An underbite, clinically known as a Class III malocclusion, is a dental condition where the lower teeth and jaw protrude past the upper teeth and jaw. This misalignment can lead to functional problems, such as difficulty chewing, and may also affect facial appearance. While traditional metal braces are a common solution, advancements in orthodontics have introduced several non-brace methods. These alternative treatments focus on leveraging natural growth processes in younger patients or applying discreet, tooth-moving forces in adults.
Correction without traditional fixed appliances depends heavily on the underlying cause, categorized as either dental or skeletal. A dental underbite involves misaligned teeth within normally positioned jaws, whereas a skeletal underbite involves a discrepancy in the size or position of the upper jaw (maxilla) or lower jaw (mandible). The treatment approach must be tailored specifically to whether the issue is primarily tooth positioning or jaw structure.
The Importance of Early Intervention and Patient Age
Correcting a skeletal underbite without surgery relies on timing the treatment during the patient’s growth phase. The years of childhood and early adolescence represent a unique opportunity for orthopedic or growth modification treatment. This phase is characterized by the malleability of the facial bones, particularly the upper jaw.
When a skeletal discrepancy is identified, treatment is often initiated between the ages of seven and ten, before the peak of the pubertal growth spurt. Treatment during this window allows the orthodontist to guide the development of the jaws toward a more harmonious relationship. If treatment is delayed until after growth has largely ceased, non-brace options for skeletal correction become ineffective, leaving tooth movement or surgery as the only viable paths.
The distinction between a skeletal and a dental underbite dictates the urgency and type of treatment. A true skeletal underbite, often caused by a deficient upper jaw or an overgrown lower jaw, requires intervention while the bone structure is still developing. A milder dental underbite, where only the teeth are positioned incorrectly, can often be addressed later in life through simpler tooth-moving methods. Addressing the skeletal issue early can prevent the need for more invasive procedures, like orthognathic surgery, in adulthood.
Non-Brace Appliances for Jaw Growth Modification
Specialized orthopedic appliances are used to modify jaw growth in younger patients by directing the growth of the maxilla and mandible. These devices are non-brace solutions designed to address the skeletal component of the underbite. They work by applying controlled forces to the jaw bones to encourage or restrict growth in specific directions.
Reverse Pull Face Mask
The Reverse Pull Face Mask, also called a protraction headgear, is a primary tool for stimulating the forward growth of a deficient upper jaw. This appliance consists of a frame that rests on the forehead and chin, connected by elastic bands to an anchor device inside the mouth, often a Palatal Expander. The elastics apply a continuous forward and downward force on the upper jaw, encouraging it to “catch up” to the lower jaw.
Palatal Expander
A Palatal Expander is frequently used in conjunction with the face mask to widen the upper jaw. This helps unlock the upper jaw from the lower jaw and facilitates its forward movement. The combination of expansion and protraction is effective for correcting underbites that are primarily due to a recessed upper jaw. Patients are typically instructed to wear the face mask for 12 to 14 hours per day, often overnight and during time spent at home, for a period of six to twelve months.
Chin Cap
For cases where the lower jaw (mandible) is slightly overgrown, a Chin Cap appliance may be used to restrict its forward growth. This device consists of a cup that fits over the chin and is connected by headgear straps to a cap on the head. The chin cap applies a backward and upward force to the mandible, which encourages a backward rotation and may slow down the forward growth trajectory. While the Chin Cap has been shown to improve the jaw relationship in growing patients, its effects are generally less profound than the forward pull of the face mask on the maxilla, and long-term stability can vary.
Clear Aligners and Corrective Myofunctional Therapy
For patients who have completed their skeletal growth or who have mild underbites, treatment shifts from modifying jaw bone structure to correcting tooth position and muscle function. Clear aligners, such as those made by Invisalign, are an effective non-brace option for minor to moderate dental underbites. These aligners work by gradually tipping or moving the lower teeth backward and the upper teeth forward, a process known as dentoalveolar compensation.
Clear Aligners
Clear aligners are custom-made, clear plastic trays that are worn sequentially. Each one is designed to move the teeth slightly closer to the desired final alignment. Specialized attachments or elastics can be worn with the aligners to increase the force and rotational control needed to correct the bite. This method is most appropriate when the jaw bones are well-positioned, and the malocclusion is due to the angle of the teeth.
Corrective Myofunctional Therapy (OMT)
Corrective Myofunctional Therapy (OMT) is an exercise-based program that addresses improper muscle habits, such as incorrect tongue posture and dysfunctional swallowing patterns. Since the constant pressure from the tongue and facial muscles influences the position of the teeth and the shape of the dental arches, retraining these muscles can support orthodontic correction. OMT aims to establish a proper resting posture for the tongue against the palate and encourage nasal breathing, which can help stabilize the bite correction. Myofunctional therapy is rarely a standalone treatment for a significant underbite but serves as a valuable adjunct to aligners or other orthodontic appliances.
Recognizing Severe Cases That Require Surgery
The non-brace and orthopedic methods have limits, and their success depends on the severity of the underbite and the age of the patient. Once skeletal growth is complete, typically in the late teens or early twenties, a severe skeletal underbite cannot be corrected by non-surgical means. This threshold is reached when the discrepancy between the size or position of the upper and lower jaws is too great to be masked by moving the teeth alone.
In these severe cases, orthognathic surgery, or corrective jaw surgery, becomes the necessary treatment to achieve a stable and functional bite. The surgery involves physically repositioning the jaw bones, either by moving the upper jaw forward, the lower jaw backward, or a combination of both. The primary fix is the movement of the bone structure, though pre- and post-surgical orthodontics are often required to align the teeth properly. A severe underbite left uncorrected can lead to long-term functional issues, including excessive wear on the teeth, chronic jaw pain, and difficulty with chewing and speaking. Surgery offers a permanent solution by establishing a correct skeletal foundation.