Clinical Trial: Mandibular Response After Maxillary Orthopedic Expansion in Class II Growing Subjects

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Mandibular Response After Rapid Maxillary Expansion in Class II Growing Patients: a Pilot Randomized Controlled Trial

Brief Summary: the effectiveness of RME (Rapid Maxillary Expander) on the sagittal dental or skeletal parameters is still controversial because very little has been written regarding the behavior of antero-posterior mandibular changes in Class II growing subjects who underwent RME as the phase 1 treatment intervention. The reported significant occlusal improvement could be attributed to other reasons, ie, skeletal growth or the use of additional appliances during transition from mixed to permanent dentition. Moreover, the majority of the studies show some limits: they are not randomized, they are not prospective, and they have no control group or they use patients from growth studies as a source for the control group. The primary objective of the present investigation was to conduct a pilot randomized controlled trial (RCT) evaluating the changes in the antero-posterior mandibular position induced by bonded or banded RMEs compared with an untreated Class II control group

Detailed Summary:

Class II malocclusions are commonly observed in orthodontic patients. During treatment planning among the several dento-skeletal pattern combinations of Class II malocclusion, it is important to consider the maxillary transverse deficiency, which is often overlooked.

it has been showed showed an underlying posterior interarch transverse discrepancy of 3 to 5 mm in subjects in early mixed dentition with Class II malocclusions without posterior crossbites in centric occlusion. When these Class II patients are asked to posture their lower jaw forward in a Class I molar relationship, this transverse discrepancy (ie, maxillary constriction) can be observed clinically. It was postulated that in these subjects the mandible is kept in a distal position relative to centric relation because the constricted maxilla is holding it back. The presence of a primitive transverse discrepancy between the dental arches induces a backward position of the mandible, as the occlusal goal is to obtain the highest number of functional contacts.

As reported by several authors, widening the maxilla with rapid maxillary expansion often leads to spontaneous forward posturing of the mandible during the retention period. The orthopedic expansion removes occlusal interferences, allowing the mandible to posture forward, thus improving the sagittal relationships. The mandibular arch acts as a ''foot'' that moves forward after the ''shoe'' is widened.

However, the effectiveness of RME on the sagittal dental or skeletal parameters is still controversial because very little has been written regarding the behavior of antero-posterior mandibular changes in Class II growing subjects who underwent RME as the phase 1 treatment intervention. The reported significant occlusal improvement could be attributed to other r
Sponsor: University of Rome Tor Vergata

Current Primary Outcome: Mandibular displacement after RME appliance therapy (linear measurement in millimeters) when compared with a matched untreated control group [ Time Frame: 12 months ]

Original Primary Outcome: Same as current

Current Secondary Outcome:

• Occlusal improvement of Class II molar relationship after RME appliance therapy (linear measurement in millimeters) when compared with a matched untreated control group [ Time Frame: 12 months ]
  The secondary outcome is to evaluate if maxillary expansion corrects or improves a Class II molar relationship (the mesiobuccal cusp of the maxillary permanent 1st molar must occlude in the embrasure between the mandibular 2nd premolar and the mandibular permanent 1st molar) when compared with an untreated control group. For each treated patient, lateral cephalograms were obtained before treatment and after 1 year to evaluate the dento-skeletal changes. Untreated patients had lateral cephalograms before and after a 1 year interval. Cephalograms were scanned using a professional table scanner (Epson Perfection V700 Photo, CA, USA), with resolution set to 150 dots per inch (dpi) gray scale and were digitized by 1 investigator., followed by a customized digitization regimen and analysis (Viewbox 3.1; dHAL Software, Kifissia, Greece). All cephalograms were at a magnification of 0%. The examiner was blinded to the origin of the films and the group to which each subject belonged
• Treatment effects on vertical dimension (SN-Go Me; angular measurement) and on Gonial Angle (Ar-Go-Me, angular measurement) and vertical growth pattern after RME appliance therapy when compared with a matched untreated control group [ Time Frame: 12 months ]

  The objective is to verify if the treatment determined a reduction of the facial divergency (SN-Go Me°) and of the gonial angle (Ar-Go-Me°) when both subjects, treated respectively with banded RME and bonded RME, are compared with untreated subjects.

  For each treated patient, standard lateral cephalograms were obtained before treatment and after 1 year to evaluate the dento-skeletal changes. The Control Group was followed up without treatment for 1 year and had lateral cephalograms before and after a one-year interval.

  Cephalograms were scanned using a professional table scanner (Epson Perfection V700 Photo, CA, USA), with resolution set to 150 dots per inch (dpi) gray scale and were digitized by 1 investigator., followed by a customized digitization regimen and analysis (Viewbox 3.1; dHAL Software, Kifissia, Greece). All cephalograms were at a magnification of 0%. The examiner was blinded to the origin of the films and the group to which each subject belonged

Original Secondary Outcome: Same as current

Information By: University of Rome Tor Vergata

Dates:
Date Received: May 15, 2017
Date Started: January 2015
Date Completion:
Last Updated: May 18, 2017
Last Verified: May 2017