Craig-Hallum analyst Alexander Nowak notes that shares of Sientra finished up 9% on Monday after FDA approved four new styles of the company's silicone gel breast implants. It appears the approval is for two textured implants and two smooth implants, he adds. The analyst points out that the market has been concerned that FDA could remove all textured implants from the market, and views this as the de-risking event to kick-off a turnaround for the stock. Once FDA concerns are fully in the rearview, investors can redirect attention back to taking market share with a superior implant, he contends. Nowak reiterates a Buy rating and a $23 price target on the shares.