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OBJECTIVE@#To investigate the clinical efficacy and advantage of minimally invasive transforaminal lumbar interbody fusion under microscope-assisted Zista channel in the treatment of degreeⅠandⅡdegenerative lumbar spondylolisthesis.@*METHODS@#The clinical data of 18 patients with degenerative lumbar spondylolisthesis treated by microscope-assisted Zista channel MIS-TLIF operation from January 2017 to March 2018 were analyzed retrospectively. There were 10 males and 8 females with an average age of 59 years (48 to 70). The course of spondylolisthesis ranged from 6 months to 5 years with an average of 33 months. The segment of spondylolisthesis was L@*RESULTS@#All the patients completed the operation successfully and were followed up more than 12 months after operation. Operation time was(160.45±34.98) min, intraoperative blood loss was (88.32±21.12) ml, postoperative drainage volume was (50.34 ±18.22)ml, and walking time after operation was (20.65±6.25) h. Preoperative and postoperative at 7 days, 3 months, 12 months, VAS score of low back pain was 7.81±2.16, 4.19±1.17, 2.25±0.62 and 1.53±0.58 respectively, VAS score of leg pain was 8.47± 2.21, 3.45±0.86, 2.31±0.73 and 1.43±0.47, JOA score was 12.01±2.33, 18.56±3.12, 23.54±3.31 and 26.34±2.65. There were significant differences in VAS and JOA scores between preoperative and postoperative (@*CONCLUSION@#MIS-TLIF under microscope-assisted Zista channel has obvious minimally invasive advantages in the treatment of degreeⅠandⅡdegenerative lumbar spondylolisthesis, and it is a safe and effective method.
Subject(s)
Female , Humans , Male , Middle Aged , Lumbar Vertebrae/surgery , Minimally Invasive Surgical Procedures , Retrospective Studies , Spinal Fusion , Spondylolisthesis/surgery , Treatment OutcomeABSTRACT
OBJECTIVE@#To investigate the clinical efficacy and advantages of the full endoscopic I See technique for the single-segment degenerative lumbar spinal stenosis.@*METHODS@#The clinical data of 38 patients with the single-segment degenerative lumbar spinal stenosis treated by full endoscopic I See technique from January 2017 to March 2018 were analyzed retrospectively. There were 16 males and 22 females, aged from 35 to 79 years with an average of(53.45±12.56) years. Five cases were L, 23 cases were L, 10 cases were LS. The clinical efficacy was evaluated by VAS, ODI and Macnab scores.@*RESULTS@#All the patients were followed up for more than 12 months after operation. The length of operation was from 55 to130 (86.0± 17.5) min. Intraoperative blood loss was ranging from 10 to 50 (17±6) ml, and the hospitalization length was from 3 to 7 days with an average of 4.6 days. The VAS scores of low back pain assessed before operation, and 3 d, 3 months, 12 months post operation were 6.67 ±1.25, 3.87 ±1.35, 2.55 ±1.21, 2.05 ±0.97, respectively, and the differences were statistically significant (P < 0.05);VAS scores of leg pain at these time points were 7.85±2.62, 3.31±1.42, 2.02±1.13, 1.85±0.86, respectively, and the differences were statistically significant (<0.05);ODI scores were 40.32±5.38, 25.76±4.81, 12.66±4.64, 9.32±2.91, respectively, and the differences were statistically significant (<0.05). Tevaluate the lumbar vertebrae function according to the Macnab criteria, 15 cases obtained excellent results, 19 cases were good, and 4 cases were fair.@*CONCLUSION@#Full endoscopic I See technique is effective in the treatment of single-segment degenerative lumbar spinal stenosis, with the advantages of less trauma, shorter hospital stay, and faster recovery.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Decompression, Surgical , Lumbar Vertebrae , Retrospective Studies , Spinal Fusion , Spinal Stenosis , Treatment OutcomeABSTRACT
Blastocystis hominis is a common parasitic protozoa in human and animal intestines; however, its pathogenicity remains controversial. Construction of animal models is of great significance to investigate the pathogenicity, pathogenic mechanisms and drug screening of B. hominis. Experimental animals, mode of infections, parasite strains and host immune status are important factors affecting the successful modeling of B. hominis infections in animals. Hereby, we review the progress of researches on animal models of B. hominis infections, and summarize the influencing factors and application of animal models of B. hominis infections, in order to provides insights into the selection of animals models of B. hominis infections.
