Effectiveness of Er:YAG laser-aided fiberotomy and low-level laser therapy in alleviating relapse of rotated incisors.

INTRODUCTION: In this study, we compared the effectiveness of laser-aided circumferential supracrestal fiberotomy (CSF) and low-level laser therapy (LLLT) with conventional CSF in reducing relapse of corrected rotations. METHODS: The study included 24 patients who were at the finishing stage of orthodontic treatment and had at least 1 maxillary incisor with 30° to 70° of rotation before starting therapy. The subjects were divided into 4 groups by treatment: conventional CSF, Er:YAG laser-aided CSF, LLLT, and control. After alginate impressions were taken, the archwire was sectioned from the experimental incisors, and they were allowed to relapse. The second impression was taken 1 month later, and the degree and percentage of relapse were calculated in photographs taken from the dental models. Gingival recession, pocket depth, and pain were also measured in the CSF groups. RESULTS: The mean percentages of relapse were 9.7% in the conventional CSF, 12.7% in the Er:YAG laser-aided CSF, 11.7% in the LLLT, and 27.8% in the control groups. Relapse was significantly greater in the control than the experimental groups (P <0.05), which were not statistically different from each other. The changes in sulcus depth and gingival recession were small and not significantly different among the CSF groups (P >0.05), but pain intensity was greater in subjects who underwent conventional CSF (P = 0.003). CONCLUSIONS: Er:YAG laser-aided CSF proved to be an effective alternative to conventional CSF in reducing rotational relapse. LLLT with excessively high energy density was also as effective as the CSF procedures in alleviating relapse, at least in the short term.

A generalized haptic feedback approach for arbitrarily shaped objects.

In surgery procedures, haptic interaction provides surgeons with indispensable information to accurately locate the surgery target. This is especially critical when visual feedback cannot provide sufficient information and tactile interrogation, such as palpating some region of tissue, is required to locate a specific underlying tumor. However, in most current surgery simulators, the haptic interaction model is usually simplified into a contact sphere or rod model, leaving arbitrarily shaped intersection haptic feedback between target tissue and surgery instrument less unreliable. In this paper, a novel haptic feedback algorithm is introduced for generating the feedback forces in surgery simulations. The proposed algorithm initially employs three Layered Depth Images (LDI) to sample the 3D objects in X, Y and Z directions. A secondary analysis scans through two sampled meshes and detects their penetration volume. Based on the principle that interaction force should minimize the penetration volume, the haptic feedback force is derived directly. Additionally, a post-processing technique is developed to render distinct physical tissue properties across different interaction areas. The proposed approach does not require any pre-processing and is applicable for both rigid and deformable objects.

Avaliação do processo de reparo de incisões realizadas em tecido cutâneo de ratos e submetidas a laser terapêutico / Evaluation of wound healing process of incisions made in cutaneous tissue of rats and submitted to therapeutic laser

O laser de baixa potência tem sido utilizado após procedimentos cirúrgicos visando acelerar o processo de reparo tecidual. No entanto, embora esse tipo de tratamento ofereça pouco ou nenhum risco à saúde do paciente, sua eficácia ainda é controversa na literatura. Este estudo foi desenvolvido para avaliar o efeito do laser de baixa potência (100 mW) sobre o processo de reparo de incisões cutâneas em dorso de ratos. Incisões de 2 cm de extensão foram confeccionadas no dorso de cinquenta e seis ratos Wistar. Após a sutura, metade dos animais recebeu laser de baixa potência em 3 pontos de aplicação, um no centro e um em cada extremidade da ferida. Em cada ponto, foi administrada uma dose de 35 J/cm2 (laser de InGaAlP, 660 nm, vermelho visível). A outra metade dos animais serviu como controle. Os tecidos incisados foram avaliados microscopicamente, de forma descritiva, em períodos de 6 horas, 2, 7 e 14 dias, levando em consideração o aspecto do revestimento epitelial e do tecido conjuntivo e a magnitude da resposta inflamatória, quando presente. Para os dois primeiros períodos, foi feita também uma avaliação morfométrica, que mensurou a densidade de fibroblastos, fibras colágenas, vasos sanguíneos e células inflamatórias no tecido conjuntivo. Na análise descritiva, as maiores diferenças foram encontradas no período de 6 horas, seguido pelo de 2 dias. Em 6 horas, o grupo tratado com laser apresentou menor resposta inflamatória que o controle e, em alguns espécimes, foi possível evidenciar início de proliferação das células do epitélio nas bordas da ferida. Em 2 dias, alguns espécimes do grupo controle ainda apresentavam células inflamatórias remanescentes, não evidenciadas no grupo laser. Nesse período, foi possível evidenciar também, em alguns espécimes do grupo laser, proliferação de fibroblastos junto às bordas da ferida. Nos períodos de 7 e 14 dias, não foram encontradas diferenças entre os grupos. Na análise morfométrica, a densidade de fibras colágenas e...

