Pulpal reactions to two experimental bonding systems for pulp capping procedures.

This study evaluated the pulpal responses induced by application of two types of bonding system to the exposed dental pulp. One consisted of the following steps: etching with neutralized EDTA, application of an experimental water-based photocuring bonding agent, and restoration with a commercially available photocuring resin composite (EDTA etching system). The other was treatment with an experimental water-based self-etching primer, application of a commercially available bonding agent, and restoration with a commercially available photocuring resin composite (self-etching system). These two systems of treatment were applied to the exposed pulp. Calcium hydroxide was used as a control for the direct pulp-capping material. The pulps in class V cavities in the anterior teeth of beagles were mechanically exposed and then filled using the etching, the self-etching, or the Ca(OH)2 system. The beagles were sacrificed on the 7th, 30th or 90th postoperative day, and pulpal responses were investigated histopathologically using light microscopy. The EDTA etching system induced severe pulp reactions at 7 days after the operation. These reactions did not completely diminish after 90 days. Reparative dentin formation was observed at day 90. The self-etching system showed moderate pulp reactions, which gradually decreased over the experimental period. Reparative dentin bridge formation was observed at day 90. No necrosis of the pulp was observed at any time. Calcium hydroxide induced both moderate and severe initial pulp reactions, with reparative dentin formation evident at day 30. Necrosis was observed in the superficial pulp. It is suggested that the EDTA etching agent caused not only pulpal damage but also re-bleeding because of rinsing and drying. The self-etching system is a promising system for direct pulp capping.

Dentin formation after corticosteroid treatment. A clinical study and an experimental study on rats.

The overall aim of this series of studies was to determine whether the extensive narrowing of the dental pulp chamber seen in dental radiographs of patients with end stage renal disease was related to the method of treatment of the renal disease. The treatments studied were immunosuppression, renal transplantation and hemodialysis. A strong correlation was found between narrowing of the dental pulp chamber and renal transplantation. In the immunosuppression group and in the renal transplantation group, the patients received immunosuppressive drugs, mainly corticosteroids and azathioprine. Significantly higher doses of corticosteroids had been given to patients showing narrowing of the dental pulp chamber than to patients without such narrowing. The total plasma clearance of the corticosteroids received was measured among transplanted patients. The total plasma clearance was lower in patients with narrowing of the dental pulp chamber than in patients without narrowing. The morphology of the corticosteroid induced dentin in premolars from five deceased patients who had received one or more renal transplants each was compared with that in extracted teeth from five healthy individuals. The results of this study showed that dentin formation after high dose corticosteroid treatment in humans seems to start with a widening of the predentin zone, followed by extensive mineralisation causing substantial reduction of the dental pulp chamber within a few years after the start of treatment. In an experimental study on rats, it was shown that intravenous administration of high doses of corticosteroids induced dentin formation along the pulp chamber walls in the molars. Energy dispersive X-ray microanalysis was used for estimation of the calcium and phosphorus content of the dentin in rat teeth. The calcium and phosphorus composition of the corticosteroid induced dentin was found to be equal to that of normal dentin in control rat molars, which might imply that the mineralisation process was not affected by the corticosteroid treatment and thus the quality of the corticosteroid induced dentin might be equal to normal dentin regarding the calcium and phosphorus composition. In a scanning microscopy study of the morphology of the corticosteroid induced dentin in rat incisors, it was found to be equal to that of normally formed dentin.

Pulp response to a novel adhesive calcium hydroxide based cement.

This study compares pulp responses to 3 formulations of calcium hydroxide, namely: a) An experimental adhesive calcium hydroxide cement containing polyacrylic acid, b) Dycal (L.D> Caulk Co, Milford, Delaware) Batch Nos 176970/176990, c) "Analar" calcium hydroxide mixed with sterile distilled water. After 28 days dentine bridges were present in 77% of teeth capped with the test material, 64% of teeth treated with Dycal and in 62% of teeth capped with calcium hydroxide and water. Inflammatory infiltrates were observed in a number of teeth remote from the bridges. Bacteria were detected in these specimens. Exposed rat molar pulp responses to an experimental adhesive calcium hydroxide cement were similar to to those observed with 2 other calcium hydroxide formulations.

Dental iatrogenesis.

In order to substantiate biocompatibility of dental materials and techniques and thereby reduce iatrogenesis, tests for pulpal and dentinal responses have been developed. These have shown that: high-speed tooth cutting techniques are superior to low-speed techniques even when both incorporate air and water coolant sprays; pressure when condensing restorative materials intensifies pulpal responses induced by the cutting procedure, and that chemically self-cured resin composites requiring the application of a matrix to enhance adaptation intensify pulpal response as compared to visible light-cured equivalents applied incrementally, fully cured throughout and not requiring the pressure of a matrix. Most cements are irritating to the pulp especially when used as luting agents and when used less than 0.5 mm from it. Conditioning agents utilising weak acids for short periods induce little irritation whilst bonding agents appear to be beneficial by providing protection from subsequently placed restorative materials. Clinicians should make every effort to minimise the development of pulpal responses and reduce iatrogenic effects.