Diagnosis and Management of Suture-Related Concerns of the Infant Skull.

The cranial fontanelles and sutures have several benign variations, including most cases of "early" or "late" closure of the anterior fontanelle, bathrocephaly, overriding sutures, and benign metopic ridging. However, recognizing true craniosynostosis and referring the patient to a craniofacial specialist in a timely fashion are imperative, as minimally invasive options can be offered to most patients younger than 6 months of age. Gaining comfort with the physical examination of an infant with an abnormal head shape is best achieved through experience and pattern recognition and will frequently facilitate an accurate diagnosis without the need for ionizing radiation.

Lineage-Specific Wnt Reporter Elucidates Mesenchymal Wnt Signaling during Bone Repair.

ß-Catenin-dependent Wnt signaling controls numerous aspects of skeletal development and postnatal bone repair. Currently available transgenic Wnt reporter mice allow for visualization of global canonical Wnt signaling activity within skeletal tissues, without delineation of cell type. This is particularly important in a bone repair context, in which the inflammatory phase can obscure the visualization of mesenchymal cell types of interest. To tackle the issue of tissue-specific Wnt signaling, we have generated and characterized a transgenic mouse strain [termed paired related homeobox 1 (Prx1)-Wnt-green fluorescent protein (GFP), by crossing a previously validated Prx1-Cre strain with a nuclear fluorescent reporter driven by T-cell factor/lymphoid enhancer factor activity (Rosa26-Tcf/Lef-LSL-H2B-GFP)]. Prx1-Wnt-GFP animals were subject to three models of long bone and membranous bone repair (displaced forelimb fracture, tibial cortical defect, and frontal bone defect). Results showed that, irrespective of bone type, locoregional mesenchymal cell activation of Wnt signaling occurs in a defined temporospatial pattern among Prx1-Wnt-GFP mice. In summary, Prx1-Wnt-GFP reporter animals allow for improved visualization, spatial discrimination, and facile quantification of Wnt-activated mesenchymal cells within models of adult bone repair.

Effects of Rat Bone Marrow-Derived Mesenchymal Stem Cells and Demineralized Bone Matrix on Cranial Bone Healing.

BACKGROUND: Studies in tissue engineering about mesenchymal stem cells (MSCs) provide promising results for bone regeneration. The aim of this study was to evaluate the effects of rat bone marrow-derived MSCs (rMSCs) alone and when combined with demineralized bone matrix (DBM) on critical-sized cranial defects of rats. METHODS: Ten rats were used to obtain allogeneic rMSCs. Forty rats were separated equally into 4 groups. A full-thickness circular bone defect was created in the frontal bone of the rats. Group 1 was an operative control group. In group 2 DBM, in group 3 rMSCs, and in group 4 DBM combined with rMSCs were applied into the defects. Bone regeneration was evaluated by computed tomographic analysis and immunohistochemistry. RESULTS: In radiological evaluation, the percentage of area healed in group 3 at the 12th week was statistically significantly greater than in group 1. In group 3 and group 4, distributed healing patterns were observed more than in group 2 and in group 1. Immunohistochemical evaluation revealed that group 4 had the best osteoinductive potential. Osteoinductive potential of group 3 was similar to group 2 and was better than group 1. CONCLUSIONS: Allogeneic rMSC applications have created a statistically significant radiologic reduction of the bone defect areas at the end of the 12 weeks. The MSC applications have also increased the bone density and changed the healing patterns. Combined use of the DBM and rMSCs has created more osteoinductive responses. This combination can provide better results in craniofacial bone reconstruction.

Contrasting phase effects on vestibular evoked myogenic potentials (VEMPs) produced by air- and bone-conducted stimuli.

We have studied the effects of stimulus phase on the latency and amplitude of cVEMPs and oVEMPs by reanalysing data from Lim et al. (Exp Brain Res 224:437-445, 2013) in which alternating phase was used. Responses for the different initial stimulus phase, either positive or negative, were separated and reaveraged. We found that the phase (compressive or rarefactive) of AC 500-Hz stimuli had no significant effect on either latency or amplitude of the responses. Conversely, phase (positive = motor towards subjects) did alter the effects of BC 500-Hz stimulation. For cVEMPs, phase consistently affected initial latency with earlier responses for positive stimuli, while, for stimulation at the mastoid, negative onset phase gave larger responses. For the oVEMP, effects were different for the two sites of BC stimulation. At the forehead, the response appeared to invert, whereas at the mastoid there appeared to be a delay of the initial response. Related to this, the effect of phase for the two sites was opposite: at the mastoid, positive responses were earlier but negative were larger (particularly for long stimuli). At the forehead, the effect was the opposite: negative onset stimuli evoked earlier responses, whereas positive onset evoked larger responses. These findings indicate a basic difference in the way that AC and BC stimuli activate vestibular receptors and also indicate that the effects of phase of BC stimulation depend on location. Stimulus alternation does little to affect the response to AC stimulation but obscures the effects of BC stimuli, particularly for the oVEMP.

