In dental prosthesis, for the teeth that need to be fully crowned, the tooth preparation is carried out, and a circle of platform is evenly ground near the gum.

Generally, except for too small or conical teeth and concave teeth can not be made shoulder.

The width of the crown neck and shoulder is usually 0.5-1.0mm(for the near and far diameter of the teeth and the diameter of the lip and tongue is not allowed, it can be designed as a shallow concave type with only the metal neck edge)

Full porcelain crown width: 1mm(due to the smaller width of the lower front teeth, the width of the shoulder can be reduced accordingly)

Purpose of neck and shoulder preparation:

If the shoulder is not prepared in place or not prepared, the crown edge will form a foreign body overhang after the full crown is worn, stimulate the gums, cause gingival inflammation and bleeding, and even lead to crown decay over time.

Significance of neck and shoulder preparation:

(1) Make the crown edge completely close to the neck of the affected tooth to increase its retention and stability.

(2) It is beneficial to the health of the periodontal tissues of the affected teeth.

(3) The crown can achieve a beautiful effect after repair.

(4) It can promote the long-term effect of repair.