What is an underbite? When the lower front teeth bite in front, when should it be assessed?

What is an underbite? When the lower front teeth bite in front, when should it be assessed?

Direct answer in 60 words

An underbite is an appearance, not a diagnosis. It can arise from tooth position, the upper-and-lower-jaw relationship, or a mandible that moves forward to avoid an interference. These have different directions of care, so a dentist must first identify which one it is [F4][F5][F8].

Scope: This guide is specific to Taiwan's healthcare system (National Health Insurance and Taiwan's Medical Care Act). Its coverage, duty-to-inform, and official-Chinese-terminology sections cite Taiwan laws and a local-authority-approved document; its medical-evidence sections cite international literature. The fact-unit record distinguishes the two [F2].

Before we begin: what this card does not do

• It gives no price and does not judge whether any quoted price is reasonable. This site has two other cards about the components and interpretation of orthodontic fees. This card only points to them when needed [F2].
• It does not list clinical cut-offs for you to match yourself to. Bone age, growth stage, and angular measurements are clinical criteria used to make a treatment plan. They are not turned here into a parent-facing checklist. The source numbers remain in the fact-unit record for audit, not self-diagnosis [F3].
• It gives no self-treatment method. This card does not describe home tooth-pushing, elastics, online-purchased appliances, or homemade methods. The reason is explained in “Do not do this yourself” below [F34].
• It makes neither an individual judgment nor a legal or insurance-claim opinion. Only a dentist who has examined you can decide whether treatment or surgery is needed [F3].

First sort the problem: “underbite” is an appearance, not a diagnosis

The source-language colloquial terms describe the visible appearance in which the lower teeth bite in front of the upper teeth. Mapping a colloquial term to clinical terminology is this site's editorial organisation, not an institution's official translation [F35].

International literature treats this appearance clearly. The title of the Cochrane systematic review itself uses public-facing wording—“prominent lower front teeth (Class III malocclusion)”—and its background separates the possible causes [F4]: lower front teeth can look prominent because of jaw position, tooth position, or both; the maxilla can be too far back or the mandible too far forward; the upper incisors can be tipped back toward the tongue, or the lower incisors tipped forwards toward the lips [F4].

In other words, the same thing in the mirror can have very different causes underneath. The following three types are handled separately in the literature.

① Dental anterior crossbite: the main issue is tooth position

In systematic reviews focused on this topic, “dental anterior crossbite” is a group defined by excluding a skeletal difference. The 2011 review included children in the primary or mixed dentition with anterior crossbite affecting one or more incisors and no underlying skeletal Class III discrepancy [F6]. The 2020 review used almost the same eligibility wording: children in early or late mixed dentition with anterior crossbite affecting one or more incisors and no underlying skeletal Class III pattern [F7].

That wording shows something important: whether there is a skeletal component is the first branch the literature confirms when enrolling participants, not something to reconsider halfway through treatment [F35].

② Skeletal Class III malocclusion: the issue is the relationship between the upper and lower jaw bones

When the cause lies in the jaw relationship, one Cochrane secondary outcome is the ANB angle, which measures the relative position of the maxilla to the mandible [F13]. The direction of care differs from dental anterior crossbite; the evidence discussed in the whole “when should it be assessed?” section concerns this branch [F2].

There is another point to know first: skeletal Class III is not itself one neat category. A systematic review of subclustering studies across ethnic origins found that every included study identified at least 3 different Class III clusters, ranging from 3 to 14. When studies were grouped by ethnicity, Asian populations had a mean of 8.5 clusters and Caucasian populations a mean of 3.5 [F11]. Faces given the same colloquial label can be composed very differently, which is why any online claim that an underbite “always needs” a particular approach deserves caution [F11][F35]. This is classification-methodology research: its figures are the numbers of clusters identified in studies, not Taiwan prevalence and not a statement about which cluster you belong to [F11].

