Recent technological advances lead to an increase in the options for the treatment of the periodontal diseases. Lasers utilized for gingival soft tissue resurfacing mainly for esthetics purposes, require careful histopathological evaluation of the effects on tissue. Up to date no comparative clinical or histological studies have been performed, aiming at demonstration of the effects of laser irradiation on connective tissue, especially its most important component -- the collagen fibers. The alteration in the structures of this tissue plays the most important role in the healing process. The aim of the present study is to evaluate the influence of Erbium: YAG - Kesler's hand piece on gingival tissue. This handpiece is designed for gingival resurfacing, in cases of 'Gummy smile' and gingival pigmentation. The following irradiation parameters were used: energy per pulse -- 500 mJ, repetition rate 10 pps, spot size 3 mm. Gingival biopsies specimens of 10 patients, 6 with 'Gummy smile' and 4 with gingival pigmentation were examined before laser treatment, and at 7 and 14 days after laser treatment. The tissues were fixed in LNRS, embedded in paraffin, and sectioned into 5 micrometer thickness, dewaxed in xylol and stained with H&E and Picrosirius Red (PSR). The sections were examined by polarization microscopy. PSR is a collagen stain that differentiates collagen fiber density by the range of colors from green through yellow to red, and/or fiber size. This was utilized in the present study to evaluate the hypothesis that Erbium -- YAG (Er: YAG) laser energy is capable of remodeling the collagen fibers in the gingival connective tissue through a photothermal process. We found a significant difference between the structures of collagen fibers at the first week and at 14 days post treatment. In the normal gingiva the predominant polarization colors were in the red-orange range, signifying tightly packed, mature collagen. During the first postoperative week, collagen fibers exhibit mainly polarization colors in the green to green-yellow range implying less packed intermediate collagen fibers. After two weeks, collagen fibers required their preoperative polarizing texture. These findings strongly suggest that the 'quality' rather than the quantity of gingival collagen fibers play an important role in order for collagen shrinkage and reproduction to occur.

Numerous groups have recommended the use of the diode laser to decontaminate infected root and implant surfaces. The aim of this study was to show the outcome after laser assisted and conventional therapy of periimplantitis and periodontitis administering approved treatment protocols. Between 1994 and 1999 a total of 50 patients with periimplantitis (20) and periodontitis (30) were treated in two groups each. Clinical, microbiological and radiographic evaluation was performed before and 6, 12, 24, 36, 48 and 60 months after treatment. In addition to the conventional treatment protocol, flap surgery, the tooth or implant surface was decontaminated with a 810 nm diode laser using 1 Watt output for 20 sec (CW mode). All accessible surfaces were decontaminated at the follow up dates. In the periimplantitis group recurrence of the marker bacteria was higher and faster over time for the conventionally operated patients. Also the clinical and radiographic reevaluation showed significantly better results. The laser group of the periodontitis patients also showed significantly better outcome in terms of clinical evaluation, microbiological counts, radiographic evaluation and tooth loss. In comparison to other long term studies our results for the conventional therapy were adequate, the laser assisted therapy brought up significantly better and reproducible results.

Today more and more patients with bleeding disorder come to our office for treatment. The number of patients with therapeutic anticoagulation is growing steadily. Discontinuation of this therapy can often be crucial. On the other hand are oralsurgical procedures extremely sensitive to bleeding due to the constant presents of saliva with its high fibrinolytic activity. The aim of this study was to evaluate the use of a surgical diode (wavelength 810 nm) laser as accessory tool in the treatment of patients with hemorrhagic diathesis. Enclosed in the study were 123 patients with: (1) Coumarintherapy, a Quick test ratio of 15 - 25%; (2) More than 300 mg of ASS/die; (3) Hemophilia, a factor activity under 35%; (4) Morbus Werlhof with less than 30000 thrombocytes. 179 Surgical procedures: (1) Tooth extraction 86%; (2) Apexectomy 3%; (3) Tumorexcision 9%; (4) Curettage and flapsurgery 1%; (5) Gingivectomy 1%. All procedures were laser-assisted with a diode laser emitting 810 nm. The glass fibers used were depending on the procedures either 200, 400, or 600 micron. No coagulating agents or tissue adhesives were used in addition. The postoperative outcome and complication rates were compared to substitution therapy and tissue adhesives. Laser-assisted treatment of these patients shows a high predictability and success rate leaving out side effects of drugs and human cryoprecipitates. Postoperative impairment is diminished.

The objective of this study was to compare the penetration effect of the near and mid-infrared laser radiation. For this reason the Er:YAG, Nd:YAG, and alexandrite laser systems were used in the experiments. The spread of the laser radiation energy in the hard dental tissue surrounding the root canal was evaluated and the possible bactericidal effect of these various laser wavelengths was analyzed. During the measurements, three experimental arrangements were used. The energy transport through the tooth tissue was observed for the frontal and side experimental layout. It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully, and the Nd:YAG is partly absorbed in the root canal's wall. On the other hand, it was proved that the alexandrite laser radiation spreads through the canal system space and leaks into the surrounding tooth tissues. All laser radiation can be efficiently used for killing dental bacteria but the spreading of their radiation in the tooth tissues is different.

We have studied photodynamic action of He-Ne laser radiation on cultures of Staphylococcus (strain 209 P), Streptococcus anhaemolyticus, and total microflora of dental deposit been sensitized by methylene blue. The concentration of the dye was varied from 0.001% to 0.1%, radiation power density was 100 mW/cm². Irradiated strain was put into thermostat for 24 hours, then the number of colonies was counted and analyzed.

