Enamel Conditioning Research Articles

Enamel Deproteinization or Sandblasting for Enamel Reconditioning Before Acid Etching to Enhance the Shear Bond Strength of Metallic Brackets in a Third Bonding: An In Vitro Study.

Enamel conditioning with 37% phosphoric acid is the most common technique during orthodontic bracket bonding procedures. However, due to the repeated de-bonding of the orthodontic brackets during treatment, other methods were needed to condition the enamel surface and increase the bond strength. This study aimed to compare the effect of conditioning the enamel surface by sandblasting with aluminum oxide particles or 5.25% sodium hypochlorite gel in combination with acid etching compared to acid etching alone on shear bond strength (SBS). One hundred eight extracted upper premolars were randomly divided into three groups according to the conditioning enamel surface method. After the first and second bonding of metal brackets, new metal brackets were bonded with a total-etching adhesive after enamel conditioning using different methods: acid etching only (37% phosphoric acid for 30 seconds) (AE group), sodium hypochlorite associated with acid etching (5.25% NaOCl gel for 60 seconds and then acid etching for 30 seconds) (NaOCl-AE group), and sandblasting associated with acid etching (sandblasting for five seconds and then acid etching for 30 seconds) (SB-AE group). The shear bond strengths of the brackets were tested with a universal testing machine. One-way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) tests were used to detect significant differences in shear bond strength among groups at the third bonding. Repeated-measure ANOVA and Bonferroni's tests were used to detect significant differences in shear bond strength among the bonding attempts within each group. 5.25% sodium hypochlorite associated with the acid etching method produced significantly greater shear bond strength than sandblasting associated with acid etching and acid etching only methods at the third bonding (16.40 ± 5.80 MPa, 13.60.47 ± 6.40 MPa, and 9.90 ± 4.40 MPa, respectively; P < 0.001). However, there was no significant difference between the AE and SB-AE groups (P = 0.247). In addition, we found a significant decrease in the shear bond strength within each group after each bonding attempt. Conditioning the enamel surface with 5.25% sodium hypochlorite associated with acid etching produced greater bond strength than conditioning by sandblasting associated with acid etching and acid etching only at the third bonding. The bond strength of the metal bracket decreased with increasing bonding attempts, even with the application of enamel surface conditioning methods.

Pretreatment of enamel with Riboflavin activated photodynamic therapy and Er, Cr: YSGG laser for bonding of orthodontic bracket with adhesive modified with cerium oxide nanoparticles

AimTo assess the degree of conversion (DC) and shear bond strength (SBS) of experimental adhesive (EA) infused with and without 1 % Cerium oxide (CeO₂)-NPs on metallic bracket bonded to enamel conditioned with three different pretreatment regimes PDT-activated (Riboflavin) RF, ECY (Er, Cr: YSGG), and Phosphoric acid (PA). Material and MethodEA and EA modified with 1 % CeO₂-NPs were prepared. Characterization of CeO2NPs was assessed using a scanning electron microscope (SEM). Seventy-two premolars extracted due to periodontal or orthodontic reasons were disinfected. Samples were mounted and allocated into three groups according to enamel surface treatment before bracket bonding. Samples in Group 1 were pretreated with Traditional 37 % PA-gel; Specimens in Group 2 surface treated with RF-activated PDT, and samples in Group 3 were conditioned using ECY. Brackets were placed on conditioned surfaces and samples were aged and underwent SBS testing using UTM. ARI index was used to assess bond failure. DC was evaluated for both adhesives using FTIR. ANOVA and Tukey post hoc test were used to compare the means and standard deviation (SD) of SBS and DC in different experimental groups. ResultsEnamel conditioned with PA and RF activated by PDT demonstrated comparable bond values with 1 % CeO2 infused in EA and EA (p>0.05).ARI analysis shows that enamel conditioned with PA and RF activated by PDT showed the majority of failure types between 1 and 2 irrespective of the type of adhesive. DC value in EA (73.28±8.37) was the highest and comparable to 1 % CeO2 infused in EA (66.48±6.81) ConclusionRF-activated PDT can be used alternatively to 37 % PA for enamel conditioning when bonding metallic brackets. Infiltration of 1 % CeO2 NPs in EA improves SBS irrespective of the type of enamel conditioning. Infusion of 1 % CeO2 NPs in EA demonstrates no significant difference in DC compared to EA.