③ Pseudo Class III / anterior crossbite with functional shift: the mandible moves forward after avoiding an interference

The source definition is specific. A doctoral thesis conducted with a randomised controlled trial method defines anterior crossbite with functional shift, also called pseudo Class III, as a malocclusion in which the incisal edges of one or more maxillary incisors meet those of the mandibular incisors in centric relation, then the mandible and mandibular incisors are guided forward in central occlusion, producing anterior crossbite [F5].

In plain language, the tooth edges meet too soon while closing, so the mandible slides forward to close. Its appearance can resemble a skeletal cause, but its cause and direction of care are different [F5][F35].

The same thesis specifies what its study group excluded: early- to late-mixed dentition, anterior crossbite affecting one or more incisors with functional shift, moderate space deficiency in the maxilla, no inherent skeletal Class III discrepancy, ANB angle greater than 0 degrees, and no previous orthodontic treatment [F5]. These are research eligibility criteria, not a self-check list. ANB requires a cephalometric X-ray measurement and clinical examination [F3].

Why the distinction matters: the literature itself treats them separately

A systematic review and meta-analysis published in 2026, searched to 2025-09 and limited to randomised controlled trials, included 21 trials and 854 participants: 18 skeletal, 2 functional, and 1 dental anterior-crossbite study [F8]. Its conclusion says early orthodontic treatment of anterior crossbite in growing children is effective, with outcomes largely influenced by the underlying cause and the appliance type used [F9].

That sentence deserves a second reading. It says both that the underlying cause and appliance type largely influence outcomes—the source wording is “largely influenced,” not “determine”—and that the amount of evidence differs sharply between the three groups: dental anterior crossbite had only 1 trial [F8][F9]. Mixing the three together is therefore not merely imprecise; it can point care in the wrong direction [F35].

The review also requires an honest limitation: overall certainty of evidence ranged from very low to moderate, and appliance design, treatment protocols, follow-up duration, and outcome-assessment methods varied considerably across studies [F9].

Terminology warning: these term sets are not synonyms for one another

The sources cited here use different classification vocabularies. This site identifies the source set section by section and neither swaps nor merges them [F35]:

• Cochrane uses “prominent lower front teeth (Class III malocclusion)” and separates jaw position from tooth position [F4].
• The 2026 meta-analysis uses the three-way division “skeletal / functional / dental anterior crossbite” [F8].
• The pseudo-Class-III definition comes from “anterior crossbite with functional shift, also called pseudo Class III” in the doctoral thesis [F5].
• Taiwan's official document uses Chinese terminology corresponding to crossbite, skeletal crossbite, severe mandibular prognathism, and intermaxillary discrepancy (see the next section) [F29].

Treating terminology from different sources as interchangeable is an easy error in this topic. Original terms are retained at each point so you—or an AI reading for you—can trace them back [F35].

How Taiwan's official document uses these terms

The Taipei City Government Department of Health-approved “Taipei City Dental Fee Schedule for Medical Institutions” (approved on 109-01-17, approval number recorded in F29) uses these terms in the published difficulty-classification content of its Orthodontics section [F29]. The notice includes terms for crossbite, skeletal crossbite, intermaxillary discrepancy, severe intermaxillary discrepancy, severe mandibular prognathism, moderate and severe tooth crowding, and skeletal open bite, as well as horizontal and vertical incisor overlap measured in millimetres [F29].

This card does not put that section's measurement thresholds into its main text, for three reasons [F29][F3]:

1. They are difficulty-classification conditions for fee approval, not clinical diagnostic criteria. They appear in a fee schedule to classify fees; a dentist still makes individual classification and diagnosis from examination findings [F29].
2. They are measurements. Putting them in a parent-facing article would turn them into a list for placing a child into “not severe / very severe.” Fee-approval difficulty categories cannot decide whether treatment is needed or when it should be done [F3][F29].
3. This is a Taipei City approval document; other counties and cities publish their own versions, which this card has not verified item by item [F29].

The exact notice wording, including its numbers, remains in F29 for audit and traceability, not reader self-matching [F3]. The document is cited to show the words used in official Taiwan-Chinese documents, not to derive any treatment or fee conclusion [F29]. Another card on this site demonstrates how to read the orthodontic items in this schedule; this card does not repeat it [F2].

