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Malocclusion of Teeth: Classification, Causes, Treatment, and More

Malocclusion is a common condition that affects many. The global prevalence of malocclusion was found to be 56%, with no significant gender differences. Regionally, Africa had the highest prevalence at 81%, followed by Europe at 72%, America at 53%, and Asia at 48%. Malocclusion prevalence remained consistent from primary to permanent dentition (1).

What is Malocclusion?

Malocclusion refers to any irregularity or misalignment of the teeth or dental arches. While not life-threatening, it significantly impacts an individual’s self-esteem and psychosocial well-being. The prevalence of malocclusion varies across different ethnicities, age groups, and genders (2)

Causes of Malocclusion

Malocclusion can be due to genetics or acquired etiology.

Acquired malocclusion can be due to trauma or injury, premature primary tooth loss, or deviation in tooth development (8), (9).

Certain traits related to malocclusion may be passed down congenitally (10).

Classification of Malocclusion

Malocclusion can be classified by Angle’s classes or Ackerman and Profitt’s classification system. Ackerman and Profitt’s classification is based on Angle’s classification but describes the malocclusion more in-depth.

Angle’s classification

This classification system is based on the position of the mesial buccal cusp of the first maxillary molar, to the buccal groove on the first mandibular molar.

Class I

Angle class I molar classification, also known as neutrocclusion, occurs when the mesiobuccal cusp of the maxillary first molar aligns with the buccal groove of the mandibular first molar.

Class II

Class II molar relationship involves the mandible positioned behind the maxilla. It’s divided into two types: Class II division 1 and Class II division 2.

  • In Class II Division 1, the maxillary incisors protrude, leading to excessive overjet and deep overbite (2). The maxillary arch is often narrow in the canine area but broad between molars. Patients may have a shorter upper lip and struggle to close their anterior lip.
  • In Class II Division 2, the maxillary central incisors are inclined towards the palate and may overlap the lateral incisors. A deep overbite and broad maxillary arch are characteristic. Unlike division 1, the upper lip seal is normal, and there is a deep mental groove. The mandible size is typically normal in division 2 (3).
Class III

Class III molar relationship is characterized by the mandible being positioned in front of the maxilla, with mandibular teeth protruding over the maxillary teeth. This malocclusion is categorized into three types based on teeth alignment (4).

  • Class III type 1: Abnormally shaped arch.
  • Class III type 2: Lingually tilted mandibular teeth.
  • Class III type 3: Lingually tilted maxillary teeth.

Ackerman and Profitt’s Classification

In Ackerman and Profitt’s classification system, malocclusion is divided into classes I, II, III, IV, V, and VI.

  • Class I: The maxillary teeth are slightly forward of the mandibular teeth, and the jaw is aligned properly.
  • Class II: The maxillary teeth are significantly forward of the mandibular teeth, and the jaw is underdeveloped.
  • Class III: The mandibular teeth are significantly forward of the maxillary teeth, and the jaw is overdeveloped.
  • Class IV: The maxillary teeth are significantly behind the mandibular teeth.
  • Class V: The maxillary teeth are significantly forward of the mandibular teeth, and the jaw is overdeveloped.
  • Class VI: The mandibular teeth are significantly behind the maxillary teeth.

Effects of Malocclusion

Malocclusion can have many negative effects on oral health. Malocclusion can lead to dental caries and periodontal disease. Malocclusion can prevent proper oral hygiene and can lead to an increased risk of dental caries and periodontal disease (5). Malocclusion can lead to Temporomandibular Disorders (6). The improper alignment of teeth or jaw relation can lead to discomfort and pain within the Temporomandibular Joint. Malocclusion can also affect a person’s quality of life. Malocclusion can affect a person’s self-esteem and mental health (7).

Treatment of Malocclusion

There are several treatment options for malocclusion. The treatment plan and options given will depend on the type of malocclusion and severity (11). A dental professional will evaluate the level of malocclusion and classification to formulate a diagnosis prior to formulating a treatment plan.

  • Palatal Expanders: These are used before braces to address a narrow palate, crowding, or crossbite. Rapid Palatal Expansion (RPE) applies pressure on the maxillary bones to split the mid-palatal suture. They’re most effective during adolescence when the maxillary bones are still flexible. Patients turn a screw daily to gradually widen the palate (12).
  • Spacers: These are used before or during braces treatment to create space between teeth. Rubber spacers are typically worn for 1 to 2 weeks and fall out when sufficient space is achieved. Metal spacers are used for longer periods, often more than six weeks, for space management.
  • Traditional Braces: This is the conventional method for treating malocclusion. Braces consist of brackets attached to teeth and an archwire that applies pressure to align teeth. Metal braces are the most common. Ceramic braces are an option and are less noticeable due to their enamel-like color. Lingual braces are placed on the lingual (tongue) surface of teeth and are mainly utliized when there are esthetic concerns (13).
  • Clear Aligners: These have gained popularity, especially among adults, as they are virtually invisible. Clear aligners use CAD/CAM technology to create customized trays for each stage of treatment. Patients wear each set of aligners for 1-2 weeks as directed by the orthodontist. They are suitable for patients concerned about aesthetics and offer flexibility. However, aligners require strict compliance and may not be suitable for severe malocclusion cases or every patient (14).
  • Future Technologies: Ongoing research is exploring newer technologies to enhance orthodontic treatment effectiveness and efficiency. These advancements may offer additional options for managing malocclusion in the future.

Diagnosis of Malocclusion

Malocclusion can have various potential causes. Diagnosing the cause often requires a thorough evaluation by an orthodontist, which may involve taking a medical history, conducting a physical examination, and ordering imaging tests like panoramic radiographs and celphalograms. Based on this evaluation, a diagnosis and treatment plan can be developed accordingly.


While some factors that cause malocclusion may not be preventable there are actions that can be taken early to help deter the effects of malocclusion. Malocclusion is typically diagnosed through visual and radiographic examinations of the teeth and face. If detected, patients are often referred to orthodontists for further evaluation and treatment. Early diagnosis through routine dental appointments is crucial for prompt intervention (15). While malocclusion is often hereditary, environmental factors like thumb sucking, and prolonged bottle or pacifier use can contribute to its development. Parents can play a role in preventing such habits early on to mitigate the risk of malocclusion.


Malocclusion, an improper alignment of teeth, is a prevalent condition affecting individuals globally. Its severity can be classified through various systems such as Angle’s, Ackerman and Profitt’s classification. Malocclusion can lead to oral health issues like dental caries, periodontal disease, and temporomandibular disorders, affecting one’s quality of life and mental health. Causes of malocclusion range from genetic inheritance to acquired factors like trauma or premature tooth loss. Treatment options include palatal expanders, spacers, traditional braces, clear aligners. Early diagnosis through routine dental appointments is crucial for effective intervention, with parents playing a role in preventing environmental factors contributing to malocclusion.