Effect of photodynamic therapy on the mechanical properties and bond strength of glass-fiber posts to endodontically treated intraradicular dentin.

STATEMENT OF PROBLEM: The use of photosensitizers in photodynamic therapy promotes intraradicular microbial reduction during nonsurgical endodontic therapy. However, studies are lacking on the consequences of the application of these agents on the mechanical properties of intraradicular dentin and on the bond strength of glass-fiber posts. PURPOSE: The purpose of this in vitro study was to evaluate the influence of photodynamic therapy on the bond strength of glass-fiber posts using a push-out test and, additionally, to measure the Martens hardness (MH) and elastic indentation modulus (Eit) of intraradicular dentin when different photosensitizers are used. MATERIAL AND METHODS: Eighty bovine teeth were used to simulate experimental endodontic treatments. Biomechanical instrumentation was performed for all root canals, and the teeth were distributed into 5 groups: control-deionized water; methylene blue 50 mg/L + red laser; methylene blue 100 mg/L + red laser; curcumin 500 mg/L + blue LED; and curcumin 1000 mg/L + blue LED. The MH and Eit of intraradicular dentin were measured using an ultramicrohardness tester under a load of 3 mN (n=8). The push-out bond strength of glass-fiber posts to dentin was measured using a universal testing machine (n=8). Mechanical properties and bond strength data were subjected to the Kruskal-Wallis test, ANOVA, and Fisher least significant difference test (α=.05). Images of representative specimens were obtained using a scanning electron microscope. RESULTS: The MH, Eit, and bond strength of intraradicular dentin were influenced by the photosensitizer used. In general, curcumin promoted lower mechanical properties values but higher bond strength values. CONCLUSIONS: Photosensitizers influenced the mechanical properties of intraradicular dentin and the bond strength of glass-fiber posts, and methylene blue at 50 mg/L had no marked effect on the mechanical properties of the dentin or the bond strength values.

Efficacy of Various Pretreatments on the Bond Strength of Denture Teeth to Denture Base Resins.

OBJECTIVE: This in vitro study evaluated the shear bond strength (SBS) of heat-cured denture base resin (PMMA) to acrylic resin teeth treated with different pretreatments, especially laser irradiation of different powers (1-4 W). MATERIALS AND METHODS: The acrylic resin teeth were separated into seven groups (n = 10) for the following different pretreatments: control group (no surface treatment) (G1), grinding with a tungsten carbide bur (G2), sandblasting (G3), and erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation at 1 W, 2 W, 3 W, 4 W output powers in (G4-7), respectively. Test specimens were produced according to the PMMA manufacturers' instructions and were subjected to a SBS test at a crosshead speed of 1 mm/min until fracture. Debonded surfaces were evaluated by a stereomicroscope for the type of failure. SEM (scanning electron microscope) analyses were done to estimate the surface changes of the acrylic resin teeth. The data were submitted using a one-way ANOVA and post hoc Tukey-Kramer multiple comparison tests (p = 0.05). RESULTS: The highest bond strength was obtained in G3, and similar SBS values were considered in other groups, and no significant differences were found among the surface treatments and the control group (p < 0.05). All groups had a high percentage of adhesive failures. CONCLUSIONS: Laser irradiations promote surface topography alterations. However laser irradiation of the adhesive surface was found ineffective. The SBS of acrylic resin teeth to a PMMA denture base material is independent of the surface pretreatments Er,Cr:YSGG laser irradiation, sandblasting, and grinding with a carbide bur. All the surface treatments provided a similar bond between the acrylic denture base and the teeth.

Photobiomodulation of wound healing via visible and infrared laser irradiation.

Fibroblast cells are known to be one of the key elements in wound healing process, which has been under the scope of research for decades. However, the exact mechanism of photobiomodulation on wound healing is not fully understood yet. Photobiomodulation of 635 and 809 nm laser irradiation at two different energy densities were investigated with two independent experiments; first, in vitro cell proliferation and then in vivo wound healing. L929 mouse fibroblast cell suspensions were exposed with 635 and 809 nm laser irradiations of 1 and 3 J/cm2 energy densities at 50 mW output power separately for the investigation of photobiomodulation in vitro. Viabilities of cells were examined by means of MTT assays performed at the 24th, 48th, and 72nd hours following the laser irradiations. Following the in vitro experiments, 1 cm long cutaneous incisional skin wounds on Wistar albino rats (n = 24) were exposed with the same laser sources and doses in vivo. Wound samples were examined on 3rd, 5th, and 7th days of healing by means of mechanical tensile strength tests and histological examinations. MTT assay results showed that 635 nm laser irradiation of both energy densities after 24 h were found to be proliferative. One joule per square centimeter laser irradiation results also had positive effect on cell proliferation after 72 h. However, 809 nm laser irradiation at both energy densities had neither positive nor negative affects on cell viability. In vivo experiment results showed that, 635 nm laser irradiation of both energy densities stimulated wound healing in terms of tensile strength, whereas 809 nm laser stimulation did not cause any stimulative effect. The results of mechanical tests were compatible with the histological evaluations. In this study, it is observed that 635 nm laser irradiations of low energy densities had stimulative effects in terms of cell proliferation in vitro and mechanical strength of incisions in vivo. However, 809 nm laser irradiations at the same doses did not have any positive effect.

