| Objective:The aim of the present study was to compare and evaluate the outcomes of internal maxillary sinus floor elevation with simultaneous implants placement by the Disk-up Sinus Reamer (DSR) and osteotome. The animal model was established, in order to explore the feasibility and superiority of the Disk-up Sinus Reamer (DSR) applied to internal maxillary sinus floor elevation and to provide an evidence for clinical application.Methods:Thirty fresh skulls of adult goats were chosen and numbered randomly. The third premolar, the first and the second molars of bilateral maxillae were extracted and the alveolar ridge was leveled off. One side of the skulls was randomly chosen as the experimental side, on which the Disk-up Sinus Reamer was used, while the other side was the control side, on which the osteotome was used. Then all the implantation sites were divided into three groups according to the elevation height, namely,3 millimeters for group A,5 millimeters for group B and 8 millimeters for group C. One hundred and eighty implants (Osstem GSⅡ) were placed in designed order immediately after the elevation operation. X-Ray was taken to show the radiographic appearances of the maxillary sinus floor after elevation. Gross observation was made to check the integrity of the sinus membrane at different elevation height on both sides, to calculate the perforation ratios and to observe the shape of the bone fragments separated from the sinus floor by DSR and osteotome. Implant stability of each site was measured. Paraffin sections of sinus membrane were made for histomorphological analysis. Data were statistically analyzed.Results:(1) Microscopic observation showed that the maxillary sinus floor membranes of both goat and human were mucoperiosteum, consisting of pseudostratified ciliated columnar epithelium, lamina propria and periosteum. The thickness of membrane in goat was about 0.9 millimeters, while 0.8 millimeters in human. (2) X-Ray showed that the endo-sinus part of the implants on the experimental side was closely surrounded by the bone grafts, presenting hemispherical bumps, while the bone grafts were mainly located above the root terminal of the implants on the control side.(3) The perforation ratios of group A, B and C were 3.33%,3.33%,6.67% respectively on the experimental side, with no significant difference between each other. On the control side, the perforation ratios of group A, B and C were 3.33%,3.33%,6.67% respectively, and the perforation ratio of group C was significantly different from that of group A and B, while there was no significant difference between that of group A and B. The perforation ratio of group C on the experimental side was significantly different from that on the control side, while for group A and B, there was no significant difference between the two sides.(4) The implant stability (ISQ) of group A, B and C were 75.41±5.90,72.48±5.36. 63.25±6.86 respectively on the experimental side, and the ISQ of group C was significantly different from that of group A and B, while there was no significant difference between that of group A and B. On the control side, the ISQ of group A, B and C were 73.33±6.13.67.14±5.10,49.68±6.87 respectively, and there was significant difference between each other. The ISQ of group B and C on the experimental side were significantly different from that on the control side, while for group A, there was no significant difference between the two sides.(5) Bone fragments separated from the sinus floor by DSR took on a dissociative disciform shape, with a regular and smooth rim. By contrast, bone fragments on the control side were irregular in shape, with acuminate cusps.Conclusions:With in the limits of the present study, it can be concluded that:(1) The anatomical and histological structures of maxillary sinus membrane in goats are similar to those in humans. Goat can be considered as an applicable animal model for maxillary sinus floor elevation.(2) Disciform bone fragment separated from the sinus floor by DSR helps to reduce the risk of membrane perforation, and to overcome some disadvantages of osteotome, such as blindness and suffering caused by striking.(3) The DSR can deliver bone grafts deep inside the hole, and scatter them evenly around the implants, contributing to increase the primary stability of the implants to some extent.(4) The DSR shows significant advantages in the event of a lower residual bone height (<5mm)or a higher elevation height(>5mm), widening the application scope of internal maxillary sinus floor elevation.(5) Internal maxillary sinus floor elevation with simultaneous implants placement by DSR proves to be a practicable and credible approach, and will make guidance to clinical application. |
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