EFFECT OF RESTORATIIVE MATERIIALS ON THE DENTAL

PULP

By:dr.heidary

The pulp undergoes histopathological changes in response to irritation or destruction of dentin Pulp injury may result from anoxious stimuli due to several factors: Biological → dental cariesPhysical → restorative procedureChemical → restorative material

CYTOTOXICITY AND BIOCOMPATIBILITY OF DIRECTAND INDIRECT PULP CAPPING MATERIALSCalcium hydroxide products are the best choice for conservative treatment of the pulp due to their therapeutic and biological potential and the property of stimulating the formation of sclerotic and reparative dentin as well as protecting the pulp against thermal stimuli.

CYTOTOXICITY AND BIOCOMPATIBILITY OF DIRECTAND INDIRECT PULP CAPPING MATERIALSMonomers present in resin composites and adhesive systems ( BISGMA, UDMA, TEGDMA, HEMA) have been shown to have cytotoxic effects in direct contact with fibroblasts and may be leached during the polymerization when the conversion degree is not fully reached.

CYTOTOXICITY AND BIOCOMPATIBILITY OF DIRECTAND INDIRECT PULP CAPPING MATERIALSdirect pulp capping with adhesive systems produces different degrees of pulp inflammation, even without bacterial presence . Some studies support the idea that when hermetic seal of cavity is obtained, the dentin pulp complex protection materials are unnecessary and they not influence the pulp repair, but hermetic seal of the restoration is difficult to be obtained

CYTOTOXICITY AND BIOCOMPATIBILITY OF DIRECTAND INDIRECT PULP CAPPING MATERIALS RMGICs are more cytotoxic to the pulp cells than conventional GICs due to the presence of unpolymerized monomers, and should not be applied directly to the pulp tissue

RELEASE OF SUBSTANCE Bis-GMA Bis-EMA UDMA TEGDMA EGDMA Methylmethacrylate (MMA) Filler particles (silicon, boron, sodium and barium) Formaldehyde : released into water under certain

circumstances; It is very likely generated by an oxidation of unsatured methacrylate groups

Bisphenol A (BPA): was found in the extract of one pit and fissure sealant and in saliva in contact with resin-based composite. Minute amounts of BPA were detected after placement of UDMA-based and Bis-GMA based composite fillings.

Fluoride

SISTEMIC TOXICITY Estrogenicity Administered intragastrically daily to female mouse display 54.5% reduction in the number of pregnancies vs 100% in control mice

LOCAL TOXICITY AND TISSUE COMPATIBILITY

CytotoxicityInfluence on cell metabolismAntimicrobial propertiesPulp reactionsReactions of gingival and oral mucosa

MECHANISMS OF CYTOTOXICITYUnbound free monomers released by dental resins during polymerization.

Approximately 15–50% of the methacrylic groups remain unreacted.

CYTOTOXICITY

Citotoxicity depends also on: Degree of polymerization

Basic chemistry of the resin matrix (methacrylate-based materials are more toxic)

Filler content

INFLUENCE ON CELL METABOLISM Composite resin /monomers may interfere with

cell metabolism at nonlethal concentrations

INFLUENCE ON CELL METABOLISM

The intracellular level of reactive oxygen species ROS ( H2O2 , superoxide anion , OH radical ) increased after exposure to HEMA, TEGDMA, or composites resin.

Camphorquinone , after irradiation with blue light, directly increased intracellular and extracellular ROS concentration → DNA damage via oxidation of DNA bases

INFLUENCE ON CELL METABOLISM

Methacrylates may interfere with cellular cholesterol and phospholipids and thus alter membrane-related functions.

ANTIMICROBIAL PROPERTIESResin-based composite hasn’t real antimicrobial activity, many studies show in fact these types behaviour:

Resin-based composites and luting composites increase the growth of Streptococcus Mutans

TEGDMA and EGDMA promote bacterial proliferation of two cariogenic species: Streptococcus Sobrinus . Lactobacillus Acidophilus Then composite’s matrix helps adhesion of bacterial microorganisms

PULP REACTIONS Comparatively few studies have addressed

the effect of resin-based composites or adhesives on the pulp in deep cavities.

Small resin particles derived from dentin adhesives were documented in dentin tubules and in pulp, this particles were surrounded by macrophages, a situation indicative of a foreign body or inflammatory reaction.

PULP REACTIONS Thermal effects on the pulp: an increase of 5,5° C of

the temperature in the pulp will cause irreversible pulpar demage in 15% of all cases

Postoperative sensitivity → the possible causes can be:

trauma caused by preparation microleakage with bacterial penetration polymerization shrinkage deformation of the restoration under stress

Sixty days after the capping procedure the tooth was extracted and processed for histological evaluation of the pulp tissue. Note the presence of bonding agent (BA) on the pulp exposure site and inside of the connective tissue (BA – arrow). Intense chronic inflammatoty reaction mediated by macrophages and a number of dilatedand congested blood vessles (BV) is observed

Pulp exposure capped with an adhesive system.Note that no hard tissue barrier was formed 60 days afterthe pulp therapy

The change in the chemical structure of the composite and the variation in the ratio of filler and monomer have a significant effect on the element release and cytotoxicity level of the materials. the flowable materials of the traditional composites were more cytotoxic than their standards.

NEEDLE ASPIRATIONNeedle(18-gauge) aspiration may be described as

the use of suction to remove fluids from a cavity or space

Aspirated samples may be used for microbial isolation

Clinical advantages of needle aspiration over I&D include:

.1reduced scarring

.2evaluation of volume and character of the aspirate

.3use of the aspirate for culture and sensitivity testing .4 the lack of postoperative drain removal

THANKS JAMEI