Conventional Acid-etch Technique Research Articles

Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared by Er: Yag Laser and Conventional Acid Etching Technique-An in-Vitro Study

Background: Brackets are one of the important components in orthodontic treatment which helps in transferring forces to the teeth to appreciate teeth movement. So, it is very important to have a better bond strength between brackets and teeth which can be achieved by different materials and techniques. Initially, etching (surface preparation) was done on the surface of the teeth by acid (37% phosphoric acid) to bond brackets directly to the teeth. Later with the introduction of lasers, surface preparation was done using Er: YAG laser which was considered as an alternative and better technique when compared with the conventional acid technique. Objective: To compare the differences in shear bond strength of orthodontic brackets bonded to enamel prepared by Er: Yag laser and conventional acid etching technique. Results: The shear bond strength of the acid group showed the least bond strength. ARI Index shows that group 3 laser etched group had major bond failure at favorable site with most number of score value between score1 to 3. ARI Index of group A & B showed most number of score value between score4 to 5 with major bond failure at unfavorable site. Conclusion: ANOVA and Chi-square test revealed statistically significant difference between 3 different groups on assessing the SBS and ARI Index. Group C (laser etched group at W. 1mJ & 10Hz) showed better bond strength at a clinically acceptable level and also had major bond failure at favorable site which produces least damage to the enamel surface. Group B laser etched group even though had higher bond strength of 15.95 MPa, their value highly deviates from the clinically required level of 8Mpa.

Clinical Effectiveness of Air Abrasion When Compared to Conventional Acid-etching Technique in Enhancing the Retention of Pit and Fissure Sealants: A Systematic Review.

The purpose of our study was to perform a systematic review to assess and compare the effectiveness of the air abrasion technique with that of the conventional acid-etching technique performed before the placement of pit and fissure sealants. A search of studies was conducted in May 2021 using PubMed, Cochrane Library, and Google Scholar databases. Clinical trials in the English language between 1997 and 2019 were included. The quality of the studies was analyzed using the Cochrane Collaboration tool. The search retrieved 276 references, out of which seven studies were included for a qualitative analysis. In these seven studies, the risk of bias across the Cochrane tool's domains varied from low to high. All the included studies considered acid-etching as a comparator to air abrasion technique either used alone or as an adjunct to acid-etching technique. When coverage of sealants or their retentivity was compared at different time intervals, it was more in the acid-etching group than in the air abrasion group. Similarly, carious lesions were seen more in the air abrasion group than in the acid-etching group. The air abrasion technique followed by acid-etching brought superior retention properties of sealants than the acid-etching technique alone. Bhadule SN, Kalaskar R, Kalaskar A, et al. Clinical Effectiveness of Air Abrasion When Compared to Conventional Acid-etching Technique in Enhancing the Retention of Pit and Fissure Sealants: A Systematic Review. Int J Clin Pediatr Dent 2024;17(3):377-384.

Comparative in-vivo bond failure rate of orthodontic brackets when bracket base is treated with micro-abrasive blasting vs. acid etching: eighteen month randomized control trial and scanning electron microscope study.

The aim of this study was threefold. Firstly, it aimed to introduce and detail a novel method for chemically etching the bases of stainless-steel orthodontic brackets. Secondly, the study sought to investigate the structural alterations within the brackets' microstructure following chemical etching compared to those with sandblasted bases, using electron microscopy analysis. Lastly, the study aimed to evaluate and compare the long-term durability and survivability of orthodontic brackets with chemically etched bases versus those with sandblasted bases, both bonded using the conventional acid etch technique with Transbond XT adhesive, over an 18-month follow-up period. The study was a randomized clinical control trial with triple blinding and split-mouth study design and consisted of two groups. The brackets in the sandblasted group were prepared by sandblasting the intaglio surface of the base of the bracket with 50 µm SiO2 particles. Hydrofluoric acid was used to roughen the base in the acid-etched group. The bases of the brackets were viewed under an electron microscope to analyze the topographical changes. A total of 5,803 brackets (3,006 acid-etch, 2,797 sandblasted) in 310 patients were bonded, in a split-mouth design by the same operator. The patients were followed for 18 months. The failure rate of 2.59% and 2.7% was noted in an acid-etched and sandblasted group, respectively. There was a close approximation of curves in the Kaplan-Meier plot, and the survival distribution of the two groups in the log-rank (Mantel-Cox) test was insignificant; x2 = 0.062 (P value = 0.804). Acid etching if the bases of the brackets can be used as an alternative to sandblasting furthermore acid etching can be performed on the chair side.

