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PubMed2005

Hardness and Young's modulus of transparent dentin associated with aging and carious disease.

This study investigated the changes in hardness and Young's modulus of the transparent layer of dentin associated with aging and the carious process. Eighteen extracted human molars with or without coronal caries were used in this study. The normal teeth were divided into two groups by age, and the carious teeth were divided into two groups of active or arrested caries. After polishing the specimens parallel to the long axis of the tooth, both hardness and Young's modulus were measured using a nanoindentation tester. The hardness and Young's modulus of the transparent layer in aged dentin were higher than the other portions of aged dentin. The transparent layer under carious lesions had a significantly lower hardness than the underlying normal dentin, whereas its Young's modulus was not significantly reduced. The hardness and Young's modulus of the transparent layer in active carious lesions were lower than those in arrested carious lesions.

Aging↗
PubMedDate not supplied

Evaluation of pumice, fissure enameloplasty and air abrasion on sealant microleakage.

PURPOSE: The purpose of this in vitro study was to evaluate microleakage of pit and fissure sealants after using three different pit and fissure preparation techniques: (1) traditional pumice prophylaxis and acid etching, (2) fissure enameloplasty and acid etching and (3) air abrasion and acid etching. METHODS: Sixty extracted third molars with no clinical evidence of caries were randomly divided into 3 groups of 20 each. Teeth were prepared using 1 of 3 occlusal surface treatments prior to placement of Delton opaque light-cured sealant. The teeth were thermocycled between 5 +/- 2 degrees C and 55 +/- 2 degrees C for 500 cycles with a dwell time of 30 seconds and then stored in 0.9% normal saline. All teeth were sealed apically and coated within 1.5 mm of the sealant margin with two layers of nail varnish. The teeth were immersed in a 1% solution of methylene blue for 24 hours to allow dye penetration into possible gaps between enamel and sealant. Three buccolingual cuts parallel to the long axis of the tooth were made yielding 4 sections and 6 surfaces per tooth for analysis. The surfaces were scored 0 to 3 for extent of microleakage using a binocular microscope at 25X magnification. RESULTS: Kruskal-Wallis and t tests revealed no significant difference in microleakage between the 3 fissure preparation methods prior to sealant placement. CONCLUSIONS: Neither air abrasion nor enameloplasty followed by acid etching produced significantly less microleakage than the traditional pumice prophylaxis with acid etching technique.

Acid Etching, Dental↗
PubMed2004

Effect of acid etching time and technique on interfacial characteristics of the adhesive-dentin bond using differential staining.

Dentin bonding using the total-etch method has been claimed to be technique-sensitive. The aim of this study is to examine the effect of acid-etch variations on the dentin demineralization and interfacial structure of the adhesive-dentin bond using a differential staining technique. Single Bond adhesive with 35% phosphoric acid gel was used. The occlusal one-third of the crown was removed from 60 extracted, unerupted human third molars. Smear layers were created by abrading the dentin with 600 grit SiC under water for 30 s. The prepared teeth were randomly assigned to four groups according to etching time (Group 1, 10 s; Group 2, 15 s; Group 3, 30 s; Group 4, 60 s). In each group, the etching gel was: (i) applied and spread to the dentin surface and left to stand undisturbed; (ii) applied and gently agitated during etching; (iii) applied without using dispensing tips for the syringe and left for the same period as above. After rinsing, the etched dentin was then treated with the adhesive per manufacturers' instructions. 3-5 micro m thin sections of the adhesive/dentin (a/d) interface were cut with a microtome and stained with Goldner's trichrome. Stained, thin sections from each prepared tooth were imaged with light microscopy. The depth and extent of dentin demineralization, and the a/d interdiffusion zone were clearly visible by this differential staining microtechnique. The thickness of the interdiffusion zone increased as a function of etching time. However, the etchant gel application methods have a significant influence on dentin demineralization. Although agitating acid gel facilitates the penetration and etching into dentin, it should not be recommended, especially for longer etching time. These results indicated that the etching technique has a large effect on the profile of both dentin demineralization and interfacial structure.

