What Causes Crooked Teeth: 8 Reasons, Prevention, Treatment
Crooked teeth are common—and not just a cosmetic concern. When teeth don’t line up, they’re harder to clean, can wear down unevenly, and may strain your jaw. You might notice food getting trapped, gums that bleed more easily, headaches from clenching, or a bite that just doesn’t feel right. For kids, crowding can shape how adult teeth come in. For adults, shifting can creep up after braces, an injury, or even years of normal aging. If you’re wondering why your teeth (or your child’s) are moving and what you can do about it, you’re in the right place.
This guide breaks down the eight most common causes of crooked teeth—what they are, how they lead to misalignment, and what you can realistically do to prevent further shifting. You’ll get practical tips for home care, signs it’s time to see a dentist or orthodontist, and an overview of treatment options, from retainers and clear aligners to braces and surgical solutions when needed. We’ll also cover how to keep teeth straight after treatment so your results last. Let’s start with the most overlooked reason: post-orthodontic relapse when retainers aren’t worn.
1. Post-orthodontic relapse (not wearing a retainer)
What it is
Post-orthodontic relapse is the tendency for teeth to drift back toward their original positions after braces or aligners. Orthodontic treatment moves teeth through bone; once the hardware comes off, a retainer maintains that new alignment while tissues stabilize. Skip the retainer, and the natural forces in your mouth start pulling teeth out of line again.
How it leads to crooked teeth
Chewing, swallowing, and even subtle tongue and lip pressures constantly nudge teeth. The fibers around teeth and the bite relationship have a “memory,” so without a retainer holding the position, gaps can reopen, crowding can return, and rotations can relapse. Over time, this shifting shows up as crooked teeth, a bite that feels off, or increased plaque trapping between newly crowded teeth.
Prevention tips
Staying straight is a lifelong habit. Think of your retainer like a seatbelt for your smile—simple protection that prevents big problems.
- Wear as directed: Follow your orthodontist’s schedule; many people need nighttime wear long-term to prevent relapse.
- Replace when needed: Lost, cracked, or loose retainers don’t hold teeth. Get a new custom retainer promptly.
- Store and clean properly: Use a ventilated case and clean daily to avoid warping or bacterial buildup.
- Schedule check-ins: Periodic fit checks catch early movement before it becomes visible crowding.
Treatment and when to see a dentist
If your retainer feels tight, doesn’t seat fully, or you notice new crowding, see your dentist or orthodontist. Mild relapse may be corrected with a new retainer or a short clear-aligner “touch-up.” Moderate to severe shifting may require limited braces or aligners. Seek care sooner if you have bite changes, jaw discomfort, or a broken/warped retainer—early intervention keeps treatment simpler and shorter.
2. Genetics and growth factors (jaw size, tooth–jaw mismatch)
What it is
Genetics strongly influence jaw size and shape, tooth size and number, and how and when teeth erupt. Research also suggests modern, softer diets are linked with smaller jaws over time. That combination can create a tooth–jaw mismatch—normal or large teeth in a smaller jaw—or inherited bite patterns like overbite or underbite, all of which raise your risk for crooked teeth.
How it leads to crooked teeth
When the jaw is too small for the teeth, they compete for space, rotate, overlap, or erupt out of line. Large or extra teeth crowd neighbors; missing teeth can let others drift. Misaligned upper and lower jaws change how the arches meet, leading to overbite, underbite, or crossbite, which further tips and shifts teeth as you chew and swallow.
Prevention tips
You can’t change your genes, but you can guide growth and reduce compounding risks.
- Prioritize nutrition: A balanced diet supports normal dental and jaw development, especially in kids.
- Manage habits early: Thumb sucking, tongue thrusting, and mouth breathing can worsen a genetic crowding tendency.
- Monitor growth: Regular dental checkups in childhood help spot spacing and eruption issues before they escalate.
- Consider interceptive care: In select kids, appliances like a palatal expander can create room for incoming adult teeth.
Treatment and when to see a dentist
Crowding, teeth that twist as they erupt, or a bite that doesn’t feel right are cues to book an exam. Options include:
- Braces or clear aligners: To align teeth and improve bite relationships.
- Palatal expander (kids): To widen a narrow upper jaw and make space.
