Effects of Novel versus Conventional Porcelain Surface Treatments on Shear Bond Strength of Orthodontic Brackets: A Systematic Review and Meta-Analysis

Background. Despite the importance of identifying proper novel porcelain preparation techniques to improve bonding of orthodontic brackets to porcelain surfaces, and despite the highly controversial results on this subject, no systematic review or meta-analysis exists in this regard. Objective. To comparatively summarize the effects of all the available porcelain surface treatments on the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets (metal, ceramic, polycarbonate) bonded to feldspathic porcelain restorations. Search Methods. A search was conducted for articles published between January 1990 and February 2021 in PubMed, MeSH, Scopus, Web of Science, Cochrane, Google Scholar, and reference lists. Eligibility Criteria. English-language articles comparing SBS of feldspathic porcelain’s surface preparation methods for metal/ceramic/polycarbonate orthodontic brackets were included. Articles comparing silanes/bonding agents/primers without assessing roughening techniques were excluded. Data Analysis. Studies were summarized and risk of bias assessed. Each treatment’s SBS was compared with the 6 and 10 MPa recommended thresholds. Studies including comparator (HF [hydrofluoric acid] + silane + bonding) were candidates for meta-analysis. ARI scores were dichotomized. Fixed- and random-effects models were used and forest plots drawn. Egger regressions and/or funnel plots were used to assess publication biases. Results. Thirty-two studies were included (140 groups of SBS, 82 groups of ARI). Bond strengths of 21 studies were meta-analyzed (64 comparisons in 14 meta-analyses). ARIs of 12 articles were meta-analyzed (28 comparisons in 8 meta-analyses). Certain protocols provided bond strengths poorer than HF + silane + bonding: “abrasion + bonding, diamond bur + bonding, HF + bonding, Nd:YAG laser (1 W) + silane + bonding, CO2 laser (2 W/2 Hz) + silane + bonding, and phosphoric acid + silane + bonding.” Abrasion + HF + silane + bonding might act almost better than HF + silane + bonding. Abrasion + silane + bonding yields controversial results, being slightly (marginally significantly) better than HF + silane + bonding. Some protocols had controversial results with their overall effects being close to HF + silane + bonding: “Cojet + silane + bonding, diamond bur + silane + bonding, Er:YAG laser (1.6 W/20 Hz) + silane + bonding.” Few methods provided bond strengths similar to HF + silane + bonding without much controversy: “Nd:YAG laser (2 W) + silane + bonding” and “phosphoric acid + silane + bonding” (in ceramic brackets). ARIs were either similar to HF + silane + bonding or relatively skewed towards the “no resin on porcelain” end. The risk of bias was rather low. Limitations. All the found studies were in vitro and thus not easily translatable to clinical conditions. Many metasamples were small. Conclusions. The preparation methods HF + silane + bonding, abrasion + HF + silane + bonding, Nd:YAG (2 W) + silane + bonding, and phosphoric acid + silane + bonding (in ceramic brackets) might provide stronger bonds.

Efektivitas antibakteri gel chitosan dengan berat molekul berbeda terhadap jumlah koloni bakteri Streptococcus mutans pada permukaan email sekitar braket ortodonti Antibacterial effectiveness of chitosan gel with different molecular weights on the number of Streptococcus mutans colonies in the enamel surface around orthodontic bracket

