Ceramic Denture Research Articles

Research on preparation and performance of ceramic denture materials applied for three dimensional printing

The micro-flow extrusion forming of ceramic material has not been developed in three dimensional (3D) printing field. The shape forming of material is by bonding and stacking of filaments of ceramic slurry extruded through micro-sized pores with rather large gaps and porosities, which can affect material's density after sintering and its mechanical property thereafter. Aiming at such a deficiency of this process, the preparation method of ceramic denture printing paste applicable to the process is studied, and the properties of slurry and sintering performance are analyzed and tested. It is concluded that the rheological properties of the prepared ceramic slurry conforms the requirement of micro-flow extrusion process, and the green body after sintering can satisfy the mechanical property requirement of oral denture. This is a technologic breakthrough, laying a foundation for the application of micro-flow extrusion forming in 3D printing of ceramic material, and promoting its development and maturation.

Implantable High-Gain Dental Antennas for Minimally Invasive Biomedical Devices

This paper proposes a novel antenna for dental implants. The proposed antenna can be attached to minimally invasive biomedical devices to monitor health conditions. Based on a combination of Archimedean spirals and a Hilbert-based curve, this 3D folded antenna was embedded on a ceramic denture $({\rm ZrO}_{2})$ , and operates within the medical radio (MedRadio) band. An omnidirectional radiation pattern was obtained from simulations of human models to eliminate specific orientation dependence. A realistic measurement of an oral cavity was also performed under the Institutional Review Board (IRB) protocol to evaluate its practical biomedical effects. A miniature antenna with a total area of less than 245 ${\rm mm}^{2}$ was designed and implemented. The measured performance achieved an antenna gain of $-$ 6.78 dBi, and had an impedance bandwidth of approximately 60 MHz. Therefore, a compact high-gain antenna with a large bandwidth was achieved.

치과용 지르코니아 코어 가공후의 잔여물을 활용하여 주입성형법으로 제조한 소결체의 특성

【Purpose: All ceramic crown, made from zirconia instead of metal for core material, is recognized the best esthetical prosthesis. Recently, high-priced zirconia blocks and expensive CAD/CAM machines come into use for making zirconia core. In this study, slip casting process is adapted to evaluate the possibility of the recycling the remained parts of zirconia block after machining. Methods: Remained zirconia blocks were reduced to powders with zirconia mortar, and screened with 180 mesh sieve. Passed powders were ball milled under various conditions to obtain the optimum zirconia slip for casting. Solid casting method was used for casting the specimens with plaster mold. Formed specimens were dried and biscuit fired at $1,000^{\circ}C$ for 1 hour. Biscuit fired specimens were finished with exact shape of square pillar. Finished specimens were fired from $1,200^{\circ}C$ to $1,550^{\circ}C$ at $50^{\circ}C$ intervals for 1 hour. Linear shrinkage, apparent porosity, water absorption, bulk density, and flexural strength were tested. Microstructures were observed by SEM. Results: Above examinations indicated that the optimum firing temperture was $1,500^{\circ}C$ , and when fired at this temperature for 1 hour, apparent porosity was 0% and flexural strength was 680MPa. SEM photomicrographs showed uniform 200~300nm grain size, which is equal with microcture of sintered commercial zirconia block. when compare 24% linear shrinkage of cast specimen with 20% linear shrinkage of CAD/CAM machined block, it was estimated that the size controlling of cast core was not so difficult. Conclusion: According to the all of this experimental results, the cast zirconia core produced from the remained parts of zirconia block was possible to use for all ceramic denture.】

Low-Invasive Implantable Devices of Low-Power Consumption Using High-Efficiency Antennas for Cloud Health Care

This paper presents low-invasive and low-power implantable biomedical devices based on a novel high-efficiency antenna for cloud health care. The proposed simple architecture was applied to fulfill a low-power consumption implantable system, including a readout circuit, an oscillator, a power management circuit, and an implantable antenna. This paper proposes a novel compact antenna for teeth implanting to attach on a low-invasive biomedical device to monitor human health conditions. A low-power consumption oscillator was connected directly to the antenna without any additional power amplifier. A hybrid of Archimedean spirals and Hilbert-based curve 3-D folded antenna was designed and fabricated on ceramic denture (ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) in Medical Radio (MedRadio) band. A compact, high gain, and large bandwidth antenna was achieved. In addition, such simple architecture also performs a high precise measurement, demonstrated by the temperature sensing of basal body temperature (BBT), indicating the conditions of female endocrine abnormalities. High sensitivity was enhanced by a negative resistance sample amplifier, and the biological BBT signals were transmitted by a frequency-modulation transmitter. The wireless measurement results indicate a small error of ±0.058°C at a distance of 60 cm indoors, and satisfy the BBT resolution requirement of 0.1 °C.

Pressure transmission and distribution under denture bases using denture teeth with different materials and cuspal angulations

Pressure transmission and distribution under denture bases may be variable depending on the different materials and cuspal angulations of denture teeth. The purpose of this study was to evaluate pressure transmission and distribution under impact load using denture teeth made with different materials and cuspal angulations. Three types (acrylic resin, microfilled composite resin, and ceramic) and 4 different cuspal angulations (0 degree, 20 degree, 33 degree, and 35 degree) of denture teeth were evaluated. Pressure transmission, distribution, and maximum pressure (n=10) were observed with pressure-sensitive sheets under an impact load. Data were statistically analyzed with 2-way ANOVA (α=.05) to determine significant interactions between denture tooth materials and cuspal angulations with respect to pressure transmission, followed by 1-way ANOVA (α=.05) to examine how materials and angulations jointly affected the pressure. Two 1-way ANOVAs were performed on the acrylic resin and ceramic denture teeth with the inclusion of 20-degree denture teeth groups. Tukey HSD and Tamhane's post hoc tests were used to evaluate data differences among groups. Denture tooth materials and cuspal angulations had significant interactions with respect to average pressure (P<.001) and maximum pressure transmission (P=.007). Zero-degree denture teeth showed significantly lower average and maximum pressures than 33- and 35-degree denture teeth for all 3 denture tooth materials (P<.001). Denture teeth with greater cuspal angulations demonstrated significantly higher average pressure transmission for all ceramic denture teeth groups (P<.05). Pressure transmission and distribution varied among denture teeth made of different materials and with different cuspal angulations. Cusped denture teeth presented significantly higher average pressure and maximum pressure transmission compared to 0-degree denture teeth.

