[Application of single anterior teeth defect with computer-aided design and computer-aided manufacturing polymethyl methacrylate single-retainer resin-bonded fixed dental prosthesis in children].

Objective: To explore the clinical effect of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA) single-retainer resin-bonded fixed dental prosthesis (RBFDP) for single anterior teeth defect. Methods: A total of 14 children between 10-14 years old (male 8, female 6) who visited the Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University from March to December 2022 with single anterior teeth loss were enrolled in this study. The intraoral scanner was used to obtain their digital impressions, and then the data were imported into CAD software. The single-retainer RBFDP was designed by the CAD software and was manufactured by milling equipment using CAD/CAM PMMA disk. The prosthesis was then tried-in and bonded to the abutment teeth with resin cement and evaluated in a 12 month follow-up observation. The marginal discoloration, marginal adaptation, color match, secondary caries, the occurrence of fractures and loose of abutment tooth were examined on the basis of the modified United States Public Health Services evaluation system. The evaluation was divided into three scores, in which score A indicated ideal restoration effect, score B means that the restoration effect was acceptable (evaluation of restoration integrity, loose of abutment teeth and secondary caries excluded), and score C indicates that the restoration effect is not good. Results: All the 14 CAD/CAM PMMA single-retainer RBFDP had good marginal adaptation and color match with no marginal discoloration, no secondary caries, no fracture of restorations and no abnormal loose of the abutment teeth. All of the six criteria achieved score A evaluation after a three month follow-up observation. One restoration was classified as score B for fracture after a six month follow-up observation, while two restoration were classified as score B for marginal discoloration after 12 month follow-up observation. Conclusions: The CAD/CAM PMMA single-retainer RBFDP was clinically effective in restoration of single anterior teeth defect in children.

[Exploration of making removable partial denture by digital technology].

To explore the digital manufacturing process of distal extension removable partial denture. From November 2021 to December 2022, 12 patients (7 males and 5 females) with free-ending situation were selected from the Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University. Three-dimensional model of the relationship between alveolar ridge and jaw position was obtained by intraoral scanning technique. After routine design, manufacturing and try-in of metal framework for removable partial denture, the metal framework was located in the mouth and scanned again to obtain the composite model of dentition, alveolar ridge and metal framework. The free-end modified model is obtained by merging the digital model of free-end alveolar ridge with the virtual model with the metal framework. The three-dimensional model of artificial dentition, and base plate was designed on the free-end modified model, and the resin model were made by digital milling technology. The removable partial denture was made by accurately positioning the artificial dentition and base plate, bonding metal framework with injection resin, grinding and polishing the artificial dentition and resin base. Compared with the design data after clinical trial, the results showed that there was an error of 0.4-1.0 mm and an error of 0.03-0.10 mm in the connection between the resin base of artificial dentition and the connecting rod of the in-place bolt and the connection between artificial dentition and resin base. After denturen delivery, only 2 patients needed grinding adjustment in follow-up visit due to tenderness, and the rest patients did not find any discomfort. The digital fabrication process of removable partial denture used in this study can basically solve the problems of digital fabrication of free-end modified model and assembly of artificial dentition with resin base and metal framework.

A comparison of the biomechanical stability of pedicle-lengthening screws and traditional pedicle screws: an in vitro instant and fatigue-resistant pull-out test.

Aims: The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing. Materials and Methods: A total of 60 lumbar vertebrae were divided into six groups: PLS submitted to instant pull-out and fatigue-resistance testing (groups A1 and A2, respectively), TPS submitted to instant pull-out and fatigue-resistance testing (groups B1 and B2, respectively) and PLS augmented with 2 ml polymethylmethacrylate, submitted to instant pull-out and fatigue-resistance testing (groups C1 and C2, respectively). The PPF and normalized PPF (PPFn) for bone mineral density (BMD) were compared within and between all groups. Results: In all groups, BMD was significantly correlated with PPF (r = 0.83, p < 0.001). The PPFn in A1 was significantly less than in B1 (p = 0.006) and C1 (p = 0.002). The PPFn of A2 was significantly less than in B2 (p < 0.001) and C2 (p < 0.001). The PPFn in A1, B1, and C1 was significantly greater than in A2 (p = 0.002), B2 (p = 0.027), and C2 (p = 0.003). There were no significant differences in PPFn between B1 and C1, or between B2 and C2. Conclusion: Pedicle lengthening screws with cement augmentation can provide the same fixation stability as traditional pedicle screws and may be a viable clinical option. Cite this article: Bone Joint J 2018;100-B:516-21.