- Targeted extractions: When extra or oversized teeth block alignment.
- Orthognathic surgery: For significant jaw discrepancies affecting function.
After alignment, long‑term retainer wear helps maintain results and prevents relapse from normal daily forces.
3. Myofunctional habits (thumb sucking, pacifiers, tongue thrusting, mouth breathing)
These everyday behaviors use gentle but persistent forces that reshape growing mouths and can destabilize an aligned smile. If you’re asking what causes crooked teeth beyond genetics, myofunctional habits are a big, fixable driver—especially in kids, but they matter for adults too.
What it is
Myofunctional habits are repetitive patterns of muscle use involving the lips, cheeks, tongue, and jaw. Common examples include thumb or finger sucking, prolonged pacifier or bottle use, tongue thrust when swallowing, and chronic mouth breathing. Over time, these patterns influence how teeth erupt and how the jaws grow and meet.
How it leads to crooked teeth
Thumbs and pacifiers press the upper front teeth forward and can narrow the upper arch. Tongue thrust places the tongue against the teeth instead of the palate, pushing incisors outward and contributing to an open bite. Mouth breathing lowers tongue posture, lets the cheeks press inward, and can narrow the upper jaw—setting the stage for crowding, crossbites, and misaligned bites.
Prevention tips
Stopping the habit early and restoring healthy tongue and lip posture reduces the risk of crooked teeth and bite problems.
- Phase out oral soothers: Transition away from pacifiers/bottles as soothing alternatives work to avoid prolonged pressure on front teeth.
- Promote nasal breathing: Treat allergies/congestion and practice lips‑together, tongue‑to‑palate rest posture.
- Address tongue patterns: Myofunctional therapy can retrain swallowing and resting posture.
- Monitor growth: Regular dental checkups catch arch narrowing, flaring, or open-bite changes early.
Treatment and when to see a dentist
See a dentist or orthodontist if you notice flared front teeth, an open bite when the back teeth touch, mouth breathing, snoring, or a lisp. Care may include habit‑breaking reminder appliances, myofunctional therapy, and, when needed, orthodontics such as clear aligners/braces. In children with a narrow upper jaw, a palatal expander can create space to reduce crowding and help normalize the bite. Retainers help maintain results once habits are corrected.
4. Malocclusion and poor jaw alignment (overbite, underbite, crossbite, open bite)
What it is
Your bite (occlusion) is how upper and lower teeth meet. Ideally, upper teeth slightly overlap lower teeth and the points of upper molars fit into the grooves of lowers. Malocclusion is any deviation from this alignment and is a core answer to what causes crooked teeth because it alters how forces act on teeth over time. Common types include:
- Overbite: Upper front teeth overlap the lowers more than normal.
- Underbite: Lower front teeth sit in front of the uppers.
- Crossbite: Some upper teeth bite inside the lowers.
- Open bite: Front or back teeth don’t touch when you close.
How it leads to crooked teeth
When jaws or arches don’t align, chewing and swallowing load teeth unevenly. Those imbalanced pressures nudge teeth to rotate, tip, crowd, or drift into gaps. Crossbites can narrow arches and trigger asymmetric wear; open bites invite tongue pressure that flares incisors; deep overbites and underbites drive ongoing shifts and can strain jaw joints—compounding crowding and spacing over time.
Prevention tips
You can’t always prevent jaw-size differences, but you can limit their impact—especially in growing kids.
- Early orthodontic screening: Identify developing overbites/crossbites before they set.
- Address habits and airway: Correct thumb sucking, tongue thrust, and mouth breathing that worsen bite issues.
- Protect alignment: Maintain routine dental care and wear retainers as directed after treatment to prevent relapse.
- Monitor eruption: Track space for incoming teeth to reduce crowding risk.
Treatment and when to see a dentist
Seek an evaluation if biting/chewing is difficult, teeth don’t meet evenly, you see midline shifts, notice speech changes, or have jaw soreness. Care may include:
- Braces or clear aligners: To straighten teeth and coordinate the bite.
- Elastics and auxiliaries: To fine‑tune jaw-to-jaw relationships.
- Palatal expander (kids): To widen a narrow upper jaw and correct crossbites.
