Shear Bond Strength Of Groups Research Articles

Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

AimThis study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS.MethodsNinety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined.ResultsSBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05).ConclusionThe bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

Comparison of shear bond strength of orthodontic metal brackets recylced using different methods: An in-vitro study

The aim of this study was to compare the effect of recycling orthodontic metal brackets by sandblasting with aluminum oxide particles of different sizes and by laser blow method after first and second rebonding /recycling. 120 human premolars extracted for orthodontic purpose were randomly divided into four groups. 40 MBT prescription Orthodontic metallic brackets were bonded on the buccal surface of the samples. Brackets were recycled by sandblasting with 3 different particles size and laser. Debonding of all brackets was performed using a universal testing machine and shear bond strength was determined. Brackets were examined under Field emission scanning electron microscope from each group at each level to compare the surface characteristic of new and rebonded brackets. Data were analyzed with paired test, ANOVA, and post hoc tests.The shear bond strength of group I (sandblasted with 25µm alumina) was significantly higher at the end of 1st recycling compared to group II(50 µm) and III(100 µm) but it was comparable to group IV(laser) at the end of 1st recycling. Group IV showed clinically significant higher shear bond strength compared to group II and III after 1st and 2nd recycling. The shear bond strength for group II and III (sandblasted with 50 and 110µm alumina) was significantly much lower after 2nd recycling as compared to new i.e., Control (p value<0.001⁎⁎⁎).25µm alumina sandblasting and Er-YAG laser blow method obtained better results after three successive recycling. Overall sandblasting emerged as the best method to recycle the orthodontic brackets.

Evaluation of Shear Bond Strength of Various Orthodontic Bracket Bonding Agents

Due to the development of properties of adhesive materials currently used in dentistry, the bonding ability between the brackets and the tooth enamel has been greatly improved. In general, in situations where cooperation can be obtained, adhesion of the orthodontic bracket through the conventional three-step process can show excellent bonding strength. However, if it is difficult to expect patient cooperation, as in the pediatric dentistry area, or if moisture isolation is not properly performed, the binding strength that does not reach the expected effect. As a result, various products that simplify the process for adhesion are being developed. The aim of this study was to evaluate and compare the shear bonding strength between the conventional 3-step adhesion system, self-etching primer system and one-step adhesion system that reduces the priming process. A total of 60 human maxillary, mandibular premolars were prepared. Group I (control group) were followed conventional 3-step bonding process. Group II were conditioned with self-etching primer. Group III were etched with 37% phosphoric acid and brackets were bonded with self-priming adhesive. The resultant shear bond strength of each group was measured and an adhesive remnant index (ARI) was recorded. The mean shear bond strength of group I, II, III were 14.69 MPa, 11.21 MPa and 12.21 MPa respectively. Significant differences could only be found between group I, II and group I, III (p < 0.05). The ARI indicated no significant difference among all groups.

Effect of Er:YAG, Co2 lasers, papain, and bromelain enzymes dentin treatment on shear bond strength of composite resin.

Effective bond strength of composite resin restoration leads to its durability, so evaluation of dentin surface treatment with enzymes and laser for higher bond strength is an important factor. Sixty human molar teeth were cut at a depth of 2 mm of occlusal part and divided into sixgroups (n = 10). G1: etched with 37% phosphoric, G2 and G3: 10% papain or bromelain enzymes were used on the dentinal surface, G4: 10% papain and bromelain enzyme mixture were used for. Then, the specimens were washed with distilled water. In G5 and G6: Er:YAG or Co2 lasers were used on the dentin surface. An adhesive system was applied and then nanohybrid composite was placed in teflon mold and lightcured. Samples were subjected to a shear bond strength (SBS) testby universal testing machines. Statistical analysis was performed, using one-way analysis of varianceand Tukey HSD tests (p < .05). The mean SBS in G1 was significantly higher in comparison with the other groups (p < .0001). On the other hand, a comparison of mean SBS between groups 2, 3, 4, and 5 shows no significant differences (p = .221). The mean SBS in group 6 (Co2 laser) was significantly lower in comparison with the other groups (p < .0001). Results showed that SBS of composite resin to dentin was not significantly affected, using either bromelain or papain 10% enzymes or erbium laser. Co2 laser had a negative effect on dentin and decreased the SBS. Phosphoric acid has the best result.