Retention in fissure resin-based sealants in schoolchildren: the etching step importance.

Randomized controlled trial. Forty-seven schoolchildren aged 9-10 years with fully sound/noncavitated erupted first permanent molars were included and randomly allocated in control and experimental groups in a split-mouth design. 47 schoolchildren (94 molars) fissure sealants applied using self-etch universal adhesive system. 47 schoolchildren (94 molars) fissure sealants applied using conventional acid-etching technique. Retention of sealants and secondary caries incidence (ICDAS). Chi-square test. Conventional acid-etch sealants retention was superior to self-etch after 6 and 24 months (p < 0.001), but no differences were found in caries incidence after 6 and 24 months (p > 0.05). Clinical retention of fissure sealants using conventional acid-etch technique is greater than self-etch.

Comparative Evaluation of Penetrative and Adaptive Properties of Unfilled and Filled Resin-Based Sealants When Placed using Conventional acid Etching, Lasing, and Fissurotomy Bur Technique of Enamel Preparation: An in vitro Scanning Electron Microscope Study.

There is a confusion regarding selection of unfilled or filled sealant and method of enamel preparation before sealant application. This study was carried out to compare three techniques of enamel preparation using both unfilled and filled type of sealants. The objective of the study is to assess the penetrative and adaptive ability of filled and unfilled sealants in three techniques of enamel fissure preparations. Total 36 extracted teeth were divided into 3 groups, each containing 12 samples. The samples of Group A were prepared by conventional acid etching with 37% phosphoric acid, and the Group B was subjected to Er: YAG lasing, while in Group C, fissurotomy followed by acid etching was done. The sealant placement was carried out using split tooth design in all the samples. Assessment of penetration and adaptation was done under scanning electron microscope using the scoring criteria adopted by Kane B et al. and Dukic W et al. Group A and Group C showed better adaptation than Group B. Statistically, no significant difference was observed in the penetration property among three techniques. Similarly, the unfilled and filled sealant showed statistically nonsignificant results for the penetration and adaptation comparison. Irrespective of the sealant material selected, the conventional method of acid etching alone or in conjunction with fissurotomy bur for better retentiveness seems to be an acceptable choice of treatment modality. The study will help the clinicians to choose the sealant material and technique of enamel preparation.

Comparison of self-etch primers with conventional acid-etch technique for bonding brackets in orthodontics: a systematic review and meta-analysis.

Bonding with self-etch primers (SEPs) is one of the most popular systems for attaching orthodontic brackets to the enamel surface. There are conflicting reports about the efficacy and success of these systems compared with acid-etch (AE) bonding. This systematic review and meta-analysis was performed to compare SEP with conventional AE technique for bonding brackets in fixed orthodontics. Articles related to the subject of interest were searched in electronic databases, including PubMed, ISI Web of Science, Scopus, EMBASE, and Cochrane's CENTRAL, from inception to 2 June 2021. Search for grey literature, and hand search for relevant studies were also performed. Based on the PICO model, randomized clinical trials using full-arch bonded fixed orthodontic appliances comparing SEP and conventional AE systems were included in the review process. After assessing the risk of bias, data from the included studies were extracted using custom piloted forms. Inverse-variance random-effects meta-analyses were performed to combine the results of bracket failure, adhesive remnant index (ARI), and bonding time. Nineteen randomized clinical trials were included in the systematic review and 17 randomized clinical trials [5 parallel-group (PG) and 12 split-mouth (SM) studies] were included in the meta-analysis. No significant difference in bracket failure at 6 months [risk ratio (RR) = 1.50, P = 0.26, 12 SM] and (RR = 0.68, P = 0.34, 2 PG), 12 months (RR = 1.6, 8 SM) and (RR = 1.17, P = 0.54, 2 PG), and ≥18 months (RR = 0.84, P = 0.31, 3 SM) and (RR = 1.20, P = 0.3, 3 PG) between SEP and AE groups could be found. Also, ARI score was similar between different bonding systems [mean difference (MD) = -0.44, P = 0.06, 4 SM]. The bonding time per tooth was faster in the SEP group (MD = -26.55, P &lt; 0.001, 2 SM) and (MD = -24.00, P &lt; 0.001, 2 PG). inclusion of three studies with a high risk of bias and high amount of inconsistency between the results of individual studies were the biggest limitations of our review. The bracket bonding failure and ARI score were not significantly different between self-etch and conventional AE bonding systems. The bonding time was lower for the SEP, but some other requirements for SEPs like pumice prophylaxis could diminish this advantage. The protocol for this systematic review was registered at PROSPERO with the ID CRD42021248540.

