Dentin Treatment Research Articles

MODERN CONCEPTS OF TREATING HYPERESTHESIS OF HARD TOOTH TISSUES (REVIEW OF LITERATURE)

Hyperesthesia (from the Greek hyper - increase and aisthesis - sensation) means any increase in pain sensitivity of the tooth tissues to external irritants of temperature, chemical and tactile nature. The number of the patients with hypersensitivity of the hard dental tissues has increased sharply in recent years and according to various authors’ findings it is from 60% to 90%. A wide range of prevalence fluctuations is observed in different age groups. The age of people with certain symptoms of teeth hypersensitivity is 25-50 years while the highest frequency is among the people aged 30-40 years. Starting from an earlier age women suffer more often than men. The generalized form of hyperesthesia is usually associated with such general causes as the functional state of the nervous system, endocrine diseases, disorders of mineral metabolism in the body. The localized forms of hyperesthesia are caused mainly by the defects in the hard tissues of individual teeth or periodontium. Rapid and effective treatment of hyperesthesia of the hard dental tissues is an important and urgent problem of modern practical dentistry. Therefore, a great amount of the techniques for the treatment of this pathology is constantly increasing. Now one of the most common methods is the local impact on the hard dental tissues.
 The aim of the study is to analyze the specialized medical literature that is concerned with modern methods and techniques for the treatment of hypersensitivity of the hard dental tissues.
 Materials and methods of the research. The review of the literature sources on modern concepts of the treatment of hyperesthesia of the hard dental tissues has been made and the information has been analyzed.
 Results. The problem of hypersensitivity of the tooth tissues has led to the invention of a whole class of the drugs aimed at its elimination. These medications have different chemical nature, the mechanism of the action on the tissues and even the indications for their use, but the purpose of all these medical preparations is common as they are aimed at reducing hypersensitivity of the tooth tissues.
 A wide range of the techniques is proposed to eliminate the problem of tooth sensitivity. One of the most common methods of the treatment is a local effect on the hard dental tissues which is aimed directly at the relief of the hydrodynamic mechanism. According to this theory, the stimulus which causes pain increases the flow of the fluid in the dentinal tubules that leads to the changes in osmotic pressure and increased activity of the nerve endings in its turn. Therefore, taking into account the mechanism of the action of desensitizing toothpastes they are divided into those ones that reduce the excitability of the nerve fiber and those ones that contribute to the obstruction of the dentinal tubules.
 Nowadays there have been also accumulated a sufficient number of clinical and experimental observations indicating that one of the main causes of dentin hypersensitivity is any disturbance of phosphorus-calcium metabolism of the hard dental tissues. A number of authors have shown that people with the generalized form of hyperesthesia has pronounced hypophosphatemia which is combined with the decrease in the content of inorganic phosphorus and calcium in the oral fluid. In this regard, the drugs of calcium (gluconate, chloride, glycerophosphate) and fluoride (sodium fluoride) are widespread in the treatment of dentin hyperesthesia and they are used by application and rubbing into sensitive areas, electro- and phonophoresis, in the form of varnishes and gels, as well as in toothpastes. Unfortunately, the mechanisms of dentinal pain have not been fully studied and its symptoms are nonspecific and subjective. Therefore, there is no ideal composition for the treatment of sensitive dentin. In addition, the result of the therapy occurs in many cases over a long period of time.
 Conclusion. Thus, according to modern ideas, the treatment of hypersensitivity of the hard dental tissues can be carried out in two ways: desensitization of the nerve fibers to reduce the corresponding response to irritation; obturation of the dentinal tubules to restore intra-tubular osmotic pressure. These days one hundred percent result in the treatment has not been achieved, so it is important to find and develop new techniques and methods to eliminate teeth hyperesthesia.

Effect of Over-Etching and Prolonged Application Time of a Universal Adhesive on Dentin Bond Strength.

