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PubMed2002

Root canal filling with calcium hydroxide using different techniques.

Several different techniques for placing calcium hydroxide into root canals have been proposed, such as amalgam carriers, vertical pluggers, McSpadden compactors, Lentulo drills, files and special syringes. Because correct filling of the root canal is necessary for calcium hydroxide paste to act effectively, the aim of this research was to study different techniques of root canal filling with calcium hydroxide pastes in dog teeth. The placement of calcium hydroxide with a file, absorbent paper points and vertical pluggers presented the lowest number of empty spaces in the three thirds of the root canal, followed by the Lentulo drill and the McSpadden compactor.

Animals↗
PubMedDate not supplied

In vitro surface analysis of active and arrested dentinal caries using a pH-imaging microscope.

This in vitro study evaluated the pH value of active and arrested caries lesions in deep dentinal caries using a pH-imaging microscope (SCHEM-100, HORIBA Ltd, Kyoto, Japan). Buccal-lingual cut sections of extracted human teeth that had either active or arrested dentinal caries lesions were placed on the pH-imaging sensor of the microscope. The pH values were compared statistically by one-way ANOVA and Fisher's PLSD test (p<0.05). In addition, both types of caries lesions were compared with a caries detector solution for this pH-imaging characterization. For both active and arrested lesions in dentin, the lowest pH values in the caries lesions (range from 5.3 to 6.6) were lower than that of intact dentin (range from 6.8 to 7.4). There were statistical differences between the lowest pH value within the active lesion (range from 5.3 to 5.8) and the arrested lesion (range from 6.3 to 6.6) (p<0.05). Although the arrested lesion was unstainable and impermeable to the dye, there was a close relationship between dye staining and pH-imaging characterization within the active lesion from visual inspection.

Adult↗
PubMedDate not supplied

Marginal and internal adaptation of stratified compomer-composite Class II restorations.

Different approaches have been proposed to improve the adaptation of Class II restorations, including applying low-elasticity modulus base liners. This in vitro fatigue test (or study) evaluated the influence of the compomer base-lining configuration on restoration adaptation. Direct Class II MOD box-shaped composite restorations with or without base and lining (n=3x8) were placed on intact human third molars with proximal margins 1 mm above or under the CEJ. The compomer (Dyract) was applied as a 1 mm-thick lining or as a base, closing proximo-gingival margins. Marginal adaptation was assessed before and after each phase of mechanical loading (250,000 cycles at 50N, 250,000 cycles at 75N and 500,000 cycles at 100N); internal adaptation was evaluated after test completion. Gold-sputtered resin replicas were observed in the SEM and restoration quality evaluated in percentages of continuity (C) at the margins and within the internal interface after sample section. Mechanical loading did not influence adaptation to enamel, while it adversely affected restoration adaptation to dentin for the full composite and compomer-base restorations (C varied, respectively, from 95.2 to 75.3% and from 98.0 to 10.6%). The internal adaptation quality showed the same general trend, however, with reduced scores of continuity. In this experimental condition, application of a low elasticity modulus layer under the restorative material proved advantageous but the compomer should not contact the gingival margins.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2002

The effect of Salvadora persica extract (miswak) and chlorhexidine gluconate on human dentin: a SEM study.

Bacterial plaque is solely responsible for the initiation and progression of periodontal diseases. There are different mechanical and chemical methods available for the maintenance of oral health through plaque control. Toothbrushes and miswak (chewing sticks) are widely used for the mechanical removal of plaque. Chlorhexidine gluconate (CHX) is one of the best-proven anti-plaque agents. The aim of this study was to evaluate the effects of CHX and miswak extract on healthy and periodontally involved human dentin. Sixteen human premolars recently extracted for orthodontic and periodontal reasons were used in the study. Teeth were free from caries, cervical restorations, or erosions. The dentin disc specimens were prepared and half of them were etched with 6% citric acid for 120 sec. Both etched and unetched were further treated with CHX and 50% miswak extract and prepared for Scanning Electron Microscopic (SEM) examination. It was concluded that CHX 0.2% and miswak extract 50% had a similar effect on dentin in the control group. Miswak extract removed more smear layer as compared to CHX. Further research is needed in vivo to compare the effects of CHX and miswak extract on periodontally involved teeth and teeth with dentinal hypersensitivity.

Anti-Infective Agents, Local↗
PubMedDate not supplied

Interfacial morphology of an adhesive composite resin and etched caries-affected dentin.

The interfacial structure between an adhesive composite resin and dentin after caries removal and acid conditioning was investigated. The hybrid layer between the adhesive resin and surface-demineralized dentin was found to be wider in the area of empty tubules compared with that of the occluded tubules, and was found to be the thinnest at the lateral walls of the cavity where the dentinal tubules run parallel to the cavity surface. Thus, the extent of demineralization by acid conditioning as well as impregnation of resin into the intertubular dentin forming the hybrid layer is probably related to the degree of closure and direction of the dentinal tubules.

