Fundamentals of dental lasers: science and instruments

Dentin Collagen versus Er:YAG Laser as Surface Biomodifiers for Intact Root Slices Simulating Delayed Replanted Roots

Objective: To evaluate effects of dentin collagen versus Er:YAG laser application through enhancing human periodontal ligament fibroblast (PDLF) cells to attach to intact root surfaces imitating delayed replanted roots. Background Data: Accidental traumatic injuries with teeth avulsion are managed by replantation. Root resorption, poor conditioning, and non-viable fibroblasts are factors responsible for failure. Methods: Thirty six human healthy single-rooted premolars were collected. Six teeth were used for PDLF, six teeth used for dentin collagen, whereas the remaining 24 teeth (48 root slices) were used for PDLF cell density and morphology. Each root was soaked in 5.25% NaOCl. Three groups (n = 16 slices/each) were planned as follows: I: Control (untreated); II: dentin collagen application; III: Er:YAG laser irradiation (4 mm distance, 40 mJ/pulse, under coolant). Following incubation, cell density and morphology of PDLF were investigated under SEM. Statistical analysis was performed using analysis of variance with Scheffé's test, and p < 0.05 was considered significant. Results: All groups showed increased cultured PDLF following incubation. Regarding cell density, attached PDLFs were significantly lower in untreated controls (36.5 ± 6.36) (p < 0.00001 i.e., <0.05) in negative empty and/or light cellular areas, compared with dentin collagen (65 ± 6) and laser-irradiated (66.75 ± 5.77) groups that did not show significant differences (p = 0.940 i.e., >0.05) and showed intermediate and/or heavy cellular areas. Regarding cell morphology, controls showed round and/or oval appearance with less lamellipodia, whereas dentin collagen and laser groups showed flat morphology with cytoplasmic processes. Conclusions: Both dentin collagen and Er:YAG laser showed comparable effectiveness as biomodification tools with good biocompatibility for human PDLF cell attachment on intact root slices imitating delayed replantation. Dentin collagen as a natural bioactive material is considered an alternative to Er:YAG laser to enhance the regenerative effects.

Laser Therapy Versus Traditional Scaling and Root Planing: A Comparative Review

Scaling and root planing (SRP) removes bacterial plaque, calculus, and associated microorganisms from the surface of the tooth and the surrounding soft tissue. While complete eradication of pathogenic microbes is impossible, gross removal can lower the microbial load, which in turn reduces inflammation and contributes to positive clinical outcomes. Instrumentation in limited-access anatomic areas like furcation, grooves, deep pockets, concavities, and distal molar areas is technically demanding with traditional mechanical debridement. However, emerging advanced systems such as lasers with bactericidal and detoxification effects offer the benefit of reaching limited-access areas that traditional SRP cannot reach. A digitized search was done on PubMed, Embase, Medline, and Google Scholar using the keywords "lasers", "periodontal therapy", "scaling", and "root planing". Upon screening and reviewing, the shortlisted articles comprised narrative reviews, systematic reviews, randomized controlled trials, comparative studies, split-mouth studies, case series, and reports of non-surgical laser therapy and lasers as an adjunct to SRP. This review presents a comprehensive comparative evaluation of different laser modalities utilized in non-surgical periodontal treatment in contrast to standard SRP, rather than an exhaustive article review. It delves into the history and development of lasers, highlighting key advancements made in the realm of periodontics and dental care. This review includes an elucidation of the theory behind laser operation, along with an exploration of its intrinsic characteristics and breakdown of the various types of lasers that are currently available, and an examination of existing literature in both present and historical contexts regarding the comparison of various types of lasers with traditional periodontal treatment.

Diode Laser Frenectomy: A Torch of Freedom for Ankyloglossia

Ankyloglossia, also known as tongue-tie, is a rare congenital anomaly of the oral cavity that not only causes difficulties in breastfeeding and teeth cleaning but also causes difficulty in speech articulation. Our patient faced difficulty in freely moving his tongue because of the short lingual frenulum wherein laser lingual frenectomy was indicated. The patient was treated successfully with a soft tissue diode laser having a wavelength of 445 nanometers. The use of a low-wavelength diode laser becomes relatively complimentary to standard scalpel surgery because of patient consolation, offers a blood-free area, reduces inflammation and edema, and is less damaging to thermal tissues.

An Update on the Use of Lasers in Prosthodontics

Lasers are employed in all fields of modern dentistry nowadays, including both surgical and non-surgical dental procedures. Prosthodontics, a branch of dentistry, has also embraced lasers as an invaluable addition to conventional methodologies. This helps improve the standard of care for patients and dentists due to its precise excision, quick healing, and enhanced tissue response after surgeries. In prosthodontics, the most commonly used lasers are carbon dioxide, argon, and yttrium-aluminum-garnet (YAG) lasers. Many reviews have been published in the literature regarding the use of lasers in dentistry; however, reviews on the use of lasers in the field of prosthodontics are limited. This review aims to explain the diverse applications and advancements of lasers in prosthodontics. Furthermore, it will highlight the integration of lasers in diagnostic protocols, treatment modalities, and the fabrication of prosthetic restorations.

Comparison of the Conventional and Laser Etching on the Bonding of the Orthodontic Brackets: An Original Research

Background

Acid etching enamel improves resin-enamel adhesion and adhesive characteristics, but has pros and cons. The effects of laser etching on the bonding of orthodontic brackets vary depending on the wavelength, power output, exposure duration, and energy delivered.

Materials and Methods

This study used a new 1064-nm diode laser to irradiate 30 freshly extracted human premolars. They were divided into three groups: group A, group B, and group C. Acid etching was used for 1 min to bond bracket to tooth surface, and Indian ink was used for 30 s. Group C uses acid etching for 1 min following 30 s of laser irradiation with Indian ink.

Results

In comparison to the other groups, group C's acid etching after laser irradiation has considerably stronger bond strength (P = 0.05). Orthodontic brackets in group B exhibited considerably poorer shear bond strength than those in the other groups.

Conclusion

Acid etching improves the adhesion of orthodontic composite resin to human enamel following laser irradiation, but can interfere with the adhesion of composite resin.

Systemic inflammatory markers following adjunctive Nd:YAG (1064 nm) laser irradiation to step 2 of periodontal therapy: a 12-month, randomized, controlled trial

OBJECTIVES

The aim of this study was to investigate whether the use of adjunctive Nd:YAG (1064 nm) laser irradiation to full-mouth scaling and root planing (FM-SRP) may offer additional benefit in the systemic inflammatory status of the patient, as depicted in a variety of systemic biomarkers over FM-SRP alone, up to 12 months after treatment.

