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Biomedical subjects

S R Thaller

Publications and source records attributed to S R Thaller.

At least 37 records · Page 2Linked to original sources
PubMed1994

Management of mandibular fractures.

The complex physiology of the masticatory system is extremely sensitive to its intricate anatomic relationships. With the ever-increasing number of patients admitted to our institution with traumatic facial injuries, it seemed an appropriate time to evaluate the most widely employed treatment modalities available for the management of mandibular fractures. Maxillomandibular fixation remains the mainstay of mandible fracture stabilization. Within recent years, rigid internal fixation with miniplates and screws has become popular. This study compares the results of the most commonly used treatment modalities available for the repair of acute mandibular fractures.

Adolescent↗
PubMed1994

The use of pericranial flaps in frontal sinus fractures.

Although injuries to the frontal sinus are a reasonably common traumatic injury encountered by reconstructive surgeons, definitive indications for open exploration and the optimum method for handling the residual sinus cavity remain unsettled. During the last 3 years, we have accomplished frontal sinus obliteration with an "extended" pericranial flap in 14 consecutive patients. Thus far, we have not encountered any complications.

Adolescent↗
PubMed1994

Teeth located in the line of mandibular fracture.

During the last decade, rigid internal fixation with mini plates and screws has attained widespread use for stabilization of facial bone fractures. This technique permits precise, three-dimensional stabilization of bony segments, decreases the time required for immobilization of the maxillo-masticatory apparatus, and allows patients to return to their preinjury state earlier. However, there is still controversy on the appropriate management of teeth located within the line of mandibular fractures. We review the outcome of teeth retained within the fracture. We performed a retrospective chart review of all patients admitted to the University of California, Davis, Medical Center with mandibular fractures from July 1, 1986, to June 30, 1991, who had retained at least 1 tooth and had had a 3-month follow-up. We were able to include a total of 254 patients who met these criteria. These patients were then divided into groups according to location of the fracture, method of stabilization, and management of dentition within the line of fracture. Data were then analyzed using a linear model to predict the percentages of success for each method of fixation. In conclusion, we found little difference in the outcome of fracture management whether the teeth were routinely extracted or retained as long as rigid fixation was employed for stabilization of the fracture segments.

Adolescent↗
PubMed1994

Repair of experimental calvarial defects with Bio-Oss particles and collagen sponges in a rabbit model.

Various materials have been used for reconstruction of both acquired and congenital calvarial defects. Unfortunately, each has its limitations. Autologous bone grafts have irregular rates of resorption that may require secondary corrective surgery, and individual harvest sites have limited stores that can necessitate additional donor locations. Alloplastic materials have unlimited quantities and volume stability but they may not become incorporated and are associated with a higher incidence of infection. The optimal bone substitute should stimulate new bone formation and permanently supplant the temporary space filler, thereby reconstituting the surgical defect. We evaluated 2 newly available bone substitutes, resorbable natural bone mineral (Bio-Oss particles) and a combination of collagen and natural bone mineral collagen combination (Bio-Oss sponges), to repair calvarial defects in an adult, male, New Zealand white rabbit model. We found that the particulate Bio-Oss material resorbed and then underwent the normal physiological stages of bone remodeling. The collagen and Bio-Oss combination was replaced by new bone ingrowth. These materials may have potential for use in the reconstruction of skull defects.

Animals↗
PubMed1993

Effect of insulin-like growth factor-1 on zygomatic arch bone regeneration: a preliminary histological and histometric study.

A number of physicians have attempted to pharmacologically manipulate the healing of bony fractures with a variety of agents such as growth hormone, thyroxine, chondroitin sulfate, and parathyroid hormone. Thus far, results from these experiments have been inconclusive. Previous research dealing with insulin-like growth factors has centered on cultures of osteoblast-like cells and has demonstrated a stimulatory effect on bone collagen synthesis, which may in fact play a critical role in the process of bone formation itself. The purpose of this investigation was to examine the effects of a genetically engineered growth factor, insulin growth factor type I, on midfacial fracture healing. In 24 adult male Sprague-Dawley rats, a standardized defect was created within the midportion of each zygomatic arch. One-half were treated with insulin growth factor type I administered with an osmotic infusion pump and the other half served as control subjects. At 2, 4, 8, and 12 weeks, animals from each group were killed and specimens of the defect obtained. Data were collected from radiographs and histological studies to compare the extent of bony repair. From this study, it appears that insulin growth factor type I could exert a potentiating effect on the repair of midfacial bone defects.