EFFECT OF 4 wt% HYDROXYAPATITE PASTA ON DENTAL EMAIL HARDNESS

Introduction: Dental erosion can affect the dental demineralization due to the pH level that is below the critical pH of 5,5 resulting a decrease in dental enamel hardness. Remineralization is needed to bring back the mineral loss. Hydroxyapatite is similar to inorganic components in dental enamel dan have biocompatible properties. Hydroxyapatite with 4 wt% concentration has a Ca/P molar ratio close to 1,67, which is similar to the human enamel and can regenerate enamel. This study is aimed to analyze the effects of 4 wt% hydroxyapatite paste on dental enamel hardness for 7 and 14 days. Material and Methods: 20 maxillary premolars were divided into 4 groups. Group A1 were applied with 4 wt% hydroxyapatite paste for 30 minutes each day for 7 days, group A2 were applied with 4 wt% hydroxyapatite paste for 30 minutes each day for 14 days, group B1 were immersed with artificial saliva for 7 days, and group B2 were immersed with artificial saliva for 14 days. All groups were immersed with artificial saliva and was incubated for 24 hours at 37°C. Hardness measurements were carried out at the start, after erosion, and at the end of the experiment. Dental enamel hardness was measured with Vickers Hardness Tester (Shimadzu HMV G-21 Series). Dental enamel hardness data were analysed with GLM Repeated Measure ANOVA test (p&lt;0,05) and One-way ANOVA test (p&lt;0,05). Results and Discussions: The result showed dental enamel hardness number after 4 wt% hydroxyapatite paste application showed significant difference than untreated group, which was immersed in artificial saliva. Dental enamel hardness number after 4 wt% hydroxyapatite paste application for 14 days showed significant difference than 7 days. Conclusion: It can be concluded that 4 wt% hydroxyapatite paste application for 14 days resulted in an increase of dental enamel hardness as in normal condition of dental enamel before erosion

Clinical performance of preheating thermoviscous composite resin for non-carious cervical lesions restoration: A 24-month randomized clinical trial

ObjectivesThis 24-month, double-blind, split-mouth randomized clinical trial aimed to compare the retention rates of a preheated thermoviscous composite resin (PHT) compared to a non-heated composite resin (NHT) in non-carious cervical lesions (NCCLs). MethodsA total of 120 restorations were restored on NCCLs using a preheated (VisCalor bulk, Voco GmbH) and a non-heated (Admira Fusion, Voco GmbH) composite resins with 60 restorations per group. A universal adhesive in the selective enamel conditioning was applied. In the PHT group, composite was heated at 68 °C for using a bench heater. In the NHT group, no heating was employed. Both restorative materials were dispensed into caps and inserted into the NCCLs. The restorations were evaluated at baseline, 6, 12, 18, and after 24 months of clinical service using the FDI criteria. Statistical analysis was performed with Kaplan–Meier estimation analysis for retention/fracture rate and Chi-square test for the other FDI parameters (α=0.05). ResultsAfter 24 months 108 restorations were assessed. Seven restorations were lost (two for PHT group and five for NHT group), and the retention rates (95 % confidence interval [CI]) were 96.7 % (81.5–99.9) for PHT group and 90.8 % (81.1–96.0) for NHT group, with no statistical differences between them (p > 0.05). The hazard ratio (95 % CI) was 0.52 (0.27 to 1.01), with no significant difference within groups. In terms of all other FDI parameters that were assessed, all restorations were deemed clinically acceptable. ConclusionsBoth composites showed high rates of retention rates after 24 months. Clinical significanceThe clinical performance of the new preheated thermoviscous was found to be as good as the non-heated composite after 24-month of clinical evaluation in non-carious cervical lesions. Registration of clinical trialsRBR-6d6gxxz

Correction to: In vitro comparison of new generation adhesive systems in enamel conditioning with ER: YAG laser: SBS and ARI analysis

Correction to: In vitro comparison of new generation adhesive systems in enamel conditioning with ER: YAG laser: SBS and ARI analysis

To evaluate the effect of different enamel conditioning procedures on the shear bond strength of new metal bracket on previously debonded tooth surface - An in-vitro study

