Storage of human periodontal ligament cells in a combination of different media

A new direction in managing avulsed teeth: stem cell-based de novo PDL regeneration

Management of avulsed teeth after replantation often leads to an unfavorable outcome. Damage to the thin and vulnerable periodontal ligament is the key reason for failure. Cell- or stem cell-based regenerative medicine has emerged in the past two decades as a promising clinical treatment modality to improve treatment outcomes. This concept has also been tested for the management of avulsed teeth in animal models. This review focuses on the discussion of limitation of current management protocols for avulsed teeth, cell-based therapy for periodontal ligament (PDL) regeneration in small and large animals, the challenges of de novo regeneration of PDL on denuded root in the edentulous region using a mini-swine model, and establishing a prospective new clinical protocol to manage avulsed teeth based on the current progress of cell-based PDL regeneration studies.

Fourteen Years After Delayed Replantation of an Avulsed Permanent Tooth: Clinical Features and Outcomes

This article reports a clinical case of a boy who underwent an avulsion of the upper right central incisor at 8 years old. The avulsed tooth was kept in the socket for 11 years after replantation. The clinical and radiographic findings after 14 years revealed a complete root resorption, but alveolar bone volume is adequate for future implantation from the recent tomography scans view, even in labial area where alveolar bone morphology is poor.

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.

An In vitro Comparison of Coconut Water, Milk, and Saline in Maintaining Periodontal Ligament Cell Viability

Background and Objectives:

Two of the most critical factors affecting the prognosis of an avulsed tooth after replantation are extraoral dry time and the storage media in which the tooth is placed before treatment is rendered. The present study is undertaken to evaluate the periodontal ligament (PDL) cell viability after storage of teeth in different storage media, namely, coconut water, milk, and saline.

Materials and Methods:

Forty sound human premolars undergoing extraction for orthodontic purpose were selected. The teeth were allowed to lie dry on sand/mud for 30 min followed by which they were randomly divided and stored in three different media, i.e., coconut water, milk, and saline. After 45-min storage in their respective media, the root surface was then scraped for PDL tissue.

Results:

The ANOVA and Newman–Keuls post hoc procedure for statistical analysis of viable cell count under a light microscope using hemocytometer demonstrated that coconut water preserved significantly more PDL cells viable (P < 0.05) compared with milk and saline.

Conclusion:

Storage media help in preserving the viability of PDL cells when immediate replantation is not possible. This study evaluated the posttraumatic PDL cells’ viability following storage in three different storage media. Within the parameters of this study, it was found that coconut water is the most effective media for maintaining the viability of PDL.

A Quantitative Analysis of a Probiotic Storage Media for Avulsed Teeth

AIM

The aim of the present in vitro study was to investigate the potential of a storage medium, probiotic yogurt (Bifidibacterium animalis DN 173010) in comparison with Hank's balanced salt solution (HBSS), saline and milk in maintaining viable periodontal ligament (PDL) cells on simulated avulsed teeth.

MATERIALS AND METHODS

Thirty-six freshly extracted single-rooted human teeth with closed apices were divided into six experimental groups (N=6). The teeth were extracted as atraumatically as possible and washed in sterile saline solution to eliminate residual blood. Following extractions, the coronal 3 mm of PDL tissues were scraped with a #15 scalpel to remove cells that may have been damaged. The positive and negative controls corresponded to 0 minutes and an 8-hour dry time, respectively. After extraction, the positive control teeth were immediately treated with dispase and collagenase. The negative control teeth were bench-dried for 8 h, with no follow-up storage solution time, and then placed in the dispase and collagenase. The number of viable protective least significant difference PDL cells were counted under a light microscope with a hemocytometer at 20× magnification and analyzed. Statistical analysis of the data was accomplished using Nonparametric ANOVA complemented by Kruskal-Wallis Test and Dunn's Multiple Comparisons Test.

RESULTS

Positive control was found to be significantly better than the others, there were statistically significant differences between positive control and other test groups (p=0.000). The teeth stored in positive control demonstrated the highest number of viable PDL cells followed in order by probiotic yogurt, HBSS, saline and milk.

CONCLUSION

Bifidibacterium animalis DN 173010 seems to be an alternative for the temporary storage of avulsed teeth, due to high number of viable PDL cells. Probiotics may be suitable transport media for avulsed teeth, but further research is warranted using the commercially available products.

