# Lower Molar Distalization Using Clear Aligners: Bodily Movement or Uprighting? A Preliminary Study
## 4 Discussion  
The aim of the study was to assess the lower molar distalization using clear aligners and evaluate the possibility of gaining tipping or bodily movement. Results suggests that the sequential distalization protocol for lower molars determines mainly a tipping movement rather than a true distal translation. All the cases presented good occlusion at the end of the treatment, with Class I molar and canine relationship, adequate anterior overjet and overbite and no signs or symptoms of TMD were revealed during or after the therapy. One of the key factors in class III cases, is the control of interincisal angle. The planning was set with the aim of a final stable incisal angle of approximately \(131^{\circ}\). Reaching this angulation, it is possible to correct anterior relationship, starting from an edge-to-edge bite or anterior crossbite to a normal overjet relationship. Currently, in the scientific literature analysis of this type of treatment is lacking, there are just few case reports. The predictability of maxillary molar distalization using aligners is high (88%) and well demonstrated by [PERSON] et al. [30]. The paper published by [PERSON] et al. [31] confirmed these results. Therefore, aligners seem to be effective in preventing distal tipping and extrusion when an upper molar distalization is programmed. According to the results of the study, no distal bodily movement was always achieved, so it is reasonable to think that uprighting is enough to correct the dental relationship. This statement is confirmed by the results that, although not statistically significant, showed \begin{table}
\begin{tabular}{l l l l l l} \hline \hline  & **MD T0-T1** & **Standard Error** & \(p\) **Value** & **Lower 95\% IC** & **Upper 95\% IC** \\ \hline SNA & 0.24 & 1.08 & 0.827 & \(-1.88\) & 2.35 \\ \hline SNB & 0.22 & 1.21 & 0.853 & \(-2.14\) & 2.59 \\ \hline ANB & 0.01 & 1.16 & 0.996 & \(-2.28\) & 2.29 \\ \hline Wits & 0.79 & 1.41 & 0.581 & \(-1.98\) & 3.55 \\ \hline SN-MP & 0.14 & 2.02 & 0.946 & \(-3.82\) & 4.09 \\ \hline PP-MP & 0.81 & 2.42 & 0.742 & \(-3.95\) & 5.56 \\ \hline Overjet & 1.27 & 0.8 & 0.127 & \(-0.31\) & 2.85 \\ \hline Overbite & 0.23 & 0.7 & 0.744 & \(-1.14\) & 1.6 \\ \hline
37 mc-CoGo & \(-1.79\) & 1.57 & 0.264 & \(-4.87\) & 1.29 \\ \hline
37 cc-CoGo & \(-2.47\) & 1.48 & 0.106 & \(-5.37\) & 0.43 \\ \hline
37 mra-CoGo & \(-0.85\) & 1.63 & 0.606 & \(-4.05\) & 2.34 \\ \hline
37 ax-CoGo & \(-4.56\) & 4.15 & 0.281 & \(-12.71\) & 3.59 \\ \hline
37 ax-CoMe & \(-4.47\) & 1.92 & 0.027 & \(-8.24\) & \(-0.69\) \\ \hline
36 mc-CoGo & \(-1.07\) & 1.61 & 0.513 & \(-4.23\) & 2.09 \\ \hline
36 cc-CoGo & \(-1.16\) & 1.49 & 0.439 & \(-4.07\) & 1.74 \\ \hline
36 mra-CoGo & \(0.15\) & 1.71 & 0.929 & \(-3.19\) & 3.49 \\ \hline
36 ax-CoGo & \(-4.56\) & 2.03 & 0.032 & \(-8.55\) & \(-0.57\) \\ \hline
36 ax-GoMe & \(-5.03\) & 1.59 & 0.003 & \(-8.15\) & \(-1.91\) \\ \hline
31 im-CoGo & \(-1.13\) & 1.52 & 0.463 & \(-4.12\) & 1.85 \\ \hline
31 ax-CoGo & \(-4.18\) & 2.44 & 0.097 & \(-8.98\) & 0.61 \\ \hline
31 ax-GoMe & \(-4.78\) & 2.19 & 0.037 & \(-9.09\) & \(-0.47\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cephalometric values analyzed. a distal movement of the second molar, with a mean decrease of 2.47 mm of the distance between the central point on the occlusal surface of the second molar and CoGo line, and the first molar, with a mean decrease of 1.16 mm of the distance between the central point on the occlusal surface and CoGo line; both these changes are clinically evident. As a matter of fact, in an adult patient, the correction of the dental relationship through molar distalization requires about 2 mm of space distally. In order to gain it, it is necessary to create space, which is why it is considered useful to extract the third molars before starting the treatment, if they were present. Furthermore, as the patients enrolled in the study are adults, an increase in mandibular size is not expected during treatment due to the normal growth process and this represents a favorable data for correction.