Effect of different sizes of bioactive glass-coated mesoporous silica nanoparticles on dentinal tubule occlusion and mineralization.

OBJECTIVES: To synthesize two different sizes of bioactive glass-coated mesoporous silica nanoparticles (BGN@MSNs) and to investigate their effects on dentinal tubule occlusion and remineralization. MATERIALS AND METHODS: Two different sizes of mesoporous silica nanoparticles (MSNs) were synthesized using the Stöber method (368A, 1840A) and coated with bioactive glass nanoparticles (BGNs) using a modified quick alkali-mediated sol-gel method (368B, 1840B). Sensitive tooth disc models were prepared and divided into six groups and the following treatments were applied: group 1-no treatment, group 2-bioglass, group 3-368A, group 4-368B, group 5-1840A, and group 6-1840B. Then, five discs were selected from each group and soaked in 6 wt% citric acid to test acid resistance. Dentinal tubule occlusion and occlusion ratio were observed using field-emission scanning electron microscopy. In vitro mineralization tests using simulated body fluid solution were performed to evaluate the remineralization effect of the treatment. RESULTS: All samples effectively occluded the dentinal tubule and formed a membrane-like layer. After acid treatment, 1840B (group 6) exhibited the highest rate of dentinal tubule occlusion. Remineralization was observed in 368B and 1840B, and 1840B exhibited the fastest remineralization. CONCLUSIONS: Dentinal tubule remineralization induced by the BGN@MSN biocomposite can be used to stabilize long-term prognosis in dentin hypersensitivity. The 1840B induced the most efficient remineralization, and its smaller size and larger surface area were effective for remineralization. CLINICAL RELEVANCE: The BGN@MSN biocomposite with its smaller size and larger surface area was more effective for remineralization and dentinal tubule sealing.

Dentin sealing and antibacterial effects of silver-doped bioactive glass/mesoporous silica nanocomposite: an in vitro study.

OBJECTIVES: To synthesize a silver-doped bioactive glass/mesoporous silica nanoparticle (Ag-BGN@MSN), as well as to investigate its effects on dentinal tubule occlusion, microtensile bond strength (MTBS), and antibacterial activity. MATERIALS AND METHODS: Ag-BGN@MSN was synthesized using a modified "quick alkali-mediated sol-gel" method. Demineralized tooth disc models were made and divided into four groups; the following treatments were then applied: group 1-no treatment, group 2-bioglass, group 3-MSN, group 4-Ag-BGN@MSN. Next, four discs were selected from each group and soaked into 6 wt% citric acid to test acid-resistant stability. Dentinal tubule occlusion, as well as the occlusion ratio, was observed using field-emission scanning electron microscopy. The MTBS was also measured to evaluate the desensitizing effect of the treatments. Cytotoxicity was examined using the MTT assay. Antibacterial activity was detected against Lactobacillus casei, and ion dissolution was evaluated using inductively coupled plasma optical emission spectrometry. RESULTS: Ag-BGN@MSN effectively occluded the dentinal tubule and formed a membrane-like layer. After the acid challenge, Ag-BGN@MSN had the highest rate of dentinal tubule occlusion. There were no significant differences in MTBS among the four groups (P > 0.05). All concentrations of Ag-BGN@MSN used had a relative cell viability above 72%. CONCLUSIONS: Ag-BGN@MSN was successfully fabricated using a modified sol-gel method. The Ag-BGN@MSN biocomposite effectively occluded dentinal with acid-resistant stability, did not decrease bond strength in self-etch adhesive system, had low cytotoxicity, and antibacterial effect. CLININAL RELEVANCE: Dentinal tubule sealing induced by Ag-BGN@MSN biocomposite with antibacterial effect is likely to increase long-term stability in DH.

Reducing dentine hypersensitivity with nano-hydroxyapatite toothpaste: a double-blind randomized controlled trial.

