Superficial Dentin Research Articles

Association between DEFB1 rs11362 and Caries Susceptibility in Permanent Dentition: A Cross Sectional Study.

Dental caries is a multifactorial chronic bacterial infectious disease. Variations in the predisposition of the general population to dental cavities suggest that genetic and immunological factors play significant roles in its pathogenesis. This study aims to explore the impact of the Beta-Defensin 1 (DEFB1) rs11362 polymorphism on caries susceptibility in permanent dentition among the Bai Kuyao and Zhuang ethnic groups in China. A sample of 754 adolescents aged 12-15 was randomly selected from primary and junior high schools in Nandan County, Guangxi, China. All adolescents underwent clinical examinations, and DNA samples were collected. The genotype of DEFB1 rs11362 was determined using single nucleotide polymorphism (SNP) typing. The concentration of human β Defensin 1 (hBD-1) protein in saliva was measured using a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). The distribution of the DEFB1 rs11362 T allele was lower in the Bai Kuyao group compared to the Zhuang group. The disparity in the rs11362 genotype was statistically significant in the superficial dentin caries subgroup of the Bai Kuyao population (p = 0.017). Following adjustment for all potential confounding variables, the analysis revealed a heightened risk of superficial dental caries among CT genotype carriers in the Bai Kuyao population under a co-dominant model (odds ratios (OR) = 2.70; 95% confidence intervals (CI) [1.35-5.44]; p = 0.005), and an increased risk among CC genotype carriers in the Bai Kuyao population under a dominant model (OR = 2.35; 95% CI [1.18-4.67]; p = 0.015). A significant difference (p < 0.05) was noted in the distribution of rs11362 genotypes and salivary hBD-1 levels among the Bai Kuyao group. Salivary hBD-1 levels were notably higher in the CC genotype group (4.12 ± 2.07 ng/mL) compared to both the CT (2.77 ± 1.62 ng/mL) and TT genotype groups (2.32 ± 0.98 ng/mL). The DEFB1 rs11362 polymorphism showed an association with caries susceptibility in permanent teeth and influenced hBD-1 protein expression in saliva. Consequently, the DEFB1 polymorphism likely represents a concealed risk factor for caries.

Evaluation of The Role of Music and Bach Flower Remedies in The Management of Anxious Pediatric Dental Patients: A Randomised Clinical Trial

Objective: Dental fear and anxiety describe negative feelings towards the dental environment, particularly significant in pediatric dentistry due to their cognitive, behavioral, and physical impacts on children. Managing this anxiety through positive dentist-child relationships and behavioral guidance techniques is crucial. This study aims to evaluate the effectiveness of passive distraction using music and Bach flower remedy in reducing dental fear and anxiety in children aged 6-8 years. Methods: This randomized controlled clinical study included 12 children (n=4 for each group) aged 6-8 years, randomly assigned to Group 1 (control), Group 2 (Bach flower remedy), or Group 3 (passive distraction with music) for treating superficial dentin caries in primary teeth without local anesthesia. Dental fear and anxiety levels were assessed using objective (heart rate, oxygen saturation, systolic and diastolic blood pressure) and subjective (Facial Image Scale and Venham’s Picture Test) measures before and after treatment. Results: The study included 12 children (6 female, 6 male) with a mean age of 7.3±0.8 years. In Group 2, heart rate significantly decreased after treatment (97.8 ± 10.1 to 90.5 ± 8.8, p.05). Conclusion: In this study, although passive distraction with music and Bach flowers did not have a significant effect on physiological and projective measurement tools in children with dental fear and anxiety, a decrease in heart rate was observed in children exposed to Bach flowers.

The Impact of Silver Diamine Fluoride Only or Simultaneously With Potassium Iodide Treatment on the Bond Durability of Resin Composite Material on Primary Teeth.

