You’ve noticed something looks off about your bite or your smile — but when you search online, you keep seeing two different words: overjet and overbite. Which one do you actually have? And does it even matter? The answer is yes — and it changes your entire treatment path. This guide will show you exactly how to tell the difference, what each condition means for your long-term health, and how the Australian Centre for AI Orthodontics and Orthopaedics (ACAOO) corrects both.
Overjet vs Overbite: The Key Differences at a Glance
These two terms describe two distinct bite problems.
Here is a precise clinical comparison:
| OVERBITE | OVERJET | |
| Direction | Vertical — upper teeth overlap too deeply downward | Horizontal — upper teeth protrude too far forward |
| Common name | Deep bite | Buck teeth |
| What you see | Lower teeth hidden behind upper teeth | Upper teeth visibly stick out forward |
| Primary cause | Bite depth, tooth positioning | Jaw alignment, lower jaw sitting too far back |
| Jaw involvement | Mainly dental — less jaw-related | Often skeletal — lower jaw retrusion |
| Key risks | Enamel wear, gum issues, TMJ discomfort | Tooth fracture risk, long-term misalignment |
| Surgery needed? | Rare — only severe skeletal cases | Rare — only extreme skeletal cases |
| ACAOO solution | Smartee S8-SGTB corrects deep bite | Smartee S8-SGTB repositions jaw + aligns teeth |
The Mirror Test: Which One Do You Have?
Before we go deeper, here is a simple self-check you can do right now. It won’t replace a clinical assessment, but it will give you a strong indication of which condition — or combination — you are dealing with.
| THE MIRROR TEST — WHICH ONE DO YOU HAVE? Stand in front of a mirror and bite down naturally, with your teeth together as you normally would. Look from the front: Can you see your lower front teeth at all? If your upper teeth cover more than one-third of your lower teeth vertically — that points to an overbite. Look from the side: Do your upper front teeth sit noticeably further forward than your lower teeth — a visible horizontal gap? That points to an overjet. Both look true? You likely have Class II malocclusion — overjet and overbite occurring together. This is very common, and the Smartee S8-SGTB is designed to correct both simultaneously. |
| IMPORTANT NOTE The mirror test gives a useful indication — but it cannot replace a 3D clinical assessment. Many patients discover they have a more complex bite picture than the mirror shows. At the Australian Centre for AI Orthodontics and Orthopaedics (ACAOO), Dr. Gareth Ho uses AI-powered 3D imaging to give you a precise, definitive diagnosis at your first visit. |
What Is an Overbite? (The Vertical Problem)
An overbite is the excessive vertical overlap of your upper front teeth over your lower front teeth. A healthy overbite sits at 1–3mm — this is completely normal. It’s only when that vertical overlap exceeds 3–4mm that it becomes a clinical concern, often referred to as a deep bite.
Left untreated, a deep overbite creates a progressive set of problems:
- Accelerated tooth wear and enamel erosion — upper and lower teeth grind against each other incorrectly
- Jaw strain and TMJ (temporomandibular joint) discomfort — the bite places asymmetric stress on the jaw joints
- Headaches and facial muscle tension — from the jaw working harder to compensate
- Chewing difficulties — food isn’t broken down efficiently
- In severe cases, the lower front teeth press into the roof of the mouth (palate), causing soft tissue damage
Overbite is primarily a dental and bite-mechanics issue. The teeth and how they meet is the main driver — though jaw structure can play a role in severe cases.
What Is an Overjet? (The Horizontal Problem)
An overjet is the horizontal distance your upper front teeth protrude beyond your lower front teeth. In a healthy bite, there is a slight overjet of 1–2mm — this is normal. When the horizontal gap exceeds 2mm, the upper teeth begin to visibly protrude, creating what is colloquially called “buck teeth.”
Overjet carries a distinct and often underestimated set of risks:
- Higher fracture and injury risk — exposed upper front teeth are significantly more vulnerable to chipping and trauma from everyday accidents
- Lip closure difficulty — patients with significant overjet often cannot close their lips comfortably at rest
- Speech difficulties — certain sounds (‘s’, ‘f’, ‘v’) become harder to produce clearly
- Facial profile imbalance — overjet affects the side profile, with the upper lip appearing pushed forward and the chin receding
- Long-term jaw misalignment — the lower jaw is often positioned too far back (retrognathia), which worsens with age if untreated
Unlike overbite, overjet is frequently skeletal in origin — meaning the lower jaw sits too far back relative to the upper jaw. This is the defining feature of Class II malocclusion, and it requires a treatment approach that addresses the jaw position, not just the teeth.
| WHY THIS DISTINCTION MATTERS FOR TREATMENT Standard clear aligners move teeth. They do not reposition jaws. If your overjet is driven by a lower jaw that sits too far back — which most moderate-to-severe cases are — standard aligners will improve the appearance of your teeth but will not correct the underlying skeletal cause. The Smartee S8-SGTB is specifically engineered to address both: teeth alignment and jaw repositioning, simultaneously. |
What Causes Overjet and Overbite?
Both conditions share some common causes, but their primary drivers differ — and understanding this shapes which treatment will achieve the most complete and stable result.