OBJECTIVES: The present randomized double-blind clinical trial aimed to compare the efficacy in reducing dentin hypersensitivity of a dentifrice formulation containing nano-hydroxyapatite with a fluoride dentifrice and a placebo. METHODS AND MATERIALS: One hundred and five subjects were recruited to participate in the study. A computer-generated random table with blocking to one of the three study treatments was used in order to have 35 subjects per group: (1) nano-hydroxyapatite 2% gel toothpaste fluoride free; (2) fluoride gel toothpaste; (3) placebo. Groups 1, 2, and 3 were instructed to treat their teeth for 10 min twice a day with the provided toothpaste gel. The participant's dentin hypersensitivity was evaluated at baseline and after 2 and 4 weeks using airblast and tactile tests. In addition, a subjective evaluation using a visual analogue scale was used. RESULTS: Significant lower values of cold air sensitivity and tactile sensitivity (p < 0.05) were found for the test group at 2 weeks and 4 weeks. In addition, statistically significant (p < 0.05) lower values of sensitivity were reported for group 1 compared to those for groups 2 and 3 at 2 and 4 weeks, respectively. The VAS scores were significantly lower (p < 0.05) in the test group at 2 and 4 weeks compared to those at baseline and in the control groups. CONCLUSION: The application of nano-hydroxyapatite in gel toothpaste fluoride free is an effective desensitizing agent providing relief from symptoms after 2 and 4 weeks.

Study of three types of desensitizers in dentin bonding strength.

One hundred and twenty human molars without decay (premolars and complete third molars) freshly extracted for orthodontic purposes were used in the study to explore the impact of application of three kinds of desensitizers on self-etching/all-etching bond strength of dentin. The roots were ground along the cementoenamel junction (CEJ), the residual crowns were divided into two parts along mesial and distal direction, and the enamel layer was removed. The dentin was ground into standard pieces of 3x3x3 mm and then polished using alumina waterproof abrasive paper. Two hundred and forty specimens were divided into two groups according to self-etching bond (OptiBond, iBond, XenoIV) and all-etching bond (OptiBond, iBond, Probond). Each of the two groups were subdivided into three groups with different brands, and then further subdivided into three experimental groups and a control group (10 samples in each final group). The surface of dentin coated with desensitizer was examined using scanning electron microscope. Results showed that only the shear strength of iBond + Ddes + Z100 resin group was lower compared to the control group (P < 0.05). The comparison of the resin shear strength in other experimental groups with the control groups demonstrated no statistically significant difference (P > 0.05). The shear strength of Optibond + Gluma, Optibond + Ddes, iBond + Ddes + Z100 resin group in all-etching bond group and the experimental groups in Probond group was lower than in the control group (P < 0.05). The resin shear strength in other groups did not differ from the controls (P > 0.05).

Efficacy of desensitizing products containing 8% arginine and calcium carbonate for hypersensitivity relief in MIH-affected molars: an 8-week clinical study.

OBJECTIVES: The objective of this study was to compare the efficacy in reducing hypersensitivity in molar incisor hypomineralization (MIH)-affected molars immediately and over 8 weeks combining a single in-office application and a homed-based program with desensitizing products containing 8% arginine and calcium carbonate. MATERIALS AND METHODS: Nineteen children with at least one MIH-affected molar with hypersensitivity were included. Hypersensitivity was assessed with an evaporative (air) stimulus and a tactile stimulus. Each child received a single in-office treatment with a desensitizing paste containing 8% arginine and calcium carbonate (elmex Sensitive Professional desensitizing paste), followed by 8 weeks of brushing twice daily with a desensitizing toothpaste containing 8% arginine, calcium carbonate with 1450 ppm fluoride (elmex Sensitive Professional toothpaste), using the elmex Sensitive Professional toothbrush. Additionally, the corresponding mouthwash (elmex Sensitive Professional mouthwash) was used. Clinical assessments were made at baseline, immediately after the in-office treatment and after 1, 2, 4 and 8 weeks of brushing twice daily. RESULTS: Fifty-six molars with an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were included. Application of the desensitizing paste decreased hypersensitivity significantly immediately and throughout the 8 weeks recalls (p < 0.001). CONCLUSIONS: In conclusion, 8% arginine and calcium carbonate were able to reduce hypersensitivity successfully during this 8-week trial. CLINICAL RELEVANCE: Hypersensitivity is a major complaint in patients with MIH. This is the first study evaluating the desensitizing effect of a desensitizing paste containing 8% arginine and calcium carbonate in patients with MIH.