Acid Etching, Dental↗
PubMed1992

Micromorphological relationship between resin and dentin in vivo and in vitro.

This study examined the relationship between resin and dentin both in vitro and in vivo using phosphoric acid conditioning. Four groups of 10 teeth each had standardized Class V preparations made with the gingival cavosurface margin in the root. In Group 1, involving freshly extracted teeth, the enamel and dentin was conditioned with 37% phosphoric acid gel for 15 seconds. NTG-GMA/PMDM was applied to the enamel and dentin followed by an application of BIS-GMA/HEMA and restoration with P50. Group 2 served as a control omitting the conditioning step. Groups 3 and 4 were treated similarly to Groups 1 and 2 except in vivo and extracted 2 weeks after restoration placement. All teeth were sectioned longitudinally through the restoration. Impressions were taken of the tissue/restoration interface and examined by SEM for disclosure of gaps. The teeth were then demineralized and the fitting surface of the restoration was examined by SEM for evidence of resin penetration into the tissue. The results showed a total absence of gaps both in vitro and in vivo after acid conditioning compared to the controls commonly showing gaps. Penetration of resin into the dentin to form a zone of diffusion or hybrid layer was observed only in the conditioned specimens. The phenomenon was observed both in vivo and in vitro. It was concluded that a significant potential exists for phosphoric acid conditioning of dentin to promote bonding.

Acid Etching, Dental↗
PubMed2003

The leakage of Class II cavities restored with packable resin-based composites.

Recently, new resin-based composites, called "packable" or "condensable" resin composites, are being promoted as amalgam alternatives. The purpose of this study was to evaluate leakage in Class II cavities restored with the five packable resin-based composites. On 45 freshly extracted human molars, cavities were prepared following a standardized pattern in which the Class II cavity had a length of 3.0 mm, width of 2.0 mm, and depth of 1.5 mm occlusally. The proximal box had an axial depth of 1.5 mm and a buccolingual width of 4.0 mm. The cervical margin was located 1.0 mm below the cement enamel junction (CEJ). The teeth were randomly divided into five groups of 8 each. The cavity surface was conditioned with 36% phosphoric acid, rinsed, excess water removed, and a dental bonding adhesive (Prime&Bond NT) was used for all the cavities. The teeth were then restored according to the manufacturer's instructions: Group 1, Surefil; Group 2, Solitaire; Group 3, Alert; Group 4, Filtek P60; and Group 5, Prodigy Condensable. After the restorations were completed, the specimens were finished and polished with an aluminum-oxide-coated disc, thermocycled, stained, sectioned, and viewed under a stereomicroscope for leakage at occlusal/enamel and gingival/dentin margins. All test groups showed that leakage of gingival/dentin margins were greater when compared with leakage of occlusal/enamel margins. At the occlusal/enamel margins, there were no significant differences between the materials; however, at gingival/dentin margins, Filtek P60 and Prodigy Condensable demonstrated less leakage, while Solitaire demonstrated greater leakage.

Composite Resins↗
PubMed2004

Influence of passive ultrasonic activation on the penetration depth of different sealers.

Correct use of instruments and irrigating solutions are major factors during chemo-mechanical preparation of root canals. Ultrasonically activated files and solutions are used for debridement of canals. In this study 42 single rooted anterior human teeth were used. The roots were divided into two groups. One group received an application of 17% ethylenediamine tetra acetic acid (EDTA) of 1 ml for 1 min using an ultrasonically energized file. The other group received an application of 17% EDTA of 1 ml for 0.5 min using an ultrasonically energized file. The groups were divided again into two subgroups. The roots were filled with a resin based sealer, AH26 and a glass ionomer sealer--Endion with lateral condensation technique. The roots were separated into two halves. The specimens were viewed through a scanning electron microscope (SEM). Statistical differences between the groups and regions were analyzed with Variance and Duncan tests. Under the conditions of this study, it can be said that ultrasonically activated irrigation did not reduce the smear layer effectively at 1 min and 0.5 min time intervals. According to this result, no difference was observed between the penetration of sealers.

Analysis of Variance↗
PubMed2003

Impact of Crest Night Effects bleaching gel on dental enamel, dentin and key restorative materials. In vitro studies.

