Clear aligner therapy has gained significant popularity in orthodontics, with practitioners increasingly using this modality for complex malocclusions, including deep bites. However, achieving predictable deep bite correction with aligners remains a significant challenge. This article reviews the current evidence on deep bite treatment with clear aligners, discusses limitations and opportunities, and outlines critical elements for successful treatment planning.
Limitations of Clear Aligners in Deep Bite Correction
Accuracy of Overbite Correction
Recent studies have revealed that the accuracy of overbite correction with clear aligners is lower than previously thought. Blundell et al. (2021) and Shahabuddin et al. (2023) reported accuracy ranges of just 33-39% with aligners alone. Moreover, this accuracy tends to decrease as the initial overbite depth increases. These findings suggest clinicians should expect significant discrepancies between planned and achieved outcomes in deep bite cases.
Overestimation in Treatment Planning Software
Another area for improvement is the tendency of treatment planning software, such as ClinCheck, to overestimate the amount of curve of Spee leveling that we can achieve clinically. Blundell et al. (2021) found that ClinCheck overestimated leveling in 95.3% of patients. This overestimation can lead to unrealistic expectations and the need for multiple refinements during treatment if we don’t compensate for it.
Challenges with Specific Tooth Movements
Specific tooth movements crucial for deep bite correction have proven challenging with clear aligners. Mandibular incisor intrusion, a key component of deep bite correction, remains one of the least accurate movements. Studies report accuracy rates of only 35-42.5% for this movement (Kravitz et al. 2009, Shahabuddin et al. 2023).
Biomechanical Challenges
The inherent bite plane effect of aligners and the high masticatory forces on molars make posterior extrusion difficult to achieve predictably. This limitation can hinder efforts to level the curve of Spee and open the bite through posterior dental extrusion.
Strategies for Improving Deep Bite Correction with Clear Aligners
Despite these challenges, several strategies can enhance deep bite correction outcomes with clear aligners:
Overcorrection and Treatment Planning
Given the tendency for under-correction, treatment design should incorporate significant overcorrection in the setup. This may involve ending the ClinCheck with an anterior edge-to-edge or slight open bite to compensate for the tendency to under-correct. We must consider complicating factors that decrease the predictability of the deep bite correction, including low-angle cases, the initial severity of the deep bite, and whether space closure with retraction is necessary, which increases the dentition’s relative extrusion and counteracts the desired intrusive movements. Voudouris et al. (2022) recommend planning for 150-200% of the desired change.
Leveling the curve of Spee and molar extrusion are effective strategies to address deep overbite. Focus should be placed on mandibular first molar extrusion, as these teeth show low extrusion accuracy relative to the occlusal plane. Significantly overcorrecting the first molar extrusion in ClinCheck can help achieve the desired vertical changes.
Optimized Features and Attachments
Utilizing optimized attachments can improve force delivery and predictability. Extrusion attachments on posterior teeth can improve aligner grip and force delivery. Expansion support, multiplane, and retention-optimized attachments will help manage deep bites. Consider expansion support or multiplane attachments for rotated teeth to allow simultaneous derotation and extrusion.
Precision bite ramps can help disarticulate posterior teeth to allow extrusion while providing an intrusive force on lower incisors. These are particularly useful when we plan greater than 1.5mm mandibular incisor intrusion. Auxiliaries like Class II elastics can aid posterior extrusion even in Class I cases. Buttons on lower molars may improve elastic effectiveness.
Aligner Modifications and Staging
Modifying aligner properties can enhance their effectiveness. Requesting increased clearance between the aligner and occlusal surface in the posterior region can allow for better posterior tooth extrusion. Pressure points on the anterior teeth help provide intrusive forces to gain predictability. These activations can be requested using the Invisalign appliance’s G5, G7, and G8 enhancements.
Careful staging of movements is crucial. Begin with posterior extrusion and incisor intrusion while incorporating significant arch expansion to level the curve of Wilson. This approach can help maintain better control over the vertical dimension throughout treatment. Staging intrusion with incisor proclination can help deep bites with the relative intrusion of the anterior teeth. Hence, cases with significant anterior crowding tend to have greater predictability in deep bite correction.
Advanced Technologies and Hybrid Approaches
Exploring new technologies, such as Invisalign’s G8 system, which aims to improve predictability through individualized activation of anterior teeth for intrusion, may offer improved outcomes.
Consider hybrid approaches for some complex deep bite cases. Combining maxillary clear aligners and mandibular fixed appliances may provide better control while still meeting some aesthetic demands.
Conclusion
While clear aligners present challenges in predictably correcting deep bites, careful treatment planning and incorporating various strategies can improve outcomes. Clinicians should plan for significant overcorrection, utilize appropriate attachments and auxiliaries, and be prepared for refinements. As aligner technology continues to advance, we can expect further improvements in the predictability of deep bite correction. By implementing these evidence-based strategies and maintaining realistic expectations, orthodontists can effectively use clear aligners to manage many deep bite cases.
References:
1. Blundell HL, Weir T, Kerr B, Freer E. Predictability of overbite control with the Invisalign appliance. Am J Orthod Dentofacial Orthop. 2021;160:725-31.
2. Shahabuddin N, Kang J, Jeon HH. Predictability of the deep overbite correction using clear aligners. Am J Orthod Dentofacial Orthop. 2023.
3. Henick D, Dayan W, Dunford R, Warunek S, Al-Jewair T. Effects of Invisalign (G5) with virtual bite ramps for skeletal deep overbite malocclusion correction in adults. Angle Orthod. 2021;91:164-70.
4. Kravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop. 2009;135:27-35.
5. Kravitz ND, Moshiri M, Nicozisis J, Miller S. Mechanical considerations for deep-bite correction with aligners. Semin Orthod. 2020;26:134-8.
6. Voudouris JC, Voudouris JD, Nicolay O, et al. Clear aligners, dentofacial orthopedics, physics, and supercorrection prescription biomechanics. Semin Orthod. 2022;27:202-58.
