Use of the Er:YAG laser for improved plating in maxillofacial surgery: comparison of bone healing in laser and drill osteotomies

Laser biomodification of the bone bed surface for placement of spiral dental implants: a study based on scanning electron microscopy

INTRODUCTION

Various rotary and mechanical instruments are used in conventional oral surgery for osteotomies. Despite the implementation of effective cooling systems, it is difficult to prevent thermal damage to the adjacent bone caused by heat generated during the procedure. A smear layer forms on the surface, which can impede the interaction of blood elements with the underlying tissue, resulting in a delayed healing process.

Effect of Er:YAG Laser Exposure on the Amorphous Smear Layer in the Marginal Zone of the Osteotomy Site for Placement of Dental Screw Implants: A Histomorphological Study

The placement of dental screw implants typically involves the use of rotary techniques and drills to create a bone bed. This study explores the potential benefits of combining this method with an Er:YAG laser. Split osteotomies were performed on 10 jaws of euthanized domestic pigs (Sus scrofa domestica), with 12 mandibular implant osteotomies in each jaw, divided into 4 groups. In order to make a comprehensive assessment of the effect of Er:YAG lasers, histomorphological techniques were used to measure the reduction in amorphous layer thickness after Er:YAG laser treatment, both with and without the placement of dental screw implants from different manufacturers. Following bone decalcification and staining, the thickness of the amorphous layer was measured in four groups: Group A-osteotomy performed without Er:YAG laser treatment-had amorphous layer thicknesses ranging from 21.813 to 222.13 µm; Group B-osteotomy performed with Er:YAG laser treatment-had amorphous layer thicknesses ranging from 6.08 to 64.64 µm; Group C-an implant placed in the bone without laser treatment-had amorphous layer thicknesses of 5.90 to 54.52 µm; and Group D-an implant placed after bone treatment with Er:YAG laser-had amorphous layer thicknesses of 1.29 to 7.98 µm. The examination and photomicrodocumentation was performed using a LEICA DM1000 LED microscope (Germany) and LAS V 4.8 software (Leica Application Suite V4, Leica Microsystems, Germany). When comparing group A to group B and group C to D, statistically significant differences were indicated (p-value = 0.000, p < 0.05). The study demonstrates the synergistic effects and the possibility of integrating lasers into the conventional implantation protocol. By applying our own method of biomodification, the smear layer formed during rotary osteotomy can be reduced using Er:YAG lasers. This reduction leads to a narrower peri-implant space and improved bone-to-implant contact, facilitating accelerated osseointegration.

Real-time closed-loop tissue-specific laser osteotomy using deep-learning-assisted optical coherence tomography

This article presents a real-time noninvasive method for detecting bone and bone marrow in laser osteotomy. This is the first optical coherence tomography (OCT) implementation as an online feedback system for laser osteotomy. A deep-learning model has been trained to identify tissue types during laser ablation with a test accuracy of 96.28 %. For the hole ablation experiments, the average maximum depth of perforation and volume loss was 0.216 mm and 0.077 mm³, respectively. The contactless nature of OCT with the reported performance shows that it is becoming more feasible to utilize it as a real-time feedback system for laser osteotomy.

First-Hand Experience and Result with New Robot-Assisted Laser LeFort-I Osteotomy in Orthognathic Surgery: A Case Report

BACKGROUND

We report the world's first developer-independent experience with robot-assisted laser Le Fort I osteotomy (LLFO) and drill-hole marking in orthognathic surgery. To overcome the geometric limitations of conventional rotating and piezosurgical instruments for performing osteotomies, we used the stand-alone robot-assisted laser system developed by Advanced Osteotomy Tools. The aim here was to evaluate the precision of this novel procedure in comparison to the standard procedure used in our clinic using a computer-aided design/computer-aided manufacturing (CAD/CAM) cutting guide and patient-specific implant.

METHODS

A linear Le-Fort-I osteotomy was digitally planned and transferred to the robot. The linear portion of the Le-Fort I osteotomy was performed autonomously by the robot under direct visual control. Accuracy was analyzed by superimposing preoperative and postoperative computed tomography images, and verified intraoperatively using prefabricated patient-specific implant.

RESULTS

The robot performed the linear osteotomy without any technical or safety issues. There was a maximum difference of 1.5 mm on average between the planned and the performed osteotomy. In the robot-assisted intraoperative drillhole marking of the maxilla, which was performed for the first time worldwide, were no measurable deviations between planning and actual positioning.

CONCLUSION

Robotic-assisted orthognathic surgery could be a useful adjunct to conventional drills, burrs, and piezosurgical instruments for performing osteotomies. However, the time required for the actual osteotomy as well as isolated minor design aspects of the Dynamic Reference Frame (DRF), among other things, still need to be improved. Still further studies for final evaluation of safety and accuracy are also needed.

Laser-Assisted Gingivectomy to Treat Gummy Smile

Excessive gingival display (EGD) is the extensive exposure of the gingiva during a smile. It is a common concern among patients, which may compromise the esthetic outcome of the dental treatment. Dental lasers demonstrate several advantages for soft tissue dental surgery compared with conventional surgical methods related to their technical characteristics. Owing to the excellent coagulation, especially of the surgical lasers, reduced to no need of anesthesia or suturing and faster healing, they demonstrate optimal clinical results. Nevertheless, good knowledge of laser-tissue interaction is required to obtain the best predictable results without gingival recession or bone tissue damage.

