Table 1 Summary of characteristics of the included studies
From: Influence of heritability on occlusal traits: a systematic review of studies in twins
Authors, year | Country | Study design | Type of twin zygosity and n, mean age (years) | Analysis of zygosities | Analysis to estimate heritability | Clinical records | Occlusal and dentoalveolar traits | Main outcomes results |
|---|---|---|---|---|---|---|---|---|
Kučević et al. 2017 [19] | Serbia | Cross-sectional study | 30 MZ pairs , 20–40 years | NR | Correlation coefficient | NR | 1. PAR index | The mean difference between the twins groups were not significant, indicating hereditary dominance for the occlusal characteristics of PAR |
Sidlauskas et al. 2016 [20] | Lithuania | Cross-sectional study | 90 MZ pairs, 22.4 years 51 DZ pairs, 20.4 years | DNA analysis | Model-fitting approach | Cephalometric landmarks | 1. Overjet 2. Overbite | Overjet is determined by unique (50%) and shared (50%) environment factors, whereas overbite is determined by dominant genetic factors (76%) and specific environment factors (24%) |
Švalkauskienė et al. 2015 [10] | Lithuania | Cross-sectional study | 40 MZ pairs, 17.8 years 32 DZ pairs, 20.2 years | DNA analysis | h2 | Dental casts | 1. Arch length 2. Arch width | Moderate to high h2 coefficients were found for the arch width. In the maxilla, the largest genetic effect was between the lateral incisors. Similar, but lower estimates were found for canines and first premolars in the maxilla, as well as for the first premolars of mandibular arch. The maxillary arch length is more likely to be genetically determined than mandibular length (h2 = 1 and 0.57, respectively) |
Kawala et al. 2007 [13] | Poland | Cross-sectional study | 90 MZ pairs, NR 74 DZ pairs, NR | Serologic and morphologic analysis | h2 | NR | 1. Overjet 2. Overbite 3. Posterior crossbite 4. Type of Angle malocclusion 5. Intertooth spacing 6. Crowding | Hereditary coefficient had low or negative values. Only class II angle malocclusion (11%) and mandibular crowding (12%) showed examined values higher than 10% of hereditary determination |
Eguchi et al. 2004 [7] | Australia | Cross sectional study | 44 MZ pairs, 15.8 years 34 DZ pairs, 17 years | DNA analysis | Model-fitting approach and h2 | 3D dental casts | 1. Arches length 2. Arches width | High genetic contribution was found for maxillary and mandibular arch width (ranged from 0.49 to 0.92) and arch length (0.86 mandibular arch and 0.94 for maxillary arch). The width between the lower second premolars showed greater environmental component (51%) |
Richards et al. 1990 [21] | Australia | Cross-sectional study | 29 MZ pairs, 15.8 years 19 DZ pairs, 15.8 years | NR | h2 | Photographs obtained by dental casts | 1. Arch morphology 2. Arch asymmetry | The genetic factors influence the shape of the maxillary (h2 = 0.90 and h2 = 0.42 for quartic and quadratic arch terms, respectively) and mandibular (h2 = 0.35 and h2 = 0.0 for quartic and quadratic arch terms, respectively) arches. However, no evidence of genetic factors influence asymmetry in either maxilla or mandible |
Boraas et al. 1988 [22] | USA | Cross-sectional study | 32 MZ pairs, 39.9 years 16 DZ pairs, 42.1 years | Serologic analysis | Correlation coefficient and h2 | Dental cast | 1. Overjet 2. Overbite 3. Arch width 4. Crowding | Intercanine and intermolar arch width, and malalignment showed significant resemblance within both monozygotic (p < 0.001) and dizygotic (p < 0.01, p < 0.05) pairs, whereas overjet and overbite showed no significant resemblance within pairs |
Sharma et al. 1986 [23] | India | Cross-sectional study | 23 MZ pairs, 17.5 years 35 DZ pairs, 17.5 years | Serological analysis | h2 | Dental casts | 1. Overjet 2. Overbite 3. Posterior crossbite 4. Arch length 5. Arch width 6. Sagittal molar relationship 7. Intertooth spacing 8. Anterior crowding 9. Posterior crowding 10. Total crowding | The occlusal traits: overbite (h2 = 0.77), sagittal molar relationship (h2 = 0.63), anterior (h2 = 0.81) and total teeth crowding (h2 = 0.68), maxillary and mandibular arch length (h2 = 0.72 and 0.66, respectively) and width (h2 = 0.63 and 0.67, respectively) are under potential dominant genetic influence |
Potter et al. 1981 [24] | USA | Cross-sectional study | 87 MZ pairs, 14 years 77 DZ pairs, 14 years | Genetic markers in the blood analysis | h2 | Dental casts | 1. Overjet 2. Overbite 3. Posterior crossbite 4. Sagittal relation of molar 5. Intertooth spacing 6. Crowding | Only overbite and spacing showed significant genetic determination. The other variables had the environmental factors as determinants, but environmental variance is not supported by the occlusal characteristics |
Corruccini et al. 1980 [17] | USA | Cross-sectional study | 32 MZ pairs, 14.5 years 28 DZ pairs, 14.5 years | Serologic and dermatoglyphic analysis | h2 | Dental casts | 1. Overjet 2. Overbite 3. Posterior crossbite 4. Arch length 5. Arch asymmetry 6. Arch width 7. Sagittal molar relationship 8. Intertooth spacing 9. Anterior crowding, 10. posterior crowding 11. Total crowding | Maxillary and mandibular arch length (42% and 28%, respectively), upper and lower molar width (16% and 22%, respectively), posterior crossbite (100%), maxillary and mandibular posterior malalignment (95% and 61%), and mandibular anterior malalignment (35%) yield significant heritability estimates |