Clinical evaluation of periodontal surgical treatment with an Er:YAG laser: 5-year results

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.

Enhanced periodontal tissue healing via vascular endothelial growth factor expression following low-level erbium-doped: yttrium, aluminum, and garnet laser irradiation: In vitro and in vivo studies

BACKGROUND

This study aimed to investigate the effects of low-level erbium-doped: yttrium, aluminum, and garnet (Er:YAG) laser irradiation on periodontal tissue healing and regeneration through angiogenesis in vivo and in vitro studies.

METHODS

Intrabony defects were surgically created in the bilateral maxilla molar of rats. The defects were treated by open flap debridement (OFD) with Er:YAG laser, including low-level laser irradiation (LLLI) to bone and blood clot surfaces, or conventional procedures. The mRNA expression of vascular endothelial growth factor (VEGF) in the surgical sites was quantified using real-time polymerase chain reaction. The decalcified specimens were prepared for histometric analysis. Also, LLLI was performed on human umbilical vein endothelial cells to evaluate the effects on angiogenesis. Cell proliferation, VEGF expression, and tube formation were assessed. In addition, capsazepine (CPZ), a selective inhibitor of transient receptor potential vanilloid 1 (TRPV1), treatment was performed before LLLI for the same assays.

RESULTS

OFD using Er:YAG laser did not generate thermal damage on bone or root surfaces. LLLI accelerated hemostasis by coagulation of the superficial layers of blood clots in the laser-treated group. Postoperative healing was sound in all animals in both groups. VEGF expression and bone formation were significantly increased in the laser-treated group compared to those in the conventional treatment group. In vitro, cell proliferation and VEGF expression were significantly increased in the LLLI group compared to the control group. Tube-formation assays showed that LLLI significantly promoted angiogenesis. CPZ treatment significantly suppressed VEGF expression and tube formation following LLLI.

CONCLUSIONS

This study suggests that Er:YAG laser irradiation may promote periodontal tissue healing by enhancing angiogenetic effect of endothelial cells via TRPV1.

Root surface biomodification in periodontal therapy: Biological rationale and clinical applications

Regenerative periodontal therapy aims to form new cementum, periodontal ligament, and alveolar bone, all sealed by gingival tissue. The root surface acts as the wound margin during this regeneration process. Root surface biomodification (root conditioning/root decontamination), therefore, seems instrumental in promoting surface decontamination and enhancing tissue attachment by removing the smear layer, exposing collagen fibrils, and facilitating blood clot formation and stabilization. This review attempted to provide an all-encompassing, evidence-based assessment of the role of root surface biomodification in regenerative periodontal therapy, particularly in intrabony defects, furcation defects, and root coverage procedures. The reviewed evidence suggested that root conditioning agents, whether used independently or in conjunction with bone graft materials, biological agents, membranes, or connective tissue grafts, do not offer any clinical advantage regarding clinical attachment gain. Thus, integrating chemical methods with the mechanical root instrumentation process does not necessarily contribute to superior clinical outcomes.

Biofilm removal from Difficult-to-Reach places via secondary cavitation within a constrained geometry mimicking a Periodontal/Peri-Implant pocket

Biofilm removal from the apical region of the periodontal or peri-implant pocket, which is very difficult to achieve with mechanical instruments, is a major unresolved issue in dentistry. Here, we propose the use of photoacoustically induced streaming and secondary cavitation to achieve superior cleaning efficacy in the apical region of the periodontal and peri-implant pocket. We have used a prefabricated narrow wedge system that mimics the consistency of periodontal and peri-implant pockets of both healthy and severely inflamed tissue. We studied the effect of single-pulse modality Er:YAG on Pseudomonas aeruginosa biofilm removal. We used different laser energies, fiber-tip positions, and laser treatment durations. The cleaning process was monitored in real-time with a high-speed camera after each individual laser pulse application. The obtained results suggest that biofilm cleaning efficacy in a difficult-to-reach place in healthy model tissue is directly related to the onset of secondary cavitation bubble formation, which correlates with a significant improvement of biofilm removal from the apical region of the periodontal or peri-implant pocket. In comparison to the healthy tissue model, the laser energy in inflamed tissue model had to be increased to obtain comparable biofilm cleaning efficacy. The advantage of photoacoustic cavitation compared to other methods is that laser-induced cavitation can trigger secondary cavitation at large distances from the point of laser application, which in principle allows biofilm removal at distant locations not reachable with a laser fiber tip or other mechanical instruments.

