Chin augmentation (mentoplasty) using an alloplastic implant is a highly common cosmetic surgical procedure. Intended to project the chin and harmonize facial proportions, chin implants are classified by the FDA as Class II medical devices under the product code FWP (Prosthesis, Chin, Internal).
While the surgery is often marketed as a simple, low-risk procedure that can be performed under local anesthesia in under an hour, chin implants sit in a complex anatomical zone. They are placed directly against the mandibular bone and in close proximity to the bilateral mental nerves, which provide sensation to the lower lip and chin. Over time, the mechanical presence of the implant can trigger chronic tissue changes.
This article analyzes the FDA’s Manufacturer and User Facility Device Experience (MAUDE) database for chin implants, breaks down the primary failure modes, and examines the clinical mechanisms of mandibular bone resorption and nerve injury.
FDA MAUDE database breakdown for product code FWP
To understand what goes wrong with chin implants in clinical practice, we analyzed the public FDA MAUDE database. Filtering for product code FWP yielded 237 adverse-event reports spanning historical entries through mid-2026.
Every MAUDE report carries an official event classification. For the 237 FWP reports, that breakdown is:
+----------------------------------------------------------------------+
| FDA MAUDE Chin Implant (FWP) — Official Event Type |
+----------------------------------------------------------------------+
| Event Type | Reports | Share |
+-----------------+---------+------------------------------------------+
| Injury | 191 | 80.6% |
| Malfunction | 35 | 14.8% |
| Other | 8 | 3.4% |
| Death | 1 | 0.4% |
| Not specified | 2 | 0.8% |
+-----------------+---------+------------------------------------------+
Injury reports dominate — more than four in five FWP events involve harm to a patient rather than a device that simply failed to work as intended. The single death in the dataset is a reminder that even "cosmetic" chin hardware is implanted against bone, near nerves and the oral cavity.
What the narratives describe
The official event type does not say what went wrong, so we read the narrative text of each report. Three complication themes recur. Counting how many of the 237 narratives reference each theme:
+----------------------------------------------------------------------+
| FDA MAUDE Chin Implant (FWP) — Narrative Theme Mentions |
+----------------------------------------------------------------------+
| Theme | Reports mentioning it (of 237) |
+-----------------------+----------------------------------------------+
| Infection | ~96 |
| Nerve injury / numb | ~6 |
| Bone resorption | ~1 |
+-----------------------+----------------------------------------------+
These are narrative keyword mentions, not mutually exclusive — a single report can describe an infected implant that also caused numbness — and they are not incidence or prevalence rates. Even with that caveat, infection is by far the most common reason a chin implant ends up back in the operating room; sensory nerve injury and bone resorption appear only as small minorities of the narratives. (The near-absence of bone resorption from MAUDE is itself informative — see the section below: radiographic studies find it is common but overwhelmingly subclinical, so it rarely gets escalated to the FDA as a discrete adverse event.)
A note on what MAUDE can and cannot tell you: reporting to MAUDE is voluntary and inconsistent, reports can be incomplete or duplicated, and the data reflect only what was submitted — not every device or every adverse event. These counts describe what is in the database, not how often complications truly occur in practice.
Mandibular bone resorption: pressure-induced remodeling
One of the most unique and under-discussed risks of chin implants is mandibular bone resorption (also called bone erosion or settling). Because the implant is placed directly onto the hard cortical bone of the mandible and sits beneath the strong mentalis muscle, it is subjected to constant pressure during facial expression, chewing, and speaking.
The biological mechanism
Bone is a dynamic tissue that constantly remodels in response to mechanical stress (Wolff's Law). When a firm implant is compressed against the bone by the overlying muscle, the localized pressure exceeds the capillary perfusion pressure of the periosteum (the membrane covering the bone). This deprives the underlying bone of blood flow and stimulates osteoclasts—the cells responsible for bone breakdown—to resorb the bone beneath the implant.
This resorption continues until a pressure equilibrium is reached. The implant "sinks" or "settles" into a shallow groove in the bone, creating a radiographic indentation.
Normal Mandible Implant Settling (Resorption)
[mentalis] [mentalis]
v v
|======| (skin) |======| (skin)
| |
/-------\ (fat) /-------\ (fat)
| v (pressure)
( B ) (bone) [ IMPLANT ]
( O ) ====v====
( N ) ( B O N E ) <-- Remodeled
( E ) ( R E S O R B )
What the clinical evidence shows
Radiographic studies consistently find that some degree of bone resorption beneath a smooth silicone chin implant is the rule rather than the exception. Long-term follow-up with lateral chin radiographs has detected erosion in the large majority of patients — one series found it in 14 of 15 patients — and reviews cite prevalence estimates of 75% or higher. That high radiographic prevalence stands in sharp contrast to the MAUDE data, where bone resorption surfaces in only about one narrative of 237 — a gap explained by the fact that subclinical erosion is asymptomatic and almost never escalated to the FDA as a discrete adverse event. The reassurance is that the vast majority of these cases are subclinical:
- The depth of bone erosion is typically less than 2.0 mm (in one series, roughly 80% of patients eroded less than 2 mm).
- The resorption is asymptomatic and does not compromise the structural integrity of the mandible.
