A bite plate is a common orthodontic appliance used primarily to address issues related to the vertical dimension of the bite, which is the amount of overlap between the upper and lower teeth. This device is typically constructed of acrylic and is designed to fit over the upper or lower teeth, creating an artificial biting surface. The purpose of the bite plate is to temporarily block the normal contact between the upper and lower back teeth. This separation initiates biological responses that allow for the correction of vertical discrepancies in the jaw relationship.
The Physical Mechanism of Action
The corrective action of a bite plate begins with a process called occlusal disengagement. When a patient bites down on the plate, the back teeth are prevented from touching, effectively “opening” the bite in the posterior region of the mouth. This separation removes the normal physical interferences that stabilize the position of the back teeth and inhibit vertical changes.
This disengagement allows for two primary types of passive tooth movement to occur, correcting the underlying bite problem. For patients with a deep bite, the posterior teeth—the molars and premolars—are freed to passively erupt, or grow longer, as the body seeks to re-establish full bite contact. The alveolar bone surrounding these teeth also increases in height, contributing to the overall bite opening.
Concurrently, the front teeth that contact the bite plate are subjected to a constant, light force. This gentle pressure can encourage the anterior teeth to be intruded, meaning they are pushed slightly back into the bone socket. The combination of posterior eruption and anterior intrusion is the biomechanical strategy used to level the bite and reduce the excessive vertical overlap.
Design Variations of Bite Plates
Bite plates are fabricated in different constructions to suit various treatment needs. One major distinction is between removable and fixed appliances. Removable plates are usually made from acrylic and are secured to the upper teeth with small wire clasps. They typically feature a thick acrylic platform positioned behind the front teeth.
Fixed, or bonded, bite plates are small pads of composite resin or glass ionomer cement that are cemented directly onto the chewing surface of specific teeth, such as the molars or bicuspids. These small blocks function similarly to the larger acrylic plate by creating a point of contact that prevents the full closure of the bite.
Beyond removability, plates are also classified by their location: anterior or posterior. An anterior bite plate is the most common type, featuring a ramp or flat surface behind the upper front teeth that the lower front teeth contact. A posterior bite plate, conversely, is placed over the biting surfaces of the back teeth, often used to eliminate interferences or to facilitate different kinds of tooth movement.
Orthodontic Conditions Requiring a Bite Plate
The primary problem requiring a bite plate is an excessive vertical overlap, known as a deep overbite. This occurs when the upper front teeth cover too much of the lower front teeth when the jaw is closed, sometimes covering them completely. This condition is generally defined as an overlap greater than 40% of the lower incisor crown height.
An exaggerated deep overbite can lead to a number of functional issues over time. The excessive overlap may cause the lower incisors to bite into the gum tissue behind the upper front teeth, leading to irritation and damage. A deep bite can also contribute to abnormal wear on the biting edges of the front teeth as they rub against one another during function.
This vertical problem is often associated with an excessive Curve of Spee in the lower arch. The Curve of Spee is the natural slight upward curve of the chewing surfaces of the lower teeth from the front to the back. When this curve is too deep, it contributes to the deep overbite, which the bite plate helps to level primarily through the eruption of the back teeth.
Wearing and Treatment Protocol
Successful treatment with a bite plate relies heavily on patient compliance, especially with removable designs. The appliance must be worn consistently, often specified as close to 24 hours a day, only removing it for brushing. Wearing the plate for fewer hours, such as only at night, will not maintain the continuous pressure needed for effective tooth movement, slowing or halting progress.
The total duration of treatment with a bite plate is typically measured in months rather than years. The appliance is often used at the beginning of orthodontic treatment to quickly open the bite before full braces are engaged. Patients should anticipate a period of adjustment immediately following the fitting of the plate.
Initial difficulties with speech, such as a temporary lisp, and some soreness in the teeth or jaw muscles are common for the first week. Since the back teeth are temporarily prevented from touching, patients are advised to eat softer foods until they adapt to chewing with the front teeth contacting the plate. Maintenance involves cleaning the removable plate with a toothbrush and cool water after every meal to prevent the buildup of bacteria and odors.