Increasing dental zirconia micro-retentive aspect through ultra-short pulsed laser microstructuring: study on flexural strength and crystal phase characterization

Objectives

Although ultra-short pulsed laser (USPL) microstructuring has previously improved zirconia bond-strength, it is yet unclear how different laser-machined surface microstructures and patterns may influence the material’s mechanical properties. Therefore, the aim of this study was to assess the flexural strength of zirconia after different USPL settings creating three different geometrical patterns with structures in micrometer scale.

Methods

One hundred sixty zirconia bars (3Y-TZP, 21 × 4 × 2.1 mm) were prepared and randomly divided into five groups (n = 32): no surface treatment (negative control-NC); sandblasting with Al₂O₃ (SB); and three laser groups irradiated with USPL (Nd:YVO₄/1064 nm/2-34 J/cm²/12 ps): crossed-lines (LC), random-hatching (LR), and parallel-waves (LW). Bars were subjected to a four-point flexural test (1 mm/min) and crystal phase content changes were identified by X-ray diffraction. Surface roughness and topography were analyzed through 3D-laser-profilometry and SEM. Data were analyzed with parametric tests for roughness and Weibull for flexural strength (α = 5%).

Results

LR (Mean[95%CI]: 852.0 MPa, [809.2–894.7]) was the only group that did not show a significantly different flexural strength than NC (819.8 MPa, [796.6–842.9]), (p > 0.05). All laser groups exhibited higher Weibull moduli than NC and SB, indicating higher reliability and homogeneity of the strength data. An increase of monoclinic phase peak was only observed for SB.

Conclusion

In conclusion, USPL created predictable, homogeneous, highly reproducible, and accurate surface microstructures on zirconia ceramic. The laser-settings of random-hatching (12 ps pulses) increased 3Y-TZP average surface roughness similarly to SB, while not causing deleterious crystal phase transformation or loss of flexural strength of the material. Furthermore, it has increased the Weibull modulus and consequently material’s reliability.

Clinical significance

Picosecond laser microstructuring (LR conditions) of 3Y-TZP ceramic does not decrease its flexural strength, while increasing materials realiability and creating highly reproducible and accurate microstructures. These features may be of interest both for improving clinical survival of zirconia restorations as well as enhancing longevity of zirconia implants.

Rhinophyma in women: a case series

Rosacea has an overall female predominance; however, rhinophyma, a feature attributed to advanced rosacea, is exceedingly rare in females. The impact of this condition on quality of life can be profound. Multiple treatment modalities have been described. However fully ablative carbon dioxide (CO2) laser for moderate-severe rhinophyma has been shown to be most effective with good cosmetic outcome and high patient satisfaction. We describe a series of 7 female patients presenting with rhinophyma to a tertiary NHS laser centre and a private dermatology clinic. A retrospective case review of rhinophyma management was performed, assessing presentation, treatments and outcomes. The mean age at presentation was 47 years (27-62 years). Three patients developed rhinophyma before the age of 30 years. One patient had severe, 2 patients had moderate and 4 patients had minor rhinophyma. Four patients underwent fractional CO2 laser treatment with a good cosmetic outcome. Two further patients developed scarring following fully ablative CO2 laser. Long-term low-dose oral isotretinoin was used in 3 patients following laser treatment, to prevent relapse. One patient solely received isotretinoin with a good outcome. In our experience, females suffering with rhinophyma presented for treatment at an early age and stage of severity. Fractional or fully ablative CO2 laser alone or in combination with oral isotretinoin is a very effective treatment modality.

Effect of different laser treatments on the shear bond strength of zirconia ceramic to resin cement

BACKGROUND

Several techniques such as sand blast, silicoating, and laser irradiation have been introduced for reliable bond between zirconia and resin cement. This study aimed to assess and compare the effect of three types of lasers on the shear bond strength (SBS) of zirconia to resin cement.

MATERIALS AND METHODS

In this in vitro study, 55 zirconia disks (6 mm diameter × 3 mm thickness) were randomly divided into five groups: control (1), sandblast (2), carbon dioxide (CO₂) (3), erbium-doped yttrium aluminum garnet (Er: YAG) (4), and neodymium-doped yttrium aluminum garnet (Nd: YAG) (5) laser irradiation. The surface morphology of one specimen from each group was evaluated by a scanning electron microscope. Zirconia disks were cemented to composite using Panavia F2. SBS test was performed at a crosshead speed of 1 mm/min after 24 h storage in distilled water and thermocycling. The data were analyzed by one-way analysis of variance and post hoc Tukey's HSD tests (α = 0.05).