Evaluation of the Effects of Photobiomodulation on Bone Healing in Healthy and Streptozotocin-Induced Diabetes in Rats.

OBJECTIVE: This study aimed to assess the effects of Photobiomodulation (PBM) with pulsed wave laser on Hounsfield unit (HU) and bone strength at a catabolic response (bone resorption) of a callus bone defect in healthy and streptozotocin (STZ)- induced type I diabetes mellitus (TI DM) in rats. BACKGROUND DATA: Conflicting results exist regarding the effect of PBM on bone healing in healthy and diabetic animals. MATERIALS AND METHODS: We randomly divided 20 adult female rats into the following groups: (1) control, no TI DM, and no PBM; (2) no TI DM and PBM; (3) TI DM and no PBM; and (4) TI DM and PBM. TI DM was induced by STZ. All rats underwent partial transversal standardized osteotomies in their right tibias. The rats received PBM (890 nm, 80 Hz, 1.5 J/cm2) thrice per week during 30 days. At 4 weeks after the surgery, the rats were sacrificed and their tibias submitted to computed tomography scanning to measure HU. The samples underwent a three-point bending test to evaluate bone strength. RESULTS: Analysis of variance (ANOVA) (p = 0.013) results showed that treatment by PBM significantly increased the biomechanical property (stress high load) of the callus defect from the partial tibia osteotomy in healthy rats compared to the control groups. However, we observed no significant increase in the biomechanical properties of the laser-treated diabetic bone defect compared to the control diabetic group. The ANOVA for the HU of callus density produced a p value of 0.000. A significant increase existed in the mean callus density in the healthy groups compared to the diabetic groups. CONCLUSIONS: The 80-Hz laser did not significantly enhance bone repair from an osteotomy of the tibia in an experimental model of TI DM rats.

Bond Strength of Abraded and Non-Abraded Bleached Enamel to Resin After Er,Cr:YSGG Laser Irradiation.

OBJECTIVE: The objective of the study was to evaluate the microtensile bond strength (µTBS) of a composite resin to abraded or non-abraded bleached enamel after Er,Cr:YSGG laser irradiation and to observe the fracture patterns of the tested interfaces. MATERIALS AND METHODS: Two hundred twenty-eight bovine incisors were sectioned, resulting in 228 enamel blocks (7 × 4 × 4 mm3) that were divided into 12 groups (n = 19) according to the factors "adhesion" after bleaching (immediate adhesion; after 14 days; and a control group with adhesion on unbleached teeth); enamel "abrasion" (with or without abrasion simulating cavity preparation); and "laser" (with or without Er,Cr:YSGG laser irradiation). Bleached enamel groups were treated with 20% carbamide peroxide, 8 h/day for 21 days. Abrasion was performed with silicon carbide sandpaper. Specimens were restored with adhesive system and a composite resin (Adper Single Bond 2 and Z250; 3M ESPE). After 7 days, specimens were prepared by cutting into 1 mm beans to µTBS test performed in a universal testing machine. Fracture mode analysis was performed by using a stereoscopic loupe. The µTBS data were statistically analyzed by three-way analysis of variance with 95% confidence level and compared by running a Tukey post hoc test (α = 0.05). RESULTS: There was no statistically significant difference between triple interaction and double interactions among factors. There was no significant difference between the factors "adhesion," "abrasion," and "laser." Laser irradiation produced significantly lower bond strength values in irradiated groups compared with the non-irradiated ones. All groups had a high percentage of adhesive failures. CONCLUSIONS: Abrasion provided no benefit to bond strength of composite resins to bleached enamel. Er,Cr:YSGG (20 Hz, 0.5 W, 3.97 J/cm2) treatment reduced the bond strength of composite resins to enamel.

