1

Pre-prosthetic crown lengthening procedure

王英斌20031221

2

The predictability of the esthetics may be determined by the patient’s presenting

anatomy rather than the clinician’s ability to manage state-of-the-art

procedures

Kois J. 2001

3

Contents

• How much should I have appropriate distance between osseous crest and final margin ?

• Esthetic consideration • Restorative consideration • Stability of soft tissue dimension after

surgical CLP• Conclusion

4

What is biologic width ?

何謂生理寬度 ?

5

Dentogingival complex

Ginigival sulcus 0.69mmGinigival sulcus 0.69mm

Junctional Epithelium 0.97mmJunctional Epithelium 0.97mm ( 0.71-1.35mm)( 0.71-1.35mm)

Connective tissue attachment 1.07mmConnective tissue attachment 1.07mm ( 1.06-1.08mm )( 1.06-1.08mm )

Biologic widthBiologic width

6

Epi. attachment 1.14 (0.32-3.27)Connective tissue attachment 0.77 (0.29-1.84)Sulcus depth 1.34 (0.26-6.03)

Vacek JS et al 1994

7

Dimensions of human dentogingival junction

Ant. teeth 1.75 Premolar 1.97 Molar 2.08

Vacek JS et al 1994

epithlieum was variable ,but c.t. tissue

attatchment was consistent Gargiulo AW 1961

Vacek JS et al 1994

8

• The biologic width follows the osseous scallop• The osseous scallop parallels

the cemento-enamel junction circumferentially .

Anterior teeth : scallop

posterior teeth : flat

9

Ferrule effect (1.5mm)

360 degree metal collar of the crown surrounding the parallel walls of the dentin extending apical to the shoulder of the preparation Libman& Nicholls 1995 IJP

pulpless tooth– post&core

Spear F. 1999 compendium

10

The influence of margins of restorations on the periodontal tissues over 26 years

increased loss of attachment found in teeth sub-

gingival restorations(>1mm) started slowly and could be detected clinically 1-3 years after the fabrication and placement of the restorations

Schätzle M et. al. J Clin Perio 2000;27:57-64

11

Osseous crest-final margin

Supra-gingival margin • Not need post-core tooth 2(B)+0.5-1(safe) =2.5-3mm• Post-core tooth

2(B)+1.5(F)+0.5-1(safe) = 4-4.5mm Subgingival margin • Not need post-core tooth 2(B)+0.5-1(safe)+1(sulcus) =3.5-4mm• Post-core tooth 2(B)+1.5(F)+0.5-1(safe)+1(sulcus) = 5-5.5mm

12

Response to this invasion• Crestal bone loss

• Gingival recession and localized bone loss

• Localized gingival hyperplasia with minimal bone loss

• Combination

13

Inflammatory Disease control first

14

Restorative –driven Esthetic –driven

15

Anterior crown lengthening

• 2mm tooth structure—minimal retention and resistance form

• 2mm – biologic width • 1mm – sulcus depth• 1.5mm –ferrule effect

16

Facial profile

Smile line

17

18

• Biotype of the periodontium (thick or thin)

• Relationship of gingiva to the osseous crest

• Relationship of preparation finish line to the osseous crest

19

Relationship of gingiva to the osseous crest ( dentogingival complex )

Normal crest (85%) facial FGM –crest : 3mm inter-proximal : 4mm high crest (2%) low crest (13%) Kois j 1994

– bone sounding

20

Aesthetic crown lengthening

Should always first consider whether orthodontic extrusion extrusion is

appropriate

21

The role of orthodontics in crown lengthening

22

1. Root length(C/R) 4. Relative importance 2. Root form 5. Esthetics3. Level of fracture 6. Endo/perio prognosis

23

Alveolar bone augmentation for implants by orthodontic extrusion

Salama & Salama IJPRD 1993

24

Uneven gingival margins

Orthodontic movement to

reposition the gingival margin

Surgical correction of

gingival margin discrepancies

25

Probing labial sulcular depth

of 2 central incisors

Shorter tooth has deep sulcular depth

Excisional gingivectomy

Delayed passive eruption

26

Repositioning of the gingival margin by extrusion

27

是否有磨耗 ??

the incisal edges abraded??

Incisal edge is thicker labiolingually

than the adjacent tooth

Abraded

Intrude the short central incisor

Stablized at least 6M

28

Repositioning of the gingival margin

by intrusion

29

Posterior crown lengthening

• 2mm tooth structure—minimal retention and resistence form

• 2mm – biologic width • 1mm – sulcus depth

30

Restorability ??

For What ??

31

Crown-root ratio

Non-CLP Surgically CLP

Orthodontic extrusion

32

Kennedy Class I & II distal-most mand. P2

•Pulpless teeth are commonly avoided as abutment for an RPD ,especially if terminal abutment is for distal extension

Kratochvil FJ 1988

33

Treatment choices

1 > extraction ? implant

2 > CLP bridge ??

34

Take into consideration about mucogingival condition

35

Crown-lengthening procedures

36

.

Aesthetic osseous surgery

美觀性的齒槽骨手術

37

Buccal scalloped incision• Double-scalloped creates triangular soft tissue within the

healthy gingiva that protects the furcation area of multi-rooted molars during healing

38

-Apically positioned 0.5-1mm apical to osseous crest -Provides the interproximal soft tissue for primary flap adaptation

Palatal scalloped incision

shape of the incision follows the radicular morphology and the depth should be at the level of palatal osseous crest or slightly at the level to that after osteoplasty and ostectomy are accomplished

39

• 15-degree declining buccopalatal slope

The well-declined bucco-lingual interproximal slope prevents inter-dental gingival proliferate on and bridging,which ultimately lead to pocket formation

40

Crown lengthening in mand. molars : A 5-year retrospective radiographic analysis

Dibart S. et al J P 2003 ;74:851-821

Critical distance from the furcation (CDF) – furcation entrance to the margin of the temp crown or excavated caries line

10/26 ( 38.5%) – radiographic FI

• critical distance from the furcation = 4mm

41

Tooth fracture treatment with orthodontic extrusion

42

Stability of soft tissue dimension after surgery

• Different surgical intervention

• Surgical skill

• Healing time

• Patient age

• Tissue biotype

43

Coronal displacement of the gingival margin

• more pronounced in patients with thick tissue biotype

• Individual variation • Not related to age or gender

Pontoriero R. et al JP 2001;72:841-848

44

Desired vs actual amount

• Clinicians may be need to be more aggressive during surgical crown lengthening procedure ,esp. disto-lingual aspect

Herrero F. et al JP 1995;66:568-571

45

Recommended

-- early definition of final margin

-- re-provisonalization 3weeks after the

surgical procedure

-- more aggressive removal of osseous structure

46

Timing for prosthetics

• Mean tissue recession following surgery was 1.32mm , while 29% of sites demonstrated 1-4mm gingival recession between 6weeks and 6 M post-operatively .

Brägger U et al 1992

47

Timing for prosthetics

• Definite crown preparation should not be made for at least 20W after surgery for ant. teeth

Wise MD 1985

The biological width was re-established to its original vertical dimension by 6 M

Lanning SK et al JP2003;74:468-474

48

Conclusion

There may be different ways of treating a disease,but there can be but one correct diagnosis

Morton Amsterdam 1974

49

Thanks for your attention !!