The radiographic assessment of pulp size: validity and clinical implications

A study was performed to determine if the radiographic appearances of the coronal pulp spaces provide a reliable indication of pulp size in maxillary incisors. The use of student and staff assessor groups showed that length of clinical experience did not influence assessments of the size of the coronal pulp. A measuring grid, superimposed over a duplicate set of films, decreased the students' perception of the size of the coronal pulp. The presence of small carious lesions or restorations did not affect the assessments for either of the film types viewed. The data were pooled to give a mean radiographic size for each tooth, and the teeth were sectioned. Analysis of the results demonstrated the value of carefully viewing incisor crowns shown on pre-operative periapical radiographs. Sectioning of the teeth suggested that very little dentine may remain to protect the pulp after routine crown preparations. Even the very conservative preparations sometimes necessary when providing veneers might be considered a hazard to the pulp, as they may expose large areas of the dentine of an immature tooth.

Long-term evaluation of human teeth after Le Fort I osteotomy: a histologic and developmental study

Transient pulpal vascular ischemia and direct injury to the apices of the teeth have been implicated as the causes of degenerative and atrophic pulpal changes in experimental animals after Le Fort I osteotomy despite the presence of collateral circulation. The long-term clinical effect of these pathologic changes in human teeth has not been studied. Seventeen maxillary third molar teeth from 10 patients whose postsurgical follow-up ranged from 6 months to 78 months (mean, 40 months) were extracted. The long-term biologic effects of Le Fort I osteotomy on the pulp and on the development of teeth were retrospectively evaluated with clinical and standard histologic techniques. Normal teeth from patients who were not operated on were used as controls. Histologic examination revealed an intact pulpal circulation and minimal pathologic changes in the pulpal tissue. Clinical and radiographic studies showed that the growing teeth developed normally after surgery. The Le Fort I downfracture procedure had little discernible long-term effect on the pulp and on the development of human third molar teeth.

Hard tissue barrier formation in pulpotomized monkey teeth capped with cyanoacrylate or calcium hydroxide for 10 and 60 minutes

Monkey incisor teeth were pulpotomized in groups of 10. After physiological hemostasis, the pulps of group I were covered with isobutyl cyanoacrylate, and those of groups II and III with calcium hydroxide for 10 and 60 minutes, respectively, whereafter this compound was washed away and the wound surfaces covered with Teflon. In group IV, calcium hydroxide was used as a positive control, and Teflon as a negative control in group V. The animals were killed after 12 weeks and the teeth removed in tissue blocks. The material was processed and evaluated histologically with respect to location and continuity of a hard tissue barrier, type of newly formed hard tissue, state of the pulp, and presence of stainable bacteria in the coronal cavity. Seven of nine teeth in group I showed a hard tissue barrier. The corresponding figure for group II was eight out of 10 teeth. All teeth in groups III and IV had a barrier. The incidence of a continuous barrier increased from group I through group IV, as did the incidence of its location below the level of the original wound surface. The condition of the pulp was related to the presence of bacteria and the continuity of the barrier to the presence of inflammation. There was no bridging in group V. The results support the theory that a low-grade irritation is responsible for the formation of a hard tissue barrier in exposed pulps.

An evaluation of a glass ionomer luting agent: pulpal histological response

Pulpal histological response after crown cementation with a glass ionomer luting agent was evaluated and compared with the response to a polycarboxylate cement or a varnish plus zinc phosphate cement. Pulpal histological response was evaluated on teeth that had full crowns cemented with the test luting agents 3, 10, and 56 days after cementation. No statistically significant differences were found in pulpal histological response between the materials tested during all periods. These findings suggest that factors other than pulpal inflammation are contributing to the reported hypersensitivity after cementation associated with glass ionomer luting agents.

Evaluation of over 400 autogenous tooth transplants

Results are described from a series of over 400 autogenous tooth transplants that have been followed up for two years or longer. A success rate of over 70% is reported.