Evaluation of coconut water neutralized by different agents on the viability of human fibroblasts: an in vitro study

Abstract Objective This study evaluated four types of pH adjustment of the coconut water (CW) on viability of human fibroblasts (HFF). Material and method Natural and industrialized CW were adjusted to pH 7.0 using: (1) Sodium Hidroxide (NaOH), (2) Sodium bicarbonate (NaHCO3), (3) Triethanolamine (C6H15NO3), (4) 2-Amino-2-Methil-1-Propanol (C4H11NO). Fibroblasts were plated at 2×104/ well in 96 well plates and maintained in the CW solutions for 2 h and 4 h. Positive control was represented by HFF maintained in DMEM and the negative control by tap water. Cell viability was analyzed by MTT formazan method. Data were analyzed by 3-way ANOVA followed by Tukey’s and Dunnet’s test. Result There are no significant effect on the cell viability regarding type of CW, period of evaluation, and the interactions between CW and period of evaluation, CW and pH adjustment method, pH adjustment method and period of evaluation (p>0.05). Conclusion The product used for CW pH adjustment did not influenced HFF viability, thought there are a tendency of better performance in natural CW.

Comparative in vitro study of the effectiveness of Green tea extract and common storage media on periodontal ligament fibroblast viability

Objective:

Green tea extract (GTE) was shown to be effective in preserving periodontal ligament fibroblasts (PDLFs) of avulsed teeth. This study aimed at determining the potential of GTE in preserving the viability of PDLFs comparing with different storage media.

Materials and Methods:

Periodontal ligament cells were obtained from freshly extracted healthy impacted third molars and cultured in Dulbecco's Modified Eagle Medium (DMEM). Cell viability was determined by storing the cells in seven media; DMEM, tap water, Hank's balanced salt solution (HBSS), whole milk, hypotonic sucrose solution, GTE, and GTE + sucrose for 1, 2, 4, and 24 h at 37°C using tetrazolium salt-based colorimetric (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) assay. Statistical analysis was performed by one-way analysis of variance and post hoc tests.

Results:

GTE showed significantly higher protective effect than HBSS at 2, 4, and 24 h (P = 0.009, P = 0.02, P = 0.016), DMED at 2 h (P = 0.003), and milk at 4 h (P = 0.039).

Conclusion:

Although with undesirable osmolality and pH, GTE had a good ability in preserving the PDLFs comparing with other studied media.

Knowledge about permanent tooth avulsion and its management among dentists in Riyadh, Saudi Arabia

Background

There is a lack of adequate information on dentists’ knowledge about tooth avulsion and its management in Saudi Arabia. The aim of this study was to evaluate the level of knowledge about permanent tooth avulsion and its management among dentists working in Riyadh, Saudi Arabia.

Methods

A total of 550 dentists were contacted to request their participation in this 19-item questionnaire survey over a three-month period starting in January 2015 using convenience sampling methodology. A questionnaire consisting of demographic items and multiple-choice questions regarding knowledge of avulsion and its management was used. The level of knowledge was assessed using a scoring system that assigned one point for each correct answer and zero points for wrong answers, with a maximum possible score of ten points. An independent t-test was used to compare the level of knowledge (mean score) based on particular variables, such as sex, nationality, type of practice, current employment, working hours and whether the respondents had attended a continuing dental education (CDE) programme on avulsion management. The level of significance was set at P< 0.05.

Results

A total of 470 completed questionnaires were collected with data suitable for statistical analysis. The majority of the respondents were Saudi (n = 331; 72.1 %) and general practitioners (n = 278; 59.3 %). Most of the participants correctly responded to the knowledge-based questions, except the questions regarding the best storage medium (milk: 24.1 %) and the duration of follow-up by clinical and radiographic examination (5 years: 15.6 %). The mean knowledge score was 5.94 ± 1.57. Gender (P = 0.001), current employment (P = 0.045) and working hours per day (P = 0.020) had a significant effect on the mean knowledge score.

Conclusions

The surveyed dentists were found to have a moderate knowledge of avulsion and its management, although a relative lack of knowledge was observed regarding the duration of follow-up after replantation.

Evaluation and comparison of efficacy of three different storage media, coconut water, propolis, and oral rehydration solution, in maintaining the viability of periodontal ligament cells

Background:

Two of the most critical factors affecting the prognosis of an avulsed tooth after replantation are extra oral dry time and the storage medium in which the tooth is placed before treatment is rendered. However, the ability of a storage/transport medium to support cell viability can be more important than the extra oral time to prevent ankylosis and replacement resorption.

