Periodontal healing of extracted dogs' teeth air-dried for extended periods and soaked in various media

Periodontal ligament repair after active splinting of replanted dogs' teeth

BACKGROUND/AIM

The high rate of root resorption resulting from tooth replantation represents a serious clinical problem. In order to prevent ankylosis and replacement resorption, the contemporary literature highlights the importance of using a flexible stabilization for traumatized teeth. For this purpose, orthodontic devices may be promising for obtaining a better prognosis and periodontal repair. The aim of this study was to evaluate the effect of an active splinting protocol with controlled force in dog's teeth following replantation.

MATERIAL AND METHODS

Sixty premolar roots from three dogs were used. They were submitted to endodontic treatment, hemisected, atraumatically extracted and subsequently replanted. They were divided into four groups: Passive Stabilization (n = 20)-after 20 min in a dry medium; Active Stabilization (n = 20)-after 20 min in a dry medium; Negative control (n = 10)-immediate replantation and passive Stabilization; and Positive control (n = 10)-90 min of extra-alveolar time and passive Stabilization. The samples were collected and submitted to histologic processing. They were then evaluated for the count of inflammatory cells, expression of neurotrophin 4, osteoclasts, apoptotic cells and collagen fibres. The results were submitted to ANOVA or Kruskal-Wallis statistical tests followed by Tukey or Dunn post-tests (α = 5%).

RESULTS

Passive Stabilization with orthodontic brackets without traction used after replantation had the highest number of inflammatory cells (p = .0122), osteoclasts (p = .0013) and percentage of collagen fibres in the periodontal ligament (p < .0001) when compared to Active Stabilization with orthodontic brackets applying amild tensile force. Neurotrophin 4 had no statistically significant difference (p = .05), regardless of the treatment. The apoptotic cells count revealed statistical differences (p < .0001) between Active Stabilization (189.70 ± 47.99) and Positive Control (198.90 ± 88.92) when compared to Passive Stabilization (21.19 ± 32.94).

CONCLUSION

The active splinting protocol using orthodontic appliances generating a light and controlled force favoured periodontal ligament repair of replanted teeth.

The effects of three modified Hank's balanced salt solutions on root resorption of late replanted teeth: A pilot study

PURPOSE

The purpose of this study was to evaluate the effects of replanted rats' teeth that had been soaked in one of three modified Hank's balanced salt solutions (HBSSs) before replantation and after extended extra-oral dry time.

MATERIALS AND METHODS

Maxillary right incisors were extracted from 55 Wistar rats and kept dry for 30 or 60 min (n = 5 each). Afterwards, the pulp was extirpated and both the papilla and enamel organ were removed with a scalpel. Each group of teeth was soaked in one of three modified HBSSs or HBSS alone. After 30 min of immersion in solutions, the root canals were dried and filled with calcium hydroxide paste, and the teeth were replanted. After 8 weeks, animals were euthanized; then, specimens were processed as 5 μm-thick serial sections for histological examination and morphometric assessments.

RESULTS

The percentages of root resorption for the groups were found to be in the following order: HBSS3 (the bFGF group) > the HBSS only group > HBSS2 (the GSH group) > no soaking (the positive control group) > HBSS1 (the ALN group) for 30 min and the positive control group > the HBSS only group > HBSS2 > HBSS3 > HBSS1 for 60 min. The lowest incidence of resorption was observed in immediately replanted teeth (negative control).

CONCLUSIONS

The findings of this study suggest that soaking for 30 min in HBSS containing 1 mM alendronate can significantly inhibit root resorption for avulsed teeth that have been dried for 60 min.

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.

Eye injuries and orofacial traumas in floorball--a survey in Switzerland and Sweden

The objective of this study was to investigate the occurrence of eye injuries and orofacial traumas in floorball. In addition, the athletes' habits of wearing protective goggles and mouthguards was surveyed, and an assessment was made of the general level of knowledge amongst athletes and coaches about preventive and first aid measures after a dental trauma and the resulting consequences. The study was conducted by the same interviewer in Switzerland and Sweden during the 2009/2010 season using a standardized questionnaire. A total of 608 individuals (565 athletes and 43 coaches) belonging to the amateur and semi-professional leagues in the two countries were individually interviewed. Although 72.7% of all athletes had observed and 27.7% of field players had sustained an injury to the eye or its vicinity, only 25 athletes (4.9%) wore protective eyewear. Similarly, despite 31.7% of all players having observed a dental or jaw injury and 11.3% of interviewed field players having suffered one, only one athlete wore a mouthguard on a regular basis. Participants from Switzerland were significantly better informed than participants from Sweden with regard to first aid measures. The results of this study show that floorball has an equally high risk for dental trauma as handball. Further investigations of dental injuries in floorball would be valuable in order to provide players, coaches, parents and sporting federations with the necessary information to make decisions regarding the use of mouthguards. It is strongly recommended that protective eyewear should be made mandatory.