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.

Comparative Evaluation of Shear Bond Strength of Brackets Bonded with self Etch Primer/Adhesive and Conventional Etch/Primer and Adhesive System.

Introduction:The shear bond strength obtained with an acid primer might not be clinically reliable. The present study evaluated the use of a new self-etch primer as compared with the conventional bonding procedure. The findings indicated that the use of a self-etch primer to bond orthodontic brackets to the namel surface provided lower, but clinically accept-able, shear bond forces (mean, 7.1 ± 4.4 MPa). Hence, this study has been designed to evaluate the shear bond strength of orthodontic brackets bonded with a self-etching primer system, and compare it with the conventional acid etching priming system.Materials and Methods:This study was designed to compare the shear bond strength of orthodontic brackets bonded with conventional acid etching- priming and a self-etching primer. For this purpose, one hundred and twenty noncarious, not subjected to any pretreatment chemical agents (e.g. hydrogen peroxide), no cracks caused by the presence of the extraction forceps, no caries and unrestored human maxillary 1st and 2nd premolars, freshly extracted for orthodontic treatment were collected and stored in distilled water before bonding. Separate molds of cold-cure acrylic were prepared and the extracted premolar teeth were embedded in the cold cure acrylic up to the cement enamel junction.Results:For the control group, the mean shear bond strength was 9.38 ± 6.02 MPa and for the experimental group, it is 6.91 ± 3.58 MPa. Group comparison using Chi-square test for the self-etching primer group adhesive remnant index (ARI) scores shows that more than half of the adhesive left over the tooth surface (score 3 and 4). For the conventional group, ARI scores show that there was no or slight amount of adhesive left over the tooth surface (score 5). The proportion of ARI score is significantly (P < 0.001) more in conventional (68.33%) as compared to self-etch primer (SEP) (28.33%). The proportion of ARI scores 4 and less is significantly more in SEP (71.67%) as compared to Conventional (6.67%) with P = 0.004 as per the Chi-square test.Conclusion:The bond strength of SEP is comparatively lesser than the conventional acid etching technique, but is definitely more or less to the required bond strength to resist masticatory forces. Majority of the studies conducted on self-etching primer are in vitro studies. Results of these cannot be extrapolated to the intraoral environment. Hence, further long-term clinical studies need to be carried out before actually recommending the use of self-etching primer in routine orthodontic bonding.

Evaluation of a newly developed calcium fluoride nanoparticles-containing orthodontic primer: An in-vitro study

