An experimental study of simvastatin-collagen composite sponge as a direct pulp capping material in rat molars / 华西口腔医学杂志

OBJECTIVE@#To assess the feasibility and efficacy of simvastatin-collagen composite sponge as a novel, direct pulp capping material.@*METHODS@#A total of 120 Sprague-Dawley rats were randomly divided into three groups: the simvastatin-collagen composite sponge group (SIM group), the collagen sponge group (CS group), and the Ca(OH)2 group (CH group). An endodontic entry cavity was prepared on the occlusion of the first molar on the left maxillary of each rat. The contralateral teeth were utilized as the normal control group. The rats were experimented after 1, 3, 7, 14, and 28 days. X-ray observations were conducted and the specimens underwent hematoxylin-eosin (HE) and Masson's Thichrome staining. Dentin bridge formations and pulpal biology reactions were evaluated histopathologically.@*RESULTS@#X-ray results: high-density images could be observed on the pulp exposure sites in the CH group on the 28th day. In the SIM group, high-density images could be observed after 14 and 28 days, whereas in the CS group, high-density images were not observable in the exposed area. HE and Masson's Thichrome staining results: different degrees of inflammation under the cavity were detected in the three groups at different time points. The inflammatory reaction of the CS group was the most serious. The degree of the inflammatory reaction varied significantly between the SIM and the CS groups on the 14th and 28th days (P<0.01). The inflammatory reaction in the SIM group was lighter than in the CH group. There was a statistical difference between the SIM and the CH groups on the 14th day (P<0.05). During the observation period, the SIM group induced the best and fastest formation of reparative dentin. As for dentin bridge formation, a significantly higher complete bridge rate was observed in the SIM group than in the CH and in the CS groups on the 14th day (P<0.05) and for the SIM and the CH groups compared with the CS group on the 28th day (P<0.05).@*CONCLUSIONS@#The simvastatin-collagen composite sponge exhibited satisfactory biocompatibility with the pulp tissue and promoted the formation of reparative dentin. The application of simvastatin-collagen composite sponge as a pulp-capping material has satisfactory potential.

Effects of the exposure site on histological pulpal responses after direct capping with 2 calcium-silicate based cements in a rat model

OBJECTIVES: Direct pulp capping is a treatment for mechanically exposed pulp in which a biocompatible capping material is used to preserve pulpal vitality. Biocompatibility tests in animal studies have used a variety of experimental protocols, particularly with regard to the exposure site. In this study, pulp exposure on the occlusal and mesial surfaces of molar teeth was investigated in a rat model. MATERIALS AND METHODS: A total of 58 maxillary first molars of Wistar rats were used. Forty molars were mechanically exposed and randomly assigned according to 3 factors: 1) the exposure site (occlusal or mesial), 2) the pulp-capping material (ProRoot White MTA or Bio-MA), and 3) 2 follow-up periods (1 day or 7 days) (n = 5 each). The pulp of 6 intact molars served as negative controls. The pulp of 12 molars was exposed without a capping material (n = 3 per exposure site for each period) and served as positive controls. Inflammatory cell infiltration and reparative dentin formation were histologically evaluated at 1 and 7 days using grading scores. RESULTS: At 1 day, localized mild inflammation was detected in most teeth in all experimental groups. At 7 days, continuous/discontinuous calcified bridges were formed at exposure sites with no or few inflammatory cells. No significant differences in pulpal response according to the exposure site or calcium-silicate cement were observed. CONCLUSIONS: The location of the exposure site had no effect on rat pulpal healing. However, mesial exposures could be performed easily, with more consistent results. The pulpal responses were not significantly different between the 2 capping materials.

Recent advances in direct pulp capping materials / 华西口腔医学杂志

The long-term effect of direct pulp capping and pulpotomy is closely related to the type of pulp capping materials. Various kinds of direct pulp capping materials are available, such as calcium hydroxide and mineral trioxide aggregates. Diverse new pulp capping materials have been reported recently. The excellent performance of calcium silicates has attracted much attention in previous studies. Moreover, enamel matrix derivative (Emdogain), which is capable of regeneration and remineralization, and other materials with similar capabilities have shown potential for use in pulp capping.

