Spectrophotometric analysis of the effectiveness of different dentin tubule occlusion techniques in preventing discoloration caused by photosensitizers used in photodynamic therapy

AIM

The efficacy of Copal Varnish (CV), dentin bonding agent (DBA), Nd:YAG laser and Er:YAG laser, which occludes dentin tubules by different mechanisms, was investigated in order to prevent unwanted coloration caused by methylene blue (MB) and phthalocyanine used in photodynamic therapy (PDT).

MATERIALS AND METHODS

165 upper incisors included in the study. Root canals were prepared up to 30/0.6 size for all teeth using Protaper Next rotary files. Then the teeth were randomly divided into 2 main groups (n = 60); MB and phthalocyanine. Each main group was randomly divided into 5 subgroups (n = 15); Positive control, DBA, CV, Er:YAG and Nd:YAG. Root canals were filled with photosensitizers (PS) and activated after the dentin tubule occlusion method was applied to all teeth. Then, the residual PSs were removed by irrigation. Color measurements of the samples were carried out 5 different time periods.

RESULTS

Clinically detectable color change was observed in all groups except for the negative control (ΔE≥3.3). It was determined that the positive control using MB caused more unwanted coloration in the CV on the 30th and 90th days compared to the phthalocyanine used in the 90th day (p < 0.05). While none of the dentin tubule occlusion methods were superior to each other in preventing undesirable coloration caused by phthalocyanine, Er:YAG caused less unwanetd coloration than CV only on the 90th day in preventing unwanted coloration caused by MB (p < 0.05).

CONCLUSIONS

All dentin tubule occlusion methods used in the present study were effective in preventing some degree of unwanted discoloration. However, it was found that no technique could completely prevent unwanted coloration.

Synthesis of Er3+:YAG Nanocrystals and Comparative Spectroscopic Analysis with Bulk Counterparts

Single-crystal Er³⁺:YAG has long been used as a laser material, and recent work has shown polycrystalline ceramic Er³⁺:YAG to be a suitable laser material, with benefits of lower cost and easier production. However, relatively little work has been done with the synthesis and spectroscopic characterization of Er³⁺:YAG nanocrystals. In this work, we present the synthesis of nanocrystalline Er³⁺:YAG and the results of comparative spectroscopic characterization with single-crystal and polycrystalline ceramic counterparts. The results show good agreement between the optical properties of the three hosts, with the nanocrystals demonstrating relatively higher intensity in the 1.53 μm emission. These results demonstrate the viability of Er³⁺:YAG nanocrystals as a potential laser material.

Efficacy of 532-nm Q-switched Nd:YAG Laser in the Treatment of Lip Melanosis

Introduction:

Lip pigmentation is frequently encountered in the Dermatology outpatient department. No effective treatment is available so far. Topical treatment requires longer time and is often unsatisfactory.

Aim:

The aim of this work was to study the efficacy of 532-nm Q-switched Nd:YAG laser in the treatment of lip melanosis.

Settings and Design:

This was a prospective interventional study.

Materials and Methods:

Twenty patients in the age group 27–53 years were included in the study. Eight patients had diffuse pigmentation and twelve patients had focal pigmentation. Test spot was done. After topical anesthesia, Q-switched Nd:YAG laser was used. Treatment interval was 4 weeks. Follow-up was done at 1 week and then monthly.

Statistical Analysis Used:

Wilcoxon signed ranks test and P value.

Results:

Seven patients (35%) showed an excellent response with more than 75% of pigment clearance. Seven patients (35%) showed a good response, two patients (10%) moderate response, and two patients (10%) had a mild response. Two patients had recurrence after 3 months follow-up. The average number of sessions required for clearance of pigmentation was 2.5. No scarring was seen.

Conclusion:

532-nm Q-switched Nd:YAG laser is safe and effective in the management of lip pigmentation and gives rapid results.

Laser Lithotripsy: The Importance of Peak Power and Pulse Modulation

Despite the worldwide spread of Ho:YAG lasers in urology departments, the physical principles behind their functioning may still seem obscure to many urologists. Moreover, a new laser source, the thulium fiber laser (TFL), was recently approved for stone lithotripsy. Here we describe the concepts of peak power and pulse modulation for laser lithotripsy, analyzing both Ho:YAG lasers and TFLs. Different pulse modalities are available for Ho:YAG lasers-long and short pulses and Moses technology-each with a different pulse shape and peak power. Lower peak power and a more rectangular pulse shape provide higher ablation efficiency and lower stone retropulsion. These characteristics are perfectly embodied by TFL, which shows the most effective ablation efficiency in laboratory studies. A long pulse is the most effective modality for Ho:YAG lasers. Moses technology, despite its promising rationale, is not superior to long-pulse mode. Clinical studies are needed in order to confirm these laboratory data. PATIENT SUMMARY: Laser lithotripsy is one of the main options for the treatment of urinary stones. The peak power and pulse modulation influence the choice of the optimal laser mode for the treatment of urinary stones. Thulium fiber lasers have shown the most favorable dusting profile in terms of both peak power and pulse modality in laboratory studies, but clinical evidence is still lacking.

