Platelet-rich plasma and bone healing: a histologic study in titanium bone chambers

The potential benefits of platelet-rich plasma in the healing of isolated defects are unclear. The purpose of this study was to evaluate the effects of PRP on bone healing in titanium bone chambers, which represented isolated defects. PRP was prepared from blood collected from six adult female albino New Zealand rabbits. Titanium bone chambers with a 4-mm inner diameter were implanted into the tibiae of each animal at baseline and 2 weeks later; chambers healed for 6 or 8 weeks, either with PRP (test) or without PRP (control). Bone chambers were harvested from each animal and processed for histologic evaluation. Bone formation in 8-week test samples was not significantly different from that of the 6-week test samples. In control samples, more bone formation was seen at 8 weeks than at 6 weeks. The fibrous tissue content in control samples was higher than that of the test group in superficial sections, revealing that the tissue differentiation rate was higher in the test chambers. Time-dependent bone tissue differentiation in bone chambers augmented with PRP is higher than in normal wound healing, and PRP seems to increase the rate of tissue differentiation in early healing.     

Maxillary sinus augmentation with different biomaterials: a comparative histologic and histomorphometric study in man

OBJECTIVE: Rehabilitation of the edentulous posterior maxilla with dental implants can be difficult because of insufficient bone volume caused by pneumatization of the maxillary sinus and crestal bone resorption. Different biomaterials have been used for sinus augmentation. The aim of the study was to compare different materials in maxillary sinus augmentation in man. METHODS: A total of 94 patients participated in this study. Inclusion criteria were maxillary partial (unilateral or bilateral) edentulism involving the premolar/molar areas, and the presence of 3-5-mm crestal bone between the sinus floor and alveolar ridge. A total of 362 implants were inserted. There were 9 biomaterials used in the sinus augmentation procedures. Each patient underwent 1 biopsy after 6 months. A total of 144 specimens were retrieved. RESULTS: None of the 94 patients had complications. All implants were stable, and x-ray examination showed dense bone around the implants. Mean follow-up was 4 years. There were 7 implants that failed. Histologic resultsshowed that almost all the particles of the different biomaterials (i.e., autologous bone, demineralized freeze-dried bone allograft Biocoral [Inoteb, St. Gonnery, France], Bioglass [US Biomaterials, Alachua, FL], Fisiograft [Ghimas, Bologna, Italy], PepGen P-15 [Dentsply Friadent CeraMed, Lakewood, CO], calcium sulfate, Bio-Oss [Geistlich Pharma AG, Wohlhusen, Switzerland], and hydroxyapatite) were surrounded by bone. Some biomaterials were more resorbable than others. Included are the histomorphometry clarified features of the newly formed bone around the different grafted particles. CONCLUSION: All biomaterials examined resulted in being biocompatible and seemed to improve new bone formation in maxillary sinus lift. No signs of inflammation were present. The data are very encouraging because of the high number of successfully treated patients and the good quality of bone found in the retrieved specimens.     

Mandibular bone remodeling under a choline-deficient diet: a histomorphometric study in rats

BACKGROUND: A deficiency of lipotropic factors in the rat induces renal, hepatic, and/or hematic damage. The aim of the present study was to evaluate the effect of a choline-deficient diet and refeeding on mandibular bone remodeling. METHODS: Fifty Wistar rats were divided into 5 groups: group 1 (G1): control diet for 15 days; group 2 (G2): choline-deficient diet for 15 days; group 3 (G3): control diet for 30 days; group 4 (G4): choline-deficient diet for 30 days; and group 5 (G5): choline-deficient diet for 15 days and control diet for 15 days. All animals were sacrificed by ether overdose. The mandibles were resected, radiographed, decalcified, processed, and embedded in paraffin. Bucco-lingually oriented sections were obtained at the level of the interradicular bone of the medial roots of the left first molar, and stained with hematoxylin and eosin (H & E). Bone tissue density and bone remodeling were determined histomorphometrically. Body weight, food intake, hematocrit, and hemoglobinemia were also recorded. RESULTS: Microscopic observation revealed that osteogenesis was lower in rats fed a choline-deficient diet, at both 15 and 30 days, and that this decrease did not revert with a control diet. Histomorphometric evaluation showed 37% and 27% reduction in bone tissue density at 15 and 30 days, respectively, and a 30% decrease in bone formation at 30 days, compared to controls. CONCLUSION: In this experimental model, a choline-deficient diet led to altered bone remodeling as observed by a marked reduction in osteogenesis.     

