Single-arch treatment, which involves placing braces on only the bottom teeth, often appeals to people seeking a targeted, less visible, or lower-cost solution for minor alignment issues. This approach focuses solely on the mandibular arch, the lower set of teeth, while leaving the maxillary arch, or upper teeth, untreated. This targeted treatment is not a universally applicable option for every patient. Treating only one arch requires a comprehensive evaluation by an orthodontist to ensure that fixing one area does not negatively affect the entire system of the mouth.
Feasibility and Common Reasons for Single-Arch Treatment
Orthodontic treatment focusing just on the bottom teeth is generally reserved for cases involving mild dental irregularities. The most common scenario is minor crowding or spacing that is localized entirely within the lower arch. This may involve only a few teeth that have shifted slightly out of alignment over time, creating cosmetic concerns without causing any functional problems with the bite.
Many adults who had comprehensive orthodontic treatment earlier in life seek single-arch correction due to orthodontic relapse. The lower front teeth are particularly susceptible to minor shifting over the years, even after wearing retainers, and single-arch treatment can be used as a simple touch-up plan.
The feasibility relies heavily on the upper arch being already well-aligned and stable. If the upper teeth are straight and the bite is already functionally correct, then minor movements of the lower teeth can often be performed safely. The goal is always to improve the alignment of the lower teeth without causing any corresponding misalignment or interference with the existing stable upper arch.
Essential Orthodontic Assessment Criteria
The single most important factor determining eligibility for bottom-only braces is the existing relationship between the upper and lower teeth, referred to as occlusion. Orthodontists must confirm that moving the lower teeth will not destabilize or negatively alter how the arches meet when the patient bites down. This requires a thorough analysis of the patient’s existing bite classification, usually aiming for a stable Class I molar relationship where the upper and lower first molars align correctly.
The assessment also focuses on the vertical and horizontal overlap of the front teeth, known as overbite and overjet, respectively. A healthy overjet, the horizontal distance between the upper and lower incisors, typically measures between 2 to 4 millimeters. Similarly, a normal overbite, which is the vertical overlap, covers approximately one-third to one-half of the lower incisors. Any movement of the lower teeth must be contained within these acceptable parameters.
If the patient’s occlusion is already slightly compromised, or if the necessary tooth movements risk creating an unstable bite, bottom-only treatment is usually contraindicated. The orthodontist must confirm that the repositioned lower teeth will track smoothly against the upper teeth during all jaw movements. If the lower arch needs significant expansion or retraction, then comprehensive treatment involving both arches becomes necessary.
Limitations and Risks of Treating Only the Bottom Teeth
The primary concern with single-arch treatment is the potential to inadvertently create a new bite problem while attempting to solve a cosmetic one. Moving the lower teeth, even slightly, changes their final position in relation to the static upper teeth, which can destabilize the previously functional occlusion. This can lead to the creation of an improper bite relationship, such as an anterior crossbite or an open bite, where the front teeth do not meet correctly.
An uneven or incorrect bite can introduce a risk of premature contact between certain teeth. When a few teeth hit before the rest, the uneven force distribution can lead to increased wear on the enamel surfaces and potential chipping of the teeth. This imbalance can also place undue strain on the temporomandibular joint (TMJ), potentially leading to discomfort or jaw pain over time.
Achieving a perfect aesthetic result is inherently limited when only one arch is treated. While the lower teeth may become straight, a slight misalignment in the upper arch or a discrepancy in the dental midlines will remain uncorrected, compromising the overall balance of the smile. Ultimately, if the single-arch treatment fails to maintain bite stability or creates functional issues, the patient may require full comprehensive treatment later to correct the newly created problems, often at a greater overall cost and duration.
Cost and Treatment Duration
The motivation for pursuing bottom-only braces is often related to the potential for a reduced financial and time commitment. Single-arch treatment is generally less expensive than full treatment, typically costing between 60% to 70% of the price of braces on both arches. The cost for metal braces on the lower arch alone can range from $1,800 to $3,500, while clear aligner options for mild cases may fall into a similar range.
The treatment duration for minor lower crowding is also typically shorter than a full case. While comprehensive treatment can last 18 to 30 months, single-arch cases often conclude within 6 to 12 months, depending on the severity of the misalignment. This shorter timeline appeals to patients who desire a quick resolution to their cosmetic concerns. However, regardless of the treatment length, the use of a retainer is a lifelong necessity to prevent the teeth from shifting back into their original positions.