While earlier periodontal investigations have proved the frequency doubled Alexandrite laser to eliminate efficiently and selectively dental calculus as well as bacteria the aim of this study was to demonstrate the safety of this laser for removal of dental calculus with respect to the dental pulp. Four adult Labrador dogs were treated with a frequency doubled Alexandrite laser (laboratory prototype, q-switched, fiber guided, wavelength 377 nm, pulse duration 1 microsecond, pulse repetition rate 70 Hz, water cooling) to remove dental calculus. After performing a modified Widman flap procedure the buccal surface of nine teeth in the lower and upper right jaw were irradiated for four minutes per tooth. Three different laser fluences up to four times higher than the fluence required for calculus removal were used (1.5, 3 and 6 J/cm²). At three other sites of the right jaw deep cavities were prepared with a dental drill and filled with compomere material (Dyract^R, Dentsply, Germany) to serve as a positive control with regard to possible pulpal reactions. The corresponding teeth of the lower and upper left jaw served as controls. Animals were sacrificed one day, one week, four weeks and six weeks after treatment. Teeth were separated, fixed in formalin and decalcified. After embedding and sectioning the histological sections were stained and investigated by a totally blinded investigator (P.A.R). Histological investigations revealed that irradiation with the frequency doubled Alexandrite laser for periodontal treatment with fluences of 1.5 J/cm² -- those fluences necessary for the selective removal of dental calculus and microbial plaque -- had no adverse side effects to the pulpal tissues. Moreover this pulpal safety study demonstrated that even applying fluences two or four times higher than those suggested for calculus removal do not lead to observable changes or alterations in the odontoblast cell layer or the pulpal tissues. No inflammatory reactions and no differences between irradiated and control teeth occurred, while the positive controls showed reactions in the odontoblast cell layer and the connective pulpal tissue.

In clinical praxis we must treat patients with some relative or absolute contraindications every day. Need of hospitalization, antibiotics, hemostyptics and complex examinations makes dentoalveolar and maxillofacial surgery in those cases quite expensive. Combination of Nd:YAG and Er:YAG laser gives us new possibilities. We can help some untreatable patients or transfer care from hospital to dental office. We have been trying to solve contraindications for laser therapy five years. In the center of our work are disorders of blood coagulation, immunity and metabolism. Nd:YAG laser is very useful in coagulation and vaporization of dental gum hypertrophies, benign and malign tumors in case of chronic anticoagulation therapy and immunosupress / in combination for example- after heart transplantation /. Special chapter is the care of patients with disseminated tumors. Er:YAG laser large solve big lesions because of minimal invasivity of course but for small benign tumors are recidives is ideal. Better and quicker healing make new standard of patients' cooperation. Generally fashionable and more comfortable laser treatment minimize need of general anesthesia. After five years we use complex laser therapy in our routine. Aim of our new work is to find ideal combination of cutting lasers to minimize classical complications of laser surgery / carbonization, long and secondary healing /.

Periodontal therapy aims in a most sufficient cleaning of tooth surfaces from supra- and subgingival calculus. As a standard dental procedure teeth are treated with ultrasonic devices. The competence of the frequency doubled Alexandrite laser for a highly effective and selective removal of calculus has been repeatedly proved. Aim of the study presented here was to determine the efficiency at simulated clinical conditions of the frequency doubled Alexandrite laser (laboratory prototype, q-switched, fiber guided, wavelength 377 nm, pulse duration 1 microsecond, pulse repetition rate 70 Hz, water cooling) by quantifying it's calculus removing efficiency. The evaluated data were compared to those obtained with an ultrasonic calculus remover. In the first part of the study sample material consisted of 23 pigs' jaws. They were divided into two groups. The teeth of one group were cleaned on their buccal surfaces using an ultrasonic device (Sonosoft Lux, KaVo, Biberach, Germany; tip #9). Than hand-guided cleaning was performed until no further improvement in cleanness was visible. Cleaning time was measured. Photographic documentation was taken before and after the treatment. The teeth in the second group were cleaned engaging a frequency doubled Alexandrite laser. Treatment time was measured and photographs were taken in the same way. In the second part of the study 21 surfaces of human teeth set up in an artificial pocket model were treated with both systems again. Measurements followed the same protocol. The results strongly support the use of the frequency doubled Alexandrite laser for calculus removal.

One of the most important difficulty in the periodontal disease treatment resides in the impossibility of decontamination of roots just affected by the periodontal disease through mechanical tools. Manual dental scaling results in the amorphous material without continuity solution due to the dental cut, denominated smear layer. The main purpose of the present study was to evaluate the structure of the radicular surface using two methods for periodontal treatments: manual and mechanical associated to the irrigation with water and with EDTA (ethylene diamine tetracycline acid), followed by the application of the Er:YAG laser or the same without laser. Thirty teeth were selected with periodontal involvement. The radicular surface was scraped with ultrasound and planed vigorously, with manual instrumentation. The teeth were divided ramdomically in several groups: GI -- control, just manual instrumentation and water irrigation; GII -- manual instrumentation, EDTA irrigation; GIII -- manual instrumentation, EDTA irrigation, Er:YAG laser irradiation; GIV -- manual instrumentation, laser irradiation; and, GV -- manual instrumentation, laser irradiation and EDTA. Kruskall Wallis statistical test was applied and shows that there was not significance difference at the level of 5% among the five groups, however, when the groups were compared in pairs, GII X GIV and GII X GV shows difference in 5%, and GI X GII, difference at 1% level. The results show equivalence around the used methodology.

This study was carried out with a 41-year-old female patient with facial paralysis as a consequence of facial nerve injury during neurosurgery. Low-reactive level laser treatment (LLLT) with a diode laser of 830 nm, 40 mw, continuous wave, spot area 3 mm², was applied twice a week for 2 weeks, then 1 weekly session following up to 30 sessions, resulting in about 80% improvement of the motor activity.

