Reconstructing Critical-Sized Mandibular Defects in a Rabbit Model: Enhancing Angiogenesis and Facilitating Bone Regeneration via a Cell-Loaded 3D-Printed Hydrogel-Ceramic Scaffold Application.

In this study, we propose a spatially patterned 3D-printed nanohydroxyapatite (nHA)/beta-tricalcium phosphate (ß-TCP)/collagen composite scaffold incorporating human dental pulp-derived mesenchymal stem cells (hDP-MSCs) for bone regeneration in critical-sized defects. We investigated angiogenesis and osteogenesis in a rabbit critical-sized mandibular defect model treated with this engineered construct. The critical and synergistic role of collagen coating and incorporation of stem cells in the regeneration process was confirmed by including a cell-free uncoated 3D-printed nHA/ß-TCP scaffold, a stem cell-loaded 3D-printed nHA/ß-TCP scaffold, and a cell-free collagen-coated 3D-printed nHA/ß-TCP scaffold in the experimental design, in addition to an empty defect. Posteuthanasia evaluations through X-ray analysis, histological assessments, immunohistochemistry staining, histomorphometry, and reverse transcription-polymerase chain reaction (RT-PCR) suggest the formation of substantial woven and lamellar bone in the cell-loaded collagen-coated 3D-printed nHA/ß-TCP scaffolds. Histomorphometric analysis demonstrated a significant increase in osteoblasts, osteocytes, osteoclasts, bone area, and vascularization compared to that observed in the control group. Conversely, a significant decrease in fibroblasts/fibrocytes and connective tissue was observed in this group compared to that in the control group. RT-PCR indicated a significant upregulation in the expression of osteogenesis-related genes, including BMP2, ALPL, SOX9, Runx2, and SPP1. The findings suggest that the hDP-MSC-loaded 3D-printed nHA/ß-TCP/collagen composite scaffold is promising for bone regeneration in critical-sized defects.

Glomus tumor in the buccal mucosa: A case report and review of the literature.

Glomus tumors are rare benign neoplasms usually occurring in the upper and lower extremities. However, oral cavity involvement is rare, with only a few case reports. We present a 37-year-old male patient with a chief complaint of an exophytic lesion in the left buccal mucosa for one year referred to our center. At the time, he did not have any pain or lymphadenopathy. The patient underwent surgery using a high-power CO2 laser. His histopathological examination revealed a glomus tumor. After 2 years of follow-up, no evidence of recurrence was detected. Glomus tumors should be taken seriously when patients have a painless exophytic bluish lesion in the buccal mucosa.

Clinical evaluation of marginal fit of uncemented CAD-CAM monolithic zirconia three-unit restorations in anterior areas, using scannable and conventional polyvinyl siloxane impression materials.

BACKGROUND: The accuracy of impression techniques determines the marginal fit of fixed prostheses. Marginal accuracy plays a main role in the success and failure of treatments. This in-vivo study evaluated the marginal fit of anterior three-unit monolithic zirconia fixed partial dentures (FPDs) using conventional and scannable polyvinyl siloxane impression materials. METHODS: Ten patients were selected to replace the lateral teeth with a three-unit monolithic zirconia bridge. For each patient, in the first group, an impression was made with a two-step putty-wash technique using scannable polyvinyl siloxane material (BONASCAN; DMP, Greece). In the identical session, as the second group, an impression of conventional putty-wash polyvinyl siloxane was taken (BONASIL A+ Putty; DMP, Greece). The marginal discrepancy was measured through the replicas, which were cut perpendicularly within the buccolingual and mesiodistal directions. An Independent t-test was employed for data analyses (P < 0.05). RESULTS: The marginal discrepancy in a conventional method for central abutment in mid-buccal, mid-lingual, mid-mesial, and mid-distal was higher than in the scannable method but it was not significant (P > 0.05). Also, the marginal discrepancy for canine abutment in the conventional method was higher than in the scannable method, but it was not significant, either (P > 0.05). CONCLUSIONS: FPDs fabricated from both scannable and conventional impression materials were not superior to each other in marginal fit for both central and canine abutments by evaluation using the replica technique.

Nasal sebaceous carcinoma: A rare case.

