Peri-implant osseointegration after low-level laser therapy: micro-computed tomography and resonance frequency analysis in an animal model.

The purpose of the present study is to evaluate the effects of low-level laser therapy on the osseointegration process by comparing resonance frequency analysis measurements performed at implant placement and after 30 days and micro-computed tomography images in irradiated vs nonirradiated rabbits. Fourteen male New Zealand rabbits were randomly divided into two groups of seven animals each, one control group (nonirradiated animals) and one experimental group that received low-level laser therapy (Thera Lase®, aluminum-gallium-arsenide laser diode, 10 J per spot, two spots per session, seven sessions, 830 nm, 50 mW, CW, Ø 0.0028 cm2). The mandibular left incisor was surgically extracted in all animals, and one osseointegrated implant was placed immediately afterward (3.25ø × 11.5 mm; NanoTite, BIOMET 3i). Resonance frequency analysis was performed with the Osstell® device at implant placement and at 30 days (immediately before euthanasia). Micro-computed tomography analyses were then conducted using a high-resolution scanner (SkyScan 1172 X-ray Micro-CT) to evaluate the amount of newly formed bone around the implants. Irradiated animals showed significantly higher implant stability quotients at 30 days (64.286 ± 1.596; 95 % confidence interval (CI) 60.808-67.764) than controls (56.357 ± 1.596; 95 %CI 52.879-59.835) (P = .000). The percentage of newly formed bone around the implants was also significantly higher in irradiated animals (75.523 ± 8.510; 95 %CI 61.893-89.155) than in controls (55.012 ± 19.840; 95 %CI 41.380-68.643) (P = .027). Laser therapy, based on the irradiation protocol used in this study, was able to provide greater implant stability and increase the volume of peri-implant newly formed bone, indicating that laser irradiation effected an improvement in the osseointegration process.

Histomorphometric assessment of the influence of low-level laser therapy on peri-implant tissue healing in the rabbit mandible.

OBJECTIVE: The purpose of this study was to demonstrate the effect of low-level laser therapy (LLLT) on the peri-implant bone healing process in the rabbit mandible. BACKGROUND DATA: LLLT has been shown to accelerate tissue repair and osseointegration of implants placed into the rabbit tibia. However, the beneficial effects of LLLT have never been tested in the rabbit mandible, which would more closely mimic the human situation. MATERIALS AND METHODS: Twenty-four male New Zealand rabbits were randomly divided into four groups of six animals each. All animals had their left mandibular incisors extracted, followed by immediate insertion of a titanium dental implant in the fresh socket. Three groups received LLLT [aluminum-gallium-arsenide (AlGaAs), λ=830nm, 50 mW, continuous wave (CW)] at three different energy densities per treatment session (E-5, 5 J/cm(2); E-10, 10 J/cm(2); and E-20, 20 J/cm(2)). Irradiation was performed every 48 h for 13 days, totaling seven sessions. One group received sham treatment (controls). Histological sections were obtained from each of the 24 mandibles dissected, without first decalcifying the specimens, and were stained with hematoxylin and eosin and Picrosirius red for histomorphometric evaluation. Bone-to-implant contact (BIC), bone formation area, and collagen fiber area were assessed by light microscopy. RESULTS: Significant differences were found between group E-20 and all other groups (p<0.05). Histomorphometric evaluation showed significantly higher BIC and significantly more collagen fibers in group E-20. CONCLUSIONS: Photobiostimulation with LLLT at an energy density of 20 J/cm(2) per session had a significant positive effect on new bone formation around dental implants inserted in the rabbit mandible.

Finite element analysis of masticatory stress on neoformed bone tissue after distraction osteogenesis and low-level laser therapy: a pilot study.

