Human Bone Repair After Mandibular Symphysis Block Harvesting: A Clinical and Tomographic Study

Spontaneous regeneration of bone following mandibular ramus bone harvesting: a CBCT analysis

The aim of this study was to evaluate healing at the donor site following autogenous block graft harvesting from the mandibular ramus. In this retrospective study, cone beam computed tomography images taken at different time-points were examined, and the volumes of preoperative and postoperative regions of interest were calculated in the software. Images were classified into four groups: 0-3 months, 4-6 months, 7-12 months, and >12 months post-surgery. To characterize the healing process over time, statistical analyses were conducted for both the 70% and 80% healing thresholds. Nearly half (n = 15, 47%) of the 32 patients included in this study achieved 70% bone healing within 4-12 months post-surgery. At the end of the 28-month period covered by this study, 21 patients (66%) had achieved 70% bone healing. The median time to achieve 70% healing was 9 months, while the median time to achieve 80% healing was 28 months. The findings of this study validate the feasibility of reutilizing the mandibular ramus area for additional bone augmentation when other intraoral sites are unavailable.

Review of the Literature on the Current State of Periosteum-Mediated Craniofacial Bone Regeneration

Study Design

This is an article review on the current state of periosteum-mediated bone regeneration (PMBR). It is a known mandibular reconstruction option in children, and though poorly understood and unpredictable, the concerns of developmental changes to donor and recipient tissues shared by other treatment options are nonexistent. The definitive role of periosteum during bone regeneration remains largely unknown.

Objective

The objective is to review the literature on the clinical and molecular mechanism evidence of this event.

Methods

Our search methodology was modeled after the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Search strategies were categorized into search 1 for clinical evidence of mandibular regeneration and search 2 for gene expression review for craniofacial regeneration. The quality assessment of each publication was undertaken, and inclusion criteria comprise mandibular continuity defect for search 1 and use of gene expression assay propriety kit for search 2.

Results

33 studies were selected for search 1 while four studies with non-human subjects were selected for search 2. Monitoring of PMBR onset was advised at 2 weeks post-operative, and the gene expression results showed an upregulation of genes responsible for angiogenesis, cytokine activities, and immune-inflammatory response in week 1 and skeletal development and signaling pathways in week 2.

Conclusions

The results suggest that young periosteum has a higher probability of PMBR than adult periosteum, and skeletal morphogenesis regulated by skeletal developmental genes and pathways may characterize the gene expression patterns of PMBR.

Autologous bone harvested during implant bed preparation: A randomized clinical trial comparing high-speed drilling with irrigation versus low-speed drilling without irrigation

OBJECTIVE

To compare collected bone weight and the frequency of autologous bone harvesting from the flutes of surgical drills used for implant bed preparation using two different drilling techniques. A comparative evaluation of radiographic bone density and bone quality was also made.

MATERIALS AND METHODS

A randomized clinical trial was made of 66 dental implants in patients with a single posterior edentulous site. The compared drilling techniques were high-speed drilling with irrigation (control group) and low-speed drilling without irrigation (test group). The bone collected in both groups was dried and weighed with a precise electronic balance. The frequency of harvesting was calculated. The median radiographic bone density of each implant site was measured using cone-beam computed tomography (CBCT) pixel values. Patient sex, age, implant position and dimensions, as well as the last drill diameter were analyzed as independent variables. The level of significance was 5%.

RESULTS

The harvesting of bone chips from drill flutes proved possible in 51.5% of the procedures in the control group and in 100% in the test group (p < 0.001). There were also statistically significant differences in bone weight between the control group (6.7 ± 10.6 mg) and the test group (41.9 ± 30.3 mg) (p < 0.001). The CBCT pixel values were directly correlated with the collected bone weight in both groups. The median radiographic bone density, arch and last drill diameter were significantly associated with harvesting bone frequency and collected bone weight (p < 0.05).