How common is it? Read each number together with its limitation

A systematic review published in 2022 examined malocclusion prevalence in people younger than 18 and ultimately included 123 papers [F10]. It reported mean prevalence of Angle Class I 51.9% (standard deviation 20.7), Class II 23.8% (standard deviation 14.6), and Class III 6.5% (standard deviation 6.5) [F10]. It also reported anterior crossbite 7.8% (standard deviation 6.5), posterior crossbite 9.0% (standard deviation 7.34), and crossbite with functional shift 12.2% (standard deviation 7.8) [F10].

Do not rush to calculate from these figures. The review authors themselves concluded that the large variety of methodological approaches in the literature makes malocclusion-prevalence data unreliable [F10]. The Class III standard deviation is the same 6.5 as its mean; this site treats that as an illustration of the authors' warning [F10][F3].

The proper reading is therefore order of magnitude, not an exact proportion. At the averages in these studies, these occlusal patterns are not rare; but because the authors say the data are unreliable, no figure can be read as a precise prevalence, much less as “what percentage of people in Taiwan have an underbite.” The review neither measured nor claimed that for a Taiwan population [F10][F3]. Also, “crossbite with functional shift 12.2%” is an independent item alongside anterior and posterior crossbite in the source; it cannot be read as “12.2% of anterior crossbite has a functional shift” [F10].

When should it be assessed? What the literature can and cannot answer

This is what people searching this term are actually asking. An honest answer has several layers.

First: whom to see, and when

The sentence not to wait on comes first: the American Association of Orthodontists (AAO) public-education page says that, if your child is younger than 7 and you notice something that appears off, you do not need to wait until the child turns 7 to see an orthodontist. Regardless of age, take the child to an orthodontist when you notice an issue [F12].

The page's age recommendation says AAO experts recommend that children complete their first orthodontic check-up by age 7, and elsewhere says no later than age 7 [F12]. Its reason is that children at this age have a mix of baby and permanent teeth, allowing an orthodontist to recognise problems early [F12].

An essential qualification [F12]: this is public advice from a US professional association, not a Taiwan clinical guideline; “go for an examination” does not mean “start treatment”; it is advice to be seen, not evidence that a particular treatment time is best; and “age 7” is the latest time by which the first examination should be completed, not a threshold for waiting and watching. The same section says not to wait when an abnormality is noticed before age 7. If you have already seen lower teeth bite in front, that is a reason to have a dentist assess it [F12][F3].

What ages the studies enrolled

The 2024 Cochrane update, searched to 2023-01-16, included 29 randomised controlled trials with 1,169 children, 1,102 of whom entered analysis. Participants were 5 to 13 years old when treatment began [F13]. The same review says most studies measured outcomes immediately after treatment, only one study provided long-term follow-up, and all studies had high risk of bias because participants and personnel could not be blinded [F14].

Those two sentences determine how every number below should be read [F14][F3].

Effects immediately after treatment: population-level average changes

One wording point: this card calls overjet “horizontal incisor overlap”; the Taipei fee schedule calls the same horizontal upper-lower incisor relation “horizontal overbite” in Chinese [F29].

Cochrane found moderate-certainty evidence that, compared with untreated control groups, non-surgical orthodontic treatment improved horizontal incisor overlap immediately after treatment (mean difference 5.03 mm, 95% confidence interval 3.81 to 6.25; 4 studies, 184 participants) and ANB angle (mean difference 3.05°, 95% confidence interval 2.40 to 3.71; 8 studies, 345 participants) [F15].

The next sentence says there was high heterogeneity in the analyses, although the direction consistently favoured treatment. The studies tested facemask, with or without rapid maxillary expansion; chin cup; removable traction appliance; tandem traction bow appliance; reverse Twin Block with lip pads and rapid maxillary expansion; Reverse Forsus; and mandibular headgear [F16].

