Duration of dentin tubule occlusion by the calcium phosphate precipitation method: An in vivo study in beagle dogs.

The aim of the present study was to assess the duration of dentin tubule occlusion by the calcium phosphate precipitation (CPP) method in the vital teeth of beagle dogs. Vital teeth were treated using the CPP method, potassium oxalate, or a bonding agent (Liner bond II) after cavity preparation and acid etching. The dentin tubules of all groups, except for the bonding agent, opened more widely with time in the absence of plaque control. Dentin tubules treated with the CPP method were open and no precipitate remained in the absence of plaque control. Differences were observed in dentin tubule occlusion when plaque control was achieved by daily tooth brushing. The majority of dentin tubules were occluded with an apatitic precipitate seven days after the CPP method with plaque control. The present results demonstrated that the CPP method is useful with proper plaque control.

Effects of toothpaste containing surface pre-reacted glass-ionomer (S-PRG) filler on crystallinity and acid resistance of hydroxyapatite.

PURPOSE: To examine the acid resistance of experimental toothpaste containing different wt% of surface pre-reacted glass-ionomer (S-PRG) filler. METHODS: Hydroxyapatite (HAP) pellets were treated with toothpaste containing 0, 1, 5, 10, 20, or 30 wt% S-PRG filler for 5 minutes. A demineralization and remineralization cycle was repeated for 7 days. The demineralized depths of the pellets were measured using a surface roughness analyzer. The crystallinity of both HAP and dicalcium phosphate dehydrate (DCPD) after the S-PRG treatment was measured by a powder X-ray diffraction (XRD) analysis. Fluoride gel (9,000 ppmF) was used for comparison. RESULTS: The demineralizd depth decreased with increases in the S-PRG filler concentration. The demineralized depth with the 30 wt% S-PRG treatment (4.6 µm ± 2.0) was slightly greater than that with the fluoride gel (3.3 µm ± 0.5), but not significantly different (P< 0.05). However, significant differences were observed in demineralized depths between the fluoride gel and the other wt% of S-PRG tested (P< 0.05). In the XRD analysis, no crystallinity changes were noted in HAP or DCPD after the S-PRG or fluoride gel treatments. The formation of calcium fluoride was not detected in any treatment group. CLINICAL SIGNIFICANCE: The results demonstrated the effectiveness of the toothpaste containing 30 wt% S-PRG filler for inhibiting the demineralization of HAP pellets. However, the toothpaste containing S-PRG filler prevented demineralization less effectively than the fluoride gel.

Fluoride activity of antibacterial ammonium hexafluorosilicate solution for the prevention of dentin caries.

PURPOSE: To evaluate the acid resistance of various antibacterial ammonium hexafluorosilicate (SiF) solutions. METHODS: Antibacterial SiF solutions were prepared with the addition of chlorhexidine (CHX), cetylpyridinium chloride (CPC), isopropyl methylphenol (IPMP), or epigallocatechin gallate (EGCG). Hydroxyapatite pellets were treated with SiF solution with or without antibacterial agents for 3 minutes. The demineralized depth of hydroxyapatite pellets after SiF treatment was measured using a surface roughness analyzer. RESULTS: SiF+CPC solution showed equivalent acid resistance to SiF and AgF treatment. In contrast, the original acid resistance activity of SiF solution was diminished by the addition of other antibacterial agents (CHX, IPMP and EGCG). SiF with the addition of CPC was the most effective for reducing the demineralized depth, showing the same levels as those of SiF and AgF. CLINICAL SIGNIFICANCE: The addition of CPC to the SiF solution did not reduce its fluoride activity, indicating that it may be useful for the prevention of dental caries. SiF with added antibacterial agents may have the potential to prevent dental caries.

Changes in the crystallinity of hydroxyapatite powder and structure of enamel treated with several concentrations of ammonium hexafluorosilicate.

PURPOSE: To evaluate the effects of changing concentrations of ammonium hexafluorosilicate [SiF: (NH4)2SiF6] solution on the crystallinity of hydroxyapatite powder (HAP) and structure of human enamel in order to overcome the tooth discoloration caused by diamine silver fluoride [AgF: (NH3)2AgF] application. METHODS: HAP was treated with several concentrations of SiF solution (from 10 to 19,400 ppm) for 5 minutes. The crystallinity of the HAP before and after SiF treatment was then measured by powder X-ray diffraction (XRD) analysis. The angular width (beta) of the 002 diffraction peak was measured at 1/2 the height of the maximum intensity. Also, enamel specimens were prepared from a human extracted tooth. Several concentrations of SiF solution were applied to polished or phosphoric acid etched enamel specimens. The enamel surface was then observed using scanning electron microscopy (SEM). RESULTS: XRD peaks became sharper after SiF treatment indicating that the crystallinity of apatite powder was increased. The 1/beta value was increased from 2.8 +/- 0.1 to 4.3 +/- 0.1 after treatment with 1,000 ppm SiF solution. The amount of CaF2 formed in HAP was gradually increased with increasing concentrations of SiF solution. TheXRD pattern was consistent with CaF2 in case of over 9,000 ppm SiF solution. SEM photographs demonstrated that exposed enamel rods with acid etching were filled with CaF2-like precipitate after SiF treatment regardless of the concentration of SiF solution.

