Bacterial Contamination Levels of Autogenous Bone Particles Collected by 3 Different Techniques for Harvesting Intraoral Bone Grafts

Effect of amoxicillin and clindamycin on the gene expression of markers involved in osteoblast physiology

Background/purpose

Amoxicillin and clindamycin are the most effective decontaminants for intraoral bone grafts before their application in bone regeneration without cytotoxic effects on osteoblasts, but their effects on the gene expression of markers involved in osteoblast growth and differentiation remain unclear. The study objective was to determine the effects of amoxicillin and clindamycin on the gene expression of markers involved in osteoblast growth and differentiation.

Materials and methods

Real-time polymerase chain reaction (RT-PCR) was performed to explore the effect of 150 μg/mL clindamycin or 400 μg/mL amoxicillin on the gene expression by primary human osteoblasts (HOBs) of runt-related transcription factor 2 (Runx-2), osterix (OSX), alkaline phosphatase (ALP), osteocalcin (OSC), osteoprotegerin (OPG), receptor activator for nuclear factor κ B ligand (RANKL), type I collagen (Col-I), bone morphogenetic proteins 2 and 7 (BMP-2 and BMP-7), TGF-β1 and TGF-β receptors (TGF-βR1, TGF-βR2, and TGF-βR3), and vascular endothelial growth factor (VEGF).

Results

Treatment with 150 μg/mL clindamycin significantly increased the gene expression of TFG-β1, TGF-βR1, TGF-βR2, TGF-βR3, RUNX-2, Col-1, OSX, OSC, BMP-2, BMP-7, ALP, VEGF, and RANKL by HOBs. Treatment with 400 μg/mL amoxicillin significantly increased the gene expression of TGF-β R1, Col-I, OSC, RANKL, and OPG alone.

Conclusion

These findings suggest that 150 μg/mL clindamycin is the decontaminant of choice to treat intraoral bone grafts before their application in bone regeneration. The osteogenic and antibacterial properties of clindamycin can favor and accelerate the integration of bone grafts in the oral cavity.

Optimized bone grafting

Bone grafting is routinely performed in periodontology and oral surgery to fill bone voids. While autogenous bone is considered the gold standard because of its regenerative properties, allografts and xenografts have more commonly been utilized owing to their availability as well as their differential regenerative/biomechanical properties. In particular, xenografts are sintered at high temperatures, which allows for their slower degradation and resorption rates and/or nonresorbable features. As a result, clinicians have combined xenografts with other classes of bone grafts (most notably allografts and autografts in various ratios) for procedures requiring better long-term stability, such as contour grafting, sinus elevation procedures, and vertical bone augmentations. This review addresses the regenerative properties of each class of bone grafts and then highlights the importance of understanding each of their biomechanical and regenerative properties for clinical applications, including extraction site management, contour augmentation, sinus grafting, and horizontal and vertical augmentation procedures. Thereafter, an introduction toward the novel production of nonresorbable bone allografts (NRBAs) via high-temperature sintering is presented. These NRBAs not only pose the advantage of being more biocompatible than xenografts owing to their origin (human vs. animal bone) but also display nonresorbable properties similar to those of xenografts. Thus, while packaging allografts with xenografts in premixtures specific to various clinical indications has never been permitted owing to cross-species contamination and FDA/CE requirements, the discovery and production of NRBAs allows premixing with standard allografts in various ratios without regulatory restrictions. Therefore, premixtures of allografts with NRBAs can be produced in various ratios for specific indications (e.g., a 1:1 ratio similar to an allograft/xenograft mixture for sinus grafting) without the need for purchasing separate classes of bone grafts. This optimized form of bone grafting could theoretically provide clinicians more precise ratios without the need to purchase separate bone grafts. This review highlights the future potential for simplified and optimized bone grafting in periodontology and implant dentistry.

A novel technique to harvest bone autografts with mild local hyperthermia and enhanced osteogenic bone quality: a preclinical study in dogs

BACKGROUND

Guided bone regeneration (GBR) involves collecting bone autografts with high bio-quality and efficiency. The current non-irrigated low-speed drilling has been limited for broader application in bone autograft harvest due to its low efficiency, inability to conduct buccal cortical perforation, and dependence on simultaneous implant placement. Increasing the drilling speed helps improve the efficiency but may incur thermal-mechanical bone damage. Most studies have addressed thermal reactions during bone drilling on non-vital models, which is irrelevant to clinical scenarios. Little has been known about bone's in vivo thermal profiles under non-irrigated higher-speed drilling and its influences on the resulting bone chips.

AIM

A novel technique for bone harvest and cortical perforation via in-situ non-irrigated higher-speed drilling was proposed and investigated for the first time.

