plethora of biological and physicochemical factors contribute to the physiological equilibrium in the oral cavity. Bacteria are an important part of the equation. Calculus formation commences when the bacterial equilibrium is broken. Bacteria accumulate locally and form biofilms on the tooth surface. The bacteria promote increases in local calcium and phosphorus concentrations, which triggers biomineralization and the development of dental calculus. Current treatments only help to relieve the symptoms caused by calculus deposition. These symptoms are prone to relapse if calculus removal is not under control. There is a need for a treatment regime that combines short-term and long-term goals in addressing calculus formation. The present review introduces the mechanisms of dental calculus formation, influencing factors, and the relationship between dental calculus and several systemic diseases. This is followed by the presentation of a conceptual solution for improving existing treatment strategies and minimizing recurrence.

A meta-analysis of the incidence and risk of skin toxicity with nab-paclitaxel and paclitaxel in cancer treatment.

BACKGROUND: Skin toxicity of varying severity occurs mostly during various courses of chemotherapy. In clinical trials and practice, we have found that both nab-paclitaxel and paclitaxel cause side effects such as rash and pruritus. To further clarify the incidence of rash and pruritus in both, we conducted the present study by a systematic evaluation, the results of which can be used to guide clinical dosing choices. METHODS: An electrical search was performed on randomized controlled research trials of nab-paclitaxel and paclitaxel for the treatment of malignancies. The necessary data were extracted, integrated, and analyzed from the included studies by systematic evaluation and meta-analysis, depending on the study design. Further subgroup analyses were performed to explore the incidence of rash and pruritus in nab-paclitaxel and paclitaxel. RESULTS: Eleven studies with a total of 971 patients with malignancy were included. Four studies were application of single-agent nab-paclitaxel compared with paclitaxel, and seven studies were comparative chemotherapy drug combinations. The incidence of rash was higher in all grades of nab-paclitaxel than that in paclitaxel (OR=1.39, CI 95% [1.18-1.62]); the incidence of rash was higher in lower grades of paclitaxel than that in solvent-based paclitaxel (OR=1.31, CI 95% [1.11-1.53]); the incidence of rash was higher in all grades in the single-agent application comparison. The incidence of rash was higher in nab-paclitaxel than that in paclitaxel (OR=1.81, CI 95% [1.26-2.59]); there was no significant difference in the incidence of pruritus between nab-paclitaxel and paclitaxel (OR=1.19, CI 95% [0.88-1.61]). CONCLUSION: In comparison with paclitaxel, nab-paclitaxel significantly increased the risk of a teething rash. There was a significant risk correlation between nab-paclitaxel and teething rash. Early prevention, identification, and treatment of rash could significantly improve patient's quality of life and optimize their clinical survival.

Reduced dietary Ca, Cu, Zn, Mn, and Mg bioavailability but increased Fe bioavailability with polyethylene microplastic ingestion in a mouse model: Changes in intestinal permeability and gut metabolites.

Microplastics emerge as a new environmental and human health crisis. Minimal research exists on effects of microplastic ingestion on the oral bioavailability of minerals (Fe, Ca, Cu, Zn, Mn, and Mg) in the gastrointestinal tract via impacting intestinal permeability, mineral transcellular transporters, and gut metabolites. Here, mice were exposed to polyethylene spheres of 30 and 200 µm (PE-30 and PE-200) in diet (2, 20, and 200 µg PE g-1) for 35 d to determine the microplastic effects on mineral oral bioavailability. Results showed that for mice fed diet amended with PE-30 and PE-200 at 2-200 µg g-1, Ca, Cu, Zn, Mn, and Mg concentrations in the small intestine tissue were 43.3-68.8 %, 28.6-52.4 %, 19.3-27.1 %, 12.9-29.9 %, and 10.2-22.4 % lower compared to control mice, suggesting hampered bioavailability of these minerals. In addition, Ca and Mg concentrations in mouse femur were 10.6 % and 11.0 % lower with PE-200 at 200 µg g-1. In contrast, Fe bioavailability was elevated, as suggested by significantly (p < 0.05) higher Fe concentration in the intestine tissue of mice exposed to PE-200 than control mice (157-180 vs. 115 ± 7.58 µg Fe g-1) and significantly (p < 0.05) higher Fe concentrations in liver and kidney with PE-30 and PE-200 at 200 µg g-1. Following PE-200 exposure at 200 µg g-1, genes coding for duodenal expression of tight junction proteins (e.g., claudin 4, occludin, zona occludins 1, and cingulin) were significantly up-regulated, possibility weakening intestinal permeability to Ca, Cu, Zn, Mn, and Mg ions. The elevated Fe bioavailability was possibly related to microplastic-induced greater abundances of small peptides in the intestinal tract, which inhibited Fe precipitation and elevated Fe solubility. Results showed that microplastic ingestion may cause Ca, Cu, Zn, Mn, and Mg deficiency but Fe overload via altering intestinal permeability and gut metabolites, posing a threat to human nutrition health.

