Thongchai Nuntanaranont

Proportion of deproteinized bovine bone and autogenous bone affects bone formation in the treatment of calvarial defects in rabbits

This study assessed new bone formation generated using three different proportions of autogenous bone (AB) and deproteinized bovine bone (DBB). Thirty bicortical skull defects were prepared in 15 rabbits, divided into 3 groups: Group 1, critical size defect (CSD) versus AB as controls; Group 2, DBB versus a composite of AB and DBB using a proportion of 1:1; and Group 3, a composite of AB and DBB using a proportion of 1:2 versus a proportion of 1:4. After 8 weeks, radiographic evaluation was assessed using densitometry and new bone formation by histomorphometry. The mean optical density of the CSD (0.108+/-0.238) and AB (0.352+/-0.161) groups differed significantly from the DBB group (1.044+/-0.093) and the groups using a proportion of 1:1 (0.905+/-0.078), 1:2 (0.865+/-0.294) and 1:4 (0.867+/-0.304). Histomorphometry revealed a higher percentage of new bone in the AB group (30.223+/-16.722) than in the groups using proportions of 1:2 (22.639+/-5.659), 1:1 (20.929+/-6.169), 1:4 (9.621+/-2.400), DBB (14.441+/-2.742) and CSD (10.645+/-8.868), respectively. The 1:2 group had significantly higher bone content than the 1:4 group. The proportions of 1:1 and 1:2 resulted in greater bone formation than the proportion of 1:4, DBB and CSD.

Biodegradable polycaprolactone-chitosan three-dimensional scaffolds fabricated by melt stretching and multilayer deposition for bone tissue engineering: assessment of the physical properties and cellular response

Fabrication of polycaprolactone (PCL)-chitosan (CS) three-dimensional (3D) scaffolds using the novel technique of melt stretching and multilayer deposition was introduced. In brief, firstly, the PCL-CS monofilaments containing 0% (pure PCL), 10%, 20% and 30% CS by weight were fabricated by melting and stretching processes. Secondly, the desired multilayer (3D) scaffolds were fabricated by arranging and depositing the filaments. Physical properties of the filaments and the scaffolds were evaluated. MC3T3-E1 cell lines were seeded on the scaffolds to assess their proliferation. A typical micro-groove pattern was found on the surfaces of pure PCL filaments due to stretching. The filaments of PCL-30%CS had the highest tendency of fracture during stretching and could not be used to form the scaffold. Increasing CS proportions tended to reduce the micro-groove pattern, surface roughness, tensile strength and elasticity of the filaments, whilst compressive strength of the PCL-CS scaffolds was not affected. The average pore size and porosity of the scaffolds were 536.90 ± 17.91 µm and 45.99 ± 2.8% respectively. Over 60 days, degradation of the scaffolds gradually increased (p > 0.05). The more CS containing scaffolds were found to increase in water uptake, but decrease in degradation rate. During the culture period, the growth of the cells in PCL-CS groups was significantly higher than in the pure PCL group (p < 0.05). On culture-day 21, the growth in the PCL-20%CS group was significantly higher than the other groups (p < 0.05). In conclusion, the PCL-20%CS scaffolds obtained the optimum results in terms of physical properties and cellular response.

A comparison of autogenous bone graft combined with deproteinized bovine bone and autogenous bone graft alone for treatment of alveolar cleft.

This study assessed the use of composite autogenous bone and deproteinized bovine bone (DBB) for repairing alveolar cleft compared with autogenous bone alone in terms of clinical outcomes and patient morbidity. 30 patients with a mean age of 10.2±1.7 years were randomly divided into two groups. Group I used autogenous cancellous bone graft harvested from the anterior iliac crests by the conventional trapdoor approach. Group II used a composite of DBB and autogenous cancellous bone harvested by a trephine bone collector; the proportion of 1:1 by volume was used. The bone graft quantities of both groups decreased with time. Their average changes were not statistically different over 24 months after grafting. The canines of both groups could spontaneously or orthodontically erupt through the grafting areas. Patients in group II recovered from uncomfortable walking significantly faster than those in group I (p<0.05) and their duration of hospital stay was significantly shorter than those in group I (p<0.05). The average operation time, intra-operative blood loss and postoperative pain were less in group II than in group I (p>0.05).

