Crown lengthening 10m university question with table of contents

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crown lengthening procedure indications biologic width periodontal university clinical guidelines

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https://www.ncbi.nlm.nih.gov/books/NBK599507/

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clinical crown lengthening surgery apically positioned flap osseous resection diagram

Crown Lengthening

Definition
Objectives
Indications
Contraindications
Preoperative assessment
Techniques
Surgical procedure
Postoperative care
Complications
Conclusion

1. Definition

Clinical crown lengthening is a periodontal surgical procedure performed to expose additional sound tooth structure by removing gingiva alone, or gingiva together with alveolar bone, and repositioning the gingival margin apically.

It is done for:

Functional/restorative reasons: to expose subgingival caries, fracture margin, or restoration margin.
Aesthetic reasons: to correct short-looking teeth, altered passive eruption, gingival asymmetry, or excessive gingival display.

The objective is to permit a well-fitting restoration while preserving the supracrestal tissue attachment, formerly termed biologic width. The European Federation of Periodontology overview describes both functional and aesthetic applications.

2. Objectives

Expose adequate tooth structure for restoration.
Obtain retention and resistance form for a crown.
Establish an adequate ferrule effect in endodontically treated teeth.
Permit isolation during restorative treatment.
Place restoration margins without invading periodontal soft tissues.
Correct gingival contour and improve smile aesthetics.
Facilitate plaque control and maintenance of periodontal health.

3. Indications

Functional indications	Aesthetic indications
Subgingival caries	Excessive gingival display or “gummy smile”
Crown or root fracture extending below gingival margin	Altered passive eruption
Inadequate clinical crown height for retention	Short clinical crowns
Need for ferrule in endodontically treated tooth	Uneven gingival margins
Subgingival restorative margin causing gingival inflammation	Gingival enlargement with suitable bone level
Tooth preparation extending close to alveolar crest	Improvement of tooth proportions

The tooth must be otherwise restorable and have an acceptable periodontal and endodontic prognosis. A periodontal surgery review identifies subgingival caries, coronal fracture, and inaccessible restorative margins as key restorative indications.

4. Contraindications

Tooth with hopeless prognosis or insufficient remaining root length.
Unfavourable crown-root ratio after surgery.
Advanced mobility or severe periodontal bone loss.
Furcation involvement likely to be exposed after osseous resection.
Inadequate attached or keratinized gingiva.
Poor plaque control or active periodontal inflammation.
High caries activity not controlled.
Aesthetic zone where postoperative recession or long clinical crown would be unacceptable.
Medical conditions that preclude elective periodontal surgery, unless appropriately controlled.
Inability of patient to maintain oral hygiene or attend follow-up.

5. Preoperative Assessment

A thorough examination is essential.

Clinical examination

Assess plaque and gingival inflammation.
Measure probing depth and gingival margin level.
Determine width of keratinized tissue.
Evaluate tooth mobility, furcation, crown-root ratio, and smile line.
Identify the desired final restorative margin.

Radiographic examination

Periapical radiograph to assess:
- Root length and morphology
- Alveolar bone height
- Furcation anatomy
- Periapical status
- Crown-root ratio after anticipated bone removal

Bone sounding After local anaesthesia, transgingival probing determines the distance from the gingival margin to alveolar crest. This helps decide whether only gingivectomy is sufficient or osseous resection is required.

Traditionally, about 3 mm of space from the planned restorative margin to the alveolar crest is aimed for: approximately 2 mm for supracrestal tissue attachment plus about 1 mm sulcus depth. This is a practical guideline, not an identical value in every patient. This clinical report similarly describes maintaining at least 3 mm between crestal bone and prosthetic margin.

6. Techniques

Technique	Indication	Main feature
Gingivectomy	Adequate distance, usually at least 3 mm, between bone crest and planned gingival margin; sufficient keratinized gingiva	Removes excess soft tissue only
Apically repositioned flap without osseous resection	Need to expose tooth structure with adequate bone-to-margin distance	Flap is placed apically
Apically repositioned flap with osseous resection	Bone crest is too close to proposed restorative margin	Bone is recontoured and flap positioned apically
Orthodontic extrusion or forced eruption	When surgical bone removal would compromise adjacent teeth, furcation, or aesthetics	Tooth structure is moved coronally, sometimes followed by minor surgery

The EFP notes that gingivectomy is appropriate where the bone crest is at least 3 mm from the proposed gingival margin, while an apically positioned flap with osseous resection is generally required when it is closer than 3 mm. EFP clinical guidance

7. Surgical Procedure: Apically Positioned Flap with Osseous Resection

Phase I therapy
Complete scaling, plaque-control instruction, and control inflammation before surgery.
Local anaesthesia and marking
Mark the desired new gingival margin after diagnostic assessment.
Incision
Perform internal bevel incision followed by crevicular incision. Remove the gingival collar where necessary.
Flap reflection
Elevate a full-thickness mucoperiosteal flap to expose alveolar bone and root surfaces.
Debridement
Remove granulation tissue and thoroughly debride root surfaces.
Osseous resection and recontouring
- Osteoplasty: reshaping of non-supporting bone.
- Ostectomy: removal of supporting bone.
  Bone is reduced to create adequate space for soft-tissue attachment and to establish physiologic bony contour.
Apical positioning of flap
Reposition the flap apically at the planned level.
Suturing
Secure the flap with interrupted or sling sutures. A periodontal dressing may be used when indicated.

8. Postoperative Care

Analgesics as required.
Chlorhexidine mouth rinse may be prescribed for short-term chemical plaque control.
Avoid brushing the operated area initially; maintain hygiene elsewhere.
Soft diet and avoidance of trauma to surgical site.
Review after approximately 7 to 14 days for suture removal.
Regular periodontal maintenance and reassessment of tissue healing.
Definitive restoration should generally be delayed until soft tissues have stabilized, especially in the aesthetic zone. Premature restoration can be affected by coronal rebound of the gingival margin.

9. Complications

Postoperative pain, swelling, and bleeding.
Gingival recession and root sensitivity.
Poor aesthetic outcome due to elongated teeth or asymmetrical gingival margins.
Loss of interdental papilla or black triangles.
Furcation exposure.
Unfavourable crown-root ratio or increased tooth mobility.
Delayed healing or infection.
Re-growth or coronal migration of gingiva.
Violation of supracrestal tissue attachment if insufficient bone is removed, resulting in chronic inflammation, pocketing, recession, or recurrent loss of attachment.

10. Conclusion

Crown lengthening is an important periodontal procedure that provides additional clinical crown height for restorative and aesthetic purposes. Proper case selection, bone sounding, maintenance of adequate space for supracrestal tissue attachment, appropriate selection of technique, and careful management of aesthetic implications determine long-term success.

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