Effect of head orthoses on skull deformities in positional plagiocephaly: Evaluation of a 3-dimensional approach.

PURPOSE: The positional non-synostotic plagiocephaly represents a cranial asymmetry affecting all 3 dimensions. The aim of this study was to evaluate volumetric indices to assess the efficiency in improving non-synostotic cranial asymmetries in treatment with head orthoses. MATERIAL AND METHODS: A total of 96 infants were included in this observational retrospective study. The cohort was further divided into subgroups according to age of helmet supply (younger/older than 7.5 months) and duration of therapy (less/more than 150 days). With 3-dimensional photogrammetry data sets, the skull volume was separated into quadrants and set in relation to each other to create an Anterior Cranial Asymmetry Index (ACAI) and a Posterior Cranial Asymmetry Index (PCAI) as 3-dimensional parameters. RESULTS: Treatment with head orthoses led to a significant reduction of ACAI (p < 0.0001) and PCAI (p = 0.001). Cranial asymmetry was more severe in the occipital region and significantly improved mainly during the first 75 days with a 40.08% decrease of PCAI value in the short-term therapy in the younger treatment subgroup (p = 0.003). CONCLUSIONS: The introduced parameters sufficiently reproduce the improvement of asymmetry during helmet therapy, following the trend of already established parameters. Asymmetry was significantly improved in the occiput region, and helmet therapy was highly effective in younger infants and in the early treatment period.

Impact of surgical management in cases of intraoperative membrane perforation during a sinus lift procedure: a follow-up on bone graft stability and implant success.

BACKGROUND: Until now, sinus floor elevation represents the gold standard procedure in the atrophic maxilla in order to facilitate dental implant insertion. Although the procedure remains highly predictive, the perforation of the Schneiderian membrane might compromise the stability of the augmented bone and implant success due to chronic sinus infection. The aim of this retrospective cohort study was to show that a membrane tear, if detected and surgically properly addressed, has no influence on the survival of dental implants and bone resorption in the augmented area. METHODS: Thirty-one patients with 39 perforations could be included in this evaluation, and a control group of 32 patients with 40 sinus lift procedures without complications were compared regarding the radiographically determined development of bone level, peri-implant infection, and implant loss. RESULTS: Implant survival was 98.9% in the perforation group over an observation period of 2.7 (± 2.03) years compared to 100% in the control group after 1.8 (± 1.57) years. The residual bone level was significantly lower in the perforation group (p = 0.05) but showed no difference direct postoperatively (p = 0.7851) or in the follow-up assessment (p = 0.2338). Bone resorption remained not different between both groups (p = 0.945). A two-stage procedure was more frequent in the perforation group (p = 0.0003) as well as peri-implantitis (p = 0.0004). CONCLUSIONS: Within the limits of our study, the perforation of the Schneiderian membrane did not have a negative impact on long-term graft stability or the overall implant survival.

Self-perception versus professional assessment of functional outcome after ablative surgery in patients with oral cancer.

PURPOSE: The extent of functional impairment after ablative surgery in the orofacial region may be directly reflected in a reduction in Quality of Life. This study intended to compare the patients' perception with an objective functional evaluation of the orofacial system in order to bilaterally distinguish direct influence factors. METHODS: A total of 45 patients were included in this study and were asked to complete the European Organisation for Research and Treatment of Cancer Core Questionnaire (EORTC QLQ-30) and the Head and Neck 35 Module (H&N 35). Afterward one independent speech therapist evaluated the patients applying the Frenchay Dysarthria Assessment regarding four main categories: mouth opening, tongue motility, swallowing and intelligibility. Comparisons between groups were performed using Whitney-Mann U-Wilcoxon test and calculating Spearman's rho. RESULTS: Overall the professional assessments by the speech therapists revealed significantly higher scores regarding intelligibility, swallowing and mouth opening when compared to the patients' self-perception. Smaller tumor sizes, no bone resection and local reconstruction techniques led to significantly better functional outcomes, when assessed by speech therapists. Swallowing was perceived significantly better by patients in cases of local reconstruction. CONCLUSIONS: From the professionals' point of view differences were perceived in more items compared to the patients' self-assessments, who widely experienced a more severe functional impairment. Physicians should take this into account when discussing adverse therapy effects with the patients.