A preliminary study of the effect of low intensity pulsed ultrasound on new bone formation during mandibular distraction osteogenesis in rabbits

This study assesses the effect of low intensity pulsed ultrasound (LIPUS) on new bone formation during mandibular distraction osteogenesis (DO) in rabbits. 24 rabbits underwent DO on the right side of the mandible. 12 rabbits received a daily 20-min LIPUS (1.5 MHz, 30 mW/cm2) treatment on the first day of the distraction until they were killed at week 0 (immediately after the distraction), week 2 and week 4 after the distraction. Four rabbits were killed at each time point. The other 12 rabbits followed the same protocol without the ultrasound treatment. A plain radiography, a micro-CT scan, a microhardness test and a histological examination were used to evaluate new bone formation in the distraction gap. At week 0 and week 2 after the distraction, the treatment groups showed higher radiopacity and microhardness (p<0.05), and more bone formation was detected by the histological examination. At week 4 after the distraction, there was no statistical difference between the two groups. In this study, LIPUS accelerated new bone formation during the distraction period and 2 weeks after the distraction, which implies that the effective time for using LIPUS is in the early stage of DO.

Assessment of bone regeneration of a tissue-engineered bone complex using human dental pulp stem cells/poly(ε-caprolactone)-biphasic calcium phosphate scaffold constructs in rabbit calvarial defects

The objective of the present study was to investigate the effect of a fabricated combination of poly-ɛ-caprolactone (PCL)–biphasic calcium phosphate (BCP) with the modified melt stretching and multilayer deposition (mMSMD) technique on human dental pulp stem cell (hDPSC) differentiation to be osteogenic like cells for bone regeneration of calvarial defects in rabbit models. hDPSCs extracted from human third molars were seeded onto mMSMD PCL-BCP scaffolds and the osteogenic gene expression was tested prior to implantation in vivo. Two standardized 11 mm in diameter circular calvarial defects were created in 18 adult male New Zealand white rabbits. The rabbits were divided into 4 groups: (1) hDPSCs seeded in mMSMD PCL-BCP scaffolds; (2) mMSMD PCL-BCP scaffolds alone, (3) empty defects and (4) autogenous bone (n = 3 site/time point/groups). After two, four and eight weeks after the operation, the specimens were harvested for micro-CT including histological and histomorphometric analysis. The explicit results presented an interesting view of the bioengineered constructs of hDPSCs in PCL-BCP scaffolds that increased the newly formed bone compared to the empty defect and scaffold alone groups. The results demonstrated that hDPSCs combined with mMSMD PCL-BCP scaffolds may be an augmentation material for bony defect.

Biomechanical properties of novel biodegradable poly ε-caprolactone–chitosan scaffolds

AIM To investigate the biomechanical properties of poly ε-caprolactone (PCL)-chitosan (CS) scaffolds fabricated by the melt stretching and multilayer deposition technique. METHODS The PCL-CS scaffolds containing CS at 0% (pure PCL), 10%, and 20% by weight were prepared. For the monolayer scaffolds, shear and blending tests simulating the reconstruction of orbital floor defects (situation A) and mandibular defects (situation B) were conducted. For the 3-D scaffolds, compression tests of their superior and lateral aspects were done. RESULTS For the monolayer scaffolds, the pure PCL group had remarkably lower shear strength than the other groups (P > 0.05). In situation A, all groups withstood the forces without any significant difference. In situation B, the pure PCL group could withstand the forces remarkably lower than those of the other group (P < 0.05). The 3-D scaffolds of all groups could withstand compressive forces directed towards their superior aspects. However, they could not withstand the forces directed towards their lateral aspects at the limited strain. CONCLUSIONS The monolayer scaffolds were suitable for reconstruction of the orbital floor and mandibular defects under light load-bearing conditions. The 3-D scaffolds could be used in the high load bearing-areas only if the forces were directed at their superior aspects.

Iliac Crest Bone Grafting of the Alveolar Cleft: Clinical and Quantitative Radiographic Assessment

Abstract Objective: To evaluate the clinical results and quantitatively assess bone graft volume after secondary alveolar cleft bone grafting. Materials and Methods: Twenty five patients with alveolar clefts (19 unilateral and 6 bilateral) were enrolled in this prospective study. All alveolar cleft defects were grafted with cancellous bone harvested from the anterior iliac crest and closed by advancement flap. Occlusal X-rays were taken preoperatively, early postoperatively, and 1, 3, 6, 12, 18, and 24 months after the operation. A custom-made film holder was used to control film-to-source distance and angulation, thus permitting a reproducible film position at each time interval. An aluminium step wedge was attached to each film for calibrating the quantitative measurement of radiographic bone density. Assessment of the bone graft was done by measurement of bone density, and bone graft height by image processing and analysis software. Results: The average bone graft volume was 3.30 mL (SD, 1.46 mL). The duration of hospital stay was 5.30 days (SD, 1.02 days). The oronasal fistula was closed in all cases. The canines eventually erupted through the grafted area with the assistance of postoperative orthodontic treatment. Bone graft density in the cleft site rapidly decreased 1 month after the operation, becoming stable after 6 months. The bone graft height significantly decreased over 6 months (p Conclusion: Due to the large amount of cancellous bone available and low surgical morbidity, iliac crest bone grafting remains a promising method for the correction of alveolar cleft defects. However, the high resorption rate of the graft should be considered when choosing the grafting material.

