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PubMed1998

Soluble calcium/SMFP dentifrice: effect on enamel fluoride uptake and remineralization.

PURPOSE: To evaluate in situ the effect of soluble calcium on fluoride uptake and remineralization by human dental enamel from a sodium monofluorophosphate (SMFP) dentifrice. MATERIALS AND METHODS: Eight volunteers took part in this cross-over, double-blind design study performed in three phases of 45 days. During each phase of the experiment, the subjects wore an acrylic resin appliance containing four blocks of human dental enamel with artificial caries to evaluate fluoride uptake and remineralization by three dentifrices: SMFP containing CaCl2, SMFP, and placebo. After each phase, the enamel blocks were removed and the total fluoride uptake (ppm F) and microhardness (Knoop) were measured. Statistical analyses (ANOVA and Turkey's test) were done. RESULTS: There was no statistically significant difference between SMFP-CaCl2 and SMFP treatments regarding the amount of fluoride and microhardness data of treated enamel blocks as well as their areas under the curves, although both differed significantly (P < 0.05) when they were compared with placebo. However, the SMFP-CaCl2 treatment demonstrated the highest values on fluoride uptake and microhardness data. Furthermore, the microhardness data demonstrated 50% and 40% of remineralization for SMFP-CaCl2 and SMFP dentifrices, respectively.

Analysis of Variance↗
PubMed1999

Dental applications of amorphous calcium phosphates.

Certain commercial materials and equipment are identified in this paper to specify the experimental procedure. In no instance does such identification imply recognition or endorsement by the National Institute of Standards and Technology or the ADA Health Foundation, or that the material or equipment identified is necessarily the best available for the purpose.

Calcium Phosphates↗
PubMedDate not supplied

Remineralization across the resin-dentin interface: in vivo evaluation with nanoindentation measurements, EDS, and SEM.

OBJECTIVE: The purpose of this study was to evaluate the in vivo remineralization of the possible non-resin infiltrated hybridoid layer between the hybrid layer and the subjacent dentin substrate using nanoindentation, energy dispersive x-ray spectroscopy microanalyses (EDS), and scanning electron microscopy (SEM) technologies. METHOD AND MATERIALS: Twenty Class V cavities were placed in healthy adult monkey teeth. Each cavity was total etched with 37% phosphoric acid for 60 seconds, rinsed, and air dispersed, and SA-Primer was applied to the collagen layer. Cavities were divided into two groups: In group 1, Protect Liner (low-viscosity resin) and Clearfil AP-X (resin composite) were placed per manufacturer's directions, and no bonding agent was placed on the acid-etched interface. In group 2, Clearfil Photobond (bonding agent) was applied, and Protect Liner and Clearfil AP-X were placed as in group 1. Teeth were observed at 7 days (control) and 6 months by nanoindentation, EDS, and SEM. RESULTS: Six-month data showed an increased nanohardness in areas 5 pm adjacent to the demineralized or partially demineralized dentin interface. Following treatment with a conventional adhesive system on the acid-etched interface (group 2), there were increased nanohardness and calcium EDS measurements in the substrate just below the resin-dentin impregnated layer. CONCLUSION: Our 6-month in vivo nanoindentation and EDS data demonstrate that the non-resin infiltrated zone becomes remineralized following adhesive resin treatment.

Acid Etching, Dental↗
PubMed2002

How can nanoleakage occur in self-etching adhesive systems that demineralize and infiltrate simultaneously?