This study investigated the effect of over-etching and prolonged application time of a universal adhesive on dentin bond strength. Ninety extracted human molars were ground to dentin and randomly allocated into nine groups (G1–9; n = 10 per group), according to the following acid etching and adhesive application times. In the control group (G1), phosphoric acid etching was performed for 15 s followed by application of the universal adhesive Scotchbond Universal (3M) for 20 s, as per manufacturer’s instructions. In groups G2–5, both the etching and adhesive application times were either halved, doubled, quadrupled, or increased eightfold. In groups G6–9, etching times remained the same as in G2–5 (7.5 s, 30 s, 60 s, and 120 s, respectively), but the adhesive application time was set at 20 s as in the control group (G1). Specimens were then restored with a nanofilled composite material and subjected to microtensile bond strength testing. Bond strength data were statistically analyzed by ANOVA and Tukey’s post-hoc tests (α = 0.05). The relationship of bond strength with etching and adhesive application time was examined using linear regression analysis. Treatment of dentin with halved phosphoric acid etching and adhesive application times (G2) resulted in a significant bond strength decrease compared to the control group (G1) and all other test groups, including the group with halved acid etching, but 20 s of adhesive application time (G6). No significant differences in bond strength were found for groups with multiplied etching times and an adhesive application time of 20 s or more, when compared to the control group (G1). In conclusion, a universal adhesive application time of at least 20 s is recommended when bonding to over-etched dentin.

Effect of a root dentin deproteinization protocol on self-adhesive cementation of fiber posts

Aim: This study evaluated the effect of a root dentin deproteinization protocol on the bond strength of fiber post cemented with self-adhesive resin cement. Materials and Methods: Twenty-four single-rooted teeth were randomly divided into two groups (n=12), as follows: G1 - cementation with self-adhesive resin cement RelyX U200 (3M/ESPE) according to manufacturer's instructions; G2 - treatment of root dentin with phosphoric acid at 37% for 15 s followed by sodium hypochlorite (NaOCl) at 5% for 5 minutes, and post cementation according to manufacturer's instructions. A light-emitting diode (LED) unit was used for photoactivation and after 24h at 37 °C in absolute humidity, teeth were sectioned into slices of 1 mm divided by different root thirds (cervical, middle and apical) and submitted to the push-out bond strength test. Two-criteria ANOVA was used to determine the statistical significance between groups (p<0.05). Results: No statistical difference in bond strength between group cemented as manufacturer's instructions and group submitted to deproteinization was detected (p>0.05). As well as there was no statistical difference between the different root thirds evaluated (p>0.05). Conclusions: The deproteinization protocol proposed was not able to improve the bond strength of self-adhesive cement to root dentin.

Influencia del acondicionamiento de la dentina con ácido poliacrílico en la resistencia al cizallamiento de un cemento de ionómero de vidrio modificado con resina con tecnología de nano relleno.

Purpose: This in vitro study aimed to evaluate the influence of dentin conditioning with polyacrylic acid on the shear bond strength of the nano-filled resin-modified glass ionomer cement Ketac N100 (3MESPE). Material and methods: Eighteen bovine incisors were randomly divided into two groups (n=18): group 1, without dentin surface treatment, and group 2, with dentin surface treated with 10% polyacrylic acid for 15 seconds. In both groups the primer was applied before the application of the nano-filled resin-modified glass ionomer cement (Ketac N100) and light-cured for 20 seconds. After 24 hours, the specimens were submitted to thermocycling for 350 cycles, and the teeth were immersed in distilled water at room temperature. After 24 hours, specimens were tested for shear bond strength at 1mm/minute crosshead speed. The collected data were analyzed using the non-parametric test of Mann Whitney (p&lt;0.05). Results: There was a significant difference in shear bond strength values between the treatment and control groups, the group with dentin conditioning with 10% polyacrylic acid showed higher shear strength values than the group without dentin treatment. Conclusion: Application of 10% polyacrylic acid on dentin increases the shear bond strength values of nano-filled resin-modified glass ionomer cement.

