# Maximally Deficiency: Treatments and Applications for Adolescents
## 2 Orthopedic Approaches
### Children in Primary and Early Mixed Dentition  
SME is a widely used method for widening the maxillary dental arch and correcting posterior crossbite, particularly effective in children up to about age 10 during the primary and early mixed dentition stages [45], when the mid-palatal suture has not yet fused or only minimally fused [3]. While the dental expansion techniques with the SME protocol can induce some skeletal changes, its predominant effect is more pronounced dental changes and buccal bone loss. This occurs because these appliances primarily cause the teeth to tip buccally, resulting in less significant orthopedic impact on the maxillary base and a higher risk of buccal bone dehiscence [46]. Clear aligners have been proposed as a potential alternative to SME-based dental expansion techniques, but thus far there is no evidence indicating any skeletal effects [47; 48]. However, in children or adolescents with cleft palate, the typical resistance provided by the mid-palatal suture is often significantly diminished or entirely absent [10]. To address this unique anatomical challenge, specialized appliances employing the SME protocol such as the Coffin spring, W-arch, or quadhelix can be utilized. These devices enable skeletal expansion in individuals with cleft conditions, widening the maxillary arch while minimizing tissue damage, in contrast to the expansion appliances with the RME approach [49; 50].  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Patient Stage** & **Techniques** & **Appliances** & **Advantages** & **Disadvantage** & **Study** \\ \hline \hline \multirow{8}{*}{Bone-borne expander} & \multirow{8}{*}{ATOZ expander} & Delivers precise positioning with a thermoplastic guide to effectively influence cultural width compared to the C-expander; its compact size makes it suitable for narrower palates. & & \\  & & & Features precision-fit insertion slots that enable effective height loss and thickness changes in late adolescent patients compared & & \\ \cline{1-1}  & \multirow{4}{*}{Tooth-bone- adolescents (around 14–19 years of age)} & \multirow{4}{*}{Tooth-bone-borne hexillary skeletal expander} & \multirow{4}{*}{Tooth-bone-enable effective bicritical stabilization and apply lateral forces against critical resistance points.} & \multirow{4}{*}{[39; 40; 41]} \\ \cline{1-1}  & & & Suitable for patients lacking anterior teeth anchorage, maintains buccal bone thickness, and exhibits distances compared to the C-expander. & & \\ \cline{1-1}  & \multirow{4}{*}{Hybrid HYRAX} & \multirow{4}{*}{Hybrid HYRAX} & \multirow{4}{*}{Hybrid HYRAX improved efficacy for maxillary protection} & \multirow{4}{*}{[42; 43; 44]} \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: _Cont._SME can be effectively carried out using both removable and fixed appliances, each tailored to specific treatment needs. Removable appliances typically incorporate Adam clasps on the first permanent molars and ball-ended clasps on the deciduous molars, often supplemented with posterior acrylic capping [51]. Conversely, fixed appliances usually consist of bands that are securely bonded to the first permanent molars [49].  
For treating maxillary constriction in young children with primary and early mixed dentitions, fixed expanders with the jackscrew, such as HYRAX, can be used to apply high forces for rapid expansion. However, the use of RME in young patients is associated with risks such as facial distortion [50]. Therefore, it is generally advised that the screw of fixed expanders should be activated very carefully and gradually. In fact, studies conducted a decade after treatment have shown that both rapid and slow palatal expansions with the fixed expander, despite being used for varying degrees of constriction, maintain stable results [52].