The shape of your smile depends on several factors working together: the width of your dental arch, how much gum tissue shows, the size and alignment of your teeth, and how your lips move when you smile. Changing any one of these can noticeably reshape your smile, and most people benefit from addressing one or two specific issues rather than overhauling everything at once.
What Determines Your Smile Shape
A balanced smile generally shows the full length of your upper front teeth with just a sliver of gum tissue visible between them. The upper lip ideally reaches the gum line, and enough back teeth are visible to fill the space between your teeth and the corners of your mouth. In practice, most people display teeth only as far back as their second premolars, while smiles rated the most attractive tend to show teeth all the way to the first molars, something only about 4% of people naturally do.
There are also natural differences between men and women. Women’s upper lips sit about 3mm shorter at rest and rise slightly higher when smiling, which means they show nearly twice as much tooth as men do even before smiling. About 1 to 2mm of visible gum tissue during a full smile is considered normal for women. These averages matter because they help a dentist or orthodontist identify what’s actually “off” about your smile rather than guessing.
Widening a Narrow Smile
If your smile looks narrow or you notice dark gaps between your back teeth and the corners of your mouth (sometimes called buccal corridors), the issue is usually a narrow dental arch. Widening the arch pushes your teeth outward so more of them are visible when you smile, filling in those shadowed gaps.
In children and teens, palatal expanders achieve this by physically widening the bone of the upper jaw. Research on young patients shows that skeletal expansion produces significantly greater and more stable widening than aligners alone, with measurable increases in the distance between the canines and between the molars. Clear aligners can also widen the arch, but they do so by tipping teeth outward rather than moving bone, which limits how much change is possible and how long it lasts.
For adults whose jaw bones have fused, traditional palatal expanders don’t work without surgical assistance. Surgically assisted rapid palatal expansion (SARPE) or newer mini-screw-assisted expanders can achieve true skeletal widening in adults. Clear aligners and braces can still make modest improvements by repositioning teeth within the existing bone, but the results are smaller. If your arch is significantly narrow, an orthodontist can tell you whether you need skeletal expansion or whether tooth movement alone will be enough.
Fixing a Gummy Smile
Showing too much gum when you smile has several possible causes, and the right fix depends on which one applies to you.
- Excess gum tissue covering your teeth. A condition called altered passive eruption means your gums never receded to their normal position as your teeth came in. Gum contouring (gingivectomy) trims away the extra tissue with a scalpel or laser, revealing more tooth surface. It costs roughly $200 to $400 per tooth, and recovery takes about a week. Most people return to work within a day or two, with swelling and sensitivity fading in three to four days. You’ll eat soft foods and brush gently around the area while it heals.
- A short or hyperactive upper lip. If your lip pulls up too high when you smile, small injections of botulinum toxin can relax the muscles that elevate it. In one study of 23 women, nearly all saw a visible reduction in gum display within two weeks. The effect lasts three to four months before you need another round, at roughly $400 per session. A more permanent option is lip repositioning surgery, which limits how far the lip can rise. That procedure ranges from $500 to $5,000.
- Excess jaw bone growth. Vertical maxillary excess means the upper jaw grew longer than normal, pushing the gum line lower. The only definitive fix is orthognathic (jaw) surgery, where a surgeon removes a section of bone and secures the jaw in a new position with small plates and screws. This is a major procedure costing $20,000 to $40,000 without insurance, but it produces dramatic, permanent changes to smile shape and facial proportion.
- Medication side effects. Certain drugs for seizures, high blood pressure, or immune suppression can cause gums to overgrow around the teeth. If this is the cause, your doctor may be able to switch your medication, after which the overgrowth often improves on its own or can be trimmed surgically.
Reshaping Individual Teeth
Sometimes the overall arch and gum line are fine, but individual teeth are chipped, uneven, or oddly shaped. Two common fixes address this: composite bonding and porcelain veneers.
Composite bonding uses tooth-colored resin applied directly to the tooth surface. It requires little to no removal of your natural enamel, can be done in a single visit, and costs $100 to $400 per tooth. The trade-off is durability. Bonding typically lasts 3 to 7 years before it chips, stains, or loses its shine.
Porcelain veneers are thin shells cemented over the front of each tooth. They require shaving a small layer of enamel so the veneer sits flush, which makes the process irreversible. Veneers cost $925 to $2,500 per tooth and last 10 to 15 years or longer with good care. A full set covering 16 to 20 teeth runs $15,000 to $40,000. Because of the cost and permanence, many people start with bonding on one or two teeth to see if the change is worth committing to veneers long-term.
Straightening Crooked or Crowded Teeth
Misaligned teeth change the shape of your smile by creating shadows, overlaps, and uneven edges. Traditional braces and clear aligners both correct this, and the choice mostly comes down to how complex your case is. Aligners handle mild to moderate crowding and spacing well. Severe crowding, significant bite issues, or cases that need teeth extracted generally respond better to braces.
Treatment typically takes 12 to 24 months, though minor cosmetic cases with aligners can finish in as few as 6 months. Beyond straightening, orthodontic treatment can also adjust how your teeth are angled, which affects how light reflects off them and how much tooth surface is visible when you smile.
Improving Smile Symmetry
An asymmetrical smile, where one side lifts higher or one corner doesn’t move as much, is usually caused by differences in muscle strength or nerve function on each side of the face. Facial exercises that target the weaker side are widely recommended, and practitioners suggest results can appear within 4 to 8 weeks of consistent practice. However, there is no strong clinical trial evidence proving these exercises produce reliable, lasting changes. They’re low-risk and free, so they’re worth trying, but set realistic expectations.
If asymmetry is significant, small amounts of botulinum toxin can be injected into the stronger side to balance how far each corner of the mouth rises. This creates a more even smile without surgery, though like all toxin injections, it needs to be repeated every few months. Structural asymmetry caused by uneven jaw growth or a past injury may require orthodontic treatment or surgery to fully correct.
Choosing the Right Starting Point
The most efficient approach is to identify the single biggest factor shaping your smile and address that first. If your teeth are straight but your gums dominate the picture, gum contouring alone can transform your smile in one appointment. If your gum line is fine but your teeth are narrow and crowded, orthodontics will do more than any cosmetic procedure. And if your teeth and gums are both in good shape but individual teeth are worn or chipped, bonding or veneers can handle the rest.
A cosmetic dentist or orthodontist can take photos and measurements of your smile at rest and at full width, compare them to established proportions, and pinpoint exactly what’s contributing to the shape you want to change. Many offices offer this evaluation as a free or low-cost consultation, and it prevents you from spending money on a procedure that addresses the wrong problem.