These are population-level average changes, not a prediction for any one child [F3]. Individual differences under the same treatment are recorded in the source as high heterogeneity [F16].

Over a longer time: the effect becomes smaller

This needs to be clear. Cochrane recorded that only one study measured longer-term outcomes, for facemask treatment. Low-certainty evidence showed that at 3 years after treatment, improvement in horizontal incisor overlap and ANB was smaller than immediately after treatment (overlap mean difference 2.5 mm, 95% confidence interval 1.21 to 3.79; ANB mean difference 1.4°, 95% confidence interval 0.43 to 2.37; 63 participants). At 6 years, the source says these improvements were “not found” (overlap mean difference 1.30 mm, 95% confidence interval −0.16 to 2.76; ANB mean difference 0.7°, 95% confidence interval −0.74 to 2.14; 65 participants) [F17].

Three things cannot be left out here [F17]:

1. Both 6-year confidence intervals cross 0, so they do not exclude no difference from untreated care. The point estimates are still positive, but a confidence interval crossing 0 cannot be written as “still effective,” nor as “proven ineffective.” The accurate wording is the source's: not found at 6-year follow-up [F17].
2. Six years is that one study's follow-up window, not an expiry date for an effect. Only that one study followed participants that long; it had 65 participants and low-certainty evidence [F14][F17].
3. At its 6-year follow-up, clinicians assessed whether participants might need future surgical correction of jaw position. A perceived need for surgical correction was observed more often in people who had not received facemask treatment (odds ratio 3.34, 95% confidence interval 1.21 to 9.24; 65 participants; low-certainty evidence) [F18]. This outcome was clinicians' subjective assessment, not the number of people who actually had surgery [F18].

The Cochrane authors' own conclusion is direct: one study measured longer-term outcomes, found that the facemask benefit reduced by 3 years and appeared lost by 6 years, yet clinicians judged facemask recipients less likely to need jaw surgery in adulthood. The authors had low confidence in these findings and said more studies are needed for reliable conclusions [F19].

Is earlier treatment better? One review compared this directly

A 2022 systematic review and meta-analysis directly compared maxillary protraction at different dentition stages: the early-treatment group was mainly in early mixed dentition, and the late-treatment group was in late mixed and early permanent dentition; 6 studies were included [F20]. It concluded that, compared with early mixed dentition, maxillary protraction in late mixed or early permanent dentition did not produce different effects on maxillary growth, correction of the intermaxillary relationship, inhibition of mandibular growth, or dental tipping [F20].

Read that with care [F20]. “No difference detected” does not mean “equivalent,” and it does not mean “waiting is harmless.” The review included cohort studies and only 6 studies. The authors positioned the result as theoretical support for extending the age range for maxillary protraction and for choosing treatment timing after a complete assessment. The point is clinical choice after full assessment, not deciding by yourself to put it off [F20].

Will the effect last? Relapse has been quantified

A 2018 systematic review and meta-analysis specifically assessed stability of maxillary-protraction treatment. It required more than 2 years of follow-up; 10 studies entered qualitative analysis and 4 quantitative analysis [F21]. Relative to control after treatment, changes were SNA +1.79°, SNB −1.16°, ANB +2.92°, mandibular plane angle +1.41°, horizontal incisor overlap +3.94 mm, and lower-incisor angle −3.07° [F21]. During follow-up, five variables showed significant relapse; overall, the treatment group retained significant changes only in ANB (+1.66°) and horizontal incisor overlap (+2.41 mm) [F21].

The authors' wording is that maxillary protraction can be a short-term effective therapy and might improve sagittal skeletal and dental relationships in the medium term, while some skeletal and dental variables showed significant relapse during follow-up and need longer-term study [F21]. This card preserves that wording and does not turn it into an effectiveness promise [F3].