ObjectivesFluoride and calcium ions have the ability to reduce the formation of white spot lesions (WSL) in enamel. This study aimed to develop a novel orthodontic primer that incorporates calcium fluoride nanoparticles (nCaF2) and investigate its cytotoxic and physical properties as this primer could enhance the remineralization process when used with the conventional acid etching technique. Materials and methodsThree groups of the newly introduced primers were prepared by adding and mixing nCaF2 (Nanoshell Company, USA at 5%, 10%, 20% in weight) to Transbond™ XT orthodontic primers (3M-Unitek, Monrovia, USA). X-Ray Diffraction (XRD) was performed to verify and evaluate the phase of the nanopowders. Field Emission Scanning Electron Microscope (FESEM) observation was used to assess the homogeneity of tested primers, and Energy Dispersive X-Ray Spectroscopy (EDS) was performed to analyze elements of the prepared samples. The three primer groups were compared to the control primer (without the addition of nCaF2) in terms of cytotoxic behavior, homogeneity, agglomeration, shear bond strength (SBS), and adhesive remnant index (ARI). ResultsnCaF2 primers with all the prepared concentrations revealed good homogeneity with no apparent agglomeration after four months of mixing. Cytotoxicity of the new primers was higher than that of the control primer, but it was within the accepted limits of the ISO standards (70% cell viability). While the SBS and ARI values were comparable with the control primer (p > 0.05). ConclusionsThe newly developed orthodontic primers with different concentrations of nCaF2 (5%, 10%, and 20%) showed a homogenous distribution of nCaF2 within the primers with no apparent agglomeration, acceptable cytotoxic level, adequate SBS, and ARI. Future clinical testing of nCaF2-containing orthodontic primer as a preventive measure for WSLs during fixed orthodontic treatment is suggested.

Effects of different types of laser etching versus phosphoric acid etching on shear bond strength of metal brackets to human enamel: A systematic review and meta-analysis of in vitro studies

This study aimed to assess the effect of different types of laser etching versus phosphoric acid etching on shear bond strength (SBS) of metal brackets to human enamel. In this systematic review and meta-analysis, relevant articles published until the end of October 2019 were retrieved from PubMed, ISI Web of Science, Scopus, Embase, and Cochrane Library. The inclusion criteria were in vitro studies on the effect of laser on SBS of metal brackets to the enamel in comparison with acid-etching, and studies published in English to the end of October 2019. After assessing the eligibility criteria and quality, a total of 18 studies were statistically analysed using STATA software. The SBS of 554 human tooth specimens in the test group (subjected to irradiation of different laser types) was compared with the SBS of 313 tooth specimens in the control group (etched with phosphoric acid). The meta-analysis showed that laser etching decreased the SBS of brackets by 1.39MPa, compared with phosphoric acid etching, and this reduction was statistically significant (P<0.05). The Er:YAG group, however, showed 0.6MPa higher SBS than phosphoric acid etching group, but this increase was not statistically significant. Laser etching yields lower SBS than acid etching; even though different laser types have different effects on SBS. Thus, the conventional acid-etching technique is still recommended for enamel etching prior to the bonding of orthodontic metal brackets.

Shear Bond Strength of Brackets Bonded with Self-Etching Primers Compared to Conventional Acid-Etch Technique: A Randomized Clinical Trial

Objectives: The purpose of this randomized clinical trial (RCT) was to compare the shear bond strength (SBS) of orthodontic brackets bonded to enamel with conventional acid-etch (AE) technique and self-etching primers (SEP).&#x0D; Materials and Methods: Twenty-two patients, requiring extraction of two bicuspids for orthodontic reasons, were recruited. In each individual, following blinding and allocation concealment, one intact premolar received conventional AE, whereas the contralateral premolar received SEP with a split-mouth design. Bonded brackets remained in the oral cavity for two months. Afterward, the teeth were extracted without debonding the brackets. SBS and adhesive remnant index (ARI) were measured using a Universal Instron machine and a stereomicroscope, respectively.&#x0D; Results: The mean SBS of the conventional AE and SEP groups was 9.53 and 9.20 MPa, respectively. Paired t-test showed no statistically significant difference between the two groups (P=0.096). Comparison of ARI between the two groups, using Wilcoxon test, indicated that significantly less adhesive remained on enamel with brackets bonded with SEP compared to brackets bonded with conventional AE (P&lt;0.001) although the SBS was higher in the AE group.&#x0D; Conclusion: The present study indicated that although there is no significant difference in SBS between SEP and conventional AE for bonding orthodontic metal brackets, the amount of residual adhesive on the enamel surface is significantly less with SEP than with conventional AE.&#x0D; (IRCT registration number: IRCT201705099086N3).