Antibacterial activity of ammonium hexafluorosilicate solution with antimicrobial agents for the prevention of dentin caries.

PURPOSE: This study evaluated the antibacterial activity of the SiF solution with the addition of antibacterial agents on a Streptococcus mutans biofilm. METHODS: Various antibacterial SiF solutions were prepared by adding chlorhexidine, cetylpyridinium chloride, isopropyl methylphenol, or epigallocatechin gallate. Hydroxyapatite pellets treated with several SiF solutions were immersed in BHI inoculated with S. mutans standardized suspension. The number of S. mutans cells adhered to each pellet was evaluated. RESULTS: SiF with the addition of CPC was the most effective for reducing the adherence of bacteria and inhibiting the formation ofbiofilm, showing the same level as AgF, In contrast, the addition of other antibacterial agents to SiF reduced the original antibacterial activity of SiF solution.

Reinforcement of bond strength of self-etching orthodontic adhesive.

OBJECTIVE: To determine the reinforcement of bond strength of a self-etching system by applying a pretreatment agent. MATERIALS AND METHODS: Sixty extracted human premolars were used in this study. The enamel surfaces were treated with four pretreatment agents-phosphoric acid, polyacrylic acid, citric acid, and ammonium hexafluorosilicate (SiF)-and were examined under a scanning electron microscope. Afterward, orthodontic brackets were bonded with a self-etching adhesive system (n  =  10 for each agent), and shear bond strength was measured through a debonding process. The adhesive remnant index (ARI) was also assessed. RESULTS: Enamel surfaces treated with polyacrylic acid seemed almost the same as intact enamel. Treatment with SiF induced slight shallow depressions compared with the intact enamel. On the other hand, enamel surfaces treated with citric acid and phosphoric acid showed severe etching patterns. All pretreatments increased the bond strength, but SiF-treated specimens revealed the greatest strength (12.201 ± 1.048 MPa), followed by polyacrylic acid (12.030 ± 2.103 MPa). The control group with no pretreatment showed the least strength (9.078 ± 1.678 MPa). All pretreatments increased ARI score compared with the control group. CONCLUSIONS: Surface conditioning before bracket adhesion could reinforce the bond strength of the self-etching adhesive system, resulting in a more reliable bonding system.

Occlusion of dentin tubules with antibacterial ammonium hexafluorosilicate solution for the prevention of dentin caries.

PURPOSE: To evaluate the degree of penetration of an ammonium hexafluorosilicate [SiF: (NH4)2SiF6] solution containing various antibacterial agents into dentin and the depth of dentin tubule occlusion by the precipitate. METHODS: Various antibacterial SiF solutions were prepared with the addition to chlorhexidine (CHX), cetylpyridinium chloride (CPC), isopropyl methylphenol (IPMP), or epigallocatechin gallate (EGCG), respectively. Two types of dentin disks were prepared from extracted teeth. One was a dentin surface covered with a smear layer, and the other treated with EDTA for 2 minutes to remove the smear layer and open dentin tubules. Then, the disks were treated with SiF solution with or without antibacterial agents for 3 minutes. The dentin surface and a longitudinally divided surface were observed with scanning electron microscopy (SEM) immediately after SiF treatment and after immersion in synthetic saliva for 7 days. RESULTS: SEM photographs demonstrated that dentin tubules after treatment with SiF were occluded homogeneously and similar to those on conventional SiF treatment regardless of the addition of an antibacterial agent. However, the depth of occlusion became significantly shallower when SiF was applied to dentin specimens covered with a smear layer.

Effects of ammonium hexafluorosilicate concentration on dentin tubule occlusion and composition of the precipitate.