LLLT has been used successfully in biomedicine and some of the results are thought to be related to cell proliferation. The effects of LLLT on cell proliferation is debatable because different studies found either increase or decrease on proliferation of cell cultures. Cell culture is an excellent method to assess both effects and dose of treatment. The aim of this study was to assess the effect off 635 and 670 nm laser irradiation of H.Ep.2 cells In Vitro using MTT. The cells were obtained from SCC of the larynx were routinely processed from defrost to the experimental condition. Twenty four hours after transplantation the cells were irradiated with doses ranging from 0.03 a 0.6 J/cm² during seven days. The results showed that 635 nm laser light does not stimulate significantly the proliferation of H.Ep.2 cells in doses ranging from 0.04J/cm² to 0.488J/cm². However 670 nm laser irradiation resulted in an increased cell proliferation when compared to both control and 635 nm irradiated cells. It is concluded that irradiation of H.Ep.2 cells with 670 nm laser results in an increased cell proliferation; best observation of cell proliferation was found on 670 nm laser irradiated cultures exposed from doses of 0.075 J/cm²; both dose and wavelengths are factors which may affect cell proliferation of H.Ep.2 cells; doses of 635 nm laser light up to 0.48J/cm² did not interfere with H.Ep.2 cell proliferation; and that the MTT was effective on the detection of H.Ep.2 cells proliferation on both irradiated and non-irradiated cell cultures.

Proliferative lesions of the oral cavity are very frequent and depend on various factors such as: traumatism, irritating conditions, medications, heredity and others. In this work we present the CO₂ laser ablation as a very conservative method to treat these lesions. In the 5 cases discussed in this work, the gingival overgrowth lesions induced an important dental misalignment, which culminated in severe functional disorder. After previous biopsy to establish the diagnostic (Gingival Fibromatosis, 4 cases -- and Miofibroma, one adult female), the treatments were performed with a CO₂ laser (Sharplan 40C) under local anesthesia with lidocaine 2% without vasoconstrictor. The patients were submitted to 3 to 6 sessions with tissue vaporization of 8 to 12 w continuous swift-focused mode, with an interval of 4 weeks between each session. The results were evaluated photographically before each laser application. The use of this technique assures a very satisfactory dental alignment associated to good functional rehabilitation.

The use of lasers for cleaning, shaping and disinfecting root canals must not produce heat which damages periapical tissue and alveolar bone. The aim of the present study was to determine the increase of external temperature at the apical surface of the root canal after Er:YAG laser irradiation with a 250 micrometer diameter fiberoptic guide with and without distilled and deionized water at 3 different total energies. Thirty single-rooted teeth were instrumented to #25 K-file using distilled and deionized water for irrigation. They were divided into three groups according to total energy (15J, 30J and 45J with 15 Hz and 140 mJ per pulse). Each group was irradiated with water and then without water. The increase in temperature at the apical root surface was measured with a multimeter and a thermocouple. Changes in apical temperature were significantly different in all groups (p less than 0.01; 15 J less than 45 J less than 30 J). Less time was necessary for return to initial room temperature at 15 J. We conclude that in vitro use of the Er:YAG laser (total energy of 15, 30, and 45 J) increased external apical root temperature and that the root canal must be filled with distilled and deionized water to reduce the risk of an increase in temperature.

Chemical action of bleaching agents applied to tooth surface is accelerated by increase in temperature. This in vitro study measured the temperature rises on the surface and in the pulp of teeth during whitening using a diode laser, a plasma arc curing (PAC) light and conventional curing lights. Extracted, non-carious single-rooted teeth were exposed to PAC light and laser at times ranging from 10 to 60 seconds and energy ranges of 2 W, 4 W, and 6 W, and to low-intensity curing lights from 1 to 4 minutes. Maximum temperature rises were analyzed for both pulpal and surface temperature. Diode laser exposures at 2 W for all times and at 4 watts for 10 seconds and PAC light exposures at 10 seconds all produced acceptably safe pulpal rises equivalent to conventional light-curing exposures. Exposures at these settings also attained surface temperature rises that were significantly higher than those using conventional light-curing. The diode laser demonstrated bleaching results equivalent to the PAC light, and both were achieved in significantly less times than conventional light- curing.

Improving our knowledge of the morphology, composition and properties of the dentin, enamel, and the dentin-enamel junction (DEJ) is vital for the development of improved restorative materials and clinical placement techniques. Most studies of dental tissues have used light microscopy for characterization. In our investigation, the spectroscopic properties of normal and non-carious transparent human root dentin, and the dentin-enamel junction were investigated using emission imaging microscopy, and micro-spectroscopy. Experimental results reveal new information on the structural and biochemical characteristics of these dental tissues.

Adhesion of endodontic sealers to root canal walls is a property material must have to promote a hermetic seal of the root canal. The present study evaluates the effect of Er:YAG laser applied to human dentine in vitro on adhesion of Grossman, Endomethasone, N-Rickert and Sealer 26 root canal sealers. The crowns of 40 human molars were cut on the occlusal side until a flat dentine surface was obtained. The teeth were divided into 2 groups: group 1, saline solution; group 2, irradiation with Er:YAG laser (KaVo Key Laser 2; 11 mm focal distance, perpendicular to the dentine surface, 4 Hz frequency, 200 mJ energy, 62 J total energy and 313 pulses, one minute application time and 2.25 W power). Five repetitions were done for each sealer and each group. An Instron universal testing machine was used for the adhesion test.The results showed a statistically significant difference at 1% for the sealers and the dentine surface treatments. Sealer 26 showed the best adhesion both with laser application and saline. Application of Er:YAG laser did not alter the adhesion of Grossman, N-Rickert or Endomethasone sealers compared to saline; however, laser application increased the adhesion of Sealer 26.

