## 3 Results
### Study Selection and Study Characteristics
 &
\begin{tabular}{l} **Group 2** \\ **Group 2** \\ **Group 2** \\ **Group 2** \\ **Group 2** \\ **Group 2** \\ **(S1) \\ **(S2) \\ **(S3) \\ **(S4) \\ **(S5) \\ **(S6) \\ **(S7) \\ **(S8) \\ **(S9) \\ **(S10) \\ **(S11) \\ **(S2) \\ **(S3) \\ \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Type of Model** & **Digital Analysis** & **Type of Specimens** & **Minimum Mean** & **Group (min)** & **Maximum Mean** & **Group (max)** \\  & **Software** & **Type of Specimens** & **Volumetric Loss** & **MVD** & **Volumetric Loss** & **MVD** \\ \hline  & & & 120 extracted permanent intact bovine & & & \\  & & & incisors. 12 upper dental arches were & & & \\  & & & produced fitting 10 teeth (from tooth 15 to & & \\ [PERSON] et al. & 2019 [33] & 3D scan & OxCheck (Version 2.13.66\%, Cytex AG, Zurich, Zurich, Switzerland) & 25) on a wax plate, with interproptical contacts as similar as possible to the & 0.17 (SD = 0.21) & Group 2A & 0.61 GD = 0.51 (IB), Groups 1B \\  & & & maxillary dental arch, wuck through & & SD = 0.37 (ZB)) & and 2B \\  & & & hot-setting glue, and merged into hot copper (ProBase, Iocular Vivadat AG, Shams, Lichtenstein) & & & \\  & & & 56 extracted human permanent teeth were & & \\  & & & collected. Two maxillary and two & & \\  & & & mandibular dental arches were developed: & & \\  & & & & Fourteen teeth ranging from 17 to 27 and 37 & & \\  & & & 047 respectively were positioned in their & & \\  & & & intra-arch locations with interproptical contacts as similar as possible to a dental & & \\ [PERSON] et al. & 2022 [35] & 3D tooth model & (Version 2.13.86\%, Cytex AG, Zurich, Switzerland) & 20.34 & & \\ [PERSON] et al. & 2022 [35] & 3D tooth model & OracCheck software (Version 2.13.86\%, Cytex AG, Zurich, Switzerland) & 20.34 & & \\  & & & through hot-setting glue, and merged into a & & \\  & & & bufferboard (ProBase, Iocular, Vivadent AG, Vivadent AG, Schaan, Liechtenstein). A & & \\  & & & gingvisor was mask mask modelled (BellALDI & & \\  & & & Superior Rosa, Bellad, Weld Scherbester, & & \\  & & & Amriwitt, Switzerland) and then replaced & & \\  & & & with silicone material (Hungem Premium, Fino, Bado, Buckler, Germany) & & \\ [PERSON] et al. & 2022 [34] & Micro-CT 3D reconstruction & CTAn (SkyScan, Bruker, Billerica, MA, USA) & 42 extracted maxillary first preambles with & 0.02 (SD = 0.01 (IB), & Groups 1B \\  & & & Bruker, Billerica, MA, USA) & 3D = 0.00 (IC)) & and IC & 0.11 GD = 0.18) & Group 2A \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._All investigations were published between 2004 and 2022. No in vivo papers were retrieved. No papers investigating clear aligners attachment clean-up were retrieved. Four researches were conducted on human premolars [25; 28; 29; 34]. Three studies used human molars [5; 31; 32], one analyzed all types of permanent teeth [35], and, in one investigation, bovine permanent incisors were selected as specimens [33]. Metal and ceramic brackets were distributed among included studies as follows: metal brackets were chosen in seven studies [5; 25; 28; 31; 32; 33]; ceramic brackets were used in one; and both metal and ceramic brackets were selected in one paper. Only one paper investigated lingual appliances [35]. For the debonding procedure, all studies removed brackets conventionally with the use of a different hand. The clean-up procedure varied among all investigations. All studies that performed the clean-up phase included at least one group with multi-fluted tungsten carbide burs, making it the most investigated tool. In order to assess the volume loss related to debonding and clean-up procedures, all studies performed a volumetric acquisition at baseline and one at the end of all procedures. Six articles used an optical scan [5; 29; 31; 32; 33; 35], one used a null-point stylus system [25], one used a Micro-CT scan followed by a 3D file reconstruction [34], and one used a contact profilometer [28]. Both baseline and after debonding/clean-up acquisitions were superimposed, and the volumes were subtracted using different digital analysis software.