Jennifer Aniston: The sex-mad dentist will see you now

After years of playing Rachel in Friends, followed by a never-ending stream of formulaic rom-coms, Jennifer Aniston tells Gill Pringle she has found a new drill

In the wake of a handful of deftly delivered crude remarks, Jennifer Aniston has changed her career around. After languishing for years in the doldrums of lacklustre romantic-comedy fare, with Horrible Bosses she has seized the opportunity to demonstrate once again that she's not just a pretty face, she's a fine comedienne too. As I talk to Aniston today, she is buzzing with energy, loving the attention she's getting for playing a lascivious dentist who pumps her patients with gas so she can have sex while they sleep in the chair. It's a character so very far removed from Rachel, whom she played for a decade in TV's Friends, and all those repetitive cutesy roles that followed; Just Go With It, The Switch, Love Happens and The Bounty Hunter in the space of the past two years alone.

"I've never played a character so inexcusably raunchy and there was no way I could resist it," she admits. "The dialogue and the situations are so outrageous and fun. I jumped at it immediately. It really stretches the limits and crosses boundaries and Dr Harris is way out in front on all counts: guilty as charged."

Horrible Bosses is her best role in years – a potty-mouthed man-eater in an all-star ensemble comedy in the same vein as Bridesmaids or Hangover. She has also, cleverly, aligned herself with a calibre of actor that tends to elevate this kind of R-rated comedy, namely Kevin Spacey, Colin Farrell and Donald Sutherland.

If many actresses would run screaming from a script that demanded she simulate oral sex with a banana, a popsicle and a hot dog, instead she laughs saying, "yeah, that was a proper meal!" And on breaking the ice with her co-star Charlie Day, the victim of her character's sexual harassment, she says: "I've never been on a set like this – within 20 minutes, I was straddling him in lingerie. I was bizarrely comfortable in these scenes, almost more than I would be playing the normal girl-next-door, and every scene was kind of crazy but that was really the fun of it," says the actress who doesn't wear just any dental coat; she is clad in a short, tight couture coat beneath which she's either topless or flaunting expensive lingerie.

She agrees that she's basically satirising male sexual behaviour for her latest screen incarnation. "That's what I think was so fun about it, sort of being a female that's usually the male character. I thought of her as kind of like a guy and that made it that much more fun." Certainly she can relate to the role of a sexually confident woman. "Are men intimidated by sexually confident women?" she muses. "Yes, I think that men are intimidated by any woman who's sexually confident, no matter what age.

"I think getting older means you get more comfortable in your body and in your skin and who you are and you have more of a 'fuck it' attitude. You're so careful and controlled in your twenties and you're just more aware of your every move. Now, I think there's just more of a freedom and a comfort and none of it really matters as long as you're enjoying yourself and having a really good time."

For a while Aniston, 42, clearly wasn't having a good time, particularly in the aftermath of the departure of her husband Brad Pitt, six-and-a-half years ago, who left her for Angelina Jolie, giving rise to years of "Poor Jen" tabloid headlines and tiresome theses on "the woman scorned". Then there were the doomed relationships with Vince Vaughn, John Mayer, Gerard Butler and male model Paul Sculfor.

Today she has hitched her wagon to actor-writer-director Justin Theroux, 39, nephew of the noted travel writer and author. On her wedding finger she wears a much-talked about gold ring and matching watch identical to that worn by Theroux, whom she met last year on the set of their upcoming comedy Wanderlust, although he is only now going public after he untangled himself from a long relationship with a previous girlfriend.

Under the guidance of Theroux, Aniston has grown in confidence in other aspects of her life, taking control of her own destiny by finally tackling the many projects her film company has on hold for development.

She has long wanted to make The Goree Girls, a 1940s-set musical centered around a group of incarcerated female Country-and-Western performers, and now is in earnest talks to finally get that project moving with a slated 2013 release date.

She also recently stepped into the director's seat to shoot a TV film, Project Five, an anthology of five short films exploring the impact of breast cancer on people's lives, with Demi Moore and Alicia Keys directing other segments, and actress friend Patricia Clarkson featuring in her portion.

