|Year : 2016 | Volume
| Issue : 1 | Page : 31-41
Stability of skeletal changes induced by growth modulation procedures in the treatment of skeletal Class II malocclusion
Prashantha Govinakovi Shivamurthy1, Alireza Jafari2, Ashutosh Shetty3, Sadashiva Shetty Kandavara4
1 Professor, Department of Orthodontics, M S Ramaiah Dental College, Bengaluru, Karnataka, India
2 Associate Professor, Department of Orthodontics, Dental Branch, Islamic Azad University, Tehran, India
3 Professor, Department of Orthodontics, A B Shetty Memorial Institute of Dental Sciences, Mangalore, India
4 Professor and Head, Department of Orthodontics, Bapuji Dental College, Davanagere, Karnataka, India
|Date of Submission||04-Sep-2015|
|Date of Acceptance||01-Nov-2015|
|Date of Web Publication||4-Feb-2016|
Prashantha Govinakovi Shivamurthy
Department of Orthodontics, M S Ramaiah Dental College, MSRIT Post, New BEL Road, Bengaluru - 560 054, Karnataka
Source of Support: None, Conflict of Interest: None
Objective: Objective of this study, based on an evaluation of lateral cephalograms, was to evaluate the degree of skeletal changes produced by the various growth modulative procedures in the treatment of skeletal Class II malocclusion and to characterize the stability of these changes in the years after treatment. Materials and Methods: Total of 40 patients with Class II malocclusion was divided into three groups according to appliance used, i.e. removable or fixed functional appliances (n = 10), combination of functional appliance with headgear (n = 10), and only headgear (n = 10). In addition, almost a matched control group (n = 10) also characterized by skeletal Class II pattern and were under observation, for more than 2 years was also selected. Lateral cephalograms of each patient were taken at the start of treatment (T1), at its completion (T2), and long-term posttreatment (T3). Results: This study showed significant improvement in maxillomandibular relationship in treated group compared to control group, and the changes remained stable in posttreatment phase. Restriction of maxillary growth was evident in headgear and combination groups whereas significant forward movement of the mandible was seen in functional group. Conclusion: Analysis of lateral cephalograms indicates that growth modulation therapy in angle Class II malocclusion brings about desired skeletal changes which remain relatively stable over a long-term period.
Keywords: Functional appliances, growth modulation, orthopedic appliances, relapse, skeletal Class II, stability
|How to cite this article:|
Shivamurthy PG, Jafari A, Shetty A, Kandavara SS. Stability of skeletal changes induced by growth modulation procedures in the treatment of skeletal Class II malocclusion. J Indian Orthod Soc 2016;50:31-41
|How to cite this URL:|
Shivamurthy PG, Jafari A, Shetty A, Kandavara SS. Stability of skeletal changes induced by growth modulation procedures in the treatment of skeletal Class II malocclusion. J Indian Orthod Soc [serial online] 2016 [cited 2019 May 25];50:31-41. Available from: http://www.jios.in/text.asp?2016/50/1/31/175719
| Introduction|| |
Over the years, growth modulation for treatment of skeletal Class II malocclusion has been accepted, rejected, and again accepted, and presently it is looked at with skepticism. Most published studies of functional appliances state that it is impossible to correctly evaluate treatment effects or to compare treatment outcomes of various appliances because of a lack of sound study designs. ,
One such series of studies which questioned the efficiency of the growth modulation procedures are the randomized clinical trials of 1990's of University of North Carolina, University of Florida, and University of Pennsylvania. ,,, The data of these studies showed that, on an average, children treated with either headgears or functional appliances had a small but statistically significant improvement in their jaw relationships, while the untreated children did not. One of the striking findings, however, was the great variation within both the treated and the control groups. If the first question about growth modification treatment is, "Does it really modify growth?" the answer now can be, "Yes, though not always or to a large extent." The second question then must be, "Does early treatment really make any difference in the long run." By no means, all the children in the clinical trials responded as might have been expected. Why did some children respond well while others did not? Why did some children improve even without treatment while others got worse? These were the questions raised following the end of the phase "one" of the study. Not only these studies but many more studies ,, have ended with more questions than answers.