Common causes of both
- jaw size, tooth size, and their proportional relationship are largely inherited — Genetics
- prolonged thumb-sucking, pacifier use, and tongue thrusting during key developmental years — Childhood habits
- places uneven forces on teeth over time, altering how they meet — Bruxism (teeth grinding)
- when upper and lower jaws don’t develop proportionally — Jaw growth discrepancies
Overjet-specific drivers
- the lower jaw is underdeveloped or positioned too far back — this is the most common skeletal cause of overjet — Mandibular retrusion
- when lower front teeth are absent, upper teeth have nothing to rest against and drift forward — Missing lower teeth
Overbite-specific drivers
- the upper teeth erupt too far, creating excessive vertical overlap — Deep bite mechanics
- excessive curvature of the lower arch pushes the bite deeper — A deep Curve of Spee
- when teeth are crowded, the bite can collapse vertically — Crowding
Many patients have both conditions simultaneously — a combined deep overbite and overjet — which falls under the clinical umbrella of Class II malocclusion. This is one of the most common complex bite presentations seen at ACAOO, and it is precisely what the Smartee S8-SGTB is designed to treat.
ACAOO’s Approach: Correcting Overjet and Overbite Together
At ACAOO, we treat the full bite picture — not just what’s visible on the surface. For patients with overjet, overbite, or both, the Smartee S8 Digital Twin Block (S8-SGTB) is our primary clinical tool for non-surgical correction.
What the Smartee S8-SGTB does that standard aligners cannot
Standard clear aligners are effective at moving teeth into better positions. They are not designed to reposition the lower jaw. For patients with Class II malocclusion — where the jaw is the primary cause of the bite problem — treating the teeth alone produces an incomplete result.
The Smartee S8-SGTB uses mandibular repositioning technology to simultaneously:
- Guide the lower jaw forward into its correct position
- Correct the horizontal protrusion (overjet)
- Reduce the deep vertical overlap (overbite)
- Level the Curve of Spee
- Align the teeth within the corrected jaw framework
The result is a complete bite correction — functional, stable, and aesthetic — achieved without surgery and without the bulk of traditional functional appliances like Twin Blocks or headgear.
The Treatment Journey at ACAOO
- AI-Powered 3D Assessment — Advanced intraoral scanning and AI diagnostics map your bite, jaw position, and facial profile in precise detail — identifying the exact nature and severity of your overjet, overbite, or both.
- Personalised Treatment Plan — Dr. Gareth Ho designs a fully customised plan using the Smartee S8-SGTB, mapped to your specific bite anatomy. Whether you have overjet, overbite, or Class II malocclusion, the plan addresses the full picture.
- Staged Jaw and Teeth Correction — The S8-SGTB works in calibrated progressive stages — simultaneously advancing the lower jaw and aligning the teeth. Both corrections proceed in parallel throughout treatment.
- Retention — Custom retainers are fitted once correction is complete, holding the new jaw and tooth positions and preventing any relapse.
- Remote Monitoring via DentalMonitoring AI — Between clinic visits, our team tracks your progress remotely using AI monitoring technology. Fewer appointments without compromising specialist oversight.
Why Choose ACAOO for Bite Correction in Sydney?
The Australian Centre for AI Orthodontics and Orthopaedics (ACAOO) is a specialist orthodontic centre, not a general dental practice. For bite conditions like overjet and overbite — where jaw structure is frequently involved — that specialist distinction matters.
Dr. Gareth Ho has been treating complex Class II bite cases in Sydney for over 20 years. Every patient receives a 3D AI-assisted assessment, a fully personalised treatment plan, and specialist-led oversight throughout their correction. For patients who prefer complete invisibility during treatment, lingual braces — fitted on the inner surfaces of the teeth — are also available as an alternative or adjunct to clear aligner therapy.
| ACAOO · SYDNEY CBD · WORLD SQUARE Not sure whether you have an overjet, an overbite — or both? Book a consultation with Dr. Gareth Ho at our Sydney CBD clinic. Using 3D AI imaging, we will give you a precise diagnosis and a clear, honest treatment plan — specific to your bite. BOOK YOUR CONSULTATION → |
Frequently Asked Questions
What is worse — overjet or overbite?
Neither is inherently worse than the other. They carry different risks: overjet poses a higher risk of tooth fracture and injury (exposed front teeth are more vulnerable), while overbite poses a higher long-term structural risk (enamel wear, gum damage, TMJ strain). Both warrant proper assessment and treatment — and both worsen without intervention.
How do I know if I have an overbite or overjet?
Use the mirror test described in this article as a starting point — front view for overbite (vertical), side view for overjet (horizontal). However, the definitive answer requires a 3D clinical assessment. At ACAOO, Dr. Gareth Ho uses AI-powered imaging to give you a precise diagnosis at your first consultation.
Can you have both overjet and overbite at the same time?
Yes — this is actually very common. When both conditions occur together, it is known as Class II malocclusion. The lower jaw typically sits too far back, creating simultaneous horizontal protrusion (overjet) and deep vertical overlap (overbite). The Smartee S8-SGTB is specifically designed to correct both conditions simultaneously.
Can overjet and overbite fix themselves over time?
No. Neither condition self-corrects. In most cases, both worsen progressively with age as the jaw, teeth, and soft tissues continue to develop and shift. Early treatment produces simpler corrections and more stable long-term results.
Is surgery required to fix overjet or overbite?
Not in the majority of cases. Surgery (orthognathic surgery) is reserved for the most extreme skeletal discrepancies — where the jaw misalignment is too large for orthodontic appliances to correct alone. Most cases, including many that appear severe, can be corrected non-surgically with the Smartee S8-SGTB at ACAOO.
How long does treatment take?
Treatment time varies by severity and whether the issue is dental, skeletal, or both. Mild cases can show meaningful improvement in 6–12 months. Class II malocclusion cases involving both overjet and overbite — treated with the Smartee S8-SGTB — typically take 12–24 months. Dr. Ho will provide a specific timeline after your initial 3D assessment.
