Shedding light on a potential hazard: Dental light-curing units

Enhancing Light-curing Competence: A Study of Radiant Exposure and Training Outcomes Among Dental Students

OBJECTIVES

The aim of this study was to measure radiant exposure and time necessary to deliver 16 J/cm2 of radiant exposure to simulated Class I and Class III preparations by first-year dental students. First-year dental students (n=89) received a 60-minute lecture on light-curing. Using the Managing Accurate Resin Curing Patient Simulator (MARC-PS) and protective blue-light-blocking glasses, students twice light-cured Class I and Class III restorations, using the Valo Grand Cordless light-curing unit with infection-control barriers on both Standard and High Power Plus modes. After their first attempts, if students did not obtain at least 16 J/cm2 of radiant exposure (RE), they received additional instruction. Paired t-tests were used to determine the change between the first and second attempts. After averaging two attempts, radiant exposure and time were compared between Standard and High Power Plus modes within individuals using paired t-tests.

RESULTS

79% of students provided 16 J/cm2 of radiant exposure on both attempts for Standard and High Power Plus modes. High Power Plus mode provided statistically significantly more radiant exposure and required less time to obtain 16 J/cm2 of radiant exposure for both restorations.

CONCLUSIONS

The MARC-PS is useful to identify students requiring instruction. It may be prudent to use High Power Plus mode or increase time on Standard mode to light-cure Class I restorations.

Alternative Direct Restorative Materials for Dental Amalgam: A Concise Review Based on an FDI Policy Statement

Dental restorative procedures remain a cornerstone of dental practice, and for many decades, dental amalgam was the most frequently employed material. However, its use is declining, mainly driven by its poor aesthetics and by the development of tooth-coloured adhesive materials. Furthermore, the Minamata Convention agreed on a phase-down on the use of dental amalgam. This concise review is based on a FDI Policy Statement which provides guidance on the selection of direct restorative materials as alternatives to amalgam. The Policy Statement was informed by current literature, identified mainly from PubMed and the internet. Ultimately, dental, oral, and patient factors should be considered when choosing the best material for each individual case. Dental factors include the dentition, tooth type, and cavity class and extension; oral aspects comprise caries risk profiles and related risk factors; and patient-related aspects include systemic risks/medical conditions such as allergies towards certain materials as well as compliance. Special protective measures (eg, a no-touch technique, blue light protection) are required when handling resin-based materials, and copious water spray is recommended when adjusting or removing restorative materials. Cost and reimbursement policies may need to be considered when amalgam alternatives are used, and the material recommendation requires the informed consent of the patient. There is no single material which can replace amalgam in all applications; different materials are needed for different situations. The policy statement recommends using a patient-centred rather than purely a material-centred approach. Further research is needed to improve overall material properties, the clinical performance, the impact on the environment, and cost-effectiveness of all alternative materials.

A Historical Perspective on Dental Composite Restorative Materials

This review article will discuss the origin of resin-based dental composite materials and their adoption as potentially useful adjuncts to the primary material used by most dentists for direct restorations. The evolution of the materials, largely driven by the industry's response to the needs of dentists, has produced materials that are esthetic, strong, and versatile enough to be used in most areas of the oral cavity to replace or restore missing tooth structures. Significant advancements, such as the transition from chemical to light-curing materials, refinements in reinforcing particles to produce optimum polishing and wear resistance, formulating pastes with altered viscosities to create highly flowable and highly stiff materials, and creating materials with enhanced depth of cure to facilitate placement, will be highlighted. Future advancements will likely reflect the movement away from simply being a biocompatible material to one that is designed to produce some type of beneficial effect upon interaction within the oral environment. These new materials have been called "bioactive" by virtue of their potential effects on bacterial biofilms and their ability to promote mineralization of adjacent tooth structures.

