The PRISMA guidelines 2009 were followed for writing the protocol and the systematic review was registered on PROSPERO. The (PROSPERO registration number: CRD42020222919) [5].

The question was- ‘Does surface treatment affect the success of delayed replantation of permanent anterior teeth with extraoral dry time of more than 60 minutes?’

A search was performed on delayed replantation of avulsed anterior permanent teeth on electronic databases Medline/PubMed, Google Scholar, and Cochrane from the year 2000 to 2018. Manual searches were also performed on the articles retrieved during the electronic search. The MESH terms and keywords like tooth avulsion*, tooth fractures*, tooth injuries*, traumatology*, delayed replantation methods and delayed replantation standards with Boolean operators were used for data identification and screening. Two reviewers independently evaluated every article and in cases of divergence, the decision whether to select the case report, was reached through discussion.

[Table/Fig-1] shows the PRISMA flow diagram for the total number of articles selected for the systematic review.

[Table/Fig-1]:

PRISMA flow diagram.

Inclusion criteria

Exclusion criteria

For evaluating the risk of bias for case reports, no standard quality assessment tools are available. Case report belongs to descriptive studies because they report occurrences of a disease or a unique finding [6]. For judging the quality of case reports for systematic review there is only one tool, the JBI critical appraisal [7]. Two reviewers independently scored the selected papers for these criteria. The criteria shown in [Table/Fig-2] were used to attain the risk of bias [8-12].

All the results of this systematic review are mentioned in [Table/Fig-3].

According to our knowledge, this is the first systematic review on the relation between surface treatment and the outcome of replantation of avulsed teeth. In this systematic review, the extraoral dry time of the five cases varied from 24 hours to 72 hours as mentioned in [Table/Fig-3]. The prognosis is best for teeth replanted within five minutes after avulsion, thereafter the PDL is compromised if the delay is between five minutes to 60 minutes and the PDL becomes non viable when the total extraoral dry time is more than 60 minutes [2].

Avulsed tooth usually after trauma, fall on the ground and a tooth that has been out of the socket for more than 60 minutes, is likely to get contaminated with soil, dirt, microorganisms and handling by the operator, thus making cleaning, disinfecting and surface treatment of utmost importance. The rationale of surface treatment is to remove non viable PDL fibres, which might act as a source of infection and could result in inflammatory resorption. The non viable periodontal tissue could also trigger the undifferentiated mesenchymal cells of the socket and differentiate into osteoblast and lead to replacement resorption i.e., ankylosis. Thus, surface treatment of avulsed tooth plays a pivoted role in successful delayed replantation [1,13,14].

Andreasen JO and Andreasen FM recommended that the avulsed tooth should be soaked in 2.4% Acidulated Phosphate Fluoride (APF) solution for 20 minutes before attempting replantation [1]. As per the International Association of Dental Traumatology (IADT) 2007, protocol for replantation of an avulsed teeth after an extraoral dry time of over 60 minutes included immersing the tooth in a 2% sodium fluoride [NaF] solution for 20 minutes [2]. In IADT 2012 guidelines [3] and the recommended guidelines of the American Association of Endodontists for the treatment of Traumatic Dental Injuries 2013 [15], it was stated that surface treatment should be done with 2% NaF solution for 20 minutes but this procedure was just suggested and was not an absolute recommendation.

Fluoride was recommended for surface treatment as it hardens the tooth structure by converting hydroxyapatite into fluorapatite and helps to prevent or delay resorption. The use of 2% acidulated sodium phosphate fluoride has shown a fall in the incidence of inflammatory resorption and an increase in replacement resorption [16]. It has been demonstrated that treatment with alkaline substances, followed by acidic solutions of fluoride provides better results [17]. Various other agents such as dexamethasone, triple antibiotic paste, sodium fluoride, stannous fluoride, tetracycline, minocycline, enamel matrix derivatives fibroblast growth factor (bFGF or FGF-2), etc. have been recommended for surface treatment [18-23].

In this systematic review, all five articles [8-12] used fluoride products for surface treatment. Harris A et al., [8] soaked avulsed teeth in 2% acidulated fluoride solution for five minutes and Aggrawal V et al., [10] soaked avulsed teeth in 2.4% acidulated sodium fluoride solution (pH 5.5) for 20 minutes as per Andreasen’s recommendation [1]. Daga A et al., [12] soaked avulsed tooth in 2% acidulated sodium fluoride solution and later placed in doxycycline antibiotic. According to the authors, this was done because a decrease in the frequency of ankylosis and inflammatory root resorption has been reported after topical application of doxycycline [21]. Rahbar M and Hassani-Dehkharghani A [11] soaked avulsed tooth in the hydrofluoric acid and then in doxycycline solution for five minutes with no explanation or rationale mentioned in the article. Anand S et al., [9] used 2.4% acidulated sodium fluoride solution (pH 5.5) for 20 minutes and then immersed in the metronidazole solution for another 20 minutes. This was done with a rationale to minimise the bacterial load and prevent resorption.

The distribution of success varies largely in this systematic review. Out of five case reports, one case report did not describe any pathological change at the end of 24 months [8]. Three cases reports no complication after 12 months [10-12] and one article report mentioned ankylosis and infraocclusion (1 mm) after 12 weeks of replantation [9]. The development of inflammatory root resorption is related to damage of the periodontium at the time of trauma, the presence of bacteria within the root canal, the extent to which the viability of the periodontal ligament cells remaining on the root surface is maintained [22]. In adults, replacement resorption is usually seen within 1-3 years and in children, it is seen after 1-5 years. Inflammatory resorption and replacement resorption processes take time and usually are unpredictable, therefore long-term follow-up should be considered. Thus, any case of replantation should have a minimum follow-up of five years for the complication of replacement resorption to occur [23]. From this systematic review, we could conclude that the follow-up period of most of the case studies was not adequate for the complications to be evaluated properly.

This systematic review was based on case reports i.e. a form of observational study rather than randomised control trials. This systematic review merely analysed the different surface treatment methods used by the clinicians for delayed replantation of avulsed teeth and its effect on the prognosis of replanted teeth. Randomised controlled trials with a long follow-up period need to be carried out to establish a concrete relation between surface treatment and prognosis of delayed replantation of avulsed teeth.

In this systematic review, there was a lot of variation in the methodology performed, agents, and concentrations of the agents used for surface treatment by the clinician for replantation of teeth. Due to data heterogenicity, a clear idea regarding technique, agents, and concentration of agents for surface treatment could not be established. As a result of short follow-up period in all the articles, the relationship between surface treatment and success of replantation could not be concluded. However, it can be safely concluded that surface treatment of avulsed teeth prior to delayed replantation shows better results and predictable outcomes.