Bone density in the AS ROI and the PS ROI
at T0 (563.3 6183.2 HU and 741.7 6167.1 HU, respectively) were significantly smaller than values in the AB ROI and the PB ROI at T0 (1057.5 6129.4 HU and 1102.8 6160.9 HU, respectively).
At T0 there was a significant difference in bone density at AS and PS ROIs, but no difference at T1 and T2.
AS and PS ROIs showed significant decreases in density from T0 to T1, significant increases from T1 to T2, and no statistically significant differences from T0 to T2.
No statistics reported. Immediately post expansion all 3 patients had a bone fill score = 0. At 2 and 4 months of expansion there was low echogenicity in the suture (US bone fill score = 1) for 2 of 3 subjects. The remaining patient had a bone fill score = 2 at 2 and 4 months respectively. At 6 months post expansion and 2 months after expander removal, 2 of the 3 patients showed a qualitative increase in echogenic material in the suture was seen but less than 100% therefore had a bone fill score = 2, and the remaining patient demonstrated 100% echogenic material, bone fill score = 3. All trends in scores over time were qualitatively confirmed with plain radiographic images.
No age dependent
significance was found for the mean obliteration index (P = 0.244).
The mean obliteration index was low, varying in all groups (minimum 0%; maximum 7.3%). Middle-aged group’s mean obliteration index tended to be higher than that of either the younger or older age groups but no significant difference was calculated.
The highest mean obliteration index (of 7.3%) was found in a 44-year-old male. The oldest individual with a mean obliteration index of 0% was a 71-year-old female. At
least one frontal slice per palate – even in the oldest age
group – exhibited a suture completely open cranio-caudally.
Axial plane: No significant differences detected in all age groups regarding means and standard deviations for suture length, linear sutural distance, and interdigitation
Interdigitation index computed
revealed no significant age-dependent differences (P = 0.633).
High standard deviation values for suture length, linear sutural distance and interdigitation index were seen in the <25 yo group and >30 yo group, while the 25–30 yo group had far less variation
Mean error of measurement amounted to 0.12% for the obliteration index, 2.4% for the suture length, and 0.41% for the linear sutural distance.
The intraexaminer and interexaminer reproducibility
values demonstrated agreement, with weighted kappa coefficients from 0.75 (95% [CI], 0.57–0.93) to 0.79 (95%CI, 0.60–0.97), and the reproducibility of examiners with the ground truth demonstrated agreement with weighted kappa coefficients from 0.82 (95% CI, 0.64–0.99) to 0.93 (95% CI, 0.86–1.00).
From the 140 subject sample, stage A was observed in children from 5 to approximately 11 years of age, a 13 year old boy was the sole exception. Should be noted there was no fusion of the palatal suture in subjects aged 5 to almost 11 years old.
Stage B was observed primarily up to 13 years of age but also 6 of 32 subjects (23% of boys, 15.7% of girls) aged 14 to 18 years old.
Stage C primarily depicted from 11 to 18 years of age, with exception being two 10-year-old girls (8.3% of girls) and 4 of 32 adults (15.7% of girls, 7.7% of boys).
Stage D was observed in 1 of 24 girls aged 11- <14 years old, and 3 of 19 girls aged 14–18 years old, as well as in 3 of 13 males aged 14–18 years old and >18 years old respectively.
Stage E was observed in 5 of 24 females aged 11- < 14 years old and 8 of 19 females aged 14–18 years old and 8 of 19 females aged >18 years old. Stage E was observed in far less males, approximately 9 of 13 males aged >18 years old only.
The intra- and inter-examiner reliability analysis demonstrated agreement for fractal dimension, with a weighted kappa coefficient of 0.84 (95% [CI] 0.74–0.93) and 0.67 (95% CI 0.38–0.95) to 0.72 (95% CI 0.48–0.97) respectively.
No subjects had a CVM of 1-IV nor maturational stage A present.
13 of 21 subjects with CVM V were found to have maturational stage B or C (61.9%; males 77.8%, females 50.0%).
42 of 110 subjects with CVM VI were found to have maturational stage B or C (38.2%; males 41.6%, females 34.0%).
Post-hoc analysis demonstrated that maturational stages B, C, D and E were related to differences in mean fractal dimension (P < 0.05).
A negative correlation existed between fractal dimension and maturation stage (−0.623, P < 0.001). Male and Female correlation coefficients determined to be −0.649 (P < 0.001) and −0.569 (P < 0.001) respectively.
A receiver operating characteristic (ROC) curve determined the boundary between maturation stages A–C and D or E. Fusion of palatal suture was determinable as a fractal dimension.
Fractal dimension is a statistically significant indicator capable of predicting dichotomous maturation stages ((A, B, & C) vs. (D or E) (area under ROC curve [AUC] = 0.794, P < 0.001).
At optimal fractal dimension cut-off value of 1.0235, statistical analysis to evaluate the predictive ability of fractal analysis to determine maturation stage ((A, B, & C) vs. (D or E)), noted the following values; specificity 86.6%, Sensitivity 64.9%, false positive rate 35.1%, false negative rate 13.4%, positive predictability 80.3%, and negative predictability 74.6%.
Prepubertal subjects demonstrated a lower bone density at the mid palatal suture as compared to the lateral control ROIs on ossified maxillary bone.
The post-expansion low bone density at the sutural ROIs supported findings that prepubertal RME effectively opens the suture.
Six months of retention following RME allows reorganization and ossification
of the midpalatal suture with sutural bone density values
similar to pre-RME values.
Ultrasound bone fill scores increased directly with the duration of time post active expansion (authors referred to this as part of the expansion period)
Non-invasive US can yield accurate information regarding bone formation at the midpalatal suture in patients undergoing SARME.
Authors note Micro CT analysis disproves the hypothesis of progressive closure of the suture directly related to patient age.
Skeletal age and/or calculation of an obliteration index is not useful in terms of diagnostic criteria to drive clinical decision making regarding the perceived efficacy of non-surgical RME.
Micro-CT Quantification of the midpalatal suture yields very low obliteration and age- independent interdigitation in the coronal plane.
All calculated parameters demonstrated substantial inter-individual and intra-sutural variation.
Utilizing CBCT to assess the midpalatal suture avoids any overlapping of soft and hard tissues.
Authors note that their proposed methodology may be useful in reliably driving clinical decision making as it relates to pursing a non-surgical (RME) or surgical expansion intervention (SARME).
Adult patients possess a greater proportion of non-fused palatal sutures than what is assumed. Therefore age of the patient should not drive SARME initiation.
Authors report a significant correlation between fractal dimension and degree of maturation of the midpalatal suture
Determination of the fractal dimension cut-off value could be used as a reference to pursue RME vs. SARME
Fractal analysis can be utilized to evaluate the degree of maturation at the palatal suture.