Choosing an appliance is a clinical decision, and reviews disagree

Cochrane recorded that alternating rapid maxillary expansion and constriction added to facemask treatment may provide no additional ANB benefit compared with expansion alone (mean difference −0.46°, 95% confidence interval −1.03 to 0.10; 4 studies, 131 participants; low-certainty evidence) [F22]. A systematic review and meta-analysis published in 2025, searched to 2024-02, identified 61 articles and included 8 in meta-analysis; it instead reported statistically significant differences between conventional maxillary disjunction and traction and several alternating rapid maxillary expansion and constriction protocols, with the latter allowing greater skeletal corrections [F23].

The fact that two reviews reach different directions on the same question is part of the answer [F35]. Appliance and protocol selection is a clinical judgment after complete examination. This card makes no appliance comparison and gives no selection recommendation [F3].

Will treatment change appearance? Population data on soft tissue

A 2025 systematic review and meta-analysis examined early Class III treatment's effects on facial soft tissue. It included 30 studies, 16 of which entered quantitative synthesis, and participant ages ranged from 6.6 to 12.3 years [F24]. Pooled results included a 1.58 mm increase in upper-lip protrusion and 4.73° decrease in nasolabial angle for facemask plus rapid maxillary expansion compared with control, and a 2.13 mm increase in upper-lip protrusion and 2.63 mm decrease in lower-lip protrusion for chin-cup treatment compared with control [F24].

The authors concluded that low- to moderate-certainty evidence suggests early treatment positively influences soft tissue in Class III patients. The same passage immediately says those conclusions are based on two-dimensional cephalometric-image analysis, which may not provide complete or accurate information, and calls for randomised trials with full 3D analysis [F25].

Keep all three qualifications together [F3][F24][F25]: these are population-level average changes, not changes every person will have and not their likely magnitude; millimetre and angle measurements are not the same as a visible change others will notice; and the measurement method has a limitation disclosed by the authors themselves.

Underbite in adults: orthodontic compensation or orthognathic surgery

Cochrane states plainly in its background that in severe cases, or when orthodontic treatment is unsuccessful, people may need jaw (orthognathic) surgery as adults [F26]. This says two things at once: surgery is not every person's pathway, and it is an option discussed in adulthood [F26].

Whether you are in a group that needs surgery requires clinical examination, imaging, and assessment of growth status by orthodontics and oral and maxillofacial surgery. This card gives no criterion for self-matching [F3].

Cochrane also records an intermediate approach: one 30-participant study evaluated surgically implanted miniplates with facemask or Class III elastics against no treatment and found substantial improvement in horizontal incisor overlap and ANB (overlap mean difference 7.96 mm; ANB mean difference 5.20°). But the evidence was low certainty and there was no follow-up beyond the end of treatment [F27]. Separately, adding surgical anchorage to a facemask may have no ANB advantage (mean difference −0.35, 95% confidence interval −0.78 to 0.07; 4 studies, 143 participants; low-certainty evidence) [F28].

Quantified risks on the surgery side

All figures below are population-level research results, not any individual's probability and not the performance record of any institution [F3]:

