Use of 3D finite element models to analyze the influence of alveolar bone height on tooth mobility and stress distribution

Mechanical Properties of the Periodontal System and of Dental Constructs Deduced from the Free Response of the Tooth

The biomechanical behaviour of the periodontal ligament (PDL) is still not well understood although this topic has been studied for almost 100 years. This study reports on clinical and mathematical studies to determine the constitutive law of the PDL. A set of mechanical parameters of the tooth-PDL system is obtained, and a new method for the evaluation of these parameters from the free response of the tooth is introduced. This response is produced by repeated impacts applied to the gingival tissue in the apical part of the tooth investigated—with the aid of a Periotest exciter. A Doppler ultrasound probe is utilized to determine the response of the tooth-PDL system. The parameters evaluated from these measurements can be considered as the elastometric properties of the dental system investigated. A modal analysis/system identification method is utilized to estimate these parameters. The investigations are carried out for different teeth abutments, both with and without a dental bridge/fixed partial prosthesis (FPP). The differences between the responses of the systems in these two cases are determined with the new method proposed. They are discussed with regard to the specific purposes of the FPP. The study demonstrates that this method can provide the dentist with the necessary objective evaluations regarding the properties and health of the tooth-PDL system, as well as of the construct that is obtained after installing a dental bridge.

Application and development of ultrasonics in dentistry

Since the 1950s, dentistry's ultrasonic instruments have developed rapidly. Because of better visualization, operative convenience, and precise cutting ability, ultrasonic instruments are widely and efficiently applied in the dental field. This article describes the development and improvement of ultrasonic instruments in several dental fields. Although some issues still need clarification, the results of previous studies indicate that ultrasonic instruments have a high potential to become convenient and efficient dental tools and deserve further development.