Comparison of coconut water, propolis, HBSS, and milk on PDL cell survival

Coconut water is biologically pure and sterile, with a rich presence of amino acids, proteins, vitamins, and minerals. The purpose of this study was to use a collagenase-dispase assay to investigate the potential of a new storage medium, coconut water, in comparison with propolis, Hank's balanced salt solution (HBSS), and milk in maintaining viable periodontal ligament (PDL) cells on simulated avulsed teeth. Seventy freshly extracted human teeth were divided into 4 experimental groups and 2 control groups. The positive and negative controls corresponded to 0-minute and 8-hour dry times, respectively. The experimental teeth were stored dry for 30 minutes and then immersed in 1 of the 4 media (coconut water, propolis, HBSS, and milk). The teeth were then treated with dispase grade II and collagenase for 30 minutes. The number of viable PDL cells was counted with a hemocytometer and analyzed. Statistical analysis showed that coconut water kept significantly more PDL cells viable compared with propolis, HBSS, or milk. Coconut water can be used as a superior transport medium for avulsed teeth.     

The influence of storage conditions on the clonogenic capacity of periodontal ligament cells: implications for tooth replantation

Viable periodontal ligament (PL) cells are required for PL healing of avulsed teeth following replantation. If immediate replantation cannot be accomplished, the ability of PL progenitor cells to reproduce (clonogenic capacity) and recolonize the wound may be extended by prevention of desiccation and storage in physiological media. This investigation examined the effects of storage in saliva, milk, Hank's balanced salt solution (HBSS) and Eagle's medium (αMEM) on the clonogenic capacity of human PL progenitor cells at 30 and 60 min extra-alveolar time. Twenty erupted human premolar teeth extracted as atraumatically as possible for orthodontic purposes were used in the present study. Fifteen premolars were placed immediately in freshly collected autologous saliva at room temperature, (+ 23°C) for 15 min. These 15 premolars were next divided into three groups of five and stored in either saliva, milk or HBSS at + 4°C in plastic cups surrounded by ice. The remaining five teeth served as positive controls and were immediately placed in αMEM at + 4°C. PL tissue was scraped from one-half of the root surface with a scalpel at 30 and 60 min total extra-alveolar duration. Cells were released from the tissue sample with a 30 min enzymatic digestion procedure and the cells from the tissue samples analyzed for clonogenic capacity. There was a reduction in clonogenic capacity with time for all protocols. Periodontal ligament cells stored in αMEM showed the least reduction between 30 and 60 min and the greatest reduction was observed for PL cells stored in saliva. The difference in clonogenic capacity following transfer from saliva to milk or HBSS was not significant at 30 min. At 60 min, cells transferred from saliva to HBSS had a statistically higher percentage of clonogenic cells than those transferred to milk (5.9% vs. 3.5%; P < 0.05). We conclude that immediate storage of avulsed teeth in autologous saliva, followed by transfer to chilled milk, preserves the presence of sufficient progenitor cells in the PL to warrant replantation and the possibility of PL healing at 60 min extra-alveolar duration.     

Effect of temperature and storage media on human periodontal ligament fibroblast viability

Abstract – Many solutions have been examined as possible storage media for avulsed teeth. The purpose of this study was to compare the effectiveness of several storage media to preserve cultured periodontal ligament fibroblasts (PDLF) under different temperatures. The media tested were: sterile Hank’s balanced salt solution (sHBSS), non‐sterile HBSS (nHBSS), skimmed milk, Save‐A‐Tooth^®, Minimum Essential Medium (MEM) and water (negative control). MEM at 37°C was used as positive control. PDLF were obtained from explants of extracted healthy human teeth. Plates containing confluent PDLF were soaked in the various media for 3, 6, 24, 48 and 72 h at 37°C and 20°C. After incubation, viability of the cells was determined using the tetrazolium salt‐based colorimetric (MTT) assay and the Trypan Blue exclusion test after 6, 24, 48 and 72 h of incubation at 20°C. The results were analyzed statistically using Kruskal–Wallis, Scheffé and Mann–Whitney (α = 5%) tests. Results from the MTT assay at 37°C and 20°C showed that skimmed milk was the best storage medium for up to 24 and 48 h, respectively, followed by nHBSS and sHBSS. Results from the Trypan Blue exclusion test showed that the best storage media were milk, sHBSS and nHBSS, with no statistical differences, for any time period. The Save‐A‐Tooth^® had a detrimental effect on cells after 24 h. The influence of temperature on the effectiveness of the storage media tested showed at 20°C a decreasing order of efficacy as follows: milk > sHBSS and nHBSS > MEM > Save‐A‐Tooth^® > water while at 37°C it was: MEM > nHBSS > milk > sHBSS > Save‐A‐Tooth^® > water. In conclusion, incubation temperature altered the effectiveness of the storage media and skimmed milk at 20°C was better than HBSS in maintaining PDLF viability.     