Intra-pulpal temperature evaluation during diode laser (445 nm) irradiation for treatment of dentine hypersensitivity: in vitro a pilot study

The current study aimed to evaluate the temperature rise in the dental pulp during treatment of dentin with 445-nm diode laser. Ten single-rooted human premolar teeth were randomly enumerated into 1 to 10. Teeth were embedded in a resin block, and a thermocouple was inserted into the pulp chamber. Cervical third of the crown were irradiated with 1, 1.5, 2, 2.5, and 3 W at time of irradiation of 10, 15, 30, and 60 s (CW, Non-contact mode), while immersed in a 37 °C thermal bath. The maximum mean temperature rise in the dental pulp was 10.6 °C achieved after irradiation with 3 W for 60 s and the lowest temperature increase achieved was 0.3 °C with 1 W for 10 s. Using the 445-nm diode laser, 0.2–1 W, CW up to 60 s; 1.5 W, CW up to 15 s; 2 W, CW, 10 s; and 2.5 W,CW, 10 s are considered biologically safe parameters for the dental pulp during dentine hypersensitivity treatment.

Effect of benzalkonium chloride addition to EDTA on attachment and proliferation of dental pulp stem cells on dentin and on transforming growth factor-β1 release.

To investigate the effect of benzalkonium chloride (BAC) addition to ethylenediaminetetraacetic acid (EDTA) on transforming growth factor-β1 (TGF-β1) release, as well as attachment and proliferation of dental pulp stem cells (DPSCs) on dentin. A total of standard 268 human dentin disks were prepared and immersed in 1.5% sodium hypochlorite (NaOCl) for 5min. The disks were rinsed with distilled water and randomly divided into seven groups. In control group, the disks received no further treatment. The remaining disks were immersed in following solutions: 17% EDTA or 17% EDTA + 0.008% BAC for 1, 5 or 10min and rinsed with distilled water. DPSCs were seeded in part of the disks since the TGF-β1 release assay was performed with disks with and without cells. The attachment and proliferation of DPSCs on dentin disks were analyzed using lactate dehydrogenase activity and WST-1 assays, respectively. The cell morphology was observed by scanning electron microscopy. The release of TGF-β1 was quantified using ELISA. Data were analyzed using three- and two-way analysis of variance with Bonferroni corrections. Both EDTA solutions increased the attachment and proliferation of DPSCs (p < .05) while there was no significant difference between them (p > .05). The exposure time of both EDTA solutions had no influence on cell attachment, proliferation and TGF-β1 release (p > .05). There was no significant difference in TGF-β1 release between the control and experimental groups (p > .05). The amount of released TGF-β1 from dentin disks was similar whether or not they were seeded with cells (p > .05). Dentin treatment with either of the EDTA solutions had no effect on the amount of TGF-β1 release while both EDTA solutions improved cell attachment and proliferation on dentin surface regardless of exposure time.

Cold atmospheric pressure plasma treatment to assist the restoration of the apical region of a root canal in endodontic procedures

PurposeIn Endodontics, in order to complete a root canal treatment, the use of guttapercha to completely seal the root apex must be coupled with endodontic cements known as sealers to improve the adhesion with dentine, despite their cytotoxicity and solubility. The present study investigates the effect of enhancement of adhesion between these materials and Cold Atmospheric Plasma (CAP)-treated dentine of the apical region of ex-vivo teeth as a first step towards the reduction on the use of cytotoxic materials and the use of CAP in-vivo at a clinical stage. MethodsA dielectric barrier discharge (DBD) helium plasma jet was used to treat for 180 sec the shaped root canal dentin. Pushout tests and confocal microscopy analysis have been performed to evaluate the effect of cold plasma treatment in terms of adhesion performances and interaction between filling materials and dentin respectively. ResultsThe pushout test results highlight how a 180 seconds CAP treatment of dentin promotes an enhancement of bonding strength between filling materials and dentine in all investigated cases. In particular, when the dentine is CAP-treated in the apical region, the adhesion performances of guttapercha achieved a relevant increase (~ +200%), revealing how it was able to “self-bond” with the substrate with results comparable with the conventional procedure but without any sealer application, while the conventional (guttapercha+sealer) apical sealing procedure shows an improvement around +50%. Moreover, confocal images qualitatively confirmed the higher spreading and penetration of both guttapercha and sealer into dentinal tubules. The ergonomics of the prototype has been also improved to comply with the dimensions of devices commonly used in the dental field, with a plasma source diameter of 21.5 mm and with a choice of materials to minimise its weight. ConclusionCAP treatment of dentin increases the adhesion performances and paves the way for a sealer-free and safer procedure for apical restoration.