There is a need for further improvement on the level of apical sealing. The use of lasers on apical surgery is still not fully understood, however some good results have been reported. The aim of this study was to assess the effect of the use of the CO₂ laser following conventional apicoectomy and retrofilling with glass ionomer using different combinations of power and types of emission 'In Vitro.' Seventy extracted human upper anterior teeth were used on this study. The teeth after conventional apicoectomy were retrofilled with Vitremer^TM. The samples were randomized into seven groups of 10, Group I acted as negative control. Groups II, III and IV were lased on defocused mode with superpulsed CO2 laser on CW with power output of 0,5; 3 and 7 Watts during 5 seconds respectively. Groups V, VI e VII were lased on defocused mode with continuous emission on CW mode with power output of 1, 10 and 20 Watts during 5 seconds respectively. All specimens were immersed on 2% Methylene Blue solution during 48 h, washed in running tap water and longitudinally sectioned. Three calibrated examiners regarding apical infiltration graded the samples. The results showed difference between groups, where Group II showed smaller level of apical infiltration. It is concluded that improving on apical sealing is better achieved by using 0.5 W on superpulsed on CW.

Ankiloglossia or frenum lingual alteration leads to important tongue dysfunction, which, besides discomfort and pain during function, is generally responsible for the difficulty to express specific phonemes. In other cases, a heavy muscular abnormal attachment of labial frenum can promote clinical changes. In such case, an eventual orthodontic therapy is indicated and aesthetic alteration is observed. In both cases, surgical removal is indicated. The surgery, for prevention purposes, must be done as soon as possible, but considering that the majority of patients are young (5 - 14 years old), difficulties during surgery are expected to occur. Correction of speech or orthodontic dysfunction in advanced ages is much more complex and difficult than in childhood. In the present work we demonstrate that the use of CO₂ lasers in these cases are advantageous and simple. The laser energy causes the tissue of the frenum to open in the classic shape with no bleeding and no need for suture, reducing the risk of cross- contamination and of postoperative infection. Scarring and other complications are also minimized. A CO₂ laser (continuous, 8 W, 10.6 micrometers) was used assisted with local anesthesia. The major advantage of laser is the possibility of its application in early ages, preventing further problems.

The aim of this study was to investigate the antibacterial effect of a diode laser in deep root canal dentine. The microbial colonization of root canal dentine can lead to failures in conventional endodontic treatment if only an inadequate bacterial reduction is achieved through canal treatment and chemical disinfection. 100 micrometer, 300 micrometer and 500 micrometer bovine dentine slices obtained by longitudinal sections were sterilized and inoculated on one side with an Enterococcus faecalis suspension. Laser radiation was performed on the opposite side with the diode laser, emits light at 810 nm and operates in the continuous wave mode (cw). Radiation was performed using a 400 micrometer tapered fiber tip at an angle of approx. 5 degrees to the surface over a period of 30 s. The output power at the distal end of the tip was 0.6 watt. The bacteria were then eluted through vibration and cultured on blood agar plates. The colony count reflected the antibacterial effect of laser radiation as a function of the layer thickness. A mean bacterial reduction of 74% was achieved even with a 500 micrometer thick slice. This investigation indicates that the diode laser can support the bacterial reduction in endodontic treatment.

An overview of the basic mechanisms of IR laser ablation of dental enamel is presented. Enamel is a highly structured tissue consisting of an heterogeneous distribution of water, mineral, protein and lipid. Absorption bands of water and carbonated hydroxyapatite can be selectively targeted from 2.7 to 11-micrometer via several laser wavelengths. Mechanistic differences in the nature of ablation and the varying surface morphology produced can be explained by the microstructure of the tissue. Suggested criteria for the choice of the optimum laser parameters for clinical use, the influence of plasma shielding and the role of exogenous water on the mechanism of ablation are discussed.

Three dimensional model calculation on the basis of Finite Elements were carried out to simulate the heat distribution process under IR laser ablation. Several models were built up to study the time behavior of the heat stored in the walls of a laser induced crater. The time resolved data show a concentration of heat in the center of the crater and a strong thermal stress in the corner ring of the cylindrical crater. The results calculated for the thermal properties of dentine are compared with experimentally observed two dimensional temperature distributions monitored by an IR camera.

There has been great interest in the potential use of a laser to replace the dental handpiece (drill). Ideally a laser emitting radiation that is absorbed strongly by both the water and hydroxyapatite in teeth, would be a more efficient laser. Previous investigators showed that the 9.3 and 9.6 micron wavelength bands of the CO₂ laser contain hydroxyapatite absorption peaks. For this study, human patients who were to have teeth removed for either orthodontic or periodontal reasons were used. A total of 16 teeth were irradiated. The number of teeth treated per patient varied from 1 - 4. The laser used was a prototype CO₂ laser (ESC Medical Systems, Yokneam, Israel). The CO₂ laser emits 50 mJ 60 microsecond-long pulses of 9.6 micrometer radiation in a beam focused to a 300 micrometer diameter (i/e²) spot. The pulps in both the laser and handpiece prepared holes appeared similar and had no apparent inflammation or vascular changes. It appears from this small sample of laser treated human teeth that this laser has an equal effect to the dental pulpal tissue when compared to the dental handpiece.

Enamel caries lesions on extracted teeth were ablated with a pulsed Nd:YAG or Er:YAG laser. Tissue ablation was accompanied by a 'popping' sound (the photoacoustic response). Analysis of the photoacoustic response yields insights into the laser/tissue interactions. Fourier Transform Infrared (FTIR) Spectroscopy of lesions before ablation show a strong protein component associated with organic material (i.e., bacteria). Following ablation this protein component is absent.