[Giant cell reparative granuloma originating from the paranasal sinus: a case report].

A 40-year-old man presented with a 10-year history of nasal obstruction of his left nose, a 1-year history of headache and orbital pain. Radiologically, an extensive paranasal sinus mass was seen. Superiorly ,the cribriform plate was demineralized, and the lesion had intracranial extension with mild mass effect over the basal frontal lobes. Histologic examination revealed a central giant cell reparative granuloma. After endoscopic removal, the patient was symptom free at the 2-month follow-up.

Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-analysis.

The objective of this study is to evaluate the association between chronic periodontitis (CP) and the risk of erectile dysfunction (ED). Electronic search using PubMed, Embase and the Cochrane Library was carried out for observational studies, longitudinal, cohort, case-control and epidemiological studies on humans, published up to December 2015. Manual searches were also performed. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to estimate the association between CP and the risk of ED. Methodological quality assessment was carried out using the Newcastle-Ottawa Quality Assessment Scale. Four case-control studies and one cross-sectional studies involving 213, 006 participants were included. Based on the random-effects model, analyses of all studies showed that CP was associated with an increased risk of ED (OR=2.28, 95% CI: 1.50-3.48). There was heterogeneity among the studies (P<0.001, I2=97.8%). Estimates of total effects were generally consistent with the sensitivity and subgroup analyses. In conclusion, our meta-analysis suggested that there was a significant association between CP and the risk of ED. Further epidemiological studies are needed to better estimate the key risk factors for periodontitis and their interaction effects.

Thermoresponsive comb-shaped copolymer-Si(100) hybrids for accelerated temperature-dependent cell detachment.

Well-defined comb-shaped copolymer-Si(100) hybrids were prepared, via successive surface-initiated atom transfer radical polymerizations (ATRPs) of glycidyl methacrylate (GMA) and N-isopropylacrylamide (NIPAAm), for accelerated cell detachment at a lower temperature. The Si-C bonded comb copolymer consisted of a well-defined (nearly monodispersed) poly(glycidyl methacrylate) (P(GMA)) main chain, a well-defined NIPAAm polymer (P(NIPAAm) block, and well-defined P(NIPAAm) side chains. The ring opening reaction of epoxy groups of the P(GMA) main chain with 2-chloropropionic acid resulted in the immobilization of the alpha-chloroester groups (the ATRP initiators for the NIPAAm side chains) and the concomitant formation of hydroxyl groups. P(NIPAAm) acted as the thermoresponsive side chains of the comb copolymer for control of cell adhesion and detachment, while the P(GMA) main chain with hydroxyl groups provided a local hydrophilic microenvironment. The unique microstructure of the comb copolymer brushes facilitated cell recovery at 20 degrees C (below the lower critical solution temperature (LCST) of P(NIPAAm)) without restraining cell attachments and growth at 37 degrees C. The accelerated detachment of cells indicated that the underlying hydrophilic environment of the comb copolymer brushes contributed to speedy hydration of the P(NIPAAm) segments below the LCST. The thermoresponsive comb copolymer-Si(100) hybrids are potentially useful as adhesion modifiers for cells in silicon-based biomedical devices.

In vitro antibacterial and cytotoxicity assay of multilayered polyelectrolyte-functionalized stainless steel.

Infection of implanted materials by bacteria constitutes one of the most serious complications following prosthetic and implant surgery. In the present study, a new strategy for confering stainless steel with antibacterial property via the alternate deposition of quaternized polyethylenimine (PEI) or quaternized polyethylenimine-silver complex and poly(acrylic acid) (PAA) was investigated. The success of the deposition of the polyelectrolyte multilayers (PEM) and its chemical nature was investigated by static water contact angle and X-ray photoelectron spectroscopy (XPS), respectively. The antibacterial activity was assessed using Escherichia coli (E. coli, a gram-negative bacterium) and Staphylococcus aureus (S. aureus, a gram-positive bacterium). The inhibition of E. coli and S aureus growth on the surface of functionalized films was clearly shown using the LIVE/DEAD Baclight bacterial viability kits and fluorescence microscopy. The cytotoxicity of the PEM to mammalian cells, evaluated by the MTT assay, was shown to be minimal and long-term antibacterial efficacy can be maintained. These results indicate new possibilities for the use of such easily built and functionalized architectures for the functionalization of surfaces of implanted medical devices.

Collagen-coupled poly(2-hydroxyethyl methacrylate)-Si(111) hybrid surfaces for cell immobilization.

To improve the biocompatibility of silicon-based implantable micro- and nanodevices, and to tailor silicon surfaces for controlled cell immobilization, well-defined functional polymer-Si(111) hybrids, consisting of nearly monodispersed poly(2-hydroxyethyl methacrylate [P(HEMA)] with covalently coupled collagen and tethered (Si-C bonded) on the silicon surfaces, were prepared. HEMA was graft polymerized on the hydrogen-terminated Si(111) surface (Si-H surface) via surface-initiated atom transfer radical polymerization (ATRP) to give rise to the Si-g-P(HEMA) hybrid. The active chloride end groups preserved throughout the ATRP process and the chloride groups converted from some (approximately 20%) of the OH groups of the P(HEMA) brushes were used as the leaving groups for nucleophilic reaction with the -NH2 groups of collagen to give rise to the Si-g-P(HEMA)-collagen surface conjugates. These hybrid surfaces were evaluated by culturing 3T3 fibroblasts. The biocompatible Si-g-P(HEMA) hybrid surface resisted attachment and growth of this cell line. The Si-g-P(HEMA)-collagen hybrid surfaces, on the other hand, exhibited good cell adhesion and growth characteristics, and the extent of cell immobilization could be controlled by adjusting the amount of immobilized collagen. Thus, incorporating the collagen-coupled P(HEMA) onto silicon surfaces via robust Si-C bonds may endow the silicon substrates with new and interesting properties for potential applications in silicon-based implantable devices, such as molecular sensors and biochips.

Pathways involved in the spread of buccal carcinoma on contrast-enhanced multislice CT.

OBJECTIVES: To explore how buccal carcinoma spread, using contrast-enhanced multislice CT (CEMSCT). METHODS: We retrospectively analysed the extent of lesions in 56 patients with primary buccal squamous cell carcinoma (SCCA). Abnormal manifestations on CEMSCT at oral subsites and involved adjacent structures were documented and evaluated, which were compared with the results of surgery and histopathology. RESULTS: Infiltration and spread to oral subsites and/or adjacent structures was confirmed in 33 patients (58.9%). The opening of the Stensen duct was the most commonly invaded oral subsite (72.7%); other sites included the gingivobuccal sulcus (60.6%), pterygomandibular raphe (54.5%), gingiva (24.2%), retromolar trigone (24.2%), orbicularis oris (18.2%) and the floor of mouth (15.2%). Of the involved adjacent structures, the buccal space was the most common site of spread (69.7%), followed by the masticatory muscles and spaces (57.6%), bone (54.5%), skin and subcutaneous fat (39.4%), pharynx (30.3%), investing fascia (15.2%) and the base of the skull (6.1%). CEMSCT manifestations of the involvement in buccal SCCAs had correlations with pathological findings (p < 0.05). The sensitivities, specificities and accuracies of two radiologists' evaluation on buccal carcinoma involvement were 50.00%, 23.21% and 73.21%; and 51.79%, 32.14% and 83.93%, respectively. CONCLUSIONS: Buccal SCCAs could superficially and deeply spread to multiple oral subsites and/or adjacent structures. CEMSCT could delineate their spread pathways and extents.

TT virus: a study of molecular epidemiology and transmission of genotypes 1, 2 and 3.

BACKGROUND: TT virus (TTV) is a recently discovered virus, which is not related to any other known virus infecting humans. OBJECTIVES: To investigate: (i) the world-wide distribution of the three major TTV genotypes; and (ii) the possible routes of viral transmission. STUDY DESIGN: (i) The phylogenetic distribution of 494 TTV isolates originating from 31 countries was analysed, using partial ORF1 sequences. (ii) Faeces samples (n=22) and saliva samples (n=72) from French individuals were tested for the presence of TTV DNA. (iii) Viral titres in paired serum and saliva samples were compared. RESULTS: (i) Genotypes 1, 2 and 3 were distributed world-wide, with a high proportion of type 1 in Asia (71%) and no type 3 identified in Africa to date. In the USA, 77% of isolates were grouped in four clusters only (genetic distances <10%). This was also the case of 76% of French isolates, 76% of Japanese isolates, and 89% of Hong Kong isolates. (ii) TTV DNA was detected in 18% of faeces samples and 68% of saliva samples tested. (iii) Viral titre in saliva samples was 100-1000 times higher than that of the corresponding serum. CONCLUSIONS: (i) The observed epidemiological distribution of TTV isolates is compatible with an ancient dissemination of viral ancestors belonging to the different genotypes and a slow genetic evolution in sedentary populations. (ii) Besides the possible transmission of TTV by the parental and oral-faecal routes, the high titre of TTV DNA observed in saliva raises the hypothesis of the viral transmission by saliva droplets. This route of transmission could explain the high degree of exposure to viral infection observed in the general population.