Therapy effects of head orthoses in positional plagiocephaly.

PURPOSE: Head orthoses offer a valuable therapeutic option for infants with positional plagiocephaly. The aim of this retrospective study was to evaluate the influence of therapy start and duration due to improvement of cranial asymmetry. MATERIAL AND METHODS: A total of 102 children during the years 2009-2014 were included. The patient cohort was divided according to age at the beginning of therapy (younger/older than 7.5 months) and duration (less/more than 150 days). To evaluate the therapy, ear shift (ES), Cranial Vault Asymmetry Index (CVAI), and Cranial Index (CI) were calculated pre- and post-therapy by using three-dimensional photogrammetry measurements. RESULTS: Treatment with head orthoses led to a significant reduction of CVAI in groups with less and more than 150 days of therapy (p < 0.0001). A significant reduction in CVAI was observed (p = 0.0235) in children younger than 7.5 months in short-term therapy. At the end of therapy, no significant difference was found in the groups, whether treated with short- or long-term head orthoses (p = 0.0813), although CVAI was significantly different comparing the third time point of both groups for treatment duration (p = 0.017). The major positive effect of helmet therapy has been seen after 75 days of treatment. A treatment that was longer than 150 days did not show any significant improvement concerning the cranial asymmetry. CONCLUSIONS: Helmet therapy is a reliable method in the treatment of positional plagiocephaly to improve cephalic asymmetries. This retrospective study indicates that an early beginning can lead to satisfying results after short-term therapy.

Nerve regeneration techniques respecting the special characteristics of the inferior alveolar nerve.

PURPOSE: The aim of this study was to examine the in situ regeneration of the inferior alveolar nerve (IAN) in its bony channel, using autologous tissue in combination with a recombinant human nerve growth factor (rhNGF). MATERIALS AND METHODS: A total of 20 New Zealand rabbits were randomly divided into five groups. Following dissection of the IAN, the animals underwent reconstruction either with muscle tissue (groups 1 and 2) or with fat tissue (groups 3 and 4). In group 5 (control), the dissected nerve was resected and reconstructed by placement of the reversed autologous segment. After 2 and 4 weeks, 1 mL rhNGF was locally injected in groups 1 and 3. Nerve function was monitored by measuring the jaw-opening reflex using electromyography for a period of 24 weeks. RESULTS: Regeneration of the nerve was achieved in all groups, but preoperative threshold values were not achieved. Comparing the experimental groups to the control, there was a significant difference in favor of the autologous nerve reconstruction. Differences between the experimental groups remained statistically not significant. CONCLUSION: Regeneration of the IAN with autologous tissue is possible, but without achieving preoperative thresholds. Additional injection of a growth factor seems to improve the speed of regeneration for fat and muscle grafts.

Long-term Survival of Straumann Dental Implants with TPS Surfaces: A Retrospective Study with a Follow-up of 12 to 23 Years.

PURPOSE: The aim of this study was to evaluate the long-term dental implant survival rates of Straumann dental implants in a university hospital environment over 12 to 23 years. MATERIALS AND METHODS: A total of 388 Straumann dental implants with titanium-sprayed surfaces (TPS) were inserted in 92 patients between 1988 and 1999 in the Department of Oral and Maxillofacial Surgery of the University Hospital Schleswig-Holstein in Kiel, and they were reevaluated with standardized clinical and radiological exams. Kaplan-Meier analyses were performed for individual factors. Cox proportional hazard regression analysis was used to detect the factors influencing long-term implant failure. RESULTS: The long-term implant survival rate was 88.03% after an observation time of 12.2 to 23.5 years. Cox regression revealed statistically significant influences of the International Team for Implantology (ITI) implantation type (p = .00354) and tobacco smoking (p = .01264) on implant failure. A proportion 82.8% of the patients with implant losses had a medical history of periodontitis. Peri-implantitis was diagnosed in 9.7% of the remaining implants in the long-term survey. CONCLUSIONS: This study emphasized the long-term rehabilitation capabilities of Straumann dental implants in complex cases. The survival rates after several years constitute important information for patients, as well as for clinicians, in deciding about different concepts of tooth replacement. Patient-related and technical factors - determined before implant placement - could help to predict the risk of implant loss.

