ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Frontoethmoidal encephaloceles are herniations of the intracranial contents through a defect in the skull at the junction of the frontal and ethmoidal bones. They are generally classified as nasofrontal, nasoethmoidal, and naso-orbital, although there may be some overlap or multiplicity. The records of 35 patients treated for frontoethmoidal encephaloceles were examined. Of these, 12 cases with complete and accurate medical records were evaluated in detail. The successful correction of frontoethmoidal encephaloceles was shown to depend on the following: a detailed understanding of the pathological anatomy (such as interorbital hypertelorism rather than true orbital hypertelorism and the presence of secondary trigonocephaly), careful planning of the bone movements to correct these deformities, and attention to detail regarding the placement of scars, positioning of the medial canthi, and the nasal reconstruction. Avoiding the “long-nose” deformity often seen after repair should be a priority. In general, the authors recommend a one-stage repair with both a transcranial and external approach.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Various agents have been theoretically and experimentally implicated as mediators of distraction osteogenesis (DO). The purpose of this study was to develop a vehicle for the potential delivery of these factors to the region of the distraction site in an attempt to manipulate this biologic process. Three adult mongrel dogs (12 months old) had oblique osteotomies performed bilaterally through the gonial regions. In group I, the external distracter was affixed to the right hemimandible of two dogs (n = 2 hemimandibles) with cannulated pins (external diameter = 1.5 mm; lumen diameter = 1.0 mm; length = 60 mm), whereas the distracter on the left was affixed with standard, noncannulated pins of the same dimensions. In group II, cannulated pins were used to affix the external distracter to both hemimandibles (n = 2 hemimandibles) of a dog. The devices were activated after a 5-day latency period and were lengthened at a rate of 1 mm/day for 20 days. During the distraction period, 0.1 ml/d of sterile india ink was injected into the cannulated pins, after which the sterile stylet was replaced. The activation protocol was followed by 28 days of fixation (consolidation period). The hemimandibles from group I underwent removal of soft tissues, acetone fixation, and gross examination/photography, whereas the hemimandibles from group II were prepared for histologic evaluation (whole mount, hematoxylin and eosin staining). All dogs survived to the end of the study and demonstrated successful DO without evidence of complications. Hemimandibles in group I displayed evidence of india ink on both the lingual and buccal cortex around the cannulated pin site, in the regenerate and on the neocortices of the distracted segment. Hemimandibles of group II showed histologic evidence of the india ink being deposited densely around the cannulated pin site and extending in a radial fashion around the pin site into the regenerate. This study demonstrates for the first time a vehicle device for the delivery of an inert dye to the regenerate site during distraction osteogenesis. This vehicle offers the potential of delivery of various factors implicated in distraction osteogenesis (i.e., mitogens) in an attempt to alter this process and also substances (i.e., chemotherapy, antibiotics, etc.) for use in the treatment of various osteopathies.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The position of mandibular teeth is difficult to document in the neonatal patient. Panorex images are difficult to obtain in an uncooperative pediatric patient. The new technique presented by the authors uses computed tomographic data to create a curved, reformatted image of the mandible, and generates an image similar to a panorex image. This curved, reformatted mandibular image provides accurate visualization of the mandible and mandibular teeth. This technique allows for precise pin placement and osteotomy in distraction osteogenesis.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The purpose of this study, based on three-dimensional (3-D) computed tomographic (CT) reconstructions, was to evaluate the relation between underdevelopment of masticatory muscles and hypoplasia of the craniofacial skeleton in hemifacial microsomia (HFM). In 25 patients with HFM and 19 control patients the volumes of the masseter, the temporal, and the medial-pterygoid and lateral-pterygoid muscles were measured on the basis of CT scans, using three-dimensional segmentation and voxel addition. The size and shape of the craniofacial structures were classified, using three-dimensional imaging based on CT scans. Contiguous 1.5-mm computed tomography scans were made with a Philips Tomoscan 350 and processed by a Cemax 1500X 3-D workstation. Using the Pearson product moment correlation coefficient, the Pruzansky/Kaban classification system, the new Craniofacial Deformity Scoring System, Cranial Deformity Scoring System, and Mandibular Deformity Scoring System (MDS) demonstrated correlation coefficients with the “masseter muscle percentage” varying from 0.71 to 0.81 (P< 0.05), with the medial pterygoid muscle percentage correlation coefficient varying from 0.43 to 0.56 (P< 0.05), with the lateral pterygoid muscle percentage correlation coefficient varying from 0.55 to 0.61 (P< 0.05), and with the temporal muscle percentage correlation coefficient varying from 0.67 to 0.84 (P< 0.05). The normal right/left difference in volume of the masticatory muscles of the control patients, calculated as a percentage of the total, demonstrated small differences of 3.4% to 4.8%. Bony malformations are associated with underdevelopment of the masseter and the temporal muscles, and demonstrate a tendency toward a clear relationship. The degree of muscular underdevelopment of the different muscles of mastication in one patient could vary widely. The normal right/left difference of the masticatory muscles of the control patients is minimal. The volume of the masticatory muscles of the nonaffected side does not demonstrate a compensatory effect in patients with HFM.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