The Er:YAG laser has been proposed as a useful tool for caries removal. In this study, we report a prospective parallel controlled study of the Dental Erbium Laser for caries removal and cavity preparation in pediatric patients. A total of 92 patients in two separate sites were randomized to treatment in a 2:1 ratio laser to conventional dental drill. The subject ages ranged from 4 to 18 years with a mean of 10.5 years with an even distribution by gender. The mean recorded treatment energy for caries removal was 147 mJ and for cavity preparation was 170 mJ. There were no significant differences in pain reported by the drill or laser treated subjects, and no complications or adverse events were reported after treatment or at any other interval during the study. The determination of success was based on four criteria: (1) acceptable caries removal, (2) acceptable cavity preparation, (3) maintenance of pulp vitality, and (4) restoration intact and serviceable. Using these criteria, it was found that all 32 of the drill procedures were a success and 59 out of 60 laser procedures were a success. This study shows that the Erbium-YAG laser is suitable for caries removal and cavity preparation in children.

Human enamel tissue has been exposed to Nd:YAG pulsed laser operating in nanosecond and picosecond pulse regime. Morphological comparison between the regimes of operation have been investigated special attention to preservation of structure was taken. Trains of pulses with picosecond duration from a Q-switched and mode-locked Nd:YAG laser and pulses with nanosecond duration from a Q-switched Nd:YAG laser both operating at 15 Hz kept at in same average power, were focused in human sound molar during 30 s. Drilled holes with different morphological characteristics were observed for several laser intensity regime. Enamel surfaces were examined in a scanning electron microscope and their morphological characteristics compared. Contrast between the morphology of the enamel when treated with different powers and lasers pulse duration were observed. Picosecond pulses promote a better defined material removal while nanosecond pulses at the equivalent average power level causes a large intermediate modified region between ablated and normal tissue, as well as a complete superficial modification of the existent original structure. Results show an important correlation between the surface morphology and the pulse width of the lasers, giving indications towards the use of ultrashort laser pulses in Dentistry.

High intensity infrared light from the pulsed Nd:YAG dental laser is absorbed by pigmented carious enamel and not absorbed by normal enamel. Therefore, this system is capable of selective removal of surface enamel caries. Safety and efficacy of the clinical procedure was evaluated in two sets of clinical trials at three dental schools. Carious lesions were randomized to drill or laser treatment. Pulp vitality, surface condition, preparations and restorations were evaluated by blinded evaluators. In Study 1 surface caries were removed from 104 third molars scheduled for extraction. One week post-treatment teeth were extracted and the pulp was examined histologically. In Study 2 90 patients with 422 lesions on 376 teeth were randomized to laser or drill and followed for six months. There were no adverse events and both clinical and histological evaluations of pulp vitality showed no abnormalities. Caries were removed in all conditions. A significantly greater number of preparations in the drill groups vs. laser groups entered dentin (drill equals 11, laser equals 1, p less than 0.001). This indicates that the more conservative laser treatment removed the caries but not the sound enamel below the lesion.

The objective of this study was to measure the peripheral thermal damage produced during the laser ablation of alveolar bone and dentin for clinically relevant IR laser systems. Previous studies have demonstrated that a char layer produced around the laser incision site can inhibit the wound healing process. Moreover, in the case of dentin, a char layer is unsightly and is difficult to bond to with restorative materials. Thermal damage was assessed using polarized light microscopy for laser pulse widths from 500 ns to 300 microseconds at 2.94 micrometer and 9.6 micrometer. Water- cooling was not employed to alleviate thermal damage during the laser irradiation. At 9.6 micrometer, minimal thermal damage was observed for pulse widths on the order of the thermal relaxation time of the deposited laser energy in the tissue, 3 - 4 microseconds, and peripheral thermal damage increased with increasing pulse duration. At 2.94 micrometer, thermal damage was minimal for the Q-switched (500 ns) laser system. This study shows that 9.6 micrometer CO₂ laser pulses with pulse widths of 5 - 10 microseconds are well suited for the efficient ablation of dentin and bone with minimal peripheral damage. This work was supported by NIH/NIDCR R29DE12091.

The objective of this study was to measure the residual heat deposition during laser ablation at those IR laser wavelengths best suited for the removal of dental caries. The principal factor limiting the rate of laser ablation of dental hard tissue is the risk of excessive heat accumulation in the tooth, which has the potential for causing damage to the pulp. Optimal laser ablation systems minimize the residual energy deposition in the tooth by transferring deposited laser energy to kinetic and internal energy of ejected tissue components. The residual heat deposition in the tooth was measured at laser wavelengths of 2.79, 2.94, 9.6 and 10.6 micrometer and pulse widths of 150 ns - 150 microsecond(s) . The residual energy was at a minimum for fluences well above the ablation threshold where it saturates at values from 25 - 70% depending on pulse duration and wavelength for the systems investigated. The lowest values of the residual energy were measured for short (less than 20 microseconds) CO₂ laser pulses at 9.6 micrometer and for Q-switched erbium laser pulses. This work was supported by NIH/NIDCR R29DE12091 and the Center for Laser Applications in Medicine, DOE DEFG0398ER62576.

