Overdevelopment of the upper jaw: causes, diagnosis, treatment

Maxillary prognathism is an excessively anterior position of the maxilla and/or its alveolar process relative to the mandible, which is clinically manifested by increased horizontal overlap of the incisors (overjet), a convex profile, and a distal molar relationship. In practice, it is often considered within the spectrum of Angle's Class II dentofacial anomalies, where the contribution of "true" maxillary hyperprojection must be distinguished from mandibular retrognathism. Distinction between the skeletal and dentoalveolar components is made clinically and by cephalometric methods (e.g., SNA, SNB, ANB angles, and the Wits index). The choice of timing and method of treatment, from orthopedic appliances during the growth period to orthognathic surgery in adulthood, depends on accurate differentiation. [1]

The clinical significance of upper prognathism extends beyond aesthetics: severe overjet increases the risk of upper incisor injury in children and adolescents, impacts chewing, speech, and lip closure, and can be accompanied by temporomandibular joint dysfunction. Some patients experience persistent psychological consequences (shame, decreased confidence), which is important to consider when choosing the strategy and timing of correction. Modern protocols utilize functional appliances, intracavitary molar distalization with temporary support devices (miniscrews), aligners with a mandibular advancement module, and, in cases of severe skeletal discrepancies, orthognathic surgery (Le Fort I variants). [2]

Digital diagnostics, 3D planning, and cone-beam computed tomography have improved the accuracy of jaw relationship assessment and surgical planning. In orthognathia, virtual surgical planning and the printing of custom-made guides have become widespread, improving the accuracy of fragment positioning and helping manage the risk of recurrence. However, stability remains a key issue: different recurrence profiles have been described for different vectors of maxillary displacement. [3]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, dentofacial anomalies are coded in blocks M26-M27. For Angle's classes, M26.212 "Malocclusion, Angle's Class II" is applicable, while M26.23 is applicable for the feature "excessive horizontal overlap." Associated features (e.g., deep bite, open relationship) are reflected when necessary. These codes are appropriate when documenting clinical forms of maxillary prognathism as part of Class II. [4]

In the International Classification of Diseases, Eleventh Revision, the section "Dentofacial Anomalies" (DA0E) contains the heading "Malocclusion" (DA0E.5) with subcategories, including "Class II division 2" (DA0E.50). In ICD-11 practice, post-coordination is used: parameters for the side, severity, and associated functional disorders are added to the basic malocclusion code. When focusing on the size and position of the jaws, "Major anomalies of jaw size" (DA0E.0) and "Anomalies of jaw-cranial base relationship" (DA0E.1) are also used. [5]

Table 1. ICD-10/ICD-11 coding guidelines for upper prognathism

Clinical situation	ICD-10 (examples)	ICD-11 (examples)	Comment
Class II malocclusion (including upper prognathism variants)	M26.212	DA0E.5 (Class II; e.g. DA0E.50 for div.2)	Specify the division 1/2 and related features. [6]
Excessive overjet	M26.23	DA0E.5 + expression modifiers	Useful for recording the risk factor for incisor injuries. [7]
Anomalies in jaw size/basic relationship	M26.09/M26.19	DA0E.0 / DA0E.1	Used for skeletal dominant phenotype. [8]

Epidemiology

Class II malocclusion is one of the most common: according to modern systematic reviews, the average prevalence in the population is approximately 23-24% (with wide variation between studies). The highest proportions of class II malocclusion are described in Caucasian cohorts; in school-age children, the distribution depends on age, gender, and assessment criteria. These figures reflect not only true differences but also methodological heterogeneity across studies. [9]

A detailed analysis by country reveals significant variations: in some Asian samples, the proportion of Class II can be below 10-12%, while in others it is above 20%. This variability highlights the need for local registries and diagnostic uniformity (including the description of severity by overjet and molar stage). In the clinic, this impacts screening planning and orthodontic resource allocation. [10]

A large overjet is an independent epidemiological marker of the risk of upper incisor trauma: meta-analyses and reviews in recent years confirm that the likelihood of injury in children with an overjet ≥3-5 mm is 2-3 times or more higher, with this effect being observed across different age groups. This argues for early interceptive correction in patients with a high risk of trauma. [11]

Table 2. Epidemiology and clinical landmarks

Indicator	Data/guideline
Average prevalence of class II	≈ 23-24% (wide range)
Highest shares of class II	more often in Caucasian cohorts
Risk of incisor injury with increased overjet	2-3+ times higher

Reasons

Etiologically, upper prognathism results from an imbalance between the position of the maxilla and mandible and the dentoalveolar arches: true overdevelopment of the maxilla (high SNA), retrognathia of the mandible (low SNB), and a combination or predominantly dentoalveolar protrusion of the incisors. The distribution of these contributions is influenced by genetics, growth pattern, soft tissue factors, and functional habits. Distinguishing these mechanisms is critical for the choice between growth orthopedics and surgery. [12]

