# Skeletal and dentoalveolar effects on the midpalatal suture and maxillary arch assessed by occlusal radiographs and three-dimensional digital models in patients treated with invisalign palatal expander and rapid palatal expander: a pilot study.

- **DOI:** [10.3389/fdmed.2026.1757094](https://doi.org/10.3389/fdmed.2026.1757094)
- **Rating:** Limited (2.8 out of 5)
- **Verdict:** IPE provides preliminary evidence of midpalatal suture opening, but uncontrolled group allocation prevents a reliable claim of equivalence with Hyrax.
- **Framework version:** v5.9
- **Pipeline version:** v0.4
- **Evaluation date:** 2026-09-18
- **Evaluation page:** https://www.nabu.science/paper/10.3389%2Ffdmed.2026.1757094

## Key claims

1. Midpalatal suture opening was achieved in all patients.
   - Support: Supported
   - Type: Primary finding
   - Basis: direct within-sample observation from a small non-randomized pilot using corrected occlusal radiographs
   - Location: Abstract, Results
2. The observed outcomes were largely comparable to those achieved with rapid maxillary expansion using a Hyrax expander for most occlusal parameters and for all radiographic parameters evaluated.
   - Support: Tentative
   - Type: Secondary
   - Basis: comparability inferred from underpowered null tests in uncontrolled, imbalanced treatment groups
   - Location: Conclusions
3. Although the amount of expansion was slightly lower, the IPE demonstrated more controlled and predictable results, supporting its use as a valid alternative in mixed dentition
   - Support: Tentative
   - Type: Secondary
   - Basis: predictability and clinical validity exceed what confidence-interval width and a 30-patient pilot establish
   - Location: Abstract, Conclusions

## Strengths

- **Direct evidence of suture opening** Occlusal radiographs showed midpalatal suture opening in the analyzed patients, supplying initial clinical evidence for a newly introduced removable expander.
  - Dimension: contribution
  - Location: Results, Radiographic Analysis; Discussion, midpalatal-suture paragraphs
- **Explicit measurement error correction** Radiographic measurements were corrected against the actual size of tooth 2.1, while digital models supplied the anatomical reference and occlusal measurements.
  - Dimension: methodological rigour
  - Location: Materials and Methods, Study Design
- **Limitations linked to future studies** The Discussion connects small sample size, immediate follow-up, and absent three-dimensional imaging to limits on power, generalizability, stability, and spatial skeletal characterization.
  - Dimension: positioning
  - Location: Discussion, limitations paragraph

## Limitations

- **No credible confounding control strategy** Treatment allocation is not described, and the Hyrax and IPE groups have markedly different sex distributions without adjustment, matching, or sensitivity analysis.
  - Dimension: methodological rigour
  - Location: Materials and Methods, Sample and Study Design; Results, opening paragraphs
- **Null results framed as comparability** The paper interprets non-significant differences as comparable outcomes despite analyzing 30 participants when its own calculation specifies 56 for 80% power.
  - Dimension: reporting
  - Location: Abstract, Results and Conclusions; Sample Size
- **Decisive baseline limitation goes unacknowledged** The limitations section discusses sample size, follow-up, imaging, and pain assessment but does not trace the undisclosed allocation process or sex imbalance through the head-to-head interpretation.
  - Dimension: positioning
  - Location: Results, opening paragraphs; Discussion, limitations paragraph

## Reliability checks

Caveats (4 of 4 checks).

- **Internal coherence:** Noted. The reported observations are broadly coherent, but the comparative interpretation is less secure than the numerical presentation suggests. Baseline imbalance, inadequate power for null comparisons, and an unresolved citation placeholder warrant caution.
- **Research conduct:** Noted. Ethics approval and parental informed consent are declared. The supplied text contains no author-level conflict-of-interest statement despite evaluating a named commercial device; unavailable supplementary files remain an assessability gap rather than a conduct concern.
- **Reference integrity:** Clean. 39 of 39 checkable references verified
  - 42 references in manuscript
  - 3 have no canonical index record — counted, but not index-checkable
  - 1 reference confirmed by manual review
  - References not verified automatically are resolved manually within 24 hours.

## Post-publication record

- **Status:** Clean
- **Summary:** No retraction or expression of concern found in Crossref (includes Retraction Watch).
- **Last checked:** 2026-10-17