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ORIGINAL ARTICLE
Year : 2015  |  Volume : 4  |  Issue : 2  |  Page : 97-102

Evaluation of treatment changes produced by different orthodontic treatment modalities using Peer Assessment Rating (PAR) index


1 Department of Orthodontics, Meghna Institute of Dental Sciences, Nizamabad, India
2 Department of Pedodontics, Kamineni Institute of Dental Sciences, Narketpally, Nalgonda, Telangana, India

Date of Web Publication12-Jun-2015

Correspondence Address:
Seena Naik Eslavath
Department of Orthodontics and Dentofacial Orthopaedics, Meghna Institute of Dental Sciences, Nizamabad, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2277-8632.158584

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  Abstract 

Background: The assessment of treatment outcome has been an important facet of the orthodontic specialty for several decades. Generally, the orthodontic outcome is graded subjectively or by some objective method of evaluation in the clinical setting or of the study groups. The individual grading of one's own treatment results can be a self-educating exercise to improve the quality of care. Unfortunately, the variation in the criteria used by different orthodontists makes it difficult to compare the results
Materials and Methods: A sample of 150 treated cases was divided into three groups as follows: Group A (n = 50) treated with edgewise mechanotherapy, Group B (n = 50) treated with light wire mechanotherapy, and Group C (n = 50) treated with functional appliance therapy. All the three groups were analyzed using Peer Assessment Rating (PAR) index. The degree of improvement in each case was categorized into three as worse-no improvement, improved, and greatly improved.
Statistical analysis used: Chi-square test was used for comparison within groups and one-way analysis of variance (ANOVA) for comparing treatment improvement between groups.
Results: All the three groups showed significant overall improvement after treatment. However, the patients in edgewise group demonstrated greater degree of overall improvement in comparison to the rest.
Conclusions: The PAR index appeared to be sensitive enough to determine the difference in outcome between the techniques used in this study.

Keywords: Orthodontic therapy, peer Assessment rating index, treatment outcome


How to cite this article:
Eslavath SN, Mood TN, Narahari KA, Chekka M, Natta S. Evaluation of treatment changes produced by different orthodontic treatment modalities using Peer Assessment Rating (PAR) index. J NTR Univ Health Sci 2015;4:97-102

How to cite this URL:
Eslavath SN, Mood TN, Narahari KA, Chekka M, Natta S. Evaluation of treatment changes produced by different orthodontic treatment modalities using Peer Assessment Rating (PAR) index. J NTR Univ Health Sci [serial online] 2015 [cited 2020 Aug 15];4:97-102. Available from: http://www.jdrntruhs.org/text.asp?2015/4/2/97/158584


  Introduction Top


The assessment of treatment outcome has been an important facet of the orthodontic specialty for several decades. To overcome the subjective difference and to ensure uniform interpretation and application criteria, several indices have been developed. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12] However, none has enjoyed universal acceptance. The Peer Assessment Rating (PAR) index was introduced by Richmond et al. in 1992 for assessing the treatment outcome in a quantitative manner. The index was formulated over a series of six meetings in 1987 with a group of 10 experienced orthodontists (British Orthodontic Standard Working Party). [10] It is a valid and reliable index of malocclusion that offers uniformity, objectivity, and standardization in assessing the outcome of orthodontic treatment. [10],[13],[14]

There are two methods of assessing improvement by using PAR index: [14] reduction in weighted PAR score and percentage reduction in weighted PAR score. The PAR index records malocclusion at any stage of treatment, and it is flexible because it allows the improvement to reflect in the treatment standards.

The present study was carried out to evaluate and compare the treatment outcomes in edgewise, light wire, and functional appliances therapy using the PAR index.


  Materiala and Methods Top


The study was carried out on a sample size of 150 sets of pre-and post-treatment study models representing all types of malocclusion selected from the record of orthodontic clinic.

