Henrique Duque de Miranda Chaves Netto

Mineralized Tissue Formation Associated With 2 Different Dental Implant Designs: Histomorphometric Analyses Performed in Dogs

The clinical success of dental implants might be associated with such factors as installation technique, implant shape, size, material, and screw threads. Therefore, the aim of this study is to analyze mineralized tissue formation on the screw threads of conical and cylindrical dental implants. This study includes 7 beagle dogs that had the lower premolars extracted. Three months after bone and soft tissue repair, 2 different designs of dental implants (1 conical and 1 cylindrical) were installed in each hemimandible using a nonsubmerged technique. Both implants when installed had different shape and thread, as revealed by scanning electron microscopy. Six weeks after implant installation, animals were killed and submitted to histomorphometric analysis. Cervical, middle, and apical areas were analyzed. Statistical analysis was carried out using Student t test at a significance level of P < .05. Statistically significant differences were not found between the conical and cylindrical implants. The conical implants presented fewer threads, a smaller area, and more bone formation when compared with the cylindrical ones, without significant differences (P  =  .1226). The highest values concerning bone formation were observed for the cervical area (P  =  .4005), and the lowest for the apical area (P  =  .1899); however, no statistically significant difference was observed. In conclusion, no statistically significant difference was observed in thread bone formation between the cylindrical and conical implant designs when placed using the nonsubmerged technique.

Análisis Histológico del Proceso de Reparación en Defectos Óseos: Reconocimiento de Defectos Críticos

Los procedimientos quirurgicos que envuelven la rehabilitacion de la region maxilofacial requieren frecuentemente el uso de injertos para la reconstruccion de de deformidades congenitas o adquiridas. De esta forma, defectos oseos pueden clasificarse como criticos o no criticos. En esta investigacion fueron utilizados 6 canes machos realizando 2 defectos bicorticales de 8mm de diametro en la calota craneal de cada animal; el relleno de las cavidades se realizo como grupo 1 con coagulo sanguineo y grupo 2 con hueso autogeno en particulas. A traves de un an analisis histologico descriptivo se observo en el periodo de tres semanas de sacrificio que el grupo 2 fue el unico en presentar regiones de aposicion de nuevo tejido oseo. En el periodo de 6 semanas el grupo 2 presento particulas de hueso autogeno utilizadas para el relleno en estado de reabsorcion avanzada en ausencia de los bordes nitidos entre el defecto y el hueso preexistente. De este modo se concluye que el metodo que auxilie en el proceso de reparacion tecidual como los injertos oseos autogenos, estan indicados en la recuperacion de defectos criticos, iguales o mayores que 8mm.

In vitro resistance of titanium and resorbable (poly L-co-DL lactic acid) osteosynthesis in mandibular body fracture.

This study was a comparative evaluation of the bending resistance of metallic and resorbable plates and screws in a mandibular body fracture model. Forty polyurethane synthetic hemimandibles were used; a vertical linear cut was made between the second and first premolars. These 40 hemimandibles were divided into four groups of 10 and were fixed with titanium plates and screws or resorbable plates and screws, with monocortical screws in the upper sector and bicortical screws in the lower sector. Bending resistance tests were done on a universal testing machine with a linear displacement speed of 1mm/min, a cell load of 500 N, and a load cell on the lower central incisor or on the lower second premolar. Results were analyzed using the Students t-test, with the significance level set at 5%. No statistically significant differences were observed between the groups studied, either in the analysis of the osteosynthesis materials or related to the load-bearing points. The variables of displacement and peak load did not present any significant differences. In this in vitro model of a mandibular body fracture, the mechanical behaviour of a resorbable osteosynthesis was similar to that of a titanium osteosynthesis.

Retrospective study of the survival and associated risk factors of wedge-shaped implants.