Long-term orofacial habits (mouth breathing, thumb sucking, infantile swallowing) and upper airway obstructions can increase the anterior position of the upper incisors and create detrimental lip biomechanics. Combined with weakness of the peribuccal muscles, this contributes to overjet. However, the presence of habits does not preclude a skeletal component. [13]

Risk factors

A family history of Class II and facial growth pattern characteristics (increased facial convexity, vertical growth component) increase the risk of upper prognathism. Early childhood habits and incisor trauma exacerbate the condition. Age is also important: the closer to puberty observation begins, the greater the potential for growth modification. [14]

A large initial overjet (≥5-6 mm) is a factor in both injury and psychological problems, especially in schoolchildren. Patients who participate in sports activities in high-risk contact zones (football, basketball, martial arts) require priority correction and protection (mouth guards) during treatment. These considerations are included in the management plan. [15]

Table 3. Modifiable and non-modifiable factors

Factor	Type	Clinical significance
Genetics/growth pattern	unmodifiable	defines the "skeletal" basis
Habits, mouth breathing	modifiable	supports overjet
Large overjet	risk marker	↑ risk of injury, indication for early correction

Pathogenesis

The key is the misalignment of the bases of the jaws: in true upper prognathism, the anterior position of the A-point relative to the cranial base (high SNA) combined with normal SNB/low SNB results in an increased ANB; in predominantly dentoalveolar prognathism, the upper incisors protrude forward without significant base displacement. A Wits assessment along the occlusal plane helps to clarify the sagittal discrepancy. The totality of measurements is more important than any single angle. [16]

Soft tissue biomechanics (lip competence, tongue tone), airway, and muscle balance influence the position of the incisors and the stability of the result. During the growth period, the rate and direction of jaw growth are added to this, explaining the effectiveness of functional appliances during the pubertal spurt. In adulthood, skeletal imbalances require surgical solutions. [17]

Symptoms

Externally, there is a convex profile with a deepened nasolabial fold, protruding upper incisors, difficulty closing the lips, and sometimes interposition of the lower lip behind the incisors. Intraorally, there is a Class II distal molar-canine relationship, increased overjet, and often a narrowing of the upper arch and crowding. Complaints include chipped and injured incisors, aesthetic discomfort, and speech impediments for certain sounds. [18]

Severe skeletal imbalances may result in chewing inefficiency and overloading of individual teeth; some patients report discomfort in the temporomandibular joint, although the cause-and-effect relationship is unclear. Symptoms may fluctuate with growth, emphasizing the importance of dynamic monitoring in childhood. [19]

Classification, forms and stages

According to Angle, Class II is divided into Division 1 (protrusion of the upper incisors, large overjet) and Division 2 (retrusion of the central incisors and protrusion of the lateral incisors, shortened upper lip, deep bite). Upper prognathism is most often characterized by a Division 1 profile, but mixed patterns are also encountered. It is also important to describe the severity by the degree of molars and the magnitude of the overjet. [20]

Skeletal classification relies on ANB, Wits, and a combination of SNA/SNB, taking into account the vertical pattern. The phenotype of "true upper prognathism" involves increased SNA with normal/increased ANB; lower retrognathia involves decreased SNB with normal SNA. Tactics vary: "growth restriction" of the upper jaw and/or stimulation of lower protrusion versus surgical positioning. [21]

Table 4. Practical classification

Axis	Categories	Clinical significance
According to Engle	Class II, Division 1 / Division 2	incisor profile and fixation plans
By the skeleton	↑SNA (max+), ↓SNB (mand−), combined	choice of orthopedics/camouflage/surgery
By severity	overjet: light/moderate/heavy; molar stage	volume and duration of treatment

Complications and consequences

Clinically significant is the risk of injury to the upper incisors, especially in children with an overjet of ≥3-5 mm; consequences include enamel chipping, dislocations, and tooth loss. Psychosocial effects (shame, ridicule) impair quality of life and motivation for treatment—this is a separate indication for early intervention. With prolonged imbalance, periodontal overload changes and abfractions are possible. [22]

After treatment, the main risks are relapse of the dental alveolar position (if retention is not maintained, habits return) and, after surgery, vector-dependent skeletal relapses. Risk management includes retention splints/mouth guards, habit management, and, in adults, careful selection of the vector of movement and fixation using Le Fort I. [23]