Effect of Er, Cr:YSGG laser enamel etching with varying power output and irradiation time on the shear bond strength.

BACKGROUND:Laser etching addresses the disadvantages of conventional acid etching technique, such as enamel decalcification and formation of white spot lesions. The aim of the present study was to evaluate and compare the shear bond strength (SBS), adhesive remnant index (ARI), and the surface characteristics of the samples treated with conventional acid etching and Er, Cr: YSGG laser etching with variable output power and time durations.METHODOLOGY:The study sample included 78 extracted teeth divided into six groups of 13 teeth each, and 3 samples from each group were utilized for analyzing etch patterns, and the remaining 10 teeth from each group were used for evaluating the shear bond strength. In Group I phosphoric acid etching was done, whereas in Group II– VI Laser etching 1.5 W/10 s, 1.5 W/15 s, 3 W/5 s, 3 W/10 s, 3 W/15 s. Statistical analysis for shear bond strength testing was performed using one-way ANOVA followed by Post HOC tests.RESULTS:The mean shear bond strength of Group I was 7.16 Mpa and Group III of 5.43 Mpa. Group II, IV, V, and VI had mean shear bond strength of 4.93 Mpa, 3.88 Mpa, 4.05 Mpa, and 4.88 Mpa, respectively. The ARI scores Group I had a significant number of samples with scores 2 other groups showed increased Score 0. The etch pattern of groups I, II, III showed the combined dissolution of both prism cores, and peripheries were seen. In group IV, the etching pattern was irregular with the pitted type of surface. In groups V and VI, relatively flat and smooth enamel surface was seen.CONCLUSION:The bond strength attained by laser etching (1.5 W/10 s and 1.5 W/15 s) was comparable to that obtained by the acid etching technique.

Shear bond strength of ceramic material veneered to zirconia core by layering and pressing techniques

Background: The advantages of the PFM systems are to combine the fracture resistance of the metal substructure with the aesthetic property of the porcelain. The present study compared the shear bond strength of ceramic material veneered to zirconia core by layering and pressing techniques.Materials and Methods: 50 samples of zirconia blocks were divided into 2 groups. Each group consisted of 25 samples. In group I, ceramic veneered over zirconia core by pressing technique and in group II, ceramic veneered over zirconia core by layering technique was used. The blocks were loaded up to failure which was assessed using universal testing machine.Results: The mean shear bond strength in group I was 13.4 MPa and in group II was 9.2 MPa. The difference found to be significant (P

Novel flash free APC brackets: An in vitro study

Objective: To analyze the time taken for the bonding, degree of flash, marginal leakage, bond strength and Adhesive Remnant Index of APC flash free brackets and APC PLUS brackets. Materials and Methods: 80 extracted human teeth (group A: APC flash-free adhesive n = 40, group B: APC Plus adhesive n = 40) were used to evaluate all the parameters mentioned above.Results: The time needed for bonding differed significantly between the two groups (A: 22.8s/ tooth; B: 35.8 s/tooth). The adhesive excess ranged from 206.6 µm to 87.7 µm (group A) and 872.9 µm to 325.5 µm (group B). The marginal leakage was observed to be higher in group B. The mean shear bond strength of group A was found to be 12.7 Mpa while group B had shown 10.47 Mpa. The maximum percentage of the group A and group B sample had shown ARI of 2. All the parameters had shown significant difference (p< 0.05) between the two groups. Conclusion: The flash free brackets had significantly reduced the time taken for bonding, reduced the degree of flash and had shown adequate bond strength. The new technology seems to facilitate a smooth adhesive-bracket and adhesive-tooth surface, which clinically might improve reduction of plaque accumulation.

