An in vitro cytotoxicity study of colorized zirconia by immersion method / 实用口腔医学杂志

Objective:To evaluate the cytotoxicity of colorized zirconia ceramics.Methods:Zirconia ceramic 3Y-TZP blocks were colorized by NH4 VO3 ,FeCl3 ,Co(NO3 )3 ,Ni(NO3 )3 and MoCl3 respectively.The cytotoxicity of colorized zirconia to L-929 cells was examined by immersion method and MTT assay.Results:During 3 days culture,L929 cells in all groups showed similar prolifera-tion and normal morphology.The toxicity gradation of all groups was 0 -I.Conclusion:Zirconia ceramics colorized with the 5 kinds of colorants has no cytotoxicity.

Clinical evaluation of four different impression methods with vinyl polysiloxane / 实用口腔医学杂志

94 cases with 148 abutments treated by all-ceramic restoration in premaxillary teeth region were randomly divided into 4 groups, and the impressions were prepared by one-step method,double curettage method,double polish method and double microfilm method respec-tively using 3M ESPE Vinyl polysiloxane as impression material.The cervical margin precision of the impressions was compared.Four kinds of impression method can produce qualified impression.Double polish method is easy to teach and learn.

Effect of different polymerization methods on shear bond strength between polymethyl methacrylate and silicone soft liner / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare shear bond strength (SBS) between two types of silicone soft liner and polymethyl methacrylate (PMMA) under the condition of heat curing and room temperature curing.</p><p><b>METHODS</b>A total of 48 PMMA specimens (50 mm x 10 mm x 3 mm) were made by water-bath heating method, and randomly divided into four groups. By using Ufi Gel P (UGP) as soft liner material, group A1 was prepared under heat curing, and group A2 was prepared under room temperature curing. To form the other two groups, Silagum-Comfort (SLC) as soft-liner material was used. Group B1 was prepared under heat curing, and group B2 was prepared under room temperature curing. Shear bond strength (SBS) was tested by using the electronic universal testing machine. The adhesives layer and surface of silastic and PMMA were observed by optical microscope and scanning electron microscopy (SEM).</p><p><b>RESULTS</b>The SBS of groups A1, A2, B1, B2 were (2.39 +/- 0.24), (1.74 +/- 0.27), (3.09 +/- 0.26), and (2.21 +/- 0.29) MPa, respectively. Significant differences were found between A1 and A2, B1 and B2, A1 and B1, and A2 and B2 (P < 0.05). Optical microscope showed numerous bubbles in the cured UGP, and no air bubbles in the SLC. The surface of PMMA was rough. SEM images showed that each group had continual consistent adhesive interface and a whisker hump on the adhesive layer of A2 and B2.</p><p><b>CONCLUSION</b>The SBS ofUGP, SLC, and PMMA achieved minimum clinical standard of 0.44 MPa. The SBS of UGP and PMMA were higher than that of SLC and PMMA. The polymerization method of heat curing was higher than room temperature curing.</p>

Cytotoxicity and antibacterial effect of silicone-based soft liner varnish containing Ag/TiO2: an in vitro study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>We aim to evaluate the cytotoxicity and antibacterial effects of Silagum-Comfort (SLC) silicone-based soft liner varnish containing Ag/TiO2 in vitro.</p><p><b>METHODS</b>Silicone-based liner circular specimens, with a diameter of 10 mm and a thickness of 2 mm, were created and divided into six groups randomly. Ag/TiO2 was incorporated into the SLC varnish based on the agent/material weight rate of 0, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%. The mixed varnish was used to polish the SLC specimens. Antibacterial specimens (ATSLC) were created. Methyl thiazolyl diphenyl-tetrazolium bromide assay method was used to evaluate the 3T3 cell cytotoxicity of ATSLC in vitro. Surface roughness (Ra) measurements of ATSLC were obtained. The antibacterial effect of ATSLC on Candida albicans was examined using the pelliclesticking method.</p><p><b>RESULTS</b>The cytotoxicity of ATSLC was graded from 0 to 2. The Ra of ATSLC increased when Ag/TiO2 agent concentration increased. However, the differences were not statistically significant compared with the 0 group. With increasing Ag/TiO2 concentration, the antibacterial agent concentration and the antibacterial rate of ATSLC also increased. When the Ag/TiO2 antibacterial agent concentration reached 2.0% and 2.5%, the antibacterial rate increased to 97.5% and 96.5, respectively.</p><p><b>CONCLUSION</b>Varnish containing Ag/TiO2 has excellent antibacterial effect and can significantly improve the antibacterial effect of silicone-based soft liner.</p>