MATERIALS AND METHODS

A total of 60 otherwise healthy stage III/IV periodontal patients were equally distributed in 3 groups. The control group received FM-SRP. In laser A group, 1 week after FM-SRP, Nd:YAG laser irradiation was delivered in periodontal pockets with PD ≥ 4 mm using specific settings (3 W, 150 mJ, 20 Hz, 100 μs). In laser B group Nd:YAG laser irradiation was delivered twice, 1 week after FM-SRP and 1 week later with different settings compared to laser A (2 W, 200 mJ, 10 Hz, 100 μs).

RESULTS

A significant reduction (p = 0.038) of IL-1β serum levels at the 6-month time point was observed for laser A group. IL-6 was found statistically significantly increased (p = 0.011) in the control group at the 6-week time point, whereas no difference was reported for the laser-treated groups (laser A, laser B).

CONCLUSIONS

The adjunctive use of Nd:YAG laser irradiation, prevented from IL-6 increase after FM-SRP, 6 weeks after treatment. Similarly, Nd:YAG laser irradiation (3 W, 150 mJ, 20 Hz,100 μs) was associated with significantly lower IL-1β levels, 6 months post-operatively.

CLINICAL RELEVANCE

Additional Nd:YAG laser application to FM-SRP may provide a potential beneficial effect on systemic inflammation.

TRIAL REGISTRATION NUMBER

ISRCTN26692900.

REGISTRATION DATE

09/06/2022.

Do erbium lasers promote changes in the tooth enamel during debonding of ceramic laminate veneers? A systematic review

The longevity of ceramic laminate veneers can be influenced by several factors, which can result in the need for a removal process. Laser removal has emerged as a good alternative to facilitate the procedure, and its repercussions on tooth enamel have been investigated. We aimed to evaluate the efficacy of erbium lasers for debonding ceramic laminate veneers without damaging the tooth enamel. This systematic review based on the PICOS model adhered to the PRISMA statement. The PubMed/MEDLINE, Web of Science, Embase, and Scopus databases were systematically searched until December 1, 2022, and 2902 studies were retrieved. After screening, four in vitro studies that analyzed the dental morphology using scanning electron microscopy, optical analysis, stereomicroscopy, or x-ray dispersion spectroscopy were included. The risk of bias was assessed using the Cochrane Collaboration tool. Our findings suggest that erbium lasers are useful for ceramic laminate veneer removal without damaging the tooth enamel. However, the removal is influenced by the type and thickness of ceramic and type of cement used. It could be concluded that the application of Erbium laser did not promote superficial changes in the dental enamel. This effect was observed in all analysis performed.

An In-Vitro Analysis of the Surface Treatment of Orthodontic Bracket Bases With Er,Cr:YSGG Laser and Its Effect on Shear Bond Strength

Introduction Shear bond strength is indispensable to prevent the debonding of orthodontic brackets. Lasers have been proven to alter the bond strength of orthodontic brackets, but their efficiency has not been validated in many trials. The study aimed to evaluate the impact of the Er,Cr:YSGG laser on the bases of orthodontic brackets and determine their bond strength with the enamel surface. Materials and methods The Waterlase iPlus (made in the USA in 2012), comprising an Er,Cr:YSGG laser, was used. Based on the surface treatment of brackets, two groups were assigned (n=10), comprising laser-treated and untreated bracket bases. The brackets were treated with the minimum laser intensity (50 Hz, 4.5 W). Then, the brackets of both groups were attached to the labial surfaces of previously extracted premolars, respectively. The shear bond strength of brackets (SBS) was assessed using the universal testing device, and the Adhesive Remnant Index (ARI) was also measured. An independent sample t-test was used to compare the bond strength between the laser-treated and untreated brackets. Results The mean bond strength of laser-treated and control group brackets was 5 MPa and 8.63 MPa, respectively. The laser-treated brackets showed lower bond strength than the control brackets, but the results were statistically insignificant (p=0.23). The ARI analysis stated that bond failures occurred mostly in the region of the bracket and adhesive interface. Conclusion Laser-etched bracket bases showed lesser shear bond strength than the untreated ones, though the difference was statistically insignificant.

Adjunctive Nd:YAG laser irradiation in the treatment of stage III/IV periodontitis: a 12-month, randomized, controlled trial

OBJECTIVES

The aim of this study was to evaluate the clinical efficacy of the adjunctive use of Nd:YAG laser (1064 nm) to full-mouth scaling and root planning (FMS), in stage III/IV periodontitis patients.

MATERIALS AND METHODS

Sixty stage III/IV periodontitis patients were randomly assigned to three groups. The control group received FMS, laser 1 group received combined FMS/single Nd:YAG laser irradiation (3 W, 150 mJ, 20 Hz,100 μs), and laser 2 group received combined FMS/double Nd:YAG laser irradiation with 1-week interval (2.0 W, 200 mJ, 10 Hz, 100 μs). PD, CAL, FMPS, GI, FMBS, and GR were evaluated at baseline, 6 weeks, 3, 6, and 12 months after treatment. Patient-reported outcomes were evaluated 1 week after treatment.

RESULTS

A significant improvement (p < 0.001) for all clinical parameters was observed during the entire study period, with the exception of mean CAL gain for the laser 2 group at 12 months. The percentage of pockets ≤ 4 mm was significantly higher compared to baseline for all groups throughout the study, with no inter-group differences at any time point. Patient-reported analgesic consumption was higher for laser 1 group.

CONCLUSIONS

The adjunctive use of Nd:YAG laser irradiation was similarly effective to FMS alone, during the entire study period. A slightly higher, though not statistically significant improvement was reported for PD at 6 and 12 months after a single post-FMS application of Nd:YAG laser for pocket epithelium removal and coagulation.

CLINICAL RELEVANCE

Additional Nd:YAG laser application for sulcular epithelium removal and coagulation may provide minor long-term improvements compared to FMS or laser irradiation for pocket disinfection and detoxification.

TRIAL REGISTRATION

ISRCTN26692900. Registration date: 09/06/2022.

An In Vitro Study of the Effect of CO2 Laser Power Output on Ablative Properties in Porcine Tongue

CO2 lasers have been generally used in oral soft-tissue surgery. Although an increase in power enhances the depth of ablation, the specific correlation between units of power and ablative depth has not been stated. This study aimed to explore ablative depth and width affected by a power unit of 10,600-nm CO2 laser continuous wave at 3 to 10 W in tissue blocks of the swine tongue. The 112 samples were randomly allocated into eight groups according to the power settings. The depth and width of the incision were measured by using the ImageJ program. The 3 W group showed the minimal depth of ablation [0.527 mm (0.474 and 0.817)] and width of ablation [0.147 mm (0.110 to 0.184)]. The maximal depth [3.750 mm (3.362 and 4.118)] and width [0.700 mm (0.541 to 0.860)] were in the 9 W group. The correlation between the ablative depth and power unit was 0.81 (p < 0.001). Based on the regression equation (p < 0.001), the ablative depth (mm) = (the power unit of laser in W × 0.491) − 0.731. In conclusion, the ablative depth of the CO2 laser on soft tissue was strongly correlated to power units enabling the prediction equation.