The effect of cigarette smoke on the shear bond strength of metallic and ceramic orthodontic brackets: An in vitro study

The bond strength between enamel and the bracket base is influenced by exposure to the oral environment. The aim of the current study was to determine the effect of cigarette smoke on the shear bond strength (SBS) of bonded metallic and ceramic orthodontic brackets. a sample of 60 sound extracted premolars were divided into four groups (n=15 each) as follows: group (A): ceramic brackets without smoke exposure, (B): metallic brackets without smoke exposure, (C): ceramic brackets with smoke exposure, (D): metallic brackets with smoke exposure. Smoking exposure was simulated using the British American Tobacco's exposure chamber manufactured by Curbridge Engineering (Hampshire, UK). Metallic and ceramic brackets were bonded to the enamel using conventional acid etching technique. SBS (MPa) was tested using the universal Instron testing machine at a constant cross head speed of 1mm/min until failure. Kolmogorov-Smirnov test was used to test the normality of the measurements. One-way analysis of variance (ANOVA) was used to compare the means of SBSs between the four groups, Post-hoc with least significance difference was used to perform a pairwise comparison between means. Statistical significance was set at P<0.05. The highest SBS corresponded to the ceramic type brackets bonded to a non-smoking sample (15.7±9.5) while the lowest levels of SBS was related to metallic type brackets bonded to smoke exposed sample (2.8±0.7) and the difference was statistically significant (P<0.05). Cigarette smoke consumption has significant effects on the SBS of orthodontic brackets. SBS levels were significantly lower in the smoke exposure groups and the lowest values corresponded to the cigarette smoke exposed metallic brackets.

Potential of high-intensity focused ultrasound in resin-dentine bonding

ObjectiveThis study introduced the potential and proof-of-concept of high intensity focused ultrasound (HIFU) technology for dentin-surface treatment for resin-dentin bonding without acid-aided demineralization. This new strategy could provide a way to enhance interface-integrity and bond-durability by changing the nature of dentin-substrate; bonded-interface structure and properties; and minimizing denuded-collagen exposure. MethodsThe interaction between HIFU waves and dentin-surface in terms of structural, mechanical and chemical variations were investigated by SEM, TEM, AFM, nano-indentation and Raman-analysis. The bonding between HIFU-treated dentin and two-step, etch-and-rinse, adhesive was preliminary explored by characterizing dentin-bound proteases activities, resin-dentin interfacial morphology and bond-durability with HIFU exposure at different time-points of 60, 90 and 120 s compared to conventional acid-etching technique. ResultsWith the increase in HIFU exposure-time from 60-to-120 s, HIFU waves were able to remove the smear-layer, expose dentinal-tubules and creating textured/rough dentin surface. In addition, dentin surfaces showed a pattern of interlocking ribbon-like minerals-coated collagen-fibrils protruding from the underlaying amorphous dentin-background with HIFU exposure for 90 s and 120 s. This characteristic pattern of dentin-surface showing inorganic-minerals associated/aligned with collagen-fibrils, with 90-to-120 s HIFU-treatment, was confirmed by the Raman-analysis. HIFU-treated specimens showed higher nano-indentation properties and lower concentrations of active MMP-2 and Cathepsin-K compared to the acid-etched specimens. The resin-dentin bonded interface revealed the partial/complete absence of the characteristic hybrid-layer formed with conventional etch-and-rinse bonding strategy. Additionally, resin-infiltration and resin-tags formation were enhanced with the increase in HIFU exposure-time to 120 s. Although, all groups showed significant decrease in bond-strength after 12 months compared to 24 h storage in artificial saliva, groups exposed to HIFU for 90 s and 120 s showed significantly higher μTBS compared to the control acid-etched group. SignificanceThe implementation of HIFU-technology for dental hard-tissues treatment could be of potential significance in adhesive/restorative dentistry owing to its ability of controlled, selective and localised combined tissue alteration/ablation effects.

Shear Bond Strength of Brackets Bonded with Self-Etching Primers Compared to Conventional Acid-Etch Technique: A Randomized Clinical Trial.

