Deproteinized bovine bone mineral in marginal defects at implants installed immediately into extraction sockets: an experimental study in dogs

Aim: To evaluate the influence of deproteinized bovine bone mineral (DBBM) particles concomitant with the placement of a collagen membrane on alveolar ridge preservation and on osseointegration of implants placed into alveolar sockets immediately after tooth extraction. Material and methods: The pulp tissue of the mesial roots of 3P3 was removed in six Labrador dogs and the root canals were filled. Flaps were elevated in the right side of the mandible, and the buccal and lingual alveolar bony plates were exposed. The third premolar was hemi-sectioned and the distal root was removed. A recipient site was prepared and an implant was placed lingually. After implant installation, defects of about 0.6mm wide and 3.1mm depth resulted at the buccal aspects of the implant, both at the test and at the control sites. The same surgical procedures and measurements were performed on the left side of the mandible. However, DBBM particles with a size of 0.25-1mm were placed into the remaining defect concomitant with the placement of a collagen membrane. Results: All implants were integrated into mature bone. No residual DBBM particles were detected at the test sites after 4 months of healing. Both the test and the control sites showed buccal alveolar bone resorption, 1.8 +/- 1.1 and 2.1 +/- 1mm, respectively. The most coronal bone-to-implant contact at the buccal aspect was 2 +/- 1.1 an 2.8 +/- 1.3mm, at the test and the control sites, respectively. This difference in the distance was statistically significant. Conclusion: The application of DBBM concomitant with a collagen membrane to fill the marginal defects around implants placed into the alveolus immediately after tooth extraction contributed to improved bone regeneration in the defects. However, with regard to buccal bony crest preservation, a limited contribution of DBBM particles was achieved.

Magnesium-enriched hydroxyapatite at immediate implants: a histomorphometric study in dogs

AimTo evaluate the influence of magnesium-enriched hydroxyapatite (MHA) (SintLife (R)) on bone contour preservation and osseointegration at implants placed immediately into extraction sockets.Material and methodsIn the mandibular pre-molar region, implants were installed immediately into extraction sockets of six Labrador dogs. MHA was placed at test sites, while the control sites did not receive augmentation materials. Implants were intended to heal in a submerged mode. After 4 months of healing, the animals were sacrificed, and ground sections were obtained for histomorphometric evaluation.ResultsAfter 4 months of healing, one control implant was not integrated leaving n=5 test and control implants for evaluation. Both at the test and the control sites, bone resorption occurred. While the most coronal bone-to-implant contact was similar between test and control sites, the alveolar bony crest outline was maintained to a higher degree at the buccal aspect of the test sites (loss: 0.7 mm) compared with the control sites (loss: 1.2 mm), even though this difference did not reach statistical significance.ConclusionsThe use of MHA to fill the defect around implants placed into the alveolus immediately after tooth extraction did not contribute significantly to the maintenance of the contours of the buccal alveolar bone crest.To cite this article:Caneva M, Botticelli D, Stellini E, Souza SLS, Salata LA, Lang NP. Magnesium-enriched hydroxyapatite at immediate implants: a histomorphometric study in dogs.Clin. Oral Impl. Res. 22, 2011; 512-517doi: 10.1111/j.1600-0501.2010.02040.x.

Development, characterization and clinical use of a biodegradable composite scaffold for bone engineering in oro-maxillo-facial surgery

We have developed a biodegradable composite scaffold for bone tissue engineering applications with a pore size and interconnecting macroporosity similar to those of human trabecular bone. The scaffold is fabricated by a process of particle leaching and phase inversion from poly(lactide-co-glycolide) (PLGA) and two calcium phosphate (CaP) phases both of which are resorbable by osteoclasts; the first a particulate within the polymer structure and the second a thin ubiquitous coating. The 3-5 mu m thick osteoconductive surface CaP abrogates the putative foreign body giant cell response to the underlying polymer, while the internal CaP phase provides dimensional stability in an otherwise highly compliant structure. The scaffold may be used as a biomaterial alone, as a carrier for cells or a three-phase drug delivery device. Due to the highly interconnected macroporosity ranging from 81% to 91%, with macropores of 0.8 similar to 1.8 mm, and an ability to wick up blood, the scaffold acts as both a clot-retention device and an osteoconductive support for host bone growth. As a cell delivery vehicle, the scaffold can be first seeded with human mesenchymal cells which can then contribute to bone formation in orthotopic implantation sites, as we show in immune-compromised animal hosts. We have also employed this scaffold in both lithomorph and particulate forms in human patients to maintain alveolar bone height following tooth extraction, and augment alveolar bone height through standard sinus lift approaches. We provide a clinical case report of both of these applications; and we show that the scaffold served to regenerate sufficient bone tissue in the wound site to provide a sound foundation for dental implant placement. At the time of writing, such implants have been in occlusal function for periods of up to 3 years in sites regenerated through the use of the scaffold.