Evaluation of the efficacy of laser-assisted flapless corticotomy in accelerating canine retraction: a split-mouth randomized controlled clinical trial

OBJECTIVE

To evaluate the efficacy of laser-assisted flapless corticotomy in the acceleration of canine retraction compared with the conventional technique and to evaluate patients' pain and discomfort levels after corticotomy.

MATERIALS AND METHODS

A single-center randomized controlled trial was conducted on 18 class II division 1 patients (7 males, 11 females; age range: 16 to 24 years) who required the first-upper-premolar extraction followed by canine retraction. A split-mouth design was used in which the Er:YAG laser-assisted flapless corticotomy was randomly allocated to one side, whereas the other side served as the control side. The primary outcome measure was the canine retraction rate which was assessed immediately after laser application, 1, 2, 4, 8, and 12 weeks after laser application. Also, the levels of pain and discomfort during the first week following laser application were assessed. Paired t-tests or Wilcoxon matched-pairs signed-rank tests were used to detect significant differences.

RESULTS

All of the selected eighteen patients entered the statistical analysis stage. Significant differences were observed (P < 0.001) in canine retraction rates between the experimental and control sides at the baseline to 1st-week, 1st- to 2nd-week, 2nd- to 4th-week, and 4th- to 8th-week intervals. No significant difference was found between the two sides at the 8th- to 12th-week interval. A significant reduction was seen in the mean score of pain during eating at all assessment times when compared to the baseline data (P = 0.002 at day 2, P < 0.001 at days 5 and 7).

CONCLUSION

Er:YAG laser-assisted flapless corticotomy appears to be an effective treatment method for accelerating canine retraction and was accompanied by a mild degree of pain and discomfort.

TRIAL REGISTRATION

ClinicalTrials.gov (No.: NCT04316403), retrospectively registered on the 20th of March 2020. URL: https://clinicaltrials.gov/ct2/show/NCT04316403.

Cold Ablation Robot-Guided Laser Osteotome (CARLO®): From Bench to Bedside

Background: In order to overcome the geometrical and physical limitations of conventional rotating and piezosurgery instruments used to perform bone osteotomies, as well as the difficulties in translating digital planning to the operating room, a stand-alone robot-guided laser system has been developed by Advanced Osteotomy Tools, a Swiss start-up company. We present our experiences of the first-in-man use of the Cold Ablation Robot-guided Laser Osteotome (CARLO^®). Methods: The CARLO^® device employs a stand-alone 2.94-µm erbium-doped yttrium aluminum garnet (Er:YAG) laser mounted on a robotic arm. A 19-year-old patient provided informed consent to undergo bimaxillary orthognathic surgery. A linear Le Fort I midface osteotomy was digitally planned and transferred to the CARLO^® device. The linear part of the Le Fort I osteotomy was performed autonomously by the CARLO^® device under direct visual control. All pre-, intra-, and postoperative technical difficulties and safety issues were documented. Accuracy was analyzed by superimposing pre- and postoperative computed tomography images. Results: The CARLO^® device performed the linear osteotomy without any technical or safety issues. There was a maximum difference of 0.8 mm between the planned and performed osteotomies, with a root-mean-square error of 1.0 mm. The patient showed normal postoperative healing with no complications. Conclusion: The newly developed stand-alone CARLO^® device could be a useful alternative to conventional burs, drills, and piezosurgery instruments for performing osteotomies. However, the technical workflow concerning the positioning and fixation of the target marker and the implementation of active depth control still need to be improved. Further research to assess safety and accuracy is also necessary, especially at osteotomy sites where direct visual control is not possible. Finally, cost-effectiveness analysis comparing the use of the CARLO^® device with gold-standard surgery protocols will help to define the role of the CARLO^® device in the surgical landscape.

A Comparative Analysis Regarding the Osseointegration of Immediate Loaded Implants Using Two Different Implant Site Preparations: Erbium:Yttrium-Aluminum-Garnet Laser Versus Surgical Conventional Way-An In Vivo and Histological Animal Study

Objective: The aim of the study is to evaluate the possibility of preparing the implant site using the erbium:yttrium-aluminum-garnet (Er:YAG) laser scanner prototype and to reduce and/or eliminate time between primary (mechanical) stability and secondary (biological) stability, looking to the immediate occlusal loading in a single implant. Background: A prerequisite for successful osseointegration is the establishment of direct bone-to-implant contact without interposition of nonbone or connective tissue. In recent years, the use of laser radiation was presented as an alternative/adjunctive treatment for bone tissue ablation due to vaporization of the tissues in the absence of a smear layer. Methods: The experimental protocol included six minipigs, which underwent tooth extraction, followed (after 2 months) by implant bed preparation in two methods: using a conventional bur kit and using an Er:YAG laser scanner (X runner) protocol. Four implants were placed in positions 34, 37, 44, and 47 on each animal. The animals underwent the second surgical procedure for bone sample collection (including the implant) before their sacrifice at 45-60-90-120 days. The newly formed bone was evaluated on the bone samples using histological examination and quantitative evaluations of different histological parameters based on microscopical analysis. Results: The results that we obtained allow some interesting comparison in terms of different bone composition, depending on the method of implant site preparation and on healing periods. Moreover, it was possible to compare the bone composition, at different time stages, of implant sites prepared in the same way. Conclusions: Our research allowed us to demonstrate that the use of Er:YAG laser compared with traditional drill leads to the presence of a greater share of lamellar bone and a lower necrotic share in the implant site. We also showed the possibility of applying immediate occlusal loading on an in vivo animal model.