OBJECTIVE: This study aimed to understand the action of masticatory forces on an implant virtually introduced into the sheep mandible after distraction osteogenesis and low-level laser therapy (LLLT) by using finite element analysis. BACKGROUND DATA: Distraction osteogenesis as an alternative for bone reconstruction that may be used in the treatment of deformities. METHODS: Four ewes underwent distraction osteogenis to elongate the left mandibular body by 15 m, and three of them underwent LLLT with the purpose of improving bone properties. After death, animals were scanned by computed tomography and their mandibles were tridimensionally reconstructed by computer programs. The physical properties related to hardness and modulus of elasticity of each animal were obtained from the dissected mandibles, and data were transferred to Femap software for finite element analysis. RESULTS: Animals exposed and not exposed to LLLT irradiation showed remarkably similar values for superficial hardness and modulus of elasticity, without statistically significant difference (p>0.05), between the values observed for the cortical bone and the cancellous bone among the groups. The neoformed mandible, after a brief period for bone healing, was able to promote stability for implant placement and proper distribution of masticatory forces. CONCLUSIONS: An implant introduced virtually into the site of bone neoformation did not suffer any micromotions relevant to osteointegration. Furthermore, finite element analysis showed that the neoformed portion of the mandible was able to absorb and distribute masticatory forces throughout its structure, even after a brief period for bone maturation.

Systemic effects of LLLT on bone repair around PLLA-PGA screws in the rabbit tibia.

To evaluate the systemic effects of low level laser therapy (LLLT) on the early stages of bone repair after implantation of poly-L-lactic/polyglycolic acid (PLLA-PGA) screws 24 rabbits were randomly allocated to one of two groups, experiment or control. Each animal underwent implantation of one 5 × 1.5 mm PLLA-PGA screw in each tibia (right and left). The experiment group received infrared laser irradiation (830 nm, 4 J, 100 mW, 10.1 s) over the right paw immediately after implantation and every 48 h thereafter, for a maximum of seven sessions. The control group was not irradiated. Both groups were divided into three subgroups according to the observation period (5, 15, or 30 days), after which animals were euthanized. The results observed in the left paw of experimental animals were compared with the left paws of control animals. We also compared the right and left paws of experimental animals so as to compare local and potential systemic effects. Bone specimens were analyzed to assess the extent of peri-implant bone formation, quantitative analysis revealed greater bone formation in the left tibia of experimental animals as compared to controls on 5-day follow-up. Descriptive analysis revealed slightly larger and thicker trabeculae in the irradiated animals at 5 days post-procedure. There were no significant differences at any other point in time. As used in this study, LLLT had a positive systemic effect on the early stages of bone formation.

Effect of low-level laser therapy on incorporation of block allografts.

OBJECTIVE: To assess the effect of low-level laser therapy (LLLT) on the incorporation of deep-frozen block allografts in a rabbit model. BACKGROUND DATA: Studies have shown that LLLT has beneficial effects on tissue repair and new bone formation. METHODS: Bone tissue was harvested from two rabbits, processed by deep-freezing and grafted into the calvaria of 12 animals, which were then randomly allocated into two groups: experimental (L) and control (C). Rabbits in group L were irradiated with an aluminum gallium arsenide diode laser (AlGaAs; wavelength 830 nm, 4 J/cm(2)), applied to four sites on the calvaria, for a total dose of 16 J/cm(2) per session. The total treatment dose after eight sessions was 128 J/cm(2). Animals were euthanized at 35 (n = 6) or 70 days (n = 6) postoperatively. RESULTS: Deep-freeze-processed block allografts followed by LLLT showed incorporation at the graft-host interface, moderate bone remodeling, partial filling of osteocyte lacunae, less inflammatory infiltrate in the early postoperative period, and higher collagen deposition than the control group. CONCLUSION: Optical microscopy and scanning electron microscopy showed that allograft bone processed by deep-freezing plus LLLT is suitable as an alternative for the treatment of bone defects. Use of the deep-freezing method for processing of bone grafts preserves the structural and osteoconductive characteristics of bone tissue.

Assessment of marginal adaptation after apicoectomy and apical sealing with Nd:YAG laser.

