Learn to Identify and Treat Patient Malocclusions
Considered to be the architect of modern orthodontics, 19th-century dentist Edward Hartley Angle developed the malocclusion classification system in 1899, and it is still used in a slightly modified version today. Angle determined that Class I malocclusions involve mild crowding and positional or rotational aberrations. Class II malocclusions include the upper incisors creating noticeable “overjet” (tilting outwards) and the upper incisors tilting labially (towards the lips). Finally, Angle wrote that Class III malocclusions exhibited a negative overjet (overbite) due to teeth overcrowding and spatial abnormalities.
The modern definition of malocclusion refers to a misalignment of the upper and/or lower teeth that is measurable enough to interfere with the person’s ability to bite properly. Dentists make a professional diagnosis of malocclusion by assessing the size and shape of teeth, the position of teeth when the mouth is closed, and, in some cases, the architecture of supporting skeletal structures. Normal alignment of teeth involves the upper teeth resting slightly over or in front of the lower teeth, with molar points corresponding with the grooves of oppositional molars.
The most common types of malocclusion are overbites and underbites. Overbites occur when teeth 6 through 11 (incisors and canines) jut out and over the bottom teeth. Underbites usually involve teeth 21 through 28 (1st bicuspid, canine, lateral and central incisors) that extend farther in front of the upper teeth when the mouth is biting or closed.
Causes of Malocclusions
Malocclusions can occur in baby teeth or permanent teeth. Excessive use of pacifiers, thumb sucking, or tongue thrusting in children from one to three years old may force baby teeth and, eventually, permanent teeth to erupt in overbite positions. Early loss of baby teeth, the eruption of extra teeth (hyperdontia), or having abnormally shaped teeth could promote an underbite or overbite.
Class III malocclusions are believed to emerge from the interaction of environmental factors and genetic susceptibility. Recent studies indicate that chromosomal loci 1p36 and 12q23, and 12q13 harbor genes increase the risk for Class III malocclusion in individuals carrying these genetic markers.
Dentoalveolar and Skeletal Malocclusion
Dentoalveolar malocclusions specify improper bite parameters between the lower and upper teeth. A dentoalveolar malocclusion also exclusively refers to bite misalignment due to crooked or otherwise incorrectly positioned teeth.
Skeletal malocclusions implicate a distorted shape and/or size of the jawbones causing the malocclusion. If the development of the mandibular or maxillary bone support is abnormal, teeth will likely be mispositioned, crowded, or crooked. Skeletal malocclusions are typically diagnosed in neonatal infants and often accompany tongue deformities, cleft palate, or other skeletal abnormalities
Class I Malocclusion
When an overlap (upper teeth rest over the lower teeth while biting down) exists but the bite is normal or near-normal, the patient may be diagnosed with a Class I malocclusion. Subtypes of Class I malocclusions include:
Class I, Type I: upper and/or lower teeth are angled towards the tongue.
Class I, Type II: a narrow arch accompanied by overlap and the lower teeth leaning towards the tongue.
Class I, Type III: teeth crowding and angling of the upper front teeth towards the tongue.
Class II Malocclusion
The classic appearance of an overbite defines a Class II malocclusion. Normal bites require a minimal overbite to accommodate closure of the upper and lower teeth. However, if the bite space between the upper teeth and lower teeth is over two millimeters, dentists may diagnose a Class II malocclusion.
Dental overbites emerge from interference with dental development, such as excessive thumb-sucking, extra teeth/crowding, or loss of molars.
Impinging overbites are severe overbites that force the lower teeth to make contact with the palate lying behind the upper teeth.
Overjets are not standard overbites. Instead, the American Board of Orthodontics defines an overjet as measured by the space between two antagonistic anterior teeth and the facial surface of the most lingual tooth to the middle of the incisal edge of the more facially positioned tooth. When this space is between 3.1mm and 9mm, the malocclusion is considered an overjet.
Class III Malocclusion
Severe underbites resulting from protrusion of the lower teeth over the upper teeth is a Class III Malocclusion. This class also includes crossbites, which are characterized by alternating, overlapping lower and upper teeth. Angle further described Class III malocclusions as involving an underdeveloped arch that promotes leaning of the upper teeth towards the tongue.
Patients with a Class III malocclusion may present with a protruding chin with or without visible signs of maxillary or upper jaw deficiencies. Several conditions may cause the development of a Class III malocclusion, such as retrusive maxillary dentition, protrusive mandibular dentition, or maxillary retrognathism.
Global Prevalence of Malocclusions
A review of studies investigating the rates of Class I, II, and III malocclusions found the following:
- Distribution of Class I malocclusions: 74.7%.
- Distribution of Class II malocclusions: 19.56%.
- Distribution of Class III malocclusions: 5.93%.
Africans and African-Americans had the highest rates of Class I malocclusions. Caucasians had the highest rates of Class II malocclusions. Asians, Eurasians, and Asian-Americans had the highest rates of Class III malocclusion.
Treatment Modalities for Malocclusions
Most Class I malocclusions can be corrected with braces. Digital or traditional bite impressions and X-rays are taken to determine the best treatment program before prescribing correctional appliances. If overcrowding is the specific cause of the Class I malocclusion, extractions may be needed before the actual treatment process begins.
Class II malocclusions can also be improved with braces, retainers, and/or headgear. Retainers may be recommended for younger patients with immature jawbones. Headgear is also useful for supporting normal jaw growth and alignment in children between six and 12 years old.
For treating Class III malocclusions, extraoral and/or intraoral appliances are first-choice treatments before orthopedic surgery is deemed necessary. Examples of intraoral appliances include the Bionator III, Frankel III Functional Appliance, and the Eschler Appliance. Examples of extraoral appliances include the Chin Cap, Face Mask with Dental Anchorage, and the Protraction Face Mask and Reverse Twin Block.
Diagnosing malocclusions is a science, but treatment is both a science and an art. That’s why it’s so important to learn from the best. We carefully select the instructors of our courses who are not only remarkably skilled at orthodontics but also adept at passing on their wealth of knowledge so that you can come away ready to offer exceptional orthodontic care to your patients.
To learn more about our popular orthodontics courses for pediatric and general dentists, check out one of the upcoming events below.