In vitro evaluation of ultrafast laser drilling large-size holes on sheepshank bone

Bone drilling has been widely used in medical surgeries such as repair and fixation in orthopedics. Traditional drilling method using drill-bits inevitably causes significant thermal and mechanical trauma in the adjacent bone tissues. This paper demonstrates the feasibility of femtosecond laser drilling in vitro large-size holes on the sheepshank bone with high efficiency and minimal collateral damage. A Yb:KGW femtosecond laser was utilized to drill millimeter-scale holes on the bone under different cooling conditions including gas- and water-assisted processes. Scanning electron microscopy, confocal laser scanning microscopy and infrared thermographic imaging system were used to investigate the residual debris, removal rate, bone temperature variation and hole morphology. Histological examination, Fourier transform infrared spectroscopy and Raman spectroscopy were employed to study thermal damage. Results show that a 4 mm hole with smooth and clean surface was successfully drilled on the bone, and the highest removal rate of 0.99 mm³/s was achieved, which was twenty times higher than the previous study of 0.05 mm³/s. Moreover, bone and bone marrow were distinguished by real-time monitoring system during laser drilling. This work demonstrates the potential for clinical applications using an ultrafast laser to produce crack-free large-size bone holes.

Machine Learning-Based Optoacoustic Tissue Classification Method for Laser Osteotomes Using an Air-Coupled Transducer

BACKGROUND AND OBJECTIVES

Using lasers instead of mechanical tools for bone cutting holds many advantages, including functional cuts, contactless interaction, and faster wound healing. To fully exploit the benefits of lasers over conventional mechanical tools, a real-time feedback to classify tissue is proposed.

STUDY DESIGN/MATERIALS AND METHODS

In this paper, we simultaneously classified five tissue types-hard and soft bone, muscle, fat, and skin from five proximal and distal fresh porcine femurs-based on the laser-induced acoustic shock waves (ASWs) generated. For laser ablation, a nanosecond frequency-doubled Nd:YAG laser source at 532 nm and a microsecond Er:YAG laser source at 2940 nm were used to create 10 craters on the surface of each proximal and distal femur. Depending on the application, the Nd:YAG or Er:YAG can be used for bone cutting. For ASW recording, an air-coupled transducer was placed 5 cm away from the ablated spot. For tissue classification, we analyzed the measured acoustics by looking at the amplitude-frequency band of 0.11-0.27 and 0.27-0.53 MHz, which provided the least average classification error for Er:YAG and Nd:YAG, respectively. For data reduction, we used the amplitude-frequency band as an input of the principal component analysis (PCA). On the basis of PCA scores, we compared the performance of the artificial neural network (ANN), the quadratic- and Gaussian-support vector machine (SVM) to classify tissue types. A set of 14,400 data points, measured from 10 craters in four proximal and distal femurs, was used as training data, while a set of 3,600 data points from 10 craters in the remaining proximal and distal femur was considered as testing data, for each laser.

RESULTS

The ANN performed best for both lasers, with an average classification error for all tissues of 5.01 ± 5.06% and 9.12 ± 3.39%, using the Nd:YAG and Er:YAG lasers, respectively. Then, the Gaussian-SVM performed better than the quadratic SVM during the cutting with both lasers. The Gaussian-SVM yielded average classification errors of 15.17 ± 13.12% and 16.85 ± 7.59%, using the Nd:YAG and Er:YAG lasers, respectively. The worst performance was achieved with the quadratic-SVM with a classification error of 50.34 ± 35.04% and 69.96 ± 25.49%, using the Nd:YAG and Er:YAG lasers.

CONCLUSION

We foresee using the ANN to differentiate tissues in real-time during laser osteotomy. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Laser surgery in management of medication-related osteonecrosis of the jaws: a meta-analysis

PURPOSE

The aim of this study was to perform a systematic review and meta-analysis to evaluate the efficacy of laser therapy on medication-related osteonecrosis of the jaw (MRONJ) treatment.

METHODS

This study followed PRISMA standards, and an electronic search was performed on the PubMed/MEDLINE, Scopus, and Cochrane databases. Eighty-nine articles were found. After reading the manuscripts, 15 articles remained for the review. Three of them were selected for meta-analysis.

RESULTS

Female gender was predominant (72.5%), and mean age was 66.5 years. Follow-up varied between 3 and 80 months, and the most used bisphosphonate was zoledronic acid (71.6%). Stage II of MRONJ was the most prevalent (68.9%), and the mandible was the most affected site (64.5%). Qualitative data showed that treatment with laser surgery (Er:YAG) was most effective regarding complete healing of the lesion (90%) compared with other treatments. Meta-analysis data showed that low-level laser therapy (LLLT) was more effective than medical treatment (P = 0.006), and surgical treatment was more effective than LLLT (P = 0.008).

CONCLUSION

Laser surgery was significantly superior to LLLT (p < 0.00001). Therefore, laser surgical therapy seems to be a great management strategy for MRONJ treatment from stage II. LLLT was shown to improve conservative management in earlier MRONJ stages.