The entire sample was divided equally into three groups As follows:

Group A: 50 cases treated with edgewise mechanotherapy

Group B: 50 cases treated with light wire mechanotherapy

Group C: 50 cases treated with functional appliance therapy

The upper and lower anterior segments (UAS, LAS), right and left buccal occlusion (RBO, LBO), overjet (OJ), overbite (OB), and center line (CL) were recorded in each pre- and post-treatment study model using the PAR ruler [Figure 1]. [10],[15] The individual components were summed up to give the overall score. The change in total score or percentage of change in the score between pre- and post-treatment models reflected the success of treatment in achievement of overall alignment and occlusion. The individual traits were weighed according to Richmond et al.[10],[15]
Figure 1: PAR rule

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Two methods were used for assessing the treatment improvement. Using the nomogram, the pre-treatment weighted PAR scores are read on the horizontal axis and the post-treatment weighted scores are read on the vertical axis. The scores for the pre- and post-treatment cases are read on their respective axis and the point where the intercept falls indicates the degree of improvement. Percentage improvement also reflects the change relative to the pre-treatment score, but gives a more sensitive assessment than the nomogram, which only provides three broad bands of treatment change.


  Results Top


Fifty subjects (n = 50) in each group were taken into consideration for calculating the mean PAR score change (T1-T2). However, for the calculating percentage reduction in PAR score, the cases having equal pre-treatment (T1) and post-treatment (T2) scores were not considered because no statistics could be applied for the value of zero.

Treatment changes in edgewise group (Group A)

Assessment of improvement: After treatment, 66.0% of the cases fell in the greatly improved category, 30% cases were improved, and 4% of cases showed worse or no improvement.

Overall treatment changes (weighted PAR score): For the edgewise group, the mean pre-treatment PAR score was 31.46 and the post-treatment PAR score was 7.46, with a mean PAR score change (T1-T2) of 24.0. The percentage in overall improvement in PAR score was 76.3%, which is statistically highly significant (P < 0.001) [Table 1].
Table 1: Treatment Changes in Different Par Score Components in Edgewise Group


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Treatment changes in the light wire group (Group B)

Assessment of improvement: After treatment, 62.0% of the cases fell in the greatly improved category, 26.0% cases were improved, and 12.0% of cases showed worse or no improvement.

Overall treatment changes (weighted PAR score): For the light wire group, the mean pre-treatment (T1) PAR score was 26.98 and the mean post-treatment (T2) PAR score was 5.62, with a mean PAR score change (T1-T2) of 21.36. The overall improvement in PAR score was 69.8%, which is a statistically highly significant (P < 0.001) improvement [Table 2].
Table 2: Treatment Changes in Different Par Score Components in Light Wire Group


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Treatment changes in functional group (Group C)

Assessment of improvement: After treatment, 36.0% of the cases fell in the greatly improved category, 54.0% cases were improved, and 10.0% of cases showed worse or no improvement.

Overall treatment changes (weighted PAR scores): For the functional group, the mean-pre-treatment (T1) PAR score was 30.56 and the mean post-treatment (T2) PAR score was 10.64, with a mean PAR score change (T1-T2) of 19.92. The overall improvement in the functional group by PAR score was 65.14%, which is statistically highly significant (P < 0.001) [Table 3].
Table 3: Treatment Changes in Different Par Score Components in The Functional Group


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  Discussion Top


The beginning of objective assessment of orthodontic treatment is linked to objective assessment of recording the prevalence and severity of malocclusion. [10],[15] A number of scoring systems have been used for standardized assessment of malocclusion. [16] These scoring systems were later used to record the malocclusion on pre-treatment and post-treatment study models to assess the treatment need and treatment improvement. [15],[17]

Several indices have been developed especially for the objective assessment of treatment outcome on pre- and post-treatment study models. However, the reliability and validity of the indices used by Eishman (1974) [1],[2] and Gottilieb (1975) [5] have never been evaluated. The Treatment Need Index [18] and the Occlusal Index by Summers (1969) [6],[7] have been used by several authors to assess the treatment outcome. [4],[3],[9] Summers' index has been found to have least amount of bias, is best correlated with the clinical standard and is most valid presently, but it has some shortcomings. [9],[19]

