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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 9  |  Issue : 2  |  Page : 111-117

Evaluation of the effects of distal malocclusion activators on the craniofacial complex


1 Department of Pediatric Stomatology, Azerbaijan Medical University, Baku, Azerbaijan
2 Private Practice, Istanbul, Turkey
3 Department of Orthodontics, Faculty of Dentistry, Biruni University, Istanbul, Turkey

Date of Submission27-Dec-2021
Date of Decision28-Feb-2022
Date of Acceptance23-Mar-2022
Date of Web Publication22-Aug-2022

Correspondence Address:
Hakan Gurcan Gurel
Department of Orthodontics, Faculty of Dentistry, Biruni University, Istanbul
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdrr.jdrr_196_21

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  Abstract 


Introduction: Class II malocclusions are the most commonly seen, and therefore, the most commonly treated type of anomalies. Dental and skeletal factors are involved in the development of Class II malocclusions. The purpose of this study was to investigate whether or not there were any changes in the increased cranial base angle and cranial base dimensions, which have been reported to be among the morphological characteristics of Class II malocclusions, with functional orthopedic treatment and to evaluate effects of these changes on facial structures. Materials and Methods: The study was conducted on hand-wrist radiographs and lateral cephalometric radiographs of 50 patients taken at the beginning and at the end of treatment. The control group comprised 17 patients and the treatment group comprised 17 patients who were treated with a Class II division 1 activator and 16 patients who were treated with a combination of Class II division 1 activator and an Occipital Headgear (Hg). Results: Among the measurements for cranial base dimensions, only the increase in S-N in the treatment group was smaller than that in the control group. No significant differences were found among groups regarding the values of NSBa and NSAr angles, which are known to be cranial base angles. Conclusion: The increase in the S-N dimension being smaller in the treatment group brings about the idea that the activator treatment may influence maxillary development and consequently the nasomaxillary complex.

Keywords: Activator, distal malocclusion, functional treatment


How to cite this article:
Novruzov Z, Behruzoglu M, Gurel HG. Evaluation of the effects of distal malocclusion activators on the craniofacial complex. J Dent Res Rev 2022;9:111-7

How to cite this URL:
Novruzov Z, Behruzoglu M, Gurel HG. Evaluation of the effects of distal malocclusion activators on the craniofacial complex. J Dent Res Rev [serial online] 2022 [cited 2022 Dec 8];9:111-7. Available from: https://www.jdrr.org/text.asp?2022/9/2/111/354201




  Introduction Top


Class II malocclusions are the most commonly seen, and therefore, the most commonly treated type of abnormalities. It was reported by ingerval that approximately 12% of orthodontic abnormalities consisted of Class II division 1 malocclusion, while Kim reported their prevalence as 49%.[1],[2] Dental and skeletal factors are involved in the development of Class II malocclusions. Both maxillary protrusion and mandibular retrusion are evident in the development of skeletal Class II malocclusions. However, it has been reported that Class II anomalies generally result from mandibular retrusion.[3]

Jakobsson stated that 30%–35% of all the Class II division 1 anomalies were orthopedically treated, whereas this rate was reported as 40% by Weislander and 1/3 by Creekmore and Radney.[4],[5],[6]

It has been proven in animal studies that it is possible to achieve skeletal changes by forcing the mandible to have an anterior position. For this reason, the treatment strategies for Class II anomalies often consist of mandibular growth stimulation. These treatment types are applied by using functional appliances.[7]

Functional appliances direct the force of a certain muscle group toward the basal bone through the dentition, by changing the function and position of the mandible. Forces are often generated by changing the mandibular position in sagittal and vertical directions. It has also been reported that osseous development is stimulated by soft tissue tensions.[7],[8]

Woodside did not agree with the notion that functional appliances produced orthopedic effects.[9] The answer to the question whether or not modification of mid-facial development and mandibular growth is possible with functional appliances is still controversial. Extensive histological and clinical research is necessary to prove that it is clinically possible to stimulate mandibular growth by using functional orthopedic appliances. The number of studies in orthodontic literature, which prove that such an effect exists, is growing in number.[10],[11],[12]

Various relationships between the angle of the cranial base and malocclusions can be observed in research studies on the cranial base.[13],[14],[15],[16]

Both maxillary and mandibular positions are closely related to the cranial base. Changes in the cranial base affect the maxilla through the nasomaxillary suture and the mandible through the glenoid fossa. In fact, the maxilla is affected to a higher extent by changes in cranial base, as it has a motionless connection with the cranial base. In particular, palatal bone plays a developmental role between the sphenoidal and the maxillary bones, consequently resulting in lowering of the maxilla.

