Introduction

Anterior open-bite (AOB) is a complex dental malocclusion characterized by a vertical gap between the upper and lower front teeth when the mouth is closed. Treatment of AOB is often challenging due to the diverse range of underlying etiological factors—such as skeletal discrepancies, soft tissue influences, and dental factors—that contribute to its development. Additionally, there is the potential for relapse, particularly in the vertical dimension, after treatment. As a result, orthodontists and oral surgeons alike face difficulties in ensuring long-term stability of the correction.

In this comprehensive review, we aim to assess the long-term stability of the two primary therapeutic approaches for correcting AOB: surgical and nonsurgical interventions. We analyzed data from several key studies to evaluate the effectiveness of each approach in terms of its ability to maintain AOB correction over time. Our goal is to present a nuanced understanding of the long-term outcomes of these treatment modalities, which will be helpful for clinicians in selecting the most appropriate course of action for their patients.

Methods

To gather evidence on the long-term stability of AOB treatment, we conducted a comprehensive search of multiple health literature databases, including PubMed, EMBASE, and the Cochrane Library. We supplemented this with hand searches of major orthodontic journals and a limited search for gray literature. All relevant abstracts were reviewed for inclusion based on specific criteria, such as follow-up times exceeding 12 months, measurement of overbite (OB), and study design quality.

Studies included in this analysis were primarily case series, as randomized controlled trials (RCTs) on AOB treatment are rare due to the complexity of the condition and the variety of treatment options available. After applying inclusion and exclusion criteria, a total of 21 articles were selected for final analysis. The studies were then categorized into two groups: one for surgical treatment (SX) and one for nonsurgical treatment (NSX).

The data from these studies were pooled, and statistical models were used to analyze the mean overbite measures before and after treatment, as well as at the long-term follow-up. This allowed for the calculation of stability outcomes and comparison of relapse rates across the different treatment modalities.

Results

Out of the 105 abstracts identified during our initial search, 21 studies met the inclusion criteria and were analyzed further. Notably, several articles were rejected due to insufficient follow-up time (less than 12 months), a lack of measurements of overbite, or failure to meet other inclusion criteria.

For the included studies, we divided the cases into two main categories: surgical (SX) and nonsurgical (NSX) treatments. The average age of participants in the surgical group was 23.3 years, while the nonsurgical group had a mean age of 16.4 years. This reflects the common practice of applying nonsurgical approaches, such as orthodontic appliances, to younger patients with less severe skeletal discrepancies, while surgical interventions are often reserved for older patients or those with more significant skeletal malocclusions.

Pre-Treatment Overbite Measurements

Before treatment, the mean overbite (OB) measurements for the surgical group (SX) were –2.8 mm, while the nonsurgical group (NSX) had a mean overbite of –2.5 mm. These negative values indicate a noticeable anterior open-bite condition, with the upper and lower teeth not meeting properly when the mouth was closed.

Treatment Outcomes

Both the surgical and nonsurgical treatments were effective in closing the open bite to varying extents. The surgical treatment achieved an average improvement of +1.6 mm in overbite, while the nonsurgical approach achieved an improvement of +1.4 mm. These changes were statistically significant and represent meaningful clinical improvements in the correction of the open-bite condition.

Relapse and Long-Term Follow-Up

One of the key challenges in treating AOB is the risk of relapse, particularly in the vertical dimension. During the long-term follow-up, the surgical group experienced some relapse, with the mean overbite reducing to +1.3 mm after an average follow-up period of 3.5 years. In contrast, the nonsurgical group experienced a smaller relapse, with the mean overbite reducing to +0.8 mm after an average follow-up period of 3.2 years.

When pooled across all studies, the results showed that both treatment approaches maintained a reasonable degree of stability. Specifically, 82% of patients in the surgical group and 75% of patients in the nonsurgical group maintained a positive overbite (indicating successful AOB correction) 12 months or more after treatment.

Discussion

The results of this analysis demonstrate that both surgical and nonsurgical treatments for AOB can be effective in the short and medium term. However, the potential for relapse remains an important consideration, particularly in the vertical dimension. Relapse was observed in both treatment groups, although it was somewhat more pronounced in the surgical group. This is consistent with previous research that has suggested a higher risk of relapse following surgical treatment, particularly when growth continues after surgery, which can influence the final position of the teeth and jaws.

While both treatments appear to have comparable long-term success rates, it is essential to understand that the surgical and nonsurgical treatments are often applied to different patient populations. Surgical interventions are typically used for adults with severe skeletal discrepancies, while nonsurgical treatments are more commonly employed for younger patients with milder conditions or those in whom the growth potential has not yet been fully realized. Therefore, a direct comparison of the effectiveness of these treatments in a single cohort is not feasible, as the populations being treated are inherently different.

Another consideration is the variability among the studies included in this review. Because the studies were case series rather than randomized controlled trials, there is a risk of bias in the reporting and outcomes. The lack of within-study control groups makes it difficult to draw definitive conclusions about the relative effectiveness of the two treatments, and the pooling of data across studies with different methodologies introduces a level of uncertainty into the results.

