*2.4.2 Acetal resins*

Acetal resins, also known as polyoxymethylene, are formed by the polymerization of formaldehyde. They have been used in dentistry since 1986, as alternative materials for denture base and clasps (**Figure 13**). Characterized by superior esthetics, acetal resins have been useful for low-weight removable partial dentures framework manufacturing in allergic patients [58]. They show high impact strength and elasticity [59]. Acetal resins are also indicated for Kemeny-type single unilateral partial dentures, provisional bridges, splints, and orthodontic appliances (**Figure 13**).