Caries detection currently occupies a good deal of attention in the arena of dental research for a number of reasons. In searching for caries detection methods with greater accuracy than conventional technique researchers have used a variety of optical methods and have increasingly turned to the use of lasers. Several laser-based methods have been and are being assessed for both imaging and disease quantification techniques. The phenomenon of fluorescence of teeth and caries in laser light and the different effects produced by different wavelengths has been investigated by a number of workers in Europe. With an argon ion laser excitation, QLF (Quantified Laser Fluorescence) demonstrated a high correlation between loss of fluorescence intensity and enamel mineral loss in white spot lesions in free smooth surface lesions, both in vitro and in vivo. Recent work with a red laser diode source (655 nm), which appears to stimulate bacterial porphyrins to fluoresce, has demonstrated that a relatively simple device based on this phenomenon can provide sensitivity and specificity values of the order of 80% in vitro and in vivo for primary caries at occlusal sites. In vitro studies using a simulated in vivo methodology indicate that the device can produce sensitivity values of the order of 90% for primary caries at approximal sites.

Occlusal surface caries are very difficult to diagnose at early stages, special difficulties are observed when the lesion is formed bilaterally in the pits and fissures walls. Preventive measures have been a constant concerning in the attempt to reduce the installation and progression of incipient occlusal decays. The early carious lesions detection through conventional diagnosis methods are questionable because they can end up with a risk of a false-positive or false-negative diagnosis. Using 22 teeth in vitro, premolars and molars, which suggested carious lesions, the exams were made by 3 examiners calibrated through pre-determined scores. The utilized methods were: GI -- visual inspection, GII -- tactile inspection (explorer probe), GIII -- conventional radiographic exam, GIV -- digital radiographic exam (Digora for Windows 1.51 and 1.51N, Soredex-orion Co.), GV -- low intensity laser for diagnosis (DIAGNOdent, KaVo, Germany) and GVI -- histologic section. The examiners did not communicate among themselves during the exams. There were significant statistical difference among the evaluated methods. Under Friedman statistical test, GI, GIII and GIV were different from GV at the 0.1% level; when we have compared GII with GV, we observed statistical difference at the 1% level. In conclusion, GV was highly statistically different from the others groups, it means that the low intensity laser for diagnosis was the most sensible method to detect decayed tissue.

Development of dental caries is associated with the loss of minerals and change in the enamel structure. In this study, we have measured and compared reflectance spectra of sound and carious enamel, to investigate its utility in detection and analysis of dental caries. One hundred twenty, 3-mm diameter human enamel cores, with no sign of fluorosis, tetracycline stain, hypoplasia, fracture and restorations, were prepared. The enamel surfaces then were ground and polished. Specimens were placed on a fitted holder with either black or white color for background, with no fluorescence. The baseline spectra were measured using a spectrophotometer with enclosed diffused illumination. Spectra measured from 380 to 780 nm at 5 nm intervals. All measurements were corrected to compensate for the spectrum of illumination. The specimens were divided into two groups and exposed to a demineralizing solution, for 48 and 96 hours, respectively. Reflectance spectra of specimens were measured following lesion induction. All specimens were sectioned and analyzed by transverse microradiography (TMR), where lesion depth and mineral loss ((Delta) Z) were measured. Dimensionality of multi-spectral data was reduced through its conversion to L*a*b* color coordinates and principal component analysis (PCA). Multiple linear regression analysis showed low correlation between L*a*b* and lesion depth and mineral loss. PCA analysis showed higher correlation coefficient, compared to L*a*b*. Preliminary results of this study suggest that multi-spectral measurement and analysis of the tooth surface could be useful in predicting the depth and severity of an early carious lesion.

A new method for detection and quantification of natural incipient caries lesions, the Quantitative Light-induced Fluorescence method (QLF), has recently been developed. The aim of this study was to test the repeatability and reproducibility of the analytical part of the method. In vivo captured images (CCD-video camera, Panasonic WV-KS 152, with an argon ion laser as light source) of 15 different incipient caries lesions on smooth surfaces were analyzed by three analysts. The images were analyzed three times in a randomized order, twice for the first reconstructed area (P₁A₁ and P₁A₂), and then once for a second one (P₂A₁). Three parameters were measured, lesion area (mm²), average change in fluorescence (%), and maximum change in fluorescence (%) in the lesion. Repeated measures ANOVA were used to calculate the intra-, and inter-examiner reliability. Intra-examiner reliability for all three analysts showed an intra-class correlation coefficient, R, between 0.93 and 0.99 (for the analyses with the first patch, P₁A₁ and P₁A₂, as well as between the first and the second patch, P₁A₁ and P₂A₁). Inter-examiner reliability showed an inter-class correlation coefficient, R, between 0.95 and 0.99 (for analyses P₁A₁, P₁A₂ and P₂A₁). It was concluded that the Quantitative Light- induced fluorescence method showed excellent repeatability and reproducibility concerning the analytical part of the method.

In vitro research has demonstrated the ability of argon laser irradiation to reduce demineralization or loss of tooth structure. This clinical pilot study was conducted to investigate the effectiveness of this procedure in vivo. Using the Ogaard model of producing demineralization, the experimental teeth were irradiated with argon laser (primarily 488 nm and 514 nm) of 250 mW, approximately 12 J/cm² fluence, prior to banding. Polarized light evaluation of the sectioned, extracted teeth showed reduced demineralization in the experimental teeth as compared to the bilateral control teeth. Lower powered argon laser irradiation significantly reduced demineralization clinically.

