Presents Dr. E. Barrie Kenney Professor & Chairman Section of Periodontics 3
E. Barrie Kenney B.D.Sc., D.D.S., M.S., F.R.A.C.D.S. Tarrson Family Endowed Chair in Periodontics.Surgical Techniques for Crown Lengthening Professor and Chairman Division of Associated Clinical Specialties UCLA School of Dentistry
1)Development of AdequateIndications for Crown Crown Preparation Lengthening 2)Esthetics
Development of Adequate Gingival Margins must not Crown Preparation invade Biological Width Requirements for Periodontal Health.
There must be a minimum ofBiological Width 1mm between the apical level Requirements of the Junctional Epithelium and the bone crest.
Crown Margins which extend An inappropriate crownapically beyond the Junctional margin increases plaqueEpithelium can violate the accumulation in closerequirements for periodontal proximity to bone crest.health.
Both Central Incisors andright lateral incisor havecrowns violating BiologicWidth concepts.
Gargiulo A., Wentz F., Orban F. This study measuredDimensions and Relations of dimensions of tissuesthe Dentogingival Junction in involved in Biological WidthHumans. considerations. J. Periodontol 1961 32:261
Used histologic sections to These are not clinicallymeasure average dimensions of accurate due to distortionbiologic width. with histologic processing.
Sulcus Gingival sulcus 0.69 mmdepth Junctional epithelium 0.97 mm This study said width of junctional epithelium plus Connection tissue 1.07 mm Biologic attachment coronal to Width connective tissue width was bone Biologic width; i.e. approximately 2 mm.
However since then it hasbeen shown that in probingthe sulcus, the probe isgenerally at the deepestposition of junctionalepithelium.
If a subgingival crown marginis placed in the middle of thegingival sulcus, the crest ofbone should be a minimum of2 mm apically positioned.
When a subgingival crownmargin is to be placed it may The necessary for 1 mm ofbe necessary to surgically connective tissue betweenmove the crestal bone margin the epithelium and bone is aapically so that there is at minimal requirement. Largerleast 2 mm space between the dimensions can be compatiblemargin and the bone. with healthy tissues.
This is the method of choiceUse of Flap Surgery with when crown margins will Osseous Resection impinge on the Biologic Width.
Periapical Radiographs areneeded to ensure sufficient rootlength is available. This casecannot have surgical crownlengthening and both premolarsneed to be extracted.
This patient had extensivetooth wear and loss of VerticalDimension
There was insufficient clinicalcrown volume of the incisorsfor adequate retention so flapsurgery was indicated.
Buccal full thickness flapelevation to expose at least 3mm of crestal bone.
Palatal flap elevation to exposeat least 3 mm of crestal bone.
The gingival level of new crownmargin is estimated and boneremoved so crestal level is 2mm apical to this.
Buccal crown margins will besubgingival for esthetics. Somargins will be in middle ofgingival sulcus i.e. 1 mmcoronal to probing depth, addanother 1 mm for connectivetissue to determine bone level.
Palatal crown margin will besupragingival. So allow 1mmfor connective tissue plus 2 to 3mm for sulcus with bone level 3to 4 mm apical to level of crownmargin.
Most cases need flap and osseous surgery.Gingivectomy for Crown Gingivectomy used when have adequate band of Keratinized Lengthening tissue and bone crest is positioned apically with an initial wide Biological Width.
Soft tissue removal will beadequate for exposure of soundtooth for margins with a 1 mmFerrule Extension.
Electrosurgery used forgingivectomy. This can also bedone with scalpels or laser.
Tissue recontoured to exposeroot surfaces for adequatepreparation of margins.
Provisional restorations at 12weeks. Marginal gingiva is nowstable so final subgingivalcrowns can be completed.
Final crown restorationsshould not be completed until In esthetic areas a minimuma minimum of 6 weeks after of 12 weeks after-surgery issurgery in order to minimized required to be sure no furtherfurther tissue loss due to gingival recession will occur.trauma of impressions.