Comparison of nanofluoridated hydroxyapatite of varying fluoride content for dentin tubule occlusion.

PURPOSE: To evaluate the viability of a series of nano-fluoridated hydroxyapatite (nano-FHA) formulations of varying fluoride content for the occlusion of exposed dentin tubules, in comparison to nano-hydroxyapatite (nano-HA). METHODS: Nano-FHA powders with varying levels of fluoride ion were synthesized to substitute hydroxyl ions (⁻OH) present in hydroxyapatite (HA). Nano-FHA were defined as 2nFHA,4nFHA,6nFHA, 8nFHA and 10nFHA, with the molar ratio of F(⁻ to Ca243; of 0.002,0.004,0.006,0.008 and 0.01, respectively. The powders were synthesized using a wet chemistry route, and characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The methylthiazol tetrazolium (MTT) assay was used to assess cell viability toward nano-FHA. According to the content of F⁻, the nano-nFHA and nano-HA powders were divided into six groups, with the artificial saliva as control. They were spread over the dentin surface for 1 minute and repeated three times per day for 7 consecutive days. After washing and brushing with distilled water for an additional 7 days, scanning electron microscopy was used to evaluate the in vitro plugging rate of the tubules and penetrating depth. RESULTS: The 2nFHA, 4nFHA, 6nFHA, 8nFHA and 10nFHA powders were prepared and characterized. The 8nFHA had less crystallinity compared to 2nFHA,4nFHA, and 6nFHA.The MTT assay (from 12 to 120 hours) showed that the cell viability of the L-929 fibroblasts in the 2nFHA, 4nFHA, 6nFHA, 8nFHA, 10nFHA, and nano-HA groups ranged from 80.54± 3.35% to 112.9± 4.8%. Most of the nano-FHA powders successfully occluded dentin tubules. The plugging rate of 8nFHA was significantly higher than that of the 2nFHA, 4nFHA, 6nFHA and nano-HA groups. The penetrating depth of the 8nFHA group into the tubules was also significantly higher than that of the other nano-FHA and nano-HA group. CLINICAL SIGNIFICANCE: The nano-FHA formulation 8nFHA showed higher plugging rate and penetrating depth into the tubules. It has the potential to be used as a desensitizing agent in treating dentin hypersensitivity with better long-term durability and efficacy of dentin tubule occlusion.

The effect of calcium phosphate-containing desensitizing agent on the microtensile bond strength of multimode adhesive agent.

OBJECTIVE: The aim of this study was to investigate the effect of calcium phosphate containing desensitizing pretreatments on the microtensile bond strength (MTBS) and microleakage of the multimode adhesive agent to dentin. MATERIALS AND METHODS: In this study, twelve noncarious, freshly extracted human third molar teeth for MTBS and 20 premolar teeth for the microleakage test were used. The teeth were restored using Clearfil Universal Bond + Clearfil APX and Teeth mate Desensitizer (TMD). For MTBS test, Group 1: Self-etch, Group 2: Etch and rinse (G1 and 2, nondesensitizer treatment served as a control), Group 3: TMD/self-etch, Group 4: Acid-etch/TMD/etch and rinse. For microleakage test, Class V adhesive cavities (3 mm × 2 mm × 2 mm) were prepared and restored as mentioned before. The restored teeth were subjected to thermal cycling. The MTBS test was performed in all procedures. The MTBS data were submitted to a one-way ANOVA and post hoc Tukey test (P P Results: Control groups exhibited a higher mean MTBS value than TMD groups, and there were statistical differences between the groups. TMD groups also demonstrated significantly less microleakage than control groups (P Conclusions: This study proves that the application of TMD with a multimode adhesive bonding system produced significantly lower MTBS and microleakage.