CONCLUSIONS

Our findings suggest that the frequency and weight of autologous bone harvested from drills are greater with low-speed drilling without irrigation than with high-speed drilling with irrigation. Radiographic bone density, arch and last drill diameter also significantly influenced the harvesting outcomes.

Computer-Assisted Evaluation Confirms Spontaneous Healing of Donor Site One Year following Bone Block Harvesting from Mandibular Retromolar Region-A Cohort Study

Bone augmentation prior to dental implant placement is a common scenario in the dental implantology field. Among the important intraoral harvesting sites to obtain bone blocks is the ramus/retromolar region that has a high success rate and long-lasting alveolar ridge augmentation. Preserving the bone volume and quality at the donor site is crucial for preventing further complications or to serve as a site for re-harvesting. Healing of the intraoral donor sites has been described in the maxillofacial field. This study aimed to evaluate the spontaneous healing of the mandibular retromolar donor site utilizing computer-assisted quantification 6 and 12 months after bone harvesting.

MATERIALS AND METHODS

The study was conducted on patients who underwent an alveolar ridge augmentation using an intraoral retromolar bone graft. Three CBCT scans were performed-intraoperative, and at six months and one year after the surgical procedure. By using the Materialise Mimics Innovation Suite software 26.0 features segmentation by thresholding, Hounsfield unit averaging, and superimposition of the tomographies, we could precisely quantify the healing process utilizing spatial and characteristic measures.

RESULTS

In all cases, the computer-aided quantification showed that six months following surgery, the donor site had recovered up to 64.5% ± 4.24 of its initial volume, and this recovery increased to 89.2% ± 2.6 after one year. Moreover, the Hounsfield unit averaging confirmed dynamic bone quality healing, starting at 690.3 ± 81 HU for the bone block, decreasing to 102 ± 27.8 HU at six months postoperatively, and improving to 453.9 ± 91.4 HU at the donor site after a year.

CONCLUSIONS

This study demonstrates that there is no need for additional replanting at the donor site following retromolar bone block harvesting, whether autogenous or allograft, since spontaneous healing occurs 12 months following the surgery.

Three-Dimensional Analysis of Bone Volume Change at Donor Sites in Mandibular Body Bone Block Grafts by a Computer-Assisted Automatic Registration Method: A Retrospective Study

This study aimed to evaluate the bone volume change at donor sites in patients who received mandibular body bone block grafts using intensity-based automatic image registration. A retrospective study was conducted with 32 patients who received mandibular bone block grafts between 2017 and 2019 at the Pusan National University Dental Hospital. Cone-beam computed tomography (CBCT) images were obtained before surgery (T0), 1 day after surgery (T1), and 4 months after surgery (T2). Scattered artefacts were removed by manual segmentation. The T0 image was used as the reference image for registration of T1 and T2 images using intensity-based registration. A total of 32 donor sites were analyzed three-dimensionally. The volume and pixel value of the bones were measured and analyzed. The mean regenerated bone volume rate on follow-up images (T2) was 34.87% ± 17.11%. However, no statistically significant differences of regenerated bone volume were noted among the four areas of the donor site (upper anterior, upper posterior, lower anterior, and lower posterior). The mean pixel value rate of the follow-up images (T2) was 78.99% ± 16.9% compared with that of T1, which was statistically significant (p < 0.05). Intensity-based registration with histogram matching showed that newly generated bone is generally qualitatively and quantitatively poorer than the original bone, thus revealing the feasibility of pixel value to evaluate bone quality in CBCT images. Considering the bone mass recovered in this study, 4 months may not be sufficient for a second harvesting, and a longer period of follow-up is required.

Facial cortical bone regeneration post-extraction in non-grafted sockets allows for early implant placement and long-term functional stability

OBJECTIVE

To evaluate posterior implant placement feasibility shortly after tooth extraction in non-grafted sockets with and without dehiscence at the time of extraction.

