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Malocclusion severity in Asian men in relation to malocclusion type and orthodontic treatment need

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Introduction: The purpose of this study was to assess the severity of malocclusion in young Asian men in relation to types of malocclusion and orthodontic treatment need. Methods: Study models of 339 male army recruits (age, 17-22 years) with no history of orthodontic treatment were assessed. The peer assessment rating (PAR) index was used to determine the severity of their malocclusions. Logistic regression and receiver operating characteristics (ROC) curves were performed to evaluate the PAR index in relation to treatment need assessed by the dental health component (DHC) and the esthetic component (EC) of the index of orthodontic treatment need. Results: The mean PAR scores were 17, 20, 28, and 18 for Class I, Class II Division 1, Class II Division 2, and Class III, respectively. PAR scores were highly correlated with DHC and EC scores (P < .001). An increase of 1 point in the PAR score significantly increased the likelihood of orthodontic treatment need for dental-health reasons or esthetic impairment (by 1.17 times [95% CI 1.13-1.21] or 1.25 times [95% CI 1.19-1.31]). The areas under the ROC curves for PAR index were 84% and 94% for the DHC and EC assessments, respectively, suggesting that PAR scores were better predicators of esthetic than dental health impairment for assessing Asian malocclusions. The optimum cutoff points were PAR scores of 17 and 20 for dental health and esthetic impairment, respectively. Conclusions: Class II malocclusions were more severe than Class I or III in Asian men. Malocclusions with definite treatment need had PAR scores that were significantly greater than those with borderline, little, or no need. ROC curves showed that the PAR index had an acceptable level of validity with the professional assessment of orthodontic treatment need in Asian malocclusions. The optimum cutoff PAR scores were 17 and 20 in relation to DHC and EC assessment, respectively. The PAR index was more predictive of esthetic than dental health need.

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Material and methods

The sample of medically fit army recruits (n = 339; age, 17-22 years) with no history of orthodontic treatment, serial extractions, and craniofacial anomalies participated in this research voluntarily with informed consent. Impressions were taken from all participants for study model fabrication. Type of malocclusion was defined according to the British Standard Institute Incisor Classification.13 Severity of malocclusion and treatment need were evaluated based on study model analysis by using

Results

Intraexaminer PAR assessment was very good, with a correlation coefficient of r = 0.96 (P < .05). Weighted kappa scores for DHC and EC were 0.96 and 0.82, respectively, which indicated very good intraexaminer agreement.

The mean and median PAR scores and sample sizes of the various malocclusions are shown in Table I. Mean PAR scores for Class I, Class II Division 1, Class II Division 2, and Class III malocclusions were 17, 20, 28, 18, respectively. The mean and median PAR scores of Class II

Discussion

The mean PAR scores indicated that most malocclusions would be categorized in the straightforward treatment category,3 mainly observed in Classes I and III malocclusions. Class II Division 2 malocclusions had the highest PAR scores compared with the other types of malocclusion. These results suggest that Class II malocclusions in Asian men have more occlusal-trait deviation than Class I or Class III malocclusions. Thus, Class II malocclusions in this sample could be perceived to be more

Conclusions

Class II malocclusions in Asian men were found to be more severe than Class I and Class III malocclusions. The highest mean and median PAR scores were found in Class II Division 2 malocclusions. Malocclusions with definite treatment need had PAR scores that were significantly greater than those with borderline, little, or no need. ROC curves showed that the PAR index has an acceptable level of validity with the professional assessment of orthodontic treatment need in Asian malocclusions. The

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    The optimal cutoff score for determining orthodontic treatment needs with the PAR index, maximizing agreement based on the decisions of orthodontic experts in white subjects, is 17 for the PAR in both the United States and the United Kingdom.14 In Asian subjects, Soh et al15 reported that a PAR index of 17 was the optimum cutoff for presumed compromised dental health and a PAR index of 20 for esthetic impairment. These investigations suggest that the casts with a PAR index of 18 and 19 in this study might be considered borderline cases for orthodontic treatment by orthodontists and were perceived to require little treatment by residents and students.

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