Aim:

Purpose of this study was evaluation and comparison of efficacy of a new storage medium, oral rehydration solution (ORS) with coconut water, and propolis in maintaining the viability of periodontal ligament (PDL) cells by using a collagenase-dispase assay.

Materials and Methods:

40 teeth were selected with intact crown which were advised for Orthodontic extraction having healthy PDL. Teeth were then randomly divided into three experimental storage solution groups. Other 10 were divided into positive and negative control groups (5 each).

Statistical Analysis and Result:

The results were statistically analyzed with analysis of variance and multiple range by using post hoc tests. The results of the prevailing study indicated that coconut water group demonstrated a significantly higher number of viable PDL cells than propolis 50%, and ORS. There was no significant difference between coconut water and propolis 50% groups.

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.

Avulsion and storage media

Avulsion of a tooth caused by trauma, and its successful treatment is a challenging situation that a dentist encounters in clinical practice. There is a definitive treatment for the avulsed tooth, which depends on many factors. The immediate replacement and replantation of the avulsed tooth is necessary, but it cannot always be accomplished for a number of reasons. Thus, the tooth should be transported in a suitable medium to maintain the cell viability. The storage medium is one of the important factors that will help the dentist in rendering successful treatment for the avulsed tooth. There is a continuing search for an ideal storage medium. This review paper focuses on the various storage media, with special reference to coconut water.

Comparative evaluation of maintenance of cell viability of an experimental transport media "coconut water" with Hank's balanced salt solution and milk, for transportation of an avulsed tooth: An in vitro cell culture study

The purpose of this study was to evaluate the efficiency of a new storage medium, coconut water, in comparison with other traditional storage media like Hank's balanced salt solution (HBBS) and milk, in maintaining the viability of an established cell line BHK-21/C13 (baby hamster kidney fibroblasts) using the direct suspension cell culture technique.

The storage media tested in the study were divided into three major groups and two control groups - Group A: HBBS, Group B: milk, and Group C: coconut water. The positive and negative controls corresponded to 0-minute and 24-hour dry times respectively.

The three groups were then divided into five subgroups, each denoting the storage time periods 15 min, 30 min, 45 min, 60 min and 120 min respectively. The cell line BHK-21/C13 was subcultured and the number of cells was standardized by making a cell suspension using Minimal Essential Medium in five culture plates.

One ml of each experimental group (HBBS, milk and coconut water) was added to eight wells of each culture plate. The culture plates containing the cells and the experimental groups were incubated for the respective time periods. The cells were then counted with a Neubauer counting chamber, under light microscope. The results were statistically analyzed using One-way ANOVA and Multiple Range Test using the Tukey-HSD procedure to identify the significant groups at p ≤ 0.05.

Within the parameters of this study, it appears that coconut water may be a better alternative to HBSS or milk, in terms of maintaining cell viability. Coconut water can be used as a superior transport medium for avulsed teeth.

Tooth replantation after use of Euro-Collins solution or bovine milk as storage medium: a histomorphometric analysis in dogs

PURPOSE

Euro-Collins solution was developed for the preservation of organs for transplantation, whose characteristics have raised interest for its use as a storage medium for avulsed teeth before replantation. This study evaluated histologically and morphometrically the healing process of dog teeth replanted after storage in Euro-Collins solution or bovine milk.

MATERIALS AND METHODS

Eighty roots of 4 young adult mongrel dogs were randomly assigned to 4 groups (n = 20) and the root canals were instrumented and obturated with gutta-percha and a calcium hydroxide-based sealer. After 2 weeks, the teeth were extracted and subjected to the following protocols: GI (negative control), replantation immediately after extraction; GII (positive control), bench-drying for 2 hours before replantation; GIII and GIV, immersion in 10 mL of whole bovine milk and Euro-Collins solution at 4 degrees C, respectively, for 8 hours before replantation. The animals were sacrificed 90 days postoperatively. The pieces containing the replanted teeth were subjected to routine processing for histologic and histometric analyses under light microscopy and polarized light microscopy.

RESULTS

Root resorption was observed in all groups. GII exhibited the greatest loss of dental structure (P < .01), and inflammatory resorption was predominant in this group. Storage in milk showed poorer results than immediate replantation and storage in Euro-Collins solution (P < .01). The teeth stored in Euro-Collins solution presented similar extension of root resorption and periodontal ligament reorganization to those of immediately replanted teeth.

CONCLUSIONS

The findings of this study suggest that the Euro-Collins solution is an adequate storage medium for keeping avulsed teeth for up to 8 hours before replantation.