DESIGN

Ninety-five patients requiring posterior extractions entered this cross-sectional study. They were divided in three groups after extraction: G1 without dehiscence, G2 with dehiscence ≤5 and G3 > 5 mm. CBCT were taken prior to implant placement at an average of 12-weeks post-extraction to evaluate the need for grafting, cortical bone formation and bucco-lingual width (BLW). Actual BLW (n = 60) were compared to minimum expected BLW in 3 scenarios of BLW thickness averaging 6.4-7.4-8.4 mm. Peri-implant tissues were assessed for pocket formation and inflammation following established success criteria.

RESULTS

New cortical bone formation and sufficient BLW made implant placement feasible in sites with and without dehiscence at the time of extraction after an average healing time of 11.9 ± 2.4weeks (range: 8-18). Total average CBCT BLW was 10.1 ± 1.6 mm. All groups had a significantly higher BLW, than scenarios 1-3 (p < 0.0001). Molars were 20 times more likely than premolars to heal with BLW>10 mm (OR = 20; RR = 4.2; CI95 %: 5.3-74.2; p < 0.0001). Dehiscence sockets were 1.5 times more likely than non-dehiscenced sockets to present BLW ≤ 10 mm (OR = 1.5; RR = 0.6; CI95 %:0.9-2.5; p = 0.08). A band of keratinized tissue was present in all implants and success rates were 100 % at an average follow-up of 51.0 ± 23.4 months.

CONCLUSION

Implant placement is feasible without socket grafting shortly after tooth extraction. Non-grafted sockets present a significant osteogenic potential. Dehiscence sockets are likely to self-repair by forming a new cortical plate. The unassisted regenerated intra-socket bone allows for functional implant stability long-term.

Alternative intraoral donor sites to the chin and mandibular body-ramus

Background

Provide a review of alternative intraoral donor sites to the chin and body-ramus of the mandible that bring fewer complications and that may be used to regenerate small and medium defects.

Material and Methods

A review was conducted using the search engine PUBMED and looking manually into scientific journals.

Results

From the 35 articles included, 6 corresponded to the coronoids, 3 corresponded to the zygomatic body, 5 corresponded to the anterior maxillary sinus wall, 3 corresponded to the zygomatic alveolar process, 2 corresponded to the incisive fossa, 2 corresponded to the anterior nasal spine, 2 corresponded to the palatal region, 5 corresponded to the tuberosity, and 7 corresponded to the palatal and mandibular tori.

Conclusions

Although there are few complications described when using alternative intraoral donor sites, the main problem with these types of grafts is their scarce bone volume, with only the zygomatic body, anterior sinus wall, and palate sites being able to be used in medium defects. More clinical trials are necessary in order to evaluate the behavior of the alternative donor sites over time. Key words:Grafting, autologous bone, autografts, mandible, maxilla, palate hard, zygoma.

Early volumetric changes after vertical augmentation of the atrophic posterior mandible with interpositional block graft versus onlay bone graft: A retrospective radiological study

PURPOSE

The aim of this study was to evaluate volumetric and clinical outcomes of atrophic posterior mandibles treated with inlay or onlay bone grafting techniques.

MATERIALS AND METHODS

In posterior mandibles, alveolar ridges were treated either with interpositional equine cancellous bone block (inlay group) or with onlay autogenous bone block (onlay group). Bone volumes at baseline and at 4 months after surgery were measured by computed tomography.

RESULTS

A total of 20 subjects were enrolled in the present study: 10 in the inlay group and 10 in the onlay group. After surgery, atrophic posterior mandibles showed a mean vertical augmentation height of 6.0 mm in the inlay group and 7.4 mm in the onlay group. No significant differences were recorded between the two groups regarding volume loss of the grafted bone or decrease in vertical bone height of the augmented site (29% and 1.9 mm for the onlay group, and 35% and 1.7 mm for the inlay group) during healing. Two complications (1 wound dehiscence and 1 mandibular fracture) occurred postoperatively in the inlay group; on the other hand, the onlay group had three complications (wound dehiscence). A total of 80 dental implants were placed in augmented areas: 46 in the inlay group with a peri-implant marginal bone loss of 0.8 mm, and 34 in the onlay group with a peri-implant marginal bone loss of 1.3 mm (p = 0.0006).