Effect of 30% Grape Seed Extract on the Shearbond Strength of Orthodontic Adhesive Resin: An In-vitro Study

Introduction: Grape Seed Extract (GSE) contains Proanthocyanidins (PA) which have been shown to cross-link and strengthen demineralised dentin collagen. There is paucity of research to evaluate if grape seed extract increases the shear bond strength of orthodontic resin when bonding to enamel. Aim: To evaluate the shearbond strength and Adhesive Remnant Index (ARI) scores of enamel surface bonded with orthodontic resin after immersing in 30% of grape seed extract and compare the same with that of control group. Materials and Methods: In this in-vitro study, 72 extracted teeth samples were divided into two groups. The two groups, each with 36 specimens, included Group I (Control), Group II (Test). Teeth in the test group were soaked in 30% grape seed extract for 10 minutes before bonding and teeth in the control group were bonded directly without soaking in grape seed extract. Shearbond strength were measured using a Universal testing machine. To evaluate the amount of resin left on the enamel surfaces after debonding, ARI scores were used. The samples were subsequently evaluated using Scanning Electron Microscope (SEM) to study the surface characteristics of enamel after immersion in grape seed extract. Student t test was used to assess the difference between two groups in shear bond strength and Chi-square test was used for ARI scores. Results: Total of 72 teeth were analysed, 36 extracted teeth in each group. The mean shearbond strength in Group I was 78.9 Newton (N), 59.03 N in Group II. There was a stastistically significant differences in the mean scores of shearbond strength between the groups (p-value=0.0024). The shearbond strength of control group was significantly higher than the Test group. Significant difference(p-value=0.016) found in ARI scores between the two groups. In SEM analysis after grape seed extract conditioning followed by acid etching, pronounced cobble stone appearance was noticed indicating a type II etching pattern. Conclusion: Adhesive failure occurred at the resin and bracket interface indicating that shear bond strength reduces when teeth were immersed in Grape Seed Extract.

Effect of green tea and sodium ascorbate on the shear bond strength of orthodontic brackets bonded on bleached enamel: An in-vitro study

ObjectiveThe primary objective was to assess and compare the shear bond strength of orthodontic brackets bonded on bleached enamel with and without using an anti-oxidizing agent.The secondary objective was to compare the shear bond strength of brackets between the groups with anti-oxidant application along with immediate bonding and that of delayed bonding without any anti-oxidant treatment, on bleached teeth. Materials & methods75 premolars were collected and thereafter randomly distributed into the 5 groups. Group 1 to 4 had undergone bleaching with 10% carbamide peroxide and group 5 was control. Group 1 was bonded immediately after bleaching while bonding was delayed in group 4 for a period of 1 week. Groups 2 and 3 received the anti-oxidant treatment with 10% sodium ascorbate gel and 10% green tea gel respectively. Hounsfield universal testing machine was used for testing the shear bond strength. ResultsFor group 1, the shear bond strength was significantly lower (mean 4.9 MPa) than group 5 (mean 12.5 MPa). The significant differences were observed on comparing the shear bond strength of antioxidant-treated and delayed bonding groups with control (p < 0.05). Mean shear bond strength in groups 2, 3 and 4 were 7.5 MPa, 9.6 MPa and 5.8 MPa respectively. ConclusionThe bond strength of brackets reduces immediately after the bleaching procedure. The bond strength can be reversed either by delaying the bonding for a period of 1 week or by using the anti-oxidizing agents but it is not up to the level of unbleached enamel.

Effect of Atmospheric Pressure Plasma Treatment on Shear Bond Strength Between Zirconia and Dental Porcelain Veneer.

