Effect of anatomical parameters of maxillary sinus on the outcomes of transcrestal sinus lift / 华西口腔医学杂志

OBJECTIVE@#To investigate the effect of three anatomical parameters (maxillary sinus width, maxillary sinus angle, and residual bone height) on the outcomes of transcrestal sinus lift with simultaneous implant placement.@*METHODS@#A total of 60 maxillary sinuses in 42 patients were included in this study. All patients were treated with transcrestal sinus lift procedure associated with simultaneous implant placement using a composite graft material of autogenous bone and Bio-Oss. For each patient, beam computed tomography (CBCT) scans were performed preoperatively, immediately after surgery, and 6 months after surgery. The parameters were measured on the preoperative and postoperative CBCT images. The correlation of three anatomical parameters with graft resorption was analyzed using Pearson's correlation test.@*RESULTS@#The average residual bone height was (4.46±1.55) mm. The average width of maxillary sinus was (13.86±2.71) mm. The average sinus angle was 78.09°±10.27°. A significant positive correlation was observed between maxillary sinus width and graft resorption (P<0.01). A positive association was also found between sinus angle and graft resorption (P<0.01).@*CONCLUSIONS@#The findings show that graft bone resorption in elevated sinus has a positive correlation with the sinus width and sinus angle.

Finite element contact stress analysis of simulating teeth with wedge shaped defects in the cervical region / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the distribution of stress of simulating teeth with wedge shaped defects in the cervical region.</p><p><b>METHODS</b>The models of anisotropic enamel of the mandibular first premolar and the opposite maxillary first premolar crown were created. A defect was introduced into the model of mandibular premolar in the buccal cervical region along the enamelo-dentinal junction (DEJ). The stress distribution in the cervical region of the mandibular premolar was investigated considering lateral condition simulating working micromotions. In this case, the stroke was applied to the maxillary first mandibular in a stepping procedure using nonlinear contact analysis.</p><p><b>RESULTS</b>The stresses were concentrated in the defect of the enamel and dentin at the DEJ in the condition of lateral loading. As the defect length increased in size, the peak maximum principal stress (MPS) value and the magnitude of the stress field along the DEJ both increased.</p><p><b>CONCLUSION</b>Undermined cervical DEJ had a significant effect on the stress distribution in the buccal cervical region.</p>

Effects of laser welding on bond of porcelain fused cast pure titanium / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium.</p><p><b>METHODS</b>Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison.</p><p><b>RESULTS</b>No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement.</p><p><b>CONCLUSIONS</b>Laser welding does not affect low-fusing porcelain fused to pure titanium.</p>

Structural characteristics of laser-welded cast pure titanium joints by different gap distance / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the microstructure of laser-welded cast pure titanium by different gap distance.</p><p><b>METHODS</b>Forty specimens were sectioned and welded at four gaps (0.00 mm, 0.25 mm, 0.50 mm and 1.00 mm). Took microhardness test and metallographic examination of welded zone surface.</p><p><b>RESULTS</b>There were no difference in microhardness value and metallographic observation between welded specimens. The width of heat-effected zone was different. The smaller grains and needle-like alphamartensitic structure were found in the heat-affected zone.</p><p><b>CONCLUSION</b>The effects of the joint gap were not significant.</p>