Study of the effectiveness of propolis extract as a storage medium for avulsed teeth Introduction Dental avulsion is a consequence of injury that results in the complete displacement of a tooth from its alveolar socket, and may affect multiple tissues, such as the periodontal ligament (PDL), alveolar bone, cementum, dental pulp, and gingival mucosa (1). The reported incidence of complete avulsion ranges from 1 to 16% of all traumatic injuries to the permanent dentition (2). Trauma to the anterior teeth is the most prevalent (3), with sports and automobile accidents the most frequent causes (4). The most frequently involved age group is 7–11 years old (4), with at higher prevalence in males (4, 5). When dental avulsion occurs, immediate replantation at the trauma site is the ideal procedure for maintaining the viability of PDL cells. However, immediate replan- tation is rarely achieved (6). The viability of PDL cells is dependent on the duration of extra-alveolar time, storage media of the tooth, and preservation of the root portion, all of which determine the prognosis for dental replan- tation (2, 5). Inflammatory resorption and replacement resorption subsequent to dental alveolar ankylosis are the most significant and common complications after replantation of avulsed teeth (7). In vivo and in vitro research suggests the use of different storage media to maintain PDL cell viability and improve the prognosis for tooth replantation. These storage media include milk, saliva, and some cell-culture media (5, 8–10). In vitro studies also suggest formulations based on propolis as promising alternative media for maintaining PDL cells (11–13). Propolis is a resinous substance derived from tree exsudates mixed with floral sap, salivary bee secretions, wax, and pollen. It is used by bees for thermally insulating, sealing, and protecting the hive against microorganisms (14, 15). Its complex chemical compo- sition is dependent on the plant source and local flora (16, 17). The compounds comprising propolis include volatile oils (5–10%), waxes (30–40%), resins, balsams, and pollen grains, which are rich sources of essential elements such as magnesium, nickel, calcium, iron, and zinc (18). Polyphenols have been identified as the main organic constituents of propolis, mainly represented by flavonoids and accompanied by phenolic acids, esters, phenolic aldehydes, and ketones (19). Dental studies have evaluated the biological activity of propolis, mainly with respect to the healing process (20), inhibition of dental plaque formation and Dental Traumatology 2010; 26: 323–331; doi: 10.1111/j.1600-9657.2010.00879.x Ó 2010 John Wiley & Sons A/S 323 Ana Regina Casaroto 1 , Mirian Marubayashi Hidalgo 2 , Ana Maria Sell 3 , Selma Lucy Franco 1 , Roberto Kenji Nakamura Cuman 1 , Eduardo Moreschi 4 , Fausto Rodrigo Victorino 5 , Va ˆ nia Antunes Steffens 6 , Ciomar Aparecida Bersani-Amado 1 1 Department of Pharmacy and Pharmacology, State University of Maringa ´; 2 Department of Dentistry, State University of Maringa ´; 3 Department of Clinical Analysis, State University of Maringa ´; 4 Department of Dentistry, University Center of Maringa ´; 5 Department of Endodontics, Bauru School of Dentistry, University of Sa ˜ o Paulo, Bauru, 6 Experimental Surgery and Biotery, State University of Maringa ´ , Maringa ´; Brazil Correspondence to: Prof. Dr Ciomar Aparecida Bersani-Amado, Universidade Estadual de Maringa ´ , Departamento de Farma ´ cia e Farmacologia, Av. Colombo, 5790, Zona 7, 87020–900 Maringa ´, PR, Brazil Tel: +55 44 3261 4923 e-mail: cabamado@uem.br Accepted 6 January 2010 Abstract – The purpose of the present study was to evaluate the efficacy of propolis extract in maintaining the viability of human periodontal ligament (PDL) cells, and to radiographically analyze tooth replantation and the adjacent periodontium in dogs after storage in this extract. Human PDL cells were incubated with the experimental media propolis, milk, saliva, Hank’s balanced salt solution (HBSS), and Dulbecco’s modified Eagles medium (DMEM, positive controls), and distilled water (negative control). Cell viability was determined 0, 1, 3, 6, 12, and 24 h later by colorimetric MTT assay. Thirty incisors from dogs were divided into two storage time blocks (1 and 3 h) and were maintained in the experimental media. HBSS served as a positive control, and dry teeth (on gauze) as a negative control. The replanted teeth were radiographed once per month for 6 months. The radiographic images were standardized by the shortening/lengthening factor, and were both qualitatively and quantitatively analyzed. The in vitro results showed that the efficacy of propolis in maintaining functional viability of PDL cells was similar to that of milk. Propolis and milk were significantly better than controls from the 6-h time period. The in vivo results showed that teeth maintained in propolis medium exhibited replacement resorption with significant reduction in tooth length, similar to teeth maintained in saliva and dried teeth. This resorption was less intense with the 3-h storage time than the 1-h storage time. Conditions close to normal were found in teeth maintained in milk, similar to the HBSS control. Therefore, although propolis was effective in maintaining the viability of human PDL cells, resorption of the tooth replantation in dogs occurred under these experimental conditions.