The effect of different energy levels of the Er: YAG laser on the repair bond strength of a nanohybrid composite resin

This study evaluates the durability of repair microshear bond strength (µSBS) of nanohybrid composite resins which surfaces are treated with different laser parameters and bur. A total of 240 nanohybrid composite resin disk shaped specimens were prepared. Then, specimens were divided into eight test groups as regards to surface treatment types (Erbium (Er:YAG) laser with seven different parameters and bur). Half of the specimens in each group were subjected to 5000 thermal cycling (TC) and the other half to 20,000 TC. Universal testing machine was used for µSBS test. The data were analyzed with a two-way analysis of variance and Tukey test. Among the specimens treated with ER:YAG laser+5000 TC, we detected the highest mean µSBS test values in the subgroups L200 and L250. Among the specimens treated with ER:YAG laser+20,000 TC, the highest mean µSBS test values were seen in the L200 subgroup. The µSBS values after the 20,000 TC were significantly lower than those after 5000 TC for all different treatment types. Thermal cycling and laser energy levels have effects on repair µSBS. Considering the bond strength and durability it seems more effective to use Er:YAG laser at 200 mJ. To repair an aged nanohybrid composite resin, Er:YAG laser surface treatments may provide some benefits by acquiring a reliable bond strength with durability. This study may give information on which parameters are more suitable to use Er:YAG laser for the repair of nanohybrid composite resins.

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.

The effect of Er,Cr:YSGG laser on periodontopathic bacteria elimination: an in vitro study

In vitro bacterial elimination using the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser against periodontopathic bacteria was investigated. Bacterial suspensions of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were spread on agar plates and the Er,Cr:YSGG laser was applied at 40 mJ pulse energy for durations of 30 s, 60 s, and 90 s. The agar plates were incubated, and growth inhibition zones were assessed. Optimal laser irradiation durations to achieve maximal bacterial elimination were evaluated using laser ablation on the bacterial colonies. The remaining viable bacteria were determined by the colony-forming unit (CFU) counting method. Growth inhibition zones were observed at all irradiation durations for both A. actinomycetemcomitans and P. gingivalis. Mean logarithmic values of CFU/ml after bacterial colony irradiation for 0 s (control), 12 s × 1 lap, 24 s × 1 lap, 48 s × 1 lap, and 24 s × 2 laps were 8.82 ± 0.35, 7.31 ± 0.94, 6.32 ± 0.61, 3.17 ± 2.90, and 0.00, respectively, for A. actinomycetemcomitans and 9.83 ± 0.50, 9.42 ± 0.11, 6.90 ± 1.60, 2.33 ± 3.19, and 0.00 for P. gingivalis. Significant differences were found between the control group and the two irradiated groups 48 s × 1 lap and 24 s × 2 laps (p < 0.05), and also between irradiated groups 12 s × 1 lap and 24 s × 2 laps (p < 0.05). An Er,Cr:YSGG laser with power setting 1.5 W and 30 Hz frequency showed potential for bacterial elimination against A. actinomycetemcomitans and P. gingivalis in vitro. Significant bacterial elimination (> 99.99%) was observed after 48 s of irradiation.

Comparison of oral mucosal biopsies done using scalpel and diode lasers: A vivo study

Background:

As dental lasers are becoming more popular in the branch of oral medicine for its various advantages and applications, this study was carried out to evaluate better mode of obtaining oral biopsies which is a common and inevitable procedure for providing final diagnosis in majority of conditions.

Methodology:

In this study, a total of 60 patients who required biopsy for final diagnosis of oral mucosal lesions as part of diagnosis in department of Oral Medicine were selected, out of which 30 were subjected to scalpel biopsies and 30 patients were subjected to diode laser biopsies. A 980 nm Zolar plus diode laser was used for the study. Out of 30 patients who were subjected to laser biopsies, 3W continuous mode settings were used for 15 patients and 3W pulsed mode was used for 15 patients. The specimens were sent to Department of Oral Pathology for histopathological evaluation to provide the final diagnosis. The time taken for each patient, volume of local anesthesia, during operative, postoperative pain scale, and co-relation of provisional and final diagnosis was noted for comparison purpose and the pathologist comments, peripheral tissue damage and artifact's for each slide were noted.

Results:

The study results showed the postoperative pain was comparatively less in diodlaser than scalpel, the lasers were patient friendly as the heammorage was negligible when compared to scalpel and suturing was not required. The pulsed mode in diode laser was advantageous over continuous mode when amount of thermal damage and postoperative pain score was compared.

Conclusion:

The results showed that oral biopsies can be made better using diode lasers, by having thorough knowledge on the device.

Efficacy of Er:YAG laser irradiation for decontamination and its effect on biocompatibility of different titanium surfaces

Background

Erbium yttrium–aluminum–garnet (Er:YAG) laser have been shown to be suitable for decontamination of titanium surfaces at a wide range of energy settings, however, high intensity of laser irradiation destroy titanium surface and low intensity cannot remove enough microbial biofilm. The aim of this study was to investigate the optimal energy setting of Er:YAG laser for decontamination of sandblasted/acid-etched (SLA) and hydroxyapatite (HA) titanium surfaces.

Material and methods

After supragingival biofilm construction in vivo, SLA and HA titanium discs were divided into three groups: blank control (BC, clean discs), experimental control (EC, contaminated discs) and experimental groups (EP, contaminated discs irradiated by Er:YAG laser at 40, 70, and 100 mJ/pulse). Scanning electron microscopy (SEM), live/dead bacterial fluorescent detection, and colony counting assay were used to detect the efficacy of laser decontamination. To investigate the effect of laser decontamination on titanium surface biocompatibility, MC3T3-E1 cell adhesion and proliferation activity were examined by SEM and CCK-8 assay.

Results

Er:YAG laser irradiation at 100 mJ/pulse removed 84.1% of bacteria from SLA titanium surface; laser irradiation at 70 and 100 mJ/pulse removed 76.4% and 77.85% of bacteria from HA titanium surface respectively. Laser irradiation improved MC3T3-E1 cell adhesion on both titanium surfaces. For SLA titanium discs, 100 mJ/pulse group displayed excellent cellular proliferation activity higher than that in BC group (P < 0.01). For HA titanium discs, 70 mJ/pulse group showed the highest activity comparable to BC group (P > 0.05).

