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Biomedical subjects

K Vargervik

Publications and source records attributed to K Vargervik.

At least 37 records · Page 2Linked to original sources
PubMed1989

Posttraumatic condylar hyperplasia.

Posttraumatic condylar hyperplasia can result in complex facial asymmetry composed of degrees of condylar and ramus overgrowth, malocclusion, and complementary maxillary deformity. Three patients with unilateral condylar hyperplasia are described to illustrate the scope of surgical and orthodontic treatment required to restore facial symmetry. Condylar hyperplasia with facial asymmetry should be recognized as a possible consequence of condylar injury, and further delineation of the onset and natural history of this deformity could lead to investigations or intervention before the establishment of all the components of the deformity.

Adolescent↗
PubMed1989

Retrognathism.

Retrognathia is a common deformity that generally requires both orthodontics and surgery for correction. The surgical correction of the problem is best completed in the majority of cases with the sagittal splitting osteotomy. While the surgery is generally successful, relapse is a formidable problem. Instrument registration methods for properly positioning the condyles are being developed, but at this time are not totally successful. Lag screw fixation of the segments is very stable and seems to limit relapse but requires a facial incision with a resulting scar. Future technology probably will allow for internal placement of lag screws. Until such techniques are available, the use of intermaxillary fixation followed by an elastics activated registration bite splint to facilitate healing is recommended.

Adult↗
PubMed1987

Aesthetic improvement resulting from craniofacial surgery in craniosynostosis syndromes.

A consecutive series of 21 patients with craniosynostosis syndromes (9 Crouzon's, 6 Pfeiffer's, 6 Apert's) was evaluated for reconstructive postoperative aesthetic improvement resulting from craniofacial surgery (Le Fort III, sliding genioplasty, nasal septal reconstruction and cranioplasty). The same consecutive series of patients had been previously evaluated for stability of Le Fort III advancement. All the patients were assessed at least one year post operatively. Stability of the advancement was confirmed. In the present study, various midline bony and soft tissue profile measurements were obtained from lateral cephalograms. These measurements were compared to similar measurements (standards) in normals. "Normal" standards and "normal" appearance imply harmonious and aesthetically pleasing facial features. This study showed markedly abnormal positions of the selected bony and soft tissue landmarks preoperatively compared to the normal but following surgery the measurements studied approached or were similar to the normal standards. Based on these measurements, the patient's appearance improved significantly following reconstructive craniofacial surgery. Suggestions for additional surgery based on these studies are made.

Acrocephalosyndactylia↗
PubMed1987

Changes in zygomatic arch position following experimental lateral displacement.

In order to obtain information about the stability of augmentation procedures in the area of the zygomatic arch, the zygomatic arch on one side was displaced laterally in eight rhesus monkeys by an osteotomy of the anterior portion of the arch and placement of an 8 mm bone graft obtained from the supraorbital ridge. The other side served as a control. The post-operative changes were studied on submento-vertex head films during a 24 month follow-up period. Three months post-operatively the amount of lateral displacement was reduced by 55%. During the next 9 months of follow-up only small changes occurred in the individual animals, and the mean values remained predominantly unchanged. Between 12 and 24 months the distance from the zygomatic arch to the midline increased with growth. On the control side this distance increased from three months on. At 24 months only 18% of the difference in width that was created by the surgical repositioning remained.

Animals↗
PubMed1987

Maxillary hypoplasia secondary to midfacial trauma in childhood.

Three normal children who suffered midfacial trauma and developed midfacial retrusion that would require Le Fort III advancements for correction of the deformity are described. The common denominator in these three cases seems to be an injury to the medial facial structure including the nasal septum. It is concluded that midfacial fractures in childhood may be a cause of subsequent midfacial hypoplasia.

Adolescent↗
PubMed1987

Surgical treatment of the jaw deformities in hemifacial microsomia.

