Dental-Plaque Decontamination around Dental Brackets Using Antimicrobial Photodynamic Therapy: An In Vitro Study.

BACKGROUND: In orthodontic therapy, the enamel around brackets is very susceptible to bacterial-plaque retention, which represents a risk factor for dental tissues. The aim of this study was to evaluate the effect of methylene blue and a chlorophyllin-phycocyanin mixture, used with and without light activation, in contrast with a 2% chlorhexidine solution, on Streptococcus mutans colonies. METHODS: Twenty caries-free human extracted teeth were randomized into five groups. A Streptococcus mutans suspension was inoculated on teeth in groups B, C, D, and E (A was the positive-control group). Bacterial colonies from groups C, D, and E (B was the negative-control group) were subjected to photosensitizers and 2% chlorhexidine solution. For groups C and D, a combined therapy consisting of photosensitizer and light activation was performed. The Streptococcus mutans colonies were counted, and smears were examined with an optical microscope. Two methods of statistical analysis, unidirectional analysis of variance and the Tukey-Kramer test, were used to evaluate the results. RESULTS: A statistically significant reduction in bacterial colonies was detected after the combined therapy was applied for groups C and D, but the most marked bacterial reduction was observed for group D, where a laser-activated chlorophyll-phycocyanin mixture was used. CONCLUSIONS: Photodynamic therapy in combination with methylene blue or chlorophyllin-phycocyanin mixture sensitizers induces a statistically significant decrease in the number of bacterial colonies.

A Comparative Analysis Regarding the Osseointegration of Immediate Loaded Implants Using Two Different Implant Site Preparations: Erbium:Yttrium-Aluminum-Garnet Laser Versus Surgical Conventional Way-An In Vivo and Histological Animal Study.

Objective: The aim of the study is to evaluate the possibility of preparing the implant site using the erbium:yttrium-aluminum-garnet (Er:YAG) laser scanner prototype and to reduce and/or eliminate time between primary (mechanical) stability and secondary (biological) stability, looking to the immediate occlusal loading in a single implant. Background: A prerequisite for successful osseointegration is the establishment of direct bone-to-implant contact without interposition of nonbone or connective tissue. In recent years, the use of laser radiation was presented as an alternative/adjunctive treatment for bone tissue ablation due to vaporization of the tissues in the absence of a smear layer. Methods: The experimental protocol included six minipigs, which underwent tooth extraction, followed (after 2 months) by implant bed preparation in two methods: using a conventional bur kit and using an Er:YAG laser scanner (X runner) protocol. Four implants were placed in positions 34, 37, 44, and 47 on each animal. The animals underwent the second surgical procedure for bone sample collection (including the implant) before their sacrifice at 45-60-90-120 days. The newly formed bone was evaluated on the bone samples using histological examination and quantitative evaluations of different histological parameters based on microscopical analysis. Results: The results that we obtained allow some interesting comparison in terms of different bone composition, depending on the method of implant site preparation and on healing periods. Moreover, it was possible to compare the bone composition, at different time stages, of implant sites prepared in the same way. Conclusions: Our research allowed us to demonstrate that the use of Er:YAG laser compared with traditional drill leads to the presence of a greater share of lamellar bone and a lower necrotic share in the implant site. We also showed the possibility of applying immediate occlusal loading on an in vivo animal model.

Alveolus soft and bone tissue regeneration after laser biomodulation - a histological study.

Functional and esthetic recovery of the patient after tooth extraction is a concern in the nowadays-dental medicine. Immediate implant placement in fresh sockets in posterior sides of the jaws is difficult because of the high amount of bone loss and the disparity between the diameter of the alveolus and the implant. The objective is to evaluate the effect of laser biomodulation alveolar socket healing process of healthy patients. A number of 36 molars have been extracted due to advanced caries lesions from the same dental arch but on opposite sites. Laser irradiation was performed on one side after extraction; the other side was used as control. An Epic-X laser diode (Biolase) Indium-Gallium-Arsenide-Phosphorus (In-Ga-As-P) 940 nm was used in a continuous mode, 0.9 W, 36 J for 80 seconds, daily exposure, in the first seven days after extraction. Specimens of soft and hard tissue were surgically incised and removed by a 4.4 mm diameter trepan from the extraction sites, eight weeks after the surgical procedure. The specimens were prepared by use of two staining procedures: Hematoxylin-Eosin (HE) and Mallory's trichrome. The prepared slides were examined under Leica DM750 optical microscope, 5× and 10× magnification. Laser biomodulation therapy accelerates bone formation by increasing osteoblastic activity. The histological study demonstrates early new bone formation, the regeneration effects in fresh intact bony alveolus compared with the soft and bone regeneration level of non-treated fresh alveolus. Laser biomodulation therapy accelerates soft tissue regeneration and bone formation.

