Study On The Correlations Between Nasal Morphology And Craniofacial Structures

To build the patient’s facial beauty is always the goal of the orthodontist by conducting the orthodontic treatment,and it’s also the motivation of the patients to see an orthodontist. As the orthodontic esthetics progressing constantly, its research results were applied to the diagnosis, treatment design and prognostic analysis in the orthodontic treatment. The nose which located in the midface plays an important role in the facial beauty. Especially the viewpoint that the nasal morphology should be taken into consideration during the treatment may be a popular trend among the orthodontist in the future.Based on the the close relationships between nose and facial skeletal structures during the growing development and the growth modification of nasomaxillary complex, we speculate that the nasal morphology may be correlated with the facial skeletal structures. And the domestic and international research results showed the correlations between the nasal morphology and the facial skeletal structures. In our study, we first analyse the correlations between the parameters representing the nasal depth, protrusion and nasal profile forms and the the three factors consisted of vertical facial skeletal structures, sagittal facial skeletal structures and sex. Then on the basis of finding the correlated parameters, further analysis were conducted on the correlated parameters to investigate their variation tendency in different vertical facial skeletal patterns, different sagittal facial skeletal patterns and different genders. Furthermore, the correlations between nasal dorsum axis and mandibular growth direction were analysed. All above were for the purpose of offering some advices to the orthodontic clinical diagnosis and treament plan in considering the nasal morphology. 1. A study on the correlations between the nasal morphology and the 3 factors consisted of vertical facial skeletal structures, sagittal facial skeletal structures and sexObjective :To find the certain nasal morphology parameters correlated with the 3 factors consisted of vertical facial skeletal structures, sagittal facial skeletal structures and sex by evaluating the correlations between the nasal morphology and the 3 factors. Methods: 311 adult orthodontic patients(209 female,102 male,with an average age of 21.49±3.39 years) were chosen randomly. The lateral cephalograms of these patients before treatment were collected. The 3-factor analysis of variance were used for analyzing the relevancy between every nasal parameters and the 3 factors. Results: Sex was a significant factor in certain nasal parameters such as nasal length, columella convexity, and nasal tip height, nasal bone length, alar height, hump, nasal base angle, nasal vertical length(P<0.05). The anteriposterior classifications were found to be significant for NLA, SFC, hump, nasal convex angle(P<0.05). The vertical classifications were found to be significant for nasal bone length and nasal dorsum axis angle(P<0.05). Conclusions: The nasal morphology was correlated with the 3 factors consisted of vertical facial skeletal structures, sagittal facial skeletal structures and sex. 2. A study on the differences of the nasal morphology between different gendersObjective :To evaluate the differences of the nasal morphology between different genders. Methods: 311 adult orthodontic patients(209 female,102 male,with an average age of 21.49±3.39 years) were chosen randomly. The lateral cephalograms of these patients before treatment were collected. Analysis of variance were used for analyzing the differences of nasal vertical length, nasal bone length, nasal length, pronasale height, alar height, hump, columella convexity and nasal base angle in different genders. Results: In terms of the nasal length, the nasal vertical length, nasal bone length and nasal length in males were longer than females(P<0.05), In terms of the nasal prominence, the pronasale height, alar height, hump, columella convexity of men were more prominent than women(P<0.05). In terms of the nasal profile norms, the nasal base angles were found to be greater in women(P<0.05).Conclusions: The male nose was proportionately larger than the female nose and usually more protrusive and longer, and the female nose tends to turn upward. 