Color stability of ceromer veneers/resin cements after accelerated ageing / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the color stability of ceromer veneers/resin cements after accelerated ageing, and to provide the reference for clinical application and choice.</p><p><b>METHODS</b>Fifteen groups of ceromer veneers/resin cements samples, five samples in each group, were prepared as experimental groups.In the fifteen groups, ceromer veneers in three thickness (1.00, 0.75, 0.50 mm) and resin cements of five shades(A1,A3, B 0.5, WO, TR), were matched through permutation and combination. Three groups of ceromer veneers with different thickness (1.00, 0.75, 0.50 mm) were used as control groups. All samples were put into xenon lamp ageing instrument to accelerate ageing.Spectrophotometer were used to measure the lightness(L(*)), red green color(a(*)) and blue yellow color(b(*)) of samples before and after accelerated ageing process, and the change of lightness (ΔL) , red green color (Δa) , blue yellow color (Δb) and color variation(ΔE) were calculated.We investigated the effect of thickness of ceromer veneer and color of resin cement on color variation by using analysis of variance.</p><p><b>RESULTS</b>The thickness factor and color factor showed significant effect on ΔE values, and they have interaction (P < 0.05). The ΔE values of all experimental groups were lower than 3.3. After accelerated ageing, all L(*) values of experimental groups decreased, and ΔL values were lower than 2.0.</p><p><b>CONCLUSIONS</b>The thickness of ceromer veneer and the color of resin cement could both affect the color stability of ceromer veneers/resin cements. The changes of lightness and color in ceromer veneers/resin cements were considered clinically acceptable after accelerated ageing.</p>

Occlusal reconstruction of a patient with hypohidrotic ectodermal dysplasia / 华西口腔医学杂志

Prosthodontic treatment for patient with hypohidrotic ectodermal dysplasia (HED) is difficult to manage because of the loss of occlusal vertical dimension, abnormal alveolar ridge and anodontia A 20-year-old case with HED was reported. The patient was treated with occlusal reconstruction by a maxillary fixed prosthesis and mandibular telescopic prosthesis. At one-year's follow-up, dentures were well used and occlusal function of the patient returned to normal.

Prosthodontic treatment on mandibular fracture with poor healing: a case report / 华西口腔医学杂志

A mandibular fracture case of twice internal fixation surgery with poor healing was treated by denture prosthodontics in Affiliated Stomatological Hospital of Nanchang University. The profile of maxillofacial region was improved, the masticatory function was enhanced, and the new bone formation was promoted.

The influence of methacryloxy propyl trimethoxyl silane on shear bond strength of three kinds metal and Filtek resin / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the influence of three different metal alloy surfaces treated with primer methacryloxy propyl trimethoxyl silane (gamma-MPS) coupling agent on the bond strength of Filtek Z350 resin.</p><p><b>METHODS</b>Total 36 specimens of nickel-chromium(Ni-Cr) alloy, pure titanium(Ti) and aurum-palladium(Au-Pd) alloy, each of 12 pieces produced by lost wax casting method, were divided into 6 groups. After treated with gamma-MPS on the bonding surface, experimental group samples were adhered to Filtek Z350 resin, then compared with the surface without gamma-MPS treatment. The tensile and shear strength of each group tested and the fracture sections were observed with scanning electron microscope (SEM).</p><p><b>RESULTS</b>Comparing the Ni-Cr alloy and pure Ti experimental group with them in control group, the shearing strength of the experimental group was higher, and the differences were significant (P < 0.001). The shearing strength of the experimental group and control group of Au-Pd alloy were not significant (P > 0.05). Comparing the experimental groups, the shearing strength of pure Ti was higher than Ni-Cr alloy, both were higher than Au-Pd alloy (P < 0.01). These entire specimens were adhesive fracture. Comparing with the control group, Ni-Cr alloy and pure Ti experimental group showed more resin juts in the fracture surface, while the Au-Pd alloy in experimental group showed less resin juts.</p><p><b>CONCLUSION</b>gamma-MPS can enhance the adhesion between metal and resin, but it is also related to the metal composition. gamma-MPS can significantly increase the bond strength of resin and Ti or Ni-Cr alloy, but not the case of Au-Pd alloy and resin.</p>