SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: The Journal of oral implantology

30

Despite the increasing clinical use of topical platelet-rich plasma (PRP) to enhance tissue healing and regeneration, there is no properly standardized method of autologous PRP gel preparation. This study examined the effect of the centrifugation time and gravitational force (g) on the platelet recovery ratio of PRP and determined the most effective centrifugation conditions for preparing PRP. Two-step centrifugations for preparing PRP were used in 39 subjects who had consented prior to the study’s start. The separating centrifugation (Step 1, used to separate whole blood into its two main components: red blood cells and plasma) was tested from 500g to 1900g at 200g increments for 5 minutes (min), and from 100g to 1300g at 200g increments for 10 minutes. After separating centrifugation, upper plasma layer was transferred to another plain tube for the condensation centrifugation and remaining lower cell layer was discarded. The condensation centrifugation (Step 2, used to condense the platelets in the separated plasma) was tested at 1000g for 15 min, 1500g for 15 min, 2000g for 5 min and 3000g for 5 min, additionally at 1000g for 10 min and 1500g for 10 min. Platelet gelation was induced by adding 10% calcium gluconate to final PRP with volume ratio of 1:10. The optimal separating centrifugation conditions were followed by 900g for 5 minutes and the condensation conditions were followed by 1500g for 15 minutes, of which recovery ratios were 92.0 ± 3.1% and 84.3 ± 10.0%, respectively.

Concepts: Blood, Red blood cell, Bone marrow, Liver, Platelet, Gravitation, Heat transfer, Blood cell

27

Abstract Several procedures have been proposed to achieve maxillary ridge augmentation. These require bone replacement materials to be manually cut, shaped and formed at the time of implantation, resulting in an expensive and time-consuming process. In the present study, we describe a technique for the design and fabrication of custom-made scaffolds for maxillary ridge augmentation, using three-dimensional (3D) computed tomography (CT) and computer-aided-design/ computer-aided-manufacturing (CAD/CAM). CT images of the atrophic maxillary ridge of ten patients were acquired and modified into 3D reconstruction models. These models were transferred as stereolithographic files (STL) to a CAD program, where a virtual 3D reconstruction of the alveolar ridge was generated, to produce anatomically-shaped, custom-made scaffolds. CAM software generated a set of tool-paths for manufacture by a computer-numerical-control (CNC) milling machine into the exact shape of the reconstruction, starting from porous hydroxyapatite (HA) blocks. The custom-made scaffolds were of satisfactory size, shape, and appearance, matched the defect area, suited the surgeon’s requirements and were easily implanted during surgery. This helped to reduce the time for the surgery, and contributed to the good healing of the defects.

Concepts: Present, Time, Medical imaging, Physician, Reconstruction era of the United States, Milling machine, Numerical control, Computer-aided manufacturing

26

Abstract In narrow alveolar ridge many surgical approaches exist, and the most frequently used is bone graftingThe subperiosteal tunneling approach is a minimal safety procedure that allows to allocate the graft in a space that is obtained between the soft tissues and the underlying bone, through an access rapresented by one single incision on the mesial limit of the bone defect. A 55-year-old caucasian woman with a severe bone atrophy in the maxillary arch was treated with horizontal bone augmentation. A mucoperiosteal tunnel with a periosteal elevator through one single incision of moderate dimensions per hemiarch, insertion of tissue bank ilium bicortical bone(FFB) and a consequent complete prosthetic-implant rehabilitation was realized. The tunnel technique provided primary intention closure of the surgical wound, avoiding dehiscences and infections, and reducing the edema and the post-operative discomfort for the patient. Clinical and histological studies support the use of FFB and it has been suggested that the results of a graft with homologous and with autologus bone can be comparable, even though the healing phase is more critical and longer for the allograft. The combination of homologous grafts with the tunnel technique reduces significantly the surgical trauma and the postoperative discomfort, as well as the risk of exposure of the graft during the healing phase, with the risk of graft failiure. In our experience, onlay grafting with frozen bone is a predictable technique for horizontal augmentation.

Concepts: Medicine, Surgery, Tissues, Organ transplant, Grafting, Tissue, Trauma surgery, Medical grafting

26

Abstract The present preclinical and clinical study assessed the inflammatory response to a high temperature-treated xenogeneic material (Bego-Oss®) and the effects of this material on the occurrence of multinucleated giant cells, implantation bed vascularization and regenerative potential.After evaluation of the material characteristics via scanning electron microscopy, subcutaneous implantation in CD-1 mice was used to assess the inflammatory response to the material for up to 60 days. The clinical aspects of this study involved the use of human bone specimens six months after sinus augmentation. Established histological and histomorphometric analysis methods were applied.After implantation, the material was well integrated into both species without any adverse reactions. Multinucleated giant cells were observed in both species and were associated with enhanced vascularization. These results revealed that the high heat treatment led to an increase in the inflammatory tissue response to the biomaterial and a combined increase in multinucleated giant cell formation.Further clarification of the differentiation of the multinucleated giant cells toward so-called osteoclast-like cells or foreign body giant cells is needed to relate these cells to the physicochemical composition of the material.