Targeting gene expression during the early bone healing period in the mandible: A base for bone tissue engineering.

PURPOSE: Although bone tissue engineering techniques have become more and more sophisticated than in the past, natural bone healing mechanisms have not been sufficiently considered for further improvement of these techniques so far. We used an established animal model with transcriptome analysis to generate an unbiased picture of early bone healing to support tissue engineering concepts. MATERIAL AND METHODS: In 30 Wistar rats, a 3-mm bone defect was created in the mandibular angle. Tissue was sampled at 5, 10, and 15 days, and the former defect area was excised to undergo transcriptome analysis after RNA extraction. Five differentially expressed genes were further evaluated with reverse transcription-polymerase chain reaction (rt-PCR). RESULTS: Transcriptome analysis revealed 2467 significantly over- and under-expressed transcripts after 5 days and 2265 after 15 days of bone healing, respectively. Validation via rt-PCR confirmed overexpression of osteoactivin, angiopoietin-like factor-4, and metallomatrix proteinase-9 and underexpression of mastcellprotease-10 and proteoglycane-2 in comparison to values in the control group. CONCLUSION: This systematic genome-wide transcriptome analysis helps to decipher the physiological mechanisms behind physiological bone healing. The exemplary depiction of 5 genes demonstrates the great complexity of metabolic processes during early bone healing. Here, BMP-2 signaling pathways and local hypoxia play decisive roles in bone formation.

Reconstruction of the orbital floor with polydioxanone: a long-term clinical survey of up to 12 years.

Fractures of the orbital floor are common in injured patients, who often require operation to prevent complications and, among other materials, polydioxanone is widely used. The aim of this study was to evaluate the long-term outcomes of fractures of the orbital floor that had been reconstructed with polydioxanone foil. A total of 101 patients (73 men and 28 women) who had reconstruction of the orbital floor for defects of 2cm(2) or smaller with polydioxanone implants, over a mean (SD) time period of 8 (2) years were evaluated. Sensitivity of the infraorbital nerve, ocular motility, and diplopia were evaluated and correlated with perioperative values. Persistent hyperaesthesia was found in 15 patients, whereas in another 15 the hyperaesthesia recovered completely over time. Three patients had double vision during follow-up. Twenty patients with preoperative diplopia had no persistent double vision postoperatively, and 15 patients with disturbed ocular motility recovered completely. Two patients had persistently disturbed motility, and one patient had enophthalmos. There was a significant association between hyperaesthesia preoperatively and postoperatively (p= 0.005). In most patients reconstruction of the orbital floor with polydioxanone was successful. Long-term complications such as diplopia, compromised bulbar motility, and hyperaesthesia of the cheek were seen in a few cases, but might not have been solely related to the use of polydioxanone.

Endocultivation: Histomorphological effects of repetitive rhBMP-2 application into prefabricated hydroxyapatite scaffolds at extraskeletal sites.

The timing of application of recombinant human bone morphogenic protein-2 (rhBMP-2) may be important in determining the final outcome of engineered bone tissue. This study investigates the impact of repetitive rhBMP-2 application on hard and soft tissue morphology in endocultivation. A 3D-printed scaffold was implanted into a pouch in the latissimus dorsi muscle in 40 Lewis rats. RhBMP-2 was injected at defined time points and animals received a total of 200 µg each. Control groups received either rhBMP-2 simultaneously with scaffold implantation, or solely a scaffold with no rhBMP-2. Fluorescence markers were injected after operation. CT-scans and histological examination were performed after 8 weeks. Multiple comparisons revealed significant differences of bone density between the groups who received delayed injections at two separate time points in time compared to those who had simultaneous rhBMP-2 application (p = 0.0038; p = 0.0063) and the control group (p = 0.017, p = 0.0284). The blood vessel count was significantly higher in groups with repetitive injections compared with both control groups. Two soft tissue types were identified and found to have different distributions in the different study groups. Fluorescence labeling showed active new bone formation after 4-5 weeks in all groups where rhBMP-2 was administered. Multiple repetitive injections were more effective than simultaneous application regarding bone density indicating time-dependent effects of rhBMP-2. Bone formation processes were detectable several weeks after rhBMP-2 application indicating long-term effects.

Periodontal regeneration employing gingival margin-derived stem/progenitor cells in conjunction with IL-1ra-hydrogel synthetic extracellular matrix.