Shedding light on the problem: Proficiency and maintenance practices of light-curing units among dental assistants

BACKGROUND

Proper light curing is crucial for the success of restorative dentistry and to bond brackets to teeth, yet the responsibility is often delegated to dental assistants (DAs). This study assessed the proficiency and maintenance protocols of DAs when using light-curing units (LCUs) in Saudi Arabia.

METHODS

Self-administered questionnaires were distributed to practicing DAs. The questionnaire contained sections on knowledge, adherence to best practices, and how to maintain the LCU. Demographic data were collected as well. Descriptive statistics and linear regressions at a significance level of (p = 0.05) were conducted to identify any relationships that influenced the DAs' LCU knowledge, practice, and maintenance protocols.

RESULTS

Among the surveyed DAs, 66% were responsible for using the LCU during treatment, 16% used their fingers for support when light curing, 50% held the LCU tip 1-2 mm from the restoration during curing, and 51% did not have a specific maintenance protocol at their workplace. 70% did not know the output from the LCU, and their educational background correlated with knowledge (b = -14.42, p < 0.001). The type of institution type correlated with adherence to best practices (b = -13.65, p = 0.011), and level of knowledge and adherence to maintenance protocols showed a direct correlation (b = 0.002, p = 0.041).

CONCLUSIONS

The findings revealed that a significant percentage of the DAs who replied had insufficient knowledge and did not follow the best practices and maintenance protocols for the LCUs they were using. Their educational background and workplace factors influenced this knowledge gap, while the absence of a maintenance protocol and suboptimal practices were associated with the type of institution.

CLINICAL SIGNIFICANCE

To maintain the best practice, clinicians and institutions should improve the education and training of DAs. Otherwise, inadequate light curing by the DAs may jeopardize the long-term success of many dental procedures.

Skill Retention of Light-Curing Technique Using Only Verbal Instructions versus Using an Instructional Video: A 2-Year Follow-Up Study of Dental Students

PURPOSE

To evaluate the retention of light-curing skills among dental students after two years of clinical experience and determine if there are any differences in the skills retention between students who received verbal instructions or those who had received an instructional video. The students' satisfaction with past learning, self-confidence, and general knowledge about light-curing were also evaluated.

METHODS

This study is a 2-year evaluation of previous work. Students had previously been divided into two groups: those who received only verbal instructions, and those who received only an instructional video about the correct light curing technique to use clinically. Each student had light-cured simulated restorations (anterior and posterior) for 10 sec using the Managing Accurate Resin Curing-Patient Simulator (MARC-PS) (BlueLight Analytics, Halifax, Nova Scotia, Canada) and a multiple-emission peak light-emitting-diode (Bluephase N, Ivoclar Vivadent, Schaan, Liechtenstein) curing light. Students then received instructions according to their assigned group and light-cured the simulated cavities again. Two years later, students from both groups light-cured the same simulated cavities. Then, they completed a modified version of the National League of Nursing (NLN) satisfaction and self-confidence questionnaire and answered light-curing knowledge questions. Statistical analysis: The mean radiant exposure values delivered before receiving specific instructions on light curing, immediately after, and two years after instruction for both teaching methods (Friedman test followed by Wilcoxon signed-rank post hoc test), and the difference between both teaching methods was assessed (two-sample Wilcoxon rank-sum test). The satisfaction and self-confidence scores were compared between teaching method groups (Wilcoxon rank-sum test) (p<0.05).

RESULTS

The mean and median irradiance values ranged between 194-1777 and 1223-1302 mW/cm² before instructions, 320-1689 and 1254-1394 mW/cm² immediately after instructions, and 95-1945 and 1260-1331 mW/cm² two years later regardless of the simulated restoration or the teaching method. The mean and median radiant exposure values ranged between 2-23 and 12.5-13.6.4 J/cm² before instructions, 3-28 and 12.8-14.3 mW/cm² immediately after instructions, and 0.7-20 and 12.8-13.6 mW/cm² two years later regardless of the simulated tooth being light cured and the teaching method. Students retained their light-curing skills after two years of clinical experience, with no significant differences between both groups. The instructional video group delivered significantly higher radiant exposure values (p=0.021) when light-curing the anterior tooth than the posterior. Students were satisfied with their past learning and confident in their light-curing skills (p=0.020). There were statistical differences in how well the two groups remembered what they had been taught about light-curing. Only 5.7% of students answered all knowledge questions correctly.

