Analysis of an existing interarch distance is one of the first steps that must be carried out in planning for the restoration of missing teeth in a partially edentulous mouth.1 When missing teeth are not replaced, the space previously occupied by the teeth may not be present any longer. The available space may also be restricted because of the potential extrusion or migration of the opposing dentition or tuberosity enlargement. Early identification of the lack of space would prevent complications in designing and constructing a fixed partial denture (FPD) or a removable partial denture (RPD) for a partially edentulous mouth.2-4 However, intraoral visual or evaluation using measuring instruments is often limited and unreliable because of the limited access to the area of interest; in particular, the posterior segment of the arches.
The indirect procedure employs preliminary impressions made to generate the study casts and mount them on an articulator to examine the relation of the teeth and edentulous ridge area.5,6 When hand articulation of the casts does not provide solid occlusal contacts (such as in an extension situation), the relation of the maxillary and mandibular casts is achieved with the aid of record bases and occlusion rims. The interarch distance is assessed and measured with a ruler on an articulator to determine the available space in seeking possible treatment options to restore the missing dentition.5 This indirect measurement of the interarch space, however, requires multiple clinical and laboratory procedures, a number of materials and instruments, and relies on the accuracy of the cast relation.
