Journal of clinical laser medicine & surgery最新文献

Failure of apicectomies is generally attributed to dentine surface permeability as well as to the lack of an adequate marginal sealing of the retrofilling material, which allows the percolation of microorganisms and their products from the root canal system to the periodontal region, thus compromising periapical healing. The purpose of this study was to evaluate dentine and the marginal permeability after apicectomy and surface treatment with 9.6 micro m TEA CO(2) or Er:YAG 2.94 micro m laser irradiation. Sixty-five single rooted human endodontically treated teeth were divided into five experimental groups: group I (control), apicectomy with high speed bur; group II, similar procedure to that of group I, followed by dentinal surface treatment with 9.6 micro m CO(2) laser; group III, similar procedure to group I followed by dentinal surface treatment with Er:YAG laser 2.94 micro m; group IV, apicectomy and surface treatment with CO(2) 9.6 micro m laser; and group V, apicectomy and surface treatment with Er:YAG laser 2.94 micro m. The analysis of methylene blue dye infiltration through the dentinal surface and the retrofilling material demonstrated that the samples from the groups that were irradiated with the lasers showed significantly lower infiltration indexes than the ones from the control group. These results were compatible with the structural morphological changes evidenced through SEM analysis. Samples from groups II and IV (9.6 micro m CO(2)) showed clean smooth surfaces, fusion, and recrystallized dentine distributed homogeneously throughout the irradiated area sealing the dentinal tubules. Samples from groups III and V (Er:YAG 2.94 micro m) also presented clean surfaces, without smear layer, but roughly compatible to the ablationed dentine and without evidence of dentinal tubules. Through the conditions of this study, the Er:YAG 2.94 micro m and the 9.6 micro m CO(2) laser used for root canal resection and dentine surface treatment showed a reduction of permeability to methylene blue dye.

Objective: This investigation was done in order to find optimal indocyanine green (ICG) concentration and energy irradiance in laser vascular welding.

Background data: Many studies have shown that laser tissue welding with albumin solder/ICG may be an effective technique in surgical reconstruction. However, there are few reports regarding optimal laser settings and concentrations of ICG within the albumin solder in laser-assisted vascular anastomosis.

Materials and methods: Porcine carotid artery strips (n = 120) were welded in end-to-end by diode laser with 50% albumin solder of 0.01, 0.1, and 1.0 mM ICG at irradiance of 27.7, 56.7, and 76.9 W/cm(2), respectively. Temperature was measured by inserting thermocouples outside and inside the vessel. Tensile strength and histology were studied.

Results: Temperature and strength of the anastomosis significantly decreased (all p < 0.05) with increasing ICG concentration at 56.7 W/cm(2). Histological study showed minimal thermal injury limited to adventitia and no appreciable difference between all groups.

Conclusions: ICG concentration within solder is the most important factor affecting both vascular temperature and tensile strength. The optimal balance between strength and minimal thermal injury may be achieved primarily at 56.7 W/cm(2) and 0.01 mM ICG.

The purpose of this article is to provide a comprehensive review on the clinical role of low intensity laser therapy (laser photostimulation) in biology and medicine. Studies on wound healing and pain relief are highlighted to show the clinical efficacy of laser therapy. Controversies about the use of low intensity laser as a therapeutic modality for wound healing and pain relief are presented and a brief explanation is provided to overcome these controversies. The importance of standard parameters is emphasized for the applications of low intensity lasers in biology and medicine. A justification has been made to warrant further research on the use of low intensity laser as a therapeutic modality. Although the therapeutic applications of low intensity laser are imminent, the heterogeneity in treatment protocols and study design calls for a vigilant interpretation of the findings.

Objective: Low-level laser therapy (LLLT) has been used for the last few years to treat sports injuries. The purpose of this study was to compare three therapeutic protocols in treating edema in second degree ankle sprains that did not require immobilization with a splint, under placebo-controlled conditions.

Materials and methods: Forty-seven soccer players with second degree ankle sprains, selected at random, were divided into the following groups: The first group (n = 16) was treated with the conventional initial treatment (RICE, rest, ice, compression, elevation), the second group (n = 16) was treated with the RICE method plus placebo laser, and the third group (n = 15) was treated with the RICE method plus an 820-nm GaA1As diode laser with a radiant power output of 40 mW at 16 Hz. Before the treatment, and 24, 48, and 72 h later, the volume of the edema was measured.

Results: A three by three repeated measures ANOVA with a follow up post hoc test revealed that the group treated with the RICE and an 820-nm GaA1As diode laser presented a statistically significant reduction in the volume of the edema after 24 h (40.3 +/- 2.4 mL, p < 0.01), 48 h (56.4 +/- 3.1 mL, p < 0.002), and 72 h (65.1 +/- 4.4 mL, p < 0.001).

Conclusions: LLLT combined with RICE can reduce edema in second-degree ankle sprains.

Objective: The aim of this study was to evaluate the ability of an Er:YAG laser (2960nm) to prepare class V cavities as compared with rotary instruments.