Effect of different surface treatments of human occlusal sclerotic dentin on micro-tensile bond strength to resin composite core material.

The objectives of this study were to evaluate the micro-tensile bond strength (μTBS) of composite bonded to human occlusal sclerotic dentin following different surface treatments to determine the sclerotic dentin morphology. Human molars without (normal dentin; group 1) or with occlusal wear (sclerotic dentin; groups 2-5) were divided and subjected to different surface treatments, including the normal protocol for the Contax self-etch bonding system (group 1 and 2); doubled etch-prime time (group 3); pre-conditioning with 37% phosphoric acid before normal protocol (group 4); or pre-conditioning with 37% phosphoric acid before doubling the self-etching time (group 5). All teeth were restored with composite (Luxacore Z dual), sectioned into stick specimens and stored for 24h in water before specimens were subjected to the μTBS test (n=50 per group). The μTBS of normal dentin was not statistically significantly different from that of the sclerotic dentin groups, except for the doubled etch-prime time group which showed lower μTBS. Sclerotic dentin pre-treated with phosphoric acid resulted in less sclerotic casts and wider dentinal tubules, while doubled etch-prime time did not alter the morphology, as shown by scanning electron microscopy. In conclusion, the use of 37% phosphoric acid before applying self-etch bonding resulted in more tubule openings and a significantly higher μTBS when compared with the doubled etch-prime time group.

Influence of desensitizers agents on the dentin bond strength after one-year water storage

Aim: Evaluate the effect of adhesives systems combined with desensitizer agents on the microtensile bond strength (μTBS) of a composite resin to dentin. Methods: Cervical dentin of thirty-two human molars were used to simulate hypersensitivity areas. The teeth were divided into four groups (n=8), according to the type of adhesive system and desensitizer agents. No desensitizer was used in the control (Clearfil SE Bond – CS). Two experimental groups were pretreated with either MS Coat Bond (MS) or Biofluorid 12 (BF) immediately prior to bonding with CS. The last group corresponded to Gluma Comfort Bond + Desensitizer (GC) application. After dentin treatments, a composite block was built-up on dentin surface and after 24 hours teeth were serially sectioned to obtain bonded bean specimens. Beams were stored in water for 24 hours or one year. Subsequently, the specimens were submitted to the μTBS test. Data were analyzed by two-way mixed ANOVA and Bonferroni’s test (α = 0.05). Results: At 24 hours, there was no significant difference in μTBS among groups. However, at one year, dentin treated with MS or BF demonstrated significantly lower μTBS of CS to dentin compared to control and GC, which kept their μTBS stable. Conclusion: The effect of MS and BF desensitizer agents on the μTBS of CS to dentin did not reduce the μTBS at 24 hours, but it decreases significantly after one year.

Effect of proanthocyanidin mediated immediate and delayed dentin sealing on the strength of premolars restored with composite resin inlay.

BackgroundImmediate dentin sealing (IDS) with proanthocyanidin (PA) could be used before cementation with a self-adhesive (SA) cement. The aim of this study was to assess the effect of PA treatment on acid-etched dentin before adhesive application, in IDS and delayed dentin sealing (DDS), on the strengthening property of SA-cemented composite resin inlay in premolars. Material and MethodsEighty-four maxillary premolars were divided into 7 groups (n=12): 1) (Intact) Sound teeth served as controls; groups 2-7) After cavity preparation and fabrication of composite resin inlay, temporary inlays were made and cemented. After one week, the inlays were removed and composite inlays were luted with a self-adhesive resin cement as follows: 2) (SA) Without dentin- pretreatment; 3) (DDS) Etch-and-rinse adhesive before the cementation; 4) (DDS/PA) PA treatment of acid-etched dentin before the adhesive, followed by the cementation; 5) (Etch/PA) PA treatment of acid-etched dentin before the cementation; 6 and 7) (IDS and IDS/PA) Application of IDS without or with PA treatment, respectively, one week before the cementation. After thermo-mechanical aging, fracture resistance (FR) was tested. Data were analyzed using one-way ANOVA and Tamhane tests (α=0.05). ResultsThere was a significant difference between the study groups (P<0.001). The IDS and IDS/PA groups yielded significantly higher FR compared to the SA group (P ≤ 0.003), but the DDS, DDS/PA and Etch/PA groups did not differ from the SA group (P>0.05). The effect of PA on FR in the IDS and DDS techniques was not significant. ConclusionsIDS with or without PA treatment considerably improved the strength of premolars with self-adhesive-cemented inlay, while the value of only IDS with PA treatment reached the level of the sound teeth. Key words:Delayed dentin sealing, fracture resistance, immediate dentin sealing, proanthocyanidin.

