2019 ODA ASM The Art and Science of Crown Lengthening for ... · Crown lengthening is the re -establishment of the dentogingival junction at a more apical level on the root to accommodate

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The Art and Science of Crown Lengthening for Successful Restorative Dentistry: From Concepts to Predictable

Results

Course Objectives

§ Definition of Crown Lengthening§ Anatomy of the dentogingival junction§ Biologic width§ Treatment considerations§ Indications and contra-indications for

crown lengthening§ Techniques for Predictable Restorative

and Esthetic Crown Lengthening

Definitions

Davarpanah, M et al.: Restorative and periodontal considerations of short clinical crowns. Int. J Periodontics Restorative Dent. 1998; 18; 424-433.

A short clinical crown is defined as any tooth with less than 4 mm of sound opposing parallel walls remaining after occlusal and axial reduction

Crown lengthening is the re-establishment of the dentogingival junction at a more apical level on the root to accommodate the JE and CT attachment

What are the Common Causes of the Short Clinical Crown?

Characteristics of the Short Clinical Crown

Common causes of the short clinical crown include:§ Caries§ Erosion§ Tooth malformation§ Fracture

Yeh, S.; Andreana, S.: Crown lengthening: basic principles, indications, techniques and clinical case reports. NY State Dent J. 2004; 70: 30-36; Assif, D. et al.: Restoring teeth following crown lengthening procedures. J Prosthet Dent. 1991; 65: 62-64.

Common causes of the short clinical crown cont’d:§ Attrition§ Excessive tooth reduction§ Eruption disharmony§ Exostosis§ Genetic variation

Yeh, S.; Andreana, S.: Crown lengthening: basic principles, indications, techniques and clinical case reports. NY State Dent J. 2004; 70: 30-36; Assif, D. et al.: Restoring teeth following crown lengthening procedures. J Prosthet Dent. 1991; 65: 62-64.

Characteristics of the Short Clinical Crown

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Anatomy of the

Dentogingival Complex

Structures comprising the periodontium and biologic width space

Anatomy of the Dentogingival Complex

§ In 1959, Sicher described the dentogingival junction composed of an epithelial attachment and a fibrous connective tissue attachment

§ In 1961, Gargiulo et al. discovered a proportional relationship between the epithelial attachment, the connective tissue attachment and the crest of the alveolar bone


§ Differences in sulcus depth due to the penetration of the supracrestal fiber attachment by the periodontal probe

§ Sulcus depth is also clinically influenced by the:

§ degree of inflammation§ amount of probing force§ location on the tooth


The location of the restorative margin relative to the alveolar bone crest is more critical than its distance below the free gingival margin for preserving gingival health (Kois, J., 1994)


Biologic Width

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The rationale for placing the restorative margin 3mm from the alveolar bone is to have the restorative margin with its anticipated biofilm deposit beyond the critical 2.7mm from the crestal bone (Mishkin, D., and Gellin, R., 1993)

Crown Margins

What are the Goals of Crown Lengthening?

Crown lengthening is based on two principles: 1. re-establish BW and 2. maintenance of adequate keratinized gingiva

Amer. Acad. of Perio., Glossary of Periodontal Terms, 4th ed. Chicago: American Academy of Periodontology; 2001:11)

Goals of Crown Lengthening

An adequate width of KG needs to be maintained around a tooth (≥ 2mm) for gingival healthGargiule A.W. et al. J Periodontol 1961;32:261-267; Vacek J.S. et al. Int J Periodontics Restorative Dent. 1994; 14:154-165: Nevins M. and Skurow H.M. Int J Periodontics Restorative Dent. 1984; 4 (3): 30-49; Block P.L. J Prosthet Dent. 1987; 57: 683-689: Lang NP, Löe H. J Periodontal 1972; 43: 623-627

A minimum of 3mm of space between restorative margins and the alveolar crest, 2mm of BW space and 1mm for sulcus depth

Goals of Crown Lengthening

Objectives of Clinical Crown Lengthening

Removal of subgingival caries


Cosmetic improvement

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Correction of occlusal plane Facilitation of improved oral hygiene

Tooth fracture and/or root perforation

Inadequate tooth structure for crown retention due to excessive occlusal wear, abrasion, erosion or delayed passive eruption


Reduce excessive gingiva Correct gingival asymmetry


What are the Considerations forCrown Lengthening?