RESULTS

The mean SBS values of the groups such as sandblast, Er: YAG, Nd: YAG, and CO₂ lasers and control were 6.64 MPa, 6.63 MPa, 4.98 MPa, 4.39 MPa, and 2.32 MPa, respectively. No significant difference was observed between sandblast and Er: YAG laser and between Nd: YAG and CO₂ lasers.

CONCLUSION

All lasers increased SBS values of zirconia to resin cement in comparison to the untreated surface. Er: YAG laser was the most effective laser treatment on the bond strength equal to that of sandblast.

Comparing intermediate-term hearing results of NiTiBOND and Nitinol prostheses in stapes surgery

OBJECTIVE

To statistically analyse the hearing thresholds of two cohorts undergoing stapedotomy for otosclerosis with two different prostheses.

METHOD

A retrospective study was conducted comparing NiTiBOND (n = 53) and Nitinol (n = 38) prostheses.

RESULTS

Average follow-up duration was 4.1 years for NiTiBOND and 4.4 years for Nitinol prostheses. The post-operative air-bone gap was 10 dB or less, indicating clinical success. The p-values for differences between (1) pre- and post-operative values in the NiTiBOND group, (2) pre- and post-operative values in the Nitinol group, (3) pre-operative values and (4) post-operative values in the two groups were: air-bone gap - p < 0.001, p < 0.001, p = 0.631 and p = 0.647; four-frequency bone conduction threshold - p = 0.076, p = 0.129, p < 0.001 and p = 0.005; four-frequency air conduction threshold - p < 0.001, p < 0.001, p = 0.043 and p = 0.041; three-frequency (1, 2 and 4 kHz) bone conduction threshold pre-operatively - p = 0.639, p = 0.495, p = 0.001 and p = 0.01; and air conduction threshold at 4 kHz: - p < 0.001, p < 0.001, p = 0.03 and p = 0.058.

CONCLUSION

Post-operative audiological outcomes for NiTiBOND and Nitinol were comparable.

[Hidradenitis suppurativa/acne inversa in daily practice]

Hidradenitis suppurativa (HS) is a chronic inflammatory disease, characterized by abscess formation and mutilating scar formation in the body folds. The burden of disease is high for both patient and treating physician. In dermatological daily practice, proper patient education and formation of a trustful physician-patient relationship are of highest importance. HS patients are treated both conservatively and surgically mostly by dermatologists, which requires extensive knowledge of the pathogenesis, trigger factors, comorbidities and treatment options. Interdisciplinary collaboration with other disciplines is still underdeveloped. New physical treatments (laser, radiofrequency, intense pulsed light [IPL]), topical and systemic therapies enable good ambulatory long-term management for all HS stages.

Appropriate Color Enhancement Settings for Blue Laser Imaging Facilitates the Diagnosis of Early Gastric Cancer with High Color Contrast

Purpose

Screening image-enhanced endoscopy for gastrointestinal malignant lesions has progressed. However, the influence of the color enhancement settings for the laser endoscopic system on the visibility of lesions with higher color contrast than their surrounding mucosa has not been established.

Materials and Methods

Forty early gastric cancers were retrospectively evaluated using color enhancement settings C1 and C2 for laser endoscopic systems with blue laser imaging (BLI), BLI-bright, and linked color imaging (LCI). The visibilities of the malignant lesions in the stomach with the C1 and C2 color enhancements were scored by expert and non-expert endoscopists and compared, and the color differences between the malignant lesions and the surrounding mucosa were assessed.

Results

Early gastric cancers mainly appeared orange-red on LCI and brown on BLI-bright or BLI. The surrounding mucosae were purple on LCI regardless of the color enhancement but brown or pale green with C1 enhancement and dark green with C2 enhancement on BLI-bright or BLI. The mean visibility scores for BLI-bright, BLI, and LCI with C2 enhancement were significantly higher than those with C1 enhancement. The superiority of the C2 enhancement was not demonstrated in the assessments by non-experts, but it was significant for experts using all modes. The C2 color enhancement produced a significantly greater color difference between the malignant lesions and the surrounding mucosa, especially with the use of BLI-bright (P=0.033) and BLI (P<0.001). C2 enhancement tended to be superior regardless of the morphological type, Helicobacter pylori status, or the extension of intestinal metaplasia around the cancer.

Conclusions

Appropriate color enhancement settings improve the visibility of malignant lesions in the stomach and color contrast between the malignant lesions and the surrounding mucosa.

Protective Role of 360° Laser Retinopexy in Patients with Rhegmatogenous Retinal Detachment: a Systematic Review and Meta-analysis

PURPOSE

Visual impairment from retinal re-detachment could be debilitating. The aim of this review is to evaluate the role of 360° laser retinopexy on success rate of rhegmatogenous retinal detachment (RRD) repair by a meta-analysis study.

