“ARCH WIDTH, ARCH LENGTH AND PALATAL DEPTH CHANGES IN CLASS II GROWING PATIENTS TREATED WITH FRANKEL II APPLIANCE COMPARED TO A CONTROL GROUP – A STUDY MODEL ANALYSIS”
BRIEF RESUME OF THE INTENDED WORK : 6.1 Need for the study :
Among various skeletal jaw discrepancies Class II malocclusion is one of the most commonly encountered types of malocclusion. One of the treatment modalities during growth period is the use of Functional appliances which aims to correct the skeletal relationship before the malocclusion is fully expressed in the permanent dentition.
Frankel has stated that the developmental inhibition in the size of the underlying skeletal structures that support the teeth is causally related to perioral and buccal muscle function. Unlike other functional appliances Frankel appliance is confined to the oral vestibule and the elimination of aberrant perioral and buccal muscle activity during development will result in full development of dental arches with less functional and morphologic deviation.
Frankel has designed, constructed, and clinically applied a series of functional appliances for the treatment of transverse, antero-posterior, and vertical jaw discrepancies seen in Class II malocclusion.
The studies on Rapid maxillary expansion have showed the changes in the palatal depth and arch length due to arch expansion in the growing patients. However, the changes in palatal depth following passive expansion by using growth modulators(Frankel appliance) needs to be evaluated in contrast with the active expansion accomplished by orthopedic appliance.
Hence, the purpose of the present study is to estimate the changes in the arch width along with arch length and palatal depth changes in a Class II malocclusion patients treated with Frankel II appliance compared with a sample of untreated Class II patients, the control group.
Research question: Is there a difference in the arch width, arch length, palatal depth in a Class II malocclusion patients treated with Frankel II appliance compared to untreated Class II patients.
Research hypothesis: There exists a difference in the arch width, arch length, palatal depth in a Class II malocclusion patients treated with Frankel II appliance compared to untreated Class II patients.
Null hypothesis: There exists no difference in the arch width, arch length, palatal depth in a Class II malocclusion patients treated with Frankel II appliance compared to untreated Class II patients.
6.2 Review of literature: In 1982, a study was done to compare the arch development in growing Class II patients after Frankel therapy with arch development in similar group of untreated Class II subjects. 60 treated and 47 untreated persons were compared for a 2-4 year period. Sequential maxillary and mandibular dental casts of the treated and untreated groups were examined. The results of this study indicate that the expansion of the maxillary and mandibular dental arches occurred to a much greater extent in patients undergoing Frankel treatment than in the control subjects and the expansion was not limited to a particular region of the dental arch in the treated cases, although the largest expansion values were recorded in the premolar and molar regions. Lesser values were recorded in the canine region.1 In 1987, a study was done to evaluate the skeletal, dental, and condylar positional changes induced by Frankel FR II therapy. The pre and post treatment cephalometric, tomographic, and dental cast records of 25 consecutively treated cases were evaluated. This study suggested that the treatment results produced by the Frankel appliance were primarily dental in nature with little skeletal or condylar alteration was observed. The maxillary inter molar width along with the mandibular inter canine and inter molar widths were significantly increased during treatment.2 In 1987, a study was done to evaluate the changes in dental arch width and arch perimeters in 24 Class II, division 1 patients treated with the Frankel II appliance were compared with changes in an untreated control group. Measurements were made on pretreatment and post treatment plaster casts. The results showed a significant increase in the occlusal arch width in the molar and premolar regions in the maxilla and in the premolar regions in the mandible and the total arch perimeter decreased significantly less in the treatment sample than in the control sample. This study suggests that the expansion produced by the functional regulator would not be sufficient to relieve severe crowding, but could be useful in avoiding removal of teeth in borderline extraction cases.3 In 1990, a study was done to assess the long term stability of the arch expansion effects of the functional regulator. Mandibular dental casts were evaluated for treatment and post retention changes in inter canine width, width between first premolars, and width between second premolars, inter molar width, incisor irregularity, and arch length. This study was comprised of 11 cases that were treated with the Frankel appliance and average of 4 years and 4 months out of active treatment. Results showed overall stability to be good, with some variability present in individual responses.4
In 2009, a study was done to compare the effects of rapid maxillary expansion and surgically assisted RME on dentoalveolar structures. Dental casts were analyzed at pretreatment, post treatment, 2 year follow up and results showed significant increase in arch width and arch length after expansion and the palatal height showed significant difference from SARME in terms of pretreatment time and the amount of relapse was not significant.5
6.3 Objectives of the study :
To evaluate the treatment effects in patients treated with FR II appliance of Frankel by using dental casts.