Most crown margins will eventually harbor biofilm since the size of a typical microorganism is only about 1µ thick (Christenson, G.J., 1966)

No bone loss occurs when the biofilm front is greater than 2.7mmcoronal to the crestalbone (Waerhaug, J., 1979)

Considerations for the Crown Lengthening ProcedureCrown Lengthening Decision Tree

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Guidelines for Dimensions for Surgical Crown Lengthening

What are the Contraindications for Crown Lengthening and What are

Possible Complications?

Treatment Planning and

Surgical Consideration

Tissue Preparation:

OHI, scaling and root planing

Clinical Protocol/SurgicalTechniques for Crown Lengthening

Operative Procedures:

Root canal therapy, post foundation, provisional restoration

Clinical Protocol/SurgicalTechniques for Crown Lengthening

Surgical Procedure:Success is based on the following criteria:§ Exposure of adequate supragingival sound

tooth structure

§ Re-establishment of the “biologic width”

§ Presence of sufficient bone to provide adequate support for the treated root

Crown Lengthening Procedure: Sequence of Therapy

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Rationale for Crown Lengthening Surgery

1) Esthetic and/or functional crown lengthening

2)Restore the Biologic width

3)Establish a Ferrule effect

4)Soft tissue and osseous management

Rationale for Crown Lengthening Surgery

Proposed Classification System

E A Lee, Pract Proced Aesthet Dent 2004;16(10):769-778

Key Factors for SuccessfulPeriodontal Restorative Relationships

A short clinical crown cannot be evaluated by visual inspection alone; assessment must include clinical examination, radiographic examination and diagnostic cast analysis for a successful rehabilitation of the short clinical crown

Davarpanah, M et al.: Restorative and periodontal considerations of short clinical crowns. Int. J Periodontics Restorative Dent. 1998; 18; 424-433.; Yeh, S.; Andreana, S.: Crown lengthening: basic principles, indications, techniques and clinical case reports. NY State Dent J. 2004; 70: 30-36.; Assif, D. et al.: Restoring teeth following crown lengthening procedures. J Prosthet Dent. 1991; 65: 62-64.

The margins of the primary preparation serve as the reference point for the surgeon

Surgical crown lengthening for a short clinical crown is performed to increase retention and resistance form


Temporary crown(s) or surgical guide stent approximating the margins of the final restoration assist the surgeon to define more exactly the relationship between the final restorative margins and the marginal bone

Scutella, F. et al. Surgical template for crown lengthening: a clinical report. J. Prosthet .Dent. 1999, 3: 253 – 256; Walker, M. and Hansen, P. Template for surgical crown lengthening fabrication technique. J. Prosthodont. 1998, 7: 265-267; Brägger, U. et al. Surgical crown lengthening od the clinical crown. J. Clin. Periodontal. 1992, 19: 58 – 63.


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Brägger, U. et al. (1992) studied periodontal tissue changes after surgical crown lengthening:

§ No change of the attachment level and probing depth six weeks post surgery

§ No or minimal changes (< 1 mm) in 85% of cases of the marginal gingival level

§ In 12% of cases, gingival retraction occurs more than 1 mm

§ In conclusion, final restoration no sooner than 6 weeks post surgery and LONGER in the esthetic zone

Guidelines for Restorative Margin Placement

§ Ideal for the periodontium to keep restorative margins supragingival

§ The depth of the gingival sulcus (base) should be the reference point to avoid VBW

§ In probing healthy gingiva, the probe penetrates ~ 0.5 mm into the epithelial attachment

Gingival tissues should be healthy with no signs of inflammation prior to tooth restoration:


§ If the gingival sulcus is ≤ 1.5mm, the margins of the restoration are prepared to 0.5 mm subgingivally

§ If the gingival sulcus is 1.5 – 2 mm, the margins of the restoration are prepared to 0.5-1.0 mm subgingivally


Spear, F.M. and Couney, J.P. Periodontal-restorative interrelationships. Carranga’s Clinical Periodontology. 9th ed. 2002, Chap. 75, p.949-964. Harrison, J.D. et al. Tissue management for the maxillary anterior region. Esthetics of Anterior Fixed Prosthodontics. 1994, Chap. 7, p. 143 - 159. Lang, N.P. Periodontal Considerations in prosthetic dentistry. Periodontal. 2000, 9: 118 – 131.