The surgical treatment of the mandibular and maxillary deformities in patients with hemifacial microsomia requires some form of mandibular lengthening. This is usually either via ramus interpositional bone grafting or end-on bone grafting. In a few cases, ramus lengthening may be completed by a sagittal split. Once the mandible has been reconstructed, the maxillary surgery can be completed. In previous forms of treatment, mandibular bone grafting was completed without regard to function and neuromuscular adaptation and a significant percentage of such procedures completed failed. Egil Harvold and his colleagues developed a method by which changes in form and function are co-ordinated by using a functional appliance resulting in neuromuscular adaptation. After the bone grafting is completed, as the second of six phases of treatment, a specially designed registration bite-block further facilitates neuromuscular adaptation by controlling mandibular movements (function), but in addition it protects the bone graft from excessive forces thereby aiding in osteogenesis (third phase). The theoretical basis, classification of deformities, and phases of treatment developed are presented and the surgery is described in detail. The results of a consecutive group of patients treated by these methods is then presented. While this form of treatment is not the only one possible, it is the only one that has been tested in the laboratory, proven in patient care, and stood the test of time.

Adolescent↗
PubMed1986

Stability of the maxilla after Le Fort III advancement in craniosynostosis syndromes.

The purpose of this study was to assess long-term position of the maxilla after surgical Le Fort III advancement of midfacial structures in patients with craniosynostosis syndromes. Data from preoperative, short and long-term postoperative lateral head films on 21 consecutive patients with Crouzon's syndrome, Pfeiffer's syndrome, or Apert's syndrome were analyzed. A method of evaluating the position of the postoperative maxilla on lateral head films is described. On average, the position of the maxilla did not change significantly in the postoperative periods studied, although some individual variation was demonstrated. Postoperative management, utilizing a registration bite splint after the intermaxillary fixation has been removed, similar to our treatment following bone grafting procedures in patients with hemifacial microsomia, is described.

Acrocephalosyndactylia↗
PubMed1986

Factors affecting long-term results in hemifacial microsomia.

Mandibular malformations in patients with hemifacial microsomia are described and six phases of treatment outlined. Growth of the malformed mandibular ramus in response to functional appliance treatment was studied in 15 subjects with type I mandibular malformations. It was found that length increase of the affected side during the treatment period was not significantly different from the growth of the other side. Changes in length of the affected side of the mandible following surgical repositioning and bonegrafting was assessed in 25 consecutive cases. In 10 of these subjects, the surgical procedure was done during the growth period and in 15 of them after growth had ceased. In the still growing subjects, there was additional length increase of the reconstructed mandibular ramus, but on an average, less than on the side which had normal temporomandibular joint structures. In seven cases, the length increase was similar on the two sides ( +/- 2 mm) or greater on the affected side, and the established symmetry was maintained. In three subjects, there was recurrence of asymmetry, which in two individuals was corrected by a second surgical lengthening of the mandible. There was minimal loss in length of the reconstructed mandibular ramus in the nongrowing subjects and the established mandibular position was maintained.

Activator Appliances↗
PubMed1985

Neuromuscular adaptation of craniofacial muscles to altered oral sensation.

Experimentally induced changes in oral sensation to the tongue altered the use of specific craniofacial muscles. An acrylic wedge was anchored to the maxillary teeth of ten adult rhesus monkeys, providing a tactile-pressure sensation to the dorsal surface of the tongue. Fifteen craniofacial and tongue muscles were studied by electromyography during the first 6 months of adaptation. The results showed that there was an overall shift in those muscles that were normally tonically active in the craniofacial region. Muscles of the suprahyoid region, the geniohyoid and digastric, as well as the platysma muscle of the face, and the lateral pterygoid muscle were tonically active in more animals after placement of the wedge. In contrast to the enhanced activity of mandibular and facial muscles that function during mandibular depression, only the anterior temporalis muscle in the superficial and deep region demonstrated more tonic activity. The superficial and deep masseter regions, as well as the medial pterygoid muscle, demonstrated no change in their EMG activity. Only the lip muscles and mentalis demonstrated increased activity, whereas the facial muscles with more vertically oriented fibers did not demonstrate any increased activity. These findings suggest that a change in the tactile stimulation to the tongue can induce a new balance in the level of activity of specific craniofacial muscles and that this altered neuromuscular pattern can remain throughout the first 6 months of adaptation.