Pendahuluan: Chitosan merupakan bahan alami, bersifat antibakteri, dan dapat dibentuk menjadi gel sehingga berpotensi sebagai agen profilaksis terhadap Streptococcus mutans, penyebab demineralisasi email. Lesi white spot merupakan salah satu risiko penggunaan alat ortodonti cekat. Berat molekul merupakan salah satu faktor yang memengaruhi efektivitas antibakteri chitosan, namun hubungannya masih memberikan hasil yang inkonsisten. Penelitian ini bertujuan menganalisis perbedaan efektivitas gel chitosan dengan berat molekul berbeda terhadap jumlah koloni bakteri Streptococcus mutans pada permukaan email sekitar braket ortodonti. Metode: Penelitian ini menggunakan metode eksperimen laboratoy dengan menggunakan 24 sampel gigi dengan braket dioles gel chitosan A (50-80 kDa), gel chitosan B (50-150 kDa), gel chitosan C (190-310 kDa), dan gel kontrol klorheksidin diglukonat 0,2% (CHX) masing-masing 6 sampel. Seluruh sampel diinkubasi dalam biakan Streptococcus mutans secara bertahap, 10 μl suspensi dari plak yang terbentuk pada sampel dibiakkan untuk memperoleh koloni pada biakan agar. Data dianalisis dengan uji one-way ANOVA dan Least Significant Difference (LSD). Hasil: Jumlah koloni bakteri Streptococcus mutans setelah aplikasi gel chitosan A, B, C, dan gel klorheksidin diglukonat 0,2% (CHX) didapatkan sebesar 10,05x106 CFU/ml; 9,72x106 CFU/ml; 10,96x106 CFU/ml; dan 4,35x106 CFU/ml sehingga tidak terdapat perbedaan bermakna jumlah koloni bakteri Streptococcus mutans antara ketiga kelompok gel chitosan (p>0,05) dan terdapat perbedaan jumlah koloni bakteri Streptococcus mutans yang bermakna antara ketiga gel chitosan dengan gel kontrol (p<0,05). Simpulan: Efektivitas antibakteri gel chitosan dengan berat molekul berbeda terhadap jumlah koloni bakteri Streptococcus mutans pada permukaan email sekitar braket ortodonti adalah sama besar, namun lebih rendah daripada efektivitas antibakteri gel klorheksidin diglukonat 0,2% pada studi ini.Kata kunci: berat molekul; braket ortodontik; kitosan; email; Streptococcus mutans ABSTRACTIntroduction: Chitosan is a natural ingredient, antibacterial, and can be formed into a gel so that it has the potential as a prophylactic agent against Streptococcus mutans, the cause of enamel demineralization. White spot lesions are one of the risks of using fixed orthodontic appliances. Molecular weight is one factor that affects the antibacterial effectiveness of chitosan, but the relationship still gives inconsistent results. This study aimed to analyze the differences in the effectiveness of chitosan gels with different molecular weights on the number of Streptococcus mutans bacteria colonies on the enamel surface around orthodontic brackets. Methods: This study used an experimental laboratory method using 24 dental samples with brackets smeared with chitosan A gel (50-80 kDa), chitosan B gel (50-150 kDa), chitosan C gel (190-310 kDa), and chlorhexidine control gel. digluconate 0.2% (CHX) each of 6 samples. All samples were incubated in Streptococcus mutans culture in stages, 10 l suspension of the plaque formed on the samples was cultured to obtain colonies on agar cultures. Data were analyzed by one-way ANOVA and Least Significant Difference (LSD). Results: The number of Streptococcus mutans colonies after application of chitosan gel A, B, C, and 0.2% chlorhexidine digluconate (CHX) gel was 10.05x106 CFU/ml; 9.72x106 CFU/ml; 10.96x106 CFU/ml; and 4.35x106 CFU/ml, so that there was no significant difference in the number of Streptococcus mutans colonies between the three chitosan gel groups (p>0.05) and there was a significant difference in the number of Streptococcus mutans bacteria colonies between the three chitosan gels and the control gel (p<0.05). Conclusions: The antibacterial effectiveness of chitosan gel with different molecular weights on the number of Streptococcus mutans bacterial colonies on the enamel surface around orthodontic brackets was simi-lar but lower than the antibacterial effectiveness of 0.2% chlorhexidine digluconate gel.Keywords: molecular weight; orthodontic bracket; chitosan; enamel; Streptococcus mutans

