當牙齒損傷到齒槽骨脊 (Alveolar crest)時,例如深 度齲齒或斷裂所造成,而又必須作上固定假牙時: -> 侵犯 Biologic width : 牙周組織發炎、牙周囊袋形成、附連喪失 (Attachment loss) Biologic Width : 1961 Gargiulo et al. : -> Biologic width = epithelial attachment + connective tissue attachment = 0.97 mm + 1.07 mm = 2.04 mm
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1984 Drs. Nevinsand Skurow : 若與補綴物有關,應該加上牙齦溝深度 Biologic width = 0.69mm +0.97 mm + 1.07 mm = 2.73 mm -> Biologic width 約為 3mm 左右 兩種生物寬度 (Biologic width ) 的界限考慮: 1.B.W. + 0.5 mm = 3.5 mm -> 適用於遭牙周疾病破壞,牙冠牙根比率不佳者,比 3mm 多提供 0.5mm ,來確保牙周復原後,補綴物的邊緣成 supragingival , 便於以後的磨削 2.B.W. + 1.5 mm = 4.5 mm -> 適用於牙冠齒質嚴重缺損,牙冠牙根比率佳的病例,比前一各 多 1mm ,提供圍箍效應 (ferrule effect) ,減少未來補綴物與冠心 根柱受力後旋轉脫離
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Surgery Method forCLP 1. Excessive Gingival Display 2 Apically Positioned flap 3. Bone contouring
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Excessive Gingival DisplayGummy smile Insufficient length of the clinical crowns Gingival margin resides over 1 mm coronal to the CEJ. Gingivectomy / gingiyoplasty precedure
Apically positioned flapwith bone recontouring At least 4 mm of sound tooth structure must be exposed at time of surgery healing supracrestal soft tissues will proliferate coronally to cover 2-3 mm of the root, leaving only 1-2mm of supragingivally located sound tooth structure
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Apically positioned flapwith bone recontouring problem tooth and adjacent teeth to reduce the osseous profile
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Apically positioned flapwith bone recontouring Indication --multiple teeth in a quadrant or sextant of the dentition Contraindication --single teeth in the esthetic zone