Tang and Wai, in a study to assess the treatment effectiveness of orthodontic appliances, concluded that Summers' occlusal index is not ideal for measuring treatment effects of orthodontic appliance because it does not take into account residual or extraction spaces, and mesiodistal or buccolingual tooth inclination. [17]

To overcome the limitations of the existing outcome indices, Richmond et al. [10] developed the PAR index. This index can record the malocclusion at any stage of treatment. This index is specially designed to measure the occlusal changes that are derived from the patient pre- and post-treatment study models. [10],[14],[15]

Some of the factors that could influence the standard of orthodontic treatment are:

  1. Experience of the practitioner;
  2. Orthodontic qualification of the practitioner;
  3. Practitioners categorized related to case load;
  4. Type of appliance used; and
  5. Reason from where the estimate arose. [19],[20]


Treatment effectiveness and treatment results

The overall mean reduction in weighted PAR scores in the edgewise group (Group A) was 76.3%. The treatment results showed that the cases treated by edgewise appliance (Group A) had a better outcome and resulted in distribution to the great improvement category, which indicated a high standard of treatment. In our study, after treatment, 66.0% of the cases were greatly improved, 30% cases improved, and 4% cases showed no improvement. In a study in Britain, Richmond et al. found 71.4% mean reduction in weighed PAR score when upper and lower fixed appliances were used by general dental practitioners. Their study showed lesser improvement in treatment outcome compared to the present study.

In the light wire group (Group B), the overall mean reduction in weighed PAR score was 69.8%. Buchanan et al. reported in their study that cases treated with Begg appliance showed an overall improvement of 65% in weighted PAR score change. [21] In our study, after treatment, 62.0% of the cases fell into the greatly improved category, 26.0% improved, and 12.0% cases showed worse or no improvement. The treatment results showed that cases treated with light wire appliance had better outcome in our hospital (Group B) compared to those in the UK.

In the functional appliance group (Group C), the overall mean percentage improvement indicated by weighted PAR score was 65.14%. This resulted in a distribution to the improved category. After treatment, 36% of the cases fell into the greatly improved category, 54% improved, and 10% cases showed worse or no improvement. In his study of cases treated with functional appliance, Fox found the mean percentage improvement in weighed PAR score was 72.3%. [18] The cases treated by functional appliance (Group C) showed overall better treatment outcome, as these cases required major treatment for sagittal correction by reduction in the OJ only.

Comparison of the three different appliance types showed that the edgewise group achieved a significantly greater reduction in weighted PAR score change (76.3%) than the light wire (69.4%) and functional (65.9%) groups. The cases with a high PAR score prior to treatment tended to fare better in terms of percentage reduction. It indicates that the mean reduction of weighed PAR score is related to the pre-treatment PAR score.

Anterior segment

The treatment changes in the upper anterior segment as shown by weighted PAR score in the edgewise (Group A), light wire (Group B), and functional (Group C) groups were 82.4%, 80.3%, and 52.3%, respectively. The percentage of improvement in edgewise and light wire groups by weighted PAR score (82.4% and 80.3%, respectively) signifies a greater reduction of contact point displacement. No significant differences were noted between edgewise and light wire groups in this parameter. A study by Alyami [22] and Holman [23] (97.66%) obtained similar improvements in upper anterior segment by weighted PAR score in the total sample (83% and 97.66%, respectively). In the functional group, the treatment changes were less effective due to lesser reduction in contact point displacement (52.3) when compared with edgewise and light wire groups, and the difference was statistically significant. The edgewise group started with high mean pre-treatment weighted PAR score (5.70%), thereby reflecting a greater percentage reduction in this study.

The treatment changes in the lower anterior segment as shown by weighted PAR score in the edgewise (Group A), light wire (Group B), and functional (Group C) groups were 77.59%, 80.53%, and 41.9%, respectively. The percentage of improvement in edgewise and light wire groups shown by weighted PAR score was 77.5% and 80.53%, respectively, signifying a greater reduction of contact point displacement in both groups. No significant difference was noted between edgewise and light wire groups.

