Influence of short-span scans on trueness in the digital transfer of the maxillomandibular relationship

Abstract

ObjectivesThis study aimed to assess the influence of the location and distribution of short-span scans, serving as intermediate registration data, on the trueness of digitally transferring the maxillomandibular relationship in full-mouth rehabilitation. MethodsMaxillary and mandibular complete-arch preparation casts mounted on an articulator were scanned, with and without interim restorations, using an intraoral scanner. Four types of short-span scans—right anterior, left anterior, right posterior, and left posterior—were captured from maxillary and mandibular casts. Each scan comprised two prepared teeth and two crowned teeth arranged alternately. These short-span scans served as intermediate data and were cross-registered with complete-arch interim restorations and preparation casts to transfer the maxillomandibular relationship. Based on the number (1 or 2), location (anterior or posterior), and distribution (unilateral or bilateral) of short-span scans, they were categorized into six groups. Trueness was assessed by evaluating the mandibular 3-dimensional (3D), spatial distance, angle, and linear distance deviations between the test and reference scans. ResultsSignificant differences in the trueness of digital cross-mounting were observed among the six groups (P < .05). The group registering the bilateral posterior areas exhibited the smallest 3D, spatial distance, angle, and linear distance deviations, whereas the group registering one anterior area showed the largest deviations. ConclusionThe number, location, and distribution of the registered short-span scans significantly affected the trueness of transferring the maxillomandibular relationship. A posterior short-span scan had higher trueness than an anterior scan. The symmetrical distribution of the two registered larger short-span scans over the cross-arch enhanced the registration trueness. Clinical significanceDigital cross-mounting in full-mouth rehabilitation using short-span scans enhances transfer accuracy, improves patient comfort, and increases chairside efficiency.