OBJECTIVE: Recurrent periapical disease poses a substantial challenge to the dental practitioner. However, the use of novel methods and materials in periapical surgery has increased the success rates of treatment. The objective of this study was to assess the effects of mineral trioxide aggregate (MTA) retrofilling and apical sealing with Nd:YAG laser (at 10 Hz, 150 mJ, 1.5 W, in 60 sec pulses) as adjuncts to apicoectomy. METHODS: Perpendicular root end resection was performed with diamond-coated burs on 40 canine teeth previously subjected to endodontic treatment. Teeth were randomly allocated into four groups: group A, apicoectomy alone; group B, apicoectomy+Nd:YAG laser; group C, apicoectomy+MTA retrofilling; group D, apicoectomy+MTA retrofilling+Nd:YAG laser. Specimens were embedded in epoxy resin and sliced lengthwise and crosswise. RESULTS: Scanning electron microscopy (SEM) analysis showed more homogeneous and canaliculi-free apical surfaces in groups B and D (p<0.01). Marginal gaps between the dentin surface and filling material were observed in decreasing order of gap size in groups B, A, D, and C (p<0.01) for cross-sectional analysis. Energy-dispersive X-ray spectrometry (EDS) revealed greater phosphorus (p<0.01) and lower calcium (p<0.01) ion content in the Nd:YAG-irradiated groups. CONCLUSIONS: In this study, Nd:YAG laser irradiation had a positive effect on dentin surface sealing, despite an untoward dimensional effect when associated with MTA retrofilling.

Assessment for treatment of tripod fractures of the zygoma with microcompressive screws.

PURPOSE: The present prospective study sought to evaluate a new rigid internal fixation device called a "neck screw," which was applied to patients presenting with a tripod fracture of the zygomaticomaxillary complex. PATIENTS AND METHODS: Seventeen patients with tripod fractures received surgical treatment from 2007 to 2010, and had their zygomaticomaxillary complex monofragments fixed using the neck screw protocol. The adequacy of fracture reduction, stability of the zygomatic monofragment after fixation, cosmetic outcomes, and postoperative complications were used to determine the efficacy of this protocol. The stability provided by the neck screw was evaluated by computed tomography (CT) scans by comparing the immediate postoperative distances between the fractured bone segments (control group) with those distances measured on CT scans obtained 5 weeks later (late group). RESULTS: The average distance observed between the fractured ends on the immediate postoperative CT scan was less than 0.58 mm, demonstrating adequate fracture reduction. No significant changes were seen in these postoperative values after 5 weeks (Wilcoxon test, P = 1.0000), demonstrating no displacement of the zygomaticomaxillary complex monofragment after fixation using the neck screw. CONCLUSIONS: The proposed surgical treatment proved efficient in 17 patients. The fixation stability provided by the neck screw was confirmed by subsequent CT scan measurements, statistical analysis, and clinical follow-up during the postoperative period, in which patients showed no significant associated complications, facial asymmetry, enophthalmos, or diplopia.

Retinoblastoma and p53 protein expression in pre-malignant oral lesions and oral squamous cell carcinoma.

The retinoblastoma (Rb) and p53 genes play a fundamental role in cell cycle mechanisms, and their deregulation is related to many steps of oral cancer carcinogenesis. This study was conducted to evaluate the expression of the p53 and Rb proteins in malignant and pre-malignant oral cavity lesions. This retrospective study was conducted at the Federal University of Bahia, Salvador, Brazil, and the Molecular Biology Laboratory of the Otorhinolaryngology Department at the University of Heidelberg, Heidelberg, Germany. Excisional biopsy samples of oral cavities were collected from patients with suspected oral lesions. The samples were processed by immunohistochemistry to be classified by a semi-quantitative score: samples with a ≤ 10% positivity were considered to have weak/negative expression (-); those with 11-50% positivity, moderate expression (+); and those with >50% positivity, high expression (++). Seventy-one patients were studied (75% male; median age, 52 years; range, 24-84). Of the samples studied, 59.4% were oral squamous cell carcinoma (OSCC) and 40.6% were pre-neoplastic lesions (leukoplakia and actinic cheilitis). OSCC presented higher expression of Rb protein compared to pre-malignant lesions: 75 vs. 25% (p<0.001). Pre-neoplastic lesions presented higher expression of p53 protein compared to OSCC lesions: 55.2 vs. 44.8% (p = 0.030). Despite the small number of samples, the expression of these cell cycle biomarkers (p53 and Rb protein) in excisional biopsies suggests that molecular lesion assessment can determine pre-malignant lesions, and that its use may improve the clinical and surgical treatment of early lesions. Thus, p53 protein expression may be related to the early steps of carcinogenesis in OSCC. Finally, a higher Rb expression was also observed in malignant lesions.