METHODS

The PubMed, Scopus, and the Cochrane Library databases were searched comprehensively from the date of database inception to January 2021, evaluating the role of 360° laser retinopexy in visual and anatomical success rate of RRD repair. This review was conducted based on the preferred reporting items for systematic review and meta-analysis (PRISMA) protocols.

RESULTS

Among 202 articles screened for eligibility, six studies were found to be eligible for inclusion in our final analysis. Our meta-analysis demonstrates that prophylactic treatment with circumferential laser photocoagulation has no significant effect on the initial rate of retinal re-detachment or final best-corrected visual acuity following pars plana vitrectomy repair of RRD. Subgroup analysis of studies (n = 3) with 23-gauge pars plana vitrectomy, however, favors attachment rate in patients undergoing 360° prophylactic laser treatment.

CONCLUSIONS

Three hundred and sixty degree laser retinopexy appears to have favorable outcomes in patients undergoing 23-gauge retinal detachment repair. This protective effect, however, is not apparent with inclusion of 20-gauge vitrectomy studies.

Effect of photobiomodulation therapy on trunk flexor performance after incisional hernia repair: a randomized controlled trial

To investigate the effect of two photobiomodulation approaches on trunk flexor performance after incisional hernia repair and to compare the effects of both wavelengths. Forty-five patients were randomly distributed after isokinetic trunk flexor assessments into infrared laser, red laser, and placebo groups. Each patient received laser treatment followed by a traditional physical therapy program. In laser treatment, 24 points in both recti were irradiated by infrared or red laser light with the following parameters; 0.6 J per point, 214.28 J/cm² as energy density, and 17.85 W/cm² as intensity, while the control group received a placebo approach. All groups received clinical treatments at a rate of 3 sessions per week for 4 weeks; in addition, the physical therapy program was continued on other days for all groups. Isokinetic trunk flexor strength was measured before treatment and 4 weeks after treatment as in each measurement, fatigue protocol was designed, and the trunk flexor strength was measured before fatigue test while the trunk flexor resistance to fatigue was measured after fatigue test. After 4 weeks, pre-and post-fatigue trunk flexor strengths in both laser groups were significantly increased compared to pre-and post-fatigue trunk flexor strength in the placebo group, respectively, and there was no significant difference between the two laser groups. Photobiomodulation approaches enhance trunk flexor response to exercise after incisional hernia repair. This enhancement leads to greater strength and more fatigue resistance for the trunk flexors in photobiomodulation groups compared to the placebo group and no difference between the two photobiomodulation effects.

Laser treatment of synovial inflammatory process in experimentally induced microcrystalline arthritis in Wistar rats

The presence of intra-articular crystals is detected in different articular pathologies of acute or chronic nature. The aim of this work was to analyze the action of the indium gallium aluminum and phosphorus (InGaAlP) (λ = 670 nm) laser on the synovial membrane present in the knee joint in experimentally induced microcrystalline arthritis in male adult Wistar rats. The animals were divided into three experimental groups (n = 24): control (A), experimentally induced arthritis (B), experimentally induced arthritis+InGaAlP laser therapy (C). The laser treatment was made daily in the patellar region of the right knee after 48 h of the experimental induction. After 7, 14, and 21 days of therapy, the rats were euthanized and the right knees were removed and processed for histomorphometric, immunohistochemical, ultrastructural, and biochemical investigation of the synovium. The number of granulocytes on the 14th and 21st days was higher in B and lower in C and, lastly, in A. The number of fibroblasts on the 14th and 21st days was similar between A and C and below B. The number of blood vessels on the 21st day was higher in B than in the other groups. The positive number of cells for the TUNEL test was higher on the 14th and 21st days in B compared to the others. The percentage of tissue area occupied by birefringent collagen fibers was higher in B on the 21st day than in the others. The ultrastructure of cells showed fibroblast-like morphology in all groups and periods evaluated. The quantification of glycosaminoglycans did not present significant differences between the groups in all the experimental periods. The amount of hydroxyproline was higher in B compared to the other groups on the 14th and 21st days. The content of non-collagen proteins was higher in B on the 21st day in relation to the other groups. Quantification of TNF-α on the 21st day was higher in A and B than in C. For TGF-β on the 21st day, groups B and C presented similar and higher values than A. For MMP-13, groups A and B presented data similar to and above C. In relation to ADAMT-S4, on the 21st day, groups B and C presented data similar to and lower than A. InGaAlP-670 nm therapy reduced the inflammatory process and tissue injuries of the synovial membrane in comparison to the untreated group, indicating its potential utilization in clinical studies aiming in the recovery of acute arthritis in patients.