PURPOSE: Single-step adhesives which etch and prime simultaneously and are not rinsed should not exhibit areas of incomplete infiltration within hybrid layers produced in sound dentin. This study examined the extent of silver uptake using ammoniacal silver nitrate in three two-step, self-etching primers (Imperva Fluoro Bond, Shofu; UniFil Bond, GC, ABF system, Kuraray) and one single-step, self-etching adhesive (AQ Bond, Sun Medical) bonded to dentin and four poly(HEMA) resins used as controls. MATERIALS AND METHODS: Flat dentin surfaces were bonded with these adhesives and sectioned into 0.8-mm-thick slabs that were then coated with nail varnish except for the bonded interfaces and immersed in AgNO3 for 24 h. Four types of poly(HEMA) resins were made: 100% HEMA; 90% HEMA-10% water; 75% HEMA-10% water, all polymerized with TBBO at 50 degrees C for 6 h; 100% HEMA polymerized at 25 degrees C for 30 min. After developing, undemineralized, unstained, epoxy resin-embedded sections were prepared for TEM. RESULTS: Nanoleakage patterns were observed in all bonded specimens. Fine segregated silver particles and reticular silver-staining patterns were found within the thin hybrid layers created by the three self-etching primers. For the single-step, self-etching adhesive, heavy silver deposits were identified within the hybridized complex formed by this adhesive within the smear layer, the underlying intact dentin, and in the adhesive layer. Increasing amounts of silver uptake were observed in poly(HEMA) specimens containing more water or that were polymerized at 25 degrees C for a short time instead of 50 degrees C for 6 h. CONCLUSIONS: Silver uptake in hybrid layers formed by self-etching adhesives in sound dentin is not necessarily caused by disparities between the depths of demineralization and resin infiltration. They represent areas of increased permeability within a polymerized resin matrix in which water is incompletely removed resulting in regions of incomplete polymerization and/or hydrogel formation.

Acid Etching, Dental↗
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↗
PubMed2006

Bond strength and failure patterns of adhesive restorations in primary teeth aged in the oral environment.

PURPOSE: To evaluate the bond strength and micromorphology of the fracture pattern of adhesive composite restorations in primary teeth after long-term clinical function. METHODS: Subjects (8-10 years-old) with deep carious lesions in primary molars had their teeth restored with resin composite (Z250). The teeth were randomly divided into two groups, according to the adhesive system used: (1) Scotchbond Multi-Purpose (SMP); and (2) Clearfil SE Bond (CSE). After the clinical and radiographic follow-up period (15-17 months), the teeth were exfoliated and the adhesive restorations were subjected to microtensile bond test. RESULTS: Student's t-test revealed a statistical difference (P= 0.001) between the two adhesive systems tested (SMP = 16.8 +/- 2.62 MPa; CSE = 27.3 +/- 2.28 MPa). The micromorphology evaluation of the failure zone revealed a weak area in the demineralized dentin (SMP) and at the top of the hybrid layer (CSE).

Child↗
PubMed1993

Permeability of dentin to adhesive agents.

The permeability of dentin to adhesive agents is of crucial importance in obtaining good dentinal bonding. In those systems that remove the smear layer, the opportunity exists for resin to infiltrate both tubules and intertubular dentin. Resin penetration into tubules can effectively seal the tubules and can contribute to bond strength if the resin bonds to the tubule wall. Resin infiltration into intertubular dentin can only occur if the mineral phase of dentin is removed by acidic conditioners or chelators. This is more easily accomplished in fractured dentin than in smear layer-covered dentin because of the residual collagen debris that remains on the surface following acid etching of smear layers. The channels for resin infiltration are the perifibrillar spaces created around the collagen fibers of dentin following removal of apatite mineral by acids. The diffusion of adhesive resins through these narrow, tortuous, long channels in 1 to 2 minutes offers a number of challenges that require further research.

Acid Etching, Dental↗
PubMed1997

The biomimetics of enamel: a paradigm for organized biomaterials synthesis.

The formation of enamel takes place through a sequence of processes that can be mimicked in inorganic materials chemistry. This chapter describes the generic features of enamel biomineralization in terms of a house-building analogy. Four stages are identified: supramolecular preorganization and spatial patterning; interfacial molecular recognition in inorganic nucleation; vectorial crystallization; and pattern evolution and hierarchy. Each of these concepts can be translated into synthetic approaches to the formation of inorganic materials with organized architectures. An example of applying this biomimetic paradigm is described. Supersaturated water-in-oil microemulsions have been used to synthesize microskeletal calcium phosphates by controlled nucleation and vectorial growth in constrained reaction environments. The results of these preliminary studies suggest that biomimetic concepts could be useful in the fabrication of biomaterial implants with controlled porosity and microstructure.

Amelogenesis↗
PubMed1992

Evaluation of smear layers on serial sections of human dentin by means of electrochemical impedance measurements.