Acid Etching, Dental↗
PubMed2002

Clinical evaluation of the role of glutardialdehyde in a one-bottle adhesive.

PURPOSE: To evaluate clinically whether the addition of glutardialdehyde to the one-bottle enamel-dentin adhesive Gluma Comfort Bond (GCB) has a desensitizing function, as insinuated by the brand name Gluma Comfort Bond+Desensitizer (GCB+D). MATERIALS AND METHODS: Two pain studies following identical protocols were conducted in Abu Dhabi (A) and Bologna (B). Each of the 60 and 59 patients selected, respectively, had two sensitive cervical tooth sites, characterized by a score three or higher on a five-step pain scale: 1 (no), 2 (slight), 3 (mild), 4 (severe), 5 (very severe) discomfort upon application of a 2-second cold air stimulus. The buccal sensitive sites treated in A were generally small, in B larger and in most cases extending into the proximal tooth area. The patients indicated their discomfort level according to the pain scale prior to and immediately after topical application of GCB and GCB+D, respectively, and then at recalls after 1 week, 1 (A) or 3 (B) months, and 6 months. The data was statistically analyzed by chi2-tests (P < 0.05). RESULTS: With the cumulative scores 1 and 2, the following percentage success rates were found for GCB/GCB+D. A: postoperatively 93/98, 1 week and 1 month 98/98, and at 6 months 92/100. In B, the respective decrease in sensitivity was uniformly 43/100 throughout the entire evaluation period, postoperatively through 6 months. The 33 teeth (57%) of GCB with scores 3 and 4 in the B-study received a rescue treatment with Gluma Desensitizer immediately after the 1 week recall. This regimen reduced the sensitivity instantaneously to scores 1 and 2 until the end of the evaluation after 6 months. In the A-study, GCB+D was significantly more effective than GCB after 1 week, 1 month, and 6 months, in the B-study at all recall sessions. It is hypothesized that a thin film of adhesive applied to a sensitive area may not polymerize and seal the dentin surface adequately due to oxygen inhibition. In particular, proximal sensitive tooth sites with poor access for adhesive application are suspected to remain inadequately sealed with a polymer film and thus sensitive. In this latter case however, glutardialdehyde as a component of the adhesive compound will result in coagulation of peripheral tubular liquid protein and thus desensitization, due to hampering of the liquid shift across the tubules upon excitation of a cold stimulus. In conclusion, glutardialdehyde played an active and effective role as a desensitizing agent, when added to the ethanol-water based one-bottle adhesive Gluma Comfort Bond.

Adult↗
PubMed1990

["Push-pull" perfusion technic, a new approach applied to the study of transdentinal fluid].

The flux through the dentin tubuli is at the origin of the hydrodynamic theory of tooth sensitivity. After a review of the various in vivo techniques reported in the literature, this study describes an original method of dentin perfusion--so called "push-pull" and specific to this topic. With this technique, the authors have demonstrated the kinetics of this flux, as well as the effect of some factors (age, colchicine, ouabain), on transdentinal fluid exchanges. The analysis of all these results suggests that a combination of active and passive movements could be at the origin of this flux, the temporary inhibition of which could present major advantages in current Periodontics practice.

Age Factors↗
PubMed1997

Controlling dentine penetration in computer microleakage tracer mapping.