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Blastocystis hominis is a parasite that parasitizes in the intestines of humans and animals, and is closely related to a variety of gastrointestinal diseases such as abdominal pain and diarrhea. B. hominis is distributed worldwide, and the prevalence of B. hominis infections and dominant subgenotypes vary in countries and in regions from the same country. This paper reviews the global prevalence of B. hominis human infections, its subtypes and geographical distribution, so as to provide insights into the understanding of the global epidemiology of B. hominis and the management of B. hominis infections.
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The study is designed to evaluate the protective effect of xanthan gum (XG) injection on cartilage injury in the rabbit osteoarthritis (OA) model induced by anterior cruciate ligament transection (ACLT), and to explore the effect of XG on the expression of caspase-3 and Bax protein in OA cartilage. Sixty male New Zealand white rabbits were randomly divided into 6 groups (n=10) according to random number table method, and one group was selected randomly as the normal control group (control) while the other 5 groups of right knee were used to establish the OA model with ACLT, which were then divided into model group (model), XG-0.6 mg·kg-1, XG-1.2 mg·kg-1, XG-2.4 mg·kg-1 treatment group and sodium hyaluronate (SH-1.2 mg·kg-1) treatment group according to drug intervention. The knee joint temperature and knee joint width of each group were measured in the course of treatment. After treatment, the macroscopic morphology of rabbit joints in each group was observed. The pathological morphology of articular cartilage of rabbits in each group was observed using HE staining. The expression of Bax and cleaved caspase-3 in the cartilage of rabbits were detected by Western blot. The result shows that XG inhibited the increase in knee joint temperature and knee width caused by OA in a dose-dependent manner. XG improved the morphological abnormalities and tissue injuries of the femoral condyle and tibial plateau caused by OA. Western blot result shows that, compared with the control group, the levels of Bax and cleaved caspase-3 in knee cartilage cells of model group and XG-0.6 mg·kg-1 group were significantly increased (P-1 group (P>0.05). These two groups are significantly higher than those of XG-1.2 mg·kg-1 and XG-2.4 mg·kg-1 (P-1 and XG-1.2 mg·kg-1 group (P>0.05). The level of Bax in knee cartilage in XG-2.4 mg·kg-1 group was lower than that of XG-1.2 mg·kg-1 group (P<0.05). In conclusion, XG effectively protected cartilage damage in OA, and inhibited the expression of Bax and caspase-3 protein in OA cartilage.
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Objective To study the effect of mechanical stretch on expression of inflammasome related factors in human periodontal ligament cells (HPDLCs). Methods HPDLCs were subjected to mechanical stretch with a 20% elongation magnitude for 6 h or 24 h, respectively. The mRNA and protein expression levels of IL-1β, Caspase-1 and NLRP3 were detected by real-time quantitative PCR and Western blot. The levels of IL-1β in the cell-culture medium of HPLCs in response to mechanical stretch for 1, 2, 4, 6 h were detected by ELISA, respectively. In control group, HPDLCs were cultured in similar conditions but not subjected with stretch. Results The mRNA and protein expression levels of IL-1β, Caspase-1 and NLRP3 were up-regulated with mechanical stretch for 6 h (P<0.05). The protein expression level of NLRP3 was up-regulated with mechanical stretch for 24 h (P<0.05). Compared with control group, the content of IL-1β in the cell-culture medium of HPLCs was increased significantly in response to mechanical stretch for 4 h and 6 h(P<0.05). Conclusions The expression of NLRP3/Caspase-1/IL-1β related factors in HPDLCs can be induced by 20% mechanical stretch for 6 h.
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Teeth that have short clinical crown, which are not alone enough to support the definitive restoration can be best treated using the post and core system. The advantages of fiber post over conventional metallic post materials have led to its wide acceptance. In addition to that the combination of aesthetic and mechanical benefits of fiber post has provided it with a rise in the field of dentistry. Also the results obtained from some clinical trials have encouraged the clinicians to use the fiber posts confidently. Fiber posts are manufactured from pre-stretched fibers impregnated within a resin matrix. The fibers could that be of carbon, glass/silica, and quartz, whereas Epoxy and bis-GMA are the most widely used resin bases. But recently studies are also found to be going on for polyimide as possible material for the fiber post resin base as a substitute for the conventional materials.