Materials and methods: Twenty-six freshly extracted human molars were selected and randomly distributed in two groups. Non standardized class V cavities were prepared using (group 1) a diamond bur for enamel, plus a tungsten bur for dentin with water irrigation and (group 2) an Er:YAG laser (output parameters, enamel: 1000 mJ, 12Hz, dentin: 500 mJ, 20Hz) with a continuous flow of water.

Results: The SEM examination revealed characteristic micro-irregularities of the lased samples as compared with the conventional prepared cavities: group 1, the walls of the cavities were slightly curved and a smear layer plus muds covered peripheric walls as well as the depth of the cavity; rare dentinal tubules were opened; linear and circular surface irregularities were observed on the dentin; and group 2, the walls of the cavities were irregular, jagged; photo-ablation creates a real cleavage of hydroxyapatite prisms with respect to the enamel prism pathway; an homogeneous dentin with opened dentinal tubules covered the depth of the cavities; intertubular dentin is selectively more ablated than Er-YAG the peritubular dentin.

Conclusions: Jagged outline as well as opened dentinal tubules are the main characteristics of the Er-YAG prepared class V cavities. Further investigations (ulstrastructural, histochemical properties of the lased dentin, resistance to traction of bonded resins) should be conducted.

Objective: To evaluate safety and short-term visual and fluorescein angiographic effects of trans-scleral diode laser photocoagulation in patients with subfoveal choroidal neovascularization from age-related macular degeneration (ARMD).

Background data: The visual outcome following treatment of subfoveal choroidal neovascularization in ARMD is still unsatisfactory. Various forms of therapy such as laser treatment, photodynamic therapy, radiation therapy, transpupillary thermotherapy, and surgical excision have been tried with variable results.

Materials and methods: Patients with subfoveal choroidal neo-vascularization were treated with trans-scleral diode laser using the diopexy probe under indirect ophthalmoscopic visualization and followed up at 2, 6, and 12 weeks. Standardized protocol refraction, visual acuity testing, reading speed, contrast requirement measurement, ophthalmic examinations, color fundus photographs, and fluorescein angiogram were used to evaluate the results of treatment.

Results: Eighteen eyes of 18 patients were included in the study between April 2000 and May 2002. At 12 weeks, 81.5% patients showed stabilization (+/-5 letters) in letter visual acuity score, and one patient showed improvement (gain of more than five letters) in letter visual acuity score. Reading speed levels and contrast requirement were found to be similar to pre-laser level at 3 months followup. At 12 weeks, moderate fluorescein leakage was seen in one eye, minimal leakage was seen in five eyes, absence of leakage was seen in 10 eyes, and progression was seen in two eyes.

Conclusion: Transcleral diode laser treatment of subfoveal choroidal neovascular membranes in ARMD may be an effective as well as safe alternative in the management of these patients.

Objective: To investigate the effect of laser photostimulation in rehabilitation of human digital flexor tendons with a placebo-controlled double-blind prospective study model.

Background data: Low-energy laser therapy has been applied in several rheumatoid and soft tissue disorders with a varying rate of success and it has also been shown to have a positive effect on tendon healing in animal experiments, but no clinical study on laser photostimulation in the treatment of human tendons has been reported to date.

Materials and methods: This study was performed in a total of 25 patients with 41 digital flexor tendon injuries in five anatomical zones. In Group I (21 digits in 13 patients), whirlpool and infrared GaAs diode laser with a frequency of 100 Hz. was applied between the 8th and 21st days postoperatively and all patients were given the Washington rehabilitation program until the end of the 12th week. In Group II (20 digits in 12 patients), the same treatment protocol was given but the laser instrument was switched off during applications.

Results: The results of the study showed a significant improvement in the laser-treated group only for the parameter of edema reduction (p < 0.01) but the difference between the two groups was non-significant for pain reduction, hand grip strength, and functional evaluation performed according to Strickland and Buck-Gramcko systems using total active motion and fingertip-to distal palmar crease distance parameters (p > 0.05).

Conclusions: Significant improvement obtained in edema reduction both immediately and 12 weeks after supplementary GaAs laser application in our study has been interpreted as an important contribution to the rehabilitation of human flexor tendon injuries because edema is known to have a detrimental effect on functional recovery during both early and late stages of tendon healing. However, our study has failed to show a significant positive effect of supplementary GaAs laser application on the other functional recovery parameters of human flexor tendon injury rehabilitation and we suggest further clinical study in this topic be done using different laser types and dosages in order to delineate the role of this promising treatment modality.

Objective: To define the optimal parameters of KTP laser irradiation during a selective caries removal.

Materials and methods: Twelve decayed human teeth, recently extracted were used. Their root canals were prepared for insertion of a thermocouple probe into the pulp chamber. The demineralized tissues were colored by Acid Red 52 before proceeding to different conditions of irradiation.

Results: Pulpal temperature increases (below 3 degrees C) were found under the following parameters with 15 sec of continuous lasing: 400 mWatts, 0.10-msec pulse width, PRR <50 Hz for efficient caries removal. A resting time average of 70 sec was necessary to allow pulp temperature to get back to its baseline.

Conclusion: KTP laser can be used safely and without any pulp over-heating under certain irradiation conditions.