Todescan Francisco F, Pustiglioni Francisco E, Imbronito Ana V, Albrektsson Tomas, Gioso Marco
Department of Periodontology, Dental School, University of São Paulo, Brazil.
Int J Oral Maxillofac Implants. 2002 Jul-Aug;17(4):467-72.
The purpose of this study was to examine the dimensions and relationships of the peri-implant tissues surrounding osseointegrated 2-stage implants placed at different depths in bone.
Twenty-four implants were placed in the mandibles of 4 mongrel dogs. A modification of the surgical protocol was introduced so that in group I, implants remained 1 mm above the bone crest, in group II, implants were placed level with the bone crest; and group III implants were countersunk to approximately 1 mm below the bone crest. After 3 months, abutment operations were carried out with the placement of 3-mm standard abutments. Following a healing period of 3 months the dogs were sacrificed. A total of 20 implants were available for histometric analysis. Non-decalcified sections were evaluated for the dimensions of the junctional epithelium, connective tissue band, marginal bone level, and bone-to-metal contact.
Histologic observations showed a mucosal barrier consisting of keratinized oral epithelium continuous with a thin junctional epithelium facing the implant and abutment surface. Junctional epithelium showed a mean of 1.67 mm for group 1, 1.93 mm for group II, and 2.78 mm for group III. These values were not statistically different. The band of connective tissue had a mean of 1.13 mm for group 1, 0.92 mm for group II, and 1.60 mm for group III. These values were not statistically different, except for group II versus group III. Bone level had a mean of 2.50 mm for group 1, 2.30 mm for group II, and 1.60 mm for group III. These differences were significant between groups I and III. The surface of bone contact along the implant (BMC%) showed mean values of 46.8% in group 1, 53.7% in group II, and 49.0% in group III (no significant differences among the 3 groups).
There was a clear tendency of the epithelium and connective tissue to be longer the deeper the implants were placed, although those differences were not statistically significant. Bone loss was smaller for group III (countersink group). This is not in accordance with recent articles which have stated that bone will maintain its biologic width.
When the microgap between implants and abutments was placed deeper in the bone, additional bone loss did not result.
本研究旨在检查植入骨内不同深度的骨结合型二期种植体周围的种植体周组织的尺寸及关系。
将24枚种植体植入4只杂种犬的下颌骨。引入了一种手术方案的改良方法，使得在第一组中，种植体位于牙槽嵴顶上方1mm处；在第二组中，种植体与牙槽嵴顶平齐；在第三组中，种植体沉入牙槽嵴顶下方约1mm处。3个月后，进行基台手术，安装3mm标准基台。经过3个月的愈合期后，处死实验犬。共有20枚种植体可用于组织计量学分析。对未脱钙切片进行评估，以测量结合上皮、结缔组织带、边缘骨水平以及骨与金属接触的尺寸。
组织学观察显示，存在一个黏膜屏障，由角化的口腔上皮构成，与面向种植体和基台表面的薄结合上皮连续。结合上皮在第一组的平均值为1.67mm，第二组为1.93mm，第三组为2.78mm。这些值在统计学上无差异。结缔组织带在第一组的平均值为1.13mm，第二组为0.92mm，第三组为1.60mm。除了第二组与第三组外，这些值在统计学上无差异。骨水平在第一组的平均值为2.50mm，第二组为2.30mm，第三组为1.60mm。第一组和第三组之间的这些差异具有统计学意义。沿种植体的骨接触表面（BMC%）在第一组的平均值为46.8%，第二组为53.7%，第三组为49.0%（三组之间无显著差异）。
尽管这些差异在统计学上不显著，但上皮和结缔组织有一个明显的趋势，即种植体植入越深，其长度越长。第三组（沉入组）的骨吸收较小。这与最近一些文章中所述的骨将维持其生物学宽度不一致。
当种植体与基台之间的微间隙置于骨内更深位置时，不会导致额外的骨吸收。
