Introduction: Transverse maxillary deficiency is a very common condition in growing patients. It is a frequent form of malocclusion that manifests during the primary and mixed dentition stages and is often clinically associated with posterior crossbite, either unilateral or bilateral. Failure to diagnose and treat this condition early may lead over time to the development of skeletal asymmetries and impairments in the growth and function of craniofacial structures. Palatal expansion is a primary therapeutic procedure for growing patients with transverse maxillary deficiency, aiming to correct maxillary constriction and restore proper dentoskeletal balance. The use of palatal expanders anchored to primary teeth during mixed dentition allows for a greater orthopedic effect while reducing dentoalveolar side effects on permanent teeth. However, although the primary objective of palatal expansion is to achieve skeletal modifications, it inevitably also produces dentoalveolar changes. In particular, the maxillary first permanent molars are often indirectly involved and may undergo undesirable three-dimensional movements that could affect treatment stability. Therefore, the distribution of dentoalveolar effects induced by expansion therapy should be carefully considered during treatment planning. Objective: To evaluate the three-dimensional positional changes of the maxillary first permanent molars and the dentoalveolar response in growing patients following maxillary expansion with the Leaf Expander®, comparing two appliance configurations: with and without distal extensions. Materials and Methods: In this randomized controlled trial (RCT), 30 patients (CVMS stages 1–2) in early mixed dentition, presenting with a posterior transverse discrepancy ≥3 mm and fully erupted maxillary first permanent molars, were randomly assigned to receive a Leaf Expander® either with distal extensions (n = 15) or without distal extensions (n = 15). Exclusion criteria included systemic diseases or syndromes, pubertal or post-pubertal growth stage, agenesis of the maxillary second premolars, absence of the second primary molars, and skeletal Class III malocclusion. The expander was cemented on the second primary molars and reactivated monthly until overcorrection was achieved. Digital intraoral scans were obtained before treatment (T0) and after treatment (T1). Molar crown angulation was assessed using 3D software, while molar rotation and transverse dimensional changes (intercanine, inter-primary molar, intermolar widths, and arch perimeter) were evaluated on digital models. Reliability was assessed using the Intraclass Correlation Coefficient (ICC). Statistical analysis included paired and independent t-tests, as well as linear regression analysis (p < 0.05). Results: No significant differences were observed between the groups at baseline (p > 0.05). All measured parameters showed significant improvements from T0 to T1 in both groups (p < 0.05). The group without distal extensions exhibited greater increases in intercanine and inter-primary molar widths, as well as a more pronounced derotation of the maxillary first permanent molars (teeth 16 and 26) (p < 0.05). Conversely, the group with distal extensions demonstrated a significantly greater increase in buccal crown angulation of the molars (p < 0.05). No significant differences were found between the groups regarding permanent intermolar width or arch perimeter increase (p > 0.05). Conclusions: The presence of distal extensions limited intercanine expansion and spontaneous derotation of the maxillary first permanent molars, while promoting greater buccal tipping of these teeth. However, distal extensions did not affect transverse expansion at the level of the permanent molars nor the increase in arch perimeter. Appliance design may selectively modulate the dentoalveolar response to orthopedic expansion therapy.
Introduzione: Il deficit trasversale del mascellare superiore è una problematica molto comune nei pazienti in età evolutiva. È una forma frequente di malocclusione che si manifesta in dentizione decidua e mista, ed è spesso accompagnata clinicamente da cross bite posteriore sia in forma monolaterale che bilaterale. La mancata diagnosi precoce e, di conseguenza, il mancato trattamento in maniera tempestiva possono portare nel tempo allo sviluppo di asimmetrie scheletriche e a problemi nello sviluppo e nella funzione delle strutture cranio-facciali. L’espansione palatale è la una procedura terapeutica di primaria importanza per i pazienti in crescita con deficit trasversale del mascellare superiore e mira a correggere la contrazione mascellare, nonché a ricreare un corretto equilibrio dento-scheletrico. L’impiego di espansori palatali ancorati ai denti decidui, in dentizione mista, consente di ottenere un effetto ortopedico e di ridurre l’entità degli effetti dento-alveolari a carico degli elementi permanenti. Nonostante, però, l’espansione palatale abbia la finalità di ottenere modificazioni scheletriche, essa comporta inevitabilmente anche una componente dento-alveolare. Infatti, i primi molari permanenti superiori sono spesso coinvolti in maniera indiretta, cioè possono subire movimenti tridimensionali indesiderati che potrebbero avere un impatto sulla stabilità del trattamento. La distribuzione degli effetti dento-alveolari prodotti dal trattamento è un fattore da tenere in considerazione durante la terapia di espansione. Obiettivo: Valutare le modificazioni tridimensionali della posizione dei primi molari permanenti superiori e la risposta dento-alveolare in pazienti in crescita dopo espansione mascellare con Leaf Expander®, confrontando due configurazioni: con o senza estensioni distali. Materiali e Metodi: In questo RCT, 30 pazienti (CVMS 1–2), in dentizione mista precoce, con discrepanza trasversale posteriore ≥3 mm e primi molari permanenti completamente erotti, sono stati randomizzati a ricevere il Leaf Expander® con (n=15) o senza (n=15) estensioni