# Predictability of Maximly Expansion with Invisalign(r) First: Treatment Planning vs. Outcome
## 1 Introduction  
Maxillary expansion treatments have been used for over a century to correct maxillary transverse deficiencies, and their efficacy is strongly supported in the literature [1]. In general, we can distinguish between two types of expansion: rapid maxillary expansion (RME) and slow maxillary expansion (SME). Both RME and SME are effective in increasing the maxillary transverse diameter in younger patients by opening the midpalatal suture, which is not fully ossified in growing individuals [2, 3]. The purpose of RME is to create significant forces at the sutural site in a short period of time to maximize the orthopedic effect, while SME is achieved with lighter forces distributed over a longer period, leading to a more physiological expansion.  
The Invisalign(r) technique was introduced in 1997 as an esthetic and comfortable alternative compared to conventional fixed appliances. Initially, treatment with clear aligners was intended for adult patients only. Compared to traditional appliances, it presents no dietary restrictions, lower risk of appliance damage due to its weekly change, no emergency appointments, simplified oral hygiene, greater patient comfort, easier compliance, and minimal social impact [4, 5].  
In 2018, Align Technology introduced the Invisalign(r) First system, consisting of clear aligners for patients aged from 6 to 10 years, to perform Phase I orthodontic treatment, including the correction of maxillary transverse deficit. Interceptive orthodontic interventions in early mixed dentition share the common goal of allowing for more favorable growth of the maxillae and the subsequent development of satisfactory occlusion. Common malocclusion traits in such treatments are arch constriction, molar rotations, and crowding, often associated with posterior crossbite, impacted teeth, and space loss for permanent dentition. In recent years, clear aligners have been proposed as a more convenient alternative to conventional approaches for achieving dentoalveolar maxillary expansion in growing patients (Figure 1) [6,7].  
Currently, scientific knowledge on the predictability and effectiveness of Invisalign(r) as corrective treatments in mixed dentition is limited. Only few studies have evaluated the effectiveness of dentoalveolar expansion with Invisalign(r) First technology in mixed dentition [8,9]. Given the lack of data in the literature, especially concerning posterior transverse changes, this study aims to investigate the predictability of the ClinCheck(r) software ([[https://www.invisalign.com/provider/align-digital-platform/clincheck](https://www.invisalign.com/provider/align-digital-platform/clincheck)]([https://www.invisalign.com/provider/align-digital-platform/clincheck](https://www.invisalign.com/provider/align-digital-platform/clincheck)), accessed on 23 October 2024) by comparing the planned orthodontic setup measurements with the actual clinical outcome. Understanding the accuracy of the software in predicting changes could help the professional anticipate the need for overcorrection, thereby reducing refinements, mid-course corrections, and treatment time.  
This study not only addresses a significant gap in the current literature, but also contributes to a better understanding of how aligner-based orthodontic treatments can provide a viable alternative to conventional methods. Comparing predicted outcomes with actual clinical results could offer an insights that can help practitioners improve their treatment planning strategies. The implications of this research are crucial for advancing orthodontic care in younger patients, particularly in improving predictability and reducing the need for refinements during treatment.