Davor Katanec

Scanning electron microscopic study of dentin lased with argon, CO2, and Nd:YAG laser

The purpose of this study was to compare morphological changes on the dentin surface induced by laser light delivered perpendicular or parallel to the dentin surface. The surface of the dentin slices and the root canal walls were lased with argon, CO2, and Nd:YAG lasers. When the laser beam was parallel to the dentin, the effects of the laser energy ranged from no effect to eroding and melting of the smear layer and dentin in the samples. When the laser beam was perpendicular to the surface, all three lasers produced well-shaped craters. From this, it was concluded that the angle of the laser beam in relation to the target surface can be a deciding factor of how much energy will be absorbed by the dentin and consequently of the morphological changes induced by the laser.

Comparison of Er:YAG Laser and Surgical Drill for Osteotomy in Oral Surgery: An Experimental Study

PURPOSE High-energy lasers have been proposed as an alternative to the conventional surgical drill in oral and maxillofacial surgery. The aims of this study were to compare thermal changes of the bone surface, procedure time, and volume of the removed bone after drilling with an erbium (Er):yttrium-aluminum-garnet (YAG) laser versus a low-speed surgical drill. The bone sections were observed under light microscopy and examined histologically. MATERIAL AND METHODS Thirty bone blocks were prepared from porcine ribs. On each block 2 holes (tunnel preparations) were performed using a low-speed, 1.0-mm-wide, surgical pilot drill and an Er:YAG laser (pulse energy, 1,000 mJ; pulse duration, 300 μs; frequency, 20 Hz). The temperature induced by the preparation techniques was measured using an infrared camera. The removed bone volume was calculated by a modified mathematical algorithm. The time required for the preparation was measured with a digital stopwatch and a time-measurement instrument integrated within the computer program. The cortical and spongiose surfaces of the specimens were examined microscopically and histologically under a light microscope with a high-resolution camera. RESULTS The Er:YAG laser removed significantly more bone tissue than the drill (P < .01) in a significantly shorter time (P < .01). The temperature was statistically lower during the laser preparation (P < .01). Cavities prepared with the laser were regular with clear sharp edges and knifelike cuts. In the drill group, the preparations exhibited irregular edges full of bone fragments and fiberlike debris. Histologic examination of the laser sides showed a 30-μm-thick altered sublayer. The tissue in the drill group was covered with a smear layer without any alterations. CONCLUSIONS The Er:YAG laser produced preparations with regular and sharp edges, without bone fragments and debris, in a shorter time, and with less generated heat. Thermal alterations in the treated surface were minimal.

Application of Diode Laser in Oral and Maxillofacial Surgery

Laser devices have gained in importance since the eighties and they are often claimed to be omni-use instruments. Though many applications turned out to be almost impracticable, an unaltered interest in laser technology has remained to date. The broad spectrum of applications for the diode laser means that it is now the most widely used device in laser dentistry. Diode lasers offer an interesting – but not unlimited – field of application in modern dentistry: oral and maxillofacil surgery and endodontic surgery.

Current Concept of Densitometry in Dental Implantology

In the literature densitometric measurements of the alveolar bone are commonly used prior to dental implants placement, as a main part of treatment planning and making the correct indications for dental implant therapy. Different assessment tools for the osseointegration quality evaluation have been proposed in everyday clinical usage. Current method for assessment of outcome of the osseoinegration process of alveolar bone around inserted dental implants is based on densitometric analysis. We have made the modification of conventionally used CADIA (computer assisted densitometric image analysis) and DIGORA software for densitometric measurement. The main task was measurement of bone density around inserted dental implants using the implants as a stepwedge. Main difference between new method and convetional stepwedge-based densitometry is the absence of stepwedge key. Usually, for the stepwedge the aluminium key is used. Digital intraoral periapical radiographs are commonly used for densitometric measurements of the alveolar bone with dental implants. Radiographs were taken following surgery during the wholw follow-up period, depends of certain method. Those RVG images were automatically digitalized and stored in the computer with the processed software DIGORA and adjusted to this research, in measuring bone density around inserted dental implant, not only in certain contours, but also in the precise positions. 12 points with diameter of 1mm on correctly allocated positions on cervical, middle and apical part of newly formated bone, around inserted implant, were measured. The measured densities were obtained automatically due to performed software package, after entering the RVG image. Positions of the 12 points were in advance specified and inserted in the software database, so the measurements on all the implants were every time in the same points. Three of those points served as a correction factors, and they were positioned on different parts of the implant. First correction point was placed in the apical part of the implant, were density of the gray shadows was highest ; second correction point was placed in the middle part of the implant were was already the perforation of the implant for the screw (density of gray shadows have medium intensity), and third correction point was placed on the cervical part of the implant, in the position were the crown screw is attached to the implant (density of gray shadows have minimal intensity) (Figure 1). Correction points served for revision of density changes in measured points which occurred in discontinuity on the x-rays (distortion on x-rays at each of four images in the series of the follow-up, differences in the exposition on the same series of four images that were taken in the follow-up period). Measuring points were positioned: first point was placed 1mm apical of the implant in the middle line, and the rest of 8 points were placed on the precise positions between previously defined screw threads, on each side of the dental implant. All the received densitometry results were processed and afterward used for the evaluation of osseointegration precess after different surgical techniques in dental implantology. In this book chapter this modified method of stepwedge-free densitometry in dental implantology will be clearly explained, making the emphasis on densitometric assessment of some surgical techniques and methods and determination of their clinical values. Assorted clinical cases of each method (maxillary sinus floor elevation techniques, splitting technique of the alveolar ridge, bone grafting procedures and flapless technique of dental implants placement)will be documented. Densitometric comparison between different maxillary sinus floor elevation techniques (lateral approach versus transcrestal approach) will also be shown through this new method. Densitometric assessment of flapless technique and determination of its clinical values in comparison with two-stage dental implant technique through computerized densitometric analysis will also be shown. Improved understanding of this current densitometric analysis may ensure increased bio-safety and predictability during implant placement using different surgical procedures in dental implantology, and may improve clinical decision-making and long-term implant success.