Three-body wear of resin denture teeth with and without nanofillers

The wear behavior of newly developed denture teeth with nanofillers may be different from teeth with other chemical formulations. The purpose of this study was to examine the 3-body wear resistance of 11 different commercially available resin denture teeth. The materials tested were conventional (SR Orthotyp PE, Orthognath) and cross-linked acrylic resin teeth without inorganic fillers (Premium 8, SR Postaris DCL, Trubyte Portrait, Artiplus), composite resin teeth with inorganic fillers (SR Orthosit PE, Vitapan), and composite resin teeth (experimental materials) with inorganic nanofillers (NC Veracia Posterior, e-Ha, Mondial). Human enamel and a ceramic denture tooth (Lumin Vacuum) were used as reference materials. The 3-body wear test was performed in a wear machine developed by the Academic Center for Dentistry Amsterdam (ACTA), with millet suspension acting as an abrasive medium (n=10, test load: 15 N, slip rate: 20%, number of cycles: 100,000). Wear was determined with the aid of a profilometer. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test using the closed testing approach (significance level for familywise error rate, alpha=.05). None of the acrylic and composite resin materials tested in this study demonstrated the 3-body wear resistance of ceramic teeth or human enamel. Teeth with inorganic fillers demonstrated significantly lower wear values than conventional or cross-linked acrylic resin teeth without fillers. Composite resin teeth with traditional fillers showed significantly lower wear than composite resin teeth with nanofillers. Denture teeth with and without inorganic fillers differed significantly with regard to the degree of wear generated in the ACTA wear simulator. The incorporation of nanofillers did not improve the wear resistance compared to teeth with traditional fillers.

Pressure transmission and distribution under impact load using artificial denture teeth made of different materials

Pressure transmission and distribution under denture bases may be different depending on the material of the artificial denture teeth used. The purposes of this study were to evaluate pressure transmission and distribution under impact load using artificial denture teeth composed of different materials, and to examine the modulus of elasticity of the artificial denture teeth. The denture base specimens with artificial denture teeth made of 4 different materials (acrylic resin, microfilled composite resin, nanocomposite resin, and ceramic) were evaluated. Pressure transmission, distribution, and maximum pressure (n=10) were observed with pressure-sensitive sheets under an impact load. Modulus of elasticity of the artificial denture teeth (n=10) was measured by using an ultramicroindentation system. Data were statistically analyzed with 1-way ANOVA, followed by Tukey HSD and Tamhane's multiple range post hoc tests (alpha=.05). Maximum pressure transmission observed from ceramic denture teeth was significantly higher than that of other groups (P<.001). Nanocomposite resin denture teeth presented the lowest pressure transmission, whereas a localized stress transmission area was observed in the ceramic denture teeth group. Significant differences in the modulus of elasticity were observed among the 4 types of artificial denture teeth (P<.001). Pressure transmission and distribution varied among the denture tooth materials. Differences in the modulus of elasticity of each type of denture tooth were demonstrated.

Two-body wear of resin and ceramic denture teeth in comparison to human enamel

Objectives To evaluate the two-body wear resistance of different artificial denture teeth when opposed to steatite ceramic balls in a dual-axis chewing simulator. Methods Artificial denture teeth including the ceramic tooth Bonartic CT ®, the composite resin tooth Condyloform II NFC ®, the acrylic resin teeth Bonartic TCR ®, Orthognath ®, Polystar Selection ®, SR Orthotyp DCL ®, and Vitapan Cuspiform ®, and human maxillary premolars were tested in a chewing simulator. Wear resistance was analyzed measuring vertical substance loss and volume loss using profilometry and an optical macroscope after various chewing cycles (49 N, up to 1,200,000 cycles). Data were statistically analyzed using one-way analysis of variance (ANOVA) followed by the Fisher test (LSD) at p ≤ 0.05. Results After 1,200,000 chewing cycles the mean vertical substance loss and volume loss for the composite resin teeth (117 μm and 0.144 mm 3) were significantly lower than for all acrylic resin teeth (149–166 μm and 0.220–0.292 mm 3) ( p ≤ 0.05), but higher than for ceramic teeth (36 μm and 0.029 mm 3) and for enamel (56 μm and 0.033 mm 3) ( p ≤ 0.05). No significant differences were found among the acrylic resin teeth for both parameters ( p > 0.05). Significance The composite resin showed improved in vitro two-body wear resistance compared to modern acrylic resin denture teeth; however, it showed less wear resistance than ceramic teeth and human enamel. Ceramic teeth should be preferred over natural teeth when occlusal stability is considered a high priority.

A new approach to fabricating the occlusal surfaces of removable prostheses

A procedure is introduced to fabricate the occlusal surfaces of removable prostheses that oppose ceramic restorations or ceramic denture teeth. It involves the use of a heat-processed glass ceramic material in the form of onlays over the plastic denture teeth. This procedure provides for more wear compatibility, improved esthetics, and individualized occlusion. (J Prosthet Dent 1998;80:133-6.)