Various surface treatments on zirconia have been reported for dental porcelain veneer. However, it has not been determined which of these treatments provide the highest bond strength. The purpose of this study is to compare the effect of airborne particle abrasion and atmospheric pressure plasma treatment on the shear bond strength between zirconia and dental porcelain veneer. The groups were divided into four groups according to the surface treatment method: the control group, the atmospheric pressure plasma treated group (group P), the airborne particle abrasion group (group A), the atmospheric pressure plasma treated group after the airborne particle abrasion (group AP). Atmospheric pressure plasma was applied on the specimens using a plasma generator (Plasma JET, POLYBIOTECH Co. Ltd., Gwangju, Korea) and airborne-particle abraded with 110 µm. The characteristics of surface treated zirconia were analyzed by 3D-OP, XRD, XPS and contact angle. The shear bond strength was tested using a universal testing machine. The shear bond strength of group P was significantly increased compared to that of the control group (P < 0.05). The shear bond strength of group AP was significantly increased as compared to group A (P < 0.05). There was no significant difference between the group P and group A (P > 0.05). As a result of this study, the atmospheric pressure plasma treatment showed significantly higher shear bond strength than control group, but similar to the airborne particle abrasion, and the atmospheric pressure plasma treatment after the airborne particle abrasion provided the highest shear bond strength. This study demonstrated that application atmospheric pressure plasma treatment on zirconia may be useful for increasing bond strength between zirconia and dental porcelain veneer.

Influence of various types of surface modifications on the shear bond strength of orthodontic brackets on Y-TZP zirconia ceramics

The aim of this study was to investigate the bonding properties of metal orthodontic brackets and surface modifications applied to the surface of zirconia samples. Zirconia samples were divided into 4 groups according to surface modifications: group I, Er:YAG laser; group II, Nd:YAG laser, group III, air abrasion with silica-coated aluminum oxide; and group IV, hydrofluoric acid. After the application of surface modifications, central incisor brackets were bonded to zirconia surface and then subjected to thermocycling 2000× between 5 and 55 °C. The bonding properties of each sample were evaluated using a universal testing machine. The nonparametric Kruskal–Wallis and Mann–Whitney U statistical tests were applied to analyze the significant differences among and between the groups. The results showed that surface modifications significantly affected shear bond strength. Shear bond strength of group III (7.42 MPa) was significantly higher than those of other groups. Group IV (3.58 MPa) was significantly lower than those of other groups. Group III seems to be the most suitable surface treatment to be applied to zirconium surfaces in terms of high bond strength and safety. Group II and group III can be considered as more suitable alternatives group IV.

A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-Generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study.

ABSTRACTAimTo compare the shear bond strength of seventh- and eight-generation self-etch dentin bonding agents in primary teeth using universal testing machine.Materials and methodsForty extracted sound human primary molars were collected and randomly divided into two groups of 20 sample each. Shear bond strength of seventh-generation bonding agent [ADPER Single Bond Universal, (group II)] and eighth-generation bonding agent [Futurabond DC, VOCO Germany, (group I)] were calculated by using Universal Testing Machine (PTC/O83/ME, INSTRON, USA) and expressed in megapascals (MPa). Recorded data were compiled and subjected to statistical analysis using Student's t test.ResultsThe mean shear bond strength of group I (eighth-generation dentin bonding agent) and group II (seventh-generation dentin bonding agent) ranged from 22.10 to 37.10 MPa and 19.80 to 30.30 MPa, respectively Student's t test showed significantly different and higher (8.7%) shear bond strength in group I when compared to group II (p value = 0.017).ConclusionShear bond strength of eighth-generation dentin bonding agent (Futurabond DC) was better than seventh-generation dentin bonding agent (Adper Single Bond Universal).Clinical significanceAn effective bond to tooth would reduce marginal microleakage, bacterial penetration, postoperative sensitivity, possibility of pulpal inflammation, and preserve tooth structure by allowing minimal cavity preparation.How to cite this articleMishra A, Koul M, Upadhyay VK, et al. A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(3):225–229.

Effect of Displacement of Bracket Position after Initial Placement on Shear Bond Strength: An In vitro Study.

