Labial incompetence: a marker for progressive bone resorption in silastic chin augmentation

Area of Science:

• Oral and Maxillofacial Surgery
• Plastic Surgery
• Biomaterials Science

Background:

• Bone erosion is a common complication of silicone rubber implants used in augmentation genioplasty.
• While generally self-limiting, severe erosion can jeopardize teeth or alter mental nerve sensibility, necessitating implant removal.
• Current understanding of erosion etiology has overlooked the role of mentalis muscle function.

Observation:

• A study examined six patients with Silastic implants, assessing labial competence and mentalis muscle activity.
• Preoperative labial incompetence and mentalis muscle hyperactivity correlated with progressive bony erosion below the implants.
• Erosion severity ranged from grade II to III, with one case exposing dental roots.

Findings:

• The study identified a direct correlation between preoperative labial incompetence, mentalis muscle hyperactivity, and the progression of mandibular bone erosion.
• Mentalis muscle strain, even secondary to denture use, was associated with severe resorption.
• Labial incompetence appears to be a reliable indicator of ongoing mandibular resorption post-Silastic augmentation.

Implications:

• An alternative surgical approach may be beneficial for microgenic patients with lip strain and mentalis muscle hyperactivity.
• Routine follow-up examinations and radiographs are recommended for patients with existing Silastic chin implants who exhibit labial incompetence.
• Early identification of labial incompetence can help predict and potentially mitigate significant bone resorption and its complications.