Fellow Orthodontist - New York

In minor case, excess overjet (dental protrusion) can be resolved with filing between teeth to make some space. However, in more severe cases, in order to obtain noticeable improvement, extraction of premolars are often necessary. To get the best result, it is important that you communicate with your orthodontist how much improvement you would like to see. This will heavily influence if extraction will be recommended.

How soon the space closes will depend on how the teeth movement was designed initially. Normally you can notice space closing after several weeks. It may not completely close but it will become less noticeable. 

It seems like your primary goal is to make room for the restoration of the implant. From a patient's perspective, I can understand that it becomes frustrating when you have to go through extensive orthodontic treatment just to get an implant done. With that in mind, an ideal treatment for you is a limited adjunctive treatment focusing on creating room for the implant crown rather than trying to achieve ideal occlusion entirely. This can be effectively achieved by bonding braces on lower teeth only and creating space by performing interproximal reshaping of your teeth. In addition, minor reshaping of the incisal edges may be needed to ensure adequate vertical space for he implant crown. The adjunctive orthodontic treatment should be limited to no more than 4-6 months to avoid delay in your implant crown placement. Hope everything works out for you.

If the aligners are not fitting from the very beginning, it is likely either due to distortion during the initial record or a distortion during the manufacturing process. Invisalign does provide a warranty fit and your doctor can request remake of the first 2-3 aligners to see if the same distortion problem persists. If the fit is good for the new aligners, then you know the problem is in the manufacturing. If the new aligners have the same distortion, then you can rule out manufacturing defect and conclude that a distortion occurred during the records process and a new impression/scan has to be made. 

Sometimes if the current aligner does not seem to be fitting, it is an indicating that teeth have not moved as much as the aligner is designed to. In this case, going back a few aligners may be required. A weekly cycle is not an uncommon practice and is often done by many orthodontists. Teeth don't always follow the movement of the aligners 100% and often times a refinement (new impression and new set of aligners) is needed to get to ideal result.