Short Clinical Crowns and a Gummy Smile: Is Gingivectomy Enough?
A 24-year-old woman is referred for esthetic crown lengthening of the maxillary anterior sextant. She reports a gummy smile and short teeth since adolescence. Her medical history is unremarkable; she takes no medications and does not smoke. Clinical examination shows clinical crown height of 7.0 mm on teeth 11 and 21, a 4-mm gingival display on smiling, probing depths of 2–3 mm, no bleeding on probing, and minimal plaque. The gingival biotype is thick, and the mucogingival junction is apical to the desired new margin. Radiographs show no caries or periapical pathology. After local anesthesia, transgingival bone sounding indicates the distance from the cementoenamel junction to the alveolar crest is 3.5 mm on tooth 11 and 2.0 mm on tooth 21. The patient asks whether simple gingivectomy can give a stable result.
1. What is your differential diagnosis for the short clinical crowns, and which measurements determine whether gingivectomy alone is sufficient?
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The differential must separate true tooth shortness from gingival coverage and skeletal factors. The main diagnosis here is altered passive eruption, in which the gingival margin remains coronal to the cementoenamel junction after eruption. Vertical maxillary excess, anterior tooth wear, and a hyperactive lip elevator can coexist but do not explain the probing findings alone; drug-induced enlargement is unlikely because there is no medication history and no generalized enlargement.
The decisive measurements are: clinical crown height relative to expected proportions; gingival display on smiling; probing depth and bleeding; position of the mucogingival junction; visibility of the cementoenamel junction; and, most importantly, the bone-sounding distance from the cementoenamel junction to the alveolar crest. A margin placed at the cementoenamel junction needs roughly 3 mm of soft-tissue space to the bone for a stable dentogingival unit. On tooth 11 the sounding distance is 3.5 mm, so removing the coronal gingiva to the cementoenamel junction should leave adequate space. On tooth 21 the distance is only 2.0 mm, so gingivectomy alone would leave less than the required space and would risk chronic inflammation, recession, or relapse. Tooth 21 therefore needs ostectomy, whereas tooth 11 may be managed by soft-tissue resection alone if the final margin can be placed at the cementoenamel junction without exposing root excessively.
2. Outline your surgical plan for teeth 11 and 21, including flap design, ostectomy decisions, and closure.
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Plan each tooth according to its bone-sounding value rather than applying one procedure to the sextant. For tooth 11, a conservative internal-bevel gingivectomy or apically positioned flap can expose the cementoenamel junction; because the biotype is thick, an external-bevel gingivectomy is technically feasible, but I would prefer an apically positioned flap if there is any concern about preserving keratinized tissue and creating a stable, scalloped margin. For tooth 21, raise a full-thickness flap with sulcular incisions and papilla-preserving design, then perform ostectomy to establish approximately 3 mm from the planned cementoenamel-junction-level margin to bone. The sounding difference suggests about 1.0–1.5 mm of ostectomy on tooth 21, verified directly with a probe after bone removal.
Use a surgical stent or mock-up to guide the final margin. Incisions should follow the desired scallop and avoid blunting the papillae. Remove ostectomy bone with a round bur under copious irrigation, refine with hand instruments, and confirm the 3-mm distance. Apically position the flap without tension and close with fine monofilament sutures; ensure the flap is not placed so apically that the crown becomes excessively long or the root is exposed. Postoperative instructions should include chlorhexidine rinsing, avoidance of brushing at the site, and review at 7–10 days. The key judgment is that the two adjacent incisors need different bone management despite similar esthetic complaints.
3. Explain the histologic and biologic basis for the 3-mm rule and the main esthetic risks of over-resection.
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The dentogingival junction consists of the sulcular epithelium, junctional epithelium, and supracrestal connective tissue attachment. The junctional epithelium and connective tissue attachment together occupy approximately 2 mm, and the sulcus adds about 1 mm, giving the familiar 3-mm dimension from the restorative margin or cementoenamel junction to bone. If this space is violated, the inflammatory infiltrate in the connective tissue tends to provoke bone resorption and clinical attachment loss until the biologic dimension is re-established. That is why ostectomy must be planned from the future margin to bone, not simply from the current gingival margin.
Over-resection produces esthetic and functional harm: black triangles from lost interdental papillae, root exposure and hypersensitivity, a long rectangular tooth appearance, labial bone loss, and soft-tissue recession that may expose the implant-like root surface. Excessive ostectomy also removes supporting bone and can compromise adjacent teeth. The histologic goal is not merely a longer crown but a stable junctional epithelium and connective tissue seal on a root surface with adequate bone support. In this patient, tooth 11 may tolerate soft-tissue resection, but tooth 21 requires bone reduction to avoid leaving a biologic-width violation. The final judgment should combine sounding, planned margin position, biotype, and the patient's smile line rather than relying on a single number.