A simplified mid-infrared anti-resonant chalcogenide fiber with fewest resonant peaks

High-power laser delivery in the mid-infrared via hollow-core fibers is attractive, but it is too difficult to be fabricated using chalcogenide glasses. Here, we designed a mid-infrared hollow-core anti-resonant chalcogenide fiber (HC-ARCF) with a simplified Kagome cladding micro-structure for the first time. Then, the fiber was firstly fabricated through a precision mechanical drilling and pressured fiber drawing method. Ultra-thin walls of 2μm in the fiber lead to the fewest resonance peaks in the 2-5μm among all reported HC-ARCFs. All the fundamental mode, the second-order mode, tube mode and node mode in the fiber were excited and observed at 1550 nm. The power and spectral properties of the core and cladding of HC-ARCF are studied for the first time. The fiber can deliver high-power of 4.84 W without damage with core-coupling, while the threshold of the node in the cladding is only 3.5 W. A broadening of the output spectrum from 1.96 to 2.41μm due to the high nonlinearity at the node was successfully observed under short-pulse laser pumping at 2μm. The potentials of the fiber used for mid-infrared high-power laser delivery via core, or nonlinear laser generation via node, were thus demonstrated.

The Application of Antimicrobial Photodynamic Therapy (aPDT) in the Treatment of Peri-Implantitis

Background

This literature review evaluates the mechanisms and efficacy of different types of antimicrobial photodynamic therapy (aPDT) for treating peri-implantitis by reviewing existing experimental studies to provide guidance for the clinical application of antibacterial photodynamic therapy (aPDT) in oral implants.

Materials and Methods

From February 2001 to February 2021, we have collected 152 randomized controlled trials of aPDT for peri-implantitis by searching the experimental studies and clinical trials published in PubMed, Embase, Web of Science, and Google Scholar databases via online search. After screening the retrieved literature, we finally selected 10 statistically significant literature for evaluation and review.

Results

Compared with the traditional nonsurgical treatment of peri-implantitis, the aPDT was superior to the traditional mechanical irrigation treatment group in terms of periodontal indexes PD, BOP, PLI, and postoperative effect, and the difference was statistically significant (P < 0.05). Furthermore, the combination of the aPDT and other treatments shows the synergistic antibacterial effect, signifying better clinical effect in many aspects (P < 0.05). In these 10 papers, by comparing the probe depth (PD), bleeding on probing (BOP), synosteosis, and periodontal pathogenic bacteria detection, etc., obtained after treating peri-implantitis by application of the antimicrobial photodynamic therapy, and using the SPSS data analysis software for statistical data processing, we found that the antimicrobial photodynamic therapy combined with other periodontal treatments has a more prominent postoperative effect. Meanwhile, the antibacterial photodynamic therapy with targeted action of photosensitizer has strong specificity to some bacteria, while the synthetic photosensitize for antibacterial photodynamic therapy can show good inactivation effect on broad-spectrum periodontal anaerobes without side effect.

Conclusion

The experimental studies and clinical data of antibacterial photodynamic therapy for treating peri-implantitis show a good postoperative treatment effect. In addition, it did not develop resistance due to the use of antibiotic drugs. Owing to multiple advantages from combining antibacterial photodynamic therapy and other treatments, it is applicable for clinical treatment.

Effect of diode laser as an adjunct to open flap debridement in treatment of periodontitis – A randomized clinical trial

Background:

The goals of periodontal therapy are to prevent the disease, arrest the disease progression, and regeneration of lost periodontium. Diode laser gained popularity in periodontal practice with a wide range of potential benefits.

Aim:

This study aims to evaluate and compare the clinical effects of laser-assisted open flap debridement (OFD) versus conventional OFD for the periodontitis treatment.

Materials and Methods:

A split-mouth, randomized clinical trial was conducted on fifteen participants with periodontitis having probing pocket depths (PPD) ≥5 mm. A total of 30 sites, two sites in each patient, were randomly divided into two groups. Group A received conventional OFD, and Group B received laser-assisted OFD. The assessment of PPD, relative attachment level (RAL), modified sulcular bleeding index (mSBI) was done at baseline, 3 months, and 6 months. Wound healing index (WHI) was assessed at 3^rd and 7^th day postsurgery, patient response to pain using visual analog scale (VAS) was assessed immediately, 1 day, and 1 week after surgery.

