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Biomedical subjects

P G Mozsary

Publications and source records attributed to P G Mozsary.

12 recordsLinked to original sources
PubMed1990

Rigid endosseous implant utilized as anchorage to protract molars and close an atrophic extraction site.

A two-stage endosseous implant, placed in the retromolar area of the mandible was utilized as rigid anchorage to translate two molars 10-12 millimeters mesially into an atrophic endentulous ridge. Despite substantial anchorage demand over a three year period, the endosseous implant remained rigid ("osseointegrated"). At the end of treatment the implant and adjacent, intravitally labeled bone were recovered. Microradiographic and polarized light analyses revealed that about 80 percent of the endosseous portion of the implant was in direct contact with mature lamellar bone. Bone labels demonstrated a remarkably high remodeling rate (about 30 percent/year) for cortical bone within 0.5 millimeter of the interface. Continuous remodeling may be the long-term mechanism whereby loaded implants resist bone fatigue and maintain "osseointegration." Clinical use of orthodontic implants, placed outside the dental arches, requires careful attention to soft tissue management.

Adult↗
PubMed1985

Microsurgical correction of the injured inferior alveolar nerve.

The pathology of inferior alveolar nerve injuries is discussed and the general and special guidelines for microsurgical reconstructive procedures are presented. Twenty-three cases are summarized: 22 cases showed marked restoration of nerve function after surgery.

Anesthesia, Local↗
PubMed1984

Circadian rhythm of mechanically mediated differentiation of osteoblasts.

Rats entrained to alternating 12 h light/dark periods were sacrificed at hourly intervals over one complete circadian cycle. Each animal was injected with 3H-Thymidine 1 h before death. Autoradiographs of serial sections of maxillary first molar periodontal ligament (PDL) were prepared. Nuclear volume was determined for labeled fibroblastlike PDL cells along a physiological bone forming surface. Preosteoblasts (large nuclei), the immediate proliferating precursors of osteoblasts, were found to synthesize DNA primarily during the environmental light period and divide during the subsequent dark cycle. Less differentiated precursor cells (small nuclei), the proliferating predecessors of preosteoblasts, were in S phase primarily during the dark period and divided in the following light cycle. Since previous studies have indicated, the stress/strain-mediated increase in nuclear size to form preosteoblasts also requires about 8-12 h, the least complex osteoblast differentiation model, which is consistent with the present data, is a 60 h sequence involving at least four cell types and five alternating dark/light cycles. The principal rate-limiting step in osteoblast differentiation is the mechanically related shift in nuclear size (change in genomic expression) associated with formation of preosteoblasts.

Animals↗
PubMed1984

Osseous adaptation to continuous loading of rigid endosseous implants.

Titanium implants, with an acid-etched surface, were screwed into holes 3 mm in diameter, about 1 cm apart, carefully prepared with an internally irrigated, surgical bur in the femurs of 3- to 6-month-old rabbits. During the first 3 days after surgery, fluorescent bone labels revealed extensive bone formation, particularly at the endosteal margin of the surgical defect, indicating preservation of a high degree of osteogenic capacity. A lattice of coarse, woven bone began encapsulating the implant within 3 days. By the end of 6 weeks, mature, lamellar bone filled voids at or near the implant surface and a rigid bone/implant interface was routinely achieved. Nonspecific, subperiosteal bony hypertrophy was noted within 6 weeks after implants were placed in young, growing animals (3 months old), but not in adults (6 months old). After 6 to 12 weeks of healing, a 100-gm load was applied for 4 to 8 weeks by stretching a stainless steel spring between the implants. All but one of twenty loaded implants remained rigid. Immediate loading of four pairs of implants resulted in spontaneous spiral-type ("torsional") fractures of the femur within 1 week. These results indicate that (1) relatively simple and inexpensive titanium implants develop a rigid osseous interface, (2) 6 weeks is an adequate healing period, prior to loading, to attain rigid stability and avoid spontaneous fracture, (3) continuously loaded implants remain stable within the bone, (4) bone formation is observed on periosteal surfaces subjected to concave flexure (compression), (5) cancellous-type bone orients perpendicularly between loaded implants, apparently corresponding to lines of stress, (6) new secondary osteons are propagated at or near the surface of loaded implants, (7) the remodeling (turnover) cycle for rabbit compact bone is about 6 weeks, and (8) endosseous implants have potential as a source of firm osseous anchorage for orthodontics and dentofacial orthopedics.

Animals↗
PubMed1983

Microsurgical reconstruction of the infraorbital nerves.

The pathogenesis of damage to and the microsurgical anatomy of the infraorbital nerve are reviewed. Indications for surgery and a microsurgical technique for decompression and scar removal or anastomosis of the nerve are presented. Results from seven surgical cases indicate a high degree of successful regeneration, with complete return of sensation occurring in six cases.

Humans↗
PubMed1982

Nuclear size as a cell-kinetic marker for osteoblast differentiation.

A nuclear morphometric assay for preosteoblasts is introduced as a cell-kinetic technique, applicable to routine histological preparations of mineralized tissue. Because this method is a morphological marker for osteoblast precursor cell differentiation, it provides a new dimension for determining the mechanism of osteoblast histogenesis. Osteoblast precursors of the periodontal ligament are a mixed population of progenitors, kinetically separable into two distinct groups according to nuclear size. Preosteoblasts, the immediate proliferating precursors of osteoblasts, have large nuclei (greater than 170 micrometers3) and are derived from relatively undifferentiated fibroblastlike cells, which have smaller nuclei (less than 80 micrometers3). Increase in nuclear volume, during G1 phase of the cell cycle, is apparently a morphological manifestation of change in genomic expression. This key event in preosteoblast differentiation is related to mechanical stress/strain and may be an important rate-limiting step in osteoblast histogenesis.

Animals↗