Mandibular reconstruction with bone transport in a patient with osteogenesis imperfecta

Osteogenesis imperfecta (OI) was originally considered a connective tissue disorder, primarily involving type 1 collagen. It is characterized by numerous skeletal and extraskeletal defects, including bone fragility, multiple fractures, blue sclerae, hearing deficits, skin and ligament laxity, and dentinogenesis imperfecta (DI). The authors describe a 24-year-old Japanese man with OI and DI who had an ossifying fibroma of the mandible. Segmental resection was performed, and the mandible was reconstructed by distraction osteogenesis with the transport segment technique. This is the first report to describe a patient with OI undergoing mandibular reconstruction with bone transport, to the authors' knowledge.     

Cortical bone regeneration with a synthetic cell-binding peptide: a histologic and histomorphometric pilot study

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix (ABM) coupled with a synthetic cell-binding peptide (P-15). This material has been reported to enhance bone formation in periodontal osseous defects. The aim of this study was to assess the effect of ABM/P-15 on the healing of cortical bone defects in rabbits. Five New Zealand rabbits were used. Two 8-mm bone defects were created in each tibia. Eight defects were filled with PepGen P-15, 8 defects with PepGen P-15 Flow, and 4 defects were used as a control group. A total of 20 defects were created. All rabbits were killed at 4 weeks. Block sections containing the defects were retrieved and the specimens processed for light microscopy examination. Newly formed bone was present in both test groups, whereas, in the control-group, only a scarce quantity of newly formed bone was present and the cortical defects had not been filled by the regenerated bone. Statistical evaluation showed that there were statistically significant differences between control sites and sites treated with P-15 and P-15 Flow (P = 0.0001), and also between sites treated with P-15 and P-15 Flow (P = 0.0001), respectively. No acute inflammatory infiltrate cells were visible in both of these groups. Both PepGen P-15 and PepGen P-15 Flow enhanced new bone formation in the cortical drilled defects, whereas control defects showed very little newly formed bone.     

Mandibular reconstruction with bone grafts.

A total of 23 patients with partly resected mandible were repaired with autogenous bone grafts from the iliac crest and ribs. The reasons for reconstruction are presented in Table 1. The grafts healed without complications in 21 cases. With the exception of two of the cases with gunshot wounds, all patients recovered good mobility of the jaw and satisfactory mandibular contours. The patients had been folloed up for 6 months to 11 years. Radiographic examination at the last examination showed that resorption of the graft had been only slight or moderate. Through marrow-spongious bone grafts are regarded as best from an osteogenetic point of view, our cases showed that good results can be achieved also with solid block grafts. The authors discuss the use of plate osteosynthesis without IMF instead of other types of graft fixation and IMF. In six cases where the area of the graft was loaded with a prosthesis, resorption was not more extensive than in the other cases.     

Early trabecular bone healing around titanium implants: a histologic study in rabbits

BACKGROUND: A detailed insight into the early healing response of trabecular bone to unloaded titanium implants is lacking. METHODS: Cylindrical implants were inserted in the tibial epiphysis of rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections and histomorphometrically analyzed. RESULTS: A hematoma was observed after 1 and 3 days of implant placement. In addition, small fragments of bone trabeculae were detected around the implant as a result of the implant installment procedure. Soon, osteoclasts were observed resorbing these fragments, whereas osteoblasts incorporated them in strands of new bone, thereby making them difficult to distinguish from day 7 onward. At that time, osteoblasts were detected at the edges of the preexisting bone, actively depositing new bone, resulting in maximal osteoid deposition around the implant after 28 days (58%). After 7 days of healing, the presence of basic remodeling units in the surrounding bone was already maximal (P <0.05 versus t = 1 and 3 days). This remodeling activity, together with the new bone formation, provided a firm anchoring of the implant in the trabecular bone. CONCLUSIONS: This study evaluated the early cellular events in trabecular bone surrounding titanium implants. The insertion of an implant into bone initiates a series of biologic processes, including the formation of a hematoma, shattered bone fragments adjacent to the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.     