Watson  considers that proper differential diagnosis, specific treatment goals, necessary knowledge, and ability to reach these objectives in a predictable and stable manner are necessary for success of growth modulation therapy.
Growth modulation procedures, both functional as well as orthopedic treatment modalities and their combinations are commonly practiced in the Department of Orthodontics and Dentofacial Orthopedics in Bapuji Dental College and Hospital, for last 20 years. A sufficient number of successfully treated cases are available today, therefore, allowing us to understand the when, what, where, why, and how of growth modulation procedures applicable to the Indian population.
Therefore, an attempt is made here to study the effect of various growth modulation procedures and also to evaluate its long-term effects.
Aims of this study
- To evaluate the degree of skeletal changes produced by the various growth modulative procedures in the treatment of skeletal Class II malocclusion
- To characterize the stability of these changes in the years after treatment.
| Materials and Methods|| |
From 1989 to 1999, approximately 436 patients had undergone at least 6 months of growth modulation procedures in the Department of Orthodontics and Dentofacial Orthopedics, Bapuji Dental College and Hospital.
Many of them had reported back for follow-up, during which a new set of records were made. Of 134 patients who reported back for follow-up, a sample of 40 patients with complete set of records and of equal gender ratio was selected.
The study group comprised individuals who had been successfully treated by one of the types of growth modification appliance for the correction of Class II skeletal discrepancy many years back and had completed the postretention period of at least 2 years.
At the time of starting the treatment, all patients were at or just prior to the peak of their growth spurt, and there were no clinical signs of any major pathology or syndromes. Many of these patients had received postgrowth modulation fixed orthodontic treatment for the purpose of finishing and detailing. None of them had undergone any extractions (except for fully/partially impacted third molars) during the study period.
They were further grouped into four samples of 10 patients each.
Group I (control group): It consists of 10 patients and was selected from the longitudinal records of the Department of Orthodontics, Bapuji Dental College and Hospital.
The subjects in control group were characterized by almost a matched skeletal Class II pattern as that of treated groups and were under observation for more than 2 years.
Group II (functional group): It consists of 10 patients treated with either removable or fixed functional appliances such as activator, twin block, and Frankel or Herbst appliance. The mean posttreatment observation period was 3 years with range being 2.1-9.7 years.
Group III (functional + orthopedic group): It consists of 10 patients treated with a combination of functional and orthopedic appliances such as activator head gear and Bionator head gear. The mean posttreatment observation period was 3.3 years with range being 2.4-4.8 years.
Group IV (orthopedic): It consists of 10 patients treated with only orthopedic appliance-like splint head gear. The mean posttreatment observation period was 3.1 years with range being 2-8.1 years.
This grouping of treated samples and having a control group in this study was based on the suggestion from Parkin et al. 
The age group of these patients ranged from 8 years to 15 years, with a mean age of 11 years 6 months.
Except for minor modifications which were as per patient's requirements, patients treated with standard design of appliance were included in the study. However, to limit correction of malocclusion with tooth movements ("differential eruption"), only the patients with no trimming of the acrylic (for activator and twin block) were considered for the study. When necessary, a second removable appliance was constructed, or reactivation of fixed functional appliance was performed to achieve the desired results.
The present study was carried out on 20 lateral cephalograms of the control group and 90 lateral cephalograms of the treated cases. For the control group, only two lateral cephalograms were traced, i.e. the pretreatment lateral cephalogram (T1) and the long-term observation lateral cephalogram (T2). Whereas for the treated group, three profile cephalograms were traced, i.e., the pretreatment lateral cephalogram (T1), the immediate postgrowth modulation lateral cephalogram (T2), and the long-term postgrowth modulation lateral cephalogram (T3). The immediate postgrowth modulation records (T2) were taken when the angle Class I relationship was achieved during clinical examination. T3 cephalograms were taken at least a minimum of 2 years from the end of growth modulation phase (range was from 2 years to 9.7 years with a mean of 3.8 years).