Nasal sebaceous carcinoma is an extremely rare cutaneous malignancy. We present the case of an 86-year-old female who had a skin nodule with surface telangiectasia on the right ala of the nose. The lesion had been removed and has been reconstructed with an advancement rotational flap with a minimal residual defect. Upon histopathological examination, the lesion was diagnosed with sebaceous carcinoma. The patient was followed up because of the high rate of recurrence as well as metastatic potential. No recurrence occurred during 4 years of follow-up, and the patient was unwilling to reconstruct the remaining alar defect. We present a rare skin cancer case that could be encountered during the head and neck examination by oral and maxillofacial surgeons. By reporting this case, we aimed to raise the awareness and familiarize clinicians with these less common lesions.

In Situ Casting of Platelet Rich Plasma/SiO2/Alginate for Bone Tissue Engineering Application in Rabbit Mandible Defect Model.

Statement of the Problem: The administration of both platelet rich plasma (PRP) and silicon dioxide (SiO2) to the bone defects accelerates bone repair and regeneration. Appli-cation of both of them may show synergistic regenerative effects. Purpose: Our objective was to evaluate the possible synergistic osteogenic effects of PRP and SiO2 by injecting them using an ad hoc device. Materials and Method: In this experimental study, PRP/SiO2 scaffolds were fabricated by in situ casting method with the help of CaCl2 as the gelation factor and alginate as the stroma; and then, the biodegradability and spatial arrangement were assessed. The injecta-ble scaffold was introduced into the 40 rabbit mandibular defects by an ad hoc two-channel injecting device. Five defects received PRP/SiO2/alginate as the treatment; the other sets of defects were treated by PRP/alginate, SiO2/alginate, and the last five defects served as the control groups by getting only alginate injections. The osteogenicity of the scaffolds was evaluated by radiological and histological procedures; they were then compared with each other. Analysis of variance and least significant difference tests were used to analyze the data. Results: The SiO2-treated group showed a significant higher bone area compared to PRP/ SiO2-treated groups on day 40 (p= 0.013). The number of osteocytes was higher in SiO2-treated than the control groups on both 20 and 40 days (p= 0.032 and 0.022, respectively). The number of osteoclast was also higher in SiO2-treated than PRP-treated group (p= 0.028). In addition, the cells of this group had just started to create Haversian systems in newly formed bone tissues. Conclusion: Silica demonstrated a superior osteogenic activity over PRP in both short and long term periods. Evidently, they showed no synergistic regenerative effects. Our ad hoc device was efficiently capable of inserting the scaffolds into the injured sites with no diffi-culties or complications.

Shaping ability of three nickel-titanium rotary instruments in simulated L-shaped canals: OneShape, Hero Shaper, and Revo-S.

BACKGROUND: Shaping ability of a file plays an important role during instrumentation in an endodontic treatment. This study aimed to compare the shaping ability of OneShape (OS), Hero Shaper (HS), and Revo-S (RS) instruments in simulated L-shaped canals. METHODS: Forty-eight simulated L-shaped canals were prepared to an apical size of 25 using OS, HS, and RS (all from Micro-Mega SA, Besançon, France), (n = 16 canals/group) systems. The amount of resin removed after each canal's preparation was measured and compared after producing a composite image made from the superimposition of pre and post-instrumented canals. Canal aberrations and the preparation time were also recorded. The data were statistically analysed by using ANOVA, Tukey, and Chi-square tests. RESULTS: One file fractured during instrumentation in the RS group. A significant difference was found at the apical end of the prepared simulated canal between the groups, with RS showing the least amount of resin removal from the inner side of the canals and HS showing the highest amount of resin removal from the outer side (P < 0.05). Regarding the total width of the canals after preparation, a significant difference was found between the groups at the apical end and the straight portion of the canals, and RS removed the least amount of resin at the straight portion of the canals (P < 0.05). No statistically significant differences were found between the different instruments regarding canal aberrations' incidence (P > 0.05). CONCLUSIONS: All of the files showed a tendency to straighten the canals, whereas OS files maintained the original canal curvatures well.

Analysis of hard tissue facial symmetry after unilateral mandibular reconstruction.