Conclusions

With regards to efficient microbial biofilm decontamination and biocompatibility maintenance, Er:YAG laser at 100 mJ/pulse and 70 mJ/pulse are considered as the optimal energy settings for SLA titanium and HA titanium surface respectively. This study provides theoretical basis for the clinical application of Er:YAG laser in the treatment of peri-implantitis.

Evaluation of Surface Roughness of a Ni-Cr Alloy Treated With the Nd/YAG Laser and the Sandblast Technique

Introduction: This study was to assess the effect of various output parameters of laser treatment on roughening the surface of a commercial nickel-chromium (Ni-Cr) alloy as compared to the sandblasting technique. Materials and Methods: Ninety-six disk-shaped (5 mm diameter and 2 mm thickness) specimens in total were made of a nickel-chromium alloy by using the lost-wax technique. Air-abrasion surface treatment was used for sixteen specimens. Specimens were divided into six groups; one of them was sandblasted and the rest were irradiated by different Nd:YAG laser output parameters as follows: Group A: energy: 122 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 1.5 mm; Group B: energy: 122 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 3.5 mm; Group C: energy: 122 mJ, frequency: 10 Hz, irradiation duration: 20 seconds, spot size: 3.5 mm; Group D: energy: 102 mJ, frequency: 10 Hz, irradiation duration: 20 seconds, spot size: 3 mm; Group E: energy: 102 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 3 mm. The surface roughness of all surface-treated specimens was evaluated by using a profilometer, and their average roughness (Ra) was calculated. The average value of each group was analyzed by t test and one-way ANOVA (SPSS 17). Results: Significant differences (P<0.05) were observed between the study groups. The highest Ra was achieved for the sandblasted group. The Ra value in group C was the highest value among the laser-etched groups. Conclusion: Based on the results, Nd:YAG laser irradiation increases surface roughness, but it is not as efficient as the sandblasting method as a gold standard.

Novel flapless esthetic procedure for the elimination of extended gingival metal tattoos adjacent to prosthetic teeth: Er:YAG laser micro-keyhole surgery

PURPOSE

This article describes a novel, minimally invasive procedure called Er:YAG laser micro-keyhole surgery (EL-MIKS) that removes metal or amalgam tattoos in the gingiva adjacent to prosthetic teeth without gingival deformity and recession. We aimed to evaluate the clinical efficacy of EL-MIKS for removing metal tattoos and present its long-term treatment outcomes.

METHODS

The EL-MIKS procedure consists of several steps that are all performed under a microscope. First, a micro-keyhole (1-2 mm diameter) was prepared using an Er:YAG laser in the center of the metal pigmentation. The connective tissue was evaporated in the deep layer, where metal debris was deposited. Second, within the accessible range, the irradiation angle was changed in various directions to ablate the metal pieces and discolored connective tissue without enlarging the keyhole. Finally, after blood filled the space created by the tissue evaporation, the surface of the blood clot at the entrance of the micro-keyhole was thermally coagulated with defocus laser irradiation. Pigmentation that could not be successfully removed from a single micro-keyhole was treated by forming new micro-keyholes at a distance of 3 mm or more from each previously created hole. Depigmentation over an extended area was completed over a few sessions every 4 weeks without gingival recession after surgery.

CONCLUSIONS

EL-MIKS, a novel depigmentation technique, was able to successfully remove an extended area of metal tattoos in the gingiva using a simpler, easier, and less invasive procedure than conventional periodontal plastic surgery. Esthetic restoration was successfully achieved without postoperative alteration of the gingival contour.

The Use of Lasers in Dental Materials: A Review

Lasers have been well integrated in clinical dentistry for the last two decades, providing clinical alternatives in the management of both soft and hard tissues with an expanding use in the field of dental materials. One of their main advantages is that they can deliver very low to very high concentrated power at an exact point on any substrate by all possible means. The aim of this review is to thoroughly analyze the use of lasers in the processing of dental materials and to enlighten the new trends in laser technology focused on dental material management. New approaches for the elaboration of dental materials that require high energy levels and delicate processing, such as metals, ceramics, and resins are provided, while time consuming laboratory procedures, such as cutting restorative materials, welding, and sintering are facilitated. In addition, surface characteristics of titanium alloys and high strength ceramics can be altered. Finally, the potential of lasers to increase the adhesion of zirconia ceramics to different substrates has been tested for all laser devices, including a new ultrafast generation of lasers.

Lasers in Maxillofacial Surgery - Review of Literature

The availability of different wavelengths of lasers has created a surgical panacea in the last decade and laser technology has become the standard of care for many oral and maxillofacial surgical procedures. In this article, based on literature search, we have reviewed the usage of laser in maxillofacial surgery based on the current evidence available on laser-assisted maxillofacial surgery, in PubMed database.

Effect of Different Nd:YAG Laser Power Outputs on Bond Strength of Resin Cement to Zirconia in Comparison to Sandblasting

Introduction: This study investigated the effect of various laser powers on the shear bond strength (SBS) of resin cement to the zirconia surface. Methods: Seventy-five zirconia disks were prepared and assigned to five groups including no surface treatment (control group), sandblasting with 50 µ Al₂ O₃ particles (second group), and Nd:YAG laser treatments with 2 W, 2.5 W and 3 W powers respectively (third, fourth and fifth groups). Afterwards, composite resin cylinders were cemented on zirconia disks using dual-curing resin cement. Before thermocycling (2000 cycles, 5-55°C), all samples were placed in distilled water at 37°C for 24 hours. Using a universal testing machine at the crosshead speed of 0.5 mm/min, the SBS was examined. Also, using a stereomicroscope, the failure type was determined. Data analyses were performed using Welch and Games-Howell tests (P < 0.05). Results: The mean bond strength difference between the control group and the other groups was significant. The respective bond strength from the highest to the lowest was observed in the sandblast group, the laser group with 2.5 W power, the laser group with 3 W power, the laser group with 2 W power, and finally the control group. However, no significant difference was observed between different laser groups (P < 0.05). Also, there was no significant difference between the sandblast and laser groups with 2.5 W and 3 W power (P < 0.05). Most of the failures in the sandblasting and laser groups with powers of 2.5 W and 3 W were mixed, but in the control and 2 W laser groups, most of the failures were of adhesive nature. Conclusion: The highest bond strength was achieved by sandblasting with Al₂ O₃ particles and then using an Nd: YAG laser with a power of 2.5 W.

Effect of Er:YAG laser irradiation using SWEEPS and PIPS technique on dye penetration depth after root canal preparation

BACKGROUND

This study aimed to investigate the penetration depth of two different dyes after root canal preparation using PIPS and SWEEPS methods.