The importance of the angular and dimensional changes in the cranial base on the maxillo-mandibular relationship can be observed in studies that have been performed. That is, the cranial base is one of the determining factors in the establishment of facial types.[15],[16],[17],[18]

Authors often state that reduction of the cranial base angle and the protrusive and downward movement of the glenoid fossa would result in mandibular protrusion, whereas the increase in the cranial base angle and the retrusive movement of glenoid fossa would result in mandibular retrusion.[13],[14],[15],[16],[19]

The purpose of this study was to investigate whether or not there were any changes in the increased cranial base angle and cranial base dimensions, which have been reported to be among the morphological characteristics of Class II malocclusions, with functional orthopedic treatment and to evaluate the effects of these changes on facial structures.


  Materials and Methods Top


The study was conducted on hand-wrist radiographs and lateral cephalometric radiographs of a total of 50 patients from the archives of Ankara University School of Dentistry, Department of Orthodontics, 17 of whom were treated with a Class II division 1 activator and 16 of whom were treated with a combination of Class II division 1 activator and an Occipital Headgear (Hg). The lateral cephalometric radiographs obtained from a total of 17 patients served as a control group and were traced at a time interval, thereby making it possible to evaluate the changes that had occurred in growth and development together with hand-wrist radiographs which were used in determining the developmental stages during the period when cephalometric tracings were performed. The information on study group and control group is shown in [Table 1].
Table 1: Age and development values of individuals in the activator, activator Hg, and control groups at the beginning and at the end of treatment/control

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The following criteria were considered in the selection of patients who constituted the study group:

  1. Having a skeletal Class II abnormality (ANB angle to be 4° or greater),
  2. Showing a bilateral Angle Class II occlusal relationship,
  3. Having an overjet of over 4 mm,
  4. Being within the correct period of growth and development.


To assess the hand-wrist developmental periods of the patients in the treatment and control groups, skeletal maturation periods were numerically coded using numbers from 1 to 9.[20]

Reference points were marked on an acetate paper placed over the cephalometric radiographs, and the coordinates of these reference points were transferred to a computer using a digitizer with ± 0.25 senstivity (Genius Newsketch 1212) and calculated using the Purpose on Request Digitizer Input Output System software. The magnification factor was not taken into consideration on the measurements.

Statistical analysis

The following statistical analysis methods were used in this study:

  1. Student t-test and analysis of variance technique on a factorial basis were used to determine whether there were any differences between the genders within the groups with regard to developmental values at the beginning and at the end of treatment/control periods
  2. Cephalometric points on the radiographs of a total of 20 individuals randomly selected from treatment and control groups were re-marked 4 weeks after the initial application and digitalization
  3. Analysis of Variance was applied between the beginning and end of treatment/control values of treatment and control groups
  4. Analysis of Variance and Duncan tests were applied to evaluate the differences between the beginning and end of treatment/control values of the treatment and control groups.



  Results Top


No gender discrimination was applied, as the differences between genders regarding development at both the beginning of treatment/control and at the end of treatment/control were not statistically significant according to the results of the Analysis of Variance on a Factorial Basis applied at the beginning of treatment/control and at the end of treatment/control regarding groups and gender.

Evaluation of the method error

All markings and measurements made on the lateral cephalometric radiographs of a total of 20 patients randomly selected from 50 individuals in treatment and control groups were repeated 4 weeks after the initial application, and primary and secondary measurements were then compared and the correlation coefficients within groups “r” were calculated to assess individual drawing and measurement error levels.

When the mean values of the differences between the dimensions of the posterior cranial base (S-Ba), the total cranial base (N-Ba) and S-SOS, which were measured at the beginning and at the end of treatment/control were compared, it was observed that the values were similar among the groups [Table 2].
Table 2: Mean values, standard errors, analysis of variance, and Duncan test results of the differences in cephalometric measurements used in the study between the beginning and end of treatment/control (A: Activator, B: Activator Headgear, C: Control Group)

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The mean values of the anterior cranial base (S-N) measurements obtained during treatment/control showed statistical differences at a significance level of P < 0.05 among groups and this difference was observed between treatment and control groups. The increase in this measurement within the control group was greater when compared to those obtained in the treatment groups [Table 2].