We aim to evaluate the bond strength between resin composite and primary demineralized dentin, pretreated with silver diamine fluoride (SDF) and simultaneous SDF with potassium iodide (KI) after thermal aging. In this in vitrostudy, human carious-free primary molars were randomly assigned into three groups and prepared by exposing the superficial dentin. The primary dentin of each molar was demineralized. The first group (the control) received saline treatment before bond application. SDF was pretreated for the second group, whereas SDF and KI were used for the third. After that, the pretreated dentin was immediately built with resin composite bonded with a universal adhesive and kept wet for 24 hours. Then, the pretreated molars were prepared into beam specimens for microtensile bond strength (µTBS), 16 for each group, and subjected to thermal aging. Lastly, they were tested using a universal testing machine, and the resulting data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test. It was found that the SDF-KI group had a significant difference with both the control and SDF groups (p < 0.05), while the control and SDF groups showed no significant differences (p =0.310). The SDF-KI group had the highest mean value of 11.73 ± 4.39 megapascal (MPa). In contrast, the control group had the lowest mean value of 9.31 ± 3.41 MPa. Post hoc pairwise comparison results showed that SDF-KI pretreatment had a significantly higher strength value than the control and SDF groups. Pretreatment of demineralized primary dentin with SDF-KI does not negatively affect the immediate loading of resin composite. However, under the limitation of this study, KI application after SDF pretreatment is recommended to enhance the bond's durability of resin composite to demineralized dentin.

Ozone and Laser Effects on Dentin Hypersensitivity Treatment: A Randomized Clinical Study

IntroductionThe aim of this study was to evaluate and compare the clinical efficacy of diode laser and ozone gas in the treatment of dentin hypersensitivity (DHS). MethodsOne hundred thirty-two teeth from 44 patients with moderate DHS were randomized into 3 groups according to a split-mouth design. In the diode laser group, the operator irradiated the superficial dentin exposed with an 808-nm wavelength and incremental power from 0.2 to 0.6 W with a 20-second interval. In the ozone gas group, the operator applied a high dose of ozone (32 g/m3) for 30 seconds using a silicon cup. In the placebo group, no therapy was applied. The dentin sensitivity level was evaluated upon enrollment (T0), immediately after treatment (T1), 3 months post-treatment (T2), and 6 months post-treatment (T3) with a cold air blast challenge and tactile stimuli. The pain severity was quantified according to the visual analogue scale. The Wilcoxon signed rank test was used to scrutinize potential statistical disparities among the treatments. Statistical significance was predetermined at P < .05. ResultsA significant decrease of DHS was observed in the ozone gas group and the `diode laser group immediately after treatment and after 3 and 6 months of the therapy. After 6 months from the therapy, the sensitivity values in the teeth treated with ozone gas remained statistically lower than those treated with diode lasers (P < .05). ConclusionsA laser diode and ozone gas are both efficient as dentin sensitivity treatment. Ozone maintains an invariable effectiveness after 6 months.

Microtensile Bond Strength of Different Bonding Agents to Superficial and Deep Dentin in Etch-and-Rinse and Self-Etch Modes.

Objectives: This study aimed to assess the microtensile bond strength (µTBS) of etch-and-rinse (E&R), self-etch (SE), and universal adhesives to superficial and deep dentin. Materials and Methods: In this in vitro study, 40 sound third molars were randomly divided into two main groups of superficial and deep dentin. Based on our classification, superficial dentin was right beneath the deepest occlusal groove, and deep dentin was 2mm beneath the deepest occlusal groove. Each group was divided into 4 subgroups (n=20) for application of Adper Single Bond 2 (ASB), Clearfil SE Bond (CSE), and Scotchbond Universal (SBU) in E&R and SE modes along with Charisma Smart composite resin on dentin. The specimens were incubated in distilled water at 37°C for 24 hours and their µTBS was then measured. The mode of failure was determined under a stereomicroscope at ×40 magnification. Data were analyzed by one-way ANOVA (alpha=0.05). Results: The highest µTBS belonged to the superficial dentin/SBU/E&R group. The µTBS was significantly higher in superficial dentin than deep dentin for all adhesives (P=0.005). There was no significant difference in mode of failure among the groups. Conclusion: Based on the results obtained in the present study, type of bonding agent and application mode affected µTBS. In use of universal adhesive, E&R mode can improve µTBS.

