Effect of intraoral aging on the setting status of resin composite and glass ionomer orthodontic adhesives

Degree of cure of orthodontic composite attachments underneath aligners

The aim of this study was to assess the percentage degree of cure (DC%) of 2-mm-thick resin composite attachments used for aligner treatment. Three types of aligner - two thermoformed aligners (Clear Aligner [CLA], polyethylene terephthalate glycol modified; and Invisalign [INV], polyester urethane) and a three-dimensional-printed aligner (Graphy TC-85DAC [GRP], an acrylate-methacrylate copolymer) - were selected, along with two universal resin composites (3M Filtek Universal [FTU] and Charisma Topaz ONE [CTO]). Samples of each composite were placed under each aligner, and the degree of cure of each composite was evaluated on the top (facing the aligner) and the bottom (facing the substrate) attachment surfaces after curing. Five specimens were used per combination of aligner and composite, and an additional group of composites irradiated without aligners served as the control. The DC% measurements were performed using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The DC% across the aligners were (median values) 33.8%-44.8% for CLA, 33.6%-40.8% for INV, 32.8%-40.6% for GRP, and 40.0%-51.7% for the control group. The DC% values of the attachments cured under any aligner were significantly lower than that of the corresponding control, with the values recorded on the top surfaces being 6% higher than those on the bottom surfaces after adjusting for aligner group and composite type.

Correlation of Shear Bond Strength and Degree of Conversion in Conventional and Self-Adhesive Systems Used in Orthodontic Bonding Procedures

(1) Background: Self-adhesive systems have been proposed for the orthodontic bonding with the intention to reduce the traditional three-component system. (2) Methods: The sample consisted of 32 extracted intact permanent premolars randomly divided into two groups (n = 16). In Group I the metal brackets were bonded with Transbond XT Primer and Transbond XT Paste. In Group II the metal brackets were bonded with GC Ortho connect. The resin was polymerized for 20 s from two directions (mesial and occlusal) using a Bluephase light-curing unit. The shear bond strength (SBS) was measured using a universal testing machine. Immediately after SBS testing, Raman microspectrometry was performed for each sample to calculate the degree of conversion (DC). (3) Results: There was no statistically significant difference in the SBS between the two groups. A significantly higher DC (p < 0.001) value was recorded in Group II, in which the brackets were bonded with GC. Very weak or no correlation (0.01) was recorded between SBS and DC in Group I and moderate positive correlation was recorded in Group II (0.33). (4) Conclusions: No difference was found in SBS between the conventional and two-step systems used in orthodontics. The two-step system demonstrated higher DC compared to the conventional system. There is a very weak or moderate correlation between DC and SBS.

EFFICACY OF CURCUMIN-MEDIATED ANTIBACTERIAL PHOTODYNAMIC THERAPY FOR ORAL ANTISEPSIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS OF RANDOMIZED CLINICAL TRIALS

BACKGROUND

currently, the presence of oral microorganisms resistant to traditional treatment is increasing, thus search for new modalities of therapies is needed. In this context, antimicrobial photodynamic therapy (aPDT) is an alternative approach for the treatment of resistant or not resistant microorganisms. Therefore, the aim of the present study was to conduct a systematic review and meta-analysis of randomized clinical trials of aPDT for oral antisepsis against oral polymicrobial biofilms.

METHODS

PubMed, Science Direct, Scopus, SciELO, Lilacs, Cochrane Library and Embase databases were searched. In total, five articles were included for qualitative analysis and four articles were used for quantitative analyses. Bias assessment of the eligible articles was made using the RoB 2 criteria. Network meta-analysis was performed using the random-effect model. Subgroup's analysis was also conducted. The groups evaluated were aPDT, exposure to light only and no treatment at all (control group). The quality of evidence was accessed by CINeMA approach.

