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>

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.

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>