To evaluate the efficacy of different enamel conditioning methods while bonding a new bracket on a previously de-bonded site, and assess the difference in shear bond strength and ARI score if any. 125 human-extracted premolars were selected. 250 premolar brackets were procured. 125 brackets were bonded on the buccal surface of the premolars using different enamel conditioning methods (bonding sequence 1) and was followed by debonding using the Instron Universal testing machine (Debonding procedure I).The remaining 125 brackets were bonded (Bonding sequence II) on the same teeth after the removal of residual adhesive. Bonding sequence II was followed by debonding (Debonding procedure II), shear bond strength calculation, and ARI score calculation. There was a significant difference in SBS between the 5 groups after initial debonding. SEP group (group 4) showed the highest SBS followed by acid etching groups (groups 3, 2, and 1). The sandblasting group (group 5) had the lowest shear bond strength value. After the second debonding, SBS was found to be highest in Group 3 {37% o-phosphoric acid (Bonding I) sandblasting (Bonding II)} followed by Group 4 {SEP (Bonding I and Bonding II)}, group 2 {acid etching (Bonding I) SEP (Bonding II)}, and group 1 (acid etching in both bonding sequences). Group 5 (sandblasting in both sequences) had the least SBS. Non-significant differences were found in ARI score of the five groups. Self-etching primer group had highest SBS and sandblasting group had least SBS after first debond. The SBS of new brackets after two debonding procedures significantly decreased but was still found to be above the required bond strength. SEP and sandblasting can be used as a substitute to acid etching technique in second time bonding of brackets as these groups had higher SBS after second debond.

Surface Roughness of Er, Cr: YSGG Laser Etched Enamel Compared to Acid Etching: An In Vitro Study

Objectives: Erbium-based lasers have been used in dentistry with different parameters for enamel conditioning with controversial results on the optimum parameter. This study aims to compare the surface roughness of enamel after conditioning by erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser or 37% phosphoric acid and after remineralization, using a scanning electron microscope (SEM). Materials and Methods: Forty-five extracted premolars for orthodontic purposes were divided into three groups according to the conditioning technique. Group 1 conditioning by Er, Cr: YSGG laser 4.5 watts/30 Hz, Group 2 conditioning by Er, Cr: YSGG laser 4.5 watts/ 20 Hz, and Group 3 conditioning by 37% phosphoric acid. Surface roughness was measured using SEM after conditioning and after remineralization using Recaldent GC MI Paste Plus. Statistical analysis was done by one-way analysis of variance ANOVA test used to compare between groups, followed by Tukey’s post hoc test. Results: Enamel surface conditioned by Er, Cr: YSGG 4.5 watts/20 Hz laser had significantly less surface roughness than 37% phosphoric acid conditioned. After remineralization both the laser groups produced significantly lower surface roughness compared to acid conditioning. Conclusion: Er, Cr: YSGG laser conditioning of enamel surfaces (with 4.5 watts and 20 Hz/ 30 Hz frequency) produced less surface roughness which could be used as a promising alternative for acid conditioning. Clinical Relevance: laser conditioning of enamel using Er, Cr: YSGG with 4.5 watts could be a promising alternative for acid conditioning since it produces less surface roughness, less plaque accumulation on the surface, and less bacterial adhesion.

Incorporation of Zirconium Oxide Nanoparticles in Adhesive Resin for Bonding of Brackets to Enamel Conditioned with Er,Cr:YSGG, Photodynamic Therapy, and Phosphoric Acid.

Objective: To evaluate the effect of enamel conditioning methods, that is, total-etch and rinse (TER), Er,Cr:YSGG (ECYL), and photodynamic therapy (PDT) on the shear bond strength (SBS) of orthodontic metallic brackets bonded using Zirconium oxide experimental adhesive (ZOEA). Methods: Sixty human incisor buccal surfaces were cleaned and allocated into three groups based on the method of enamel surface treatment, that is, TER using 37% phosphoric acid gel, methylene blue photosensitizer activated by PDT and ECYL (n = 20 each). Each group was further divided into two subgroups (n = 10) based on the type of adhesive, that is, ZOEA and experimental adhesive (EA). Metallic brackets were seated using composite resin. Samples were placed in a universal testing machine for SBS and failure mode using the ARI index. One-way analysis of variance and post hoc Tukey were used for multiple comparisons. ARI was presented in percentages in different investigated groups. Results: TER+ZOEA (17.16 ± 0.41 MPa) displayed the highest bond integrity. However, group PDT+EA (11.34 ± 0.25 MPa) demonstrated the lowest bond scores. The intergroup comparison revealed that the TER system displayed significantly higher SBS values than the PDT and ECYL groups (p < 0.05). The intragroup comparison revealed that enamel conditioned with TER and brackets bonded with ZOEA and EA displayed comparable bond integrity (p > 0.05). Conclusions: Enamel conditioned with TER bonded to a metallic bracket displayed better bond strength than PDT and ECYL. Zirconium oxide nanoparticles incorporated in adhesive have proved to be promising in improving the bond integrity of adhesive.