All the lateral cephalograms were traced on 0.36 microns forted matte acetate with 0.3 mmHg lead pencil. The landmarks were traced by one investigator (PGS) and verified by a second author (AJ). Any discrepancies in landmark position were resolved by mutual agreement. The midpoint between the right and left images was used for bilateral landmarks.
Since some of the older cephalograms were taken with a different machine, the analysis included only angular measurements to eliminate magnification error. Angular measurements for skeletal, dental, and soft tissues were recorded to a nearest of 0.5°.
Robert M. Ricketts's new explanation for growth of human mandible in his article, "Principle of Arcial Growth of Mandible"  also explored in this study.
Error of the method
In order to assess the error of localizing the reference points and analysis procedure, 10 randomly selected tracings were retraced and re-measured after a month. The casual errors were assessed using Dahlberg's (1940) formula, and systematic errors were ascertained using paired t-test similar to the recommendation of Houston.  The casual errors of the method (Dahlberg's formula) did not exceed 0.77° or 0.56 mm.
Paired t-test demonstrated statistically significant systematic error differences in only three measurements (SNB, SN-GoMe, and incisor-mandibular plane angle [IMPA]).
The pretreatment cephalometric measurements of the four groups (T1) were compared using Student's t-test [Table 1]. Multiple group comparisons were provisionally done by one-way ANOVA F-test. Since the data were moderately skewed, a nonparametric method Mann-Whitney test was used for two-group comparisons. A P < 0.05 was considered statistically significant (S), P < 0.01 highly significant (HS), and P value more than 0.05 to be statistically insignificant (not significant). Continuous data are expressed as mean ± 1 standard deviation.
| Results|| |
Comparison of pretreatment cephalometric measurements (T1)
- The equivalence of the control and treatment groups was examined by comparing pretreatment cephalometric values
- At the beginning of the treatment, the facial convexity angle including the ANB and N-A-Pg angles showed a significant difference between the headgear and nonheadgear groups. The profiles of the nonheadgear group were straighter when compared to the headgear group
- Maxillary sagittal position when compared among the groups (i.e. SNA and S-N-SP), functional group showed slight retrognathism. Comparison of the vertical proportions (i.e. palatal plane to SN, angle of inclination, MP-SN, Jarabak ratio, and gonial angle) among the groups showed similar results
- The functional appliance and combination groups (Groups II and III), however, had more retrognathic mandible (SNB and SN-Pg) than the other groups
- The combination group and headgear group measured higher values for facial axis angle
- Significant differences were found mostly between the groups in soft tissue parameters. For example, soft tissue facial convexity angle were 22.4 ± 5.3 in the functional appliance-headgear group, significantly higher when compared to others. Nasolabial angle was 100.2 ± 11.9 in functional group, more obtuse compared to the other groups as well as control group
- Upper incisors showed more proclination, and the lower incisor were more retrognathic in functional group
- In arcial growth analysis, functional group showed significant smaller lower face height angle. Whereas functional and combination groups showed slightly higher mandibular arc angle.
