Infraoccluded first permanent molars and their association with facial and skeletal development

Introduction: Permanent molar infraocclusion, usually caused by ankylosis, has been scarcely studied. Unilateral first molar infraocclusion (UFMI) restricts alveolar bone development locally, leading to asymmetrical dental arches and occlusion. This study investigates whether its effect extends beyond dental structures to affect facial and skeletal asymmetries. Methods: A retrospective analysis was conducted on consecutively recruited patients with UFMI in comparison with age- and gender-matched controls. The percentage of patients with occlusal cant (OC), chin deviation (CD), and the mean vertical asymmetry index (VAI), rami length difference ratios (RLD), and condyle length difference ratios were evaluated. For clinical significance, the percentage of patients with VAI and RLD values >3% was compared. The effect of age and jaw were studied. Results: The UFMI group consisted of 29 patients, 16 males and 13 females, mean age of 13.4 ± 3.8 years. Patients with UFMI displayed significantly more CD and OC and higher VAI and RLD ratios vs the controls (59.0% vs 14.0%, 38.0% vs 7.0%, 3.2% vs 1.0%, and 4.0% vs 2.0%, respectively). VAI >3% was found in 34.5% of patients with UFMI and none of the controls (P <0.001). RLD ratios >3% were found in 51.7% of UFMI vs 24% controls (P = 0.030). CD and OC prevalence significantly increased with age in the UFMI group. Maxillary UFMI influenced more than mandibular UFMI. Conclusions: UFMI is linked to significant facial and skeletal asymmetry, particularly in older age groups. These findings highlight the potential relevance of early diagnosis and intervention to mitigate potential long-term influence on facial growth and development.