Effect of the laser beam on implant site preparation: a preliminary pilot study.

The aim of this preliminary study is to histologically evaluate the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser on soft and hard tissues during implant bed preparation, in comparison with bur and cutter in order to observe the following aspects: (i) the shape of the cavity, (ii) the presence of debris, and (iii) structural modification of the cell architecture. Bone temperature changes during the preparation of the implant bed were also measured in order to evaluate thermal damage on soft and hard tissues. Er:YAG laser, Fotona X-Runner scanner and circular cutter of 5 mm diameter were compared using an in vitro model. Implant bed preparations were performed in bovine rib bone (hard tissue) and tongue muscle (soft tissue) tissues. Results of the study show that in all bur samples were present more debris and more blood cells than in laser samples, which, according to the rules of healing processes, can be a negative factor for the osseointegration process. Regarding the thermal effects on soft tissue, they were present when using MAX mode, but absent when using quantum square pulse (QSP) mode. A preliminary conclusion emphasizes the use of laser to prepare the implant site without debris formation. Nowadays, is not still present a laser device that can overtake the technical limitations of the laser scanner (i.e., deepness control and scanner movement during the preparation of the holes, etc.).

Fluorescence influence on screening decisions for oral malignant lesions.

OBJECTIVES: The aim of the present study was to assess the capability of the low-cost VELscope device to visualize the tissue auto-fluorescence of potentially malignant oral lesions and to establish the diagnostic accuracy, sensitivity, and specificity of this method when validating the retrieved data through the gold standard, i.e., histological examination. PATIENTS, MATERIALS AND METHODS: Eighteen patients were evaluated by conventional oral examination (COE) followed by direct visual fluorescence evaluation (DVFE) using VELscope. Areas clinically suspicious detected by COE or with positive DVFE (visual fluorescence loss) were further investigated using surgical biopsy. RESULTS: Eight positive biopsies for malignant lesions were detected by COE and DVFE. Only one positive biopsy for a premalignant lesion was not in accordance with COE and DVFE. One lesion identified on the VELscope and COE as a non-malignant lesion was confirmed by the biopsy. Therefore, the VELscope system had a sensitivity of 94.44% and a specificity of 100% in discriminating in situ normal mucosa from carcinoma or from invasive carcinoma, compared with histology. The predictive positive value was 100% and the negative predictive value was 50%, with a 95% confidence interval (CI). CONCLUSIONS: DVFE allows for a simple and cost-effective margin determination, in order to perform the detection and screening of oral precancerous and early cancerous disorders. It was found that the VELscope system could not fully replace the histopathology procedure. Nonetheless, the study demonstrated its usefulness for clinical examination, monitoring oral lesions, and guiding the biopsy. Therefore, this method may add sensitivity to the oral tissue examination and be an effective adjunct for high-risk patients.

Scanning electron microscopy evaluation of the root canal morphology after Er:YAG laser irradiation.

The current limits of the endodontic disinfection strategies are not only a result of bacterial biofilm growth mode inside the root canals, they are equally due to the anatomical complexity of the root canal system, of its structure, of the dentin composition and of the factors associated with chemical disinfectants. One of the major problems is the fact that a great part of the endodontic anatomy remains uninstrumented after conventional treatment and even the accessible parts of the root canals are covered in smear layer, which results as a by-product of the instrumentation and acts as a barrier for irrigants, medication and even influencing the quality of the endodontic filling. Therefore, strategies in advanced disinfection in endodontics are developed and tested in order to meet these challenges. The present study aims to assess the possibility of improving the debridement of the root canals by using erbium-doped yttrium-aluminum-garnet (Er:YAG) laser radiation. We used extracted teeth, which were subjected to the conventional treatment protocol and then divided into three study groups: the negative control group and two other groups, which were exposed to laser radiation using two energy levels. Scanning electron microscopy (SEM) revealed the efficiency of the laser aided treatment versus the conventional methods of cleaning and disinfection of root canals.