Analysis of treatment effects (T1-T2)
Analysis of changes during retention phase (T2-T3)
- The average interval between the pre- and post-treatment/observation cephalograms (for controls) varied among the groups (33, 25, 16, and 18 months in control, functional appliances, functional-headgear group, and headgear group, respectively) [Table 2]
|Table 2: Difference in mean changes occurred due to growth alone or in combination with growth modulation treatments (T1-T2) |
Click here to view
- Maxilla to cranium: The results of the study showed a significant decrease in SNA and S-N-Sp parameters in functional + headgear combination group (SNA 1.6° and S-N-Sp 1.5° after deducting control group values) as well as with headgear group (SNA 2.9° and S-N-Sp 3.2° after deducting control group values). In control and functional group, there was no much change
- With respect to the relation of maxilla to cranium in vertical direction, there has been retro-rotation of maxillary plane in all three treated groups as evident by angle of inclination (1.8°, 1.6° and 1.7° in functional, functional + headgear, and headgear groups, respectively, after deducting control group values) and by palatal plane to SN (1.1° and 2.0° in functional + headgear and headgear groups, respectively, after deducting control group values)
- Mandible to cranium: A significant forward displacement of mandible in functional group as evident by SNB of 1.6° and SN-Pg of 1.3° after deducting control group values
- No change was observed in controls, functional + headgear, and headgear groups
- Furthermore, not much change was observed with respect to the relation of mandible to cranium in vertical direction
- Within the mandible: There was significant increase in gonial angle in combination of functional and headgear group (3.0° after deducting control group values) and significant decrease of the same in control group (−1.2 ± 1.4)
- Maxilla to mandible: An HS decrease in ANB and N-A-Pg values in headgear group followed by combination of functional + headgear and functional groups (ANB 3.0° and N-A-Pg 6.5° in headgear group, ANB 2.1° and N-A-Pg 4.4° in functional + headgear group, and ANB 1.7° and N-A-Pg 1.4° in functional group after deducting control group values) in comparison to control group which showed no change
- Dental: There was significant proclination of upper anterior in control group during observation period when compared to all treated groups which showed significant retroclination as evident from interincisal angle (9.4°, 13.9°, and 9.2° in functional, functional + headgear group, and headgear groups, respectively, after deducting control group values) and U1-NA (7.3°, 10.1°, and 0.2° in functional, functional + headgear group, and headgear group, respectively, after deducting control group values). Functional group showed slight proclination of lower anterior when compared to controls (L1-NB 0.4° of proclination and IMPA 2.7° of proclination in functional groups compared to control group values) whereas combination of functional + headgear and headgear groups showed retroclination during this period compared to controls. (L1-NB 3.0° and 5.9° of retroclination in functional + headgear group and headgear group, respectively, and IMPA 4.9° and 7.4° of retroclination in functional + headgear group and headgear group, respectively, compared to control group values)
- Soft tissue: There was slight acuteness of nasolabial angle in functional group compared to control (4.2° after deducting control group value) and functional + headgear and headgear groups showed obtuseness of nasolabial angle compared to control (4.8° and 0.6° after deducting control group value)
- Soft tissue facial convexity uniformly decreased in all three treated groups in comparison to control group (2.0°, 1.6°, and 1.5° in functional, functional + headgear, and headgear groups, respectively, after deducting control group value)
- Mentocervical angle significantly decreased in functional + headgear group (1.5° after deducting control group value), and headgear group showed increase in this angle (6.8° after deducting control group value)
- Arcial growth: The lower face height angle showed no significant change whereas mandibular arc angle showed substantial increase for functional group as evident with 2.3 ± 5.9 (2.0° after deducting control group value). This angle showed no significant change for other groups.
- The mean interval between the posttreatment to postretention cephalograms varied among the groups (3, 3.3, and 3.1 years in, functional appliances, functional-headgear, and headgear groups, respectively)
- In this analysis except the changes in U1-NA, none of the other parameters were statistically significant [Table 3]
- Maxilla to cranium: Results of this analysis showed almost no changes in sagittal position maxilla in all the treated groups
- Whereas the retro-rotation of maxillary plane in all three treated groups observed during treatment reverted slightly as evident by angle of inclination and by palatal plane to SN although it was not statistically significant
- Mandible to cranium: Significant forward displacement of mandible observed with functional group was undisturbed in postretention phase
- Mandibular plane became more horizontal, i.e., rotated anticlockwise in postretention period as evident with MP-SN and Jarabak ratio. This observation was more so with functional group and to a lesser extent in functional + headgear and headgear groups
- Within the mandible: The significantly increased gonial angle in combination of functional and headgear group reverted back in long-term (postretention phase). Decrease in gonial angle was also noted in other two treatment groups
- Maxilla to mandible: An HS decrease in ANB and N-A-Pg values seen in headgear group during treatment period continued in postretention phase also. The same improvement in combination of functional + headgear and functional group remained unchanged
- Dental: The significant retroclination of upper incisors in all the treated groups during treatment period reverted up to some extent as evident from interincisal angle and U1-NA. Lower incisors also demonstrated proclination in all treated groups in postretention period
- Soft tissue: The slight acuteness of nasolabial angle in the functional group and obtuseness in the headgear group as a result of treatment remained unchanged, but the obtuseness of this angle in functional + headgear group (7.4 ± 7.1) reverted to some extent (−2.2 ± 7.9)
- Decrease in soft tissue facial convexity in all three treated groups observed in postretention phase also though to a very little extent in headgear group
- All the treated groups demonstrated increase in mentocervicle angle. It was, in fact, reversal of the changes observed during treatment period in functional and combination groups in postretention phase
- Arcial growth: The lower face height angle in postretention period also showed no significant change whereas mandibular arc angle showed substantial increase for functional group (2.3 ± 5.9) previously during the treatment phase bounced back to some extent (−1.5 ± 4.6).
