3D occlusal changes of upper first molars after rapid maxillary expansion on permanent versus deciduous teeth: a retrospective multicenter CBCT study
Bibliographic record
Abstract
BACKGROUND: The purpose of this study was to compare the three-dimensional dental changes for the maxillary first molars and the overall skeletal effects achieved after expansion between the rapid maxillary expansion (RME) appliance attached to two different anchor units, the maxillary deciduous molars and the maxillary permanent first molars. METHODS: Patients were retrospectively selected according to the anchorage unit used for RME: deciduous upper second molars (RME-E group; 10 M, 10 F; mean age 8.4 ± 1.1 years) and first upper permanent molars (RME-6 group; 10 M, 10 F; mean age 12.6 ± 1.8 years). CBCT scans were obtained before treatment start (T1) and after retention and removal of the expander (T2). Images were analyzed using a new three-dimensional intra-hemi-maxillary reference system. 3D landmarks were marked to calculate all changes on maxillary first permanent molars; mesio-distal and buccal-lingual inclination and rotation, as well as intermolar and interforaminal distances were calculated. The Wilcoxon test was used to compare within-group changes, whereas the Mann-Whitney test was used to compare between-group differences, with the significance level set at 0.05. RESULTS: In the RME-E group, significant distorotation and lingual inclination of the first permanent molars at T2 were observed (p < 0.01); in the RME-6 group, only the buccolingual inclination of the crossbite side after RME was resulted statistically significant (p < 0.01). In both groups, intermolar and interforaminal values increased significantly (p < 0.01). Intergroup analysis showed a significantly higher distorotation and reduced buccal inclination of maxillary first permanent molars in the RME-E group after RME (p < 0.01). CONCLUSIONS: RME is effective in treating maxillary transverse hypoplasia; RME anchored too deciduous teeth spontaneously reduces buccal inclination and increases distorotation of maxillary first permanent molars, whereas anchorage to permanent molars is associated with increased buccal inclination, albeit with little clinical significance.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".