Lasers in dentistry

Current status of Er:YAG laser in periodontal surgery

Lasers have numerous advantageous tissue interactions such as ablation or vaporization, hemostasis, bacterial killing, as well as biological effects, which induce various beneficial therapeutic effects and biological responses in the tissues. Thus, lasers are considered an effective and suitable device for treating a variety of inflammatory and infectious conditions of periodontal disease. Among various laser systems, the Er:YAG laser, which can be effectively and safely used in both soft and hard tissues with minimal thermal side effects, has been attracting much attention in periodontal therapy. This laser can effectively and precisely debride the diseased root surface including calculus removal, ablate diseased connective tissues within the bone defects, and stimulate the irradiated surrounding periodontal tissues during surgery, resulting in favorable wound healing as well as regeneration of periodontal tissues. The safe and effective performance of Er:YAG laser-assisted periodontal surgery has been reported with comparable and occasionally superior clinical outcomes compared to conventional surgery. This article explains the characteristics of the Er:YAG laser and introduces its applications in periodontal surgery including conventional flap surgery, regenerative surgery, and flapless surgery, based on scientific evidence from currently available basic and clinical studies as well as cases reports.

Photodynamic therapy adjuvant to non-surgical periodontal therapy: Systematic review of randomized clinical trials

OBJECTIVES

To systematically evaluate randomised controlled trials (RCTs) on whether adjuvant application of antimicrobial photodynamic therapy (aPDT) through the technique of irradiation in the external region of the periodontal pocket with optic-fibre tip offers benefits to scaling and root planning (SRP).

METHODS

Five databases were searched by two independent reviewers according to pre-specified eligibility criteria up to April 2023. No restrictions regarding date of publication, language and minimum follow-up period were imposed. The Cochrane Collaboration's Risk of Bias tool (RoB 2.0) was used for quality appraisal and Grading of Recommendations, Assessment, Development and Evaluation for assessing the certainty of evidence.

RESULTS

A total of 1388 publications were identified and reviewed for eligibility. Four of them fulfilled the inclusion criteria. The sample consisted of a total of 83 patients with periodontitis. In these, 330 periodontal sites were evaluated. The clinical findings of the majority of the included studies demonstrated that patients who received the association of aPDT + RAR with the protocol evaluated here, obtained clinical results similar to patients who received only the SRP alone. In none of the evaluated RCTs, clinical advantages were observed that would categorise this aPDT protocol as superior to conventional treatment.

CONCLUSION

Applying aPDT after SRP with external irradiation of the periodontal pocket does not seem to result in any clinical benefit compared to the use of SRP alone in patients with periodontitis.

Technical Note on Vestibuloplasty around Dental Implants Using Erbium YAG Laser-Assisted Periosteal Fenestration (LA-PF)

Various vestibuloplasty techniques have been reported to increase the attached mucosa (AM) and vestibular depth around dental implants. However, these surgical methods have disadvantages, such as limitations in manipulation, necessity of suturing, postoperative discomfort, swelling, and pain. This study aimed to evaluate the efficacy of laser-assisted periosteal fenestration (LA-PF) in treating patients with a shallow vestibule and insufficient AM around dental implants. LA-PF was performed using an Erbium YAG laser (Er:YAG laser). First, a partial-thickness, apically positioned flap was used. A horizontal periosteal fenestration was performed using an Er:YAG laser to expose the bones. Periosteal suturing was not required. After 12 months, sufficient AM and deep vestibules were obtained and maintained. Thus, the LA-PF technique may be a simple and predictable treatment modality for shallow vestibules with insufficient AM around dental implants.

To Evaluate the Clinical Efficacy of 940 nm Diode Laser and Propolis Gel (A Natural Product) in Adjunct to Scaling and Root Planing in Treatment of Chronic Periodontitis

Background

Recently, various adjunctive treatment options along with Scaling and root planing (SRP) such as local drug delivery, medications, and lasers have been introduced for the treatment Chronic periodontitis (CP) but literature is limited.

Aim

To evaluate the clinical efficacy of 940 nm diode laser and propolis gel in adjunct to Scaling and root planing (SRP) in the treatment of CP.

Subjects and Methods

Randomized clinical trial was conducted among 30 CP patients with a probing depth of ≥5 mm was allocated randomly into Group 1 (SRP), Group 2 (SRP + diode laser), and Group 3 (SRP + propolis gel). Plaque index, gingival index, pocket probing depth, and clinical attachment level were assessed at baseline, one and three months. Data analysis was performed using SPSS version 17 for windows, and statistical techniques employed were repeated measures by using One-way ANOVA, Tukey's HSD, independent t-test, and paired t-test.

Results

Post-treatment sites among all the three groups showed statistically significant reduction in Periodontal index (PI), Probing pocket depth (PPD), and Clinical attachment level (CAL), whereas gingival inflammation was significantly reduced in groups 2 and 3 from baseline to one and three months. On comparison, at baseline, all clinical parameters were statistically insignificant. At one month, the mean difference of PI, Gingival index (GI) was statistically significant between group 1 and 2 whereas the mean difference of CAL and PPD were statistically significant from group 1 to groups 2 and 3.

Conclusions

Lasers with SRP were greatly effective in reducing gingival inflammation, PPD, and CAL. Propolis gel also offered encouraging and promising clinical results but still needs further long-term studies to establish its precise role in the treatment of CP.

Efficacy of Er, Cr: YSGG laser phosphoric acid gel and Riboflavin activated by Photodynamic therapy on enamel reconditioning rebonded to metallic brackets: An Invitro study

AIM

To evaluate the shear bond strength (SBS) and failure percentage of rebonded metallic brackets after employing various enamel-reconditioning methods (37% phosphoric acid, sandblasting, Er, Cr: YSGG laser, and Riboflavin (RF).

MATERIAL AND METHODS

After sample size calculation, a sum of 40 non-carious, non-traumatically extracted and sound human premolar teeth were collected and the enamel surface was prepped by etching, washing, and drying. The enamel surface was primed with a bonding agent and light cured, later brackets were bonded via composite. After bonding, bracket debonding was begun using a Weingart plier and the enamel surface was reconditioned before rebonding. Samples were divided into four (n=10) reconditioning groups at random and subjected to SB with 90-μm alumina particles group 1, Er, Cr: YSGG laser group 2, 37% PA (control) group 3, and RF group 4 respectively. After reconditioning, brackets were rebonded to the enamel surface via an adhesive system and composite. Later, samples were exposed to the universal testing machine for SBS analysis, and bond failure analysis was performed by using an adhesive remnant index (ARI). Statistical analysis was executed by one-way ANOVA and Post Hoc Tukey multiple comparison tests at a statistically significant level of p ˂ 0.05.

RESULTS

The SBS analysis showed that the highest SBS of rebounded brackets was exhibited by 37% phosphoric acid (control) and the lowest SBS by sandblasting enamel surface with 90-μm alumina particles for enamel prior rebonding. However, Er, Cr: YSGG laser and RF activated by PDT validated comparable SBS results to control (p>0.05). Contrarily, sandblasting with 90-μm alumina particles showed a statistically significant difference from other analyzed reconditioning groups (p<0.05). Deliberating failure rate analysis by ARI index, the most eminent failures predicted among groups were scored between 0 and 1 except for sandblasting which majorly resulted in a score of 2 showing cohesive type failure.

CONCLUSION

Chromium-doped erbium, yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser, and Riboflavin activated by photodynamic therapy have the potential to be used as an alternative to 37% phosphoric acid for enamel surface reconditioning before the rebonding metallic bracket.

Potential of Lasers in the Realm of Aesthetic Dentistry: A Narrative Review

In contemporary dental practice, patients' interests are taken into account in terms of function and appearance. The importance in everyday circumstances, current advertising, and the media in general highlight their effect on an attractive appearance. Many academics in the field of dental aesthetics have stated equivocally that when examining the impact of tooth appearance necessitates a multidisciplinary approach. Laser technology in cosmetic dentistry is in its early stages of development and has a lot of potential in the future. Also, with expanding use of lasers in clinical dentistry, treatment planning and prognosis will see a significant improvement in the future. The introduction of this technology has turned dentistry into a painless, bloodless field with increased predictability and instant outcomes. Furthermore, these techniques can help a cosmetic dentist regulate gingiva and osseous outlines with greater creativity in the pursuit of aesthetic dental principles with more efficient use of patient time. Even from the patient standpoint, the reduced requirement for suturing and faster healing times improves case acceptance and enables the increased demand for aesthetic dentistry. The resolution of this paper is to deliver an overview of various laser applications in aesthetic dentistry and its pros and cons over the conventional approaches.

Air Quality in a Dental Clinic during Er:YAG Laser Usage for Cavity Preparation on Human Teeth-An Ex-Vivo Study

Chemical air pollution in dental clinics consists of the emission of gases and particulate matter (PM), both generated by dental equipment and tooth tissues. One basic application of Erbium Laser devices is cavity preparation on human teeth due to its strong affinity to water and hydroxyapatite. The objective of this study was the evaluation of indoor air quality during the application of an Er:YAG laser, as a dentin removal instrument, in a Dental Clinic. Particulate Matter (PM) was measured using the standard method of EN legislation. In order to measure total Volatile Organic compounds (VOCs), a portable monitor was used. In the first experiment, PM10 and PM2.5 concentrations were increased by approximately 10 and 15 times, respectively. From the second experiment it can be concluded that neither of the measured particle concentrations exceeded the recommended indoor limit values while windows were open, although laser influence was still detectable. Within the limitations applied herein, it was found that Er:YAG laser activity for hard dental tissue removal was associated with high PM and TVOCs concentration values in the working environment, under insufficient or no ventilation. Physical ventilation in the aforementioned setting proved to be an important key factor in improving air quality, as both PM and TVOCs concentrations decreased significantly.

Influence of different irrigation regimens on the dentinal tubule penetration of a bioceramic-based root canal sealer: a confocal analysis study

This study aims to assess the efficacy of various irrigation protocols on the dentinal tubule penetration of a bioceramic-based endodontic sealer. Sixty-four single-rooted extracted human mandibular incisors were used. After instrumentation, teeth were randomly divided into the following four groups (n = 16 each) according to the final irrigation technique: group 1, conventional endodontic needle (CEN); group 2, EndoActivator (EA); group 3, Er,Cr: YSGG laser; group 4, XP-endo Finisher (XPF). The root canals were finally irrigated with 17% EDTA and 5.25% NaOCl for 1 min (min) respectively. The teeth were then obturated with Endosequence BC Points and rhodamine B dye-labeled BC Sealer. After 2 weeks, 1-mm-thick transverse sections were cut 2 and 5 mm from the apex, and examined by confocal laser scanning microscopy at 5 × magnification. The total percentage of sealer penetration (TPSP), sealer penetration area (SPA), and maximum sealer penetration depth (MSPD) was measured. Data were analyzed by Kruskal-Wallis, Dunn's multiple comparison, and Wilcoxon tests, with significance set at P < 0.05. At 2 mm level, no significant differences were detected among the groups (P > 0.05). At the 5 mm level, the XPF group showed significantly higher values for both TPSP and SPA in comparison with the Er,Cr: YSGG laser and CEN groups (P < 0.05), but no significant difference was observed with the EA group. The choice of different final irrigation techniques can affect dentinal tubule penetration.

Ablation Precision and Thermal Effects of a Picosecond Infrared Laser (PIRL) on Roots of Human Teeth: A Pilot Study Ex Vivo

BACKGROUND/AIM

Picosecond infrared laser (PIRL) was investigated regarding its possible therapeutic application in cutting dental roots.

MATERIALS AND METHODS

Extracted human teeth were processed in the root area by laser ablations followed by histological evaluation. Dentin adjacent to the cutting surface was evaluated morphometrically.

RESULTS

PIRL produced clearly defined cutting boundaries in dental roots. At the bottom of the cavity, the ablation surface became slightly concave. Heat development in this scantly hydrated tissue was considerable. We attributed the excess heating effects to heat accumulation due to multiple pulse overlap across a limited scan range imposed by tooth geometries.

CONCLUSION

Defined areas of the tooth root may be treated using the PIRL. For clinical translation, it would be necessary to improve beam delivery to facilitate beam steering for the intended oral application (e.g. by using a fiber) and identify optimal repetition rates/scan speeds combined with cooling techniques to minimize accumulated heat within ablation cavities.

Temperature Change from Diode Lasers in Oral Mucosa: An Ex Vivo Study

Objective: The aim of this ex vivo study was to assess the mean temperature change deep in tissue during diode laser (980 vs. 810 nm) irradiation using continuous and pulsed laser and initiated versus noninitiated tips. Background data: Previous studies have determined thermal effects of diode lasers on tissue damage but have yet to compare the incision qualities of 980 versus 810 nm diode lasers. Further studies need to be done to determine the efficiency of diode lasers to create a safer protocol for clinicians. Methods: Ninety-six incisions of 20 mm length were made in three bovine tongues using diode lasers (980 and 810 nm). Both continuous and pulsed modes were tested with initiated (using blue articulating paper) and noninitiated glass fibers (n = 12 per group). Thermocouples attached to LabChart^® software were used to measure mean temperature changes. Mean, standard deviations, and p values were conducted for each group to test the statistical significance (p < 0.05). Results: Quality of incisions were better using the initiated tips for both laser wavelengths. Pulsed mode with 810 nm diode laser produced the least mean temperature change in tissue. Overall, both pulsed and continuous mode showed similar thermal effects on tissue. Conclusions: Within the limitations of this study, noninitiated tips are responsible for diffuse irradiation in tissue and are associated with tissue temperature increase during surgery. Low incision quality was observed using noninitiated tips. The temperature changes seem to be dependent on the laser wavelength and are higher for 980 nm compared with 810 nm pulsed diode laser.

Effects of Dentin Ablation by a Q-Switching Er:YSGG Laser with a High Pulse Repetition Rate

Objective: The aim of the study was to evaluate the characteristics of dentin ablation with a high pulse repetition rate Q-switching 2.79 μm laser. Materials and methods: Dentin was ablated using a homemade Q-switching Er:YSGG laser with a high pulse repetition rate. Er:YSGG radiation was applied with a pulse energy of 1 or 10 mJ for 100 or 3 Hz pulse repetition rate, respectively. A scanning electron microscope (SEM) was used to observe the microstructures of dentin samples after ablation. Teeth were irradiated in vitro with a 100 Hz pulse repetition rate under two different modes: free running and Q-switching. A thermocouple was applied to measure the temperature in the pulp cavity during ablation. Results: A 100 or 3 Hz Q-switching laser was used to irradiate dentin for 30 and 100 sec, respectively. There was no significant difference in ablation mass loss between the two conditions. The SEM photographs showed more dentinal tubules and no damage in the ablation area when using the 100 Hz Q-switching laser. The temperature of the pulp cavity was maintained below 41°C when using a Q-switching laser. Conclusions: The Q-switching Er:YSGG laser with a high pulse repetition rate exhibited greater ablation efficiency and better morphology than the low pulse repetition rate Q-switching laser. The experimental results also demonstrate the significant advantage of the Q-switching laser over free-running lasers for protecting dental pulp tissue. The Q-switching Er:YSGG laser with a high pulse repetition rate is expected to become an efficient new dental tool.

Laser Conditioning: A Preferred Option Over Conventional Acid Etching for Orthodontic Bonding

Aim:

To evaluate the demineralization resistance and the shear bond strength of enamel surfaces after erbium, chromium: yttrium–scandium–gallium-garnet (Er,Cr:YSGG) laser etching (2 W/15 Hz, 2 W/25 Hz) and to compare them with conventional acid etching for orthodontic bonding.

Materials and Methods:

A total of 60 extracted human premolars with intact enamel surface were used for this study. Demineralization Resistance was estimated using ion-coupled plasma atomic emission spectrometer (ICP-AES). Shear bond strength was evaluated using Universal Testing Machine—Instron.

Results:

Statistically significant difference ( P < .001) was found in the concentration of dissolved calcium (Ca) and phosphorus (P), with the highest mean Ca and P in the acid-etched group, followed by 2 W/15 Hz laser-etched group and least with 2 W/25 Hz laser-etched group. Maximum bond strength was found in the acid-etched group (12.06 MPa), followed by the 2 W/25 Hz laser-etched group (9.01 MPa) and 2 W/15 Hz laser-etched group (8.39 MPa). The differences were statistically significant.

Conclusions:

Laser conditioning of enamel surface revealed significant demineralization resistance with a minimal dissolution of Ca and P ions in the demineralizing solution. Moreover, optimum bond strength was obtained similar to that of acid etching; hence, Er,Cr:YSGG laser conditioning of enamel surface is preferred over the conventional phosphoric acid etching for orthodontic bonding.

Histological Effects of an Innovative 445 Nm Blue Laser During Oral Soft Tissue Biopsy

Continuously evolving laser devices can be used in various fields; they are an alternative to the traditional cold blade surgery to perform biopsies of oral soft tissues. The aspect focused on in this paper is the possibility to use the 445 nm diode laser (Eltech K-Laser srl, Treviso, Italy) in complete safety, by evaluating its thermal effects during microscopy. A histological evaluation of the alteration of the peri-incisional edges on 10 samples was realized. All excisional biopsies were related to clinically unsuspected lesions and performed by the same expert operator. The surgical procedure was performed with the same laser parameters and the same pathologist evaluated the thermal effect on the samples. An average value of the detected tissue alteration was calculated; the average damage of the epithelium was 650.93 μm, while in the connective tissue it was 468.07 μm. In all the cases a clear diagnosis was possible, and no clinical complications were observed; so, the 445 nm diode laser proved to be a device that can be safely used for biopsies of clinically unsuspicious lesions. Due to the small number of cases, this in vivo preliminary experience needs to be extended.

Early Creeping Attachment Noted after Mandibular Labial Frenuloplasty

Recession of the mandibular central incisors is frequently associated with high frenum insertion. Often times, this recession is accompanied by a lack of sufficient amount of keratinized tissue and absence of attached gingiva. In this case report, an ASA I patient presented with Cairo Recession Type 2 (RT2) and a minimal amount of keratinized tissue on the mandibular central incisors and underwent frenuloplasty in the anterior mandible with the use of a conventional scalpel technique due to high frenum attachment. The results demonstrated creeping attachment of 1.0 mm as early as 10 days postoperatively resulting in complete root coverage and closure of the interproximal space between teeth #24 and 25. A second soft tissue surgery was avoided due to complete root coverage which remained stable at the 6-month follow-up appointment.

Efficient energy transfer from Er3+ to Ho3+ and Dy3+ in ZBLAN glass

Spectroscopic properties of erbium (Er³⁺)-, holmium (Ho³⁺)-, dysprosium (Dy³⁺)-doped and Er³⁺/Ho³⁺, Er³⁺/Dy³⁺ co-doped ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF) glasses were studied. The experimental results show that efficient energy transfer from Er³⁺ to Ho³⁺ and Dy³⁺ occurs in the Er³⁺/Ho³⁺ and Er³⁺/Dy³⁺ co-doped ZBLAN glasses, respectively. This valuable discovery enables us to design and develop high power Ho³⁺-doped and Dy³⁺-doped ZBLAN fiber lasers in the 3 µm wavelength region that can be pumped with readily available high-efficiency, high-power diode laser pumps at 980 nm.

