Department of Periodontology, The Forsyth Institute, Cambridge, MA 02142, USA.
J Periodontol. 2011 Sep;82(9):1339-52. doi: 10.1902/jop.2011.100617. Epub 2011 Feb 22.
The present study is designed as a proof-of-concept study to evaluate light/chemical hardening technology and a newly formulated polymethylmethacrylate, polyhydroxyethylmethacrylate, and calcium hydroxide (PPCH) plus polyanhydride (PA) (PPCH-PA) composite graft material as a bone substitute compared to positive and negative controls in a minipig model.
PPCH-PA (composite graft); PPCH alone (positive control), PA alone (positive control), and no graft (negative control) were compared. Four mandibular premolar teeth per quadrant were extracted; a total of 48 implants were placed into sockets in three minipigs. Abutments were placed protruding into the oral cavity 4 mm in height for immediate loading. Crestal areas and intrabony spaces were filled with PPCH-PA, PPCH, or PA using a three-phase delivery system in which all graft materials were hardened by a light cure. In the negative control group, implant sites were left untreated. At 12 weeks, block sections containing implants were obtained. Evaluations included periodontal probing, pullout-force load, and stability measurements to determine implant stability, radiographs to examine bone levels, and scanning electron microscopy (SEM)-energy-dispersed spectroscopy to determine bone-to-implant contact.
Probing measurements did not reveal any pathologic pocket formation or bone loss. Radiographs revealed that immediate implant placement and loading resulted in bone at or slightly apical to the first thread of the implant in all groups at 12 weeks. Stability test values showed a relative clinical stability for all implants (range: -7 to +1); however, implants augmented with PPCH-PA exhibited a statistically significantly greater stability compared to all other groups (P <0.05). The newly formed bone in PPCH-PA-treated sites was well organized with less marrow spaces and well-distributed osteocytes. SEM revealed a tighter implant-socket interface in the PPCH-PA group compared to other groups with reduced microfissures and implant-bone interface fractures during pullout testing, whereas implants treated with PA or no graft showed ≈ 10-μm microfissures between the implant and bone with fractures of the intrathread bone.
The newly formulated chemically hardened graft material PPCH-PA was useful in immediate implant placement after tooth extraction and resulted in greater stability and a well-organized implant-bone interface with immediate loading, especially in those areas where cancellous bone was present. The results of this proof-of-concept study warranted further research investigating different healing times and longer durations.
本研究旨在通过小型猪模型，评估光/化学固化技术及新型聚甲基丙烯酸羟乙酯/聚羟乙基甲基丙烯酸钙/聚酸酐（PPCH-PA）复合材料作为骨替代物与阳性和阴性对照物相比的效果。
PPCH-PA（复合材料移植物）；单独的 PPCH（阳性对照）、单独的 PA（阳性对照）和无移植物（阴性对照）进行了比较。每象限四颗下颌前磨牙被拔出；总共在三只小型猪中植入 48 颗种植体。将种植体植入牙槽窝内，高出牙龈 4mm，进行即刻负载。使用三相输送系统在嵴顶区和骨内间隙填充 PPCH-PA、PPCH 或 PA，所有移植物材料均用光固化法硬化。在阴性对照组中，种植体部位未进行处理。在 12 周时，获得含有种植体的块状标本。评估包括牙周探查、拔出力负荷和稳定性测量以确定种植体稳定性、放射线照相术检查骨水平以及扫描电子显微镜（SEM）-能谱分析以确定骨-种植体接触。
探查测量未发现任何病理性牙周袋形成或骨丢失。放射线照相术显示，在所有组中，即刻种植体放置和加载在 12 周时导致骨在种植体的第一个螺纹处或稍位于其上方。稳定性测试值显示所有种植体均具有相对临床稳定性（范围：-7 至+1）；然而，用 PPCH-PA 增强的种植体与所有其他组相比具有统计学上更大的稳定性（P<0.05）。PPCH-PA 治疗部位新形成的骨组织排列整齐，骨髓腔较少，骨细胞分布均匀。SEM 显示，与其他组相比，PPCH-PA 组的种植体-牙槽窝界面更紧密，在拔出试验中减少了微裂缝和种植体-骨界面骨折，而用 PA 或无移植物处理的种植体显示出约 10μm 的种植体-骨之间的微裂缝，并有骨内螺纹骨折。
新型化学固化移植物材料 PPCH-PA 可用于拔牙后即刻种植体放置，并在即刻负载时可提供更大的稳定性和组织良好的种植体-骨界面，尤其是在存在松质骨的区域。这一概念验证研究的结果证明需要进一步研究不同的愈合时间和更长的时间。