The validity of laser fluorescence (LF) and near-infrared reflection (NIRR) in detecting early proximal cavities

OBJECTIVES

Diagnosing cavitated proximal lesions is important for therapeutic decisions. This clinical study aimed to determine the validity of laser fluorescence (LF) and near-infrared reflection (NIRR) techniques for detecting early proximal cavities.

MATERIALS AND METHODS

The study included 43 proximal surfaces in 15 females who had limited radiolucent lesions in their bitewing radiographs. The approximal areas of interest were assessed by DIAGNOdent Pen (LF) and the Proxi interchangeable head of VistaCam iX intraoral camera (NIRR). Finally, orthodontic separators were placed in the contact points to provide enough space between the teeth. The sensitivity, specificity, and accuracy of diagnosing cavitated proximal surfaces were calculated for LF and NIRR against direct visual and tactile examination as the reference standard.

RESULTS

On the basis of the reference standard, 34 surfaces (79.1%) were not cavitated, whereas 9 surfaces (20.9%) were cavitated and in need of restoration. The sensitivity, specificity, and accuracy of LF were 44.4%, 61.8%, and 58%, and those of NIRR were 88.9%, 14.7%, and 30%, respectively.

CONCLUSIONS

The VistaCam iX Proxi was more sensitive and DIAGNOdent Pen was more specific in detection of proximal cavities. However, none of the techniques was accurate enough to be recommended as a sole approach for proximal caries detection.

CLINICAL RELEVANCE

LF showed an overall superior diagnostic performance to NIRR for diagnosing proximal cavitation in permanent posterior teeth. Within the limitations of this study, neither VistaCam iX Proxi nor DIAGNOdent Pen could be considered a suitable device for diagnosing proximal cavities.

Effect of Er:YAG laser radiation on pull-out fracture load of esthetic posts luted to root canal dentin with various resin cements

BACKGROUND

This study investigated the influence of erbium-doped: yttrium aluminum garnet (Er:YAG) laser on the pull-out fracture load of fiber-reinforced composite (FRC) posts luted to dentin with different resin cements.

MATERIALS AND METHODS

In this in vitro experimental study, 90 premolars were endodontically treated. The post spaces were prepared, and the teeth were divided into three groups dependent on the cement applied for luting FRC posts: Group 1: An etch-and-rinse system, Group 2: A self-etch cement, and Group 3: A self-adhesive cement. After 6 months' storage and thermocycling, each group was divided into three subgroups (n = 10) according to the treatment applied for removing the posts; subgroup 1: Control, subgroup 2: Treatment with Er:YAG laser at 250 mJ, 20 Hz, and subgroup 3: Treatment by Er:YAG laser at 300 mJ, 10 Hz. The pull-out load was recorded in Newton. The data were analyzed by two-way ANOVA at P < 0.05.

RESULTS

The fracture load was significantly affected by the cementation group (P = 0.005) and treatment subgroup (P = 0.008). The pull-out load of self-etch cement was significantly greater than that of the self-adhesive and etch-and-rinse systems (P < 0.05). Treatment with Er:YAG laser caused a significant reduction in pull-out load of FRC posts (P < 0.05).

CONCLUSION

The fracture load of fiber posts is influenced by the type of cement and treatment applied. Post removal would be less challenging when using a self-adhesive or conventional etch-and-rinse cement or using Er:YAG laser at the FRC-resin interface.

Efficacy of photobiomodulation in the management of tinnitus: A systematic review of randomized control trials

There is a controversy in regards to the efficacy of photobiomodulation (PBM) in the management of tinnitus. The aim was to systematically review randomized controlled trials (RCTs) that assessed the efficacy of PBM (low-level laser therapy) in the management of tinnitus. The focused question was "Is PBM effective in the management of tinnitus?". Indexed databases were searched up to and including June 2020 using different combinations of the following key words: (a) laser; (b) diode; (c) low-level laser therapy; (d) photobiomodulation; (e) tinnitus; (f) medium-level laser; (g) photo-biomodulation; and (h) low-power laser; and RCTs performed on humans were included. Letters to the editor; case reports/series; commentaries; experimental studies and historic reviews were excluded. The risk of bias was assessed using the modified cochrane collaboration tool. The format of the current systematic review was personalized to summarize the appropriate information. Ten RCTs (2 single-blinded and 8 double-blinded) were included. One study reported 30% and 100% resolution of tinnitus using diode and Neodymium-doped Yttrium Aluminum Garnet lasers; respectively. One study reported that PBM was effective in relieving tinnitus for up to 3 months. Eight studies reported that PBM was ineffective in the management of chronic tinnitus. The risk of bias was high; medium and low in 4; 5 and 1 studies; respectively. The effectiveness of PBM in the management of tinnitus remains debatable. Further power-adjusted and well-designed RCTs with long-term follow-up are needed.

