Periosteal elevation induces supracortical peri-implant bone formation.

PURPOSE: The aim of the study was to evaluate the possibility of supracortical peri-implant bone formation after periosteal elevation. MATERIALS AND METHODS: Periosteal elevation with an elevation height of 5 or 10 mm was performed in an animal experiment with 24 female domestic pigs. For this purpose, four implants were inserted in the frontal bone of each animal. The implants protruded from the local bone by 5 or 10 mm. In the test groups, the periosteum was attached to the protruding implants. In the control groups, the implants were covered with biocompatible degradable periosteal-shielding devices. Each 8 animals were sacrificed after 20, 40 and 60 days. De novo bone formation was evaluated radiographically and histologically. RESULTS: Bone formation rate was higher in the test groups compared to the control groups after 20, 40 and 60 days. After 40 and 60 days, a statistically significant higher (P < 0.01) bone formation rate was found for both elevation heights. The maximum height of the generated bone was statistically significantly higher (P < 0.01) in the test groups for both elevation heights, compared to the control groups for all time points investigated. CONCLUSION: Periosteal elevation by dental implants is a treatment option for supracortical peri-implant bone formation.

Vestibuloplasty: porcine collagen matrix versus free gingival graft: a clinical and histologic study.

BACKGROUND: A free gingival graft (FGG) is currently the gold standard for augmenting small areas of keratinized mucosa. The porcine collagen matrix (CM) represents an alternative to autologous tissue harvesting. This study aims to compare the CM versus FGGs for augmenting keratinized peri-implant mucosa based on clinical and histologic evaluations. METHODS: The study included 14 patients who underwent a vestibuloplasty with either a FGG from the palate (n = 7) or the CM (n = 7). An implant-fixed vestibular retention splint was inserted for 30 days. Follow-up examinations were performed at 4, 10, 30, and 90 days after surgery. Width of keratinized mucosa was measured in the region of each implant (days 10, 30, and 90). After 90 days, a biopsy was harvested for histologic and immunohistologic analyses. To characterize newly formed soft tissue, the authors stained for tissue-and differentiation-specific markers, cytokeratin (CK) 5/6, 13, and 14, to detect presence or absence of keratinization. RESULTS: The groups showed similar healing, with increased peri-implant keratinized mucosa. The CM group had overall significantly shorter operation times than the FGG group. Both groups showed similar overall shrinkage (32.98% CM versus 28.35% FGG). All biopsies showed a multilayered, keratinized, squamous epithelium. CKs 5/6 and 14 were detected in the basal and suprabasal layers, and spots of CK 13 were detected in the suprabasal layer. CONCLUSIONS: During the whole observation period, both groups showed comparable clinical and histologic outcomes. Within the limitations of the present study, CM seems to be a promising alternative for the regeneration of keratinized mucosa without tissue harvesting. Comparative long-term studies are needed to investigate changes over time.

Guided bone regeneration in pig calvarial bone defects using autologous mesenchymal stem/progenitor cells - a comparison of different tissue sources.

Due to donor side morbidity and the absence of osteogenic properties in bone substitutes, there is a growing need for an alternative to traditional bone grafting within the scope of tissue engineering. This animal study was conducted to compare the in vivo osteogenic potential of adipose-derived (AD), periosteum-derived (PD) and bone marrow-derived (BM) mesenchymal stem/progenitor cells (MSC). Autologous mesenchymal stem/progenitor cells of named tissue origin were induced into osteogenic differentiation following in vitro cell expansion. Ex vivo cultivated cells were seeded on a collagen scaffold and subsequently added to freshly created monocortical calvarial bone defects in 21 domestic pigs. Pure collagen scaffold served as a control defect. The animals were sacrificed at specific time points and de novo bone formation was quantitatively analyzed by histomorphometry. Bone volume/total defect volume (BV/TV) and the mineralization rate of newly formed bone were compared among the groups. In the early stages of wound healing, up to 30 days, the test defects did not show better bone regeneration than those in the control defect, but the bone healing process in the test defects was accelerated in the later stage compared to those in the control defect. All the test defects showed complete osseous healing after 90 days compared to those in the control defect. During the observation period, no significant differences in BV/TV and mineralization of newly formed bone among the test defects were observed. Irrespective of the tissue sources of MSC, the speed and pattern of osseous healing after cell transplantations into monocortical bone defects were comparable. Our results indicate that the efficiency of autologous AD-MSC, PD-MSC and BM-MSC transplantation following ex vivo cell expansion is not significantly different for the guided regeneration of bone defects.