Project Five is slated to air in the US in October, breast-cancer awareness month, with distribution rights to other countries still under discussion.

"I actually love the directing experience because, having been acting for as long as I have, I've been observing for so many years," she says. "It was fun to discover how much you actually know even not having gone to a film school of any sort. There's an instinct from just being around it as many years as I have so I enjoyed it."

While audiences might be surprised to discover Aniston's sex-maniac alter-ego in Horrible Bosses, director Seth Gordon never had any doubts she could deliver. "Aniston is one of the greatest comediennes around. She's just not recognised as that, as evidenced by the roles she's offered," he says.

Among a litany of smutty remarks, there's one memorable line where her character talks about "fingering herself while watching Gossip Girl's Penn Badgley on TV". "She actually didn't know who he was but she said it faithfully anyway," recalls the director. "There were a couple of other dirty lines that followed that I think will be in the DVD. Between takes she'd work with her acting coach Leigh Kilton Smith, constantly suggesting new lines. I think it was Jen who came up with the line, 'I bet he's packing a plus-size sausage in those True Religions'."

Suggest her new film may be too raunchy for the folk at Smart Water, whose product she endorses, and she agrees. "Sure, there's always that, but that's the fun. You don't want to play it safe all the time, and I've never had a script that's come to me that's allowed me to go into this direction. So it was a great opportunity and I don't think that I really cared if there was sort of a bad reaction to it. I actually didn't think there would be. I really just thought that it'd be fun for everybody, or I would hope," she says.

Almost more of a controversy than the raunchy dialogue was her determination to dye her hair dark brown for the character, something she now jokingly describes as "Hairgate".

"The studio didn't want me to do it," recalls the actress, who enlisted her long-time pal and hair guru Chris McMillan to create a startlingly different look. Her Horrible Bosses director readily supported her decision, saying: "The goal was to give her a new look that we hadn't seen before. At first the studio was scared because it was such a departure from how they knew her and they were worried that the look would overwhelm the character. But I'm really glad they came around because I think its wonderful; she looks great and it's a way we haven't seen her before, in the best possible way." All nice work for a five-day shoot for which she was apparently paid US$6m.

The popular media calls her "Jen" but her closest friends refer to her as Aniston. "There's so many damn Jennifers out there," says Gordon. "So I think calling her Aniston is almost a sign of being one of the guys, like in a sports team where everyone is called by their last name. It's a flattering thing; it means she's one of the guys."

Aniston is coy when asked whether part of the appeal of her new role was to escape being branded as "America's sweetheart". "No. I didn't take the role so that I could sort of rid myself of that title. I don't know where that even came from. There's so many different American sweethearts... So, that's a label. You're branded. There's always going to be something attached to you, just sort of for..." she stops short of all the other things she's been known for over recent years, like the poster girl for the beautiful woman who has everything but love.

Her previous attempts at changing career direction have largely been met with lukewarm responses, such as when she co-starred with Clive Owen in 2005 thriller Derailed. And while she received critical applause for her 2002 indie film The Good Girl, she has rarely strayed far from the formulaic studio-romantic-comedy fare for which she's guaranteed a big cheque.

For many years now, she has had the luxury of being her own boss, running her own production company, Echo Films. "I'm always a very nice boss to myself. My philosophy is to create a positive work environment. If you're gonna kill 'em, you've gotta kill 'em with kindness," says the actress, who has kept the same tight-knit group of colleagues around her for years.

"I think women are just becoming stronger and being given more power. They're not barefoot and pregnant in the kitchens anymore. That started in the late Sixties and Seventies with Helen Gurley Brown. I think it's been a progression of women empowering themselves. I don't know if I'd use the word 'aggressive', because that sort of has a negative connotation to it. I think women are just strong. I'm sure there are men that may have a problem with that...but I think we're all becoming very equal."

But she'd be naive to imagine that Hollywood is anywhere close to being an equal-opportunity business, saying: "In comedies, it's very rare to get a great female comedy role. I mean, it's all the big boys. It's all usually male-driven – Adam [Sandler], Ben Stiller, Jim Carrey, you know. That's where the comedy is. I'm just happy that they wrote a strong woman for me with this."

'Horrible Bosses' opens on 22 July