CONCLUSIONS

Inlay xenogeneic grafts showed volumetric bone remodeling similar to that recorded for onlay autogenous bone. The success of the autogenous onlay blocks (82.4%) appeared to be lower than that registered for the inlay group (93.8%), but the difference was not significant.

Autogenous bone block grafting provides facial implant tissue stability long-term

BACKGROUND

Mucosal recession (MR) and bone loss can compromise anterior implant esthetics.

PURPOSE

To evaluate tissue stability and clinical outcomes of anterior implants augmented with autogenous block transplants long-term.

MATERIALS AND METHODS

This prospective cross-sectional clinical study analyzed facial tissue recession of anterior implants augmented with autogenous bone blocks and compared them to adjacent teeth in forty patients 52 months post-augmentation. Clinical parameters, MR and implant transparency, were assessed at delivery and follow-up. The hypothesis is that the facial mucosa of augmented implant sites is more resistant to trauma than the gingival margins of adjacent teeth.

RESULTS

Teeth were seven times more likely to present a facial recession than adjacent augmented implants at 52-month follow-up (RR: 7; P < .001; 95%CI: 2.7-18.0). Augmented implant sites were six times more likely to present "no-tissue-recession" than adjacent teeth (RR: 6.2; P < .001; 95%CI: 2.4-15.7). Mean tooth facial tissue recession was significantly higher than adjacent implants, 1.18 ± 1.05 mm (range: 0-3.5 mm) vs. 0.06 ± 0.2 mm (95%CI: 0.8-1.5; P < .0001). Thick biotype teeth were 2 times more resistant to recession than thin biotype teeth (RR: 2.03; P = .03; 95%CI: 1.2-3.5). Implant success rates were 100%. Lack of transparency and MR at facial implant sites lasted an average of 52 months and up to 144 without signs of inflammation or pocket formation regardless of the individual's biotype. Facial bone thicknesses of 2.2 mm seem optimal for tissue stability.

CONCLUSIONS

Autogenous bone block augmentation with staged implant placement seems to be a predictable, short-healing, reconstructive protocol in the esthetic zone maintaining stable peri-implant tissues long-term. Implant augmented sites seem more resistant to develop a recession than adjacent teeth.

Translating Periosteum's Regenerative Power: Insights From Quantitative Analysis of Tissue Genesis With a Periosteum Substitute Implant

: An abundance of surgical studies during the past 2 centuries provide empirical evidence of periosteum's regenerative power for reconstructing tissues as diverse as trachea and bone. This study aimed to develop quantitative, efficacy-based measures, thereby providing translational guidelines for the use of periosteum to harness the body's own healing potential and generate target tissues. The current study quantitatively and qualitatively demonstrated tissue generation modulated by a periosteum substitute membrane that replicates the structural constituents of native periosteum (elastin, collagen, progenitor cells) and its barrier, extracellular, and cellular properties. It shows the potentiation of the periosteum's regenerative capacity through the progenitor cells that inhabit the tissue, biological factors intrinsic to the extracellular matrix of periosteum, and mechanobiological factors related to implant design and implementation. In contrast to the direct intramembranous bone generated in defects surrounded by patent periosteum in situ, tissue generation in bone defects bounded by the periosteum substitute implant occurred primarily via endochondral mechanisms whereby cartilage was first generated and then converted to bone. In addition, in defects treated with the periosteum substitute, tissue generation was highest along the major centroidal axis, which is most resistant to prevailing bending loads. Taken together, these data indicate the possibility of designing modular periosteum substitute implants that can be tuned for vectorial and spatiotemporal delivery of biological agents and facilitation of target tissue genesis for diverse surgical scenarios and regenerative medicine approaches. It also underscores the potential to develop physical therapy protocols to maximize tissue genesis via the implant's mechanoactive properties.

