Principles of planning of tooth preparation for fixed dentures according to the analysis of cone beam computed tomography

Abstract

Introduction. The relevance of the study is to develop a plan for the preparation of teeth for fixed dentures based on the analysis of cone beam computed tomography (CBCT) to prevent complications.

The aim of the study. To develop the basic principles of planning the preparation of different groups of teeth for fixed dentures based on the analysis of cone beam computed tomography.

Materials and methods. An analysis of the planning of orthopedic treatment of fixed dentures on the basis of CBCT examination of the teeth of the upper and lower jaws in 26 patients with disorders of the anatomical structure of the crown part of the teeth and their placement in the dentition, defects of the crown part of the teeth, tremas and diastemas, and 42 patients with small and medium defects of the dentition was carried out. The examination was performed on an X-ray machine with the function of a Veraviewepocs 3D R100 P computed tomography scanner.

Results of the study. The analysis of examinations of the anatomical structure of different groups of teeth using CBCT showed the possibility of preliminary determining the safe areas of the predicted volume of tissue preparation of the crown part of the tooth for fixed dentures, correctly modelling the future slope of the prepared tooth walls with the condition of a tight fit of the artificial crown in the cervical region of the tooth and the possibility of preparing a tooth with a ledge while maintaining its vitality. It was proved that using the software function “Measurements and Overlays”, “Measure angle” in the lateral and frontal projections, it is possible to selectively shift the slope and optimally move the lines (of the future preparation) on the medial, distal, lingual, vestibular sides of the teeth (maintaining their parallelism with an accuracy of 0.01 degrees) and solve possible options for the predicted volumetric preparation of the vital teeth for fixed dentures. The criterion for choosing the predicted depth of preparation of the tissues of the crown part of the vital teeth in the cervical region from the vestibular, oral, medial and distal sides, without a ledge or using the appropriate depth of the ledge, is the thickness of the dentin to the pulp chamber of the tooth in the axial plane, which was measured with the “Ruler” function with an accuracy up to 0.01 mm.

Conclusions. The use of the obtained CBCT data of the anatomical structure of the teeth will allow the following: to predict the possibility of preparation of the vital teeth for fixed dentures, to predict the volume of preparation of the crown part of the tooth, taking into account its individual anatomical structure and tooth inclination, to optimally choose the method of preparation – without a ledge or using the appropriate depth of the ledge, to prevent complications from the tooth pulp and marginal periodontium, and to improve the quality of orthopedic treatment of fixed dentures.