The alternating current impedance characteristics of a uni-directional porous glass membrane and serial sections of dentin from unerupted human third permanent molars (with and without smear layers) were measured. The membrane was equilibrated at 20 +/- 1 degrees C in a range of concentrations of unbuffered KCl, and the tooth sections were equilibrated in 0.1 mmol/L unbuffered KCl. Each section's impedance was measured for a 50-mV (rms) alternating potential difference applied over 1 Hz to 65 kHz. By means of complex non-linear least-squares regression analysis, the dc resistance of each specimen was determined. Scanning electron microscopy and subsequent image analysis enabled the cross-sectional area of the pores in the membrane and dentin tubule surface-openings to be measured. The results showed that the measured cross-sectional area of pores in the membrane was in good agreement with that calculated from the measured dc resistance and solution resistivity over the range of electrolyte concentrations. In dentin, the presence of smear layers on the cut surfaces increased the measured resistance. The resistance of the smear layer varied, suggesting that its thickness changed across the surface of the dentin. This was superimposed on regional variations in resistance of smear-free dentin which were found to be related to alterations in the number of tubules present and their cross-sectional area. The resistivities of the dentin tubule contents and smear layer material were generally lower than that of the hydrating electrolyte. It is postulated that this could be due to ions from partial dissolution of the mineral in the dentin.

Dentin↗
PubMed1989

[Should toothpastes foam? Sodium lauryl sulfate--a toothpaste detergent in focus].

Sodium lauryl sulfate is one of the most widely used synthetic detergents in toothpaste. Generally, surface active agents lower the surface tension, penetrate and loosen surface deposits and emulsify or suspend the debris which the dentifrice removes from the tooth. The concentration in dentifrices usually ranges from 0.5-2.0%. It has previously been shown that sodium lauryl sulfate has the potential to initiate hypersensitivity to metal ions. Furthermore, the mucosal permeability will be increased to oil and water soluble compounds. Experiments from this laboratory indicate that sodium lauryl sulfate will interact with the deposition of fluoride on dental enamel. It is furthermore suggested that this interaction may have the potential to decrease the cariostatic effect of fluorides. Clinical studies from Denmark give support to this statement. In conclusion, sodium lauryl sulfate has some side effects, and future work should therefore be concentrated on finding other possible toothpaste detergents without these side effects.

Dentifrices↗
PubMed1982

Formation of tight junctions in differentiating and secretory ameloblasts of rat molar tooth germs.

Forty newborn rats were perfused with Karnovsky fixative and the tight junctions in differentiating and secretory ameloblasts were examined by conventional electron microscopy and freeze-fracture replications. Pre-ameloblasts were divided into types I, II and III based on morphology. Initial indications of tight-junction formation appeared as linear aggregations of particles in type II. The apparent tight junctional strands were observed in type III and in secretory ameloblasts. Though the junctional strands were numerous and long, no complete barrier between pre-ameloblasts at their distal ends was present. Complete zonular tight junctions were first observed at the distal ends of secretory ameloblasts; at this stage, proximal tight junctions incompletely sealed the paracellular spaces around the ameloblasts. Throughout their formative processes, the tight junctional strands were engaged in forming gap junctions. The structural features of tight junctions were considered to be closely associated with the cytodifferentiation of ameloblasts and permeability in the ameloblast layer.

Ameloblasts↗
PubMedDate not supplied

Microshear bond strength of resin composite to teeth affected by molar hypomineralization using 2 adhesive systems.

PURPOSE: When restoring hypomineralized first permanent molars, placement of cavo-surface margins can be difficult to ascertain due to uncertainty of the bonding capability of the tooth surface. The purpose of this study was to investigate the adhesion of resin composite bonded to control and hypomineralized enamel with an all-etch single-bottle adhesive or self-etching primer adhesive. METHODS: Specimens of control enamel (N=44) and hypomineralized enamel (N=45) had a 0.975-mm diameter composite rod (Filtek Supreme Universal Restorative) bonded with either 3M ESPE Single Bond or Clearfil SE Bond following manufacturers' instructions. Specimens were stressed in shear at 1 mm/min to failure (microshear bond strength). Etched enamel surfaces and enamel-adhesive interfaces were examined under scanning electron microscopy. RESULTS: The microshear bond strength (MPa) of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel (3M ESPE Single Bond=7.08 +/- 4.90 vs 16.27 +/- 10.04; Clearfil SE Bond=10.39 +/- 7.56 vs 19.63 +/- 7.42; P=.001). Fractures were predominantly adhesive in control enamel and cohesive in hypomineralized enamel. Scotchbond etchant produced deep interprismatic and intercrystal porosity in control enamel and shallow etch patterns with minimal intercrystal porosity in hypomineralized enamel. Control enamel appeared almost unaffected by SE Primer; hypomineralized enamel showed shallow etching. The hypomineralized enamel-adhesive interface was porous with cracks in the enamel. The control enamel-adhesive interface displayed a hybrid layer of even thickness. CONCLUSIONS: The microshear bond strength of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel. This was supported by differences seen in etch patterns and at the enamel-adhesive interface.