Assessment of post-traumatic PDL cells viability by a novel collagenase assay

Abstract – Both length of extra-alveolar time and type of storage media are significant factors that can affect the long-term prognosis for replanted teeth. Numerous studies have examined various media in an attempt to determine the ideal material for storage of the avulsed tooth. The purpose of this study was to compare the number of viable periodontium ligament (PDL) cells in different storage media using a collagenase assay. Thirty-three freshly extracted human teeth were divided into four experimental and two control groups. The positive and negative controls corresponded to 0 min and an 8-h dry time, respectively. The experimental teeth were stored dry for 30 min and then immersed in one of four media (Hank's balanced salt solution (HBSS), milk, saline, water) for 45 min. The teeth were then treated with dispase grade II and collagenase for 30 min. The number of viable and nonviable PDL cells was counted with a hemocytometer and analyzed. An anova demonstrated no statistically significant differences in the viability of PDL cells among saline, HBSS and milk. Within the parameters of this study, it appears that milk or saline is an equally viable alternative to HBSS for storage of avulsed teeth.     

Survival of human periodontal ligament cells in media proposed for transport of avulsed teeth

Abstract –  Many solutions have been examined as possible storage media for avulsed teeth. In this report, human periodontal ligament (PDL) cells were exposed for 1 h to culture medium, milk, Hanks Balanced Salt Solution (HBSS), Soft Wear, Opti Free, and Solo Care contact lens solutions, Gatorade^®, and tap water, at room temperature and on ice. The number of viable cells was counted using the trypan blue exclusion technique, immediately after exposure (0 h) and at 24 and 48 h, to test the proliferative capacity of the cells after treatment. The results indicated that a significantly higher number of cells survived and proliferated when the exposures were performed at 0°C. Water had a detrimental effect on the cells, whereas culture medium and HBSS preserved significantly more viable cells than the other experimental solutions. Within the parameters of this study, it appears that HBSS is the optimal storage medium for avulsed teeth. Low-fat milk could serve as an alternative if ice is available. Contact lens solutions or Gatorade^® on ice could serve as short-term (1 h) storage media if the other solutions are not readily available.     

A quantitative analysis of Propolis: a promising new storage media following avulsion

Abstract –  Both length of extra-alveolar time and type of storage media are significant factors that can affect the long-term prognosis of replanted teeth. Numerous studies have examined various media in an attempt to determine the ideal material for storage of the avulsed tooth. The purpose of this study was to use a Collagenase–Dispase assay to investigate the potential of a new storage media, Propolis, in maintaining viable periodontal ligament (PDL) cells on simulated avulsed teeth. Seventy freshly extracted human teeth were divided into five experimental groups and two control groups. The positive and negative controls corresponded to 0-min and an 8-h dry time, respectively. The experimental teeth were stored dry for 30 min and then immersed in one of the five media (Hank's balanced salt solution (HBSS), milk, saline, Propolis 50%, and Propolis 100% for 45 min). The teeth were then treated with dispase grade II and collagenase for 30 min. The number of viable PDL cells were counted with a hemocytometer and analyzed. Statistical analysis demonstrated that both Propolis groups kept significantly more PDL cells viable compared to either milk, saline, or HBSS. Within the parameters of this study, it appears that Propolis may be a better alternative to HBSS, milk, or saline in terms of maintaining PDL cell viability after avulsion and storage.     