Effect of Naturally Derived Dentin Bio-modifiers on Immediate and Long-Term Bond Strength of Etch and Rinse Adhesive to Dentin

Purpose: To investigate the effect of 10% Proanthocyanidin (PA) rich grape seedextract (GSE) and cardanol oil applied for 60s on immediate and long-term shearbond strength (SBS) of etch and rinse to dentin. Materials and methods: The occlusalsurfaces of forty two samples were ground to expose flat superficial dentin surfaces.The samples were divided into 3 groups; Group A1 (control group) without any pretreatment,Group A2 (10 % GSE), Group A3 (cardanol). Pre-treatments were appliedfor 60s and then washed away for 30s. Each group was further randomly subdividedinto two groups (n=7) according to the storage time (immediate 24 hours) and (longtermsix months period). Shear bond strength (SBS) was tested using a universal testingmachine at a cross head speed of 0.5mm/min. Data was tabulated and presented asmean and standard deviation, one-way ANOVA, post hoc Tukey’s test for pairwise andPaired student t-test was performed between paired groups. Results: All pre-treatmentgroups showed statistically no significant SBS values after 24 hours of storage. Whileat 6 months storage, group A3 showed the highest SBS mean value followed bygroup A2 while Control Group recorded the lowest shear bond strength mean value.Conclusion: Natural dentin Bio-modifiers are considered effective in improving theshear bond strength of the bonded interface and the Bond strength of dentin is affectedby the storage time.

Effect of Naturally Derived Dentin Bio-modifiers on Immediate and Long-Term Bond Strength of Etch and Rinse Adhesive to Dentin

Purpose: To investigate the effect of 10% Proanthocyanidin (PA) rich grape seedextract (GSE) and cardanol oil applied for 60s on immediate and long-term shearbond strength (SBS) of etch and rinse to dentin. Materials and methods: The occlusalsurfaces of forty two samples were ground to expose flat superficial dentin surfaces.The samples were divided into 3 groups; Group A1 (control group) without any pretreatment,Group A2 (10 % GSE), Group A3 (cardanol). Pre-treatments were appliedfor 60s and then washed away for 30s. Each group was further randomly subdividedinto two groups (n=7) according to the storage time (immediate 24 hours) and (longtermsix months period). Shear bond strength (SBS) was tested using a universal testingmachine at a cross head speed of 0.5mm/min. Data was tabulated and presented asmean and standard deviation, one-way ANOVA, post hoc Tukey’s test for pairwise andPaired student t-test was performed between paired groups. Results: All pre-treatmentgroups showed statistically no significant SBS values after 24 hours of storage. Whileat 6 months storage, group A3 showed the highest SBS mean value followed bygroup A2 while Control Group recorded the lowest shear bond strength mean value.Conclusion: Natural dentin Bio-modifiers are considered effective in improving theshear bond strength of the bonded interface and the Bond strength of dentin is affectedby the storage time.

Microshear Bond Strength of Composite to Superficial Dentin by Use of Universal Adhesives with Different pH Values in Self-Etch and Etch &amp; Rinse Modes

Background: This study aimed to assess the microshear bond strength (micro-SBS) of two universal adhesives with different pH values in etch-and-rinse (E and R) and self-etch (SE) modes to superficial dentin.Materials and Methods: This in vitro experimental study evaluated 75 extracted sound human third molars. Superficial dentin was exposed by trimming the enamel and removing 0.5–1 mm of tooth structure beyond the dentinoenamel junction. A 600-grit abrasive paper was used to create smear layer. The teeth were randomly divided into five groups (n = 15). All-Bond Universal and G-Premio Bond were applied in E and R and SE modes in four groups. Clearfil SE Bond was used in the control group. Z350XT composite cylinders (0.9 mm diameter and 1.5 mm height) were then bonded to the prepared surface. The teeth were incubated at 37°C and 100% humidity for 24 h. Micro-SBS was measured by a universal testing machine, and the mode of failure was determined under a stereomicroscope. Data were analyzed using ANOVA, Bonferroni test, and Fisher's exact test (alpha = 0.05).Results: The micro-SBS of Clearfil SE Bond was significantly lower than all other groups (P < 0.05). All-Bond Universal yielded the maximum micro-SBS in SE and minimum micro-SBS in E and R mode. All-Bond Universal showed significantly lower micro-SBS in E and R mode than SE mode (P < 0.05). No other significant differences were noted. The mode of failure was also significantly different among the groups (P < 0.05). Mixed failure had the highest frequency in G-Premio in E and R mode.Conclusion: Type of adhesive and application mode affected the micro-shear bond strength to superficial dentin.