OBJECTIVES: Microleakage tracer penetration tests in dentine with simple sectioning are often confounded by dentine tubule penetration into the interface, leaching of water soluble tracers on wet sectioning, lack of standardized cavity dimensions affecting stresses, inadequate sectioning missing important tracer regions and airlocks obstructing tracer entry. The present aim was to create high resolution maps of stained interfaces without these confounding factors. METHODS: Ten intact extracted permanent upper central incisors were horizontally sectioned through the upper root, one third of the root length from the mid-buccal enamel limit. A dentine-bonded resin composite (Scotchbond MP, Z100, 3M) restoration was placed in a cylindrical cavity milled centrally in the root face of the coronal portion of five teeth. Tubules were angled at a mean of 12.5 +/- 4.8 degrees to the root face, and travelled approximately radially from the interface, such that tubule penetration was directed sufficiently radially outward to be distinguished from vertical interface penetration. Waterfast silver nitrate staining was applied with initial vacuum at 30 mmHg. A precision grinding machine serially removed approximately 100 microns increments of the tooth until no tracer remained, and computer image analysis data for the 18 revealed surfaces were used to construct detailed interface tracer maps. RESULTS: Control specimen tubule penetration was directed sufficiently radially outward to permit tubule penetration to be isolated from vertical interface penetration in test specimens, and ignored. Interface penetration ranged from approximately 0.3 to 1.6 mm in depth, and 0.90 to 5.09 mm2 in area. CONCLUSIONS: This method provided quantitative standardized high resolution mapping of interface tracer penetration, unconfounded by dentine penetration. None of the interfaces was fully sealed.

Coloring Agents↗
PubMed1991

[Investigations of centrifugal penetration of the tooth root hard substances by hydrogen peroxide].

After application of hydrogen peroxide into the root canal of extracted teeth of patients between the ages of 18 and 30 years the antiseptic could be detected on the root surface by means of iodometry and in tooth cross sections in dentine and cementum by means of staining reaction (benzidine-peroxidase solution). Out of the root canals which were apically not passable and coronally closed the first traces of the instilled 5% hydrogen peroxide appeared after 14 min 45 sec on the root surface. In the dentine a mean penetration depth of hydrogen peroxide up to 1.28 mm (apical root area), 1.45 mm (middle root third) and 1.95 mm (coronal root area) could be measured. Best results were obtained after rinsing/suction treatment of the root canal, especially in combination with low-frequency ultrasound.

Adolescent↗
PubMed2004

An ultrastructural analysis of the prototype single-step adhesive applied on enamel and dentin surfaces.

A new type of self-etching agent, the single-step adhesive, was developed. The purpose of this study was to investigate the difference in the ultrastructural features of enamel and dentin surfaces following application of the prototype single-step adhesive (EXM618, 3M, MN, USA). Extracted caries-free human premolars were used in this study. Occlusal enamels of teeth--to be used as cut surface specimens--were removed perpendicular to the long axis of the specimens. The mesial and distal surfaces of these teeth, on the other hand, were used as uncut surface specimens in the test. In addition, Mega Bond (Kuraray Medical Inc., Tokyo, Japan) and Xeno CFII Bond (Dentsply Sankin, Tokyo, Japan) were used as controls. After covering half of the tooth surfaces with nail varnish (for control), the other half of each surface was treated with one of the three test adhesives--EXM618, Mega Bond, or Xeno CFII Bond--according to the manufacturer's recommendations. Conditioned enamel and dentin surfaces (i.e., decalcified depth and rugged surface) were observed with a scanning confocal laser microscope (SCLM 1100, Olympus, Tokyo, Japan; henceforth abbreviated as SCLM). Based on the findings of this study, the prototype single-step adhesive EXM618 appears to be suitable for use in dental clinics.

Acid Etching, Dental↗
PubMed2003

Pulpal response to Er:YAG laser drilling of dentine in healthy human third molars.