A preliminary study of hardness and modulus of elasticity in sheep mandibles submitted to distraction osteogenesis and low-level laser therapy.

OBJECTIVES: To investigate the quality of newly formed bone in sheep mandibles submitted to distraction osteogenesis and low-level laser therapy (LLLT), based on hardness and modulus of elasticity values. The ideal moment for laser application (during the latency/activation period vs. during the bone consolidation period) was also evaluated. Computed tomography imaging was used to assess relapse as a result of early device removal. STUDY DESIGN: Extraoral distraction devices were placed in five sheep so as to achieve 1.5 cm of lengthened bone in 60 days. Distraction devices were removed 50, 40, and 33 days after surgery. Four animals were treated with LLLT, at different times, and one was used as control (no LLLT). RESULTS: When applied during the bone consolidation period, LLLT caused an increase in hardness and modulus of elasticity values. On the other hand, animals irradiated with LLLT during the latency/activation period presented a delay in bone healing. A period of consolidation of 13 days (early device removal) was associated with relapse. CONCLUSIONS: Nanoindentation tests were able to detect slight abnormalities in bone metabolism and proved to be important tools for the assessment of bone quality following distraction osteogenesis. LLLT provided increased benefits when applied during the bone consolidation period, once it promoted an increase in hardness and modulus of elasticity values. According to our results, the bone consolidation period should be of at least 3 weeks, so as to prevent relapse.

Histological and physical analysis of bone neoformation by osteogenesis distraction: A preliminary report.

INTRODUCTION: Osteogenesis distraction (OD) is a mainstream technique in maxillofacial surgical reconstruction with varied applications. OD technique employs a distractor with the aim to get new bone in the site of interest. Osseous maturation time is necessary before the device can be removed and few patients' complaint of related discomfort, especially when these devices are external, and induces superficial infections, paresthesia, hypertrophic scars and social relationship difficulties. The use of Low Level Laser Therapy (LLLT) has been proved beneficial to soft tissue and osseous repairs. MATERIALS AND METHOD: 12 rabbits were randomly divided in to two groups. In all animals, distractor was placed and one group was exposed to LLLT while the other group served as control. After consolidation, animals were sacrificed, the new bone formed were subjected to investigations including histomorphometric, physical analysis and tomographical analysis. Statistical analyses were performed using SPSS software. RESULT: Newly formed bone was significantly different between the groups. The physical properties of the neobone were comparatively better when the animals were exposed to LLLT with varying statistical significance. CONCLUSION: The results obtained with smaller sample size in this study need to be interpreted with care. The results of this preliminary pilot study encourage the use of LLLT during healing period. However the histological, tomographical and physical findings need to be ascertained using a larger sample size to study the bio-stimulatory effects with laser therapy from basics to clinical relevance on wound and bone healing.

Transference of virtual planning and planning over biomedical prototypes for dental implant placement using guided surgery.

OBJECTIVES: This study evaluated the transference of virtual planning and planning over biomedical prototypes for dental implant placement using guided surgery. MATERIAL AND METHODS: This experiment was conducted with 11 identical replicas of a human edentulous mandible. For each mandible, models and surgical guides were manufactured using stereolithography. Simulated surgeries were performed on the prototypes. Following this, the implants were placed in the mandible replicas. Superposition of the tridimensional pre- and postoperative models was used for virtual evaluation. The real evaluation was conducted by linear measurements directly on the models. RESULTS: The variations in angles and distances between the coronal, central and apical regions of the 22 implants evaluated in this study had mean values <1.45 degrees and 0.41 mm. The correlations between the positions of implant beds in each mandible were fair to very good, according to the distance analyzed and the interpretation guidelines used. CONCLUSIONS: According to the results of this study, the variations found in the transference of dental implant positioning to the operative field, determined during virtual planning and obtained in surgeries simulated with biomedical prototypes, confirm the reliability of guided surgery techniques in implantology.

