Laser-tissue interactions

Since the development of the ruby laser by Maiman in 1960, there has been great interest among dental practitioners, scientists, and patients to use this tool to make dental treatment more pleasant. Oral soft tissue uses are becoming more common in dental offices. The possible multiple uses of lasers in dentistry, beyond soft tissue surgery and dental composite curing, unfortunately, have not yet been realized clinically. These include replacement of the dental drill with a laser, laser dental decay prevention, and laser decay detection. The essential question is whether a laser can provide equal or improved treatment over conventional care. Safe use of lasers also must be the underlying goal of proposed or future laser therapy. With the availability and future development of different laser wavelengths and methods of pulsing, much interest is developing in this growing field. This article reviews the role of lasers in dentistry since the early 1960s, summarizes some research reports from the last few years, and proposes what the authors feel the future may hold for lasers in dentistry.

Lasers in dentistry.

This article reviews the current and potential applications of laser technology in nonsurgical therapy for the treatment of periodontal diseases. Based on its various characteristics, such as ablation or vaporization, hemostasis, and sterilization effect, laser treatment may serve as an adjunct or alternative to conventional, mechanical periodontal therapy. The Carbon dioxide (CO2) and the Neodymiumdoped:Yttrium-Aluminum-Garnet (Nd:YAG) lasers were previously approved for soft tissue treatment in periodontics (1, 2, 4), because of their superior ability of soft tissue ablation, accompanied by strong hemostatic and bactericidal effects (6, 37, 143, 170, 218). However, when these lasers are applied to dental hard tissues the result is major thermal damage, especially at a high-energy output, rendering them unsuitable for hard tissue treatment (56, 214). Recently, the Erbium-doped:Yttrium-AluminumGarnet (Er:YAG) laser was developed in dentistry (71, 85, 87). As it is capable of ablation in both soft and hard tissues, the Er:YAG laser can be used for periodontal hard tissue treatment such as root surface debridement, as well as soft tissue management (78). The use of lasers within the periodontal pocket has become a topic of much interest and is a promising field in periodontal therapy. This article deals with recent advances in nonsurgical laser therapy for periodontal disease, and will briefly describe the advantages and disadvantages of various laser types.

Lasers in nonsurgical periodontal therapy.

Background: Despite the large number of publications, there is still controversy among clinicians regarding the application of dental lasers to the treatment of chronic periodontitis. The purpose of this review is to analyze the peer-reviewed research literature to determine the state of the science concerning the application of lasers to common oral soft tissue problems, root surface detoxification, and the treatment of chronic periodontitis.Methods: A comprehensive computer-based search combined the following databases into one search: Medline, Current Contents, and the Cumulated Index of Nursing and Allied Health. This search also used key words. In addition, hand searches were done for several journals not cataloged in the databases, and the reference lists from published articles were checked. All articles were considered individually to eliminate non-peer-reviewed articles, those dealing with commercial laser technology, and those considered by the author to be purely opinion articles, leaving 278 p...

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Lasers in Periodontics: A Review of the Literature

Effective ablation of dental hard tissues by means of the erbium-doped:yttrium-aluminum garnet (Er:YAG) laser has been reported recently, and its application to caries removal and cavity preparation has been expected. However, few studies have investigated the capability of the Er:YAG laser to treat caries. In the present study, the effectiveness of caries removal by using an Er:YAG laser in vitro was compared with that of conventional mechanical treatment. Thirty-one extracted human teeth with root caries were used. Half of the caries in each tooth was treated with the Er:YAG laser, and the other was removed with a conventional bur or was left untreated as a control. Laser treatment was performed by means of a combination of contact and non-contact irradiation modes with cooling water spray, with a new fiber delivery and contact probe system. Conventional bur treatment was conducted by means of a low-speed micromotor. Measurements of the time required for caries removal, histopathological observations of...

Comparison between Er:YAG Laser and Conventional Technique for Root Caries Treatment in vitro

Lasers in dentistry: new possibilities with advancing laser technology?