Results:

The results revealed a significant reduction in PPD, mSBI, and gain in RAL within the groups from baseline to 3 months and 6 months. Intergroup comparison showed a significant difference in PPD, RAL, mSBI, WHI and VAS scores.

Conclusions:

The use of 980 nm diode laser provided additional benefits over conventional flap therapy.

Comparison of Er,Cr:YSGG laser to minimally invasive surgical technique in the treatment of intrabony defects: Six-month results of a multicenter, randomized, controlled study

BACKGROUND

The purpose of this publication is to report on the six-month clinical results and patient-reported outcomes (PROs) comparing the surgical use of the erbium, chromium-doped: yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser (ERL) and minimally invasive surgical technique (MIST) for the treatment of intrabony defects in subjects with generalized periodontitis stage III, grade B.

METHODS

Fifty-three adults (29 females and 24 males; aged 19 to 73 years) with 79 intrabony defects were randomized following scaling and root planing (SRP) to receive ERL monotherapy (n = 27) or MIST (n = 26). Recession, probing depth (PD), clinical attachment level (CAL), treatment time, and PROs were assessed and compared for each treatment group. Clinical measurements were recorded at baseline, 4 to 6 weeks following SRP, and 6 months following surgical therapy.

RESULTS

The following primary and secondary outcome variables were non-inferior with the following margins: CAL with a non-inferiority margin of 0.6 mm (p = 0.05), PD with a non-inferiority margin of 0.5 mm (p = 0.05). Recession with a non-inferiority margin of 0.4 mm (p = 0.05). Faster procedure times were found for ERL (16.39 ± 6.21 minutes) versus MIST (20.17 ± 5.62 minutes), p = 0.0002. In the first 2 to 3 days of post-therapeutic diary outcomes, subjects reported less bruising, facial swelling, and use of ice pack for the ERL group.

CONCLUSIONS

This is the first multicenter, randomized, masked, and controlled study demonstrating the ERL is not inferior to MIST in terms of clinical outcomes but is superior in PROs for the surgical treatment of intrabony defects.

Minimally invasive periodontal therapy

Historically, surgical techniques were governed by specific incisions and surgical designs. With the advent of anesthesia, the complicated cases were managed but at the cost of the tissues leading to morbidities of various degrees. The innovations and the advances in the surgical techniques led to the ideology that surgeries could be done with minimal tissue manipulation and sacrifice. Thus the concept of "minimally invasive dentistry" was introduced with the primary goal to achieve satisfactory therapeutic results with minimal trauma during the process. In context to the management of periodontitis, this modality includes use of conservative incisions which preserves as much soft tissue as possible, avoiding continuous incisions and vertical incisions, use of magnification etc. The ultimate goal of any treatment modality is the resolution of the disease and regeneration if possible with minimal postoperative pain and morbidity. Minimal invasive periodontal therapy involves treatment options which cure the disease with reduced postoperative pain, improved healing and better patient acceptance. This paper covers the advent of minimal invasive periodontal therapy modalities both surgical and non-surgical along with the literature review.

Er:YAG Laser Irradiation Reduces Microbial Viability When Used in Combination with Irrigation with Sodium Hypochlorite, Chlorhexidine, and Hydrogen Peroxide