PURPOSE To assess the long-term behavior of wedge-shaped implants and evaluate the influence of the associated risk factors on implant survival rates. MATERIALS AND METHODS A retrospective review of clinical records of patients treated with wedge-shaped implants between 1992 and 2011 was conducted. Data on patient sex, age, smoking habits, and history of periodontitis; details of implant length, diameter, angle, and location; and data on surgical, reconstructive, and prosthetic procedures, and systemic disease were selected for analysis. RESULTS A total of 1,169 implants placed in 154 patients (mean age 55.17 ± 11.33 years) were evaluated. Women received 637 implants, and men received 532 implants; 60.4% were placed in patients who were undergoing periodontal maintenance care, 17.9% in smokers, 17.7% in hypertensive patients, 5.7% in diabetic patients, and 4.4% in cardiac patients. The mean overall survival for implants was 194.26 ± 9.91 months. Seventy-three implants were lost: 3 before implant loading and 70 after loading. The cumulative survival rates at 5 and 10 years were 96.6% (confidence interval [CI]: 95.5% to 97.7%) and 91.8% (CI: 90.1% to 94.1%), respectively. Univariate analysis indicated tobacco smoking (P = .014) and implant location (P < .001) as significant risk factors for implant failure. The multivariate analysis showed tobacco smoking (P = .016), location (P = .001), and male sex (P = .038) as significant, and the latter factor was associated with previous periodontal disease. CONCLUSIONS Overall survival of the wedge-shaped implant showed good long-term results. Male sex, tobacco smoking, and posterior maxillary location were associated with a greater risk of implant failure.

Bifosfonatos y Osteonecrosis de los Maxilares: Consideraciones Sobre su Tratamiento

Los bifosfonatos son potentes inhibidores de los osteoclastos, son drogas usadas principalmente para el tratamiento de mieloma multiple y en metastasis oseas de tumores solidos como el cancer de mama. En el ano 2003 fue relatado el primer caso de osteonecrosis de los maxilares (ONM) asociado al uso de bifosfonatos, sin embargo aun no se ha establecido una relacion causa efecto de estas drogas sobre la ONM. La incidencia en tiempos anteriores en relacion al uso de bifosfonatos era muy baja, siendo que hoy dia alcanza 10% o mas en las patologias mencionadas tratadas con estas drogas. Este articulo tiene por objetivo alertar sobre una posible complicacion en pacientes que hacen uso de bifosfonatos, a traves de la revision de la literatura y la presentacion de un caso clinico.

Regeneración Ósea en Defectos Críticos Tratados con Matriz Ósea Bovina Inorgánica Aplicada con dos Diferentes Vehículos

Multiples materiales se han utilizado en la reconstruccion osea; la matriz osea bovina ha sido ampliamente estudiada y aun existen investigaciones que identifican su capacidad de contribuir en la formacion osea. El objetivo de esta investigacion fue establecer la reparacion osea en defectos criticos de calotas de perros rellenados con matriz osea bovina inorganica transportada con carboxi-metil-celulosa. Se diseno un estudio experimental en 6 perros donde se realizaron 3 defectos de 8mm de diametro en los parietales de cada animal; el defecto fue rellenado aleatoriamente con hueso autogeno particulado (grupo I), matriz osea bovina inorganica con suero fisiologico al 0,9% (grupo II) y matriz osea bovina con carboxi-metil-celulosa (grupo III). Se realizo el sacrificio de los animales a la tercera y sexta semana momento en el que se realizaron los estudios radiograficos de los defectos tratados y los estudios histologicos de rutina con tinciones de hematoxilina-eosina. No se observo procesos infecciosos vinculados a los materiales injertados. En el grupo del hueso autogeno se observo una adecuada aposicion osea en la tercera y sexta semana junto a una relacion correcta con la imagen radiografica; en el grupo II se observo etapas de formacion osea y permanencia de los fragmentos de hueso injertado; en el grupo III se observo infiltrado inflamatorio en los dos periodos de sacrificio, abundante tejido conectivo y bajo nivel de formacion osea. Las radiografias de los grupos II y III mostraron signos de formacion osea que en la histologia eran solo remanentes del material injertado. Se concluye que la matriz osea bovina inorganica es compatible con el tejido oseo y que puede contribuir a la formacion osea aunque el empleo de la carboxi-metil-celulosa, como vehiculo, podria obstaculizar la regeneracion osea.