Biodegradation of hyaluronic acid derivatives by hyaluronidase.

Hyaluronic acid (salt) (HA) has been chemically modified as a biomaterial for medical applications such as controlled drug release matrices, nerve guides and wound dressings. A series of HA derivatives, which include different ester types and different degrees of esterification, have been used to investigate the stability of these materials in testicular hyaluronidase. Gel permeation chromatography and capillary viscometer have been employed to determine the size of the molecules, the former used for the water insoluble derivatives that dissolve in dimethyl sulphoxide, the latter for the water soluble samples. The preliminary experimental results indicated that the molecular weight of fully esterified hyaluronic acid (both ethyl and benzyl esters) did not decrease after treatment in the enzyme for 7 and 14 days while the water soluble partially esterified HA were degraded by the enzyme producing a sharp reduction of viscosity within minutes. These observations tend to suggest that the carboxylic groups in the beta-glucoronic acid unit are the activation centre of this enzyme and the total blockage of these groups can restrict the cleavage of beta (1-->4) glycoside bonds by this enzyme.

Mechanisms of polymer degradation in implantable devices. I. Poly(caprolactone).

Poly(caprolactone) is a biodegradable aliphatic (poly(alpha-hydroxy acid), with important applications in the field of human therapy, due to its biocompatibility and bioresorbability. The degradation of poly(alpha-hydroxy acids) depends on chemical hydrolysis, but there is much interest in the precise mechanisms, including the role of free radicals, especially oxygen free radicals and their role in human disease. The hydrolytic degradation of poly(caprolactone) in aqueous environments was used as the control in a study of the effects of hydroxyl radicals in aqueous solutions. Different methods (GPC, DSC, SEM) were employed to investigate the mechanism of degradation of this semicrystalline physiologically absorbable polymer. The data indicate that hydroxyl radical is likely to be a major factor in the degradation of this polymer.

Human neutrophil chemokinesis and polarization induced by hyaluronic acid derivatives.

Neutrophils and macrophages are known to undergo significant modifications in their morphology and basal metabolism in response to chemical factors, in particular changes in the shape, movement, phagocytic activity and degranulation. These phenomena often involve an increase in chemokinesis and cellular secretory activity, usually expressed in antimicrobial activity. Once activated, the cells can move quickly towards the source of the stimulus, where they produce and release great amounts of enzymes (e.g. proteases, hydrolases, lysozyme) and reactive oxygen metabolites (e.g. O2-., H2O2, OH.). This study has examined the ability of surfaces of selected biomaterials to influence neutrophil morphology and locomotion. The surface of two films derived from hyaluronic acid derivatives were compared with that of glass. The two hyaluronic acid derivatives, despite having a similar chemical structure, were shown to interact with human neutrophils in different ways. A hyaluronic acid ethyl ester stimulated the whole population of neutrophils to take up a non-spherical morphology (polarize) and to move with a velocity similar to that of N-formyl-methionine-leucine-phenylalanine-stimulated cells on a glass surface. In contrast, only 44% of the examined cells on the surface of hyaluronic acid benzyl ester were polarized and their mean speed was only slightly higher with respect to that found with non-stimulated cells on glass. Moreover, while on the benzyl ester and on glass a correlation between neutrophil circularity (i.e. the shape of the cell) and cell speed was found, the ethyl ester did not show any correlation.

Quantitative assessment of the tissue response to films of hyaluronan derivatives.