Adherence of head and neck cancer patients to laser photobiomodulation in a public health service: Pilot study

OBJECTIVE

The aim of this study was to evaluate the adherence of patients with head and neck cancer who underwent radiotherapy or radio-chemotherapy combined to the preventive laser photobiomodulation protocol in a public health service.

MATERIALS AND METHODS

This was a cross-sectional study, whose population sample included patients with malignant head and neck neoplasms. Thirty head and neck cancer patients undergoing cancer treatment, were examined and interviewed through a record of signs and symptoms of oral mucositis (OM) and adherence to the preventive laser photobiomodulation protocol, that began in the first session of radiotherapy, and included the laser application three times a week during the 3-week period. The collected data were documented, and the descriptive and inferential statistics were performed with a significance level of p < 0.05.

RESULTS

It was observed that 66.6% of patients developed OM. There was a predominance of degrees I and II, with 36.8% and 31.6%, respectively. A total of fifteen patients (50%) missed one or more laser photobiomodulation sessions. A positive association was found between patients who missed at least two laser photobiomodulation sessions with the development of OM degrees III (p < 0.05).

CONCLUSIONS

There was moderate adherence of patients with head and neck cancer to the laser photobiomodulation protocol and the development of more severe degrees of OM was related to individuals that didn't attend scheduled sessions.

Network meta-analysis of the treatment efficacy of different lasers for peri-implantitis

The aim of this study was comparing different lasers with conventional non-surgical treatment (CNT) for the management of peri-implantitis, regarding probing depth (PD), plaque index (PLI), clinical attachment level (CAL), and sulcus bleeding index (SBI). Randomized controlled trials (RCTs) on different lasers and CNT for peri-implantitis were searched. Pairwise and network meta-analyses were performed to analyze the PD, PLI, CAL, and SBI outcomes. The risk of bias, evidence quality, statistical heterogeneity, and ranking probability were also evaluated. Eleven studies were included in this study, involving three types of lasers. Diode + CNT had significantly superior efficacy to CNT alone, regarding PD reduction, while Er:YAG + CNT had significantly superior efficacy than CNT in terms of the PLI, CAL, and SBI. The highest probability of being most effective for PD was diode + CNT (49%), while Er:YAG + CNT had the highest probability of improving the PLI, CAL, and SBI (66%, 53%, and 79%, respectively). Diode + CNT was significantly superior for PD management in peri-implantitis compared with CNT alone, while Er:YAG + CNT significantly improved the PLI, CAL, and SBI. Therefore, Er:YAG + CNT might be recommended methods considered for management of peri-implantitis.

Diode Laser-Can It Replace the Electrical Current Used in Endoscopic Submucosal Dissection?

Background/Aims

A new medical fiber-guided diode laser system (FDLS) is expected to offer high-precision cutting with simultaneous hemostasis. Thus, this study aimed to evaluate the feasibility of using the 1,940-nm FDLS to perform endoscopic submucosal dissection (ESD) in the gastrointestinal tract of an animal model.

Methods

In this prospective animal pilot study, gastric and colorectal ESD using the FDLS was performed in ex vivo and in vivo porcine models. The completeness of en bloc resection, the procedure time, intraprocedural bleeding, histological injuries to the muscularis propria (MP) layer, and perforation were assessed.

Results

The en bloc resection and perforation rates in the ex vivo study were 100% (10/10) and 10% (1/10), respectively; those in the in vivo study were 100% (4/4) and 0% for gastric ESD and 100% (4/4) and 25% (1/4) for rectal ESD, respectively. Deep MP layer injuries tended to occur more frequently in the rectal than in the gastric ESD cases, and no intraprocedural bleeding occurred in either group.

Conclusions

The 1,940-nm FDLS was capable of yielding high en bloc resection rates without intraprocedural bleeding during gastric and colorectal ESD in animal models.

Flow Cytometry as an Important Tool in Proteomic Profiling

Flow cytometry enables the simultaneous detection of multiple surface and intracellular antigens for proteomic profiling of cells. This allows characterization and identification of specific cell subtypes within a heterogeneous population and is usually called immunophenotyping. Antigen-specific antibodies, conjugated to various fluorophores, are incubated with the sample to identify each marker. Fluorescent light of various wavelengths can be separated, detected, and converted into a digital signal in a flow cytometer. Here we describe an eight-color experiment to identify key peripheral blood cell types; however, this technique can be expanded to detect more than 30 parameters simultaneously.