Comparison of Bone Graft Healing Between Autogenous Bone, Blood Clot and Anorganic Bovine Bone Matrix: Radiographic and Histological Analyses

Los procedimientos que envuelven la rehabilitacion de la region maxilofacial frecuentemente requieren el uso de injertos oseos. El seguimiento de la evolucion del injerto oseo frecuentemente es realizado con analisis clinico y especialmente a traves de estudios de imagenes, aunque pocos estudios han correlacionado ambos. El objetivo de esta investigacion fue establecer la relacion entre radiografias y las etapas de la reparacion osea en defectos creados con hueso autogeno, coagulo sanguineo y matriz osea de hueso bovino. Tres defectos de 8 mm de diametro fueron realizados en el parietal de 6 perros adultos, escogiendo el injerto seleccionado para cada defecto; 3 y 6 semanas despues fueron realizados los estudios histologicos y radiograficos. Los resultados mostraron que el hueso autogeno y el coagulo sanguineo presentaron semejanzas en los analisis histologico y radiografico; para el hueso bovino se observo areas decritas como hueso en la radiografia mientras realmente fueron particulas de hueso heterogeno descritas en el analisis histologico. Concluimos que el test radiografico puede ser usado como parametro para la reconstruccion y seguimiento preferentemente cuando es usado el injerto autogeno.

Bone Formation in Maxillary Sinus Lift Using Autogenous Bone Graft at 2 and 6 Months

The aim of this study is to compare the bone formation in maxillary sinus lift with an autogenous bone graft in histological evaluation at 2 or 6 months. A comparative study was designed where 10 patients with missing teeth bilaterally in the posterior zone of the maxilla were selected. Patients received a particulate autogenous bone graft under the same surgical conditions, selecting a site to collect a biopsy and histological study at two months and another at six months postoperatively. Histomorphometry was performed and were used Kolmogorov-Smirnov test, students t-test and Spearmans correlation coefficient, considering a value of p<0.05. Differences were observed in inflammatory infiltrate and vascularization characteristics; however, the group analyzed at two months presented 38.12% ± 6.64 % of mineralized tissue, whereas the group studied at 6 months presented an average of 38.45 ± 9.27 %. There were no statistical differences between the groups. It is concluded that the bone formation may be similar in intrasinus particulate autogenous bone grafts in evaluations at two or six months; under these conditions, early installation of implants is viable.

Survival in patients with oral and maxillofacial diffuse large B-cell lymphoma

The purpose of this study was to determine the survival and prognostic factors of patients with diffuse large B-cell lymphoma (DLBCL) of the oral cavity and maxillofacial region. Retrospectively, the clinical records of patients with a primary diagnosis of DLBCL of the oral cavity and maxillofacial region treated at the A.C. Camargo Hospital for Cancer, São Paulo, Brazil, between January 1980 and December 2005 were evaluated to determine (A) overall survival (OS) at 2 and 5 years and the individual survival percentage for each possible prognostic factor by means of the actuarial technique (also known as mortality tables), and the Kaplan Meier product limit method (which provided the survival value curves for each possible prognostic factor); (B) prognostic factors subject to univariate evaluation with the log-rank test (also known as Mantel-Cox), and multivariate analysis with Coxs regression model (all the variables together). The data were considered significant at p≤0.05. From 1980 to 2005, 3513 new cases of lymphomas were treated, of which 151 (4.3%) occurred in the oral cavity and maxillofacial region. Of these 151 lesions, 48 were diffuse large B-cell lymphoma, with 64% for OS at 2 years and 45% for OS at 5 years. Of the variables studied as possible prognostic factors, multivariate analysis found the following variables have statistically significant values: age (p=0.042), clinical stage (p=0.007) and performance status (p=0.031). These data suggest that patients have a higher risk of mortality if they are older, at a later clinical stage, and have a higher performance status.

Surgical repositioning of osseointegrated malposed dental implant with segmental osteotomy.

Abstract After extensive research, the practice with dental implants has been used on a large scale. With the increase in its indications in various local conditions, more complications have been observed. Among these, one of the most frequent is the installation of the implants in a three-dimensional altered position, making the prosthesis and aesthetics more difficult to achieve. For this reason, techniques such as segmental osteotomy have been developed and adapted to implantology to reestablish the adequate position of these implants with correct aesthetic outcome and function. The present clinical report shows the segmental osteotomy technique in a malposed osseointegrated dental position of the upper central incisor with 1-year follow-up.