不同离体时间和保存液对犬离体牙牙周膜细胞活力影响的实验研究

目的:探讨完全脱位牙不同离体时间和保存液对牙周膜细胞活力的影响。方法:麻醉拔除犬牙35个,首先将20个牙随机分为5组,分别为室温干燥放置0、30、60、120、240 min组,另15个牙室温干燥放置30 min后,随机分为3组,分别放入牛奶、HBSS液,100 g/L蜂胶液中浸泡2 h。各组处理完成后,采用全牙消化法获得牙周膜细胞,并通过4 g/L台盼蓝染色法检测各组牙周膜活细胞数和存活率。结果:室温干燥放置30、60、120、240 min后,牙周膜细胞存活率依次为33.6%、23.6%、18.5%、0.8%,而0 min的牙周膜细胞存活率可达95.5%。拔后30 min,经牛奶、HBSS液和100 g/L蜂胶液中保存2 h后,牙周膜细胞均有活力,其细胞存活率大小依次为100 g/L蜂胶液、HBSS液和牛奶,其中100 g/L蜂胶液与HBSS液相比无统计学差异(P>0.05),但与牛奶组相比,均有统计学差异(P<0.05)。结论:随着离体时间延长,完全脱位牙根面牙周膜细胞活力明显下降。100 g/L蜂胶液和HBSS液保存犬牙牙周膜细胞活力优于牛奶液。     

Viability of fibroblasts in a novel probiotic storage media

Abstract – A number of storage media have been investigated as to their ability to maintain the viability of the periodontal ligament (PDL) cells and thus to permit longer extra‐alveolar periods prior to replantation of avulsed teeth. The aim of the present in vitro study was to evaluate the number of viable PDL cells of avulsed teeth treated by Hank’s Balanced Salt Solutions (HBSS), saline, a novel probiotic solution and milk. Thirty‐six freshly extracted single‐rooted human teeth with closed apices were divided into one of the four experimental groups and two control groups (N = 6 each). The positive and negative controls corresponded to 0 min and an 8‐h dry time respectively. Following extraction, the coronal 3 mm of PDL tissue was scraped with a #15 scalpel to remove cells that might have been damaged. The experimental teeth were dried for 30 min followed by a 45 min immersion in one of the four experimental media. Each experimental tooth, after drying and soaking, was incubated for 30 min with a 2.5 ml solution of 0.2 mg ml^?1 of collagenase CLS II and a 2.4 mg ml^?1 solution of dispase grade II in phosphate buffer saline (PBS). The cells were then labelled with 0.4% Trypan blue for determination of viability. The teeth stored in positive control demonstrated the highest number of viable PDL cells followed in rank order by HBSS, saline, Lactobacillus reuteri solution and milk. There was no significant difference in the number of viable PDL cells between HBSS, milk, L. reuteri solution and saline. Within the parameters of this study, it appears that probiotic may be able to maintain PDL cell viability as HBSS, milk, or saline.     

Which is the most recommended medium for the storage and transport of avulsed teeth? A systematic review

Background/Aims

A wide variety of materials has been researched for their use as potential storage media for avulsed teeth, but it is essential to recognize the medium most recommended for improvement of the prognosis of avulsed teeth. The aim of this systematic review was to identify the most recommended medium to store and transport avulsed teeth based on the survival of periodontal ligament (PDL) cells as determined by in vitro studies.

Methods

Only laboratory‐based experimental studies on PDL cells found on adult permanent teeth were included. Data were collected using PubMed, CINAHL plus (EBSCO host), and the Cochrane Library, along with Google Scholar and a hand search. The key terms employed were permutations of [avulsed permanent teeth* OR dental avulsion* OR knocked out teeth*] AND [storage media* OR transport media* OR biological transport* OR PDL cell viability* OR PDL cell survival*]. A customized data extraction pro forma was used to extract the data and to evaluate the quality and risk of bias.

Results

The initial search yielded 978 articles, but only 67 were selected. Milk was the most recommended individual medium followed by Hank's balanced salt solution. Among natural products other than milk, propolis and coconut water were most frequently recommended. Recommendations were based on maintenance of PDL cell viability followed by ease of availability, low cost, and long shelf life.

Conclusions

Natural products are more effective in maintaining the PDL cell viability compared to synthetic products. Some storage media recommendations were also based upon practical aspects. Although natural products other than milk have more recommendations as a group, milk is the most recommended storage medium individually, based not only on PDL cell viability, but also practical considerations.     

