Clinical evaluation of desensitizing treatments for cervical dentin hypersensitivity

The aim of this study was to compare different treatments for dentin hypersensitivity in a 6-month follow-up. One hundred and one teeth exhibiting non carious cervical lesions were selected. The assessment method used to quantify sensitivity was the cold air syringe, recorded by the visual analogue scale (VAS), prior to treatment (baseline), immediately after topical treatment, after 1 week, 1, 3 and 6 months. Teeth were randomly assigned to five groups (n = 20): G1: Gluma Desensitizer (GD); G2: Seal&Protect (SP); G3: Oxa-gel (OG); G4: Fluoride (F); G5: Low intensity laser-LILT (660 nm/3.8 J/cm²/15 mW). Analysis was based on the non-parametric Kruskal-Wallis test that demonstrated statistical differences immediately after the treatment (p = 0.0165). To observe the individual effects of each treatment, data was submitted to Friedman test. It was observed that GD and SP showed immediate effect after application. Reduction in the pain level throughout the six-month follow-up was also observed. In contrast, LILT presented a gradual reduction of hypersensitivity. OG and F showed effects as of the first and third month respectively. It can be concluded that, after the 6-month clinical evaluation, all therapies showed lower VAS sensitivity values compared with baseline, independently of their different modes of action.

Micromorphological and hardness analyses of human and bovine sclerotic dentin: a comparative study

The purpose of this study was to test the hypothesis that both human and bovine sclerotic dentin have similar hardness properties, in addition to similar micromorphological characteristics. Sixteen teeth (8 human and 8 bovine) exhibiting exposed dentin in the incisal edge and showing characteristics typical of sclerosis were used. Vickers surface microhardness testing was conducted. Three areas of the dentin surface of each specimen were selected. All teeth were processed for scanning electron microscopy in order to estimate the amount (in percentage) of solid dentin on the sclerotic dentin surface. The data were compared by Student's t test (α = 0.05). The micromorphological and microhardness data were compared by Pearson's linear correlation test (α = 0.05). The mean percentages of solid dentin of human and bovine sclerotic dentin were similar (human 90.71 ± 0.83 and bovine 89.08 ± 0.81, p = 0.18). The mean microhardness value (VHN) of human sclerotic dentin was significantly higher than that of bovine sclerotic dentin (human 45.26 ± 2.92 and bovine 29.93 ± 3.83, p = 0.006). No correlation was found between the microhardness values and the amount of solid dentin in the sclerotic dentin, irrespective of the species considered (human R² = 0.0240, p = 0.714; bovine R² = 0.0017, p = 0.923; and combined R² = 0.038, p = 0.46). We concluded that although both bovine and human sclerotic dentin present a similar amount of solid tissue, human sclerotic dentin presents higher microhardness than bovine sclerotic dentin.

Influence of bioactive materials used on the dentin surface whitened with carbamide peroxide 16%

This study investigated the influence of bioactive materials on the dentin surface whitened. MATERIAL AND METHODS: Three bovine teeth were shaped into three dentin wafers. Each wafer was then sectioned, into six dentin slices. One slice from each tooth was distributed into one of 6 groups: 1.CG = control group (distilled water); 2.WT = whitening treatment; 3.WT + MI Paste Plus, applied once a day; 4.WT + Relief ACP30, applied once a day for 30 mintes; 5.WT + Relief ACP60, applied once a day for 60 minutes; 6.WT + Biosilicate®, applied once a week. All groups were treated over 14 days. RESULTS: CG presented all dentinal tubules occluded by smear layer; WT group was observed all dentinal tubules opened. In the groups 3, 4 and 6, tubules were occluded. Group 5, dentinal tubules were completely occluded by mineral deposits. CONCLUSION: The use of bioactive materials immediately after whitening treatment can reduce or even avoid the demineralization effect of whitening and avoid exposing dentinal tubules.

