部分牙冠课件

1、部分牙冠1 section 4 partial crown部分牙冠2definition ：partial crown is a kind of fixed prosthetic restoration which cover part of the dental surface.characteristics ：less cutting of the tooth, short cervical margin, less stimulus to the gingival margin, easily be inserted, etc.部分牙冠3classification ：l 3/4 cro

2、wn of anterior toothl 3/4 crown of posterior toothl window crownl half crown部分牙冠4 3/4 crown3/4 crown of anterior tooth indication tight occlusion, the anterior tooth with little defect in the proximal surface or incisal angle which is not suitable for full crown or veneering.the retainer of anterior

3、 fixed bridge that doesnt fit for other kinds of retainers .1. those cases that need fixed splint or occlusal reconstruction.部分牙冠52. contraindication the cases that defect is so much that enough resistance form and retention form can not be prepared the cases that the pulposis and periapical disease

4、s have not been cured.部分牙冠63. tooth preparation of anterior 3/4 crown（1）preparation of proximal surfacepurpose cutting out enough proximal space for 3/4 crown, remove the undercut, guarantee the smooth insertion of crown.部分牙冠7 requirement two proximal surfaces should be parallel with each other or p

5、olymerize toward the incisal end at 25and the space should not be less than 0.5mm. for those teeth with short crown and little proximal undercut, the crown margin should be at the level of gingival margin and the shoulder should be prepared. on the contrary, for those with long crown and obvious und

6、ercut, the crown margin may be above the gingival margin and no undercut exists in the crown-covered area. method slice cut and preparation by diamond bur部分牙冠8method of proximal slice cutting with one-side carbide disc, cut from the incisal end to gingival end and the disc should incline to the ling

7、ual surface according to the width of mesio-distal distance of the labial and lingual surfaces. avoiding excessive cutting at the incisal angle.部分牙冠9method of proximal preparation by carbide bur the virtues of this method are safety, easy to control the dimension. column-shaped bur and cone-like car

8、bide bur with the diameter less than 1mm is first used to cut out the space from the lingual-proximal surface and remove the undercut. 部分牙冠10the preparation method and dimension for proximal surface of 3/4 crown部分牙冠11（2）the preparation of incisal bevel：purpose to protect the incisal end of 3/4 crown

9、, keep enough thickness of the restoration and avoid interference when protrusion.requirement the incisal surface should incline from labial surface to lingual surface for upper incisors and from lingual surface to labial surface for lower incisors. plane of 45 should be prepared on mesio-distal dim

10、ension method the width of incisal bevel relates to the labial-lingual dimension and space more than 0.35mm should be prepared. for canine, two bevels should be prepared.部分牙冠12the preparation of incisal bevel of 3/4 crown部分牙冠13（3）the preparation of lingual surfacerequirement space of 0.5mm on the li

11、ngual surface and no undercut on the axial wall method space of 0.5mm from the lingual protuberance to gingival and 0.5mm from incisal bevel to lingual protuberance. column-shaped stone and wheel-shaped stone are required. 部分牙冠14two stages preparation of lingual surfacesection 2section 1部分牙冠15（4）the

12、 preparation of proximal groovepurpose avoid lingual-towards dislocation of 3/4 crown.requirement parallel to the incisal 2/3 of labial surface, between labial 1/3 and middle 1/3 of proximal surface. the depth of groove is 1mm and two grooves should be parallel to each other or polymerize to the inc

13、isal end. the groove is arch-like in shape and the incisal end should be wider than gingival end. the line angle between the groove and proximal surface should be clear.method fissure bur or fine carbide bur should be used to prepare the proximal groove.部分牙冠16the position and dimension of proximal g

14、roove （1）the position is correct （2）the groove is too close to labial surface （3）the starting point is too close to lingual surface （4）the groove is too close to lingual surface部分牙冠17（5）refinementthe line angle should be continuous and round and no undercut is permitted.部分牙冠18（6）the preparation of i

15、ncisal grooverole increase the marginal strength of 3/4 crown and promote the retention.method the apex angle of the groove is 90, the height of labial wall is twice that of lingual wall and the end of incisal groove should be connected with the proximal grooves. 部分牙冠19the position and shape of inci

16、sal groove部分牙冠204. the manufacture of anterior 3/4 crown（1） wax pattern preparation （2） casting（3） examination and cementation部分牙冠21(二）二）3/4 crown of posterior tooth indicationthose cases with lingual and occlusal surface defect that are not fit for full crown and filling.those cases with occlusal s

17、urface defect or require occlusion reconstructionretainer of fixed bridge1. stabilization splint 部分牙冠22 contraindication the same with anterior 3/4 crown部分牙冠233. the tooth preparation of posterior 3/4 crownbasically same with the anterior 3/4 crown, the difference is：（1）preparation of occlusal surfa

18、ce：space of 0.51.0mm should be prepared on the occlusal surface，the margin of crown should be below the occlusal marginal crest in order to protect the dental cusps.部分牙冠24the preparation of occlusal surface of posterior 3/4 crown部分牙冠25（2）the preparation of occlusal groovepurpose avoid the lingual-towards dislocation of crown. method the dimension of the groove should be 1.5mm1.5mm, the margin is round and the groove should be