The short answer is, about 12-18 months   .

The long answer is, it depends. How long you continue treatment is dependant on a few factors. 

If your teeth are very crooked or crowded, it may take longer to complete the treatment. But, if your teeth are not terrible, treatment could take less than a year. 

Another factor is your ability to keep up your appointments and wear time. On average, you should be wearing your aligners 22 hours a day and have checkups every few weeks so the orthodontist can give you a new set of aligners. If you do not wear your aligners for the allotted time and skip appointments, your treatment will be lengthened. 

Gaps in your teeth are another reason people are hesitant to smile. Closing gaps with Invisalign is simple if the gaps are small, but may take more time if they're significant. 

Following all your orthodontist recommendations and instructions will result in a straighter smile. 

In some cases, if your case is too severe your orthodontist might recommend a different treatment option. 

The great thing about Invisalign is that it's perfect for both adults and teenagers. Overall, there's no difference in Invisalign treatment time for adults and teenagers. For some teenagers, treatment takes longer, but this may be due to forgetting to reinsert the aligners. 

There are many benefits to Invisalign. First, they are completely removable, which means that you can take them out while eating, brushing your teeth, and so forth. This improves the health of your teeth because you're able to reach all the crevices, keeping your teeth free from disease-inducing plaque. 

Second, because the aligners are made of plastic, many people do not even notice you have them. This can be perfect for those who are already self-conscious about their smile.

Overall, they're fairly comfortable to wear. There might be an adjustment period once you first try them on, but once you get used to them, they become like second nature. If you do experience any discomfort from your aligners, let your orthodontist know so they can make proper improvements.

If you're reckless with Invisalign liners, like leaving them on the bathroom counter or not placing them back in their case, chances are they might break. But if you're careful and take good care o them, they will last. 

While traditional braces are needed for some cases, when compared to Invisalign, there are a few important differences. 

Traditional braces are made of metal brackets and wires and can irritate the gums and lining of the cheek reasonably easily. Also, brushing is a little more challenging, because you have to navigate around the wires and brackets. If you skip brushing or brush poorly, food particles can create plaque on your teeth which can lead to cavities and other dental problems. 

When you see your orthodontist for adjustments, they can be a bit painful and intrusive. Although, the depends on the level of treatment you're receiving due to your case. 

Usually, with Invisalign, there are no food restrictions because you can remove the aligners before meals. With traditional braces, certain foods that are sticky or hard are off-limits due to the damage they might cause the brackets. 

Traditional braces may also pop off of your teeth, in which you'll have to contact the orthodontist to resecure the bracket or reattach the wire. This can add time to your treatment plan and may be considered a dental emergency. 

Generally speaking, if your dental issues are not complicated, Invisalign would be a great treatment. If you have larger problems that need correcting, your orthodontist will suggest a different treatment route. Either way, your orthodontist is in your corner and committed to helping you achieve the smile you want.