Quantitative light-induced fluorescence (QLF) for diagnosis of enamel condition during various dental procedures

Relevance. Quantitative light-induced fluorescence (QLF) is widely used to diagnose the enamel condition during various dental interventions and allows for quick, objective and noninvasive assessment of the patient's oral hygiene status and follow-up of enamel de- and remineralization level.Materials and methods. The QLF technique used by the study increases the visual contrast between sound and diseased oral tissues when various (organic) substances in the mouth absorb light of a certain wavelength (different colours) and then re-emit the absorbed energy at a different wavelength. Filtration of illuminating light gives a fluorescent image or a QLF image. In a clinical setting, we used a QLF equipment set, namely, the Q-ray clinical software; Qraycam pro camera for full-arch imaging; Qraypen C intraoral camera; Qscan plus.Results. QLF was an additional tool for a practising dentist or dental hygienist, which allowed for the detection of the pathological process at the earliest stage, assisting in the diagnosis of the dental enamel condition, the detection of plaque without disclosing agents and assessment of its exact amount, contributing to the identification of hidden foci of enamel demineralization and carious lesions, cracks, tartar and oral hygiene evaluation.The analyzed data show the very high efficiency of the performed therapy with the 'R.O.C.S. medical 0+' remineralizing gel. The objective QLF data fully confirm the external elimination of white spots, and their almost complete disappearance is noted.Conclusion. Quantitative light-induced fluorescence and its parameters are essential not only for understanding the effectiveness of the applied techniques for bleaching, microabrasion, remineralization and other manipulations but also for their safety for dental enamel.

In vitro assessment of bracket adhesion post enamel conditioning with a novel etchant paste

Background: 37% phosphoric acid (PA) is the traditional enamel etching technique prior to bracket ‎adhesion, yet it has been implicated in numerous enamel injuries. The purpose of the current study was to create a calcium phosphate (CaP) etching paste in a ‎‎simplified capsule ‎formula that can underpin clinically ‎adequate bracket bond strength ‎without jeopardizing the ‎integrity of enamel upon ‎the debracketing procedure. Materials and Methods: micro-sized hydroxyapatite (HA) powder was mixed with 40% PA solution to prepare ‎experimental acidic CaP paste. Sixty human premolars were ‎assigned into two groups of 30 each. ‎Enamel conditioning was accomplished using 37% PA-gel‎ for control group and CaP paste for experimental group. Each group was further divided into two subgroups regarding the water storage (WS) period (24 h and 30 days). Shear bond strength (SBS) test conducted with examination of debonded surfaces for adhesive remnants and enamel damage using a digital microscope. Results: CaP paste produced significantly lower SBS values than PA (p &lt; 0.01), yet sufficient for clinical use. PA etching caused often cracked enamel surfaces with excessive ‎retention of adhesive remnants (mainly ARI scores 2 and 3). Contrarily, enamel treated with the experimental CaP paste exhibited smooth, ‎unblemished surfaces mostly clean of adhesives residues (scores 0 and 1). Conclusion: a newly developed CaP paste in a capsule formula fosters ‎clinically adequate bracket ‎adhesion with a sustained bonding performance, allows a harmless bracket removal with ‎minimal or no adhesive residues on debonded surfaces; thus, it can be introduced as a suitable ‎alternative to PA‎.

