# Reliability of clinical orthodontic indicators in the Norwegian Registry of Cleft Lip and Palate

## TL;DR

This study shows that the Norwegian Registry of Cleft Lip and Palate provides reliable orthodontic data for 6-year-olds with clefts.

## Contribution

The study confirms the robustness and reliability of orthodontic indicators in a national cleft registry.

## Key findings

- Orthodontic indicators in the NRCLP showed substantial to almost perfect agreement with reassessments.
- Intra-rater and inter-rater agreements were almost perfect for GOSLON scores and supernumerary teeth assessments.
- The registry data is reliable for dentoalveolar and intermaxillary relations in children with UCLP.

## Abstract

The aim of this study was to assess to the reliability of the orthodontic data for 6-year-old patients with unilateral cleft lip and palate (UCLP) as recorded in the Norwegian Registry of Cleft Lip and Palate (NRCLP).

This study included 64 children with UCLP, born between 2011 and 2015 and enrolled in the two Norwegian cleft centers. All participants had orthodontic recordings from the age of six in the NRCLP and corresponding dental model casts and radiographs available from the cleft centers. Data on dentoalveolar relations, assessed using GOSLON yardstick, the presence of supernumerary teeth and agenesis, and cephalometric values for intermaxillary sagittal relations recorded in the NRCLP were compared to reassessments conducted by four independent and blinded orthodontists. Intra-rater and inter-rater agreement were evaluated using single measure intraclass correlation coefficients and Gwet’s agreement coefficients.

Comparisons between reassessments and the NRCLP data showed substantial to almost perfect agreement for all orthodontic indicators. Intra-rater agreement for GOSLON was almost perfect. Inter-rater agreement among the four orthodontists was almost perfect for GOSLON scores and for assessment of supernumerary teeth and agenesis, and substantial for the intermaxillary sagittal relations.

This study demonstrates that NRCLP in daily use since 2011, shows robust orthodontic indicators and reliable and trustworthy data for six-year-old children with UCLP.

The online version contains supplementary material available at 10.1186/s12903-025-07043-6.