Managing Benign and Malignant Oral Lesions with Carbon Dioxide Laser: Indications, Techniques, and Outcomes for Outpatient Surgery

Purpose  Because of its affinity for water-based tissues, carbon dioxide (CO ₂ ) laser has become an instrument of choice for treating oral mucosa conditions, ranging from inflammatory to malignant lesions. The aim of this work is to systematically evaluate the outcomes of laser surgery over a wide range of lesions, while providing a solid and reproducible protocol for CO ₂ laser surgery in the outpatient management of oral lesion.

Methods  Seventy-eight patients underwent 92 laser outpatient procedures for treatment of a wide range of benign and malignant lesions. We performed 60 removals, 11 exeretic biopsies, 15 vaporizations, and 3 vaporization/removal combined. We analyzed laser parameters applied for each technique and provided a systematic evaluation of surgical results.

Results  No problems occurred intraoperatively in any of the patients. Five patients complained marginal pain, while 3 patients had postsurgery bleeding. All treatments were successful, with the notable exception of 3 relapsing verrucous proliferative leukoplakias and an infiltrating squamous cell carcinoma of the tongue requiring radicalization. We did not record any adverse reactions to drugs or lesions due to laser action. Concordance between clinical diagnosis and pathology results was at 94.8%.

Conclusions  Our data indicate that CO ₂ laser is a solid choice for outpatient treatment of oral lesions. This technique grants painless and almost bloodless treatment, with negligible recurrence rates. Providing a solid reference for laser settings and operative techniques could provide a foundation for further exploring this tool while offering the basis for a positive comparison between different surgical techniques and options.

Effects of laser treatments on surface roughness of zirconium oxide ceramics

BACKGROUND

The aim of this study was to analyze the surface roughness of yttrium stabilized tetragonal polycrystalline zirconia (Y-TZP) ceramics after different laser treatments (CO_2, ER: YAG).

METHODS

5x5x2 mm rectangular prisms of forty eight Y-TZP (Zirkonzahn) ceramic specimens were prepared. In order to standardize surfaces, 600-, 1200- grid silicon carbide papers were used to gradually ground wet on 300 rpm grinding machine for 10 s. Eight groups (n = 6) were randomly formed from the specimens of each ceramic as control (GroupC), sandblasted (GroupS), two different CO₂ laser treatments (Group3W: 3 W and 382 w/cal, Group4W: 4 W and 509w/cal) and four different Er: YAG laser treatments (Group150SP: 150 mJ and 10-Hz with 100μS; Group150SSP: 150 mJ and 10-Hz with 300μS; Group300SP: 300 mJ and 10-Hz with 100μS; Group300SSP: 300 mJ and 10-Hz with 300μS). A profilometer was used to conduct surface roughness measurements (Ra). Surface morphologies of the specimens were evaluated under SEM after laser treatment.

RESULTS

To analyze the data one-way ANOVA and to compare the mean values Tukey HSD tests (α = .05) were used. One - way ANOVA results showed that Group S had the highest Ra value and Group150 SP had the lowest. After sandblasting group the highest value was seen in Group4W. There were no statistically significant differences among Group C, Group3W, Group150SSP, Group300SP, and Group300SSP.

CONCLUSIONS

The study showed that surface roughness of zirconium oxide ceramics was increased with CO2 laser.

Comparative study of debris and smear layer removal with EDTA and Er,Cr:YSGG laser

Background

To evaluate in vitro, the ability in removing debris and Smear Layer of 17% EDTA and Er,Cr:YSGG laser.

Material and Methods

58 unirradicular teeth were instrumented with MTwo® and divided into 3 groups according to irrigation protocol: 17%EDTA, laser and a combination of 17%EDTA and laser. All samples were analyzed in the apical and middle third with Scanning Electron Microscope. The Chi-cuadrado and McNemar tests were used to determine the statistical analysis and data processing and analysis was performed with the statistical package StatGraphics Centurion XVI.

Results

Debris analysis showed statistical significant differences when compared EDTA vs laser and EDTA vs EDTA+laser in the middle third. The Smear Layer removal showed statistical significant differences in the middle third when compared EDTA vs laser and EDTA vs EDTA+laser.

Conclusions

Laser showed a greater cleaning capacity than EDTA in the middle third; the cleanliness was even better when combined laser with EDTA, so the effect is accumulative.

Key words:Root canal treatment, Smear Layer, Er,Cr:YSGG laser, debridement.

WITHDRAWN: Ethical and legal ramifications of using diode lasers for nonsurgical periodontal therapy

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Histological evaluation of three techniques for caries removal

A number of concepts and devices have been proposed for caries removal. Among these, the Er:YAG laser is a potential alternative to conventional mechanical treatment. This study compared the effectiveness of the Er:YAG laser with that of low-speed rotary instruments for removal of carious tissue in 26 extracted human molars and premolars with severe decay (i.e., large occlusal or proximal decay but no pulpal contact). The teeth were divided into three groups of eight teeth, and two teeth were used as controls. After sectioning all the teeth through the center of the carious lesion before excavation, each group was randomly assigned to three groups-Er:YAG laser versus tungsten bur, Er:YAG laser versus polymer bur, and polymer bur versus tungsten bur-to evaluate the efficacy of the three techniques. The time required for carious treatment of each half was recorded, and samples were then histologically examined. Mean duration of caries removal did not significantly differ in relation to the technique used. Histological analysis of tooth halves treated with the Er:YAG laser revealed a regular 5-µm-thick stained layer that appeared to be denatured collagen. A smear layer was often detectable in halves treated with carbide burs. A superficial disorganized layer, which was found to be affected dentin, was observed in halves treated with polymer burs. The present findings indicate that the three techniques were clinically and histologically effective in removing the infected dentin layer.(J Oral Sci 58, 583-589, 2016).

34 nm-wavelength-tunable picosecond Ho3+/Pr3+-codoped ZBLAN fiber laser

We propose and demonstrate a broadly wavelength-tunable mode-locked Ho³⁺/Pr³⁺-codoped ZBLAN fiber laser operating in the 3 μm mid-infrared spectral region based on a semiconductor saturable absorber mirror. Wavelength selection is realized by rotating a plane ruled grating. The fiber laser exhibits stable continuous-wave mode-locking operation over a wide wavelength tuning range of 34 nm (2842.2 nm~2876.2 nm), with a 10.17 MHz repetition rate and 22 ps pulse duration. Stable mode-locked pulses can be maintained until the launched pump power of 1.25 W. Maximum average output power of 127.7 mW and the corresponding pulse energy of 12.56 nJ are achieved. To the best of our knowledge, this is the first demonstration of a wavelength-tunable mode-locked fiber laser operating in the 3 μm spectral region. Such simple, robust, and versatile mid-infrared picosecond laser source can find various applications in laser surgery, spectroscopy, and nonlinear frequency conversion.