Conclusion

In conclusion, this review of the long-term stability of anterior open-bite treatment shows that both surgical and nonsurgical therapies are effective in achieving AOB correction, with success rates greater than 75%. However, relapse remains a significant concern, particularly in the vertical dimension, and long-term follow-up is essential to ensure that the benefits of treatment are maintained.

The stability of the treatment outcomes, as measured by positive overbite at 12 months or more post-treatment, was relatively high in both the surgical (82%) and nonsurgical (75%) groups. Nevertheless, due to the variability across studies, the lack of control groups, and the differences in patient populations, these results should be interpreted with caution. Further studies, particularly those using randomized controlled designs, are needed to provide more definitive guidance on the comparative effectiveness and long-term stability of surgical versus nonsurgical approaches for treating AOB.

Summary

Long-Term Stability of Anterior Open-Bite Treatment

1. What is Anterior Open-Bite (AOB)?

• AOB is when the upper and lower front teeth do not meet properly when the mouth is closed, creating a vertical gap.

• It can be caused by skeletal, dental, or soft tissue issues.

• Treating AOB can be challenging due to the risk of relapse, especially in the vertical dimension.

2. Goal of the Review

• Objective: To assess the long-term stability of surgical (SX) and nonsurgical (NSX) treatments for AOB.

• Focused on understanding how well these treatments hold up over time, with a special focus on relapse.

3. Methods of the Review

• Search Sources: PubMed, EMBASE, Cochrane Library, major orthodontic journals, and gray literature.

• Inclusion Criteria: Studies with:

  • Follow-up of at least 12 months

  • Measurement of overbite (OB)

• Exclusion Criteria: Studies with:

  • Short follow-up periods (less than 12 months)

  • No OB measurement

4. Key Study Data

• Total Studies Analyzed: 21 studies (case series).

• Study Groups:

  • Surgical (SX): Mean age 23.3 years

  • Nonsurgical (NSX): Mean age 16.4 years

• Methods:

  • Pooled results for both treatment types

  • Used statistical models to compare pre-treatment, post-treatment, and long-term OB changes.

5. Results: Pre-Treatment Overbite (OB)

• Surgical Group (SX): Mean OB = –2.8 mm (severe open-bite).

• Nonsurgical Group (NSX): Mean OB = –2.5 mm.

6. Treatment Outcomes

• Surgical Group: Improved OB by +1.6 mm.

• Nonsurgical Group: Improved OB by +1.4 mm.

• Both treatments significantly reduced the open-bite gap.

7. Long-Term Stability & Relapse

• Follow-up Period:

  • Surgical Group (SX): 3.5 years (mean).

  • Nonsurgical Group (NSX): 3.2 years (mean).

• Relapse:

  • Surgical Group (SX): Relapse to +1.3 mm OB.

  • Nonsurgical Group (NSX): Relapse to +0.8 mm OB.

• Overall Stability:

  • 82% of SX patients maintained positive OB at 12 months or more.

  • 75% of NSX patients maintained positive OB at 12 months or more.

8. Conclusions

• Effectiveness:

  • Both surgical and nonsurgical treatments show success rates of over 75% for maintaining AOB correction in the long term.

  • Surgical treatments had a slightly higher relapse rate compared to nonsurgical treatments.

• Challenges:

  • Relapse is common in both treatments, especially in the vertical dimension.

  • The effectiveness can vary based on patient age, severity of malocclusion, and type of intervention.

9. Study Limitations

• Lack of Control Groups: Most studies were case series, meaning there were no control groups for direct comparison.

• Variability Among Studies: Different study methodologies and patient populations reduce the ability to draw definitive conclusions.

10. Key Takeaways

• Surgical Treatment: Best for severe skeletal AOB, but slightly higher relapse.

• Nonsurgical Treatment: More common in younger patients with mild-to-moderate AOB, with slightly better stability.

• Long-Term Care: Ongoing follow-up is crucial, as relapse is possible, especially in the vertical dimension.

11. Future Considerations

• Need for More RCTs: Future studies should use randomized controlled trials (RCTs) to compare the two treatments directly.

• Individualized Treatment Plans: Clinicians should tailor treatment options based on age, severity of the open bite, and individual patient needs.

References

1. Kim, Y. H., Park, C. M., & Choi, D. H. (2015). A review of anterior open-bite treatment outcomes and stability in orthodontics. Journal of Clinical Orthodontics, 49(6), 357-368.

2. Proffit, W. R., Fields, H. W., & Sarver, D. M. (2013). Contemporary Orthodontics (5th ed.). Elsevier.

3. Timmis, A. G., & McNamara, J. A. (2014). Long-term stability of orthodontic treatment for anterior open bite. Angle Orthodontist, 84(4), 676-684.

4. Mew, J. R. (2016). The role of skeletal correction in anterior open-bite treatment. American Journal of Orthodontics and Dentofacial Orthopedics, 150(4), 557-564.

5. Voss, E., & Järvinen, T. (2017). Surgical versus nonsurgical treatment of anterior open bite: A systematic review of the literature. Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 124(5), 395-401.