Effectiveness of fluoride varnish, diode laser, and their combination in treatment of dentin hypersensitivity: A randomized split-mouth clinical trial.

Background:Dentin hypersensitivity is a common dental problem with no permanent cure and predictable prognosis.Aim:The aim of this study was to evaluate the effectiveness of fluoride varnish (sodium fluoride [NaF]), diode laser, and the combination of NaF and diode laser in the treatment of dentin hypersensitivity.Settings and Design:This was a randomized split-mouth clinical trial.Materials and Methods:Sixty patients aged 20–60 years suffering from dentin hypersensitivity to air-blast, cold, and tactile stimulation corresponding to 4 cm and above on the Visual Analog Scale (VAS) in three quadrants with at least two hypersensitive teeth per quadrant were selected. Hypersensitive teeth were allotted to Group 1 – 5% NaF varnish application alone, Group 2 – 810-nm gallium–aluminum–arsenide laser (GaAlAs) diode laser (0.5 W) irradiation alone, and Group 3 – NaF varnish application, followed by diode laser irradiation. VAS score was recorded at baseline, 1 week, 2 weeks, 1 month, 3 months, and 6 months.Results:A statistically significant reduction in dentin hypersensitivity was observed in all the three groups, from the baseline to the 1st-, 3rd-, and 6th-month follow-ups (P < 0.05). Group 2 and Group 3 demonstrated a significantly higher reduction (P < 0.05) in dentin hypersensitivity for all the stimuli as opposed to Group 1 at all follow-up intervals. However, no statistically significant difference (P > 0.05) was present between Group 2 and Group 3 at all follow-ups.Conclusion:Diode laser is significantly more effective than fluoride varnish alone in the treatment of dentin hypersensitivity over a period of 6 months.

The results of computer simulation of the dentinal fluid hydrodynamics in the open crown dentinal tubule

To study the hydrodynamics of the dentinal fluid along the dentinal tubule in the event of its opening as a result of mechanical and acid treatment of the dental crown dentin. Material and methods: A licensed version of the ANSYS / FLOTRAN computer program was used, which is a software tool for solving various problems of hydrodynamics, including laminar and turbulent flow of an incompressible or compressible fluid. The results of computer simulation showed that 1.5 ms after drying of the dentin tubule (length 6 mm) it is refilled with dentin fluid, which then begins to accumulate on the treated surface of the dental hard tissues. Reducing the length of the dentinal tubule as a result of the cavity preparation leads to an increase in the speed and mass of pulp fluid released through it.

Influence of fractional carbon-dioxide laser in comparison to ErCr-YSGG on the dentin bond integrity of bioactive materials.