MATERIALS AND METHODS

A total of 60 single-rooted human teeth which were extracted for periodontal reasons were collected and stored in the sterile saline until using in the study. The crowns of the teeth were cut such that the remaining piece was 12 mm long. The root canals were prepared. Teeth were divided randomly into two initial groups (n = 30): indocyanine green solution (ICG) and methylene blue solution. Then, these teeth were divided into final subgroups (n = 10): Er:YAG laser irradiation with PIPS(photon-induced photoacoustic streaming) technique, Er:YAG laser irradiation with SWEEPS(shock-wave enhanced emission photoacoustic streaming) technique, and no irradiation. The penetration depth measurements were done by the stereo microscope in three zones of each specimen.

RESULTS

The difference between ICG in the control group and PIPS and SWEEPS in the coronal area was not significant. In the middle section the difference between PIPS and the control group was marginally insignificant (P = 0.053). In the methylene blue group, PIPS had significantly higher penetration depth in the apical area compared to the control group (P = 0.004). In the middle section, both PIPS and SWEEPS showed significantly higher penetration than the control group.

CONCLUSION

According to the results of this study, the laser has the potential to increase the penetration of methylene blue. Root canal preparation with the PIPS technique can increase the dye penetration. However, the SWEEPS technique and the conventional method have a similar outcome in terms of dye penetration.

Removal of Composite Restoration from the Root Surface in the Cervical Region Using Er: YAG Laser and Drill-In Vitro Study

Background: Recently, the defects of the tooth surface in the cervical region are often restored using composite filling materials. It should meet the needs of the patients regarding esthetics and material stability. The aim of the study was to analyze the tooth root surface at the cervical region after the removal of the composite filling material by means of the Erbium-doped Yttrium Aluminium Garnet (Er: YAG) laser or drill using the scanning electron microscopy (SEM) and fluorescence microscopy. Materials and Methods: For the purposes of this study, 14 premolar teeth (n = 14) were removed due to orthodontic reasons. The rectangular shape cavities with 3 mm in width and 1.5 mm in height were prepared with a 0.8 mm bur on high-speed contra-angle in the tooth surface just below cemento-enamel junction (CEJ) and filled with the composite material. The composite material was removed with the Er: YAG laser at a power of 3.4 W, energy 170 mJ, frequency 20 Hz, pulse duration 300 μs, tip diameter 0.8 mm, air/fluid cooling 3 mL/s, and time of irradiation: 6 sec, at a distance from teeth of 2 mm (G1 group, n = 7) or a high-speed contra-angle bur (G2 group, n = 7). After the removal of composite material, the surfaces of teeth were examined using the scanning electron microscopy (SEM) and fluorescence microscopy. Results: The Er: YAG irradiation allowed to remove completely the composite material from the tooth cavity. The study confirmed, that the ends of collagen fibers were only partially denatured after the Er: YAG laser application. Conclusion: It has been proved that using the Er: YAG laser is an effective and safe method of composite removal for the dentin surface.

Use of Laser Systems in Orthodontics

Laser systems have been used in the practice of dentistry for >35 years. Laser systems have so many advantages, such as increase patient cooperation, reduce the duration of treatment time, and help the orthodontists to enhance the design of a patient's smile to improve treatment efficacy, and the success of orthodontic treatments can also be improved by diminishing the orthodontic pain and the discomfort of the patients. Laser systems also have some disadvantages, such as cost, large space requirements for some types, and high-risk potential for physician and patient if not used at the appropriate wavelength and power density, that is why before incorporating lasers into clinical practice, the physician must fully understand the basic science, safety protocol, and risks associated with them. Lasers have many applications in orthodontics, including accelerating tooth movement, bonding and debonding processes, pain reduction, bone regeneration, etching procedures, increase mini-implant stability, soft tissue procedures (gingivectomy, frenectomy, operculectomy, papilla flattening, uncovering temporary anchorage devices, ablation of aphthous ulcerations, and exposure of impacted teeth), fiberotomy, scanning systems, and welding procedures. In reviewing the literature on the use of laser in orthodontics, many studies have been conducted. The purpose of the present study was to give information about the use of laser in the field of orthodontics, the effects of laser during the postoperative period, and its advantages and disadvantages and to provide general information about the requirements to be considered during the use of laser.

Juvenile Hyaline Fibromatosis Management With a Diode Laser: A Rare Case Report

Juvenile hyaline fibromatosis (JHF) is an unknown hereditary disorder with variable penetrance. The characterizations of this disease consist of different signs and symptoms such as multiple tumorous (tumor-like) muco-cutaneous proliferation, gingival hypertrophy, perianal lesions, articular contractures, and osteolytic lesions. A 3-year-old girl with numerous painless nodular masses on her gingival, ear and anal areas is presented in this case report. Based on characteristic histological features, the diagnosis of JHF was made. The patient underwent surgery following general anesthesia and the above areas were surgically operated with appropriate laser parameters, and the patient was able to eat and wash away after a day and was discharged with an antibiotic prescription after one day in the hospital and returned to normal after a week. The recurrence occurred in other areas a year later, especially in the cheek, the ears and the anal area. Therefore, this rare case is presented with recurrence.

Evaluation of Enamel Topography after Debonding Orthodontic Ceramic Brackets by Different Er,Cr:YSGG and Er:YAG Lasers Settings

In the last decade, the success of lasers in simplifying many dental procedures has heightened the need for research in the orthodontic field, in order to evaluate the benefits of laser-assisted ceramic brackets debonding. Conventional ceramic brackets removal delivers a high shear bond strength (SBS), which might lead to enamel damage. Nowadays, debonding ceramic brackets by Er:YAG laser seems a viable alternative technique; however, there is no data on the use of Er,Cr:YSGG in the literature. We aimed to evaluate the difference in enamel topography derived from different erbium laser settings used during debonding. One hundred and eighty bovine incisors teeth were randomly divided into fifteen experimental groups, according to different erbium laser settings using scanning methods. SBS testing was performed after debonding; stereomicroscopic and SEM analyses were done after cleaning the remaining adhesive so as to assess the incidence of enamel microcracks formation and enamel loss. There were no statistically significant differences between the proportions of teeth with normal enamel topography within the control group when compared with any of the Er:YAG groups. However, the proportion of teeth with a normal enamel topography in Er,Cr:YSGG was 4 W/20 Hz (83.3%) and in Er:YAG was 5 W/20 Hz (91.7%), which was statistically significantly higher than the control group (41.7%). The selection of erbium lasers' optimal parameters during debonding influences the enamel topography. When considering the evaluation of both microscopic and statistical analyses, irradiation by Er:YAG (120 mJ/40 Hz) displayed a significant reduction in microcracks compared with conventional debonding, even though some microstructural changes in the enamel could be noted. Er,Cr:YSGG (4 W/20 Hz) respected the enamel topography the most out of the studied groups.