There was a greater percentage of improvement in UAS and LAS in cases treated with edgewise and light wire appliances (groups A and B). This shows that better control on teeth is achievable with the fixed appliances than when using the functional appliances alone.

Buccal occlusion

The treatment changes in the RBO as indicated by weighted PAR score in edgewise (Groups A), light wire (Group B), and functional (Group C) groups were 37.4%, 38.5%, and 29.4%, respectively. The difference was statistically not significant between the three groups. Greater treatment changes in RBO were observed by Holman by weighted PAR score (59.9%). In the LBO, the treatment changes shown by weighted PAR score in edgewise (Groups A), light wire (Group B), and functional (Group C) groups were 48.8%, 32.5%, and 15.6%, respectively. Greater treatment changes in the RBO were observed by Holman by weighted PAR score (54.24%). [23]

A study by Alyami [22] reported the mean improvement in RBO and LBO was 4.0% only. Comparing the treatment results statistically, no significant differences were noted between groups A, B, and C, but less improvement was noted in the functional group (Group C). The overall improvement in the buccal occlusion was very poor, which can be partly explained by the fact that the PAR index measures the sagittal lateral occlusion according to the interdigitation of the cusps. So, there is no difference between neutro-occlusion and a full inter pre-molar width class II and class III relationship.

Overjet

The treatment changes in the OJ indicated by weighted PAR score in edgewise (Group A), light wire (Group B), and functional (Group C) groups were 82.5%, 91.3%, and 84.6%, respectively. Alyami [22] observed less reduction in OJ in the treatment group by weighted PAR score (62.0%). However, Holman [23] found that the treatment changes were more effective in OJ by weighted PAR score (91.61%). OJ was the major contributor for the overall success of treatment. This was greatly reduced in Group B (91.3) when compared to groups A and C (82.5 and 84.6, respectively). No statistically significant difference was found on comparing the treatment changes between three groups.

Overbite

The treatment changes in the OB as shown by weighted PAR score in edgewise (Group A), light wire (Group B), and functional (Group C) groups were 70.4%, 77.3%, and 40.6%, respectively. The overall treatment changes in the OB were greatly reduced in groups B and A (77.3% and 70.4%, respectively) compared to Group C (40.6%). The treatment changes were less effective in Group C (functional), as these cases started with low pre-treatment PAR score. On comparing the treatment changes, no significant difference was noted between groups A and B. A 54.0% improvement in correction of OB was observed by Alyami. [22] However, Holman [23] observed 71.72% improvement in the total sample. Our findings in OJ reduction by fixed appliance are close to those of Alyami.

Center line

The treatment changes in the CL shown by weighted PAR score in edgewise (Group A), light wire (Group B), and functional (Group C) groups were 74.0%, 63.8%, and 63.1%, respectively, indicating good treatment improvement in all three groups. The treatment changes between the three groups were statistically not significant. Alyami [22] reported the mean improvement in CL to be 88.0% in his study. However, Holman [23] reported the mean improvement in CL to be 85.0% in his study. Greater change in his sample can be attributed to higher pre-treatment score for CL.

The overall mean reduction in all three groups shown by weighted PAR score was 69.7%, and only 8.6% of the cases fell into worse or no improvement category. It was noted that treatment mechanotherapy and pre-treatment PAR scores reflect the overall treatment improvement. The edgewise group showed higher reduction in total weighted PAR score, compared to the other two groups.


  Conclusions Top


  1. The PAR index appeared to be sensitive enough to determine difference in outcome between the techniques used in this study.
  2. All the cases showed significant overall improvement after treatment with standard edgewise, light wire, or functional appliance treatment technique. However, the patients in edgewise group demonstrated greater degree of overall improvement.
  3. Simple comparison of the percentage reduction in PAR score and nomogram grading may be misleading and cautious interpretation of results is necessary
.

 
  References Top

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    Figures

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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