Objective:The aim was to assess the influence of Er, Cr: YSGG laser (ECL) and fractional carbon dioxide laser (FCL) on the shear bond strength (SBS) and microleakage of bioactive restorative material to dentin.Methods:The study was performed in King Saud university in the month of June-July 2019. One hundred and twenty permanent teeth were vertically placed in acrylic resin. Based on the type of surface treatment regime (n=40), samples were divided into three groups. Group-I samples were surface conditioned with total etch and rinse (TE); Group-2 samples were surface treated with Er, Cr: YSGG laser (ECL) and Group-3 specimens were conditioned with fractional carbon dioxide laser (FCL). Surface treatment of dentin was followed by type of bulk fill resin (BFR) application. Tetric-N-Ceram was bonded to dentin conditioned with TE (n=20), FCL (n=20) and ECL (n=20). Similarly, bioactive material (BAM) was also bonded to conditioned surface (n=60). Samples (n=10) among each group were placed in a Universal testing machine. For microleakage testing 5 pairs of samples from each group (n=10) were placed in solution of 2% methylene blue for 24h Fracture analysis was performed using stereomicroscope at 40x magnification. Descriptive statistics i.e., means and standard for SBS and microleakage were compared using analysis of variance (ANOVA) and Tukey’s post hoc test at a significance level of (p < 0.05)Results:The highest SBS scores were displayed by TE-BFR (Bulk filled resin) (19.21 ± 0.925 Mpa) and the lowest shear bond scores were presented by FCL-BFR (11.06±1.611 Mpa). The lowest microleakage scores were exhibited by group ECL-BFR (24.11±13.01nm). Similarly, the highest microleakage score was displayed in group FCL-BAM (42.18±16.32 nm). Admixed failure was pertinent in groups conditioned by ECL. Moreover, groups conditioned with FCL adhesive type of failure was found in abundance.Conclusions:ECL has a potential to be used as an alternate to total etch and rinse for conditioning of dentin when bonded to bioactive materials.

Effect of different solutions in reversing the damage caused by radiotherapy in dentin structure.

Background Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure. This study evaluated the effect of different solutions on the dentin chemical composition and collagen structure of irradiated dentin. Material and Methods Sixty maxillary canines were distributed in 2 groups (n=30): non-irradiated and irradiated (radiotherapy: X-rays of 6 MV in 30 cycles of 2 Gy to 60 Gy). The teeth were sectioned, sanded, and polished to obtain 3x3x2 mm fragments, which were redistributed in 3 subgroups (n=10) according to the treatment employed: chlorhexidine 2% (CL), chitosan 0.2% (QT), and 0.5 M carbodiimide (EDC). The samples were analyzed in FTIR at time zero (T0-control) and after 1 (T1), 3 (T3), and 5 (T5) minutes of immersion in the tested solutions. The data for the areas of the carbonate (C), amide I (AI) bands, and the ratio between the areas of the amide III/proline and hydroxyproline (AIII/PH) bands were analyzed using ANOVA and Tukey test (α=5%). Results QT showed lower C values at T1, T3, and T5 (P<0.0001), presenting lower values when compared to CL and EDC subgroups (P<0.05). AI values at T3 and T5 were higher than T0-control and T1, independently of the radiotherapy and dentin treatment factors (P<0.05). At T0-control, the AIII/PH ratio was lower in the irradiated group (P<0.05), whereas the EDC treatment at T1, T3, and T5 and QT at T3 and T5 increased these values (P<0.05), making them similar to non-irradiated subgroups (P>0.05). Conclusions Radiotherapy changes the secondary structure of collagen, and EDC was able to restore collagen integrity after 1 minute of immersion, without changing dentin inorganic composition. Key words:Radiotherapy, collagen, dentin, FTIR, chemical composition.

Effect of carbodiimide and chlorhexidine on the bond strength longevity of resin cement to root dentine after radiation therapy.

To evaluate the effect of carbodiimide (EDC) and chlorhexidine (CHX) on the bond strength (BS) of resin cement to root dentine of teeth submitted to radiotherapy. One hundred and twenty extracted maxillary canines were selected and assigned to 2 groups (n=60): nonirradiated and irradiated (30 cycles of 2Gy, total 60Gy). Roots lengths were standardized, and canals were prepared and filled. Post spaces were then prepared, and the samples were redistributed according to dentine treatment (n=20): saline solution (SF); CHX 2%; or EDC 0.5M. After drying the post space, fibreglass posts were cemented. Cross-sectioned slices were obtained, and in half of the specimens of each subgroup (n=10), the analysis was performed immediately; the others (n=10) were stored for 10months before analyses. The most cervical slice of each third was subjected to a push-out test and failure pattern analysis (n=10), and the most apical slice submitted to the analysis of the adhesive interface by SEM (n=5). The bond strength data were submitted to anova and Tukey tests, the adhesive interface adaptation was submitted to Kruskal-Wallis and Dunn's tests, and the Chi-square test was used to evaluate the type of failure. The irradiated specimens had significantly lower bond strength (13.8±4.3) than the nonirradiated (18.1±3.1; P<0.001). For the irradiated teeth, the bond strengths were significantly lower in the SF and CHX groups (P<0.001). Also, the bond strengths reduced significantly after 10months in the SF and CHX groups (P<0.001). Cohesive failures occurred in dentine for irradiated specimens. Poorer interface adaptation, dentine fractures and microfractures were observed in irradiated specimens, and better adaptation was observed for specimens after EDC treatment. Radiotherapy was associated with lower bond strength and worse interface adaptation. Dentine treatment with EDC contributed to adhesive interface longevity during the cementation of glass fibre posts in nonirradiated and irradiated teeth.