distali. Criteri di esclusione: malattie sistemiche o sindromi, stadio puberale/post-puberale, agenesia dei secondi premolari superiori, assenza dei secondi molari decidui, Classe III scheletrica. L’espansore è stato cementato sui secondi molari decidui e attivato mensilmente fino alla sovracorrezione. Le scansioni digitali intraorali sono state effettuate prima (T0) e dopo il trattamento (T1). L’angolazione coronale dei molari è stata misurata tramite software 3D; rotazione molare e variazioni trasversali (intercanina, interdecidua, intermolare, perimetro d’arcata) sono state valutate su modelli digitali. L’affidabilità è stata misurata con ICC. L’analisi statistica ha incluso t-test appaiati e indipendenti, e regressione lineare (p<0,05). Risultati: Nessuna differenza significativa è stata rilevata tra i gruppi al baseline (p>0,05). Tutti i parametri hanno mostrato miglioramenti significativi da T0 a T1 in entrambi i gruppi (p<0,05). Il gruppo senza estensioni ha evidenziato aumenti maggiori nelle distanze intercanina e interdecidua, e una più marcata derotazione dei molari (D16, D26) (p<0,05). Il gruppo con estensioni ha mostrato un incremento significativamente maggiore nell’angolazione vestibolare dei molari (p<0,05). Nessuna differenza significativa è emersa per l’ampiezza intermolare permanente o il perimetro d’arcata (p>0,05). Conclusioni: La presenza delle estensioni distali ha limitato l’espansione intercanina e la derotazione spontanea dei primi molari, inducendo però una maggiore inclinazione vestibolare. Tali braccetti non influenzano l’espansione trasversale a livello dei molari permanenti né l’aumento del perimetro d’arcata. Il design dell’apparecchio può modulare selettivamente la risposta dento-alveolare al trattamento ortopedico.
Impatto delle Estensioni Distali sulla Risposta Dento-Alveolare Tridimensionale e sulla Posizione dei Primi Molari Permanenti Superiori dopo Espansione Mascellare in pazienti in crescita: Studio Randomizzato e Controllato
BAISI, ANNALISA
2025/2026
Abstract
Introduction: Transverse maxillary deficiency is a very common condition in growing patients. It is a frequent form of malocclusion that manifests during the primary and mixed dentition stages and is often clinically associated with posterior crossbite, either unilateral or bilateral. Failure to diagnose and treat this condition early may lead over time to the development of skeletal asymmetries and impairments in the growth and function of craniofacial structures. Palatal expansion is a primary therapeutic procedure for growing patients with transverse maxillary deficiency, aiming to correct maxillary constriction and restore proper dentoskeletal balance. The use of palatal expanders anchored to primary teeth during mixed dentition allows for a greater orthopedic effect while reducing dentoalveolar side effects on permanent teeth. However, although the primary objective of palatal expansion is to achieve skeletal modifications, it inevitably also produces dentoalveolar changes. In particular, the maxillary first permanent molars are often indirectly involved and may undergo undesirable three-dimensional movements that could affect treatment stability. Therefore, the distribution of dentoalveolar effects induced by expansion therapy should be carefully considered during treatment planning. Objective: To evaluate the three-dimensional positional changes of the maxillary first permanent molars and the dentoalveolar response in growing patients following maxillary expansion with the Leaf Expander®, comparing two appliance configurations: with and without distal extensions. Materials and Methods: In this randomized controlled trial (RCT), 30 patients (CVMS stages 1–2) in early mixed dentition, presenting with a posterior transverse discrepancy ≥3 mm and fully erupted maxillary first permanent molars, were randomly assigned to receive a Leaf Expander® either with distal extensions (n = 15) or without distal extensions (n = 15). Exclusion criteria included systemic diseases or syndromes, pubertal or post-pubertal growth stage, agenesis of the maxillary second premolars, absence of the second primary molars, and skeletal Class III malocclusion. The expander was cemented on the second primary molars and reactivated monthly until overcorrection was achieved. Digital intraoral scans were obtained before treatment (T0) and after treatment (T1). Molar crown angulation was assessed using 3D software, while molar rotation and transverse dimensional changes (intercanine, inter-primary molar, intermolar widths, and arch perimeter) were evaluated on digital models. Reliability was assessed using the Intraclass Correlation Coefficient (ICC). Statistical analysis included paired and independent t-tests, as well as linear regression analysis (p < 0.05). Results: No significant differences were observed between the groups at baseline (p > 0.05). All measured parameters showed significant improvements from T0 to T1 in both groups (p < 0.05). The group without distal extensions exhibited greater increases in intercanine and inter-primary molar widths, as well as a more pronounced derotation of the maxillary first permanent molars (teeth 16 and 26) (p < 0.05). Conversely, the group with distal extensions demonstrated a significantly greater increase in buccal crown angulation of the molars (p < 0.05). No significant differences were found between the groups regarding permanent intermolar width or arch perimeter increase (p > 0.05). Conclusions: The presence of distal extensions limited intercanine expansion and spontaneous derotation of the maxillary first permanent molars, while promoting greater buccal tipping of these teeth. However, distal extensions did not affect transverse expansion at the level of the permanent molars nor the increase in arch perimeter. Appliance design may selectively modulate the dentoalveolar response to orthopedic expansion therapy.| File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14251/7563