Evaluation of Different Types of Lasers in Surface Conditioning of Porcelains: A Review Article

To achieve proper bond strength for porcelains, adequate surface roughness is essential, which is traditionally gained by sandblasting or acid etching with hydrofluoric (HF) acid. Nowadays with the development of laser systems, serious efforts were made to apply this new instrument for surface etching of porcelains due to easy usage, safety, and more efficiency. There are different kinds of lasers and porcelains, so choosing the ones which will be good match for each other is crucial. Besides that, changing the irradiation setting can be beneficial as well. This article reviewed 33 related studies and summarized results of etching accomplished by Nd:YAG, Er:YAG, Er,Cr:YSGG and CO2 lasers on different types of porcelains considering different laser settings and evaluation methods to bring a comprehensive insight.

Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system

OBJECTIVE

The purpose of this study is to assemble a laser system for the selective removal of dental composite from tooth surfaces, that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical hand-piece, and evaluate the performance of that system on extracted teeth.

METHODS

Ten extracted teeth were collected and small fillings were placed on the occlusal surface of each tooth. A clinical system featuring a CO₂ laser operating at 50 Hz and spectral optical feedback was used to remove the composite. Removal was confirmed using a cross polarized optical coherence tomography (CP-OCT) system designed for clinical use.

RESULTS

The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20 μm.

CONCLUSION

We have demonstrated that spectral feedback can be successfully employed in an automated system for composite removal by incorporating dual photodiodes and a galvanometer controlled CO₂ laser. Additionally, the use of registered OCT images presents as a viable method for volumetric benchmarking. Overall, this study represents the first implementation of spectral feedback into a clinical hand-piece and serves as a benchmark for a future clinical study. Lasers Surg. Med. 49:658-665, 2017. © 2017 Wiley Periodicals, Inc.

High performance of a passively Q-switched mid-infrared laser with Bi2Te3/graphene composite SA

We report passively Q-switched ∼2 and ∼3  μm mid-infrared (MIR) solid-state lasers with a self-assembly solvothermal-synthesized Bi₂Te₃/graphene heterostructure saturable absorber (SA) for the first time. Based on the oxidation resistance and high thermal conductivity of graphene, and large modulation depth of Bi₂Te₃ nanosheets, two high-performance Q-switching lasers were realized. One is a Tm:YAP laser with a maximum average output power of 2.34 W and a pulse width of 238 ns at ∼2  μm. The corresponding maximum pulse peak power was 91 W, which was much improved in comparison with the pure graphene-based Tm laser. The other one is an Er:YSGG laser producing a pulse width of 243 ns, which is the shortest among the 2D SAs-based ∼3  μm solid-state lasers, as far as we know. Our results indicate that such a composite Bi₂Te₃/graphene material is a promising SA for generating high-performance mid-infrared pulse lasers.

Diode Laser Ear Piercing: A Novel Technique

Earlobe piercing is a common office room procedure done by a plastic surgeon. Various methods of ear piercing have been described. In this article, we describe a novel method of laser ear piercing using the diode laser. An 18-year-old female patient underwent an ear piercing using a diode laser with a power of 2.0 W in continuous mode after topical local anaesthetic and pre-cooling. The diode laser was fast, safe, easy to use and highly effective way of ear piercing. The advantages we noticed while using the diode laser over conventional methods were more precision, minimal trauma with less chances of hypertrophy and keloids, no bleeding with coagulation effect of laser, less time taken compared to conventional method and less chance of infection due to thermal heat effect of laser.

Light in diagnosis, therapy and surgery

Light and optical techniques have made profound impacts on modern medicine, with numerous lasers and optical devices being currently used in clinical practice to assess health and treat disease. Recent advances in biomedical optics have enabled increasingly sophisticated technologies — in particular those that integrate photonics with nanotechnology, biomaterials and genetic engineering. In this Review, we revisit the fundamentals of light–matter interactions, describe the applications of light in imaging, diagnosis, therapy and surgery, overview their clinical use, and discuss the promise of emerging light-based technologies.

FT-Raman spectroscopic characterization of enamel surfaces irradiated with Nd:YAG and Er:YAG lasers

Background. Despite recent advances in dental caries prevention, caries is common and remains a serious health problem. Laser irradiation is one of the most common methods in preventive measures in recent years. Raman spectroscopy technique is utilized to study the microcrystalline structure of dental enamel. In this study, FT-Raman spectroscopy was used to evaluate chemical changes in enamel structure irradiated with Nd:YAG and Er:YAG lasers.

Methods. We used 15 freshly-extracted, non-carious, human molars that were treated as follows: No treatment was carried out in group A (control group); Group B was irradiated with Er:YAG laser for 10 seconds under air and water spray; and Group C was irradiated with Nd:YAG laser for 10 seconds under air and water spray. After treatment, the samples were analyzed by FT-Raman spectroscopy.

Results. The carbonate content evaluation with regard to the integrated area under the curve (1065/960 cm^–1) exhibited a significant reduction in its ratio in groups B and C. The organic content (2935/960 cm^-1) area exhibited a significant decrease after laser irradiation in group B and C.

Conclusion. The results showed that the mineral and organic matrices of enamel structure were affected by laser irradiation; therefore, it might be a suitable method for caries prevention.

Evaluation of temperature rises during the application of different power levels of potassium titanyl phosphate and neodymium-doped:yttrium aluminum garnet lasers to external primary root canals

Background/purpose

Nowadays, laser systems play crucial roles in endodontic treatments. Therefore, these systems should be investigated in terms of parameters that may prevent periodontal tissues damages during laser irradiation. In this context, the purpose of this study was to evaluate temperature rises during the application of different power levels of potassium titanyl phosphate (KTP) and neodymium-doped:yttrium aluminum garnet (Nd:YAG) lasers to external primary root canals.

