Scanning electron microscopy of tissue changes on the pressure surface of human premolars following tooth movement.

Abstract

abstract – The pressure side of human, premolars subjected to experimental movement for 5–76 d were studied in the scanning electron microscope. Sham‐operated and untreated premolars were used as controls. In order to study the morphology and occurrence of root resorptions, the organic tissue was removed using 1:2 diamino ethane or sodium hypochlorite and the denuded root surfaces were re‐examined in the scanning electron microscope. Areas of compressed soft tissue were regularly present and the size, shape and number of such zones varied in the experimental groups. Initially, tissue affected by pressure was mainly located in the marginal region and subsequently the mid‐portion of the roots became generally influenced. Removal of hyalinized tissue started shortly after the formation, and during this soft tissue removal the underlying hard tissue was resorbed. Observation of circumferentially removed, coalesced fibers corresponded with the finding of extensively resorbed lacunae in the mineralized tissue beneath. The resorptive processes of the cementum began after 10 d as round cavities measuring about 6 μm. Further resorption in cementum was characterized by numerous small, thin‐walled round lacunae which confluenced into extensive, shallow resorptions after 20 d. Dentin was distinguished by the presence of tubules, and in sites of active resorption removal of mineral crystals had occurred, exhibiting a latticed fiber arrangement.