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

Apexogenesis and revascularization treatment procedures for two traumatized immature permanent maxillary incisors: a case report

Traumatic injuries to an immature permanent tooth may result in cessation of dentin deposition and root maturation. Endodontic treatment is often complicated in premature tooth with an uncertain prognosis. This article describes successful treatment of two traumatized maxillary central incisors with complicated crown fracture three months after trauma. The radiographic examination showed immature roots in maxillary central incisors of a 9-year-old boy with a radiolucent lesion adjacent to the right central incisor. Apexogenesis was performed for the left central incisor and revascularization treatment was considered for the right one. In 18-month clinical and radiographic follow-up both teeth were asymptomatic, roots continued to develop, and periapical radiolucency of the right central incisor healed. Considering the root development of these contralateral teeth it can be concluded that revascularization is an appropriate treatment method in immature necrotic teeth.

Effect of different air-drying time on the microleakage of single-step self-etch adhesives

OBJECTIVES: This study evaluated the effect of three different air-drying times on microleakage of three self-etch adhesive systems. MATERIALS AND METHODS: Class I cavities were prepared for 108 extracted sound human premolars. The teeth were divided into three main groups based on three different adhesives: Opti Bond All in One (OBAO), Clearfil S3 Bond (CSB), Bond Force (BF). Each main group divided into three subgroups regarding the air-drying time: without application of air stream, following the manufacturer's instruction, for 10 sec more than manufacturer's instruction. After completion of restorations, specimens were thermocycled and then connected to a fluid filtration system to evaluate microleakage. The data were statistically analyzed using two-way ANOVA and Tukey-test (alpha = 0.05). RESULTS: The microleakage of all adhesives decreased when the air-drying time increased from 0 sec to manufacturer's instruction (p < 0.001). The microleakage of BF reached its lowest values after increasing the drying time to 10 sec more than the manufacturer's instruction (p < 0.001). Microleakage of OBAO and CSB was significantly lower compared to BF in all three drying time (p < 0.001). CONCLUSIONS: Increasing in air-drying time of adhesive layer in one-step self-etch adhesives caused reduction of microleakage, but the amount of this reduction may be dependent on the adhesive components of self-etch adhesives.

[ in vitro evaluation of coronal microleakage through four temporary restorations by dye penetration]

Temporary restorations should be able to seal the access cavity and prevent bacterial leakage. The aim of this study was to evaluate the amount of dye penetration through temporary restorations, namely Zonalin, Zamharir, IRM and Coltosol, into the root canal. In this experimental study, 120 sound human premolar teeth were selected. After access cavity preparation, cleaning and shaping were accomplished using step-back technique and obturated by lateral condensation technique using gutta-percha and AH-26 sealer. The teeth were divided into six groups [n=20]. In the first to fourth group, the crown was restored with zonalin, zamharir, IRM and coltozol. Group five and six were considered as positive and negative control. After keeping these teeth in 37[degree sign] C and 100% humidity for 48 hours, samples were immersed in 10% Indian ink for 72 hours. After sectioning the crowns longitudinally the amounts of dye penetration in the two halves of teeth were assessed using stereomicroscope [xlO]. Statistical analyses were performed using ANOVA test. Zonalin had minimum and Coltosol had maximum amount of dye penetration. There were not any significant differences between the Zonalin-Zamharir groups and between the IRM- Coltosol groups [p>0.05]. Regarding different materials with ZOE base used in this study to treat tooth root, zonal in is the best as a temporary restorative material. However more comprehensive studies need to be performed about Zamharir

Microscopic evaluation of cleaning efficiency of three different Nickel-Titanium rotary instruments

This study compared the cleaning efficiency of Mtwo, Race and Medin Nickel-Titanium [NiTi] rotary instruments. Sixty mandibular molar mesial roots were selected with angle curvatures between 25-35 degrees and divided into three groups; each containing 20 teeth. Canals were prepared with the rotary files and irrigated with 2.5% NaOCl solution after each instrument. Total of 5mL of normal saline was used as the final rinse; subsequently the canals were dried with paper points. The amount of debris and smear layer in three parts of the root canal walls was evaluated using SEM and the data were analyzed by using the Kruskal-Wallis test and the Mann-Whitney U test. The results for remnant debris in the coronal part of root canals were similar, whereas in the middle third, Mtwo instruments achieved significantly better results compared to Race and Medin instruments. In the apical third of the root canals more debris was created by Race instruments. Overall, Mtwo instruments had greater success in producing clean canals

In vitro comparison of apical leakage in root canals obturated with 0.04 and 0.02 tapered gutta-percha

Gutta-percha is the most commonly used material for root canal obturation; it has been recently manufactured with different tapers. The aim of this in vitro study was to compare microleakage of canals obturated with standard gutta-percha [0.02 taper] or the new 0.04 taper gutta-percha master cone using the cold lateral condensation technique. Forty-four extracted single rooted teeth were selected. The crowns were removed and all the canals were prepared using RaCe rotary files. The teeth were then divided into experimental [n=2] and control [n=2] groups. In the first study group, the teeth were obturated with 0.02 taper gutta-percha master cone and lateral condensation. In the second study group, the canals were obturated by 0.04 tapered master cones and the same obturation method. The degree of leakage was measured using fluid filtration method. Data were analyzed statistically by student t-test. There was no significant difference between the mean microleakage of two experimental groups [P=0.558]. Lateral condensation technique using 0.04 tapered master cones can provide an effective apical seal similar to 0.02 gutta-percha cones