The erbium-doped yttrium aluminum garnet (Er:YAG) laser is used to treat periodontal disease; however, its effectiveness at killing oral bacteria is not well known. Furthermore, the compounding effect of the combination of a laser treatment and irrigation methods with antimicrobials on bacterial viability is yet to be determined. The purpose of this in vitro study was to evaluate the effect of the Er:YAG laser with irrigation using chlorhexidine (CHX), hydrogen peroxide (H₂O₂), or sodium hypochlorite (NaOCl) on the viability of oral bacteria. Three bacterial species were used in our study: Streptococcus gordonii, Fusobacterium nucleatum, and Porphyromonas gingivalis. Bacteria were grown in an anaerobic chamber in brain heart infusion broth and incubated at 37 °C. Bacterial samples with an OD of 0.5 were irradiated with the Er:YAG laser at 2940 nm using a 400-µm Varian tip. The experiment was repeated four times using these parameters: 40 mJ, 40 Hz, and 1.6 W for 20 seconds with the 300 µs short pulse duration in contact mode. Treatment groups consisted of the following: (1) no treatment, (2) 0.5% H₂O₂ alone, (3) 0.5% NaOCl alone, (4) 0.03% CHX alone, (5) Er:YAG irradiation alone, (6) Er:YAG irradiation with 0.5% H₂O₂, (7) Er:YAG irradiation with 0.5% NaOCl, and (8) Er:YAG irradiation with 0.03% CHX. Microbial viability was determined through plating and colony counts and calculated into CFU/ml. Statistical analysis was done using a two-tailed paired t-test. The use of the Er:YAG laser alone failed to show statistically significant antibacterial activity against any of bacteria. The most effective mono-treatment with irrigation solutions for all three bacteria were 0.5% H₂O₂ and 0.5% NaOCl (p < 0.001 for each solution). Irrigation with 0.03% CHX was most effective against F. nucleatum (p < 0.01) and less against P. gingivalis and S. gordonii and showed the least antibacterial action alone but improved significantly in combination therapy (p < 0.05). The combined treatment with the Er:YAG showed the greatest and most significant improvement in the reduction of bacterial viability compared to any other treatment group (p < 0.05 for each combined treatment). Irradiation with the Er:YAG laser with the addition of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX under a short working time (20 s) resulted in a significant reduction of bacterial viability for all three bacterial species compared with any single treatment option. The combination of irradiation with the Er:YAG laser with the addition of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX resulted in a larger reduction of bacterial survival when compared to monotherapies with antimicrobial solutions or laser. The combination of the Er:YAG laser with a low concentration irrigant solution of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX could be an effective treatment protocol for the reduction of periodontal pathogens and thus suitable treatment for non-surgical periodontal therapy.

Long-term assessment of periodontal disease progression after surgical or non-surgical treatment: a systematic review

The primary aim of this systematic review was to assess the evidence on periodontal disease progression after treatment in patients receiving supportive periodontal therapy (SPT) and to identify predictors of clinical attachment level (CAL) loss. A protocol was developed to answer the following focused question: In adult patients treated for periodontitis, what is the disease progression in terms of CAL loss after surgical or non-surgical treatment? Randomized controlled clinical trials, prospective cohort studies, and longitudinal observational human studies with a minimum of 5 years of follow-up after surgical or non-surgical treatment that reported CAL and probing depth changes were selected. Seventeen publications reporting data from 14 investigations were included. Data from 964 patients with a follow-up range of 5-15 years was evaluated. When the CAL at the latest follow-up was compared to the CAL after active periodontal therapy, 10 of the included studies reported an overall mean CAL loss of ≤0.5 mm, 3 studies reported a mean CAL loss of 0.5-1 mm, and 4 studies reported a mean CAL loss of >1 mm. Based on 7 publications, the percentage of sites showing a CAL loss of ≥2 mm varied from 3% to 20%, and a high percentage of sites with CAL loss was associated with poor oral hygiene, smoking, and poor compliance with SPT. The outcomes after periodontal therapy remained stable over time. Disease progression occurred in a reduced number of sites and patients, mostly associated with poor oral hygiene, poor compliance with SPT, and smoking.

Laser reduction of specific microorganisms in the periodontal pocket using Er:YAG and Nd:YAG lasers: a randomized controlled clinical study

The objective of this study was to evaluate the microbiological and clinical outcomes following nonsurgical treatment by either scaling and root planing, combination of Nd:YAG and Er:YAG lasers, or by Er:YAG laser treatment alone. The study involved 60 patients with generalized chronic periodontitis, randomly assigned into one of three treatment groups of 20 patients. The first group received scaling and root planing by hand instruments (SRP group), the second group received Er:YAG laser treatment alone (Er group), and the third group received combined treatment with Nd:YAG and Er:YAG lasers (NdErNd group). Microbiological samples, taken from the periodontal pockets at baseline and 6 months after treatments, were assessed with PET Plus tests. The combined NdErNd laser (93.0%), followed closely by Er:YAG laser (84.9%), treatment resulted in the highest reduction of all bacteria count after 6 months, whereas SRP (46.2%) failed to reduce Treponema denticola, Peptostreptococcus micros, and Capnocytophaga gingivalis. Full-mouth plaque and bleeding on probing scores dropped after 6 months and were the lowest in both laser groups. The combination of NdErNd resulted in higher probing pocket depth reduction and gain of clinical attachment level (1.99 ± 0.23 mm) compared to SRP (0.86 ± 0.13 mm) or Er:YAG laser alone (0.93 ± 0.20 mm) in 4-6 mm-deep pockets. Within their limits, the present results provide support for the combination of Nd:YAG and Er:YAG lasers to additionally improve the microbiological and clinical outcomes of nonsurgical periodontal therapy in patients with moderate to severe chronic periodontitis.

