The safe zone for placement of chin implants

Area of Science:

• Anatomy
• Plastic Surgery
• Surgical Safety

Background:

• Alloplastic chin augmentation necessitates precise identification of the mental foramen and mentalis muscle origin.
• Failure to do so can lead to lower lip paresthesia, incompetence, or chin ptosis.
• This study defines a safe dissection zone along the mandible's inferior border for implant placement.

Purpose of the Study:

• To define a safe zone of dissection for alloplastic chin augmentation.
• To identify anatomical landmarks crucial for avoiding neurovascular complications.

Main Methods:

• Dissection of fourteen fresh cadaveric hemifaces using loupe magnification.
• Identification of the mentalis muscle origin and mental foramen using established landmarks.
• Measurement of vertical distances from the mandibular border to define the safe dissection zone.

Main Results:

• The mentalis muscle originates from the alveolar process below incisor roots.
• The mental foramen is typically located below the first and second premolar roots.
• The mentalis origin is 1.8 ± 0.3 cm and the mental foramen is 1.5 ± 0.2 cm superior to the mandibular inferior border, establishing a safe zone.

Conclusions:

• A defined safe dissection zone is identified for alloplastic chin augmentation.
• This safe zone is applicable to both submental and intraoral incision approaches.
• The findings are also relevant for reconstructive and orthognathic mandible procedures.