Objectives:The purpose of this randomized clinical trial (RCT) was to compare the shear bond strength (SBS) of orthodontic brackets bonded to enamel with conventional acid-etch (AE) technique and self-etching primers (SEP).Materials and Methods:Twenty-two patients, requiring extraction of two bicuspids for orthodontic reasons, were recruited. In each individual, following blinding and allocation concealment, one intact premolar received conventional AE, whereas the contralateral premolar received SEP with a split-mouth design. Bonded brackets remained in the oral cavity for two months. Afterward, the teeth were extracted without debonding the brackets. SBS and adhesive remnant index (ARI) were measured using a Universal Instron machine and a stereomicroscope, respectively.Results:The mean SBS of the conventional AE and SEP groups was 9.53 and 9.20 MPa, respectively. Paired t-test showed no statistically significant difference between the two groups (P=0.096). Comparison of ARI between the two groups, using Wilcoxon test, indicated that significantly less adhesive remained on enamel with brackets bonded with SEP compared to brackets bonded with conventional AE (P<0.001) although the SBS was higher in the AE group.Conclusion:The present study indicated that although there is no significant difference in SBS between SEP and conventional AE for bonding orthodontic metal brackets, the amount of residual adhesive on the enamel surface is significantly less with SEP than with conventional AE.(IRCT registration number: IRCT201705099086N3).

Is laser conditioning a valid alternative to conventional etching for aesthetic brackets?

ER:Yag lasers have been described as a more conservative alternative to conventional acid-etching enamel conditioning technique, when bonding conventional metallic orthodontic brackets. Since the use of aesthetic orthodontic brackets is constantly increasing, the purpose of the present report has been to test laser conditioning with different aesthetic brackets. Study Design: Five different aesthetic brackets (microfilled copolymer, glass fiber, sapphire, polyoxymethylene and sintered ceramic) were tested for shear bond strength and Adhesive Remnant Index scores using two different enamel conditioning techniques (acid etching and ER:Yag laser application). Two hundred bovine incisors were extracted, cleaned and embedded in resin. Specimens were then divided into 10 groups with random tables. Half of the specimens were conditioned with conventional orthophosphoric acid gel, the other half with ER:Yag laser. Different aesthetic brackets (microfilled copolymer, glass fiber, sapphire, polyoxymethylene and sintered ceramic) were then bonded to the teeth. Subsequently all groups were tested in shear mode with a Universal Testing Machine. Shear bond strength values and adhesive remnant index scores were recorded. Statistical analysis was performed. When considering conventional acid etching technique, sapphire, polyoxymethylene and sintered ceramic brackets exhibited the highest SBS values. Lowest values were reported for microfilled copolymer and glass fiber appliances. A significant decrease in SBS values after laser conditioning was reported for sapphire, polyoxymethylene and sintered ceramic brackets, whereas no significant difference was reported for microfilled copolymer and glass fiber brackets. Significant differences in ARI scores were also reported. Laser etching can significantly reduce bonding efficacy of sapphire, polyoxymethylene and sintered ceramic brackets.

Microtensile bond strength of a resin-based fissure sealant to Er,Cr:YSGG laser-etched primary enamel

The aim of this study was to evaluate the effect of Er,Cr:YSGG laser pre-treatment alone, or associated with acid-etching, on the microtensile bond strength of a resin-based fissure sealant to primary enamel. Twenty-five human primary molars were randomly divided into five groups including (1) 35 % acid etching, (2) 2.5-W laser etching, (3) 3.5-W laser etching, (4) 2.5-W laser etching + acid etching, and (5) 3.5-W laser etching + acid etching. Er,Cr:YSGG laser was used at a wavelength of 2.780 nm and pulse duration of 140-200 μs with a repetition rate of 20 Hz. Following surface pre-treatment, the fissure sealant (ClinPro™, 3M Dental Products) was applied. Each tooth was sectioned and subjected to microtensile testing. Kruskal-Wallis test was used for statistical analysis. The level of significance was set at p < 0.05. The microtensile bond strength values of group 1 were significantly higher than those of group 2, while no statistically significant difference was detected between groups 1, 3, 4, and 5. It was concluded that 3.5-W laser etching produced results comparable to conventional acid etching technique, whereas 2.5-W laser etching was not able to yield adequate bonding performance.

