Maxillary sinus augmentation with simultaneous implantation using guided bone regeneration / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of new bone formation in sinus augmentation with guided bone regeneration (GBR) using collagen membranes.</p><p><b>METHODS</b>The first maxillary molars of 18 adult female Beagle dogs were extracted and the sinus floors of both sides were lifted with simultaneous implantation. A combination of autografts and Bio-Oss in a 2:1 ratio was placed in the space under the membrane. On the experimental side in each dog, the collagen membrane was folded at the lateral osteotomy window, the apex of the implants and a certain part of palatal bone. On the contralateral control side, the collagen membrane only covered the osteotomy window. Six animals were sacrificed at 4, 12, and 24 weeks respectively after surgery. Gross observation, biomechanical testing and histological examinations were performed.</p><p><b>RESULTS</b>The translocation of grafted materials and bone absorption were found on the top of implants in the control side, and the grafted materials kept original shape at the experimental side at 4th week. The granule of Bio-oss absorbed obviously at 12th and 24th week. The pull-out force increased with time. At 24th week, the force of pull out was 558.1 ± 37.4 N at the study side, and 471.4 ± 31.5 N at the control side. There was a significant difference in the pull-out force was noted between the two groups (P < 0.01). Histological examination showed new bone formation on the sinus floor, and the grafted materials gradually reduced with time</p><p><b>CONCLUSIONS</b>GBR with the enfolded-coverage of the membrane can effectively decrease absorption of the grafted materialon the apical surface of implants and stimulate new bone formation in the sinus augmentation.</p>

Influence of bone quality on the stress distribution for three-posterior immediately loaded implants: a three-dimensional finite element analysis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To assess and compare the peri-implant stress distribution of three posterior implants under immediate loading with 4 different bone qualities using three dimensional (3D) finite element (FE) analysis.</p><p><b>METHODS</b>A 3D finite element model representing three implants in a portion of mandible at the 654 region was developed, and three implants received a crown each. Four types of bone qualities (B1, B2, B3 and B4) were designed for the model. Load of 100 N was applied on the occlusal surfaces of the crowns at a 45° angle to the vertical axis of the implants.</p><p><b>RESULTS</b>Von Mises stresses in the peri-implant bone of 4 in bone quality from B1 to B4 were (13.17 ± 9.32), (12.95 ± 9.14), (15.00 ± 9.44), and (16.81 ± 10.74) MPa, and those of 5 were (15.51 ± 10.32), (14.73 ± 8.96), (16.79 ± 8.40), and (18.34 ± 8.45) MPa. Stress in bone quality B4 showed the highest value, followed by B3 bone, the lowest stress were found in B1 and B2 bone. It was significantly different (P < 0.05). However, von Mises stresses in different quality of bone around 6 [(42.45 ± 25.71), (41.66 ± 25.29), (42.70 ± 23.24), (42.06 ± 23.66) MPa] were close to each other, and were as twice or three times as those of 4 and 5, irrespective of different bone qualities.</p><p><b>CONCLUSIONS</b>The stress distribution around implant under immediate loading was not only affected by different bone qualities, but also by the direction of loading, and the latter may have a greater impact when a severe load delivered.</p>

CT multiplanar image anatomic study on orbital bone used for implant operation / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the orbital bone quantity by spiral computer tomography (CT) for orbital implant operation.</p><p><b>METHODS</b>Fifty-two normal skull specimens with marks received spiral CT scan and their multiplanar images were obtained. The quantity (length x width) were measured on multiplanar images.</p><p><b>RESULTS</b>The right orbital bone quantity at 7:00 was the highest, average 11.91 mm x 8.38 mm, and at 3:00 was the lowest, average 2.31 mm x 1.34 mm. The left orbital bone quantity at 5:00 was the highest, average 12.03 mm x 8.56 mm, and at 9:00 was the lowest, average 2.44 mm x 1.29 mm. There had no significance correlation with gender at the same position in both sides.</p><p><b>CONCLUSION</b>Useful data had been obtained for the selection of the placement sites, direction, length, and diameter of orbital implants.</p>

Clinical application of computer assisted technology based spiral CT scan for locating impacted tooth / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate clinical value of computer assisted technology for locating the impacted tooth.</p><p><b>METHODS</b>Thirty-five patients with impacted tooth were received spiral CT scan. The DICOM data were processed by Simplant software for locating the impacted tooth.</p><p><b>RESULTS</b>The reconstruction images clearly showed detail of the impacted teeth, including 3D surface image, eruption orientation, buccal and lingual location, medial and distal location and relationship with dentition and circumambient anatomic structure.</p><p><b>CONCLUSION</b>The computer assisted technology can localize the impacted tooth precisely and provide valuable information for clinical treatment.</p>