Context:Displacement of bracket after initial placement on tooth surface in the precure phase of bonding influences the shear bond strength.Aims:The aim of this study was to evaluate the influence of bracket displacement during the precure phase after initial placement on the tooth surface on shear bond strength of chemical cure and light cure composites.Settings and Design:In vitro experimental study.Subjects and Methods:Stainless steel orthodontic premolar brackets were bonded to the buccal surfaces of 88 maxillary 1st premolar teeth. Teeth were divided into four groups: (1) Group 1 – Control group for light-cure composites, (2) Group 2 – Displacement group for light-cure composites, (3) Group 3 – Control group for chemical cure composites, and (4) Group 4 –Displacement group for chemical cure composites. In the control groups, the brackets were bonded with no precure bracket displacement. In the displacement groups, the brackets were bonded with 2 mm precure linear displacement. Photoactivation was carried out for light-cure composites. Shear bond strength tests were carried out using the universal testing machine. Statistical analysis used: Data were analyzed using the one-way analysis of variance test.Results:The mean shear bond strength of Groups 1, 2, 3, and 4 were observed to be 14.49 ± 0.75, 13.40 ± 0.61, 12.34 ± 0.53, and 11.55 ± 2.43MPa, respectively, with the displacement groups showing lower shear bond strength when compared to the control groups. Whether displaced or not, chemically cured composites showed lower bond strength when compared to light-cured composites.Conclusions:Displacement of brackets during bracket placement seemed to reduce the enamel bond strength after the final positioning of the bracket.

Kekuatan Perlekatan Geser Tumpatan Semen Ionomer Kaca pada Dentin setelah Aplikasi Dentin Conditioner dan Cavity Conditioner

Backround: Smear layer formed during cavity preparation interfere with the adhesion between restoration and tooth structure and is considered a barrier that would degrade the quality of adhesion. Smear layer does not have a stable substrate for adhesion, gradually layer dissolves in the restorative material and cause microleakage, penetration of bacteria and inflammation of the pulp. Adhesion to dentin is more difficult to achieve than enamel, therefore the cleaning procedure on dentin require special treatment. Conditioner form a weak acid is used to remove the smear layer and surface contamination on the email or dentin which can reduce the adhesion of the material and the tooth surface. Dentin conditioner is an acid material containing 10% polyacrylic acid conditioner while Cavity conditioner an acid material containing 20% polyacrylic acid and 3% aluminum chloride. The higher the concentration, the more smear layer is dissolved in order to obtain adhesion of glass ionomer cements better because it is not blocked by the smear layer. Purpose: The purpose of this laboratory research is to study the shear bond strength of glass ionomer cement in dentin after application dentin conditioner and cavity conditioner .Material and Method: Twenty seven bovine cow's teeth were divided into three groups. Each group consisted of nine samples. Group 1 was control (without conditioner). Group 2 was treated with the Dentin conditioner. Group 3 was treated with the Cavity conditioner. Result: The average shear bond strength in group 1 is 3.31 Mpa, group 2 is 7.74 MPa and group 3 is 9.92 Mpa. Conclusion: There is a significant difference between third group and the shear bond strength of glass ionomer cement on dentin with application of the Cavity conditioner is higher than with application of the Dentin conditioner and without application conditioner

Evaluation of the shear bond strength of ceramic orthodontic brackets to glazed monolithic zirconia using different bonding protocols

AbstractAIM: The aim of this study was to evaluate the shear bond strength (SBS) of ceramic brackets to glazed monolithic zirconia using three different bonding protocols.MATERIALS AND METHODS: Forty-five monolithic glazed zirconia embedded into acrylic resin were randomly assigned to 3 groups (n = 15) following air abrasion by 50 μm aluminum oxide particles, the groups were treated with: (A) Assure Plus, (B) Silane + Assure Plus (C) Hydrofluoric acid + Silane + Transbond XT primer. Ceramic brackets were bonded to the zirconia discs using Transbond XT. Following thermocycling (500 cycles, 5° - 55° C), SBS, failure mode and Adhesive Remnant Index were assessed.RESULTS:Group C showed the highest SBS followed by Group B with no statistically significant difference. Most of the specimens in Group C showed an adhesive failure between the bracket base and the adhesive, whereas Group B presented mainly a mixed cohesive adhesive failure. SBS in Group A was significantly lower than either groups showing an adhesive failure at the zirconia- adhesive interface.CONCLUSIONS: Both Assure Plus + Silane and the classical ceramic bonding protocol achieved clinically acceptable SBS of ceramic brackets bonded to glazed zirconia. However, Assure Plus + Silane achieved better debonding characteristics.

