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PubMedDate not supplied

Micromorphological study of resin-dentin interface of non-carious cervical lesions.

This study examined the interfaces between two dentin adhesives, namely, One Coat Bond, Clearfil SE Bond and a resin-modified glass ionomer cement (Fuji II LC) and the dentin of non-carious cervical lesions (NCCLs) with FE-SEM, and compared them with the interfaces produced with "normal" dentin. Fifteen human premolars each with a buccal NCCL were used. Cervical cavities were prepared on the lingual surface of the same teeth for the normal (control) dentin. All lesions and prepared cavities were cleaned with a slurry of pumice and water. The teeth were randomly divided among the three products that were applied according to the manufacturers' instructions. For the resin-bonded specimens, the cavities were restored with resin composite. All specimens were stored in 37 degrees C tap water. Resin-bonded specimens were observed using FE-SEM after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite (NaOCl). The resin-modified glass ionomer cement (RM-GIC) specimens were observed after 10% phosphoric acid and 5% NaOCl treatment. The hybrid layer could be observed for the two adhesive systems in all specimens, but the thickness varied depending on the bonding system used and the dentin substrate. The results suggested that the hybrid layer produced in normal dentin was slightly thicker than that of NCCLs. Further, the hybrid layer thickness decreased in all specimens after NaOCl treatment.

Bicuspid↗
PubMed2004

Assessment of morphological changes and permeability of apical dentin surfaces induced by Nd:Yag laser irradiation through retrograde cavity surfaces.

The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces induced by Nd:YAG laser irradiation at different power settings with and without a laser initiator. Seventy five single rooted human maxillary anterior teeth were used. Following the establishment of the working lengths, the root canals were enlarged with step-back technique. The apex of each root was resected 3 mm perpendicular to its long axis. Standard Class I cavities of 2 mm depth and 2 mm width were prepared. The teeth were randomly divided into five groups with fifteen teeth in each. In Group 1, the retrograde cavity preparations were lased with Nd:YAG laser at 2 W and those in Group 2 preparations were lased with Nd:YAG laser at 3.2 W. In Group 3, the retrograde cavity surfaces were lased with Nd:YAG laser at 2 W following the application of India ink. Group 4 was lased with the same settings of Group 2 after an absorbent cotton point soaked with India ink was inserted into the cut dentinal surfaces and the inner walls of the apical preparations. Group 5 served as control. Five teeth from each group were examined using scanning electron microscopy (SEM). The amounts of smear layer, debris, and recrystalized dentin present were assessed and scored. Retrograde cavities of ten teeth from each group were filled with amalgam to examine apical dye penetration. The teeth were immersed in 2% basic fuscin and kept for 48 hours. Dye penetration was evaluated by stereomicroscope at a magnification of X10. The results showed the usage of India ink with Nd:YAG laser enhanced the amount of melting and recrystalization of dentin and the radiation and initiator increased the leakage.

Analysis of Variance↗
PubMed2000

Temperature dependence of the electrical resistance of sound and carious teeth.

Temperature variations are expected to influence measurement error in electrical resistance of teeth. It was the aim of this study to determine the changes in electrical behavior of extracted human teeth due to temperature changes in the range of room temperature to intra-oral temperature. Nine extracted teeth were selected, and the occlusal or an approximal surface was chosen for measurement. Carious involvement of the surfaces ranged from sound to cavitated. Electrical impedance spectroscopy sweeps in a frequency range of about 100 kHz to 10 Hz were completed at selected temperatures between 22 degrees C and 40 degrees C. After fitting the data to equivalent circuits that yielded parameter values for components of the equivalent circuit, we calculated the dc bulk resistance (Rh). The temperature dependence of Rb of the surfaces with different carious involvement was very similar, and the mean drop of Rb from 20 to 35 degrees C was 45% (SD 2%). It was concluded that the electrical resistance of sound and carious tooth surfaces is inversely related to temperature.

Dental Caries↗
PubMed1998

Effects of pulsed Nd:YAG laser irradiation on root canal wall dentin with different laser initiators.