RESULTS

aPDT mediated by curcumin had significant results in the reducing bacterial load (0.31-0.49 log₁₀ UFC/ I²=0%) when compared with the control group. The included articles were classified as low risk of bias, despite biases detected by allocation and blinding. Moreover, quantitative analysis between aPDT and control group and between light and control group were classified with low risk of confidence rating, while the results from aPDT versus light were classified as moderate risk of confidence rating.

CONCLUSION

aPDT has significant efficacy for oral antisepsis, however more randomized clinical trials will be needed to validate the present results.

The effect of antimicrobial photodynamic therapy on shear bond strength of orthodontic bracket: An in vitro study

OBJECTIVES

The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy (aPDT) with methylene blue (MB) and indocyanine green (ICG) on bond strength of orthodontic brackets to enamel.

MATERIALS AND METHODS

A total of 45 non-carious and sound human premolar teeth were used in this study. All teeth were examined under a stereomicroscope at ×10 magnification. The samples were divided to 3 groups including no treatment (control group), aPDT with MB and 660 nm diode laser and aPDT with ICG and 808 nm diode laser. After aPDT procedure, orthodontic brackets were bonded to enamel surfaces. Then, the samples were thermocycled for 5000 cycles between 5° and 55° C in water bath. The brackets were then debonded using a universal testing machine. The adhesive remnant index (ARI) score and SEM microscope evaluation were assessed. One-way analysis of variance (ANOVA) with Post-hoc test were used to compare the SBS values among groups.

RESULTS

The highest SBS mean value was presented in group 1 (control) (31.98 ± 6.36). Whereas, the lowest SBS mean value was observed in group 3 (aPDT with ICG) (24.11 ± 5.78). There were significant differences in SBS values between control and aPDT groups (P < 0.05). Some superficial porosity and irregularity was presented following aPDT on surface of enamel when examined by scanning electron microscope. The mode of failure was mostly score 0 and score 1 in all groups.

CONCLUSION

MB and ICG mediated antimicrobial photodynamic therapy both reduced the bond strength of orthodontic brackets compared to control group.

Coronavirus Disease 2019-Challenges Today and Tomorrow in Orthodontic Practice: A Review

From the start of 2020, the world has witnessed the biggest health and humanitarian crisis in the modern century named coronavirus disease 2019. The rapid spread of infection created chaos and confusion across the globe. Like all other health professions, a timely and major reorganization of orthodontic services is challenging. Unlike other medical emergencies, an orthodontic emergency does not require immediate attention in most cases. With advances in the modern web-based communication systems, minor problems can be managed online in orthodontic practice. During an emergency, however, orthodontists have a moral obligation to treat and manage patients under the World Health Organization guidelines and protocol.

Challenges, limitations, and solutions for orthodontists during the coronavirus pandemic: A review

INTRODUCTION

Orthodontic patients worldwide missed appointments during the early months of the coronavirus disease 2019 (COVID-19) pandemic. A significant problem with this virus is its high transmission power. Asymptomatic patients can transmit the virus. The aim of this review is to examine orthodontic emergencies and the necessary strategies and measures for emergency and nonemergency treatment during the coronavirus pandemic.

METHODS

The following databases were comprehensively searched: PubMed, MEDLINE, Scopus, and Google Scholar. Up-to-date data released by major health organizations such as the World Health Organization and major orthodontic associations involved in the pandemic were also evaluated.

RESULTS

Few studies were conducted on managing orthodontic offices or clinics during the pandemic, and most are not of high quality. Appropriate communication is the most important issue in managing orthodontic patients, particularly virtual counseling. Many orthodontic emergencies can be managed in this way by patients themselves. Most studies recommend using the filtering facepiece 2 masks, equivalent to N95 masks for non-COVID-19 patients undergoing aerosol-generating procedures and all suspected or confirmed COVID-19 patients in orthodontic visits.

CONCLUSIONS

At this time, there are no definitive clinical protocols supported by robust evidence for orthodontic practice during the COVID-19 pandemic. Orthodontists should not rush to return to routine orthodontic work and should follow state guidelines. Nonemergency orthodontic visits should be suspended during the severe acute respiratory syndrome coronavirus 2 pandemic in high-risk areas. Resuming orthodontic procedures during the pandemic requires paying special attention to screening, performing maximum efforts to reduce aerosol generation, using appropriate personal protective equipment, having proper ventilation, and fully adhering to sterilization and disinfection principles.