Management of dentine hypersensitivity: efficacy of professionally and self-administered agents.

CONTEXT: The gold standard treatment modality for dentine hypersensitivity has not yet been established. This review examines the effectiveness of self and professionally applied treatments for the reduction in pain from dentine hypersensitivity. MATERIALS AND METHODS: Electronic (three databases) and hand searches were performed 14-21 July 2014 to identify randomized controlled trials for the treatment of dentine hypersensitivity. RESULTS: This systematic review provided numerous treatment modalities for dentine hypersensitivity. Eleven agents and 105 Randomized Controlled Trials were robust enough to be included. The studies varied considerably in design, observation period, active agents, formulation of the whole agent, negative and positive controls and comparator products investigated. The stimuli used were predominantly airblast and tactile or thermal. Due to the heterogeneity between the studies and lack of direct comparison between agents there was insufficient data to undertake a meta-analysis to compare agents for meaningful conclusions. Best available evidence for each treatment agent has been documented as a narrative. CONCLUSIONS: Treatments including stannous fluoride, arginine, calcium sodium phosphosilicate and strontium toothpaste appear to be clinically effective for the treatment of dentine hypersensitivity compared to comparators and controls. There is limited evidence to confirm the relative effectiveness of individual professionally applied agents.

Effectiveness of a calcium sodium phosphosilicate-containing prophylaxis paste in reducing dentine hypersensitivity immediately and 4 weeks after a single application: a double-blind randomized controlled trial.

AIMS: The aim of this single-site, randomized, controlled, double-blind, 3-arm parallel study was to determine the effectiveness of a prophylaxis paste containing 15% calcium sodium phosphosilicate (CSPS; NovaMin(®) ) with and without fluoride in reducing dentine hypersensitivity immediately after a single application and 28 days following dental scaling and root planing. MATERIALS & METHODS: Overall, 151 subjects were enrolled in this study. All subjects received a scaling and root planing procedure followed by a final prophylaxis step using one of three different prophylaxis pastes: Test-A (15% NovaMin(®) and NaF), Test-B (15% NovaMin(®) ) and a control. Dentine hypersensitivity was assessed by tactile stimulus (Yeaple Probe(®) ) and by air blast (Schiff scale) at baseline, immediately after and 28 days after a prophylaxis procedure. One hundred and forty-nine subjects completed the study. RESULTS: Subjects having received the test prophylaxis pastes showed statistically lower (anova, p < 0.05) dentine hypersensitivity compared with the control group immediately after the prophylaxis procedure (Yeaple Probe(®) : Test-A = 20.9 ± 12.6, Test-B = 22.7 ± 12.9, Control=11.2 ± 3.1; Schiff score: Test-A = 1.1 ± 0.6, Test-B = 1.1 ± 0.6, Control = 2.0 ± 0.7) and after 28 days (Yeaple probe: Test-A = 21.5 ± 11.9, Test-B = 20.6 ± 11.3, Control = 11.8 ± 6.0; Schiff score: Test-A = 1.0 ± 0.6, Test-B = 1.0 ± 0.6, Control = 2.0 ± 0.7). CONCLUSIONS: In conclusion, the single application of both fluoridated and non-fluoridated prophylaxis pastes containing 15% CSPS (NovaMin(®) ) provided a significant reduction of dentine hypersensitivity up to at least 28 days.

Effect of pretreatment with calcium-containing desensitizer on the dentine bonding of mild self-etch adhesives.

