They don't call it a movie-star grin for nothing. When your face is plastered all over giant billboards it helps to have a gleaming set of perfectly white, straight chompers. You know, the kind you see in toothpaste commercials. For stars who weren't born with the perfect smile, a talented cosmetic dentist is just a phone call away. But for every set of pearly whites, there's a case of veneers gone wrong. We bring you the best and worst celebrity smiles.

Courtney Love

What "worst of" list would be complete without Kurt's missus? As if her scary sagging skin and skeletal frame weren't unappealing enough, Courtney Love went and got what AwfulPlasticSurgery.com calls "chiclet teeth." Sure, they're nice and white-an amazing feat considering their owner-but these chompers look completely unnatural. They enter the room two seconds before she does. Honey, why don't you spend some of that Nirvana money on getting them fixed?

Hilary Duff

A wholesome cutie like Hilary Duff can get away with a lot of things-even dating Joel Madden (ick)-but horsey veneers is not one of them. Fans, bloggers, and basically anyone with eyeballs reeled when the singer/actress revealed overly large veneers in 2005. The reason for the new teeth? According to TeenMusic.com, Hilary Duff explained, "My teeth aren't the strongest, and I kept chipping them on the microphone. One show, I literally spit half of my two front teeth out." Fortunately the Duffster is now sporting newly refined veneers that don't stick out of her head.

Regis Philbin

You've got to wonder how Kelly Ripa manages without sunglasses-Regis Philbin's veneers are so white, they're blinding. Dr. Kevin Frawley, a cosmetic dentist in Beverly Hills, told FoxNews.com that, "When somebody's teeth jump out and seem like a night light in a dark room, that's porcelain veneers or crowns. The Regis Philbin Chicklet look, that opaque white that looks ridiculous, you're not going to get that with bleaching." It's not Reege's teeth aren't nice and straight; they're just unnaturally white, and that's just not right.

Eva Longoria

Okay, okay, hear us out. Sure, this tiny "Desperate Housewife" looks gorgeous, but have you ever taken a close look at her teeth? Eva Longoria could gnaw down a tree with those bucktooth babies! People just don't notice because a) she's incredibly hot, and b) her veneers are otherwise okay. Even the dentists agree. Steven Lorentzen told MSPMag.com that, "Because it's symmetrical, her smile looks good, but it's not something that we would strive to accomplish as cosmetic dentists. Her two front teeth are very prominent, but for her, they work." At any rate, she's still the cutest chipmunk in the (Holly)woods.

Kirsten Dunst

Kirsten Dunst doesn't have veneers, but she definitely needs them. Just ask cosmetic dentist Ned Windmiller, who told MSPMag.com that, "She could use some cosmetic dentistry. Her laterals-the teeth on the side-project too much." In other words, we think Kiki went a bit overboard when preparing for her role as a child vampire in Interview with a Vampire. No wonder she smiles so rarely.

Gary Busey

Most of Hollywood was surprised that Gary Busey was passed over for the lead in Seabiscuit, considering his too-bright, too-big teeth should have made him a shoo-in. Even more appalling is their banana yellow hue (ever heard of White Stripes, Gary?). Whether those chompers are the result of veneers or just plain bad luck is anyone's guess.

Michael Douglas

It looks like Michael Douglas has been chugging bleach-or investing in veneers-judging by the radioactive white glow emitting from his mouth. According to The Daily Mail, "Earlier pictures of Michael Douglas's teeth show them to be a little uneven in size and nowhere near as white as they are now." His teeth are more even now, but the overall result is unnatural and has less character, which must be a detriment to his acting career.

BEST CELEBRITY SMILES

Jessica Simpson

It's rumored that this Southern belle has had veneers and/or bonding, and judging by her mega-watt smile, we'd believe it. The brightness of Jessica Simpson's smile suits her bubbly personality and looks age-appropriate. Overall, her amazing teeth are disarming, not fake-looking.

Tom Cruise

He's got one of the best smiles in the business, but the teeth themselves weren't that great. And who can forget the braces he sported a few years back? Sure, metal mouth is a bit humiliating, but the hard work paid off. Says The Daily Mail, "Tom appears to have had just about everything done. One of his top teeth used to be noticeably bigger than the other and he has definitely had work done on his upper teeth to straighten, whiten and reposition them." So, just so we're clear, psychiatry bad, cosmetic dentistry good? Gotcha.

Carol Burnett

Forget dentures. Whenever Carol Burnett wanted a smile makeover (her originals were a bit, um, tragic) she headed to the cosmetic dentist's office. "Carol Burnett has had some veneers and crowns," says dentist Ned Windmiller told MSPMag.com. "Whoever did it did a great job. They look very appropriate for her age." The new teeth are bright but not overwhelmingly so, and look perfectly even; they suit Burnett's large mouth very well.

Matt Damon

For a guy with an incredible smile, Matt Damon sure does play a lot of all-business characters. That's a shame, because Damon's just-right-white, perfectly straight teeth are enough to send girls swooning. According to BeautyNewsNYC.com, Damon gets a little help from celebrity cosmetic dentist Dr. Larry Rosenthal. How do you like them apples?

Kate Beckinsale

It's not uncommon for British actors and actresses to pay a little visit to the dentist before making it big here in the States. Case in point: Kate Beckinsale, who, according to Handbag.com, sports a lovely manufactured smile. The site quotes Dr. Tim Bradstock-Smith, founder of the London Smile Clinic, who said, "She appears to have had a gum lift and veneers." Now what about those enlarged breasts?

Halle Berry

Who can resist these pearly whites? Says dentist Ned Windmiller to MSPMag.com: "In a smile design, we try to aim for a smile like hers. The top edge of the teeth follow the contour of her upper lip, while the biting edge of the teeth follow the contour of her lower lip. The shape and color are very natural looking, translucent. Her two front teeth are dominant and symmetrical." We'd love to get the number of Halle Berry's cosmetic dentist.