Comparison of shear bond strength of composite resin, compomer, and resin-modified glass-ionomer cements in primary teeth: An in-vitro study.

The contemporary esthetic restorative materials such as composite resin and glass-ionomer cements and their modifications have all been developed keeping in mind the requirements of permanent teeth. There have been plenty of studies that have focused on the characteristics of these materials in relation to permanent teeth with a relative dearth of such studies as regard to the primary teeth. The present study was undertaken to compare and evaluate the shear bond strength of composite resin, compomer, and resin-modified glass-ionomer cements in primary teeth. Thirty non-carious primary molars that were indicated for extraction because of physiological resorption or, for orthodontic reasons, were selected. The selected teeth were randomly allocated to three groups of 10 each for composite, compomer, and resin-modified glass-ionomer cements. The enamel from the occlusal surface of all teeth was removed to expose the superficial dentin and was wet polished with 400 grit sand paper. Composite, compomer, and resin-modified glass-ionomer stubs were bonded on to the occlusal surfaces using a plastic tube as a template. All samples were, then, subjected to thermocycling and evaluation of shear bond strength using the universal testing machine at a cross-head speed of 0.5 mm/min, whereas the results obtained were subjected to statistical analysis. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA), whereas one-way analysis of variance (ANOVA) and Tukey's multiple post-hoc procedures were used for statistical analysis. A P < 0.05 was considered statistically significant. The mean shear bond strength values for Groups I, II, and III were found to be 11.7 ± 3.07 MPa, 7.74 ± 4.16 Mpa, and 4.43 ± 2.08 Mpa, respectively, whereas one-way ANOVA and Tukey's multiple post-hoc procedures indicated that there were remarkable differences among the three groups with the results being statistically significant (P < 0.05). Composite resin showed the highest shear bond strength in relation to primary dentin when compared to compomer and resin-modified glass-ionomer cements.

Effect of quercetin pretreatment on the immediate and aged bond strength of bleached dentin