Effects of low-level laser therapy on bone formed after distraction osteogenesis.

This study evaluated the effect of low-level laser therapy (LLLT) on the chemical composition, crystallinity and crystalline structure of bone at the site of distraction osteogenesis. Five rabbits were subjected to distraction osteogenesis (latency = 3 days; rate and frequency = 0.7 mm/day for 7 days; consolidation = 10 days), and three were given LLLT with arsenide-gallium-aluminum (AsGaAl; 830 nm, 40 mW): 10 J/cm(2) dose per spot, applied directly to the distraction osteogenesis site during the consolidation stage at 48 h intervals. Samples were harvested at the end of the consolidation stage. X-ray fluorescence and X-ray diffraction were used to analyze chemical composition, crystallinity and crystalline structure of bone at the distraction osteogenesis site. The analysis of chemical composition and calcium (Ca) and phosphorus (P) ratios revealed greater mineralization in the LLLT group. Diffractograms showed that the crystalline structure of the samples was similar to that of hydroxyapatites. Crystallinity percentages were greater in rabbits that were given LLLT. Crystallinity (41.14% to 54.57%) and the chemical composition of the bone at the distraction osteogenesis site were similar to the that of the control group (42.37% to 49.29%). The results showed that LLLT had a positive effect on the biomodulation of newly formed bone.

Histological evaluation of the effect of low-level laser on distraction osteogenesis in rabbit mandibles.

OBJECTIVES: This study evaluated the action of low level laser therapy (LLLT) on the percentage of newly formed bone in rabbit mandibles that underwent distraction osteogenesis (DO). STUDY DESIGN: Ten rabbits underwent bone lengthening according to the following protocol: Latency - 3 days; Activation - 7 days 0.7 mm/d; and Consolidation - 10 days. The control group was composed of 4 rabbits. The experimental group, composed of 6 rabbits, received infrared GaAlAs LLLT (wavelength=830 nm, P=40 mW) according to the following protocol: point dose of 10 J/cm(2) applied directly on the bone site that underwent DO during bone consolidation at 48-hour intervals. RESULTS: The percentage of newly formed bone was greater in the LLLT group (57.89%) than in the control group (46.75%) (p=0.006). CONCLUSION: The results suggest that LLLT had a positive effect on the percentage of newly formed bone. Better-quality bone sites may allow early removal of the osteogenic distractors, thus shortening total treatment time.

Low-level laser therapy for implants without initial stability.

OBJECTIVE: This study evaluated the effect of low-level infrared laser on removal torque values of implants with poor initial stability inserted in rabbit tibias. BACKGROUND DATA: It is important to analyze the effects of laser radiation on bone repair when low-quality bone and implants with poor initial stability are used. MATERIALS AND METHODS: Thirty male white New Zealand rabbits (Oryctolagus Cuniculus) about 2 mo old and weighing 1.5-2.0 kg were used. Machined implants with poor initial stability were inserted in the tibia of each animal. Animals were randomly divided into two groups: laser irradiated and laser nonirradiated. Each group was further divided into three subgroups, according to the day the animals were killed: 15, 30, or 45 d. Torque values were measured with an axial digital torquemeter that applied counter-torque. The Student's t-test was used to calculate means and standard deviations for the comparisons between laser and control groups. RESULTS: A significant increase (p = 0.050) in removal torque values was found in the group of laser-irradiated implants at 15 and 30 d when compared with the control groups. At 45 d, no significant differences were found. CONCLUSION: In this study, low-level laser therapy promoted the osseointegration of implants with poor initial stability, particularly in the initial stages of bone healing.