BACKGROUND AND OBJECTIVES: Maintenance of pulpal health is a critical prerequisite for successful application of light amplification by stimulated emission of radiations (lasers) in the hard tissue management of vital teeth. The purpose of this study was to investigate the short- and long-term pulpal effects to cavity-preparations in healthy human teeth using erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser. MATERIALS AND METHODS: A total of seven healthy third molars that were to be removed due to space-problem were used. Following the laser excavation, the cavities in dentine were closed temporarily and the teeth were extracted after 7 days (n = 5) and 3 months (n = 2) post-operation. The specimens were fixed, decalcified, subdivided, and processed for light and transmission electron microscopy. RESULTS: In the short-term group, four of the five laser-drilled teeth did not reveal any pathological changes in the pulp-dentine complex. One tooth showed mild disruption of odontoblasts (OB) and vascular dilatation subjacent to the deepest point of the cavity-preparation with a remaining dentine thickness (RDT) of less than 80 microm. The two teeth under long-term observation revealed distinct apposition of tertiary dentine (TD), lined predominantly with cuboidal cells on its pulpal aspect. CONCLUSIONS: These results would allow a conclusion to be drawn that the Er:YAG laser under investigation is a pulp preserving hard-tissue drilling tool when used with the specific energy settings and emitting radiation at a wavelength of 2.94 microm.

Dental Pulp↗
PubMed2003

Water treeing--a potential mechanism for degradation of dentin adhesives.

PURPOSE: To test the hypothesis that water channels are present along the adhesive-dentin interface that can be detected using transmission electron microscopy examination of tracer penetration. MATERIALS AND METHODS: Different total-etch adhesives (Single Bond, Excite, and PQ1) and self-etch adhesives (Prompt L-Pop, Reactmer Bond, and an experimental self-etch adhesive) were bonded to dentin and enamel. Bonded resin-tooth slabs were immersed in 50 wt% conventional silver nitrate or 50 wt% basic, ammoniacal silver nitrate for 24 hours, exposed to a photodeveloping solution, and prepared for transmission electron microscopy. RESULTS: With both types of silver nitrate, all adhesives exhibited nanoleakage within hybrid layers. In addition, water trees in the form of interconnecting, dendritic silver deposits were seen along the surface of the hybrid layers that extended perpendicularly into the adhesive layers. With ammoniacal silver nitrate, additional isolated, unconnected silver grains were observed within the adhesives.

Acid Etching, Dental↗
PubMed1994

Effect of dentine on release of TEGDMA from resin composite in vitro.

Triethylene glycol dimethacrylate (TEGDMA) is a component of some resin composites which contributes to their cytotoxicity. The presence of dentine between resin composite and test cells reduces the cytotoxicity in vitro. To determine why dentine has this protective effect, the diffusion of TEGDMA from a composite resin through dentine to the pulp space was compared with release directly into aqueous solution in vitro. Both release rate and total cumulative release of TEGDMA for the two groups, at times up to 100 days, were determined using reversed-phase HPLC. Release rate directly into water was highest in the minutes immediately after immersion and declined thereafter. However, in the tooth model, using an equivalent mass and surface area of composite resin, no TEGDMA was detectable in the pulp space until 43 min after restoration placement. The rate of diffusion through dentine from that time until day 1 was less than 1% of the highest (initial) direct release rate. The rate declined thereafter. It is relevant, however, that by day 3 the total cumulative release of TEGDMA through dentine was 60% of the direct release. Dentine therefore appears to exert its protective effect principally by retarding or 'damping' the initial high release of TEGDMA to a substantial degree.

Bisphenol A-Glycidyl Methacrylate↗
PubMedDate not supplied

[Focus on the smear layer in 1990].

The smear layer is a debris-ladden layer, adhering firmly to the hard tissues of the tooth. It plays a major role in the different adhesive systems. An update of the recent knowledge on smear layer will be done in this article. When the carious lesion is removed, a microscopic debris-ladden layer forms at the level on the enamel and the dentine. This layer of materials is extremely adherent to the dental structure, and will come in between the hard dental tissues and the filling materials. In this article different studies were reviewed on the formation, structure and physiology of the smear layer. Consequences of this smear layer's removal on the pulp are discussed. A small study of different adhesive systems is conducted.