Observation of clinical effects of mineral trioxide aggregate as direct pulp capping in immature permanent an-terior teeth / 口腔疾病防治

Objective@# To evaluate the clinical effects of mineral trioxide aggregate (MTA) as apulp-dressing agent in immature permanent anterior teeth. @*Methods @#68 perma nent anterior teeth with deep caries or accidental pulp exposure were randomly divided into treatment group (MTA) and control group (calcium hydroxide). The exposed pulps were treated permanently with direct pulp capping. The effect of potential clinical variables on the treatment outcome was evaluated clinically and radiographically during a 24-month follow-up. In order to assess the cumulative successes, data were analyzed with chi-square test and log-rank test (α= 0.05). @*Results @#The successful rate of the treatment group (91.4%) was higher than that of the control group (60.6%) significantly (P < 0.05). None of the gender, occlusal site, type of pulp exposure, site and diameter of pulp exposure had a considerable influence on the outcome (P > 0.05).@*Conclusion@# MTA as a biocompatable, osteogenesis-inducing and inflammation-controlling material appears to be suitable for direct pulp capping.

Histopathologic responses of human dental pulp to calcium hydroxide and mineral trioxide aggregate as pulp capping agents / 实用医学杂志

Objective To investigate human pulpal response to mineral trioxide aggregate (MTA) and calcium hydroxide (CH) as pulp capping agents. Methods This study was conducted on 90 intact first and second premolars of human maxillary and mandibular teeth of 30 volunteers. The patients were randomly assigned into three groups with 10 in each group. Under local anesthesia, the teeth were exposed and capped either with MTA, or CH. After 30, 60, and 90 days, 10 teeth of each group were extracted and prepared for histologic ob-servation. The data were analyzed with Wilcoxon rank sum test and paired t-tests (α = 0.05). Results MTA had a higher success rate and resulted in less pulpal inflammatory response and more predictable hard dentin bridge formation than CH (P < 0.05). Conclusion MTA appears to be a suitable replacement for CH in direct pulp capping.

The Role of Autonomous Wntless in Odontoblastic Differentiation of Mouse Dental Pulp Cells

PURPOSE: Wnt signaling plays an essential role in the dental epithelium and mesenchyme during tooth morphogenesis. Deletion of the Wntless (Wls) gene in odontoblasts appears to reduce canonical Wnt activity, leading to inhibition of odontoblast maturation. However, it remains unclear if autonomous Wnt ligands are necessary for differentiation of dental pulp cells into odontoblast-like cells to induce reparative dentinogenesis, one of well-known feature of pulp repair to form tertiary dentin. MATERIALS AND METHODS: To analyze the autonomous role of Wls for differentiation of dental pulp cells into odontoblast-like cells, we used primary dental pulp cells from unerupted molars of Wls-floxed allele mouse after infection with adenovirus for Cre recombinase expression to knockout the floxed Wls gene or control GFP expression. The differentiation of dental pulp cells into odontoblast-like cells was analyzed by quantitative real-time polymerase chain reaction. RESULT: Proliferation rate was significantly decreased in dental pulp cells with Cre expression for Wls knockout. The expression levels of Osterix (Osx), runt-related transcription factor 2 (Runx2), and nuclear factor I-C (Nfic) were all significantly decreased by 0.3-fold, 0.2-fold, and 0.3-fold respectively in dental pulp cells with Wls knockout. In addition, the expression levels of Bsp, Col1a1, Opn, and Alpl were significantly decreased by 0.7-fold, 0.3-fold, 0.8-fold, and 0.6-fold respectively in dental pulp cells with Wls knockout. CONCLUSION: Wnt ligands produced autonomously are necessary for proper proliferation and odontoblastic differentiation of mouse dental pulp cells toward further tertiary dentinogenesis.

Effect of Mineral Trioxide Aggregate and Calcium Hydroxide on Reparative Dentin Formation in Rats

We investigated the pulpal response to direct pulp capping in rat molar teeth using mineral trioxide aggregate (MTA) and calcium hydroxide (CH). A palatal cavity was prepared in rat maxillary molar teeth. Either MTA or CH was placed on the exposed pulp and all cavities were restored with composite. Rats were sacrificed for histological evaluation after 12 hours and at 2, 7, 14 and 21 days. In both the MTA and CH groups, reparative dentin formation was clearly observed on histology after 14 days. The MTA-capped pulps were found to be mostly free from inflammation, and hard tissue of a tubular consistent barrier was observed. In contrast, in CH-capped teeth, excessive formation of reparative dentin toward residual pulp was evident. The pulpal cell response beneath the reparative dentin layer was examined by immunofluorescence using antibodies against DSP. After 2 days, a few DSP immunopositive cells, most of which showed a cuboidal shape, appeared beneath the predentin layer. At 7 days, DSP-immunopositive cells with columnar odontoblast-like cells were seen beneath the newly formed hard tissues. At 14 and 21 days, DSP was more abundant in the vicinity of the odontoblastic process along the dentinal tubules than in the mineralized reparative dentin. The CH group showed strong expression patterns in terms of DSP immunoreactivity. Our results thus indicate that MTA may be a more effective pulp capping material as it induces the differentiation of odontoblast-like cells and the formation of reparative dentin without the loss of residual pulp functions.

