The effect of gingival fiberotomy on orthodontic cuspid retraction in cats.

Distal tipping forces were applied to the maxillary cuspid teeth of five domestic cats. Surgical elimination of the gingival attachment of one tooth in each cat resulted in greater distal crown movement and a shift of the center of rotation toward the root apex.

The effect of orthodontic force application on the pulpal tissue respiration rate in the human premolar.

This study investigates the effect of an orthodontic force on pulpal respiration in the human premolar. The participants in this study required the removal of four first premolars for orthodontic treatment. After written consent was obtained, these teeth were used in the following manner. Randomly, the premolars on one side of the mouth were designated as experimental and the premolars on the opposing side served as controls. The four teeth were removed following a 3-day application of an orthodontic force. The pulp tissue was then extirpated and used for the investigation. A radioactively labeled carbon dioxide production system was used to evaluate the effect on pulpal respiration of the orthodontic force. It is thought that this method has been proved to provide a viable and sensitive biochemical analysis of tissue respiration on very small samples over short observation periods. The data were collected and prepared for statistical analysis. This investigation demonstrated that the pulp tissue respiration in seventeen subjects was depressed an average of 27% as a result of orthodontic force application. A positive correlation between the age of the participant and the amount of tissue respiratory depression was also demonstrated. It was therefore concluded that orthodontic forces of very short duration do cause biochemical and biologic pulpal tissue alterations and that orthodontic forces may be less biologically safe as the age of the patient increases.

The response of human pulpal tissue after orthodontic force application.

Previous investigations have dealt with significant alterations in pulpal respiration associated with dental materials and methods. The purpose of this investigation was to note if significant alterations in pulpal respiration remained after the insult had been removed. A rest period of 1 week was chosen to evaluate the pulpal respiration response after application of an initial 72-hour orthodontic force. A radiorespirometric method was used to determine differences in experimental and control pulpal tissue respiration rates within individuals. These data showed that the mean respiration rates of experimental pulpal tissue compared with control pulpal tissue remained depressed approximately 33.2% after the 7-day rest period. However, it was found upon further investigation that there were really two groups present--one that had returned to normal respiration rates and one that did not within a 1-week rest period. Age and apical opening size correlated with the return of the respiration rates to normal during the 1-week rest period. Age was negatively correlated with respiration rate and apical opening size correlated with the return of the respiration rates to normal during the 1-week rest period. Age was negatively correlated with respiration rate and apical opening size was positively correlated with respiration rate.

Frictional changes in force values caused by saliva substitution.

The objective of this study was to determine the magnitude of frictional force changes between several sizes of stainless steel orthodontic wires (0.018 inch round, 0.020 inch round, and 0.018 X 0.025 inch rectangular) and an edgewise bracket (0.022 X 0.028 inch slot) when an artificial saliva medium was introduced. The wires were secured in the bracket slots with a 0.010 inch polyurethane ligatures. The force values in the saliva substitute medium were compared with those produced in a dry control and in glycerin. Clinically significant differences among the environmental conditions and among the wire sizes were found. The introduction of saliva substitute provides a significant reduction in force values.