Deise Ponzoni

Histological evaluation of the influence of magnetic field application in autogenous bone grafts in rats

BackgroundBone grafts are widely used in oral and maxillofacial reconstruction. The influence of electromagnetic fields and magnets on the endogenous stimulation of target tissues has been investigated. This work aimed to assess the quality of bone healing in surgical cavities filled with autogenous bone grafts, under the influence of a permanent magnetic field produced by in vivo buried devices.MethodsMetal devices consisting of commercially pure martensitic stainless steel washers and titanium screws were employed. Thirty male Wistar rats were divided into 3 experimental and 3 control groups. A surgical bone cavity was produced on the right femur, and a bone graft was collected and placed in each hole. Two metallic washers, magnetized in the experimental group but not in the control group, were attached on the borders of the cavity.ResultsThe animals were sacrificed on postoperative days 15, 45 and 60. The histological analysis of control and experimental samples showed adequate integration of the bone grafts, with intense bone neoformation. On days 45 and 60, a continued influence of the magnetic field on the surgical cavity and on the bone graft was observed in samples from the experimental group.ConclusionThe results showed intense bone neoformation in the experimental group as compared to control animals. The intense extra-cortical bone neoformation observed suggests that the osteoconductor condition of the graft may be more susceptible to stimulation, when submitted to a magnetic field.

Histological analysis of the effects of a static magnetic field on bone healing process in rat femurs

BackgroundThe aim of this study was to investigate, in vivo, the quality of bone healing under the effect of a static magnetic field, arranged inside the body.MethodsA metallic device was developed, consisting of two stainless steel washers attached to the bone structure with titanium screws. Twenty-one Wistar rats (Rattus novergicus albinus) were used in this randomized experimental study. Each experimental group had five rats, and two animals were included as control for each of the groups. A pair of metal device was attached to the left femur of each animal, lightly touching a surgically created bone cavity. In the experimental groups, washers were placed in that way that they allowed mutual attraction forces. In the control group, surgery was performed but washers, screws or instruments were not magnetized. The animals were sacrificed 15, 45 and 60 days later, and the samples were submitted to histological analysis.ResultsOn days 15 and 45 after the surgical procedure, bone healing was more effective in the experimental group as compared to control animals. Sixty days after the surgical procedure, marked bone neoformation was observed in the test group, suggesting the existence of continued magnetic stimulation during the experiment.ConclusionThe magnetic stainless steel device, buried in the bone, in vivo, resulted in increased efficiency of the experimental bone healing process.

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 improves peri-implant bone formation: resonance frequency, electron microscopy, and stereology findings in a rabbit model

Previous studies have reported positive effects of low-level laser therapy (LLLT) on bone healing. This study evaluated the effects of LLLT on peri-implant healing in vivo. Thirty-two rabbits had their mandibular left incisors removed, followed by immediate insertion of a dental implant into the fresh socket. Animals were assigned randomly to four groups: control (non-irradiated) or LLLT at three different doses per session: 5J/cm(2), 10J/cm(2), and 20J/cm(2). A GaAlAs laser (830nm, 50mW) was applied every 48h for 13 days, starting immediately after surgery. The implant stability quotient (ISQ) was measured using resonance frequency analysis upon implant insertion and immediately after death, 30 days after the last application. Tissues were prepared for scanning electron microscopy (SEM) and stereology. Variables measured were bone-implant contact (BIC) and bone neoformation within implant threads at three different sites. The results showed better ISQ for the 20J/cm(2) group (P=0.003). BIC values were significantly higher (P<0.05) in the 20J/cm(2) group, on both SEM and stereology. Bone area values were better in the 10J/cm(2) (P=0.036) and 20J/cm(2) (P=0.016) groups compared to the control group. Under these conditions, LLLT enhanced peri-implant bone repair, improving stability, BIC, and bone neoformation. The findings support and suggest parameters for the design of clinical trials using LLLT after implant placement.