Microplastics affect arsenic bioavailability by altering gut microbiota and metabolites in a mouse model.

Microplastics exposure is a new human health crisis. Although progress in understanding health effects of microplastic exposure has been made, microplastic impacts on absorption of co-exposure toxic pollutants such as arsenic (As), i.e., oral bioavailability, remain unclear. Microplastic ingestion may interfere As biotransformation, gut microbiota, and/or gut metabolites, thereby affecting As oral bioavailability. Here, mice were exposed to arsenate (6 µg As g-1) alone and in combination with polyethylene particles of 30 and 200 µm (PE-30 and PE-200 having surface area of 2.17 × 103 and 3.23 × 102 cm2 g-1) in diet (2, 20, and 200 µg PE g-1) to determine the influence of microplastic co-ingestion on arsenic (As) oral bioavailability. By determining the percentage of cumulative As consumption recovered in urine of mice, As oral bioavailability increased significantly (P < 0.05) from 72.0 ± 5.41% to 89.7 ± 6.33% with PE-30 at 200 µg PE g-1 rather than with PE-200 at 2, 20, and 200 µg PE g-1 (58.5 ± 19.0%, 72.3 ± 6.28%, and 69.2 ± 17.8%). Both PE-30 and PE-200 exerted limited effects on pre- and post-absorption As biotransformation in intestinal content, intestine tissue, feces, and urine. They affected gut microbiota dose-dependently, with lower exposure concentrations having more pronounced effects. Consistent with the PE-30-specific As oral bioavailability increase, PE exposure significantly up-regulated gut metabolite expression, and PE-30 exerted greater effects than PE-200, suggesting that gut metabolite changes may contribute to As oral bioavailability increase. This was supported by 1.58-4.07-fold higher As solubility in the presence of up-regulated metabolites (e.g., amino acid derivatives, organic acids, and pyrimidines and purines) in the intestinal tract assessed by an in vitro assay. Our results suggested that microplastic exposure especially smaller particles may exacerbate the oral bioavailability of As, providing a new angle to understand health effects of microplastics.

The accuracy and learning curve of active and passive dynamic navigation-guided dental implant surgery: An in vitro study.

OBJECTIVES: Infrared dynamic navigation systems can be categorized into active and passive based on whether the surgical instruments can emit or only reflect light. This in vitro study aimed to compare the accuracy of implant placement and the learning curve of both active and passive dynamic navigation systems, using different registration methods. METHODS: Implants (n = 704) were placed in 64 sets of models and divided into active (Yizhime, DCARER, Suzhou, China) and passive (Iris-Clinic, EPED, Kaohsiung, China) dynamic navigation groups. Both marker point-based registration (M-PBR) and feature point-based registration (F-PBR) were employed for the two groups. Based on preoperative and postoperative cone-beam computed tomography imaging, the coronal, midpoint, apical, and angular deviations were analyzed from 2D and 3D views. The operation time was recorded for each group. RESULTS: The active dynamic navigation group exhibited significantly higher accuracy than the passive dynamic navigation group (angular deviation, 4.13 ± 2.39° versus 4.62 ± 3.32°; coronal global deviation, 1.48 ± 0.60 versus 1.86 ± 1.12 mm; apical global deviation, 1.75 ± 0.81 versus 2.20 ± 1.68 mm, respectively). Significant interaction effects were observed for both registration methods and four quadrants with different dynamic navigation systems. Learning curves for the two dynamic navigation groups approached each other after 12 procedures, and finally converged after 27 procedures. CONCLUSIONS: The accuracy of active dynamic navigation system was superior to that of passive dynamic navigation system. Different combinations of dynamic navigation systems, registration methods, and implanted quadrants displayed various interactions. CLINICAL SIGNIFICANCE: Our findings could provide guidance for surgeons in choosing an appropriate navigation system in various implant surgeries. Furthermore, the time required by surgeons to master the technique was calculated. Nevertheless, there are certain limitations in this in vitro study, and therefore further research is required.