Effect of Curing Time on the Bond Strength of Orthodontic Brackets Bonded by Light Cure Resin-Modified Glass Ionomer Cement: An In vitro Evaluation

This study was designed with the aim to evaluate the effect of curing time on the shear-bond strength of orthodontic brackets bonded using light cure Resin-Modified Glass Ionomer Cements (RMGIC). This class of cement when used for luting orthodontic brackets offers certain advantages when compared to the more commonly used resin cements. Intact natural teeth (premolars) extracted for therapeutic purposes as part of orthodontic treatment was sourced for use in this study. The teeth were equally divided into four groups four testing, Group 1 - brackets bonded with RMGIC and cured for 3 seconds, Group 2 - brackets bonded RMGIC and cured for 6 seconds, Group 3 - brackets bonded with RMGIC and cured for 9 seconds and Control group - brackets bonded with composite and cured for 15 seconds. A high intensity LED light source was used to cure the cements. The Shear-Bond strength of the brackets was evaluated using a universal testing machine. One-way ANOVA test and Tukey multiple comparison tests were done to compare the difference of Shear-Bond Strengths among the groups tested. The average Shear Bond Strength among study groups was 7.64±2.86 MPa. The ANOVA and Tukey multiple comparison tests could not identify a statistically significant difference in Shear-Bond Strengths among the groups. Curing time does not appear to have a statistically significant effect on the Shear Bond Strength of orthodontic brackets bonded using Resin-Modified Glass Ionomer Cements..

Effects of diamond-like carbon coating on frictional and mechanical properties of orthodontic brackets: An in vitro study

Objectives: The aim of this study is to apply a diamond-like carbon (DLC) coating on orthodontic brackets and to examine the effects of the coating on surface properties and friction. Materials and Methods: 0.022-inch upper right canine brackets, 0.018-inch stainless steel wires, and 0.019 × 0.025-inch stainless steel wires were used in the study. Half of the brackets were treated with physical vapor deposition technique and coated with DLC. Different binary groups constituted of coated and uncoated brackets and wires were subjected to friction experiments using the Instron universal testing machine (Instron, Norwood, MA, USA). The surface properties of the coatings were evaluated using Raman, Scanning Electron Microscopy, and non-contact optical profilometer. Results: The friction force values between the DLC-coated brackets and the stainless-steel wires in both dimensions were found to be statistically significantly lower than the friction force between the uncoated brackets and the wires (P < 0.001). The surface roughness value, especially around the slot groove decreased significantly in the coated brackets (P < 0.05). DLC coating layer thickness is approximately 1.0 μm (806 nanometers). Conclusion: DLC coating improves the surface properties of orthodontic brackets, and DLC coating process remarkably reduced the friction force.

The Impact of Different Types of Orthodontic Appliances and Its Location in Producing CT Scan Artefacts

Fixed orthodontic appliances can produce metal artefacts in CT images which may degrade the diagnostic image quality. The study aimed to evaluate the artefacts based on the types and location of the metallic and non-metallic orthodontic brackets. This is an in-vitro cross-sectional study. Four different types of orthodontic brackets (stainless steel, titanium, monocrystalline, and polycrystalline ceramic bracket) were bonded consecutively in four different locations of the cadaveric skull. All scans were performed by a single operator using the same CT machine followed by a standard scanning protocol. Artefact intensity for all data sets was quantified by calculating the standard deviation (SD) of the grey values within the dataset by following a standard method. The One-way ANOVA Bonferroni test was used for the data analysis. The mean artefact score of the stainless steel bracket was significantly (p < 0.001) high in comparison with other types of the orthodontic brackets. Besides, the mean artefact score was significantly (p=0.002) low when orthodontic brackets were placed unilaterally. Stainless steel brackets produced a significant amount of noise in CT images which can degrade the diagnostic image quality. Thus, the polycrystalline ceramic bracket can be a better alternative of stainless steel brackets for patient need frequent CT scan.

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.