Biological characteristic effects of human dental pulp stem cells on poly-ε-caprolactone-biphasic calcium phosphate fabricated scaffolds using modified melt stretching and multilayer deposition.

Craniofacial bone defects such as alveolar cleft affect the esthetics and functions that need bone reconstruction. The advanced techniques of biomaterials combined with stem cells have been a challenging role for maxillofacial surgeons and scientists. PCL-coated biphasic calcium phosphate (PCL-BCP) scaffolds were created with the modified melt stretching and multilayer deposition (mMSMD) technique and merged with human dental pulp stem cells (hDPSCs) to fulfill the component of tissue engineering for bone substitution. In the present study, the objective was to test the biocompatibility and biofunctionalities that included cell proliferation, cell viability, alkaline phosphatase activity, osteocalcin, alizarin red staining for mineralization, and histological analysis. The results showed that mMSMD PCL-BCP scaffolds were suitable for hDPSCs viability since the cells attached and spread onto the scaffold. Furthermore, the constructs of induced hDPSCs and scaffolds performed ALP activity and produced osteocalcin and mineralized nodules. The results indicated that mMSMD PCL-BCP scaffolds with hDPSCs showed promise in bone regeneration for treatment of osseous defects.

In vivo evaluation of modified silk fibroin scaffolds with a mimicked microenvironment of fibronectin/decellularized pulp tissue for maxillofacial surgery

This study aimed to carry out in vivo testing of the formation of new bone by modified silk fibroin scaffolds with a mimicked microenvironment of fibronectin/decellularized pulp in bone defects. Silk fibroin scaffolds were fabricated into three-dimensional scaffolds before being coated with fibronectin/decellularized pulp. The coated scaffolds were implanted into rabbits. Twenty-four bicortical calvarial defects in 12 rabbits were divided randomly into two groups: non-coated and coated silk fibroin scaffolds. The rabbits were sacrificed 2, 4 and 8 weeks after operation for evaluation of new bone formation. The morphology of the scaffolds, new bone formation and histology were evaluated by scanning electron microscopy, micro-CT and hematoxylin and eosin staining, respectively. The results showed that the coated silk fibroin scaffolds had a fibrillar network and crystal particles in the porous structure. The coated silk fibroin scaffolds demonstrated the ability to induce the formation of new bone with low inflammation and high vascularization. The results indicated that the modified silk fibroin scaffolds showed suitable biological performance and promise for bone regeneration in maxillofacial surgery.

Mandibular Lengthening by Distraction Osteogenesis: Role of Periosteum and Endosteum

Abstract Objective: To study the role of the periosteum and endosteum in new bone formation by distraction osteogenesis. Materials and Methods: Twenty four rabbits were divided into 3 groups of perieosteum destruction (group P), endosteum destruction (group E), and a control group (group C). After right mandibular body osteotomy followed by distractor placement, the buccal periosteum in the segment between the second and third screws was removed by scalpel in group P. In group E, the endosteum was scraped out from both bone ends between the second and third screws. In group C both periosteum and endosteum were preserved during the surgical operation. After a latency period of 3 days, bone lengthening was started at a rate of I mm per day for 10 days, after which the newly formed bone was allowed to consolidate for 6 weeks with the device serving as an external fixator Radiographs were taken at the following time intervals: 2 weeks, 4 weeks, and 6 weeks after completion of distraction and 6 months after consolidation. The animals were sacrificed 6 weeks after completion of distraction and 6 months after consolidation for the gross macroscopic, histological, and radiological examinations and stability measurement of the distracted segment. Results: New bone was generated in all animal groups. The buccal cortex was incompletely formed in groups P and E but was completely formed and indistinguishable in the control group after 6 months. Histologically, the newly formed bone in the control group had a more mature appearance and better organised bone spicules than in groups P and E. In addition the remodelling process occurred more rapidly in the control group. However, quantitative analysis of the newly formed bone by densitometry revealed no statistically significant differences at each time interval among the 3 groups except for a decline in density in the control group after 6 months due to the bone remodelling process. The stability of the regenerated bone of the lengthened segment was best in the control group, with groups P and E showing marked changes in the length of the distracted distance. Conclusion: Although groups P and E exhibited slower new bone maturation, the amount of newly formed bone was equal in all groups. It could be stated that the periosteum and endosteum are probably not indispensable or particularly important for adequate callus formation. This may be due to the rich blood supply of the craniofacial skeleton. However the instability of the segment caused by the slow maturation and remodelling of the newly formed bone in groups P and E should be noted, and a longer consolidation period is recommended to avoid instability of the regenerated segment in such cases.