Interimplant distance and crestal bone resorption: a histologic study in the canine mandible

Background: Crestal bone loss has been shown to occur around dental implants. This crestal bone resorption may determine a more apical position of the gingival margin. A clear trend of increased bone loss with increased interimplant distance has been reported. Purpose: The aim of the present study was to evaluate, in the canine mandible, the crestal bone behavior around dental implants inserted with different interimplant distances. Materials and Methods: Sandblasted and acid‐etched implants (Bone System, Milano, Italy) were placed in the mandibles of six beagle dogs. Each dog received 10 implants in the mandible (five in the right side and five in the left side). A total of 60 implants was used in this study. The implants were divided in four groups: group I, with a 2 mm interimplant distance; group II, with a 3 mm interimplant distance; group III, with a 4 mm interimplant distance; and group IV, with a 5 mm interimplant distance. The dogs were killed after 12 months. Results: No statistically significant differences were found in regard to vertical bone loss whereas on the contrary, statistically significant differences were found in regard to lateral bone loss (p= .0001). Statistically significant differences also were found in regard to vertical crestal bone loss (p= .0001). In fact vertical crestal bone loss decreased, from 1.98 mm in group I to 0.23 mm in group IV. Conclusions: The clinical significance of these data lies in the fact that the increased crestal bone loss results in an increase in the distance between the base of the contact points of the neighboring implants and the crest of bone, and this fact could determine whether the papilla is present or absent between two implants.     

Microcomputed and histologic evaluation of calvarial bone grafts: a pilot study in humans

Two evaluation techniques (histology and microcomputed tomography [micro-CT]) were synergistically applied to calvarial bone graft to verify whether additional bone information can be obtained for the assessment of bone grafts. Ten extensive bone defects in the anterior and posterior maxilla or mandible involving crestal bone were treated by grafted blocks and chips of autogenous calvarial bone. The grafts were fixed with lag screws and left to heal for 4 months. No complications were observed. At surgical reentry for implant placement, a cylindric bone biopsy of both graft and native bone was retrieved and analyzed with both micro-CT and standard histology. Two- and three-dimensional (2D, 3D) micro-CT analyses allowed bone connectivity indices to be evaluated. This is useful for estimating bone strength and observing bone structure. The integration of the grafted calvarial bone with the residual bone of the recipient site was considered satisfactory. Histologic analysis allowed observations to be made at a higher resolution. Calvarial bone grafts seem to have positive effects when used as grafting materials. The application of both histologic and micro-CT techniques allows a better evaluation of grafted bone by concurrently allowing 2D and 3D visual and morphometric analysis of bone vitality, structure, turnover, and strength.     

Mandibular augmentation in dogs with hydroxylapatite combined with demineralized bone

This study investigates the tissue response in dogs to mandibular augmentation with hydroxylapatite (HA) combined with demineralized bone. Thirty mongrel dogs underwent ridge augmentation with 3 ml of HA alone (HAO), HA combined with autogenous bone (HAB), or HA combined with demineralized bone (HAD). Bone was not found in the HAO augmented ridges through 52 weeks; bone was found in the HAB augmented ridges by 12 weeks, and the HAD augmented ridges had bone formation after 26 weeks. This study demonstrates that demineralized bone can induce osteogenesis within the HA augmented dog ridge, but it is delayed when compared to HAB augmentations.     

Efficacy of bovine bone mineral for alveolar augmentation: a human histologic study

The purpose of this study was to evaluate the osteoconductivity of bovine bone mineral in humans. Fifteen patients referred to a private specialist surgical practice were treated consecutively for the repair of alveolar defects, and/or ridge maintenance at the site of extraction sockets, prior to implantation. Bio-Oss xenograft (Geistlich Pharma, Wolhusen, Switzerland) was utilized as the principal grafting material. Bone cores were trephined out at the time of implant placement and processed and examined to evaluate the tissue response under the light microscope. A total of 22 trephines were processed for histomorphometric evaluation to calculate the mean percentage of bone, residual graft and connective tissue by area. In addition, the mean percentage bone-to-graft contact was also calculated. The mean percentage area of new bone formation was 26.9%, and the percentage of residual graft and connective tissue as 25.6% and 47.4% respectively. The mean percentage contact length between bone and residual graft was 34%. One implant placed into a site, which was histologically identified as having little new bone and, unusually, an inflammatory infiltrate, failed with mobility at abutment connection. All other implants were restored into function, with a survival rate at baseline of 97%.     