Acid Etching, Dental↗
PubMed2003

Morphological characterization of the resin-dentin interface in primary teeth.

The effects of self-etching adhesives on primary teeth were evaluated. Reports in the literature suggest differences between the first and second dentition regarding the composition and the morphology and, therefore, a possible difference in the performance of dental adhesives. The purpose of this study was to evaluate the effects of self-etching adhesives on primary dentin. Eight dentin disks were obtained from the occlusal surface of primary molars. The disks were divided between four dental adhesives [Prompt L-PoP (LP), Clearfil SE BOND (SE), Etch&Prime 3.0 (EP) and Prime&Bond NT (PB) + H(3)PO(4) (Control) and "restored" with a composite (Pertac II)]. After sectioning, fixation and HMDS drying, specimens were polished and Field Emission SEM examinations were carried out. Clearly visible hybrid layer formation was found for PB, LP and EP. An undoubtedly detectable interdiffusion zone was not evident after the use of SE. A clearly visible adhesive layer was recognizable for PB, EP and SE, but not continuously detectable for LP. Debonded regions were observed for all systems evaluated, but distinct differences in the failure mode were detected. The evaluated dental adhesives did not generate completely sealed interfaces between the composite resin and the dentin of primary teeth in vitro.

Acid Etching, Dental↗
PubMed1977

A comparative study of five materials for use in filling root canal spaces.

The purpose of this study was dual: (1) to test the adaptation of various filling materials to the walls of instrumented root canals and (2) to test which of the experimental materials can be utilized with the pressure syringe. The root canal spaces of 210 extracted permanent anterior teeth were instrumented and, with the pressure syringe, the canals and access cavities were filled with a sealer or cement. Teeth filled with laterally condensed gutta-percha and sealer, and with a silver cone plus laterally condensed gutta-percha and sealer served as the controls. Except for the apical openings, the roots were coated with sticky wax and then placed in methylene blue dye at 37 degrees C. for periods of 1 day, 1 week, and 1 month. The teeth were removed from the dye and sectioned longitudinally, and the length of the dye penetration between the filling and the canal wall was measured. Of all materials tested, the silver point control exhibited the least amount of marginal seepage at each time period. AH-26 exhibited the least amount of marginal seepage after 30 days as compared to the other experimental materials and the gutta-percha control, and was the easiest material to handle of all those tested. Since gutta-percha has been shown to be clinically successful, and since it did not differ significantly in dye seepage from the other materials, all materials tested will give a satisfactory result up to 30 days when used as a root canal sealer under these testing conditions.

Acrylic Resins↗
PubMed2005

Influence of specimen size and regional variation on long-term resin-dentin bond strength.

OBJECTIVES: Verify whether the dimension of a bonded specimen stored prior microtensile testing and its regional variation may affect the resin-dentin bond strength (BS) over time. METHODS: Thirty human third molars had a flat dentin surface exposed and all peripheral enamel removed. Two adhesive systems (Single-Bond and One-Step) were applied and composite resin crowns (Z250) were constructed. Teeth were divided into three groups (n = 5). Group A specimens were sectioned to obtain sticks to be tested in tension (0.5 mm/min) immediately. Group B specimens were stored in water for 6 months, before sectioning and testing. Group C specimens were sectioned; the sticks were stored for 6 months and tested. In groups A and B, the origin of the sticks, periphery and inner regions was controlled. Bond strength (BS) was expressed as an index that considers cohesive failures and estimated values of premature debonded specimens. One-way ANOVA and Tukey's test (alpha = 0.05) were used to compare groups A, B and C, and a second analytical approach (A and B) employed a two-way ANOVA (time versus regional differences) for each adhesive system. RESULTS: For Single-Bond (SB), the BS for specimens in group A was higher than for groups B and C. For One-Step (OS), the BS in group A was higher than for B, which was in turn higher than for C. In the second group approach, no difference was found when the test was performed immediately; however, after 6 months, the inner sticks from group B showed significantly higher BS. SIGNIFICANCE: (1) The amount of decrease in BS is dependent on the specimen size; (2) the decrease in BS was greater for peripheral specimens than more centrally located specimens.