Evaluation of bone healing following Er:YAG laser ablation in rat calvaria compared with bur drilling

The Er:YAG laser is currently used for bone ablation. However, the effect of Er:YAG laser irradiation on bone healing remains unclear. The aim of this study was to investigate bone healing following ablation by laser irradiation as compared with bur drilling. Rat calvarial bone was ablated using Er:YAG laser or bur with water coolant. Er:YAG laser effectively ablated bone without major thermal changes. In vivo micro-computed tomography analysis revealed that laser irradiation showed significantly higher bone repair ratios than bur drilling. Scanning electron microscope analysis showed more fibrin deposition on laser-ablated bone surfaces. Microarray analysis followed by gene set enrichment analysis revealed that IL6/JAK/STAT3 signaling and inflammatory response gene sets were enriched in bur-drilled bone at 6 hours, whereas the E2F targets gene set was enriched in laser-irradiated bone. Additionally, Hspa1a and Dmp1 expressions were increased and Sost expression was decreased in laser-irradiated bone compared with bur-drilled bone. In granulation tissue formed after laser ablation, Alpl and Gblap expressions increased compared to bur-drilled site. Immunohistochemistry showed that osteocalcin-positive area was increased in the laser-ablated site. These results suggest that Er:YAG laser might accelerate early new bone formation with advantageous surface changes and cellular responses for wound healing, compared with bur-drilling.

Differential Proteome Analysis of Human Neuroblastoma Xenograft Primary Tumors and Matched Spontaneous Distant Metastases

Metastasis formation is the major cause for cancer-related deaths and the underlying mechanisms remain poorly understood. In this study we describe spontaneous metastasis xenograft mouse models of human neuroblastoma used for unbiased identification of metastasis-related proteins by applying an infrared laser (IR) for sampling primary tumor and metastatic tissues, followed by mass spectrometric proteome analysis. IR aerosol samples were obtained from ovarian and liver metastases, which were indicated by bioluminescence imaging (BLI), and matched subcutaneous primary tumors. Corresponding histology proved the human origin of metastatic lesions. Ovarian metastases were commonly larger than liver metastases indicating differential outgrowth capacities. Among ~1,900 proteins identified at each of the three sites, 55 proteins were differentially regulated in ovarian metastases while 312 proteins were regulated in liver metastases. There was an overlap of 21 and 7 proteins up- and down-regulated at both metastatic sites, respectively, most of which were so far not related to metastasis such as LYPLA2, EIF4B, DPY30, LGALS7, PRPH, and NEFM. Moreover, we established in vitro sublines from primary tumor and metastases and demonstrate differences in cellular protrusions, migratory/invasive potential and glycosylation. Summarized, this work identified several novel putative drivers of metastasis formation that are tempting candidates for future functional studies.

[Methods of removing failed implants]

Implant restoration has become one of the most regular methods of restoring dentition defect or edentulous. Implant placement and osseointegration are partly unreserved (fracture, implant is not in the correct three-dimensional position and cannot be repaired, peri-implantitis-affected nonmobile implants) need to be removed. This article reviews the different methods of removing implants and discusses the limitations of each method, as well as the complications that may occur during the procedure.

Laser Technology in Orthopedics: Preliminary Study on Low Power Laser Therapy to Improve the Bone-Biomaterial Interface

Low Power Laser (LPL) seems to enhance the healing of bone defects and fractures. The effect of LPL In other orthopedic areas such as osteointegration of implanted prosthetic bone devices is still unclear. In the present study, 12 rabbits were used to evaluate whether Ga-AI-As (780 nm) LPL stimulation has positive effects on osteointegration. Hydroxyapatite (HA) cylindrical nails were drilled into both distal femurs of rabbits. From postoperative day 1 and for 5 consecutive days, the left femura of all rabbits were given LPL treatment (Laser Group-LG) with the following parameters: 300 Joule/cm2 1 Watt, 300 Hertz, pulsating emission, 10 minutes. The right femura were sham-treated (Control Group-CG). At 4 and 8 weeks after implantation, histologic and histomorphometric investigations evaluated bone-biomaterial-contact. Histomorphometry showed a higher degree of osteointegration at the HA-bone interface in the LG Group at 4 (p<0.0005) and 8 weeks (p<0.001). These preliminary positive results seem to support the hypothesis that LPL treatment can be considered a good tool to enhance the bone-implant interface in orthopedic surgery.

Laser-Assisted Osteotomy for Implant Site Preparation: A Literature Review

PURPOSE

The aim of this study was to review the scientific evidence about the laser osteotomy in implant bed preparation.

METHODS

An electronic search was performed on relevant English articles up to April 2016 in the PubMed, Scopus, and Google Scholar databases.

RESULTS

Twenty-two articles (1 clinical, 13 animal, and 8 ex vivo studies) were included. Implant sites prepared by erbium family lasers and drill showed comparable results regarding the percentage of bone-to-implant contact, values of biomechanical tests, and healing process. Selection of proper laser wavelength and parameters was of paramount importance to minimize the risk of thermal bone damage. Lack of depth control and long time needed for implant site osteotomy with laser were the most challenging concerns for its clinical applicability. Computer-guided laser osteotomy showed promise for future use of laser osteotomy in clinical settings.

CONCLUSION

Evidence from animal studies shows promising results regarding laser osteotomy in implant site preparation. However, because of the lack of clinical studies, it is not possible to make a conclusive result whether there is superiority of laser osteotomy in clinical practice.

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.