Nd:YAG laser irradiation effect on apical intracanal dentin - a microleakage and SEM evaluation

The purpose of this in vitro study was to evaluate the effect of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation on intracanal dentin surface by SEM analysis and its interference in the apical seal of filled canals. After endodontic treatment procedures, 34 maxillary human incisors were randomly assigned to 2 groups. In the negative control group (n=17), no additional treatment was performed and teeth were filled with vertically condensed gutta-percha; in the laser-treated group (n=17), the root canals were irradiated with Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) before filling as described for the control group. Two specimens of each group were prepared for SEM analysis to evaluate the presence and extent of morphological changes and removal of debris; the other specimens were immersed in 0.5% methylene blue dye (pH 7.2) for 24 h for evaluation of the linear dye leakage at the apical third. SEM analysis of the laser-treated group showed dentin fusion and resolidification without smear layer or debris. The Student’s t-test showed that the laser-treated group had significantly less leakage in apical third than the control group. Within the limitations of this study, it may be concluded that the morphological changes on the apical intraradicular dentin surface caused by Nd:YAG laser resulted in less linear dye apical leakage.

Effect of chlorhexidine concentration on the bond strength to dentin in primary teeth

PURPOSE: To evaluate the effect of the use of 0.5% and 2% chlorhexidine digluconate on the immediate bond strength of a conventional adhesive system to dentin in primary teeth. METHODS: Twenty-one healthy primary molars were divided into three groups (n=7), being one control (A) and two experimental groups (B and C). After dentin exposure, in Group (A) the adhesive procedure was performed using 37% phosphoric acid gel (15 s); dentin was washed (15 s), air dried (30 s) and rehydrated with water. Groups B and C followed similar procedures but for re-hydration with 0.5% and 2% chlorhexidine, respectively, for 30 s. A resin composite block was built simulating a restoration, and the teeth were stored in distilled water at 37°C for 24 h before the microtensile bond strength test. The bond strength data were analyzed by analysis of variance. RESULTS: No statistically significant difference in bond strength was found among the tested groups (P>0.05) CONCLUSION: The 0.5% and 2% concentrations of chlorhexidine presented similar behavior and caused no adverse effects on the bond strength to dentin in primary teeth.

Morphologic changes and removal of debris on apical dentin surfaces after Nd : YAG laser and diode laser irradiation

Objective: To verify the effects of laser energy on intracanal dentin surfaces, by analyzing the morphologic changes and removal of debris in the apical third of 30 extracted human teeth, prepared and irradiated with the Nd:YAG laser and diode laser. Background Data: Lasers have been widely used in endodontics. The morphologic changes in dentin walls caused by Nd: YAG and diode laser irradiation could improve apical seals and cleanliness. Materials and Methods: The protocol used for Nd: YAG laser irradiation was 1.5 W, 100 mJ, and 15 Hz, in pulsed mode, and for diode laser was 2.5 W in continuous mode. Each specimen was irradiated four times at a speed of 2 mm/sec with a 20-sec interval between applications. Five calibrated examiners scored the morphologic changes and debris removal on a 4-point scale. Results: In analyzing the scores, there were no statistically significant differences between the two types of laser for either parameter, according to Kruskal-Wallis testing at p = 0.05. The SEM images showed fusion and resolidification of the dentin surface, with partial removal of debris on the specimens irradiated with the Nd: YAG laser and the diode laser, compared with controls. Conclusion: Both lasers promote morphologic changes and debris removal. These alterations of the dentin surface appeared to be more evident in the Nd: YAG laser group, but the diode laser group showed more uniform changes.

Analysis of Permeability and Morphology of Root Canal Dentin After Er,Cr:YSGG Laser Irradiation