Direct Pulp Capping With ProRoot MTA Alone and in Combination With Er:YAG Laser Irradiation: A Clinical Trial

Background: Due to the complications of root canal treatment, conservative modalities to preserve pulp vitality are favorable. Direct pulp capping (DPC) refers to the coverage of the pulp tissue exposed by a biocompatible agent that can improve the prognosis of the tooth by 44% to 95%. Some recent studies have reported more predictable results (a success rate of about 90%) for DPC with laser and regenerative materials such as mineral trioxide aggregate (MTA). This study aimed to clinically compare DPC with ProRoot MTA alone and in combination with Er:YAG (erbium-doped yttrium aluminium garnet) laser irradiation (2940 nm). Methods: This clinical trial was conducted on 26 patients with a mean age of 29 years (in the range of 17 to 46 years) who required DPC following pulp exposure during deep caries removal. The teeth were divided into two groups. In the control group, the teeth underwent DPC with ProRoot MTA while in the test group, the teeth were first irradiated with a 2940 nm Er:YAG laser and then underwent DPC with ProRoot MTA. The patients were recalled at one, 3 and 6 months for the follow-up (clinical and radiographic examinations). The data were analyzed using Fisher exact test. Results: The success rate was 75% in the laser group and 93% in the control group. The groups were not significantly different (P>0.05). Conclusion: No significant difference was found in terms of the success rate of DPC with ProRoot MTA alone and in combination with Er:YAG laser irradiation.

[Treatment of nevus of Ota and Ito and epidermal nevus syndrome]

Nevus of Ota, nevus of Ito and nevus of Hori are special melanocytic nevi that have a slate-brown or blue/grey coloring. They are pigmented disorders characterized by its heterotopic melanocytic dermal location and by blue/brown unilateral and sometimes bilateral facial patch in case of nevus of Ota, and in the supraclavicular, scapular, and deltoid region in case of nevus of Ito. It is more common in patients with Asian and dark-skinned ethnic backgrounds. Histologically, elongated, dendritic melanocytes are seen scattered mainly throughout the upper third of reticular dermis. An acquired variant is called Hori's nevus with more bilateral facial distribution, similar to melasma. Dermal melanocytosis can also occur elsewhere on the body, including inside the mouth. Despite its benign nature, patients frequently seek therapy because of its facial involvement. QS lasers are used effectively to treat these lesions. The number of treatment sessions correlates with clinical improvement. Post laser hypo- and hyperpigmentation are common side effects mainly affecting patients with darker skin.

Influence of the laser pulse shape in the treatment of stones in the upper urinary tract

PURPOSE

Urinary stones can be successfully treated using a Holmium: Yttrium-Aluminum-Garnet (Ho: YAG) laser. Regarding success rates, laser pulse energy, frequency, and pulse width are well-known contributing factors. Whether the pulse shape might be a further factor influencing the laser efficiency is unclear. This study aimed to evaluate different modes of laser pulse shapes in a real-world setting.

MATERIALS AND METHODS

The Dornier Medilas® H Solvo (Weßling, Germany) was used in the treatment of ureter and kidney stones. Patients were randomized into standard pulse shape (SPS) and new pulse shape groups (NPS1; ureter) and (NPS2; kidney pelvis), depending on the stone localization. The primary endpoint was laser efficiency defined as mm³ stone destruction per overall operating time. Secondary endpoints encompassed number of stone recoveries and stone-free rate.

RESULTS

Altogether 145 patients (24 SPS vs. 32 NPS1; 51 SPS vs. 38 NPS2) were included. No differences in sex, age, body mass index, stone localization and stone composition were found, except for preoperative stone size (133±95 [SPS] vs. 197±139 [NPS1] mm³; p=0.023) and (348±298 [SPS] vs. 525±429 [NPS2] mm³; p=0.042). Regarding the primary endpoint, a significant increase in laser efficiency could be detected for the NPS1 and NPS2 groups compared to the SPS groups (39.9±44.9 vs. 28.8±30.2 and 51.7±61.3 vs. 22.4±24.2 mm³/min [mean±standard deviation]). No statistically significant differences were found for secondary endpoints and perioperative complication rates.

CONCLUSIONS

Efficiency of the Ho: YAG laser can be positively influenced by different pulse shapes. This adds the variable of individualized intraoperative decision making.

