Effect of Rapid Maxillary Expansion on Condyle–fossa Relationship in Growing Patients

Abstract

Aim: This study tests whether rapid maxillary expansion (RME) exerts long term effects on interglenoid fossa distance and condyle fossa relationship. Materials and methods:Consecutive growing patients aged 8 to 13 years were allocated either to the RME group or control group. Cone-beam computed tomography was performed at baseline and at 6 months. Specific software was used to determine fixed landmarks. Multivariate Analysis of Covariance (MANCOVA) models were used, with time by group interaction, using age as a covariate.Results: Twenty-seven patients with a mean age of 11.4 ± 1.5 years were included. There was an overall significant group by time interaction (p = 0.012, effect size 0.59). Change in the lateral position of the glenoid fossa, the primary outcome, was reached (p = 0.008, effect size 0.258). Change in the laterolateral position of the center of the condyle, and the co-primary outcome was also significant (p = 0.011, effect size = 0.24). Nasal cavity width increased (p = 0.065, effect size = 0.14). There was an initial asymmetry in the horizontal position of the condyles that was carried on with no effect of RME. Conclusion:Rapid maxillary expansion (RME) produces a significant increase in the interglenoid fossa distance and displacement of the mandibular condyles at 6 months in growing patients compared to a control group. Clinical significance:The current study shows that RME is effective during growth, widening the interglenoid fossa distance and the lateral positions of the condyles and eventually enlarging the nasal cavity, without causing asymmetry.

Effects of rapid maxillary expansion on temporomandibular joints:

“…One article reported that RME modified joint space and condylar postion, promoting greater spatial symmetry between the crossbite and non-crossbite 25 side. Three articles found that the RME was able to change the individual condylar position 27,28,30 and joint space, 26,29 maintaining the symmetric relationship between the condyles. 26,27,29 There was no evaluation of intercondylar symmetry in the measures used by McLeod et al (2016), 28 who observed no alteration of the condylar position in the glenoid fossa in individuals.…”

“…Of these, one study was eliminated because it was a protocol proposal to be followed in future studies, 15 one for evaluating pre-and post-intervention changes through gypsum models and bite registration, 16 one for assessing condylar change by means of zonograms, 17 and five studies were excluded since they examined patients who underwent slow maxillary expansion. 10,[18][19][20][21] Therefore, seven articles from the systematic search were included for qualitative analysis; [22][23][24][25][26][27][28] as well as one record found by hand search (n ¼ 1); 29 totaling eight articles included in this review ( Table 1). A quantitative analysis was not feasible given the heterogeneity in the methodology of the selected articles.…”

“…22 Five articles evaluated the condylar position and articular spaces by means of tomography: two by conventional tomography 25,26 and three by cone beam tomography. [27][28][29] The standard protocol for RME employed by several authors 4,5 consisted of two quarter-turns of activation per day until overcorrection was reached. That protocol was used for six of the studies included.…”

“…That protocol was used for six of the studies included. [22][23][24][25]28,29 Leonardi et al (2012) 26 used the protocol of three quarter-turns per day while Melgaço et al (2014) 27 achieve one full turn per day.…”

“…However, variability was observed in relation to the time of measurement fafter the activations. One study evaluated after 6 and 18 weeks, 22 two after 12 weeks, 25,27 one after 12 and 18 weeks, 24 one after 18 weeks, 23 two after 24 weeks, 28,29 and one immediately after the activations. 26…”