Walter A. Castelli

The effects of different splinting times on replantation of teeth in monkeys

The purpose of the study was to examine histologically the tissue changes affecting the teeth and surrounding structures after using both 7- and 30-day fixation periods on replanted teeth in monkeys. Eight adult male rhesus monkeys were used. The maxillary central and lateral incisors were extracted, treated endodontically, reimplanted, and temporarily immobilized with an interproximal acid-etch splint. The splints were removed at 1 week in half of the teeth and at 30 days in the other half. The monkeys were killed at 7 and 14 days, and at 1, 2, 3, 4, 5, and 6 months postoperatively. The results showed that replanted teeth that were splinted for 7 days recovered uneventfully, whereas the teeth that were splinted for 30 days demonstrated increased areas of root resorption and ankylosis. Thus, it is suggested that after tooth replantation the periodontium will repair rapidly with a shorter time of splinting (7 days). Extended splinting periods (30 days) seem to induce further root resorption and dentoalveolar ankylosis.

Removal of the Temporalis Muscle from Its Origin: Effects on the Size and Shape of the Coronoid Process

Removal of certain masticatory muscles from their mandibular attachment has produced a decrease in the size of the regions of insertion, particularly of the coronoid process and mandibular angle.1-5 In these studies, the temporalis, medial pterygoid, and masseter muscles were removed from their mandibular attachment or were almost totally extirpated. It has been concluded that the maintenance of the form of the bony processes to which these muscles attach is the result of muscle tension. Also, it has been shown that the arteries supplying the coronoid process, angle, and condyle of the rat, guinea pig, monkey, and man arise from vessels that supply the muscles attaching to these processes, and generally not from the inferior alveolar artery which primarily supplies the mandibular body and teeth.6-9 Therefore, it would seem that removal of the masticatory muscles from their mandibular attachment would eliminate the arterial supply to these bony processes. If, however, the blood supply of the mandible is maintained while direct muscle tension is decreased or eliminated by separating the masticatory muscles from their cranial attachment, the effect of the lack of muscle tension could be evaluated. It is the purpose of this study to note the effects on the coronoid process produced by removal of the temporalis muscle from its cranial origin.

Healing after tooth reimplantation in monkeys. A radioautographic study.

The purpose of this study was to examine radioautographically the dynamics of tissue changes during healing after reimplantation of maxilliary incisors in adult rhesus monkeys. The period selected for the study was 1 day to 4 months. The study revealed that a new attachment will be restored after tooth reimplantation. Epithelial tissues start to proliferate immediately after reimplantation; this proliferation reaches its peak in 3 days. After 7 days a new junctional epithelium is re-established. Connective tissue proliferation reaches its peak in 7 days and starts mainly from the supracrestal connective tissue and the bone marrow spaces. The interface is undetectable after 7 days, being replaced by young connective tissue which re-establishes the continuity of the periodontal membrane and the supracrestal connective tissue. Orientation and maturation of the fibers are not observed until 4 months after reimplantation. Changes toward root resorption and ankylosis can be seen as early as 14 days after reimplantation.

Interruption of the Arterial Inferior Alveolar Flow and its Effects on Mandibular Collateral Circulation and Dental Tissues

The interruption of circulation through the inferior alveolar artery was followed by the establishment of a fast retrograde blood flow through the vessel. The mental artery and the mandibular branch of the sublingual artery were the main vessels to contribute to that flow. No histopathologic changes were found in the experimental hemimandibles; however, temporary regressive changes were found in the dental pulps of molars.

Histopathologic findings in temporomandibular joints of aged individuals

Twenty-four TMJs from well preserved 62- to 97-year-old human cadavers, 12 men and 12 women, were used in this study. The TMJs were routinely processed to identify (1) the histologic and histopathologic changes present in the articulations and (2) the components of the joint most frequently affected by these changes. The most significant histopathologic findings were (1) intense fibrocartilaginous proliferations of the condylar head and articular eminence linings, (2) neovascularization or myxomatoid degenerative changes in articular disks, and (3) proliferation of synovial villi, subsynovial tissue, and muscular fibers. The components of the joint most frequently affected were (1) the condylar head (30.4%), (2) the articular disk (21.7%), (3) the synovial lining (13%), (4) the articular eminence (8.6%), and (5) the lining of the articular fossa (4.3%). Five joints were considered to be within normal histologic limits, and one joint was excluded from the study because of metastatic malignancy.

Long-term results after intentional tooth reimplantation in monkeys

The purpose of this study was to evaluate histologically the long-term response to intentional tooth reimplantation in six rhesus monkeys. The study revealed that cervical and apical root resorption is a universal complication after tooth reimplantation and that arrested areas of resorption will show repair by deposition of cementum. A highly cellular periodontal membrane usually will develop. Periodontal fibers will reattach to reparative bone and cementum but seldom regain functional orientation. Partial or complete ankylosis may result. A further complication is progressive undermining resorption of the ankylosed teeth. Long-term studies are mandatory to evaluate the response to intentional tooth reimplantation.

Revascularization of the Periodontium After Tooth Grafting in Monkeys

In replanted and homo transplanted teeth a vascular network developed in the blood clot between the two parts of the torn periodontium, which allowed the grafted ligament to regain its vascularity. When dentoalveolar ankylosis developed, the periodontal vasculature was split into a number of vascular clusters. In homotransplants, a definite cellular immunologic response by the host was absent. An acrylic radicular obturator was used.

The storage of teeth before reimplantation in monkeys: A histologic study

This study is a histologic comparison of twenty teeth which were extracted, endodontically treated, stored for 7 days at +4 degrees C. and at -10 degrees C., and subsequently reimplanted in ten monkeys. In these monkeys, as controls, ten more teeth were extracted, endodontically treated, and immediately reimplanted. Up to 1 year, 100 per cent success was obtained in those teeth stored at +4 degrees C. before reimplantation, and only 50 per cent success was obtained in those teeth stored at -10 degrees C. before reimplantation.

Effects of Composite Restorations on the Periodontal Membrane in Monkeys

We evaluated the histopathological response of the periodontal membrane to intentionolly-replanted teeth carrying composite (experimental) and silver amalgam (control) restorations in the middle third of each root. The study revealed that the amalgam produced, in the periodontal tissues, an initial localized inflammation that subsided with the subsequent formation of a fibrous capsule. However, the periodontal membrane adjacent to the composite resin restorations demonstrated chronic inflammation. It was concluded that the composite evoked chronic inflammatory responses of the periodontal tissues in monkeys.

Effect of renovascular hypertension on the morphology of oral blood vessels

Renovascular hypertension was created in twenty adult male rats to study the effects of systolic hypertension on the morphology of vessels supplying the gingiva, periodontal membrane, pulp tissue, and alveolar bone. Gingival arterioles showed changes consisting mainly of proliferation of the intima and elastic layers, some hyalinization of the wall, and reduction of the lumen. Similar but less frequent changes were observed in the vessels feeding the periodontal membrane; however, pulp tissue and alveolar arterioles were unaltered.