Background: The removal of calculus and plaque is an essential component of a therapeutic approach to control periodontal disease. Er:YAG laser scaling was recently introduced as an alternative to conventional scaling procedures. In this histological study, the effects of laser instrumentation of diseased root surfaces are compared to mechanical removal of plaque and calculus with ultrasonic instruments and scalers. Methods: Areas of subgingival calculus were identified on 40 freshly extracted human teeth. Each of these areas was randomly divided into 2 equal parts. The control site was treated either with scaling and root planing or with an ultrasonic instrument. The test site was cleaned using an Er:YAG laser according to the manufacturer's instructions. The end point of debridement was the inability to mechanically or visibly detect any remaining calculus. After pre- and postsurgical photographs and impressions for scanning electronic microscopic investigation, a plastic embedding technique was used to...

Er:YAG Laser Scaling of Diseased Root Surfaces

The aim of the present study was to investigate laser-fluorescence effects on the root surface. The possibility of detecting subgingival calculus should be evaluated to control complete calculus removal after scaling and root planing. Twenty freshly extracted human teeth, partially covered with calculus on the root surface, were fixed on a translation stage. The specimens were irradiated by light from a laser source (diode laser, 0.05). After scaling, when no debris remained at the root surface, laser-fluorescence values decreased significantly (p < 0.05). The histological findings supported the clinical results. In conclusion, the present study indicates that laser-fluorescence values on the root surface are strongly correlated to the presence of calculus. This fluorescence effect can basically be used to develop a new detecting system for subgingival calculus in periodontal pockets.

The possibility of detecting subgingival calculus by laser-fluorescence in vitro.

Haemostatic and aseptic effects and intricate cut geometry are beneficial aspects of non-contact laser osteotomy. Collateral thermal damage, however, has severely limited the use of conventional lasers. The purpose of this study was to test the side effects on bone after cutting it with short CO2 laser pulses and simultaneous application of a fine air-water spray. The 10.6 microm CO2 laser emitted 80 micros pulses of 46 mJ energy, f=100 Hz, focused to a spot diameter of 130 im. Scan rate amounted to 40 mm/s. To approximate live conditions 10 samples of cortical bone and 10 rib segments were prepared immediately after sacrificing of pigs. A reference cut with a bandsaw and three laser cuts with an increasing number of beam passes (4, 16, 64) were performed on each sample. Half of the samples were decalcified in EDTA. The others were embedded in plastic to cut non-decalcified sections. The laser incisions were not accompanied by carbonisation. The incisions with slightly convergent walls were 150 im wide. The depths of the cavities increased with the number of the beam passes from approximately 0.5 mm (4 passes) to 3 mm (64 passes). At the border of the incisions two narrow zones of damage were noted: an amorphous intensively stained zone of 1-3 microm width and a wider, also sharply demarcated but faintly stained zone of 7-10 microm. A broader zone of about 50 microm was characterised by empty lacunae and osteocyte damage. These effects were not predictable; intact osteocytes were also observed near to the cut surface. Polarised light microscopy showed no alterations in the inorganic structure of the bone at the cut borders. The histological results indicated only minimal damage to bone ablated at the specified parameters. The described laser procedure might have advantages over mechanical instruments.

Osteotomy with 80-micros CO2 laser pulses--histological results.

Background: Hyaluronic acid (HA) has shown anti-inflammatory effects in gingivitis therapy. The potential benefits of local subgingival application of HA adjunctive to scaling and root planing (SRP) were evaluated in this study. Methods: Twenty patients with chronic periodontitis were included in this split-mouth study. Sulcus fluid flow rate (SFFR) and sulcus bleeding index were monitored at baseline and after 1, 2, 3, 4, 5, 6, and 12 weeks; probing depth and clinical attachment level were monitored at baseline and 6 and 12 weeks. Subgingival plaque samples were also taken at these same three appointments to determine the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola. All patients were treated with full-mouth scaling and root planing (SRP); in addition, an HA gel was administered subgingivally in the test sites every week for 6 weeks. Results: An improvement of all clinical variables was observed (P <0.0...

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis.

Matthias Frentzen

Papers

Lasers in dentistry: new possibilities with advancing laser technology?

Er:YAG Laser Scaling of Diseased Root Surfaces

The possibility of detecting subgingival calculus by laser-fluorescence in vitro.

Osteotomy with 80-micros CO2 laser pulses--histological results.

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis.