Low-level laser therapy and myofacial pain dysfunction syndrome: a randomized controlled clinical trial

Myofacial pain dysfunction syndrome (MPDS) is the most common reason for pain and limited function of the masticatory system. The effects of low-level lasers (LLLs) for controlling the discomfort of patients are investigated frequently. However, the aim of this study was to evaluate the efficacy of a particular source producing 660 nm and 890 nm wavelengths that was recommended to reduce of the pain in the masticatory muscles. This was a double-blind and placebo-controlled trial. Sixteen MPDS patients were randomly divided into two groups. For the laser group, two diode laser probes (660 nm (nanometers), 6.2 J/cm², 6 min, continuous wave, and 890 nm, 1 J/cm² (joules per square centimetre), 10 min, 1,500 Hz (Hertz)) were used on the painful muscles. For the control group, the treatment was similar, but the patients were not irradiated. Treatment was given twice a week for 3 weeks. The amount of patient pain was recorded at four time periods (before and immediately after treatment, 1 week after, and on the day of complete pain relief). A visual analog scale (VAS) was selected as the method of pain measurement. Repeated-measures analysis of variance (ANOVA), the t-test and the paired t-test were used to analyze the data. In each group the reduction of pain before and after the treatment was meaningful, but, between the two groups, low-level laser therapy (LLLT) was more effective (P = 0.031) According to this study, this type of LLLT was the effective treatment for pain reduction in MPDS patients.     

Colonoscopy — how difficult,how painful?

Colonoscopy is sometimes painful for the patient and often difficult for the endoscopist, but it is hard to predict how difficult or painful the examination will be. The purpose of this study was to identify factors that influence difficulty and pain during colonoscopy.Some 1,284 consecutive patients undergoing office colonoscopy by three endoscopists were prospectively studied. A standard questionnaire was completed by the nursing staff, who assessed the degree of difficulty and pain associated with each exam on a four-point scale.There were 682 men and 551 women (sex not recorded in 51). There was no pain in 27%, mild pain in 39%, moderate pain in 25%, and severe pain in 9%. There was no difficulty in 25%, mild difficulty in 33%, moderate difficulty in 28%, and severe difficulty in 14%. Colonoscopy was significantly easier (P<0.001, chi square) and less painful (P<0.001, chi square) in patients after sigmoidectomy. It was more painful after hysterectomy (P<0.05, chi square) and more difficult and painful in women than in men (P<0.01, chi square). There were significant differences between endoscopists in the assessment of pain associated with colonoscopy.Most colonoscopies are associated with little or no pain (66%) and are easy or only mildly difficult to perform (58%). Patients who have had sigmoid resection are especially easy and painless to examine while women, especially after hysterectomy, are at higher risk of having a painful experience. Colonoscopy technique can influence the amount of pain experienced by the patient.     

Effects of super-pulsed Nd-YAG laser on arterial tissue: comparison with continuous wave

The effects of a super-pulsed Nd-YAG laser at 1.32 μm wavelength on normal or atherosclerotic human arterial tissue were evaluated and compared with those obtained with continuous wave. One joule per pulse was delivered through a 0.2 mm optical fibre with a pulse width of 10 ms at 10 Hz (super-pulse), or 10 W (10 J) were delivered at continuous wave in saline or blood. Ten joules were delivered with super-pulse or continuous wave for each tissue specimen. The aortic specimens were lased either by continuous wave or super-pulse. At super-pulse mode, ablation efficiency (mm³ J⁻¹) was 0.0149±0.0044 for normal tissue in saline, 0.0148±0.0043 for atheroma in saline, 0.0138±0.0062 for normal tissue in blood, and 0.0146±0.0049 for atheroma in blood. There was no significant difference between the groups. At continuous wave mode, ablation efficiency was 0.0507±0.0299 for atheroma in blood (p<0.001 vs super-pulse). However, extensive charring was observed with continuous wave lasing (41% with continuous against 14% with pulsed mode,p<0.001). Heavily calcified plaques were also ablated at 1.5 J per pulse and 15 W (continuous wave), resulting in extensive charring with continuous wave (77% vs 18% with super-pulse,p<0.01). In conclusion, at super-pulse mode, 1.32 μm Nd-YAG laser has neither the selectivity for atheroma nor influence of blood, thermal injury induced by super-pulse is less than that induced by continuous wave (cw), calcified plaques can be ablated by super-pulse, and super-pulsed Nd-YAG laser angioplasty is safer to use than continuous wave.     