This in vitro study aimed to investigate the effect of quercetin pretreatment on the bond strength of bleached dentin. Human dentin blocks (2 × 2 × 1 mm) were prepared and randomly divided into 5 groups (n = 16): deionized water pretreatment + no bleaching treatment (DNB); deionized water pretreatment + bleaching treatment (DYB); 75 μg/mL quercetin pretreatment + bleaching (Q75B); 150 μg/mL quercetin pretreatment + bleaching (Q150B); and 300 μg/mL quercetin pretreatment + bleaching (Q300B). The surfaces of superficial dentin (bonding surfaces) were treated with the respective solutions for 2 min, and then the surfaces opposite to the bonding surfaces (near pulp, bleaching surfaces) were subjected to bleaching treatment with 40% hydrogen peroxide (Ultradent, USA) for two 15-min sessions (groups DYB, Q75B, Q150B, and Q300B). After the bleaching procedure, the bonding surfaces were bonded with resin cements (Panavia V5, Kuraray, Japan). The bonded specimens were then divided into 2 subgroups (n = 8): the aging group (subgroup T), which was subjected to 10,000 thermocycles, and the nonaging group (subgroup N), which was not subjected to thermocycling. The microshear bond strength (μSBS) was obtained using a universal testing machine (AGS-X, Shimadzu, Tokyo, Japan). Additional dentin blocks (5 × 5 × 1 mm) were prepared and treated the same as the groups DYB, Q75B, Q150B, and Q300B (n = 8) to evaluate the color change, defined as groups CCDYB, CCQ75B, CCQ150B, and CCQ300B, respectively. Color evaluation was performed using a spectrophotometer (Vita Easyshade Advance 4.0, Vident, USA) to obtain a baseline and again at the end of the bleaching treatment. The data were analyzed via two-way analysis of variance (ANOVA) and Tukey's post-hoc test (α = 0.05). For the immediate bond strength, the specimens in the groups Q75B, Q150B, and Q300B showed significantly higher μSBS values than those in the group DYB (all P < 0.05). No significant differences in the μSBS values were found among the groups Q75B, Q150B, Q300B, and DNB, respectively (all P > 0.05). For the aged bond strength, both the groups Q150B and Q300B exhibited significantly higher μSBS values than groups DYB and DNB (all P < 0.05), whereas no significance differences were found between groups Q150B and Q300B (P = 1.00) or between the groups DYB and DNB (P = 1.00). No significant differences were observed in the △E values among all the groups tested (P = 0.80). Therefore, the application of quercetin for 2 min prior to the bleaching procedure preserved the immediate bond strength and improved the aged bond strength of bleached dentin while maintaining the effectiveness of bleaching.

Comparative evaluation of shear bond strength of universal bonding agent and total-etch bonding agent on superficial and deep dentin

Background: To conserve the tooth structure, bonded restorations are popular nowadays. Bonding to enamel is predictable by acid-etch technique. However, bonding to dentin remains a challenge. Aim: To determine the better bonding agent between universal bonding agent and total-etch bonding agents based on shear bond strength using universal testing machine.&#x0D; Methodology: Eighteen human permanent mandibular molars were sectioned longitudinally to obtain thirty-six samples. Samples were randomly divided into three groups according to the bonding agent, Group A (Unbonded), Group B (Universal bonding agent) which was again divided into Subgroup B1 (Superficial dentin), Subgroup B2 (Deep dentin) and Group C (total-etch bonding agent) which was again divided into Subgroup c1 (Superficial dentin) ,Subgroup c2 (Deep dentin). Composite block was built up and samples were mounted in acrylic resin. Thermocycling was done and then samples were subjected to Universal testing machine. Statistical Analysis: The data was analysed using One-way ANOVA and Post hoc tests. Result: Universal bonding agent showed higher mean shear bond strength than total-etch bonding agent at both superficial and deep dentin level. Conclusion: The shear bond strengths of Universal Bonding agent and total-etch bonding agents were affected by the dentin level i.e., superficial and deep dentin.

Evaluation of bond strength of posterior restorative material with tooth treated with silverdiamine fluoride – Invitro study

Silver diamine fluoride (SDF) solution is being used in arresting dental caries in countries throughout the world since the 1970s. The mechanism of action is that silver-salts promote dentin sclerosis/calcification, silver nitrate has anti-microbial effects, and fluoride helps in the process of remineralization and prevention. The aim of this study is to evaluate the bond strength of posterior restorative material with tooth treated with silver diamine fluoride using universal testing machine60 premolar tooth were sectioned transversally and each root was embedded in cold-cure epoxy resin. The labial tooth surface was wet ground using silicon carbide discs to prepare a flat superficial dentin. The tooth were conditioned using 10% polyacrylic acid, and divided accordingly. Two increments of resin composite were placed into the plastic tubes of size 5mm X 3mm and each increments were light polymerized for 40 seconds. The same procedure was followed for glass ionomer cement. All specimens were stored at 37 in water for 24hrs before testing. The push out bond strength analysis was tested using the universal testing machine.The maximum push out bond strength is seen in GIC in dentin-21.85 N/mm, followed by the group with composite-19.27 N/mm and with the lowest value in the group containing SDF+KI+GIC-3.601 N/mm.Addition of Potassium iodide used to reduce the staining of the SDF does affect the bond strength of the restoration to dentin. GIC has the best bond strength with tooth, followed by composite among the groups.