Pit and fissure caries remain the most common form of caries and are difficult to detect and prevent. In this study, the hypothesis that specific IR laser irradiation used for ablation of the occlusal pits and fissures can also inhibit caries progression was tested. To do so on the pits and fissures, higher fluences were used to test this hypothesis than were used by previous studies. Occlusal pits and fissures of extracted human teeth were ablated with Er:YAG ((lambda) equals 2.94 micrometer, 200 microsecond pulse duration), Er:YSGG ((lambda) equals 2.79 micrometer, 200 microseconds pd) or CO₂ ((lambda) equals 9.6 micrometer, 5 microseconds pd) laser irradiation (n equals 10 per group). 'Enamelplasty' performed on non-irradiated pits and fissures using a high- speed 1/4 round carbide bur served as the control group. After laser ablation in the test groups and enamelplasty in the control group, artificial caries-like lesions were created by subjecting the teeth to pH cycling. Thin (80 micrometer) sections were then analyzed utilizing polarized light microscopy and transverse microradiography (TMR). The relative mineral loss, or (Delta) Z values, measured in vol.% x micrometers and (standard deviations) were 2074(929) for bur control, 1053(787) for Er:YAG, 583(261) for Er:YSGG, and 1047(416) for CO₂ groups. Laser ablation of the pits and fissures resulted in a 50% inhibition of caries progression for both CO₂ and Er:YAG and 72% caries inhibition for Er:YSGG. All laser groups were significantly superior in caries inhibition at a statistical level of P less than 0.01 compared to the control (bur) group. Results indicate that these lasers can not only conservatively prepare pits and fissures but, in addition, can have marked caries preventive effects.

The evaluation of microleakage is a method conventionally used to evaluate the composite restoration in cavities prepared by laser or conventional drill. The samples were five sound molar human extracted teeth with cavity preparation Class V in each surface (buccal, lingual, mesial and distal) divided in: GI -- cavity preparation with Er:YAG laser, adhesive agent Single Bond (3M), composite Z100 (3M) color A2; GII -- cavity preparation laser, 35% phosphoric acid etching, adhesive, composite; GIII -- cavity preparation with a drill, adhesive, composite; GIV -- cavity preparation with a drill, acid etching, adhesive, composite. The samples were sealed with a coating of nail varnish except on the area of the restoration and immersed in 50% aqueous solution of silver nitrate for 24 hours while kept in darkness. Samples were rinsed, soaked in photorevealing solution and exposed to fluorescent light for 6 hours. After, they were embedded in epoxy resin and sectioned longitudinally using the diamond saw microtone under running water. The specimens were observed under optical microscopy and the results were analyzed under Kruskall Wallis resulting in difference statistically between GI X GIV at the 5% level; and under Mann-Whitney resulting non-difference statistically between groups divided in cervical or occlusal walls.

In this research results of approbation of the optical PNC- method in dental clinic are presented. The PNC-method was used for diagnostics stages of caries (initial, moderate and deep). The variant of the PNC-method adapted for dental diagnosis is based on simultaneous analyses the following parameters by special algorithms: backscattering and probing radiation, stimulated (endogenous) autofluorescence of caries induced batteries. Analyze of informational signals show good correlation with tooth morphological structure and concentration of anaerobic microflora in hearth of caries lesion. Investigation was performed in vivo on 101 tooth in conditions of typical dental clinic. Comparison of the PNC- method with visual and X-ray ones, which are widely used in clinical practice was made. Preliminary results showed high potential of usage the PNC-method in clinical practice and more high probability of initial caries detection (up to 100%) in comparison with X-ray method (approximately 75%). In cases when X-ray diagnosed absence of initial caries, more sensitive the PNC-method detected initial caries in stage 'white lesion.'

The results of hard tooth tissues research by the optical PNC- method in experimental and clinical conditions are presented. In the experiment under 90 test-sample of tooth slices with thickness about 1 mm (enamel, dentine and cement) were researched. The results of the experiment were processed by the method of correlation analyze. Clinical researches were executed on teeth of 210 patients. The regions of tooth tissue diseases with initial, moderate and deep caries were investigated. Spectral characteristics of intact and pathologically changed tooth tissues are presented and their peculiar features are discussed. The results the optical PNC- method application while processing tooth carious cavities are presented in order to estimate efficiency of the mechanical and antiseptic processing of teeth. It is revealed that the PNC-method can be used as for differential diagnostics of a degree dental carious stage, as for estimating of carefulness of tooth cavity processing before filling.

Caries prevention is a goal to be achieved by dentist in order to promote health. There are several methods used to detect dental caries each one presenting advantages and disadvantages, especially regarding hidden occlusal caries. The improvement of laser technology has permitted the use of laser fluorescence for early diagnosis of hidden occlusal caries. The aim of this study was to assess the efficacy of the use of 655 nm laser light on the detection of hidden occlusal caries. Forty molar teeth from patients of both sexes which ages ranging from 10 - 18 years old were used on this study. Following manufacture's instructions regarding the use of the equipment, the teeth had their occlusal surface examined with the DIAGNOdent. Twenty six of 40 teeth had hidden occlusal caries detected by the DIAGNOdent. However only 17 of these 26 teeth showed radiographic signs of caries the other 9 teeth showed no radiological signs of the lesion. Radiographic examination was able to identify 34,61% of false negative cases. This means that many caries would be left untreated due to the lack of diagnosis using both visual and radiographic examination. The use of the DIAGNOdent was effective in successfully detecting hidden occlusal caries.

The morphological complexity of the occlusal surface of deciduous molar teeth is considered as a factor to increase vulnerability to caries lesion. Occlusal surface of these teeth shows sulcus, pits and fissures which allow retention of both micro-organisms and food debris which make them more susceptible to caries. In the last decades there was a significant reduction on caries of smooth surface but not on the occlusal surface where dentinal caries develops under fissures which are apparently caries-free under eye observation. This is known as a hidden caries. The occlusal surface of sound extracted deciduous molar teeth were examined using a 655 nm diode laser (DIAGNOdent - KaVo) in order to detect hidden caries. When there was indication of a hidden caries, the area was examined using SEM and confirm or not the diagnosis. The authors concludes that the diagnosis of caries using 655 diode laser is reliable and precise method.