CONCLUSION

Students retained their light-curing skills after two years of clinical experience, with no significant difference between verbal instructions or instructional video teaching methods. However, their knowledge about light curing remained very poor. Nevertheless, the students were satisfied with how they had been taught and had confidence in both teaching methods.

The Involvement of Photobiology in Contemporary Dentistry-A Narrative Review

Light is an emerging treatment approach that is being used to treat many diseases and conditions such as pain, inflammation, and wound healing. The light used in dental therapy generally lies in visible and invisible spectral regions. Despite many positive results in the treatment of different conditions, this therapy still faces some skepticism, which has prevented its widespread adoption in clinics. The main reason for this skepticism is the lack of comprehensive information about the molecular, cellular, and tissular mechanisms of action, which underpin the positive effects of phototherapy. However, there is currently promising evidence in support of the use of light therapy across a spectrum of oral hard and soft tissues, as well as in a variety of important dental subspecialties, such as endodontics, periodontics, orthodontics, and maxillofacial surgery. The merging of diagnostic and therapeutic light procedures is also seen as a promising area for future expansion. In the next decade, several light technologies are foreseen as becoming integral parts of modern dentistry practice.

Influence of Light-EmittingDiode-Derived Blue Light Overexposure on Rat Ocular Surface

We aim to investigate the effect of overexposure to blue light on the rat ocular surface and explore the potential mechanisms. 450 nm light-emitting diode (LED) derived light at 1000 lux was used to irradiate SD rats, 12 hours a day, for consecutive 28 days. Rats in the control group were exposed to 400 lux white light at the same time (in an indoor environment). Tear film breakup time (TBUT), tear volume, and corneal fluorescein staining scores were used to measure the changes to the ocular surface. Expressions of nuclear factor-κB (NF-κB), inhibitor-κB (I-κB), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured by real-time PCR, and the activation of the NF-κB pathway was detected by Western blotting, respectively. Cornea ultrastructure was examined by TEM and optical microscope on day 28. Pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB signaling pathway, was used to measure the inhibition of blue light injury. The above indexes were detected again when compared with the solvent-treated group. On day 28, compared with day 0, the TBUT of the blue light group was significantly shorter, and the score was significantly higher. The amount of tear secretion changed slightly with time. HE and PAS staining revealed significantly decreased corneal epithelial cell layers and increased goblet cells after 28-day irradiation of blue light. Disarranged stromal cells, vacuoles in the basal nuclei, and decreased desmosomes were also found in the blue light group. Significantly increased levels of NF-κB, IL-6, TNF-α, and the ratio of phosphorylated NF-κB p65 (pNF-κB p65) to total NF-κB p65 implied blue light-induced damage and pathway activation. In addition, PDTC significantly reduced the phosphorylation of NF-κB activated in blue light-treated corneas and alleviated the ocular surface changes caused by blue light. Finally, our results demonstrated that long-term blue light exposure in rats could cause ocular surface changes and manifest as dry eye. Inflammation and activation of the NF-κB pathway may play a role in the pathogenesis.

Resin Composites in Posterior Teeth: Clinical Performance and Direct Restorative Techniques

Resin composites are the most versatile restorative materials used in dentistry and the first choice for restoring posterior teeth. This article reviews aspects that influence the clinical performance of composite restorations and addresses clinically relevant issues regarding different direct techniques for restoring posterior teeth that could be performed in varied clinical situations. The article discusses the results of long-term clinical trials with resin composites and the materials available in the market for posterior restorations. The importance of photoactivation is presented, including aspects concerning the improvement of the efficiency of light-curing procedures. With regard to the restorative techniques, the article addresses key elements and occlusion levels for restoring Class I and Class II cavities, in addition to restorative strategies using different shades/opacities of resin composites in incremental techniques, restorations using bulk-fill composites, and shade-matching composites.