BACKGROUND: This study aimed to determine how successful reconstruction of the mandible can recover the symmetry. MATERIALS AND METHODS: All patients who underwent surgical treatment for unilateral mandibular reconstruction in 4 years were retrospectively examined. Bilateral differences of gonion (GO) positions were measured in 3 dimensions based on immediate postoperative computed tomography. The data collected was analyzed in 3 ways: First, the comparison of bilateral differences of GO in 3 dimensions. Second, the mean Asymmetry Index in control subjects was used to divide all cases into three groups: "Symmetry," "Asymmetry," and "Marked asymmetry." Third, "maximum normal asymmetry" was calculated, and all cases were categorized as below and above maximum normal asymmetry. The difference between two gonial angles was used to determine the amount of asymmetry. RESULTS: Forty-seven patients and 47 normal adults were enrolled. The mean bilateral GO difference in the control group was higher than in the study group patients, but it was not statistically significant. The mean Asymmetry Index for the control group was not also significantly higher than the study cases. The study group was "Symmetric" in 78.7% of the cases whereas the control group in 91.4%, 19.1% of the study group and 8.5% of controls were "Asymmetric," and 2.1% of study cases and 0% of controls were "Markedly Asymmetric." Maximum normal asymmetry was 82.9% in the study group and 97.8% in the control group. The mean differences between the right and left gonial angles were higher in the study group, but it was not significant (P = 0.1). CONCLUSIONS: Our study's results showed that bilateral symmetry in mandibular reconstruction patients was satisfactory and similar to the normal individuals.

The effects of orthognathic surgery on auditory function.

BACKGROUND: Orthognathic surgery is widely used in treating functional and skeletal problems. Any surgical procedure could cause side effects. OBJECTIVES: This study aimed to evaluate the potential changes in orthognathic surgery on the hearing function of patients. MATERIALS AND METHODS: Thirty-one orthognathic surgery candidates were recruited in this study. Patients underwent either single or double jaw surgery. Pure tone audiometry (PTA), tympanometry, and Eustachian Tube Dysfunction Test (ETFT) were performed postoperatively at 24 h, 6 weeks, and 6 months after surgery. Patients were tabulated based on the type of maxilla and mandibular surgical movements (vertical and horizontal). RESULTS: PTA evaluation, based on horizontal or vertical movements, did not show significant differences, although vertical movements resulted in less change in hearing threshold. In other words, no significant changes occurred in patients' hearing threshold after surgery. No significant difference was also observed between horizontal and vertical movements in the results of tympanometry. Negative changes were found in the results of ETFT in vertical movements, which returned to pre-surgery values in the final test. CONCLUSIONS: The risk of minor changes in hearing function is probable during the first week after orthognathic surgery, but these negative changes will either totally fade or remain negligible. Patients gave informed consent preoperatively, and reassurance postoperatively is prudent.

A Long-Standing Giant Mandibular Ameloblastoma and its Management with Microvascular Free Fibular Graft: a Case Report.

Ameloblastoma is one of the most common benign epithelial odontogenic tumors of jaws. We report a case of long-standing slow-growing giant ameloblastoma involving almost all of mandibular bone. The solid multicystic lesion was excised, and the histopathological examination showed the follicular type of ameloblastoma. Furthermore, the defect was reconstructed with microvascular osteocutaneous free fibular graft.

Maxillary Sinus Myxofibrosarcoma Mimicking Nodular Fasciitis: A Rare Case Report.

Myxofibrosarcoma (MFS) is a fibroblastic soft tissue sarcoma that is extremely rare in the maxillofacial region. Due to its non-specific clinicoradiographic findings and challenging histopathological features, the diagnosis is difficult. Here, we present a case of MFS which was first diagnosed as nodular fasciitis. The initial examination of the incisional biopsy showed a benign-appearing proliferation of fibroblasts without features of malignancy. The patient returned with recurrence four months after surgical excision of the primary lesion. The second histologic study revealed a high-grade spindle cell sarcoma with myxoid features most compatible with MFS. Definitive diagnosis of MFS was confirmed by these histopathologic features and supportive immunohistochemical stains. Unfortunately, the patient died of disease 3 months later.

Does the systemic administration of L-arginine affect dental implant stability in nicotine consumer dogs?

