Abstract: Four studies, involving a total of 183 participants and 257 teeth were identified. Each of the interventions aimed to reduce infection or alter the inflammatory response or both at the time of or shortly after the tooth or teeth were replanted. Each study assessed a different intervention and therefore it was not appropriate or possible to numerically synthesise the data. All evidence was rated as being of very low quality due to problems with risk of bias and imprecision of results. This means that we are very uncertain about all of the results presented in this review. One study at high risk of bias with 69 participants (138 teeth) compared a 20-minute soak with gentamycin sulphate for both groups prior to replantation with the experimental group receiving daily hyperbaric oxygen for 80 minutes for the first 10 days. There was some evidence of a benefit for the hyperbaric oxygen group in respect of periodontal healing, tooth survival, and pulpal healing. One study at unclear risk of bias with 22 participants (27 teeth) compared the use of two root canal medicaments, Ledermix and Ultracal. There was insufficient evidence of a difference for periodontal healing or tooth survival. This was the only study to formally report adverse events with none identified. Study authors reported that Ledermix caused a greater level of patient dissatisfaction with the colour of avulsed and replanted teeth. A third study at high risk of bias with 19 participants compared extra- or intra-oral endodontics for avulsed teeth which were stored dry for longer than 60 minutes before replantation. There was insufficient evidence of a difference in periodontal healing. The fourth study at high risk of bias with 73 participants compared a 10-minute soak in either thymosin alpha 1 or saline before replantation followed by daily gingival injections with these same medicaments for the first 7 days. There was some evidence of a benefit for thymosin alpha 1 with respect to periodontal healing and tooth survival. Based on the results of the included studies, there is insufficient evidence to support or refute the effectiveness of different interventions for avulsed and replanted permanent front teeth. The overall quality of existing evidence was very low, and therefore great caution should be exercised when generalising the results of the included trials. There is urgent need for further well-designed randomised controlled trials.

Plain-language summary: Authors from Cochrane Oral Health carried out this review and the evidence is up to date to 8 March 2018. The review investigated what treatments encourage the tooth to repair by periodontal healing. A total of four studies were included with a total of 183 participants with 257 teeth. One study involved children and young adults, with the other three involving children only. Each study evaluated a different treatment: hyperbaric oxygen, root canal pastes (Ledermix versus Ultracal), removal of the nerve of the tooth (pulp extirpation), and soaking the knocked out tooth in thymosin alpha 1. Each of the interventions aimed to reduce infection or change the inflammatory response or both, at the time of or shortly after the tooth or teeth were replanted. The evidence currently available is insufficient to draw reliable conclusions regarding the superiority of different interventions for knocked out and replanted permanent front teeth. There is urgent need for further well-designed randomised controlled trials. We judged the quality of the evidence to be very low due to problems with the design of the studies.