The effect of post-mastectomy radiation therapy on breast implants: Unveiling biomaterial alterations with potential implications on capsular contracture.

Post-mastectomy breast reconstruction with expanders and implants is recognized as an integral part of breast cancer treatment. Its main complication is represented by capsular contracture, which leads to poor expansion, breast deformation, and pain, often requiring additional surgery. In such a scenario, the debate continues as to whether the second stage of breast reconstruction should be performed before or after post-mastectomy radiation therapy, in light of potential alterations induced by irradiation to silicone biomaterial. This work provides a novel, multi-technique approach to unveil the role of radiotherapy in biomaterial alterations, with potential involvement in capsular contracture. Following irradiation, implant shells underwent mechanical, chemical, and microstructural evaluation by means of tensile testing, Attenuated Total Reflectance Fourier Transform InfraRed spectroscopy (ATR/FTIR), Scanning Electron Microscopy (SEM), high resolution stylus profilometry, and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Our findings are consistent with radiation-induced modifications of silicone that, although not detectable at the microscale, can be evidenced by more sophisticated nanoscale surface analyses. In light of these results, biomaterial irradiation cannot be ruled out as one of the possible co-factors underlying capsular contracture.

Effects study on the thermal stresses in a LEU metal foil annular target.

The effects of fission gas pressure, uranium swelling and thermal contact conductance on the thermal-mechanical behavior of an annular target containing a low-enriched uranium foil (LEU) encapsulated in a nickel foil have been presented in this paper. The draw-plug assembly method is simulated to obtain the residual stresses, which are applied to the irradiation model as initial inputs, and the integrated assembly-irradiation process is simulated as an axisymmetric problem using the commercial finite element code Abaqus FEA. Parametric studies were performed on the LEU heat generation rate and the results indicate satisfactory irradiation performance of the annular target. The temperature and stress margins have been provided along with a discussion of the results.

Stiffening of rabbit corneas by the bacteriochlorophyll derivative WST11 using near infrared light.

PURPOSE: We evaluated the efficacy and safety of photochemical corneal stiffening by palladium bacteriochlorin 13'-(2-sulfoethyl)amide dipotassium salt (WST11) and near infrared (NIR) illumination, using ex vivo and in vivo rabbit eye models. METHODS: Corneas of post mortem rabbits and living rabbits were pretreated topically with 2.5 mg/mL WST11 in saline or in 20% dextran T-500 (WST-D), washed and illuminated with an NIR diode laser (755 nm, 10 mW/cm(2). Studies with corneas of untreated fellow eyes served as controls. Tensile strength measurements, histopathology, electron spin resonance, and optical spectroscopy and fluorescence microscopy were used to assess treatment effects. Comparative studies were performed with standard riboflavin/ultraviolet-A light (UVA) treatment. RESULTS: WST11/NIR treatment significantly increased corneal stiffness following ex vivo or in vivo treatment, compared to untreated contralateral eyes. The incremental ultimate stress and Young's modulus of treated corneas increased by 45, 113, 115%, and 10, 79, and 174% following 10, 20, and 30 minutes of incubation with WST11, respectively. WST-D/NIR had a similar stiffening effect, but markedly reduced post-treatment edema and shorter time of epithelial healing. WST11/NIR and WST-D/NIR generate hydroxyl and superoxide radicals, but no singlet oxygen in the cornea. Histology demonstrated a reduction in the keratocyte population in the anterior half of the corneal stroma, without damage to the endothelium. CONCLUSIONS: Treatment of rabbit corneas, with either WST11/NIR or WST-D/NIR, increases their biomechanical strength through a mechanism that does not involve singlet oxygen. The WST-D/NIR treatment showed less adverse effects, demonstrating a new potential for clinical use in keratoconus and corneal ectasia after refractive surgery.

Development of hierarchical magnesium composites using hybrid microwave sintering.

