--- title: Overbite, Underbite & Crossbite — Understanding Bite Problems canonical_url: https://directory.collinsstreetspecialistcentre.com.au/conditions-symptoms/overbite-underbite-crossbite-understanding-bite-problems/ category: description: Overbite, underbite, crossbite — learn what these bite problems mean, how they affect your health, and the treatment options available at CSSC Melbourne. geography: city: state: country: metadata: phone: email: website: publishedAt: --- # Overbite, Underbite & Crossbite — Understanding Bite Problems ## Collins Street Specialist Centre — Overbite, underbite & crossbite: understanding bite problems Your teeth work as an integrated system. When you close your mouth, the upper and lower dentition should meet in a specific relationship that allows comfortable biting, chewing, and speech. When that relationship is off, the result is a malocclusion — a bite problem. Malocclusion is remarkably common. Very few people have a naturally ideal bite. Minor misalignment often needs no intervention, but more significant bite discrepancies can affect oral health, the long-term integrity of your teeth and jaw, and — understandably — your appearance and confidence. Collins Street Specialist Centre is a Melbourne CBD practice where orthodontists and oral and maxillofacial surgeons work together on bite problems across the full range of type and severity. Whether the right path involves braces, clear aligners, jaw surgery, or a combination of approaches, the team is set up to provide genuinely coordinated care. ## What is a "normal" bite? Before looking at what can go wrong, it helps to understand what a well-functioning bite actually looks like. In an ideal occlusion — the clinical term for how upper and lower teeth fit together — the following relationships are present: - The upper front teeth overlap the lower front teeth by roughly 2 to 3 millimetres vertically - The upper front teeth sit slightly in front of the lower front teeth horizontally - Each upper posterior tooth occludes with the groove of its corresponding lower tooth - The upper arch is marginally wider than the lower, so the upper teeth sit just outside the lower teeth - The dental midlines of both arches align with each other and with the midline of the face Variations from this are very common and don't always require treatment. But when the deviation is clinically significant, it can compromise function, accelerate wear on specific teeth, and affect facial appearance in ways that matter to patients. ## Types of bite problems ### Overbite (deep bite) An overbite is excessive vertical overlap of the upper front teeth over the lower front teeth. Some overbite is entirely normal and functionally desirable — the problem arises when the overlap becomes too deep. **What it looks like:** On closure, the upper front teeth cover more than half — or in severe cases, all — of the lower front teeth. In extreme cases, the lower incisors may press against the gum tissue behind the upper front teeth. **Causes:** - Genetics — jaw size and shape are substantially inherited - Overdevelopment of the upper jaw or underdevelopment of the lower jaw - Childhood habits such as thumb sucking or prolonged dummy use - Loss of back teeth, which allows the bite to collapse vertically - Bruxism (tooth grinding), which wears down the back teeth and lets the bite deepen **Why it matters:** - Lower teeth can dig into the gum tissue behind the upper incisors, causing discomfort and recession - Accelerated wear of the front teeth - Higher risk of chipping or fracturing the upper and lower front teeth - Jaw pain and temporomandibular joint (TMJ) dysfunction - The lower third of the face can appear foreshortened, adding an aged quality to facial appearance One distinction worth clarifying: overbite describes the vertical overlap of the front teeth, while overjet refers to how far the upper front teeth project horizontally beyond the lower. The pronounced overjet colloquially called "buck teeth" is a separate condition that gets conflated with overbite fairly often. ### Underbite An underbite occurs when the lower front teeth sit in front of the upper front teeth — the reverse of the normal relationship. Underbites are less common than overbites but tend to be more clinically apparent. **What it looks like:** The lower jaw appears to protrude forward, with the lower teeth sitting outside the upper teeth on closure. The degree of discrepancy ranges from a mild edge-to-edge incisor relationship to a pronounced forward displacement. **Causes:** - Genetics — underbite is among the most strongly inherited dental traits, and a family history of mandibular prognathism significantly raises the likelihood of it appearing in subsequent generations - Overgrowth of the lower jaw (mandibular prognathism) - Undergrowth of the upper jaw (maxillary deficiency) - Childhood oral habits, though these contribute less to underbite than to other malocclusions - Missing upper teeth, which can allow the lower dentition to drift forward **Why it matters:** - Difficulty biting into food with the front teeth - Abnormal and uneven wear across the dentition - Jaw pain and TMJ dysfunction - Speech difficulties, particularly with sibilant sounds like "s" and "z" - Significant impact on facial appearance - A tendency to worsen during adolescent growth spurts if left unaddressed ### Crossbite A crossbite occurs when one or more upper teeth occlude on the