AIM: This study investigated the periodontal regenerative potential of gingival margin-derived stem/progenitor cells (G-MSCs) in conjunction with IL-1ra-releasing hyaluronic acid synthetic extracellular matrix (HA-sECM). MATERIALS AND METHODS: Periodontal defects were induced at four sites in eight miniature pigs in the premolar/molar area (-4 weeks). Autologus G-MSCs were isolated from the free gingival margin and magnetically sorted, using anti-STRO-1 antibodies. Colony formation and multilineage differentiation potential were tested. The G-MSCs were expanded and incorporated into IL-1ra-loaded/unloaded HA-sECM. Within every miniature pig, four periodontal defects were randomly treated with IL-1ra/G-MSCs/HA-sECM (test group), G-MSCs/HA-sECM (positive-control), scaling and root planing (SRP; negative control-1) or left untreated (no-treatment group; negative control 2). Differences in clinical attachment level (ΔCAL), probing depth (ΔPD), gingival recession (ΔGR), radiographic defect volume (ΔRDV), and changes in bleeding on probing (BOP) between baseline and 16 weeks post-transplantation, as well as periodontal attachment level (PAL), junctional epithelium length (JE), connective tissue adhesion (CTA), cementum regeneration (CR) and bone regeneration (BR) at 16 weeks post-transplantation were evaluated. RESULTS: Isolated G-MSCs showed stem/progenitor cell characteristics. IL-1ra loaded and unloaded G-MSCs/HA-sECM showed higher ΔCAL, ΔPD, ΔGR, PAL, CR and BR as well as a lower JE compared to their negative controls and improved BOP. CONCLUSION: G-MSCs in conjunction with IL-1ra-loaded/unloaded HA-sECM show a significant periodontal regenerative potential.

Immunohistological expression of human ß-defensin-1 and human ß-defensin-2 in exacerbation of acute and secondary chronic osteomyelitis of the mandible.

BACKGROUND: The majority of patients diagnosed with osteomyelitis of the jaw have severe complaints. Unfortunately, the pathogenesis still remains unclear. Human ß-defensins expressed in epithelial and bone tissues as a part of the innate immunity may be involved in disease development. In this study, we hypothesize that expression levels of human ß-defensin-1 and -2 in the acute and secondary chronic osteomyelitis may be altered in comparison with healthy bone and with bisphosphonate-associated necrosis as well as irradiation from a previous study. METHODS: Bone samples were collected during surgical debridement in a total of eight patients suffering from acute or secondary chronic osteomyelitis of the jaw. Expression levels of hBD-1 and -2 were quantified and related to non-stained cells. Ratios were compared by one-way ANOVA and multiple tests by Holm-Bonferroni. RESULTS: Multiple testing revealed no significant differences for expression levels of human ß-defensin-1 between all groups, whereas labeling index of human ß-defensin-2 was significantly different between specimens of bisphosphonate-associated osteonecrosis of the jaws and all other groups. No significant difference occurred between samples of floride osteomyelitis and healthy bone for expression of hBD-1 and -2. CONCLUSIONS: Although the affected patients showed all clinical signs of acute inflammation, expression levels in acute and secondary chronic osteomyelitis in the jaws did not reveal statistically significant differences compared with healthy bone samples. The weak immunological host response in terms of a putative genetically predisposition should be further discussed as pathogenesis factor for osteomyelitis in the future.

Using eddy currents for noninvasive in vivo pH monitoring for bone tissue engineering.

PURPOSE: The metabolic processes that regulate bone healing and bone induction in tissue engineering models are not fully understood. Eddy current excitation is widely used in technical approaches and in the food industry. The aim of this study was to establish eddy current excitation for monitoring metabolic processes during heterotopic osteoinduction in vivo. METHODS: Hydroxyapatite scaffolds were implanted into the musculus latissimus dorsi of six rats. Bone morphogenetic protein 2 (BMP-2) was applied 1 and 2 weeks after implantation. Weekly eddy current excitation measurements were performed. Additionally, invasive pH measurements were obtained from the scaffolds using fiber optic detection devices. Correlations between the eddy current measurements and the metabolic values were calculated. RESULTS: The eddy current measurements and pH values decreased significantly in the first 2 weeks of the study, followed by a steady increase and stabilization at higher levels towards the end of the study. The measurement curves and statistical evaluations indicated a significant correlation between the resonance frequency values of the eddy current excitation measurements and the observed pH levels (p = 0.0041). CONCLUSIONS: This innovative technique was capable of noninvasively monitoring metabolic processes in living tissues according to pH values, showing a direct correlation between eddy current excitation and pH in an in vivo tissue engineering model.