Subject(s)
Bisphenol A-Glycidyl Methacrylate , Carbon , Crowns , Dentin , Dentistry , Quartz , ToothABSTRACT
<p><b>OBJECTIVE</b>To elucidate the variation in characterizations and genetic evolution of the matrix protein 2 or ion channel protein(M2) genes of avian influenza subtype H5N1 viruses in the boundary region of Yunnan province from 2008 to 2012.</p><p><b>METHODS</b>A total of swab samples were collected from foreign poultry such as the junction between Yunnan and Vietnam, Laos,myanmar and wild birds in boundary region of Yunnan province from 2008 to 2012 and screened by H5N1 subtype-specific multiplex RT-PCR. The M genes of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. The alignment and phylogenetic analysis of M2 genes were performed with sequences of the known reference strains.</p><p><b>RESULTS</b>A total of 71 positive samples were found out of 1240 samples and the positive rate was 5.72%. A total of 14 different M2 sequences were obtained from 30 positive samples and were divided into 3 distinct clades or sub-clades(1.2.1, 1.2.2 and 2) by phylogenetic analysis, 5, 7 and 2, respectively. The M2 genes and Hemagglutinin(HA) genes of H5N1 viruses from the boundary region of Yunnan province had showed different relationship of genetic evolution. The substitution or mutation of key amino acids sites had been found among the domains of epitope, adamantane-resistance, and poultry or human original viral strains.</p><p><b>CONCLUSION</b>The M2 genes of H5N1 subtype viruses in boundary region of Yunnan province from 2008 to 2012 showed genetic divergence and the virus of clade 1.2.2 had become dominant epidemic strain in this region.</p>
Subject(s)
Animals , Birds , Virology , Chickens , Virology , China , Evolution, Molecular , Influenza A Virus, H5N1 Subtype , Classification , Genetics , Influenza in Birds , Virology , Phylogeny , Poultry , Virology , Viral Matrix Proteins , GeneticsABSTRACT
Bats are considered as important animal reservoirs for many pathogenic viruses to humans. The viral metagenomic analysis was performed to study gut and lung tissues of 30 insectivorous bats collected in Yunnan Province and 26 reads were noted to group A rotavirus (RVA). Further RT-PCR screening on bat samples and in vitro viral isolation on cell cultures confirmed the presence of a novel RVA, named as RVA/Bat-tc/MYAS33/2013/G3P[10], in one of 30 Stoliczka's trident bats. The VP7 gene of this strain MYAS33 was closely related to that of an equine RVA strain from Argentina and the nucleotide sequence similarity was 93%, while its VP4 gene was a rare P[10] type and obtained the maximum sequence identity (94.8%) with that of a human strain from Thailand. The present study highlights the potential role of bats as reservoirs for RVAs.
Subject(s)
Animals , Humans , China , Chiroptera , Virology , Molecular Sequence Data , Phylogeny , Rotavirus , Classification , Genetics , Rotavirus Infections , Virology , Viral Proteins , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To elucidate the characteristics of variation and the genetic evolution of non-structural protein (NS1, NS2) genes related to avian influenza subtype H5N1 viruses isolated from the boundary region of Yunnan province.</p><p><b>METHODS</b>Swab samples were collected from foreign poultry and wild birds in the boundary regions of Yunnan province and screened by H5/N1 subtype-specific multiplex RT-PCR. The NS segment of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. The alignment and phylogenetic analysis on those available NS1, NS2 genes were performed with sequences of the known reference strains.</p><p><b>RESULTS</b>71 positive samples were identified from 1240 samples, with the positive rate as 5.72%. Fourteen different NS segment sequences were obtained from 30 representative positive samples and could be divided into 3 distinct clades or sub-clades (I-1, I-2 and II), by phylogenetic analysis. The NS1/NS2 genes and Hemagglutinin (HA) genes of H5N1 viruses from the boundary regions of Yunnan province showed different relationships regarding the characteristics on genetic evolution. The substitution or mutation of key amino acids sites had been noticed in the nuclear location signal domains, effect domain, and other pathogenicity markers.</p><p><b>CONCLUSION</b>NS genes of H5N1 subtype viruses in boundary region of Yunnan province showed genetic divergence and the virus of clade I-2 and II had become dominant epidemic strains in this region since 2010.</p>
Subject(s)
Animals , Amino Acid Sequence , Animals, Wild , Birds , Virology , China , Epidemiology , Evolution, Molecular , Genome, Viral , Influenza A Virus, H5N1 Subtype , Genetics , Influenza in Birds , Epidemiology , Virology , PhylogenyABSTRACT
