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Table of Contents   
ORIGINAL RESEARCH  
Year : 2012  |  Volume : 23  |  Issue : 2  |  Page : 182-186
Comparison of sagittal and vertical dental changes during first phase of orthodontic treatment with MBT vs ROTH prescription


Department of Orthodontics and Dentofacial Orthopedics, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India

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Date of Submission04-May-2011
Date of Decision05-Aug-2011
Date of Acceptance08-Feb-2012
Date of Web Publication3-Sep-2012
 

   Abstract 

Objective: The present study was to evaluate and compare anchorage loss in sagittal, vertical dimension in incisal, molar segments and distal tipping of upper canine after first phase of orthodontic mechanotherapy utilizing MBT and ROTH philosophies.
Materials and Methods: Thirty patients with class I dentoalveolar malocclusion requiring extraction of all first premolars were randomly assigned into group I and group II. Set of two lateral cephalograms (T1) and (T2) were obtained with appliance in place and after sufficient leveling and aligning respectively. Linear measurements were recorded on the tracings using Pancherz analysis. A Wilcoxon t-test was use to assess the linear changes.
Results: In group I sample, upper and lower incisors retroclined during T1 - T2; by mean (SD) value of 2.267 (1.0032) mm, 2.4 (0.98) mm, respectively. Group II sample showed upper incisor proclination by -0.4 (1.404) and lower incisal retroclination by 0.06 (1.48). Upper and lower molars in group I remained stationary and group II upper and lower molars moved mesially by -1.133 (0.351) and -0.002 (0.005). In group I, upper and lower incisors extruded by -0.867 (0.611) and -0.67 (0.703), respectively, and group II the upper and lower incisors extruded by -0.9 (0.507) and -0.133 (0.639). Upper canine tipped distally during T1 - T2 in group I by -0.33° (2.609) and group II there was a change in distal tip of upper canine by -3° (3.184).
Conclusion: Results from this random clinical trial showed that MBT technique effectively addressed perceived inadequacies of ROTH philosophy.

Keywords: Anchorage, canine lacebacks, MBT prescription, ROTH prescription

How to cite this article:
Talapaneni AK, Supraja G, Prasad M, Kommi PB. Comparison of sagittal and vertical dental changes during first phase of orthodontic treatment with MBT vs ROTH prescription. Indian J Dent Res 2012;23:182-6

How to cite this URL:
Talapaneni AK, Supraja G, Prasad M, Kommi PB. Comparison of sagittal and vertical dental changes during first phase of orthodontic treatment with MBT vs ROTH prescription. Indian J Dent Res [serial online] 2012 [cited 2020 Mar 29];23:182-6. Available from: http://www.ijdr.in/text.asp?2012/23/2/182/100423
Fixed appliance therapy is one of the most widely used treatment modalities in orthodontic practice. The transition from standard edgewise to pre adjusted appliances had allowed orthodontists to treat patients efficiently and with consistent quality of results. Although many techniques have been effectively transferred from standard edgewise to pre adjusted systems, there remain significant differences that require variations in treatment mechanics. Several prescriptions have been proposed by several investigators leading to the development of different pre adjusted bracket systems, such as Andrews, Roth, and MBT.

Amongst the many prescriptions that followed Andrew's original Straight Wire Appliance, [1] the Roth prescription is regarded as the second generation straight wire appliance. Roth [2] devised a single prescription as one that would be applicable to most cases to finish to an "end of appliance therapy" goal in which all tooth positions are slightly overcorrected and from which the teeth will most likely settle into non orthodontic normal position.

The inadequacies in the horizontal and vertical anchorage control were the two significant factors that became apparent during the leveling and aligning phases of orthodontic mechanotherapy with the first and second generation of preadjusted edgewise bracket systems. In the horizontal dimension, the additional tip built into the anterior brackets increased the tendency of anterior teeth to tip forward and this phenomenon significantly burnt the molar anchorage. The root apices of canines tipped excessively closer to the premolar root apices. In the vertical dimension, an extrusion of the incisors due to an augmented mesial tip in the cuspid bracket slot caused a deepening of overbite. [3],[4]

Mc Laughlin, Bennett and Trevisi [5] redesigned the entire straight wire bracket system in order to overcome the perceived inadequacies of original straight wire appliance and Roth philosophy. Thus evolved the third generation of straight wire appliance, the MBT bracket system, characterized by light forces that eliminated the necessity of overcorrection, first and second order compensations. Therefore, MBT came with reduced mesial tip of 8° and 3° on the upper and lower canine brackets, respectively. In addition to the reduced tip, the concept of lace backs and bend backs with light arch wire forces were features proposed by Bennett and Mc Laughlin that provided the most effective way of translating the cuspids distally, prevented labial flaring of anteriors and hence provided significant anchorage control in the horizontal and vertical dimension during leveling and aligning phase of orthodontic mechanotherapy. [3]

