Cheek and lip retractors come in two basic styles: self-retained or manual. Each type offers advantages and disadvantages, depending on the reason you are using them in the first place. For photography, the manual retractors are usually better, since they allow you to customize how they are being used. For example, with manual retractors, you can increase the retracting pressure on one side to get a more complete shot while easing up on the other side. They are also more indicated when you want to retract more of the upper lip than the lower or when you are taking occlusal views.
On the other hand, self-retained retractors are much more effective when power bleaching, since you need consistent and reliable retraction during the entire procedure, which may last up to an hour. Seating porcelain veneers can also be more efficient when this type of retractor is used. If you provide power bleaching or seat multiple porcelain veneers all at once, these retractors will come in handy. Otherwise, they may take up residence in one of your storage drawers.