PURPOSE: To examine the effects of a paint-on 19% sodium percarbonate 'overnight' bleaching gel on the structure and integrity of enamel, dentin and some common restorative materials, with a laboratory cycling model. METHODS: Enamel, root dentin and restorative materials (glass-ionomer, composite and amalgam) were prepared in methacrylate molds with surface polishing. A treatment regimen was carried out including diurnal incubation in pooled human saliva and including twice daily toothbrushing with standard fluoridated dentifrice. Test samples were treated daily with Crest Night Effects bleaching gel, which included drying of surfaces, painting of percarbonate bleaching gel, and then incubation throughout the day (8 hours) to simulate overnight wear. Treatments were carried out over 14 days, to simulate clinical exposure periods. Control and test specimens were evaluated for surface and subsurface structure and morphological integrity utilizing surface microhardness, surface profilometry, and confocal laser scanning microscopy. RESULTS: Percarbonate bleaching film treatments had no effects on enamel or root dentin surface microhardness, or on subsurface ultrastructural integrity of enamel and coronal dentin. Surface profilometry confirmed retention of small amounts of residual silicone polymers, which contributed to CLSM air objective appearance and surface roughness measures. Restoratives were generally passive to bleaching gel treatments, though composite showed a tendency to attract retained residual silicone film.

Bicuspid↗
PubMed1992

Changes in pulpal blood flow and in fluid flow through dentine produced by autonomic and sensory nerve stimulation in the cat.

We have recorded the flow of fluid through exposed dentine in cat canines. The effects on this flow of electrical stimulation of the cervical sympathetic trunk (CST) and of the inferior alveolar nerve (IAN) were investigated. In some preparations, pulpal blood flow was also monitored with a laser Doppler flow meter and the compound action potentials evoked by IAN stimulation were recorded from the tooth. CST stimulation (0.5-5/s) resulted in a significant decrease in the rate of outward flow of fluid through the dentine or, with the higher frequencies tested, a reversal of the flow. CST stimulation also produced vasoconstriction. IAN stimulation caused a significant increase in the rate of outward flow of fluid from the dentine. This effect required the recruitment of A delta fibres: A beta fibres alone had no effect. Pulpal vasodilatation occurred with the same threshold. Mechanical stimulation of dentine in an acutely denervated tooth also caused vasodilatation, indicating that pulpal afferents were involved. The results show that the rate of fluid flow through dentine, and hence the rate of inward diffusion of chemicals from the oral cavity, can be influenced by changes in the state of the pulpal microvasculature.

Action Potentials↗
PubMed1992

Phosphoric acid as a dentin etchant.

This study determined the effect of phosphoric acid (H3PO4) application to dentin on the shear bond strength (SBS) and microleakage of an experimental bonding system. Thirty human maxillary permanent first and second molars were used for the SBS evaluation. In 15 of the teeth the Dentin Conditioner was applied to dentin for 30 seconds (A), while in the remaining 15 teeth the smear layer was removed by the application of a 37% H3PO4 gel for 20 seconds (B). The Primers 1 and 2 were mixed and applied to the conditioned dentin followed by the application of the Dentin Bonding Resin prior to the placement in three increments of the Bisfil-M composite. The specimens were stored in physiological saline at 37 degrees C for 24 hours prior to applying a shear load at a crosshead speed of 0.5 mm. inch-1 in an Instron machine. Shear bond strengths were expressed in MPa. Circular Class V preparations were made on the roots of 30 maxillary permanent canines, 15 restored using the Dentin Conditioner (C) and 15 by removing the smear layer with the H3PO4 gel (D). Microleakage of the restorations was determined quantitatively by means of a spectrophotometric method. The quantitative microleakage was expressed as microgram dye/restoration. The data were analyzed by the Student t-test. The following results were obtained: A: 14.2 +/- 2.2 MPa; B: 7.2 +/- 4.2 MPa; C: 30.0 +/- 28.6 micrograms dye/restoration; (D) 10.3 +/- 8.2 micrograms dye/restoration. Removing the smear layer with H3PO4 reduced the SBS to dentin but decreased the quantitative microleakage significantly.

Acid Etching, Dental↗
PubMed2005

Barodontalgia as a differential diagnosis: symptoms and findings.

This paper provides a review of the literature concerning the etiology and manifestations of barodontalgia, as well as important clinical considerations for its management. Barodontalgia is characterized by exposure to a pressure gradient, such as that experienced by underwater divers, aviation personnel and air travellers. This form of dental pain is generally marked by a predisposing dental pathology such as acute or chronic periapical infection, caries, deep or failing restorations, residual dental cysts, sinusitis or a history of recent surgery. Studies indicate that severity of barodontalgia and the resulting deterioration of dental health correlates with duration of barometric stress. Restorative materials are also affected by pressure gradients. Resin is indicated as a luting agent of choice for cementing fixed prostheses in populations at risk for barodontalgia. Under the influence of pressure gradients, resin cements maintain original bond strength and demonstrate the least amount of microleakage compared with other cements. The key to avoiding barodontalgia is good oral health. Clinicians must pay close attention to areas of dentin exposure, caries, fractured cusps, the integrity of restorations and periapical pathology in those at risk. The Fédération dentaire internationale describes 4 classes of barodontalgia based on signs and symptoms and provides specific and valuable recommendations for therapeutic intervention.