Dental Light-Curing-Assessing the Blue-Light Hazard

This article focuses on the current understanding and concerns over the blue-light hazard when using dental light-curing units. It also provides information and safety protocols to guide the practitioner in making important decisions regarding dental personnel's health and the quality of dental restorations.

The potential 'Blue Light Hazard' from LED Headlamps

Many dental personnel use light-emitting diode (LED) headlamps for hours every day. The potential retinal 'blue light hazard' from these white light headlamps is unknown.

METHODS

The spectral radiant powers received from direct and indirect viewing of an electronic tablet, an LED curing light, a halogen headlamp, and 6 brands of LED headlamps were measured using integrating spheres attached to fiberoptic spectroradiometers. The spectral radiant powers were measured both directly and indirectly at a 35 cm distance, and the maximum daily exposure times (t_MAX) were calculated.

RESULTS

The headlamps emitted very different radiant powers, emission spectra, and color temperatures (K). The total powers emitted at zero distance ranged from 47 mW from the halogen headlamp to 378 mW from the most powerful LED headlamp. The color temperatures from the headlamps ranged from 3098 K to 7253 K. The t_MAX exposure times in an 8-hour day when the headlamps were viewed directly at a distance of 35 cm were: 810 s from the halogen headlamp, 53 to 220 s from the LED headlamps, and 62 s from the LED curing light. Light from the LED headlamps that was reflected back from a white reference tile 35 cm away did not exceed the maximum permissible exposure time for healthy adults. Using a blue dental dam increased the amount of reflected blue light, but t_MAX was still greater than 24 hours.

CONCLUSIONS

White light LED headlamps emit very different spectra, and they all increase the retinal 'blue light hazard' compared to a halogen source. When the headlamps were viewed directly at a distance of 35 cm, the 'blue light hazard' from some headlamps was greater than from an LED curing light. Depending on the headlamp brand, t_MAX could be reached after only 53s. The light from the LED headlamps that was reflected back from a white surface that was 35 cm away did not exceed the maximum permissible ocular exposure limits for healthy adults.

CLINICAL RELEVANCE

Reflected white light from dental headlamps does not pose a blue light hazard for healthy adults. Direct viewing may be hazardous, but the hazard can be prevented by using the appropriate blue-light-blocking glasses.

[Light-curing effectiveness using led lamps: a review]

Introduction

LED lamps have a new light-curing technology which can be monowave or polywave, which allows it to reach more initiators such as camphorquinone, Lucirin TPO and Propanodione, which have a wide variety of advantages and disadvantages. These lamps have evolved over time, as have different ergonomics, longevity, systems and quality standards.

Objective

The objective of this literature review is to improve the clinician on the proper use of different LED lamps and how they influence the efficiency of resin photopolymerization.

Material and methods

Extensive research has been carried out in the existing literature on this topic. From the beginning of this information until April 18, 2022, the bibliographic search carried out includes 86 articles published in the Medline database through PubMed, LILACS, Science Direct and SciELO, and there is no language restriction.

Results

The photopolymerization effects of Polywave and Monowave LED lamps present significant differences between the compressive strength of the light-cured resin, with single-wave and polyvalent LED lamps where the types of light and lamp directly influence the compressive strength of the resin. composite resins.

Conclusion

The type of light and lamp directly affects the efficiency of the photopolymerization of the composite resin, so it is concluded that LED lamps with single wave technology (Monowave) produce a greater depth of photopolymerization than those with multiple wave technology (Polywave).

The Ability of Dental Practitioners to Light-Cure Simulated Restorations

CLINICAL RELEVANCE

Using a patient simulator, dental professionals were tested to determine their ability to light-polymerize simulated restorations in their dental practice. After receiving specific instructions and training using the simulator, their ability to deliver sufficient light to polymerize restorations was significantly and substantially improved.