In this work, hierarchical magnesium based composites with a micro-architecture comprising reinforcing constituent that is a composite in itself were fabricated using powder metallurgy route including microwave assisted rapid sintering technique and hot extrusion. Different level-I composite particles comprises sub-micron pure aluminum (Al) matrix containing Al2O3 particles of different length scale (from micrometer to nanometer size). Microstructural characterization of the hierarchical composites revealed reasonably uniform distribution of level-I composite particles and significant grain refinement compared to monolithic Mg. Hierarchical composite configurations exhibited different mechanical performance as a function of Al2O3 length scale. Among the different hierarchical formulations synthesized, the hierarchical configuration with level-I composition comprising Al and nano-Al2O3 (0.05 microm) exhibited the highest improvement in tensile yield strength (0.2% YS), ultimate tensile strength (UTS), tensile failure strain (FS), compressive yield strength (0.2% CYS) and ultimate compressive strength (UCS) (+96%, +80%, +42%, +80%, and +83%) as compared to monolithic Mg. An attempt has been made in the present study to correlate the effect of different length scales of Al2O3 particulates on the microstructural and mechanical response of magnesium.

The effect of equal daily dose achieved by different power densities of low-level laser therapy at 635 and 670 nm on wound tensile strength in rats: a short report.

OBJECTIVE: The aim of our study was to compare the effects of different power densities of LLLT at 635 and 670 nm achieving a daily dose of 5 J/cm(2) on wound tensile strength (TS) in rats. BACKGROUND DATA: Optimal parameters of low-level laser therapy (LLLT) are still unknown. MATERIALS AND METHODS: Under general anesthesia, one full-thickness skin incision was performed on the back of each rat (n = 40) and immediately closed using an intradermal running suture. Rats were separated into five groups depending on treatment parameters: (1) sham irradiated control group (SIC); (2) 635 nm laser-treated group at 4 mW/cm(2) (L-635/4); (3) 635 nm laser-treated group at 15 mW/cm(2) (L-635/15); (4) 670 nm laser-treated group at 4 mW/cm(2) (L-670/4); and (5) 670 nm laser-treated group at 15 mW/cm(2) (L-670/15). The total daily dose was 5 J/cm(2). Seven days after surgery each wound was removed for wound TS measurement. RESULTS: The lowest wound TS results were measured in the SIC rats (10.5 +/- 2.8 g/mm(2)). Higher wound TS results were measured in group L-670/15 (11.5 +/- 2.5 g/mm(2)) and group L-635/4 (11.7 +/- 4.3 g/mm(2)) rats, while significantly higher results were found in group L-670/4 (15.8 +/- 4.4 g/mm(2)) and group L-635/15 (15.9 +/- 4.8 g/mm(2)). The differences were significant between certain groups (p < 0.01: SIC vs. L-635/15, SIC vs. L-670/4; p < 0.05: L-635/4 vs. L-635/15, L-635/4 vs. L-670/4, L-635/15 vs. L-670/15, L-670/4 vs. L-670/15). CONCLUSION: Both red lasers significantly increased wound TS at selected parameters. Whereas the 635 nm laser significantly improved wound healing by using the higher power density, the 670 nm laser improved healing using a lower power density.

Radioprotection of tendon tissue via crosslinking and free radical scavenging.

Ionizing radiation could supplement tissue bank screening to further reduce the probability of diseases transmitted by allografts if denaturation effects can be minimized. It is important, however, such sterilization procedures be nondetrimental to tissues. We compared crosslinking and free radical scavenging potential methods to accomplish this task in tendon tissue. In addition, two forms of ionizing irradiation, gamma and electron beam (e-beam), were also compared. Crosslinkers included 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and glucose, which were used to add exogenous crosslinks to collagen. Free radical scavengers included mannitol, ascorbate, and riboflavin. Radioprotective effects were assessed through tensile testing and collagenase resistance testing after irradiation at 25 kGy and 50 kGy. Gamma and e-beam irradiation produced similar degenerative effects. Crosslinkers had the highest strength at 50 kGy, EDC treated tendons had 54% and 49% higher strength than untreated, for gamma and e-beam irradiation respectively. Free radical scavengers showed protective effects up to 25 kGy, especially for ascorbate and riboflavin. Crosslinked samples had higher resistance to collagenase and over a wider dose range than scavenger-treated. Of the options studied, the data suggest EDC precrosslinking or glucose treatment provides the best maintenance of native tendon properties after exposure to ionizing irradiation.