Crestal bone remodeling in loaded and unloaded implants and the microgap: a histologic study

PURPOSE: The aim of this study was to histologically evaluate the crestal bone response to loaded and unloaded implants in beagle dogs. MATERIALS AND METHODS: Sand-blasted and acid-etched implants (Bone System, Milano, Italy) were placed in the mandible of six beagle dogs. The two premolars and the first molars had been extracted 3 months previously. Each dog received 12 implants in the mandible, and a total of 72 implants were used in this study. Three months after implantation, second-stage surgeries were performed for placement of abutments or healing screws. Three dogs were killed after 6 months, and three dogs were killed after 12 months. All 72 implants were retrieved. RESULTS: No statistically significant differences were found in the amount of bone loss between test and control implants, both at 6 and 12 months. Statistically significant differences were found, in both groups, between the bone loss observed at 6 months and that found at 12 months. CONCLUSION: Loading does not seem to be a relevant factor in the peri-implant bone resorption observed during the first year of function. Our results support previous findings that bone crest level changes could depend on the location of the microgap.     

Maxillary sinus augmentation using a synthetic cell-binding peptide: a histologic and transmission electron microscopy case study in man

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix coupled with a synthetic cell-binding peptide (P-15). This material has improved bone formation in periodontal osseous defects and bone regenerative procedures. There were 3 specimens retrieved 18 months after a sinus lifting procedure using PepGen P-15. These specimens were treated to be observed under light microscopy and transmission electron microscopy. Light microscopy showed that most of the particles were surrounded by newly formed bone. In some areas, osteoid matrix was present. No acute inflammatory infiltrate was present. In transmission electron microscopy, all phases of bone formation (i.e., osteoid matrix, woven bone, and lamellar bone) were observed in the newly formed bone around the biomaterial particles. In some regions, this newly formed bone seemed to present interdigitations connecting to or entering into the particle surface. To our knowledge, this is the first report presenting data on transmission electron microscopy of PepGen P-15 used in a sinus augmentation procedure in man. Our results confirm previous reports on the clinical effectiveness of this material.     

Enhanced ridge preservation by bone mineral bound with collagen-binding synthetic oligopeptide: a clinical and histologic study in humans

Background: The ridge‐preservation technique has been applied with membrane alone or membrane plus graft. Synthetic peptides, mimicking bioactive growth factor or extracellular matrix protein, have been attempted to provide an active surface of the biomaterials in inducing bone formation while alleviating the limitations of whole protein such as short half‐life, immunologic responses. The aim of the present clinical study is to examine the osteogenic effect of synthetic oligopeptide–coated bone mineral compared to bone graft without peptide when applied with collagen membrane in a ridge‐preservation technique. Methods: Synthetic oligopeptide from the collagen‐binding domain of osteopontin was chemically synthesized and coated onto the surface of bone mineral particulates. Ridge preservations were performed at 44 extraction sites in 42 patients (20 males and 22 females). Analyses of clinical parameters and histomorphometric evaluations were conducted to compare the osteogenic effects of the grafts between baseline and 6 months. Results: In the bone grafts of the control group treated without synthetic peptide, new bone formation was only seen around borders and basal areas. However, new bone was observed broadly in the defects of the test group treated with synthetic peptide–coated bone mineral, as seen not only at peripheries but also in the central and coronal parts of bone cores in the defects. The average percentage of new bone formation was significantly higher in the test group (5.3% ± 8.3% versus 10.4% ± 4.6%). The contact percentages between the graft particles and the new bone were 8.2% ± 11.3% for the control group and 20.4% ± 7.5% for the test group (P <0.05). Conclusions: The ridge‐preservation approach using synthetic oligopeptide–coated bone mineral with collagen membrane effectively prevented the resorption of hard tissue with higher bone‐to‐graft contact, and the oligopeptide‐coated bone may be a choice for ridge‐preservation procedures while assuring new bone formation.