Does pulsed magnetic field therapy influence nerve regeneration in the median nerve model of the rat?

The aim of this study was to evaluate the impact of pulsed magnetic field therapy on peripheral nerve regeneration after median nerve injury and primary coaptation in the rat. Both median nerves were surgically exposed and denervated in 24 female Wistar rats. A microsurgical coaptation was performed on the right side, whereas on the left side a spontaneous healing was prevented. The study group underwent a daily pulsed magnetic field therapy; the other group served as a control group. The grasping force was recorded 2 weeks after the surgical intervention for a period of 12 weeks. The right median nerve was excised and histologically examined. The histomorphometric data and the functional assessments were analyzed by t-test statistics and one-way ANOVA. One-way ANOVA indicated a statistically significant influence of group affiliation and grasping force (P = 0.0078). Grasping strength was higher on a significant level in the experimental group compared to the control group permanently from the 9th week to the end of the study. T-test statistics revealed a significantly higher weight of the flexor digitorum sublimis muscle (P = 0.0385) in the experimental group. The histological evaluation did not reveal any statistically significant differences concerning the histomorphometric parameters. Our results suggest that the pulsed magnetic field therapy has a positive influence on the functional aspects of neural regeneration. More studies are needed to precisely evaluate and optimize the intensity and duration of the application.

Sensoric protection after median nerve injury: babysitter-procedure prevents muscular atrophy and improves neuronal recovery.

The babysitter-procedure might offer an alternative when nerve reconstruction is delayed in order to overcome muscular atrophy due to denervation. In this study we aimed to show that a sensomotoric babysitter-procedure after median nerve injury is capable of preserving irreversible muscular atrophy. The median nerve of 20 female Wistar rats was denervated. 10 animals received a sensory protection with the N. cutaneous brachii. After six weeks the median nerve was reconstructed by autologous nerve grafting from the contralateral median nerve in the babysitter and the control groups. Grasping tests measured functional recovery over 15 weeks. At the end of the observation period the weight of the flexor digitorum sublimis muscle was determined. The median nerve was excised for histological examinations. Muscle weight (P < 0.0001) was significantly superior in the babysitter group compared to the control group at the end of the study. The histological evaluation revealed a significantly higher diameter of axons (P = 0.0194), nerve fiber (P = 0.0409), and nerve surface (P = 0.0184) in the babysitter group. We conclude that sensory protection of a motor nerve is capable of preserving muscule weight and we may presume that metabolism of the sensory nerve was sufficient to keep the target muscle's weight and vitality.

Peri-implantitis versus periodontitis: functional differences indicated by transcriptome profiling.

BACKGROUND: Periodontitis and Periimplantitis are oftentimes discussed as one entity, which is reflected by therapeutical as well as by scientific approaches. It is unclear, to which extent the similarity of the clinical characteristics is attributed to similarities in the underlying disease mechanisms. PURPOSE: The main objective of the study is to display if or how different periimplantitis and periodontitis are on the mRNA level, representing a high-resolution map of disease-associated events. MATERIALS AND METHODS: Aiming to describe the pathophysiological mechanisms in vivo, primary gingival tissue from 7 periimplantitis patients, 7 periodontitis patients and 8 healthy controls was employed in order to generate genome wide transcriptome profiles. RESULTS: On the basis of quantitative transcriptome analysis, we could show that periimplantitis and periodontitis exhibit significantly different mRNA signatures. Additionally we present a disease associated mRNA profile, which displays potential periimplantitis disease mechanisms. A gene ontology analysis revealed various pathways, supporting the hypothesis of periimplantitis being a complex inflammatory disorder with a unique pathophysiology. While in periimplantitis tissue the regulation of transcripts related to innate immune responses and defense responses were dominating, in periodontitis tissues bacterial response systems prevailed. CONCLUSIONS: Taken together, our results suggest considering periimplantitis and periodontitis as disease entities with shared as well as with distinct features, which should be reflected on the therapeutical as well as on the scientific level.