The effects of pulsed Nd:YAG laser irradiation with different laser initiators on the permeability and ultrastructure of the root canal wall dentin were investigated in vitro. Forty extracted human single-rooted teeth were randomly assigned to four groups. Group 1 teeth were not lased as a control. Group 2 specimens received four 10-s duration laser exposures for a total exposure of 40 s/canal. In group 3 specimens, the root canals were painted with black ink and then lased by the same method as group 2 teeth. In group 4 specimens, root canals were treated with 38% Ag(NH3)2F and then lased by the same method as group 2 teeth. Laser parameters were set at 2 W, 20 pps. After being placed in 0.6% rhodamine B solution for 48 h, the teeth were sectioned for study by stereoscope and scanning electron microscopy. Statistical analysis showed there were significant differences (p < 0.05) in dentin permeability in the apical areas between groups 3 and 1, 4 and 1, and 4 and 2. Scanning electron microscopic examination showed that laser treatment alone had no obvious effects on the root canal wall. The root canal surfaces prepared for by laser irradiation with black ink or 38% Ag(NH3)2F revealed melting, smear layer evaporation, and open dentinal tubules. Black ink was more effective than 38% Ag(NH3)2F as a Nd:YAG laser initiator.

Dental Pulp Cavity↗
PubMed1992

Reduction of intra-oral demineralization of enamel after single exposures to sodium fluoride.

Studies demonstrated the effects of single rinses with low concentrations of NaF on the intra-oral demineralization of enamel. Blocks of bovine enamel were covered with Streptococcus mutans IB1600, mounted in palatal appliances, and worn in the mouths of volunteers for specified times. Subjects rinsed with solutions of NaF, with or without sucrose. Demineralization was determined as changes in iodide penetrability (delta Ip) of the enamel, while the pH and F of the streptococcal plaque, and enamel F, were determined with ion-specific electrodes. Delta Ip was reduced by about 80% (from 14.5 +/- 2.7 to 2.8 +/- 2.3 units) when 250 micrograms F/mL was added to the sucrose rinse. Corresponding plaque pH's were 4.1 +/- 0.5 and 4.2 +/- 0.3, consistent with a lack of effect on bacterial acidogenesis. Protection against mineral loss was concentration-dependent. Administration of sucrose at different times after NaF revealed that the effect of F persisted for at least 60 min. Analyses of plaque F demonstrated an initial elevation and concentration within the cells, followed by a drop to stable, baseline values. Enamel F increased slowly to almost 500 micrograms/g enamel after 105 min. The protective effect of F appeared to be manifested in two stages, the first related to a high plaque F and the second to F that became incorporated into the enamel. Analysis of the data suggested that F was transferred from plaque to enamel during the experimental period.

Adult↗
PubMed1996

Regional strengths of bonding agents to cervical sclerotic root dentin.

The regional bond strengths of three current-generation bonding systems (All Bond 2, Scotchbond Multi-Purpose, and Clearfil Liner Bond 2) were measured in natural wedge-shaped defects in the cervical area of extracted human teeth. A microtensile testing method was used to compare the strengths of resin bonds made to occlusal margins with those made to gingival margins. Controls consisted of normal teeth which had artificial wedge-shaped defects, of the same depth and dimension, created with a high-speed bur. The results indicated that there were no regional differences in bond strength, although bonds made to natural lesions were from 20 to 45% lower than those made to normal dentin in artificially created wedge-shaped defects, depending on the bonding agent. Scanning electron microscopy revealed that Clearfil Liner Bond 2 created the thinnest hybrid layers, which were difficult to measure in the natural lesions. The natural lesions contained sclerotic dentin, whereas the artificial lesions were composed of normal dentin. Although the bond strengths to sclerotic dentin were lower than those to normal dentin, the absolute values (ca. 16 to 17 MPa) were high relative to previous-generation bonding agents.

Acid Etching, Dental↗
PubMed2004

Diffusion of calcitonin through the wall of the root canal.