Analysis of the systemic effect of red and infrared laser therapy on wound repair.

OBJECTIVE: To evaluate, using histological analysis, the systemic action and repair process of wounds produced on the back of rats and treated with red, infrared, or both lasers applied directly or indirectly to the wounds. BACKGROUND DATA: Skin tissue repair and wound healing are complex processes that involve a series of dynamic events. Many benefits are associated with biomodulation using laser therapy. METHODS: Thirty-six male Wistar rats were divided into four groups: control (without laser), red laser (aluminium gallium indium phosphide (AlGaInP); lambda=685 nm; phi=0.0314 cm2; CW; P=30 mW; D=20 J, time of irradiation=667 sec), infrared laser (gallium-aluminum-arsenide (GaAlAs): lambda=830 nm; phi=0.0314 cm2; CW; P=50 mW; D=20 J, time of irradiation=401 sec), and both lasers (infrared laser: GaAlAs; lambda=830 nm; phi=0.0314 cm2; CW; P=50 mW; D=10 J, time of irradiation=201 sec+red laser: AlGaInP; lambda=685 nm; phi=0.0314 cm2; CW; P=30 mW; D=10 J, time of irradiation=334 sec; total dose=20 J). Three subgroups were formed according to observation time points. Three wounds were produced on the back of each animal. Only the wound closest to the head was irradiated in the experimental groups. For the evaluation of skin reaction and wound healing, three animals of each group were killed at 3, 5, and 7 days postoperatively. The irradiation protocol established 48-hour intervals between applications, with the first application immediately after the surgical procedure. RESULTS: In the red and infrared laser group, healing was more advanced in the wound located furthest from the point of laser application. The most effective healing of a proximal wound was verified in the control group on the 7th postoperative day. CONCLUSION: The combined application of red and infrared lasers resulted in the most evident systemic effect on the repair of skin wounds produced in rats.

Effects of diode laser therapy on the acellular dermal matrix.

Acellular dermal matrix (ADM) was subcutaneously implanted into calvarian skin of male Wistar rats (n = 40). Low-level laser (lambda 685 nm, 4 J/cm(2)) was locally applied in experimental group (n = 20) above the skin flap. Grafts were harvested at 1, 3, 7 and 14 days after surgery and underwent histological analyses. In treated animals, the extent of edema and the number of inflammatory cells were reduced (P < 0.05). The amount of collagen in graft treated with low-level laser were significantly higher than those of controls (P < 0.05) and were statistically more prominent on the 14th day after surgery. The mean count of fibroblasts was significantly higher in the low-laser therapy group within the 3rd day, showing a marked influx of fibroblasts into area. In conclusion, wound healing of the ADM appear to be positively affected by laser therapy.

Is 3D-CT reformation using free software applicable to diagnosis of bone changes in mandibular condyles?

OBJECTIVES: This study evaluated the agreement of computed tomography (CT) imaging using 3D reformations (3DR) with shaded surface display (SSD) and maximum intensity projection (MIP) in the diagnosis of bone changes in mandibular condyles of patients with rheumatoid arthritis (RA), and compared findings with multiplanar reformation (MPR) images, used as the criterion standard. MATERIAL AND METHODS: Axial CT images of 44 temporomandibular joints (TMJs) of 22 patients with RA were used. Images were recorded in DICOM format and assessed using free software (ImageJ). Each sample had its 3DR-SSD and 3DR-MIP results compared in pairs with the MPR results. RESULTS: Slight agreement (k = 0.0374) was found in almost all comparisons. The level of agreement showed that 3DR-SSD and 3DR-MIP yielded a number of false-negative results that was statistically significant when compared with MPR. CONCLUSIONS: 3DR-SSD or 3DR-MIP should only be used as adjuvant techniques to MPR in the diagnosis of bone changes in mandibular condyles.

Parent and caretaker knowledge about avulsion of permanent teeth.

