Digital Versus Conventional Nance-Based Space Maintainers for Preservation of Maxillary Arch Dimensions in Children: A Randomized Controlled Clinical Trial
Year: 2026
Type: preprint
Abstract: Background Early extraction of deciduous molars can conduct to space loss and mesial rotation of the maxillary first permanent molars. Though Digital workflows and 3D-printed appliances were introduced in an attempt to enhance the precision of space maintainers (SM), but the combined Nance-transpalatal arch (Nance-TPA) design has rarely been studied. This study compared digitally fabricated and conventional Nance and Nance-TPA SMs in preserving maxillary dental arch dimensions after bilateral early loss of primary molars. Methods This single-blinded, parallel-group randomized controlled trial followed the CONSORT statement. A total of 128 healthy children aged 8 to 9 years with bilateral prematurely extracted maxillary primary molars were randomly allocated 1:1:1:1 (n = 32 per group) to digital Nance, digital Nance-TPA, conventional Nance, or conventional Nance-TPA. Digital appliances were designed from intraoral scans and fabricated from cobalt-chromium by direct metal laser sintering. Digital arch scans were recruited at baseline and at 3, 6, and 12 months. Arch perimeter, palatal vault depth, maxillary and anterior segment width and length, and molar rotation were measured using 3D Slicer Software. Findings were assayed using a three-factor mixed repeated-measures ANOVA with Bonferroni-adjusted comparisons (p < 0.05). Results Eight patients were lost to follow-up (attrition 6.25%), mainly due to appliance breakage, and 120 patients (30 per group) were analyzed. All measured parameters changed significantly over time (p < 0.001). Digital fabrication was allied with a significantly greater arch perimeter at 3, 6, and 12 months (p = 0.029, p = 0.001, and p < 0.001, respectively), whilst conventional appliances showed greater palatal vault depth (p < 0.001). Digital groups differed significantly from conventional groups in maxillary width from 3 months onward. The digital Nance-TPA group showed the least molar rotation and the most stable anterior segment width. The conventional Nance-TPA group showed the most stable arch perimeter and maxillary width. No single appliance-fabrication combination was superior across all dimensions. Conclusions Digital and conventional Nance-based appliances both showed measurable changes in arch dimensions over 12 months, and the effect of fabrication method and appliance design depended on the parameter measured. Digital fabrication was favorable for arch perimeter and palatal vault depth, and adding a TPA helped limit molar rotation and preserve few arch dimensions. Appliance selection should therefore be individualized to the arch dimension of greatest clinical concern.
Source: Research Square
Authors: Nehal Salman, Hani AlSwafeeri
Institution: Pharos University in Alexandria
Language: English
Subfield: Orthodontics
Field: Dentistry
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7225824317