Effects of Er:YAG Laser on the Attachment of Human Periodontal Ligament Fibroblasts to Denuded Root Surfaces Simulating Delayed Replantation Cases: An In Vitro Study

Objective: To investigate the effects of Er:YAG laser on the attachment of human periodontal ligament fibroblasts (hPDLFs) to denuded root surfaces simulating delayed replantation cases. Background data: Dental avulsion is one of the most severe dental traumas, which is often treated with replantation. In delayed replantation scenarios, poor prognosis, including root resorption, usually occurs due to poor root surface conditioning and nonviable hPDLF attachment. Methods: Thirty-six root fragments (5 × 5 × 2 mm) were obtained from periodontium tissue-free premolar root surfaces. Specimens were randomly and equally assigned to the following: Group A, untreated control; Group B, 25 J/cm² and 10 Hz of Er:YAG laser irradiation; and Group C, 50 J/cm² and 10 Hz of Er:YAG laser irradiation. Some specimens in each group were then prepared for surface topography visualization under SEM, others were subjected to coculture with hPDLF suspension, and cell adhesion was further evaluated by SEM. Results: Group A presented homogenous smooth root surface, with fewer and round-shaped cells attached; Group B and C exhibited rather rough and irregular morphologies, and spindle-shaped fibroblasts were firmly attached by numerous lamellipodia and extensions. After a 3-day coculture, the number of fibroblasts attached in Group A was significantly lower compared with the other two laser-treated groups (p = 0.008 < 0.05). No significant alterations were observed between the two laser groups (p = 0.135 > 0.05). Conclusions: Er:YAG laser-treated root surfaces are compatible for the attachment of PDLFs, which suggests that Er:YAG laser irradiation may be used as a promising strategy for root surface conditioning in delayed replantation cases.

Influence of Er,Cr:YSGG Laser Irradiation on the Push-Out Bond Strength of Zirconia and Glass Fiber Posts with Radicular Dentin

Objective

This in vitro study was designed to evaluate the influence of an Er,Cr:YSGG laser on the bond strength of zirconia and glass fiber posts with root dentin.

Materials and methods

Ninety extracted single-rooted human teeth were randomized into 6 groups (n = 15/group) on the basis of different posts (zirconia/glass fiber) and Er,Cr:YSGG laser tips (axial and radial). Specimens were prepared for push-out testing with the help of a cutting machine; six slices (2 on each cervical, middle, and apical) of approximately 1 mm thickness were sectioned for all roots on a plane perpendicular to the long axis of the post. All specimens were placed into a universal testing machine with a defined 0.5 mm/min crosshead speed until the maximum failure load was obtained.

Results

The highest mean push-out bond strength of the glass fiber and zirconia groups was achieved with laser treatment. The highest push-out bond strength was achieved with the axial fiber tip (7.63 ± 1.22 MPa), and the lowest was achieved with a radial fiber tip of the glass fiber group (6.98 ± 0.96 MPa). ANOVA showed a statistically significant difference between the groups (p = 0.041). The mean push-out bond strength was found to be higher with an axial fiber tip for both cervical and apical segments in the glass fiber and zirconia groups (p < 0.05). The independent t-test resulted in the overall highest mean push-out bond strength in the apical segments (p = 0.026).

Conclusion

Within the limits of the present in vitro research study, an enhancement in the push-out bond strength of resin cement, mainly in the cervical region of the root canal, was achieved after irradiation with an Er,Cr:YSGG laser using an axial fiber tip.

Reduced Need of Infiltration Anesthesia Accompanied With Other Positive Outcomes in Diode Laser Application for Frenectomy in Children

Introduction: The abnormal maxillary labial frenum is common in children during the primary or mixed dentition stage. A conventional surgery for this abnormality usually requires infiltration anesthesia which leads to fear in children and consequent noncooperation during the surgery. The aim of present study was to evaluate the reduction in the need of infiltration anesthesia, intraoperative bleeding control and postoperative pain and wound healing in children when using the diode laser for abnormal labial frenum in the maxilla. Methods: The present study was carried out among 30 children attending the Hanoi Medical University, Vietnam. A Diode Laser with 810 nm wavelength and power of 0.8 W was used for frenectomy. Results: The proportion of procedures without any need of infiltration anesthesia was 70%, while 93.34% of children demonstrated positive and very positive behavior. Proportion of indolence on the first day after surgery was 83.3%. While 83.3% of children did not take any analgesics, not a single child complained of any pain 3 days after surgery. Conclusion: Our results indicated that the use of diode laser showed several benefits in maxillary labial frenectomy in children. These included reducing the need of infiltration anesthesia, increasing the children's cooperation as well as decreasing the postoperative pain.

Evaluation of zirconia surface roughness after aluminum oxide airborne-particle abrasion and the erbium-YAG, neodymium-doped YAG, or CO2 lasers: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Veneer chipping and crown decementation are the most frequent failures in restorations using zirconia as an infrastructure. Increasing the roughness of the zirconia surface has been suggested to address this problem.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate yttria-stabilized tetragonal zirconia polycrystal surface roughness, produced with aluminum oxide airborne-particle abrasion and the erbium yttrium aluminum garnet (YAG), neodymium-doped YAG, or CO₂ lasers.

MATERIAL AND METHODS

This study was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. The review identified relevant studies through December 2017 with no limit on the publication year in the search databases: Web of Science, Scopus, and MEDLINE via PubMed. The selected studies were submitted to a risk of bias assessment. The means and standard deviations of roughness were evaluated for the meta-analysis using Review Manager software.

RESULTS

The 17 studies that met all inclusion criteria presented a medium risk of bias. All the treatment methods tested were able to create a roughness on the yttria-stabilized tetragonal zirconia polycrystal surface. The I² test values presented a high heterogeneity among the studies.

CONCLUSIONS

The presintered specimens submitted to airborne-particle abrasion had higher surface roughness compared with abrasion after the sintering process. Irradiation with the neodymium-doped YAG and CO₂ lasers was destructive to the zirconia surfaces. The erbium laser used with lower energy intensity appears to be a promising method for surface treatment.

Gingival augmentation by combination of laser and Acellular Dermal Matrix allograft in a patient with dystrophic form of epidermolysis bullosa: A case report

A patient suffering from epidermolysis bullosa with gingival recession and lack of attached gingiva of the mandibular anterior teeth. Treatment was performed to increase the amount of attached gingiva. An erbium laser was used and the site augmented with Acellular Dermal Matrix allograft to reduce the donor site surgical complications.