Enhanced Activation of Canonical Wnt Signaling Confers Mesoderm-Derived Parietal Bone with Similar Osteogenic and Skeletal Healing Capacity to Neural Crest-Derived Frontal Bone.

Bone formation and skeletal repair are dynamic processes involving a fine-tuned balance between osteoblast proliferation and differentiation orchestrated by multiple signaling pathways. Canonical Wnt (cWnt) signaling is known to playing a key role in these processes. In the current study, using a transgenic mouse model with targeted disruption of axin2, a negative regulator of cWnt signaling, we investigated the impact of enhanced activation of cWnt signaling on the osteogenic capacity and skeletal repair. Specifically, we looked at two calvarial bones of different embryonic tissue origin: the neural crest-derived frontal bone and the mesoderm-derived parietal bone, and we investigated the proliferation and apoptotic activity of frontal and parietal bones and derived osteoblasts. We found dramatic differences in cell proliferation and apoptotic activity between Axin2-/- and wild type calvarial bones, with Axin2-/- showing increased proliferative activity and reduced levels of apoptosis. Furthermore, we compared osteoblast differentiation and bone regeneration in Axin2-/- and wild type neural crest-derived frontal and mesoderm-derived parietal bones, respectively. Our results demonstrate a significant increase either in osteoblast differentiation or bone regeneration in Axin2-/- mice as compared to wild type, with Axin2-/- parietal bone and derived osteoblasts displaying a "neural crest-derived frontal bone-like" profile, which is typically characterized by higher osteogenic capacity and skeletal repair than parietal bone. Taken together, our results strongly suggest that enhanced activation of cWnt signaling increases the skeletal potential of a calvarial bone of mesoderm origin, such as the parietial bone to a degree similar to that of a neural crest origin bone, like the frontal bone. Thus, providing further evidence for the central role played by the cWnt signaling in osteogenesis and skeletal-bone regeneration.

Differences in biomechanical properties and thickness among frontal and parietal bones in a Japanese sample.

The aim of this study was to assess the mechanical properties and thickness of adult frontal and parietal bones. The heads of 114 Japanese cadavers (78 male cadavers and 36 female cadavers) of known age and sex were used. A total of 912 cranial samples, 8 from each skull, were collected. Samples were imaged using multidetector computed tomography to measure sample thickness. The fracture load of each sample was measured using a bending test with calculation of flexural strength. Statistical analyses demonstrated no significant bilateral difference in either the mechanical properties or thickness of frontal or parietal bones. The mechanical properties and thicknesses of frontal bones were significantly greater than those of parietal bones regardless of sex. Therefore, the skull may have a great ability to resist frontal impacts compared with parietal impacts. In female samples, parietal bones were found to have a more uniform structure when compared with male samples. Male parietal bones were found to be thicker at medial sites than at lateral sites. This study also revealed parietal bones at lateral sites in female samples were thicker than in male samples. No strong association was observed between age and flexural strength of frontal or parietal bones. However, the fracture load was negatively correlated with age most likely due to the reduction of thickness.

Pre-activation and muscle activity during frontal impact in relation to whiplash associated disorders.

OBJECTIVE: For the evaluation of neck injury the relative distance was observed between a marker placed on the forehead and a marker placed on the shoulder and also by change of the angle. To compare the severity of head injury a value of maximum head acceleration was used, HIC and a 3 ms criterion. All criteria were related to the activity of musculus sternocleidomastoideus and musculus trapezius in a situation of expected or unexpected impact. MATERIALS AND METHODS: The situation was recorded using a Qualisys system, head acceleration of probands in three axes was recorded using the accelerometer, activity of neck muscles was monitored by a mobile EMG. RESULTS: Maximum head acceleration was 12.1 g for non-visual and 8.2 g for visual. HIC36 was 5.7 non visual and 4.0 for visual. 3-ms criterion was 11.5 g for non-visual and 7.8 g for visual. The average time of muscle activation of the observed group without visual perception is 0.027 s after hitting an obstacle, with visual perception 0.127 s before the crash. CONCLUSIONS: Kinematic values indicate more favourable parameters for neck injuries for visual. Head injury criteria show an average decrease of about 30% for visual. We can conclude that the visual perception means a significant increase in pre-activation of the observed muscle group of almost 400% and lower activation in both following phases of approximately 40%.