Acute response of the arterial wall to pulsed laser irradiation

This study was designed to examine the acute response of normal arterial wall to pulsed laser irradiation. Irradiation with an Excimer or a Holmium YAG laser was performed in 15 normal iliac sites of 8 male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mj/mm²/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 μm, 3.5 Hz, 400 mj/ pulse, 250 μsec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The mean luminal diameter increased similarly from 2.01 ± 0.29 to 2.46 ± 0.27 mm (P < 0.0005) and from 2.09 ± 0.53 to 2.45 ± 0.30 mm (P < 0.005) after excimer and Ho:YAG laser irradiation, respectively. Perforation occurred in 3 of 15 Ho:YAG irradiated sites and 0 of 15 excimer laser irradiated sites. The sites irradiated with excimer or Ho:YAG laser had similar histologic features, consisting of shedding of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with the Ho:YAG laser (P<0.05). Irradiation with excimer or Ho:YAG laser of normal arteries results in: (1) vasodilation of the irradiated artery; (2) localized mechanical vascular injury, and (3) Ho:YAG laser induces more severe damage to the arterial wall than excimer. © 1993 Wiley-Liss, Inc.     

Effects of Nd:Yag laser irradiation on osteoblast cell cultures

The application of Nd:YAG lasers in endodontics has been explored by many investigators for different purposes. The aim of this in vitro study is to evaluate the effects of Nd:YAG laser on osteoblast cell cultures. A 1,064 nm Nd:YAG laser was used to irradiate human osteoblast-like cells (Saos-2) in noncontact mode for 10 s with different energy settings. The settings varied were pulse energy (20–120 mJ), pulse repetition rate (10–30 Hz), and power output (0.2–3.6 W). He–Ne, the aiming beam of Nd:YAG laser, was used in noncontact mode for 10 s. After 7-, 14-, and 21-day incubation period, cell viability and proliferation were evaluated with methylthiazoletetrazolium (MTT) colorometric method. The comparison of average MTT values gave no statistically significant difference between 20 mJ, 10 Hz, He–Ne, and control (p<0.05). The differences between all other groups were significant (p<0.05). Increase in the pulse energy, pulse repetition rate, and power output has a negative effect on the cell viability and proliferation.     

A Randomized Controlled Trial Comparing Laser Intra-Hemorrhoidal Coagulation and Milligan–Morgan Hemorrhoidectomy

Purpose: To compare laser intra-hemorrhoidal coagulation with Milligan–Morgan (MM) hemorrhoidectomy. Method: Patients with symptomatic grade II or III internal hemorrhoids according to the Goligher's classification (refractory to medical treatment) were enrolled in this double-blinded randomized controlled trial study. In the laser group, hemorrhoidal columns were coagulated using a 980-nanometer (nm) radial laser emitting fiber (three, 15-W pulses of 1.2 s each, with 0.6-s intervals). Operative time, postoperative pain and complications, and recovery or resolution of symptoms were measured. Patients were followed up for at least one year for evaluating healing, resolution of symptoms, and late complications. Results: Postoperative pain scores (at 12, 18, and 24 hr after surgery) were significantly lower in the laser group compared with the MM group (p <.01). The operative time and intra-operative blood loss were more in the MM group (p <.001). The administration of analgesics was significantly reduced in the laser group (p <.05). Two patients in the laser group were presented with thrombosis of external hemorrhoid 7–10 days after the procedure, which was resolved with medical treatment, but no patients in the MM group developed hemorrhoidal thrombosis (p >.05). One-year follow-up showed comparable results in terms of the resolution of symptoms and sustainable cure. Conclusions: Intra-hemorrhoidal coagulation with 980-nm diode laser reduces postoperative pain, intra-operative bleeding, and administered analgesics with a comparable resolution rate of hemorrhoid symptoms. However, for the patients who experience complications, such as hemorrhoidal thrombosis, the overall pain may be equivalent to or even worse than conventional hemorrhoidectomy.     

755nm翠绿宝石激光联合800nm半导体激光治疗腰骶部多毛疗效分析

目的:回顾性分析755nm翠绿宝石激光联合800nm半导体激光治疗腰骶部多毛的临床疗效和安全性。方法:收集笔者医院2017年1月1日-2018年6月30日收治的100例腰骶部多毛患者病例资料,其中50例患者为单纯755nm翠绿宝石激光治疗;50例患者为755nm翠绿宝石激光联合800nm半导体激光治疗。分析两组患者的治疗效果、不良反应发生情况及对治疗效果的满意度。结果:相较于单纯755nm激光治疗,755nm翠绿宝石激光联合800nm半导体激光脱毛的有效率和治愈率显著高于755nm治疗组,两组比较有统计学意义(P<0.05);组间的VAS(视觉模拟评分法)疼痛评分比较,差异无统计学意义(P>0.05),但联合治疗组发生疼痛的次数显著低于单一治疗组(P<0.05);单纯治疗组出现2例色素沉着斑,联合治疗组无色素沉着斑出现,两组比较差异无统计学意义(P>0.05),两组均未出现色素减退斑及瘢痕;联合治疗组患者的总满意率显著高于单一治疗组(P<0.05)。结论:755nm翠绿宝石激光联合800nm半导体激光治疗腰骶部多毛临床疗效明显,安全性良好,疼痛感轻,值得广泛应用。     

Vibrations produced during erbium:yttrium–aluminum–garnet laser irradiation

The purpose of this study was to evaluate vibrations induced by an erbium:yttrium–aluminum–garnet (Er:YAG) laser in the non-contact mode and compare the vibrations with different pulse durations and energy parameters. The experiment was conducted on an extracted tooth built up in silicone impression material. The vibrations were measured by piezoelectric accelerometer for a super-short pulse (SSP), a very short pulse (VSP), and a short pulse (SP) at a frequency of 5 Hz for 1 s. For VSP and SP, the energy parameters tested were 200 mJ, 300 mJ, and 400 mJ. Measurements were performed 15 times for each individual irradiation energy level. The highest values of vibrations were measured for SP (0.160 ± 0.04 m/s²), and the lowest were measured for VSP mode at the energy parameter 200 mJ (0.05 ± 0.02 m/s²). There was a statistically significant (P < 0.01) difference between the various laser pulse modes (SSP, VSP, SP) at different energy parameters. At energy levels of 300 mJ and 400 mJ, the least amount of vibration during cavity preparations with the non-contact Er:YAG laser was produced by SSP mode.     

High-power diode laser at 980 nm for the treatment of benign prostatic hyperplasia: ex vivo investigations on porcine kidneys and human cadaver prostates

Diode laser systems at 980 nm have been introduced for the treatment of lower-urinary-tract-symptoms (LUTS) suggestive of benign prostatic enlargement (BPE). However, the coagulation and vaporization properties are unknown. We therefore aimed to evaluate these properties in ex vivo models in comparison with the kalium-titanyl-phosphate-(KTP) laser. The diode laser treatment was applied to isolated, blood-perfused porcine kidneys and fresh human cadaver prostates (HCPs) at different generator settings. We performed histological examination to compare the depth of coagulation and vaporization. The diode laser showed larger ablation and coagulation characteristics than the KTP laser did. Ablation of the diode laser was found to be 1.79-times (120 W in porcine kidney, P < 0.0001) and 3.0–5 times (200 W in HCP, P < 0.0005) larger. The diode laser created a nine-times (120 W in porcine kidney, P < 0.0001) and seven-times (200 W in HCP, P < 0.0001) deeper necrosis zone. The diode laser vaporization was highly effective ex vivo. Owing to the laser’s deep coagulation zones, in vivo animal experiments are mandatory before the diode laser (980 nm) is applied in a clinical setting, so that damage to underlying structures is prevented.     

Effects of different setting of diode laser on the mRNA expression of growth factors and type I collagen of human gingival fibroblasts

The aim of this study was to analyze the influence of non-surgical applications of diode laser (940 nm) on the cell proliferation and mRNA expressions of type I collagen and growth factors in human gingival fibroblasts (GF). Gingival fibroblasts were isolated from human gingival connective tissue of systemically healthy individuals. Cells were treated with different laser parameters as follows; (1) Infected pocket setting (power: 2 W, pulse interval: 1 ms, pulse length: 1 ms, 20 s/cm²); (2) Perio-pocket setting (power: 1.5 W, pulse interval: 20 ms, pulse length: 20 ms, 20 s/cm²); and (3) Biostimulation setting (power: 0.3 W in continuous wave, 20 s/cm²). Proliferation of GF was evaluated after different laser applications using a real-time cell analyzer. Total RNA was isolated on day 2 and cDNA synthesis was performed. Type I collagen, insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-β) mRNA expressions were determined with quantitative RT-PCR. In a proliferation experiment, no significant differences were observed in the different laser applications when compared to the control group. Statistically significant increases in IGF, VEGF, and TGF-β mRNA expressions were noted in the laser groups when compared to the untreated control group (p < 0.05). A significant increase in collagen type I mRNA expression was noted in only biostimulation set-up of diode laser (p < 0.05). The results of this study demonstrate that non-surgical laser applications modulate behavior of gingival fibroblasts inducing growth factors mRNA expressions and these applications can be used to improve periodontal wound healing.     

Laser acupuncture therapy for pain and vague complaints in neurosurgery

The value of diode laser acupuncture for pain and other vague neurological complaints has been studied in chronic patients of head trauma and of cerebrovascular disease or neuralgia in head and neck regions. Gallium-Aluminium-Arsenide (Ga-Al-As) diode laser pain attenuator PANALAS-4000 manufactured by Japan Medical Laser Laboratory was used in the following specifications; wave length: 830 nm, power: 20-40 mW, frequency: 5-50 c.p.s., pulse duty: 0.9. The laser acupuncture was applied to some of the representative Chinese meridian points, local pain points and related nerves for 1 to 7 times in a week. It was given in 310 patients in our neurosurgical department. 175 of 227 patients who complained of pain and 12 of 39 patients who complained of numbness showed improvement within 24 hours, another 24 patients with pain and 16 patients with numbness showed improvement after 24 hours. No side effect was noticed. The duration of the effectiveness was about 2 or 3 days. It is very useful to apply the laser acupuncture for pain and vague complaints in neurosurgery.     

高能量激光联合针对性手功能训练治疗1-2级拇腕掌关节骨性关节炎的疗效观察

目的：观察高能量激光(high-intensity laser therapy,HILT)联合针对性手功能训练对1-2级拇腕掌关节(carpometacarpal,CMC)骨性关节炎(osteoarthritis,OA)的疼痛和侧捏力的影响。方法：选择2020年4月至2022年4月诊断为1-2级CMC OA的患者42例,年龄58~80(68.90±7.58)岁,均为女性,分为观察组和对照组,各21例。观察组患者接受HILT及手功能训练4周,对照组患者接受超短波治疗及矫形器制动4周。分别在干预前、干预后即刻以及干预后12周采用疼痛视觉模拟评分(visual analogue scale,VAS)比较疼痛程度,采用测力计观测拇指侧捏力并比较手指功能恢复情况。结果：干预后即刻及干预后12周,两组患者VAS及拇指侧捏力均较治疗前改善(P<0.05)。但与对照组比较,观察组VAS减轻程度更大(干预后立即t=3.37,P<0.05,干预后12周t=9.05,P<0.05),拇指侧捏力平均值高于对照组(干预后立即t=-2.55,P<0.05,干预后12周t=-9.51,P<0.05)。结论：高能量激光联合针对性手功能训练较传统方法更能有效改善1-2级拇腕掌关节骨关节炎的疼痛和侧捏力。     

Comparison of fibre tips for percutaneous interstitial laser photocoagulation

This paper seeks to optimize the parameters of interstitial laser photocoagulation, and clarify controversies regarding the effect of three types of fibre tips used in percutaneous application on the size of thermal lesions produced. Bare-cut, pre-charred and conical diffused tips of 600 μm silica core fibre were compared using a diode laser (805 nm) applied in vitro using fresh porcine livers. Continuous wave laser radiation at 805 nm was applied at 1.0, 1.5, 2.0 and 2.5 W for 5, 10 and 15 min. The sizes of the resultant lesion, cavity and char were measured and analysed using the method of analysis of variance for statistical significance. It is concluded that the fibre tips do not significantly affect the lesion size (p> 0.05). Conical fibre tips produced less char when applied for 10 min or more at 2–2.5 W. Laser power and irradiation time affect the lesion size significantly (p< 0.05), and the size of the lesion produced depends on both laser power and irradiation time, not merely on the total laser energy applied.     

Early surgical intervention alleviates sensory symptoms following acute traumatic central cord syndrome

Purpose

To investigate the impact of early versus delayed surgery on sensory abnormalities in acute traumatic central cord syndrome (ATCCS).

Methods

Pressure pain threshold (PPT), temporal summation (TS), conditioned pain modulation (CPM) and pain assessments were performed in 72 ATCCS patients (early vs. delayed surgical treatment: 32 vs. 40) and 72 healthy subjects in this ambispective cohort study. These examinations, along with mechanical detection threshold (MDT) and disabilities of arm, shoulder and hand (DASH), were assessed at 2 years postoperatively.

Results

Preoperatively, more delayed surgical patients had neuropathic pain below level compared with early surgical patients (P < 0.05). Both early and delayed surgical patients showed reduced PPT in common painful areas and increased TS, while reduced CPM only existed in the latter (P < 0.05). Reduced PPT in all tested areas, along with abnormalities in TS and CPM, was observed in patients with durations over 3 months. Both incidences and intensities of pain and pain sensitivities in common painful areas were reduced in both treatment groups postoperatively, but only early surgical treatment improved the CPM and TS. Follow-up analysis demonstrated a higher MDT and lower PPT in hand, greater TS, greater DASH, lower pain intensities and higher incidence of dissatisfaction involving sensory symptoms in delayed surgical patients than in early surgical patients (P < 0.05).

Conclusions

Central hypersensitivity may be involved in the persistence of sensory symptoms in ATCCS, and this augmented central processing may commence in the early stage. Early surgical treatment may reverse dysfunction of endogenous pain modulation, thus reducing the risk of central sensitization and alleviating sensory symptoms.

     

Prevention of cardiovascular diseases - a scientific dilemma

In order to improve the technique of transoesophageal atrial stimulation (TAS), the effects of body position, interelectrode spacing and electrode surface area on pacing threshold were assessed in two substudies. The effects of intra-oesophageal local anaesthesia and of two different pacing wave configurations on pacing threshold and discomfort were also assessed. Substudy I comprised 16 subjects (3 patients with a history of paroxysmal supraventricular tachycardia and 13 healthy volunteers) and substudy II comprised 16 healthy volunteers. TAS was performed using a hexapolar luminal prototype oesophageal electrode catheter. In substudy I bipolar pacing was performed in the semi-supine and left decubitus body positions for different pulse durations (20, 10, 6 and 2 ms), interelectrode pole distances (10 to 24 mm) and electrode pole surface areas (0.22 to 0.66 cm²). In substudy II TAS was performed with square wave and triangular waveform pulses after intra-oesophageal saline and lidocaine 20 mg/ml. These solutions were given in random order. Neither the interelectrode distance nor electrode surface areas had any significant influence on pacing thresholds. Stimulation thresholds were not affected by body position. Intra-oesophageal lidocaine did not affect the discomfort experienced. Peak pacing thresholds using a triangular waveform were significantly higher than thresholds using a square waveform (p &;lt; 0.001). The optimal pacing technique for TAS remains to be defined. The TAS-induced pain is probably not generated from the oesophageal mucous membrane. There is a significant difference in pacing thresholds between triangular and square waveforms.     