UNLABELLED: Ammonium hexafluorosilicate [SiF: (NH(4))(2)SiF(6)] was prepared in order to overcome the tooth discoloration caused by diamine silver fluoride [AgF: (NH(3))(2)AgF] application. We employed a single concentration of SiF solution in our previous study; therefore, it is still unclear how the concentration of SiF solution affects the occlusion of dentin tubules and composition of the precipitate. OBJECTIVE: The aim of this study was to evaluate the effects of changing the concentration of SiF on its clinical use as a dentin hypersensitivity treatment. METHODS: To simulate dentin tubules subject to dentin hypersensitivity, dentin disks were treated with EDTA for 2 min. Then, the disks were treated with several concentrations of SiF solution (from 100 to 19,400 ppm) for 3 min. The occlusion of dentin tubules was evaluated using scanning electron microscopy (SEM), and the composition of the precipitate formed in the tubules after SiF treatment was assessed using energy dispersive X-ray analysis (EDXA). RESULTS: SEM photographs demonstrated that dentin tubules after treatment with SiF were occluded homogeneously and fully regardless of the concentration of SiF solution. The Ca/P molar ratio of the precipitate formed in dentin tubules after SiF treatment was increased with the concentration of SiF solution. SIGNIFICANCE: It was concluded that the capacity to occlude dentin tubules was the same regardless of the concentration of SiF solution. However, the composition of the precipitate formed in the tubules was dependent on the concentration of SiF solution.

Effects of calcium phosphate precipitation method on acid resistance to apatite powder and bovine tooth.

The aims of this study were to evaluate the effects of CPP method on the crystallinity of apatite powder and on the acid resistance of bovine enamel. Crystallinity degrees of apatite powder before and after CPP treatment were measured by powder X-ray diffraction analysis. Polished bovine enamel specimens treated with CPP method or NaF were immersed in a lactic acid solution for up to five days. The demineralized depth of enamel was measured with a surface roughness analyzer. XRD peaks became sharper after the CPP treatment, indicating an increased crystallinity of the apatite powder. The demineralized depth of bovine enamel treated with CPP method was shallower than that of enamel treated with NaF. Results of this study revealed that the CPP method increased the crystallinity of apatite powder and the acid resistance of enamel. Therefore, the CPP method would be useful not only for treating dentin hypersensitivity, but also for the prevention of dental caries.

Ammonium hexafluorosilicate elicits calcium phosphate precipitation and shows continuous dentin tubule occlusion.

UNLABELLED: Diamine silver fluoride [AgF: (NH(3))(2)AgF] has been used clinically in Japan, as it reduces dental caries and dentin hypersensitivity. However, AgF stains the teeth black due to silver precipitation. To overcome this drawback, the authors prepared ammonium hexafluorosilicate [SiF: (NH(4))(2)SiF(6)], which does not stain the teeth, and SiF occluded open dentin tubules completely with silica-calcium phosphate precipitate. OBJECTIVES: The aim of this study was to evaluate the duration of dentin tubule occlusion after SiF treatment in a simulated oral environment. METHODS: To simulate dentin tubules subject to dentin hypersensitivity, dentin disks were treated with EDTA for 2 min. The disks were treated with 0.476 mol/L SiF for 3 min, and then the disks were immersed in synthetic saliva, which was regularly replenished to maintain its ionic concentration, for up to 7 days. The occluding ability of the dentin tubules was evaluated using scanning electron microscopy (SEM), and the hydraulic conductance was measured following Pashley's method at regular intervals. RESULTS: SEM photographs demonstrated that dentin tubules were occluded homogeneously and completely with the precipitate at 7 days after treatment with SiF. In addition, newly formed calcium phosphate precipitate was present at the dentin surface. The dentin permeability showed a consistently low value throughout the experimental period. The values immediately after SiF treatment and 7 days after immersion were 11.9+/-3.7% and 7.9+/-2.9%, respectively. SIGNIFICANCE: Ammonium hexafluorosilicate is useful for the treatment of dentin hypersensitivity, since ammonium hexafluorosilicate induced calcium phosphate precipitation from the saliva; therefore, it has a continuous effect on dentin tubules occlusion under a simulated oral environment.

Effect of ammonium hexafluorosilicate on dentin tubule occlusion for the treatment of dentin hypersensitivity.

PURPOSE: To evaluate the occluding ability of ammonium hexafluorosilicate (SiF). METHODS: Dentin disks prepared from human extracted teeth were grouped as follows to prepare different situations of dentin hypersensitivity: (1) those sonicated for 20 minutes; (2) those treated with 0.5 mol/L EDTA for 2 minutes; (3) those treated with 6% citric acid for 2 minutes; (4) those treated with 50% citric acid for 2 minutes. Then, SiF or diamine silver fluoride (AgF) was applied to the dentin disks and the dentin tubule occlusion was observed with scanning electron microscopy (SEM). The percent of open tubules before and after SiF or AgF treatment were measured by NIH image using SEM photographs. Also, the dentin permeability was measured. RESULTS: SEM micrographs demonstrated that the dentin tubules were completely occluded by the precipitate after SiF treatment. Also, the dentin permeability was reduced to 10.3%. In contrast, most of the dentin tubules remained open after AgF treatment. EDXA analysis showed that the precipitate in the dentin tubules that forms after SiF treatment contains Si, Ca and P, indicating a silica-calcium phosphate complex.