Shear bond strengths of various resin cements between three types of adherends and bovine teeth with and without thermocycling.

This study evaluated the shear bond strengths of various types of resin cements between three types of adherends (composite resin, metal, and ceramic) and bovine teeth with and without thermocycling. A conventional resin cement (Variolink N), two adhesive resin cements (PANAVIA F 2.0, Multilink N), and three self-adhesive resin cements (MAXCEM ELITE, Rely X Unicem 2, Speed CEM) were used. The adherends were cemented on the superficial dentin of bovine incisors using each resin cement. Herein, 10 specimens from each group were thermocycled 5,000 times, and the other 10 were stored without thermocycling. With the resin and ceramic adherends, the shear bond strengths of Rely X Unicem 2 were significantly higher than those of the other resin cements both with and without thermocycling (p<0.05). With the metal adherend, the shear bond strengths were not significantly different among the cement groups, except MAXCEM ELITE, which showed the lowest strength.

Physicochemical and Mechanical Effects of Commercial Silver Diamine Fluoride (SDF) Agents on Demineralized Dentin.

To investigate the effects of four commercial silver diamine fluoride (SDF) agents on the chemical composition and microstructural properties of dentin, and its relation to the bond strength of two adhesives. Ninety human molars were randomly divided into sound dentin (negative control), demineralized dentin (positive control), and four experimental groups (n = 15) according to the SDF treatments (Cariestop [Biodinamica Quimica y Farmaceutica], RivaStar 1 [SDI], RivaStar 2 [SDI], and Saforide [Tokyo Seiyaku Kasei]). ATR-FTIR, x-ray diffraction, and SEM techniques were employed to characterize the compositional, crystalline, and microstructural properties of the samples. The microtensile bond strength test evaluated the bonding performance of two adhesives in demineralized dentin treated with SDF agents. Regarding the chemical composition, all SDF-treated groups showed a significantly higher phosphate:organic matrix ratio than the demineralized dentin group (p < 0.05). The XRD analyses revealed that the crystallite size for hydroxyapatite crystals increased on the surface areas (deep, medium, and superficial dentin) for all experimental groups compared to demineralized dentin (p < 0.05). SEM images showed that the behavior of the agents used differs on each surface treated. Bond strength values were adversely affected with both adhesive systems in the four experimental groups (p < 0.05). The application of SDF agents resulted in the formation of different crystalline phases of silver salts and the increase of mineralization of the pretreated demineralized dentin. However, SDF application showed a negative effect on the bond strength of the adhesives.

Effect of different adhesive strategies and storage time on bond strength of bi-functional monomers to simulated endodontically-treated dentin.

Adhesive strategies were evaluated on the bond strength of bi-functional monomers bonded to endodontically-treated-dentin (ETD). Superficial dentin was removed on human molars. Teeth were immersed in 5 mL 2.5% NaOCl, followed by immersion in 5 mL 17% EDTA. Dentin surface impregnated with epoxy resin-based sealer was then divided four groups (n=10): Scotchbond Multi-Purpose (SBMP); Single Bond Universal (SBU); Optibond All-in-One (OPB); and Tetric-N-Bond Universal (TBU). After 24-h or 1-year-of-storage specimens were submitted to microtensile bond strength (µTBS) and failure classification. A confocal laser scanning microscope (CLSM) evaluated the hybrid layer formation. Two-way ANOVA and Tukey-HSD test were performed (α=5%). The µTBS did not present statistical differences among adhesive strategies after 24-h. Significant differences were found after 1-year-of-storage. CLSM analysis showed water infiltration and consequently degradation of the hybrid layer after 1-year-of-storage. The use of SBU universal adhesive on the self-etching mode on ETD produced more stable bond over the 1-year-of-storage.

The Effect of Different Condition of Pulpal Pressure on Microtensile Bond Strength of Several Dentin Bonding Agents on Deep and Superficial Dentin.