Treating Mucocele in Pediatric Patients Using a Diode Laser: Three Case Reports

A mucocele is the most common minor salivary gland disease and among the most common biopsied oral lesions in pediatric patients. Clinically, a mucocele appears as a round well-circumscribed painless swelling ranging from deep blue to mucosa alike in color. Mucoceles rarely resolve on their own and surgical removal under local anesthesia is required in most cases. Different treatment options are described in the literature, including cryosurgery, intra-lesion injection of corticosteroid, micro-marsupialization and conventional surgical removal using a scalpel, and laser ablation. Therefore, the goal of this paper was to report three cases of mucocele removal in pediatric patients using a diode laser with a one-month follow-up. Mucoceles were removed by a pediatric dentist using a diode laser with a wavelength of 930 nm in continuous mode and a power setting of 1.8 Watts. In all cases, no bleeding occurred during or after the procedure and there was no need for suturing. On clinical examination during the one-month follow-up, in all three cases there was minimal or no scarring, minimal post-operative discomfort or pain, and no recurrence. Diode lasers provide an effective, rapid, simple, bloodless and well accepted procedure for treating mucocele in pediatric patients. Minimal post-operative discomfort and scarring was reported by all the three patients.

Comparative study on the incision healing of the palatal mucosa by using Er:YAG laser or traditional scalpel in the SD rats

The aim of this study was to compare the histology of wound healing following incisions with the scalpel or the Er:YAG laser in the palatal mucosa of SD rats. Two types of wounds were performed with the stainless steel scalpel or the Er:YAG laser in the palatal mucosa of SD rats, while the adjacent untreated palatal mucosa was chosen as control. Rats were sacrificed on day 1, day 3, day 7, and day 30 post-surgery. Biopsy samples from each wound were examined and the expression of IL-1ß and TGF-ß1 was determined by enzyme-linked immunosorbent assay (ELISA). The early postoperative incision of the scalpel group had obvious bleeding and swelling, while the laser wound mainly covered the surface of white pseudomembrane. The infiltration of neutrophils and lymphocytes in the stroma of the scalpel incision was more than that of the laser group. Compared to the laser group, 1 and 3 days after operation, the TGF-β1 content of the scalpel group were significantly increased (P = 0.032 and 0.019). Seven days after operation, the TGF-β1 content of two groups was decreased. TGF-β1 expression of control group was obviously increased (P > 0.05); 1, 3, and 7 days after operation, the traditional scalpel amount of IL-1β expression was significantly higher than that of control group (P = 0.000, 0.000, and 0.001). Postoperative day 1, IL-1β expression of laser group and control group had no significant difference (P = 0.572). Three days after operation, IL-1β expression of laser incision was increased and was significantly higher than that in control group (P = 0.032), however lower than the scalpel group (P = 0.03). Seven days after operation, the IL-1β expression of two groups had no significant difference (P = 0.333); however, the IL-1β expression of two groups were significantly higher than that of the control group (P = 0.02 and 0.001). Compared to the traditional scalpel, the incision of Er:YAG laser has smaller inflammation reaction, more pseudomembrane coverage, and minimal damage of the mucoperiosteal tissue.

Paediatric dentistry- novel evolvement

Pediatric dentistry provides primary and comprehensive preventive and therapeutic oral health care for infants and children through adolescence, together with special health care needs. This specialty encompasses a variety of skills, disciplines, procedures and techniques that share a common origin with other dental specialties however these have been modified and reformed to the distinctive requirements of infants, children, adolescents and special health care needs. Disciplines comprise of behavior guidance, care of the medically and developmentally compromised and disabled patient, supervision of orofacial growth and development, caries prevention, sedation, pharmacological management, and hospital dentistry including other traditional fields of dentistry. The skills apply to the ever-changing stages of dental, physical, and psychosocial development for treating conditions and diseases distinctive to growing individuals. Hence with the changing scope of practice it is imperative that the clinician stays updated with the current evidence based trends in practice, collaborates with other disciplines and Imparts quality oral health care tailored to the specific needs of every child.

Effect of 810 nm diode laser on physiologic gingival pigmentation

Background and aims

Physiologic gingival pigmentation (PGP) is the most common type of gingival pigmentation causing esthetic concerns particularly in gummy smile patients. Laser therapy is an effective and noninvasive treatment modality for such patients. This study aimed to evaluate the efficacy of diode laser for treatment of PGP.

Subjects and methods

This quasi-experimental study (one-group pretest-post-test design) was conducted on 20 patients complaining of gingival melanin pigmentation. The gingiva of the anterior segment of the arch was ablated with 810 nm diode laser until the entire visible pigmentation was removed. Clinical observations for the intensity of pigmentation were made at baseline, one month and three months, postoperatively. Data were analyzed using SPSS and Friedman test.

Results

Preoperatively, the mean score of gingival melanin pigmentation in the maxilla and mandible was 2.95. At one month postoperatively, the mean scores of the maxilla and mandible were 1.53 and 1.55, respectively. After three months, the mean rank of scores of the maxilla and mandible was 1.53 and 1.50, respectively. The difference between the pre- and postoperative mean scores was statistically significant (P < 0.001).

Conclusion

Diode laser therapy is an effective and minimally invasive modality for gingival depigmentation. But further investigations with long-term follow ups are warranted in this respect.

Surface modifications of human tooth using Nd:YAG laser for dental applications

Ablation using Nd:YAG laser has potential in resulting a rough effect on tooth surfaces. The objective of this study is to perform a comparative evaluation of the roughness structure of enamel using the Cynosure Cynergy Nd:YAG laser and 37% phosphoric acid. The results obtained for laser-etched with a pulse width of 300ms show roughed and porous surface with greater depth. Both show remarkable graininess on the surface and fewer indentations. Comparison of the elemental compositions demonstrated that calcium has higher composition when exposed to laser-etch compared to acid-etch. The atomic percentages of calcium in sample A for acid-etched and laser-etched are 5.08 and 9.61, respectively. While acid-etched and laser-etched for sample B are 3.98 and 12.84, respectively. Other elements are not profoundly affected by the technique used in this study. However, carbon and oxygen show inconsistent results for both of the samples. Thus, Nd:YAG laser provides significant effects on the tooth surface but does not primarily modify the element compositions of the tooth. Therefore, Nd:YAG laser can potentially be implemented for etching procedure as a replacement of acid etching technique.

Influence of laser irradiation on the push-out bond strength between a glass fiber post and root dentin

STATEMENT OF PROBLEM

A major issue related to the failure of endodontically treated teeth restored with an intraradicular post is gradual debonding of the glass fiber post, resin cement, and dentin.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of laser irradiation on the push-out bond strength of glass fiber posts to radicular dentin.

