Abstract
Unilateral posterior crossbite is a type of malocclusion that involves morpho-functional characteristics of masticatory muscle, such as the masseter: electrophysiological data have shown that the affected side works less than the contralateral muscle, which shows a normal or increased activity, probably in order to compensate for the affected side. The aim of present work was to measure the diameter and the cross-sectional area of ipsilateral and contralateral muscle fibers to verify if hypertrophy and/or hypotrophy take place in this malocclusion. We used immunofluorescence pictures to measure, using ImageJ software, the diameter and the cross-sectional area of fibers from control and crossbite groups; after that, the data were processed to perform statistical analyses. Results show that the fiber diameters of contralateral muscle are larger than the diameters of ipsilateral and control fibers, and that this difference is statistically significant. No statistically significant difference was found between the fiber diameters of the ipsilateral and control muscles. All these data suggest that, during unilateral posterior crossbite, morphological changes take place in the contralateral masseter muscle, which undergoes hypertrophy, probably to compensate for the low activity of the affected muscle.
Highlights
Unilateral posterior crossbite is a type of malocclusion characterized by an altered buccal–lingual relationship [1,2]
The intensity of fluorescence was higher in the contralatside (Figure 1C), supporting our previous results showing a higher expression of eral muscles (Figure 1B) than in the control muscle (Figure 1A) and the ipsilateral side sarcoglycans and integrins in contralateral masseter muscles when compared to ipsilateral (Figure 1C), supporting our previous results showing a higher expression of sarcoglycans ones [6]
Several functional and morphological data support the existence of hypertrophy and hypotrophy or atrophy [22], no investigations about masseter muscle fiber diameters during unilateral posterior crossbite exist in the literature
Summary
Unilateral posterior crossbite is a type of malocclusion characterized by an altered buccal–lingual relationship [1,2]. Electrophysiological studies have demonstrated that the masseter muscle of the affected side, named ipsilateral, works less than the healthy side, named contralateral, and that the contralateral side can exhibit a normal or increased activity [1,5]. Both the high activity on one side and the low activity on the other side determine several morphological changes, which seem to be typical of hypertrophic and hypotrophic processes, respectively [6]. In the most severe cases of malocclusion, the existence of an atrophic condition in the ipsilateral masseter muscle has been demonstrated [6].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call