Animals↗
PubMed1993

The effects of insulin-like growth factor-1 on critical-size calvarial defects in Sprague-Dawley rats.

In a previous study prepared in 1992, we found that insulin-like growth factor-1 showed promise in hastening intramembranous bone repair in midfacial bone defects. For the present study, we created critical-size calvarial defects in 36 adult male Sprague-Dawley rats. The rats were then divided into two groups and killed at 1, 2, 3, 4, 5, 6, and 8 weeks. Twenty-one rats were administered insulin-like growth factor-1 subcutaneously with a 14-day osmotic infusion pump. An untreated group served as controls. Results were compared using routine histology to examine bone reconstitution of the surgical defects. Within the experimental group, we observed repair commenced at approximately 1 week and the critical-size calvarial bone defects were completely obliterated by 6 weeks; in the control group, even by 8 weeks, the surgical defects remained almost unchanged. In summary, this is further evidence that insulin-like growth factor-1 may have the potential to accelerate repair of intramembranous bone defects.

Animals↗
PubMed1993

The effect of insulin growth factor-1 on calvarial sutures in a Sprague-Dawley rat.

Early investigations attempting to determine the exact pathogenesis of premature closure of the cranial sutures were limited by the untoward sequelae caused by surgical procedures in animal models to simulate the development of craniosynostosis. In an attempt to create a model for evaluating the effects of manipulating the craniofacial sutures without the limitations of associated scarring, we conceived an animal prototype dependent on the effects of insulin growth factor-1 on the anterior frontal suture in a Sprague-Dawley rat model. The experimental group received 2 mg of IGF-1 over a 14-day period via a subcutaneously placed osmotic infusion pump, whereas the age-matched control group received no treatment. We present our preliminary histological results describing the effect of IGF-1 on calvarial sutures.

Animals↗
PubMed1993

Reconstruction of calvarial defects with anorganic bovine bone mineral (Bio-Oss) in a rabbit model.

Reconstructive surgeons have employed various procedures using either autogenous or alloplastic materials to repair cranial defects secondary to trauma, extirpative surgery, or congenital anomalies. Currently, the choice appears to be dependent on the personal choice or background of the operating surgeon. For years, our preference has been to use calvarial bone grafts as our primary source of reconstructive material. Disadvantages include uneven resorption of the bone grafts and limited quantities. For these reasons, bony substitutes present new possibilities for reconstruction of craniomaxillofacial defects. We evaluated Bio-Oss, which is a natural bone mineral derived from a bovine source that is chemically and physically identical to human bone, as a possible replacement material to reconstruct skull defects in a rabbit model.

Animals↗
PubMed1993

Fractures of the edentulous mandible: a retrospective review.

Treatment of edentulous mandibular fractures has remained somewhat controversial. A recent review of the literature showed that a number of techniques have been proposed with varying degrees of success. It was my clinical impression that I encountered an extremely high proportion of complications when caring for these injuries. For this reason, I performed a retrospective chart review of all patients with a diagnosis of mandibular fractures admitted to the University of California, Davis, Medical Center during the period July 1, 1989 to June 30, 1991. A total of 11 patients of 349 admissions were found to have edentulous mandibular fractures (3%). They were treated with a variety of techniques, including splints or dentures, intraosseous wire fixation, or rigid internal fixation with miniplates and screws. Successful results were obtained with each technique; however, the overall complication rate was 18% (2 patients), which was consistent with my overall results for the treatment of mandibular fractures. I recommend that no one technique is applicable to each fracture and that treatment must be individualized.

Adult↗
PubMed1993

Polyglyconate plates and screws to stabilize zygomatic osteotomies in a rabbit model.

