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Biomedical subjects

T A Turvey

Publications and source records attributed to T A Turvey.

At least 37 records · Page 2Linked to original sources
PubMed1991

Stability after surgical-orthodontic correction of skeletal Class III malocclusion. I. Mandibular setback.

Postsurgical stability of mandibular setback to correct mandibular prognathism was compared for three approaches: transoral vertical ramus osteotomy, bilateral sagittal split osteotomy with wire osteosynthesis and maxillomandibular fixation, and bilateral sagittal split osteotomy with rigid internal fixation via bone screws. In the transoral vertical ramus osteotomy group, the mean postsurgical change in chin position was almost zero, but nearly 50% of the patients did have clinically significant changes in chin position; two thirds of these movements were posterior and one third anterior. In the bilateral sagittal split osteotomy groups, the chin either stayed in its immediately postsurgical position or moved anteriorly. In one fourth of the patients who received maxillomandibular fixation and in nearly half of the patients who received rigid internal fixation, the chin moved forward more than 4 mm.

Adult↗
PubMed1990

Effects of trauma to the mandibular nerve on human perioral directional sensitivity.

The capacity of 4 patients who had previously experienced trauma to their mandibular nerves to distinguish opposing directions of tactile motion over the distribution of the mental nerve was compared to that of 8 neurologically normal adults. Brushing stimuli were delivered to the perioral region and were precisely controlled for their velocity, the length of skin traversed, the width of skin contacted, and the orientation and direction of motion. A temporal, 2-alternative, forced choice method was used to obtain estimates of directional sensitivity, d'. It was discovered that impairment in cutaneous directional sensitivity could be readily detected within areas of hypaesthesia. Although directional sensitivity was found to increase linearly with the length of skin traversed for both the patients and the neurologically normal adults, the slope and the x-intercept of the linear relationship differed between the two groups. The difference in the slope suggests that direction discrimination within the hypaesthetic areas is relatively insensitive to changes in the length of skin traversed. The difference in the x-intercept suggests that a greater length of skin must be traversed before any information about direction is made available at the hypaesthetic sites. The dependency of the capacity of neurologically normal and impaired individuals to process information about direction of tactile motion on the length of skin traversed and the velocity of stimulation suggests that a high degree of stimulus control is required for the detection and quantification of subtle neurosensory deficits.

Adolescent↗
PubMed1990

Alterations in velopharyngeal function after maxillary advancement in cleft palate patients.

Velopharyngeal function was assessed aerodynamically prior to surgery and at least 1 year following surgery in 24 cleft palate patients who underwent maxillary advancement. In 5 patients (23%) deterioration and in 5 patients (23%) improvement of velopharyngeal function was observed. In those patients whose velopharyngeal function improved, a pharyngeal flap was in place at surgery. Of the 5 patients whose velopharyngeal function deteriorated, 4 had adequate and 1 borderline adequate velopharyngeal function prior to surgery. In the remaining 14 patients, velopharyngeal function was unchanged. No relationship between the amount of maxillary advancement or the "need ratio" and velopharyngeal function was observed.

Adolescent↗
PubMed1990

Stability of mandibular advancement after sagittal osteotomy with screw or wire fixation: a comparative study.

Stability and clinical results in 70 patients who underwent bilateral sagittal ramus osteotomy for mandibular advancement were studied. The patients were grouped by the method of fixation (screws vs. wire) and matched for the amount of advancement. There were 35 patients in each group, and the age, sex, and presurgical mandibular plane angle distributions were similar for the two groups. Although the pattern of skeletal and dental changes during the first postsurgical year were quite different for the groups, stability, incisal opening, and clinical results were equivalent at 1 year following surgery. In the first 6 weeks postsurgery, the screw fixation group was more stable horizontally and vertically than the wire group, but between 6 weeks and 1 year, the wire group showed recovery, and the mean differences all but disappeared.

Adult↗
PubMed1990

Orbital emphysema causing vision loss after a dental extraction.

The use of high-speed air-cooled rotary cutting instruments is common in dental practices. When used near open wounds, the forced air can lead to subcutaneous emphysema and involvement of vital structures. This case highlights the unfortunate episode of orbital emphysema with optic nerve damage after a pneumatically cooled drill was used in the removal of a mandibular second molar.

Adult↗
PubMed1989

The effect of orthognathic surgery on occlusal force.

To investigate the effect of orthognathic surgery on occlusal force, such force was measured during maximum effort, chewing, and swallowing in 70 patients who had superior repositioning of the maxilla and/or mandibular advancement or setback. Larger changes in occlusal force than could be accounted for by the altered geometry were observed in all groups. Of 15 patients who had only superior repositioning of the maxilla, ten had greater than 20% increase in occlusal force, three had little change, and two showed a greater than 20% decrease. When the mandible was advanced, 11 of 34 patients had greater than 20% increase in maximum biting force, 11 had little or no change, and 12 had greater than 20% decrease. When the mandible was set back, six of the 21 patients had greater than 20% increase, nine had little or no change, and six had greater than 20% decrease. It appears that considerable change in bit force, which is not primarily related to jaw geometry, occurs after orthognathic surgery.

