Abstract
BackgroundThe inclination of the occlusal plane (OP) is related to facial types and experiences physiological growth-related changes. The aims of this research were to determine if there were any differences in the inclination of OP in subjects with three types of skeletal malocclusion and to investigate the characteristics and differences of functional occlusal plane (FOP) compared to bisected occlusal plane (BOP).MethodsA sample of 90 Caucasians patients was skeletal-classified into three (n = 30), and pre- and post-treatment cephalograms were digitized. Six linear and 8 angular cephalometric measurements were selected. The changes of OP inclination within each group and the differences among the three groups pre- and post-treatment were compared with paired t test and ANOVA test, respectively. The comparison and correlation between BOP and FOP were analyzed with paired t test and coefficient of correlation, respectively.ResultsThe BOP angle increased in all of the three groups but only had statistically significant differences in skeletal class II patients in a mean of 1.51° (p < 0.05). The FOP-SN angle showed stability (p > 0.05) in all three groups. The inclination of FOP was closely related to that of BOP (p < 0.001) but revealed discrepancies in each group.ConclusionsBOP and FOP were statistically significantly steeper in class II subjects compared to the other two groups both before and after treatment. The BOP angle statistically significantly increased by 1.51° in skeletal class II patients. BOP was a more reproducible reference plane compared to FOP during cephalometric tracing process, while FOP showed stability in orthodontically treated patients with all three skeletal patterns.Electronic supplementary materialThe online version of this article (doi:10.1186/s40510-014-0041-1) contains supplementary material, which is available to authorized users.
Highlights
The inclination of the occlusal plane (OP) is related to facial types and experiences physiological growth-related changes
Between groups Through the comparison of the pre-treatment measurements of class II and class III groups with class I group with normal malocclusions, the results showed that skeletal class II malocclusions were mainly due to mandibular retrusion with a normal SNA angle (p > 0.05), while results showed the opposite in skeletal class III group with maxillary retrusion (smaller SNA compare to class I (p < 0.05), normal SNB)
The results revealed that the angle measured between bisected occlusal plane (BOP) and SN plane is statistically significantly increased in skeletal class II group after orthodontic treatment by an average of 1.51° (p = 0.013), while no statistically significant differences were detected in class I and class III groups
Summary
The inclination of the occlusal plane (OP) is related to facial types and experiences physiological growth-related changes. The aims of this research were to determine if there were any differences in the inclination of OP in subjects with three types of skeletal malocclusion and to investigate the characteristics and differences of functional occlusal plane (FOP) compared to bisected occlusal plane (BOP). A functional correlation between the inclination of OP and the masticatory closing path has been observed. This is an important determinant in occlusion and one of the contributing factors to masticatory movement [5]. During dentoskeletal growth, reduced vertical height of dentition unilaterally affects the mandibular position, subsequently leading to a lateral condylar shift during functional movement, such as opening and closing. Occlusal deviations are related to transverse inclination of the OP, and contralateral differences in occlusal vertical dimension can reduce muscular balance eventually, resulting in a mandibular asymmetry [8]
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