Rigid internal fixation with miniplates and screws continues to be widely used in the correction of both congenital and acquired craniomaxillofacial deformities. This technique allows precise three-dimensional stabilization of bony segments. A number of recent reports have detailed some disadvantages, including potential growth restriction in developing children, bone resorption, infection, extrusion, and palpability. These problems have often necessitated secondary surgery for hardware removal. A biodegradable plate and screw system would eliminate these potential and real problems. Over the last 2 decades, there has been an escalating interest in developing satisfactory biodegradable materials for bony fixation. We have previously reported the initial phases of a long-term evaluation of various biomaterials currently available. The purpose of this study is to examine a biodegradable plate and screw system fabricated from a faster resorbing material--polyglyconate. This system would be applicable to pediatric reconstructive problems. Earlier studies have shown its tissue compatibility and feasibility for multiple surgical uses. Osteotomies were created at the midpoint of each zygomatic arch of 42 adult male white New Zealand rabbits. The animals were then divided into two equal groups. The first group served as a control and the bony segments were permitted to heal without stabilization, whereas in the experimental group, the bony segments were stabilized with biodegradable plates and screws made from polyglyconate. Animals were then sacrificed at 2, 4, 6, 8, 12, and 16 weeks, at which time radiographs were obtained. Zygomatic complexes were then removed en bloc, and routine hematoxylin and eosin slides were made for light microscopy. Without fixation, fracture segments became significantly displaced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Midfacial fracture repair in the adult rat.

The consensus in the literature is that fracture healing within the midface occurs via fibrous union. Clinical experience with the surgical correction of established traumatic deformities has not borne this out. An earlier histological examination with human biopsy specimens demonstrated that eventually repair occurred by direct bony union. However, a recent study in a rabbit model challenged this conclusion and indicated that the process of new formation resembles secondary bone formation as in endochondral formed bone. The purpose of our inquiry is to elucidate further the process of midfacial bony repair in an adult male Sprague-Dawley rat model.

Animals↗
PubMed1992

Midfacial fractures in the pediatric population.

Fractures to the midface in the pediatric age group are rare because the mandible and cranium provide protection and absorb most of the traumatic impact. In addition, these midfacial bones are extremely elastic. When caring for midfacial fractures, standard reconstructive procedures directed toward restoration of form and function must be met. Unfortunately, diagnosis of facial fractures may be difficult because it is very dependent on the site and severity of injury as well as the child's age. Fracture management is similar to that seen in adults with the major exception related to the developing dentition, which requires adjustments in the securing of intermaxillary fixation. Children will usually recover quickly and, fortunately, complications remain rare. It is important for clinicians to closely evaluate these patients for other associated injuries. Unfortunately, due to the small numbers and poor long-term follow-up, definitive conclusions are often difficult to obtain.

Accidental Falls↗
PubMed1992

Use of biodegradable plates and screws in a rabbit model.

During the last decade, rigid internal fixation with miniplates and screws has gained widespread acceptance in the correction of both congenital and acquired craniomaxillofacial deformities. Recent studies have proposed that the currently employed metallic plates and screws may require removal because of potential facial growth restriction in growing children. Others have reported bone resorption under the plate due to stress shielding, infection, extrusion, and palpability in regions where there is minimal tissue coverage. Because these implants are radiopaque, they generate significant that interfere with radiological studies and with radiation therapy in patients undergoing treatment for malignancies. There is no question that the use of a biodegradable plating system would eliminate each of these potential or real problems, because stability is necessary only for a reasonably short period until the fracture segments have become united. We report the initial phase of a long-term study examining various materials that will be available for fabrication of a biodegradable plate and screw system. We evaluated a commercially developed biodegradable plate and screw system to treat zygomatic arch fractures in a rabbit model. Fractures were surgically created at the midpoint of each zygomatic arch. The experimental animals were then divided into three equal groups. Fractures in the first group were permitted to heal without any form of stabilization. In the second group, segments were secured with standard titanium plates and screws. Biodegradable plates and screws were employed for stabilization in the experimental group. Animals were then killed, and radiographs were obtained at 2, 4, 6, and 8 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Surgical correction of unilateral lambdoid synostosis: occipital rotation flap.