Adaptation, Physiological↗
PubMed1985

Response to activator treatment in Class II malocclusions.

A clinical study was designed to disclose the effects of activator treatment in the correction of Class II malocclusions. The rationale for the use of the activator appliance was based on the premise that correction of distocclusion can be achieved by inhibition of forward growth of the maxilla, inhibition of mesial migration of maxillary teeth, inhibition of maxillary alveolar height increase and extrusion of mandibular molars, increased growth of the mandible, anterior relocation of the glenoid fossa, mesial movement of mandibular teeth, and combinations of these effects. The appliance, as designed for this study, could potentially have an effect on all of these factors. Measurements were obtained from cephalometric head films obtained at 6-month intervals. Matched-pairs analyses of control versus treatment change after 6 months and after 1 year of treatment were done on 36 and 29 pairs, respectively. Pretreatment versus treatment changes were analyzed on 33 subjects by means of the spline regression analysis; posttreatment versus treatment changes were analyzed on 18 subjects by means of the Student Newman-Keuls multiple comparison test. The matched-pairs analyses of mean values demonstrated significant reduction in forward growth of the maxilla, uprighting of the maxillary incisors, reduced overjet, leveling of the mandibular occlusal plane, improved molar relationship, downward and forward relocation of the glenoid fossae, increased advancement of all mandibular structures, increased face profile angle, and increased lower face height. The two longitudinal analyses yielded similar findings, but some differences were noted. Because rather severe dental malocclusions were corrected, the slight average inhibition of maxillary growth and the anterior relocation of glenoid fossae alone could not account for the correction of the Class II dental arch relationship. It was therefore concluded that, in addition to the statistically significant changes, smaller changes occurred in several areas without being consistent enough or of a large enough magnitude to become statistically significant in the analyses of mean values. Comparison of group averages may mask treatment effects that significantly contribute to the correction of malocclusions in individual cases.

Activator Appliances↗
PubMed1984

Morphologic response to changes in neuromuscular patterns experimentally induced by altered modes of respiration.

The present experiment was designed to test whether specific recordable changes in the neuromuscular system could be associated with specific alterations in soft- and hard-tissue morphology in the craniofacial region. The effect of experimentally induced neuromuscular changes on the craniofacial skeleton and dentition of eight rhesus monkeys was studied. The neuromuscular changes were triggered by complete nasal airway obstruction and the need for an oral airway. Alterations were also triggered 2 years later by removal of the obstruction and the return to nasal breathing. Changes in neuromuscular recruitment patterns resulted in changed function and posture of the mandible, tongue, and upper lip. There was considerable variation among the animals. Statistically significant morphologic effects of the induced changes were documented in several of the measured variables after the 2-year experimental period. The anterior face height increased more in the experimental animals than in the control animals; the occlusal and mandibular plane angles measured to the sella-nasion line increased; and anterior crossbites and malposition of teeth occurred. During the postexperimental period some of these changes were reversed. Alterations in soft-tissue morphology were also observed during both experimental periods. There was considerable variation in morphologic response among the animals. It was concluded that the marked individual variations in skeletal morphology and dentition resulting from the procedures were due to the variation in nature and degree of neuromuscular and soft-tissue adaptations in response to the altered function. The recorded neuromuscular recruitment patterns could not be directly related to specific changes in morphology.

Animals↗
PubMed1984

Experimentally induced neuromuscular changes during and after nasal airway obstruction.

