## 5 Discussion  
Tooth autotransplantation TAT offers a viable biological approach to tooth replacement in children and adolescents after traumatic dental injuries (TDIs), agenesis, developmental anomalies, or specific orthodontic problems [25; 26; 27; 28; 29]. In a recent systematic review, [PERSON] et al. [28] reported an overall survival rate for conventional TAT ranging between 93% and 100% (weighted mean: 96.7%, median: 100%) after 9 months to 22 years of observation (median: 8.75 years). The survival rates for conventional TAT of teeth with incomplete root formation was reported to be 97.4, 97.8, and 96.3% after 1, 5, and 10 years, respectively [29]. Studies reporting on the aesthetic results after TAT are limited [28]. [PERSON] et al. [38] reported a clinical assessment of a reshaped autotransplanted tooth using composite build-ups compared to a natural contralateral tooth according to objective parameters. Figure 3: (**A**) stereomicroscopy gap measurements; (**B**) distribution of the gap thickness between the veneer and the tooth. The authors reported a 59% match, 27% deviation, and 14% mismatch with the natural contralateral tooth [38]. While restoring or reshaping transplanted teeth to the anterior maxilla is essential for psychological and aesthetic reasons [36], reshaping of transplanted teeth is usually delayed three to four months after transplantation to avoid interfering with the natural healing process [28; 29; 38; 43]. This interval could be bridged using a simple indirect temporary aesthetic restoration for autotransplanted teeth. The current report proposes a digital technique for designing and fabricating temporary veneers for autotransplanted teeth via chair side 3D printing technology, namely DLP. Simultaneously, the accuracy of this printing technology was validated by examining the marginal and internal adaptation of these temporary veneers. A precise fit is an essential requirement for any dental restoration or prostheses. Ill-fitting prostheses will result in damage for the periodontitis, tooth structure, and the prosthesis itself [23; 44; 45]. This study applied two methods for evaluating the adaptation of the veneers: direct view with microscope to measure the marginal fit, and \(\upmu\)CT to evaluate the internal adaptation. Although there is no consensus about the best method to examine the marginal adaptation of fixed dental prosthesis, a direct view method is the most used method and with the most reproducible results. In the present study, marginal gaps were measured by stereomicroscopy (direct viewing method), resulting in a mean of a marginal gap of 100 \(\upmu\)m, which is below the clinically acceptable value of marginal gaps of 120 \(\upmu\)m [46; 47]. To assess internal adaptation, \(\upmu\)CT scans of the maxillary central incisor shaped veneers fitted on premolars, simulating the clinical situation, were used. The majority of the studies where \(\upmu\)CT was used to assess internal adaptation performed two dimensional measurements of the internal gaps on cross sectional slides [48; 49], while in this study, three-dimensional evaluation of the internal gap was applied. The average median thickness of the internal gaps in the present study was 152 \(\upmu\)m, which is within the accepted values [50; 51; 52]. In a 2-year follow-up study on the use of 3D printed veneers, values of internal adaptation of porcelain laminate veneers ranged from 195 to 202 \(\upmu\)m, which is higher than our values, while clinical performance was rated 100% satisfactory over the 2-year period [52]. One of the potential limitations of the suggested protocol is the use of one specific 3D printing technology and one specific printing material. Future studies are needed to study different 3D printing technologies other than DLP, while using other printing materials.