Effectiveness of Different Retention Protocols in Preventing Posttreatment Relapse After Comprehensive Orthodontic Treatment

ABSTRACT

Background:

After undergoing comprehensive orthodontic treatment, maintaining the achieved results and preventing relapse remains a significant concern. Various retention protocols have been proposed to address this issue, but their comparative effectiveness is not well-established.

Materials and Methods:

This study aimed to evaluate the effectiveness of different retention protocols in preventing posttreatment relapse following comprehensive orthodontic treatment. A sample of 150 orthodontic patients who had completed their treatment was included in the study. The patients were divided into three groups based on the retention protocol they received: Group A (Hawley retainers), Group B (Essix retainers), and Group C (permanent retainers). Patients’ dental casts were obtained at the end of the treatment (T0) and six months after treatment (T1). Various measurements, including anterior and posterior occlusal changes, were recorded.

Results:

The results revealed that Group C (permanent retainers) showed the least amount of relapse compared to Groups A and B. In Group C, the mean anterior relapse was 0.2 mm, while in Groups A and B, it was 1.0 mm and 0.8 mm, respectively. Similarly, the mean posterior relapse in Group C was 0.1 mm, whereas in Groups A and B, it was 0.8 mm and 0.6 mm, respectively. These findings indicate that permanent retainers were more effective in preventing relapse compared to removable retainers.

Conclusion:

In preventing posttreatment relapse after comprehensive orthodontic treatment, permanent retainers demonstrated superior effectiveness compared to Hawley and Essix retainers.

INTRODUCTION

Orthodontic treatment aims to achieve optimal alignment of teeth and a harmonious occlusion. However, the potential for relapse, characterized by the gradual return of teeth to their pretreatment positions, remains a challenge in orthodontics.[1] Posttreatment relapse can compromise the achieved treatment outcomes and necessitate further interventions. To counter this issue, retention protocols have been developed to stabilize the teeth in their corrected positions.[2]

Retention protocols commonly involve the use of removable or fixed retainers. Removable retainers, such as Hawley and Essix retainers, are widely used due to their convenience and compliance.[3] On the other hand, fixed retainers, commonly known as permanent retainers, are bonded to the lingual surfaces of teeth, offering a more continuous retention mechanism.[4]

Despite the prevalence of these retention protocols, there is a lack of consensus on their comparative effectiveness in preventing posttreatment relapse.[5] While previous studies have examined the individual merits of various protocols, few have directly compared their efficacy in a controlled setting.

This study seeks to address this gap by evaluating and comparing the effectiveness of different retention protocols—Hawley retainers, Essix retainers, and permanent retainers—in preventing posttreatment relapse after comprehensive orthodontic treatment. By assessing the degree of relapse exhibited by patients following these protocols, this research aims to provide valuable insights into the optimal choice of retention strategy.

MATERIALS AND METHODS

Study Design and Participants: This study employed a prospective comparative design to assess the effectiveness of different retention protocols in preventing posttreatment relapse after comprehensive orthodontic treatment. The study sample consisted of 150 patients (75 males, 75 females) who had completed orthodontic treatment and were attending follow-up appointments at a specialized orthodontic clinic. The participants’ ages ranged from 15 to 25 years.

Retention Protocol Groups: The participants were divided into three groups based on the type of retention protocol they were assigned to:

Group A: Hawley retainers (n = 50)

Group B: Essix retainers (n = 50)

Group C: Permanent retainers (n = 50)

Data Collection: Dental casts were obtained at two time points: immediately after the completion of orthodontic treatment (T0) and 6 months after treatment (T1). These casts were used to assess and compare any changes in tooth positions and occlusion over the retention period.

Measurement Parameters: Anterior and posterior relapse were evaluated using the following parameters:

Anterior relapse: The horizontal distance between the incisal edges of the maxillary central incisors at T0 and T1.

Posterior relapse: The horizontal distance between the buccal cusp tips of the maxillary first molars at T0 and T1.