Desensitizing agents are frequently applied to sensitive teeth and may affect subsequent resin bonding. The current study aimed to evaluate the bonding performance of two self-etch adhesives containing functional monomers to dentine pretreated with three new calcium-containing desensitizers. No desensitizer was applied in the control group. Groups 1, 2, and 3 were treated with an arginine-calcium carbonate-containing polishing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste, and an experimental hydroxyapatite paste, respectively. G-Bond and Clearfil S(3) Bond were used for bonding after desensitizer treatments. The microtensile bond strength (µTBS) was tested (n = 20 beams per group) and failure mode distribution was analyzed. Scanning electron microscopy was used to observe the occlusion of dentinal tubules. The mean (±SD) µTBS values, expressed in MPa, of groups 1, 2, and 3 and the control group were, respectively, 30.81 (7.79), 44.41 (8.02), 31.49 (6.13), and 41.40 (8.67) for G-Bond and 39.63 (9.59), 32.55 (7.86), 37.50 (8.60), 27.90 (6.52) for S3 Bond. Most failures were recorded as adhesive failure (69.375%), instead of cohesive failure or mixed failure. The dentinal tubules were seldom plugged in group 2, but were mostly occluded in groups 1 and 3. Two-way anova indicated that desensitizer application in association with a compatible adhesive system should be used when endeavoring to control hypersensitivity without adverse interference in bonding.

Effects of oxalate desensitizer with different resin cement-retained indirect composite inlays on fracture resistance of teeth.

PURPOSE: This study investigated whether the tubular occluding effect of oxalate desensitizer (OX) during adhesive cementation (three resin cements) influenced fracture resistance of teeth restored with adhesive inlays. MATERIALS AND METHODS: Ninety intact maxillary premolars were randomly divided into 9 groups of 10 each. The two control groups were Gr 1, intact teeth and Gr 2, mesio-occlusodistal preparation only. In six experimental groups, the composite inlays were cemented with ED Primer II/Panavia F 2.0, Excite DSC/Variolink II, and One-Step Plus/Duolink according to manufacturers' instructions (Groups 3, 5, and 7, respectively) or with OX during cementation (Groups 4, 6, and 8, respectively). In Group 9, inlays were cemented with a resin cement without adhesive system. After thermocycling, fracture strength was tested. The data were analyzed using two-way and one-way ANOVA and LSD post hoc tests (α = 0.05). RESULTS: Fracture resistance of the six groups were significantly affected by OX (p = 0.002) but not by the resin cement type (p > 0.05). The interaction of the two factors was statistically significant (p = 0.052). A statistically significant difference between all groups was found (p < 0.001). The mean fracture resistances (N) were: Gr1 = 1168 ± 157,(a) Gr2 = 360 ± 110,(d) Gr3 = 1026 ± 188,(b) Gr4 = 887 ± 143,(c) Gr5 = 1007 ± 132,(b) Gr6 = 810 ± 164,(c) Gr7 = 1033 ± 218,(a) Gr8 = 955 ± 147,(ab) Gr9 = 780 ± 86(c) (groups with the same superscript letter indicate statistical similarity). CONCLUSIONS: Combining an OX with three resin cements had a significant negative effect on the fracture resistance of premolars restored with composite inlay cemented with Panavia F2.0 and Variolink II, but it had no significant effect when cemented with Duolink.

Effect of re-etching oxalate-occluded dentin and enamel on bonding effectiveness of etch-and-rinse adhesives.

PURPOSE: To determine whether or not re-etching of oxalate-treated dentin and enamel increases microshear bond strength (µSBS) and improves hybridization. MATERIALS AND METHODS: Two single-bottle etch-and-rinse adhesives, SingleBond (3M/ESPE) and OptiBond S (Kerr), were bonded to deep occlusal dentin and enamel after perfusion under 20 mmHg simulated intrapulpal pressure. For each adhesive tested, the experimental groups were: G1: bonding according to manufacturer's instructions (control); G2: application of oxalate desensitizer (D/Sense Crystal, Centrix) to acid-etched substrate followed by 60 s water rinsing prior to bonding; G3: same as G2, but with a further 15-s re-etching with 35% phosphoric acid before bonding. The microshear bond strength (µSBS) to dentin and enamel was tested (n = 15); a scanning electron microscopic (SEM) analysis of surface topography (n = 2), interface (n = 2), and failure mode was also performed. The data were statistically analyzed using ANOVA and Tukey's tests at p ≤ 0.05. RESULTS: In enamel, both adhesives showed no significant difference in µSBS among groups. In dentin, the highest statistically µSBS for both adhesives was recorded for G1, followed by G2, with the lowest values revealed remnants of calcium oxalate crystals that were removed only from enamel surfaces after re-etching. SEM images of the interface revealed inadequate dentin hybridization in G2 and G3 compared to G1. CONCLUSION: Re-etching after oxalate treatment compromises bonding of single-bottle etch-and-rinse adhesives to dentin and provides no added benefits to enamel bonding.

