The Iron Claw actor's appearance has changed somewhat over the years

    Ever since he burst onto the scene in in 2006, Zac Efron has been one of showbiz's biggest heartthrobs. And over the years, the 36-year-old has well and truly moved on from Troy Bolton and embraced the movie star lifestyle complete with a Hollywood glow-up.

    The star, who is due to appear in the upcoming comedy movie, has also been the subject of headlines about his appearance after reports began stating that he had cosmetic procedures, however, Zac was keen to stress this wasn't the case.

    But Zac, like many A-listers, has embraced his glow-up in other ways. HELLO! spoke to an expert about his transformation.

    Zac Efron's teeth transformation

    Leading cosmetic dental expert and celebrity dentist Dr Sam Jethwa of Bespoke Smile explained his verdict on thestar's changing smile over the years.

    "The first thing I notice when looking at the before pictures is the gap in between the two front teeth, which is called diastema. The gap is creating a slight illusion that his teeth are crooked, but they are actually fairly straight, apart from some minor overlapping on the upper right side."

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    Dr Sam added: "The shape of the four front teeth has changed, especially the front two which appear much wider and shorter in the before picture. We can also see that the smile in the after picture is symmetrical and incredibly neat."

    The Bespoke Smile boss also added that the 17 Again star probably underwent composite bonding. "[This] is non-invasive and involves the application of a tooth-coloured composite resin to the surface of the tooth, which is then shaped and polished."

    Hollywood glow-up

    A killer-watt smile is commonplace in Hollywood, but part of Zac's charm is how he manages to flash his pearly whites while still looking natural.

    "If not composite bonding, Zac may have had ultra-thin veneers on the upper front four teeth, we can see the shape of the canine teeth remain the same. His new smile is natural, and in keeping with his facial features," said Dr Sam.

    "The pictures suggest that Zac has had teeth whitening, due to the brighter pantone. Teeth whitening is now a popular and safe treatment where we use peroxide gels or lasers to brighten and whiten your teeth."

    Not only has Zac brightened his smile, but the actor has also sported many different hairstyles over the years and, most notably, built up quite the physique, especially for his most recent role in The Iron Claw.

    What Zac Efron has said about his transformation

    But the star has been forced to address his changing appearance in recent times.

    Fans were convinced that Zac had undergone facial plastic surgery after his jawline changed in shape and definition, however, he explained in a candid interview with Men's Health that this was the result of undergoing a procedure following a freak accident at home.

    Sharing details of his shocking injury, Zac explained how he slipped on a pair of socks while running at home and crashed into a granite fountain, causing him to shatter his jaw.

    Zac lost consciousness before eventually waking up with "his chin bone hanging off his face."

    The actor recalled the traumatic healing process during which his muscles swelled to an abnormal size. "The masseters just grew. They just got really, really big," he said.

    During his press tour for, Zac also opened up to ET about his physical transformation to portray wrestler wrestling star of the 1980s, Kevin Von Erich.

    This movie's a true story, and that man, Kevin Von Erich right there, he really motivated me to get in shape for this movie," adding: "The physicality he brought to the ring every single day was really unique. It changed wrestling."

    He went on: "I knew that was going to be the hardest [thing] for me to master and get right. So, I put everything I had into it," and confessed: "It was shocking at every point of the transformation."

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