Assessment of Temperature Rise and Time of Alveolar Ridge Splitting by Means of Er:YAG Laser, Piezosurgery, and Surgical Saw: An Ex Vivo Study

The most common adverse effect after bone cutting is a thermal damage. The aim of our study was to evaluate the bone temperature rise during an alveolar ridge splitting, rating the time needed to perform this procedure and the time to raise the temperature of a bone by 10°C, as well as to evaluate the bone carbonization occurrence. The research included 60 mandibles (n = 60) of adult pigs, divided into 4 groups (n = 15). Two vertical and one horizontal cut have been done in an alveolar ridge using Er:YAG laser with set power of 200 mJ (G1), 400 mJ (G2), piezosurgery unit (G3), and a saw (G4). The temperature was measured by K-type thermocouple. The highest temperature gradient was noted for piezosurgery on the buccal and lingual side of mandible. The temperature rises on the bone surface along with the increase of laser power. The lower time needed to perform ridge splitting was measured for a saw, piezosurgery, and Er:YAG laser with power of 400 mJ and 200 mJ, respectively. The temperature rise measured on the bone over 10°C and bone carbonization occurrence was not reported in all study groups. Piezosurgery, Er:YAG laser (200 mJ and 400 mJ), and surgical saw are useful and safe tools in ridge splitting surgery.

The use of lasers for direct pulp capping

Direct pulp capping helps extend the life of a diseased tooth by maintaining tooth vitality. Nowadays, lasers are more frequently used during direct pulp capping in the clinic, but their use has not been previously reviewed. This review presents the basic properties of currently available lasers, scientific evidence on the effects of laser application on direct pulp capping, and future directions for this technology. An extensive literature search was conducted in various databases for articles published up to January 2015. Original in vitro, in vivo, and clinical studies, reviews, and book chapters published in English were included. Various laser systems have been increasingly and successfully applied in direct pulp capping. Lasers offer excellent characteristics in terms of hemostasis and decontamination for field preparation during direct pulp capping treatment; however, the sealing of exposed pulp with one of the dental materials, such as calcium hydroxide, mineral trioxide aggregates, and bonded composite resins, is still required after laser treatment. Clinicians should consider the characteristics of each wavelength, the emission mode, irradiation exposure time, power, type of laser tip, and the distance between the laser tip and the surface being irradiated.

Comparison of four different techniques for performing an osteotomy: a biomechanical, radiological and histological study on rabbits tibias

This animal study compares different methods of performing an osteotomy, including using an Erbium-doped Yttrium Aluminum Garnet laser, histologically, radiologically and biomechanically. A total of 24 New Zealand rabbits were divided into four groups (Group I: multihole-drilling; Group II: Gigli saw; Group III: electrical saw blade and Group IV: laser). A proximal transverse diaphyseal osteotomy was performed on the right tibias of the rabbits after the application of a circular external fixator. The rabbits were killed six weeks after the procedure, the operated tibias were resected and radiographs taken. The specimens were tested biomechanically using three-point bending forces, and four tibias from each group were examined histologically. Outcome parameters were the biomechanical stability of the tibias as assessed by the failure to load and radiographic and histological examination of the osteotomy site. The osteotomies healed in all specimens both radiographically and histologically. The differences in the mean radiographic (p = 0.568) and histological (p = 0.71) scores, and in the mean failure loads (p = 0.180) were not statistically significant between the groups. Different methods of performing an osteotomy give similar quality of union. The laser osteotomy, which is not widely used in orthopaedics is an alternative to the current methods.

Esthetic Correction of Orthodontically Transposed Teeth with Veneers and Laser Periodontal Modification

Missing teeth in the esthetic zone, whether congenital or as a result of other factors, present difficult choices in clinical management. The missing teeth can be replaced by surgical or restorative intervention but are often treated orthodontically. These repositioned teeth often lead to an unaesthetic result because of differences in morphology, color, and particularly in gingival architecture. This article describes the use of multiple lasers for periodontal modification and feldspathic porcelain veneers to achieve a highly esthetic result.

A report on the use of Er:YAG laser for pilot hole drilling prior to miniscrew insertion

The aim of the present in vitro study was to investigate the required time period of the Er:YAG laser that is used for drilling through cortical bone when pilot hole drilling is needed before miniscrew insertion. Even though Er:YAG laser is used in various in vivo and in vitro studies, there is no accepted procedure of laser for depth control during drilling through cortical bone. The study sample consisted of 120 cortical bone segments having 1.5 and 2.0 mm of cortical bone thickness. An Er:YAG laser, with a spot size of 1.3 mm and an air-water spray of 40-50 ml/min, was used. The laser was held 2 mm away from and perpendicular to the bone surface with different laser settings. Twelve specimens were prepared for each subgroup. As the cortical bone thickness increased, the time needed to drill through the bone increased. Frequency increase directly caused a decrease in irradiation duration. When three different frequency, three different energy, and four different power values were tested for both the 1.5- and 2-mm cortical bone thicknesses, the shortest duration needed to drill through cortical bone was seen in the 3.6-W (300 mJ-12 Hz) setting. When pilot holes are drilled prior to miniscrew placement in 1.5 to 2 mm of cortical bone using Er:YAG laser, the most appropriate value is found with the 3.6-W (300 mJ-12 Hz) setting.

Laser vs bur for bone cutting in impacted mandibular third molar surgery: A randomized controlled trial

BACKGROUND

The aim of this study was to assess the feasibility of Er: YAG laser in bone cutting for removal of impacted lower third molar teeth and compare its outcomes with that of surgical bur.

