orthodontics

Functional genioplasty in growing patients

Anisha ValliLeave a comment

🎯 You’re an orthodontic student wondering: “When should a genioplasty be done? What’s the deal with remodeling? Does age really matter?”
Here’s your answer – all decoded from the Angle Orthodontist (2015) paper by Chamberland, Proffit, and Chamberland — in a crisp, clinical, and structured format. 💡📐

🦴 Wait… What’s This Fancy “Functional Genioplasty”?

Back in 1957, two legends—Trauner and Obwegeser—decided the chin needed a glow-up and introduced the inferior border osteotomy of the mandible. 💥 Boom! Chin augmentation was born—not just to make selfies better but to actually help patients functionally. That’s what we call a win-win. 🙌

🪛 More Than Just A Pretty Face: Why Move the Chin?

Let’s break it down:

  • Got a patient with a horizontal deficiency (aka retruded chin)?
  • Or maybe some vertical excess (think long lower face)?

With functional genioplasty, you can move that chin forward and upward—like giving it a motivational speech. 📈😎

And guess what? It’s not just cosmetic. Precious and Delaire (yes, they sound like a law firm, but they’re ortho legends) coined this combo the “functional genioplasty” because it:

  • 💋 Improves lip function
  • 😌 Helps achieve lip competence at rest
  • 💪 Reduces lip pressure on lower incisors (bye-bye proclination problems!)

🔍 Study Recap:

  • 54 patients underwent forward-upward genioplasty.
  • Divided into 3 age groups (<15, 15–19, >19 years).
  • Followed over 2 years to assess bone remodeling, symphysis changes, and post-surgical stability.
  • Compared to a control group that refused surgery.

📊 What This Study Wanted to Figure Out (And Why You Should Care)

This particular study wasn’t just chin-wagging for fun—it had serious ortho goals:

  1. Understand how the chin bone remodels after genioplasty (Does it behave or act out? 🧐)
  2. Track post-surgical stability in both growing and nongrowing patients (Spoiler: not all chins like to stay put! 👀)
🔬 Parameter👶 <15 yrs (Group 1)🧑 15–19 yrs (Group 2)🧔 >19 yrs (Group 3)🧍 Control Group💡 Clinical Significance
Bone Remodeling✅ Most remodeling⚠️ Moderate❌ Least❌ NoneYounger = better regenerative potential
Inferior Border Notch↓ 1.2 mm(Sig.)↓ 0.6 mm (Sig.)↓ 0.3 mm (NS)No changeEarly surgery improves contour smoothing
Apposition at B Point0.7–1.0 mmSameSame-0.4 mm (Resorption)Positive changes across all surgical groups
Symphysis Thickness↑ Significantly↑ Moderate↑ Slight↓ Thin over timeChin strengthens structurally post-surgery
Facial Alveolar Bone Support🆙 Enhanced⚠️ Moderate⚠️ Moderate❌ DeterioratesImproves incisor stability in younger patients
Lingual Bone Apposition✅ Prominent⚠️ Moderate⚠️ Slight❌ AbsentLong-term gain in chin bulk = aesthetic & functional support
Mandibular Growth↔ Not affected↔ Not affected↔ Not affectedNatural progressionNo hindrance to growth post-genioplasty
Relapse (Pg Position)❌ Minimal❌ Minimal❌ Minimal–Genioplasty remains highly stable, even in growing patients
Surgical Limitations✅ Canines erupted✅ Canines erupted✅ Canines eruptedNADon’t operate before mandibular canines erupt (~12–13 yrs)

🧑‍⚕️ Scenario 1: Meet Aarav, Age 13 — Class II with a Retruded Chin

You’re finishing Aarav’s orthodontic treatment. He has:

  • A retruded chin
  • Lip incompetence at rest
  • Mild lower incisor proclination (thanks to elastics and arch expansion)

Your options:

  1. Retract lower incisors? Risk: bone dehiscence, relapse.
  2. Advance the chin (Functional Genioplasty)? Potential benefits:
    • 🦴 More bone formation (especially at the inferior border)
    • 💪 Improved lip competence
    • 🎯 Enhanced incisor stability

🔬 What the study shows:

  • Aarav’s age (<15) puts him in Group 1 — the best bone response!
  • Greater remodeling = smoother chin contours, stronger symphysis
  • Plus, no negative effect on mandibular growth was found.

