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PubMed1990

Pathogenic mechanisms in pulpal disease.

The unpredictable response of the dental pulp to clinical insults is frequently encountered in the daily practice of dentistry. Even though the pulp often shows remarkable capacity for recovery, painful symptoms and pulp tissue breakdown may follow such clinical insults as caries, dental trauma, or operative dental procedures. In recent years pulp biology research has provided a deeper insight into the basic mechanisms that govern pulpal defense and repair. This communication focuses on dentin permeability to bacterial antigens and how bacterial elements may be processed and dealt with by the dentin-dental pulp complex.

Antigens, Bacterial↗
PubMed2004

Effect of dentin perfusion on the sealing ability and microtensile bond strengths of a total-etch versus an all-in-one adhesive.

OBJECTIVES: To test the null hypothesis that perfusion of dentin has no effect on the sealing or bond strength in Class V resin composite restorations using a two-step total-etch (Scotchbond 1), or a one-step self-etch (all-in-one) (Prompt L-Pop) adhesive. METHODS: Dentin permeability in Class V cavity preparations cut into extracted human third molars was measured in a fluid transport setup. Resin composites were placed using either Scotchbond 1, or Prompt L-Pop with or without dentin perfusion at 1.47 kPa. Permeability was re-measured, and the reduction in permeability was calculated as a percentage of the initial value. Additionally, microtensile bond strength (microTBS) to dentin was measured. RESULTS: Whereas the ability of Scotchbond 1 to seal dentin was significantly decreased due to dentin perfusion (p = 0.00025), that of Prompt L-Pop was not affected (p = 0.099). Scotchbond 1 produced significantly less dentinal seal than Prompt L-Pop only in the restorations carried out with perfusion (p = 0.0003), in the absence of perfusion, however, the difference was not significant (p = 0.343). Dentin perfusion significantly decreased the microTBS of Scotchbond 1 to dentin (p = 0.001). Due to excessive premature failure during sectioning, microTBS test could not be performed with Prompt L-Pop. SIGNIFICANCE: Dentinal fluid flow may have detrimental effects on the sealing ability of dental adhesives depending on the type of adhesive used. Studies aiming to rank adhesives in relation to their sealing ability in vitro should not disregard dentin perfusion.

Acid Etching, Dental↗
PubMed1991

Fluid and protein flux across the pulpodentine complex of the dog in vivo.

Dentinal fluid volume and protein concentrations were measured from cavities prepared in the dentine of dog molars. Fluid was collected under spontaneous conditions, during the application of negative pressures, and during a recovery period. The data allowed the calculation of dentine permeability as hydraulic conductances, fluid flux, protein flux, reflection coefficients and pulpal tissue pressures. In general, the protein concentration of dentinal fluid was about one-fifth that of plasma during spontaneous conditions and it fell when fluid flux was increased by the application of external negative pressures. The collection and analysis of dentinal fluid looks promising as a non-invasive method of assessing the state of the underlying pulp.

Animals↗
PubMed2004

In vivo and in vitro permeability of one-step self-etch adhesives.

Adhesive dentistry should effectively restore the peripheral seal of dentin after enamel removal. We hypothesize that non-rinsing, simplified, one-step self-etch adhesives are effective for minimizing dentin permeability after tooth preparation procedures. Crown preparations in vital human teeth were sealed with Adper Prompt, Xeno III, iBond, or One-Up Bond F. Epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. Dentin surfaces from extracted human teeth were bonded with these adhesives and connected to a fluid-transport model for permeability measurements and TEM examination. Dentinal fluid droplets were observed from adhesive surfaces in resin replicas of in vivo specimens. In vitro fluid conductance of dentin bonded with one-step self-etch adhesives was either similar to or greater than that of smear-layer-covered dentin. TEM revealed water trees within the adhesives that facilitate water movement across the polymerized, highly permeable adhesives. Both in vitro and in vivo results did not support the proposed hypothesis.

Acid Etching, Dental↗
PubMed1996

Reducing the risk of sensitivity and pulpal complications after the placement of crowns and fixed partial dentures.