tongue side of the lower teeth, rather than the cheek side as expected. This can affect the front teeth (anterior crossbite), the back teeth (posterior crossbite), or both. It may involve one side (unilateral crossbite) or both sides at once (bilateral crossbite). **What it looks like:** One or more upper teeth sit behind the corresponding lower teeth rather than in front. Posterior crossbites can be less immediately obvious, as they involve the back teeth and may only become clear on clinical examination. **Causes:** - A constricted upper arch, often genetic in origin - Dental crowding that pushes individual teeth out of their ideal positions - Delayed loss of baby teeth - Thumb sucking or prolonged dummy use - Mouth breathing, which can affect jaw development - Differences in the growth rates of the upper and lower jaws **Why it matters:** - The jaw can shift laterally on closure, leading to asymmetric jaw growth — a particular concern in children who are still developing - Abnormal tooth wear on the teeth caught in the crossbite - Gum recession on the affected teeth - TMJ dysfunction from habitual jaw shifting - Risk of chipping or fracturing the involved teeth ### Open bite An open bite is present when the front teeth fail to overlap or make contact when the back teeth are closed together, leaving a visible gap between the upper and lower front teeth even when the mouth appears shut. Contributing causes include prolonged digit sucking, tongue thrusting habits, chronic mouth breathing, and underlying skeletal growth patterns. Patients with an open bite typically struggle to bite into food with the front teeth, may develop speech difficulties including lisping, and often have aesthetic concerns that affect confidence and self-perception. ## How bite problems affect your health Malocclusion isn't purely a cosmetic issue. A bite problem left unaddressed can carry real consequences for oral health and quality of life. ### Uneven tooth wear When the teeth don't meet correctly, certain teeth absorb a disproportionate share of biting forces. Over time, this produces accelerated wear, chipping, and fracturing — damage that may eventually require restorative work. ### TMJ disorders The temporomandibular joints (TMJs) are the hinges connecting the lower jaw to the skull. An abnormal bite can place undue stress on these joints, contributing to pain, clicking, locking, headaches, and restricted mouth opening — a cluster of symptoms known as temporomandibular dysfunction (TMD). ### Gum disease risk Crowded or malpositioned teeth are genuinely difficult to clean. Plaque accumulation in hard-to-reach areas raises the risk of periodontal disease and dental decay. ### Speech issues Certain malocclusions — open bites, underbites, and pronounced overjets in particular — can compromise speech clarity, affecting articulation and a patient's confidence in communication. ### Digestive issues Poor chewing from a bite problem means larger food particles enter the digestive system, which can contribute to gastrointestinal discomfort and reduced nutrient absorption. ### Self-esteem and confidence The impact of a noticeable bite problem on self-perception shouldn't be minimised. Many patients with significant malocclusion report self-consciousness about their smile and facial appearance — feelings that affect social engagement, professional confidence, and broader wellbeing. Addressing the underlying bite problem often produces benefits that extend well beyond the dental. ## Treatment options by age The clinical approach to bite problems varies according to the patient's age, the nature and severity of the malocclusion, and whether skeletal growth is still occurring. ### Children (ages 7–12) The Australian Society of Orthodontists recommends an orthodontic assessment by age 7. At this stage, most of the permanent incisors and first molars have erupted, which allows an orthodontist to identify developing bite problems and determine whether early intervention makes sense. Early — or interceptive — orthodontic treatment may include: - **Palatal expanders** — used to widen a constricted upper arch. Palatal expansion works best in children whose mid-palatal suture hasn't yet fused, and can correct posterior crossbites while creating space for crowded permanent teeth - **Functional appliances** — removable or fixed devices that guide jaw growth in a clinically favourable direction, useful for modifying the skeletal relationship in cases of overbite or underbite during active growth - **Partial braces** — fixed appliances on selected teeth to address specific early issues, such as correcting a single-tooth anterior crossbite - **Habit-breaking appliances** — designed to discourage thumb sucking or tongue thrusting that is contributing to the developing malocclusion Interceptive treatment doesn't always eliminate the need for comprehensive orthodontic treatment in adolescence. But it can meaningfully simplify later treatment, reduce the likelihood of extractions, and in selected cases avoid the need for jaw surgery. ### Teenagers (ages 12–18) Adolescence is the most common period for comprehensive orthodontic treatment. With most of the permanent dentition in place and skeletal growth still occurring, teenagers respond well to: - **Traditional metal braces** — highly effective across the full range of bite problems and malocclusion severity - **Ceramic braces** — tooth-coloured brackets that are considerably