2. To compare the changes with that of untreated Class II patients by using dental casts.
MATERIALS AND METHODS
7.1. Source of the data:
Pre-treatment and post-treatment dental casts of Class II patients treated with FR II appliance of Frankel and pre observation and post observation dental casts of untreated Class II patients will be collected from the record section of the Department of Orthodontics and Dentofacial Orthopedics, Bapuji Dental College and Hospital, Davangere.
Sample Size Determination-
For the purpose of study, the probability of Type I error (α) is fixed at 5% and Type II error (β) at 20%.
Data for the calculation of sample size is obtained from the reference article.1
SD1 = 1.4, SD2 = 1.
(SD1)2 = (1.4)2 = 1.96
(SD2)2 = (1)2 = 1
S2 = (SD1)2+(SD2)2 = 1.96 + 1 = 1.48
d = mean1 – mean2 = 3 – 0.5 = 2.5
n = [1.96+0.84]2×2×1.48 = 9.28
Hence, 10 patients will be taken in each group
7.2. Method of collection of data: Criteria for selection of sample:
FR II group-
All patients in the growing phase as determined by the hand wrist radiograph.
All patients in the mixed dentition period.
Patients demonstrating Class II skeletal discrepancy with ANB>40 and having end on to Class II molar relationship.
4. Patients with orthognathic maxilla and retrognathic mandible.
5. Increased overjet and overbite.
6. Positive VTO.
7. The study models of good quality.
Class II skeletal discrepancy with prognathic maxilla.
Severe skeletal discrepancy requiring surgical intervention.
Study models with loss of anatomic details.
All patients in the growing phase as determined by the hand wrist radiograph.
Patients with unfavorable growth pattern.
Patients with severe skeletal discrepancy requiring surgical intervention.
Method of study:
The sample shall be divided into 2 groups:
Group I – FR II group (10 individuals)
Group II-Control group (10 individuals)
Maxillary and mandibular dental casts of FR II treated and control groups will be collected.
Maxillary and mandibular dental casts will be measured for the arch width changes in the occlusal, gingival and alveolar regions before and after treatment in the treatment sample and in the control group.
In the pretreatment dental casts, the distance between left and right permanent first molars, primary first and second molars, and primary canines will be measured and in the post treatment dental casts, the distance between left and right permanent first molars, premolars, and permanent canines will be measured using dial caliper.
In the mixed dentition period if the permanent tooth had not yet erupted no occlusal or gingival measurements will be made, however, an alveolar measurement will be made at the midpoint of the edentulous space.
Arch length will be measured as the sum of the right and left distances from the mesial anatomic contact points of first permanent molars to the contact point of central incisor.
6. Palatal depth will be measured from mid deepest part of the palate to the line connecting the distolingual cusp tips of the upper first permanent molar.
Statistical Analysis :
The changes in these dental cast variables resulting from treated and untreated patients will be compared for statistical differences using t-tests.
Intra group comparisons will be done by paired t-test / Wilcoxon signed rank test.
Inter group comparisons will be done by unpaired t-test / Mann whitney U test.
7.3 Does the study require any investigations or interventions to be conducted on patients or other humans or animals? If so, please describe briefly
Yes, patients study models will be used.
7.4 Has ethical clearance been obtained from your institution in case of 7.3?
Yes, ethical clearance has been obtained from the institution and attached.
LIST OF REFERENCES :
McDougall PD, McNamara JA, Dierkes MJ. Arch width development in class II patients treated with the Frankel appliance. Am J Orthod 1982;82:10-22.
Hamilton SD, Sinclair PM, Hamilton RH. A cephalometric, tomographic, and dental cast evaluation of Frankel therapy. Am J Orthod Dentofac Orthop 1987;92:427-34.
Mcwade RA, Mamandras AH, Hunter WS. The effects of Frankel II treatment on arch width and arch perimeter. Am J Orthod Dentofac Orthop 1987;92:313-20.
Hime DL, Owen AH. The stability of the arch expansion effects of Frankel appliance therapy. Am J Orthod DentoFac Orthop 1990;98:437-45.
Sokucu O, Kosger HH, Bicakci AA, Babacan H.The stability in dental arches in RME and SARME: A 2 year follow up. Angle Orthod 2009;79:207-13.
I/We agree with the treatment plan and give my/our full consent for the treatment procedures and any modifications in the plan during treatment, as deemed necessary. I/We have been explained about the photographs, study models, x-rays, duration, maintenance of appliance, keeping of appointments and the financial commitments pertaining to the treatment. Further I/We have no objection for using my/our records as a teaching aid, scientific presentations,as a study subject or in academic journal for which I have no objection.
I/We have been informed about the treatment purpose, procedure, the benefits and risks in the language that I understand in a comprehensible manner.
I/We hereby grant to the Department of Orthodontics, Bapuji Dental College and Hospital Davangere, India all right to use the details.