Impact of vertical loading on the implant-bone interface.

OBJECTIVES: The main aim of this study was to evaluate the impact of vertical loading occurring during removal of cemented restorations on the implant-bone interface. METHODS: Thirty-six titanium implants (Camlog 4.3 × 9 mm) were placed 1 mm supraosseous in the frontal skull of four minipigs. After a 13 week healing period the implants were exposed and the implant stability was measured. Three implants per minipig were vertically loaded using 20 or 100 impulses, respectively with an 18 Ns impulse imitating a crown removal. Three implants were left unloaded as control. The animals were sacrificed after 13 or 18 weeks. The harvested specimens were analyzed using scanning electron microscopy (SEM), light and fluorescence microscopy. RESULTS: No post operative complications or deaths of the minipigs occurred. All implants osseointegrated. The average bone-implant contact area (BIC) was 78 ± 5.1%. No statistically significant difference could be found when comparing the BIC areas of the control and the experimental groups between the sacrificed animals at 13 weeks and 18 weeks (P > 0.05). Therefore, the results of each subgroup were pooled. No significant differences regarding the BIC area could be detected between the control and the experimental groups (P > 0.05). Except one failing implant no cracks due to vertical loading could be evaluated in the SEM. Fluorescence microscopy revealed a significantly higher bone remodeling activity in the vertically loaded groups. CONCLUSIONS: Removal of cemented implant restorations seems not to have an impact on the mechanical implant stability, but seems to increase bone remodeling activity.

Three-dimensional finite element analysis of occlusal stress distribution in the human skull with premolar extraction.

OBJECTIVE: To analyze the effect of orthodontic treatment with premolar extraction on the stress distribution of the occlusal force in the human skull. MATERIALS AND METHODS: A three-dimensional finite element (3D FE) model was constructed based on computed tomography scan data, and it served as the pretreatment model. For the extraction model simulating postorthodontic occlusion, the first premolar was removed in the pretreatment model, and the anterior and posterior segments were repositioned. Stress distribution was evaluated by 3D FE analysis in both models under the simulation of 1000 N for occlusal forces and 400 N for masseter muscle force. RESULTS: The occlusal stresses were concentrated at the alveolar bone near the teeth, the infrazygomatic crest, the frontal process, the temporal process of the zygomatic bone, the infraorbital rim, the pyriform aperture region, and the pterygoid plate in both models. The von Mises stress at the pterygoid plate area was lower in the extraction model (3.53 MPa) than in the pretreatment model (5.57 MPa), while the stress at the frontal process of the maxilla was higher in the extraction model (2.32 MPa) than in the pretreatment model (2.16 MPa). CONCLUSIONS: The results indicated that the occlusal forces were transferred through the maxillonasal, maxillozygomatic, and maxillopterygoid stress trajectories and that stress distribution moved more "forward" with the orthodontic treatment with premolar extraction.

A sensitivity analysis to the role of the fronto-parietal suture in Lacerta bilineata: a preliminary finite element study.

Cranial sutures are sites of bone growth and development but micromovements at these sites may distribute the load across the skull more evenly. Computational studies have incorporated sutures into finite element (FE) models to assess various hypotheses related to their function. However, less attention has been paid to the sensitivity of the FE results to the shape, size, and stiffness of the modeled sutures. Here, we assessed the sensitivity of the strain predictions to the aforementioned parameters in several models of fronto-parietal (FP) suture in Lacerta bilineata. For the purpose of this study, simplifications were made in relation to modeling the bone properties and the skull loading. Results highlighted that modeling the FP as either an interdigitated suture or a simplified butt suture, did not reduce the strain distribution in the FP region. Sensitivity tests showed that similar patterns of strain distribution can be obtained regardless of the size of the suture, or assigned stiffness, yet the exact magnitudes of strains are highly sensitive to these parameters. This study raises the question whether the morphogenesis of epidermic scales in the FP region in the Lacertidae is related to high strain fields in this region, because of micromovement in the FP suture.

Is there an optimal force level for sutural expansion?