Optical properties of human articular tissue as implication for a selective laser application in arthroscopic surgery

Background and Objective: Optical density of normal and pathological hyaline cartilage, meniscus, and synovium is determined using native and laser-irradiated tissue samples in order to examine potentials for a selective laser ablation. Study Design/Materials and Methods: One hundred forty-four autopsy specimens were irradiated in a direct contact mode using a XeCl excimer laser (λ = 308 nm; 20 ns; 40 Hz; 40 ± 2.1 J/mm²; 800 μm fused silica fiber) and a continuous-wave Nd:YAG laser (λ = 1,064 nm; 1 s; 124 ± 5.4 W/mm²; 600 μm fused silica fiber). Transmission spectra were obtained by microspectrophotometry in a spectral range from 250 to 770 nm. Results: In the ultraviolet spectrum analyzed, optical density (OD) is calculated to 0.81 ± 0.05 for native hyaline cartilage, to 1.0 ± 0.07 for meniscal tissue, and to 0.68 ± 0.04 for synovium. With increasing wavelength the OD steadily decreases reaching mean values of 0.06 ± 0.01, 0.13 ± 0.03, and 0.15 ± 0.04 at 750 nm. Compared to normal tissue degeneration of cartilage and meniscus lead to a significant increase in OD with a maximum relative OD of 4.39 and 1.26, respectively (P <.001 and P <.01). In synovitis the OD increases with a maximum ratio of 1.45:1 (P <.01). Following Nd:YAG laser exposition the OD of the coagulated zone exceeded the value of native tissue by a factor of 9.71 for cartilage, 4.71 for meniscus, and 3.04 for synovium (P <.001). Excimer irradiation leads to a 3.38-fold increase in OD for cartilage, 2.23-fold for meniscal tissue, and 1.6-fold for synovium (P <.01). Conclusion: The results presented indicate that a preferential ablation of pathological tissue structures in articular surgery is possible by selecting laser systems with an appropriate spectral emission range. However, thermal laser tissue interaction may lead to severe alterations in optical properties reducing potentials of a preferential or selective laser application. © 1995 Wiley-Liss, Inc.     

Efficacy of Low Power Laser Therapy in Fibromyalgia: A Single-blind, Placebo-controlled Trial

Low energy lasers are widely used to treat a variety of musculoskeletal conditions including fibromyalgia, despite the lack of scientific evidence to support its efficacy. A randomised, single-blind, placebo-controlled study was conducted to evaluate the efficacy of low-energy laser therapy in 40 female patients with fibromyalgia. Patients with fibromyalgia were randomly allocated to active (Ga-As) laser or placebo laser treatment daily for two weeks except weekends. Both the laser and placebo laser groups were evaluated for the improvement in pain, number of tender points, skinfold tenderness, stiffness, sleep disturbance, fatigue, and muscular spasm. In both groups, significant improvements were achieved in all parameters (p<0.05) except sleep disturbance, fatigue and skinfold tenderness in the placebo laser group (p>0.05). It was found that there was no significant difference between the two groups with respect to all parameters before therapy whereas a significant difference was observed in parameters as pain, muscle spasm, morning stiffness and tender point numbers in favour of laser group after therapy (p<0.05). None of the participants reported any side effects. Our study suggests that laser therapy is effective on pain, muscle spasm, morning stiffness, and total tender point number in fibromyalgia and suggests that this therapy method is a safe and effective way of treatment in the cases with fibromyalgia. Paper received 29 March 2001; accepted after revision 10 July 2001.     