Minimizing the aerosol-generating procedures in orthodontics in the era of a pandemic: Current evidence on the reduction of hazardous effects for the treatment team and patients

The purpose of this critical review is to list the sources of aerosol production during orthodontic standard procedure, analyze the constituent components of aerosol and their dependency on modes of grinding, the presence of water and type of bur, and suggest a method to minimize the quantity and detrimental characteristics of the particles comprising the solid matter of aerosol. Minimization of water-spray syringe utilization for rinsing is suggested on bonding related procedures, while temporal conditions as represented by seasonal epidemics should be considered for the decision of intervention scheme provided as a preprocedural mouth rinse, in an attempt to reduce the load of aerosolized pathogens. In normal conditions, chlorhexidine 0.2%, preferably under elevated temperature state should be prioritized for reducing bacterial counts. In the presence of oxidation vulnerable viruses within the community, substitute strategies might be represented by the use of povidone iodine 0.2%-1%, or hydrogen peroxide 1%. After debonding, extensive material grinding, as well as aligner related attachment clean-up, should involve the use of carbide tungsten burs under water cooling conditions for cutting efficiency enhancement, duration restriction of the procedure, as well as reduction of aerosolized nanoparticles. In this respect, selection strategies of malocclusions eligible for aligner treatment should be reconsidered and future perspectives may entail careful and more restricted utilization of attachment grips. For more limited clean-up procedures, such as grinding of minimal amounts of adhesive remnants, or individualized bracket debonding in the course of treatment, hand-instruments for remnant removal might well represent an effective strategy. Efforts to minimize the use of rotary instrumentation in orthodontic settings might also lead the way for future solutions. Measures of self-protection for the treatment team should never be neglected. Dressing gowns and facemasks with filter protection layers, appropriate ventilation and fresh air flow within the operating room comprise significant links to the overall picture of practice management. Risk management considerations should be constant, but also updated as new material applications come into play, while being grounded on the best available evidence.

Adverse reactions to orthodontic materials

Adverse effects can arise from the clinical use of orthodontic materials, due to the release of constituent substances (ions from alloys and monomers, degradation by-products, and additives from polymers). Moreover, intraoral aging affects the biologic properties of materials. The aim of this review is to present the currently identified major adverse effects of the metallic and polymeric components found in orthodontic appliances and materials. Corrosion in metallic orthodontic attachments releases metal ions, mainly iron, chromium, and nickel. The latter has received the greatest attention because of its reported potential for an allergic response. The formation of an oxide layer may inhibit the outward movement of ions, thereby acting as an obstacle for release. Titanium alloys have superior corrosion resistance than stainless steel. The efficiency of polymerisation is considered an essential property for all polymers. A poor polymer network is susceptible to the release of biologically reactive substances, such as bisphenol-A (BPA), which is capable of inducing hormone-related effects. The close proximity of a light-curing tip to the adhesive, pumice prophylaxis after bonding, indirect irradiation and mouth rinsing during the first hour after bonding may decrease BPA release. The adverse effects of some orthodontic materials should be considered during material selection and throughout orthodontic treatment, in order to minimise possible undesirable implications.

Retrieval analysis of lingual fixed retainer adhesives

INTRODUCTION

Our objective was to analyze the surface and bulk properties alterations of clinically aged composites used for fixed retention.