| Discussion|| |
Growth modulation has always remained a controversial subject with a wide spectrum of divergent views. One of the pitfalls of growth modulation therapy is its stability in the years after treatment [Table 4].
|Table 4: Difference in mean overall changes from pretreatment to post - retention period (T1-T3) |
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Wieslander and Buck,  Wieslander and Lagerström,  Watson,  McNamara and Bryan,  DeVincenzo,  Falck,  Hirschfelder and Fleischer-Peters,  Perillo et al.,  and Mills and McCulloch  with their study stressed the changes induced by growth modulative appliances and concluded that there is an overall picture of good stability with minor tendency for posttreatment changes.
In contrast to the above findings, Tuenge and Elder,  Melsen,  Pancherz and Fackel,  Livieratos and Johnston,  Dermaut and Aelbers, , and Tulloch et al.  with their study showed rapid cephalometric and histological changes following growth modulation were only temporary and tend to be diminished or eliminated by subsequent growth, and there has been acceleration but not true stimulation.
Hence, with these divergent schools of thought in mind, the present study has been conducted with the objective to evaluate the degree of skeletal changes produced by the various growth modulative procedures in the treatment of skeletal Class II malocclusion and to characterize the stability of these changes in the years after treatment.
Advantages in this study are having sample of only local "Davangere population" of uniform nature and having control group of untreated cases with "skeletal Class II malocclusion" (i.e., same as that of treated group) and not normal "skeletal Class I malocclusion" as in many previous studies. Furthermore, all the cases were treated by the group of doctors having same treatment philosophy unlike in many previous studies where the cases were treated by doctors of divergent philosophy [Figure 1] [Figure 2] [Figure 3] [Figure 4] [Figure 5] [Figure 6] [Figure 7] [Figure 8].
Maxilla to the cranium
The results of the present study showed a significant backward movement of maxilla in functional + headgear and headgear groups which have remained stable over the years. This confirms the orthopedic effect of the head gear. This result is in accordance with the study of Wieslander and Buck,  whereas in contrast to Tuenge and Elder,  Melsen,  Pancherz and Fackel,  Tulloch et al.,  and Dermaut and Aelbers. , In control and functional group, there was no change in maxillary position which is in accordance with Pancherz and Anehus-Pancherz,  and Perillo et al. 
The retro-rotation of maxillary plane in all three treated groups as evident by angle of inclination and by palatal plane has reverted partially in long-term. This finding was in accordance with works of Wieslander and Buck,  Tuenge and Elder,  and Melsen. 
Mandible to the cranium
There is significant forward displacement of mandible in the functional group as evident by SNB of 1.8 ± 1.6 and SN-Pg of 1.7 ± 1.5. No change was observed in other groups. In long-term, the forward displacement of mandible, though to a very less extent, was observed in all treated groups which can be interpreted as late mandibular growth. This finding is in accordance with Melsen,  McNamara and Bryan,  DeVincenzo,  Falck,  Perillo et al.,  Mills and McCulloch  and is in contrast to the findings of Pancherz and Fackel (1990),  Wieslander,  and Tulloch et al. 
Coming to the vertical relationship of the mandible to the cranium, all three treated groups showed mild opening of mandibular plane (retro-rotation) immediately after treatment, whereas controls showed no change. In long-term, all treated groups showed strong auto-rotation of mandible. This finding is in accordance with works of Hans Pancherz (1977)  and Melsen. 
There was slight closure of facial axis in functional and head gear group; whereas in combination group, there was slight opening. However, in long-term, all treated groups showed closure of facial axis, whereas no change was observed in controls.