Sensitivity after cementation of a crown with glass-ionomer cement is often attributed to an adverse effect on the pulp by the luting agent. Most permanent restorative materials in common use today do not tend to irritate the pulp; the main cause of pulpal damage is infection, the bacteria originating in the smear layer or deep in the dental tubules, inaccessible to caries-excavating procedures. A poorly fitting provisional crown may expose cut dentin to the oral fluids, and mechanical trauma caused by frictional heat during preparation may also damage the pulp. The following precautions are recommended during precementation procedures to reduce the risk of an inflammatory response in the pulp: (1) The provisional crown should be well fitting, covering cervical dentin but not impinging on the periodontal tissues. The permanent crown should be cemented as soon as possible. (2) The superficial smear layer should be removed and the dentinal surface should be treated with an antibacterial solution before the provisional crown is placed. (3) To decrease dentinal permeability under the provisional crown, the dentinal surface should be covered with a liner that can be easily removed before final cementation. (4) to ensure optimal mircomechanical bonding, the dentinal surface should be thoroughly cleaned, and the dentin should be kept moist until cementation. (5) The occlusion should be carefully checked before cementation of the crown.

Bacterial Infections↗
PubMedDate not supplied

Amalgam buildups: shear strength and dentin sealing properties.

The retentive strength and sealing properties of amalgam buildups were compared in vitro in three groups of specimens. All teeth were prepared with flat, nonretentive surfaces. In the first group, the amalgam buildups were retained by four self-threading Minim pins. In the second group, retention was provided by a circumferential slot prepared in the dentin just inside the DEJ. The third group utilized an adhesive resin for retention. Dentin permeability was measured as a hydraulic conductance before and after placement of the amalgam buildups and before and after thermocycling. All methods of retention sealed dentin very well even in the absence of cavity varnish. The 90 degree retentive strength was: pins, 10.3 +/- 0.9 MPa; slots, 4.1 +/- 0.5 MPa; resin, 3.1 +/- 0.8 MPa (mean +/- SEM).

Adolescent↗
PubMed1989

[Smear layer on prepared dentin].

Whenever dental tissues cut with a rotary instrument, a layer of grinding debris and organic film left of their surfaces, which is described by the term "smear layer". In this paper, we present the morphology and views for the formation of the smear layer. Additionally, we examine the influence of smear layer, on dentin permeability, infection by bacteria beneath dental restorations and on bonding capacity of adhesive dental materials. Following, detailed description of cleaning and chemical agents, used for smear layer removal from prepared dentin surfaces.

Dental Bonding↗
PubMed1990

[Use of the CO2 laser in enamel-dentin bonding procedures: experimental findings].

The objective of this study is to verify if laser (CO2) preparation of dental tissues has an effect on the quality of the seal of composite fillings. Forty-eight cavities were filled with the Scotchprep/Scotchbond 2 system, using P 50 (3M) as filling material, following the clinical protocol of the system; 40 cavities had previously been treated with a CO2 laser Sharplan 1020 (SBM). The teeth were thermocycled (240 cycles 4 degrees C/55 degrees C), then placed in a 0.5% basic fuschine solution for 48 hours after isolation of the root dentin. After inclusion and section, the penetration of the coloring agent was examined at the interface tooth-filling. This was followed by examination of the interface composite-tooth with the Scan Electronic Microscope. In order to visualize a possible alteration of the dentinal seal, 4 cavities treated with laser were placed in a 0.5% basic fuschine solution for 48 hours after isolation of the root dentin. Four reference cavities were cut with a diamond bur on a high speed handpiece. The following results were obtained: 1) the dentinal permeability of the laser-treated samples increases markedly in comparison with the reference group. 2) the filling-tooth junction of the laser-treated samples were never dye-tight (contrary to the reference samples). 3) fissures were created in the enamel and the dentin. The Scan Electron Microscopy confirms these results.

Carbon Dioxide↗
PubMed1978

[Studies of the permeability of human dentin Part I: Basic studies of constant physiological parameters and experimental variables (author's transl)].

Diffusion processes proceeding in the dentin are of fundamental scientific interest and of major importance to numerous therapeutical measures, with the permeability of dentin playing an essential role. Their exact quantitative determination is possibly in vitro only and depends upon various factors. Relevant investigative results obtained using standardized parameters and the methods employed are subjected to a critical analysis and interpreted with regard to the possibility of using them for specific comparative studies. The results reported in this paper are only indirectly applicable to clinical studies. However, they can considered a useful starting point for further studies.

Adult↗
PubMed2000

The permeability of the dentine and other tissues that are exposed at the tip of a rat incisor.

