Orthodontics glossary for men: Class II, overjet, MSE, and what each one can move

You are twenty-something, staring at a side-profile thread after midnight. Someone has written “Class II,” “overjet,” “MSE,” and “camouflage” as if they were items on a face-changing menu. You can recognize the words, but not the boundary between a tooth moving and a bone moving.

Here is the useful answer: orthodontic vocabulary describes different structures, and those structures do not move by the same amount. The forum's biggest mistake is turning a treatment measurement into a promise about your face.

Every one of these words has a number attached, and the number is smaller than the forum thinks. This is a glossary for reading claims, not a diagnosis or a treatment plan.

Key numbers

• 74.7% — the pooled global distribution of Class I malocclusion in permanent dentition; the range across population studies was 31–97%. Source
• 3 mm — the operational threshold above which overjet was called abnormal in a major population review. Source
• 1.80 mm — the mean mandibular-length gain attributed to Twin Block versus untreated controls in a randomized-trial meta-analysis. Source
• 2.33 mm vs 6.55 mm — mean skeletal versus dental intermolar expansion reported for MARPE, the appliance family that includes MSE. Source
• 1.96 mm — the average lower-lip retraction associated with extraction in one large soft-tissue meta-analysis. Source
• 21% — pooled persistent lower-lip and chin sensory disturbance one year after sagittal split osteotomy. Source

Table of contents

• How to read this glossary
• The classification vocabulary
• Measurements: overjet, overbite and the rest
• Appliances that move teeth
• Appliances that claim to move bone
• The surgical vocabulary
• Terms that circulate without a source
• How to cite this page
• The bottom line
• Sources

How to read this glossary

Every entry carries one of three labels. Measured means studies report a specific change, Contested means reviews disagree, and No evidence found means we could not locate a credible outcome record. A study number is a measurement, not a promise about your face.

The classification vocabulary

Class I

Measured. Angle's Class I meant normal mesio-distal dental-arch relationships with front-teeth problems—not a “good face.” It was 74.7% globally (31–97% range): occlusal, not facial. Primary classification.

Class II

Measured. Class II meant lower-jaw retrusion with distal lower-tooth occlusion; pooled global prevalence was 19.56%, not profile severity. Original paper split it into Division 1 (prominent upper incisors, narrow arch) and Division 2 (bunched/inward-inclined incisors).

Class III

Measured. Class III is lower-jaw protrusion, with the lower teeth meeting mesial to normal; the global pooled distribution was 5.93%. It may be dental, skeletal, or both, and it does not say how far forward anything sits. Angle's 1899 definition is narrower than the forum word “underbite.”

The measurements: overjet, overbite and the rest

Overjet

Measured. Overjet is the horizontal distance between upper and lower incisors. One review treated anything above 3 mm as abnormal and found it in 20.14% of permanent dentitions. Moving teeth reduces overjet, and so does skeletal correction, but neither is the same as growing a longer lower jaw. See the population definitions.

Overbite

Measured. Overbite is vertical overlap, counted as deep above 2.5 mm and open below 0 mm. Deep overbite appeared in 21.98% of permanent dentitions globally, while the average overbite in US NHANES III was 2.9 mm. See overbite and facial appearance.

Crossbite

Measured. Posterior crossbite required more than two affected teeth in the definition used, and it affected 9.39% of permanent dentitions globally. It describes how the arches fit in width, not how strong a jaw is. Source.

Crowding and irregularity

Measured. Only 35% of US adults had well-aligned mandibular incisors in NHANES III, and irregularity affected social acceptability and function in 15%. Crooked lower front teeth are ordinary, not defective structure, and this US survey beats a forum anecdote.

Appliances that move teeth

Braces and clear aligners

Contested. Across 887 adults in 11 studies, aligners scored 9.9 points worse on ABO grading and carried 1.6 times the risk of an unacceptable result. A 2025 review found no difference in non-extraction cases, but better quality from fixed appliances when teeth were extracted. Compare the evidence by complexity: invisible is not equivalent.

Functional appliance

Measured. Compared with no treatment, functional appliances reduced overjet by 5.46 mm (fixed) or 4.62 mm (removable) on low-quality evidence. The jaw-length gain is a smaller, separate number: 1.53 mm overall, and 1.80 mm for Twin Block. The Cochrane review keeps those apart, and so should you.

Camouflage

Measured. Camouflage moves teeth relative to the bone to mask a mild jaw discrepancy, so it repositions teeth rather than jaws. Saying it “does nothing” confuses a dental correction with a skeletal one. Definition.

Premolar extraction

Contested. Extraction was associated with 1.96 mm of lower-lip and 1.26 mm of upper-lip retraction, and rated pleasantness went up rather than down. The evidence is very low quality and individual responses were unpredictable, but a review of non-growing patients found no sign of the “dished in” profile the forums promise. Extraction evidence.