Concepts: Giant cell, Foreign-body giant cell

26

Abstract Purpose: to evaluate the action of recombinant human growth hormone (rhGH) on osseointegration of titanium implants in rabbits. Materials and Methods: fourteen adult new Zealand rabbits, with age of 30 weeks, were used in the study, randomly divided into 2 groups. In each animal, two (2.2mm x 6mm) pure titanium implants were placed in the left tibia. In one group (test group), 1UI (0.3mg) of rhGH as a lyophilized powder was applied to each osteotomy site prior to implant placement. Only titanium implants were placed in osteotomy sites of the other group (control). Animals were sacrificed at 14 and 42 days after surgery and samples were then prepared for histological analysis and biomechanical test. Results: biomechanical test showed tensile pull-out stress values of 33.88 N/cm2 for controls and 59.26 N/cm2 for the rhGH group at 14 days and 25.99 N/cm2 and 29.69 N/cm2 for control and test group respectively at 42 days. Scanning electron microscope (SEM) analysis showed a more uniform and abundant bone tissue in contact to the implants in the test group at 14 days, and no differences between groups in 42 days. Furthermore, histological analysis also showed accelerated bone repair in 14 days and a more advanced stage of bone remodeling for the rhGh-treated group when compared to controls after 42 days of repair. Conclusions: such results show that the topical use of rhGH induce new bone formation in the early stages of bone repair and hence accelerates osseointegration of titanium dental implants.

Concepts: Bone, Skeletal system, Growth hormone, Scanning electron microscope, Dental implant, Titanium, Oral and maxillofacial surgery, Osseointegration

26

Abstract The objective of the present study is the evaluation of the comprehensive 5-year results of fixed mandibular dentures fabricated from metal-acrylic or metal-ceramics according to the ‘All-on-4'™ protocol. Twenty-seven patients that received immediately loaded 'All-on-4'™ fixed mandibular dentures in 2005 were included in the study, and they were evaluated up to 5 years after denture integration. Endpoints were chosen in accordance with the 2007 Pisa consensus and included bone resorption, the Oral Health Impact Profile (OHIP), the Sulcus Fluid Flow Rate (SFFR), and prosthodontic complications. The initial situation in both groups was largely identical. Bone loss remained under 2 mm after 5 years in all implants and showed no group difference. The SSFR showed a gradual increase in both groups, and acrylic-bearing implants showed a substantially and significantly higher flow rate from the third year onward. The subjective improvement as expressed by the OHIP score was immediate and dramatic, and it showed no group differences. All acrylic restorations showed some extent of abrasion, and veneer fractures occurred in 4 patients (28.6%). Besides a single fracture of a fixation screw, there were no prosthetic complications in patients with ceramic suprastructures. According to bone loss and subjective outcome, acrylic and ceramic suprastructures apperared to be equivalent after 5 years; however, sulcus flow and prosthodontic complications suggest that the economic advantage of acrylic dentures may be specious. The rational choice of implant suprastructures requires comprehensive, long-term observation. Short-term economical benefits might be cancelled out in the long run.

Concepts: Time, Bone, Bone fracture, Fracture, Fluid dynamics, Economics, Dentures, Prosthodontics

26

Abstract Aim: To accurately portray the risk management of a patient presenting with mandibular osteonecrosis following bisphosphonate exposure and immediate loading of dental implant treatment. This case report describes a 58-year-old African American female having experienced previous success of implant osseointegration in the maxilla, sought similar mandibular treatment four years later and had been taking bisphosphonate for a total 5 years. All existing mandibular teeth were extracted and 6 Brånemark System implants were placed and immediately loaded without complication. Two weeks postoperative, a slower rate of healing was noticed. Over a period of six weeks, the patient’s condition worsened. An extraoral fistula exuded from a lesion on the left inferior border of the mandible. The patient was diagnosed with bisphosphonate-induced osteonecrosis of the jaw (BONJ) and discontinued bisphosphonate medication indefinitely. The patient was treated for BONJ and four of the six implants which were encapsulated in tissue were removed. She ceased the oral Fosamax therapy for two and a half years following the BONJ, and had morning-fasting serum C-terminal telopeptide (CTX) test of 457 pg/ml* which showed her bone turnover rate had returned to normal levels. Four new Brånemark System implants were placed in the mandible and were immediately loaded. Four months later, a screw-retained implant-supported final prosthesis was delivered. The patient has been followed for 5 years from the time of retreatment of mandibular arch and 11 years from time of implant placement in the maxillary arch. All postoperative evaluations have been uneventful. This case report demonstrated how management of BONJ can lead to successful retreatment with implants after a drug holiday, and how being cognizant to the length of time of Fosamax therapy can help clinicians avoid BONJ complications.