Comparison of soymilk, powdered milk, Hank's balanced salt solution and tap water on periodontal ligament cell survival

The purpose of this study was to evaluate the ability of soymilk, powdered milk, and Hank's balanced salt solution (HBSS) to maintain human periodontal ligament (PDL) cell viability in vitro. PDL cells were obtained from extracted healthy third molars and cultured in Dulbecco's modified Eagles medium (DMEM). The cultures were exposed for 1, 2, 4, and 8 h to experimental solutions (tap water served as negative control and DMEM as positive control) at 37°C. The viable cells were then counted using the trypan blue exclusion technique. Data were analyzed by using one-way anova, post hoc Scheffe and two-way anova test. Statistical analysis showed that HBSS, powdered baby formula, and soymilk maintain cell viability equally well in different periods of times. Tap water cannot keep cells viable as well as other solutions. Soymilk and powdered baby formula can be recommended as suitable storage media for avulsed teeth for up to 8 h.     

Use of soymilk as a storage medium for avulsed teeth

Abstract

Objective. Tooth avulsion is one of the most severe forms of dental trauma. In these cases, immediate reimplantation is ideal; however, it almost never happens. The purpose of this study was to evaluate the viability of cells stored in soymilk and compare with other several storage media. Materials and methods. The media tested were: long-shelf-life coconut water, long-shelf-life whole milk, long-shelf-life soymilk, Gatorade, egg white, and Hank's Balanced Salt Solution. Cells cultured in DMEM and distilled water served as positive and negative controls, respectively. Plates containing confluent 3T3 fibroblast were soaked in the various media for 2, 12 and 24 h. After incubation at 37°C, viability of the cells was determined using the MTS assay. Data were analyzed by using one-way ANOVA and complemented by Tukey test with a significance level of 5%. Results. Statistical analysis showed that DMEM, whole milk, HBSS and soymilk were the most effective media for maintaining cell viability at all tested times (p < 0.05), followed by coconut water, egg white and Gatorade. The least amount of viable cells was observed in the distilled water group. Conclusions. The present study shows that the efficacy of soymilk in maintaining the viability of 3T3 fibroblasts is similar to that of HBSS and milk. Therefore, it can be concluded that soymilk could be a suitable alternative storage medium for avulsed teeth.     

Effect of HBSS storage time on human periodontal ligament fibroblast viability

Abstract – Hank’s balanced salt solution (HBSS) is recommended for the storage of avulsed teeth. The objective of this study was to evaluate if the HBSS storage time influences its ability to maintain the viability of human periodontal ligament fibroblasts (PDLF) by the analysis of cell metabolic function using MTT assay. PDLF were kept at 20°C for 3, 6, 24, 48, 72, 96 and 120 h in recently prepared HBSS (HBSS), HBSS stored for 6 months (HBSS 6 M), HBSS stored for 12 months (HBSS 12 M), and in Save‐A‐Tooth system’s HBSS (Save). Minimum essential medium (MEM) at 37°C and tap water at 20°C served as positive and negative controls, respectively. Cell viability was determined by the tetrazolium salt‐based colorimetric (MTT) assay. Data were statistically analyzed by the Kruskal–Wallis and Scheffé tests (α = 5%). Starting with the 6 h time‐point, HBSS was significantly more effective than HBSS 6 M, HBSS 12 M and Save in maintaining cell viability. HBSS 6 M effectiveness was similar to that of HBSS 12 M for up to 48 h, becoming higher at 72 h. In conclusion, the storage time of HBSS had a negative influence on its ability to maintain PDLF viability.     

Transport media for avulsed teeth: A review

Management protocols for avulsed teeth should include management of the pulp and periodontal ligament (PDL) cells in order to improve the long‐term prognosis and survival of these teeth. The use of an inappropriate transport or storage medium potentially increases the risk of PDL cell necrosis, which can result in ankylosis and replacement resorption of the tooth root. Considering the critical role of these media, an informed choice of a suitable medium is essential for a favourable outcome. The literature regarding transport media for avulsed teeth was reviewed using PubMed/MEDLINE up to February 2010. This review outlines the common storage media that are available and highlights their specific features or problems. Although HBSS, ViaSpan and Eagle's medium have great potential to maintain the PDL cells in a viable state after avulsion, the practicalities of using these solutions, the costs and the lack of ready availability to the general public make them less than ideal. Milk remains the most convenient, cheapest and readily available solution in most situations while also being capable of keeping PDL cells alive. Hence, milk remains the storage medium of choice for avulsed teeth that cannot be replanted immediately or very soon after the avulsion.     