Previous studies by Usmani et al.[6] Sueri et al.[7] T. Hosseinzadeh-Nik et al.[8] showed incisor retroclination and controlled canine and molar movements in the horizontal dimension utilizing lacebacks when compared to the non laceback groups. In contrast, Irvene et al.[9] conveyed no difference in the anteroposterior position of lower incisors and a clinically significant increase in the loss of posterior anchorage after first phase of orthodontics in the laceback group using Andrews non extraction series of brackets in their randomized clinical trial. Hence, the results from previous literature are based on comparative values from clinical trials between laceback and non laceback groups utilizing a common system of orthodontic prescription; Andrews, Roth, or MBT. Despite the fact that MBT and Roth prescription are the most commercially sought after systems in today's orthodontic practice, there lacks an vivo examination using a prospective randomized clinical trial to evaluate and compare sagittal anchorage control in the incisal and molar segments, vertical anchorage control in the incisal segment and distal angulation of the canine after the first phase of orthodontics using MBT and Roth philosophies.

Therefore, we aimed to evaluate and compare the following:

  • Sagittal position of upper and lower incisors at the end of leveling and aligning phase of orthodontic mechanotherapy.
  • Mean mesial migration of upper and lower molars at the end of leveling and aligning phase of orthodontic mechanotherapy.
  • Vertical position of upper and lower incisors at the end of leveling and aligning phase of orthodontic mechanotherapy.
  • Angulation of upper canine root at the end of leveling and aligning phase of orthodontic mechanotherapy.

   Materials and Methods Top


The present study involved 30 subjects who were randomly divided into two Groups. The sample size for each group of patients was calculated as n=15 based on an alpha significance level of 0.05 and a beta of 0.2. This gave the study a statistical power of 80% to detect a 1 mm difference in the linear measurements between the two groups. Group I sample (MBT Prescription) includes 15 patients (9 males and 6 females) with a mean age of 14 years and 11 months (range 12-18 years). Group II sample (ROTH prescription) includes 15 patients (7 males and 8 females) with a mean age of 15 years and 3 months (range 13-17 years and 9 months). The subjects were selected according to the following criteria:

  • Class 1 skeletal relationship.
  • Angles class I molar relationship.
  • Mild to moderate crowding with the Little's irregularity index of 2-4 mm.
  • The treatment plan for subjects included pre adjusted edgewise appliance therapy (MBT and ROTH) of 0.022 inch slot dimension and extraction of four first premolars.
  • No major skeletal dysplasia's in the transverse and vertical direction.
  • Absence of oral habits.
Patients in the I st group were bonded and banded with an orthodontic appliance of MBT prescription (3M UNITEK) with a slot dimension of 0.022 inch and patients in the II nd group were bonded and banded with Roth prescription (3M UNITEK) of 0.022 slot dimension. Banding and direct bracket bonding was performed by a single operator who was blinded to reduce operational bias.

Anchorage augmentation procedures like transpalatal arch in the maxillary jaw and lingual arch in the mandibular jaw were carried out in both the groups. With the appliances in place, a stage I cephalogram (T1) with a 10% magnification and intraoral photographs were obtained for all subjects in both the groups. To differentiate the right and left sides on cephalogram an L shaped 0.017 × 0.025 inch stainless steel wire was inserted into the upper and lower molar tubes during radiographic exposure. This wire served as an identification marker for measuring linear molar displacements. Passive lace backs were placed on all four quadrants from the power arm of I st molar to the canines in a figure of eight fashion in those patients treated with MBT prescription (group I). Initial leveling and alignment of the orthodontic mechanotherapy was done with heat activated nickel titanium 0.016 round arch wire and heat activated 0.016 × 0.022 nickel titanium rectangular arch wires for a period of 8 weeks in both the groups.

The distal end of all wires were flamed and quenched in cold water (annealing) before placement. This allowed accurate bend backs to be placed exactly distal to the molar tubes. After 8 weeks, the arch wires were removed and a second set of photographs and lateral cephalogram (T2) were taken.

Sagittal and vertical dental changes occurring during the examination period in either group were analyzed cephalometrically by means of two cephalograms, one after the placement of appliance and the second after the leveling and aligning phase of orthodontic mechanotherapy. Both T1 and T2 cephalograms were traced on Matte acetate tracing film based on Pancherz analysis. [10]

The measuring points, reference points and reference lines are defined as follows.