Structural changes in the dental and periodontal tissues of the rat incisor following application of orthodontic loads

The present study deals with the morphometric changes in the loaded rat incisor and its supporting structures 3 months after load removal. The material examined was limited to that part of the tooth that is located between 8 and 20 mm from the tooth apex. Of the ten albino rats in whom laterointrusive loads (19 +/- 0.6 g) were applied to the lower left incisor for a period of 2 weeks, the rate of tooth eruption returned to normal in four animals (group A); in six rats, eruption remained grossly impaired (group B). These two groups were compared with a control group of four rats in whom the incisors were allowed to erupt normally during the 3 months of the experiment. The left mandibles were dissected and fixed; the incisors were demineralized, embedded in paraplast, and cut into transverse serial sections of 6 micron, which were used to produce a three-dimensional reconstruction of all tissue components by means of computerized histomorphometry. The parameters of pulp and dentin, and the total tooth size and shape in group A were similar to those of the control group. In group B, pulp and dentin were changed significantly, tooth size increased, and the oval shape was altered into a more rounded contour, together with a significant enlargement of the socket. Although the total PDL volumes remained similar in all three groups, the tooth/socket relation, as expressed by PDL width and PDL area at the different tooth sides and at varying distances from tooth apex, diverged from normal significantly in all teeth that had been subjected to loading.

Adaptation of eight modern dental amalgams to walls of Class I cavity preparations

An in vitro study was conducted in which a range of amalgam alloys was condensed into Class I cavity preparations. The force of condensation and increment size were varied to determine the effect of these operator variables on the adaptation, of the alloys investigated, to the prepared cavity walls. Specimens were sectioned, metallographically polished and examined using light and scanning electron microscopes. For each specimen ten random points on the pulpal and both vertical walls were selected to measure the adaptation of the amalgam to the tooth structure. For the Class I cavity preparation the adaptation of all alloys to the vertical walls was better than the adaptation to the pulpal walls. The overall adaptability of the alloy did not appear to be determined by the particle size, shape or composition. Condensation force was the most important factor in influencing adaptation of amalgam to the cavity walls. Heavy condensation forces produced better adaptation for all alloys particularly when condensing small increments.

The effect of dentinal stimulation on pulp nerve function and pulp morphology in the dog

The effect of dentinal stimulation on pulpal nerve responses and pulp morphology has been studied in the dog. Canine tooth (n = 25) dentin was stimulated by drilling, probing, and air-blasting for from two to five hours. Acid-etching was used to open dentinal tubules. All test teeth showed disruption of the odontoblast layer and its separation from the predentin; also, dislocation of odontoblast nuclei into dentinal tubules was found in most cases. Single-fiber (n = 14, conduction velocity = 24.3 +/- 7.4 (SD) m/s) recordings of the responses of canine tooth pulpal nerves to dentinal stimulation were made in ten of the stimulated teeth. No changes in the sensitivity of the nerves to dentinal stimulation could be detected. It is concluded that pulpal nerve function and morphological changes of the pulp are not clearly correlated. The condition of the dentin surface seems to be the important factor.

Tissue reaction following application of extrusive and intrusive forces to teeth in adult monkeys

Intrusion has been regarded as a very controversial topic in the orthodontic literature. Although it seems a logical way to handle deep overbite in adult patients who have elongated teeth, reports on iatrogenic damage have led to the suggestion of alternative methods. Considering the disadvantages of these alternatives, it seems reasonable, however, to improve our knowledge of tissue reaction as related to intrusion. Three Macaca fascicularis monkeys were used for the experiment. By means of a segmented arch approach, the upper incisors and the four first premolars were submitted to forced eruption for 8 weeks followed by 12 weeks of intrusion. A split-mouth technique was used to study the influence of oral hygiene on the tissue reaction. On the right side of the mouth, the teeth were brushed with chlorhexidine three times per week. On the left side, no oral hygiene was performed. After intrusion of the teeth, a 1-to-14 day retention period with passive appliance preceded the killing of the monkeys. A buccolingual hematoxylin- and eosin-stained serial section was produced, and soft- and hard-tissue reactions described. It appeared that the hygiene program could limit but not prevent gingival inflammation. There was, however, a marked difference in the histologic picture of the marginal bone on the two sides. On the hygiene side, clear signs of bone deposited during forced eruption were still present. This was not the case on the nonhygiene side. The extension of bone resorption was also different on the two sides.(ABSTRACT TRUNCATED AT 250 WORDS)