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At least 145 records · Page 8Linked to original sources
PubMed1996

Transient effects of low-energy CO2 laser irradiation on dentinal impedance: implications for treatment of hypersensitive teeth.

This study evaluated the effect of CO2 laser irradiation on dentinal impedance by passing known cyclic potentials across dentinal wafers mounted as a window in an electrolytic cell and measuring the resulting electrical impedance. Wafers were equilibrated in 0.1 M of KCl. The wafer specimens were irradiated with a CO2 laser (12 W, 0.1 ms, energy density 1.25 J/cm2). The time for impedance equilibration after irradiation was compared with equilibration after mounting. Mounted samples required 48 h to approach equilibrium in the electrolyte. After laser irradiation, impedance of previously equilibrated samples also required 48 h to equilibrate. This, along with exponential curve fitting, confirmed that laser treatment reintroduced a transient alteration in impedance. Equilibration time after irradiation and the mounting were similar. Dentin desociation apparently caused this transient impedance. Energy dispersive X-ray analysis confirmed the disappearance of K+Cl- after irradiation. Therefore, laser irradiation may cause dentinal desociation, yielding temporary clinical relief of dentinal hypersensitivity until rehydration occurs.

Carbon Dioxide↗
PubMed1996

Relationship between endodontic preparations and human dentin permeability measured in situ.

Endodontic preparations may induce changes in the permeability of radicular dentin. The aim of this study was to analyze the variation of hydraulic conductance measured in situ after three endodontic preparations (manual K+H files, ultrasonic preparation, and manual with NaOCI and EDTA). Scanning electron microscopic analysis of the canal walls was made to permit correlations between variations of permeability and the amount of surface covered with smear layer or organic debris. There was an inverse relationship between the variations in dentin permeability and the presence of smear layer. The significance of this correlation was variable according to the techniques used. Dentin thickness was as significant a factor in influencing radicular permeability as was the smear layer. The use of EDTA induced a considerable increase in radicular permeability. The use of ultrasonics produced a similar but weaker effect.

Analysis of Variance↗
PubMed1999

The combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules.

Various methods and materials used in the treatment of dentin hypersensitivity are thought to achieve a therapeutic benefit by tubule occlusion. The aim of the present study was to evaluate the combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules. Thirty-six dentin specimens with exposed dentinal tubule orifices were used in this study. The samples were randomly divided into four groups. Groups A, B, and C were varnished by sodium fluoride, whereas group D served as a control. Then, group C was lased by 30 mJ of Nd:YAG laser, 10 pulses/s for 2 min by light painting. Three hours later, groups B and C were brushed by an electrical toothbrush for 30 min. Under SEM observation, the control group showed numerous exposed dentinal tubule orifices, and the sodium fluoride varnished specimens showed closure of exposed dentinal tubule orifices. After electrical toothbrushing, most of the sodium fluoride varnish was brushed away, except in the specimens that were irradiated by Nd:YAG laser. Over 90% of the dentinal tubule orifices were occluded by sodium fluoride varnish combined with Nd:YAG laser irradiation.

Combined Modality Therapy↗
PubMed2000

Effect of region and dentin perfusion on bond strengths of resin-modified glass ionomer cements.

OBJECTIVES: The purpose of this study was to evaluate the hypothesis that regional differences and pulpal pressure would significantly affect bond strengths of resin-modified glass ionomer cements to dentin. METHODS: Twenty-six extracted caries-free human third molars were ground to expose middle dentin and were randomly divided into two groups for bonding: no pulpal pressure and pulpal pressure of 15cm H(2)O. Fuji II LC, Vitremer, or Photac-Fil Quick were applied to the previously pre-treated surfaces and light-cured as recommended by the manufacturers. After immersion in water at 37 degrees C for 24h, the teeth were sectioned to 0.7mm thick slabs, divided into pulp horn, center, and peripheral regions according to visual criteria, and trimmed along the bonded interface for microtensile bond test to a cross-sectional area of 1mm(2). The slabs were subjected to tensile forces and the data analyzed using ANOVA and Fisher's PLSD at the 95% level of confidence. RESULTS: For Fuji II LC, bond strengths to the pulp horn regions were significantly lower than those to the other regions independent of pulpal pressure (p<0.05). On the other hand, regional bond strengths were not observed for Vitremer and Photac-fil Quick 0.05). CONCLUSIONS: Pulpal pressure had a stronger influence on bond strengths and failure modes of resin-modified glass ionomers than regional differences of the substrate.

Analysis of Variance↗
PubMed1997

Dentine permeability and dentine adhesion.