- Selective extractions: When crowding blocks alignment.
- Orthognathic surgery: For significant jaw discrepancies affecting function. Long‑term retainer wear helps keep a corrected bite—and teeth—stable.
5. Gum disease and tooth loss from poor dental care
When people ask what causes crooked teeth beyond genetics, poor dental care is a major factor. Skipping checkups and daily cleaning raises the risk of gum disease and cavities. Left untreated, gingivitis can progress to periodontitis—a deeper infection that damages the bone and tissues supporting your teeth—making them loosen, shift, or even fall out.
What it is
Gingivitis is inflammation of the gums from plaque buildup. Periodontitis is the advanced stage, where infection breaks down the bone and ligament around teeth. Cavities and untreated decay can also lead to infections and extractions that disrupt your bite.
How it leads to crooked teeth
As periodontal disease erodes support, teeth become mobile and migrate under everyday chewing forces. Gaps widen, teeth tip or rotate, and your bite collapses unevenly. When a tooth is lost, neighboring teeth drift into the space and the opposing tooth can over-erupt—creating crowding, new spaces, and misalignment.
Prevention tips
Daily care and routine dental visits keep gums healthy and teeth stable.
- Brush and clean between teeth: Floss or use interdental tools to remove plaque where brushes can’t reach.
- See your dentist regularly: Professional cleanings catch and treat gingivitis before it turns into periodontitis.
- Treat decay early: Prompt fillings prevent infections and extractions that trigger shifting.
- Protect your bite: Manage clenching/grinding and wear retainers as directed to maintain alignment.
Treatment and when to see a dentist
If your gums bleed, look puffy, or you notice bad breath, loose teeth, or new spaces, book a visit. Treatment may include professional cleanings, scaling and root planing (deep cleaning), and restoration of decayed teeth. Replacing missing teeth helps prevent drifting, and orthodontics (braces or clear aligners) can realign teeth once gum health is stabilized. Early care keeps treatment simpler and preserves bone and tooth support.
6. Early loss of baby teeth and childhood decay
Ask any pediatric dentist what causes crooked teeth in kids, and early loss of baby teeth ranks near the top. Baby teeth aren’t “extras”—they’re placeholders that guide adult teeth into position. When decay or trauma takes a baby tooth too soon, the entire arch can start to shift.
What it is
Early loss means a primary (baby) tooth falls out or is removed before its natural time, often because of cavities or injury. Without that placeholder, nearby teeth begin to move, and the path for the permanent tooth changes.
How it leads to crooked teeth
Once a gap opens, neighboring teeth drift into it. That steals space from the incoming adult tooth, which may erupt rotated, crowded, or out of line. Premature loss can also contribute to crossbites or open bites by altering how the upper and lower arches grow and meet—problems that become harder to fix later.
Prevention tips
A few consistent habits greatly reduce childhood decay and protect those critical placeholders.
- Daily cleaning: Brush with fluoride toothpaste twice a day and clean between teeth to remove plaque in tight spots.
- Smart nutrition: Limit sugary snacks and drinks; choose balanced meals that support normal tooth and jaw development.
- Routine checkups: Regular dental visits catch small cavities early and monitor spacing and eruption patterns.
- Curb harmful habits: Address thumb sucking, tongue thrusting, and mouth breathing early so they don’t compound spacing issues.
Treatment and when to see a dentist
If a baby tooth comes out early—or a cavity is suspected—schedule a visit promptly. Your dentist will treat decay, monitor eruption, and, if needed, recommend interceptive orthodontics (for example, expansion in a narrow upper jaw) to preserve room and guide adult teeth. If crowding or bite changes appear, limited braces or clear aligners can realign teeth; long‑term retainer wear helps keep the new position stable.
7. Facial trauma and injury
Accidents happen—on the field, at the gym, on the stairs, or in the car. A blow to the mouth or jaw can chip, loosen, or knock out teeth and even shift the bone that supports them. Because trauma applies sudden force, it’s one of the fastest ways crooked teeth and bite changes can appear.
What it is
Facial trauma includes any impact to the teeth, gums, jawbone, or surrounding tissues from sports injuries, falls, or collisions. Damage ranges from chips and cracks to displaced teeth and jaw fractures, all of which can alter how teeth line up.