Within the mandible
Another significant observation was made in gonial angle. Very small change observed in the head gear group, whereas combination group showed substantial change toward vertical growth pattern immediately posttreatment and controls showed a change toward horizontal growth pattern. However, in long-term, all three treated groups showed a significant change indicating anterior rotation of mandible. This finding is again in accordance with studies of Pancherz  and Melsen. 
Coming to an another important parameter, i.e. ANB, all three treated groups showed significant decrease in ANB angle indicating a strong normalization of sagittal jaw discrepancies immediately posttreatment whereas controls showed no change. In long-term, all treated groups showed further improvement in jaw discrepancy, as discussed earlier indicating late mandibular growth. This is in accordance with works of Wieslander and Buck,  Wieslander and Lagerströöm,  Hansen and Pancherz,  Perillo et al.  and in contrast to studies of Pancherz and Fackel,  Tulloch et al.,  and Dermaut and Aelbers. ,
Coming to Jarabak ratio, there was no significant change between pre- and immediate post-treatment in both controls and treated groups. Whereas in long-term evaluation, all three treated groups showed a significant change in Jarabak ratio which shows forward rotation of mandible.
There was significant decrease in the interincisal angle for the control group resulting in more proclination of the teeth, whereas results have showed increased angulation for all the treated groups resulting in more retroclination of anteriors. However, all the treated groups showed decreased values in long-term which can be interpreted as a result of the second phase of treatment with fixed mechanotherapy.
Coming to relative inclination of upper incisors, given by U1-SN, there was significant change in the functional and the combination groups indicating more retroclination of upper incisors whereas controls and head gear groups showed very minimal changes. However, in the long run, in both functional and combination groups changes reverted leading to more proclination as discussed earlier which can be interpreted as result of the second phase of treatment, whereas the head gear group showed continued retroclination.
However, when the same upper incisors were compared to NA line, controls and headgear groups showed slight proclination; whereas the functional and combination groups showed retroclination. However, in long-term, the combination group showed reversal of the change.
Coming to lower incisors, controls and functional groups showed slight proclination of lower incisor and combination and head gear groups showed retroclination. However, in the long-term, all treated groups showed proclination of lower anteriors.
There were expected changes among dental parameters immediately posttreatment. However, in the long-term, the dramatic changes can be attributed to the second phase of fixed mechanotherapy which was done for final finishing and detailing.
In soft tissue evaluation, results showed that there was no significant change in nasolabial angle controls and functional group immediately after the growth modulation and also in the long-term. However, the combination and head gear groups showed an increased nasolabial angle immediately posttreatment. In the long-term results, this angle was quite stable in headgear group; whereas in the combination group, it slightly reverted back.
Coming to the soft tissue facial convexity, controls showed no change; whereas treated groups showed substantial decrease of facial convexity. In long-term, the convexity further decreased which can be interpreted as late mandibular growth and the soft tissue growth.
Nasomental and mentocervical angles showed no significant changes immediate posttreatment and also in long-term for all groups.
The lower face height angle showed no significant change; whereas mandibular arc angle showed substantial increase for functional group which has reverted back partially in long-term. This angle showed no significant changes for other groups.
| Summary and Conclusion|| |
Significant backward movement of maxilla in the functional + headgear and head gear groups and forward movement of mandible seen in the functional group immediate postgrowth modulation have remained stable in long-term. All the treated groups showed significant decrease in the ANB angle and soft tissue facial convexity posttreatment which continued in the long-term posttreatment period. The retro-rotation of palatal plane which was seen immediate posttreatment in all the treated groups and increase in nasolabial angle found in the combination and headgear groups reverted partially in long-term posttreatment. All the treated groups showed mild opening of mandibular plane immediately posttreatment, which in the long-term showed strong closure in all groups. Retroclination of upper and lower incisors seen postgrowth modulation in various groups reverted back in long-term evaluation. In arcial growth, mandibular arc angle showed substantial increase for the functional group immediate postgrowth modulation reverted back partially in the long-term.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2], [Table 3], [Table 4]