Cytotoxic effects and pulpal response caused by a mineral trioxide aggregate formulation and calcium hydroxide.

PURPOSE: To evaluate the in vivo pulpal response after pulpotomy with different capping agents. In addition, the in vitro cytotoxic effects of both materials were assessed by applying them on culture of pulp cells. METHODS: For the in vivo test, the coronal pulp of 28 teeth of dogs was mechanically removed and the root pulps were capped with the following dental materials: Group 1: Pro-Root MTA (PRMTA); and Group 2 (control): calcium hydroxide saline paste (CH). After 60 days, the animals were sacrificed and the teeth processed for histological analysis. In the in vitro test, experimental extracts obtained from both capping agents were applied on the cultured MDPC-23 odontoblast-like cells. RESULTS: In the root pulps capped with PRMTA or CH, coagulation necrosis partially replaced by dystrophic calcification as well as tubular dentin matrix laid down by elongated pulp cells was observed. None or mild inflammatory response occurred beneath the capped pulpal wound. Regarding the pulpal response, PRMTA and CH presented no statistical difference. However, the teeth capped CH presented greater healthy pulp loss which resulted in convex shape of the hard barrier than PRMTA. When applied on the cultured cells, it was demonstrated that PRMTA and CH solutions decreased the cell metabolic activity by 9.9% and 29.4%, respectively. CH caused higher cytotoxic effects to the MDPC-23 cells as well as deeper healthy pulp tissue loss than PRMTA. However, similar sequence of healing occurred after pulpotomy with both dental materials.

Abnormal pulp calcification in primary molars after fluoride supplementation.

Forty-five caries-free primary molars from children with continuous fluoride supplementation (n = 28) after birth and from children without fluoride prophylaxis (n = 17) were investigated by light microscopy. The following results were obtained: The prophylaxis group evidenced a special form of calcification consisting of fibrodentin-like hard tissue developing intramurally in the dentin wall especially at the pulp floor and spreading irregularily into the pulp cavity by displacing the degenerating pulp tissue (n = 24). These teeth were ankylosed in the bi- and trifurcation area as well as inside the roots. This kind of hard tissue was not observed in the teeth from untreated children. Only 5 children had greater calcifications attached at the pulp wall. Nevertheless, this difference was statistically significant (p = 0.001) and indicates a relationship between fluoride prophylaxis, the special form of pulp calcification and tooth ankylosis.

Tablet fluoridation influences the calcification of primary tooth pulp.

This study was conducted to determine the influence of long-term tablet fluoridation on primary pulp calcification by light microscopy. Twenty-four caries-free primary molars (after continuous postpartally initiated 1- to 10-year tablet fluoridation) were compared to 17 primary molars of children without fluoride prophylaxis. Pulp calcification in children with tablet fluoridation was significantly more frequent and more pronounced than in untreated children (p = 0.001). Besides the known pulp stones, the prophylaxis group evidenced a special form of calcification consisting of fibrodentin-like hard tissue not observed in the untreated children. These hard tissue bodies developed "intramurally" on the pulp floor and the inside of the dental roots with an irregular extramural spread into the coronal and radicular pulp by displacement and fibrotization of the pulp tissue. Moreover, some of the teeth had more or less extensive areas of interglobular dentin. The affected teeth were ankylosed in the area of the bi- and trifurcation and on the inside of the roots and were thus infra-occluded. Although the duration of tablet fluoridation has no statistically significant influence on pulp calcification, there is a correlation between extensive pulp calcification, postnatally initiated fluoride prophylaxis and the infraocclusion of primary molars.

Dental changes in hypervitaminosis D.

Vitamin D is required for the normal development of teeth and bones. When there is excess vitamin D, systemic and dental changes may occur. This is a case report of a girl who experienced hypercalcemia secondary to excess vitamin D derived from the consumption of milk that was incorrectly fortified. The changes in the permanent dentition to date are enamel hypoplasia and focal pulp calcification. These changes correspond to the timing of the toxemia caused by hypervitaminosis D.

Pulpal obliteration related to long-term glucocorticosteroid medication.

Glucocorticosteroids (GCS) are used in the treatment of chronic autoimmune diseases and many long-term illnesses. While these drugs may be considered essential for the patient's health, adverse reactions do occur. The incidence of adverse reactions depends upon the dose level and the duration of treatment. Three case reports of patients on long-term GCS therapy are presented. Pulpal obliteration was assessed by radiographic records. In all instances, pulpal obliteration to some degree is described; however, the rate and extent of pulpal obliteration in the mature dentition seem greater than those occurring in the immature dentition. In the cases reported, the greatest dentin deposition appeared to occur on the roof of the pulp chamber, indicating that the pattern of dentin deposition by pulp tissue in GCS-treated individuals is different from that of the normal aging process.

Characterization of a system of mineralized-tissue formation by rat dental pulp cells in culture.