Appliances that claim to move bone

MSE and MARPE

Measured. MSE is one MARPE device: miniscrew-assisted expansion aimed at a skeletal response in older patients. Success was reported at 92.5%, but the split matters — 2.33 mm of bone against 6.55 mm across the dental arch, on very low-quality evidence. When someone claims “six millimetres,” the MARPE review is the reason to ask which six.

Airway change after MARPE

Measured. In non-growing patients, a meta-analysis found 2.05 mm more nasal-cavity width, 1.67 cm³ more upper-airway volume, no change in the lower airway, and 1.54 mm more alar-base width. Those gains are real but small and location-specific, not a transformed face. Airway review.

Mewing and orthotropics

No evidence found. No randomized trial shows that orthotropics changes adult facial bone. A regulator's determination recorded testimony that the premise lacked evidence, alongside claims about tongue space and treatment before age 8. Read the determination rather than the before-and-after thread.

The midpalatal suture

Measured. Expansion gets harder with age as the suture and surrounding bone interdigitate. In 20 palates from men over 70, every anterior third was ossified. A posterior portion can stay unossified, which is not the same as never closing, and this study is why “anyone can expand” is wrong.

The surgical vocabulary

SARPE and SARME

Measured. Surgically assisted palatal expansion releases the midpalatal suture with a cut, which is a different order of intervention from an archwire. Of 851 patients, 187 had complications, or 21.97%: epistaxis in 2.47%, pain in 2.00%, and asymmetric or inadequate expansion in 4.47%, most of them minor. Source.

BSSO

Measured. Bilateral sagittal split osteotomy is the standard mandibular orthognathic operation. Persistent lower-lip and chin sensory disturbance ran at 21% one year after surgery, while tongue-sensation injury was 0.1% in a separate review. Those are different nerves with different risks, so the surgical evidence beats a generic warning about “nerve damage.”

Le Fort I

Measured. Le Fort I frees the maxilla so it can be repositioned in all three planes, unlike tipping incisors or widening an arch. The term names that capacity, not the aesthetic direction a surgeon will choose. See the surgical review.

MMA and genioplasty

Measured. Maxillomandibular advancement moves both jaws forward. The apnoea-hypopnoea index fell by 41.87 events per hour, but 32.73% of patients with early lower-face numbness still had it beyond one year. Genioplasty is a different operation, repositioning the chin alone or alongside jaw surgery, and a 2025 review of 105 articles and 5,218 patients found no standardized evaluation. Our jaw-surgery context separates chin position from mandibular length.

Terms that circulate without a source

Repetition is not evidence. We searched GDC and hearing records for John Mew's 2017 erasure and could not retrieve the determination, so we do not state it as fact. Mike Mew's documented 2024 erasure is a primary record; the older claim is not.

The line that “the adult midpalatal suture never fuses” traces to 20 older male palates and two CBCT cases, and the first found every anterior third ossified. No population study supports it.

We found no source for a universal expansion-airway percentage either. The reviews report 2.05 mm and 1.67 cm³ of change with the lower airway unchanged, which is not a generic “30% bigger airway.”

Europe PMC searches for “intraoral mandibular distraction osteogenesis” returned ten records on ankylosis, asymmetry, and micrognathia, not outcomes of a branded forum protocol. The technique is real; the package sold around it is undocumented.

How to cite this page

Suggested citation: Real World Appeal, “Orthodontics glossary for men: Class II, overjet, MSE, and what each one can move,” updated September 16, 2026. Quote the study beside any millimetre claim. This page is a reading aid, not a clinical instrument.

The bottom line

Every one of these words has a number attached, and the number is smaller than the forum thinks. Overjet reduction is not jaw-length gain, dental width is not skeletal width, a classification is not facial destiny, and an operation's capacity is not your result.

If you want a first-impression read across face, body, and presentation, the Real World Appeal test is free. It is a structured perception read, not a clinical instrument and not an orthodontic examination.

Sources

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• Alhammadi MS et al. “Global distribution of malocclusion traits.” Dental Press Journal of Orthodontics (2018). Linked source
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• N'Guyen T, Ayral X, Vacher C. Surgical and Radiologic Anatomy 30(1):65–68 (2008). Linked source
• General Dental Council. “Public Full Determination, Mew, Michael Gordon, case CAS-192947” (2024). Linked source
• Walker A et al. Otolaryngology-Head and Neck Surgery 172(4):1142–1154 (2025). Linked source
• Kostares E et al. Oral and Maxillofacial Surgery 28(3):1055–1062 (2024). Linked source
• Alves LC et al. Medicina Oral Patologia Oral y Cirugia Bucal 30(6):e830–e838 (2025). Linked source
• Dalmeijer SWR et al. Craniomaxillofacial Trauma & Reconstruction 18(1):5 (2025). Linked source
• Alhammadi MS et al. Clinical Oral Investigations 26(11):6443–6455 (2022). Linked source