AceShowbiz -

Has Shania Twain gone under the knife? The 51-year-old Canadian singer sparked rumors she had plastic surgery done after she made an appearance as a guest mentor on "The Voice". Despite her age, she looked so different that many wondered if she had work done on her face.

Twain's face now looks a lot fuller and plumper than it did in her 30s. Weighing in on the "You're Still the One" hitmaker's look, two N.Y.C.-based doctors revealed to Life & Style what kind of procedures she could have undergone to maintain her youthful appearance.

"Shania's eyebrows have maintained their nice elevated arch, and her forehead looks smooth and natural," dermatologist Dr. Kenneth Mark said, before crediting Botox for her look. "Injections of Voluma have seemingly lifted her cheeks. The excellent placement was subtle - avoiding an overly plumped look," Dr. Mark added. "Such a youthful angular jawline points to Ultherapy."

Meanwhile, plastic surgeon Dr. Yoel Shahar observed, "She appears to have filler under her lower eyelids to maintain her youthful look," before adding, "She's also likely had Botox to her crow's feet." The two doctors suggested that Twain had regular Botox and filler injections and also underwent a nonsurgical treatment using ultrasound waves to tighten and tone skin.