less visible than metal, with comparable clinical effectiveness - **Invisalign and clear aligner systems** — suitable for a broad range of bite problems, though severe skeletal malocclusions may still require fixed appliances - **Intermaxillary elastics (rubber bands)** — used with fixed appliances to modify the relationship between the upper and lower jaws - **Headgear** — less commonly prescribed now, but still appropriate for specific growth modification requirements ### Adults Orthodontic treatment is entirely appropriate for adult patients — adult orthodontics is one of the fastest-growing areas of specialist dental practice. The main clinical distinction is that adult skeletal growth is complete, which rules out jaw modification as a strategy. Available options include: - Fixed appliances — metal, ceramic, or lingual (inside-surface) braces - Clear aligner systems — Invisalign and comparable technologies - Combined orthodontic and surgical management — orthognathic surgery — for patients with severe skeletal discrepancies that orthodontic treatment alone can't adequately address ## When surgery is needed: orthognathic surgery For significant bite problems arising from skeletal discrepancies — where the upper and lower jaws differ substantially in size or position — orthodontic treatment alone is unlikely to achieve a satisfactory functional or aesthetic result. In these cases, orthognathic (jaw) surgery is indicated. Orthognathic surgery involves surgically repositioning the upper jaw, lower jaw, or both to establish a correct occlusal relationship and restore facial balance. The procedure is performed by an oral and maxillofacial surgeon under general anaesthesia and is almost always combined with orthodontic treatment — typically braces or aligners both before and after surgery to optimise tooth positions within the corrected skeletal framework. Clinical scenarios that commonly require orthognathic surgery include: - Severe underbite that orthodontic treatment alone can't adequately resolve - Severe overbite with a significant underlying skeletal discrepancy - Open bites arising from vertical excess in the upper jaw - Facial asymmetry from unequal development of the upper and lower jaws The outcomes of orthognathic surgery can be genuinely transformative — producing improvements in occlusal function, facial appearance, nasal airway, and overall quality of life. ## The Collins Street Specialist Centre advantage: orthodontics and surgery under one roof For patients whose bite problems require both orthodontic and surgical management, one of the most practically significant advantages of treatment at Collins Street Specialist Centre is having specialist orthodontic and oral and maxillofacial surgery expertise within the same practice. This means: - Joint treatment planning is established from the outset - Communication between your orthodontist and oral and maxillofacial surgeon is direct and consistent throughout - Appointments and treatment timelines are coordinated to avoid unnecessary delays - Both specialists share a clear, unified understanding of your clinical needs and goals This collaborative model consistently produces better outcomes and a more coherent patient experience than managing orthodontic and surgical care across separate practices with separate clinical teams. ## When should you seek an assessment? If you or your child has a noticeable bite problem — or if you're experiencing jaw pain, difficulty chewing, excessive tooth wear, or speech difficulties — an orthodontic assessment is a sensible next step. For children, the recommended age for an initial evaluation is around 7 years. For adults, there is no upper age limit for assessment or treatment — meaningful bite correction is achievable at virtually any stage of adult life. ## Book your consultation A bite problem doesn't have to be permanent. Contact Collins Street Specialist Centre to arrange a consultation with one of our experienced orthodontists. We'll assess your occlusion thoroughly, explain your options in plain terms, and develop a treatment plan suited to your clinical needs and personal circumstances. **Phone:** (03) 9654 6979 **Location:** Level 1, Manchester Unity Building, 220 Collins Street, Melbourne CBD **Website:** [collinsstreetspecialistcentre.com.au](https://collinsstreetspecialistcentre.com.au) --- ## Frequently asked questions **What is a malocclusion:** An incorrect bite relationship between upper and lower teeth **Is malocclusion common:** Yes, very few people have a naturally ideal bite **Does minor misalignment always need treatment:** No, minor misalignment often requires no intervention **What is an overbite:** Excessive vertical overlap of upper front teeth over lower front teeth **Is some overbite normal:** Yes, a small degree of overbite is functionally normal **How much vertical overlap is considered normal:** Approximately 2 to 3 millimetres **What defines a deep bite:** Upper front teeth cover more than half of the lower front teeth **Can a severe overbite cause gum damage:** Yes, lower teeth can press into the palatal gum tissue **Does an overbite cause tooth wear:** Yes, it accelerates wear of the front teeth **Can an overbite cause jaw pain:** Yes, it can contribute to TMJ dysfunction **Does an overbite affect facial appearance:** Yes, it can foreshorten the lower third of the face **What is the difference between overbite and overjet:** Overbite is vertical