Mandibular Response After Maxillary Orthopedic Expansion in Class II Growing Subjects

May 18, 2017 updated by: Roberta Lione, University of Rome Tor Vergata

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

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

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

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 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.

Considering that it was not possible to estimate from previous studies the standard deviation to be used for sample size calculation of the main trial with special regards to type of intervention and observation intervals, 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.

To evaluate the sagittal mandibular response induced by RME therapy in mixed dentition patients with Class II malocclusion, comparing the effects of bonded RME and banded RME with a matched untreated Class II control group

This is a single center, prospective 3-arm parallel group randomized clinical trial with a 1:1:1allocation ratio. 30 (thirty) of subjects are planned. Each subject in the treated groups will be treated with a Rapid Maxillary Expander (RME), bonded or banded respectively. Subjects will be assigned to the groups in random order. Evaluations will be taken at baseline and at the end of the retention period/follow up (for a total of 12 months). Subjects who meet all inclusion criteria and none of the exclusion criteria will be entered into the study.

Allocation of patients to the three groups in a 1:1:1 ratio was determined by a computer-generated randomization list using Rv.0.1 software and by a block size of 4. Then, the allocation information (randomization results) was concealed in opaque and sealed envelopes by the statistician.

The study was blinded in regard of the statistical analysis. Data were recorded and blinded for the statistician: blinding was obtained by eliminating from the elaboration file every reference to patient group assignment

To determine the reliability of the method 15 radiographs chosen at random were traced and digitized by the same investigator on 2 separate occasions at least one month apart. A paired t-test was used to compare the two measurements (systematic error). The magnitude of the random error was calculated by using the method of moment's estimator (MME). Exploratory statistics revealed that not all cephalometric variables were normally distributed (Kolmogorov-Smirnov test) with equality of variances (Levene's test).Kruskal-Wallis test or ANOVA with Tukey's post-hoc tests were used to compare the T2-T1 changes in the three groups. All changes were considered significant at P<0.05. All statistical computations were performed with Statistical Package for the Social Sciences software (Version 12, Chicago, IL)..

10 randomized subjects will be included in the treated group 1, 10 randomized patients will be included in the treated group 2 and 10 randomized patients will be used as untreated control group.

The baseline age was 8.1 ± 0.6 years (range 6.6-9.1 years).

Sample size for this pilot trial was calculated according to the method proposed by Whitehead et al. For a standardized effect size of 1 (a clinically relevant change of 2.0 mm with a combined Standard Deviation of 2.0 mm derived from Guest et al.) for the 8 primary outcome variable Pogonion to Nasion perpendicular, a sample size of 10 subjects per group was required for a Type I error rate of 5% and a power of 80%.

Study Type

Interventional

Enrollment (Actual)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
      • Rome, Italy, 00133
        • University of Rome "Tor Vergata"

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

6 years to 9 years (CHILD)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • early mixed dentition with first molars fully erupted,
  • Class II malocclusion (full-cusp or end-to-end molar relationships),
  • negative posterior transverse interarch discrepancy ≥ 4 mm,
  • Overjet ≥ 5 mm,
  • and prepubertal stage of development (Cervical Stage 1 - Cervical Stage 2 in cervical vertebral maturation)

Exclusion Criteria:

  • previous orthodontic treatment,
  • extracted or congenitally missing teeth,
  • craniofacial syndromes or clefts,
  • use of additional orthodontic devices during the observation period

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: TREATMENT
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: NONE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
ACTIVE_COMPARATOR: Treated Group 1
Patient treated with bonded RME (Rapid Maxillary Expander) with a 13-mm screw. The acrylic splints of the bonded expander extended from the first deciduous molars through the first permanent molars.
Device: Bonded RME (Rapid Maxillary Expander) appliance

The expansion screw was activated 1 quarter of a turn per day (0.25 mm per turn) until the palatal cusps of the maxillary posterior teeth approximated the lingual cusps of the mandibular posterior teeth.

The expander was kept in place as a passive retainer for 8 months. After expander removal, patients were followed without performing any additional treatment for 4 months.
ACTIVE_COMPARATOR: Treated Group 2
Patients treated with banded RME (Rapid Maxillary Expander) in the form of a butterfly palatal expander with a 13-mm screw cemented through bands on the second deciduous upper molars.
Device: Banded RME (Rapid Maxillary Expander) appliance

The expansion screw was activated 1 quarter of a turn per day (0.25 mm per turn) until the palatal cusps of the maxillary posterior teeth approximated the lingual cusps of the mandibular posterior teeth.

The expander was kept in place as a passive retainer for 8 months. After expander removal, patients were followed without performing any additional treatment for 4 months.
NO_INTERVENTION: Untreated Control Group
Matched untreated Class II control group prospectively evaluated after one year

What is the study measuring?

Primary Outcome Measures

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

The primary outcome was the change in the position of point Pogonion to the Nasion perpendicular (Pg to N perp). The objective is to evaluate the changes in the sagittal mandibular position induced by bonded or banded RMEs compared with an untreated control group.

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
12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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
12 months
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
12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Rome Tor Vergata

Investigators

  • Principal Investigator: Roberta Lione, Dentistry, Research Fellow, Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata," Rome, Italy, and research Fellow, Department of Dentistry, University Nostra Signora del Buon Consiglio, Tirana, Albania

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

January 1, 2015

Primary Completion (ACTUAL)

November 1, 2015

Study Completion (ACTUAL)

November 1, 2016

Study Registration Dates

First Submitted

May 15, 2017

First Submitted That Met QC Criteria

May 18, 2017

First Posted (ACTUAL)

May 19, 2017

Study Record Updates

Last Update Posted (ACTUAL)

May 19, 2017

Last Update Submitted That Met QC Criteria

May 18, 2017

Last Verified

May 1, 2017

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 130/14

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

no individual participant data are to be shared

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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