Crown tissue proportions and enamel thickness distribution in early Pleistocene Homo antecessor maxillary premolars (Atapuerca, Spain)

AbstractObjectivesBoth morphometric and proteomic studies have revealed the close relationship of Homo antecessor with Neanderthals and H. sapiens. Considering this relationship, we aim to characterize the Early Pleistocene Atapuerca‐Gran Dolina (TD6) maxillary premolars to test if their pattern of enamel thickness is shared with Neanderthals or H. sapiens.Materials and MethodsWe employed microcomputed tomography to estimate 2D and 3D tissue proportions in seven H. antecessor maxillary premolars, belonging to two individuals: H1 and H3, and compared them to a sample of extinct and extant Homo populations of African, Asian and European origin (n = 52).ResultsOur results reveal a different pattern of enamel thickness between the Atapuerca‐Gran Dolina two individuals. While TD6‐H1 possesses thin‐enameled crowns, with a clear affinity with Neanderthals, TD6‐H3 exhibits the thick pattern, a trait shared with the majority of fossil hominins and H. sapiens.DiscussionThis work provides new data on upper premolar enamel thickness in H. antecessor. By documenting both a thin and a thick pattern of enamel thickness in the TD6 sample, we warn about the taxonomic utility of this feature in the characterization of isolated remains. We suggest that the thin enamel condition would have emerged during the Early Pleistocene and it became the most frequent and typical condition in Neanderthals. Possible causes for the pattern observed in TD6 include sexual dimorphism or presence of two populations in the sample; however, population variability is the most plausible explanation with a character expression intermediate between those of Neanderthals and other members of the genus Homo. This interpretation is compatible with the phylogenetic position of H. antecessor close to the ancestor of Neanderthals and H. sapiens.

Evaluation of the Effect of Enamel Deproteinization Combined with a Self-etching Primer on the Adhesion of Orthodontic Brackets: An In Vitro Study

Aim:The study aimed to evaluate enamel deproteinization with sodium hypochlorite in the enamel conditioning using a self-etching primer for adhesion in orthodontic brackets.Background:The bonding in orthodontics plays a major role in the success of the treatment. The self-etching primers reduce the chair time and diminish the risk of saliva contamination.Methods:The sample comprised 80 bovines' incisors, divided into 4 groups according to the deproteinization process and adhesive system used: G1: enamel deproteinization + Transbond Plus self-etching primer + Transbond XT adhesive; G2: enamel deproteinization + 37% phosphoric acid + conventional primer + and Transbond XT adhesive; G3: Transbond Plus self-etching primer + Transbond XT adhesive; and G4: 37% phosphoric acid + conventional primer + Transbond XT adhesive. EMIC®DL 500 Universal Testing Machine was used for testing the shear bond strength of the samples.Results:Brackets bonded with self-etching primer showed greater adhesion force. The enamel deproteinization did not improve the bonding strength, regardless of the primer used.Conclusion:The deproteinization process does not improve the result of the adhesive bonding when using a self-etching primerin vitro.

Incisor enamel microstructure of West Indian caviomorph hystricognathous rodents (Octodontoidea and Chinchilloidea)

Analysis of the incisor enamel microstructure of extinct and extant West Indian caviomorph rodents emphasizes a clear microstructural distinction between the Echimyidae (Capromyinae and Heteropsomyinae) among Octodontoidea and the “Heptaxodontidae”, whose phylogenetic affinities are debated. All capromyines and heteropsomyines have a pattern of enamel characterized by a rectangular crystallite arrangement, which is biomechanically strongest in limiting crack propagation most efficiently (subtype [Sbt.] 3 of multiserial Hunter-Schreger bands [HSBs]). This enamel condition is exclusive to all mainland octodontoids. In stark contrast, “heptaxodontids” sampled here exhibit much less derived enamel subtypes of multiserial HSBs, with parallel to acute angular crystallite arrangement (Sbt. 1 [Clidomys], Sbt. 1–2 [Elasmodontomys], and low acute Sbt. 2 [Amblyrhiza]), less well adapted for prevention of crack propagation. The incisor enamel microstructure of Amblyrhiza and Clidomys is consistent with a chinchilloid assignment, as reflected by the anatomy of their auditory region and their unusual dental pattern. For Elasmodontomys, the primitive condition of its incisor enamel is difficult to reconcile with its highly nested phylogenetic position within the Octodontoidea clade (among the Capromyinae), as recently inferred from aDNA analyses. The different enamel patterns among extinct and extant West Indian caviomorphs indicate distinct high-level taxonomic groups, but restricted to the Octochinchilloi (Octodontoidea and Chinchilloidea) among Caviomorpha. The great diversity of caviomorphs on the Caribbean islands resulted from intra-archipelago diversification through time, but their high-level phylogenetic diversity can only be explained by distinct sources, implying de facto multiple (potentially time-staggered) natural colonizations of the West Indies. The chinchilloid-compatible enamel and dental pattern characterizing Borikenomys from lower Oligocene deposits in Puerto Rico strongly suggest a link with some of the recently-extinct “heptaxodontids”, which would substantiate their much greater antiquity in the Caribbean islands.