• Persistent neurosensory disturbance: a 2026 systematic review and meta-analysis, searched from 1998 to 2025-02, included 47 studies and 5,406 patients. The pooled 1-year incidence of persistent neurosensory disturbance after sagittal split osteotomy was 21% (95% confidence interval 13% to 32%). “Persistent” meant any neurosensory disturbance reported or assessed 12 months after surgery [F30]. Older age, greater mandibular advancement, and intraoperative nerve exposure or manipulation were statistically significantly associated with higher risk [F31]. Two qualifications matter: the review population underwent sagittal split osteotomy in both advancement and setback directions, while underbite surgery more often involves mandibular setback; and the available evidence found persistent neurosensory disturbance not significantly associated with skeletal class in 4 of 5 studies [F31].
• Condylar resorption: a 2018 systematic review of condylar changes after bilateral sagittal split osteotomy in Class II and III dentofacial deformities found condylar-resorption-rate data in 5 studies, ranging from 0.0% to 4.2%. Its authors concluded that condylar resorption and relapse were present in a small percentage of studied patients [F32]. This is a range of rates separately reported by studies, not a pooled estimate, and the review included only 6 studies [F32].
• Stability (relapse): a 2021 systematic review and meta-analysis compared stability after one-jaw and two-jaw surgery for skeletal Class III. It included 9 studies, 8 in quantitative analysis. Short term, no significant difference was detected at ANB, A point, or B point; for horizontal incisor overlap, however, mandibular setback alone had greater short-term relapse (mean difference −0.40 mm, 95% confidence interval −0.77 to −0.04). At long-term follow-up of 5 years or more, skeletal and overlap-correction stability differences were statistically non-significant [F33]. The authors said both procedures appear to offer comparable stability within the review's limitations and that more high-quality research is needed [F33]. This compares two procedures; it is not an overall answer to “will surgery relapse?” [F33].
• Quality-of-life pattern: a 2022 systematic review and meta-analysis assessed oral-health-related quality of life before, during, and after orthodontic-orthognathic treatment. Quality of life decreased during pre-surgical orthodontics and improved after treatment. Two studies with 87 participants entered meta-analysis, showing improvement of 14.85 scale points before versus after treatment (95% confidence interval 10.36 to 19.35) [F44]. The same review states that all 6 included studies had serious risk of bias, data supporting the results were limited, and evidence quality was low [F44]. It advises that patients be fully informed about possible quality-of-life effects of facial and aesthetic changes across sequential treatment phases [F44].

What should be discussed in the consultation? Taiwan's official document is clear

In its Oral and Maxillofacial Surgery section, Taipei's approved fee schedule has an “orthognathic consultation fee” item. Its published description says that a dentist provides consultation or re-consultation on orthognathic surgery and that the content includes the purpose of the surgery, possible surgical methods and risks, and hospitalisation- and anaesthesia-related issues; it is roughly charged in 30-minute units, with less than 30 minutes counted as 30 minutes, and does not include examination, analysis, or treatment-plan preparation [F36].

Put another way, the purpose of surgery, possible methods and risks, and hospitalisation and anaesthesia issues are content the official Taiwan document specifies for this item. Asking about them in consultation is not making a dentist's work difficult; they are within what the item is meant to cover [F36]. The same schedule separately lists preparation of an orthognathic-surgery treatment plan, described as creating a possible plan according to the patient's stated concerns [F36].

Above that is Taiwan law. Article 81 of Taiwan's Medical Care Act requires medical care institutions, when diagnosing and treating a patient, to inform the patient or relevant people such as a legal representative of the patient's condition, treatment policy, measures, medication, prognosis, and possible adverse reactions [F37]. This is the basis for asking for a written explanation [F37].

National Health Insurance coverage

Article 51 of Taiwan's National Health Insurance Act lists items excluded from coverage. Paragraph 3 includes “non-traumatic therapeutic orthodontics” [F38]. That is the legal source for the general self-pay status of orthodontics [F38]. Whether an individual case is trauma-related therapeutic orthodontics, and whether other care during a course—including surgery, hospitalisation, and anaesthesia—is covered, depends on current Taiwan National Health Insurance Administration rules and review. This card makes no individual determination and gives no legal opinion on insurance claims or contract terms; those depend on the policy and contract terms [F38][F3].

Other cards on this site cover the composition of fees and how to read a quotation. This card neither repeats them nor gives any amount [F2].

Risk factors: what to know before deciding

Orthodontics and orthognathic surgery both have risks and contraindications. The actual treatment method and result vary by person and require a dentist's assessment. The following are dimensions recorded in the literature; a dentist must decide whether each applies to your situation:

