Pulp revascularization can sterilize the tooth root, transform the necrotic pulp tissue into a sterile matrix, then stimulate the root tip bleeding, form a blood clot in the root canal, and generate pulp-like tissue to promote the continued development of the tooth root and improve the crown. Root ratio, to improve the strength of tooth roots, presents a better application prospect [
15,
16]. PRF can assist in the application of pulp revascularization of mature permanent teeth, and the effect is good [
17].
Pulp revascularization can protect the liver cells and active tissues around the roots of the patient's teeth, introduce the patient's own blood, form a biological scaffold, and promote the generation of tissues similar to the pulp [
18]. This tissue has the sensation and function of normal pulp, which can enable mature permanent teeth to continue to develop, and eventually reach a level close to that of normal teeth, which is conducive to improving the hardness of the teeth, the thickness of the root canal wall, and the length of the root [
19,
20]. Wu Tiantian [
21] pointed out in the research that PRF is derived from the body, and the joint action of various components in inflammation regulation, angiogenesis, soft and hard tissue repair and regeneration and other physiological processes play important functions, and it has been gradually applied to young people. Permanent tooth pulp regeneration, apical barrier, delayed replantation and vital pulp preservation treatments, and the effect is good. Relevant data show that [
22], pulp revascularization can repair infected or necrotic pulp, allow tooth roots to grow and develop, improve crown-to-root ratio, and increase root strength. The results of this study showed that the total effective rate of the experimental group (100.00%) was higher than that of the control group (50.00%), the thickness of the root canal wall of the experimental group was higher than that of the control group, and the crown root length was lower than that of the control group (
P < 0.05). After the treatment, the thickness of the root canal wall and the length of the crown root have been improved, and most of the patients have achieved good results. This indicates that pulp revascularization promotes the continued development of the tooth root and accelerates the restoration of normal function of the tooth root. The reason is that, on the one hand, PRF provides a good root canal stent, providing sufficient space to store the hard tissue deposits on the inner wall of the root canal; on the other hand, PRF is rich in active factors, including cell chemokines, which promote cell entry and thereby Promote the restoration of dental pulp tissue [
23,
24]. This is consistent with the research results of He X [
25], which further confirms that PRF can provide a good scaffold material for pulp regeneration and the effect of pulp restoration is ideal. After treatment, the bite degree, chewing function, color, overall aesthetic score, and satisfaction of the experimental group were higher than those of the control group. Zhang Xin and others [
26] selected 62 children with pulp necrosis as the research object. The control group underwent conventional pulp revascularization, and the observation group received PRF during the pulp revascularization. The total success rate of the observation group was 96.77%, which is significantly higher than 74.19% in the control group (
P < 0.05). It is concluded that the application of PRF to young permanent teeth during pulp revascularization can improve the total success rate of treatment, postoperative root length and root canal wall thickness. The effect is better than that of conventional pulp revascularization surgery.
PRF is a fillable fibrin complex composed of platelets, cytokines and white blood cells. Compared to platelet-rich plasma, PRF is more economical and easier to prepare and is feasible in clinical practice [
27]. Due to the great potential of PRF in clinical application. Its related technology is also constantly improving [
28]. By adjusting the centrifugation procedure, injectable platelet rich fibrin (I-PRF) can be prepared without the use of anticoagulants. I-PRF has a three-dimensional fibrin meshwork while retaining the fluid nature, which has higher antibacterial, anti-inflammatory and regeneration abilities [
29,
30]. With reference to the preparation protocol of I-PRF, higher concentrations of platelets and leukocytes were obtained from the buffy coat layer by high-speed centrifugation, which was named concentrated PRF (C-PRF). The growth factor release from C-PRF was then significantly increased and showed greater potential for cell migration and proliferation [
31]. According to the "Low-Speed Centrifugation Concept", the preparation of PRF was further modified. An important product is Advanced-PRF (A-PFR), which leads to an increase in the number and distribution of platelets and leukocytes in the fibrin meshwork [
32]. A-PRF is a variant of standard PRF that contains more growth factors with better regeneration potential and is commonly used in periodontal regeneration and implant surgery. The abovementioned materials provide a variety of therapeutic materials for dental pulp revascularization.
Recommendations for future
Although this study confirmed the effectiveness of autologous PFR, PRF was still a complex mixture of multiple cytokines, growth factors, platelets, and various white blood cells. Furthermore, it is necessary to identify the major components that are beneficial for pulp revascularization based on omics research. The concentration and content of such beneficial components can be increased by adding exogenous active components, molecular ultrafiltration, etc., to further improve the therapeutic effect.