3. A study on the differences of the nasal morphology among the sagittal facial skeletal patternsObjective :To evaluate the differences of the nasal morphology among the sagittal facial skeletal patterns. Methods: 311 adult orthodontic patients(209 female,102 male,with an average age of 21.49±3.39 years) were chosen randomly. ANB angle which was most commonly used to describe the anteroposterior relationships of the jaws in literature was used for sagittal skeletal classification. The lateral cephalograms of these patients before treatment were collected. Analysis of variance were used for analyzing the differences of the nasal parameters correlated with the sagittal facial skeletal structures in different sagittal facial skeletal patterns. Pearson correlation analysis was used for analyzing the the correlations between the sagittal skeletal structures and these nasal parameters. Results: The class II groups had greater nasolabial angles than class I and class III groups(P<0.05). But there were no significant difference between class I and class III groups. As the anteroposterior skeletal pattern changed from class III to I, then to II, the nasal convex angle and SFC decreased(P<0.05). The hump of two genders showed no significant difference among the sagittal facial skeletal patterns. Nasolabial angles and hump were only correlated with the facial convex angle. Whereas the nasal convex angle showed correlations with facial convex angle, APDI, SNB, mandibular length. SFC showed correlations with the facial convex angle, APDI, SNA, SNB, maxillary length, mandibular length, Mc and the jaw convex angle. Conclusions: The mechanism of different sagittal facial skeletal patterns having different nasal convex angle and SFC may due to the different mandibular position, length and maxillary protrusion. The changes of facial convex angle may cause NLA increase in class II groups. 4. A study on the differences of the nasal morphology among the vertical facial skeletal patternsObjective :To evaluate the differences of the nasal morphology among the vertical facial skeletal patterns. Methods: 311 adult orthodontic patients(209 female,102 male,with an average age of 21.49±3.39 years) were chosen randomly. Go Gn-SN angle which was most commonly used to describe the vertical skeletal relationships of the jaws in literature was used for skeletal classification. The lateral cephalograms of these patients before treatment were collected. Analysis of variance were used for analyzing the differences of the nasal parameters correlated with the vertical facial skeletal structures in different vertical facial skeletal patterns. Pearson correlation analysis were used for analyzing the the correlations between the vertical skeletal structures and these nasal parameters. Results: The high angle groups had greater dorsum axis angle than low angle and optimum angle groups(P<0.05), but there were no significant differences between low angle and optimum angle groups(P>0.05). In the males group, the high angle groups had greater nasal bone length than low angle and optimum angle groups(P<0.05), but there were no significant difference between low angle and optimum angle groups(P>0.05). And there were no significant difference among the vertical facial skeletal patterns in female group(P>0.05). The nasal bone length showed positive correlations with PP-SN, lower facial height, upper face height, posterior facial height and Y axis angle(P<0.05). The dorsum axis angle showed positive correlations with Y axis angle and lower facial height(P<0.05). Conclusions: The dorsum axis angle of high angle individuals had increasing trends and the nasal bone length of male high angle individuals also had increasing trends. The mechanism of different vertical facial skeletal patterns had different nasal-bone length might due to the different PP-SN, skeletal height and Y axis angle. The differences of nasal dorsum axis angle might be caused by the differences of Y axis angle and mandibular height. 5. A study on the correlations between nasal dorsum axis and mandibular growth directionObjective:To analyze the correlations between the growth directions of mandibular and the nasal dorsum axis. Methods: 311 adult orthodontic patients(209 female,102 male,with an average age of 21.49±3.39 years) were chosen randomly. The lateral cephalograms of these patients before treatment were collected. Y axis angle and dorsum axis angle were measured and the correlations between them were analyzed. The dorsum swing angle which represented the differences between these two angles was calculated, and the influencing cranialfacial factors were analyzed. Results: The correlations between Y axis angle and dorsum axis angle were suggested(r=0.489,P =0004). The mean of the dorsum swing angle is 2.25゜±3.89゜, and 95% confidence interval is(1.82゜,2.70゜). The dorsum swing angle was not correlative with sex significantly, but it was correlative significantly with the anteroposterior relationship between upper and lower jaws. Y axis angle and dorsum axis angle in class I patients were nearly equal. Compared with the Y axis, the dorsum axis changed downward and backward in class III patients with opposite change in class II patients. As the anteroposterior skeletal pattern changed from class III to I, then to II, the Y axis angle increased(P<0.01), whereas there was no significant change in the dorsum axis angle(P>0.05). Conclusions: Y axis angle had positive correlation with the dorsal axis angle, and they were approximate parallel. The differences of dorsum swing angles among different anteroposterior patients might result from the differences of growth directions of mandibular instead of the differences of growth directions of nasal dorsum.