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Association between post-expansion pterygopalatine suture splitting phenotypes and maxillary first molar dentoalveolar changes: a retrospective CBCT study

Year: 2026

Type: article

Abstract: The post-expansion pterygopalatine suture (PPS) splitting phenotype is an imaging-defined feature observed after maxillary skeletal expander (MSE) treatment. This study investigated the association between post-expansion PPS splitting phenotypes and maxillary first molar dentoalveolar changes; transverse expansion outcomes were secondary. This retrospective observational study included 90 patients aged 13–26 years treated with MSE and classified into bilateral split (BS), unilateral split (US), and non-split (NS) groups ( n = 30 each). Pre-expansion (T0) and post-expansion (T1) CBCT scans were analyzed. Primary outcomes were side-specific changes in the cementoenamel junction (CEJ)-to-buccal alveolar crest distance, buccal bone thickness 6 mm apical to the CEJ, and maxillary first molar tipping. Within the US group, split and non-split sides were compared. Secondary outcomes included changes in nasal width, hard palate width, and maxillary first molar furcation-center intermolar width. Linear mixed-effects models with Holm-adjusted pairwise comparisons were used. The mean age was 18.31 years (SD, 3.68). Significant time × side-pattern interactions were observed for all three primary outcomes (all P < 0.001). Across the model-based pairwise comparisons, non-split side patterns showed approximately 0.5 mm greater increases in the CEJ-to-buccal alveolar crest distance, 0.5 mm greater reductions in buccal bone thickness, and approximately 4.6° greater molar tipping than split side patterns. Within the US group, changes in all three outcomes were significantly greater on the non-split side than on the contralateral split side (all P < 0.001). Significant time × phenotype interactions were also observed for nasal width, hard palate width, and maxillary first molar furcation-center intermolar width ( P = 0.004, P = 0.031, and P < 0.001, respectively), with generally greater increases in the split phenotypes than in the NS phenotype. Post-expansion PPS splitting phenotype was associated with side-specific maxillary first molar dentoalveolar changes and transverse expansion outcomes after MSE treatment. Non-split sides showed greater increases in the CEJ-to-buccal alveolar crest distance, greater reductions in buccal bone thickness, and greater molar tipping.

Source: BMC Oral Health

DOI: 10.1186/s12903-026-09643-2