Genetics of three-dimensional tooth inclination and angulation in orthodontic patients with Class I Occlusion: A cross-sectional study

Rahma ElNaghy; Andrew Thomas Daabous; Majd Hasanin; Nazanin Tanha; Nicholas Ancona; Riyad Al-Qawasmi

doi:10.1016/j.ortho.2022.100713

Genetics of three-dimensional tooth inclination and angulation in orthodontic patients with Class I Occlusion: A cross-sectional study

Int Orthod. 2023 Mar;21(1):100713. doi: 10.1016/j.ortho.2022.100713. Epub 2022 Dec 7.

Authors

Rahma ElNaghy¹, Andrew Thomas Daabous², Majd Hasanin², Nazanin Tanha², Nicholas Ancona², Riyad Al-Qawasmi²

Affiliations

¹ School of Dentistry, University of Detroit Mercy, Department of Graduate Orthodontics, Detroit, Michigan, USA. Electronic address: elnaghra@udmercy.edu.
² School of Dentistry, University of Detroit Mercy, Department of Graduate Orthodontics, Detroit, Michigan, USA.

PMID: 36495779
DOI: 10.1016/j.ortho.2022.100713

Abstract

Purpose: This cross-sectional study aimed to utilize quantitative polymerase chain reaction (qPCR) to investigate the influence of genetic variance over teeth inclination and angulation in orthodontic patients with Class I occlusion.

Materials and methods: DNA was extracted from adolescent patients seeking orthodontic treatment in a single institution (from July 2018 to April 2020), who had CBCTs taken as part of initial standardized records. Patients had permanent dentition, Class I skeletal and dental classifications, with normal vertical and transverse skeletal dimensions, normal incisors inclination, no to mild crowding or spacing. qPCR was performed using genetic markers for candidate genes EPB41, TGFβ3, GHR and PAX9. Three-dimensional teeth inclinations (TI) and angulations (TA) were evaluated using Invivo6 software and correlated with genotypes. Reliability of TI and TA was assessed using intraclass correlation coefficients (ICC). Mixed models and multiple linear regression analyses were used to assess the association between each single nucleotide polymorphisms (SNP) with tooth inclination (TI) and with tooth angulation (TA). The results were evaluated at the significance level of P<0.05.

Results: Twenty four adolescent patients with mean age of 13.4±2.4 years were included in the study. ICC showed adequate intra-examiner reliability for TI and TA (0.806<r<0.988, P<0.001). Multiple linear regression analysis showed a significant association between TI and homozygous-T polymorphism for PAX9 (P=0.028) and homozygous-G polymorphism for GHR (P=0.028). Also, a significant association between TA and homozygous-A polymorphism for EPB41 (P=0.019) and homozygous-G polymorphism for GHR (P=0.001) was evident.

Conclusions: Autosomal recessive patterns of inheritance for PAX9 and GHR with TI and for EPB41 and GHR with TA were shown. This study offers insight toward the hierarchical nature of epigenetic interactions between heredity and the environment in determining the three-dimensional positions of teeth in orthodontic patients with Class I occlusion.

Keywords: Class I malocclusion; Genetics; Tooth angulation; Tooth inclination.

MeSH terms

Adolescent
Child
Cross-Sectional Studies
Humans
Malocclusion*
Reproducibility of Results
Tooth Crown
Tooth*