Objective: The aim of this study was to evaluate the morphology and permeability of root canal walls irradiated with Er,Cr:YSGG laser after conventional endodontic treatment. Background: Laser irradiation can be used for dentinal tubule exposure, smear layer removal, and disinfection. Another potential, interesting application is as an adjunct to endodontic treatment, especially in the intracanal medication phase. Methods: Fifty-two single-rooted teeth had their crowns sectioned at the cementoenamel junction and were randomly divided into four groups (n = 13): G1: conventional preparation (CP) + irrigation with EDTA-T+rhodamine B dye solution associated with NDP (dexamethasone phosphate, paramonochlorophenol, polyethylenoglycol) (Rhod-NDP); G2: CP+EDTA-T + Er,Cr:YSGG laser irradiation 0.75W+Rhod-NDP; G3: CP + EDTA-T + Er,Cr:YSGG 1.5W+Rhod-NDP; G4: CP + EDTA-T + Er,Cr:YSGG 2.5W + Rhod-NDP. For the permeability analysis (n = 9), teeth were transversely cut and two slices of each third were selected. The images were analyzed by ImageLab software (Softium Informatica Ltda., Sao Paulo, SP, Brazil). Additional samples (n = 4) were examined by scanning electron microscopy. Results: Data were analyzed statistically using the Kruskal-Wallis and Student-Newman-Keuls tests for the following areas: apical third (H = 23.4651): G1 (14.25)(a), G2 (17.66)(ab), G3 (26.50)(b), G4 (39.58)(c); medium (H = 23.1611): G1 (14.16)(a), G2 (16.66)(ab), G3 (28.83)(b), G4 (38.33)(b); and cervical (H = 32.4810): G1 (9.66)(a), G2 (20.00)(ab), G3 (27.00)(b), G4 (41.33)(c), (p<0.01). Despite the irregular aspect of laser irradiation along the canal walls, the parameters of 1.5W and 2.5W allowed morphologic modifications that increased dentinal permeability. Conclusions: Irradiation with Er, Cr: YSGG laser could be effective in endodontic treatment for increasing dentinal permeability.

Effect of Titanium Tetrafluoride and Amine Fluoride Treatment Combined with Carbon Dioxide Laser Irradiation on Enamel and Dentin Erosion

Objective: This in vitro study aimed to analyze the influence of carbon dioxide (CO(2)) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and amine fluoride (AmF) in protecting enamel and dentin against erosion. Methods: Bovine enamel and dentin samples were pretreated with carbon dioxide (CO(2)) laser irradiation only (group I), TiF(4) only (1% F, group II), CO(2) laser irradiation before (group III) or through (group IV) TiF(4) application, AmF only (1% F, group V), or CO(2) laser irradiation before (group VI) or through (group VII) AmF application. Controls remained untreated. Ten samples of each group were then subjected to an erosive demineralization and remineralization cycling for 5 days. Enamel and dentin loss were measured profilometrically after pretreatment, 4 cycles (1 day), and 20 cycles (5 days) and statistically analyzed using analysis of variance and Scheffe's post hoc tests. Scanning electron microscopy (SEM) analysis was performed in pretreated but not cycled samples (two samples each group). Results: After 20 cycles, there was significantly less enamel loss in groups V and IV and significantly less dentin loss in group V only. All other groups were not significantly different from the controls. Lased surfaces (group I) appeared unchanged in the SEM images, although SEM images of enamel but not of dentin showed that CO(2) laser irradiation affected the formation of fluoride precipitates. Conclusion: AmF decreased enamel and dentin erosion, but CO(2) laser irradiation did not improve its efficacy. TiF(4) showed only a limited capacity to prevent erosion, but CO(2) laser irradiation significantly enhanced its ability to reduce enamel erosion.

Ablation Rate and Morphology of Superficial and Deep Dentin Irradiated with Different Er:YAG Laser Energy Levels

Objective: In this study we evaluated the ablation rate of superficial and deep dentin irradiated with different Er:YAG laser energy levels, and observed the micromorphological aspects of the lased substrates with a scanning electron microscope (SEM). Background Data: Little is known about the effect of Er: YAG laser irradiation on different dentin depths. Materials and Methods: Sixty molar crowns were bisected, providing 120 specimens, which were randomly assigned into two groups ( superficial or deep dentin), and later into five subgroups (160, 200, 260, 300, or 360 mJ). Initial masses of the specimens were obtained. After laser irradiation, the final masses were obtained and mass losses were calculated followed by the preparation of specimens for SEM examination. Mass-loss values were subjected to two-way ANOVA and Fisher's least significant difference multiple-comparison tests (p < 0.05). Results: There was no difference between superficial and deep dentin. A significant and gradual increase in the mass-loss values was reached when energies were raised, regardless of the dentin depth. The energy level of 360 mJ showed the highest values and was statistically significantly different from the other energy levels. The SEM images showed that deep dentin was more selectively ablated, especially intertubular dentin, promoting tubule protrusion. At 360 mJ the micromorphological features were similar for both dentin depths. Conclusion: The ablation rate did not depend on the depth of the dentin, and an energy level lower than 360 mJ is recommended to ablate both superficial and deep dentin effectively without causing tissue damage.