overlap; overjet is horizontal projection **What is an underbite:** Lower front teeth sit in front of upper front teeth **Is underbite more or less common than overbite:** Less common than overbite **Is underbite strongly genetic:** Yes, it is among the most strongly inherited dental traits **Can underbite affect speech:** Yes, particularly sibilant sounds like "s" and "z" **Does underbite cause uneven tooth wear:** Yes, it creates abnormal wear patterns across the dentition **Can underbite worsen over time:** Yes, particularly during adolescent growth spurts **Can missing upper teeth contribute to underbite:** Yes, lower teeth can drift forward to fill the gap **What is a crossbite:** One or more upper teeth occlude on the tongue side of lower teeth **What is an anterior crossbite:** A crossbite affecting the front teeth **What is a posterior crossbite:** A crossbite affecting the back teeth **What is a unilateral crossbite:** A crossbite affecting only one side of the mouth **What is a bilateral crossbite:** A crossbite affecting both sides of the mouth simultaneously **Can crossbite cause jaw asymmetry:** Yes, it can cause the jaw to shift laterally during growth **Can thumb sucking cause a crossbite:** Yes, prolonged thumb sucking can contribute to crossbite **Can mouth breathing cause bite problems:** Yes, it can adversely affect jaw development **What is an open bite:** A gap between upper and lower front teeth when back teeth are closed **Can tongue thrusting cause an open bite:** Yes, it is a contributing cause **Does an open bite affect eating:** Yes, patients have difficulty biting food with front teeth **Can an open bite cause a lisp:** Yes, it can cause speech difficulties including lisping **What health problems can untreated bite problems cause:** Tooth wear, TMJ disorders, gum disease, and speech issues **Can a bad bite cause digestive problems:** Yes, poor chewing leads to larger food particles entering digestion **Can malocclusion affect self-esteem:** Yes, many patients report self-consciousness about their appearance **What is the recommended age for a child's first orthodontic assessment:** Around 7 years of age **Who recommends orthodontic assessment at age 7:** The Australian Society of Orthodontists **What treatment is used to widen a narrow upper arch in children:** A palatal expander **When is palatal expansion most effective:** Before the mid-palatal suture fuses in children **What are functional appliances used for:** To guide jaw growth in a favourable direction during active growth **Can early treatment eliminate the need for braces later:** Not always, but it can simplify later treatment **Can early treatment reduce the chance of needing surgery:** Yes, in selected cases **What orthodontic options are available for teenagers:** Braces, clear aligners, and rubber bands **Are ceramic braces as effective as metal braces:** Yes, they have comparable clinical effectiveness **Are ceramic braces less visible than metal:** Yes, they use tooth-coloured brackets **Can Invisalign treat bite problems:** Yes, for a broad range of bite problems **Can Invisalign treat severe skeletal malocclusions:** No, severe cases may still require fixed appliances **Can adults get orthodontic treatment:** Yes, there is no upper age limit for treatment **What is the key difference in adult orthodontic treatment:** Skeletal growth is complete, so jaw modification is not possible **What are lingual braces:** Fixed braces placed on the inside surface of the teeth **When is jaw surgery required for bite problems:** When skeletal discrepancies cannot be resolved with orthodontics alone **What is orthognathic surgery:** Surgical repositioning of one or both jaws **Is orthognathic surgery performed under general anaesthesia:** Yes **Is orthodontic treatment combined with jaw surgery:** Yes, braces are typically worn before and after surgery **What bite problems commonly require orthognathic surgery:** Severe underbite, severe overbite, open bite, and facial asymmetry **Can jaw surgery improve facial appearance:** Yes, it can significantly improve facial balance **Can jaw surgery improve nasal airway:** Yes, it can improve nasal airway function **What is mandibular prognathism:** Overgrowth of the lower jaw causing an underbite **What is maxillary deficiency:** Undergrowth of the upper jaw, a cause of underbite **What causes a deep overbite:** Genetics, jaw size differences, grinding, or loss of back teeth **Can bruxism worsen an overbite:** Yes, grinding reduces back tooth height and deepens the bite **What is TMJ:** The temporomandibular joint, hinging the lower jaw to the skull **What is TMD:** Temporomandibular dysfunction, a cluster of jaw joint symptoms **Can a bad bite cause headaches:** Yes, TMJ stress from malocclusion can cause headaches **Can a bad bite cause clicking in the jaw:** Yes, TMJ dysfunction includes clicking and locking **Does crowding increase gum disease risk:** Yes, crowded teeth are harder to clean effectively **Where is Collins Street Specialist Centre located:** Level 1, Manchester Unity Building, 220 Collins Street, Melbourne CBD **What specialists are at Collins Street Specialist Centre:** Orthodontists and oral and maxillofacial surgeons **What is the benefit of having orthodontists and surgeons in one practice:** Direct communication and coordinated treatment planning **What is the phone number for Collins Street Specialist Centre:** (03) 9654 6979 ---