The effect of calcium phosphate ion clusters in enhancing enamel conditions versus Duraphat and Icon.

This study aimed to evaluate and compare the remineralisation, mechanical, anti-aging, acid resistance and antibacterial properties of calcium phosphate ion clusters (CPICs) materials with those of Duraphat and Icon. The remineralisation and mechanical properties were investigated using scanning electron microscopy, Fourier-transform infrared (FTIR) spectroscopy and nanoindentation. CPICs induced epitaxial crystal growth on the enamel surface, where the regrown enamel-like apatite layers had a similar hardness and elastic modulus to natural enamel (p> 0.05). Acid resistance and anti-aging properties were tested based on ion dissolution and surface roughness. CPICs exhibited similar calcium and phosphate ion dissolution to the control (p> 0.05), and its roughness decreased after thermocycling (p< 0.05), thereby decreasing the risk of enamel surface demineralisation. The minimum inhibitory concentration was 0.1mg/ml, and the minimum bactericidal concentration ranged from 0.05 to 0.1mg/ml. Overall, this biomimetic CPICs is a promising alternative to dental demineralisation.

The Use of Laser Energy for Etching Enamel Surfaces in Dentistry-A Scoping Review.

Background: In dental practice, different situations require etching the enamel layer. Acid etching, the present golden standard, may be replaced by other methods, such as laser etching. The main focus of our scoping review is to assess the existent literature regarding the effectiveness of different types of lasers, to identify the main aspects studied so far, and to understand where new search strategies are needed. Methods: The search was conducted in several databases focusing on the laser etching of human definitive enamel. We included English language articles published between January 2000 and December 2021. Results: The 34 articles reviewed showed that hard lasers, Er:YAG, Er,Cr:YAG, may represent an alternative etching method on enamel surfaces. They create a fractured, irregular surface and open dentin tubules, highly suitable for adhesion but with a lower risk of cavity formation. Nd:YAG, CO2, and Diode lasers do not help in creating sufficient shear bond strength. There is, however, evidence suggesting that microcracks in the enamel layer may appear after thermomechanical ablation using laser energy. Conclusions: While the use of acid etching is still successfully used for enamel conditioning, some researchers have emphasized the role played by saliva in the enamel-remineralization process a few days after the procedure. In this context, laser energy can be used, especially for bonding ceramic brackets in the case of orthodontic treatments. However, as thermomechanical ablation can generate microcracks, further research is required in order to establish clear findings concerning the use of laser energy on enamel etching.

The effect of multiple enamel conditioning on enamel micro-hardness

White spot formation is one of the common side effects in orthodontic treatments and multiple enamel conditioning might happen even during on session of fixed orthodontic treatments. The aim of the present study was to evaluate the impact of multiple enamel conditioning with different methods on enamel micro-hardness (MH). In this In vitro experimental study, the buccal surfaces of 105 extracted premolars were evaluated in seven groups: One control and six experimental groups. The enamel conditioning was performed in three ways: Etching with phosphoric acid 37%, etching with phosphoric acid 37% followed by primer application and conditioning with self-etch primer. The conditioning process in each way was also performed twice consecutively. The specimens were submitted in pH cycling model with demineralization and re-mineralization solutions for 14 days. Afterward Vickers MH test was applied with 0.981N force on the teeth for 10 s indentation time. Data were analyzed using One-Way ANOVA and Tukey HSD (honestly significant difference) test for multiple comparisons. A value of P < 0.05 was considered statistically significant. MH analysis showed statistically significant differences between the control group and the other conditioned groups (P < 0.05). The groups conditioned with acid-etch and primer, particularly twice, showed the lowest amount of MH in comparison to other groups. Self-etch primer had the least effect on MH of the enamel. Single time etching without using primer, made no considerable difference when compared to multiple etching. Etching process and covering the enamel with primer decrease enamel MH. Using self-etch primer is a more conservative method of enamel conditioning.