BACKGROUND: Nicotine can have detrimental effects on dental implant osseointegration. This study aimed to evaluate the influence of systemic L-arginine supplement on the osseointegration of dental implants in nicotine consumer dogs. METHODS: Twelve 1-year Labrador Retriever dogs had their right and left third and fourth mandibular premolars removed, and the sockets were left to heal for 6 months. Dogs were randomly divided into three groups (n = 16): group 1-0.2 mg/kg nicotine was injected twice daily; group 2-0.2 mg/kg nicotine was injected twice daily in addition to 200 mg/kg L-arginine capsules taken orally; and group 3-placebo. Forty-eight dental implants were inserted into the healed sockets of the dog's mandible and were assessed by implant stability quotient (ISQ) using resonance frequency analysis (RFA) during 4 weeks and insertion and removal torque value analysis. RESULTS: No implant failure occurred during the study period. The change in torque value between insertion and removal was similar in the placebo and nicotine+arginine consumer dogs (p = 0.276), which shows a positive effect of arginine supplementation in nicotine consumers. There was a significant difference in torque value change between nicotine+arginine vs. nicotine consumers (p = 0.049) and placebo vs. nicotine (p = 0.003). After 4 weeks, the placebo had the most significant improvement in torque value (47.0 ± 16.9), followed by nicotine+arginine (25.1 ± 37.8), and the worst torque value was for the nicotine group (- 5.7 ± 24.0) pound per inch. The results show that except in the first week, there are significant differences in ISQ between the groups in different periods. ISQ in all of the groups has reduced at first but then increased over time. At the time of implant placement, insertion torque was significantly higher in the nicotine consumer group than the nicotine+arginine consumer group and placebo group (p = 0.020). CONCLUSION: Arginine supplementation promotes bone healing and implant primary stability by improving dental implant osseointegration biomechanical characteristics.

Kissing tumors; the concurrent diagnosis of leiomyosarcoma and squamous cell carcinoma of the esophagus.

BACKGROUND: Esophageal leiomyosarcoma (LMS) is a rare tumor that constitutes less than 1% of all malignant esophageal tumors. Concurrent occurrence of esophageal leiomyosarcoma with squamous cell carcinoma (SCC) is even rarer than isolated leiomyosarcoma. CASE PRESENTATION: In this report, we present a case of concurrent leiomyosarcoma and SCC in a 64-year-old woman presenting with vomiting and solid dysphagia, which has not been properly diagnosed following several referrals and diagnostic modalities. At last Exploratory laparotomy with gastric pull-up was performed in addition to radical laryngectomy with partial resection of the esophagus and subtotal thyroidectomy. Pathologic evaluation of the surgical specimen showed concurrent LMS (5.2 × 4.5 × 3 cm) and SCC (1.5 × 0.6 × 0.6 cm) at the same anatomical level in the proximal esophagus. CONCLUSIONS: This study proposes the importance of using ancillary diagnostic tests such as immunohistochemistry (IHC) to diagnose less common cases such as concurrent LMS and SCC.

Synergic effects of decellularized bone matrix, hydroxyapatite, and extracellular vesicles on repairing of the rabbit mandibular bone defect model.

BACKGROUND: Extracellular vesicles (ECV) and bone extracellular matrix (ECM) have beneficial effects on the treatment of some pathological conditions. The purpose of this study was to find the synergic effects of decellularized bone (DB) ECM and ECVs on the repair of rabbit. METHODS: The quality of decellularized sheep bones was confirmed by H&E, Hoechst, DNA quantification, immunohistochemistry, histochemical staining, and scanning electron microscopy (SEM). Osteoblast-derived ECVs were evaluated by internalization test, Transmission electron microscopy, Dynamic light scattering, and flow cytometry for CD9, CD63, CD81 markers. The hydrogel containing DB and hydroxyapatite (HA) with or without ECVs was evaluated for osteoblast functions and bone repair both in vitro and in vivo. RESULTS: The data indicated ECM preservation after decellularization as well as cell depletion. In vitro assessments revealed that mineralization and alkaline phosphatase activity did not improve after treatment of MG63 cells by ECVs, while in vivo morphomatrical estimations showed synergic effects of ECVs and DB + HA hydrogels on increasing the number of bone-specific cells and vessel and bone area compared to the control, DB + HA and ECV-treated groups. CONCLUSIONS: The DB enriched with ECVs can be an ideal scaffold for bone tissue engineering and may provide a suitable niche for bone cell migration and differentiation.

Intraoperative Blood Loss in Maxillofacial Trauma Surgery.

