The invention relates to a preparation method of a neck and a shoulder of a tooth during the tooth
full crown repair process, the specific steps are that: a shoulder preparation special
machine needle which is provided with a columnar base part, a columnar middle part and a spherical or short columnar top part with sands is adopted, the
radius of the top part of the special
machine needle is 1.2 to 1.4mm, the
radius of the middle part is 0.3mm while the length is 8 to 10mm; the
radius of the base part is 1mm while the length is 8 to 10mm; the base part of the special
machine needle is arranged on a
mobile phone to rotate the machine needle, the top part of the machine needle is arranged on a
tooth tissue which is near to a gum and can move along the outline of the gum, the middle part of the machine needle is parallel or nearly parallel to the surface of the tooth, when the middle part of the machine needle is tightly affixed with the
tooth surface, the shoulder with the depth of 0.9 to 1.1mm is formed at the edge of the tooth, thus completing the preparation of the tooth edge at the labial side / buccal side. The method can ensure the accurate preparation amount of the neck and the shoulder of the tooth during the
full crown repair treatment process, the
full crown and the tooth have great marginal
adaptation, and the full crown has high strength and pleasing appearance after the repair, which is conductive to the
oral health. The method further has simple operation and time conservation, which is not easy to damage the
periodontal tissue during the preparation process.