A mussel glue-inspired monomer-etchant cocktail for improving dentine bonding.

OBJECTIVES: The humid oral environment adversely affects the interaction between a functionalised primer and dentine collagen after acid-etching. Robust adhesion of marine mussels to their wet substrates instigates the quest for a strategy that improves the longevity of resin-dentine bonds. In the present study, an etching strategy based on the incorporation of biomimetic dopamine methacrylamide (DMA) as a functionalised primer into phosphoric acid etchant was developed. The mechanism and effect of this DMA-containing acid-etching strategy on bond durability were examined. METHODS: Etchants with different concentrations of DMA (1, 3 or 5 mM) were formulated and tested for their demineralisation efficacy. The interaction between DMA and dentine collagen, the effect of DMA on collagen stability and the collagenase inhibition capacity of the DMA-containing etchants were evaluated. The effectiveness of this new etching strategy on resin-dentine bond durability was investigated. RESULTS: All etchants were capable of demineralising dentine and exposing the collagen matrix. The latter strongly integrated with DMA via covalent bond, hydrogen bond and Van der Waals' forces. These interactions significantly improve collagen stability and inhibited collagenase activity. Application of the etchant containing 5 mM DMA achieved the most durable bonding interface. CONCLUSION: Dopamine methacrylamide interacts with dentine collagen in a humid environment and improves collagen stability. The monomer effectively inactivates collagenase activity. Acid-etching with 5 mM DMA-containing phosphoric acid has the potential to prolong the longevity of bonded dental restorations without compromising clinical operation time. CLINICAL SIGNIFICANCE: The use of 5 mM dopamine methacrylamide-containing phosphoric acid for etching dentine does not require an additional clinical step and has potential to improve the adhesive performance of bonded dental restorations.

Reconstruction of large segmental bone defects in rabbit using the Masquelet technique with α-calcium sulfate hemihydrate.

BACKGROUND: Large segmental bone defects can be repaired using the Masquelet technique in conjunction with autologous cancellous bone (ACB). However, ACB harvesting is severely restricted. α-calcium sulfate hemihydrate (α-CSH) is an outstanding bone substitute due to its easy availability, excellent biocompatibility, biodegradability, and osteoconductivity. However, the resorption rate of α-CSH is too fast to match the rate of new bone formation. The objective of this study was to investigate the bone repair capacity of the Masquelet technique in conjunction with isolated α-CSH or an α-CSH/ACB mix in a rabbit critical-sized defect model. METHODS: The rabbits (n = 28) were randomized into four groups: sham, isolated α-CSH, α-CSH/ACB mix, and isolated ACB group. A 15-mm critical-sized defect was established in the left radius, followed by filling with polymethyl methacrylate spacer. Six weeks after the first operation, the spacers were removed and the membranous tubes were grafted with isolated α-CSH, isolated ACB, α-CSH/ACB mix, or none. Twelve weeks later, the outcomes were evaluated by manual assessment, radiography, and spiral-CT. The histopathological and morphological changes were examined by H&E staining. The levels of alkaline phosphatase and osteocalcin were analyzed by immunohistochemistry and immunofluorescence staining. RESULTS: Our results suggest that the bone repair capacity of the α-CSH/ACB mix group was similar to the isolated ACB group, while the isolated α-CSH group was significantly decreased compared to the isolated ACB group. CONCLUSION: These results highlighted a promising strategy in the healing of large segmental bone defect with the Masquelet technique in conjunction with an α-CSH/ACB mix (1:1, w/w) as they possessed the combined effects of sufficient supply and low resorption.