Neuromuscular changes were studied by electromyography in rhesus monkeys which adapted to nasal obstruction for 2 years and then in the succeeding year recovered to nasal respiration. Obstructing the nasal passage with silicone plugs induced specific behavioral responses which remained for the duration of nasal obstruction and were lost within 8 days after removal of the plugs. Animals demonstrated individual variations, but more than 80% consistently maintained a lower mandibular posture for the entire 2-year period. Rhythmic mandibular, tongue, and upper lip movements were evident in fewer than 60% of the animals. Certain craniofacial and tongue muscles (the genioglossus, dorsal tongue fibers, digastric, geniohyoid, dilator naris, and vertically oriented fibers of the superior orbicularis oris, that is, lip-elevator fibers) were recruited rhythmically and remained rhythmically active throughout the entire 2-year period of nasal obstruction. This rhythmic activity ceased within 1 week after removal of the nose plugs. A tonic or consistent discharge was also induced in the genioglossus, dorsal tongue fibers, the geniohyoid, superior orbicularis oris, and lip-elevator fibers over the entire 2 years of nasal obstruction. Not all muscles lost their tonic discharge after removal of the nasal plugs. The genioglossus, geniohyoid, inferior orbicularis oris, and lip-elevator fibers discharged tonically during the recovery period. These data suggest that nasal obstruction can induce neuromuscular changes which extend beyond the period of obstruction and remain after the original stimulus for neuromuscular change has been removed.

Airway Obstruction↗
PubMed1984

Neuromuscular patterns in hemifacial microsomia.

This study was designed to establish the extent of neuromuscular abnormalities in different types of hemifacial microsomia and to relate these findings to the existing skeletal malformations. Neuromuscular recruitment patterns were established in twenty-three normal subjects. These patterns served as baselines for comparison with recruitment patterns obtained from forty-eight subjects with hemifacial microsomia. The anterior and posterior temporalis, masseter, suprahyoid, buccinator, platysma, mentalis, and upper and lower lips were studied electromyographically. Consistent presence or absence of recruitment for a given task was considered a significant finding with which the hemifacial microsomia data were compared. The subjects with hemifacial microsomia were divided into five groups according to type of mandibular malformation. Abnormal recruitment was found in all recorded muscles except the lips, mentalis, and buccinator muscles. There were variations in recruitment patterns within each group as well as among the groups. A relationship was found between the development of the gonial angle area and the recorded masseter activity. Muscle activity was recorded in the area of the temporal muscle, even in the absence of a coronoid process. It was found that after insertion into a new coronoid process the temporal muscle developed mass and palpable contraction. This study shows that in persons with hemifacial microsomia certain neuromuscular patterns may differ from the norm because of missing or underdeveloped muscles and because of the different relationship between the mandible, its attached muscles, and other structures.

Adolescent↗
PubMed1983

Nasal airway function as it relates to the timing of mid and lower facial osteotomies.

It has been established in primate studies that mouth-breathing can affect lower facial development. We submit that mouth-breathing has a similar effect on human development--specifically, that chronic mouth-breathing during growth contributes to long-face syndrome. When reconstructive surgery is contemplated for this deformity, we believe that the sequence of surgical steps is important and that particular attention should be given to enhancing nasal respiration. The possibility that mouth-breathing is a factor in relapse following mandibular surgery is discussed.

Adolescent↗
PubMed1983

Growth characteristics of the premaxilla and orthodontic treatment principles in bilateral cleft lip and palate.

Sixty-three individuals with complete bilateral cleft lip and palate (BCLP) were studied. In 51 of these subjects no surgical set-back or early bone grafting procedures were done. In the other 12 subjects early surgical procedures to reduce the prominence of the premaxilla had been done. In the larger group the premaxilla was, on the average, protrusive until age 12, after which it gradually became more retrusive. By the end of the growth period the premaxilla was not excessively protrusive in any of these subjects. It was concluded that it is advantageous for the premaxilla in individuals with BCLP to be protrusive during most of the growth period, since the premaxilla grows forward at a slower rate than the mandible. In the 12 subjects with premaxillary surgery, midface retrusion was demonstrated at an early age. The forward growth of the premaxilla in these individuals was slower than in the BCLP without premaxillary surgery and all 12 subjects developed rather severe midface retrusion. Orthodontic treatment principles for four different stages of craniofacial and dental development have been outlined.

Adolescent↗