🧓 Scenario 2: Nikhil, Age 23 — Same Malocclusion, Same Chin Deficiency

Nikhil finishes treatment with a similar skeletal profile as Aarav. You suggest genioplasty.

🧬 What the data shows:

  • Adults (Group 3) had less remodeling.
  • That notch at the osteotomy cut? Barely remodels in adults.
  • Symphysis thickness improves less (only ~1 mm vs. 3+ mm in younger patients)
  • No evidence of harm, but less biological benefit.

Clinical Insight: Functional genioplasty is safe at any age, but biologically more rewarding when done before age 15.

🦷 Scenario 3: Reena, Age 15, Refuses Surgery

She has:

  • Facial convexity
  • Lip strain
  • Thin symphysis
  • Minor chin deficiency

She opts out of genioplasty. You compare her 2-year follow-up with someone who had surgery.

📊 Study Control Group Data:

  • No bone gain. In fact, symphysis got thinner.
  • Bone resorption at B point occurred naturally.
  • Lip incompetence persisted.
  • Lower incisors still looked proclined.

🧠 Conclusion: Without genioplasty, facial convexity and esthetic imbalance remain. Growth alone won’t fix chin deficiency.

🦴 Remodeling Magic: What’s Happening to the Bone?

Functional genioplasty in adolescents causes:

  • Bone apposition at B point (above the chin) – smoothing out facial profile
  • New alveolar bone formation facial to lower incisors – supports tooth roots, reduces relapse risk
  • Lingual bone formation – adds symphysis thickness = stronger chin structure

And all this happens without any bone grafts (unlike some other studies).

❓ Skeletal vs. Chronologic Age?

Good question!

The study used chronologic age instead of skeletal age (like cervical vertebral maturation) because:

  • It’s simpler, radiation-free, and surprisingly more accurate in predicting pubertal growth spurts.
  • It also aligned with prior landmark studies (e.g., Martinez).

🚫 What About Growth Inhibition?

Fear: Early surgery could mess with mandibular growth.

📉 Study results: NO negative effect seen.

  • Growth at the chin remained normal.
  • Mandibular plane angle changes were the same in surgical and control groups.
  • Vertical growth of the lower face continued normally in younger patients.

🧪 Verdict: Genioplasty doesn’t stunt mandibular growth—you’re good to go if permanent teeth have erupted (especially canines around 12–13 yrs).

🔧 Fixation Type: Wire vs Screws?

91% of patients in this study had wire fixation—and it worked beautifully. 💪

  • Stable results.
  • Minimal relapse.
  • Cost-effective!

So don’t feel pressured to use fancy plates or bone screws unless you’re combining with other osteotomies.

📉 Relapse? Myth Busted.

📍 Previous studies said young patients may relapse more.
📍 This study says: Nope!

  • Pg (pogonion) changes were maintained.
  • No significant relapse.
  • Functional genioplasty = super stable (one of the most stable orthognathic procedures out there).

✨ Real-Life Application:

As an ortho student or resident, when you see a patient with:

  • Class II profile
  • Lip incompetence
  • Proclined lower incisors
  • Thin symphysis
  • Low self-esteem due to facial esthetics…

Think beyond elastics and IPR. Functional genioplasty could be the missing piece for long-term stability, function, and confidence.

🦷👨‍⚕️ Remember: You’re not just aligning teeth—you’re shaping faces and futures.

Next time the chin looks shy, help it step up—literally! 😄

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