Characterization of bone repair in rat femur after treatment with calcium phosphate cement and autogenous bone graft

BackgroundIn this study, the biocompatibility, stability and osteotransductivity of a new cement based on alpha-tricalcium phosphate (alpha-TCP) were investigated in a bone repair model using a rat model.MethodsThe potential of alpha-TCP on bone repair was compared to autogenous bone grafting, and unfilled cavities were used as negative control. Surgical cavities were prepared and designated as test (T), implanted with alpha-TCP blocks; negative control (C - ), unfilled; and positive control (C + ), implanted with autogenous bone graft. Results were analyzed on postoperative days three, seven, 14, 21 and 60.ResultsThe histological analyses showed the following results. Postoperative day three: presence of inflammatory infiltrate, erythrocytes and proliferating fibroblasts in T, C - and C + samples. Day seven: extensive bone neoformation in groups T and C + , and beginning of alpha-TCP resorption by phagocytic cells. Days 14 and 21: osteoblastic activity in the three types of cavities. Day 60: In all samples, neoformed bone similar to surrounding bone. Moderate interruption on the ostectomized cortical bone.ConclusionsBone neoformation is seen seven days after implantation of alpha-TCP and autogenous bone. Comparison of C - with T and C + samples showed that repair is faster in implanted cavities; on day 60, control groups presented almost complete bone repair. Alpha-TCP cement presents biocompatibility and osteotransductivity, besides stability, but 60 days after surgery the cavities were not closed.

Clinical management of angioneurotic oedema patient post-orthognathic surgery

Angioneurotic oedema is an acute swelling involving the submucosal or subcutaneous tissues; it is most often located in the oral and maxillofacial region, which can result in upper airway obstruction. Its aetiology is frequently associated with immunoglobulin-mediated hypersensitivity reactions that elicit a heightened inflammatory response. The objective of this study was to report the case of a patient who developed an episode of angioneurotic oedema following combined orthognathic surgery. Pharmacological and nonpharmacological interventions used in the treatment of this important clinical condition are described and discussed.

Nitrogen-containing bisphosphonate therapy: assessment of the alveolar bone structure in rats – a blind randomized controlled trial

This study aimed to assess the effect of zoledronic acid exposure on structures of the alveolar bone of rats. The sample was composed of 42 male Wistar rats. Animals in the T1 and T2 groups received weekly doses of 0.2 mg/kg intraperitoneal zoledronic acid for 3 weeks, while animals in the T3 group received the same treatment for 8 weeks. The control groups C1, C2 and C3 received equivalent doses of saline. The first upper molars of Wistar rats in the C2, T2, C3 and T3 groups were extracted. Cone‐beam computerized tomography scans were performed, and the image density was analysed by grey levels. The presence and type of inflammatory infiltrate, vascularization and bone necrosis were assigned by histological qualitative scores. Histomorphometric analysis of bone density was performed in the groups without extraction. No significant differences were found in the bone grey density estimated by grey‐level value and histomorphometric analysis between the C1 and T1 groups (P > 0.05). The grey levels in the T3 group were lower (P < 0.05) than in the C3 group, corresponding to the bone defect. Histological assessments showed the presence of bone necrosis in the T3 group and lower levels of bone remodelling in the test groups (T2 and T3) compared to the control groups (C2 and C3). The results of qualitative analyses did not differ significantly between the groups (P > 0.05). Zoledronic acid‐exposed animals showed maxillary changes including reduced grey levels, the presence of bone necrosis and a higher prevalence of inflammatory signs.

HAIRY POLYP on the dorsum of the tongue – detection and comprehension of its possible dinamics

BackgroundThe formation of a Hairy Polyp on the dorsum of the tongue is a rare condition that may hinder vital functions such as swallowing and breathing due to mechanical obstruction. The authors present the situation on a child with an approach of significant academic value.MethodsImaging diagnostics with the application of a topical oral radiocontrastant was used to determine the extent of the tumor. Performed treatment was complete excision and diagnostics was confirmed with anatomopathological analysis.ResultsThe patient was controlled for five months and, showing no signs of relapse, was considered free from the lesion.ConclusionAccurate diagnostics of such a lesion must be performed in depth so that proper surgical treatment may be performed. The imaging method proposed has permitted the visualization of the tumoral insertion and volume, as well as the comprehension of its threatening dynamics.

Intramuscular 30% polymethylmethacrylate (PMMA) implants in a non-protein vehicle: an experimental study in rats

INTRODUCTION: In the present study, the stability and biocompatibility of a 30% polymethylmethacrylate (PMMA) filling material implanted in the masseter muscle of rats were investigated according to the cytologic characteristics presented in the graft versus host reaction. METHODS: The study included 20 rats, which were divided into 4 groups: groups I, II, III, and IV corresponded to animals evaluated 7, 14, 45, and 60 days after surgery, respectively. The implant was placed in the right masseter muscle at the level of the mandibular angle. RESULTS: After 7 days, lymphoplasmacytic inflammatory infiltrates, a fibrous capsule, a large number of neutrophils, macrophages, and exudate were observed. The second group (14 days) showed granulation tissue composed of a lymphoplasmacytic inflammatory infiltrate, newly formed vessels, and a fibrous capsule. However, the second group also exhibited regeneration of the muscle fibers, and a decreased number of neutrophils and exudate. After 45 and 60 days, the inflammatory infiltrate decreased in intensity compared to the first 2 groups. CONCLUSIONS: The inflammatory reaction caused by PMMA is transient and does not compromise the function and the shape of the masseter muscle tissue, suggesting that PMMA is biocompatible.