Analysis of Variance↗
PubMed2005

Sealer penetration and apical microleakage in smear-free dentin after a final rinse with either 70% isopropyl alcohol or Peridex.

Tensioactive agents may alter dentinal wettability allowing increased sealer penetration into dentinal tubules. This may improve the apical seal and better entomb remaining bacteria. The purpose of this study was to determine if a final rinse with either 70% isopropyl alcohol or Peridex in instrumented, smear-free canals would affect apical microleakage or Roth's 801 sealer penetration into dentinal tubules. Sixty root segments were instrumented followed by smear layer removal. The segments were randomly divided into three groups receiving a final rinse with 6% sodium hypochlorite (NaOCl), 70% isopropyl alcohol or Peridex. Obturation was completed using lateral compaction and Roth's 801 sealer pigmented with carbon black. Microleakage was measured by fluid filtration. Sealer penetration was measured using light microscopy. No significant differences were found between groups for microleakage or sealer penetration. Although a final rinse with either 70% isopropyl alcohol or Peridex did not increase sealer penetration, neither significantly affected apical microleakage compared to NaOCl.

2-Propanol↗
PubMed2005

Effect of ProRoot MTA mixed with chlorhexidine on apoptosis and cell cycle of fibroblasts and macrophages in vitro.

AIM: To compare the percentage of apoptotic cells and the cell cycle profile of fibroblasts and macrophages exposed to either ProRoot mineral trioxide aggregate (MTA) mixed with chlorhexidine (CHX), or exposed to ProRoot MTA mixed with sterile water. METHODOLOGY: Mouse gingival fibroblasts or mouse macrophages were seeded in six-well plates and allowed to attach overnight. Freshly mixed or set (allowed to dry for 24 h) specimens of tooth-coloured (white) ProRoot MTA were prepared with 0.12% CHX gluconate (MTA/CHX) or with sterile water (MTA/H2O). The cells were exposed for 24 h to the MTA specimens, which were placed over permeable membrane inserts to avoid direct contact with the cells. Untreated cells served as controls. Propidium iodide staining followed by flow cytometry was used to evaluate the effects of ProRoot MTA on cell apoptosis and cell cycle. Statistical analyses were performed by one-way anova followed by post-hoc tests with the use of the SigmaStat 2.0 software, and significance was determined at P < or = 0.05. RESULTS: MTA specimens containing CHX induced apoptosis of macrophages and fibroblasts (P < 0.05). In contrast, no change in the proportion of apoptotic cells was observed when sterile water was used to prepare the specimens (P > 0.05). Cell cycle analysis showed that exposure to MTA/CHX decreased the percentage of fibroblasts and macrophages in S phase (DNA synthesis) as compared with exposure to MTA/H2O (P < 0.05). CONCLUSION: This in vitro study demonstrated that the substitution of CHX for sterile water in MTA increases its cytotoxicity. This suggests that the potentially beneficial antimicrobial effect of CHX may be accompanied by an increase in the cytotoxicity of the resulting MTA-based material.

Aluminum Compounds↗
PubMed2005

Continuing etching of an all-in-one adhesive in wet dentin tubules.

Self-etch adhesives that etch and prime simultaneously are becoming more acidic. We hypothesized that the degree of acidic monomer conversion at the interface and within the tubules was high enough that the acidic reaction would be very self-limiting. Dentin surfaces prepared from extracted, unerupted human third molars were treated with Prompt L-Pop (3M ESPE). The prepared teeth were stored in normal saline, and specimens retrieved at intervals < or = 4 wks were randomly selected for light, scanning electron microscopic and micro-Raman spectroscopic analysis. Morphologic and spectroscopic analyses indicated dentin demineralization and adhesive penetration throughout the demineralized layer and tubules. Increased dentin demineralization and loss of adhesive integrity were noted after aqueous storage. The degree of monomer conversion at the interface was consistently greater than conversion within the tubules. Fluid within the tubules may inhibit monomer conversion. The acidic characteristics of this adhesive may be retained and, thus, continue to affect/demineralize the surrounding dentin.

Acid Etching, Dental↗