• The effect of early treatment can shrink and some variables relapse: Cochrane recorded a smaller benefit at 3 years and a benefit not found at 6 years, with confidence intervals crossing 0 [F17]; the maxillary-protraction stability review recorded significant relapse in five variables during follow-up [F21].
• Evidence on adverse effects of early-treatment appliances is itself insufficient in quantity: a 2025 systematic review of adverse effects of a 2×4 fixed orthodontic appliance in mixed dentition found 82 patients with a mean age of 10 years, mostly with pseudo Class III malocclusion, anterior crossbite, and crowding. It concluded that literature-based evidence on adverse effects was inadequate in quantity, though most included studies were high quality with low risk of bias [F39]. “Insufficient evidence” does not mean “no risk.” [F39]
• Specific orthognathic-surgery risks: the pooled 1-year persistent-neurosensory-disturbance incidence after sagittal split osteotomy was 21% (95% confidence interval 13% to 32%). The review includes both mandibular advancement and setback directions and is a population-level pooled estimate, not a probability for a person or institution [F30]; condylar-resorption rates ranged from 0.0% to 4.2% across studies [F32]; there is a short-term overlap-relapse difference between procedures [F33]; and hospitalisation- and anaesthesia-related issues are expressly listed within the official Taiwan consultation item [F36].
• Quality of life can worsen first during treatment: the review recorded reduced quality of life during pre-surgical orthodontics and improvement after treatment, while also stating that evidence quality was low [F44].
• The association with temporomandibular-joint symptoms has low-certainty evidence: a 2025 systematic review of 13 studies found that most studies showed malocclusion may be associated with pain-related temporomandibular-disorder signs or symptoms in children and adolescents. The source's most frequent associations included posterior crossbite, Class II malocclusion, Class III malocclusion, and anterior open bite [F40]. But the same review rated certainty of evidence low by GRADE and says existing research has limited reliability and inconsistent findings. This card therefore does not say that an underbite causes temporomandibular disorders; the literature does not support that causal sentence [F40][F35].
• General risks of orthodontic treatment—root resorption, decalcification white spots, discomfort and cleaning difficulty during wear, and the need for retention—are covered in other orthodontic cards on this site and are not repeated here [F2].

One point that must be clear: do not do this yourself

Online suggestions to push teeth yourself, tie teeth with elastics, or buy and wear an orthodontic appliance without professional assessment are not provided here and are explicitly discouraged [F34].

The reason follows directly from the evidence: the same appearance of lower teeth biting in front has at least three different underlying causes, and outcomes are largely influenced by the cause and appliance type [F8][F9]. Distinguishing causes requires clinical examination and imaging; the definition of pseudo Class III itself requires assessing mandibular movement between centric relation and central occlusion [F5]. Applying force yourself without identifying the cause can therefore apply force in the wrong direction [F34].

There is one more point: even for appliances used in clinical care, a systematic review judged the literature on adverse effects insufficient in quantity [F39]. In that situation, self-treatment has no evidence-based safety information to rely on [F34].

If you have already used any device or method yourself and notice loose teeth, red swollen or bleeding gums, pain, or a bite change, stop using it and seek care promptly [F34].

Before-appointment checklist: take these eight questions to the visit

These are questions, not a self-check list. The answers must come from a dentist who has examined you [F3].

1. For me or my child, is this mainly about tooth position, jaw relationship, or mandibular shift during biting? Which examinations or images support that? [F4][F5]
2. If care begins now, which outcome is expected to change? How long will it be followed? If relapse occurs, what is the next step? [F17][F21]
3. What are the reasons for acting now versus observing longer? In my case, what is the timing based on? [F20]
4. Could this treatment plan still lead to a need for surgery? Who decides, and at roughly what point? [F18][F26]
5. If surgery is discussed, please explain the consultation content listed in the Taiwan fee schedule: purpose of surgery, possible methods and risks, and hospitalisation- and anaesthesia-related issues [F36].
6. What discomfort or adverse effects may occur during treatment? Which changes mean I should return before the planned appointment? [F37][F39]
7. How long is the retention phase, how should I cooperate, and what are the known consequences of not doing so? [F21]
8. Which items are included and excluded from the fee? Can I receive written information stating the charge items and amounts? (This card gives no quotation; see this site's orthodontic-fee cards for how to read fees.) [F2]

Every clinical statement in this article is mapped line by line to its cited source (see the sources and evidence chain below). It has not been clinically reviewed by a licensed practitioner. This is health information, not individual advice; assessment by a clinician is required.