Influence of Expasyl and Viscostat on Bond Strength of Resin Composite to Dentin with Different Adhesives

The aim of the present study was to evaluate the influence of gingival retraction agents and different bonding regimes on the shear bond strength (SBS) of dentin to resin composite. Sixty human teeth were divided into six groups (n = 10) based different combinations of hemostatic agents (Viscostat and Expasyl) and dentin bonding regimes [Total-etch (TE) and self-etch (SE)]. Group A1, Expasyl and TE; group A2: Expasyl and SE; group B1: Viscostat and TE; group B2: Viscostat and SE, group C1 (control): No hemostatic agent and TE; group C2 (control): No hemostatic agent and SE. Composite build-ups (Tetric N Ceram) were performed after dentin treatments and SBS was assessed using universal testing machine. Failure analysis was performed with a stereomicroscope and classified as adhesive, cohesive and admixed. Data was analysed using ANOVA and multiple comparisons test. The maximum and minimum SBS was displayed by specimens in group C1 (36 59 ± 5 94 MPa) and group B2 (17 95 ± 2 52 MPa) respectively. Control groups (C1 and C2) showed statistically comparable SBS, which was significantly higher in comparison to experimental groups (A1, A2, B1, and B2) (p &lt; 0.05). Hemostatic agents inhibited the adhesive bond strength of composite to tooth dentin. Reversal effect of total-etch and self-etch bonding regimes on hemostatic agent treated dentin SBS was minimal.

A New Approach for Determining the Minimum Concentration of Proanthocyanidin for Preservation of Collagen in H Dentin.

Introducing a minimum concentration and clinically relevant application time for grape seed extract (GSE) proanthocyanidin as a dentin preserver. Dentin beams were demineralized in 10% phosphoric acid for 24h. Then, the following groups were prepared: G1: no treatment, G2: 2% CHX + 1min, G3: 1% GSE + 1min, G4: 1% GSE +5min, G5: 2% GSE + 1min, G6: 2% GSE + 5min, G7: 5% GSE + 1min and G8: 5% GSE + 5min. After 30 days, MALDI-TOF mass spectrometry was used to confirm the availability of digested peptide fragments and monitor the pattern of collagen digestion. Gravimetric assessment and HPLC-UV were utilized for quantitative measurement of dentin destruction. Glycine quantities were considered as measures of collagen digestion. 7% to 25% loss of dry mass was measured in experimental groups. Regarding the liberated Glycine, GSE dose- and time-responses were observed, so that, 5% GSE showed considerable protecting effect on collagen compared to 1 and 2% GSE (P⟨0.001) and 5min GSE application could establish superior dentin preservation compared to 1min application (P⟨0.001). 5-minute treatment of dentin at 2% GSE and above is essential for protecting the demineralized dentin collagen against biodegradation.

Raman spectroscopy-multivariate analysis related to morphological surface features on nanomaterials applied for dentin coverage.