METHODS

Twenty-six lingual retainers bonded for different time periods (2.2-17.4 years) were retrieved from postorthodontic patients. Fifteen lingual retainers had been cemented by a chemically cured adhesive (Maximum Cure, Reliance Orthodontic Products, Itasca, Ill), and 11 were treated with a photo-cured adhesive (Flow-Tain, Reliance Orthodontic Products). The first group was in service for 2.8 to 17.4 years and the second for 2.2 to 5.4 years. Five specimens from each material were prepared and used as the control (or reference) group. The debonded surfaces from enamel were studied by attenuated total reflectance Fourier transform infrared spectroscopy (n = 3 per material per group), low-vacuum scanning electron microscopy, and energy dispersive x-ray microanalysis (n = 3 per material per group). All specimens were used for the assessment of Vickers hardness, indentation modulus, and elastic index with the instrumented indentation testing method. The values of Vickers hardness, indentation modulus, and elastic index were compared between the retrieved and the reference groups with 1-way analysis of variance and the Student-Newman-Keuls multiple comparison test (α = 0.05).

RESULTS

The attenuated total reflectance Fourier transform infrared spectroscopy analysis showed that both retrieved composites demonstrated reduced unsaturation in comparison with the corresponding reference specimens. Some bonded surfaces showed development of organic integuments. All retrieved specimens showed reduced silicon content. Barium was identified only in the photo-cured group. No significant differences were found between the reference and retrieved groups in Vickers hardness, indentation modulus, and elastic index.

CONCLUSIONS

Despite the changes in composition, the mechanical properties of the materials tested remained unaffected by intraoral aging.

Oral Decontamination of Orthodontic Patients Using Photodynamic Therapy Mediated by Blue-Light Irradiation and Curcumin Associated with Sodium Dodecyl Sulfate

OBJECTIVE

The aim of this study was to investigate the effects of the antimicrobial photodynamic therapy (aPDT) using the association of curcumin with the surfactant sodium dodecyl sulfate (SDS) for oral decontamination in orthodontic patients.

BACKGROUND DATA

The installation of the orthodontic appliances promotes an increase in the retentive area that is available for microbial aggregation and makes difficult the oral health promotion. However, aPDT is one possible approach that is used for the reduction of oral microbial load.

MATERIALS AND METHODS

Twenty-four patients (n = 24) were randomly distributed into four groups: Light group: which was treated only with the blue light, no drug; PDT group, which was treated with curcumin and blue light; PDT + S group, which was treated with curcumin plus surfactant and irradiated with blue light; and Chlorhex group, which was treated with chlorhexidine. The photosensitizer agent was prepared by adding 0.1% of SDS to a curcumin solution of 1 g/L. Two distinct LED devices emitting blue light (450 ± 10 nm) were used as follows: extra-oral irradiation (200 mW, 80 mW/cm(2), 36 J and 14 J/cm(2)) and intra-oral irradiation (1200 mW, 472 mW/cm(2), 216 J and 85 J/cm(2)).The collection of nonstimulated saliva (n = 3; 3 mL/collection) was performed at the following steps: (1) immediately before swishing (curcumin, chlorhexidine, or water); (2) after swishing; and (3) after performing aPDT treatments. The colony-forming units (CFU) were counted visually, and the values were adjusted to CFU/mL.

RESULTS

There was significant Log reduction for PDT (from 6.33 ± 0.92 to 5.78 ± 0.96, p < 0.05), PDT + S (from 5.44 ± 0.94 to 3.83 ± 0.71, p < 0.01), and Chlorhex (from 5.89 ± 0.97 to 2.55 ± 1.80, p < 0.01) groups. The survival rate was significantly reduced in both PDT + S and Chlorhex groups compared with all situations (p < 0.05). However, there was no significant difference between PDT + S and Chlorhex groups (p ≥ 0.05).

CONCLUSIONS

These results indicate that when associated with the surfactant SDS, the aPDT can be used as an adjutant and a convenient agent to promote the oral decontamination in clinical practice.

Do we need a randomized controlled trial to assess trivial, albeit standard used, clinical steps in bonding? The answer is yes, but there are some interpretation issues

The feasibility of generalizing and extrapolating the results of the RCT assessing the necessity of a bonding stage to the routine clinical situation is discussed in this commentary. The lack of difference in failure rate between the two procedures followed may not receive the dimensions of a directive to alter a step of the bonding process, before other factors related to the performance of the materials are considered.