Effects of diode laser (810 nm) irradiation on root canal walls: thermographic and morphological studies.

This study investigated the thermal effects and the morphological changes after diode laser irradiation (810 nm) of root canals. Samples were irradiated at 2.5 W, 1,989 W/cm2 (group 2) and 1.25 W, 10 Hz, 994 W/cm2 (group 3), with group 1 being the control group of nonirradiated samples. The temperature rise was evaluated using an infrared thermographic camera, and the morphological changes were assayed by scanning electron microscopy (SEM). The SEM images revealed closed dentinal tubules, especially at the apical regions when compared with the control samples. The maximum temperature variations at the apical region were analyzed, and the resulting 95% confidence intervals of the medians (Wilcoxon) ranged from 1.6 to 8.6 degrees C (group 2) and from 1.2 to 3.3 degrees C (group 3). The results suggest that the diode laser can be used for endodontic purposes and show that the method is safe for periodontal tissues at the investigated parameters.

SEM evaluation of the interaction pattern between dentin and resin after cavity preparation using ER:YAG laser.

OBJECTIVE: The aim of this study was to describe the interaction pattern formed between dentin and resin on cavities prepared with an erbium laser (Er:YAG). The morphological aspect of the irradiated dentin after acid etching was also observed. METHODS: Ten dentin disks were obtained from fresh extracted third molars. Each disk received two cavities, one prepared with a conventional high-speed drill, while the other cavity was obtained by the use of an Er:YAG laser (KaVo KEY Laser, KaVo Co.). The laser treatment was performed with 250 mJ/pulse, 4Hz, non contact mode, focused beam, and a fine water mist was used. Five disks were prepared for morphological analysis of the acid etched dentin. The other five disks had their cavities restored with Single Bond (3M) followed by Z100 resin (3M). The specimens were observed under scanning electron microscopy after dentin-resin interface demineralization and deproteinization. RESULTS AND CONCLUSIONS: It was observed that the morphological characteristics of the acid-etched irradiated dentin were not favorable to the diffusion of monomers through the collagen network. The dentin-resin interfacial aspect of irradiated dentin, after acid etching, showed thin tags and scarce hybridization zones, which agreed with the morphology of the irradiated and acid-etched dentin substrate observed.

Laser Doppler Blood-Flow Signals from Human Teeth during an Alignment and Leveling Movement Using a Superelastic Archwire.

Objective. The purpose of this study was to examine alterations in blood-flow signals (BFS) from human teeth during an alignment and leveling phase (superelastic wire 0.014'') in a clinical orthodontic treatment using laser doppler flowmetry (LDF). Materials and Methods. Recordings were made in 12 maxillary left central incisors. The basal value of the BFS from each tooth (without orthodontic forces) was compared with the corresponding values of BFS during four periods of observation: 20 minutes, 48 hours, 72 hours, and one month after the activation of the orthodontic appliance. Results. Statistically significant decrease of BFS was observed at 20 minutes, 48 hours, and 72 hours (P < 0.05). No differences were found comparing BFS on day 30 and the corresponding basal values. Conclusion. Under real clinical conditions, a significant decrease in BFS was verified during the initial phase of the treatment, followed by a recovery on day 30.

Uso da fluxometria laser doppler em dentes decíduos traumatizados / Use of laser Doppler flowmetry in traumatized primary teeth

A necrose pulpar apresenta-se como uma sequela de difícil diagnóstico em dentes decíduos traumatizados e, muitas vezes, somente é detectada após o aparecimento de sinais como fístula, lesão periapical e reabsorção inflamatória externa. Os dados provenientes da anamnese, dos exames clínicos intra-bucal e radiográfico são limitados. Para melhorar esse diagnóstico, sugere-se a utilização de testes objetivos e não invasivos que avaliem a circulação sanguínea. O objetivo deste artigo foi apresentar um caso clínico que utilizou a Fluxometria Laser Doppler para auxiliar no diagnóstico de necrose pulpar do dente 51, em uma criança de 4 anos e 2 meses de idade atendida no Centro de Atendimento e Pesquisa de Traumatismos em Dentes Decíduos da Disciplina de Odontopediatria da Faculdade de Odontologia da Universidade de São Paulo. O dente 51 não apresentava sinais clínicos de necrose pulpar. O aparelho utilizado foi o Fluxômetro Laser Doppler (Moor Instruments, Axminster, Inglaterra), modelo moorLAB, com diodo laser emitindo no comprimento de onda de 780nm, potência de 1mW, banda Doppler fixada em 15kHz. Para o dente 51, foi obtido valor de fluxo de 2,1UA e o valor da variação percentual entre o dente 51 e 52 foi de 40,4%. Estes valores classificam o dente como desvitalizado. Assim sendo, foi possível realizar o diagnóstico de necrose pulpar utilizando a Fluxometria Laser Doppler como método auxiliar sem que houvesse sinais clínicos evidentes dessa sequela.

The diagnosis of pulp necrosis in traumatized primary teeth is difficult. Pulp necrosis is usually detected after signs like fistula, periapical radiolucency and inflammatory root resorption appear. Data from anamnesis and clinical and radiographic examinations are limited. In order to improve diagnosis, the use of objective and noninvasive tests that assess blood flow has been suggested. The aim of this article was to present a clinical case where laser Doppler flowmetry was used to aid the diagnosis of pulp necrosis in the upper right central incisor (tooth 51) of a child aged 4 years and 2 months seen at the Pediatric Dental Trauma Research Center of the Pediatric Department of FOUSP. Tooth 51 presented no clinical sign of pulp necrosis. The laser Doppler flowmeter (Moor Instruments, Axminster, England) model moorLAB was used with a 780 nm diode laser, cut-off frequency of 15 kHz and intensity of 1mW. The flow value of tooth 51 was 2.1UA and the percentage variation between teeth 51 and 52 was 40.4%. These values classify the tooth as devitalized. Therefore, it was possible to obtain a diagnosis of pulp necrosis using laser Doppler flowmetry in a tooth without evident clinical signs of this sequela.