Adhesives↗
PubMed2004

Effects of application techniques and fissure types on the in vitro performance of two fissure sealants.

PURPOSE: To evaluate the effect of two materials, modified applications, moisture contamination and fissure types on the microleakage and penetration ability of fissure sealants. METHODS: 140 extracted human molar teeth were randomly assigned to 14 groups. The three following factors were tested: 1) two sealing materials (Concise and Tetric Flow), 2) four modified applications (cleaning with an air polishing device, etching with a vibration system, the use of drying agent and sealant application with a vibration system), 3) the procedures performed under two conditions (at ambient room condition and in a humidity chamber). Each tooth was subjected to thermal cycling (5000 cycles at 5-55 degrees C) and dye immersion (5% Methylene blue for 24 hours). After sectioning, microleakage, penetration ability and fissure type were examined. Multiple regression analyses were used for statistical analysis. RESULTS: The type of sealing materials and the modified applications were significantly associated with microleakage (P<0.001). The significant impacts on penetration ability were the fissure type, material and mode of application (P<0.004). CLINICAL SIGNIFICANCE: Concise showed significantly better performance than Tetric Flow. The non-invasive cleaning method with an air polishing system and the use of drying agent improved the quality of sealants. The greatest influence on penetration ability was the fissure type.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2002

Effects of a potassium nitrate mouthwash on dentinal tubules--a SEM analysis using the dentine disc model.

The concept of tubular occlusion as a method of dentine desensitisation is a logical conclusion from the hydrodynamic hypothesis put forth by Brannström. The aim of this study was therefore to investigate qualitatively by SEM whether a 3% potassium nitrate/0.2% sodium fluoride mouthwash occluded tubule orifices, and by x-ray microanalysis, to characterise the nature of the deposits if any, following application. Following the 'dentine disc model' methodology 1mm thick tooth sections from unerupted molars were obtained. These were treated with the test and control mouthwashes and subjected to scanning electron microscopy. If any deposits were seen, they were to be subjected to elemental analysis using the energy dispersive x-ray analyser. Examination of all the dentine disc surfaces, treated by water (control), active and control mouthwashes demonstrated that none of the treatments, at any of the time intervals, had any visible effect on the dentinal tubule orifices i.e. there was no dentinal tubular occlusion seen. The results suggest that potassium nitrate does not reduce dentinal hypersensitivity, at least by tubule occlusion. This could mean that there is a different mechanism of action, which could not be detected by this in vitro model.

Dentin↗
PubMed2005

Evaluation of the interface between one-bottle adhesive systems and dentin by Goldner's trichrome.

PURPOSE: To evaluate the hybrid layers in interfaces between dentin and six contemporary one-bottle adhesive systems using a nondestructive differential staining micro-technique. METHODS: The adhesive systems used in this study were divided to three groups based on hydrophilic/hydrophobic component ratios (i.e. ability to dissolve in water), from highest to lowest as follows: Group 1 (Dentastic UNO.DUO, PermaQuick PQ1) > Group 2 (One-Step, Primer&Bond NT) > Group 3 (Optibond Solo, Single Bond). The occlusal third of the crown was removed from 36 extracted, unerupted human 3rd molars. Smear layers were created by abrading the dentin with 600 grit SiC under water. The exposed dentin was treated with one of the adhesive systems per manufacturer's instructions. After 24 hours in water, 3-5 microm thin sections of the adhesive/dentin (adhesive/dentin ) interface were cut with a microtome and stained with Goldner's trichrome. Stained thin sections from each prepared tooth were imaged with light microscopy. RESULTS: The thickness and color difference of adhesive/dentin interfaces among these one-bottle adhesive systems were clearly visualized. The width of the hybrid layers varied, ranged from 4.1-9.2 microm for six adhesive systems. The color differences in the stained sections are reflected to the extent and degree to which the adhesive envelops the exposed collagen. Among these six bonding systems, resin encapsulation of collagen varied from highest to lowest as follows: Group 1 (UNO, PQ1) > Group 2 (OS, PBNT) > Group 3 (OP, SB). The differences in collagen encapsulation are dependent on the adhesive composition, or the ability to tolerate water during the infiltration of the wet demineralized matrix.