SUMMARY

Objectives: To determine the ability of dental professionals to deliver a radiant exposure of at least six J/cm2 in 10 seconds to simulated restorations.Methods and Materials: The study initially examined 113 light-emitting-diode (LED) light polymerization units (LPUs) used in dental offices to determine if they could deliver at least 6 J/cm2 radiant exposure (RE) in 10s. This assessment was completed by using a laboratory-grade light measuring device (checkMARC, BlueLight Analytics, Halifax, NS, Canada). The participating dental professionals whose LPUs could deliver 6 J/cm2 then used their own LPU to light-cure simulated anterior and posterior restorations in the MARC Patient Simulator (BlueLight Analytics). They then received specific instructions and were retested using the same LPUs. Data were statistically analyzed with a series of one-way analysis of variance (ANOVA), two-way ANOVA, paired-samples t-tests, Fisher post hoc multiple comparison tests, and McNemar tests with a preset alpha of 0.05 (SPSS Inc).Results: Ten (8.8%) LPUs could not deliver the required RE to the checkMARC in 10s and were eliminated from the study. For the anterior restoration, most dental practitioners (87.3%) could deliver at least 6 J/cm2 before instructions. After receiving additional light-curing instructions, only two (1.9%) participants were unable to deliver 6 J/cm2 to the anterior location. At the posterior location, only 55.3% (57) participants could deliver at least 6 J/cm2 before the instructions. After receiving these instructions, an additional 32 participants delivered at least 6 J/cm2. Overall, after receiving instructions on how to use the LPU correctly, the participants improved the amount of RE they delivered to anterior and posterior restorations by 22.5% and 30%, respectively.Conclusion: This study revealed that at the baseline, 44.7% of participating dental professionals failed to deliver 6 J/cm2 in 10s to the posterior simulated restoration when using their own LPU.

Mechanisms of blue light-induced eye hazard and protective measures: a review

The risk of blue light exposure to human health has attracted increased research attention. Blue light, with relatively high energy, can cause irreversible photochemical damage to eye tissue. Excessive exposure of the eye to blue light tends to cause a series of alterations, such as oxidative stress, mitochondrial apoptosis, inflammatory apoptosis, mitochondrial apoptosis and DNA damage, resulting in the development of dry eye disease, glaucoma, and keratitis. Accordingly, physical protection, chemical and pharmaceutical protective measures, gene therapy, and other methods are widely used in the clinical treatment of blue light hazard. We reviewed the studies on possible blue light-induced signaling pathways and mechanisms in the eye and summarized the therapeutic approaches to addressing blue light hazard.

The light-curing unit: An essential piece of dental equipment

INTRODUCTION

This article describes the features that should be considered when describing, purchasing and using a light-curing unit (LCU).

METHODS

The International System of Units (S.I.) terms of radiant power or radiant flux (mW), spectral radiant power (mW/nm), radiant exitance or tip irradiance (mW/cm² ), and the irradiance received at the surface (also in mW/cm² ) are used to describe the output from LCU. The concept of using an irradiance beam profile to map the radiant exposure (J/cm² ) from the LCU is introduced.

RESULTS

Even small changes in the active tip diameter of the LCU will have a large effect on the radiant exitance. The emission spectra and the effects of distance on the irradiance delivered are not the same from all LCUs. The beam profile images show that using a single averaged irradiance value to describe the LCU can be very misleading. Some LCUs have 'hot spots' of high radiant exitance that far exceed the current ISO 10650 standard. Such inhomogeneity may cure the resin unevenly and may also be dangerous to soft tissues. Recommendations are made that will help the dentist when purchasing and then safely using the LCU.

CONCLUSIONS

Dental manufacturers should report the radiant power from their LCU, the spectral radiant power, information about the compatibility of the emission spectrum from the LCU with the photoinitiators used, the active optical tip diameter, the radiant exitance, the effect of distance from the tip on the irradiance delivered, and the irradiance beam profile from the LCU.