The Invisalign treatment is designed just to straighten teeth but its clinical success is underpinned by the condition of the natural teeth to start with. Tooth decay causes cavities which may lead to tooth loss if left untreated which can detract from the quality of the smile both you and your orthodontist are striving to achieve. Your dentist and/or orthodontist would normally advise that your cavities be treated prior to the application of your Invisalign tooth aligner to ensure the best chance of both functional and aesthetic success can be realised for the sake of your continued good oral health.