Efecto del 10% de ascorbato de sodio aplicado durante diferentes períodos de tiempo sobre la resistencia al cizallamiento del material compuesto al esmalte blanqueado

Aims: Residual peroxide on the enamel surface and in the interprismatic spaces decreases the shear bond strength (SBS) of composite to bleached enamel. Evidence shows that 10% sodium ascorbate can efficiently neutralize the singlet oxygen generated by the bleaching agents. This study aimed to assess the effect of duration of application of sodium ascorbate on SBS of composite to bleached enamel. Materials and Methods: This in vitro experimental study was conducted on 30 sound human third molars, which were randomly divided into three groups (n=10). In group 1, the teeth were bleached for 45 minutes and were then subjected to immediate bonding and restoration with composite resin. In groups 2 and 3, the teeth were bleached, immersed in 10% sodium ascorbate solution for 5 (group 2) and 10 (group 3) minutes and were then bonded and restored with composite, and the SBS was then measured. Results: The highest SBS (14.02±8.6MPa) was noted in group 3 (immersion in 10% sodium ascorbate for 10 minutes before bonding). The lowest SBS was noted in group 1 (immediate bonding after bleaching) (p&lt;0.05). The difference in SBS of groups 1 and 2 was not significant (p=0.4). Conclusion: Application of 10% sodium ascorbate for 10 minutes increases the SBS of composite to bleached enamel.

Comparison of shear bond strength of traditional 3-step composite with self etch primer and composite.

The revolution in orthodontics has been due to replacement of cemented bands by orthodontic brackets. Acid etching is required to bond a bracket on tooth’s surface. Traditional three step acid etch procedure consisted of etching, sealing/priming and bonding. The self etch system (etchant and primer together) can be used without the need for surface preparation, saving chair side time and minimizing contamination. Objectives: To compare the shear bond strength (SBS) of orthodontic bracket bonded with Conventional etching primer (Transbond XT, 3M Unitek) with self etch primer (Adper Prompt L-Pop, 3M ESPE). Study Design: Prospective study Setting: Orthodontic Clinic of Ihsan Mumtaz Hospital, Lahore and PCSIR (Lahore). Period: 6 months from June 2018 to December 2018. Material and Methods: 60 human maxillary premolars were randomly divided into 2 groups of 30 each. Group-I was bonded with conventional etching primer + composite and Group-II was bonded with self etch primer + composite. Shear bond strength was measured through Ionstron force testing machine. Statistical Analysis: For each variable, shear bond strength, arithmetic mean, standard deviation, minimum and maximum values were calculated. t-test was used to compare the shear bond strength (SBS) of the two groups and P value less than and equal to 0.05 was considered significant. Results: The mean shear bond strength in group 1 and group II was10.5MPa and 7.36MPa respectively. Conclusion: The shear bond strength of Conventional etching primer + adhesive was significantly higher than the shear bond strength of self etch primer +adhesive group.

Effect of hydroxyapatite nanoparticles on enamel remineralization and estimation of fissure sealant bond strength to remineralized tooth surfaces: an in vitro study