SIGNIFICANCE

In the past 2 centuries, the periosteum, a niche for stem cells and super-smart biological material, has been used empirically in surgery to repair tissues as diverse as trachea and bone. In the past 25 years, the number of articles indexed in PubMed for the keywords "periosteum and tissue engineering" and "periosteum and regenerative medicine" has burgeoned. Yet the biggest limitation to the prescriptive use of periosteum is lack of easy access, giving impetus to the development of periosteum substitutes. Recent studies have opened up the possibility to bank periosteal tissues (e.g., from the femoral neck during routine resection for implantation of hip replacements). This study used an interdisciplinary, quantitative approach to assess tissue genesis in modular periosteum substitute implants, with the aim to provide translational strategies for regenerative medicine and tissue engineering.

Histopathological comparative analysis of periimplant bone inflammatory response after dental implant insertion using flap and flapless surgical technique. An experimental study in pigs

AIM

To evaluate by histopathological analysis the peri-implant bone inflammation degree, in certain time intervals (7, 14, 21 and 28 days), following mini-incision flapless and flap implant placement.

MATERIAL AND METHODS

The experiment was conducted on four domestic pigs. Nine weeks prior to implant insertion, second and third mandibular premolars were extracted. Each animal received six implants in lower jaw. On one randomly chosen side of jaw flapless technique using mini-incision was performed, while on the other side implants were inserted after flap raising. After 7, 14, 21, and 28 days, the experimental animals were sacrificed. Following mandibular resection and decalcification, the samples for histopathological analysis of the peri-implant bone were obtained in the empty implant bed area, from the buccal side of the mandible, adjacent to implant neck region and parallel to crestal edge of implant bed. The degree of inflammatory response of the peri-implant bone was estimated through ordinal scores from 0 to 2.

RESULTS

Seven days after the surgery all samples in the flap group had score 2 indicating high inflammation degree, in contrast to lower inflammatory reaction in flapless group. On the 14th and 21st postoperative day decreasing of inflammation degree was noted in all samples of the flapless group (score 1), while in flap group samples presented scores 1 and 2. Twenty-eight days after the implant placement, further reduction of inflammation in the flapless group (33% of samples had score 0) was observed.

CONCLUSION

Flapless technique in comparison to conventional flap procedure minimizes postoperative bone inflammatory reactions.

Spontaneous Regeneration of the Mandible: An Institutional Audit of Regenerated Bone and Osteocompetent Periosteum

PURPOSE

Childhood mandibular lesions are frequently benign; this allows for a conservative surgical approach to their management. Two of the most common approaches for reconstruction of acquired mandibular defects in adolescents are vascularized and nonvascularized osseous flaps or grafts. A third, less commonly used treatment option often used in developing parts of the world that some Western centers are considering as part of their treatment algorithm is spontaneous bone regeneration. This study reports on the authors' experiences with spontaneous bone formation of the resected young mandible. It also attempts to quantify any relation between spontaneous bone regeneration and an aging osteocompetent periosteum.

PATIENTS AND METHODS

This was a retrospective study based on consecutive data collated from records of the oral and maxillofacial surgery departments from 2 tertiary institutions. Eligible patients were no older than 18 years and had benign mandibular neoplasms. The surgical procedure was mandibulectomy with subperiosteal dissection and intermaxillary fixation. Regenerated bone evaluation was by clinical examination and periodic panoramic radiographs.

RESULTS

Sixteen consecutive cases with mandibular lesions were seen at the 2 institutions, 8 of which met the inclusion criteria. The average age was 10.75 years. The predominant pathology was unicystic ameloblastoma. All cases exhibited spontaneous bone regeneration, with 2 cases exhibiting "incomplete" bone regeneration.

CONCLUSION

Immediate reconstruction can be delayed to allow for spontaneous bone regeneration of defects in young patients. In the absence of regeneration, secondary reconstruction can be considered. Although the literature reports more young patients with bone regeneration than adults, increasing age during childhood and adolescence might not necessarily indicate a decrease in periosteal bone-regenerating potential.