Objective To elucidate the genetic diversifications of avian influenza subtype H5N1 viruses in the boundary regions of Yunnan province during 2009 to July,2011.Methods Swab samples were collected from foreign poultry and wild birds in boundary regions of Yunnan province during 2009 to July,2011 and tested by H5/N1 subtype-specific multiplex RT-PCR.The HA genes of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD 18-T vectors for sequencing.Both alignment and phylogenetic analysis were performed with sequences of the known reference strains.Results Fifteen different HA sequences were obtained from 36 representative positive samples and could be divided into 2 distinct Clades (2.3.2 and 2.3.4).Through phylogenetic analysis,Clade 2.3.2 and 2.3.4 could then be further divided into 3 ( Ⅱ -1 to Ⅱ -3 ) and 2 smaller clades ( Ⅰ -1 and Ⅰ -2),respectively.The viruses of Clade 2.3.2 Ⅱ -1 and Ⅱ-2 were new variant strains of H5N 1 virus.The cleavage sites of HA from positive samples all possessed molecular characterization of highly pathogenic avian influenza virus.Mutation of key amino acids had been found among receptor binding sites,potential glycosylation sites,neutralizing epitopes and others.Conclusion It seemed evident that the H5N1 subtype viruses showed genetic diversifications and had undergone the evolution progress of multi-clade (2.3.2,2.3.4) to single caide (2.3.2) in the boundary regions of Yunnan province,during 2009 to July,2011.
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<p><b>OBJECTIVE</b>To investigate the variation of the corrosion resistance of anodized oxidation film on titanium by electrochemical methods.</p><p><b>METHODS</b>TiO2 nanotube layer was formed on Ti surface by anodization. The morphology was observed with scanning electron microscope (SEM) and the crystal phase was analyzed using X-ray diffraction(XRD) before and after annealing. Polarization curves were examined by electrochemical methods.</p><p><b>RESULTS</b>Titanium oxide nanotubes with 80 nm diameter and 400 nm length was seen on Ti after anodization. The annealing nanotubes was anatase crystalline phase by X-ray diffraction analysis. The self-corrosion potential and break-down potential of smooth Ti were significantly lower than TiO2 nanotubes by anodization (P < 0.05). The self-corrosion current and passived current were significantly higher than TiO2 nanotubes by anodization (P < 0.05). Annealing improved the corrosion resistance of anodized oxidation film on titanium.</p><p><b>CONCLUSION</b>The results of electrochemical examinations indicate that the TiO2 nanotubes by anodization increases the corrosion resistance of titanium.</p>
Subject(s)
Corrosion , Microscopy, Electron, Scanning , Nanotubes , Oxidation-Reduction , TitaniumABSTRACT
Objective To develop a set of stretch strain cell loading unit with proprietary intellectual property rights so as to provide a necessary tool for the research of cellular mechanics. Methods Based on the deformation theory of round substrates, the stretch strain cell loading unit could apply the stretch strain to cultured cells in vitro by utilizing digital measuring controlling system and computer software. MTT colorimetric test was adopted to evaluate the ability of human periodontal ligament cells (HPDLCs) to attach and grow on the silastic membrane. The cultured HPDLCs were loaded with 1%, 10% and 20% stretch strain for 0.5, 1 and 24 h, respectively, by the loading unit, and an inverted phase contrast microscope was used to observe the morphology and realignment of HDPLCS. Results The stretch strain cell loading unit could apply the stretch strain of different magnitude, frequency and duration to cultured cells in vitro, with the advantage of a large range strain output, high precision, convenient operation and clear visual monitoring. When cells were seeded for 1, 2, 4, 7, 8 d, respectively, there was no statistical difference between the MTT absorbance value of silastic membrane group and that of control group (P>0.05), showing the good ability of cultured cells to attach and grow on the silastic membrane. After HPDLCs were loaded with 10% and 20% strain for 24 h, the morphology and realignment of HPDLCs changed, and cells became spindle shaped, being parallel to each other with long axis perpendicular to the stretch vector. Conclusions The stretch strain cell loading unit is capable of loading the stretch strain to cultured cells effectively and provides a necessary method for cytomechanical research.