BackgroundThe management of noncavitated caries lesions before sealant therapy is a clinical challenge when the tooth needs sealant application. Sealing noncavitated carious lesions in pits and fissures may lead to failure of the fissure sealant (FS) due to incomplete sealing. Therefore the use of remineralizing agents such as nanoparticles has been suggested. This study investigated the ability of hydroxyapatite nanoparticles (nano-HA) to remineralize enamel, and their effect on sealant microleakage and shear bond strength (SBS).MethodsA total of 192 third molars were demineralized and pretreated with two concentrations of nano-HA with and without sodium hexametaphosphate (SHMP), followed by phosphoric acid etching and resin FS application. The study groups were 1) etching + FS, 2) etching + nano-HA 0.15% + FS, 3) etching + nano-HA 0.03% + FS, 4) etching + mixture of nano-HA 0.15% and SHMP 0.05% + FS, 5) etching + mixture of nano-HA 0.03% + SHMP 0.01% + FS. The laboratory tests included microleakage in 50 teeth, scanning electron microscopy (SEM) evaluation in 10 samples, and SBS in 100 samples. Enamel remineralization changes were evaluated in 32 teeth with energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM).ResultsNano-HA enhanced the SBS to remineralized enamel in a large percentage of nanoparticles. Mean SBS in group 2 was significantly greater than in groups 1, 3 and 4 (all P < 0.05). SBS was related to nano-HA concentration: nano-HA 0.15% yielded greater SBS (16.8 ± 2.7) than the 0.03% concentration (14.2 ± 2.1). However, its effect on microleakage was not significant. Nano-HA with or without SHMP led to enhanced enamel remineralization; however, the Calcium (Ca)/Phosphate (P) weight percent values did not differ significantly between the groups (P > 0.05). SEM images showed that SHMP did not affect sealant penetration into the deeper parts of fissures. FESEM images showed that adding SHMP led to increased nanoparticle dispersal on the tooth surface and less cluster formation.ConclusionsThe ultraconservative approach (combining nano-HA 0.15% and SHMP) and FS may be considered a minimal intervention in dentistry to seal demineralized enamel pits and fissures.

Comparison of Shear Bond Strength of Different Wire-Composite Combinations for Lingual Retention: An in Vitro Study

Context: As lingual bonded retainers are required for long-term retention in the oral cavity, the wire-composite combination of choice may be the determining factor for the success of lingual bonded retainers. Aim: We compared the shear bond strength of different wire-composite combinations used for lingual bonded retainers and identified the combination of choice for lingual retention in terms of the shear bond strength. Materials and Methods: A total of 108 extracted human maxillary premolars in pairs were divided into 6 groups of 9 samples each. Three different types of retainer wires (namely, Respond [Ormco Corp., Orange, CA, USA], Leone Ligature Wire [Leone S.p.a., Firenze, Italy], and SRW™ Stranded Retention Wire [Ortho Classic Inc., USA]) were bonded to the teeth with the composites (G-aenial™ Universal Flo and Tetric N-Flow). The shear bond strength was measured on debonding using universal testing machine INSTRON. Results: The maximum shear bond strength (58.28 N) was observed in group IV (Respond wire with Tetric N-Flow), whereas the minimum (25.28 N) was observed in group VI (SRW™ Stranded Retention Wire with Tetric N-Flow). A highly significant difference was observed when the shear bond strength of group IV was compared with all the other groups. Conclusions: The maximum shear bond strength was observed in the wire-composite combination of Respond dead-soft wire with Tetric N-Flow composite. Therefore, it could be the wire-composite combination of choice for bonded lingual retainer.

Bonding performance of a self-adhering flowable composite resin to different deciduous surfaces

Objective: Evaluation of the shear bond strength of self-adhering flowable composite-resin to different surfaces of deciduous molars.Methods: Eighteen-freshly extracted sound human deciduous molars were used. The teeth were embedded in acrylic blocks, such that their buccal surfaces were shown and aligned with the acrylic surfaces. The teeth were randomly divided into three groups. Group I: enamel surfaces without any intervention (Uncut Enamel), Group II: enamel surfaces with minimal grinding (Cut Enamel) and Group III: dentin surfaces. For all groups, self-adhering flowable composite-resin (DyadTM-flow, Kerr, USA); was applied. Specially designed holed-split Teflon mould was used for constructing composite - resin cylinders (3×3mm) over the buccal surfaces of the mounted teeth. The DyadTM-flow was applied in a central hole of the mould upon tooth surface, and then light cured for 20 seconds. The teeth were stored in distilled water at 37OC for 24 hours. The strength was recorded blindly by a different assessor using universal testing machine and statistically analyzed. Modes of failure were studied using digital microscope.Results: Mean values of shear bond strength for groups I, II, III were 9.6, 5 and 3.6 MPa respectively, with statistically insignificant difference P=0.09 (P value≥0.05). Some specimens showed spontaneous de-bonding after water storage [group I (33.3%) and III (83.33%)]. Failure mode was 100% adhesive failure in all groups. Conclusions: Bonding of DyadTM-flow was highest in uncut enamel however further material improvement may be required.