This study aimed to assess the possible relation between the dimensions of the palatal surface area and anthropometric measurements of the head and face in living subjects. An intra-oral scanner was used to determine the palatal surface area. The excellent ICC for the palatal surface areas indicated the high reproducibility of the intra-oral scanner technique. Various head and face measurements had a significant correlation with the palatal surface area. When stratified on sex, significant correlations with the female palatal surface were found with the mandibular length and palatal width.
The adult palatal surface area found was 2120.6 mm2, which was comparable to findings that were disclosed in other studies with a mean of 1990–2010 mm2 [5, 6, 16]. In these studies, the palatal surface areas were determined using foil impressions taken from stone models [5, 6], while another study used CBCT imaging and digital analysis [16]. Apparently, all methods used so far reveal comparable and representative results as the reported palatal surface areas are in the same range. In addition, the technique presented in the current study, using an intra-oral scanner, adds up to this line of methods as it had a very good reproducibility with an excellent ICC. Moreover, the intra-oral scanner has the beneficial effect that it does not use ionizing radiation and its technique is easy, safe and less laborious.
The palatal surface area in the current study did not differ between the two sexes. This finding is consistent with results of two other studies [5, 16], while another study revealed that male participants had a significantly larger palatal surface areas compared to females [6]. This latter study, however, included females with a mean age 16.8 ± 8.02 years and males of 20.7 ± 13.4 years old [6]. These participants were considerable younger than the volunteers in the current study with a mean age of 42.6 ± 14.8 years. In this light, is has to be noted that maturation of female facial structures starts at an earlier age compared to males [24]. For this reason, in younger aged groups; there is a significant difference in palatal surface area between the two sexes. That could explain why the study by Kerr et al. found significant differences for the palatal surface area measurements [6]. However, when investigating older subjects, such as the current study, these differences for the palatal surface area apparently disappeared.
In the current study, head and face proportions differed significantly between females and males. This finding is broadly supported by the work of other studies describing the effects of sex on anthropometric orofacial measures, mentioning larger measures for males when compared to females [25–27]. In our previous study, investigating cadavers with CBCT, comparable anthropometric differences between two sexes were observed [16]. In the cadaver study, the length of the head did not differ significantly for the two sexes, while in the current study there was a significant difference for the length of the head between the two sexes. This result could be explained by the limited number of cadavers used in the CBCT study (female N = 8, and male N = 5) [16] compared to the larger number of living subjects in the current study (female N = 23, and male N = 28).
In the current study, various anthropometric measurements had a significant correlation with the palatal surface area. This is in contrast with the CBCT study with human cadavers where only a statistically significant correlation between the length of the head and palatal surface area was observed. There are several possible explanations for this result; firstly, the previous study included cadavers with possibly solidified soft tissues. Secondly, the number of included subjects might also influence this observation; the cadaver study had a possibly limited statistical power due to the limited number of cadavers used (N = 12). Although in the current study more significant correlations were found between palatal surface area and facial anthropometric measurements, most of these correlations are poor or fair (± 0.3). Finally, sex differences have influenced these correlations, as males had significant larger head and face proportions then females. For this reason, most of significant correlations disappeared after stratifying the subjects based on their sex, especially for males. And so, females had a significant correlation between palatal surface with the mandibular length and the palatal width. Possibly the face type of females attributed to this significant correlation. It could be that that this relates to the fact that the face type of females is different compared to males; for females the most common face type is mesoprosop (medium-broad face) or euryprosop (short and wide), while for male it is the leptoprosop (long and narrow) and hyperleptoprosop [28, 29].