Evaluation of the knowledge of tooth avulsion of school professionals from Adamantina, São Paulo, Brazil

Tooth avulsion is common in children, and emergency management in these cases is critical. This management can be made, not only by a dentist but by people who are present where the accident occurs. Consequently, knowledge of tooth avulsion is fundamental for school professionals working with children. The purpose of the present study was to evaluate the knowledge of tooth avulsion of school professionals from Adamantina, São Paulo, Brazil. For that purpose a questionnaire, including questions regarding emergency procedures for tooth avulsion, was answered by 117 teachers. The results demonstrated that 75.2% of school professionals knew the importance of emergency management and 60.6% would look for a dentist for treatment of the cases; 18.8% would reimplant the tooth and 7.6% would keep it in milk. This study showed the lack of knowledge of teachers on tooth avulsion; educational campaigns are necessary to improve the emergency management of tooth avulsion.

Histological evaluation of a replanted tooth retained for 49 years

A maxillary incisor that had been replanted immediately after avulsion 49 years previously was evaluated histologically after extraction. The histological evaluation revealed resorption of the apical root surface, depositions in cement with different phases and mineral density, and histological changes in the periodontal ligament.

Evaluation of the topical effect of alendronate on the root surface of extracted and replanted teeth. Microscopic analysis on rats' teeth

The treatment of choice for tooth avulsion is replantation. The ideal replantation should be realized as quickly as possible, or at least, the avulsed tooth should be kept in an adequate solution to preserve the periodontal ligament attached to the root. If that is not possible, treatment of the radicular surface should be done in order to prevent radicular resorption. The purpose of this study was to test sodium alendronate as a substance for topical treatment of the radicular surface of avulsed teeth in an attempt to prevent the occurrence of dental resorptions. Fifty-four rat maxillary right central incisors were extracted and replanted. Group I--extra-alveolar dry period of 15 min, intracanal dressing with calcium hydroxide (CALEN, S.S. White, Artigos Dentários LTDA, Rio de Janeiro, Brazil) and replantation; Groups II and III - extra-alveolar dry periods of 30 and 60 min, respectively, immersion in 1% sodium hypochlorite for 30 min for removal of the periodontal ligament, washing in saline solution for 5 min, and treatment of the radicular surface with 3.2 mg/l sodium alendronate solution for 10 min. Intracanal dressing with calcium hydroxide and replantation followed. At 15, 60, and 90 days post-reimplantation, the animals were killed and the samples obtained and processed for microscopic analysis. The results indicated that sodium alendronate was able to reduce the incidence of radicular resorption, but not of dental ankylosis. No significant differences were observed regarding variations in the extra-alveolar periods among the groups.

Replantation of 45 avulsed permanent teeth: a 1-year follow-up study

Thirty-four patients with 45 avulsed and replanted permanent teeth were followed for 1 year. All teeth were soaked in tetracycline before replantation. In addition, enamel matrix derivative was used in teeth with dry storage times exceeding 30 min. Splinting was carried out with a non-rigid titanium splint and was limited to 7-10 days. Within that period, root canal treatment was begun in all teeth with a closed apex, whereas teeth with an open apex and ideal post-traumatic storage were not instrumented. All patients were given tetracycline systematically for 10 days. The survival rate of replanted avulsed permanent teeth was 95.6% at the 1-year follow-up. In 82.2%, root canal treatment was performed. Pulp survival was never observed, but three teeth had pulp canal obliteration. Normal periodontal healing was observed in 57.7% of teeth; 42.3% of teeth showed external root resorption (28.9% replacement resorption, 6.7% infection-related resorption, 6.7% surface resorption). The occurrence of replacement resorption correlated with the period of extraoral dry storage. Compared with other clinical studies on avulsed and replanted teeth, the present study reports a higher percentage of periodontal healing. The favorable treatment outcome may be associated with a strict protocol to enforce endodontic treatment, the use of topical and systemic tetracycline, and the relatively high number of ideally stored teeth following avulsion. In contrast, the present study has a follow-up period limited to 1 year.