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<p><b>OBJECTIVE</b>To investigate the feasibility of applying three-dimensional printing in the fabrication of facial prostheses cavity.</p><p><b>METHODS</b>The computer aided design (CAD) model of negative mold of a nasal prosthesis was generated with Magics RP software according to an existed CAD model of the positive pattern of nasal prosthesis (STL file). The negative mold and positive pattern of the nasal prosthesis were fabricated by three dimensional printing. The actual nasal prosthesis was produced by pouring silicon into the negative mold. The actual nasal prosthesis and rapid prototyping (RP) fabricated positive pattern were both scanned with a three-dimensional scanning system. Quantitative measurements of registration errors were calculated to evaluate the surface matching degree between the two models.</p><p><b>RESULTS</b>The max positive error between the models of the actual silicon nasal prosthesis and the RP-fabricated positive pattern was 0.98 mm. It was located at the apex nasi area, and the max negative error was -0.64 mm.</p><p><b>CONCLUSIONS</b>Facial prostheses cavity direct three dimensional printing can be one of the methods for automated fabrication of the facial prostheses.</p>
Subject(s)
Computer-Aided Design , Face , Imaging, Three-Dimensional , Maxillofacial Prosthesis , Printing, Three-Dimensional , Prostheses and Implants , Prosthesis Design , SoftwareABSTRACT
Conventional diagnosis and treatment for facial prostheses have setbacks and limitations, including complicated procedure, inefficiency, low accuracy and poor esthetics, which could not meet the demand for high quality of the prostheses of the patients. With the technology of the computer aided design and computer aided manufacture (CAD/CAM), the new era for diagnosis and treatment for facial prostheses has been started since the 1990's. The digital diagnosis and treatment system for facial prostheses has been formed during these ten years, which including the digital data acquisition of the facial defect, CAD for facial prostheses, rapid fabrication of the prostheses. This new system will be the development direction and mainstream technology in the future.
Subject(s)
Humans , Computer-Aided Design , Face , Prostheses and Implants , Prosthesis DesignABSTRACT
<p><b>OBJECTIVE</b>The aim of this study is to evaluate whether the firing times affect the chroma of zirconia by adding rare-earth oxides.</p><p><b>METHODS</b>Six kinds (S1, S2, S3, S4, S5, S6) of tooth-like yttria stabilized tetragonal zirconia polycrystal (Y-TZP) were available by introducing internal colorating technology, the color were gauged with ShadeEye NCC chromatometry instrument, and one-way ANOVA was used to analysis the color of each kind of tooth-like zirconia after 1, 2, 3, 4, 5 times firing individually.</p><p><b>RESULTS</b>After 1, 2, 3, 4, 5 times firing respectively, the chromatic aberration ranged between 0.10-1.47 merely. The luminosity of three kinds (S1, S2, S6) of tooth-like zirconia were decreased (P < 0.05), the luminosity of the other three kinds (S3, S4, S5) of tooth-like zirconia were not obviously changed (P > 0.05), as for the hue and chroma, no significant differences were found (P > 0.05).</p><p><b>CONCLUSION</b>There are no significant influence on the color of tooth-like Y-TZP after 1, 2, 3, 4, 5 times firing respectively, the chroma of yttria stabilized tetragonal zirconia polycrystal by adding rare-earth oxides are with high stability.</p>
Subject(s)
Dental Porcelain , Dental Stress Analysis , Materials Testing , Oxides , Surface Properties , Yttrium , ZirconiumABSTRACT
<p><b>OBJECTIVE</b>To investigate preparation parameters of TiO2 nanotube layer with anodization, and to evaluate the osteoblast activity on TiO2 nanotube layer in vitro.</p><p><b>METHODS</b>Titanium dioxide nanotube layer was grown using anodization method. TiO2 nanotube layers with different structure were obtained by controlling the voltage and time of anodization and rinsing process after anodization. Pure titanium without anodization was used as control. Osteoblasts were cultivated on the anodizated TiO2 nanotube, and the growth of osteoblasts was then evaluated and analyzed.</p><p><b>RESULTS</b>The voltage, duration of anodization and rinsing process following anodization were key factors to affect morphology of TiO2 nanotube layer. The area of osteoblast cultured on TiO2 nanotube layer was larger than that on pure titanium. Results from methylthiazol tetrazolium (MTT) test showed that the proliferation of osteoblasts after 96 h cultivation on TiO2 nanotube layer (0.62 +/- 0.02) was significantly higher than that on unanodizated titanium (0.55 +/- 0.03, P < 0.05). Three weeks later, the alkaline phosphatase (ALP) activity on TiO2 nanotube layer [(130.8 +/- 5.1) A(405)/mg] was significantly higher than that on unanodizated titanium [(109.6 +/- 4.5) A(405)/mg, P < 0.05].</p><p><b>CONCLUSIONS</b>The structure of TiO2 nanotube layer was greatly associated with anodization voltage. The TiO2 nanotube layer had a positive effect on osteoblast behavior.</p>