Aerospace Medicine↗
PubMed2005

A comparative SEM study of smear layer removal by detergents and EDTA on the root surface.

The present study performed an SEM evaluation of the efficiency of the following detergents on smear layer removal on the root surface: sodium lauryl sulphate, Plax, castor oil, and EDTA 24%. Sodium lauryl sulphate did not remove the smear layer and showed the worst results of all detergents tested. Plax and castor-oil detergents showed similar results represented by partial removal of the smear layer; these results were better than those obtained in the control (physiologic serum) and sodium lauryl sulphate groups. Neutral EDTA 24% was the most efficient detergent for smear layer removal.

Benzoates↗
PubMedDate not supplied

Microscopic evaluation of the interface between glass-ionomer cements and tooth structures prepared using conventional instruments and the atraumatic restorative treatment (ART) technique.

OBJECTIVE: The purpose of this study was to evaluate the effect of cavity preparation using hand instruments and conventional rotary instruments on the bonding of glass-ionomer cements to formerly carious teeth. METHOD AND MATERIALS: In 2 experimental groups (12 teeth each with primary caries) caries was removed and cavities prepared using hand instruments according to the atraumatic restorative treatment (ART) technique or conventional rotary instruments. In the control group (12 caries-free teeth) Class 1 cavities were prepared using conventional instrumentation. Cavities in all teeth were restored with 1 of the commercial glass-ionomer cements designed for use with the ART technique, either Fuji IX (GC) or Ketac Molar (3M Espe). After 21 days of storage in physiologic saline at 37 degrees C, 3 400-microm-thick slices from each tooth were stained using the Mallory method and evaluated using a light transmitting microscope. RESULTS: In all samples, a region of interaction was observed between the cement and dentin and enamel. However, the interface in teeth from which caries had been removed was different from that in the control group. All were stained using Mallory staining, but only teeth which had been carious showed coloration. No differences were found in intensity of color or appearance between the cavity preparation techniques. CONCLUSION: The occurrence of caries in a tooth alters the bonding behavior of glass ionomers to that tooth. The method of caries removal (ART or conventional preparation) does not influence the quality of the interface between a glass ionomer and either dentin or enamel.

Acids↗
PubMed2006

Marginal quality in enamel and dentin after preparation and finishing with an Er:YAG laser.

PURPOSE: To find the most appropriate Er:YAG laser parameters for an optimal marginal adaptation of Class V restorations in enamel and dentin. METHODS: Six saucer-shaped mixed Class V cavities were prepared in each of the eight experimental groups with an Erbium:YAG hard laser (Opus Duo) on extracted human molars in near contact mode with a conical 800 microm sapphire tip under continuous water spray by using different pulse energy and pps (pulse per second) parameters. The cavities were restored under the simulation of dentin fluid with Clearfil SE Bond and Clearfil APX PLT composite applied in two layers and light-cured. Marginal adaptation in enamel and dentin was quantified before and after simultaneous thermal (5-50-5 degrees C, 2 minutes each) and mechanical (max. 49N; 1,200,000 cycles) stresses by using the replica technique in a SEM under x200 magnification. RESULTS: With the exception of dentin margins before loading, significant differences for percentages of "continuous margin" and "enamel fractures" were detected before and after loading (P < 0.05, ANOVA, Student's t-test). A pulse energy of 100 mJ both on dentin and enamel was found optimal for finishing and smoothing the preparation margins after cavity preparation with 500 mJ or more.

Analysis of Variance↗
PubMedDate not supplied

[Structural changes in human dentin with the use of modern filling materials].

Changes in human dentin surface structure, effected by potassium oxalate, potassium nitrate, calcium hydroxide, were studied by scanning electron microscopy. Crystal layers of different structures with complete or partial occlusion of the dentin tubes were detected. Complete occlusion was achieved only if potassium oxalate was used.

Calcium Hydroxide↗
PubMed1991

[Chelation].

The use of chelation in endodontics demands a knowledge of the workings of its physico-chemical process. To explain this, we must define unsaturated salts and contrast them with the complexes to which the chelates belong. A few examples of application illustrate these different properties especially the action of E.D.T.A. on the calcified tissues of the endodontium. The mode of action of liquid E.D.T.A. or chelating gels in calcified root canals, poses several questions. The varied studies realized in this domaine allow us to affirm the usefulness of E.D.T.A. in root canal disinfection and in opening up lateral and accessory canals. Also, we must consider the possible influence of chelating agents on the apical seal when the permanent root filling is post poned, and their role in changing the permeability of dentine.

Chelating Agents↗