A small, low‑quality study tested thymosin‑alpha‑1 on knocked‑out front teeth and saw a hint it might help the gums and keep the tooth alive, but the evidence is weak and not reliable for everyday use.

Traumatic dental injuries are common. One of the most severe injuries is when a permanent tooth is knocked completely out of the mouth (avulsed). In most circumstances the tooth should be replanted as quickly as possible. There is uncertainty on which interventions will maximise the survival and repair of the replanted tooth. This is an update of a Cochrane Review first published in 2010. To compare the effects of a range of interventions for managing traumatised permanent front teeth with avulsion injuries. Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 8 March 2018), Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 2) in the Cochrane Library (searched 8 March 2018), MEDLINE Ovid (1946 to 8 March 2018), and Embase Ovid (1980 to 8 March 2018). The US National Institutes of Health Ongoing Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We considered randomised and quasi-randomised controlled trials that included a minimum follow-up period of 12 months, for interventions for avulsed and replanted permanent front teeth. Two review authors independently selected studies, extracted data and assessed the risk of bias. Authors were contacted where further information about their study was required. 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.