The aim of this study was to evaluate the in vitro diffusion of synthetic salmon calcitonin (CT), used as an intracanal medication, to the external root surface, with or without the presence of intact root cementum. Fifty-four human central incisors were used in the experiment, and were divided into two groups of 21 (test groups) and two groups of 6 teeth (control groups). After root canal preparation, 10 mul of calcitonin was inserted within the root canal chamber. The root was sealed and made externally impermeable. Specimens were then placed in tubes with saline solution buffered with phosphates and stored at 37 degrees C. The diffusion of calcitonin was measured after 1, 4 and 7 days. To count calcitonin present at the external media (PBS), ELISA test (an antigen-antibody reaction) was used. Results showed that there was calcitonin diffusion through dentin in all of the test samples. The absence of cementum increased the diffusion of calcitonin (p=0.05). The highest counts of CT were obtained on day 7 for groups with or without cementum - showing a direct relation between time and diffusion of the medication.

Animals↗
PubMed2000

Optical scattering power for characterization of mineral loss.

Mineral loss in early caries cannot be measured without invasive procedures. To quantify mineral loss without sectioning the tooth, one must determine the optical scattering of the enamel. Using enamel white-spot lesions, we hypothesize that the optical scattering power (Sp) of the demineralized enamel would provide a quantitative estimate of mineral loss. Enamel slabs were demineralized to produce artificial white spots. The data were acquired by means of a Charge-Coupled Device (CCD) camera and image-processing software. For the purpose of comparison, mineral loss (deltaZ) of the demineralized samples was determined by the use of a microhardness approach after the samples were sectioned. The scattering power correlated well with deltaZ (r2 = 0.82). In contrast, simple reflectance of the demineralized samples correlated poorly with deltaZ (r2 = 0.22). The validity of using scattering power to measure demineralization has been confirmed by a three-dimensional Monte Carlo Simulation.

Animals↗
PubMed2003

Influence on pH of vehicle containing glycerin used with calcium hydroxide.

- The pH values of the external aqueous medium, relative to the roots of 41 human premolar teeth filled with Ca(OH)2 in to several vehicles, were evaluated in the present study. After root canal biomechanical preparation and smear-layer removal, the teeth were stored individually, immersed in flasks containing 800 ml of ultra-pure deionized water for a period of 118 days. A pH meter was used to analyse the pH values as a function of time. The measurements were divided into phase 1: dissolution, in which all canals remained empty and open in the absence of medicament for 48 days, and phase 2: diffusion, in which the specimens were divided into 10 groups which consisted of three control groups: group 1, water control; group 2, sealing control; and group 3, opened canal dissolution control, and seven experimental groups, with five teeth each, whose canals were filled with Ca(OH)2 paste associated with the following vehicles: group 4, saline solution; group 5, polyethylene glycol (Calen); group 6, glycerin and parachlorophenol (PMCC); group 7, PMCC; group 8, glycerin; group 9, glycerin and formo cresol (FC); and group 10, anesthetic solution. This phase lasted for 70 days. A total of 1058 measurements of the pH values were made. Regression analysis was used for statistical evaluation. The results show that all groups containing polyol in the composition of the paste had a trend to acidification in the interval between filling and 14 days later (therapeutic period) and, at the end of the experiment (1687 h to 70 days after canal filling), the pH was slightly alkaline. We conclude that polyhydroxy alcohol (glycerin and polyethylene glycol, Calen) diffusion enhances acidification of the aqueous medium.

Calcium Hydroxide↗
PubMed2002

Intracoronal sealing ability of two dental cements.