Relationship Between Surface Topography and Energy Density Distribution of Er,Cr:YSGG Beam on Irradiated Dentin: An Atomic Force Microscopy Study

Objective: The aim of this study was to assess by atomic force microscopy (AFM) the effect of Er,Cr:YSGG laser application on the surface microtopography of radicular dentin. Background: Lasers have been used for various purposes in dentistry, where they are clinically effective when used in an appropriate manner. The Er, Cr: YSGG laser can be used for caries prevention when settings are below the ablation threshold. Materials and Methods: Four specimens of bovine dentin were irradiated using an Er, Cr:YSGG laser (lambda = 2.78 mu m), at a repetition rate of 20 Hz, with a 750-mu m-diameter sapphire tip and energy density of 2.8 J/cm(2) (12.5 mJ/pulse). After irradiation, surface topography was analyzed by AFM using a Si probe in tapping mode. Quantitative and qualitative information concerning the arithmetic average roughness (Ra) and power spectral density analyses were obtained from central, intermediate, and peripheral areas of laser pulses and compared with data from nonirradiated samples. Results: Dentin Ra for different areas were as follows: central, 261.26 (+/- 21.65) nm; intermediate, 83.48 (+/- 6.34) nm; peripheral, 45.8 (+/- 13.47) nm; and nonirradiated, 35.18 (+/- 2.9) nm. The central region of laser pulses presented higher ablation of intertubular dentin, with about 340-760 nm height, while intermediate, peripheral, and nonirradiated regions presented no difference in height of peritubular and interperitubular dentin. Conclusion: According to these results, we can assume that even when used at a low-energy density parameter, Er, Cr: YSGG laser can significantly alter the microtopography of radicular dentin, which is an important characteristic to be considered when laser is used for clinical applications.

Antimicrobial photodynamic action on dentin using a light-emitting diode light source

Objective: The aim of this study was the evaluation of two different photosensitizers activated by red light emitted by light-emitting diodes (LEDs) in the decontamination of carious bovine dentin. Materials and Methods: Fifteen bovine incisors were used to obtain dentin samples which were immersed in brain-heart infusion culture medium supplemented with 1% glucose, 2% sucrose, and 1% young primary culture of Lactobacillus acidophilus 108 CFU/mL and Streptococcus mutans 108 CFU/mL for caries induction. Three different concentrations of the Photogem solution, a hematoporphyrin derivative (1, 2, and 3 mg/mL) and two different concentrations of toluidine blue O (TBO), a basic dye (0.025 and 0.1 mg/mL) were used. To activate the photosensitizers two different light exposure times were used: 60 sec and 120 sec, corresponding respectively to the doses of 24 J/cm(2) and 48 J/cm(2). Results: After counting the numbers of CFU per milligram of carious dentin, we observed that the use of LED energy in association with Photogem or TBO was effective for bacterial reduction in carious dentin, and that the greatest effect on S. mutans and L. acidophilus was obtained with TBO at 0.1 mg/mL and a dose of 48 J/cm(2). It was also observed that the overall toxicity of TBO was higher than that of Photogem, and that the phototoxicity of TBO was higher than that of Photogem. Conclusion: Based on our data we propose a mathematical model for the photodynamic effect when different photosensitizer concentrations and light doses are used.