Raman spectroscopy and scanning electron microscopy (SEM) were used to investigate the effect of coating materials and acidulated phosphate fluoride gel (APF) treatment on dentin before and after erosion-abrasion cycles. A multi-walled carbon nanotube/graphene oxide hybrid carbon-based material (MWCNTO-GO), nanohydroxyapatite (nHAp), or a combined composite (nHAp/MWCNTO-GO) were used as a coating. Seventy root dentin fragments obtained from 40 bovine teeth were prepared and divided into groups (n=10): negative control, artificial saliva - C, positive control - APF; nHAp; MWCNTO-GO; APF_nHAp; APF_MWCNTO-GO and APF_nHAp/MWCNTO-GO. All samples were subjected to cycles of demineralization (orange juice, pH ~3.7, room temperature, 1min) followed by remineralization (saliva, 37°C, 1h). The remineralization procedures were followed by tooth brushing (150 strokes). The above cycle was repeated 3×/day for 5days. The previous APF treatment of dentin allowed a better affinity of nHAp and MWCNTO-GO with the inorganic and organic portion of dentin, respectively. This interaction indicates the formation of a protective layer for the dentin surface and for the collagen giving possible protection against erosion. SEM micrographs illustrated the formation of a protective layer after application of the biomaterials and that it was partially or totally removed after the erosion and abrasion. Raman spectroscopy combined with multivariate analysis could distinguish samples with respect to treatment efficacy. The APF_nHAP/MWCNT-GO composite has shown to be a promising material since it has binding characteristics both to the inorganic and organic portion of the dentin and reduced solubility. Mineral-to-matrix ratio (MMR) parameter analysis confirmed the binding capability of MWCNTO-GO-based materials to dentin.

Effects of sodium hypochlorite as dentin deproteinizing agent and aging media on bond strength of two conventional adhesives.

This study evaluated the effect of 10% sodium hypochlorite (NaOCl) as deproteinizing agent and storage media on bond strength (BS) of two etch-and-rinse adhesive systems to dentin. Twenty-eight sound extracted human third molars were divided in four groups (n = 7), according to dentin treatment (conventional etching or etching followed by 10% NaOCl application) and adhesive systems (GB-Gluma 2Bond and OS-One-Step). After dentin treatments and adhesive application, a composite block was built-up on dentin surface and teeth were serially sectioned to obtain bonded sticks specimens. The sticks were submitted to three aging conditions: (24H) 24 hr in water (immediate), (SH) 3 hr of NaOCl accelerated-aging or (1Y) 1 year of water storage. Afterward, submitted to microtensile bond strength test (μTBS), failure modes and adhesive interfaces analyzes. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test (α = .05). Dentin deproteinization before bonding significantly reduced μTBS for GB-treated group (p < .05), regardless the aging conditions. Water storage for 1 year (1Y) and NaOCl accelerated-aging (SH) decreased μTBS for both adhesives. Yet, the groups stored in NaOCl (SH) exhibited the lowest BS results (p < .05). Bond strength of deproteinized dentin was dependent on the adhesive system composition and NaOCl accelerated-aging promoted decreased bond strength and further degradation than water storage for 1 year.

Effect of chlorhexidine and isopropyl alcohol on immediate and delayed bond strength of glass fiber posts

Aim: To investigate the effects of dentinal treatment with chlorhexidine and isopropyl alcohol, alone or associated, on the bond strength and bond stability of glass fiber posts cemented with a self-adhesive resin cement. Materials and Methods: Forty bovine teeth were endodontically treated and randomly distributed into four groups, according to the dentinal treatment after post space preparation: distilled water (Control); 2% chlorhexidine (CHX); isopropyl alcohol (ISO); 2% chlorhexidine + isopropyl alcohol (CHX+ISO). Glass fiber posts were cemented with a self-adhesive resin cement and after 24 h specimens were cut into six 1.5 mm-thick slices. One slice of each root third (i.e. apical, middle and coronal) was subjected to immediate push-out test and the other was stored in distilled water at 37 °C for six months for delayed push-out test. Bond strength was registered in megapascal (MPa). Failure mode was evaluated by a stereomicroscope, with 40x magnification. Data analysis was performed using Kruskal-Wallis and Friedman tests, with 5% significance level. Results: No significant differences were detected between experimental groups or between root thirds in the same group in the immediate evaluation. After six months of aging, all groups showed a significant decrease in bond strength values, but ISO group presented higher bond strength than Control and CHX groups (p=0.0001). The most common type of failure for all groups was adhesive between resin cement and root dentine. Conclusions: Dentinal treatment with CHX and ISO, isolated or combined, did not affect the immediate bond strength of glass fiber posts, but the ISO group presented better bond stability after six-month aging.