Impact of Gluma Desensitizer on the tensile strength of zirconia crowns bonded to dentin: an in vitro study.

This study tested the impact of Gluma Desensitizer on the tensile strength of zirconia crowns bonded to dentin. Human teeth were prepared and randomly divided into six groups (N = 144, n = 24 per group). For each tooth, a zirconia crown was manufactured. The zirconia crowns were cemented with: (1) Panavia21 (PAN), (2) Panavia21 combined with Gluma Desensitizer (PAN-G), (3) RelyX Unicem (RXU), (4) RelyX Unicem combined with Gluma Desensitizer (RXU-G), (5) G-Cem (GCM) and (6) G-Cem combined with Gluma Desensitizer (GCM-G). The initial tensile strength was measured in half (n = 12) of each group and the other half (n = 12) subjected to a chewing machine (1.2 Mio, 49 N, 5°C/50°C). The cemented crowns were pulled in a Universal Testing Machine (1 mm/min, Zwick Z010) until failure occurred and tensile strength was calculated. Data were analyzed with one-way and two-way ANOVA followed by a post hoc Scheffé test, t test and Kaplan-Meier analysis with a Breslow-Gehan analysis test (α = 0.05). After the chewing simulation, the self-adhesive resin cements combined with Gluma Desensitizer showed significantly higher tensile strength (RXU-G, 12.8 ± 4.3 MPa; GCM-G, 13.4 ± 6.2 MPa) than PAN (7.3 ± 1.7 MPa) and PAN-G (0.9 ± 0.6). Within the groups, PAN, PAN-G and RXU resulted in significantly lower values when compared to the initial tensile strength; the values of all other test groups were stable. In this study, self-adhesive resin cements combined with Gluma Desensitizer reached better long-term stability compared to PAN and PAN-G after chewing simulation.

Effects of potassium oxalate on knoop hardness of etch-and-rinse adhesives.

The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives-two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])-were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; p<0.05). Regardless of the adhesive, the treatment with potassium oxalate reduced the adhesives' KHN (p<0.05), with the OS system exhibiting the lowest KHN compared with the MP and SB systems.

Caries-preventive activity of fluoride-containing resin-based desensitizers.

OBJECTIVE: The purpose of this study was to evaluate the effects of different desensitizing agents on the prevention of root caries when applied to root surfaces. MATERIALS AND METHODS: Thirty human roots were sectioned into quarters with a 3 × 4 mm window. A desensitizer (VX, Clinpro™ XT Varnish; SP, Seal & Protect®; or PB, Clearfil™ Protect Bond) was applied to three of the quarters in each window. Teeth were stored separately in water for one day, 30 days, or 60 days. The remaining quarter, without the application of desensitizer, served as a control. After storage in water, all specimens were subjected to pH cycling. Scanning electron microscopy was used to observe the demineralization bands created on the subsurface layer. The weight percentages of fluorine (F), silica, and calcium (Ca) were determined using electron probe microanalysis to quantify the elemental distributions in the root dentin. The concentrations of F released during a pH cycling were measured. RESULTS: For the control group, the average lesion depth was 18.92 ± 5.42 µm, and the average Ca loss was 15.66% ± 6.80% in the superficial layer and 30.44% ± 9.61% in the subsurface layer. No Ca loss occurred in the desensitizer-treated groups. All desensitizing agents remained intact for at least 60 days. F levels were increased in the hybrid layer but not in the subhybrid area. Outward release of F diminished with time. CONCLUSION: The F-containing resin-based desensitizers protected exposed root surfaces from demineralization. F liberated from the desensitizers was detected only at minimal levels.