Alterações pós-anestésicas do hematócrito em cirurgias ortognáticas

BACKGROUND AND OBJECTIVES Blood transfusions have been heavily questioned due to the increased number of transfusion-transmitted diseases This study aimed at evaluating perioperative blood loss and hematocrit recovery in 14 days, in patients submitted to orthognathic surgery under induced hypotensive anesthesia, with three different volume replacement techniques. METHODS This was a prospective study of consecutive patients submitted to orthognathic surgery in the period August 1985 to July 2003. Patients were distributed in three groups: group I with pre-operative self-donation of blood 7 days before surgery; group II with intraoperative self-donation; and group III with normovolemic hemodilution. Pre-medication, induction, maintenance, drugs and monitoring were standardized. Patients were submitted to induced hypotensive general anesthesia. The following data were evaluated: blood loss, anesthetic length, systolic, diastolic and mean blood pressure, heart rate, hematocrit and hemoglobin at pre-induction, 60 hours after the first sample and at 14th the postoperative day, as well as perioperative complications. RESULTS Blood loss was 1340.03 +/- 427.97 in group I; 1098.08 +/- 429.30 in group II; and 1044.71 +/- 526.56 in group III, with statistical significance in group I as compared to groups II and III. There was significant decrease in pre-induction hemoglobin as compared to 60 hours and 83% hematocrit recovery in 14 days. CONCLUSIONS Perioperative blood loss for all groups was high, with need for allogeneic blood transfusion. Virtually all patients have tolerated blood loss since in general they were young patients, physical status ASA I and II without associated diseases. Hematocrit has not returned to preoperative values after 14 days.JUSTIFICATIVA E OBJETIVOS: Com o aumento de doencas transmissiveis atraves das transfusoes sanguineas, as suas indicacoes estao sendo muito questionadas. Os objetivos deste trabalho sao avaliar a perda sanguinea peri-operatoria, e a recuperacao do hematocrito apos 14 dias, em pacientes submetidos a cirurgia ortognatica, realizada sob anestesia geral e hipotensao controlada, com tres diferentes tecnicas de reposicao volemica. METODO: Foi realizado um estudo prospectivo em pacientes submetidos consecutivamente a cirurgia ortognatica, no periodo entre agosto de 1985 a julho de 2003. Os pacientes foram divididos em tres grupos; grupo I, com autodoacao previa de 7 dias; grupo II, com autodoacao intra-operatoria; e grupo III, com hemodiluicao normovolemica. A medicacao pre-anestesica, a inducao, a manutencao, os farmacos e a monitorizacao foram padronizados. Os pacientes foram submetidos a anestesia geral com hipotensao arterial induzida e controlada. Foram analisados a perda sanguinea, o tempo anestesico, as pressoes sistolica, diastolica e media, a frequencia cardiaca, o hematocrito e a hemoglobina antes da inducao anestesica, e o hematocrito e a hemoglobina apos 60 horas e 14 dias do pos-operatorio bem como as complicacoes peri-operatorias. RESULTADOS: A perda sanguinea foi de 1340,03 ± 427,97 no grupo I; 1098,08 ± 429,30 no grupo II; e 1044,71 ± 526,56 no grupo III, com diferenca estatistica significativa no grupo I em relacao aos grupos II e III. Houve diminuicao significativa do hematocrito antes da inducao da anestesia (24%), comparado aos resultados obtidos em 60 horas, e restauracao de 83% do hematocrito, em 14 dias. CONCLUSOES: A perda sanguinea peri-operatoria nos tres grupos foi consideravel, com minima necessidade de transfusao de sangue alogenico. A quase totalidade dos pacientes tolerou a perda sanguinea, pois eram em geral jovens, estado fisico ASA I e II e sem grande comorbidade associada. O hematocrito em 14 dias nao recuperou o valor pre-operatorio.