Preparation Junctions For All-Ceramic CAD/CAM Crown And Bridge Restorations

Download Article


1Department of Prosthetic Dentistry Faculty of Dental Medicine Medical University Plovdiv, 3 Chr. Botev Blvd., Plovdiv, 4000 Bulgaria


Background: The preparation junction type is determined by a number of factors that need to be taken in consideration with CAD/CAM Fixed Prosthodontics: the used material; the condition of the retainer teeth, their periodontium and the occlusion; the design software and the type of drills; the working protocol; the cement and the method of cementation.

The aim: of this article is to describe the optimal preparation junctions for CAD/CAM crown and bridge restorations made by ceramics based on zirconium dioxide and the basic factors that affect them.

Materials and methods: Chamfer and radial shoulder preparation junctions are suitable (width 1 – 1, 5 mm). Trimming of 1, 5-2 mm dental tissues is necessary on the occlusal surface. The homothetic tooth reduction is optimal. The surface has to be smooth and the edges rounded.

Results: The preparation width depends on the size and vitality of the tooth. In stained teeth the removal of more tissues provides a greater volume needed for masking the dark color. Vestibular preparation under the level of the gingiva is preferable to ensure optimal aesthetics. The preparation junction is determined also by the CAD/CAM software abilities, the type of drills and protocol of impression taking (classical or digital). The creation of a working model with an intraoral scanner is greatly facilitated by preparations above the gingival margin.

Conclusions: Knowledge about the criteria for selection of preparation junctions is essential for fabrication of accurate and aesthetic CAD/CAM restorations.

Keywords: preparation junctions; CAD/CAM; all-ceramic crown and bridge restorations


  1. Кисов Хр. Керамични фасети. Клиничен и лабораторен протокол. Непрекъснато усъвършенстване ЕООД, София, България, 2008. (Bulgarian)
  2. Newman М, Takei Н, Klokkevold P, Carranza F. Carranza’s Clinical Periodontology, St. Louis, Missouri: SAUNDERS Elsevier, 12th Edition, June 2014.
  3. Dawson P. Functional occlusion. From TMJ to Smile Design. St. Louis, Missouri: MOSBY Elsevier, July 2006.
  4. Hayashi K, Sachdeva AU, Saitoh S, Lee SP, Kubota T, Mizoguchi I. Assessment of the accuracy and reliability of new 3-dimensional scanning devices. Am J Orthod Dentofacial Orthop, 2013;144:619-625.
  5. Song Y, Zhao YJ, Sun YC, Lü PJ, Wang Y. Initial evolution research for design and process accuracy of one type of domestic computer aided design soft and computer aided manufacture. Zhonghua Kou Qiang Yi Xue Za Zhi, 2013;48:550-553. (Chinese)
  6. Vlahova A, Kissov Chr, Kazakova R. Clinical Protocol for Eugenol Elimination of Contaminated Dental Tissues Subjected to Adhesive Cementation. SYLWAN, 2015; 159:161-165.
  7. Кисов Хр. Изпиляване на зъбите за изцялокерамични и металокерамични корони. Индекс, София, България, 2005. (Bulgarian)
  8. Vlahova A, Kazakova R, Bozhkova T, Hadzhigaev V, Zlatev St, Kissov Chr, Todorov G. First steps with CAD/CAM: a single crown design by 3Shape Dental System. Folia Medica, 2015;57:50-51.
  9. Хаджигаев В, Влахова А, Златев Ст, Тодоров Р, Попов И. Изработване на CAD/CAM мостова конструкция по оптичен отпечатък. Клиничен случай. Сборник научни трудове, 45 години Факултет дентална медицина – Пловдив, 2015:43-48. (Bulgarian)
  10. Кисов Хр, Влахова A, Карацанова Д. Какво ново при керамиките на циркониевия диоксид. СДК и НУС, 2014;13;47-48. (Bulgarian)
Citation Information: Balkan Journal of Dental Medicine. Volume 20, Issue 2, Pages 122–125, ISSN (Online) 2335-0245, DOI:, July 2016