Class III malocclusion has always been orthodontics’ plot twist — unpredictable, stubborn, and full of surprises. For decades, clinicians believed the villain was a big, bad mandible. Turns out? Many children actually have a retruded maxilla, not a hypergrown mandible.

Cue the protraction facemask — an appliance designed to pull the maxilla forward during childhood, before growth makes the situation harder to fix.

But here’s the real question every orthodontic student should be asking:

👉 Does the facemask actually work?
And if yes, by how much, in whom, and under what conditions?

A group of researchers (Kim et al., 1999) got tired of the confusion and did something smart:
They conducted a meta-analysis — essentially combining data from 14 acceptable studies out of 440 initially screened — to find real, clinically meaningful answers.

🔍 Why a Meta-Analysis Was Needed

Research on facemask therapy was messy:

• Different appliances
• Different ages
• Different force levels
• Different study designs
• Many case reports, few controlled trials

And because each study had small sample sizes, the orthodontic world couldn’t agree on:

• the best age to start treatment
• whether palatal expansion helps
• how much skeletal vs dental effect is actually achieved

A meta-analysis solves this by pooling data to reveal the big picture.

1. Overall Effects of Facemask Therapy

Parameter	Direction of Change	Clinical Meaning
SNA	↑ increases	Maxilla moves forward
SNB	↓ decreases	Mandible rotates down-back
ANB	↑ increases (~2.8° mean)	Skeletal relationship improves
Wits	↑ improves (4–5 mm)	Sagittal correction achieved
Mandibular plane angle	↑ increases	Down-back rotation of mandible
Palatal plane angle	Slight ↓	Mild clockwise tipping
Upper incisor inclination	↑ labial proclination	Dental compensation
Lower incisor inclination	↓ uprighting	Chin-cup and soft tissue effects
Point A	Moves forward	Skeletal protraction confirmed

2. Expansion vs. Non-Expansion Groups (RPE vs No RPE)

Finding	RPE Group	Non-Expansion Group	Interpretation
Maxillary forward movement	Similar	Similar	Both effective
Mandibular rotation	Similar	Similar	Similar skeletal effect
ANB improvement	Similar	Similar	No major difference
Upper incisor proclination	LESS	MORE (+2.8°)	RPE reduces dental side-effects
Treatment duration	Shorter	Longer	RPE may speed skeletal effect
Overall skeletal response	Slightly more favorable	Slightly less favorable	RPE enhances orthopedic effect

3. Younger vs. Older Age Groups

Age Group	Treatment Response	Magnitude of Advantage	Clinical Interpretation
Younger patients (4–10 yrs)	Larger skeletal change	+0.6° SNA, +1.0° ANB, +1.3 mm Wits	Earlier = better
Older patients (10–15 yrs)	Still responds well	Slightly reduced effect	Still worth treating
Overjet correction	More skeletal	More dental	Younger = orthopedic, Older = dentoalveolar
Variation	Higher in younger	Lower in older	Younger growth less predictable

4. Expected Treatment Effects (Averaged Across 14 Studies)

Variable	Combined Mean Change	Interpretation
SNA	+1.7°	Maxillary advancement
SNB	–1.2°	Mandibular backward rotation
ANB	+2.79°	Significant skeletal correction
Wits	+4–5 mm	Sagittal improvement
Upper incisor torque	+7°	Labial flaring
Lower incisor torque	–3°	Uprighting
Point A horizontal	Forward movement	Confirms orthopedic action
Total treatment duration	~6–12 months	Typical clinical protocol

🎒 What Ortho Students Should Understand by the End

Here is the logical framework you must take away:

1. Class III ≠ always mandibular excess

Maxillary retrusion is common → treat the right jaw.

2. Facemask therapy produces both skeletal and dental changes

But the skeletal component is real, reproducible, and meaningful.

3. Early treatment works best, but late mixed dentition still responds

Don’t write off 10–12-year-olds.

4. Expansion improves efficiency, but doesn’t determine success

It’s an enhancer, not a prerequisite.

5. Meta-analysis helps us see beyond isolated case reports

This study cuts through the clinical noise to reveal clear trends.