When to see a doctor

An orthodontist should be consulted if there is noticeable protrusion of the upper incisors, difficulty closing the lips, chipped or injured teeth, or ridicule about one's appearance. The optimal "window" for function and growth is the pubertal spurt; an early assessment at 7-8 years of age allows for the planning of interceptive measures if the risk of injury is high. For adults with significant skeletal imbalance, a consultation with a maxillofacial surgeon is essential. [24]

Athletes with a large overjet require a custom mouth guard even before treatment begins to reduce the risk of injury. Parents of children with habits (finger, pacifier) should discuss their correction, as this affects the stability of the results. Such steps reduce the time and extent of subsequent therapy. [25]

Diagnostics

Step 1 - Clinical examination: profile/convexity, lip competence, overjet and deep overlap size, molar-canine occlusion, arch volume, and airway. Bad habits and traumatic history are recorded. In children, the stage of maturity is additionally assessed (including by the thoracic vertebrae on a lateral teleradiograph). [26]

Step 2 – targeted imaging and cephalometry: lateral teleradiography with measurements of SNA, SNB, ANB, Wits, and vertical parameters; if necessary, CBCT for 3D planning and airway/root assessment. Digital 3D scans of the jaws and a profile/facial photograph serve as the basis for the dynamics. The results are discussed at a multidisciplinary consultation during the proposed surgery. [27]

Step 3 – forming a diagnosis by axes (skeletal/dental/soft tissue) and choosing a strategy: growth orthopedics, orthodontic "camouflage," or surgery (post-growth). For high-risk incisor injuries, early overjet reduction is a priority. The treatment plan is agreed upon with the patient using digital simulation. [28]

Table 5. Diagnostic minimum

Component	What do we measure/evaluate?	For what
Clinic	profile, overjet, Engle's ratios	primary stratification
Cephalometrics	SNA/SNB/ANB, Wits, vertical angles	skeletal versus dentoalveolar
3D data	CBCT, intraoral scans	biomechanics/surgical planning

Differential diagnosis

The first question is "upper prognathism" or "lower retrognathism": true upper prognathism has an increased SNA, while lower retrognathism has a decreased SNB; ANB and Wits help clarify the contribution of each jaw. The second is "skeletal versus dentoalveolar": with predominantly dentoalveolar prognathism, anterior inclination of the upper incisors is observed without significant displacement of the basal surfaces. This influences the choice: distalization/extractions vs. orthognathia. [29]

Specific differential cases include bimaxillary protrusion (both arches are brought forward with relatively normal ANB), ethnic profile norms, and the consequences of endocrinopathies (rare). For children, age norms and stages of tooth replacement are taken into account. When in doubt, the "rule of thumb" is to first treat the potentially traumatic overjet, then determine the residual skeletal imbalance. [30]

Table 6. How to distinguish the main scenarios

Scenario	SNA	SNB	ANB/Wits	Tactics
True upper prognathism	↑	N/↑	↑	max+ limitation / surgery at maturity
Lower retrognathia	N	↓	↑	functional devices / mand extension
Dentoalveolar prognathism	N	N	N/moderate ↑	distalization/extractions/aligners

Treatment

During the period of active growth, the goal is to change the developmental trajectory of the jaws and reduce overjet. For patients with predominantly retrognathic mandibles, functional appliances (Twin-Block, Herbst, and their modifications) are used. Randomized studies have shown a reduction in overjet and an improvement in grade during the pubertal spurt. The choice of appliance depends on age, cooperation, and vertical profile. [31]

If true upper prognathism predominates, strategies to limit maxillary growth (various types of headgear or camouflaging mechanical brackets) are used in growing patients. The effect is moderate, but significant with proper selection and adherence to the wearing regimen. Combinations with functional devices allow for control of both bases. Modern protocols prioritize interceptive overjet reduction in trauma-prone children. [32]

In adults, for mild to moderate cases without significant skeletal imbalance, "camouflage" is used: distalization of the upper molars with mini-screws (TADs), intermaxillary traction, and premolar extractions for anterior retraction. Systematic reviews show that TAD distalization effectively displaces molars distally with minimal anchor loss, especially when using rigid palatal appliances. The choice of technique is determined by the patient's profile, periodontal status, and needs. [33]

Aligners can be used both for camouflage and in growing patients in combination with mandibular advancement modules or intermaxillary traction devices. Modern reviews and comparative studies indicate that for mild-to-moderate Class II teeth, aligners with elastics or a mandibular advancement module can reduce overjet and improve class status; however, the quality of evidence varies, and for skeletal imbalance, classic functional appliances are preferred. Clinical selection and monitoring of cooperation are critical. [34]

In cases of severe skeletal upper prognathism (high SNA and ANB, unfavorable soft tissues), orthognathic surgery is indicated after growth has completed. Basic options include single-jaw positioning of the maxilla (maxillary setback) at the Le Fort I level or bimaxillary procedures (combined with mandibular repositioning/augmentation). Modern series confirm that the "horseshoe" and other modifications of the Le Fort I technique provide predictable stability when positioned correctly. [35]