- The aesthetic projection of the chin is maintained because the soft-tissue capsule masks the bone loss.
However, in a small subset of cases (as represented in the MAUDE database), severe bone resorption can occur. Erosion can exceed 4.0 to 5.0 mm, penetrating through the hard outer cortical plate into the soft inner cancellous bone. Severe resorption can lead to:
- Tooth root damage: If the implant is positioned too high on the mandible, bone erosion can encroach upon the roots of the lower incisor teeth, causing pain, tooth mobility, or pulp death.
- Loss of aesthetic projection: As the implant sinks deeper into the bone, the chin loses its projected appearance, prompting revision surgery.
- Implant migration: As the bone erodes unevenly, the implant can shift, leading to facial asymmetry.
Material differences: silicone vs. porous polyethylene
The rate of bone resorption is highly dependent on the implant material. Smooth silicone implants (such as those manufactured by Implantech) do not integrate with the surrounding tissue. They are held in place by a slippery fibrous capsule. This lack of tissue integration allows micro-movement and concentrates pressure on the underlying bone, leading to higher rates of resorption.
Porous polyethylene implants (such as Medpor, manufactured by Stryker/Porex) allow surrounding tissue and blood vessels to grow directly into the pores of the material. This tissue integration anchors the implant to the bone, reduces micro-movement, and distributes pressure more evenly, resulting in significantly lower rates of bone resorption. However, the trade-off is that porous implants are extremely difficult to remove if they become infected.
Mental nerve injury: sensory disruption
The second major anatomical risk is injury to the mental nerve. The mental nerve exits the mental foramen (a small opening in the mandible) roughly below the second premolar tooth on each side. It splits into branches that provide sensation to the lower lip, chin, and anterior gingiva (gums).
Mechanisms of nerve injury
In the MAUDE dataset, roughly 6 reports document nerve injuries, numbness, or paresthesia. These occur through three main pathways:
- Surgical traction (neuropraxia): During pocket dissection, the surgeon must identify and retract the mental nerve to slide the implant underneath it. Stretching or bruising the nerve with surgical instruments is common, leading to temporary numbness of the lower lip. This typically resolves within 4 to 12 weeks.
- Direct compression: If the implant is too large or placed too high, its wings (in extended anatomical designs) can sit directly over the mental foramen. The mechanical weight and pressure of the implant compress the nerve against the bone, causing persistent numbness or a painful tingling sensation (paresthesia).
- Transection: Meticulous dissection is required to avoid cutting the nerve. Direct transection causes permanent sensory loss to the lower lip and chin.
Infection and the inevitability of explantation
Infection is the leading reason for device removal in the FWP database, mentioned in roughly 96 of the 237 reports.
An implant is a foreign body. Once bacteria (such as Staphylococcus aureus or Staphylococcus epidermidis) gain access to the implant surface, they form a biofilm—a protective layer of extracellular matrix that shields the bacteria from the patient's immune cells and systemic antibiotics.
The MAUDE narratives show a consistent clinical timeline:
- An infection develops anywhere from 2 weeks to 6 months post-operatively (often presenting as swelling, redness, or a draining sinus tract inside the mouth).
- The patient is treated with multiple courses of oral or intravenous antibiotics, which may temporarily reduce symptoms.
- Because the biofilm cannot be eradicated by drugs alone, the infection returns once antibiotics are stopped.
- The clinician is ultimately forced to surgically remove (explant) the chin implant to clear the infection.
Mitigation strategies for providers and patients
To minimize the risks of bone resorption, nerve injury, and chronic infection, clinical protocols emphasize several key steps:
- Implant positioning: The implant must be placed along the lowest border of the mandible (the inferior border of the symphysis) and must sit below the mental foramen. Placing the implant too high increases the risk of tooth root impingement and nerve compression.
- Rigid fixation: Securing the implant to the bone with small titanium screws (rigid fixation) prevents micro-movement and reduces sliding friction, which minimizes pressure-induced bone resorption.
- Proper pocket size: The surgical pocket should be dissected precisely to fit the implant. A pocket that is too large allows the implant to migrate upward toward the nerve or downward under the chin.
- Aseptic surgical entry: Chin implants can be placed through an intraoral incision (inside the mouth) or a submental incision (under the chin). While the intraoral approach leaves no visible scar, it exposes the implant to oral bacteria, carrying a slightly higher infection rate than the submental approach.
Sources
- FDA MAUDE (Manufacturer and User Facility Device Experience) Database — analysis of product code FWP: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/search.cfm
- "Bone Resorption after Use of Silicone Chin Implants, Long-term Follow-up Study with Lateral Chin Radiography" (PMC6110682): https://pmc.ncbi.nlm.nih.gov/articles/PMC6110682
- "Mandibular Bone Resorption Following Chin Augmentation" — Frontiers in Surgery (2022): https://www.frontiersin.org/journals/surgery/articles/10.3389/fsurg.2022.815106/full
- "Bone Changes With Silicone Chin Implants: Clinical Case, Review, and Considerations for Technique Modification" (PMC11805566): https://pmc.ncbi.nlm.nih.gov/articles/PMC11805566
- Bony changes beneath silicone chin implants — radiographic analysis (PMC8240745): https://pmc.ncbi.nlm.nih.gov/articles/PMC8240745