Results after replantation of avulsed permanent teeth. II. Periodontal healing and the role of physiologic storage and antiresorptive-regenerative therapy

The status of the periodontal ligament (PDL) and of the pulp are decisive for the healing of avulsed and replanted teeth. A tooth rescue box was developed and distributed to offer optimal storage conditions for avulsed teeth. The therapy comprised extraoral endodontic treatment and applications of medicaments to enhance periodontal healing. In this long-term clinical study the healing results following avulsion and replantation were investigated. Twenty-eight permanent teeth in 24 patients were evaluated. The extraoral storage media and periods varied considerably. Soon after avulsion six teeth were stored in a cell culture medium (tooth rescue box Dentosafe) for 1-53 h; the PDL was defined as not compromised. Sixteen teeth were stored in a non-physiologic situation temporarily, the PDL was considered as compromised. Six teeth were stored in non-physiologic conditions for longer periods; the condition of the PDL was defined as hopeless. On 14 teeth antiresorptive-regenerative therapy (ART) with the local application of glucocorticoids and enamel matrix derivative and the systemic administration of doxycyclin was used. In all teeth extraoral endodontic treatment by retrograde insertion of posts was performed. The mean observation period was 31.2 months (+/-24.1; 5.1-100.2; median: 23.8). All six teeth rescued physiologically healed with a functional PDL (functional healing, FH) irrespective of the storage period. Of eight teeth with a compromised PDL on which ART was used, three teeth healed with a functional PDL. All other teeth showed replacement resorption, in three teeth additionally infection-related resorption was recorded. The predominant influence on the healing results was the immediate physiologic rescue of avulsed teeth (chi-square, P = 0.0001). The use of ART seemed to support FH (chi-square, P = 0.0547) in teeth with a compromised PDL. No other factors (maturity of roots, crown fractures, gender, age, antibiotics) were related to healing. In a linear regression analysis physiologic storage (P = 0.0013) and ART (P = 0.0421) were related to FH. For a good prognosis avulsed teeth should be stored immediately in a cell-compatible medium. Therefore the tooth rescue box should be distributed at places with higher risks of accidents, in families with children and in emergency facilities. The use of ART might have potential for enhancing the prognosis of teeth with a PDL that is compromised but not in a hopeless condition. Extraoral endodontic treatment reduces infection-related complications; this item was discussed in the first part of the publication.

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.

Root resorption in dental trauma: 45 cases followed for 5 years

We aimed to: (i) study the prevalence of root resorption after luxation or avulsion injuries on permanent teeth referred to our dental clinic over a 3-year period; (ii) study the relationship between type of injury and resultant type of resorption complication; and (iii) evaluate success of treatment protocols for various resorption complications. We observed 1943 patients with dental trauma, aged between 2 and 26 years, referred to the Accident and Emergency Department of the Dental Clinic, University of Brescia, from 1st September 1997 to 31st December 2001. Of these, 261 permanent teeth had sustained luxation (n = 188) or avulsion (n = 73) injuries. Permanent teeth luxation and avulsion injuries occurred most often in upper incisors (75%) of patients mostly aged 12-21 years, with males more commonly affected than females (68.3% vs. 31.7%). These cases were followed for 5 years, and complications and response to treatment were recorded. Root resorption was observed in 45 (17.24%) of these cases. Of the 45 cases with resorption, 9 were associated with luxation injury (20%) while 36 (80%) with avulsion. We distinguished 30 cases of inflammatory root resorption (18 transient and 12 progressive) and 15 cases of ankylosis and osseous replacement. When resorption was recognized, quick and effective treatment could still result in an excellent functional and aesthetic outcome for these teeth.

The effect of topical minocycline on replacement resorption of replanted monkeys' teeth