All done procedure by laser in free gingival graft treatment: A case series study

AIM

This case series study evaluated the application of Er;Cr:YSGG laser for a free gingival graft procedure and the effect of low level laser therapy on post surgical pain and wound healing.

CASES

6 cases with mucogingival problems needing free gingival grafts were selected. First, the recipient site was anesthetized and de-epithelialization was done with a Er;Cr:YSGG laser. After tracing the palatal donor site with the laser, the graft was harvested. For root modification of the recipient tooth, conditioning of the dentin was done by the same laser. The inner side of graft was trimmed by the laser before suturing at the recipient site. After final adaptation of the grafts and suturing process, the recipient and donor sites were irradiated by therapeutic laser for reduction of post surgical complications.

RESULTS

All patients reported the reduction in pain level after day 2 on donor and recipient site. Also, the wound healing was achieved after 14 days in all cases in donor site.

CONCLUSION

According to high surface absorbance, better incision, coagulation and application on both soft and hard tissues, Er;Cr:YSGG laser can be safe, minimally invasive manner and useful for all steps of the free gingival graft procedure.

Effect of Diode Laser-assisted Flap Surgery on Postoperative Healing and Clinical Parameters: A Randomized Controlled Clinical Trial

Background and Objectives:

Lasers have been widely used because of several potential benefits such as antibacterial effect and stimulation of wound healing. In addition, lasers help in hemostasis and delaying epithelial migration which may facilitate the outcome of flap surgery. Hence, this study is aimed to investigate the adjunctive effect of diode laser irradiation on conventional access flap surgery in the treatment of periodontal disease.

Materials and Methods:

A total of 23 patients requiring periodontal flap surgery in two sextants with probing pocket depth ≥5 mm in at least three teeth 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 conventional access flap surgery was done in the control quadrant. Procedural pain and tissue response of the patients were evaluated at 3, 7, and 14 days postoperatively. Clinical parameters including probing depth, clinical attachment level, plaque index, and gingival index were recorded at baseline, 3 months, and 6 months following treatment.

Results:

There is no significant difference between the groups with respect to healing response of tissues; however, patients experienced more pain in test sites compared to control sites. Intragroup comparisons showed a statistically significant reduction of all clinical parameters from baseline to 6 months without any significant difference between the groups.

Conclusion:

Overall within the limitations of the study, diode lasers did not show any significant added benefits over conventional access flap surgery.

Stimulation of human gingival fibroblasts viability and growth by roots treated with high intensity lasers, photodynamic therapy and citric acid

OBJECTIVE

The aim of this study was to compare the effect of root biomodification by lasers, citric acid and antimicrobial photodynamic therapy (aPDT) on viability and proliferation of human gingival fibroblasts (FGH).

DESIGN

Groups were divided in control (CC - only cells), and root fragments treated by: scaling and root planing (positice control - SC), Er:YAG (ER-60mJ,10pps,10Hz,10s,2940nm), Nd:YAG (ND-0.5W,15Hz,10s,1640nm), antimicrobial photodynamic therapy (PDT-InGaAIP,30mW,45J/cm²,30s,660nm,toluidine blue O), citric acid plus tetracycline (CA). Fibroblasts (6th passage, 2×10³) were cultivated in a 24-h conditioned medium by the treated root fragments. Cell viability was measured by MTT test at 24, 48, 72 and 96h. In a second experiment, FGH cells (10⁴) were cultivated on root fragments which received the same treatments. After 24, 48, 72h the number of cells was counted in SEM pictures. In addition, chemical elements were analyzed by energy dispersive spectroscopy (EDS). Data was analyzed by two-way ANOVA (first experiment), repeated measures ANOVA (second experiment) and ANOVA (EDS experiment) tests complemented by Tukey's test (p<0.05).