The objective of this study was to examine the effect of different conditions of simulated hydrostatic pulpal pressure on the μTBS of HEMA-based and HEMA-free dentin bonding agents (DBAs). The influence of dentin location (deep and superficial) on μTBS was also evaluated. Flat coronal dentin surfaces of extracted human molars were prepared. Three groups of resin-bonded specimens were exposed to different pulpal pressures. Pulpal pressure was maintained for 20 min for each group. A flowable resin composite was used for coronal build-up. The bonded teeth were sectioned and, after 24 h of water storage, stressed to failure using the microtensile tester (μTBS). Failed samples were analyzed by SEM inspection. HEMA-based DBAs were much more sensitive to pulpal pressure conditions than non-HEMA-containing DBAs. Pulpal pressure had a greater influence in deep dentin. The HEMA-free DBA was insensitive to the presence or absence of pulpal pressure condition. SEM inspection confirmed a relationship between the presence of voids inside the HEMA-based DBAs layer and the lower μTBS results. HEMA-based DBAs are more sensitive to pulpal pressure conditions than HEMA-free DBAs. Interestingly, HEMA-free DBA showed a greater number of water droplets at resin–dentin interface in all tested conditions.

Comparative Evaluation of Resin Dentin Interface using Universal and Total- Etch Adhesive Systems on Sound and Eroded Dentin: In Vitro Study.

Objective This study aimed to compare the resin-dentin interface of sound and eroded dentin using universal and total-etch adhesive systems. Materials and Methods Forty caries-free extracted human premolars were collected, and the occlusal surfaces were ground by using slow speed diamond disc with copious water supply until a flat superficial dentin was exposed. The test group underwent erosive cycle (n = 20), and another group (n = 20) was reserved for control group. Erosive protocol consisted of immersion in 1.23% citric acid for 1 minute every 12 hours and stored in artificial saliva. Both the control and eroded teeth were further subdivided (n = 10) for composite restoration by using either self-etch or total-etch systems. Then the tooth samples were sectioned longitudinally and observed under confocal laser scanning microscope at ×10 magnification to evaluate resin tag length and hybrid layer thickness. Statistical Analysis The data obtained were analyzed by using independent t-test. Results The highest mean value of the resin tag length and thickness of hybrid layer was observed with total-etch system in sound dentin group compared with other groups (p < 0.001). Conclusion The resin-dentin interface of sound dentin was found to be better than eroded dentin by using total-etch system. The resin-dentin interface of eroded dentin was superior to sound dentin by using self-etch adhesive system.

Effect of three collagen crosslinkers on the shear bond strength of self – etch adhesive system to dentin at varying time intervals.

Abstract&#x0D; Background:&#x0D; When resin composite is bonded to dentin, the bond strength reduces with increase in depth of dentin. This is due to the increase in number of dentinal tubules, their diameter and less amount of intertubular dentin compared to “superficial dentin.21”&#x0D; Objective:&#x0D; This study proposes to improve bond strength of dentin to composite by biomodifying the dentin substrate prior to application of composite with three different crosslinking agents i;e Glutaraldehyde, Genipin and Riboflavin at varying time intervals.&#x0D; Method:&#x0D; 42 extracted maxillary incisor teeth were selected. Teeth were sectioned to mesial and distal halves. (n=84). Specimens were divided into 4 groups. Group I was used as control group and Glutaraldehyde, Genipin and Riboflavin crosslinking agents were applied to other groups (II, III, IV) respectively before applying composite resin. These groups were further subdivided into A and B groups based on time of applying crosslinking agent. Shear bond strength was calculated for all specimens using universal testing machine. Results were analysed using Student t test for intra-group and inter-group comparison.&#x0D; Results:&#x0D; Greater bond strengths were recorded in all the groups compared to the control group. Application of Glutaraldehyde and Genipin as crosslinking agents reported higher shear bond strength compared to application of Riboflavin. The mean shear bond strength values further increased with increased application time of crosslinking agent. &#x0D; Conclusion:&#x0D; Dentin surface pre-treatment with crosslinking agents at varying time intervals&#x0D; substantially improved the bond strength.&#x0D; &#x0D;