Comparative evaluation of periodontal ligament fibroblasts stored in different types of milk: effects on viability and biosynthesis of collagen

Milk remains one of the most frequently recommended solutions for storage of avulsed teeth because it can maintain cell viability and is easily accessible. However, some negative effects of milk on avulsed teeth have been reported, just as the effects of milk on the long‐term functions of cells are not clear. This study aimed to evaluate the effects of different types of milk on the viability, proliferation, and functions of periodontal ligament fibroblasts (PDLF)s in vitro. Human PDLFs were culture‐medium depleted for 5 min and stored in Hanks’ balanced salt solution (HBSS), whole cow's milk, low‐fat cow's milk, or almond milk for 1 h at 25°C. Cell viability and proliferation were assessed using MTT assays. Expression of the genes encoding type I collagen and its modifying enzymes were analyzed using real‐time PCR. Collagen matrix production was evaluated using Picrosirius red polarization. Our results showed the overall efficiency of low‐fat cow's milk in maintaining the viability and proliferation of PDLFs, and in enhancing the process of collagen production. Almond milk storage resulted in the highest rate of PDLF proliferation, and comparable collagen biosynthesis ability to the control. Therefore, besides low‐fat cow's milk, almond milk may potentially be an alternative tooth‐storage medium for PDLF preservation and PDL tissue regeneration.     

Storage media enhance osteoclastogenic potential of human periodontal ligament cells via RANKL‐independent signaling

Abstract – Background: Hank’s balanced salt solution (HBSS) and milk have gained wide acceptance as storage media for avulsed tooth. However, the effect of the media and storage time on the periodontal ligament (PDL) cells involvement in the development of root resorption is still unclear. The purpose of this study was to evaluate whether precultured PDL cells in HBSS, milk, or modified Eagle’s medium alpha (α‐MEM) would affect osteoclastogenesis. Materials and methods: PDL cells were precultured in HBSS, milk, or α‐MEM for 1 h or 6 h before being co‐cultured with RAW 264.7 cells for an additional 3 days for mRNA analysis and 11 days for osteoclastogenesis assay. Results: Cyclooxygenase‐2 (COX‐2) mRNA was detected immediately in PDL cells precultured in the three storage media. The expression was up‐regulated markedly in all co‐cultures when compared with RAW cells alone. As a result of the co‐culture, interleukin‐1β (IL‐1β) expression was detectable in both PDL and RAW cells. TRAP+ multinucleated, osteoclast‐like cells developed in all co‐cultures; the number of TRAP+ cells was highest (P < 0.05) in the co‐cultures that PDL cells precultured in milk for 6 h. The mRNA level of receptor activator of nuclear factor‐kappa B ligand (RANKL) was not detected in PDL cells. Osteoprotegerin (OPG) mRNA expression reduced with increased preculture time, but the difference was not significant (P > 0.05). Conclusions: PDL cells kept in the three storage media led to TRAP+ multinucleated, osteoclast‐like cells formation via RANKL‐independent signaling. The ability to induce osteoclastogenesis may be considered as one of the factors to evaluate the ability of storage medium to maintain PDL viability after tooth avulsion.     

Effect of soaking in Hank's balanced salt solution or milk on PDL cell viability of dry stored human teeth

Abstract— This study was designed to evaluate the effect of soaking in either Hank's balanced salt solution (HBSS) or milk on peri⁻odontal ligament (PDL) cell viability in avulsed teeth. Dry storage times of 30, 60, and 90 min were evaluated. PDL cell viability was determined after removal of the cells from the root surfaces of extracted teeth using a modification of the procedure described by Nakashima (Arch Oral Biol 1991;36:655–63). After trypsinization and subsequent treatment in collagenase, the cells were stained with trypan blue, and viable and non-viable cells were counted using a hemocytometer and converted to percentages for statistical comparison. The results of this study demonstrated no significant difference in the number of viable cells with or without soaking in HBSS or milk at any of the dry storage times. In addition, there was no significant difference in PDL cell viability between the 30-and the 60-min dry periods. Although the soaking procedure had no obvious negative consequence, no simcant improvement in PDL cell viability by the addition of this step was demonstrated under the conditions of this study.     

