Assessment of the impact of tongue size in patients with bimaxillary protrusion.

Background: Tongue size, posture and pressure are considered to have significant influences on the positioning of dentoalveolar structures. Based on the equilibrium theory, forward resting posture of the tongue with light force and long duration could have both a horizontal and vertical effect on teeth. Bimaxillary proclination, a malocclusion trait often seen in African descents with multifactorial etiological factors, could well be related to tongue dimensions.

Objectives: The aim of this study was to evaluate the relationship between tongue dimensions and bimaxillary proclination patients.

Methodology: One hundred selected lateral cephalometric radiographs of consecutive orthodontic patients who met the study criteria were divided into study (bimaxillary proclination with interincisal angle [I/I]< 108°) and control (normal with interincisal relationship [I/I] ≥ 108°) groups. The subjects' tongues were pre-coated with barium sulphate before radiography in order to delineate the tongue outline. Tongue dimensions and the intermaxillary space surface area were determined and analyzed using SPSS version 11 and a computer programme for epidemiological analysis.

Results: The mean tongue measurements in the bimaxillary proclination group were higher than those in the control group except for tongue proportion. These differences were statistically significant for tongue thickness, tongue length and intermaxillary space length (P < 0.05). However, there was no statistically significant difference in the tongue area and intermaxillary space area between subjects with bimaxillary proclination and a normal interincisal relationship (P > 0.05). None of the variables (tongue thickness, tongue length, intermaxillary space length, tongue area and percentage tongue proportion) could be used as predictors for interincisal relationship.

Conclusion: Tongue length, thickness and intermaxillary space length were significantly different between the bimaxillary and normal subjects. However, none of the measured tongue variables could be used as a predictor for incisor relationship.