Abstract
Abstract Background The aim of the present study was to assess sexual dimorphism related to occlusal variables recorded from dental casts of Australian twins and to compare trends across primary (T1), mixed (T2) and permanent (T3) dentitions in the same individuals. Methods The sample comprised 22 males and 25 females selected at random from monozygotic pairs and 19 males and 19 females from dizygotic pairs. Overjet, overbite, midline deviation, midline diastema, primary and permanent molar relationship, and primary and permanent canine relationships were measured in millimetres using a digital calliper Results The mean values for overjet in males in the permanent dentition and for overbite in the mixed and permanent dentitions were significantly greater than those for females. The other occlusal traits showed no sexual dimorphism. Midline diastemata were most prevalent in the primary dentition while coincident midlines were most prevalent at all stages for both genders. In addition, a mesial step deciduous molar relationship was more prevalent on the right side and a flush terminal plane present on the left. Furthermore, a Class II permanent molar relationship was predominant in T1/T2, while a Class I relationship was most prevalent in the permanent dentition. Class II primary and permanent canine relationships were most common at all stages Conclusions Significant sexual dimorphism was found for overjet and overbite at several occlusal developmental stages but sexual dimorphism was not found for the other occlusal traits studied
Highlights
During development, the occlusal relationships of the dental arches pass through a series of modifications to adapt to the vertical, transverse and antero-posterior growth of the maxilla and mandible
Changes in arch dimensions during growth present a degree of sexual dimorphism, as males display an increase of 1.3 mm on average in arch circumference in the maxilla compared with 0.5 mm in females, while arch circumference tends to decrease in the mandible, in males by an average of 3.4 mm and in females by an average of 4.5 mm.[2]
Dahlberg statistics ranged from 0.1 mm for midline diastema to 0.6 mm for the permanent left canine relationship, confirming that random errors were small in magnitude
Summary
The occlusal relationships of the dental arches pass through a series of modifications to adapt to the vertical, transverse and antero-posterior growth of the maxilla and mandible. Sexual dimorphism is evident in males and females in relation to tooth crown size and its magnitude and patterning vary from tooth to tooth, as well as between populations.[4,5,6,7] Males present larger dental crown dimensions, on average, than females[8] and this is evident through the primary and permanent dentitions.[9] Changes in arch dimensions during growth present a degree of sexual dimorphism, as males display an increase of 1.3 mm on average in arch circumference in the maxilla compared with 0.5 mm in females, while arch circumference tends to decrease in the mandible, in males by an average of 3.4 mm and in females by an average of 4.5 mm.[2]. Conclusions: Significant sexual dimorphism was found for overjet and overbite at several occlusal developmental stages but sexual dimorphism was not found for the other occlusal traits studied. (Aust Orthod J 2018; 34: 36-44)
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