Histological evaluation of direct pulp capping with DSP-derived synthetic peptide in beagle dog / 대한치과보존학회지

The purpose of this study was to investigate the pulpal response to direct pulp capping with dentin sialoprotein (DSP)-derived synthetic peptide in teeth of dogs, and to compare its efficacy to capping substances Ca(OH)2 and white mineral trioxide aggregate (WMTA). A total of 72 teeth of 6 healthy male beagle dogs were used. The mechanically exposed pulps were capped with one of the following: (1) DSP-derived synthetic peptide (PEP group); (2) Ca(OH)2 (CH group); (3) a mixture paste of peptide and Ca(OH)2 (PEP+CH group); or (4) white MTA (WMTA group). The access cavity was restored with a reinforced glass ionomer cement. Two dogs were sacrificed at each pre-determined intervals (2 weeks, 1 month, and 3 months). After the specimens were prepared for standard histological processing, sections were stained with hematoxylin and eosin. Under a light microscope, inflammatory response and hard tissue formation were evaluated in a blind manner by 2 observers. In the PEP group, only 3 of 17 specimens showed hard tissue formation, indication that the DSP-derived synthetic peptide did not induce proper healing of the pulp. Compared with the CH group, the PEP group demonstrated an increased inflammatory response and poor hard tissue formation. The CH and WMTA groups showed similar results for direct pulp capping in mechanically exposed teeth of dogs.

Histological Study of Reparative Dentin Formation after Direct Pulp Capping and Pulpotomy using MTA / 대한해부학회지

The ultimate goal of a regenerative pulp treatment strategy is to reconstitute normal tissue continuum at the pulp-dentin border, regulating tissue-specific processes of reparative dentinogenesis. However, little is known about the molecular mechanism of reparative dentinogenesis. The purpose of this study was to investigate the pulpal response after direct pulp capping and pulpotomy with mineral trioxide aggregate (MTA) by histological and immunohistochemical studies. There was continuous reparative dentin bridge formation at 2 weeks after treatment with MTA in both the pulp capping and the pulpotomy groups. The cells in the pulp capping group showed typical odontoblast characteristics, while the cells of reparative dentin in pulpotomy group were round in shape, lost their polarity, organized as a sheet of cells, and trapped in osteodentin-like mineralized tissue. In pulp capping group, upper layer of the reparative dentin showed cell lacunae indicating osteoblastic characteristics, whereas lower layer of the reparative dentin contained predentin and dentinal tubule-like structures as normal dentin. However, there was osteodentin formation in pulpotomy group. DSP protein was expressed at 4 weeks in odontoblasts of pulp capping group, while BSP was expressed at 4 weeks after pulpotomy. These results suggest that two different types of reparative dentin formation, dentin-like and bone-like dentin, may depend on the type and extent of the injury and the effect of the associated defense reaction on the structural and functional integrity at the dentin-pulp border.

The effect of rhBMP2 used as a indirect pulp capping agent / 实用口腔医学杂志

Objective: To investigate the reparative dentine formation induced by the recombinant human bone morphorgenetic protein2(rhBMP2) used as a indirect pulp capping agent in dog teeth. Methods: Type V cavities were prepared in 48 teeth of 2 dogs. rhBMP2 with zinc oxide(A) was lined on the bottom of 24 cavities, saline with zinc oxide(B) in 12 and zinc oxide eugentol cement(C) in 12. 0.5 g of tetracycline was orally administered to the dogs twice a day on day 24, 54, 83 and 111. On day 135, the teeth were extracted and processed for the quantitative observation of reparative dentin under a fluorescent microscope .Results: On day 135, the reparative dentine (expressed as "?m" of diameter of area) in group A, B and C was 825.04? 125.46, 315.33? 80.43 and 415.25? 90.75 respectively(P