Measuring points:

  • Incision inferius (Ii) - The incisal tip of the most prominent mandibular central incisor.
  • Incision superius (Is) - The incisal tip of the most prominent maxillary central incisor.
  • Molar inferius (Mi) - The mesial contact point of the mandibular permanent I st molar determined by a tangent perpendicular to OL.
  • Molar superius (Ms) - The mesial contact point of maxillary permanent 1 st permanent molar determined by a tangent perpendicular to OL.
  • Canine inferius (Ci) - The cuspal tip of maxillary canine.
  • Canine apical (Ca) - The apical tip of maxillary canine.
Reference points:

  • Nasion (N) -The most anterior limit of suture nasofrontalis.
  • Sella (S) - The center of sella turcica.
Reference planes:

  • Nasion- sella line (NSL) - The line through Nasion and Sella.
  • Occlusal line (OL) - A line through Incision superius and the distobuccal cusp of the maxillary permanent first molar.
  • Occlusal line perpendicular (OLP) - A line perpendicular to occlusal line through Sella.
  • CIA - A line drawn along the long axis of the canine connecting cuspal and apical tip of maxillary canine.
  • Palatal plane (Pp) - A line drawn from anterior nasal spine to posterior nasal spine.
  • Mandibular plane (Mp) - A line drawn from Gonion to Menton.
Measuring procedure [Figure 1]
Figure 1: Measuring procedure

Click here to view


The linear sagittal measurements of the upper and lower incisors on T1 and T2 cephalograms were measured by drawing a line through Incision superius, Incision inferius to the occlusal line perpendicular.

The linear sagittal measurement of the upper and lower molars was drawn by measuring the length of the occlusal plane between molar superius, molar inferius to occlusal line perpendicular.

The linear vertical measurements of the upper and lower incisors were drawn by measuring the length of the perpendicular line drawn though incision superius to palatal plane and incision inferius to mandibular plane, respectively.

Inclination of the upper canine root was measured in both T1 and T2 cephalograms by calculating the angular measurement between NSL and long axis of the canine (CIA).

Sagittal and vertical changes of different measuring points in relation to the occlusal line perpendicular occurring during examination period of eight weeks were registered by calculating the difference in the land mark position between T1 and T2 cephalograms.

Variables for the dental changes in sagittal and vertical dimensions were obtained by the following calculation:

  • T1 (Is-OLP) - T2 (Is-OLP) change in sagittal position of maxillary central incisor.
  • T1 (Ii-OLP) - T2 (Ii-OLP) change in sagittal position of mandibular central incisor.
  • T1 (Ms-OLP) - T2 (Ms-OLP) change in sagittal position of maxillary first molar.
  • T1 (Mi-OLP) - T2 (Mi-OLP) change in sagittal position of mandibular first molar.
  • T1 (Is-PP) - T2 (Is-PP) change in vertical position of maxillary central incisor.
  • T1 (Ii-MP) - T2 (Ii-MP) change in vertical position of mandibular central incisor.
  • T1 (angle between CIA and NSL) - T2 (angle between CIA and NSL) change in the angulation of upper canine root.
Therefore, a negative value with respect to linear sagittal and vertical measurements suggests a forward displacement of incisors, mesialisation of molars and extrusion of incisors. A negative angular measurement suggests a distal inclination of the canine root.

Linear measurements were performed with a 0.5 mm graduated steel ruler and all measurements were estimated to the nearest 0.5 mm and angular measurements were carried out with a protractor with an accuracy of one degree. The cephalograms were traced independently by two examiners who were blinded to whether the patients had received MBT or ROTH Prescription to reduce any observer bias. Cephalometric measurements were made twice by the two different operators to determine the repeatability of landmark identification and measurement techniques. All linear and angular variables had a coefficient of intrarater reliability (r = ∑ 2 total/∑ 2 between) between 0.85 and 1.00, thus this error was considered negligible. The statistical analysis was performed using the Wilcoxon signed rank test.