INTRODUCTION: The purpose of this study was to establish the causal relationships between expansion force magnitudes, sutural separation, and sutural bone formation. METHODS: Thirty-seven 6-week-old rabbits were randomly assigned to 4 force groups (0, 50, 100, or 200 g). Constant forces were delivered for 42 days by nickel-titanium open-coil springs to miniscrew implants (MSIs) placed in the frontal bone on both sides of the midsagittal suture. Inter-MSI and bone marker widths were measured biweekly to quantify sutural separation and MSI movements. Sutural bone formation was quantified based on the incorporation of fluorescent bone labels administered at days 18, 28, and 38. RESULTS: Nine of 74 MSIs failed between days 0 and 14, including 4 in the controls and 5 in the 50-g group. A decelerating curvilinear pattern of sutural separation was evident in the 50-g, 100-g, 200-g groups. Bone markers showed that sutural widths increased by 0.6, 3.2, 5.1, and 6.2 mm in the control, 50-g, 100-g, and 200-g groups, respectively. Except for the 200-g group, significantly greater amounts of bone formation were observed between days 18 and 28 than between days 28 and 38. Sutural bone formation also increased with increasing forces up to 100 g; there was no difference between the 100-g and the 200-g groups. Sutural separation explained 71% and 53% of the variations in bone formation between days 18 and 28 and days 28 and 38, respectively. CONCLUSIONS: Within the limits of this study, sutural bone formation is directly related to the amount of sutural separation, which is in turn related to the amount of force applied. The results suggest that there is a level of induced sutural separation that provides the greatest amount of bone formation.

The tolerance of the frontal bone to blunt impact.

The current understanding of the tolerance of the frontal bone to blunt impact is limited. Previous studies have utilized vastly different methods, which limits the use of statistical analyses to determine the tolerance of the frontal bone. The purpose of this study is to determine the tolerance of the frontal bone to blunt impact. Acoustic emission sensors were used to provide a noncensored measure of the frontal bone tolerance and were essential due to the increase in impactor force after fracture onset. In this study, risk functions for fracture were developed using parametric and nonparametric techniques. The results of the statistical analyses suggest that a 50% risk of frontal bone fracture occurs at a force between 1885 N and 2405 N. Subjects that were found to have a frontal sinus present within the impacted region had a significantly higher risk of sustaining a fracture. There was no association between subject age and fracture force. The results of the current study suggest that utilizing peak force as an estimate of fracture tolerance will overestimate the force necessary to create a frontal bone fracture.

Changes in bone mineral and matrix in response to a soft diet.

Alterations in the magnitude of habitual mechanical loads upon the skeleton may not only affect bone architecture, but also influence the nature of the bone matrix. We tested the hypothesis that changing the mechanical consistency of the diet affects both the mineral and non-mineralized moieties of bone matrix. Female rats were fed a soft diet (powdered chow as a paste), while control animals were fed the standard chow. After 8 or 20 wks, animals were killed. Cranial (mandible, maxilla, parietal, and frontal) bones and ulnae were analyzed for mineralization density by quantitative backscattered electron microscopy, and sulphated glycosaminoglycan levels with alcian blue staining were measured by microdensitometry. The soft diet group showed a significant increase in mineralization density distribution at almost all cranial sites and a reduction in alcian blue staining in alveolar bone. Altering the consistency of the diet significantly affects mineral concentration and glycosaminoglycan content of alveolar bone.

Correlated low-frequency BOLD fluctuations in the resting human brain are modulated by recent experience in category-preferential visual regions.

The resting brain is associated with significant intrinsic activity fluctuations, such as the correlated low-frequency (LF) blood oxygen level-dependent (BOLD) fluctuations measured by functional magnetic resonance imaging. Despite a recent expansion of studies investigating resting-state LF-BOLD correlations, their nature and function are poorly understood. A major constraint on LF-BOLD correlations appears to be stable properties of anatomic connectivity. There is also evidence that coupling can be modulated by recent or ongoing task performance, suggesting that certain components of correlated dynamics are malleable on short timescales. Here, we compared activity during extended periods of rest following performance of 2 distinct cognitive tasks using different categories of visual stimuli-faces and complex scenes. Prolonged exposure to these distinct categories of visual information caused frontal networks to couple differentially with posterior category-preferential visual regions during subsequent periods of rest. In addition, we report preliminary evidence suggesting that conditions exist in which the degree of modulation of LF-BOLD correlations predicts subsequent memory. The finding that resting-state LF-BOLD correlations are modulated by recent experience in functionally specific brain regions engaged during prior task performance clarifies their role as a dynamic phenomenon which may be involved in mnemonic processes.