The mean values of differences in S-Ar, S-Co, and SOS-Ba dimensions, which were obtained during treatment/control were similar among groups.

The mean values of differences in the perpendicular distances from point N to the HR plane (N-TW), and those from points N, Ba, and SOS to the VR plane (SOS-T Vert), (Ba-T Vert), (N-T Vert), which were obtained during treatment/control were found to be similar among groups [Table 2].

When the mean values of differences in measurements of the perpendicular distance from point SOS to the HR plane (SOS-TW) and the perpendicular distance from point Ba to the HR plane (Ba-TW), which were obtained during treatment/control were compared, a statistically significant difference among the groups was observed. The difference was at a significant level of P < 0.05 for SOS-TW and P < 0.01 for Ba-TW, which resulted from a greater change within the control group.

When the mean values of the differences in measurements of the perpendicular distance from point A to the VR plane (A-T Vert), which were obtained during treatment/control were compared, a statistical difference at a significance level of P < 0.05 was found among the groups. Slight increases were observed in both treatment groups for this measurement, which shows the position of the maxilla on the sagittal direction, whereas an increase was observed in the control group.

The mean values of the differences in the angles between the HR plane and the anterior cranial base (TW/SN) and the Frankfort horizontal plane (TW/FH), which were obtained during treatment/control, were similar among the groups [Table 2].

The mean values of the differences in NSBa and NSAr angles, which were obtained during treatment/control were similar among the groups [Table 2].

The mean values of differences in the NSCo angle which were obtained during treatment/control showed a decrease in all groups; however, a statistical difference at a significance level of P < 0.05 was observed between activator Hg combination group and the control group [Table 2].

The mean values of differences in WTSOS, WTAr, and WTBa angles, which were obtained during treatment/control were similar among the groups [Table 2].

The mean values of the differences in the WTCo angle which were obtained during treatment/control showed a decrease in all groups. A statistical difference at a significance level of P < 0.01 was observed between the treatment and the control groups [Table 2].


  Discussion Top


In this study, it was investigated whether or not the monoblock-type activator and a combination of the activator and Hg for treatment of individuals with skeletal and dental Class II malocclusion had any influence on the cranial base angle and dimensions, and if so, the relationship of these changes with characteristic features of facial structure underwent evaluation.

The same criteria with those used in the selection of individuals in the treatment group were used in the selection of individuals for the control group. That is, attention was paid to the treatment and control groups so that they would include individuals with similar craniofacial skeletal structure. The reason for using the superposition method in this study was that it is impossible to distinguish changes which occur either with growth and development or with the influence of treatment with this method. It has previously been mentioned that similar craniofacial structures were considered in the selection of individuals for treatment and control groups. It was assumed that changes resulting from activator treatment could be distinguished from growth and developmental changes by forming groups and making measurements from reference planes created from constant points.

It was observed in this study that the S-N dimension showed a lower degree of increase in both treatment groups when compared to those in the control group [Table 2]. That is, the dimensional increase of the anterior cranial base is decreased by activator treatment. Assuming that the sella region is more stable, it can be stated that activator treatment would affect the Nasion region. To relate the changes occurring in the Nasion region with the influence of the activator treatment, it would be sufficient to remember that the nasomaxillary complex is unitary during the postnasal period. As a matter of fact, it was observed that point A showed a sagittally retrusive motion in both treatment groups, whereas it moved in a protrusive direction in the control group, in accordance with the A-T Vert measurements regarding the maxilla (P < 0.01) [Table 3], [Table 4], [Table 5]. This indicates that maxillary development is restrained by the activator. Although statistically insignificant, a decrease in the SNA angle in the treatment groups and an increase in the SNA angle in the control group were observed, which showed a sagittal position of the maxilla. In our findings regarding the S-N plane, it was observed that this dimension showed a lower degree of increase in the activator treatment group. This finding is in accordance with the statement that maxillary development is restrained by the activator. Accordingly, it is highly probable that restrained maxillary development is the factor that prevents the increase of the S-N plane. That is, the influence of activator over the maxilla is observed in the nasomaxillary complex. It has been reported that the S-N dimension is affected by the remodeling process in the Nasion region.[21],[22] The situation that the protrusive movement of point A (A-T Vert) in the control group at a statistically significant level could not be determined with the SNA angle in accordance with our vertical reference plane may be related with the dimensional increase in the S-N plane within the control group. Such that, the protrusive movement of point N is not restrained in the control group; therefore, the extent of movements of points A and N in the sagittal direction occur at similar levels. For this reason, protrusive movement of point A is not reflected on the SNA angle.
Table 3: Mean values, standard errors, and t-test results of cephalometric measurements used in the study for the activator group at the beginning and end of treatment