OBJECTIVES: The objectives of this paper are to review the structure of dentine as it pertains to adhesive bonding and to describe the importance of resin permeation into dentinal tubules and into spaces created between collagen fibrils by acid-etching during resin bonding. The advantages and disadvantages of separate acid-etching, priming and adhesive applications are discussed. DATA SOURCES: Although not an exhaustive review, the concepts included in the review were obtained from the dentine bonding literature. STUDY SELECTION: Attempts were made to critically evaluate what is known about dentine permeability and adhesion and what remains to be discovered. Speculations were made on a number of controversial issues that are not yet resolved. CONCLUSIONS: Acid-etching of dentine produces profound changes in the chemical composition and physical properties of the matrix which can influence the quality of resin-dentine bonds, their strength and perhaps their durability.

Acid Etching, Dental↗
PubMed1997

The dentin substrate: structure and properties related to bonding.

OBJECTIVES: Dentin is a vital, hydrated composite material with structural components and properties that vary with location. These variations are reviewed along with alterations by physiological and pathological changes that allow classification into various forms of dentin. Structural characteristics and mechanical properties are reviewed and the limitations of our understanding of structure-property relationships for normal and modified forms of dentin are discussed with respect to their impact on dentin bonding. Recent progress in methods available to study dentin and its demineralization are emphasized with their promise to increase our understanding of dentin properties and structure. DATA SOURCES: Recent microstructural studies, focusing on scanning electron microscopy, atomic force microscopy and X-ray tomographic microscopy are included. A review of fundamental studies with emphasis on microstructurally sensitive methods, and prior reviews of basic mechanical properties are included with discussion of their correlation to composition and structure. STUDY SELECTION AND CONCLUSIONS: Emphasis in this work was placed on the major structural components of the tissue, including the collagen based organic matrix and its mineral reinforcement, the distribution of these components and their microstructural organization as related to mechanical properties and response to demineralization. Little information is included on biochemical and developmental studies or on non-collagenous proteins and other organic components for which limited understanding is available with respect to their role in structure-property relations and influence on bonding. In spite of the fact that the complexity of dentin precluded a comprehensive review, it is clear that local structural variations influence properties and impact nearly all preventive and restorative dental treatments. Much more work is needed in order to understand differences between vital and non-vital dentin, and dentin from extracted teeth. Although our knowledge is rudimentary in certain areas, increasingly sophisticated methods of studying dentin should provide the necessary information to model structure-property relations, optimize dentin bonding, and improve many aspects of preventive and restorative dentistry.

Apatites↗
PubMed1998

Fibrinogen/fibrin and fibronectin in the dentin-pulp complex after cavity preparation in rat molars.

OBJECTIVE: The purpose of this study was to examine changes in distribution of fibrinogen/fibrin and fibronectin in the dentin-pulp complex after cavity preparation. STUDY DESIGN: Class V cavity preparations were prepared on maxillary first molars of 12 rats. The dentin and pulps were observed histologically and immunohistochemically for fibrinogen and fibronectin at 6 hours and 1, 2, and 3 days after the preparation. RESULTS: At 6 hours and 1 day after cavity preparation, positive staining for fibrinogen was noted in the exudative lesion and in the dentinal tubules under the cavity preparation. Fibronectin staining in the exudate showed a pattern with close similarity to the fibrinogen staining. At 3 days after cavity preparation, the irregularly shaped predentin under the cavity preparation showed strong positive staining for fibronectin. CONCLUSIONS: Fibrinogen/fibrin and fibronectin are present during the healing process of the dentin-pulp complex after cavity preparation.

Animals↗
PubMed1999

Crown cementation and pulpal health.

LITERATURE REVIEW: A direct result of the liquid continuum within the pulpo-dentine complex is the effect of restorative dentistry on the health of the dental pulp. Better understanding of the role of the complex in relation to restorative dentistry enables strategies to be devised in preserving pulp vitality. A review of the literature produced good laboratory evidence to support the prophylactic sealing of crown preparations with dentine bonding agents.

Cementation↗
PubMed1997

The dentine disc. A review of its applicability as a model for the in vitro testing of dentine hypersensitivity.

