The TPA can relieve crowding in the upper arch primarily through molar derotation along with mild transversal dental expansion, thus inducing both increased arch width and perimeter.
Additionally, during molar derotation, transeptal fibers could potentially move deciduous molars or premolars buccally, potentially offering further increases in dental arch width and perimeter [7, 8].
The authors suggested that these results might be due to the presence of increased frictional forces on molar derotation in palatal distalizing mechanics.
Potential problems include the need for multiple staged corrective surgeries (Kritter 1977), the possibility of gradual derotation with growth, and once again, lack of pelvi-femoral stability.
In addition to the amount of derotation, the staging (amount of derotation/aligner) also has a considerable impact on the treatment efficacy: for premolar derotations with a staging <1.5°/aligner, the total efficacy was 41.8% (SD = 0.3), whereas with a staging >1.5°/aligner, the accuracy decreased to 23.2% (SD = 0.2).
uCa excretion was expressed as a molar ratio with uCr.
It should be noted, however, that the total efficacy in our study was composed of the efficacy of the three investigated movements: premolar derotation, molar distalization and incisor torque.
As the results were normally distributed according to the Shapiro-Wilk test, student's paired t-test was used to analyze statistical difference between T2 (clinical achieved tooth movement) and ClinT2 (predicted tooth movement) values in each group (1 3: incisor torque, premolar derotation, molar distalization) for each subgroup (a: using an attachment, b: no attachment/using Power Ridge).
"This is one we need to monitor," Mrs. Levine said, pointing to what looked like a black-and-white photograph of a molar with an old silver amalgam filling.
This is especially true for the first molars of murine rodents, because the upper molar exclusively occludes with the first lower molar [41].
