Interarch elastics, commonly called rubber bands, are a frequent and important part of orthodontic treatment for many patients. These small, removable latex or synthetic bands are different from the tiny elastic ligatures that hold the wire to the brackets or the metal bands sometimes placed on molars. The purpose of interarch elastics is not to straighten individual teeth, but to apply carefully calculated force between the upper and lower jaws. This force is used to correct the relationship between the upper and lower arches.
The Specific Function of Interarch Elastics
While the brackets and wires on your teeth primarily work to level and align the dental arch, elastics serve the unique function of correcting the relationship between the upper and lower jaws. This alignment issue between the jaws is known as a malocclusion, or a “bad bite.” Interarch elastics apply a force that guides the entire upper arch or lower arch into its intended position relative to the opposing arch. This movement creates a proper, stable fit where the teeth meet when the mouth closes.
The elastics are hooked onto small protrusions on the brackets in specific configurations determined by the orthodontist. For instance, a Class II malocclusion, often called an overbite, requires elastics that run from a hook on the upper jaw back to a hook on the lower jaw. This configuration encourages the lower jaw to move forward and the upper teeth to move backward. Conversely, a Class III malocclusion, or an underbite, is addressed with an opposite elastic configuration.
These bands typically stretch from a hook on the lower jaw forward to a hook on the upper jaw. This setup exerts a force that moves the upper teeth forward and the lower teeth backward. The precise placement of the elastics, often from the canine tooth on one arch to a molar on the opposite arch, determines the vector of force.
This targeted force can also be used to address open bites, crossbites, and to fine-tune the final intercuspation, which is how the cusps of the teeth fit together. The force exerted by these elastics is carefully calibrated, often around 200 to 300 grams per side, to ensure effective movement of the dental structures. Without the use of these elastics, the fixed appliances alone cannot achieve the necessary movement to correct the jaw relationship.
The Typical Timing for Starting Elastics
Elastics are generally not introduced at the very beginning of orthodontic treatment. The overall process is typically divided into distinct phases, and the initial phase focuses on leveling and aligning the individual teeth. During this time, the orthodontist uses flexible wires to uncrowd teeth and rotate them into their correct positions within their respective arches. This foundational work can take several months, depending on the severity of the initial misalignment.
Once the teeth are mostly straight and the initial wires have been replaced with stiffer, rectangular archwires that provide more stable anchorage, the treatment transitions into the working or finishing phase. Elastics are typically introduced at this juncture because the teeth are now in a better position to absorb and transmit the force required for bite correction.
The exact timing is highly personalized and depends on how quickly your teeth respond to the initial alignment forces. While some patients may start using elastics a few months into treatment, others may not be ready for nearly a year. The orthodontist will assess your progress at each appointment, looking for signs that the teeth are sufficiently aligned to begin the complex work of arch-to-arch correction. The severity of the malocclusion also influences the timeline, as more complex bite corrections often require a longer initial alignment period.
Elastic wear often ranges from a few months up to six to eight months, and occasionally longer for difficult cases. Consistent wear is tracked by the orthodontist to determine when a stable and corrected bite has been achieved, which signals that the elastic phase is complete. The progression through this stage is a major step toward the final result and can directly influence the overall length of time you wear braces.
Daily Wearing Schedule and Compliance
The practical schedule for wearing interarch elastics is rigorous and demands a high degree of patient cooperation. To generate the continuous, gentle force necessary for biological tooth movement, elastics must be worn for approximately 20 to 22 hours per day. This means they must be worn constantly, including while sleeping, to sustain the therapeutic pressure.
Elastics are typically removed only for brushing and flossing, and sometimes for eating, although some orthodontists may instruct patients to eat with them in place. Since the elastic material loses its strength and tension over time, new bands must be placed multiple times a day, usually after every meal and before bed. This replacement frequency, often three to four times daily, ensures that the teeth are constantly subjected to the intended level of force.
Inconsistent wear, or non-compliance, is the single greatest cause of treatment delays during the bite correction phase. If elastics are not worn as prescribed, the teeth can quickly shift back toward their original positions, undoing the progress made. Missing even a single day of wear can negate the tooth movement achieved over the two preceding days. This back-and-forth movement creates unnecessary resistance, which prolongs the treatment time. The success of this final phase relies directly on following the orthodontist’s instructions precisely.