Surgical planning is performed in 3D: virtual surgical planning, printing of customized guides and splints, airway assessment, and soft tissue vector assessment. Meta-analyses show that the 3D approach improves positioning accuracy and reduces technique-dependent variability; however, a learning curve remains, especially with posterior impaction. Teamwork between an orthodontist, surgeon, and technician is the standard of modern treatment. [36]

Stability is a separate goal: the risk of relapse depends on the direction and magnitude of movement, the quality of bonding, and orthodontic preparation/retention. Systematic reviews note acceptable skeletal stability in the sagittal plane after segmental and total Le Fort I implants, but late dentoalveolar shifts are possible. Retention protocol and habit management remain key after any treatment option. [37]

Postoperative care includes dietary recommendations, mandibular physiotherapy, occlusion control and elastic management, and prevention of complications (infection, paresthesia, secondary malocclusion). According to reviews, typical complications of Le Fort I include bleeding, infection, segmental necrosis (rare), tooth devitalization, and relapse; careful planning and technique reduce these risks. Subsequent orthodontic finishing is mandatory. [38]

Regardless of the treatment method, all patients are prescribed retention (removable/fixed retainers) and monitoring of relapse factors (habits, breathing, lip tone). For children and adolescents, an injury prevention program (customized sports mouthguards) is implemented before and during treatment. Regular examinations and photo/scan monitoring help identify drift early. [39]

Table 7. Choice of treatment strategy by phenotype

Phenotype	Growth period	Adult
True superior prognathism (↑SNA)	headgear strategies, combined	Le Fort I setback/bimaxillary
Retrognathia of the lower back (↓SNB)	Twin-Block/Herbst/other functional	camouflage/bimaxillary
Dentoalveolar prognathism	distalization, aligners, extractions	TAD-distalization/aligners/extractions

Prevention

Primary prevention involves early orthodontic screening (first visit around age 7) focusing on habits, airway, and injury prevention. Interceptive overjet reduction in high-risk groups reduces the incidence of incisor injuries. Training parents and athletes in the use of mouthguards reduces dental losses. [40]

Secondary prevention of recurrence includes retention, control of soft tissue factors, and habit modification. In adults after surgery, this includes adherence to nutritional and elastic management protocols and scheduled visits to assess stability. Digital monitoring (photos/scans) improves adherence. [41]

Table 8. Preventive measures and their purpose

Measure	Target
Early screening and interception	reduce dangerous overjet
Sports mouthguards	protection of incisors
Retention and habit control	relapse prevention

Forecast

In mild to moderate cases without significant skeletal imbalance, the prognosis is favorable: camouflage strategies and/or interception allow for stable function and aesthetics with good retention. In growing patients, functional appliances are most effective during peak puberty. Timely correction reduces the risk of incisor injuries and improves quality of life. [42]

In cases of severe skeletal upper prognathism, long-term stability depends on the correct choice of vector and extent of orthognathic correction and the quality of orthodontic preparation/retention. In general, Le Fort I and its variations demonstrate acceptable stability with modern fixation and 3D planning, but the risk of relapse varies from person to person. Joint planning and informed consent are the foundation for a predictable outcome. [43]

FAQ

Is it always a "large" upper jaw?
Not necessarily. Often, "upper prognathism" is a combination of moderate enlargement of the upper jaw and/or protrusion of the upper incisors with a relatively "small" lower jaw. Cephalometry (SNA/SNB/ANB, Wits) helps differentiate between the two. [44]

Is it possible to correct this without surgery?
In growing patients, yes, with functional appliances and/or restrictive strategies for the upper jaw; in adults with mild to moderate imbalance, camouflage (TAD distalization, aligners, extractions) is the solution. In cases of severe skeletal discrepancy, orthognathic surgery is optimal. [45]

Will aligners cope with Class II?
In mild-to-moderate cases, yes, often, especially in combination with intermaxillary traction or a mandibular advancement module in growing patients; however, in cases of severe skeletal problems, there is less evidence, and classical approaches or surgery are preferred. Patient selection is everything. [46]

Is a large overjet dangerous?
Yes. It increases the risk of upper incisor injuries by 2-3 times and is an argument in favor of early interceptive correction and the use of sports mouthguards. [47]

What codes should be used in documents?
ICD-10: M26.212 (Class II), M26.23 (excessive overjet), additional codes M26.0x/M26.1x as needed. ICD-11: DA0E.5 (malocclusions, including Class II), with post-coordination of parameters; when focusing on size/base - DA0E.0/DA0E.1. Check local coding rules. [48]