Materials and methods

Sixty primary mandibular molars were selected and chemomechanical preparation was performed. KTP laser treatment was applied to 30 of these 60 samples and the remaining 30 received Nd:YAG laser treatment. The teeth samples received laser application (KTP or Nd:YAG) at three different power levels (1 W, 1.5 W, and 2 W, respectively, applied to 10 samples from each group). Nine holes were drilled (1 mm in diameter) through the level of the coronal, middle, and apical third of each tooth canal to provide entry for a Type L thermocouple wire, which was used to measure temperature changes. Data were assessed with two-way analysis of variance and the Tukey test.

Results

All power levels indicated statistically significant differences between Nd:YAG and KTP laser systems (P < 0.05). Moreover, the same regional (apical, middle, and coronal) comparisons performed between Nd:YAG and KTP laser systems showed statistically significant differences (P < 0.05).

Conclusion

All parameters of KTP laser indicated lower temperature rises than Nd:YAG laser. Therefore, KTP laser may be preferable to protect the periodontal tissues from harmful thermal effects during the endodontic treatment of primary root canals.

Technology of Lasers and Their Applications in Oral Surgery: Literature Review

The word “Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation”. Recent advances in laser technology have brought a kind of revolution in dentistry. The purpose of this article is to provide an overview of clinical application of lasers in oral medicine and especially in oral surgery, including their advantages, disadvantages and safety.

Lasers for caries removal in deciduous and permanent teeth

BACKGROUND

Despite considerable improvements in oral health, dental caries continue to be a public health issue. The most frequently used, and universally accepted technique, to remove caries is through mechanical ablation of decayed tissues by means of rotating drills (diamond or tungsten carbide, or both). In the past few decades, the introduction of adhesive filling materials (resin composites) has affected cavity filling procedures by reducing its retention needs, with advantages for dental tissue conservation. Consequently, new minimally invasive strategies were introduced into dental practice, such as the use of lasers to perform highly controlled tissue ablation. Laser use has also raised expectations of limiting pain and discomfort compared to using drills, as well as overcoming drill phobia.

OBJECTIVES

The main objective of the review was to compare the effects of laser-based methods to conventional mechanical methods for removing dental caries in deciduous and permanent teeth.

SEARCH METHODS

We searched the following electronic databases: Cochrane Oral Health's Trials Register (searched 22 June 2016), Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 5) in the Cochrane Library (searched 22 June 2016), MEDLINE Ovid (1946 to 22 June 2016), Embase Ovid (1980 to 22 June 2016), ProQuest Dissertations and Theses (1980 to 22 June 2016), Zetoc (limited to conference proceedings) (1993 to 22 June 2016), and ISI Web of Knowledge (limited to conference proceedings) (1990 to 22 June 2016). We checked the reference lists of relevant articles to identify additional studies. We searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials.

SELECTION CRITERIA

We included randomised controlled trials, split-mouth trials and cluster-randomised trials (irrespective of their language) comparing laser therapy to drill ablation of caries. We included participants of any age (children, adolescents and adults).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts of citations identified by the review search strategy. Two review authors independently evaluated the full text of relevant primary studies, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included nine randomised trials, published between 1998 and 2014, involving 662 participants. The population consisted of both children and adolescents in four trials, only adults in four trials, and both children/adolescents and adults in one trial. Four studies examined only permanent teeth, and five studies evaluated both deciduous and permanent teeth. Six trials used Er:YAG (erbium-doped yttrium aluminium garnet) lasers, two trials employed Er,Cr:YSGG (erbium, chromium: yttrium-scandium-gallium-garnet) lasers, and one trial used Nd:YAG (neodymium-doped yttrium aluminium garnet) laser.Overall, the trials had small sample sizes, and the majority were at unclear or high risk of bias. The primary outcomes were evaluated in a limited number of trials (removal of caries (four trials (but only two reported quantitative data)); episodes of pain (five studies)). There was insufficient evidence to suggest that either lasers or drill were better at caries removal (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.99 to 1.01; 2 studies; 256 treated caries; P = 0.75; I² = 0%; low-quality evidence).The incidence of moderate or high pain was greater in the drill group compared to the laser group (RR 0.40, 95% CI 0.28 to 0.57; 2 studies; 143 participants; P < 0.001; I² = 50%). Similarly, the need for anaesthesia was significantly higher in the drill group than in the laser group (RR 0.25, 95% CI 0.10 to 0.65; 3 studies; 217 children/adolescents; P = 0.004; I² = 0%).In terms of marginal integrity of restoration, there was no evidence of a difference between laser and drill comparisons evaluated at 6 months (RR 1.00, 95% CI 0.21 to 4.78; 3 studies), 1 year (RR 1.59, 95% CI 0.34 to 7.38; 2 studies), or 2 years (RR 1.00, 95% CI 0.21 to 4.74; 1 study).There was no evidence of a difference for durability of restoration between laser therapy or drill at 6 months' follow-up (RR 2.40, 95% CI 0.65 to 8.77; 4 studies), at 1 year (RR 1.40, 95% CI 0.29 to 6.78; 2 studies) or at 2 years' follow-up (RR 0.50, 95% CI 0.02 to 14.60; 1 study).Only two trials investigated the recurrence of caries, but no events occurred during 6 months' follow-up.There was insufficient evidence of a difference between laser or drill in terms of pulpal inflammation or necrosis at 1 week (RR 1.51, 95% CI 0.26 to 8.75; 3 studies) and at 6 months (RR 0.99, 95% CI 0.10 to 9.41; 2 studies).

AUTHORS' CONCLUSIONS

Given the low quality of the body of evidence, we concluded that evidence was insufficient to support the use of laser as an alternative to traditional drill therapy for caries removal. We found some evidence in favour of laser therapy for pain control, need of anaesthesia and patient discomfort, but, again, the body of evidence was of low quality. Additional well-designed, randomised trials investigating the most relevant outcomes are needed.

Analysis and simulation of heat transfer in human tooth during the curing of orthodontic appliance and food ingestion

The aim of this study was to analyze and simulate the heat transfer in the human tooth undergoing fixed orthodontic appliances and food intake. An in vivo representative mathematic model of a layered thermographic profile was developed during the LED curing of Gemini bracket 0.022 in slot (conventional ligating system) and Transbond XT adhesive. The characterization of the layered thermic response allowed to identify if during the LED curing process, according to manufacturer’s specification (light curing unit, adhesive) can induce pulpar necrosis. The profile’s thermographic model was the simulation basis of many conditions such as food intake, due to in vivo metrology is affected by the impossibility of a correct apparatus position and the physiologic function of the oral cavity which is exposed to uncontrollable temperature changes. The metrology was carried out with a T-440 thermographic camera during LED curing bracket, using a LED curing light (Elipar S10) placed at 3 ± 1 mm for 5 s at each mesial and distal surface. The thermography outcomes were analyzed in the FLIR Tools Software, Microsoft Excel 2013 and SPSS 22. To adjust the mathematic model error, in vitro studies were performed on third molars for the purpose of realizing extreme exposition temperature condition tests caused by the LED curing unit without jeopardizing the human tooth vitality as would it be on in vivo experimentation. The bracket curing results according to manufacturer’s conditions reached 39°C in vivo temperatures and 47°C on in vitro tests, which does not jeopardize human tooth vitality as said by previous researches, although, an LED curing precise protocol established by the manufacturer’s LED curing light is sustained.