BACKGROUND AND OBJECTIVES: This study is aimed to assess the intraoperative blood loss of patients with maxillofacial bone fracture surgical intervention and to assess their need for blood transfusion. MATERIALS AND METHODS: In this retrospective study, intraoperative blood loss of 206 patients with facial bone fractures, who underwent surgery between 2017 and 2018, was retrieved. The patient's demographic information, the amount of blood loss, the type of facial bone fracture, and the patient's requirement for blood products were evaluated. RESULTS: The average amount of intraoperative blood loss was 77.6 ml, and none of the patients required a blood transfusion during the operation in this group of patients. maxillofacial bone fracture was most common in young males. The leading cause of fractures was motor vehicle accident. There was a reverse correlation between the patient's age and surgical blood loss, but there was no statistically significant relationship between the patient's gender and intraoperative surgical blood loss. CONCLUSION: The results of the present study show that preparation for blood transfusion in patients with maxillofacial traumatic bone fracture requiring surgery is uncommon if patients have no systemic disease or specific blood dyscrasias preoperatively.

Marginal bone resorption of posterior mandible dental implants with different insertion methods.

BACKGROUND: To evaluated the marginal bone loss around dental implants by two insertion methods. METHODS: Eligible patients were divided into two groups; manual and mechanized groups. Peri-apical x-ray using a customized device to standardize the radiographs designed and used to take three periodical radiographs; after surgery, three months, and six months follow up. An independent t-test was used to compare the two groups regarding the average level of marginal bone loss (p < 0.05). RESULTS: After excluding dropouts, a total of 273 patients (120 males and 153 females, aged between 25 and 67 years old) were included in the study. The average marginal bone loss in the manual insertion method was 0.44 ± 0.84 mm, and 0.59 ± 0.20 mm, and for the mechanized method was 0.51 ± 0.20 mm and 0.67 ± 0.19 mm after three and six months, respectively. There was a significant difference in marginal bone loss after six months between the two groups(p < 0.001). However, no differences were observed after three months (p = 0.24). CONCLUSIONS: Under the condition of this study, both techniques were safe and resulted in an acceptable amount of bone resorption; however, in the manual method, the less marginal bone loss occurred after six months.

Oro-Antral Fistula Repair With Different Surgical Methods: a Retrospective Analysis of 147 Cases.

STATEMENT OF THE PROBLEM: An oro-antral fistula (OAF) creates a passage for oral microbes into maxillary sinus with numerous possible complications. PURPOSE: This retrospective study evaluates the success of three different surgical techniques of OAF repair. MATERIALS AND METHOD: Records of patients that were treated for OAF repair were retrieved and reviewed. Data recorded were patients' age, gender, etiology, size, location, duration, and method of repair. According to the surgical technique used to repair the OAF, patients were divided into three groups including buccal flap, palatal flap, and buccal fat pad. All of the patients were locally anesthetized with 2% lidocaine and 1/100000 or 1/80000 epinephrine. Then the edges of the fistula were excised and fistula wall was dissected in a stitched layer by three surgical methods. The three groups were compared concerning the success or failure of surgical technique based on complete closure of OAF after three months postoperatively. RESULTS: 147 patients (116 males and 31 females) with adequate records were included in the study. The surgical methods used in patients were, buccal flap in 59 (40.1%), buccal fat pad in 42 (40.8%), and palatal flap in 28 (19%) individuals. Success rates of these techniques were significantly different. Buccal fat pad was the most successful flap (98.3%), followed by buccal flap (89.8%), and palatal flap (85.7%). The most common cause of OAF in this group of patients was dental extraction. CONCLUSION: Buccal fat pad flap seems to be one of the best treatments for the closure of OAF lager than 5 mm.

Shaping Ability of ProTaper Universal, ProTaper NEXT and WaveOne Primary in Severely Curved Resin Blocks.

AIM: Complex anatomy of roots requires endodontic rotary instruments that respect and follow that anatomy. The purpose of this study was to compare the shaping ability of three engine-driven nickel-titanium instruments in severely curved simulated canals. MATERIALS AND METHODS: Forty-eight severely curved simulated canals in resin blocks were prepared to an apical size of 25 using the following systems (n = 16 per group): ProTaper Universal (PTU), ProTaper NEXT (PTN), and WaveOne Primary (WO) (all Dentsply Maillefer, Ballaigues, Switzerland). Composite images were made from the superimposition of pre- and post-instrumentation images. The amount of resin removed by each system was measured by using a digital template and image analysis software. Shaping ability of each system was compared using different parameters: total resin removal, centering ability, canal transportation in the apical, middle and coronal third of canal. Preparation times were also recorded. The data were statistically analyzed by using analysis of variance, paired t-test, and Tukey's post hoc test. RESULTS: Canals prepared with PTN were better centered in the apical part than those prepared with WO and PTU (p < 0.05). WO removed significantly more resin at the outer aspect of the maximum point of curvature. WO and PTU caused similar canal transportations at 7 points out of 11 measuring points. At measuring points 3, 4, and 5 WO caused more canal straightening than PTU. Instrumentation with PTU required more time than with the two other instruments (p <0.05). No preparation error or instrument separation occurred. CONCLUSION: In the apical part of the canals PTN obtained the best results with regard to canal transportation. CLINICAL SIGNIFICANCE: All of the rotary instruments were safe in preparing severely curved canals and PTN showed better preparation of apical part of the canal.