[Observation and analysis of lens turbidity lesion induced by low intensity 635 nm laser radiation]

Objective: To study the characteristics of the lens turbidity after long-term exposure to low intensity 635nm laser. Methods: Cluster sampling method was adopted to select 812 employees in a laser leveler workshop in a city of Guangdong Province from January 2014 to December 2018. They were divided into the control group, diffuse reflection (DR) group and direct vision (DV) group for retrospective observation and analysis of lens turbidity. The laser irradiation intensity of each group was investigated, the position and shape of lens opacity were analyzed, and the influencing factors were statistically analyzed with the repeated measurement data of dichotomy. Results: The laser irradiance and radiant exposure of DV group were between 0.72×10(-4) and 9.92×10(-4) mW/cm(2) and between 2.61×10(-2) and 1.53 J/cm(2), respectively. The subjects were mainly diagnosed with lens turbidity lesion, especially for the DV group. Most of lesions occurred in the pole and periphery of the anterior cortex. The lesions exhibited multipoint patterns with greyish white color. The turbidity rates in DV group (before work and work for 1, 2, 3 years) were 0%, 1.99% (8/402) , 4.98% (20/402) and 6.72% (27/402) , respectively, in the order of observation points. The statistical analysis of single factor effect showed that the turbidity rate was higher in DV group and higher in the second year in the DV group (P<0.01) . Multi-factor analysis of the laser effect on the lens showed that the main effect between groups, between the observation point were statistically significant (P<0.05) , but no statistical significance in the interaction between group×observation points (P>0.05) . Conclusion: Lens turbidity lesion can be caused by long-term exposure to low intensity 635 nm laser, so the product safety classification should be strictly strengthened. It is necessary to strengthen the protection of laser photochemical damage in the production process.

Photobiomodulation Therapy in the Proliferation and Differentiation of Human Umbilical Cord Mesenchymal Stem Cells: An In Vitro Study

Introduction: Since photobiomodulation therapy (PBMT) favors in vitro mesenchymal stem cell (MSC) preconditioning before MSC transplantation, increasing the proliferation of these cells without molecular injuries by conserving their characteristics, in the present in vitro study we analyzed the effect of PBMT on the proliferation and osteogenic differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs). Methods: Irradiation with an InGaAIP Laser (660 nm, 10 mW, 2.5 J/cm² , 0.08 cm² spot size, and 10 s) was carried out. The cells were divided into four groups: CONTROL [cells grown in Dulbecco's Modified Eagle Medium (DMEM)], OSTEO (cells grown in an osteogenic medium); PBMT (cells grown in DMEM+PBMT), and OSTEO+PBMT (cells grown in an osteogenic medium plus PBMT). The cell proliferation curve was obtained over periods of 24, 48 and 72 hours using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Osteogenic differentiation was analyzed by the formation of calcium nodules over periods of 7, 14 and 21 days. Morphometric analysis was performed to quantify the total area of nodular calcification. Results: The highest cell proliferation and cell differentiation occurred in the OSTEO+PBMT group, followed by the PBMT, OSTEO and CONTROL groups respectively, at the observed times (P <0.05). Conclusion: PBMT enhanced the osteogenic proliferation and the differentiation of hUCMSCs during the periods tested, without causing damage to the cells and preserving their specific characteristics, a fact that may represent an innovative pretreatment in the application of stem cells.

Efficacy of Er,Cr Laser incision Corticotomy in Rapid Maxillary Canine Retraction: A Split-Mouth Randomized Clinical Trial

Introduction: This study sought to evaluate the efficacy of lasercision corticotomy for the acceleration of canine movement. Our secondary objectives were assessing the canine rotation, the rate of anchorage control, the level of pain, and the gingival index (GI). Methods: Twelve orthodontic patients (9 females and 3 males) referring to the School of Dentistry and one dental clinic from May 2019 to September 2019 participated in this split-mouth randomized clinical trial. The allocation of the test and control sides was performed by flipping a coin. The mean age of patients was 18.91±3.87 years (range 15-30 years). The treatment plan included maxillary first premolar extraction. Following the initial leveling and alignment phase, an initial impression was made. Corticotomy was carried out with the erbium, chromium-doped yttrium scandium gallium garnet (Er, Cr: YSGG) laser (3.5 W, 30 Hz, 40% air, 80% water) in one maxillary quadrant (the laser side). Canine retraction was immediately initiated following surgery using nickel-titanium closed-coil springs with 150 g force. The impression was repeated 1 month after the onset of retraction. The casts were scanned, and the distance between the canine cusp tip and the rugae line was measured to quantify the amount of anteroposterior canine movement. The molar anchorage control was also evaluated by measuring the distance between the mesial contact of the permanent first molar and the rugae line. Gingival health was evaluated using the GI. The modified McGill pain questionnaire was used to assess the level of patients' pain. Results: Lasercision corticotomy accelerated canine retraction with no adverse effect on gingival health. Anchorage loss in the posterior teeth and pain scores were not significantly different between the control and laser sides. Conclusion: Laser corticotomy can effectively accelerate canine retraction with no complications or discomfort for the patients.