The purpose of this study was to compare the efficacy of sealing the coronal 2-mm of the root canals versus covering the entire pulpal floor with one of two dental-resin cements (Principle or C&B Metabond). Sixty-two molars with the occlusal half of the crowns and the apical half of the roots removed were used. Each canal was enlarged by using a #3 Gates Glidden bur and obturated with unsealed gutta-percha cones. The teeth were randomly assigned to four groups, each containing 15 teeth, plus a negative and a positive control. In group 1, 2 mm of Principle were placed over the entire pulpal floor. In group 2, Principle was placed 2 mm into each canal orifice. Groups 3 and 4 were the same as groups 1 and 2, except C&B Metabond cement was used. After the cement set, the gutta-percha was removed and the integrity of the seal was tested by fluid filtration at a pressure of 20 cm H2O at 1 h and at 1, 2, and 4 weeks. The data were analyzed by a three-way ANOVA and the Student-Newman-Keuls tests at alpha = 0.05. The controls behaved as expected. Results showed that there were no statistically significant differences among the materials used or the location (p > 0.05), but there was a significant difference with respect to time. Principle leaked significantly more than C&B Metabond at 1 h (p < 0.05), but the seal became tighter over time. C&B Metabond leaked less early (p < 0.05) but increased in leakage at 4 weeks. Both materials sealed well over the 4-week study. Principle was easier to use, and sealing the entire pulpal floor was easier than sealing only the canal orifice.

Analysis of Variance↗
PubMed1997

Effectiveness of calcium lactate added to food in reducing intraoral demineralization of enamel.

Following the demonstration that rinses with solutions of soluble calcium salts reduced sucrose-induced demineralization, a study was undertaken to determine whether a similar effect could be obtained by the supplementation of a solid food with calcium lactate (CL). Subjects wore palatal appliances containing blocks of bovine enamel that were coated with Streptococcus mutans IB 1600 and ate 5-gram portions of cookies made with defined levels of CL. Determinations were made of changes in iodide penetrability (delta Ip) of the enamel, as well as the pH, calcium and inorganic phosphate of the streptococcal plaque. CL at 3.2% (w/w) reduced delta Ip from 12.9 +/- 1.7 to 6.1 +/- 0.9 units, i.e. by 52.7%. Plaque pH was not affected. Demineralization was reduced progressively with increasing concentrations of added CL, and CL was most effective with increasingly sweet cookies. Plaque contained 32.4 +/- 6.0 and 17.1 +/- 4.2 mM calcium after 1 and 5 min, respectively. Calculations showed that the plaque was saturated with respect to enamel during the first 5-10 minutes after food ingestion, in spite of the progressive drop in plaque pH. In conclusion, the present study demonstrated the reduction of the cariogenic potential of solid food by relatively low concentrations of CL. The effect appeared to be related to the ability of the food to maintain high levels of calcium in the streptococcal plaque during the period of active acidogenesis.

Acids↗
PubMed1995

Late effects of radiation therapy in the head and neck region.

The head and neck region is composed of numerous structures, each with an inherent response to radiation that is largely governed by the presence or absence of mucosa, salivary glands, or specialized organs within that site. Irradiated mucocutaneous tissues demonstrate increased vascular permeability that leads to fibrin deposition, subsequent collagen formation, and eventual fibrosis. Irradiated salivary tissue degenerates after relatively small doses, leading to markedly diminished salivary output. This, in turn, effects the teeth by promoting dental decay which, in turn, effects the integrity of the mandible. Details of these changes are presented, including their pathophysiology, clinical syndromes, and potential treatment.

Capillary Permeability↗
PubMed2007

Electric device improves bonds of simplified etch-and-rinse adhesives.

OBJECTIVES: This study investigated the effects of an electric field produced by a new device for the application of etch-and-rinse adhesives on demineralized dentin surfaces. METHODS: Three simplified etch-and-rinse adhesives (Single Bond, Prime&Bond NT and One-Step) were applied with the electric device and compared with controls prepared with disposable sponges. Specimens were processed for microtensile bond strength test and nanoleakage investigation using high resolution SEM. RESULTS: Microtensile testing revealed higher bond strengths (p<0.05) for all adhesives tested when electricity was used. Adhesive interfaces prepared with electric impulses exhibited very homogenous hybrid layers with minimal nanoleakage compared with the controls. SIGNIFICANCE: The use of electricity produced by a new electronic device during the application of dentin adhesives may increase adhesive adaptation to the dentin substrate and improve dentin hybridization due to the substrate modifications induced by an electric field on the demineralized dentin organic matrix.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2006

Ultrastructure of intraradicular dentin after irrigation with BioPure MTAD. II. The consequence of obturation with an epoxy resin-based sealer.