Tomographic follow-up of bone regeneration after bone block harvesting from the mandibular ramus

Autogenous bone is still considered the gold standard, and the applicability of autogenous bone grafts is well established. However, the possibility of second harvesting from the same donor region remains unclear. The aim of this study was to perform a prospective evaluation of hard tissue deposition in the mandibular ramus after bone block harvesting using cone beam computed tomography (CBCT). Twenty-two patients with indications for augmentation procedures using autogenous bone from the mandibular ramus were selected. Three CBCT scans were performed with a tomographic guide before bone harvesting (T1) and at 14 days (T2) and 6 months (T3) after the surgical procedures. Measurements were obtained in 2D (area, mm(2)) and 3D (volume, mm(3)), and were subsequently compared. In the 2D analysis, the mean bone formation rate was 56%, while for the 3D analysis the mean rate was 9.7%. Despite this difference, there was a significant correlation between area and volume measurements. Our findings demonstrated the presence of hard tissue in the mandibular ramus at 6 months after bone harvesting, which suggests that it would be possible to reuse the same region for a second block harvesting. However, the second bone harvesting would involve less bone for transplantation when compared to the first bone harvesting.

Volume changes of iliac crest autogenous bone grafts after vertical and horizontal alveolar ridge augmentation of atrophic maxillas and mandibles: a 6-year computerized tomographic follow-up

PURPOSE

To evaluate by computerized tomography the long-term volume resorption of autogenous corticocancellous grafted bone harvested from the ilium and used in an alveolar augmentation procedure followed by endosseous dental implant placement.

PATIENTS AND METHODS

Eleven maxillary grafts (8 positioned horizontally) and 13 mandibular grafts (10 positioned vertically) were placed in 16 patients. Using software programs, pre- and postsurgical computerized tomographic scans were used to compare volumes of grafts over time (up to 6 yr) to determine the annual percentage of remaining bone and the overall percentage of bone resorption that could be expected. Yearly measurements of volumes and percentages of remaining bone were then compared statistically.

RESULTS

At the 6-year survey for blocks grafted in the mandible, an average resorption rate of 87% was obtained; for maxillary grafts at the same survey, complete resorption of the grafts (mean, 105.5%) was recorded. In general, bone resorption appeared slow, except for that recorded in the first 2 years of healing, the only period in which statistical comparisons among all time points showed significant differences for all variables.

CONCLUSIONS

Volumetric measurements of the grafts and their related percentages of remaining bone attested to a progressive and unavoidable bone resorption of almost all the grafted bone in the maxilla and mandible. Although the present data were from a heterogeneous group of defects treated with horizontal and vertical procedures, clinicians, when performing alveolar bone augmentation with an autogenous hip bone, should aim at titanium dental implant osseointegration, not only in the augmented bone but also in the native bone below the graft.

Exploring CBCT-based DICOM files. A systematic review on the properties of images used to evaluate maxillofacial bone grafts

Previous studies suggests that cone beam computerized tomography (CBCT) images could provide reliable information regarding the fate of bone grafts in the maxillofacial region, but no systematic information regarding the standardization of CBCT settings and properties is available, i.e., there is a lack of information on how the images were generated, exported, and analyzed when bone grafts were evaluated. The aim of this study was to (1) do a systematic review on which type of CBCT-based DICOM images have been used for the evaluation of the fate of bone grafts in humans and (2) use a software suggested in the literature to test DICOM-based data sets, exemplifying the effect of variation in selected parameters (windowing/contrast control, plane definition, slice thickness, and number of measured slices) on the final image characteristics. The results from review identified three publications that used CBCT to evaluate maxillofacial bone grafts in humans, and in which the methodology/results comprised at least one of the expected outcomes (image acquisition protocol, image reconstruction, and image generation information). The experimental shows how the influence of information that was missing in the retrieved papers, can influence the reproducibility and the validity of image measurements. Although the use of CBCT-based images for the evaluation of bone grafts in humans has become more common, this does not reflect on a better standardization of the developed studies. Parameters regarding image acquisition and reconstruction, while important, are not addressed in the proper way in the literature, compromising the reproducibility and scientific impact of the studies.