Induction of periimplantitis in dental implants.

Development, progression, and therapy of periimplantitis are nonresolved emerging problems. The aim of this pilot study was to establish a model for periimplantitis in mice to have a base for tests with immune-deficient knockout organisms to improve the knowledge about development and progression of periimplantitis and to develop further therapeutic options.In 8 mice, titanium implants were inserted in the median of the palate. Four of these implants had ligatures (periimplantitis group). After 2 weeks, the animals received a special diet enriched with sugar and flavor. After 9 weeks, micro-computed tomography (micro-CT) examinations to evaluate the periimplant tissue and histologies were performed.Dental implant insertions within the oral cavity are possible in living mice. Implants with ligatures showed significantly larger periimplant bone defects than controls. The radiologic findings were confirmed by histology. At the end of the observation period, the portion of implants lost was higher in the ligature group.This is the first publication to describe the insertion of dental implants in living mice. In addition, it is the first time that periimplant infection could be induced in that species. This model will pave the way to study knockout mice with reduced or even enhanced resistance to periimplantitis.

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.

Periodontal regeneration employing gingival margin-derived stem/progenitor cells: an animal study.

AIM: This study investigated the periodontal regenerative potential of gingival margin-derived multipotent postnatal stem/progenitor cells. MATERIAL AND METHODS: Periodontal defects were induced at six sites in eight miniature pigs in the premolar/molar area (-4 weeks). Autologous cells isolated from the gingival margin were magnetically sorted using STRO-1 antibodies and characterized flow cytometrically for the expression of CD14, CD31, CD34, CD45, CD117 and STRO-1 surface markers. Colony formation and multilineage differentiation potential were tested. The cells were expanded and loaded on deproteinized bovine cancellous bone (DBCB) and Collagen scaffolds. Within every miniature pig, six periodontal defects were randomly treated with loaded-DBCB (test group 1), unloaded-DBCB (control group 1), loaded-Collagen scaffolds (test group 2), unloaded-Collagen scaffolds (control group 1), scaling and root planing (negative control 1) or left untreated (negative control 2). Differences in clinical attachment level (ΔCAL), probing depth (ΔPD), gingival recession (ΔGR) and radiographic defect volume (ΔRDV) between baseline and 12 weeks, as well as histological attachment level (HAL), junctional epithelium length (JE) and connective tissue adhesion (CTA) after 12 weeks were evaluated. RESULTS: Isolated cells showed stem/progenitor cell characteristics. Cell-loaded scaffolds showed higher ΔCAL, ΔPD, ΔGR, HAL and lower JE and CTA compared with unloaded scaffolds and negative controls. The sort of scaffold had no significant influence on the measured outcomes. CONCLUSION: Gingival margin-derived stem/progenitor cells show significant periodontal regenerative potential.

Endocultivation: metabolism during heterotopic osteoinduction in vivo--monitoring with fiber optic detection devices.

Reconstructions of facial bone defects are one of the most challenging aspects in surgical treatment of malignant diseases, large facial traumata, or congenital anomalies. High-level reconstruction techniques are often associated with an elevated morbidity by the harvest of autologous bone grafts from the patient. Tissue engineering techniques may help to solve this problem. The aim of this study was to monitor metabolic processes during cellular colonization of matrices in vivo in an established rat model for endocultivation. After implantation of computer-designed hydroxyapatite scaffolds into the latissimus dorsi muscle of six rats, 100 µg bone morphogenetic protein-2 (BMP-2) was injected twice, in week 1 and 2, directly into the center of the matrices. The development of pH value and oxygen (O2) saturation inside the matrix was followed by fiber optic detection technique over 8 weeks and analyzed by variance analyses. Bone density measurements were performed by computed tomography as well as histological evaluations. Two weeks after implantation, oxygen supply and pH value measurements had decreased significantly. In the following weeks both parameters increased and stabilized on higher levels. This is the first study reporting a reproducible method to follow metabolic processes during heterotopic osteoinduction in vivo. It was shown that in the beginning of the study pH value and O2 saturation decreased and it took several weeks to regain physiological levels. This is an important step to further understand the physiological process of bone induction.