Virchow (1851) is credited with initially describing calvarial development following premature closure of individual sutures. He noted that resultant compensatory growth occurred perpendicular to the fused suture, resulting in asymmetrical calvarial development. Lambdoid synostosis, whether unilateral, bilateral, or associated with other cranial fusions, is reasonably uncommon. Previous authors report an incidence of less than 10% of all reported cases of premature fusion of the calvarial or skull base sutures. We report 27 patients (20 boys, 7 girls) ranging in age from 3 months to 8 years with unilateral lambdoid craniosynostosis followed over a three-year period. In 19 patients, calvarial reshaping was performed by repositioning a parietooccipital bone flap stabilized with lag-screw fixation to provide an increased radius of curvature to the affected area and to reestablish the resultant craniectomy between the parietooccipital junction and into the posterior fossa retromastoid occipital bone as an appropriate site for growth. Indications for one-stage calvarial reshaping included untreated lambdoid stenosis in older children or a failed simple lambdoid synostectomy after approximately 18 months. Each child experienced significant improvement in calvarial shape and ipsilateral ear position. Although we had no operative complications, two children underwent a second outpatient procedure for removal of hardware palpated by their parents.

Bone Screws↗
PubMed1992

Care of maxillofacial injuries: survey of plastic surgeons.

The purpose of this survey was to evaluate the current trends in the care of facial trauma. Data were obtained through the responses of a survey mailed to all those members and candidates listed in the 1989 American Society of Plastic and Reconstructive Surgeons Directory. A total of 2777 questionnaires were sent, with 1113 (40 percent) returned by means of a self-addressed envelope. Demographic results show that over 70 percent of the treating plastic surgeons fall within the age range 30 to 50 years. Although significant advances have occurred, treatment goals have remained unchanged. These center around the principles of accurate reduction and precise stabilization of fracture segments. The results of this survey reveal that a number of acceptable techniques were employed in the surgical repair of mandibular and zygomatic complex fractures. In the care of Le Fort III fractures, 59 percent of the respondents preferred the use of miniplates and screws for stabilization. Only 26.8 percent believed that facial fracture repair should be performed within the initial 24 hours. With frontal sinus fractures, the vast majority of plastic surgeons (82.1 percent) obtained a neurosurgical consultation. When the posterior wall was involved, 45.6 percent favored removal of the sinus mucosa, 29.7 percent obliterated the frontal sinus with a variety of autogenous materials, while 20.5 percent preferred cranialization. In summary, this survey shows a wide variation in the practice of facial fracture management within the plastic surgical community.

Adult↗
PubMed1991

Pediatric mandibular fractures.

In spite of curiosity, facial fractures, particularly mandibular fractures, in the pediatric age group embrace only a modest proportion of facial fractures that occur within the general population. Several large series report an overall incidence of approximately 1% of all facial bone fractures. A considerable volume of literature has been generated describing the pattern of injury and treatment modalities for pediatric facial bone fractures. At our institution, which is an extremely busy university-based regional trauma center, we have witnessed a persistent escalation in the number of patients requiring repair of their facial bone fractures. During the period of January 1989 through January 1990, we treated a total of 204 patients for repair of mandible fractures. An analysis of the records of this group revealed only 3 patients who were younger than 4 years of age and 2 additional patients younger than 8 years. There were another 10 patients 17 years and younger, for a total incidence of 0.08%. Additionally, we found that within this seemingly small group, there was a surprisingly high incidence of severe, associated injuries.

Adolescent↗
PubMed1991

Maxillofacial trauma: a potentially fatal injury.

Trauma remains one of the fastest growing causes of death in the United States, especially within the young adult population. Injuries to both the soft tissue and bony skeleton of the face constitute a high percentage of all traumatic admissions that pass through many emergency rooms. Because maxillofacial injuries are often dramatic, they can easily divert attention away from other medical priorities. In spite of numerous significant advances, the management of maxillofacial trauma remains a challenging problem for all reconstructive surgeons. From reading the literature, it can be assumed that maxillofacial trauma is rarely life threatening or an immediate cause of death, unless associated with airway compromise. We present our experience with 6 illustrative patients who either succumbed to complications or had life-threatening exsanguination secondary to isolated facial trauma.

Adult↗