   Results Top


In MBT group, upper incisors retroclined during T1 - T2 with mean (SD) by 2.267 (±1.0032) mm and in ROTH group upper incisors proclined by -0.4 (±1.404) mm with statistically significant difference between groups (P=0.001). Lower incisors were retroclined in both groups; 2.4 (±0.98) mm in MBT and 0.06 (±1.48) mm in ROTH group, respectively. Statistical comparison between groups was in significant (P=0.072). Upper molar showed no mesial movement in MBT group and in ROTH group upper first molar showed a mesial movement of -1.133 (±0.351) mm. Statistical comparison was significant (P=0.03). Lower first molar in MBT group showed no anchorage loss while in ROTH group lower first molar showed a mesial movement of -0.002 (±0.05) mm. Statistical comparison between groups was insignificant (P=0.18). Upper incisors in MBT and ROTH group extruded by -0.867 (±0.611) mm and -0.9 (±0.507) mm with difference being statistically insignificant (P=0.964). Lower incisors extruded in MBT and ROTH groups by -0.067 (±0.703) mm and -0.133 (±0.639) mm, respectively, with difference being statistically insignificant (P=0.453). Upper canine in MBT group had a change in distal tip by -0.33° (±2.609) and in the Roth group the angulation of the upper canine increased by -3° (±3.184) and this difference was significant (P=0.004) [Table 1].
Table 1: Statistical comparison of horizontal, vertical changes and canine angulation between Group I (MBT) and Group II (ROTH)

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   Discussion Top


In the present study, there was a retroclination of upper and lower incisors with a mean SD value of 2.267 (±1.0032) mm, 2.4 (±0.98) mm, respectively, in group I (MBT) sample and upper incisors proclined by 0.4 (±1.404) mm in the group II (ROTH) sample. Retroclination of upper and lower incisors in group I (MBT) sample can be attributed to the presence of canine lace backs and reduced tip on the upper and lower canine bracket (8°, 3°) in the MBT 4 system as compared to ROTH 3 system which is characterized by an absence of lace back phenomenon and additional tip on upper canine bracket (13°) which augments the tendency to labial flaring of anterior teeth.

Group II (ROTH) sample showed a negligible retroclination of lower incisor by 0.06 (±1.48) mm. This greater anchorage control in the lower incisal segment in the anteroposterior direction could be due to greater molar anchorage control in the mandibular jaw base [11],[12] and further complimented by a reduced mesial tip on the lower anterior brackets (CI-2°, LI-2°, C-7°) in comparison to upper anteriors (CI-5°, LI-9°, C-13°) in the group II (ROTH) sample of patients. [3]

The results are in accordance with the previous studies by Usmani et al., Sueri et al., and T. Hosseinzadeh-Nik et al. who found that anterior segments retroclined when canine lace back ligatures were used in the appliance system. This can be explained by the force characteristics of lace back ligatures. Lace back ligatures when tied to the canines cause minimal distalization of crowns and the cuspid roots have enough rebound time to upright into the correct positions as the main arch wire takes into its position. [5] Hence, the incorporation of lace backs into the appliance system irrespective of the prescription used could be a means to prevent or minimize the horizontal anchorage loss in the incisal segment.

Horizontal anchorage in the posterior segment of upper and lower arches was well controlled in the group I (MBT) sample, where as in the group II (ROTH) sample there was a mesialisation of upper molars by 1.133 (±0.351) mm and lower molar moved mesially by 0.002 (±0.005) mm. The posterior anchorage control in group I (MBT) sample of patients could be due to reduced anterior tip, canine lace backs, which contribute to the generation of light interrupted reactionary forces in to the appliance system. Results from our present study support the fact from previous literature that interrupted impulses were better in minimizing the molar anchorage control need when compared to continuous forces which contributed to significant molar anchorage loss. [13]

On comparison with ROTH system, heavy continuous forces are generated and transmitted to posterior buccal segments during the forward inclination of canine crown and the remaining anterior teeth under the influence of an additional mesial tip (13°); thus, contributing to an anchorage loss in the molars. The results from the present study demonstrate that transpalatal bar is an ineffective means of anchorage control in the sagittal plane of space. [14],[15]

However, previous studies by Usmani et al. and Sueri et al. found no statistically significant difference for the mean mesial molar migration between lace back groups and non-lace back groups treated by the same system of pre-adjusted edge wise appliance. In the present study, the difference in the mean mesial molar migration between groups could be attributed to variation in the second order values on the anterior teeth between ROTH prescription and MBT prescription.

In the vertical dimension, the upper and lower incisors in both MBT as well as ROTH system showed extrusion and this could be explained as a factor brought about as a result of tip built into the cuspid brackets with the preadjusted edge wise appliance. Within the appliance systems, the maxillary anteriors showed more extrusion than the mandibular anteriors.

The present study shows the validity of lace backs in distalization of canines in the MBT system and there was a significant forward inclination of upper canines (3°) within the ROTH system. The results of our study are in accordance with previous studies by Hoffman and Way, [16] Ziegler and Ingerval [17] who had shown that rebound time provided to the cuspid roots by the lace back ligatures proved to be effective for canine distalization.

On the other hand, the concept of overcorrection integrated into the ROTH system is pronounced with the cuspid root tipping distally into the extraction spaces closer to the premolar root apices at the end of leveling and aligning phase of mechanotherapy.