The aim of this study was to evaluate the in vivo response following implantation into a rat model of three innovative hyaluronan derivatives for clinical use: HYAFF 7, HYAFF 11 and HYAFF 11p75 (respectively, the 100% ethyl ester, 100% and 75% benzyl esters). The tissue reaction evoked by films of these new biomaterials implanted into the dorsolumbar musculature of rats was assessed quantitatively using a well established technique based upon an image analysis system. The number of inflammatory cells present and the patterns of cell distribution around the implant up to a distance of 642 microns were examined at different time periods after implantation. Since a well-delineated tissue-material interface was needed for this type of investigation, it was not possible to apply image analysis to sections once dissolution of the implanted materials had begun. Films of both the total esters, HYAFF 7 and HYAFF 11, were found to undergo a slow dissolution process and, after a month, films of these materials were still present at the site of implantation. Differences in response to the two materials were observed only during the first two weeks, particularly with respect to neutrophil distribution and total cellularity. HYAFF 7 was found to be more reactive, with higher numbers of neutrophils near the surface of the implant than HYAFF 11. Thereafter, the differences between the two materials were minimal and owing mainly to a faster dissolution of HYAFF 7 films. After 3 and 5 months, considerable degradation of films of both total esters had occurred. Significant quantities of material appeared inside numerous macrophages with an ED1-positive phenotype. Only a very thin layer of fibrous connective tissue, indicative of low reactivity, was found to surround the site of implantation, separating the dissolved material and the phagocytic cells from healthy muscular tissue. ED2-positive macrophages were primarily confined within the lining connective tissue. The partial benzyl ester, HYAFF 11p75, showed a different behaviour. In fact, evidence of film dissolution was already present a week after the implantation. After two weeks, the implanted films were completely dissolved and numerous ED1-positive macrophages phagocytosing the material were observed at the site of implantation. Therefore, in agreement with previous in vitro studies, which showed a greater susceptibility to degradation of hyaluronan derivatives with lower percentage of esterification, HYAFF 11p75 underwent resorption faster than the corresponding total ester.

The mechanical and microscopic aspects of the deformation and fracture of a poly (ether urethane-urea) spun arterial prosthesis.

The mechanical properties of a microporous, electrostatically spun poly (ether urethane-urea), used in the construction of arterial prostheses, have been examined, with particular reference to anisotropic, crack initiation processes and preconditioning. The results demonstrate considerable anisotropy in relation to samples derived from circumferential and longitudinal directions of the tube wall structure related to the spinning process. There is also a considerable difference in crack initiation on inner and outer surface of the arterial wall, again related to the processing conditions. The results provide an important contribution to an understanding of structure-property relationships in microporous arterial prosthesis.

Corrosion fatigue behaviors of two biomedical Mg alloys - AZ91D and WE43 - In simulated body fluid.

Magnesium alloys have been recently developed as biodegradable implant materials, yet there has been no study concerning their corrosion fatigue properties under cyclic loading. In this study the die-cast AZ91D (A for aluminum 9%, Z for zinc 1% and D for a fourth phase) and extruded WE43 (W for yttrium 4%, E for rare earth mischmetal 3%) alloys were chosen to evaluate their fatigue and corrosion fatigue behaviors in simulated body fluid (SBF). The die-cast AZ91D alloy indicated a fatigue limit of 50MPa at 107 cycles in air compared to 20MPa at 106 cycles tested in SBF at 37°C. A fatigue limit of 110MPa at 107 cycles in air was observed for extruded WE43 alloy compared to 40MPa at 107 cycles tested in SBF at 37°C. The fatigue cracks initiated from the micropores when tested in air and from corrosion pits when tested in SBF, respectively. The overload zone of the extruded WE43 alloy exhibited a ductile fracture mode with deep dimples, in comparison to a brittle fracture mode for the die-cast AZ91D. The corrosion rate of the two experimental alloys increased under cyclic loading compared to that in the static immersion test.

[The applied anatomy of the periosteal flap composed of submental artery and dgastric muscle].

OBJECTIVE: To provide anatomical basis for a new style operation using periosteal flap composed of submental artery, anteroventral portion of digastric muscle and submental artery for the renovation of laryngotrachea. METHODS: The anatomical structures correlative with submental artery, submental vein, anteroventral portion of digastric muscle and mandibular periosteum in 23 (46 sides) cephalocervical samples were measured. RESULTS: The periosteal flaps had shown many advantages inculding large transfer capacity, rich blood supply, flexibility. CONCLUSION: It is feasible that the periosteal flap composed of submental artery, anteroventral portion of digastric muscle and mandibular periosteum is useful laryngotracheal renovation.