Enamel conditioning in orthodontics ‒ A literature review

The strength of the bond between the bracket and the enamel surface depends on three factors, namely, the retention mechanism of the bracket base, the adhesive material or bonding resin, and the preparation of the tooth surface. Commonly used adhesive systems employ an enamel conditioner, a primer solution, and an adhesive resin to bond the orthodontic brackets to the enamel surface. The aim of this study was to compare the effects of different enamel conditioning techniques for bracket bonding.

A comparison of the shear bond strength of orthodontic brackets bonded after enamel conditioning with sodium hypochlorite and papain gel: An in vitro study

A comparison of the shear bond strength of orthodontic brackets bonded after enamel conditioning with sodium hypochlorite and papain gel: An in vitro study

53 - Use of EDTA on Bond of Adhesives to Fluorotic Enamel

To compare the effect of active pre-conditioning with 17% ethylenediaminetetraacetic acid (EDTA) vs. 37% phosphoric acid (PA) on the resin-enamel microshear bond strength (μSBS), enamel-etching pattern, and in-situ degree of conversion (in-situ DC) of four universal adhesive systems on sound enamel and fluorotic enamel. 224 extracted human molars (112 with no fluorosis and 112 with fluorosis) were sectioned into 4 parts and divided into 16 experimental groups based on the enamel surface (sound or fluorotic enamel), adhesive system (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], or Scotchbond Universal [SBU]), and enamel conditioning agent (phosphoric acid [PA] mode or EDTA mode). The specimens were stored for 24 h and tested under shear stress at 1.0 mm/min (μSBS). The adhesive-enamel interfaces were evaluated for in situ DC using micro-Raman spectroscopy. The enamel-etching pattern was evaluated using a scanning electron microscope. The SBS and in situ DC data were analyzed separately using three-way analysis of variance and Tukeys post-hoc test (α = 0.05). Sound enamel showed higher μSBS and DC values as compared to fluorotic enamel (p < 0.05). However, no significant difference was observed for μSBS, DC (p > 0.05), and etching patterns when the PA and EDTA modes were compared in sound and fluorotic enamel. Moreover, CUB and SBU showed higher mean values of μSBS than that of FBU and IBU in both sound and fluorotic enamel (p < 0.05). As compared to PA, active pre-conditioning with EDTA showed similar μSBS values and enamel etching patterns for all the adhesive systems in fluorotic enamel, without compromising the in situ DC.

Effect of Amelogenin Solution in the Microhardness of Remineralized Enamel and Shear Bond Strength of Orthodontic Brackets.

Objectives To evaluate the microhardness of tooth enamel remineralized with enamel matrix protein solution as well as the shear bond strength of orthodontic brackets bonded to this surface. Materials and Methods In total, 24 human premolars were selected and divided into 3 experimental groups (n = 8): SE—sound enamel, DE—demineralized enamel, and TE—demineralized enamel treated with amelogenin solution. Samples from DE and TE groups were subjected to pH cycling to induce initial artificial caries lesion. TE group was treated with amelogenin solution. Samples were placed in artificial saliva for 7 days. Knoop microhardness was measured before any intervention (T0), after pH cycling (T1) and after amelogenin solution treatment application (T2). Twenty-four hours after ceramic orthodontic brackets were bonded, samples were subjected to shear test in a universal testing machine. Microhardness and shear measurement distributions were subjected to Kolmogorov–Smirnov normality test, which was followed by parametric tests (α = 0.05): 2-way analysis of variance (factors: enamel condition × treatment) and Tukey posttest for all three groups (SE, DE, and TE) in T0 and T2 for microhardness; analysis of variance and Tukey's test, for shear bond strength test. Results Means recorded for Knoop microhardness in T2, for the SE (366.7 KHN) and TE (342.8 KHN) groups, were significantly higher than those recorded for the DE group (263.5 KHN). The shear bond strength of the SE (15.44 MPa) and TE (14.84 MPa) groups statistically differed from that of the DE group (11.95 MPa). Conclusion In vitro demineralized enamel treatment with amelogenin solution was capable of taking samples' hardness back to levels similar to those observed for sound enamel. The shear bond strength on the enamel subjected to this treatment was similar to that observed for healthy enamel and higher than that observed for demineralized enamel.