MATERIALS & METHODS

The study comprised 40 subjects requiring removal of impacted mandibular third molar, randomly categorized into two equal groups of 20 each, who had their impacted third molar removed either using Er: YAG laser or surgical bur as per their group, using standard methodology of extraction of impacted teeth. Clinical parameters like pain, bleeding, time taken for bone cutting, postoperative swelling, trismus, wound healing and complications were compared for both groups.

OBSERVATION & RESULT

Clinical parameters like pain, bleeding and swelling were lower in laser group than bur group, although the difference was statistically not significant. However, postoperative swelling showed significant difference in the two groups. Laser group required almost double the time taken for bone cutting with bur. Trismus persisted for a longer period in laser group. Wound healing and complications were assessed clinically and there was no significant difference in both the groups.

CONCLUSION

Based on the results of our study, the possibility of bone cutting using lasers is pursued, the osteotomy is easily performed and the technique is better suited to minimally invasive surgical procedures. The use of Er: YAG laser may be considered as an alternative tool to surgical bur, specially in anxious patients.

Platelet Derived Growth Factor Secretion and Bone Healing After Er:YAG Laser Bone Irradiation

Er:YAG laser irradiation has been reported to enhance wound healing. However, no studies have evaluated the synthesis of growth factors after laser irradiation. The present study investigated the effects of laser irradiation on the amount of secretion of platelet derived growth factor (PDGF) in the wound, clarifying the effects of the Er:YAG laser on the bone healing. Osteotomies were prepared in the tibiae of 28 rats using an Er:YAG laser (test group). Maximum power of 8 watts, energy per pulse of 700 mJ, and frequency up to 50 Hz were used. The laser was used with external water irrigation, a spot size of 2 mm, energy per pulse of 500 to 1000 mJ/pulse, and energy density of 32 J/cm2. Twenty eight additional rats served as a control group and their osteotomies were prepared with a drill 1.3 mm in diameter at 1000 rpm, with simultaneous saline irrigation. Two rats from the tested group and 2 from the control group were sacrificed on each day following surgery (1–14 days), and the tissue specimens were prepared for histologic evaluation. Immunohistochemical staining with anti-PDGF was performed after histologic examination. The difference between the PDGF staining intensities of the 2 treatment groups was analyzed using a multivariate logistic regression test. A significant rise in PDGF staining occurred in both groups 2–3 days following surgery. However, while high PDGF counts remained for the 2-week experimental period in the laser group, PDGF levels in the control group returned to baseline levels 8 days post surgery. The 2 groups (laser and control) were found to be different throughout the experiment, and the rat type was found to be a significant predictor (P  =  .000011). The present study demonstrated that Er:YAG laser irradiation seems to stimulate the secretion of PDGF in osteotomy sites in a rat model. It is possible that the high levels of PDGF are part of the mechanism that Er:YAG irradiation enhances and improves the healing of osteotomy sites.

Comparison of Er:YAG laser and piezoelectric osteotomy: An animal study in sheep

OBJECTIVES

It was the aim of this study to compare the feasibility of complete osteotomy of long bones in sheep using a newly designed variable square pulsed Er:YAG laser and piezoelectric surgery. In addition to uneventful bone healing after laser osteotomy, the goal was to assess the possibility to cut thick bony structures with both techniques in a surgically acceptable time frame of 2-3 minutes.

MATERIAL AND METHODS

A tibia midshaft osteotomy was performed in 24 sheep using either an Er:YAG laser (n = 12) or piezoelectric device (n = 12). Laser and piezoelectric groups were divided in two subgroups (n = 6) with sheep sacrificed after 2 and 3 months, respectively. A complete radiological, histological and histomorphometric analysis was performed to compare the course of bone/fracture healing and remodelling.

RESULTS

Laser and piezoelectric osteotomies of the sheep tibia up to a depth of 22 mm were possible without any thermal damage. Radiological and histological results after 2 months showed primary gap healing with distinct periosteal callus formation on the transcortex. After 3 months, radiological and histological analysis revealed less callus formation on the transcortex, with almost no visible osteotomy gap and a distinct formation of lamellar bone crossing the original osteotomy gap.

CONCLUSION

Er:YAG laser osteotomy can successfully be used in long bones with a depth of up to 22 mm, thus challenging the dogma of adverse effects of laser osteotomy due to thermal or other damages.

A comparison of bone bed preparation with laser and conventional drill on the relationship between implant stability quotient (ISQ) values and implant insertion variables

PURPOSE

The aim of this study was to investigate a comparison of implant bone bed preparation with Er,Cr:YSGG laser and conventional drills on the relationship between implant stability quotient (ISQ) values and implant insertion variables.

MATERIALS AND METHODS

Forty implants were inserted into two different types of pig rib bone. One group was prepared with conventional drills and a total of 20 implants were inserted into type I and type II bone. The other group was prepared with a Er,Cr:YSGG laser and a total of 20 implants were inserted into type I and type II bone. ISQ, maximum insertion torque, angular momentum, and insertion torque energy values were measured.

RESULTS

The mean values for variables were significantly higher in type I bone than in type II bone (P < .01). In type I bone, the ISQ values in the drill group were significantly higher than in the laser group (P < .05). In type II bone, the ISQ values in the laser group were significantly higher than in the drill group (P < .01). In both type I and type II bone, the maximum insertion torque, total energy, and total angular momentum values between the drill and laser groups did not differ significantly (P ≥ .05). The ISQ values were correlated with maximum insertion torque (P < .01, r = .731), total energy (P < .01, r = .696), and angular momentum (P < .01, r = .696).

