Replantation Of Incisors Research Articles

Reprint of: Relationship Between Surface and Inflammatory Resorption and Changes in the Pulp After Replantation of Permanent Incisors in Monkeys

The etiology of surface and inflammatory root resorption after the replantation of incisors was examined in green vervet monkeys. The teeth were examined histologically and histobacteriologically for pulpal healing and root resorption 2 and 8 weeks after replantation. In contrast to surface resorption, inflammatory resorption was related to infected necrotic tissue or an infected leukocyte zone in the root canal. The following theory for surface and inflammatory resorption is presented. Damaged periodontal ligament areas and damaged parts of the root surface are attacked by a resorption process whereby resorption of cementum and dentin may occur. Inflammatory resorption or surface resorption will then occur depending on the pulpal status and the depth of the resorption cavity. If the resorption cavity penetrates the intermediate layer of cementum and contacts dentinal tubules that are in communication with infected necrotic pulp tissue or an infected leukocyte zone, then inflammatory resorption will take place as a result of the diffusion of toxic elements from the pulp canal to the resorption cavity. However, if the resorption cavity is shallow and does not penetrate the intermediate layer of cementum, a tooth that displays similar pulpal changes will elicit only surface resorption because the intermediate layer of cementum will tend to arrest the diffusion of toxic elements. Finally, if the pulp contains vital, inflamed, or noninflamed tissue or if root canal treatment has been performed, surface resorption will occur regardless of the depth of the cavity.

Effects of temperature, storage time and media on periodontal and pulpal healing after replantation of incisors in monkeys.

The effect of temperature of various storage media and at varying storage periods upon periodontal ligament (PDL) and pulpal healing after tooth replantation was examined in green vervet monkeys (Cercopithecus aethiops). Mandibular lateral incisors with mature root formation were extracted and kept in dry storage at 22, 4 and -18 degrees C; in saline at 37, 22, 4 and -18 degrees C; or in saliva (i.e. in the buccal vestibule) at 37 degrees C for either 60 or 120 min prior to replantation. The animals were sacrificed 8 weeks after replantation and the replanted teeth examined histometrically. The following histological parameters were registered for each tooth: normal PDL, surface resorption, inflammatory resorption, replacement resorption (ankylosis), downgrowth of pocket epithelium, periapical inflammatory changes, and the extent of vital pulp. A total of 125 replanted teeth were examined. Storage in saliva at 37 degrees C showed a similar amount of normal PDL compared to saline storage for both 60 and 120 min. Saline storage for 60 or 120 min showed no difference in the extent of normal PDL when storage was compared at 37, 22 and 4 degrees C. However, storage at -18 degrees C resulted in significantly less normal PDL than storage at other temperatures. Dry storage for 60 min showed significantly less root resorption at 4 degrees C compared to 22 degrees C. Furthermore, dry storage at -18 degrees C showed significantly less normal PDL than storage at 4 degrees C. When the dry storage period was extended to 120 min, no difference was found between 22, 4 and -18 degrees C. It is concluded that the temperature (above 0 degrees C) of the storage medium is of importance only for dry storage and in such a situation only for shorter extra-alveolar periods, i.e. for 60-min storage and not for 120 min, where extensive destruction of the PDL always takes place. It is suggested that the temperature effect of 4 degrees C could be related to less evaporation from the PDL and thereby less damage to the PDL cells or a strict temperature effect upon cell metabolism. Pulp healing in all the cases was limited to the entrance of the pulp canal, and no significant pattern was found between storage media, time and temperature.

Influence of root development on periodontal and pulpal healing after replantation of incisors in monkeys

The influence of root development on periodontal and pulpal healing after replantation was examined in 30 green vervet monkeys (cercopithecus aethiops) in which a total of 50 teeth were replanted. Maxillary central incisors with different stages of root development (immature, young mature and mature root formation) were replanted with untreated pulps or after root canal treatment with gutta percha and Kerr® sealer. The extra-alveolar period in all groups was 18 min. The animals were sacrificed 8 weeks after replantation and the teeth examined histologically. The following histologic parameters were registered for each tooth: surface resorption, inflammatory resorption, replacement resorption (ankylosis), downgrowth of pocket epithelium, periapical inflammatory changes and extent of vital pulp. Histologic analysis showed that the extent of vital pulp was significantly related to the stage of root development, being almost complete in teeth with immature roots and almost totally lacking in young mature and mature teeth. Surface resorption was found with the same frequency in the different root development groups while inflammatory resorption was slightly more frequent in young mature teeth than in mature teeth, a finding possibly related to a protective action of a thick cementum layer in the mature teeth. Replacement resorption was found with almost the same frequency in the different root development groups in non-endodontically treated teeth. As ankylosis is the most important factor determining the prognosis of replanted and autotrans-planted teeth, the present findings indicate that replantation and auto-transplantation of mature teeth could be of clinical use.

Relationship between surface and inflammatory resorption and changes in the pulp after replantation of permanent incisors in monkeys

The etiology of surface and inflammatory root resorption after the replantation of incisors was examined in green vervet monkeys. The teeth were examined histologically and histobacteriologically for pulpal healing and root resorption 2 and 8 weeks after replantation. In contrast to surface resorption, inflammatory resorption was related to infected necrotic tissue or an infected leukocyte zone in the root canal. The following theory for surface and inflammatory resorption is presented. Damaged periodontal ligament areas and damaged parts of the root surface are attacked by a resorption process whereby resorption of cementum and dentin may occur. Inflammatory resorption or surface resorption will then occur depending on the pulpal status and the depth of the resorption cavity. If the resorption cavity penetrates the intermediate layer of cementum and contacts dentinal tubules that are in communication with infected necrotic pulp tissue or an infected leukocyte zone, then inflammatory resorption will take place as a result of the diffusion of toxic elements from the pulp canal to the resorption cavity. However, if the resorption cavity is shallow and does not penetrate the intermediate layer of cementum, a tooth that displays similar pulpal changes will elicit only surface resorption because the intermediate layer of cementum will tend to arrest the diffusion of toxic elements. Finally, if the pulp contains vital, inflamed, or noninflamed tissue or if root canal treatment has been performed, surface resorption will occur regardless of the depth of the cavity.

The effect of limited drying or removal of the periodontal ligament. Periodontal healing after replantation of mature permanent incisors in monkeys.

The effect of limited drying or removal of the periodontal ligament upon periodontal healing after replantation of incisors was studied in green Vervet monkeys. All teeth were examined histologically either 2-, 4- or 8 weeks after replantation. The drying experiment demonstrated that an area of ankylosis was established after 2 weeks corresponding to the dried portion of the root and was removed by a resorptive process in the majority of cases after 8 weeks. The removal of the periodontal ligament led to development of surface-, inflammatory- and replacement resorption. Furthermore, 1 mm2 and 4 mm2 lesions on the root surface developed transient ankylosis which disappeared after 8 weeks while lesions of 9 mm2 or 16 mm2 in size resulted in an ankylosis which, in most cases, persisted after 8 weeks. Based on these findings, it is postulated that physical removal or extended drying of the periodontal ligament initiates a rapid osteogenesis in the alveolus which establishes an ankylosis. If the damaged area is placed next to a zone on the root surface with a vital periodontal ligament, a later resorptive process is established from this zone, whereby the ankylosis area is gradually resorbed. It is estimated that the extent of this process in this experiment amounted to possibly 1 -- 1.5 mm.