§ If the gingival sulcus is > 2 mm especially in the esthetic zone from the vestibular side, internal bevel gingivectomy is considered and restorative margins are placed 0.5-1.0 mm subgingivally; (N.B. a deeper gingival sulcus demonstrates less predictability and potential for more severe gingival recession)

Spear, F.M. and Couney, J.P. Periodontal-restorative interrelationships. Carranga’s Clinical Periodontology. 9th ed. 2002, Chap. 75, p.949-964. Harrison, J.D. et al. Tissue management for the maxillary anterior region. Esthetics of Anterior Fixed Prosthodontics. 1994, Chap. 7, p. 143 - 159. Lang, N.P. Periodontal Considerations in prosthetic dentistry. Periodontal. 2000, 9: 118 – 131.



Crown Lengthening and the Ferrule Effect

Crown Lengthening and the Ferrule EffectFerrule Effect: a 360-degree metal collar of the crown surrounding the parallel walls of the dentin extending coronal to the shoulder of the preparation

Sorensen JA, Engelman MJ. Ferrule design and fracture resistance of endodontically treated teeth. J Prosthet Dent 1990;63(5):529-536.

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Crown Lengthening and the Ferrule EffectFerrule Effect: Risk Assessment Analysis

Gegauff AG. Effect of crown lengthening and ferule placement on static load failure of cemented cast post-cores and crowns. J ProsthetDent 2000;84(2):169-179.

Restorative Crown Lengthening

Esthetic Crown Lengthening

Healing Time

§ Recommended healing time between crown lengthening surgery, initial crown preparation and final preparation and crown placement varies in the literature

§ Recommended healing times vary from 6 to 8 weeks to 6 months

§ In general, 2 to 3 months is recommended for posterior areas

§ For a gingivectomy/gingivoplasty tissue maturation completed within 4 to 6 weeks

§ For flap elevation and bone exposure allow 8 to 12 weeks for tissue stabilization and maturation

§ For flap elevation and osseous surgery allow ≥ 6 months for soft tissue stabilization-particularly for esthetic cases Wagenberg B.D. et. al. Int J Periodontics Restorative Dent. 1989; 9: 322-331; Brägger U. et. al. J Clin Periodontal 1992; 19: 58-63; de Waal H. Castellucci G. Int J Periodontics Restorative Dent 2004; 75: 1288-1294Deas D.E. et. al. J Periodontal 2004; 75: 1288-1294

Healing Time Delayed (Altered) Passive Eruption

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§ The concept of delayed passive eruption was first introduced by Coslet et al. in 1977. Some patients with this condition in case of high lip line may present a smile with clinical crowns that appear short or shorter than they should be

§ A classification was proposed evaluating the relationship between the gingiva and the clinical crown on one hand and the relationship between the CEJ and the bone crest on the other.

Delayed (Altered) Passive Eruption

Coslet et al., The Alpha Omegan. 1977;70(3):24-28

Orthodontic Crown Lengthening

§ Modifies the alveolar housing and gingiva§ Can increase the zone of attached gingiva§ Osseous resection may be necessary after

forced eruption§ Limits the amount of osseous resection on

adjacent teeth§ Corrects vertical osseous defects§ Prevents exposure of furcations

Forced Eruption

Benefits:

Forced Eruption

Advantages:1. Objective can be achieved without compromising the bone support of adjacent teeth

2. In the presence of compromised bone support, a favorable C/R ratio can be achieved by orthodontic treatment because the entire attachment unit follows the erupted tooth3. Can be used in select cases in the treatment of one and two wall infrabony pockets

Crown Lengthening: Forced Eruption

Dr. J S Ingber Dr. J S Ingber


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G Braga and A Bocchieri Int J Periodontics Restorative Dent 2012;32:81–90


G Braga and A Bocchieri Int J Periodontics Restorative Dent 2012;32:81–90


2019 ODA ASM The Art and Science of Crown Lengthening for ... · Crown lengthening is the re -establishment of the dentogingival junction at a more apical level on the root to accommodate

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