METHODS

The third mandible premolars of eight beagles were extracted and healed for three months. Sixteen partial edentulous sites (left and right) were randomized into four groups for bone autograft harvest without irrigation: chisel, 50 rpm drilling, 500 rpm drilling, and 1000 rpm drilling. Bone chips were harvested on the buccal plates of the missing tooth. An infrared camera and an implantable thermocouple collaboratively monitored in vivo real-time bone temperature at the drilling sites. In vitro performances of cells from bone chips, including cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, mRNA transcriptional level of osteogenic genes and heat shock protein 70 (HSP-70), and HSP-70 expression at the protein level were also studied.

RESULTS

500 rpm produced mild local hyperthermia with a 2-6 °C temperature rise both on the cortical surface and inside the cortical bone. It also held comparable or enhanced cell performances such as cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, and osteogenic genes expression.

CONCLUSIONS

In-situ non-irrigated higher-speed drilling at 500 rpm using a screw drill is versatile, efficient, and thermal friendly and improves the bio-quality of bone chips. Our novel technique holds clinical translational potential in GBR application.

Socket Preservation Using Xenograft Does Not Impair Implant Primary Stability in Sheep: Clinical, Histological, and Histomorphometric Study

Implant primary stability, which depends mainly on the amount and quality of bone, is important for implant survival. Socket preservation aims to reduce bone volumetric changes after tooth extraction. This animal study aims to examine whether preserving a ridge by using xenograft impairs the primary stability of the implant. Eighteen artificial bone defects were prepared in 4 sheep (5- and 8-mm length). Defects were randomly grafted with xenografts: Bio-Oss (BO), Bio-Active bone (BB), or left for natural healing (control). After 8 weeks, bone biopsy was harvested and dental implants installed. During installation, peak insertion torque (IT) was measured by hand ratchet, and primary stability by the Osstell method. Histomorphometric analysis showed a higher percentage of new bone formation in the naturally healed defects compared to sites with xenograft (control: 68.66 ± 4.5%, BB: 48.75 ± 4.34%, BO: 50.33 ± 4.0%). Connective tissue portion was higher in the BO and BB groups compared to control (44.25 ± 2.98%, 41 ± 6%, and 31.33 ± 4.5%, P < .05, respectively). Residual grafting material was similar in BO and BB (7 ± 2.44%, 8.66 ± 2.1%, respectively). Mean IT and implant stability quotient (ISQ) values were not statistically different among the groups. A positive correlation was found between IT and ISQ (r = 0.65, P = 0). In conclusion, previously grafted defects with xenograft did not influence primary stability and implant insertion torque in delayed implant placement. These results may be attributed to a relatively high bone fill of the defect (∼50%) 2 months after grafting.

The influence of alveolar bone healing degree on its potential as a source of human alveolar bone-derived cells

BACKGROUND

The concept of bone tissue engineering has emerged as a novel alternative approach that comprises three essential components: osteogenic cells, osteoinductive signals and osteoconductive scaffolds. The low-speed drilling represents a useful and accessible autologous source for human alveolar bone-derived cells (hABCs). The aim of this study was to compare the efficacy of two donor sites (healing sites (HS) and non-augmented healed sites (NAHS)) as a source of hABCs.

METHODS

Nineteen patients were enrolled in this study. The patients' demographic data were described. Bone type and dental implant location were also determined. The hABCs obtained were characterized. Apoptosis and sclerostin expression in the samples were also assessed with immunohistochemistry.

RESULTS

The hABCs left earlier the tissue explants of the HS than the NAHS. The proliferation of the hABCs had reached the sub-confluence stage in both groups. Cellular efficacy was not statistically significant between the two groups. The hABCs exhibited osteogenic phenotype as they expressed bone sialoprotein (BSP), osteopontin (OP) and tissue non-specific alkaline phosphatase (TNAP). In both groups, the level and the distribution pattern of apoptotic cells and sclerostin expression were similar.

CONCLUSIONS

Within the limitations of this study, both HS and NAHS were similarly effective to provide hABCs.

Microbiological analysis of autologous bone particles obtained by low-speed drilling and treated with different decontamination agents

The aim of this study was to compare the effectiveness of three agents - two antibiotics (amoxicillin and clindamycin) and an antiseptic (chlorhexidine) - to decontaminate bone grafts obtained by low-speed drilling. The study included 248 bone tissue samples harvested from 62 patients by low-speed drilling before dental implant placement. Each of four samples obtained from every patient was dropped, using a sterile instrument, into a sterile tube containing a 500-μl solution of 400μg/mL amoxicillin, 150μg/mL clindamycin, 0.12% chlorhexidine, or physiological saline for 1min. The number of colony-forming units (CFU) was determined at 48h of culture. The use of clindamycin, amoxicillin, or chlorhexidine as decontaminant for 1min significantly reduced the CFU count when compared to physiological saline (control agent). In both anaerobic and CO₂-rich atmospheres, significant differences in CFU/mL were found between the control and chlorhexidine groups (P<0.001), control and amoxicillin groups (P<0.001), control and clindamycin groups (P<0.001), chlorhexidine and amoxicillin groups (P<0.0001), and chlorhexidine and clindamycin groups (P<0.0001). In conclusion, clindamycin had the highest decontaminating effect on bone particles obtained by low-speed drilling, followed by chlorhexidine and amoxicillin. Clindamycin may therefore be a valid alternative option for the routine decontamination of intraoral bone grafts.