CONCLUSION

Within the limitations of this study, the effects of bone bed preparation with Er,Cr:YSGG laser on the relationship between implant stability quotient (ISQ) values and implant insertion variables were comparable to those of drilling.

Different air-water spray regulations affect the healing of Er,Cr:YSGG laser incisions

Surgeries performed with high-intensity laser devices may be improved with accurate protocols, including the air-water spray regulation. Thus, this study sought to investigate the healing process of wounds made on the dorsum of rat tongues using an Er,Cr:YSGG laser device with different air-water spray regulations. The incisions were made on the dorsum of Wistar rat tongues using an Er,Cr:YSGG laser with three different air-water spray regulations (100/0%, 50/50%, 11/7%). Scalpel incisions functioned as controls. The sacrifices occurred between 0 and 14 days after surgery. Morphological, histological, and immunohistochemical (fibronectin and type III collagen) analysis of the wounds were performed. The air-water spray regulation influenced wound healing and the inflammatory response, especially in the earlier stages. Incisions performed using the 100/0% air/water spray regulation had the worst results, expressing a greater amount of fibronectin and type III collagen. The 50/50% air/water spray regulation brought in a non-clear surgical field and poor laser interaction with the tissue. The 11/7% air/water spray regulation showed the best clinical results and less pronounced histological events. According to the results encountered, the air-water spray should be regulated to improve surgery.

Bone healing after bur and Er:YAG laser ostectomies

PURPOSE

Ostectomies, performed by different methods, are often necessary in oral and maxillofacial surgery. Rotatory and reciprocating devices are most frequently used but have disadvantages, such as noise, vibration, and the potential for inducing thermal damage. Laser systems are interesting alternatives to these procedures. We analyzed bone healing in a rat model after mandibular ostectomy with a surgical bur or noncontact erbium:yttrium-aluminum-garnet laser using different energy levels.

MATERIALS AND METHODS

Four groups of 5 rats each underwent ostectomy of the bone cortical of the mandibular body, with irrigation, using a surgical bur or erbium:yttrium-aluminum-garnet laser with different energy parameters. A metal plate was used for morphologic standardization of the cavities. The samples collected after 7, 14, 45, 60, and 90 days were analyzed by optical microscopy.

RESULTS

The ostectomies performed with surgical burs resulted in bone healing from the cortical endosteum and remaining trabecular bone. The cortical endosteum was repaired after 45 days, followed by bone remodeling. After laser irradiation, healing involved bone neoformation from the external cortical surface and endosteum. Surface regions with thermal damage were observed after laser treatment in the 3 conditions used up to day 60, followed by bone remodeling.

CONCLUSIONS

Laser ostectomies resulted in a thin layer of thermal damage. Bone healing was faster when surgical burs were used, with similar results reached after 90 days.

Low-level laser therapy supported teeth extractions of two patients receiving IV zolendronate

BRONJ (bisphosphonate-related osteonecrosis of jaws) is a frequently encountered disease, particularly in the maxillofacial region, and a consequence of bisphosphonate use. Treatment of BRONJ remains controversial, as efficiency of medical and surgical approaches as well as a combination of these methods with supportive treatments have not been clearly demonstrated in the literature. In recent years, laser usage alone or in combination with the main therapy methods, has become popular for the treatment of bisphosphonate-related osteo-necrosis of jaws. In this article, we present the successful management of two dental patients who had high potentials for BRONJ development as a result of chemo and radiotherapy combined with IV zoledronic acid application. Multiple consecutive teeth extractions followed with primary wound closure and LLLT applications were performed under high doses of antibiotics prophylaxis. Satisfactory wound healing in both the surrounding soft and hard tissues was achieved. LLLT application combined with atraumatic surgical interventions under antibiotics prophylaxis is a preferable approach in patients with a risk of BRONJ development. Adjunctive effect of LLLT in addition to careful infection control on preventing BRONJ was reported and concluded.

Low level laser therapy does not modulate the outcomes of a highly bioactive glass-ceramic (Biosilicate) on bone consolidation in rats

The main purpose of the present work was to evaluate if low level laser therapy (LLLT) can improve the effects of novel fully-crystallized glass-ceramic (Biosilicate) on bone consolidation in tibial defects of rats. Forty male Wistar rats with tibial bone defects were used. Animals were divided into four groups: group bone defect control (CG); group bone defect filled with Biosilicate (BG); group bone defect filled with Biosilicate, irradiated with LLLT, at 60 J cm(-2) (BG 60) and group bone defect filled with Biosilicate, irradiated with LLLT, at 120 J cm(-2) (BG 120). A low-energy GaAlAs 830 nm, CW, 0.6 mm beam diameter, 100 W cm(-2), 60 and 120 J cm(-2) was used in this study. Laser irradiation was initiated immediately after the surgery procedure and it was performed every 48 h for 14 days. Fourteen days post-surgery, the three-point bending test revealed that the structural stiffness of the groups CG and BG was higher than the values of the groups BG60 and BG120. Morphometric analysis revealed no differences between the control group and the Biosilcate group. Interestingly, the groups treated with Biosilicate and laser (BG 60 and BG120) showed statistically significant lower values of newly formed bone in the area of the defect when compared to negative control (CG) and bone defect group filled with Biosilicate (CB). Our findings suggest that although Biosilicate exerts some osteogenic activity during bone repair, laser therapy is not able to modulate this process.