Effect of storage media on human periodontal ligament cell apoptosis

The ability of storage media to preserve periodontal ligament (PDL) cell vitality has been previously evaluated. However, the mechanisms by which different storage conditions alter the functional status of PDL cells have not been determined. The purpose of the present study was to investigate, in vitro, the level of programed cell death or apoptosis in a population of PDL cells following storage under different conditions. Primary human PDL cells were plated into 24-well-culture plates and allowed to attach for 24 h. Cells were then exposed for 1 h to milk, Hank's balanced salt solution (HBSS), Soft Wear contact lens solution or Gatorade at room temperature or on ice. Culture medium was used as a negative control. Apoptosis was evaluated at 24, 48, and 72 h after treatment on quadruplicate samples by using the ST 160 ApopTag Fluorescein Direct In Situ Detection Kit. The total number of cells and the total number of apoptotic cells were counted. The results indicated that at 24 and 72 h, PDL treated with Gatorade and the contact lens solution displayed the highest percentages of apoptotic cells when compared with the other treatment groups at room temperature. Overall, cells treated on ice showed significantly lower levels of apoptosis when compared with treatments at room temperature. In conclusion, the results indicated that apoptosis plays a major role in cell death in cells treated with Gatorade and contact lens solutions in comparison to other storage solutions and that storage on ice can inhibit programed cell death.

Treatment of root surface in delayed tooth replantation: a review of literature

The time elapsed between a trauma and tooth replantation usually ranges from 1 to 4 h. The chances of root surface damage are higher when tooth replantation is not performed immediately or if the avulsed tooth is not stored in an adequate medium. This invariably leads to necrosis of pulp tissue, periodontal ligament cells and cementum, thus increasing the possibility of root resorption, which is the main cause of loss of replanted teeth. This paper presents a comprehensive review of literature on root surface treatments performed in cases of delayed tooth replantation with necrotic cemental periodontal ligament. Journal articles retrieved from PubMed/MedLine, Bireme and Scielo databases were reviewed. It was observed that, when there are no periodontal ligament remnants and contamination is under control, replacement resorption and ankylosis are the best results and that, although these events will end up leading to tooth loss, this will happen slowly with no loss of the alveolar ridge height, which is important for future prosthesis planning.

Effect of propolis on survival of periodontal ligament cells: new storage media for avulsed teeth

Propolis is a multifunctional material used by bees in the construction and maintenance of their hives. Propolis possesses several biologic activities such as anti-inflammatory, antibacterial, antioxidant, antifungal, antiviral, and tissue regenerative, among others. The purpose of this study was to determine the ability of propolis to serve as a temporary storage medium for the maintenance of periodontal ligament (PDL) cell viability of avulsed teeth. PDL cells were obtained from healthy third molars and cultured in Dulbecco's Modified Eagles Medium (DMEM). Cultures were subjected to 10% propolis solution, 20% propolis solution, long-shelf life light milk with lower fat content (milk), Hank's Balanced Salt Solution, tap water as the negative control, and DMEM as the positive control. Tissue culture plates were incubated with experimental media at 37 degrees C for 1, 3, 6, 12, or 24 hours. PDL cell viability was assessed by trypan blue exclusion. Statistical analysis of the data was accomplished by using one-way analysis of variance complemented by the Tukey test. The level of significance was 5% (p<0.05). The results showed that 10% propolis was a more effective storage medium than other groups. In conclusion, propolis can be recommended as a suitable transport medium for avulsed teeth.

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

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 degrees 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.

Human periodontal ligament cell viability in milk and milk substitutes

The purpose of this study was to determine the efficacy of several milk substitutes compared to whole milk in maintaining the viability of human periodontal ligament (PDL) cells on avulsed teeth. PDL cells were obtained from freshly extracted, healthy third molars and cultured in Eagle's minimal essential media (EMEM). The cells were plated onto 24-well culture plates and allowed to attach for 24 h. EMEM was replaced with refrigerated whole milk (positive control), reconstituted powdered milk, evaporated milk, or one of two baby formulas (Similac or Enfamil). Tap water served as the negative control. Tissue culture plates were incubated with the experimental media at 37 degrees C for 1, 2, 4, or 8 h. Cell viability was determined by a cell proliferation assay (CellTiter 96 AQ Assay), with absorbance read at 450 nM. A two-way ANOVA (p < 0.001) indicated that at 1 h there was no difference in the effect on PDL cell viability between any of the materials and whole milk. At 2 h, Enfamil and Similac performed significantly better than whole milk, whereas evaporated milk performed worse. At 4 h, Enfamil performed better than whole milk, whereas all other milk substitutes performed worse. At 8 h, all substitutes performed worse than whole milk. These results suggest that Enfamil, which is supplied in powder form that does not require special storage and has a shelf life of 18 months, is a more effective storage medium for avulsed teeth than pasteurized milk for at least 4 h.