Ex vivo and in vivo investigations of the novel 1,470 nm diode laser for potential treatment of benign prostatic enlargement

Perioperative haemorrhage is still the major complication of transurethral resection of the prostate (TURP) for benign enlargement of the prostate. Photoselective vaporisation of the prostate (PVP) with the potassium–titanyl–phosphate (KTP) laser has been shown to achieve instant tissue ablation with excellent haemostatic properties. Our aim was to determine the tissue removal capacity, coagulation and haemostatic property of the novel 1,470 nm diode laser, ex vivo and in vivo. We evaluated two prototype diode laser systems at 1,470 nm in an ex vivo, isolated, blood-perfused, porcine kidney model (n = 5; 10 W–50 W) and in an in vivo investigation of beagle prostate (n = 4; 100 W) to assess vaporisation capacities and coagulation properties at different generator settings. The diode laser evaluation was compared with an 80 W KTP laser in the porcine model. After the laser treatment we performed a histological examination to compare the depth of coagulation and vaporisation. The diode laser system (50 W) showed significantly lower (P < 0.0001) capacities for tissue removal than the 80 W KTP laser (0.96 mm ± 0.17 mm and 5.93 mm ± 0.25 mm, respectively, P < 0.0001), while coagulation zones were significantly (P < 0.001) larger in diode laser-treated kidneys (3,39 mm ± 0.93 mm and 1.27 mm ± 0.13 mm, respectively). In vivo, the diode laser displayed rapid ablation of prostatic tissue with no intraoperative haemorrhage. Histological examination revealed coagulation zones of 2.30 mm (±0.26) at 100 W in the diode laser-treated prostates.     

Laser phototherapy effect on protein metabolism parameters of rat salivary glands

The aim of this study was to evaluate the effects of infrared diode laser phototherapy (LP) on tissues of the submandibular gland (SMG) and parotid gland (PG). Wistar rats were randomly divided into experimental (A and B) and control (C) groups. A diode laser, 808 nm wavelength, in continuous wave mode, was applied to the PG, SMG and sublingual gland in the experimental groups on two consecutive days. The doses were 4 J/cm² and 8 J/cm², and total energy was 7 J and 14 J, respectively. The power output (500 mW) and power density (277 mW/cm²) were the same for both experimental groups. In order to visualize the area irradiated by the infrared laser, we used a red pilot beam (650 nm) with 3 mW maximum power for the experimental groups. For the control group, the red pilot beam was the only device used. The SMG and PG were removed after 1 week of the first irradiation. Total protein concentration, amylase, peroxidase, catalase and lactate dehydrogenase assays were performed, as well as histological analysis. Statistical tests revealed significant increase in the total protein concentration for groups A and B in the parotid glands (P < 0.05). Based on the results of this study, LP altered the total protein concentration in rats’ parotid glands.     

Heat generation caused by ablation of restorative materials with an ultrashort pulse laser (USPL) system

Heat generation during the removal of dental restorative materials may lead to a temperature increase and cause painful sensations or damage dental tissues. The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an ultrashort pulse laser (USPL) system. A total of 225 specimens of phosphate cement (PC), ceramic (CE), and composite (C) were used, evaluating a thickness of 1 to 5 mm each. Ablation was performed with an Nd:YVO₄ laser at 1,064 nm, a pulse length of 8 ps, and a repetition rate of 500 kHz with a power of 6 W. Employing a scanner system, rectangular cavities of 1.5-mm edge length were generated. A temperature sensor was placed at the back of the specimens to record the temperature during the ablation process. All measurements were made employing a heat-conductive paste without any additional cooling or spray. Heat generation during laser ablation depended on the thickness of the restoration material (p < 0.05) with the highest values in the composite group (p < 0.05), showing an increase of up to 17 K. A time delay for temperature increase during the ablation process depending on the material thickness was observed in the PC and C group (p < 0.05) with highest values for cement (p < 0.05). Employing the USPL system for removal of restorative materials, heat generation has to be considered. Especially during laser ablation next to pulpal tissues, painful sensations might occur.