Biologic Width

1. PERIODONTICS SEMINAR BIOLOGIC WIDTH & ITS IMPLICATIONS

2. Biologic width • Definition Physiologic dimension of the junctional epithelium and connective tissue attachment above the level of the alveolar crest • Mean values junctional epithelium – 0.97mm connective tissue attachment – 1.07mm biologic width = 0.97mm+1.07mm = 2.04mm

3. Variations0.75mm – 4.3mm 0.75mm – premature violation 4.3mm – crown lengthening procedures

4. Margin placement & biologic width - supra-, sub-, equi-gingival - subgingival placement • esthetic • extension of caries • retention & resistance form • Margin within about 1mm of gingival sulcus ~ ideal • Biologic width evaluation - variations to be considered - radiographic ~ superimposition - discomfort on probing - ‘sounding to bone’ ~ probing through anaesthetised

5. attachment tissues till bone is touched ~ subtract from gingival sulcus depth

6. Responses to biologic width violation 2 responses : - gingival inflammation only - gingival recession with bone loss • thin,fragile,highly scalloped gingiva ~ more chances of gingival recession • thin alveolar housing ~ horizontal bone loss • thick alveolar housing ~ vertical bone loss

7. a) thin marginal bone, b) thick marginal boneA lower incisor with thin labial bone (A). Bone loss can become vertical only when it reaches thicker bone in apical areas. Upper molars with thin facial bone, where only horizontal bone loss can occur (B). Upper molar with a thick facial bone, allowing for vertical bone loss

9. Correcting biologic width violation - 2 options • Surgery • Orthodontic extrusion - surgery ~ more rapid, bone removed away from margin by measured distance of ideal biological width for that patient + additional 5mm for ‘ferrule’ effect - interproximal violation ~ surgery contraindiated - orthodontic extrusion ~ interproximal violations 2 types ; - low orthodontic extrusion force ~ bone & gingiva follows ~osseous contouring - rapid orthodontic extrusion force with supracrestal fibrotomy~ gingival inflammaton ~ bone does not follow

10. Accelerated orthodontic eruption (rapid tooth eruption) in conjunction with fibrotomy procedure (a, b). The radiographs show the "positive" angular crest on the "control" distal side and the unchanged crest on the mesial "test" side

11. Crown lengthening procedures & biologic width - short clinical forms - retention & resistance form - extention of caries • Methods - removal of soft tissue only ~ adequate attached gingiva & > 3mm of tissue coronal to the bone crest or - removal of both soft tissue and alveolar bone~ inadequate attached gingiva & < 3mm of tissue coronal to bone crest - gingivectomy or flap technique - subgingival extention of caries ~ additional 1mm of bone removed to provide ‘ferrule’ effect

12. Conclusion The average biological width is 2.04mm considering the variations which may occur in each person. This concept establishes a healthy state of the periodontium and any violations to it, by procedures like clinical crown

13. lengthening, inadverent placement of margins of restoration breaching the attachment apparatus, will hinder the healthy state of the periodontium resulting in periodontal problems as has been mentioned. Thus it is essential to properly evaluate the biologic width of the particular case and preserve this entity before and while performing such treatment modalities. References • Clinical Periodontology by Carranza • www.wikipedia.com • Stomatologija,Baltic Dental & Maxillofacial Journal,2006 • www.pubmed.com

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