Effect of phosphate amendment on relative bioavailability and bioaccessibility of lead and arsenic in contaminated soils.

Hand-to-mouth activity is an important pathway for children's exposure to contaminated soils, which is often co-contaminated by Pb and As in mining and smelting sites. To reduce soil Pb risk to humans by oral exposure, phosphate amendments have been used to reduce Pb relative bioavailability (RBA), but its efficiency has not been investigated using validated in vitro assays nor its influence on As-RBA. Here, 5 contaminated soils (A-E) were amended with 0.5% phosphoric acid (PA) to study its effect on Pb- and As- RBA using a newly-developed mouse kidney model and bioaccessibility using 4 in vitro assays including UBM, SBRC, IVG, and PBET. Based on the mouse kidney model, Pb-RBA in PA-amended soils decreased from 14.2-62.5% to 10.1-29.8%. In contrast, As-RBA decreased from 26.5% to 15.9% in soil B but increased from 27.5 to 41.2% in soil D, with changes being insignificant in 3 other soils (35.8-58.8 to 28.1-61.1%). When assessing Pb bioaccessibility in PA-amended soils, decreased bioaccessibility were found using PBET and SBRC. For As, its bioaccessibility increased in PA-amended soils, inconsistent with in vivo data. Our results shed light on the importance of method selection to assess risk in Pb- and As-contaminated soils amended with phosphate.

[Influence of different designs of marginal preparation on stress distribution in the mandibular premolar restored with endocrown].

OBJECTIVE: To evaluate the effect of different designs of marginal preparation on stress distribution in the mandibular premolar restored with endocrown using three-dimensional finite element method. METHODS: Four models with different designs of marginal preparation, including the flat margin, 90° shoulder, 135° shoulder and chamfer shoulder, were established to imitate mandibular first premolar restored with endocrown. A load of 100 N was applied to the intersection of the long axis and the occlusal surface, either parallel or with an angle of 45° to the long axis of the tooth. The maximum values of Von Mises stress and the stress distribution around the cervical region of the abutment and the endocrown with different designs of marginal preparation were analyzed. RESULTS: The load parallel to the long axis of the tooth caused obvious stress concentration in the lingual portions of both the cervical region of the tooth tissue and the restoration. The stress distribution characteristics on the cervical region of the models with a flat margin and a 90° shoulder were more uniform than those in the models with a 135° shoulder and chamfer shoulder. Loading at 45° to the long axis caused stress concentration mainly on the buccal portion of the cervical region, and the model with a flat margin showed the most favorable stress distribution patterns with a greater maximum Von Mises stress under this circumstance than that with a parallel loading. Irrespective of the loading direction, the stress value was the lowest in the flat margin model, where the stress value in the cervical region of the endocrown was greater than that in the counterpart of the tooth tissue. The stress level on the enamel was higher than that on the dentin nearby in the flat margin model. CONCLUSIONS: From the stress distribution point of view, endocrowns with flat margin followed by a 90° shoulder are recommended.

[Three-dimensional accuracy of plaster casts obtained using three impression materials].

OBJECTIVE: To evaluate the accuracy of 3 impression materials in reproductions of simian dental arches using a 3-dimensional optical digitizer. METHODS: Two simian dental arches were prepared as the master models. Impressions were made for stone casts using three impression materials, including alginate impression materials, C-silicone materials and Impregum-Penta polyether rubber. Five plaster replication models for each master model, as well as for each impression materials were made. The master models and the casts were digitized using a 3-dimensional optical scanner and digitizer. The images of each plaster cast and its original master model were superimposed to obtain the setting cross-section volume of the dental crown. The ratios of the plaster cast volume change and discrepancy distribution patterns were analyzed. RESULTS: Compared with the volume of the master models, the discrepancies of the plaster casts volume were -5.84%, -3.21%, and -0.63% for alginate impression materials, silicone materials and Impregum-Penta polyether rubber, respectively. The discrepancy between the master models and casts from alginate material was statistically significant (P<0.05), but not for silicone materials or Impregum-Penta polyether rubber. Maximal deviation of image fitting was located in the cervix and the gingival areas. CONCLUSION: The volumes of all the plaster casts from the 3 impression material are smaller than that of the master model. Impregum-Penta polyether rubber allows the most precise and silicone material the relatively accurate reproduction of the denture model, while alginate can not. The major error areas are in the dental cervix and gingival region.