Influência do laser de baixa intensidade na estabilidade de mini-implantes ortodônticos (estudo em coelhos) / Influence of low-intensity laser in orthodontic mini-implants stability (Rabbit study)

Foi avaliado, com ensaio mecânico de tração, a estabilidade de mini-implantes ortodônticos de dois formatos distintos após serem inseridos em tíbias de coelho e submetidos a aplicação do laser de baixa intensidade. A amostra compreendeu 32 mini-implantes ortodônticos, sendo 16 de forma cilíndrica e 16 de forma cônica. Foram utilizados nesse estudo, oito coelhos da raça Nova Zelândia com idade de dez meses e pesando em média 3000 gramas; divididos em dois grupos de quatro animais cada, denominados como Grupo A (cilíndrico) e Grupo B (cônico). Em cada animal foram instalados dois mini-implantes por tíbia. O lado direito dos animais teve os sítios de colocação dos implantes irradiados com laser de baixa intensidade durante um período de 21 dias, que iniciou no pós-operatório e seguiu-se respeitando-se o intervalo de 48 horas entre as sessões de irradiação, totalizando dez até o final do experimento. O lado esquerdo não recebeu irradiação. Após o período experimental de 21 dias com aplicação do laser, os animais foram eutanasiados, as tíbias removidas e os corpos de prova foram utilizados para os ensaios de tração na máquina universal (Emic DL 2000, São José dos Pinhais, Brasil). Os valores de força máxima para tração foram obtidos em N e foram submetidos a análise de variância (ANOVA) e ao teste de Tukey. Os grupos os quais foram realizadas as aplicações do laser, independente do formato, apresentaram forças médias maiores em relação aos grupos que não foram submetidos a esses procedimentos, demonstrando uma tendência a uma resposta positiva para a aplicação do laser, apesar de não haver diferenças estatísticas entre os mesmos. Concluiu-se que a aplicação do laser de baixa intensidade na região de instalação dos mini-implantes não promoveu aumento significante em sua estabilidade quando comparados com aqueles que não receberam essas aplicações, muito embora, tenha sido observado uma forte tendência nesse sentido...

Effect of low-level laser therapy on healing of medial collateral ligament injuries in rats: an ultrastructural study.

OBJECTIVE: This study sought to investigate whether low-level laser therapy (LLLT) with a helium-neon (He-Ne) laser would increase fibril diameter of transected medial collateral ligament (MCL) in rats. BACKGROUND DATA: It has been shown that LLLT can increase ultimate tensile strength MCL healing. METHODS: Thirty rats received surgical transect to their right MCL, and five were assigned as the control group. After surgery, the rats were divided into three groups: group 1 (n = 10) received LLLT with He-Ne laser and 0.01 J/cm(2) energy fluency per day, group 2 (n = 10) received LLLT with 1.2 J/cm(2) energy fluency (density) per day and group 3 (sham-exposed group; n = 10) received daily placebo laser with shut-down laser equipment, while control group received neither surgery nor LLLT. Transmission electron microscope (TEM) examination was performed on days 12 and 21 after surgery and dimension and density of ligament fibrils were measured. The data were analyzed by Student t-test and Mann-Whitney tests, respectively. RESULTS: On day 12, the fibril dimension of group 2 and their density were higher than of groups 1 and 3. CONCLUSION: LLLT with He-Ne laser on incised MCL in rats could not significantly increase fibril diameter and their density in comparison with sham-exposed group.

In vitro and in vivo tissue repair with laser-activated chitosan adhesive.

BACKGROUND AND OBJECTIVES: Sutures are currently the gold standard for wound closure but they are still unable to seal tissue and may induce scarring or inflammation. Biocompatible glues, based on polysaccharides such as chitosan, are a possible alternative to conventional wound closure. In this study, the adhesion of laser-activated chitosan films is investigated in vitro and in vivo. In particular we examine the effect of varying the laser power, as well as adding a natural cross-linker (genipin) to the adhesive composition. STUDY DESIGN/MATERIALS AND METHODS: Flexible and insoluble strips of chitosan films (surface area approximately 34 mm(2), thickness approximately 20 microm) were bonded to sheep intestine using several laser powers (0, 80, 120, and 160 mW) at 808-nm wavelength. The strength of repaired tissue was tested by a calibrated tensiometer to select the best power. A natural cross-linker (genipin) was also added to the film and the tissue repair strength compared with the strength of plain films. The adhesive was also bonded in vivo to the sciatic nerve of rats and the thermal damage induced by the laser assessed 4 days post-operatively. RESULTS: Chitosan adhesives successfully repaired intestine tissue, attaining a maximum repair strength of 14.7+/-4.3 kPa (n = 30) at the laser power of 120 mW. The chitosan-genipin films achieved lower repair strength (9.1+/-2.9 kPa). The laser caused partial demyelination of axons at the site of operation, but the myelinated axons retained a normal morphology proximally and distally. CONCLUSIONS: The chitosan adhesive effectively bonded to tissue causing only localized thermal damage in vivo, when the appropriate laser parameters were selected.