Tapia's Syndrome after Cosmetic Malar Augmentation: a Case Report.

Tapia's syndrome is an infrequent complication of airway manipulation. It is usually due to an extra-cranial ipsilateral injury to the hypoglossal nerve and the recurrent laryngeal branch of the vagal nerve, which can happen after any surgery. It is usually characterized by unilateral paralysis of the muscle of the tongue and vocal cords although it can also occur bilaterally. We present a patient with postoperative unilateral hypoglossal and recurrent laryngeal nerves palsy that occurred after cosmetic malar augmentation for esthetic correction of the left cheek flatness with an uncomplicated transnasal intubation. We report the first case of Tapia's syndrome after porous polyethylene implantation for cosmetic cheek reconstruction. The patient was treated immediately after the diagnosis with 0.5mg dexamethasone for two weeks. After three months, the movements of the vocal cord and tongue movement started to improve and the patient's hoarseness fully recovered after six months.

Improvement of Esthetic, Functional, and Social Well-Being After Orthognathic Surgical Intervention: A Sampling of Postsurgical Patients Over a 10-Year Period From 2007 to 2017.

PURPOSE: The objectives of this study were to evaluate the effect of orthognathic surgery on the long-term quality of life of patients who received this treatment and to delineate the common reasons for dissatisfaction. MATERIALS AND METHODS: In this retrospective cohort study, patients who underwent orthognathic surgery were studied. One hundred thirty-two patients who had undergone orthognathic surgery from 2007 to 2017 in the oral and maxillofacial surgery department participated in this study. They were divided based on their dentofacial deformity into those with Class II malocclusion and those with Class III malocclusion. Each participant completed a modified questionnaire used to assess the patient's esthetic, social, and functional abilities after orthognathic surgery. RESULTS: The rate of esthetic improvement in orthognathic surgery patients was 91.7%. No significant difference between male and female patients was found regarding the changes in social, esthetic, and functional aspects before and after orthognathic surgery. Both genders recommended orthognathic surgery for patients with similar problems. One in four patients was dissatisfied with the nasal appearance after the surgical procedure (25.8%). CONCLUSIONS: In this study the patients' satisfaction from the orthognathic surgical procedure was mostly a result of improvements in facial esthetics, followed by psychological well-being and then functional abilities. Most dissatisfaction after the orthognathic surgical procedure was related to nasal appearance.

Effect of CO2 laser power intensity on the surface morphology and friction behavior of alumina ceramic brackets.

OBJECTIVE: This study aims at reducing frictional resistance of the ceramic brackets by using CO2 laser irradiation. METHODS: Forty-two polycrystalline Al2 O3 ceramic brackets were randomly divided into six groups of seven samples: a control group B0 (not subjected to laser irradiation) and five groups subjected to irradiation with intensities of 10 (B10), 30 (B30), 70 (B70), 90 (B90), and 110 (B110) J/cm2 . After irradiation, two samples from each group were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), while the remaining five samples were tested for frictional resistance. The sliding friction of stainless steel wires (SS-wires) in the brackets was measured using a universal testing machine. RESULTS: Samples from the first set (groups B0, B10, and B30) were significantly more resistant to wire sliding than the samples from the second set (groups B70, B90, and B110). The SEM analysis shows different degrees of blister formation on the bracket surfaces subjected to laser irradiation and no changes in their grain sizes. The AFM results indicate more consistent blister formation for groups B70, B90, and B110 than for other groups. CONCLUSION: Different CO2 laser power intensities significantly affect frictional resistances of SS-wires in Al2 O3 ceramic brackets.