Evaluation of pain perception during orthodontic debonding of metallic brackets with four different techniques

Abstract Objective The aim of this study was to evaluate patients’ pain levels during four different debonding procedures. The null hypothesis was that the pain perception of the patients undergoing four different debonding applications was not statistically significant different. Material and Methods One hundred and twenty orthodontic patients who underwent orthodontic debonding were included in this study. The patients were randomly divided into 4 groups according to technique used in the patients. Debonding groups were as follows: Group 1) Conventional debonding group, Group 2) Medication group (acetaminophen was given 1 hour before debonding), Group 3) Soft bite wax group, and Group 4) Soft acrylic bite wafer group. The patients’ levels of anxiety and fear of pain were evaluated before debonding, and Numerical Rating Scale (NRS) was applied to evaluate their pain perception during debonding. Mann-Whitney U and Kruskal–Wallis tests were used to evaluate non-normally distributed data. Categorical data analysis were carried by chi-square and McNemar tests. The significance level was set at p<0.05. Results Anxiety scores of the patients were not statistically significant between both genders and debonding groups. In the quadrants in which the patients were perceived, the highest pain level was in the left side of the mandible. The teeth in which the highest pain level was perceived were the lower left and upper right lateral incisors. Although there was no statistically significant difference among the pain scores of the patients in each group, quadrant scores of female patients showed significant differences, being the lowest scores in the soft bite wax group. Conclusions Majority of the patients had no fear of pain before debonding. Pain levels of the patients in the conventional debonding group were not significantly different from those of the other groups, except quadrant scores of females in the soft bite wax group. The null hypothesis was accepted.


Introduction
Orthodontic treatment procedures such as separator placement, orthodontic force application, archwire placement and activation, and debonding procedure usually involve pain and discomfort, and 90% to 95% of patients reported having pain during orthodontic treatment. [1][2][3][4][5][6] It has been generally accepted that pain perception may be related to age, individual pain threshold, motivation, psychological condition, previous negative dental experience, and the magnitude of orthodontic force. Some previous reports showed women reported more pain experience than men, 7,8 while other reports showed no gender differences regarding pain perception. 5,[9][10][11] Pain may arise during the active phases of orthodontic treatment and during the debonding procedure. 1,2 To lessen or prevent the pain during debonding are as important as preventing enamel damage and, thus, the use of different orthodontic instruments, ultrasound, laser application, thermal heating the orthodontic adhesives, or biting occlusal bite wafers at debonding have been discussed in previous reports. [11][12][13] Debonding procedure should be harmless, painless and quick. 14 Pain and discomfort resulting from fixed orthodontic appliances, such as elastomeric separator and arch wire placement, were evaluated in previous studies, 5,6,15 but pain perception in debonding procedure is still a poorly documented issue in orthodontics. The aim of this study was to evaluate the pain levels in different debonding applications and the patients' anxiety levels before the procedure to determine the best debonding technique. The null hypothesis was that the pain perception of the patients undergoing four different debonding applications is not statistically significant different (conventional debonding, debonding with acetaminophen administration, debonding while biting a soft plastic wafer, and debonding with biting wax).

Material and methods
The sample size was determined using a The debonding procedures applied to each group were as follows: Group 1) Conventional debonding group: Debonding was performed with a Weingart plier.

Results
Distribution of the patients' anxiety scores before debonding and their between-groups comparisons and the comparisons between the genders are shown in Table 1. No between-groups differences and no gender differences in all groups    Table 2 and 3, respectively. Approximately one third of the patients (n=36) declared no pain during debonding. According to the results in Table 2, the chin area in which the frequency of pain perception was maximum (26.7%) was the lower left mandibular area.
The results of Table 3 Table 4 were classified according to gender, and pain scores of the male and female patients in each group and the results of between-groups comparisons of each gender are shown in Table 5.
As can be seen from females showed statistically significant differences between the groups. Soft bite wax and soft acrylic bite wafer groups showed lower pain scores. These two groups also showed lower pain scores in males, although it was not statistically significant (p=0.097).

Discussion
Bond strength is important for maintaining orthodontic treatment efficiency, but easy debonding of the brackets is preferred at the end of the treatment. Many kinds of debonding methods have been suggested to lessen the patient discomfort. These debonding methods include ultrasonic instrumentation, laser irradiation and electrothermal heating, using special pliers. In addition to these methods, modified adhesive resins containing thermoexpandable microcapsules have been used to lessen the pain and discomfort. 3,11,[17][18][19] Pain is an inherently subjective symptom, and thus no objective method exists for its assessment. Visual analog scale (VAS), numerical rating scale (NRS), and verbal rating scale (VRS) are commonly used measurement instruments to quantify pain intensity of the patients. The comparative studies regarding these instruments showed no statistically significant difference among them. 17,20 In this study, numerical rating scale was used to assess the pain perceived during debonding because of its easy application.
Debonding procedures should be harmless,    Stabilizing the teeth with a finger can also be helpful for minimizing discomfort. 13 Table 4).
The location of the tooth has an impact on the degree of pain, 25 being the debonding of incisors more painful than that of posterior teeth. 15,21 This phenomenon may be related with the tactile sensory threshold, since this threshold is about 1 gram in the anterior portion of the dentition in normal subjects and gradually increases toward the posterior segment, ranging from 5 to 10 gram. 21  This finding is consistent with the study by Williams and Bishara 12 (1992), who noted that gender difference has little influence on pain.
Koyama, et al. 27 (2005) noted that the subjective pain experience is related to expectations of pain and alters the brain mechanism, in other words, positive expectations result in a reduced pain experience.
A statistically significant difference was observed in the quadrant scores of female patients. Soft bite wax group showed lower debonding pain levels than the other groups and no significant differences among the other groups was observed. The subjectivity of pain perception shown in this study was similar to that in the previous reports. 25,28 It might be thought that this study had some limitations. For example, there may have been a bias in patient recruitment into the different groups because this study is a controlled clinical trial. Again, adding the patients with ceramic brackets could enhance the scientific value of the study.

Conclusions
The results of this study can be summarized as follows: 1-Pre-anxiety scores of the patients showed no difference between genders and groups.