Dental hard tissue ablation using mid-infrared tunable nanosecond pulsed Cr:CdSe laser

BACKGROUND AND OBJECTIVE

Mid-infrared erbium: yttrium-aluminum-garnet (Er:YAG) and erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers (2.94- and 2.78-μm, respectively) are utilized for effective dental hard tissue treatment because of their high absorption in water, hydroxide ion, or both. Recently, a mid-infrared tunable, nanosecond pulsed, all-solid-state chromium-doped: cadmium-selenide (Cr:CdSe) laser system was developed, which enables laser oscillation in the broad spectral range around 2.9 μm. The purpose of this study was to evaluate the ablation of dental hard tissue by the nanosecond pulsed Cr:CdSe laser at a wavelength range of 2.76-3.00 μm.

STUDY DESIGN/MATERIALS AND METHODS

Enamel, dentin, and cementum tissue were irradiated at a spot or line at a fluence of 0-11.20 J/cm² /pulse (energy output: 0-2.00 mJ/pulse) with a repetition rate of 10 Hz and beam diameter of ∼150 μm on the target (pulse width ∼250 ns). After irradiation, morphological changes, ablation threshold, depth, and efficiency, and thickness of the structurally and thermally affected layer of irradiated surfaces were analyzed using stereomicroscopy, scanning electron microscopy (SEM), and light microscopy of non-decalcified histological sections.

RESULTS

The nanosecond pulsed irradiation without water spray effectively ablated dental hard tissue with no visible thermal damage such as carbonization. The SEM analysis revealed characteristic micro-irregularities without major melting and cracks in the lased tissue. The ablation threshold of dentin was the lowest at 2.76 μm and the highest at 3.00 μm. The histological analysis revealed minimal thermal and structural changes ∼20 μm wide on the irradiated dentin surfaces with no significant differences between wavelengths. The efficiency of dentin ablation gradually increased from 3.00 to 2.76 μm, at which point the highest ablation efficiency was observed.

CONCLUSION

The nanosecond pulsed Cr:CdSe laser demonstrated an effective ablation ability of hard dental tissues, which was remarkably wavelength-dependent on dentin at the spectral range of 2.76-3.00 μm. These results demonstrate the potential feasibility of the use of pulsed Cr:CdSe laser as a novel laser system for dental treatment. Lasers Surg. Med. 48:965-977, 2016. © 2016 Wiley Periodicals, Inc.

A new sealed RF-excited CO2 laser for enamel ablation operating at 9.4-μm with a pulse duration of 26-μs

Several studies over the past 20 years have shown that carbon dioxide lasers operating at wavelengths between 9.3 and 9.6-μm with pulse durations near 20-μs are ideal for hard tissue ablation. Those wavelengths are coincident with the peak absorption of the mineral phase. The pulse duration is close to the thermal relaxation time of the deposited energy of a few microseconds which is short enough to minimize peripheral thermal damage and long enough to minimize plasma shielding effects to allow efficient ablation at practical rates. The desired pulse duration near 20-μs has been difficult to achieve since it is too long for transverse excited atmospheric pressure (TEA) lasers and too short for radio-frequency (RF) excited lasers for efficient operation. Recently, Coherent Inc. (Santa Clara, CA) developed the Diamond J5-V laser for microvia drilling which can produce laser pulses greater than 100-mJ in energy at 9.4-μm with a pulse duration of 26-μs and it can achieve pulse repetition rates of 3 KHz. We report the first results using this laser to ablate dental enamel. Efficient ablation of dental enamel is possible at rates exceeding 50-μm per pulse. This laser is ideally suited for the selective ablation of carious lesions.

Femtosecond laser for cavity preparation in enamel and dentin: ablation efficiency related factors

To study the effects of laser fluence (laser energy density), scanning line spacing and ablation depth on the efficiency of a femtosecond laser for three-dimensional ablation of enamel and dentin. A diode-pumped, thin-disk femtosecond laser (wavelength 1025 nm, pulse width 400 fs) was used for the ablation of enamel and dentin. The laser spot was guided in a series of overlapping parallel lines on enamel and dentin surfaces to form a three-dimensional cavity. The depth and volume of the ablated cavity was then measured under a 3D measurement microscope to determine the ablation efficiency. Different values of fluence, scanning line spacing and ablation depth were used to assess the effects of each variable on ablation efficiency. Ablation efficiencies for enamel and dentin were maximized at different laser fluences and number of scanning lines and decreased with increases in laser fluence or with increases in scanning line spacing beyond spot diameter or with increases in ablation depth. Laser fluence, scanning line spacing and ablation depth all significantly affected femtosecond laser ablation efficiency. Use of a reasonable control for each of these parameters will improve future clinical application.

Energy output reduction and surface alteration of quartz tips following Er:YAG laser contact irradiation on soft and hard tissues in vitro

Though the Er:YAG laser (ErL) has been used in periodontal therapy, the irradiated tip damage has not been studied in detail. In this study, the change in the energy output, surface morphology, and temperature of quartz tips was evaluated following contact irradiation. Soft tissue, calculus on extracted human teeth, and porcine bone were irradiated by ErL for 60 min at 14.2 or 28.3 J/cm(2)/pulse and 20 Hz with or without water spray. The energy output ratio declined the most in the calculus group, followed by the bone and soft tissue groups with and/or without water spray. Carbon contamination was detected in all groups, and contamination by P, Ca, and/or other inorganic elements was observed in the calculus and bone groups. The rate of energy output reduction and the degree of surface alteration/contamination is variously influenced by the targeting tissue, temperature elevation of the tip and water spray.