Bone damage induced by different cutting instruments--an in vitro study

The aim of this study was to compare the peripheral bone damage induced by different cutting systems. Four devices were tested: Er:YAG laser (2.94 mm), Piezosurgery, high-speed drill and low-speed drill. Forty-five bone sections, divided into 9 groups according to different parameters, were taken from pig mandibles within 1 h post mortem. Specimens were fixed in 10% buffered formalin, decalcified and cut in thin sections. Four different parameters were analyzed: cut precision, depth of incision, peripheral carbonization and presence of bone fragments. For statistical analysis, the Kruskal-Wallis test was applied to assess equality of sample medians among groups. All sections obtained with the Er:YAG laser showed poor peripheral carbonization. The edges of the incisions were always well-shaped and regular, no melting was observed. Piezosurgery specimens revealed superficial incisions without thermal damage but with irregular edges. The sections obtained by traditional drilling showed poor peripheral carbonization, especially if obtained at lower speed. There was statistically significant differences (p<0.01) among the cutting systems for all analyzed parameters. Er:YAG laser, gave poor peripheral carbonization, and may be considered an effective method in oral bone biopsies and permits to obtain clear and readable tissue specimens.

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.

An Ultrasound Assisted Anchoring Technique (BoneWelding Technology) for Fixation of Implants to Bone - A Histological Pilot Study in Sheep

The BoneWelding^® Technology offers new opportunities to anchor implants within bone. The technology melted the surface of biodegradable polymer pins by means of ultrasound energy to mould material into the structures of the predrilled bone. Temperature changes were measured at the sites of implantation in an in vitro experiment. In the in vivo part of the study two types of implants were implanted in the limb of sheep to investigate the biocompatibility of the method. One implant type was made of PL-DL-lactide (PLA), the second one was a titanium core partially covered with PLA. Healing period was 2 and 6 months, with 3 sheep per group. Bone samples were evaluated radiologically, histologically and histomorphometrically for bone remodeling and inflammatory reactions. Results demonstrated mild and short temperature increase during insertion. New bone formed at the implant without evidence of inflammatory reaction. The amount of adjacent bone was increased compared to normal cancellous bone. It was concluded that the BoneWelding^® Technology proved to be a biocompatible technology to anchor biodegradable as well as titanium-PLA implants in bone.

Osteonecrosis of the jaws caused by bisphosphonates: evaluation of a new therapeutic approach using the Er:YAG laser

A series of 49 patients diagnosed with osteonecrosis and all treated with latest-generation bisphosphonates was reviewed retrospectively to evaluate the use of erbium-doped: yttrium, aluminum, and garnet laser (Er:YAG) in terms of clinical outcome, and examine current trends from the clinical-therapeutic standpoint. Pathology reports on specimens submitted over the previous 7 years from either the mandible or the maxilla were reviewed; 49 patients were identified as having osteonecrosis of the jaws. For each of these cases, the medical history and profile were evaluated; 19 were treated with conservative therapy, 20 with radical surgery, and 10 with Er:YAG laser (2,940 nm). Of the 20 patients treated surgically (bone baquette, curettage, sequestrectomy of the necrotic bone), some required re-treatment, which resulted in bone fracturing. None of the patients were treated successfully. The 19 cases treated conservatively produced an improvement in symptoms, but not remission of the lesions. Of the ten patients treated with Er:YAG laser, six achieved total remission of signs and symptoms, four an improvement, and re-treatment was required in one case. Our present approach is to recommend intensive prophylactic care before the administration of bisphosphonates, and great caution is advised even in simple maneuvers like curettage, because this may exacerbate the avascular process. The use of Er:YAG laser appears to be promising (within the limits of our experience). It can be concluded that at 1 year of laser surgery, the treatment led to significant improvements in clinical parameters, and may represent a valid alternative, although studies on a larger scale are needed.

Influence of low-level laser therapy on biomaterial osseointegration: a mini-review

The aim of this paper is to provide an overview of the available literature on low-level laser therapy (LLLT) and its influence on bone repair and the osseointegration of biomaterials. Extensive studies of alveolar bone repair, a common problem in periodontal therapy, have been conduced worldwide. The utility of LLLT in biomaterial osseointegration is still unanswered, due to lack of literature and poorly understood mechanisms. It is still difficult for one to compare studies about the action of LLLT on the osseointegration of biomaterials because the experimental models and duration of treatments are very distinct. However, it could be concluded that LLLT may offer advantages in terms of periodontal and bone functional recovery and biomaterial osseointegration.

Effects of femtosecond laser irradiation on osseous tissues

BACKGROUND AND OBJECTIVE

Few studies have investigated femtosecond (fs) lasers for cutting bone tissue.

STUDY DESIGN/MATERIALS AND METHODS

A 775 nm, 1 kHz, 200 femtosecond, up to 400 microJ laser system was used to irradiate in vitro calcified cortical bone samples and bone tissue culture samples.

RESULTS

The ablation threshold in cortical bone was 0.69+/-0.08 J/cm(2) at 775 nm and 0.19+/-0.05 J/cm(2) at 387 nm. Plasma shielding experiments determined that the ablation plume and the plasma significantly affect material removal at high repetition rates and appear to generate thermal transients in calcified tissue. Confocal analysis revealed intact enzymatic activity on the surface of cells immediately adjacent to cells removed by fs laser irradiation.

CONCLUSIONS

These experiments demonstrate that fs lasers used for bone tissue cutting do not appear to generate significant temperature transients to inactivate proteins and that cellular membrane integrity is disrupted for only a few cell layers.