Читать книгу Biological Mechanisms of Tooth Movement - Группа авторов - Страница 30

Oppenheim (1911) conducted OTM on a juvenile baboon, wherein he performed all sorts of tooth movements (labial, lingual, intrusion, extrusion, and rotation), with a split mouth design (where one side of the dental arch is operated upon, while the other side serves as control). He processed the jaw tissues histologically, and concluded that

The bony tissue, be it compact or cancelleous, reacts to pressure by a transformation of its entire architecture; this takes place by resorption of the bone present and deposition of new bony tissue; both processes occur simultaneously. Deposition finally preponderates over resorption. The newly formed bony spicules are arranged in the direction of the pressure [Figure 2.6]. Increased pull has similarly resulted in addition of new bony tissue as a result, and simultaneous orientation of the spicules thereof in the direction of the pull [Figure 2.7]. The entire transformation of the architecture and the orientation of the newly formed spongy bone spicules always occur so characteristically and lawfully, that we can say by the histological preparations in what manner the movements were accomplished. This characteristic transformation results only upon the application of very slight, physiological‐like influences. Should the force be too strong, the result will be such serious injuries to the periosteum, due to the disturbances in circulation, that there will be no typical reaction of the bony cells.

Figure 2.6 Histologic section from the original article by Oppenheim (1911). Lingual movement; lingual side of the PDL, where it forms compression. The individual newly formed bone spicules (k¹) have arranged themselves in the direction of the force, perpendicular to the long axis of the tooth. The ends of the spicules directed toward the tooth: the ends subjected directly to the pressure show broad, uncalcified zones (cG), which are surrounded by densely arranged rows of osteoblasts (ob). At the ends of the spicules directed from the tooth, occasionally numerous osteoclasts are seen. a, dentine; b, cementum; g, PDL; ok, osteoclasts; nearer to the apex of the root old unchanged bone (k).

(Source: Oppenheim, 1911. Reproduced with permission of Oxford University Press.)

Oppenheim substantiated his findings by drawing support from Wolff ’s law, and his investigations could not find any injury in the PDL. He concluded that, in OTM, all mechanical forces applied to a tooth are absorbed by the PDL, and at times he could observe a hypertrophy to withstand the increased demand placed upon it. Unlike Sandstedt, Oppenheim reported on seeing no hyalinization or undermining resorption in his experimental material. He further wrote that “The vitality of the periosteum suffers no injury during the application of “physiological forces,” even on compression of the PDL to a third of its original thickness. It may be exposed to slight hemorrhages, to occasional constriction in the lumen, or disappearance of the vessels, but the staining ability of the cell nuclei is retained, and no disintegration can be demonstrated by any photographs.