The tissues that form the incisal surface of a rat incisor include dentine, an atubular calcified tissue which lines the last-formed dentine, and calcified pulp remnants. The permeability of these tissues was investigated in vitro and in vivo using Evans blue dye. The incisal surface was prepared by etching it with acid or removing 1 mm by fracturing or with a diamond disc followed by etching. In some cases, 1.5-3.0 mm was removed to expose the soft tissue of the pulp. The dye was applied for 30 min, then longitudinal sections of the crown were cut and examined microscopically to determine the extent to which the dye had diffused into the underlying tissues. In only those teeth in which the dye had been applied direct to the pulpal soft tissue could any be detected below the exposed tooth surface. In previous experiments, it was found that both cat and human dentines were freely permeable to Evans blue when they were tested in vitro. It is concluded that the dentine and other tissues that form the incisal surface of a rat incisor are less permeable than cat or human dentine.

Acid Etching, Dental↗
PubMed2002

Update on materials used in intracoronal bleaching.

Intracoronal bleaching has emerged as a popular technique to bleach discoloured, endodontically treated anterior teeth. Although hydrogen peroxide and sodium perborate have traditionally been used in intracoronal bleaching, some concern has been expressed regarding the use of hydrogen peroxide, mainly because of the suspected "cause and effect" relationship between hydrogen peroxide and invasive cervical root resorption. Other complications associated with use of hydrogen peroxide alone or in combination with sodium perborate include increased dentine permeability, alteration in the chemical structure of dentine, and general weakening of physical properties of dental hard tissues. This has prompted researchers to look for alternative bleaching agents as effective as the traditional bleaching agents but unassociated with such complications. Some of these alternatives have been shown to be as effective as sodium perborate in lightening tooth colour under in vitro conditions and may represent a useful alternative to the traditional materials that are currently in use.

Borates↗
PubMed1989

Dentin: a dynamic substrate--a review.

The structure of dentin is unusual in that the number and size of its tubules changes as one moves from the periphery toward the pulp chamber. Near the pulp, the tubules are very close together and the water content of this deep dentin is high. Near the enamel, the tubules are far apart, occupying less than 1% of the surface area. When enamel or dentin is cut, the surface becomes covered by an adherent layer of cutting debris called the smear layer. Its composition presumably reflects the composition of the underlying dentin. It is only about 1 micron thick but its presence modifies the function of the dentin a great deal. It lowers dentin permeability and therefore can be regarded as protective. However, it masks the underlying dentin and hence interferes with attempts to bond dental materials directly to dentin. If it is removed, the dentin becomes much more permeable and fluid shifts across the open tubules can cause sensitivity in vivo. As smear layers are very acid-labile, they often dissolve in oral fluids. Several attempts have been made to replace smear layers with acid resistant structures that accomplish the same function. Smear layer structure is being studied by using both scanning electron microscopy as well as electronic particle sizing equipment. The close adaptation of dental materials to smear layers and to underlying dentin is currently an area of very active research. Removal of smear layers increases adaptation and bonding strength but may increase the incidence of pulpal inflammation if the bonding is not uniform or permanent. The dynamics of dentin are just beginning to be understood.

Dental Restoration, Permanent↗
PubMed2004

Use of the Nd:YAG laser in the treatment of Early Childhood Caries.

AIM: This was to demonstrate that traditional therapy of Early Childhood Caries (ECC) can be improved with the use of the Nd:YAG laser. METHODS: This investigation was conducted on three 3 year-old children in which the four maxillary primary incisors were affected by ECC. The teeth were treated with the Nd:YAG laser and one unrestorable tooth for each child was extracted for investigation by scanning electron microscopy. RESULTS: The laser therapy provided several clinical advantages (reduction of dentine permeability and hypersensitivity, sterilization of the lased surface, and fluoride penetration within the tooth). Good patient compliance was also achieved due to the type of appliance and materials used, absence of noise and vibration, a lack of need for local analgesia, and the reduced number of brief appointments. CONCLUSION: This approach to treatment of ECC permits teeth to be retained in the dental arch and delays the use of traditional methods to a later time when the child has reached an age sufficient for cooperation with the practitioner.

Child, Preschool↗
PubMed1976

Chelating agents: their effect on the permeability of root canal dentin.

An in vitro assessment was made of the ability of three chelating agents used in endodontics to alter the dye penetration of dentinal tubules from the root canal surface. The experiment and control for this study were within the same root. It was found that all three agents significantly reduced the dye penetration into dentin, but there was no difference among the agents in the degree of reduction of dye penetration.

Chelating Agents↗