Subject(s)
Alkaline Phosphatase , Cell Culture Techniques , Cell Proliferation , Nanotubes , Chemistry , Osteoblasts , Cell Biology , Physiology , Titanium , ChemistryABSTRACT
Objective To construct a system for three dimensional face scanning and measurement. Methods The measurement system was based on the principle of triangulation and the combination of gray-code and phase-shift structured light projection. The system software was developed for Windows XP with the aid of tools such as Visual C++ and Hoops. Results A three dimensional measurement system based on structured light projection was developed. The system hardware was composed of fringe projection unit, image gathering unit, system control unit and mechanical appearance, and the system software was composed of point cloud display and editing module. The lamp house of the system was 12V, the working distance was 900 mm, the scanning time was 5.5 s and the scanning field was 500 mm×400 mm. Conclusion The three dimensional measurement system based on structured light projection is a refined machine with safe light to eyes, and the accuracy and scanning speed are suitable to face scanning.
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<p><b>OBJECTIVE</b>To study the influence of two-step sintering method on the sintering property, mechanical properties and microstructure of zirconia ceramic.</p><p><b>RESULTS</b>The nano-size zirconia powder were compacted and divided into two groups, one group for one-step sintering method, another group for two-step sintering method. All samples sintered at different temperature. The relative density, three-bend strength, HV hardness, fracture toughness and microstructure of sintered block were investigated.</p><p><b>RESULTS</b>Two-step sintering method influenced the sintering property and mechanical properties of zirconia ceramic. The maximal relative density was 98.49% at 900 degrees C/1,450 degrees C sintering temperature. There were significant difference of mechanical properties between one-step sintering and two-step sintering, the three-bend strength and fracture toughness declined, hardness increased at two-step sintering. The three-bend strength, HV hardness and fracture toughness reached to maximum value as 1,059.08 MPa +/- 75.24 MPa, 1,377.00 MPa +/- 16.37 MPa and 5.92 MPa x m1/2 +/- 0.37 MPa x m1/2 at 900 degrees C/1,450 degrees C sintering temperature respectively. Microscopy revealed the relationship between the porosity and shapes of grains was correlated to strength of the zirconia ceramics.</p><p><b>CONCLUSION</b>Despite of the two-step sintering method influences the properties of zirconia, it also is a promising esthetic all-ceramic dental material.</p>
Subject(s)
Ceramics , Dental Materials , Dental Porcelain , Hardness , Materials Testing , Porosity , Temperature , ZirconiumABSTRACT
<p><b>OBJECTIVE</b>To analyze the limitation of currently used shade guide systems comparing with color range of nature teeth.</p><p><b>METHODS</b>Digital pictures of shade guide systems A (VITAPAN Classic), B (VINTAGE Halo), C (3D-MASTER), and 322 central incisors were taken under the same condition as light source of D65 with the observation method of d/0 degrees. The data obtained from nature tooth color were compared with the color range of three shade guide systems mentioned above in items of L * a * b */C * H degrees.</p><p><b>RESULTS</b>The normal chroma value (95%) of the natural teeth were L* 61.631-73.250, a * -0.719-1.879, and b * 8.701-17.790. Natural tooth colors were different from those of the shade guide system A which color range was narrower, short of red hue, higher values, and unevenly distribution of saturation. On the other hand, the range of red hue increased in shade guide system B while its saturation was slightly high. The color range of shade guide system C was greatest among the three shade guide systems. The saturation and value of shade guide system C covered all varieties of nature teeth measured in this research, but it still lacked red hue comparing to the nature teeth.</p><p><b>CONCLUSIONS</b>Comparing the color range of nature teeth, the shade guide systems used in clinic have uneven hue distribution and cannot cover all colors of nature teeth. Generally, all the shade guide systems are lack of the hues which are named under the category of red tone.</p>