Determination of periodontal ligament cell viability in long shelf-life milk

The purpose of this study was to determine the ability of long shelf-life milk to serve as a temporary storage medium for the maintenance of periodontal ligament (PDL) cell viability on avulsed teeth. PDL cells were plated onto 24-well culture plates and allowed to attach for 24 h. Minimal Essential Medium was replaced with regular pasteurized milk (refrigerated milk), long shelf-life milk (Parmalat), or Save-A-Tooth. Tap water served as the negative control, and Minimal Essential Medium served as the positive control. The tissue culture plates were incubated at 37 degrees C for 1, 2, 4, or 8 h. Cell viability was determined using a cell proliferation assay (CellTiter 96 AQ Assay) and absorbance read at 490 nm. ANOVA indicated that all media performed significantly better than tap water at all time periods. At 8 h, PDL cell viability in regular pasteurized milk and long shelf-life milk were significantly greater than in Save-A-Tooth (p < or = 0.001). There was no significant difference between regular pasteurized milk and long shelf-life milk at any time period. These results suggest that long shelf-life milk, which has the advantage of not requiring refrigeration, is as effective a storage medium for avulsed teeth as regular pasteurized milk and more effective than Save-A-Tooth.

Determination of periodontal ligament cell viability in the oral rehydration fluid Gatorade and milks of varying fat content

The purpose of this study was twofold: 1) to determine if the oral rehydration fluid Gatorade could serve as a suitable temporary storage medium for maintenance of periodontal ligament (PDL) cell viability on avulsed teeth and 2) to determine if fat content is related to maintenance of cell viability when milk is used as the temporary storage medium. PDL cells were cultured from extracted human teeth then incubated over timed intervals from 15 to 210 min in the oral rehydration fluid Gatorade, milks of varying fat content, and saliva. Dulbeco's Modified Eagles Medium served as the positive control while tap water served as the negative control. Cell viability was determined using a colorimetric assay that used Cell Proliferation Reagent WST-1. Results using Gatorade yielded cell viability data similar to the negative control, tap water, indicating that this oral rehydration fluid was not suitable as a temporary storage medium for the avulsed tooth. However, the fat content of milk was found to have an effect on cell viability, suggesting that milks with lower fat content may be more appropriate for maintaining PDL cell viability than milks with higher fat content.

Effects of long-term exposure of human periodontal ligament cells to milk and other solutions

Periodontal ligament (PDL) cells cultured from healthy extracted human teeth were exposed to milk, Alcon Opti-Free contact lens solution, K-Mart contact lens solution, saline, and Hank's balanced salt solution. The appearance and rate of loss of the cells from the culture dishes were recorded over time at both room temperature (20 degrees C) and 4 degrees C. The results indicated that saline was superior to either of the contact lens solutions in its ability to maintain the vitality of the PDL cells. Milk at 4 degrees DC provided good short-term viability , but cells did not remain attached after 48 h. At 20 degrees C, however, milk resulted in a 24.4% retention of cells after 72 h. Hank's balanced salt solution was the best storage media, with 46.8% of sells remaining attached after 72 h of exposure. This study supports milk as a good short-term storage medium for maintaining the vitality of PDL cells in vitro.

Replantation of 400 avulsed permanent incisors. 4. Factors related to periodontal ligament healing

400 avulsed and replanted permanent teeth were examined for periodontal ligament (PDL) healing, using standardized radiographic and clinical examination procedures (i.e. percussion test and mobility test). The effect of various clinical factors was examined, such as age and sex of the patient, type of tooth replanted, presence of crown fracture or bone fracture, stage of root development (including apical diameter and length of the pulp), type and length of extra-alveolar storage, clinical contamination of the root surface, type of root surface cleansing procedure, type and length of splinting period and antibiotic therapy. Surface resorption was generally diagnosed after 12 months; while inflammatory resorption and replacement resorption (ankylosis) were usually observed after 1 month and 1-2 months respectively. Most resorptive processes were diagnosed within the first 2-3 years. However, although rarely, even after 5 and 10 years new resorptive processes could be diagnosed. A univariate statistical analysis of 272 teeth revealed 9 factors significantly related to PDL healing. A subsequent multivariate analysis revealed that the following 4 factors had the strongest impact upon PDL healing, in descending order of significance: Stage of root development; length of the dry extra-alveolar storage period; immediate replantation and length of the wet period (saliva or saline storage). Nonphysiological storage, such as homemade saline and sterilizing solutions (chloramine and alcohol) always led to root resorption. Storage in tap water for more than 20 minutes usually led to root resorption. The common denominator for all these factors related to PDL healing appears to be survival of the PDL cells along the root surface. Based on these findings, immediate replantation is recommended irrespective of stage of root development.