Several studies during the last 30 years have demonstrated the potential of laser pre-treatment of enamel to inhibit subsequent acid-induced dissolution or artificial caries-like challenge in the laboratory. The aim of the present study was to examine the difference between primary and permanent teeth enamel in the prevention of caries-like lesion progression by long pulsed TEA-carbon dioxide (CO₂) laser irradiation in vitro by means of a pH-cycling model. Thirty caries-free permanent tooth crowns and forty caries-free primary tooth crowns were cleaned and varnished with acid-resistant varnish, leaving one exposed window of enamel. Five groups of 10 enamel samples were irradiated in their individual windows by a TEA- CO₂ laser at 9.6 micrometer wavelength, 25 pulses per spot, 5 microsecond pulse duration, 0.5,10,15 Hz repetition rates, 1774 micrometer beam diameter and 1.0, 1.5 J/cm² per pulse fluence. All teeth, including 2 non-irradiated control groups, were subjected to pH-cycling to produce artificial caries-like lesions. Results were assessed by cross-sectional microhardness testing. Inhibition of caries progression of from 29% to 57% was achieved over the range of laser conditions tested. At the same irradiation conditions (repetition rate: 10 Hz, fluence: 1.5 J/cm²), the inhibition rate in primary teeth enamel was 54% compared with 49% in the permanent teeth enamel (significant at p less than 0.05). Safety and efficacy studies will be required before these promising laboratory results can be applied in clinical practice.

Shortened curing times for light activated composites have been sought for many years. This study was conducted to compare diametral tensile strengths (DTS) of four composites cured with three light curing devices: halogen lamp, argon laser and plasma arc. Twelve samples were made for each composite and light curing device for a total of 192 samples. Diametral tensile strengths were measured on the Instron testing machine and statistical analysis performed using ANOVA and Fisher PLSD. Results indicate there wee no statistical differences in the DTS of the composites tested as a result of the curing light source. The Plasma Arc curing light was able to produce statistically equal diametral tensile strengths in 3 and 6 seconds as compared to the argon laser in 10 seconds and the halogen light in 40 seconds. Supported in part by Dental Medical Diagnostics.

Ever since the laser was introduced in dental medicine, there has been a constant discussion about its use in caries prevention. Various studies have already illustrated the possible uses of CO₂ and argon lasers in this field of dentistry. The aim of the present study was to examine the Er,Cr:YSGG laser with regard to potential in reducing the acid solubility of dental enamel. Thirty freshly extracted bovine incisor teeth were prepared for this purpose. The crowns of the teeth were covered with hard wax, leaving a standardized test area free. The test specimens were then divided into three groups. The test area was uniformly irradiated with 2.7 J/cm² in the first test group and 6.5 J/cm² in the second test group. The third test group was left untreated (control group). Demineralization of the teeth was performed over a period of 24 hours in acetate buffer solution (0.1 mol/l) with a pH value of 4.5 and a temperature of 37 degrees Celsius. The calcium content of the solution was subsequently determined by flame photometry. The results confirm a significantly lower calcium content in the test group exposed to radiation of 6.5 J/cm² (p less than 0.025). Dental enamel seems to have increased acid resistance following irradiation with the Er,Cr:YSGG laser.

Secondary caries (SC) is the most common reason for restoration failure. The purpose of this study was to evaluate the Quantitative Light-Induced Fluorescence (QLF) method for monitoring therapies to inhibit SC progression. Forty-eight human teeth with resin restorations were demineralized for 4 days in a microbial caries model. Half of each specimen was then covered with an acid-resistant varnish to maintain the baseline lesion, and treated (group 1: non-treated control; group 2: chlorhexidine varnish for 24 h; group 3: fluoride varnish for 24 h; group 4: APF topical fluoride gel for 4 min), prior to being demineralized for 4 more days. Specimens were analyzed by QLF, sectioned, stained with Rhodamine B, and analyzed with a confocal microscope (CLSM) for lesion depth. The QLF results indicated that the control group was significantly (p less than 0.05) different (i.e., lesions progressed) from groups treated with fluoride (groups 3 and 4; lesions remineralized). All other group comparisons were not significantly different. Results obtained from CLSM analysis were similar to the ones obtained with QLF, except that lesions in group 2 were significantly deeper than the ones in the fluoride groups. Results suggest that the QLF method has a clear potential for monitoring remineralizing therapies for SC.

Various materials and techniques have been investigated in order to minimize or eliminate microleakage in composite restorations. The CO₂ laser (10.6 micrometer) removes the smear layer and creates an irregular surface able to promote micromechanical retention for adhesive restorative materials. Forty Class V cavities were performed with high-speed drill in 20 extracted human molar and randomly divided into 4 different groups: Group 1 -- CO₂ laser (3 W, 2 Hz, 50 ms) and after 37% phosphoric acid etching on dentin and enamel surface; Group 2 -- 37% phosphoric acid etching and after CO₂ laser; Group 3 -- CO₂ laser; Group 4 -- 37% phosphoric acid etching. The cavity restored with composite resin (Z-100) and thermally stressed (700 cycles, 5 - 55 degree Celsius). After the samples were impermeabilized, immersed in 50% silver nitrate solution for 8 hours and sectioned with Isomet saw. The teeth were exposed to Photoflood light (G.E.) for 5 minutes to reveal the dye. Leakage was observed under stereomicroscope and evaluated with scores. Results were analyzed with ANOVA (p greater than 1%) and Tukey's test (p equals 5%) and showed significant lower microleakage in the group treated only with CO₂ laser and phosphoric acid etching alone (group 3 and 4) than groups treated with phosphoric acid and CO₂ laser together (group 1 and 2).