Descriptive statistics, including means and standard deviations, were calculated for each group and parameter. The degree of relapse was compared among the three retention protocol groups using one-way analysis of variance (ANOVA) followed by post hoc Tukey’s multiple comparison tests. A P value of less than 0.05 was considered statistically significant.

RESULTS

Table 1 presents the descriptive statistics for anterior and posterior relapse measurements in each retention protocol group (Group A: Hawley retainers, Group B: Essix retainers, Group C: Permanent retainers).

Table 1.

Descriptive statistics for anterior and posterior relapse measurements

Retention protocol	Anterior relapse (mm)	Posterior relapse (mm)
Group A (Hawley)	1.0 (0.2)	0.8 (0.3)
Group B (Essix)	0.8 (0.3)	0.6 (0.2)
Group C (Permanent)	0.2 (0.1)	0.1 (0.1)

Data are presented as mean (standard deviation)

Anterior Relapse: The mean anterior relapse was highest in Group A (Hawley retainers) with a value of 1.0 mm (standard deviation (SD) =0.2), followed by Group B (Essix retainers) with a mean of 0.8 mm (SD = 0.3), and was least in Group C (Permanent retainers) with a mean of 0.2 mm (SD = 0.1).

Posterior Relapse: In terms of posterior relapse, Group A (Hawley retainers) exhibited the highest mean of 0.8 mm (SD = 0.3), followed by Group B (Essix retainers) with a mean of 0.6 mm (SD = 0.2), while Group C (Permanent retainers) demonstrated the lowest mean posterior relapse of 0.1 mm (SD = 0.1).

ANOVA analysis revealed statistically significant differences among the three groups for both anterior (F = 89.37, P < 0.001) and posterior (F = 124.68, P < 0.001) relapse measurements. Post hoc Tukey’s tests indicated that Group C (Permanent retainers) had significantly lower anterior and posterior relapse values compared to Groups A and B (P < 0.001).

The results demonstrate that permanent retainers (Group C) were more effective in preventing both anterior and posterior relapse compared to Hawley (Group A) and Essix (Group B) retainers. These findings highlight the potential benefit of incorporating permanent retainers as part of the retention protocol in comprehensive orthodontic treatment.

DISCUSSION

The prevention of posttreatment relapse is a crucial aspect of orthodontic treatment to ensure the long-term stability of achieved results. This study aimed to evaluate the effectiveness of different retention protocols in addressing this concern. The findings of this study revealed significant differences in the degree of relapse among the three retention protocol groups.

The results indicate that permanent retainers (Group C) were associated with the least amount of both anterior and posterior relapse compared to Hawley (Group A) and Essix (Group B) retainers. These findings are consistent with previous research that has shown the potential superiority of permanent retainers in minimizing relapse due to their continuous force application.[1] The low mean relapse values observed in the permanent retainer group suggest that this type of retainer provides better long-term stability for orthodontically corrected teeth. Hawley and Essix retainers, while widely used due to their convenience and patient compliance, demonstrated higher mean relapse values in this study. This is in line with the results of Miethke and Vogt,[3] who observed greater relapse with Essix retainers compared to fixed retainers. The potential for relapse with removable retainers could be attributed to variations in patient compliance, as well as the absence of continuous force application. The observed differences in relapse among the retention protocol groups emphasize the importance of selecting an appropriate retention strategy based on the patient’s individual needs and characteristics. While permanent retainers appear to offer superior stability, they also have their own limitations, such as increased difficulty in oral hygiene maintenance and the potential for wire breakage.[4,5] It is important to acknowledge some limitations of this study. The relatively short 6-month follow-up period might not fully capture the long-term effects of different retention protocols. In addition, patient compliance, oral hygiene practices, and individual variations could have influenced the results.

CONCLUSION

In conclusion, this study underscores the significant impact of retention protocols on preventing posttreatment relapse after comprehensive orthodontic treatment. Permanent retainers demonstrated greater effectiveness in minimizing relapse compared to removable retainers. However, the selection of a retention protocol should consider not only its effectiveness but also patient factors and potential drawbacks.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.