Tetracycline has been reported to possess antiresorptive properties in addition to antimicrobial actions. Systemic administration of tetracycline showed variable results in the control of replacement resorption after replantation with good results in half of the cases, and almost no healing in the rest. The purpose of this study was to evaluate histologically the effect of topically applied minocycline on replacement resorption of replanted monkeys' teeth. Thirty-two roots from seven monkeys were endodontically treated aseptically to prevent inflammatory resorption of pulpal origin, a common sequela after avulsion injury. Teeth were then extracted as atraumatically as possible. Teeth in the negative control group (10 roots) were replanted almost immediately, while teeth in the positive control group (12 roots) were allowed to bench-dry for 1 h prior to replantation, both without further treatment. Teeth in the experimental group (10 roots) were bench-dried for 1 h, rinsed with saline, and then immersed in 1 ml of 50 mg ml(-1) minocycline hydrochloride for 5 min before replantation. No splinting was used. After 12 weeks, the animals were sacrificed and histological sections were prepared and evaluated according to a morphometric analysis modified from that described by Andreasen (1987) as complete healing, inflammatory resorption, and replacement resorption. Kruskal-Wallis test showed significant differences among the three groups in all the three healing categories. Further analysis with Mann-Whitney U-test showed teeth in the negative control group to have significantly higher complete healing and significant lower unfavorable healing, comprising of replacement resorption and inflammatory root resorption than the positive control group and the minocycline group. Topical application of minocycline to the root surface appeared to result in slightly higher occurrence of complete healing (32.46%) compared to the delayed replantation group with no minocycline treatment (positive control) (16.58%), but the difference was not statistically significant (P = 0.09).

Effect of catalase supplementation in storage media for avulsed teeth

The type of liquid medium used to store avulsed teeth prior to replantation has been shown to affect the long-term prognosis. One possibility is that some storage media contain hydrogen peroxide (H2O2) that may be toxic to periodontal ligament cells. Therefore, the aim of this study was to determine if the addition of catalase to storage media improved the prognosis of replanted dog teeth. Forty-eight mongrel premolar roots were endodontically treated, extracted, randomly divided and placed into one of four storage media: Hank's balanced salt solution (HBSS), containing no antioxidant); Viaspan, containing the antioxidant, glutathione, or the same two media supplemented with catalase(100 U ml(-1)) for 1, 5, or 26 h prior to replantation. After 2 months, the dogs were euthanized and the roots histologically examined to evaluate the attachment tissues. Regardless of the storage medium used, overall healing was excellent and only 4% of the roots displayed inflammatory or replacement resorption. When roots from the different storage media were compared, those stored in HBSS were found to display the highest incidence of surface resorption (55.7%). Supplementation of HBSS with catalase resulted in a lower level of surface resorption (48.6%) that was statistically significant (P < 0.05). Roots stored in Viaspan - or + catalase displayed even lower levels of surface resorption (41.3 and 38.2%, respectively). The improvement observed with catalase-supplemented HBSS was confined to the 45-min incubation period; only Viaspan - or + catalase reduced surface resorption at the 5- and 26-h incubations. Collectively, these data demonstrate that roots stored in media containing antioxidant activity undergo less surface resorption. These results suggest that low levels of H2O2 in storage media for avulsed teeth may adversely affect periodontal ligament cells.

Extraoral endodontic treatment by retrograde insertion of posts: a long-term study on replanted and transplanted teeth

OBJECTIVE

The aim of the study was to investigate the healing results of teeth replanted or transplanted in different indications and treated by extraoral root canal therapy.

STUDY DESIGN

Extraoral root canal treatment was performed from a retrograde direction with posts made of ceramics or titanium. Preoperatively, the pulp status was classified as definitely infected (n = 47) or not infected/symptomless (n = 78), and the condition of the periodontal ligament (PDL) was classified as damaged (n = 50) or not damaged (n = 75) according to trauma type and extraoral storage. The healing after replantation or transplantation was diagnosed as functional, ankylosis, or infection depending on clinical and radiographic findings.

RESULTS

In total, 125 teeth in 99 patients were replanted or transplanted. Mean observation period was 44.4 months. Teeth with a less damaged PDL in no case exhibited ankylosis/replacement resorption after a mean observation period of 53 months. Teeth without preoperative infection of the pulp in no case showed infection-related complications after a mean observation period of 30 months. Teeth classified as definitely infected before treatment had a high frequency of continuous periradicular bone and root resorption.

CONCLUSIONS

The extraoral insertion of posts appeared to inflict no additional damage to the PDL that was clinically relevant. Infection-related complications were prevented. Teeth that were classified as definitely infected at the time of treatment had a low rate of healing and should undergo conventional root canal disinfection before this surgical procedure is applied.