Low-power laser therapy has been used after surgical procedures to improve wound healing. However, although such kind of treatment offers little or no risk to the patient's health, its effectiveness remains controversial. This study was developed to evaluate the effect of low-power laser (100 mW) on the healing of skin incisions in rats. Two centimeters incisions were made on the back of fifty-six Wistar rats. After suturing, half of the animals received low-power laser application on three points, one on center and one on each end of the wound. For each point, a dose of 35 J/cm2 (InGaAIP laser, 660 nm, visible red) was administered. The other half of the animals served as control. The incised tissues were evaluated microscopically in a descriptive way in periods of 6 hours, 2, 7 and 14 days, considering the aspects of epithelium and connective tissue and the magnitude of inflammatory response, when present. For the first two periods, it was also done a morphometric evaluation, which measured the density of fibroblasts, collagen fibers, blood vessels and inflammatory cells in the connective tissue. In descriptive analysis, the greatest differences were found in the period of 6 hours, followed by the period of 2 days. In 6 hours, the laser-treated group showed less inflammatory response than control and, in some specimens, it was possible to see the beginning of epithelium proliferation on the edges of the wound. In two days, some specimens of the control group still showed remaining inflammatory cells, not observed in the laser group. In this period, it was also possible to see, in some specimens of the laser group, proliferation of fibroblasts along the edges of the wound. In the periods of 7 and 14 days, no differences were found between the groups. In morphometric analysis, density of collagen fibers and blood vessels was higher for the laser group in...

Mathematical modeling of thermal ablation in tissue surrounding a large vessel.

Thermal ablation of a solid tumor in a tissue with radio-frequency (rf) energy can be accomplished by using a probe inserted into the tissue under the guidance of magnetic resonance imaging. The extent of the ablation can be significantly reduced by heat loss from capillary perfusion and by blood flow in a large vessel in the tissue. A mathematical model is presented of the thermal processes that occur during rf ablation of a tissue near a large blood vessel, which should not be damaged. Temperature distribution dynamics are described by the combination of a 3D bioheat transport in tissue together with a 1D model of convective-dispersive heat transport in the blood vessel. The objective was to determine how much of the tissue can be ablated without damaging the blood vessel. This was achieved by simulating the tissue temperature distribution dynamics and by determining the optimal power inputs so that a maximum temperature increase in the tissue was achieved without inducing tissue damage at the edge of the large vessel. The main contribution of this study is to provide a model analysis for pretreatment and, eventually, for intra-operative application to thermal ablation of a tumor located near a large blood vessel.

[Gingival depigmentation for aesthetic purposes using erbium:YAG laser: rationale and technique].

Melanin, carotene and hemoglobin are the most common natural pigments contributing to the normal color of the gums. Although physiologic and ethnic melanin pigmentation is not a medical problem, complains about "black gums" are common. Gingival depigmentation has been carried out using surgical, chemical, electrosurgical and cryosurgical procedures. Recently, Laser Ablation has been recognized as one of the most effective, pleasant and reliable techniques. Effective depigmentation of the gingival requires removal of all or most of the melanocytes from the basal layer of the gingival epithelium. Using non-specific radiation means ablation of all the epithelial cell layers, as well as connective tissue rete pegs, leaving behind only remnants of the epithelial rete ridges. CO2, Nd:YAG and Erbium:YAG lasers, meeting most of these requirements and being available in the dental office, seems to be the lasers of choice for this procedure. Five patients (3 F; 2 M) who were referred to the TAUSDM for cosmetic therapy of "black gums" were treated using Erbium-YAG laser. The laser beam was set up at 850 mj/10 pulses per second producing peak power of 2.13 kwand peak power density of 30.43 kw/sq/cm. The beam was defocused to produce a 3 mm diameter circle, thus reducing the beam penetration while increasing the treated surface. Using the "brush" technique, 800-2,000 pulses were required per patient, with an average of 500-1,100 pulses per 1 sq.cm, depending on the thickness of the epithelium and the intensity of the pigmentation. Treatment required only topical anesthesia. Healing was uneventful and required no supportive therapy. Three months follow up has shown no repigmentation in any of the patients. Patients' evaluation analysis showed that the results were pleasing; no pain was experienced during lasing as well as during healing. Two patients were interupted by the lasing burning smell, which may be reduced or eliminated by operating a power suction during the procedure.