Azo Compounds↗
PubMed1991

Permselectivity of sound and carious human dental enamel as measured by membrane potential.

A microwell technique was used for determination of the permselectivities of sound and carious enamel in the same slice of tooth. The permselectivity determination was accomplished by drilling microwells in the enamel and filling them with a simulated plaque fluid containing lactate, carbonate, and inorganic ions at concentrations similar to those in resting plaque fluid, but with different concentrations of KCl. The electrical potentials developed across the enamel membrane were measured with microreference electrodes placed in the wells or in the solution outside the tooth. The results showed that the membrane potential was a function of the composition of the solutions separated by the enamel membrane and was independent of the composition of the solutions in the adjacent wells. The enamel was found to be cation-permselective, and sound enamel was more permselective than carious enamel. The flux rate of K+ was estimated from the change in the K+ concentration of the well solution as a function of time. The flux rate and the membrane potential data were used in the Nernst-Planck Flux Equation for calculation of the diffusion coefficient of K+ through enamel. The results indicate that the permselectivity of enamel can greatly influence the diffusion of ions through enamel membranes.

Carbonic Acid↗
PubMed1992

Demineralization and remineralization evaluation techniques.

This paper compares the experimental techniques utilized to assess the de- or remineralization of enamel or dentin in intra-oral studies. In in situ studies, it is important for one to know how much mineral has been lost or gained, and where the loss or gain occurred. The main emphasis in this paper is on techniques suitable for direct or indirect mineral quantification. The measuring techniques considered are microradiography, iodine absorptiometry, various microhardness tests, polarized light, light-scattering, iodide permeability, and wet chemical analysis. The various techniques are compared concerning suitability for the determination of mineral content in vol% (or wt%), mineral changes in vol% micron (or kg.m-2), and mineral distributions. Furthermore, sample preparation, the importance of protein penetration, nominal mineral loss range, the estimated mineral loss threshold, and the applicability to dentin are compared and considered. It is concluded that, although more than ten techniques are available for the measurement of changes after de- or remineralization in situ, transverse microradiography is the most practical technique for the direct and quantitative measurement of mineral content, mineral changes, and mineral distributions. Cross-sectional microhardness testing and light-scattering are also practical indirect techniques for quantitative mineral loss (or gain) determination in intra-oral studies.

Dental Enamel↗
PubMedDate not supplied

Variables contributing to the quality of fissure sealants used by general dental practitioners.

This study investigated the factors that could influence microleakage, penetration ability and the formation of resin tags of different sealants used in routine oral health care. One hundred and two caries-free extracted molars were divided into 34 groups of three teeth each. A questionnaire and three teeth were submitted to 34 dentists participating in the study. They completed the questionnaire anonymously based on their own clinical procedures. The teeth were then treated, corresponding to the questionnaires. The types of sealants were categorized into three groups: classical sealant, flowable composite and flowable compomer. The molars were thermocycled in water (5,000 cycles between 5 degrees C and 55 degrees C), then stained with 5% methylene blue for 24 hours. Each tooth was then sectioned longitudinally at three sites. Fissure type, microleakage and penetration ability of the sealants was evaluated with a computer-linked light microscope (25x magnification). Formation of resin tags at the enamel-sealant interfaces was examined using SEM. Variables thought to influence performance of the sealants were analyzed by multiple regression analyses. Classical sealants showed significantly lower microleakage than flowable composites and flowable compomers. Conventional etching with phosphoric acid was critical for sealant success. Agitating the etchant could improve the quality of sealing by decreasing microleakage significantly. In addition, the fissure types had a significant effect on the penetration ability of sealants.

Acid Etching, Dental↗