Treatment of replacement resorption with Emdogain--a prospective clinical study

The present clinical study investigated the outcome of intentional replantation using Emdogain for periodontal healing following trauma-related ankylosis. Sixteen ankylosed teeth affected by replacement resorption were treated as follows: After tooth extraction, the root canal was obturated with a retrograde titanium post. Emdogain was applied to the root surface and into the extraction socket with subsequent replantation of the tooth. Evaluation parameters included horizontal and vertical Periotest scores, percussion sound and periapical radiographs. All findings were compared to those of the adjacent teeth. The mean follow-up period was 15 months (range 4-24 months). Eleven teeth showed no signs of recurrence of ankylosis: they were in full function and exhibited no pathological clinical findings. Four severely traumatized teeth demonstrated a recurrence of ankylosis after a mean period of 6 months, one tooth was lost in a second accident after 7 months. The estimated probability of 1 year without recurrence of ankylosis was P=0.66 (95% confidence interval [0.40; 0.94]). The mean survival time was 10.2 months (SD 1.1). The results indicate that treatment of replacement resorption following light to moderate trauma with replantation and Emdogain appears to prevent or delay recurrence of ankylosis in many cases.

Effect of topical alendronate on root resorption of dried replanted dog teeth

Alendronate (ALN) is a third generation bisphosphonate with demonstrated osteoclast inhibitory activity that may slow down the resorptive process after severe traumatic injuries. Eighty-two premolar roots of five mongrel dogs were endodontically treated and restored, extracted and treated as follows: 70 roots were bench dried for either 40 or 60 min. Thirty-eight of these roots were then soaked for 5 min in a 1 mM solution of ALN in Hanks' Balanced Salt Solution (HBSS) and replanted. Thirty-two roots were soaked for 5 min in HBSS and replanted. In the remaining 12 roots which were not exposed to the bench drying procedure, a 0.5 mM deep lingual mid-root cemental defect was made. Six of these roots were soaked in a 1 mM solution of ALN in HBSS for 5 min and replanted. The other six roots were soaked for 5 min in HBSS and replanted. Historical negative and positive controls were used from similarly treated teeth in our previous studies. After 4 months the dogs were killed and the roots prepared for histological evaluation. Five-microm-thick cross-sections of the root and surrounding tissue taken every 70 microm were evaluated for healing according to the criteria of Andreasen. In the 12 roots with cemental defects, healing with cementum of the damaged root surface was evaluated. In addition, residual root mass was also measured to determine the extent of root structure loss for each soaking method. Cemental healing took place in all 12 artificially damaged roots, indicating that these soaking media did not inhibit cementogenesis. The alendronate-soaked roots had statistically significantly more healing than the roots soaked in HBSS without alendronate. This improvement in healing was seen in all dogs except one and in all teeth except the first premolar. Soaking in alendronate also resulted in significantly less loss in root mass due to resorption compared to those teeth soaked in HBSS without alendronate.

Treatment of replacement resorption with Emdogain--preliminary results after 10 months

Ankylosis of traumatized teeth in children and adolescents may inhibit further development and growth of the corresponding jawbone. Therefore, ankylosed teeth should be removed. As an alternative treatment option to autotransplantation of a premolar, intentional replantation using Emdogain may be considered, provided the ankylosis is detected at an early stage or has only affected a small area of the root. Eleven ankylosed teeth presenting with replacement resorption were treated as follows: after tooth extraction, the root canal was treated extraorally and obturated by retrograde insertion of a titanium post. Emdogain was applied to the root surface and into the extraction socket with subsequent replantation of the tooth. During a mean follow-up period of 6.3 months, no signs of recurrence of ankylosis were noted. The horizontally and vertically measured Periotest scores were identical to those obtained on the adjacent teeth. These results suggest that intentional replantation using Emdogain may prevent or delay ankylosis of these replanted teeth.

In vitro viability, mitogenicity and clonogenic capacity of periodontal ligament cells after storage in six different media

The choice of storage medium for preserving traumatically avulsed teeth is important for the success of future replantation. The objectives of this study were to evaluate the effectiveness of six different media: culture medium, alpha minimal essential medium (alpha-MEM), milk, Hank's balanced salt solution (HBSS), ViaSpan and conditioned medium (CM) to preserve cultured periodontal ligament fibroblasts (PDLF). Periodontal ligament fibroblasts were obtained from explants of human healthy extracted teeth. Plates with confluent PDLF were soaked in the various media for 2, 8 and 24 h at 4 degrees C. A control group was incubated with culture medium at 37 degrees C. After incubation, cell viability was determined by trypan blue exclusion test. Viable cells were then analyzed for mitogenic (with thymidine) and clonogenic capacity (by culturing one cell/well). Storage of PDLF up to 24 h decreased their vitality by only 2%-14%. Vitality of the PDLF after 2, 8 and 24 h was highest when stored in milk or HBSS (91%-97%) and lowest when stored in ViaSpan or CM (82%-93%). PDLF stored for 2-8 h in various media had a mitogenic capacity comparable to the control. However, increasing the storage period to 24 h decreased the mitogenicity of the cells by 3%-39%. The highest mitogenicity was found in PDLF stored in milk or HBSS and the lowest in CM or ViaSpan. The clonogenic capacity of the cells dropped by 38%-71% after 24 h and was the best indicator of the deteriorating effect of long storage. Milk and HBSS were the most effective in preserving the clonogenic capacity. Nevertheless, reduction in the viability, mitogenicity or clonogenic capacity was statistically significant in nearly all the tested media only after 24 h of incubation. In conclusion, HBSS and milk were the most effective media for preserving the viability, mitogenicity and clonogenic capacity after storage for up to 24 h at 4 degrees C.