[A simple alternative technic in the treatment of idiopathic hydrocele in adults: vaginal "fenestration"]. / Une alternative technique simple dans le traitement de l'hydrocèle idiopathique de l'adulte: la "fenestration" vaginale.

The author describes a new, simple technique for the treatment of idiopathic hydrocele according to a "fenestration" procedure designed to correct the imbalance of intravaginal hydrostatic exchanges. The operation consists of initially hemming separately the deep fibrous layer and the parietal leaflet of the tunica vaginalis to form the margins of the "window", which is then applied by its fibrous layer to the dartos, continuous with the subcutaneous connective tissue, a site of rich lymphatic drainage. In a series of 108 patients treated by this technique since September 1982, with a follow-up of 6 years, the anatomical and functional results were excellent in 98 cases (90.7%), moderate in 6 cases (5.5%) and poor in 4 cases (3.7%). Compared to classical techniques, the fenestrated opening of the tunica vaginalis with preservation of the tunica vaginalis and limited opening of the serosa, preserves the testicular support and the protective role of the serosa on the testis. Lastly, suture of the margins of the window to the dartos, by facilitating deep lymphatic drainage towards the superficial connective tissue, reconstitutes a physiological equilibrium in the constant exchanges of intravaginal serous fluids. Experience has demonstrated the anatomical and functional efficacy and reliability of this extremely simple procedure, which is essentially indicated in adult patients with idiopathic hydrocele and a healthy tunica vaginalis.

[A simple alternative method in the treatment of idiopathic hydrocele in adults: vaginal "fenestration"]. / Une alternative technique simple dans le traitement de l'hydrocèle idiopathique de l'adulte: la "fenestration" vaginale.

The author describes a new, simple technique for the treatment of idiopathic hydrocele according to a "fenestration" procedure designed to correct the imbalance of intravaginal hydrostatic exchanges. The operation consists of initially hemming separately the deep fibrous layer and the parietal leaflet of the tunica vaginalis to form the margins of the "window", which is then applied by its fibrous layer to the dartos, continuous with the subcutaneous connective tissue, a site of rich lymphatic drainage. In a series of 108 patients treated by this technique since September 1982, with a follow-up of 6 years, the anatomical and functional results were excellent in 98 cases (90.7%), moderate in 6 cases (5.5%) and poor in 4 cases (3.7%). Compared to classical techniques, the fenestrated opening of the tunica vaginalis with preservation of the tunica vaginalis and limited opening of the serosa, preserves the testicular support and the protective role of the serosa on the testis. Lastly, suture of the margins of the window to the dartos, by facilitating deep lymphatic drainage towards the superficial connective tissue, reconstitutes a physiological equilibrium in the constant exchanges of intravaginal serous fluids. Experience has demonstrated the anatomical and functional efficacy and reliability of this extremely simple procedure, which is essentially indicated in adult patients with idiopathic hydrocele and a healthy tunica vaginalis.

Chemically separated connective tissue grafts: clinical application and histological evaluation.

Subepithelial palatal connective tissue grafts, separated from the epithelium either chemically (n = 5) or surgically (n = 2) were inserted in patients presenting with gingival recession. Biopsies at the grafted tissue and a portion of non-keratinized mucosa were taken 12 months later. Histology showed keratinization of the newly formed epithelium, and interestingly a deep projection of epithelium into the connective tissue in almost all biopsies, sometimes with an enlargement and a cyst-like space. We conclude that chemical separation of epithelium and connective tissue is clinically feasible for connective tissue grafts and that the subepithelial connective tissue grafting technique should be modified to avoid this projection of epithelium.

Principles and methods of osseous reconstruction.

Osseous reconstruction must be predicated on the cellular mechanisms related to bone regeneration. The use of particulate bone and cancellous marrow in allogeneic cribs was developed with cellular physiology as its basis. Consequently, this form of graft system has repeatedly met the requirements for osseous reconstruction. Hyperbaric oxygen therapy, when utilized to improve local tissue physiology, offers the surgeon another modality to overcome some of the unique problems of the oncologic patient.