Crown Lengthening PDF

Tishk International University Dentistry Faculty Periodontics Department Periodontology CROWN LENGTHENING Dr. Jafar Naghshbandi D.D.S ; M.S , PhD Diplomate Of The American Board Of Periodontology  SPECIAL THANK...

Tishk International University Dentistry Faculty Periodontics Department Periodontology CROWN LENGTHENING Dr. Jafar Naghshbandi D.D.S ; M.S , PhD Diplomate Of The American Board Of Periodontology  SPECIAL THANKS WHOEVER TAUGHT ME A WORD MADE ME HIS SERVANT. Dr. Raul Caffesse Dr. Jim Simon  Objectives Definition Crown lengthening Indications Rationale A. Esthetic and functional concerns B. Biological width C. Ferrule length Crown lengthening methods A. Gingivectomy B. Flap+ Osseous Resection C. Apically positioned flaps (APF) D. APF + Osseous resection Surgical crown lengthening Crown lengthening Contraindications Crown lengthening Orthodontic techniques Clinical cases Conclusion  Esthetic periodontal corrective procedures Inadequate tooth structure for restoration: 1.surgical crown lengthening 2.Forced eruption with fiberotomy Recession: 1.Free gingival / lateral pedicle graft 2.Subepithelial connective tissue graft 3.Guided tissue regeneration Edentulous ridge defects: 1.Onlay/inlay grafts 2.Synthetic bone grafts Gingival overgrowth: 1.Gingivectomy / Gingivoplasty 2.Apically postioned flap with or without ostectomy Electrosurgery/laser for esthetic contouring  Esthetic periodontal corrective procedures Inadequate tooth structure for restoration: 1.surgical crown lengthening 2.Forced eruption with fiberotomy Recession: 1.Free gingival / lateral pedicle graft 2.Subepithelial connective tissue graft 3.Guided tissue regeneration Edentulous ridge defects: 1.Onlay/inlay grafts 2.Synthetic bone grafts Gingival overgrowth: 1.Gingivectomy / Gingivoplasty 2.Apically postioned flap with or without ostectomy Electrosurgery/laser for esthetic contouring Definition Crown lengthening (CL) is any procedure by which the amount of tooth exposed supragingivally is increased.  Clinical crown Clinical crown Is that portion of the tooth that is coronal to the alveolar crest Biological width  Crown lengthening Indications Inadequate clinical crown for retention due to extensive caries, subgingival caries or tooth fracture Short clinical crowns Placement of sub gingival restorative margins. Unequal, excessive or unaesthetic gingival levels for esthetics Planning veneers or crowns on teeth with the gingival margin coronal to the cemeto enamel junction (delayed passive eruption) Teeth with excessive occlusal wear or incisal wear Restorations which violate the biologic width. Assist with impression accuracy by placing crown margins more supragingivally.  Rationale A. Esthetic and functional concerns B. Biological width C. Ferrule length A. Esthetic and functional concerns Exposure of subgingival caries Exposure of a fracture High lip line, delayed passive eruption, excess gingival display Biological width Biologic width is the distance established by the junctional epithelium and connective tissue attachment to the root surface of a tooth Dimension and components of biologic width Mean depth of the histologic sulcus is 0.69 mm Mean junctional epithelium measures 0.97 mm (0.71-1.35 mm) Mean supraalveolar connective tissue attachment is 1.07 mm (1.06-1.08 mm) The total of the attachment is 2.04 mm (Gargiulo et al, 1961) Significance of Biological Width In Restorative dentistry Biological width is the natural seal that develops around teeth and dental implants, protecting the alveolar bone from infection and disease Evaluation of biologic width violation Clinical method Bone sounding Radiographic evaluation  Clinical method Signs of biologic width violation are: Chronic progressive gingival inflammation around the restoration Bleeding on probing Localized gingival hyperplasia with minimal bone loss Gingival recession Pocket formation Clinical attachment loss and alveolar bone loss. Biologic width violation  Bone sounding The biologic width can be identified by probing under local anesthesia to the bone level and subtracting the sulcus depth from the resulting measurement If this distance is less than 2 mm at one or more locations, a diagnosis of biologic width violation can be confirmed.  Radiographic evaluation Bitewing Radiographic interpretation can identify interproximal violation of biologic width. However, since more common location of biologic width violation is on the mesiofacial and distofacial line angles of teeth, radiographs may not be diagnostic in all cases Parallel profile radiographic (PPR) technique Is to measure the dimensions of the dento gingival unit (DGU) and hence the biologic width. This technique could be used to measure both length and thickness of DGU with accuracy, as it is simple, concise, noninvasive and reproducible method.  Biologic considerations MARGIN PLACEMENT AND BIOLOGICAL WIDTH Supragingival Equigingival Subgingival  Margin placement guidelines 3 Rules should be followed 1. If the sulcus probes 1.5mm or less, Place the margin 0.5mm below the gingival crest. 2. If sulcus probes more than 1.5mm- Place the margin 12 depth of the sulcus below the crest. 3. If sulcus probes more than 2.0mm, Esp. on facial aspect- Gingivectomy should be done & create a 1.5mm sulcus – Place the margin 0.5mm below the gingival crest.  Biologic considerations Supragingival margin least impact on the periodontium Equigingival margin Previous thought: retains more plaque than supra & sub gingival margins therefore results in greater gingival inflammation This is not valid today, from a periodontal viewpoint, both supragingival and equigingival margins are well tolerated Subgingival margin Greatest biologic risk Not as accessible as supra or equigingival for hygiene procedures.  C. Ferrule length A dental ferrule is an encircling band of cast metal around the coronal surface of the tooth. A 360-degree metal collar of the crown surrounding the parallel walls of the dentine extending coronal to the shoulder of the preparation. (Sorensen and Engelman) The word originates from combining the Latin for iron (ferrum) and bracelets (viriola) (Brown1993).  Ferrule length A basic prosthetic concept is that the greatest amount of retention and resistance to dislodgement of the restoration occurs at the apical one- third of the preparation. Apical 1/3 of the preparation provide the greatest retention and resistance of the restoration With1~2mm the ferrule height material forces of occlusion dispersed onto the PDL rather than post and core  Ferrule length A. A tooth prepared for a full- coverage crown with a ferrule B. A tooth prepared for a full- coverage crown without a ferrule. Crown lengthening Surgical crown lengthening Orthodontic crown lengthening  Crown lengthening methods Gingivectomy: when there is an adequate band of Keratinized gingiva (KG) (≥2 mm) and distance from CEJ to alveolar bone crest is (≥2 mm) Flap + Osseous Resection: when there is an adequate band of Keratinized gingiva (KG) (≥2 mm) and distance from CEJ to bone crest is (