Effect of Oxalate Desensitizer on the Durability of Resin-Bonded Interfaces

Potassium oxalate desensitizers were previously shown to effectively reduce the immediate permeability of resin-bonded dentin. The current study evaluated whether the effect of the combined application of oxalate with etch-and-rinse adhesives interferes with the durability of resin-dentin bonds when using etch-and-rinse adhesives. The bond strength of resin-bonded dentin specimens composed of two-step or three-step etch-and-rinse adhesives (Single Bond, One-Step and Scotchbond Multi-Purpose, respectively) was tested immediately (24 hours) and after 12 months of water storage. The adhesives were used either according to the manufacturers` instructions (control groups) or after treating acid-etched dentin with a potassium oxalate gel (BisBlock, BISCO, Inc). The treatment of dentin with potassium oxalate was shown to negatively affect the baseline bond strength of resin-bonded dentin specimens, regardless of the adhesive used (p<0.05). After storage, the bond strength of the resin-bonded interfaces was significantly reduced for all the tested groups (p<0.001). Nevertheless, the rate of decreasing bond strength was significantly lower for oxalate-treated specimens than for the controls (p<0.05).

Influence of Er:YAG Laser Frequency on Dentin Caries Removal Capacity

The purposes of this study were to evaluate in vitro the influence of different frequencies of Er:YAG laser on the human dentin caries removal capacity. Thirty fragments obtained from third molars were randomly assigned into three groups (n = 10) according to the laser frequency used: 4, 6, and 10 Hz. The caries lesion (+/-1 mm deep) was induced before the irradiation by S. mutans cultures for 6 weeks. The specimens of all groups were irradiated with 200 mJ of energy in noncontact and focused mode under constant refrigeration (water flow: 2.5 mL/min). Quantitative analysis of the caries removal was performed by DIAGNOdent (TM) and the Axion Vision (TM) software. Qualitative analysis was performed by Scanning electron microscope (SEM) and light microscope (LM). Data were analyzed by ANOVA and Fishers` tests. The DIAGNOdent (TM) revealed that the caries removal was similar with 4 and 6 Hz and was superior with 10 Hz (P < 0.05). The analysis with Axion Vision (TM) software revealed that the caries removal was similar with 6 and 10 Hz and the 4 Hz group promoted the lowest caries removal. Through SEM morphologic analysis, some specimens irradiated with 4 Hz presented, under the demineralized dentin, a disorganized collagenous matrix. The LM images revealed that all frequencies used promoted irregular caries removal, being observed over preparations with 6 and 10 Hz. It can be concluded that the increase of Er:YAG laser frequency provided a higher dentin caries removal without selectivity to the disorganized dentin. Microsc. Res. Tech. 74:281-286, 2011. (C) 2010 Wiley-Liss, Inc.

Bond strength of an adhesive system irradiated with Nd : YAG laser in dentin treated with Er : YAG laser

The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm(2). ne adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm(2). Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser.

Influence of etching time on bond strength in dentin irradiated with erbium lasers

The purpose of this in vitro study was to evaluate the effect of etching time on the tensile bond strength (TBS) of a conventional adhesive bonded to dentin previously irradiated with erbium:yttrium-aluminum-garnet (Er:YAG) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers. Buccal and lingual surfaces of 45 third molars were flattened until the dentin was exposed and randomly assigned to three groups (n = 30) according to the dentin treatment: control (not irradiated), irradiated with Er:YAG (1 W; 250 mJ; 4 Hz; 80.6 J/cm(2)) laser or Er,Cr:YSGG (4 W; 200 mJ; 20 Hz; 71.4 J/cm(2)) laser, and into three subgroups (n = 10) according to acid etching time (15 s, 30 s or 60 s) for each experimental group. After acid etching, the adhesive was applied, followed by the construction of an inverted cone of composite resin. The samples were immersed in distilled water (37A degrees C for 24 h) and subjected to TBS test [50 kilogram-force (kgf), 0.5 mm/min]. Data were analyzed by analysis of variance (ANOVA) and Tukey statistical tests (P a parts per thousand currency signaEuro parts per thousand 0.05). Control group samples presented significant higher TBS values than those of all lased groups. Both irradiated groups exhibited similar TBS values. Samples subjected to the different etching times in each experimental group presented similar TBS. Based on the conditions of this in vitro study we concluded that Er:YAG and Er,Cr:YSGG laser irradiation of the dentin weakens the bond strength of the adhesive. Moreover, increased etching time is not able to modify the bonding strength of the adhesive to irradiated dentin.