I am a master degree candidate at Faculty of Dentistry-Cairo University,Periodontist and implantologist.
Animals are considered as a suitable convenient pre-clinical model for assessment of dental biomaterials. Small animal models have rapid bone turn-over, thus provide general idea about healing process at several intervals after surgical procedure. Ability to produce bilateral surgical procedures is an added advantage, since it allow for intra-animal comparison and reduce the numbers of animals needed. Moreover, small animal models are small domestic mammals that require relatively manageable husbandry
Abstract: The objective of this study is to systematically evaluate the effects of a tissue-engineered bone complex for maxillary sinus augmentation in a canine model. Twelve sinus floor augmentation surgeries in 6 animals were performed bilaterally and randomly repaired with the following 3 groups of grafts: group A consisted of tissue-engineered osteoblasts/beta-TCP complex (n=4); group B consisted of beta-TCP alone (n=4); group C consisted of autogenous bone obtained from iliac crest as a positive control (n=4). All dogs had uneventful healings following the surgery. Sequential polychrome fluorescent labeling, maxillofacial CT, microhardness tests, as well as histological and histomorphometric analyses indicated that the tissue-engineered osteoblasts/beta-TCP complex dramatically promoted bone formation and mineralization and maximally maintained the height and volume of elevated maxillary sinus. By comparison, both control groups of beta-TCP or autologous iliac bone showed considerable resorption and replacement by fibrous or fatty tissue. We thus conclude that beta-TCP alone could barely maintain the height and volume of the elevated sinus floor, and that the transplantation of autogenous osteoblasts on beta-TCP could promote earlier bone formation and mineralization, maximally maintain height, volume and increase the compressive strength of augmented maxillary sinus. This tissue engineered bone complex might be a better alternative to autologous bone for the clinical edentulous maxillary sinus augmentation.
Pub.: 19 Sep '09, Pinned: 25 Aug '17
Abstract: Implant dentistry in the posterior maxilla often requires bone augmentation. The gold standard, autogenous bone graft, requires additional surgery with associated morbidity, while bone biomaterials may not support relevant bone formation. Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS), however, induces significant, clinically relevant bone formation in several settings including the maxillary sinus floor.The objective of this study was to compare local bone formation and osseointegration following maxillary sinus augmentation using rhBMP-2/ACS or a particulate autogenous cancellous bone graft obtained from the iliac crest in conjunction with immediate placement of dental implants.Bilateral sinus augmentation using an extraoral approach including rhBMP-2 (0.43 mg/ml)/ACS or the autogenous bone graft, alternated between left and right sinus cavities in five adult male Yucatan mini-pigs, was performed. Two 12-mm dental implants were inserted into the sinus wall protruding approximately 8 mm into the sinus cavity. Surgical sites were closed and sutured in layers; block biopsies collected for histometric analysis at 8 weeks.rhBMP-2/ACS induced bone of significantly greater and consistent quality compared with the iliac crest autogenous bone graft; bone density averaging 51.9 ± 3.0% vs. 32.9 ± 2.5% (P = 0.01). However, there were only numerical differences in augmented bone height (9.3 ± 0.5 vs. 8.6 ± 0.7 mm) and bone-implant contact (37.4 ± 3.0% vs. 30.7 ± 5.9%) between treatments.rhBMP-2/ACS induces bone of superior quality compared with an iliac crest particulate autogenous cancellous bone graft when used for maxillary sinus augmentation, and should perhaps be considered the new standard for this indication.
Pub.: 27 Jan '12, Pinned: 25 Aug '17
Abstract: Sinus augmentation is a routine surgical procedure in dentistry. At present, various animal models are available for the research purpose on this topic. In particular, for the first time, we have performed a morphological study on sheep sinus, using cone beam computed tomography (CBCT), to precisely define the anatomy of the ovine sinus. Then, we compared the sheep and human sinus morphological parameters, in order to uniform the research approach to the sinus augmentation procedures and to standardize this experimental model. Six fresh heads of adult female sheep were studied with CBCT and histologic examination to determine the dimensions and the organization of the ovine maxillary sinus. The comparison of the dimensional values between man and sheep shows evident differences between the two species; CBCT offers detailed information for studying normal maxillary sinus. Human and sheep maxillary sinus show anatomical differences that must be taken into account in experimental procedures.
Pub.: 15 May '15, Pinned: 25 Aug '17
Abstract: The aim of this retrospective study was to compare the performance of implants placed after alveolar distraction osteogenesis (ADO) or autogenous onlay bone grafting (AOBG) based on implant survival, peri-implant bone resorption, and clinical parameters.From February 2008 to July 2012, 17 patients (6 women and 11 men) with implant placement after ADO (group 1, n = 8) or AOBG (group 2, n = 9) were included in this retrospective study. In all, 37 implants were placed in group 1 and 22 implants were placed in group 2. Implant survival rate, peri-implant bone resorption, probe depth (PD), modified plaque index (mPI), and modified sulcus bleeding index (mSBI) were analyzed to evaluate implant prognosis.Successful reconstruction of vertical alveolar defects and uneventful implant placement were achieved in all patients in the 2 groups. After a mean follow-up of 47.9 ± 13.3 months, implant survival was 97.3% (36 of 37) in group 1 and 95.5% (21 of 22) in group 2. No statistically relevant differences were observed. Peri-implant bone resorption was 1.29 ± 0.59 mm in group 1, which was slightly higher than 1.24 ± 0.87 mm in group 2 at last follow-up. The difference was not statistically relevant. Favorable peri-implant conditions were indicated by PD, mPI, and mSBI in the 2 groups.ADO and AOBG can be used for correction of vertical alveolar defects with a reliable implant prognosis. Comparably high implant survival rates and favorable peri-implant conditions were attained.
Pub.: 25 Jul '17, Pinned: 25 Aug '17
Abstract: Preclinical in vivo experimental studies are performed for evaluating proof-of-principle concepts, safety and possible unwanted reactions of candidate bone biomaterials before proceeding to clinical testing. Specifically, models involving small animals have been developed for screening bone biomaterials for their potential to enhance bone formation. No single model can completely recreate the anatomic, physiologic, biomechanic and functional environment of the human mouth and jaws. Relevant aspects regarding physiology, anatomy, dimensions and handling are discussed in this paper to elucidate the advantages and disadvantages of small-animal models. Model selection should be based not on the 'expertise' or capacities of the team, but rather on a scientifically solid rationale, and the animal model selected should reflect the question for which an answer is sought. The rationale for using heterotopic or orthotopic testing sites, and intraosseous, periosseous or extraskeletal defect models, is discussed. The paper also discusses the relevance of critical size defect modeling, with focus on calvarial defects in rodents. In addition, the rabbit sinus model and the capsule model in the rat mandible are presented and discussed in detail. All animal experiments should be designed with care and include sample-size and study-power calculations, thus allowing generation of meaningful data. Moreover, animal experiments are subject to ethical approval by the relevant authority. All procedures and the postoperative handling and care, including postoperative analgesics, should follow best practice.
Pub.: 14 Apr '15, Pinned: 25 Aug '17