In bony defects of the cranium, bone healing may be complicated by prolapse of surrounding tissue into the defect. This tissue acts as an impediment to prevent the migration of osteogenic cells, leading to impaired bone formation. It has been previously shown that a membrane placed over the bony defect inhibits the connective tissue cells from entering the wound and theoretically improves bone formation. The use of a proven resorbable material, Lactosorb, is used in this animal model and has shown a significant increase in autogenous bony formation. The majority of previous work was accomplished with nonresorbable material that resulted in foreign body formation. This paper is unique because resorbable material in the animal model is relatively inexpensive and easy to use and has allowed successful autogenous bony regeneration.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

This study aimed to clarify the relation between the anatomical variations of the pterygomaxillary region and fracture of the pterygoid plate during Le Fort I osteotomy. We present a secure method to separate maxillary tuberosities from pterygoid plates without injuring the pterygoid plates. Thirty specimens of hemisection of Korean skulls were used for the study. The maxilla was sectioned transversely on the floor of the pyriform aperture and posteriorly to the lateral pterygoid plate with a mechanical saw. The section was 5 to 6 mm above the tooth roots. The pterygomaxillary junction was separated with a curved osteotome in two steps: initially with light tapping of the shallow groove 2 to 3 mm anterior to the pterygomaxillary fissure at a half right angle and then changing the course of forceful tapping to more than 60°. The maxillary tuberosity separated from the medial and lateral pterygoid plates during the procedure was grouped into the “disjunction group” (24 of 30, 80%) and the pterygoid plates fractured were grouped into the “fracture group” (6 of 30, 20%). The thickness of the pterygomaxillary region (T) was significantly greater in the disjunction group than in the fracture group (P= 0.034). The concavity of the pterygomaxillary fissure (C) was significantly deeper in the disjunction group than in the fracture group (P= 0.020). There was no significant difference of width of the pterygomaxillary fissure between the disjunction group and the fracture group (P= 0.169). The thin pterygomaxillary region and less concave pterygomaxillary fissure on the preoperative computed tomography scan draw precautionary attention to vulnerable pterygoid plates fractured in the procedure of Le Fort I osteotomy.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Eggshell has been recently introduced as a bone substitute candidate in reconstructive surgery. The aim of this experimental study study was to determine its degradation rate in both a skeletal and extraskeletal site. In experiment 1, eggshell particles with four different sizes (50, 75, 150, and 300 &mgr;m in diameter) were implanted in subcutaneous pouches of 30 rats. In experiment 2, a fragment of ostrich eggshell was implanted on the nasal dorsum of 10 rats. Animals were sacrificed at 1 (N = 10), 2 (N = 10), and 4 months (N = 10) during the first stage of the study, and at 1 year during the second stage of the study. The results were assessed by X-ray examination and routine histological techniques. In experiment 1, all animals healed uneventfully. At 1 month, only 50-&mgr;m particles had undergone resorption. At 2 months, both 50-and 75-&mgr;m particles had undergone resorption. At 4 months, the 150-and 300-&mgr;m particles were resorbed incompletely. Histologically, the eggshell elicited a mild inflammatory reaction at 1 month that decreased progressively at further stages. In experiment 2, all animals except one healed uneventfully. Radiologically, the eggshell implant displayed a noticeable stability. Histologically, seven of nine implants were encapsulated, but two of them were surrounded by a bony rim. In conclusion, eggshell is a resorbable implant, but the degradation kinetic is size dependent. Large ostrich grafts are also suitable as onlay graft, but a complementary osteosynthesis is recommended to enhance osteointegration.

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

An intraindividual comparative study of proximal tibial marrow defects in nine adult Goettinger miniature pigs (GMPs) was undertaken. The left side of the defect was filled with granular &bgr;-tricalcium phosphate (TCP) ceramic ad modum Cerasorb, and the right side was filled with granular &agr;-TCP ceramic ad modum Biobase &agr; pore. Simultaneously, dental screw implants were inserted in each ceramic and fixed within the orthotopically replanted corticalis lids. Control defects were made in two other animals. The survival period ranged from 4 to 86 weeks (control study, 16 and 20 weeks). The reorganization and degree of bone regeneration, dynamics of ceramic degradation, and remodeling characteristics of the bone regenerate referring to osseo-integration of the dental implants were examined histomorphologically in nondecalcified specimens. The results reveal that both ceramic types were osteoconductive exclusively. Centripetally oriented angiogene bone regeneration occurred at the margins of the circular defects. Ceramic degradation was performed hydrolytically and within cells. Furthermore, it was demonstrated that decomposition of the intratrabecularly integrated ceramic residues underlies a dynamic process of degradation. Within 86 weeks, nearly 80% to 90% of the larger &agr;-TCP granules, and nearly 90% to 95% of the &bgr;-TCP granules were degraded. At this time, especially for the &agr;-TCP modification, ceramic microparticles were found in the marrow, either unbound or within polynuclear macrophages. The predictable degradation of both ceramic types provides an early functional adaptation of bone regenerates and facilitates a biofunctional, anisotropic orientation of the neotrabeculae without delay. It is concluded that because of the initially pronounced accumulation of macrophages, dental implants should not be inserted simultaneously with ceramic, but after further progress of ceramic degradation (5 to 6 months after TCP implantation).

ISSN:1049-2275    

出版商:OVID    

年代:2001

数据来源: OVID