Tooth splinting: a review of the literature and consideration of the versatility of a wire-composite splint

The principles of tooth luxation splinting have been changed since the animal and human tests conducted in the early 1970s showed that masticatory stimulus promotes healing of luxated teeth and normally exerted occlusal forces are able to prevent and eliminate small resorption cavities on the root surface. It has also been shown that fixation of only one week is enough to achieve the clinical healing of repositioned teeth. Apart from esthetic and hygienic components, present-day demands on tooth fixation techniques also include ease of construction and removal and the use of devices which allow slight movement of the fixed teeth. This paper presents the history of tooth splinting, our present-day knowledge of the subject, and introduces various splinting techniques. The wide range of indications for a flexible wire-composite splint are analyzed more thoroughly.

Twelve-year follow-up of a replanted incisor

A case report with a 12-yr follow-up of a replanted maxillary incisor is presented. A maxillary incisor, #8, with incomplete root formation was replanted without splinting following a 2-h sojourn in salt water. The pulp responded positively to the electric pulp tester for 2 yr. There was no response to the electric pulp tester 5 yr postoperatively. Although there was some external root resorption, the root appeared to have reached normal length. Two parallel vertical radiolucent slits were present in a trabeculated substance in the site normally occupied by the pulp. This case illustrates an example of revascularization and pulp obliteration. Interestingly, at the 12-yr follow-up, the replanted tooth, as well as tooth 7, showed blunted apices that occurred following orthodontic tooth movement.

Mitoses and microorganisms in the periodontal membrane after storage in milk or saliva

Milk and saliva were tested in vitro as potential storage media for avulsed teeth. Developing monkey teeth were extracted and stored in milk or saliva for periods ranging from 1 to 6 h. The osmolality, pH, conductivity and number of viable bacteria in the media were determined after predetermined intervals during the storage periods. After the storage periods the teeth were either prepared for scanning electron microscopy or cultured for 24 h in Eagle's medium supplemented with 3H-thymidine. In the scanning electron microscope numerous adherent bacteria were seen covering the periodontal membrane after storage in saliva but none were found after storage in milk. The cultured teeth were sectioned and evaluated with autoradiography. Superficial parts of the periodontal membrane were rapidly injured by storage in saliva while the epithelial root sheath and the apical pulpal cells were affected at a later stage. Cells neighboring the cementoblasts incorporated 3H-thymidine after 6 h storage in milk but not after storage in saliva for the same length of time. It was concluded that the low osmolality in combination with bacteria which adhered to the periodontal membrane made saliva less suited than milk for long time storage of avulsed teeth. Furthermore, a viable layer of cells close to the root surface seemed to be a prerequisite for a successful healing without root resorption after replantation.

Storage of experimentally avulsed teeth in milk prior to replantation

Extracted monkey teeth were endodontically treated, stored in milk or saliva for two or six h, and then replanted. Periodontal conditions were evaluated after eight wk. Teeth that had been stored for two or six h in milk or for two h in saliva showed periodontal healing almost as good as that of immediately replanted teeth. Teeth that had been kept in saliva for six h or bench-dried for one h showed extensive replacement resorption. Milk may thus be recommended as a storage medium for ex-articulated teeth prior to replantation in cases when immediate replantation is not possible.

Influence of osmolality and composition of some storage media on human periodontal ligament cells

The effect of media with different osmolalities and compositions on cell viability and integrity of the cell membrane has been studied. Physiologic media, such as milk, saline and physiologic sucrose solution, preserved cell viability and membrane morphology equally well. The cell membrane of cells stored in saliva was more extensively damaged than the cell membrane of cells stored in a sucrose solution with an hypotonic osmolality similar to saliva. Thus a hypotonic osmolality seemed to potentiate the damaging effect of an unfavourable composition or a bacterial contamination of the storage media.