The Influence of Thrust Force on the Vitality of Bone Chips Harvested for Autologous Augmentation during Dental Implantation

Bone drill chips that are collected during implant site preparation can be reused as autologous bone-grafting material for alveolar ridge augmentation. This study characterized five market-leading implant drill sets regarding their geometric properties and ability to produce vital bone chips. The drill geometry of each tool of five commercial implant drill sets was characterized while using optical profile projector devices and SEM. Bone chips were collected during the in vitro preparation of porcine jaw bone with the various drill sets. Produced bone chip masses were measured. The bone chips were cultured in vitro and the number of outgrown cells was determined and measurand for vitality. Furthermore, the thrust force and cutting torque were recorded to examine the mechanical loads of the manual drilling process. The tool geometry and set configuration of one out of five implant drill sets appears to be superior regarding chip mass, vitality, and thrust force. It could be proven that there is a correlation between vitality and thrust force. The thrust force is influenced by the cutting behavior of the tool, which in turn depends on the geometry of the tool. The tool geometry has an influence on the vitality of the augmentation material due to this relationship.

Increasing the Stability of Dental Implants: the Concept of Osseodensification

One of the most important factors that affect osseointegration is the primary stability of the implant. Dental implants inserted at the posterior region of the maxilla exhibit the lowest success rates as the low density bone in this area often jeopardize rigid fixation of the implant. Many surgical techniques have been developed to increase the primary stability of an implant placed in low density bone, such as bicortical fixation of the implant, undersized preparation of the implant bed and bone condensation by the use of osteotomes. A new promising technique, named osseodensification, has been recently developed that creates an autograft layer of condensed bone at the periphery of the implant bed by the aid of specially designed burs rotating in a clockwise and anti-clockwise direction. The purpose of this review is to emphasize that implant primary stability is strongly influenced by the surgical technique, to quote and briefly analyse the various surgical procedures laying weight to osseodensification procedure.

Osteogenic potential of three different autogenous bone particles harvested during implant surgery

OBJECTIVES

The aim was to compare the osteoblast activity and osteogenic potential of autogenous bone particles harvested using three different techniques and determine the most advantageous method of collecting autogenous bone particles.

SUBJECTS AND METHODS

Bone particles were harvested from 20 patients during dental implant surgery using bone scraping, low-speed drilling and bone trap filtering. After the osteoblasts were cultured, cell proliferation, migration, mineralization, transcription of osteogenesis-related genes, secretion of osteogenesis-related proteins and osteoinductive protein content in the bone particle matrix were evaluated.

RESULTS

Osteoblast activity and osteogenic potential were higher in bone samples harvested by scraper or low-speed drilling than in samples harvested by bone trap filter. Although these parameters were slightly lower in the low-speed drilling group than in the scraper group, significant differences were found only in bone Gla protein levels. However, the levels of osteoinductive proteins in the bone particle matrix were significantly higher in the low-speed drilling group than in the scraper group.

CONCLUSIONS

Low-speed drilling is a recommendable and effective technique for collecting autogenous bone particles. In implant operations, low-speed drilling can be considered the first-line option, and if the quantity of harvested bone is insufficient, bone shavings obtained by the scraper may be considered.

Risk Factor Analysis of Graft Failure With Concomitant Cyst Enucleation of the Jaw Bone: A Retrospective Multicenter Study

PURPOSE

Cysts are common pathologic entities in the oral and maxillofacial region. Enucleation is commonly used for treatment and is occasionally followed by bone grafting. However, no studies have evaluated factors affecting the failure of grafts used for cystic defects in the oral and maxillofacial region. Therefore, the present study was conducted to determine the risk factors for postoperative graft failure in patients treated with cyst enucleation and simultaneous bone grafting.

MATERIALS AND METHODS

Clinical data for 305 patients who had undergone cyst enucleation with simultaneous bone grafting were retrospectively investigated in this multicenter case-and-control study. The predictor variables included host, pathologic, and treatment factors. The outcome variable was success or failure of the bone graft. Descriptive statistics were computed, and the P value was set at .05.

RESULTS

Bone graft failure was observed in 48 cases. The mean duration from surgery to failure was 38.7 days. Multivariable logistic regression analysis showed a significant association between graft failure and younger age (odds ratio [OR] = 1.033; P = .016), smoking (OR = 2.598; P = .017), preoperative infection (OR = 4.660; P = .001), large cysts (OR = 1.052; P = .010), impaction of the mandibular third molar in the cystic cavity (OR = 3.021; P = .007), perilesional osteosclerosis (OR = 4.973; P = .001), and the use of mixed non-autogenous and autogenous bone grafts (OR = 3.891; P = .007).

CONCLUSIONS

This study provides a list of important factors that should be considered by clinicians planning enucleation and simultaneous bone grafting for cysts in the oral and maxillofacial region.