crown lengthening

89
CROWN LENGTHENING INDICATIONS AND TECHNIQUES Eilaf Al-Marei BDS.MFDRSI.KBAGD/R5

Upload: mohamadal-askar

Post on 23-Nov-2015

150 views

Category:

Documents


10 download

DESCRIPTION

complication of dental extractions

TRANSCRIPT

Crown lengthening

Crown lengthening indications and techniques Eilaf Al-MareiBDS.MFDRSI.KBAGD/R5OUTLINE

Definition Anatomy of the periodontiumIndications ContraindicationsTypesPrinciples of crown lengthening surgeryHealing following crown lengthening Definition Surgical crown lengthening is defined as : A procedure used to expose sound tooth structure with or without removal of alveolar bone for restorative purposes.

Glossary of periodontal terms, ed 4. 2001.Anatomy of the periodontium

4Biologic width Gingival Margins must not invade Biological Width Requirements for Periodontal Health.

Biological Width Requirements: There must be a minimum of 1mm between the apical level of the Junctional Epithelium and the bone crest.

Biologic width Crown Margins which extend apically beyond the Junctional Epithelium can violate the requirements for periodontal health.

An inappropriate crown margin increases plaque accumulation in close proximity to bone crest.6

Dimensions and Relations of the Dentogingival junction in Humans Gargiulo A., Wentz F., Orban F. J. Periodontol 1961.

This study measured dimensions of tissues involved in Biological Width considerations.

Used histologic sections to measure average dimensions of biologic width. These are not clinically accurate due to distortion with histologic processing.1.Cadaveric specimens. 2. functionallt the supracrestal attachment can be divided into 2 parts ( the CT attachment and epithelial attchment). 3. in this study, CT measurments were fairly constant but epithelial attachment ( junctional and sulcular ) was highly variable.8

Dimensions and Relations of the Dentogingival junction in Humans Gargiulo A., Wentz F., Orban F. J. Periodontol 1961.

This study concluded that the width of junctional epithelium plus connective tissue width was Biologic width; i.e. approximately 2 mm.

The means value for CT 1.07 mm, epithelial attchment 1.66 mm ( junctional 0.97, sulcular 0.69 ).9However since then it has been shown that in probing the sulcus, the probe is generally at the deepest position of junctional epithelium.

If a subgingival crown margin is placed in the middle of the gingival sulcus, the crest of bone should be a minimum of 2 mm apically positioned.

10Biologic width Definition:

The width of the junctional epithelium and supracrestal connective tissues that lie between the base of the gingival sulcus and the alveolar crest and represents the area of attachment of the periodontal soft tissues to the tooth .

The average dimension of biologic width is 2.04 mm.

Gargiulo et al. Dimensions and relations of the dntoalveolar junction in humans. J Periodontol 1961.Vacek et al. The dimensions of the human dentogingival junction. Int J Periodontics Restorative Dent 1994.

The rest. Margins should not be placed more than 0.5-1 mm subgingivally, and there should be at least 3 mm distance btw the rest. And alveolar crest.11Biologic width Ingber et al in 1977:

Suggested that the term biologic width relates to the average value of the dentogingival junction, that is 2 mm. An additional 1 mm must be added coronal to the 2 mm dentogingival junction as an optimal distance between the bone crest and a restorative margin.Biologic width When a subgingival crown margin is to be placed it may be necessary to surgically move the crestal bone margin apically so that there is at least 2 mm space between the margin and the bone.

The necessary for 1 mm of connective tissue between the epithelium and bone is a minimal requirement.

Response to violation of biologic width Localized gingival hyperplasia with minimal bone loss. Gingival recession and localized bone loss. Localized infrabony periodontal pocket. Combinations.

De waal & Castellucci: International J Periodont & Rest Dent 1993.