Origin matters: differences in embryonic tissue origin and Wnt signaling determine the osteogenic potential and healing capacity of frontal and parietal calvarial bones.

Calvarial bones arise from two embryonic tissues, namely, the neural crest and the mesoderm. In this study we have addressed the important question of whether disparate embryonic tissue origins impart variable osteogenic potential and regenerative capacity to calvarial bones, as well as what the underlying molecular mechanism(s). Thus, by performing in vitro and in vivo studies, we have investigated whether differences exist between neural crest-derived frontal and paraxial mesodermal-derived parietal bone. Of interest, our data indicate that calvarial bone osteoblasts of neural crest origin have superior potential for osteogenic differentiation. Furthermore, neural crest-derived frontal bone displays a superior capacity to undergo osseous healing compared with calvarial bone of paraxial mesoderm origin. Our study identified both in vitro and in vivo enhanced endogenous canonical Wnt signaling in frontal bone compared with parietal bone. In addition, we demonstrate that constitutive activation of canonical Wnt signaling in paraxial mesodermal-derived parietal osteoblasts mimics the osteogenic potential of frontal osteoblasts, whereas knockdown of canonical Wnt signaling dramatically impairs the greater osteogenic potential of neural crest-derived frontal osteoblasts. Moreover, fibroblast growth factor 2 (FGF-2) treatment induces phosphorylation of GSK-3beta and increases the nuclear levels of beta-catenin in osteoblasts, suggesting that enhanced activation of Wnt signaling might be mediated by FGF. Taken together, our data provide compelling evidence that indeed embryonic tissue origin makes a difference and that active canonical Wnt signaling plays a major role in contributing to the superior intrinsic osteogenic potential and tissue regeneration observed in neural crest-derived frontal bone.

Adaptation of the cranium to spring cranioplasty forces.

BACKGROUND: During spring-assisted cranioplasty, the spring transmits forces through adjacent cranium. We have previously demonstrated that the ectocranial-endocranial thickness of cranial sutures increases significantly over time in the presence of continuous spring forces. We wished to investigate if cranial bone showed similar adaptational responses. METHODS: New Zealand white rabbits were randomized into a treatment group [a spring was placed across a posterior frontal suture (PFS) suturectomy and a control group (PFS suturectomy)]. Animals (n = 6) were euthanized from each group at 4, 7, and 10 weeks, respectively. A sham group (n = 6) was euthanized at 10 weeks. Frontal bone thickness was recorded at five reproducible anatomical points on the frontal bone. Histological analysis of the bone architecture was performed. RESULTS: Frontal bone thickness was significantly greater than controls at all five sites at weeks 7 and 10. There were multiple significant differences between the 4-, 7-, and 10-week groups with each site progressively thickening over time. Histological analysis revealed a uniform increase in thickness of the endocranial and ectocranial cortical bone in the treatment groups. CONCLUSIONS: Cranial bone adapts to the presence of continuous spring cranioplasty forces by progressively thickening over time. This property is beneficial in craniosynostosis cases with very thin and poor quality bone and may partly explain the observed lack of spring erosion through bone.

Bone repair and augmentation using block of sintered bovine-derived anorganic bone graft in cranial bone defect model.

OBJECTIVE: To histomorphometrically investigate the repair of critical size defects (CSDs) and bone augmentation in cranial walls using block of sintered bovine-derived anorganic bone (sBDAB) graft. MATERIAL AND METHODS: Forty guinea-pigs were divided into test (n=20) and CSD control (n=20) groups. In each animal, a full-thickness bone defect with 9.5 mm diameter was made in the frontal bone. The defects were filled with an sBDAB block soaked in blood in the test group and with blood clot in the CSD control group. The skulls were collected at 0 h (n=2) and 30, 90 and 180 days (n=6/group and period) postoperatively. The volume density and total volume of newly formed bone, sBDAB, blood vessels and connective tissue, vertical thickness of removed bone plug, sBDAB block and graft area were evaluated. RESULTS: The vertical thickness of the adapted sBDAB block was 3.8 times higher than that of the removed bone plug and did not show significant difference between periods, filling in average 29.8% of the total graft region. The sBDAB block exhibited complete osseointegration with the borders of the defect at 90 days. At 90 and 180 days, the vertical thickness of the graft was 279% in the average, and the total volume of bone augmentation was, respectively, 78.8% and 148.5% higher compared with the removed bone plug. The defects of the CDS control group showed limited osteogenesis and filling by connective tissue plus tegument. CONCLUSION: The sBDAB block can be used to promote repair of CSDs and bone augmentation in the craniomaxillofacial region, due to its good osteoconductive and slow resorptive properties.