How it leads to crooked teeth
Injured teeth may loosen and migrate under everyday chewing forces. If a tooth is lost, neighbors drift into the space and opposing teeth over‑erupt, creating crowding and new gaps. Significant impacts can also change how the upper and lower arches meet—leading to misaligned bites that nudge teeth further out of position over time.
Prevention tips
Simple precautions lower the risk that trauma turns into long‑term misalignment.
- Wear an athletic mouthguard: Especially for contact or high‑impact sports.
- Use seatbelts and helmets: Reduce facial injuries from crashes and falls.
- Don’t use teeth as tools: Avoid opening packages or bottles with your teeth.
- Get checked after any impact: Early evaluation catches subtle loosening or bite changes.
Treatment and when to see a dentist
See a dentist or emergency provider right away if a tooth is moved, loose, fractured, or missing. Care may include repositioning and splinting injured teeth, repairing cracks, and stabilizing the bite. After healing, orthodontics (clear aligners or braces) can realign shifted teeth, and replacing missing teeth helps prevent further drifting. Retainers maintain the corrected position once treatment is complete.
8. Aging, wisdom teeth, and natural tooth shifting
What it is
Teeth aren’t fixed in cement—they respond to subtle forces for life. As we age, bone remodels more slowly and can thin, the gum attachment changes, and daily chewing and clenching keep applying pressure. Around the late teens to 20s, wisdom teeth may erupt; if they’re misaligned or impacted, they can complicate spacing and gum health even when they don’t need removal.
How it leads to crooked teeth
Age-related changes can narrow arches slightly and make lower front teeth crowd or overlap. Any loss of bone support from gum disease accelerates mobility and drifting. Problematic wisdom teeth can inflame gums, trap plaque, or push on neighbors, contributing to bite changes or crowding in some people, while others have no issues at all.
Prevention tips
A few steady habits help keep aging and late eruptions from undoing your alignment.
- Wear your retainer at night: Long‑term retention counters natural drifting.
- Keep gums healthy: Daily interdental cleaning and regular checkups reduce bone loss and shifting.
- Control clenching/grinding: A custom night guard limits tooth wear and unwanted tooth movement.
- Monitor wisdom teeth: Periodic exams and X‑rays catch impaction, infection, or spacing problems early.
- Replace missing teeth promptly: Prevents neighbors from drifting into gaps.
Treatment and when to see a dentist
Book a visit if your retainer feels tight, you notice new crowding, your bite feels different, or you have jaw or gum soreness—especially around the back molars.
- Mild shift: New or adjusted retainer; short clear‑aligner “touch‑up.”
- Moderate/severe shift: Limited braces or aligners to re‑align and rebalance the bite.
- Wisdom tooth issues: Removal if there’s pain, infection, damage to neighbors, or crowding risk; monitoring if healthy and fully erupted.
- Gum treatment: Professional cleanings or deep cleaning first, then orthodontics once stability is restored.
Retainer wear after any correction keeps age‑related drift in check.
Key takeaways and next steps
Crooked teeth usually come from a mix of factors—genetics and jaw growth, myofunctional habits, bite misalignment, gum disease and tooth loss, trauma, and age-related changes. The good news: early checks, consistent home care, and the right appliances can prevent small shifts from becoming big problems. Most cases are manageable with retainers, aligners or braces, interceptive care in kids, and gum treatment when needed.
- Wear your retainer long‑term: Nightly use helps prevent relapse and age‑related drift.
- Fix habits and airway issues: Stop thumb sucking/tongue thrust and promote nasal breathing.
- Protect gum health: Daily interdental cleaning and regular cleanings stabilize teeth.
- Guard against forces: Use sports mouthguards and manage grinding with a night guard.
- Monitor growth and eruption: Early pediatric checkups catch spacing and bite issues fast.
- Act on warning signs: Tight retainer, new crowding, bite changes, gum bleeding, or trauma.
Ready to protect your alignment and comfort? Book a dental exam, then consider convenient, affordable custom retainers and night guards delivered to your door with an at‑home impression kit from Remi. Small moves today—retainer tonight, cleaning on the calendar, protection in place—keep your smile straight for the long haul.