Pulp tissue was obtained from maxillary incisors of young adult male Wistar rats, minced and digested with 0.5% trypsin and 0.02% EGTA at 37 degrees C for 30 min. Dissociated cells were cultured with or without 10 nM dexamethasone using Eagle's minimal essential medium supplemented with 10% fetal bovine serum and 50 micrograms/ml ascorbic acid. Confluent cells were subcultured at 7 days and the medium further supplemented with beta-glycerophosphate (beta-GP). Dexamethasone in primary culture and/or secondary culture enhanced the formation of mineralized tissue while > 5 mM beta-GP was necessary for mineralization to occur. Biochemical analysis of the radiolabelled medium revealed that these cells produced type I, type I trimer and type III collagens. Analysis of [32PO4]-labelled medium, using DEAE-Sephacel ion-exchange chromatography and sodium dodecylsulphate-polyacrylamide gel electrophoresis, showed that these cells produced phosphophoryn-like protein. These results indicate that some of the rat dental pulp cells in culture express an odontoblast-like phenotype.

Pathological mineralization in a serially passaged cell line from rat pulp.

The ultrastructure of crystal formation in association with dental pulp cells isolated from rat incisor was studied in vitro. A clone, RPC-K, was obtained and incubated with Na-beta-glycerophosphate (BGP). Growing pulp cells showed low alkaline phosphatase (ALP) activity, which began to increase with cell proliferation. Pulp cells formed cell multilayers after day 14 of culture. Mineralized tissues were observed within cell multilayers on day 28 of culture. Vesicular structures were found around degenerate and necrotic cells. Some of these vesicles contained needle-like crystals. Organic structures appeared at the periphery of mineralized tissues with a post-embedding demineralization and staining method. Electron diffraction patterns of the newly formed crystals revealed a pattern consistent with hydroxyapatite (HAP). These findings suggest that the RPC-K cell line might be useful for a model system to investigate pathological mineralization.

Reaction of the dental pulp to hydroxyapatite.

The purpose of this study was to evaluate the action of hydroxyapatite (HA) (Osteogen HA Resorb, GBD Marketing Group Inc., Valley Stream, N.Y.) on the dental pulp of rats. Four upper molar pulps in 45 rats were exposed and capped with synthetic HA (Osteogen) with a stereoscopic microscope. Pulps capped with calcium hydroxide (Dycal, L.D. Caulk Co., Milford, Del.) served as controls. The cavities were filled with amalgam, and the molars on each side of the maxilla were protected by the placement of a pedodontic steel crown. Pulp inflammation and dentin repair were compared by histologic observations and computer image analysis after 7, 14, and 28 days. After 7 days a partial acute pulpitis were observed in specimens treated with Osteogen or Dycal. Reparative dentin formation along the pulp walls was also seen. After 14 days the pulpitis was more extensive in the Osteogen-treated teeth than in the control teeth. Dentin formation as measured by morphometric analysis was more pronounced in Osteogen-treated teeth. Neo-odontoblasts were observed after the use of both materials. After 28 days an acute inflammatory reaction was still evident in the Osteogen-treated group. A complete dentinal bridge was observed more frequently with Dycal than with Osteogen. Despite the putative abilities of HA to be osteoconductive, osteogenic, and dentinogenic, the results of this study indicate that it should not be used as a pulp-capping agent because of its tendency to cause scattered dystrophic calcification in the dental pulp, which could interfere with future endodontic treatment.

Root canal calcification associated with prednisone therapy: a case report.

This report details an 8-year follow-up of a patient with systemic lupus erythematosus (SLE) who was treated with up to 60 mg per day of prednisone for more than 8 years. Radiographic documentation demonstrated complete calcification of all pulp chambers and root canals during an 8-year period. During this time, the patient had been successfully treated for case type III adult onset periodontitis. Follow-up examinations recorded minimal attachment loss, and radiographs showed stable bone levels.

Non-specific induction of mineralization of incisor pulp in the rat.

Mineralized intrapulpal lesions were readily formed in the rat incisor after a single intrapulpal injection of the calcergen potassium permanganate, as well as after saline. Besides that there occurred irregular secondary dentin apposition and hard tissue overbridging at the injection site. The mechanism of topical calcinosis in relation to pulp tissue was discussed.

The clinical and histological evaluation of cresatin with calcium hydroxide on the human dental pulp.

Metacresylacetate with calcium hydroxide in a methylcellulose base produces clinically and radiographically successful pulpotomies, when performed on sound primary teeth. Under sterile conditions, with proper surgical and restorative technique, pulp tissue will heal with metacresylacetate with calcium hydroxide-methylcellulose. The dental pulp will form on osteodentin bridge and the pulp adjoining the bridge will remain histologically viable and free of inflammation. Methylcellulose with sterile distilled water does not produce as favorable a histological reaction as metacresylacetate with calcium hydroxide-methylcellulose. No dentinal bridging was in evidence and there were present in the radicular pulp varying degrees of inflammation.