Diagnostic value on signs of subluxation of cervical vertebrae with radiological examination.

OBJECTIVE: To investigate the relationship between radiographic signs of subluxation in the cervical vertebrae and their clinical diagnostic value. DESIGN: Controlled, clinical study. SETTING: Institute of Clinical Anatomy and Biomechanics and NanFang Hospital of the First Military Medical University, Guangzhou, China. SUBJECTS: Eighty-seven subjects with cervicodynia and 21 asymptomatic volunteers. INTERVENTIONS: Radiological signs of subluxation from anteroposterior, lateral, open-mouth and dynamic radiographs of the cervical vertebrae of the subjects were measured and analyzed. MAIN OUTCOME MEASURES: The right and left odontoid lateral mass interspace, divergence of the spinous processes, sign of double contour and position of odontoid process were studied. RESULTS: The bilateral odontoid lateral mass interspaces were asymmetrical in most cases, and the divergence of spinous processes, sign of double contour and position of odontoid process were also common. Cervical vertebrae C5, C4 and C6 showed no special variations. CONCLUSION: There was little evidence to support the contention that signs of subluxation in the cervical vertebrae are of diagnostic significance. Subluxation should be defined in two ways: as a purely roentgenological diagnosis and as a combination of roentgenological signs with clinical signs.

Surface-active and stimuli-responsive polymer--Si(100) hybrids from surface-initiated atom transfer radical polymerization for control of cell adhesion.

A simple two-step method was developed for the covalent immobilization of atom-transfer radical polymerization (ATRP) initiators on the hydrogen-terminated Si(100) (Si-H) surface. Well-defined functional polymer-Si hybrids, consisting of covalently tethered brushes of poly(ethylene glycol) monomethacrylate (PEGMA) polymer, N-isopropylacrylamide (NIPAAm) polymer, and NIPAAm-PEGMA copolymers and block copolymers on Si-H surfaces, were prepared via surface-initiated ATRP. Kinetics study revealed that the chain growth from the silicon surface was consistent with a "controlled" process. Surface cultures of the cell line 3T3-Swiss albino on the hybrids were evaluated. The PEGMA graft-polymerized silicon [Si-g-P(PEGMA)] surface is very effective in preventing cell attachment and growth. At 37 degrees C [above the lower critical solution temperature (LCST, approximately 32 degrees C) of NIPAAm], the seeded cells adhered, spread, and proliferated on the NIPAAm graft polymerized silicon [Si-g-P(NIPAAm)] surface. Below the LCST, the cells detached from the Si-g-P(NIPAAm) surface spontaneously. Incorporation of PEGMA units into the NIPAAm chains of the Si-g-P(NIPAAm) surface via copolymerization resulted in more rapid cell detachment during the temperature transition. The "active" chain ends on the Si-g-P(PEGMA) and Si-g-P(NIPAAm) hybrids were also used as the macroinitiators for the synthesis of diblock copolymer brushes. Thus, not only are the hybrids potentially useful as stimuli-responsive adhesion modifiers for cells in silicon-based biomedical microdevices but also the active chain ends on the hybrid surfaces offer opportunities for further surface functionalization and molecular design.

A study of calcium ion-selective PVC membrane electrode based on neutral carrier N,n,n',n'-tetracyclo-3-oxapentanediamide (correction of oxapetanediamide).

A calcium ion-selective PVC membrane electrode based on neutral carrier n,n,n',n'-tetracyclohexyl-3-oxapetanediamide, using di-(2-ethylhexyl)phthalate as the plasticizer and potassium tetrakis (4-chlorophenyl) borate as the additive is reported in this paper. The ion selective membrane consists of 1 wt% of the Ca2+ selective ligand, 65 wt% of the plasticizer, 1 wt% of the additive and 33 wt% of poly (vinyl chloride) powder. The electrode has the linear response range of 2.0 x 10(-7)-10(-1) mol/L with the Nernstian slope of 28 mV/decade at 25 degrees C and the detection limit of 2.0 x 10(-8) mol/L. The response time of the calcium ion-selective electrode is as the concentration of calcium ion is rapidly shifted from 10(-5) to 10(-4) mol/L. The potential stability and reproducibility are good. The free calcium in blood serum was determined by the calcium ion-selective electrode with satisfactory results.