## 4 Discussion  
The severity of the injury is considered one of the most important factors affecting the healing of damaged tooth structures [20]. Apart from that, the stage of root development, compression of tissues (pulp, PDL, bone), patient's age, and bacterial contamination are also found to have a significant impact on regeneration/repair potential. The value of splinting in healing appears questionable. An evidence-based appraisal of splinting luxated, avulsed, and root-fractured teeth revealed that the healing outcomes are determined by the type of the injury rather than factors associated with splinting, such as type of the splint or the fixation period [21]. Another study suggests that the likelihood of successful periodontal healing after replantation of avulsed teeth is unaffected by splinting duration [22]. However, both of these papers were based upon studies not providing the highest level of evidence and the authors recommend that dentists should follow the current guidelines while splinting injured teeth. Although the role of splints in promoting optimal healing of injured dental tissues remains unclear, their use is still accepted and recommended. In terms of a medico-legal aspect, applying a splint is relevant for creating a safe environment that prevents additional trauma, accidental ingestion, and aspiration of replanted or a repositioned tooth. From a biomechanical point of view, there are two factors that promote tissues healing: (1) low-magnitude strains induction to the tissues and (2) a controlled micromovement of the tooth in the traumatized socket (approximately 50 \(\upmu\)m) [13; 23]. The micro tension across the healing wound has a positive effect on the activity of fibroblasts responsible for the production of procollagen and on the production and maturation of collagen [23]. However, excessive loading should be avoided. Both types of splints, rigid and flexible ones, reduce stresses in comparison with non-splinted teeth. This is due to the lack of load partitioning between teeth via a splint in the un-splinted group [23]. Moreover, the splinting materials with three different flexibility patterns (rigid, semi-rigid, and flexible) used for tooth replantation elicit similar biomechanical behavior of bone structures and PDL [24]. That means that even the splint which is classified as rigid displays some amount of flexibility allowing for some tension to be transferred to traumatized structures. However, the greatest stress concentration is observed in the alveolus of a traumatized tooth when rigid material is used [24]. It has been proven that masticatory stimulation during the healing period partially prevents or reduces the development of ankylosis in replanted teeth [25] and promotes regeneration of the PDL [26]. That is why flexible splints that allow for physiological tooth mobility are recommended. Excessive forces, especially during the initial period of healing, cause occlusal trauma, which may lead to severe root and bone resorption [26]. According to researchers, the teeth need protection from such traumatic forces for one week after replantation to let the PDL heal [26]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Split** & **\(\Delta\)PTV Horizontal** & **\(\Delta\)PTV Vertical** \\ \hline Wire Composite Splint & \(0.45\pm 0.57\) & \(0.10\pm 1.19\) \\ Power Chain Splint & \(0.27\pm 0.82\) & \(-0.95\pm 1.31\) \\ Titanium Trauma Splint & \(0.74\pm 0.122\) & \(-0.46\pm 1.04\) \\ \hline \hline \end{tabular} \(\Delta\)PTV = (pre-application PTV) – (post-application PTV). Positive values represent decreased tooth mobility while negative values increased tooth mobility.  
\end{table} 
Table 10: Splint effects (\(\Delta\)PTV) for lateral incisors.