Traumatic dentoalveolar injuries are frequent in children and adolescents, affecting teeth, their supporting structures and adjacent soft tissues and contributing to the appearance of major psychosocial and economic problems. Tooth avulsion, the most severe dentoalveolar lesion, is a dental emergency. The prognosis of avulsed teeth significantly depends on prompt and efficient action at the site of the accident, thus requiring that parents or caretakers be knowledgeable about the correct management of this situation. The objective of the present study was to assess the level of knowledge of parents or caretakers concerning the management of tooth avulsion and to investigate the association between level of knowledge and schooling, monthly family income and age. We interviewed 107 parents or caretakers using a 12-item questionnaire comprising objective questions whose answers received a score from 0 to 3. The results show that 99% of those interviewed would immediately seek professional help; however, 71% did not know what avulsion was. Only 3% would use milk as storage medium and 16% would attempt replantation of the avulsed tooth. The distribution of final means for the overall level of parent or caretaker knowledge was 44.63% for score 3, 15.88% for score 2, 17.99% for score 1 and 21.47% for score 0, showing a low level of knowledge concerning tooth avulsion. Schooling, monthly family income and age were not associated with the knowledge scores for any of the 12 questions. The level of parent and caretaker knowledge concerning the management of tooth avulsion is low, without association with age, schooling and monthly family income.

Marginal adaptation of root-end filling materials: an in vitro study with teeth and replicas.

AIM: The purpose of this investigation was to evaluate the marginal adaptation of five root-end filling materials. METHODS AND MATERIALS: Fifty human single-rooted teeth were resected 3 mm from the apex. Root-end cavities were then prepared using an ultrasonic tip and filled with one of the following materials: silver amalgam without zinc, white MTA-Angelus, white Portland cement (PC), Vitremer, and GC Fuji Ortho LC. The apical portion of the roots was then sectioned to obtain two 1 mm thick transversal sections. Epoxy resin replicas of these apical sections were fabricated for an analysis of marginal adaptation. Scanning electron microscopy (SEM) was used to determine gaps in the adaptation of the root-end filling materials at the interface between them and the dentin. The Kruskal-Wallis test and a multiple comparison test were used for statistical data analysis. The Spearman correlation coefficient was used to determine the correlation between the results found for teeth and replicas. RESULTS: Materials containing calcium oxide (MTA and PC) showed similar results. Resin modified glass ionomer cements (GICs) presented similar variations in marginal adaptation, but Vitremer showed significantly greater marginal adaptation when compared to GC Fuji Ortho LC. CONCLUSION: A positive and significant correlation was observed between marginal adaptation values found in the teeth and their replicas. CLINICAL SIGNIFICANCE: The use of ionomers as root-end filling materials may improve clinical outcomes in periradicular surgery.

Effect of low-level laser therapy after implantation of poly-L-lactic/polyglycolic acid in the femurs of rats.

This study evaluated the use of red and infrared lasers on tissue surrounding the femurs of 60 rats randomly divided into three groups after implantation of bioabsorbable plates. The control group were not subjected to laser irradiation; group A was treated with red laser [indium-gallium-aluminum-phosphide (InGaAlP) laser, wavelength 685 nm, 35 mW, continuous wave (CW), Ø = 0.06 cm, 2.23 min], and group B was subjected to infrared laser [gallium-aluminum-arsenium (GaAlAs) laser, wavelength 830 nm, 50 mw, CW, Ø = 0.06 cm, 1.41 min], both at 10 J/cm(2). Samples were stained with hematoxylin and eosin (H&E) and examined microscopically. Results showed that the laser irradiation had had a positive photobiomodulation effect on inflammation, confirmed by a better histologic pattern than that of the control group at 3 days and 7 days. Semiquantitative analysis revealed that groups A and B had a histologic score significantly greater than that of the control group at 3 days. At 21 days, histomorphometric analysis revealed a more intense inflammation in the red laser group than in the other groups. We concluded that low-level laser therapy (LLLT) has positive effects on the photobiomodulation of inflammation in the tissues surrounding the poly-L-lactic/polyglycolic acid (PLLA/PGA) bioabsorbable plate. It stimulated vascularization, fibroblast proliferation, and collagen deposition.