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.

Effect of systemic tetracycline and amoxicillin on inflammatory root resorption of replanted dogs' teeth

The use of systemic penicillin after an avulsion injury has been recommended as a way to decrease the occurrence of resorption complications. Our previous study has shown systemic tetracycline to possess anti-resorptive properties independent of potential anti-bacterial actions. The purpose of this study was to compare histologically the effectiveness of tetracycline and amoxicillin in limiting inflammatory root resorption (IR) secondary to pulpal infection, in replanted dogs' teeth. Thirty root canals in five dogs were infected with plaque. The roots were extracted, the lingual mid-roots were shaved with a fissure bur ensuring cemental damage and immediately replanted. Dogs were given either tetracycline hydrochloride or amoxicillin, administered orally, on the day of extraction and replantation and for the following 6 days. The control group was teeth in these animals treated in the same manner but where no antibiotics were given. After approximately 6 months, the dogs were sacrificed and the teeth prepared for histologic evaluation. The shaved root surface was identified in cross-sections and eight equidistant points along the cut root surface were evaluated for healing (H) or IR in eight sections per tooth. For the tetracycline group, H averaged 67.22% and IR 32.78%, which was not statistically different from the amoxicillin group with H averaging 56.88% and IR 43.12%. The tetracycline group was superior to the control group with H = 27.86% and IR = 72.14%. Since tetracycline has been shown to have anti-resorptive properties in addition to the antibacterial properties demonstrated here, it could be considered as an alternative to amoxicillin after avulsion injuries.

Susceptibility of Nd:YAG laser-irradiated root surfaces in replanted teeth to external inflammatory resorption

Nd:YAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2 x 3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n = 12 roots) and 3 (n = 4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 pps, 300 microns tip, 20 s). In Groups 2 (n = 12) and 4 (n = 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfusion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 microns) at 180-microns intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P < 0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in Nd:YAG laser-irradiated dentin. Therefore, the clinical application of Nd:YAG laser to the root surfaces of replanted teeth is not warranted.

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

This study was designed to evaluate the effect of soaking in either Hank's balanced salt solution (HBSS) or milk on periodontal 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 significant improvement in PDL cell viability by the addition of this step was demonstrated under the conditions of this study.

The effect of systemic tetracycline on resorption of dried replanted dogs' teeth

The use of systemic penicillin after an avulsion injury has been recommended to decrease the occurrence of resorption complications. Tetracycline antibiotics have been reported to possess anti-resorptive properties in addition to their anti-microbial actions. The purpose of this study was to evaluate histologically the effect of systemically administered tetracycline and amoxicillin on the inhibition of resorption due to attachment damage after replantation of dogs' teeth. Thirty-one roots from the teeth of four beagle dogs were endodontically treated to inhibit subsequent inflammatory root resorption of pulpal origin. They were then extracted and left to bench dry for 1 h to ensure severe periodontal ligament damage before replantation. For the teeth in the experimental groups, two dogs were given tetracycline hydrochloride and the other two dogs were given amoxicillin, administered orally, on the day of extraction/replantation and for the following 6 days. The control group were teeth in these animals treated in the same manner but where no antibiotics had been given. After 12-16 weeks, the dogs were sacrificed and histological sections were prepared and evaluated for complete healing, inflammatory and replacement root resorption, and the groups were compared. It was shown that healing in the amoxicillin and the control groups was poor (10.90% and 11.28%, respectively), while for the tetracycline group, 35.45% showed complete healing. Individual teeth with over 50% complete healing sites were considered as having good healing, and significantly more of these teeth were found in the tetracycline group (5 of 11 teeth) compared to the amoxicillin (1 of 11 teeth) or control group (1 of 8 teeth).