Transmission pathways of vibratory stimulation as measured by subjective thresholds and distortion-product otoacoustic emissions.

To clarify the contribution of the skull contents to the transmission of bone vibratory stimuli, and to examine the characteristics of such stimuli, we compared auditory thresholds and distortion-product otoacoustic emission (DPOAE) levels with a bone vibrator placed on various sites of the head, including the eye. The best audiometric thresholds and the highest DPOAE levels were obtained with the vibrator placed on the mastoid of the measuring side, or on the "ultrasound-window" of the temple. The audiometric thresholds obtained with the bone vibrator on the eye were similar to those of the forehead, and about 10 dB higher than at the best sites. DPOAEs were clearly present when elicited by a combination of air-conducted stimuli presented through an insert earphone and with the bone vibrator placed on the eye. These results indicate that vibratory sounds can be transmitted through the skull contents to the inner ear. The intracranial transmission pathway of the vibratory stimuli may play a significant role, particularly at low frequencies, and possibly also when the vibratory stimuli are applied on the skull bone.

Stress and displacement patterns in the craniofacial skeleton with rapid maxillary expansion: a finite element method study.

INTRODUCTION: The purpose of this finite element study was to evaluate stress distribution along craniofacial sutures and displacement of various craniofacial structures with rapid maxillary expansion (RME) therapy. METHODS: The analytic model for this study was developed from sequential computed tomography scan images taken at 2.5-mm intervals of a dry young human skull. Subsequently, a finite element method model was developed from computed tomography images by using AutoCAD software (2004 version, Autodesk, Inc, San Rafael, Calif) and ANSYS software (version 10, Belcan Engineering Group, Downers Grove, Ill). RESULTS: The maxilla moved anteriorly and downward and rotated clockwise in response to RME. The pterygoid plates were displaced laterally. The distant structures of the craniofacial skeleton--zygomatic bone, temporal bone, and frontal bone--were also affected by transverse orthopedic forces. The center of rotation of the maxilla in the X direction was somewhere between the lateral and the medial pterygoid plates. In the frontal plane, the center of rotation of the maxilla was approximately at the superior orbital fissure. The maximum von Mises stresses were found along the frontomaxillary, nasomaxillary, and frontonasal sutures. Both tensile and compressive stresses could be demonstrated along the same suture. CONCLUSIONS: RME facilitates expansion of the maxilla in both the molar and the canine regions. It also causes downward and forward displacement of the maxilla and thus can contribute to the correction of mild Class III malocclusion. The downward displacement and backward rotation of the maxilla could be a concern in patients with excessive lower anterior facial height. High stresses along the deep structures and the various sutures of the craniofacial skeleton signify the role of the circummaxillary sutural system in downward and forward displacement of the maxilla after RME.

What wrapped perichondrial and periosteal grafts offer as regenerators of new tissue.

The major goals in contour restoration procedures are to re-establish the desired contour with the use of resilient and durable materials that can be easily found and harvested. Cartilage grafts are commonly used for these purposes though they often possess a problem of donor site morbidity and shortage of quantity. The neo-cartilage formation capacities of both perichondrium and periosteum are well-known. We aimed to optimize both the amount and quality of the newly forming tissue from perichondrial and periosteal grafts. For this purpose the grafts were wrapped on themselves. Placement of oxidized regenerated cellulose (ORC) within graft layers was performed in two groups with the aim of giving support to the regenerating tissue, and increasing the connective tissue formation within the graft layers. Three-month-old New Zealand white rabbits were used. Group 1 ear perichondrial, and Group 2 calvarium periosteal grafts of 1.4 x 2.4 cm were harvested, folded on themselves, and sutured at the edges to create closed pockets. 0.8 x 0.8 cm sized ORC sheets were placed inside the pockets before wrapping in Group 3 perichondrial and Group 4 periosteal grafts. 0.2-mL autogenous blood was injected in each pocket. All grafts were transplanted under the abdominal muscle fascia, and harvested after 6 weeks. Volumes and weights of wrapped perichondrial grafts were higher than their periosteal counterparts either with or without the inclusion of ORC. Grafts with ORC (Groups 3 and 4) were heavier than the grafts lacking ORC (Groups 1 and 2), in a statistically significant manner (P