Effect of a nano-hydroxyapatite paste on bleaching-related tooth sensitivity.

STATEMENT OF THE PROBLEM: Bleaching-related tooth sensitivity has been shown to be facilitated by the presence of enamel defects. A nano-hydroxyapatite (n-HAP) paste has been shown to repair these defects. PURPOSE OF THE STUDY: Using a randomized clinical trial, an n-HAP paste was investigated to determine its efficacy in reducing bleaching-related tooth sensitivity. METHODS AND MATERIALS: An n-HAP paste (Renamel AfterBleach, Sangi Co., Ltd., Tokyo, Japan) and a placebo (zero-HAP) were randomly assigned for use in 42 participants. A 7% hydrogen peroxide gel was used twice daily for 14 days, with use of assigned desensitizer for 5 minutes immediately following. A diary was completed daily for 4 weeks to note: use of the agents and sensitivity on a visual analog scale (VAS). Three aspects of tooth sensitivity were investigated: percentage of participants; number of days; and intensity level. Color change was assessed. RESULTS: For Groups zero-HAP and n-HAP, respectively, 51 and 29% of participants reported tooth sensitivity (p = 0.06). Days of sensitivity were 76 and 36, respectively (p = 0.001). Change in VAS score from baseline trended higher for group zero-HAP (p = 0.16). Color change was equivalent. DISCUSSION: The data trend indicated group n-HAP experienced less sensitivity over all three measures. Only the number of days of sensitivity was statistically significant. CONCLUSION: Within the limits of the study it can be concluded that the use of the n-HAP paste was associated with a statistically significant reduction in the number of days of tooth sensitivity experienced during active bleaching. CLINICAL RELEVANCE: For those using a tooth whitener without a desensitizing agent, this study indicates that a paste containing nano-hydroxyapatite crystal can effectively reduce the duration of tooth sensitivity.

The effects of desensitizing resin, resin sealing, and provisional cement on the bond strength of dentin luted with self-adhesive and conventional resincements.

STATEMENT OF PROBLEM: Self-adhesive resin cements were designed to bond without any pretreatment of dentin. However, pretreatments such as the application of desensitizing resin or the resin sealing of dentin with priming/bonding solutions might influence the bonding quality of these self-adhesive resin cements. Little is known about the effect of dentin pretreatment on the bond quality of self-adhesive resin cements. PURPOSE: This study evaluated whether dentin desensitizing or sealing methods influenced the shear bond strength of 1 self-adhesive and 2 conventional resin cements. MATERIAL AND METHODS: One-hundred and eighty human molars were assigned to 5 different pretreatment groups: 1) freshly ground dentin, 2) glutaraldehyde/hydroxyethylmethacrylate (HEMA) desensitized dentin (Gluma), 3) contamination of desensitized dentin with provisional cement, 4) sealed dentin (dual bonding technique), and 5) contamination of sealed dentin with provisional cement. The shear bond strength of a self-adhesive resin cement (RelyX Unicem; RXU) and 2 conventional resin cements (Variolink II; VAR, Panavia 21; PAN) was assessed for each pretreatment group (n=12 per cement types). Two-way ANOVA and 1-way ANOVA together with the post hoc Tukey multiple comparison (α=.05) were performed. RESULTS: On freshly ground dentin, PAN exhibited the highest shear bond strength values (P<.001). The use of the glutaraldehyde/HEMA resulted in a significant increase in the bond strength of RXU as compared to fresh dentin (P<.001). Resin sealing of dentin increased the bond strength of RXU but had no significant effect on VAR or PAN. RXU exhibited the highest mean bond strength after the contamination of resin-sealed dentin by provisional cement. CONCLUSIONS: Glutaraldehyde/HEMA treatment and resin sealing of dentin have a beneficial effect on the shear bond strength of self-adhesive resin cement (RXU). Contamination of dentin with provisional cement has no influence on the bond strength of the self-adhesive resin cement (RXU) or VAR but lowered the bond strength of PAN.

