Immunohistological evaluation of revascularized immature permanent necrotic teeth treated by platelet-rich plasma: an animal investigation

Objective: pulp regeneration within the root canal of necrotic teeth is considered an ideal treatment to allow for continued root development and recover teeth vitality. This study aims to evaluate the inductive effect of platelet-rich plasma [PRP] on expression of angiogenesis factors and pulpal revascularization of immature necrotic teeth

Materials and Methods: in this experimental animal study, we randomly divided 28 immature premolars from two mixed breed dogs into four groups, two experimental, negative and a positive control. Premolars in negative control group were left intact to develop normally. In the positive control and experimental groups, we removed the pulps and induced pulp necrosis, after which the chambers were sealed. Then, we applied the revascularization protocol in the experimental teeth located in the right quadrant. Two months later, the same protocol was applied to the left quadrant. The root canals were disinfected by irrigation with sodium hypochlorite [NaOCl] solution and application a triple antibiotic past. Following the induction of a blood clot [BC] inside the canal space, the coronal portion of the canals was assigned to either of two experimental groups: group 1 [BC+PRP+ mineral trioxide aggregate [MTA]], group 2 [BC+MTA]. Access cavities were sealed with a Glass Ionomer. The jaws that held the teeth were processed for histologic analysis of newly formed tissue and immunohistochemical evaluation according to vascular endothelial growth factor [VEGF] and factor VIII expressions in the canals

Results: histological analysis demonstrated no significant difference in the formation of new vital tissue inside the root canals between groups1 [42.8%] and 2 [43.5%, P>0.05]. Based on immunohistochemical evaluation, micro-vessel density [MVD] of the granulation tissues in both groups were similar and were higher compared with the normal pulp. We observed strongly positive expressions of VEGF and factor VIII in the stromal and endothelial cells, with severe intensity after one month. Both factors showed down-regulation at three months postoperative

Conclusion: PRP could not increase the formation of new vital tissue. The immunohistochemical results showed that VEGF and factor VIII played a pivotal role in the formation of new vessels inside the root canals of immature, non-vital teeth

effect of propolis as a biological storage media on periodontal ligament cell survival in an avulsed tooth: an in vitro study

Both the length of extra-alveolar time and type of storage media are significant factors that can affect the long-term prognosis of replanted teeth. This study aims to compare propolis 50%, propolis 10%, Hank's balanced salt solution [HBSS], milk and egg white on periodontal ligament [PDL] cell survival for different time points. In this in vitro experimental study, we divided 60 extracted teeth without any periodontal diseases into five experimental and two control groups that consisted each experimental group with 10 and each control group with 5 teeth. The storage times were one and three hours for each media. The controls corresponded to 0-minute [positive] and 12-hour [negative] dry time. Rinsing in the experimental media, the teeth were treated with dispase and collagenase for one hour. Cell viability was determined by using trypan blue exclusion. Statistical analysis of the data was accomplished by using two-way analysis of variance [ANOVA] complemented by the Tukey's HSD post-hoc. Within one hour, there was no significant difference between the two propolis groups, however these two groups had significantly more viable PDL cells compared to the other experimental media [p<0.05]. The results of the three-hour group showed that propolis 10% was significantly better than egg white, whereas both propolis 10% and 50% were significantly better than milk [p<0.05]. Based on PDL cell viability, propolis could be recommended as a suitable biological storage media for avulsed teeth

Effect of propolis on dentin regeneration and the potential role of dental pulp stem cell in guinea pigs

Evaluation of the effect of Propolis as a bioactive material on quality of dentin and presence of dental pulp stem cells. For conducting this experimental split-mouth study, a total of 48 maxillary and mandibular incisors of male guinea pigs were randomly divided into an experimental Propolis group and a control calcium hydroxide group. Cutting the crowns and using Propolis or calcium hydroxide to cap the pulp, all of the cavities were sealed. Sections of the teeth were obtained after sacrificing 4 guinea pigs from each group on the 10th, 15th and 30th day. After they had been stained by hematoxylin and eosin [H and E], specimens underwent a histological evaluation under a light microscope for identification of the presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulp and the presence of remnants of the material used. The immunohistochemistry [IHC] method using CD[29] and CD[146] was performed to evaluate the presence of stem cells and the results were statistically evaluated by Kruskal-Wallis, Chi Square and Fisher tests. In H and E stained specimens, there was no difference between the two groups in the presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulp and the presence of remnants of used material[p>0.05]. There was a significant difference between the quality of regenerative dentin on the 15[th] and 30[th] days [p<0.05]: all of the Propolis cases presented tubular dentin while 14% of the calcium hydroxide cases produced porous dentin. There was no significant difference between Propolis and calcium hydroxide in stimulation of dental pulp stem cells [DPSCs]. This study which is the first one that documented the stimulation of stem cells by Propolis, provides evidence that this material has advantages over calcium hydroxide as a capping agent in vital pulp therapy. In addition to producing no pulpal inflammation, infection or necrosis this material induces the production of high quality tubular dentin

Coronal sealing ability of three temporary filling materials

Providing adequate coronal seal of temporary filling materials is critical for the success of root canal therapy. The aim of this in vitro study was to compare coronal seal ability of three restorative materials over different periods of time. Ninety-eight molar teeth were selected. Once access cavities were prepared, teeth were divided randomly into three time groups [1 day, 1 week, and 4 weeks]. Each group was then subdivided into three groups of 10 teeth. Each subgroup was restored using one of three restorative materials including Coltosol, Cavizol and Zonalin and then incubated in distilled water at 37[degree]C. The samples were then immersed in 2% methylene blue dye. After rinsing and drying, teeth were sectioned longitudinally and examined for dye penetration. Kruskal-Wallis and Mann Whitney U tests were used to analyze the data. All experimented materials showed increasing leakage from the 1[st] day to the 4[th] week. Zonalin showed more leakage than Coltosol and Cavizol at each time interval [P<0.05], but there was no significant difference between Coltosol and Cavizol. Coltosol and Cavizol are suitable temporary materials for up to 1 week

Relation between pulpal neuropeptides and dental caries

Dental pulp has neural fibers that produce neuropeptides like Substance P [SP] and calcitonin gene-related peptide [CGRP]. The inflammation of dental pulp can lead to an increase amount of SP and CGRP release, especially in symptomatic irreversible pulpitis. Therefore, it can be assumed that neuropeptides have some role in the progression of inflammation of the dental pulp. The aim of this study was to determine the relation between the presence and concentration of neuropeptides in dental pulps of carious teeth caries. For this purpose, pulpal tissues were collected from 40 teeth [20 carious and 20 intact]. Pulpal samples were cultured for 72 hours. ELISA reader was used for the detection of SP and CGRP in supernatant fluids. Statistical analysis was made by Mann-Whitney U and Chi square tests. SP and CGRP were present in 65% and 20% of inflamed pulpal samples, respectively and 40% and 5% of normal pulpal samples, respectively. Level of SP was significantly higher in inflamed pulp samples compared to intact pulps; however, there was no statistical difference when the other groups and neuropeptides were compared. The mean concentration of SP in normal pulps was 3.4 times greater than that of CGRP; interestingly in inflamed pulps the concentration of SP was 22.3 times greater than CGRP. We can conclude that in inflamed dental pulps, the concentration of SP is higher than CGRP. It can be hypothesized that CGRP has less effect on the inflammatory changes of dental pulps