Early healing pattern of autogenous bone grafts with and without e-PTFE membranes: A histomorphometric study in rats

Objective. The aim of this study was to perform quantitative and qualitative analyses of the initial repair pattern of an autogenous bone block graft when covered or not with e-PTFE membranes. Study design. Sixty male Wistar rats received a bone graft plus an e-PTFE membrane (MB) or just the graft (B). A block graft was harvested from the animal's calvarium and was laid and stabilized on the external cortical area near the angle of the mandible. Descriptive histology and histomorphometric analyses were carried out and the data were analyzed statistically by ANOVA and the Tukey test, with the level of significance set at 5%. Results. The results for group B showed that there was bone loss during the healing period (B0 = 1.38, B45 = 1.05, F = 7.91 > F C = 3.02), that is, the initial volume of the graft decreased in time. Bone tissue loss was about 24%. In contrast, the MB group showed bone tissue gain along the observation period (MB0 = 1.54, MB45 = 2.40, F = 7.91 > FC = 3.02), meaning that the total volume of newly formed bone was greater than the original graft area. Bone tissue gain was approximately 55%. MB showed significantly greater bone gain when compared to B (B45 = 1.05, MB45 = 2.40, F = 39.86 > FC = 1.90). These significant differences between B and MB could already be observed after 21 days. Conclusions. The bone block graft underwent resorption at an early healing stage, while additional new bone formation was observed when the bone graft was covered with an e-PTFE membrane. © 2005 Mosby, Inc. All rights reserved.

Comparative therapeutic use of Risedronate and Calcarea phosphorica - Allopathy versus homeopathy - In bone repair in castrated rats

Osteoporosis, a disease characterized by progressive bone loss, has been the target of several studies in the past few years. It results in a much higher risk for fractures and might cause slower bone lesion healing. The aim of this work was to study the effects of Risedronate (allopathic medicine) and Calcarea phosphorica 6CH (homeopathic medicine) on the repair of bone lesions in male rats with osteoporosis induced by castration. Eighty-four three-month-old rats were used divided into four groups of twenty-one animals each. Three groups where castrated and one group was submitted to Sham surgery. One month later, cortical lesions were made in all animals' tibiae and, after one day, the different experimental treatments began according to the following groups: CR - castrated/Risedronate (1 mg/kg/day); CCp - castrated/ Calcarea phosphorica 6CH (3 drops/day); CP - castrated/placebo and SP - Sham/placebo. The animals were sacrificed at seven, fourteen and twenty-eight days after the beginning of the treatments and had their tibiae removed. Digital radiographs of the tibiae were taken and analyzed in order to evaluate the optical density of the defect area. Then, they were decalcified and processed for histological and histomorphometrical analysis. The data were submitted to ANOVA, and to the Tukey and Dunnett tests (5%). The allopathic and homeopathic treatments led to different bone formation as regards remodeling and maturation aspects. Further research is necessary to access the resistance and quality of the newly formed bone.

Hindlimb unloading producing effects on bone biomechanical properties in mature male rats

Aging is associated with decline in muscle mass and strength and reduced bone density. Age-related bone loss is a primary factor in osteoporosis and all individuals are potential candidates for osteoporosis because bone loss with aging occurs in men and women, but less studied in men. To examine the appropriateness of hindlimb elevation, by tail suspension as a model for diminished mechanical loading, and to determine the influence of age on bone responsiveness to skeletal unloading, we use dual X ray absorptiometry (DXA) and digital radiographic images to analyze the response of the femur from mature rats to biomechanical loads. Femurs from male Wistar rats (9-mo-old) were scanned using DXA and DIGORA and measures obtained in ephipyseal and diaphyseal regions of interest. The mechanical testing was divided into compression load to fracture the head and a three-point bending load to fracture the femur middiaphysis. In femoral epiphysis from hindlimb unload (HU), animals presented significant differences between mineral bone content and density assessed by DXA. Detailed regions of femoral epiphysis (head, throcanteric fossa, throcanter and metaphysis) presented significant lower values from radiographic density. Only compressive load necessary to fracture the femoral head neck was also significantly diminished in HU animals. Disuse induced, as in elderly patients, deterioration of the trabecular bone architecture with critical effect on bone fragility. Rats with 21 days of hindlimb unloading can simulate disuse, suggesting that certain sub-regions of their aging bones are more susceptible to fracture, while other, i.e. diaphyses, are not.

Role of periodontal pathogenic bacteria in RANKL-mediated bone destruction in periodontal disease

Accumulated lines of evidence suggest that hyperimmune responses to periodontal bacteria result in the destruction of periodontal connective tissue and alveolar bone. The etiological roles of periodontal bacteria in the onset and progression of periodontal disease (PD) are well documented. However, the mechanism underlying the engagement of periodontal bacteria in RANKL-mediated alveolar bone resorption remains unclear. Therefore, this review article addresses three critical subjects. First, we discuss earlier studies of immune intervention, ultimately leading to the identification of bacteria-reactive lymphocytes as the cellular source of osteoclast-induction factor lymphokine (now called RANKL) in the context of periodontal bone resorption. Next, we consider (1) the effects of periodontal bacteria on RANKL production from a variety of adaptive immune effector cells, as well as fibroblasts, in inflamed periodontal tissue and (2) the bifunctional roles (upregulation vs. downregulation) of LPS produced from periodontal bacteria in a RANKL-induced osteoclast-signal pathway. Future studies in these two areas could lead to new therapeutic approaches for the management of PD by down-modulating RANKL production and/or RANKL-mediated osteoclastogenesis in the context of host immune responses against periodontal pathogenic bacteria. © 2010 Mikihito Kajiya et al.