The results from the present study demonstrate the third generation preadjusted edgewise appliance, the MBT system characterized by lace back ligatures in combination with reduced anti-tip and anti-rotation features placed less demand on anchorage control needs by minimizing the unwanted tooth movements in the anterior and posterior segments of the arch, right from the initial leveling and aligning phases of mechanotherapy.


   Conclusion Top


The following conclusions can be obtained from these in-vivo investigations:

A significant retroclination of upper and lower incisors occurred with MBT prescription after first phase of orthodontic mechanotherapy while there could be a proclination of labial segments with Roth prescription.

Mesial migration of the upper molars was evident in patient treated with Roth prescription hence reinforcement of molar anchorage is deemed to the necessary in the maxillary arch right from the onset of the orthodontic treatment.

ROTH prescription was characterized by significant forward inclination of the canines, while canine distalized into extraction spaces with no influence on incisal proclination in the MBT prescription.

 
   References Top

1.Andrews LF. The Straight wire appliance. Explained and Compared. J Clin Orthod 1976;10:174-95.  Back to cited text no. 1
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2.Roth RH. The straight wire appliance 17 years later. J Clin Orthod 1987;21:632-42.  Back to cited text no. 2
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3.McLaughlin RP, Bennett JC, Trevisi HJ. Systemised Orthodontic Treatment Mechanics. Edinburgh: Mosby; 2001. p. 101-2.  Back to cited text no. 3
    
4.McLaughlin RP, Bennett JC. Anchorage control during leveling and aligning with a preadjusted appliance system. J Clin Orthod 1991;25:687-96.  Back to cited text no. 4
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5.McLaughlin RP, Bennett JC. The transition from standard edge wise to pre-adjusted appliance systems. J Clin Orthod 1989;23:142-53.  Back to cited text no. 5
    
6.Usmani T, O'Brien KD, Worthington HV, Derwent S, Fox D, Harrison S, et al. A randomized clinical trial to compare the effectiveness of canine lacebacks with reference to canine tip. J Orthod 2002:29:281-6.  Back to cited text no. 6
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7.Sueri MY, Turk T. Effectiveness of Laceback ligatures on maxillary canine retraction. Angle Orthod 2006;76:1010-4.  Back to cited text no. 7
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8.Hosseinzadeh-Nik T, Farrokhzadeh AM, Golestan B. Horizontal Dental Changes during First Stage of Treatment Using the MBT Technique. J Dent Tehran Univ Med Sci 2007;4:9-14.  Back to cited text no. 8
    
9.Irvine R, Power S, McDonald F. The effectiveness of laceback ligatures: A randomized controlled clinical trial. J Orthod 2004:31;303-11.  Back to cited text no. 9
    
10.Pancherz H. The mechanism of class II correction in Herbst appliance treatment. A Cephalometric investigation. Am J Orthod 1982;82:104-13.  Back to cited text no. 10
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11.Graber TM, Vanarsdall AL, Vij KW. Orthodontics: Current principles and techniques. St. Louis, Missouri, Elsevier Mosby Inc;2004. p. 278.  Back to cited text no. 11
    
12.Evans TJ, Jones ML, Newcombe RG. Clinical comparison and performance perspective of three aligning arch wires. Am J Orthod Dentofacial Orthop 1998;114:32-9.  Back to cited text no. 12
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13.Daskalogiannakis J, McLachlan KR. Canine retraction with rare earth magnets: An investigation into the validity of the constant force hypothesis. Am J Orthod Dentofacial Orthop 1996;109:489-95.  Back to cited text no. 13
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14.Zablocki HL, McNamara JA Jr, Franchi L, Baccetti T. Effect of the transpalatal arch during extraction treatment. Am J Orthod Dentofacial Orthop 2008;133:852-60.  Back to cited text no. 14
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15.Kojima Y, Fukui H. Effects of transpalatal arch on molar movement produced by mesial force: A finite element simulation. Am J Orthod Dentofacial Orthop 2008;134:335-6.  Back to cited text no. 15
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16.Huffman DJ, Way DC. A Clinical evaluation of tooth movement along arch wires of two different sizes. Am J Orthod 1983;83:453-9.  Back to cited text no. 16
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17.Ziegler P, Ingervall B. A Clinical study of maxillary canine retraction with a retraction spring and with sliding mechanics. Am J Orthod Dentofacial Orthop 1989;95:99-106.  Back to cited text no. 17
[PUBMED]    

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Correspondence Address:
Ashok K Talapaneni
Department of Orthodontics and Dentofacial Orthopedics, Narayana Dental College and Hospital, Nellore, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.100423

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