Comparative evaluation of effect of polymerizable and non-polymerizable desensitizing agents on crown-retentive-strength of zinc-phosphate, glass-ionomer and compomer cements.

The Purpose of this study was to evaluate the effect of polymerizable and non-polymerizable dentine desensitizers on retention of complete cast crowns cemented with three different types of cements. Freshly extracted human molars (n = 90) were prepared for standardized crown preparation (6-degree taper 4-mm height). The axial surface area of each preparation was determined and specimens were distributed equally among groups (n = 10). Dentine desensitizers, cementing agents, glass ionomer cement and compomer cement. Teeth were prepared and individual castings were made using high noble porcelain-metal alloy. Castings were cemented, thermo-cycled and removed along the path of insertion using a universal testing machine. Tooth surface as well as inner surface of the casting was examined and nature of cement failure was determined. Compomer cement exhibited the highest retentive strength and all dentine treatments resulted in significantly different retentive values. Zinc phosphate was the least retentive. Crown retentive values of Compomer cement were improved with Prime & Bond NT and Gluma Desensitizer Retentive values of zinc phosphate cement with Prime & Bond NT were decreased and not affected with Gluma Desensitizer Retentive values of Glass ionomer cement were not affected by any of the desensitizers used in the study.

Resin-based materials to control human dentin permeability under erosive conditions in vitro: A hydraulic conductance, confocal microscopy and FTIR study.

OBJECTIVES: To characterize the behavior of three different polymeric agents before and after an erosive challenge on dentin permeability, to analyze their degradation in both conditions, and to analyze their degree of conversion (DC). METHODS: The permeability of human dentin disks (1.0 ± 0.2 mm) was measured with smear layer, after its removal, after treatment (LpTreat) with Gluma Desensitizer, PRG Barrier Coat (PBC) or Icon infiltrant (n = 11/group) and after exposure to citric acid (LpEro) (6%, pH 2.1, 1 min). The specimens were analyzed under a Laser Scanning Confocal Microscope (n = 2/group) and the products' DC were calculated. Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (permeability analysis), to paired t-test (for specimens treated with Icon) and to t-test (DC analysis) (α < 0.05). RESULTS: Icon showed the lowest LpTreat and LpEro values, while PBC and Gluma did not differ from each other under these conditions. Icon and PBC showed LpEro similar to a dentin with smear layer. Under the Laser Scanning Confocal Microscope, more deposits were noticeable on dentin after treating with PBC. Gluma presented the deepest penetration in dentin. The DC of PBC was the highest. SIGNIFICANCE: Icon caused the highest reduction on permeability values, followed by PBC and Gluma. PBC generated more deposits covering dentin and seemed to be more efficient after an erosive challenge. The association of a polymeric resin with inorganic ion-releasing fillers seem to be a great strategy to manage dentin hypersensitivity under erosive conditions.

Effect of bioactive glasses containing strontium and potassium on dentin permeability.

Dentin hypersensitivity (DH) is characterized by pain caused by an external stimulus on exposed dentin. Different therapeutic approaches have been proposed to mitigate this problem; however, none of them provide permanent pain relief. In this study, we synthesized and characterized experimental bioactive glasses containing 3.07 mol% SrO or 3.36 mol% K2 O (both equivalent to 5 wt% in the glass), and evaluated their effect on dentin permeability to verify their potential to treat DH. The experimental materials were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, micro-Raman spectroscopy, and X-ray diffraction to confirm the respective structures and chemical compositions. The reduction in the hydraulic conductance of dentin was evaluated at the three stages: minimum permeability; maximum permeability (24% ethylenediaminetetraacetic acid [EDTA] treatment); and final dentin permeability after treatment with the bioactive glasses. They all promoted a reduction in dentin permeability, with a significant difference for each sample and posttreatment group. Also, a significant reduction in dentin permeability was observed even after a simulated toothbrushing test, demonstrating effective action of these materials against DH. Besides, incorporating 3.07 mol% SrO was a positive factor. Therefore, strontium's desensitizing and re-mineralizing properties can be further exploited in bioactive glasses to promote a synergistic effect to treat DH.