COVID-19 Impact on Young Arthroplasty Surgeons

BACKGROUND

The current coronavirus crisis, COVID-19, has affected all orthopedic surgeons. Surgeons at early stages of their career are at risk of being affected differently than their more established counterparts.

METHODS

We conducted an online survey for members of the Young Arthroplasty Group to determine what effects this had on their current practice.

RESULTS

Nearly 40% of our surveyed group responded ranging from residents, fellows, and early career surgeons. All groups had been affected by the crisis, with different impacts on each subgroup.

CONCLUSION

COVID-19 had significant impact on young surgeons affecting their compensation, redeployment, and career advancement. Available resources should be offered to this group, where available, to mitigate the impact of the crisis.

Management of recalcitrant vitiligo in Vogt-Koyanagi-Harada syndrome: Adjuvant ablative fractional laser

The course of dermatologic findings in Vogt-Koyanagi-Harada disease is variable. Herein, we report the remarkable repigmentation of widespread facial vitiligo lesions in an adolescent girl with Vogt-Koyanagi-Harada disease. The patient was treated with a combination of fractional erbium:YAG laser, topical tacrolimus, and phototherapy.

Safety and Efficacy of YAG Laser Vitreolysis for the Treatment of Vitreous Floaters: An Overview

Emerging evidence has suggested that the entoptic phenomena associated with vitreous opacities (i.e. vitreous floaters) are more bothersome than previously believed. In addition, the prevalence of vitreous floaters is likely increasing due to the evolving global pandemic of myopia. The use of YAG laser vitreolysis for the treatment of annoying vitreous floaters has attracted significant attention in recent years as the technique offers a number of potential advantages. Unfortunately, the currently available evidence that is needed to guide clinical practice is both very limited and contradictory. As a consequence, the technique remains highly controversial. A review of the existing literature sheds light on patient- and treatment-related factors that may significantly affect both the effectiveness and the safety of the procedure. The current article discusses important aspects of key publications on the topic, offers suggestions for clinical practice, and highlights unmet needs that should be addressed by future research.

Persistence of Descemet membrane and recipient-type endothelium after keratoplasty. A case report

A case is presented of a retained Descemet's membrane after penetrating keratoplasty, highlighting the importance of the anterior segment optical coherence tomography (OCT) in the diagnosis and treatment planning of keratoplasty complications. A review of literature is also presented. An 88 year-old man underwent penetrating keratoplasty for bullous keratopathy. A retained host Descemet's membrane was detected. The retained membrane went unnoticed until the visual acuity decreased. The ophthalmological examination showed the presence of an opalescent membrane located below the endothelium, and was identified as the Descemet membrane of the receptor. Nd:YAG laser membranotomy was performed after the diagnosis. To conclude, it is noted that the inadvertent retention of the host Descemet membrane is a rare complication in penetrating keratoplasty. The anterior segment OCT was used to determine the diagnosis, and Nd:YAG laser membranotomy is an indicated treatment in these cases.

Effect of Er:YAG and Fluoride Varnishes for Preventing Primary Enamel Demineralisation

PURPOSE

To measure the demineralisation changes on human deciduous enamel produced by pH cycling after preventive treatment with Er:YAG laser irradiation, fluoride varnish application and a combination of the two.

MATERIALS AND METHODS

Sixty extracted human anterior primary teeth were assigned to six groups (n = 10). Group C: untreated; group L: Er:YAG laser; group TCP-NaF: Clinpro White (5% sodium fluoride and modified tricalcium phosphate); group CPP-ACP-NaF: MI varnish (5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate); group L+TCP-NaF: Er:YAG + 5% sodium fluoride + modified tricalcium phosphate; group L+ CPP-ACP-NaF: Er:YAG + 5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate. The samples were subjected to a 10-day pH-cycling regimen to create caries-like lesions, with 8 h in demineralising solution and 16 h in remineralising solution at 37°C. Enamel demineralisation was evaluated by laser fluorescence (DIAGNOdent) before and after pH cycling. The Mann-Whitney U-test and Wilcoxon tests were performed with statistical significance set at p ≤ 0.05.