The use of green tea extract as a storage medium for the avulsed tooth

Introduction

Green tea extract (GTE) has been reported to have remarkable anti-inflammatory, antioxidant, and anticarcinogenic effects and to prolong allograft survivals. The purpose of the present study is to investigate in vitro the efficacy of GTE as a storage medium for avulsed teeth. We estimated the possibility for storage medium by maintaining the viability of human periodontal ligament (PDL) cells.

Methods

Human PDL cells were cultured and stored in the following media: (1) Hank’s balanced salt solution (HBSS), (2) tap water, (3) milk, (4) GTE, and (5) commercial green tea. After 1, 3, 6, 12, and 24 hours, cells in different media were examined under the optical microscope, and their viabilities were analyzed by using a nucleocounter and 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium assay. The data were statistically analyzed by analysis of variance tests with post analysis using the Duncan method (P < .05).

Results

The result indicates that there was no difference in cell viability between GTE and HBSS media, whereas GTE showed higher cell viability than other media (P < .05).

Conclusions

Our study shows that the efficacy of GTE in maintaining the viability of human PDL cells is similar to that of HBSS and higher than that of milk. Therefore, we conclude that GTE could be a suitable, alternative storage medium for avulsed teeth.     

(-)-Epigallocatechin-3-gallate: a novel storage medium for avulsed teeth

The purpose of the present study was to evaluate the efficacy of (-)-epigallocatechin-3-gallate (EGCG) in maintaining the vitality of human periodontal ligament (PDL) cells when used as a storage medium for avulsed teeth prior to replantation. Thirty freshly extracted single-rooted human teeth with closed apices were randomly assigned to three experimental groups with 10 samples per group and immersed in one of the storage media: EGCG, Hank's balanced salt solution (HBSS), or milk for 2 h. The PDL cells were dissociated by an enzyme treatment with collagenase and trypsin. The cells were then labeled with 0.4% Trypan blue for the determination of viability. The result showed that EGCG group had the highest percentage of cell viability, followed by HBSS and milk group, in descending order.     

Effect of milk renewal on human periodontal ligament fibroblast viability in vitro

Abstract – Milk has been studied extensively and has gained wide acceptance as a suitable storage medium capable of maintenance of avulsed teeth that cannot be replanted immediately. The objective of this study was to evaluate whether the renewal of milk as a storage medium every 24 h for up to 120 h is able to increase its ability to maintain human periodontal ligament fibroblasts (PDLF) viability in vitro. Plates with confluent PDLF were soaked in minimum essential medium (MEM) at 37°C (positive control) and in skimmed milk (22 wells) and water (negative control) for 24, 48, 72, 96, and 120 h at 5 and 20°C. The skimmed milk was renewed every 24 h in 11 of the wells of each plate. After these periods, cell viability was determined by the tetrazolium salt‐based colorimetric (MTT) assay. Data were statistically analyzed by Kruskal–Wallis and Scheffé tests (α = 5%). At 24 h, milk and MEM performed similarly. However, from 48 h onwards, MEM was significantly better than renewed and not renewed milk at both temperatures. Regardless of temperature (5 or 20°C), renewal of milk with fresh milk did not affect its ability to maintain PDLF viability.     

Investigations On A Cell Culture Medium For Storage And Transportation Of Avulsed Teeth

Non-physiologic storage of avulsed teeth leads to a high incidence of root resorption, resulting in poor prognosis. This study investigated the suitability of specially composed cell culture media for storage of extracted teeth for up to 48 hours. Autoradiographic investigations revealed that the proliferative activity of periodontal ligament (PDL) cells of teeth stored in cell culture medium for up to 48 hours increased with storage time. Studies on proliferation of PDL cells after storage of teeth in different media for up to 24 hours demonstrated that the proliferative activity is dependent on the composition of the medium. Immunohistochemical investigations with markers for cell proliferation revealed that pulp cells of extracted immature teeth show numerous proliferations after storage for up to 24 hours in a special cell culture medium but few proliferations after storage in Hanks Balanced Salt Solution (HBSS). The investigations indicate that a special cell culture medium can preserve cell viability of PDL cells adhering to extracted teeth for at least 48 hours. The in vitro results are confirmed by a case presented: After storage of two upper central incisors for 36 hours in the cell culture medium the teeth could be successfully reimplanted after extraoral insertion of titanium posts into the root canal (auto-alloplastic reimplantation). Clinical and radiological follow-up examinations for 12 months revealed normal periodontal healing.