Hydroxyapatite crystals biologically inspired on titanium by using an organic template based on the copolymer of acrylic acid and itaconic acid.

Hydroxyapatite coating on metal implants is an effective method to enhance bioactive properties of the metal surface. We report here a method to coat the Ti-6Al-4V alloy with hydroxyapatite crystals. After alkaline/heat treatment, the spontaneous growth of organoapatite on titanium alloy surface involves sequential preadsorption of titanium isopropoxide (TIPO) and the copolymer of acrylic acid and itaconic acid on the metal, followed by exposure to simulated body fluid (SBF). The organoapatite characterization of the coating was carried out by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. The copolymer of acrylic acid and itaconic acid overlayer which is rich of carboxylate groups can lead to the deposition of needle-like and homogeneous HA on the surface after immersion in SBF.

Comparison of two types of alginate microcapsules on stability and biocompatibility in vitro and in vivo.

Transplantation of encapsulated living cells is a promising approach for the treatment of a wide variety of diseases, especially diabetes. Range-scale application of the technique, however, is hampered by insufficient stability of the capsules. It is difficult to find the optimal membrane to meet all the properties required for cell transplantation. To overcome these difficulties, it is necessary to compare characteristics such as mechanical strength, cell proliferation and biocompatibility of different membranes. We prepared Ca-alginate-poly-L-lysine-alginate (APA) and Ba-alginate-poly-L-lysine-alginate (BPA) microcapsules using the electrostatic droplet method. The integrity of the microcapsules was measured by suspending them in a saline buffer and shaking at 150 rpm for 48 h. The microcapsules were cultured in simulated body fluid to analyze the osmotic pressure stability and implanted in the leg muscle pouch of SD rats to test in vivo transplantation stability. The microcapsules were implanted in the intraperitoneal cavity; then the biocompatibility of microcapsules was identified through analyzing fibrosis formation of microcapsules. The proliferation of cells (Cos-7 and HL-60) cultured in the microcapsules was measured by MTT assay. After 48 h shaking at 150 rpm, the percentages of intact microcapsules of BPA and APA microcapsules were 98.5 +/- 0.248% and 95.7 +/- 0.221% (p < 0.05), respectively. The intact percentages of APA and BPA microcapsules were 96.9% and 97.7%, respectively, after being soaked in SBF at 37 degrees C for 15 days. The empty APA and BPA microcapsules were not adhered to the muscle and there was light cellular overgrowth. There is no difference on biocompatibility in implantation into peritoneal cavities. After the cells were cultured in microcapsules, A(490 nm) of the 8th week was significantly higher than that of 1 day, and the 4th week was at the peak of the cell proliferation curve. After culture for 2 to 6 weeks, spheroids started to develop gradually within the beads. The mechanical strength of BPA microcapsules was higher than that of APA microcapsules. However, there was no difference between the two kinds of capsules in biocompatibility. Microencapsulation did not affect cell proliferation or increase the quantity of cells. In conclusion, BPA microcapsules were more suitable for transplantation in vivo.

[The preliminary study of three-dimensional simulation of the craniofacial system].

OBJECTIVE: To look for the way of three-dimensional simulation of the craniofacial system. METHODS: A three-dimensional laser scanner was used for gypsum models digitization and computed tomography scans was employed for skull reconstruction, then the data of teeth and temporomandibular joint were picked up and integrated. The ARCUS sigma system was used to record spatial mandibular movements. The data of both digital reconstruction and spatial movements were transferred into one coordinate system. The software for three-dimensional simulation was programmed. RESULTS: The preliminary program could be used to analyze static and dynamic occlusion and gnathic relations, to check the contact points and to show from various visual angles and slices. The occlusal plane, curves, and helical axis were initially defined and displayed. CONCLUSIONS: Using available instruments and methods, we developed the primary edition for three-dimensional simulation of the craniofacial system. However, it is far from a mature system and there is still plenty of work to be done.