Lack of clinical evidence on low-level laser therapy (LLLT) on dental titanium implant: a systematic review

Low-level laser therapy (LLLT) has proved to have biostimulating effects on tissues over which they are applied, therefore accelerating the healing process. Most studies in implantology were focused on a reduction of the duration of osseointegration. There exist few articles analyzing the potential effects of these therapies on the osseointegration of titanium dental implants. The aim of this study was to assess the effect of LLLT on the interaction between the bone and the titanium dental implant and the methodological quality of the studies. We conducted an electronic search in PubMed, ISI Web, and Cochrane Library. From 37 references obtained, only 14 articles met the inclusion criteria. The analysis of the studies shows that most of the experiments were performed in animals, which have a high risk of bias from the methodological point of view. Only two studies were conducted in human bone under different conditions. Several protocols for the use of low-power laser and different types of laser for all studies analyzed were used. Although animal studies have shown a positive effect on osseointegration of titanium implants, it can be concluded that it is necessary to improve and define a unique protocol to offer a more conclusive result by meta-analysis.

Diode Laser in Minor Oral Surgery: A Case Series of Laser Removal of Different Benign Exophytic Lesions

INTRODUCTION

The role of laser in conservative management of oral disease is well established. Laser procedures are common in the fields of oral surgery, implant dentistry, endodontic, and periodontic therapy.

CASE

This case series describes the use of diode laser for the excision of oral exophytic lesions. All the patients attended the oral medicine department of Shahid Beheshti University of Medical Sciences, Tehran, Iran. Criteria in patient selection were accessibility to lesions, patient fear from blade surgery, aesthetics, and probability of bleeding. An informed consent was filled by every patient. All of the lesions were completely excised under local anaesthesia by diode laser with 300 μm-fibre tip, 808 nm continuous wavelength and 3-3.5 W power for 3×60 seconds (Dr Smile, Italia). During surgery, the fibre tip was in contact with lesions. No analgesics were prescribed to the patients. The patients were followed for the first, second, and forth week after treatment.

CONCLUSION

The lesions could be excised using the diode laser. This procedure was a quick clinical technique without bleeding.

Evaluation of the use of a 940 nm diode laser as an adjunct in flap surgery for treatment of chronic periodontitis

BACKGROUND

Lasers have several potential benefits such as antibacterial effect and stimulation of wound healing. In addition, hemostasis and delaying epithelial migration may facilitate the outcome of flap surgery. There is a minimal research and evidence currently available for the optimum method of use of a diode laser in flap surgery and its benefit and safety. Hence, this study aimed to investigate the adjunctive effect of diode laser irradiation in open flap debridement (OFD), while treating chronic periodontitis.

MATERIALS AND METHODS

A total of 30 patients with generalized chronic moderate to severe periodontitis with pocket probing depth (PD) ≥5 mm post - Phase I therapy were selected for a split-mouth study. Flap surgery with adjunctive diode laser irradiation was performed in the test quadrant while routine OFD was done in the control quadrant. Clinical parameters including PD, clinical attachment level, gingival recession, plaque index, gingival index and tooth mobility were recorded at baseline, 3 months and 6 months following treatment. In addition, patients' rating of procedural pain as well as the development of complications postoperatively was assessed.

RESULTS

All clinical parameters significantly improved after therapy without any statistically significant difference between the two groups for any of the parameters. The exception was a significantly greater reduction in gingival inflammation in the laser treated group. The laser treatment was acceptable to the patient and did not cause any complications.

CONCLUSION

The diode laser can be safely and effectively used as an adjunct to the treatment of chronic periodontitis with the advantage of decreased gingival inflammation.

Evaluation of pain on use of electrosurgery and diode lasers in the management of gingival hyperpigmentation: A comparative study

Background:

Gingival depigmentation is a periodontal plastic surgical procedure whereby the gingival hyperpigmentation is removed by various techniques such as electrosurgery, cryosurgery, abrasion with diamond bur and lasers. The aim of this study was to determine the pain levels during the gingival depigmentation procedure using electrosurgery and lasers.

Materials and Methods:

Twenty patients, both male and female, between the ages of 20 and 40 years were randomly allocated into two groups of 10 patients each: Those undergoing depigmentation with electrosurgery (Group I) and those by diode lasers (Group II). Patients of both groups were asked to define the level of pain and discomfort by using the Visual Analog Scale (VAS) intraoperatively, 24 h post-operatively and 1 week post-operatively.

Results:

Both the groups showed a decrease in the pain levels, which was statistically highly significant 1 week post-operatively when compared 24 h post-operatively. There was a statistically highly significant difference in the pain levels between the electrosurgery and the lasers groups after 24 h (P < 0.001), with the lasers group demonstrating lesser pain and discomfort. Although there was no significant difference between the two groups intraoperatively and 1 week post-operatively on comparison, lesser mean scores were observed for the lasers group.

Conclusion:

The growing concern for esthetic requires the removal of hyperpigmentated gingival areas to create a confident and pleasant smile, which could be easily attained by using either electrosurgery or lasers. This study concluded that lasers produce lesser pain and discomfort compared with electrosurgery during gingival depigmentation.

In situ investigation of the effect of TiF4 and CO2 laser irradiation on the permeability of eroded enamel

OBJECTIVE

Interest in erosion and its role in tooth wear has increased considerably. Due to the limited contribution of patients in modifying their dietary habits, therapeutic resources aiming to reduce the progression of erosion-like lesions have been discussed. This study sought to evaluate the effect of TiF4 and CO2 laser in controlling the permeability of in situ eroded enamel.

DESIGN

Ten volunteers wore an intraoral palatal device containing two enamel slabs, treated with TiF4 gel and TiF4 gel + CO2 or placebo gel and placebo gel + CO2. After the washout period, volunteers were crossed over to the other treatment. During both phases, specimens were submitted to erosive challenges and then evaluated for permeability measured as the percentage of copper ion penetration over the total enamel thickness.

RESULTS

Two-way analysis of variance (ANOVA) revealed that there was a significant interaction between the factors under study (p = 0.0002). Tukey's test showed that TiF4 significantly reduced the enamel permeability of eroded enamel specimens, regardless of whether CO2 laser irradiation was performed.

CONCLUSIONS

It may be concluded that when the placebo gel was applied, CO2 laser was able to reduce enamel permeability; however, when TiF4 was applied, laser irradiation did not imply a reduction in permeability. TiF4 provided a lower permeability of eroded enamel, regardless of whether the CO2 laser was used.

Use of carbon dioxide laser in oral soft tissue procedures

Lasers have been introduced in dentistry as an alternative to conventional knife surgery. The advantage to the operator includes a clean dry field that enhances visibility and reduces the procedure time. The patient benefits by minimal postoperative pain and swelling. The paper discusses use of carbon dioxide laser in five conditions commonly encountered in oral cavity.