Before Ash and Ramfjord, many dentists believed that "ideal occlusion" was purely about mechanical alignment (cusps fitting perfectly into fossae). Ash and Ramfjord shifted the profession's focus to . They proved that teeth can look "imperfect" on a model but function perfectly in a living patient without causing pain or damage.

: Unlike static definitions that only look at how teeth fit together when closed, Ash and Ramfjord focused on opening and closing movements during mastication.

"Occlusion" by Sigurd P. Ramfjord and Major M. Ash is a foundational dental textbook focusing on the relationship between tooth contact and biological systems. It highlights the "Michigan splint" for TMJ management and advocates for "freedom in centric" in clinical occlusion. You can find a digital preview of the textbook on Internet Archive or check library listings for NLM Catalog .

Overview of Occlusion and Malocclusion | PDF | Tooth - Scribd