Estudio histológico comparativo de la reparación ósea entre hueso alveolar y extra-alveolar en los cerdos sometidos a osteotomía con alta y baja velocidad, con refrigeración líquida

Taking into account the bone repair process in pigs has shown a greater similarity among the histological variables studied compared to other biological models, the present study has as its aim to evaluate the histological bone repair process of osteotomy performed on alveolar and extra-alveolar bones, using drilling tools with liquid refrigeration. Material and method: Eighteen Large White pigs weighing between 20 and 25 Kg were divided into three groups of six animals in order to evaluate the osteotomy repairs with low and high speed in the alveolar bone and threes in the extra-alveolar area, study periods of 7, 14 and 28 days. Results: It was observed that in the alveolar bone at the postoperative times of 14 and 28 days, the best repair results were in the osteotomy performed with low speed, while in the 7 day postoperative period, the results with high speed were slightly better, in alveolar areas as well as extra-alveolar areas. There no statistically significant differences between the alveolar and extra-alveolar bone repair process. Conclusions: The repair process, by means of microscopic analysis in the alveolar and extra-alveolar areas, are similar with better results observed in osteotomies performed with low speed drills in the 14 and 28 day study periods, and at 7 days postoperative the results with high speed drills and refrigeration were slightly better. Research works using pigs as an animal model are perfectly viable. © 2011 SECOM.

Bone augmentation and autogenous transplantation of premolar to the site of the fissure in a cleft palate patient

This article presents a case report of autogenous tooth transplantation to the site of the fissure, in addition to bone augmentation with graft of autogenous bone harvested from the iliac crest, performed in a cleft palate patient, who had insufficient bone volume. A non-syndromic 10-year-old girl, with a unilateral cleft lip and palate, incisal transforamen fissures, agenesis of the maxillary left central incisor and both maxillary lateral incisors, was treated with autogenous bone graft in the cleft area. The orthodontic treatment plan was to replace the missing lateral incisors with the maxillary canines and to extract the mandibular first premolars. One of the mandibular premolars was extracted from its site with 2/3 of its root formation completed and transplanted to the maxillary left central incisor area. After orthodontic treatment, the anatomic crowns were characterized with composite resin. Autogenous tooth transplantation can be performed in the area of the fissure in young cleft palate patients, by performing bone graft augmentation before transplantation of the tooth, to gain sufficient recipient alveolar bone volume. A multidisciplinary approach is mandatory for the success of this clinical procedure, especially in cleft palate patients. © 2012 John Wiley & Sons A/S.

The influence of topic and systemic administration of copaiba oil on the alveolar wound healing after tooth extraction in rats

The Copaiba oil has been used as an auxiliary treatment of inflammations, skin disorders and stomach ulcers, however, in dentistry, this alternative medicine has not been investigated yet. The purpose of this study was to evaluate the influence of topic and systemic administration of copaiba oil on the alveolar wound healing after tooth extraction. Twenty-eight wistar male rats had their lower first molar teeth extracted. Subsequently, they were divided in four groups, according to the treatment performed: (a) alveolar socket irrigation with copaiba oil; (b) alveolar socket irrigation with physiological serum; (c) daily gavage with copaiba oil or (d) daily gavage with physiological serum. After the sacrifice, the mandibles were removed and processed in order to obtain decalcified histological sections. The results demonstrated high level of epithelial migration, small number of inflammatory cells and vascular enhancement in the animals which received systemic administration of copaiba oil. The rats treated with topic administration of copaiba oil presented ulcerations and large number of inflammatory cells. An increased bone neoformation was observed in both groups treated with copaiba oil when compared with placebo group. It could be concluded that topic or systemic administration of copaiba oil leads to a better alveolar bone healing, however the topic application on connective tissue should be carefully considered, regarding the whole socket wound healing. © Medicina Oral S. L. C.I.F. B 96689336 - eISSN: 1989-5488.

Ação do estrógeno na expressão de proteínas relacionadas ao metabolismo ósseo durante regeneração alveolar em ratas

Pós-graduação em Odontologia - FOA

Tratamento de doença periodontal induzida em ratos através da aplicação de laser de Er, Cr:YSGG: análise histológica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do efeito do atenolol no processo de reparo alveolar em ratos espontaneamente hipertensos (SHR)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do estrógeno (17B-estradiol) no osso alveolar e na movimentação dentária em ratas, após remoção do aparelho ortodôntico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do alcoolismo crônico e da deficiência estrogênica sobre a variação de estequiometria da hidroxiapatita na crista óssea alveolar de ratas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)