Factors Affecting the Shear Bond Strength of Orthodontic Brackets - a Review of In Vitro Studies.

The adhesive material used to bond orthodontic brackets to teeth should neither fail during the treatment period, resulting in treatment delays, untoward expenses or patient inconvenience nor should it damage the enamel on debonding at the end of the treatment. Although the effectiveness of a bonding system and any unfavorable effects on the enamel may be studied by conducting in-vivo studies, it is nearly impossible to independently analyze different variables that influence a specific bonding system in the oral environment. In-vitro studies, on the other hand, may utilize more standardized protocols for testing different bonding systems and materials available. Thus, the present review focused attention on in-vitro studies and made an attempt to discuss material-related, teeth-related (fluorotic vs non-fluorotic teeth) and other miscellaneous factors that influences the shear bond strength of orthodontic brackets. Within the limitations of this review, using conventional acid-etch technique, ceramic brackets and bonding to non-fluorotic teeth was reported to have a positive influence on the shear bond strength of orthodontic brackets, but higher shear bond strength found on using ceramic brackets can be dangerous for the enamel.

A Comparison of Shear Bond Strengths of Metal and Ceramic Brackets using Conventional Acid Etching Technique and Er:YAG Laser Etching.

Background and aims. The aim of this study was to compare shear bond strength (SBS) of metal and ceramic brackets bonded to enamel using acid versus Er:YAG laser etching. Materials and methods. Eighty premolars were divided into 4 groups: AM (acid etching/ metal brackets), AC (acid etching/ ceramic brackets), LM (laser etching/ metal brackets) and LC (laser etching/ ceramic brackets). Enamel condition-ing was done using acid in AC and AM and Er:YAG laser in LC and LM. Brackets were debonded with a Dartec machine and the SBSs were determined. Adhesive remnant index was evaluated under a stereomicroscope. Two additional teeth were conditioned with acid and laser for scanning electron microscopy examination. Comparisons of SBS value were done by ANOVA test. Results. statistical analyses showed that SBSs of acid groups were significantly higher than that of laser groups, but dif-ferences between SBS values of AC/ AM and LC/LM were not significant. SEM examination revealed different etching pattern. Conclusion. Low power Er:YAG laser etching offers clinically acceptable SBS which besides its other superiorities to acid etching can be an appropriate alternative for bonding of ceramic brackets.

Femtosecond laser etching of dental enamel for bracket bonding

The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.

Comparison of the Shear Bond Strength of Orthodontic Brackets in Bonding and Rebonding: Preparation with Laser Versus Conventional Acid Etch Technique

The purpose of this study was to compare the bond strength of orthodontic brackets using laser versus acid etching. Debonding of brackets is a common problem in orthodontic treatments. Eighty extracted premolar teeth were divided into two groups. The enamel of the teeth in group A and B were etched using CO2 laser and phosphoric acid, respectively. The brackets were bonded to the teeth using Transbond XT and then debonded from the teeth by Instron machine. The remaining composite on the tooth surface was removed by a tungsten carbide polishing bur. Both groups were divided into two subgroups (A1, A2 and B1, B2). The teeth were prepared again with laser in A1, B1 subgroups and with acid in A2, B2 subgroups. At each stage, the shear bond strength and residual adhesive index were measured. One way ANOVA and χ(2) tests were used to analyze data. The mean shear bond strength was significantly lower in group A and higher in group B compared with all other groups (p < 0.05). Most of the bond failures were degree 0 and 1 in groups A, A1, and B1, and degree 2 and 3 in groups B, A2, and B2. Primary preparation with acid has a higher bond strength value than does CO2 laser. Less adhesive residue remained on enamel after tooth preparation with laser following debonding. Secondary preparation of the enamel using laser has higher bond strength value than does primary preparation with laser, which can rationalize use of laser in rebonding of brackets.