Guided bone regeneration: dynamic procedures versus static shielding in an animal model.

Due to its osteoinductive potential, the periosteum plays a crucial role in the process of neoosteogenesis. Therefore, periosteal elevation can lead to new bone formation in an artificially created space. In this study, we compared dynamic periosteal elevation with static shielding in an animal experiment. Different elevation/shielding heights of 5, 10, and 15 mm were tested with regard to various consolidation periods. Histological analysis, histomorphometry, and microradiography were used to measure the quantity and quality of the newly formed bone. No significant differences regarding bone quantity or quality were found between the two techniques. The cumulative results for the bone regeneration in the space created by distraction/elevation were about 66% in the dynamic and 67% in static procedure. The main advantages of both techniques are minimal invasion and low morbidity. In terms of clinical applications, periosteal elevation could be applied in cranio-maxillofacial surgery, in pre-implant augmentation and in reconstructive surgery.

Bone regeneration in osseous defects-application of particulated human and bovine materials.

OBJECTIVE: Different bone substitute materials are used to manage the challenge of local bone loss subsequent to craniofacial reconstructive surgery. In this animal study we examined the de novo bone formation in bone defects after insertion of Puros Allograft of human origin or Navigraft of bovine origin, and compared the regenerative potential of each material to that of autogenous bone. STUDY DESIGN: Using the adult domestic pig as the animal model, we created identical bone defects in the frontal skull and filled them with the different test materials using random assignment. A defined number of defects remained unfilled to serve as control. We performed microradiographic, histologic, and polychromatic fluorescence labeling evaluations of the bone specimens at 1, 8, and 12 weeks after the procedure. RESULTS: Both of the materials that we tested allowed for complete bony consolidation of the defects by the end of the test period. After 12 weeks, the microradiographically measured mineralization rate was 5% to 10% lower than the mineralization rate of autogenous bone grafts. CONCLUSION: Both Puros Allograft and Navigraft met the clinical requirements for bone substitutes, promoting predictable regeneration of the bony defects.

Conventional radiographs: are they still the standard in localization of projectiles?

The penetration of air gun pellets in facial soft tissue can cause major problems during the removal of foreign bodies, although conventional radiography, computed tomography, image-guided surgical removal, and ultrasound have been applied to facilitate the procedure. It was the aim of the present case report to introduce a modified intraoperative method for the localization of air gun pellets, based on the use of radiopaque markers in conventional radiographs. A 66-year-old patient attempted to commit suicide by using an air gun. The pellet hit the right temporal region. A computed tomographic (CT) scan was acquired to localize the foreign body. The first attempt to remove the pellet through the penetrating wound failed. Because of a dislodgement of the pellet, the CT scan could no longer be used for the localization of the air gun pellet. As the air gun pellet was positioned under the zygomatic arch, ultrasound was unable to identify its position. Successful intraoperative localization of the projectile was performed after fixation of radiopaque markers to the skin in the region of the estimated localization, with conventional radiographs in 2 planes, acquired with a mobile dental x-ray device. Although the markers remained attached to the patient as reference makers, the air gun pellet was removed easily. The use of radiopaque markers in conventional radiographs in 2 planes allows fast, intraoperative localization of radiopaque foreign bodies within soft tissue. The procedure can be carried out with a conventional x-ray device that should be available in every oral and maxillofacial practice. The use of reference markers should be considered a standard procedure for the localization of radiopaque foreign bodies in the head and neck.