The dentine disc has been extensively used as a model for assessing potential desensitizing agents in vitro by scanning electron microscopy (SEM). Although the disc provides a readily available and reproducible test substrate, this paper addresses the problems associated with this model such as the natural variation in the dentine tubules and the resulting differences in surface morphology. At the ultrastructural level the surface of a single etched disc exhibits variations in the size, density, orientation and extent of etching of the cut dentine tubules. In the present study a precise control procedure was designed which allowed greater correlation between test and control surfaces. Two adjacent areas of the same disc were used, one as the test surface, the other the control. Two proprietary desensitizers were examined using this methodology. This study has shown that the dentine disc is a good, reliable model for in vitro screening and testing of potential desensitizing agents, providing such controls are applied.

Dentin↗
PubMed1998

Perfusing dentine with horse serum or physiologic saline: its effect on adhesion of dentine bonding agents.

Freshly prepared dentine specimens of human teeth were perfused with either horse serum or physiologic saline. After application of AllBond2, ART Bond, Syntac or an experimental dentine bonding agent called P-Bond, a composite cylinder was added and cured at the same time. After 1500 thermal cycles with constant imitation of intrapulpal pressure, the shear bond strengths were measured. Resulting shear bond strength values were analysed with Students t-test or Mann-Whitney Test. The values for AllBond2 were not significantly different. The values for ART Bond (P < 0.05) and for Syntac (P < 0.05) were significantly higher if the dentine was perfused with horse serum. For P-Bond (P < 0.001) the values were significantly higher if the dentine was perfused with physiologic saline. According to these results it does not seem to be appropriate to take a clear decision as to which of the two perfusing media investigated might be more suitable to imitate in vivo conditions.

Animals↗
PubMed2000

The effect of venting on pulpward pressure transmission and seating on crown cementation: a laboratory study.

Measurable hydraulic forces towards the pulp chamber can occur whilst cementing a crown. This study investigated the effect of crown venting and the use of two different seating forces (100 and 2. 5 N) on pulpward pressure transmission. Forty single-rooted premolar teeth were collected from patients requiring extractions for orthodontic reasons. A standardized crown preparation was made and impressions taken to construct individual base-metal alloy crowns. The teeth were divided into four groups based on the type of crown (vented or non-vented) and force used (100 or 2.5 N). The teeth mounted on a specially constructed stand and connected to a 0-104 kPa pressure transducer. The pulp chamber was perfused with saline driven by nitrogen gas at 83 kPa for up to 2 h until a steady state perfusion rate was achieved. Crowns were cemented to the teeth on a uniaxial seating device using zinc phosphate cement. Simultaneous recordings of both pressure pulse and seating discrepancies were recorded. The 40-fold increase in seating force from 2.5 to 100 N resulted in a significant increase (P<0.001) in pulpward pressure in both vented and non-vented crowns. Seating was also significantly improved for the vented crowns regardless of which force was used. Venting had no significant effect on pulpward pressure transmission. It was concluded that a significant relationship existed between seating force and pulpward pressure transmission. Venting improved crown seating but did not have a demonstrable effect on pulpward pressure transmission.

Analysis of Variance↗
PubMed2001

Changes in the pattern of horseradish peroxidase diffusion into predentin and dentin after cavity preparation in rat molars.

OBJECTIVE: The purpose of this study was to examine the process of reducing dentin permeability in adult rat molars after cavity preparation with horseradish peroxidase as a tracer. STUDY DESIGN: Class V cavities were prepared on the upper first molars of 18 rats. Horseradish peroxidase was injected into the vascular system at intervals of 3 hours and 3, 5, 7, 10, and 14 days after cavity preparation, and frozen sections were processed by the diaminobenzidine procedure. RESULTS: Horseradish peroxidase reaction products were noted in the dentinal tubules immediately beneath the cavity up until 14 days after cavity preparation. An abrupt stoppage of reactive products caused by impermeable junctional zone formation at the interface of the primary dentin and reparative dentin was observed at 14 days after cavity preparation. CONCLUSION: Reparative dentin formation and subsequent impermeable junctional zone formation participate in the reduction of dentin permeability after cavity preparation.

Animals↗
PubMed2002

Invasion of dentinal tubules by oral bacteria.