MATERIAL AND METHODS

Thirty-two mandibular bovine incisors were endodontically treated and divided into 4 groups according to the surface treatment of the post: silane control (GC); irradiation with Er:YAG (GYAG); irradiation with Er,Cr:YSGG (GCR); and 980-nm diode laser (GDI) application. After surface treatment, the glass fiber posts were cemented with dual adhesive resin cement. To evaluate bond strength, the specimens were subjected to a push-out test at a crosshead speed of 0.5 mm/min using a universal testing machine. Failure mode was analyzed using stereomicroscopy. The surface morphology was evaluated qualitatively after surface treatment by using confocal laser microscopy. The push-out test data (MPa) were analyzed using a linear mixed effects model and the Bonferroni test (α=.05).

RESULTS

At the cervical third, no significant differences were observed between the GC and GCR groups (P=1.00), and both of the groups exhibited higher bond strength. At the middle and apical thirds, the GCR group revealed higher bond strength, which was significantly different from that observed in all other groups (P<.05). No statistical differences were observed among the other tested protocols (GC, GYAG, and GDI groups; P=1.00). Adhesive failure was predominant in all groups.

CONCLUSIONS

Irradiation with Er,Cr:YSGG improved the bond strength of the cement-post-dentin interfaces.

In Vitro-Activity of Er:YAG Laser in Comparison with other Treatment Modalities on Biofilm Ablation from Implant and Tooth Surfaces

BACKGROUND AND AIM

Bacterial biofilms play a major role in the etiology of periodontal and peri-implant diseases. The aim of the study was to evaluate the removal of bacterial biofilms and attachment of epithelial cells (EC), gingival fibroblasts (GF) and osteoblast-like cells (OC) to dentin and titanium surfaces after Er:YAG laser (Er:YAG) in comparison with other treatment methods.

MATERIAL AND METHODS

Multi-species bacterial biofilms were grown on standardized dentin and titanium specimens with a sand-blasted and acid etched (SLA) surface for 3.5 d. Thereafter, the specimens were placed into artificially-created pockets. The following methods for biofilm removal were used: 1) Gracey (dentin) or titanium curettes (CUR), 2) Er:YAG, 3) photodynamic therapy (PDT) and 4) CUR with adjunctive PDT (CUR/PDT). Colony forming units (CFUs) of the remaining biofilms and attachment of EC, GF and OC were determined. Statistical analysis was performed by means of ANOVA with post-hoc LSD.

RESULTS

All treatment methods decreased statistically significantly (p<0.001) total CFUs in biofilms compared with untreated dentin and titanium surfaces respectively. On dentin, Er:YAG was equally efficient as CUR and PDT but inferior to CUR/PDT (p = 0.005). On titanium, surfaces, the use of Er:YAG resulted in statistically significantly superior biofilm removal compared to the 3 other treatments (each p<0.001). Counts of attached EC, GF and OC were the lowest on untreated contaminated dentin and titanium surfaces each. After CUR/PDT higher EC counts were found on dentin (p = 0.006). On titanium, all decontamination methods statistically significantly increased (p<0.001) the counts of attached EC without differences between groups. Statistically significantly higher counts of GF (p = 0.024) and OC (p<0.001) were observed after Er:YAG decontamination compared with untreated surfaces.

CONCLUSION

Ablation of subgingival biofilms and in particular decontamination of titanium implant surfaces with an Er:YAG laser seem to be a promising approach and warrants further investigations.

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.

Evaluation of Mechanical Properties of Glass Fiber Posts Subjected to Laser Surface Treatments

OBJECTIVE

The aim of this study was to evaluate the influence of laser irradiation on flexural strength, elastic modulus, and surface roughness and morphology of glass fiber posts (GFPs).

BACKGROUND DATA

Laser treatment of GFPs has been introduced to improve its adhesion properties.

MATERIALS AND METHODS

A total of 40 GFPs were divided into 4 groups according to the irradiation protocol: GC-no irradiation, GYAG-irradiation with erbium:yttrium-aluminum-garnet [Er:YAG], GCR-irradiation with erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG), and GDI-irradiation with diode laser. The GFP roughness and morphology were evaluated through laser confocal microscopy before and after surface treatment. Three-point bending flexural test measured flexural strength and elastic modulus. Data about elastic modulus and flexural strength were subjected to one-way ANOVA and Bonferroni test (p < 0.05). The effect of roughness was evaluated using the linear mixed effects model and Bonferroni test (p < 0.05).

RESULTS

Laser treatment changed surface roughness in the groups GCR (p = 0.000) and GDI (p = 0.007). The mean flexural strength in GYAG (995.22 MPa) was similar to that in GC (980.48 MPa) (p = 1.000) but different from that in GCR (746.83 MPa) and that in GDI (691.34 MPa) (p = 0.000). No difference was found between the groups GCR and GDI (p = 0.86). For elastic modulus: GYAG (24.47 GPa) was similar to GC (25.92 GPa) (p = 1.000) but different from GCR (19.88 GPa) (p = 0.002) and GDI (17.20 GPa) (p = 0.000).

CONCLUSIONS

The different types of lasers, especially Er,Cr:YSGG and 980 ηm diode, influenced the mechanical properties of GFPs.

Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

BACKGROUND

The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching.

MATERIAL AND METHODS

The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05).

RESULTS

A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching.

CONCLUSIONS

The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material.

KEY WORDS

Laser, diode, dentin, tubule, diameter.

Using low level laser therapy to reduce early postoperative airway obstruction following modified Hogan's flap

INTRODUCTION AND OBJECTIVE

The most common postoperative complications of velopharyngeal insufficiency surgery are postoperative bleeding and airway obstruction or obstructive sleep apnoea. Consequently, the aim of this study was to evaluate the effect of low level laser therapy (LLLT) during the first postoperative days in children undergoing superiorly based pharyngeal flap (SBF) surgery.

MATERIALS AND METHODS

A randomized double blind clinical study on 30 children divided on two groups 15 patients each, who underwent SBF. LLLT was used in a group and the other was a control group. The study was conducted in academic tertiary care medical centres between 2013 and 2015. The degree of edema, oxygen saturation, occurrence of obstructive sleep apnoea (OSA) and steroid administration were recorded.

RESULTS

The mean of the average oxygen saturation was significantly less in the control group in the 1st and 2nd day as compared to the laser group. The need for oxygen and the incidence of OSA in the first 3 days were significantly higher in the control group as compared to the laser group. The degree of edema showed no significant difference in the first day but was significantly higher in the control group in the 2nd and 3rd days. Hence, the need of steroids was significantly higher in the control group in the first 3 days.

CONCLUSIONS

Preliminary results showed that low level laser therapy is effective in reducing the incidence of early postoperative airway obstruction after SBF operations.