RESULTS

The Wilcoxon test revealed statistically significant differences at baseline and after pH cycling in groups C (p = 0.02), L (p = 0.034) and L+TCP-NaF (p = 0.025) and the lowest percentage of healthy tooth substance compared to the other groups.

CONCLUSIONS

The results suggest that the treatment protocols employed in groups TCP-NaF, CPP-ACP-NaF, and L+ CPP-ACP-NaF had similar effects in terms of preventing demineralisation, as reflected in a higher percentage of healthy dental structure maintained. Hence, these treatments are recommended for clinical use as an effective preventive measure.

Optimized Scintillator YAG:Pr Nanoparticles for X-ray Inducible Photodynamic Therapy

We describe a sol-gel synthetic method for the production of praseodymium-doped yttrium aluminum garnet (YAG) nanoparticles suitable for X-ray inducible photodynamic therapy (X-PDT). Our sol-gel based approach was optimized by varying temperature and time of calcination, resulting in nanoparticles that were smooth, spherical, and 50-200 nm in crystallite size. The powders were uniformly coated with a thin (10 nm) layer of silica to facilitate surface conjugation with functional moieties. Measurements of photon flux revealed that coated and uncoated powders emitted a similar photon emission spectrum in response to 50 keVp X-rays. We also determined that the presence of silica did not significantly reduce flux and the emission peak had a maximum at approximately 320 nm. Thus, these YAG:Pr powders are suitable candidates for future in vivo X-PDT studies.

Treatment of atrophic facial acne scars with fractional Er:YAG laser in skin phototype III-IV: A pilot study

BACKGROUND

Fractional ablative lasers have recently been used for the treatment of skin scars. The objective of this study was to assess the efficacy and safety of the fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser (2940 nm) in the treatment of skin scars.

MATERIALS AND METHODS

A total of 9 patients (8 female, 1 male) with Fitzpatrick skin types III and IV suffering from atrophic facial acne scars were treated with a fractional Er:YAG laser for 2-5 (mean 3.3) sessions 4-6 weeks apart. One independent investigator assessed the efficacy, using standardized photographs, before and 1 month after the last treatment. The patients' satisfaction rate was also evaluated.

RESULTS

The treatment was well tolerated by all patients without any anesthesia. The downtime was 2-3 days. All patients showed improvement in scars: excellent in 1, good in 1, and fair in 7 patients. Six patients were highly satisfied and 3 were satisfied with treatment. No adverse effect was noted.

CONCLUSION

A fractional Er:YAG laser can deliver an effective and minimally invasive treatment for acne scars.

Co-Precipitation of YAG Powders for Transparent Materials: Effect of the Synthesis Parameters on Processing and Microstructure

The fabrication of transparent polycrystalline Y₃Al₅O₁₂ (YAG) is still a challenge, requiring the achievement of highly pure and fully dense, homogeneous materials. An important role is played by the powder characteristics: pure, fine and unagglomerated powders are essential for achieving full density and the required microstructural features. Keeping in mind these requirements, the aim of this work was to investigate the role of different synthesis parameters during co-precipitation, which is widely used to prepare YAG powders for transparent devices. The key role of the precipitant solution is here illustrated, by comparing the effect of aqueous ammonia (AA) versus ammonium hydrogen carbonate (AHC). This latter allowed the preparation of softly agglomerated powders, characterized by a very good sinterability. However, when AHC is used, attention should be paid to its concentration. By comparing the effect of two AHC precipitant solutions (at 0.5 M and 1.5 M, respectively), only the former one allowed the preparation of pure YAG powders, free from secondary phases. In this last condition, by using both chlorides and nitrates as YAG precursors, pressureless sintering at 1500–1600 °C/3 h gave rise to pure materials, highly dense and characterized by a fine and homogeneous microstructure.

Current status of surgery in dermatology

An article titled "Current issues in dermatologic office-based surgery" was published in the JAAD in October 1999 (volume 41, issue 4, pp. 624-634). The article was developed by the Joint American Academy of Dermatology/American Society for Dermatologic Surgery Liaison Committee. A number of subjects were addressed in the article including surgical training program requirements for dermatology residents and selected advances in dermatologic surgery that had been pioneered by dermatologists. The article concluded with sections on credentialing, privileging, and accreditation of office-based surgical facilities. Much has changed since 1999, including more stringent requirements for surgical training during dermatology residency, and the establishment of 57 accredited Procedural Dermatology Fellowship Training Programs. All of these changes have been overseen and approved by the Residency Review Committee for Dermatology and the Accreditation Committee for Graduate Medical Education. The fertile academic environment of academic training programs with interaction between established dermatologic surgeons and fellows, as well as the inquisitive nature of many of our colleagues, has led to the numerous major advances in dermatologic surgery, which are described herein.