Indications of crown lengthening Restorative purposes. periodontal purposes. Esthetic needs.Indications for crown lengthening Restorative needs:

1. To increase the clinical crown height. 2. To access subgingival caries. 3. To produce a ferrule for post crown restoration. 4. To access a perforation in the coronal third of the root. 5. To relocate the margins of the restorations that are impinging on the biologic width.17Indications for crown lengthening Periodontal needs:

1. To excise hyperplastic gingiva. 2. To apically position gingiva where there is altered or delayed eruption.Indications for crown lengthening Esthetic needs:

1. To correct gummy smile. 2. To increase the length of short teeth. 3. To modify uneven gingival contour.Contraindications for crown lengthening Non restorable teeth.

Teeth that are non functional or not of strategic value.

Inability to maintain adequate plaque control.

Medical condition such as bleeding disorders/ furcation will be exposed/ C:R ratio not favourable/20Contraindications for crown lengtheningWhen adjacent teeth would be severely compromised.

When extensive procedures are required for salvaging the tooth.

Compromising medical conditions.

Contraindications for crown lengthening Smoking.

Thin gingival tissue biotype.

Narrow band of attached gingiva.Not absolute contraindication22Classification of crown lengthening Functional crown lengthening.

Esthetic crown lengthening.crown lengthening

Techniques:

1. Gingivectomy or gingivoplasty.

2. Apically positioned flap procedure including bone resection.

3. Forced tooth eruption with or without fiberotomy.

Jan Lindhe. Clinical periodontology and implant dentistry. Fourth edition.24 crown lengthening techniques

Gingivectomy:

External bevel gingivectomy. Internal bevel gingivectomy.

External: more adequate KG and no bone involvement/ eliminate PD and expose tooth structureInternal: less KGl eliminate PD/ expose tooth/ if correction of bone needed then internal bevel always the choice.25

crown lengthening techniques

2) Apically positioned flap with bone recontouring:

At least 4 mm of tooth structure must be exposed.

During healing the supracrestal soft tissues will proliferate coronally to cover 2-3 mm of the root.

Herrero et al. 1995, Pontoriero 2001.

Gingival tissues have an inherent tendency to bridge abrupt changes in the countor of the bone crest, so in order to retain gingival margin at its new apical position, bone recountoring must be performed at adjacent teeth as well.27

Apically positioned flap with bone recontouring

Indications: - Multiple teeth.

Contraindications: - Single tooth.Single teeth in esthetic zone28

crown lengthening techniques

3) Forced tooth eruption:

Orthodontic tooth movement can be used to erupt teeth in adults. The tooth must be extruded a distance equal or slightly longer than needed. A full thickness flap then is elevated and bone recontouring is performed to expose sound root structure.

Ritan 1967, Ingber 1974, Potashnick & Rosenberg 1982 .

Forced tooth eruptionIndications: - At sites where removal of attachment and bone from adjacent teeth must be avoided. - Reducing PD at sites with angular bony defects. - Level and align gingival margins.

Contraindications: - Few teeth remaining. t

Brown 1973, Ingber 1974, 1976.Angular bony defects at the problem tooth can be reduced while the attachment level at the adjacent tooth surface remains unchanged.35

Forced tooth eruption with fiberotomy Scalpel is used at 7-10 days intervals.

Indications: - CL at sites where it is important to maintain unchanged the location of the gingival margin at adjacent teeth.

Contraindications: - Teeth associated with angular bony defects.

- Scalpel is used to sever the supracrestal CT fibers , preventing the crestal bone from following the root in coronal direction.41

Functional crown lengthening Exposure of sound tooth structure.

1. Inadequate amount of tooth structure for proper restorative therapy. 2. Subgingival location of fracture lines. 3. Subgingival location of carious lesions.

Jan Lindhe. Clinical periodontology and implant dentistry. Fourth edition.Indicated if the clinical crown height cannot provide adequate retention. ( tooth surface loss usually max and man ant teeth, reduction in interocclusal space)44

Functional crown lengthening Coslet classification: by Coslet et al 1977

- Type I: Adequate keratinized gingiva(2mm). - Type II:Inadequate keratinized gingiva(