A comparative volumetric study of symphysis donor defects, unfilled or filled with bone substitute

OBJECTIVES

Background Intraoral autogenous bone grafts are a convenient source of bone in reconstruction of the residual ridge before dental implant placement.

PURPOSE

The aim of this study was to evaluate bone volume of symphysis donor defects filled with bone substitute compared with unfilled symphysis donor defects.

PATIENTS, MATERIALS AND METHODS

The study included 26 patients who underwent either alveolar ridge reconstruction or maxillary sinus elevation. Two groups were studied: symphyseal donor defects filled with bone substitute and unfilled symphyseal donor defects. Pre- and postoperative volumetric variables were determined using computed tomography scans and the software program SimPlant® (Materialise Dental Italia, Roma, Italy).

RESULTS

At 6 months postsurgery, the filled donor defects exhibited a significant increase in bone volume compared with unfilled donor defects (97.7% and 73.4%, respectively). At 18 months postsurgery, volume of unfilled donor defects was reevaluated with no significant increase in bone volume.

CONCLUSIONS

Six months following block harvesting procedure, filled donor defects maintained bone volume, while unfilled donor sites generated defects that cannot achieve full regeneration; even not 18 months postblock harvesting.

Bone microbial decontamination agents in osseous grafting: an in vitro study with fresh human explants

BACKGROUND

Establishing a safe prophylactic antimicrobial protocol in bone grafting may enhance osseous volume outcomes. The purpose of this in vitro study is to assess human osteoblast response and safety after explant antimicrobial exposure.

METHODS

Fresh human bone explants were exposed to three antimicrobials: povidone-iodine (PovI; 0.05%, 1%, and 5%), chlorhexidine (CHX; 0.2% and 1%), and sodium hypochlorite (NaOCl; 2.5%, 4.5%, and 5.25%) at different times (15, 30, 45, and 60 seconds) and concentrations to assess cellular toxicity. Explants were washed three times with saline after exposure. Controls, explants cultured in the absence of antimicrobials, were performed for all experimental situations tested. Trials were conducted in triplicate. Particle size influence on osteoblast growth was determined between bone fragments with a diameter <2 and ≥2 to 5 mm. Test and control groups were monitored by light microscopy to evaluate cellular growth. Osteoblast differentiation and morphology was assessed by alkaline phosphatase activity and scanning electron microscopy (SEM).

RESULTS

Osteoblast growth was similar for particles <2 and ≥2 to 5 mm. Alkaline phosphatase control reference values were not significantly different from test groups (0.35 mU/mL ± 0.004 versus 0.34 mU/mL ± 0.009; P >0.05). Light microscopy showed on average 97% osteoblastic growth for bone particles exposed to PovI 5% and CHX 0.2% for all times and CHX 1% up to 30 seconds. The odds ratio of positive osteoblastic growth after a 30-second 2.5% NaOCl exposure was 2.4 times higher than after 5.25%. On average, one of two replicas yielded positive growth with 2.5% NaOCl and one of three with 5.25%. After 60-second explant exposure, positive osteoblastic growth was 7.7 times more likely to occur with 5% PovI or 0.2% CHX than with 5.25% NaOCl (P <0.05). SEM analysis confirmed light microscopy similar cellular adhesion and osteoblast phenotypic features between test and control groups.

CONCLUSIONS

Best osteoblastic growth occurred after bone PovI exposure and CHX 0.2%. Cellular toxicity seems to be influenced by the type of antimicrobial, concentration, and exposure time. SEM analysis confirmed absence of osteoblast phenotypic alterations after exposure. Decontamination agents can safely be used in bone transplantation using up to 5% PovI and 0.2% CHX for 1 minute and CHX 1% for 30 seconds.