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Table 4: Mean values, standard errors, and t-test results of cephalometric measurements used in the study for the activator Hg group at the beginning and end of treatment

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Table 5: Mean values, standard errors, and t-test results of cephalometric measurements used in the study for the control group at the beginning and end of treatment

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Changes in the dimensions S-Ba, N-Ba, SOS-Ba, S-SOS, S-Ar, and S-Co were observed to be similar among the groups [Table 2]. Unlike the anterior cranial base, the activator did not have any influence on the posterior cranial base and the cranial base dimensions. The lack of any changes in the posterior cranial base dimensions may be related to the fact that most of the development of SOS, which consists of the only cartilage structure in that area, is completed during the earlier phases. It is known that Clivus and SOS are responsible for the changes in S-Ba dimension.[21]

The finding that no significant difference was observed among the groups in the mean values of differences in NSBa and NSAr angles which were obtained during treatment/control period in this study indicates that activator treatment does not change these angles [Table 2]. Identical findings were obtained for WTAr and WTBa angles. In fact, as there are studies in which the glenoid fossa has been reported to be dragged retrusively with activator treatment,[12] it could be expected that point Ba would be affected by the glenoid fossa. It is also known that due to the growth process in the spheno-occipital synchondrosis, part of the cranial base which is in front of SOS remains stable, while the part behind it moves retrusively in a downward direction.[21],[23] However, the fact that this movement could not be determined in our study may be due to the reason that the time interval between cephalometric radiographs, which were obtained at the beginning of treatment/control and at the end of treatment/control, being relatively short.

The mean values of changes in NSCo during treatment/control period in this study showed a decrease in both the treatment and the control groups [Table 3], [Table 4], [Table 5]. This decrease was statistically significant only in the control group [Table 5]. The same findings apply for the WTCo angle (P < 0.01). This situation results from the relocation of the condyle. These findings also indicate that activator treatment results in a positional change in the mandible, rather than a dimensional change. However, the high rate of decrease in the WTCo angle in the control group is contradictory. Therefore, it is only necessary to keep in mind that protrusive activation of the mandible is implemented to divert recent condylar development in the posterior direction.

A higher rate of decrease in the ANB angle was observed in the treatment groups when compared to those in the control group [Table 2]. This difference was also found to be statistically significant (P < 0.01). This finding may result from the anterior cranial base and the maxillo-mandibular relationship because changes in the S-N dimension were also observed with activator treatment [Table 2]. According to our findings, the decrease in ANB angle is influenced by both a decrease in SNA angle and an increase in SNB angle.

A statistically significant level of decrease was observed in Wits measurements for both treatment groups, when compared to those in the control group in our study (P < 0.001). No statistically significant changes were observed in either the Wits measurements or the ANB angles [Table 3], [Table 4], [Table 5]. The improvement in maxillo-mandibular relationship with the influence of activator treatment and combination of activator and headgear treatments can be identified from both angular and dimensional measurements.


  Conclusion Top


Among the N-Ba, S-N, and S-Ba measurements for cranial base dimensions, only the increase in S-N in the treatment groups was lower compared to that in the control group.

No significant differences were found among groups regarding the values for NSBa and NSAr angles, which are known to be cranial base angles, and the values for WTAr and WTBa angles used in this study. This shows that no changes occur in the cranial base inclination with activator treatment.

Changes in S-SOS, SOS-Ba, and S-Ba dimensions were similar among the groups. This shows that the activator treatment has no influence on SOS development.

The decrease in the ANB angle within the treatment groups is influenced by both the decrease in the SNA angle and the increase in the SNB angle.

Ethical clearance

A non-invasive ethical approval was granted for this study by the Ethical Committee of Faculty of Dentistry, Ankara University.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Jakobsson SO. Cephalometric evaluation of treatment effect on Class II, Division I malocclusions. Am J Orthod 1967;53:446-57.  Back to cited text no. 4
    
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Wieslander L. The effect of force on craniofacial development. Am J Orthod 1974;65:531-8.  Back to cited text no. 5
    
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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