Effects of plaque control on the patency of dentinal tubules: an in vivo study in beagle dogs.

BACKGROUND: The aim of this in vivo study was to evaluate the effects of plaque control on the patency of dentinal tubules using vital teeth of beagle dogs. METHODS: Class V cavities were prepared on the cervical areas of the mandibular and maxillary molars in each dog with a diamond point. To simulate the state of dentinal hypersensitivity, the teeth were etched with 50% citric acid for 2 minutes to obtain patent dentinal tubules. Plaque control was achieved by brushing the left-side teeth every day, whereas no plaque control was performed for the right-side teeth. A dentin biopsy was performed after 1, 2, and 3 weeks using the cylindrical diamond point to obtain dentin specimens. RESULTS: In the plaque control group, some of the dentinal tubules were occluded with precipitate (Ca/P=1.49), and the diameter of the dentinal tubules decreased from 2.42+/-0.33 microm (mean+/-SD) to 1.11+/-0.51 microm after 7 days, although most of the dentinal tubules remained open. In contrast, no precipitate was observed in the dentinal tubules of the non-plaque control group. Also, the diameter of the dentinal tubules increased from 2.42+/-0.33 to 2.9+/-0.49 microm, due to the demineralization of the peritubular and intertubular dentin. CONCLUSION: Plaque control plays a key role in reducing the patency of dentinal tubules and, therefore, might promote the natural repair of dentinal hypersensitivity.

Effects of pre- or post-application of calcium chloride on occluding ability of potassium oxalate for the treatment of dentin hypersensitivity.

PURPOSE: To evaluate whether calcium ion supply using 1-6 mol/L CaCl2 solution could enhance the occluding ability of dentin tubules with 30% potassium oxalate treatment. METHODS: Calcium chloride solution (1-6 mol/L) was applied to dentin disks before or after application of 30% potassium oxalate solution. Occluding ability after potassium oxalate treatment was evaluated with scanning electron microscopic (SEM) observation and measurement of dentin permeability. In addition, the composition of the precipitate formed when mixing potassium oxalate and calcium chloride was analyzed with a powder x-ray diffractometer (XRD). RESULTS: SEM observations revealed that the dentin tubules were occluded homogeneously and completely with the precipitate when calcium chloride solution was applied before or after potassium oxalate treatment. However, the depth of the precipitate in dentin tubules from the dentin surface became shallower when pre-treated with calcium chloride before potassium oxalate. Although dentin permeability was greatly reduced in both groups, no significant difference could be observed between samples with and without calcium chloride application.

Comparison of the occluding ability of dentinal tubules with different morphology between calcium phosphate precipitation method and potassium oxalate treatment.

The aim of this study was to evaluate the occluding ability of calcium phosphate precipitation (CPP) method and potassium oxalate treatment when each method was applied to dentin disks with different surface morphology. Occluding ability was observed by scanning electron microscopy. Irrespective of the diameter of the dentinal tubules, the CPP method showed a consistent occluding ability for dentinal tubules at the dentin surface, and that the depths of the precipitate formed in the dentinal tubules by CPP method were not significantly different. In contrast, the occluding ability of potassium oxalate treatment was reduced with increasing diameter of the dentinal tubules. However, the reduction of the occluding ability of potassium oxalate treatment was more markedly affected by the demineralization of dentin surface. Since the CPP method showed a consistent occluding ability irrespective of the diameter of the dentinal tubules, it is suggested that the CPP method would be a useful means for treating dentin hypersensitivity.

Calcium phosphate precipitation method for the treatment of dentin hypersensitivity.

PURPOSE: To evaluate the feasibility of the calcium phosphate precipitation (CPP) method as a treatment for dentin hypersensitivity using vital teeth of beagle dogs. Also, gingival tissue response to two types of CPP methods was examined histologically. MATERIALS AND METHODS: Dentin tubules of the dogs' vital teeth were exposed by shallow cavity preparation followed by etching with 50% citric acid to simulate the condition of hypersensitive dentin. After CPP treatment was applied to the vital tooth, the dentin surface and longitudinal sections were observed by SEM to evaluate the occluding ability of the CPP method. The precipitate was also analyzed by energy-dispersive X-ray microanalysis to obtain compositional information. The gingival tissue before and after CPP method was examined histologically with light microscopy. RESULTS: Dentin tubules were occluded homogeneously and completely with an apatitic mineral after application of the CPP treatment in vital teeth. However, the depth of the precipitate in dentin tubules from the dentin surface was approximately half that seen in extracted teeth. No histological change was observed in gingival tissues when NaHCO3 was used as a post-treatment solution of the CPP method, whereas another CPP method using NaOH solution resulted in atrophy and degeneration of the epithelium of gingival tissue.