[Effectiveness and safety of holmium laser therapy via flexible bronchoscopy in 40 children with tracheobronchial tuberculosis]

Objective: To explore the effectiveness and safety of holmium laser treatment via flexible bronchoscopy in children with tracheobronchial tuberculosis (TBTB). Methods: The clinical data of 40 children with TBTB admitted in Qilu Children's Hospital of Shandong University from February 2016 to June 2019 were retrospectively analyzed. According to the treatment approach, they were divided into conventional treatment group (20 cases) and holmium laser treatment group (20 cases). The sex, age, course of disease and lesion location before treatment, and the time till relief of atelectasis and airway obstruction after treatment were compared between the two groups with t test and χ² test. Results: Among the 40 cases, 24 were males and 16 females, and 35 had lymph node fistula (87.5%) and 5 had granulation proliferation (12.5%). There was no statistically significamt difference between the conventional group and laser group in sex (male ratio: 50%（10/20） vs. 75%（15/20）, χ²=2.66, P=0.10), age （(3.2±2.2） years vs. （2.2±1.8） years, t=1.41, P=0.16), course of disease (<1 month ratio: 30%（6/20） vs. 35%（7/20）, χ²=0.11, P=0.73), lesion location (single lesion ratio： 45%（9/20） vs. 60%(12/20), χ²=0.90, P=0.34). The effectiveness was evaluated after 3 months, and the total effective rate were 100% in laser group and 40% in conventional group, the difference was significant (χ²=25.34, P<0.01). No serious adverse events occurred in the two groups during the observational period. Conclusions: Holmium laser treatment via bronchoscopy is an effective way to remove the tuberculosis foci in the trachea, which can reduce the incidence of further related complications, and could be applied in clinical approach.

Current use of thulium lasers in endourology and future perspectives

Thulium lasers operate at wavelengths between1940-2013 nm either in a continuous wave or in a pulsed mode, which enables smooth incisions with fast vaporization or effective laser lithotripsy for urolithiasis. Thulium laser enucleation is a minimally invasive and size-independent treatment for benign prostatic hyperplasia (BPH) with excellent long-term results. Since its introduction, several modifications in the technology and surgical techniques have been proposed such as vaporesection, vaporization and enucleation with regard to BPH treatment. Recent developments in the thulium laser technology include the introduction of a super pulsed thulium fiberlaser.  This technique delivers the laser energy through anactive fiber with an absorption maximum in water at awavelength of 1940 μm. Preclinical studies showed asignificantly higher stone fragmentation rate in differentex vivo models compared to the Ho:YAG laser. Another innovative thulium laser that works, as a hybrid laser has yet not been tested clinically, however, will soon be introduced. With the introduction of both new thulium lasers as novel devices, the armamentarium in the field of endourology for lithotripsy and enucleation increases. We here present different thulium lasers and surgical techniques that are possible to perform with each device including the reasons and advantages of each modification.

Management of peri-implantitis using a diode laser (810 nm) vs conventional treatment: a systematic review

The purpose of this study was to systematically assess clinical studies on the effect of using a diode laser in the treatment of peri-implantitis. Study question was "In patients with peri-implantitis around functional dental implants, can treatment by a diode Laser (810 nm) versus conventional treatment be effective in reducing the probing depth?". The study included only randomized controlled clinical trials that involved patients with peri-implantitis. Included articles evaluated a diode laser (810 nm) used as monotherapy or as adjuvant therapy in the non-surgical treatment while their control group received conventional methods of treatment for peri-implantitis. Studies that involved other types of laser treatment options, surgical therapy, photodynamic therapy, case series, or case reports were excluded. Three electronic databases were searched for published articles from 2010 to 2018: PubMed/Medline, Cochrane, and Web of Science. The references were manually hand searched for relevant articles. The search initially identified 44 studies, which were filtered to yield a total of 3 eligible studies. All included studies compared laser treatment by a diode laser (810 nm) to conventional therapy by mechanical debridement for a follow-up period ranging from 6 months to 1 year, and risk of bias was assessed for each of the three included studies. A qualitative analysis of the three studies was conducted. This systematic review could not support the usage of a diode laser in the treatment of peri-implantitis. To confirm this assumption, more clinical trials with long-term follow-up periods are recommended.