Bacterial invasion of dentinal tubules commonly occurs when dentin is exposed following a breach in the integrity of the overlying enamel or cementum. Bacterial products diffuse through the dentinal tubule toward the pulp and evoke inflammatory changes in the pulpo-dentin complex. These may eliminate the bacterial insult and block the route of infection. Unchecked, invasion results in pulpitis and pulp necrosis, infection of the root canal system, and periapical disease. While several hundred bacterial species are known to inhabit the oral cavity, a relatively small and select group of bacteria is involved in the invasion of dentinal tubules and subsequent infection of the root canal space. Gram-positive organisms dominate the tubule microflora in both carious and non-carious dentin. The relatively high numbers of obligate anaerobes present-such as Eubacterium spp., Propionibacterium spp., Bifidobacterium spp., Peptostreptococcus micros, and Veillonella spp.-suggest that the environment favors growth of these bacteria. Gram-negative obligate anaerobic rods, e.g., Porphyromonas spp., are less frequently recovered. Streptococci are among the most commonly identified bacteria that invade dentin. Recent evidence suggests that streptococci may recognize components present within dentinal tubules, such as collagen type I, which stimulate bacterial adhesion and intra-tubular growth. Specific interactions of other oral bacteria with invading streptococci may then facilitate the invasion of dentin by select bacterial groupings. An understanding the mechanisms involved in dentinal tubule invasion by bacteria should allow for the development of new control strategies, such as inhibitory compounds incorporated into oral health care products or dental materials, which would assist in the practice of endodontics.

Animals↗
PubMed1997

Vital tooth bleaching: sensitivity and pulpal considerations.

For some patients, sensitivity and discomfort follow vital tooth bleaching. Clinical observations, however, suggest these are reversible episodes with no irreversible long-term effects. Using milder peroxide formulations or gels diminishes postoperative discomfort. The author recommends careful treatment when patients have large restorations, cervical erosion or enamel cracks. Fluoride treatment, sealing restorations and premedication may lessen discomfort.

Animals↗
PubMed2004

In vivo versus in vitro microtensile bond strength of axial versus gingival cavity preparation walls in Class II resin-based composite restorations.

BACKGROUND: Gingival margins in Class II composite restorations are a site of frequent failure. The purpose of the authors' study was to compare the microtensile dentin bond strength of gingival and axial restored cavity preparation walls of Class II composite restorations under in vivo and in vitro conditions. METHODS: After obtaining informed consent, the authors placed Class II resin-based composite restorations in 14 premolar teeth from five patients, under in vivo or in vitro conditions. The teeth were sectioned to obtain rectangular specimens from axial and gingival walls with a surface area of approximately 0.5 square millimeter. The authors tested 85 microtensile adhesive samples from the 14 teeth on a testing instrument (Universal Instron, Model 125, Instron, Canton, Mass.) until failure. RESULTS: The mean (+/- standard deviation) mircotensile dentin bond strengths in mega-pascals were as follows: in vivo axial, 36.5 (14.9); in vivo gingival, 17.6 (11.6); in vitro axial, 49.5 (13.9); in vitro gingival, 34.0 (13.1). A two-way analysis of variance found a statistically significant difference between in vitro and in vivo conditions and between the axial and gingival walls (P < or = .001). Eighty-eight percent of the fractured samples involved the adhesive layer as observed under scanning electron microscopy up to x2,500. Seventeen of the gingival samples and two of the axial samples debonded during the preparation phase and could not be tested. CONCLUSION: The dentinal microtensile strength of adhesive/resin-based composite bonded to the gingival wall was significantly weaker than the bond to the axial wall, and in vivo conditions produced significantly weaker bond strengths than did in vitro conditions. CLINICAL IMPLICATIONS: The dentinal adhesive bond of resin-based composite to gingival walls is significantly weaker and thus more subject to failure than the bond to axial walls. In vitro bond strength studies may overestimate the bond strength of adhesives in in vivo applications.

Adolescent↗
PubMed2006

Managing dentin hypersensitivity.

BACKGROUND: The objective of this review is to inform practitioners about dentin hypersensitivity (DH) and its management. This clinical information is described in the context of the underlying biology. TYPES OF STUDIES REVIEWED: The authors used MEDLINE to find relevant English-language literature published in the period 1999 to 2005. They used combinations of the search terms "dentin*," "tooth," "teeth," "hypersensit*," "desensiti*" and "desensitiz*." They read abstracts and then full articles to identify studies describing etiology, prevalence, clinical features, controlled clinical trials of treatments and relevant laboratory research on mechanisms of action. RESULTS: The prevalence of DH varies widely, depending on the mode of investigation. Potassium-containing toothpastes are the most widely used at-home treatments. Most in-office treatments employ some form of "barrier," either a topical solution or gel or an adhesive restorative material. The reported efficacy of these treatments varies, with some having no better efficacy than the control treatments. Possible reasons for this variability are discussed. A flowchart summarizes the various treatment strategies. CLINICAL IMPLICATIONS: DH is diagnosed after elimination of other possible causes of the pain. Desensitizing treatment should be delivered systematically, beginning with prevention and at-home treatments. The latter may be supplemented with in-office modalities.

Adhesives↗