Advanced imaging of dentin microstructure

This study aimed to demonstrate the feasibility of using optical coherence tomography (OCT) for locating the sectioning site of a specimen before characterizing the ultrastructural features of dentin surfaces as well as the inner wall of the dentinal tubules (DT) using a field emission scanning electron microscope (FESEM). Eight sound human molar teeth were extracted, examined via cross-polarization optical coherence tomography (CP-OCT), embedded, and hemisectioned using a low-speed diamond sawing machine. Next, each sectioned surface was further trimmed, polished, and examined under a confocal laser scanning microscope (CLSM) to locate the target area on the superficial dentin. Subsequently, each section was gold-coated and examined using FESEM. Backscattered reflection from the dentin layer was less than that from the enamel under CP-OCT. Distinct reflections from certain enamel and dentin microstructures were observed before sectioning the specimens. Areas with enamel cracks and dentin defects were identified and avoided during sectioning. At the micron level, the CLSM images exhibited a homogenous distribution of the DT orifices. Low magnification FESEM images showed intertubular dentin as a loosely condensed globular layer with shallow grooves in between, whereas peritubular dentin exhibited more organized condensation of apatite crystals surrounding the DT orifices. High magnification of the DT revealed a cross-linking layer of mineralized collagen network extending in the peri-intratubular lumen, with scattered globules of matrix vesicles. CP-OCT enabled the realization of rapid initial scanning and image acquisition with high contrast at the micron scale before profound insights into dentin ultrastructures at the nano scale were provided by FESEM. The variations in structural densities of the dental tissues significantly affected the image contrast and helped identify underlying structures.

INFLUÊNCIA DO USO DA PROANTOCIANIDINA EM UM ADESIVO AUTOCONDICIONANTE: AVALIAÇÃO DA RESISTÊNCIA DE UNIÃO

Introdução: Os sistemas adesivos possibilitam a execução de restaurações estéticas e minimamente invasivas, sendo, portanto, objeto de pesquisas para contornar os problemas que se apresentam no procedimento restaurador. Objetivo: Avaliar in vitro a resistência de união de um sistema adesivo autocondicionante, e deste modificado com soluções extrativas de semente de uva. Metodologia: Duas soluções extrativas foram preparadas com extrato de semente de uva em pó dissolvido em acetona e etanol. A partir delas e de um adesivo, seis sistemas adesivos autocondicionantes experimentais foram preparados, diferindo quanto ao solvente utilizado e às proporções entre adesivo puro e solução extrativa, esta, variando em 7,5%, 15% e 30%. Setenta incisivos bovinos hígidos tiveram as raízes removidas com disco de carborundum e as faces vestibulares desgastadas com lixas d’água de granulação 120, 240, 600 e 1200 sob refrigeração até expor a dentina superficial. Os dentes foram distribuídos aleatoriamente em sete grupos distintos: Controle; A7,5; A15; A30; E7,5; E15; e E30, contendo 10 elementos cada. A aplicação dos adesivos foi executada de acordo com as recomendações do fabricante do adesivo controle. A restauração foi realizada com uma matriz de silicone com dimensões 2 mm de altura e 4 mm de diâmetro e inserido o material restaurador em incremento único e fotopolimerizado por 40s. Após três meses armazenados em água destilada, os espécimes foram submetidos ao teste de resistência de união. Foi empregado o método estatístico Teste Paramétrico Anova 1 Fator e pós- teste de Tamhane (p&lt;0,05). Resultados: Os grupos A7,5, E7,5 e E30 não apresentaram diferença em relação ao grupo Controle; A15 e A30 mostraram desempenho estatisticamente semelhante entre si; e E15 não apresentou diferença estatística em relação aos outros adesivos. Conclusões: A adição de proantocianidina teve efeitos diferentes, dependendo dos solventes e das concentrações utilizadas, mas sem alterar significativamente o desempenho do adesivo.