In addition to an initial report on the creation of thick demineralized collagen matrices in root dentin that were irrigated with BioPure MTAD or EDTA as final rinses for 5 minutes, this study examined the effect of a 2-minute irrigation time of these final irrigants on the extent of demineralization of intact intraradicular dentin and on interfacial nanoleakage after obturation with AH Plus and gutta-percha using warm vertical compaction. Transmission electron microscopy confirmed that the reduction in irrigation time did not compromise the smear layer removing capacity of these two irrigants when 1.3% NaOCl was employed as the initial rinse. BioPure MTAD created 5 to 6 microm thick demineralized dentin matrices, while 17% EDTA produced 1 to 2 microm thick matrices that were suboptimally infiltrated by the epoxy resin-based sealer, as manifested by the occurrence of silver tracer deposits within the hybrid layers.

Chelating Agents↗
PubMed2002

Expression of endothelial adhesion molecules in the alveolar ridge mucosa, gingiva and periimplant mucosa.

OBJECTIVES: The purpose of this study was to analyze the expression of adhesion molecules on endothelial cells in the alveolar ridge mucosa, the gingiva and the periimplant mucosa in humans. MATERIAL AND METHODS: Twelve partially edentulous subjects were included in the study. In each subject, one soft tissue biopsy was harvested from the edentulous alveolar ridge mucosa, one from a tooth site and one from an implant site. After 3 weeks of undisturbed plaque accumulation, an additional biopsy was obtained from one tooth and one implant site in each subject. The tissue samples were snap frozen and prepared for immunohistochemical analysis. RESULTS: In the alveolar ridge mucosa, smaller proportions of endothelial cells expressing ICAM-1, ELAM-1 and VCAM-1 were observed than in the gingiva. ELAM-1-positive cells occurred in lower numbers than in periimplant mucosa. After 21 days of plaque accumulation, ELAM-1 was increased in tooth sites, but decreased in periimplant mucosa. CONCLUSION: The results of the present study indicated that the proportions of activated endothelial cells and the extravasation of leukocytes is larger in gingiva and periimplant mucosa than in alveolar ridge mucosa. This might be due to the less permeable keratinized epithelial layer in the edentulous ridge mucosa, which offers proper protection against microbial pathogens. The greater expression of endothelial cell adhesion molecules during experimental gingivitis, compared to periimplant mucositis, may reflect its longer history of repeated antigenic assaults.

Aged↗
PubMed1997

The effect of airflow on site-specific electrical conductance measurements used in the diagnosis of pit and fissure caries in vitro.

There has been renewed interest in the electronic diagnosis of occlusal caries using measurement of conductance or impedance. One of two previously manufactured electronic caries detectors (the Vanguard electronic caries detector, Massachusetts Manufacturing Corporation, Cambridge, Mass., USA) had a probe tip with an integral air supply. Airflow is essential for removing superficial moisture and preventing surface conduction to the gingival margin. The aim of this study was to determine the effect of airflow on electronic diagnosis of occlusal caries using a prototype electronic caries meter (ECM II. LODE, Groningen, The Netherlands) fitted with a flow meter. Stable conductance readings were taken at 76 discrete sites on 32 extracted teeth with no visible signs of cavitation, at 3 airflows: 5, 7.5 and 10 litres/min. The stable conductance scale was a continuous scale from -0.45 to 13.25 and set by the manufacturer. Histological validation was carried out on macroradiographs of sections cut to include each sample site. The histological picture was compared with the stable conductance readings taken at various airflows. Sensitivity and specificity were calculated using different conductance readings to differentiate sound and carious sites, and receiver operating characteristic (ROC) curves constructed. Of the sites, 32% had enamel and dentine caries and 33% had enamel caries. The ROC curves showed airflow to be highly relevant. An airflow of 5 litres/min was shown to be inadequate and led to large numbers of false-positive diagnoses. A minimum airflow of 7.5 litres/min was required to achieve optimum sensitivity (92%) and specificity (87%) for dentine caries diagnosis.

Air Movements↗