Craniofacial size in individuals with supernumerary teeth: A multicenter geometric morphometric study
Sofia Bakirtzi1, Eva Henninger1, Luca Friedli1
1Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, 3010, Switzerland.
Background:
Although tooth agenesis has been consistently associated with reduced craniofacial size, the craniofacial implications of supernumerary teeth remain unexplored. This study aimed to assess whether the presence, number, and location of supernumerary teeth are associated with craniofacial size in non-syndromic individuals, and whether these effects differ by sex.
Methods:
A retrospective multicenter study was performed using > 10,000 orthodontic records from Switzerland and Greece (2002-2023). The sample included 200 individuals with supernumerary teeth (125 males, 75 females; mean age 12.7 ± 5.7 years) and 200 age- and sex-matched controls. Supernumerary teeth were classified by number and location (maxilla vs. mandible). Craniofacial morphology was described on pre-treatment lateral cephalograms using 117 landmarks and semi-landmarks across different anatomical regions. The size of these regions and of the entire craniofacial complex was measured as the natural logarithm of centroid size (ln[CS]). Multiple linear regression models were applied to test associations between craniofacial size, sex, age, and supernumerary tooth number or location. Statistical significance was set at α = 0.05.
Results:
Age and sex were strong predictors of craniofacial size (P < 0.001), with larger dimensions in males and older individuals. The number of supernumerary teeth showed a small positive association with maxillary size (β = 0.011; P < 0.005), evident only when rare severe cases (> 2 teeth) were included, and no significant effects on the cranial base, mandible, or overall facial size. Location-specific analyses indicated that individuals with mandibular supernumerary teeth (n = 50) had larger mandibular (β = 0.016; P = 0.009) and maxillary dimensions (β = 0.022; P < 0.001), with males also showing slightly larger overall facial size (+ 2.5%; P = 0.014). Maxillary supernumerary teeth (n = 145) showed no significant craniofacial size differences.
Conclusion:
Supernumerary teeth exert limited, region-specific effects on craniofacial size. While overall facial dimensions remain largely unchanged, mandibular supernumeraries, though uncommon, are associated with modest enlargement of both jaws in males. These findings contrast with the consistently reduced craniofacial size in cases with tooth agenesis, underscoring the differential developmental impact of different tooth number anomalies.
