You may dread your regular check-up, but an historian says dentists themselves were stressed about their work until an Iowa invention changed the practice of dentistry forever. The new “100 Creations of the 20th Century” exhibit which opens at the State Historical Building in about two weeks features a remarkable invention: the Den Tal Eze chair. John Naughton came up with the idea for the chair and introduced it at the 1958 Iowa Dental Convention.Curator Jack Lufkin says Naughton’s chair let dentists sit while patients were stretched out in a reclining position. Prior to the invention, dentists did their work standing up, leaning over patients, and it led to a lot of backaches. Naughton’s chrome and leather prototype will be on display at the State Historical Building in the “A Few of Our Favorite Things” exhibit which opens December 16th.