Concepts: Bone, Mandible, Implants, Prosthetics, Dental implant, Osseointegration, Jaw, Maxilla

25

Abstract BackgroundThis study compared the material-specific tissue response to the synthetic, hydroxyapatite-based bone substitute material Nanobone® (NB) with that of the xenogeneic, bovine-based bone substitute material Bio-Oss® (BO) .Materials and MethodsThe sinus cavities of 14 human patients were augmented with NB and BO in a split-mouth design. Six months after augmentation, bone biopsies were extracted for histological and histomorphometric investigation prior to dental implant insertion.The cellular inflammatory pattern, the induction of multinucleated giant cells, vascularization, the relative amounts of newly formed bone, connective tissue and the remaining bone substitute material were evaluated. ResultsNB granules were well integrated in the peri-implant tissue and were surrounded by newly formed bone tissue. Multinucleated giant cells were visible on the surfaces of the remaining granules. BO granules were integrated into the newly formed bone tissue, which originated from active osteoblasts on their surface. Histomorphometric analysis showed a significantly higher number of multinucleated giant cells and blood vessels in the NB group compared to the BO group. No statistical differences were observed in regard to connective tissue, remaining bone substitute and newly formed bone. ConclusionThe results of this study highlight the different cellular reactions to synthetic and xenogeneic bone substitute materials. The significantly higher number of multinucleated giant cells within the NB implantation bed seems to have no effect on its biodegradation. Accordingly, the multinucleated giant cells observed within the NB implantation bed have characteristics more similar to those of foreign body giant cells than to those of osteoclasts.

Concepts: Bone, Blood, Collagen, Tissues, Dental implant, Connective tissue, Osteoblast, Foreign-body giant cell

24

The aim of this study is to present a method, using three CAD/CAM surgical guides, to accurately obtain the desired bone reduction followed by immediate implant placements and loading for patients diagnosed with terminal dentition. Patients who had bone reduction, implants placed and immediately loaded using Anatomage Invivo 5 CAD/CAM surgical guides between the period 2013 to 2015 were evaluated retrospectively. Patients diagnosed with terminal dentition and treated using the “three-guide technique” were identified. Pre and post-surgical images were superimposed to evaluate deviations of the bone reduction and deviations at the crest, apex, and angle of implants placed. Twenty-six implants placed in 5 patients were included in this study. The overall deviation means measured for bone reduction was 1.98mm. The overall deviation means measured for implant placement at the crest, apex, and angle were 1.43mm, 1.90mm, and 4.14o respectively. CAD/CAM surgical guide fabrication is an emerging tool that may facilitate the surgical process and aid in safe and predictable execution of bone reduction and immediate implant placement. A method is presented, using three CAD/CAM surgical guides, to obtain the desired bone reduction followed by immediate implant placement and loading for patients diagnosed with terminal dentition. This method may improve guide stability for patients with terminal dentition undergoing complete implant-supported treatment by taking advantage of the teeth to be extracted.

Concepts: Medical terms, Surgery, Orthopedic surgery, Teeth, Dental implant, Implant, Reduction, The Crest

24

Dental implants may fail to osseointegrate in sites of endodontic failure. This may occur as a result colonization by various anaerobic and facultative bacterial species. If an implant is placed in a site where vegetative bacteria are residing, the implant may fail to integrate if a bacterial colonization proceeds coronally. If the implant apical cortical bone is thin or if there is an apical fenestration the colonization may proceed through the thin or non-existent bone through the covering mucosa relieving inflammatory pressure to create an apical (retrograde) peri-implantitis. Enterococcus faecalis may be a prime culprit in these implant failures. After thorough debridement, the implant may be immediately placed after extraction of an endodontically failed tooth and the patient treated with an appropriate antibiotic. Alternatively waiting for post-extraction healing and subsequent implant placement can be done. Nevertheless either way may allow the formation of bacterial vegetative forms or biofilms. The implant surface may be colonized when the surface is exposed to the bacteria. Thorough debridement is crucial. Nevertheless organisms may persist. Randomized controlled trials are needed to elucidate this issue.

Concepts: Archaea, Bacteria, Antibiotic resistance, Streptococcus, Failure, Dental implant, Microorganism, Osseointegration