RESULTS

ND, PDT and CA promoted higher cell viability (p<0.05). ND and ER groups presented higher number of cells on root surfaces (p<0.05). ER group presented higher calcium and CA group a higher carbon percentages (p<0.05).

CONCLUSIONS

All treatments but scaling and root planing stimulated fibroblast viability while Er:YAG and Nd:YAG treated root surfaces presented higher number of cells.

Periodontal and peri-implant wound healing following laser therapy

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri-implant treatment, focusing on postoperative wound healing of periodontal and peri-implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports.

Laser assisted periodontics: A review of the literature

Over the years, the use of the laser within health field and more particularly dentistry has been increasing and improving. The application of laser in the periodontal treatment takes part of a non-surgical and surgical approaches, is used for the decontamination of periodontal pockets due to its bactericidal effect, and the removal of granulation tissues, inflamed and diseased epithelium lining, bacterial deposits and subgingival calculus. However in spite of all the marketing surrounding, the use of laser highlighting its beneficial effect, the capacity of laser to replace the conventional treatment for chronic periodontitis is still debatable. In fact there is no evidence that any laser system adds substantial clinical value above conventional treatments of chronic periodontitis. Some studies showed a significant positive effect on clinical attachment level gain and probing depth reduction. In the other hand, several articles demonstrated no evidence of the superior effectiveness of laser therapy compared to root planing and scaling. Our aims is to review the literature on the capacity of erbium:Yttrium-aluminum-garnet and neodymium:Yttrium-aluminium-garnet laser to either replace or complete conventional mechanical/surgical periodontal treatments.

Gingival tissue healing following Er:YAG laser ablation compared to electrosurgery in rats

The erbium-doped yttrium aluminum garnet (Er:YAG) laser is currently used for periodontal soft tissue management with favorable outcomes. However, the process of wound healing after Er:YAG laser (ErL) treatment has not been fully elucidated yet. The aim of this study was to investigate the gingival tissue healing after ErL ablation in comparison with that after electrosurgery (ElS). Gingival defects were created in 28 rats by ablation with ErL irradiation or ElS. The chronological changes in wound healing were evaluated using histological, histometrical, and immunohistochemical analyses. The ErL-ablated gingival tissue revealed much less thermal damage, compared to the ElS. In the ElS sites, the postoperative tissue destruction continued due to thermal damage, while in the ErL sites, tissue degradation was limited and the defects were re-epithelialized early. Heat shock protein (Hsp) 72/73 expression was detected abundantly remote from the wound in the ElS, whereas it was slightly observed in close proximity to the wound in the ErL sites. Hsp47 expression was observed in the entire connective tissue early in the wound healing and was found limited in the wound area later. This phenomenon proceeded faster in the ErL sites than in the ElS sites. Expression of proliferating cell nuclear antigen (PCNA) persisted in the epithelial tissue for a longer period in the ElS than that in the ErL. The ErL results in faster and more favorable gingival wound healing compared to the ElS, suggesting that the ErL is a safe and suitable tool for periodontal soft tissue management.

Histological and SEM analysis of root cementum following irradiation with Er:YAG and CO2 lasers

Recently, the Er:YAG and CO(2) lasers have been applied in periodontal therapy. However, the characteristics of laser-irradiated root cementum have not been fully analyzed. The aim of this study was to precisely analyze the alterations of root cementum treated with the Er:YAG and the CO(2) lasers, using non-decalcified thin histological sections. Eleven cementum plates were prepared from extracted human teeth. Pulsed Er:YAG laser contact irradiation was performed in a line at 40 mJ/pulse (14.2 J/cm(2)/pulse) and 25 Hz (1.0 W) under water spray. Continuous CO(2) laser irradiation was performed in non-contact mode at 1.0 W, and ultrasonic instrumentation was performed as a control. The treated samples were subjected to stereomicroscopy, scanning electron microscopy (SEM), light microscopy and SEM energy dispersive X-ray spectroscopy (SEM-EDS). The Er:YAG laser-treated cementum showed minimal alteration with a whitish, slightly ablated surface, whereas CO(2) laser treatment resulted in distinct carbonization. SEM analysis revealed characteristic micro-irregularities of the Er:YAG-lased surface and the melted, resolidified appearance surrounded by major and microcracks of the CO(2)-lased surface. Histological analysis revealed minimal thermal alteration and structural degradation of the Er:YAG laser-irradiated cementum with an affected layer of approximately 20-μm thickness, which partially consisted of two distinct affected layers. The CO(2)-lased cementum revealed multiple affected layers showing different structures/staining with approximately 140 μm thickness. Er:YAG laser irradiation used with water cooling resulted in minimal cementum ablation and thermal changes with a characteristic microstructure of the superficial layer. In contrast, CO(2) laser irradiation produced severely affected distinct multiple layers accompanied by melting and carbonization.