Near infrared laser-tissue welding using nanoshells as an exogenous absorber.

BACKGROUND AND OBJECTIVE: Gold nanoshells are a new class of nanoparticles that can be designed to strongly absorb light in the near infrared (NIR). These particles provide much larger absorption cross-sections and efficiency than can be achieved with currently used chemical chromophores without photobleaching. In these studies, we have investigated the use of gold nanoshells as exogenous NIR absorbers to facilitate NIR laser-tissue welding. STUDY DESIGN/MATERIALS AND METHODS: Gold nanoshells with peak extinction matching the NIR wavelength of the laser being used were manufactured and suspended in an albumin solder. Optimization work was performed on ex vivo muscle samples and then translated into testing in an in vivo rat skin wound-healing model. Mechanical testing of the muscle samples was immediately performed and compared to intact tissue mechanical properties. In the in vivo study, full thickness incisions in the dorsal skin of rats were welded, and samples of skin were excised at 0, 5, 10, 21, and 32 days for analysis of strength and wound healing response. RESULTS: Mechanical testing of nanoshell-solder welds in muscle revealed successful fusion of tissues with tensile strengths of the weld site equal to the uncut tissue. No welding was accomplished with this light source when using solder formulations without nanoshells. Mechanical testing of the skin wounds showed sufficient strength for closure and strength increased over time. Histological examination showed good wound-healing response in the soldered skin. CONCLUSIONS: The use of nanoshells as an exogenous absorber allows the usage of light sources that are minimally absorbed by tissue components, thereby, minimizing damage to surrounding tissue and allowing welding of thicker tissues.

Therapeutic low energy laser improves the mechanical strength of repairing medial collateral ligament.

BACKGROUND AND OBJECTIVES: Low energy laser therapy has been shown to enhance collagen production but its effect on tissue strength is not well reported. We tested the effects of therapeutic laser on the strength of healing medial collateral ligaments (MCLs) in rats. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four rats received surgical transection to their right MCL and eight received sham operation. After surgery, 16 received a single dose of gallium aluminum arsenide laser to their transected MCL for 7.5 minutes (n = 8) or 15 minutes (n = 8) and eight served as control with placebo laser, while the sham group didn't receive any treatment. The MCLs were biomechanically tested at either 3 or 6 weeks post-operation. RESULTS: The normalized ultimate tensile strength (UTS) and stiffness of laser and sham groups were larger than control (P < 0.001). The UTS of laser and sham groups were comparable. Laser and sham groups had improved in stiffness from 3 to 6 weeks (P < 0.001). CONCLUSIONS: A single dose of low energy laser therapy improves the UTS and stiffness of repairing MCL at 3 and 6 weeks after injury.

Wound repair after fractionated external beam radiation therapy and concomitant hyperthermia in an experimental rat model.

BACKGROUND: Fractionated radiation therapy (RT) with adjuvant hyperthermia (HT) is being used in the treatment of cancer with noted clinical success. However, little information regarding wound repair in tissues receiving this combination therapy is available for comparison of surgical risk. Consequently, this study was undertaken to assess the effects of this combined therapy on wound healing by quantitatively evaluating wound repair using tensile strength measurements. METHODS: Four treatment cohorts were designated: sham control, RT alone (600 cGy/d for 4 days), HT alone (water bath at 41.8 degrees C, subcutaneous temperature of 41.0 +/- 0.5 degrees C for 60 minutes on days 1 and 4), and combined RT and HT. At 1 week after treatment, surgical incisions of the dorsal flank were made. Tensile strength measurements of wounds were obtained at 14 and 21 days after incision. RESULTS: No significant differences were observed in the combined treatment arm (RT and HT) compared with the reduced wound breaking strength of RT alone. Statistically significant differences in tensile strength were seen when the control group or HT alone was compared with RT and HT or RT alone. CONCLUSIONS: Concomitant exposure to fractionated RT and specific HT conditions demonstrated no disproportionate alteration in wound tensile strength compared with radiation exposure alone in this animal model.

[Wound healing after laser and red light irradiation]. / Wundheilung nach Laser- und Rotlichtbestrahlung.

Laser irradiation and red light irradiation, daily 2 respectively 4 J/cm2, do not bring any acceleration of wound healing in rats. No significant effect was evident in the cell pattern of wounds during various phases of healing through the irradiation. The tensile strength of cicatrices increased by laser irradiation, but not by red light irradiation (monochromatic lambda = 633 nm).