Low loss silica hollow core fibers for 3-4 μm spectral region

We describe a silica hollow-core fiber for mid-infrared transmission with a minimum attenuation of 34 dB/km at 3050 nm wavelength. The design is based on the use of a negative curvature core wall. Similar fiber designed for longer wavelengths has a transmission band extending beyond 4 µm.

In vitro adhesion of Streptococcus sanguinis to dentine root surface after treatment with Er:YAG laser, ultrasonic system, or manual curette

OBJECTIVE

The purpose of this in vitro study was to evaluate the dentine root surface roughness and the adherence of Streptococcus sanguinis (ATCC 10556) after treatment with an ultrasonic system, Er:YAG laser, or manual curette.

BACKGROUND DATA

Bacterial adhesion and formation of dental biofilm after scaling and root planing may be a challenge to the long-term stability of periodontal therapy.

MATERIALS AND METHODS

Forty flattened bovine roots were randomly assigned to one of the following groups: ultrasonic system (n = 10); Er:YAG laser (n = 10); manual curette (n = 10); or control untreated roots (n = 10). The mean surface roughness (Ra, microm) of the specimens before and after exposure to each treatment was determined using a surface profilometer. In addition, S. sanguinis was grown on the treated and untreated specimens and the amounts of retained bacteria on the surfaces were measured by culture method.

RESULTS

All treatments increased the Ra; however, the roughest surface was produced by the curettes. In addition, the specimens treated with curettes showed the highest S. sanguinis adhesion. There was a significant positive correlation between roughness values and bacterial cells counts.

CONCLUSION

S. sanguinis adhesion was the highest on the curette-treated dentine root surfaces, which also presented the greatest surface roughness.

Lasers and the treatment of chronic periodontitis

For many intraoral soft-tissue surgical procedures the laser has become a desirable and dependable alternative to traditional scalpel surgery. However, the use of dental lasers in periodontal therapy is controversial. This article presents the current peer-reviewed evidence on the use of dental lasers for the treatment of chronic periodontitis.

Long-term histologic analysis of bone tissue alteration and healing following Er:YAG laser irradiation compared to electrosurgery

BACKGROUND

The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is reportedly useful for periodontal therapy. However, the potential thermal damage that Er:YAG laser irradiation can produce on bone tissue has not been fully clarified. The purpose of this study was to histologically examine the effects of the Er:YAG laser on bone tissue and subsequent wound healing compared to electrosurgery in a long-term study.

METHODS

Calvarial bone from 30 rats was exposed to contact and non-contact Er:YAG laser irradiation (115 mJ/pulse, 10 Hz) without water coolant, or electrode contact. The treated surfaces were analyzed by scanning electron microscopy (SEM), and the healing process was histologically observed until 12 months post-surgery.

RESULTS

Contact irradiation resulted in substantial bone ablation, whereas non-contact irradiation produced slight tissue removal. Histologic and SEM analyses of the lased surface showed no severe thermal damage, except for the production of a superficially affected layer with a microstructured surface. The layer did not inhibit new bone formation, and the ablated defect was repaired uneventfully. Although the thickness of the layer gradually decreased, it generally remained in the cortical bone through the observation period. Electrosurgery produced a large area of thermal necrosis without ablation, and the damaged area was not replaced with new bone.

CONCLUSIONS

Unlike electrosurgery, Er:YAG laser irradiation without water coolant easily ablated bone tissue, and thermal alteration in the treated surface was minimal. The superficially affected layer did not interfere with the ensuing bone healing, resulting in favorable repair of the defect.