Bite Force↗
PubMed1989

Surgical orthodontic correction of mandibular deficiency by sagittal osteotomy: clinical and cephalometric analysis of 1-year data.

A homogeneous sample of 76 mandibular retrognathic patients (mean age, 28 years) were examined for postoperative alterations after surgical treatment by bilateral sagittal split osteotomy and mandibular advancement with wire fixation. Skeletal and dental measures were obtained from preoperative, immediate postoperative, fixation-release, and 1-year cephalograms. Spearman correlation was used as a preliminary analysis to assess the relationship between postsurgical change and age, genioplasty, amount of mandibular advancement, and preoperative mandibular plane angle. Genioplasty and amount of mandibular advancement were included as independent factors in the subsequent repeated-measures analysis of variance, since these were the only two factors that showed a consistent trend of correlations with postoperative change. Genioplasty was a significant factor in the X and Y coordinate changes in pogonion, while the amount of mandibular advancement was a significant factor in the X coordinate movements of all mandibular landmarks except gonion and condylion. The mean amount of horizontal advancement was 5.2 mm, and anterior face height increased 5.1 mm. During fixation, B point moved posteriorly (x = -1.6 mm, p less than 0.01) and inferiorly (y = 1.0 mm, p less than 0.01). After fixation release, these trends were reversed, resulting in a nonsignificant net horizontal change (x = -0.5 mm, p = 0.10) and a significant net superior movement (y = -1.3 mm, p = 0.01) by 1 year. Pogonion, menton, and mandibular incisor tip showed similar patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Surgical correction of vertical maxillary excess during adolescence.

The timing of orthognathic surgery for the correction of dentofacial deformities is controversial. The expected predictable response to treatment in a young adult patient with vertical maxillary excess is illustrated by a case report. The concerns of the patient were addressed both morphologically and psychosocially. Postponing treatment for this group of patients until growth has finally stabilized may have far-reaching consequences, although the risk of outgrowing the correction is minimized. A retrospective study of 20 adolescents who had surgical impaction of the maxilla is reported.

Adolescent↗
PubMed1989

Pathogenesis of cleft palate in Treacher Collins, Nager, and Miller syndromes.

Abnormalities of the secondary palate were studied in an animal model in which features of Treacher Collins syndrome (TCS) and Nager or Miller syndromes (both of which are facially similar to Treacher Collins, but include limb malformations) were induced by acute maternal exposure to 13-cis-retinoic acid (13-cis-RA, isotretinoin, Accutane). Previous work in our laboratory has illustrated that excessive cell death in the proximal aspect of the maxillary and mandibular prominences of the first visceral arch and in the apical ectodermal ridge of the limb bud probably accounts for the characteristic craniofacial and limb abnormalities observed (Sulik et al, 1987; Sulik and Dehart, 1988). The current study shows that maternal treatment with 400 mg per kilogram 13-cis-RA at 8 days 14 hours (8d14hr) or 9d6hr post fertilization results in abnormalities of the secondary palate that vary in incidence and severity. Following the earlier treatment time, 82 percent (68 of 74) of the 18d fetuses were affected, with, severely hypoplastic, unfused palatal shelves present in 34 percent (25 of 74). The less severely affected fetuses had malformations that involved primarily the posterior aspect of the palatal shelves. This malformation (foreshortening of the posterior portion of the palate) constituted the major developmental alteration that resulted from treatment at the later time, at which time a 52 percent (26 of 50) malformation incidence was seen. The change in pattern of malformations with treatment time is consistent with the changing pattern of programmed cell death, which was observed to occur in the first visceral arch.

Animals↗
PubMed1988

Alterations in nasal respiration and nasal airway size following superior repositioning of the maxilla.

Twenty patients who underwent superior repositioning of the maxilla via Le Fort I down fracture had their respiratory mode and nasal cross-sectional area determined prior to and 6 months following surgery. Inductive plethysmography and nasal air flow techniques were used in the determination of these parameters. Prior to surgery, five patients were nasal breathers, five were predominantly nasal breathers, six were oral-nasal breathers, and four were predominantly oral breathers. Nine patients had inadequate nasal airways. Six months following surgery, 14 patients were nasal breathers and six were predominantly nasal breathers. Sixteen patients had adequate nasal airways, three had borderline nasal airways and one had an inadequate nasal airway postsurgically. These findings suggest that superior repositioning of the maxilla by Le Fort I down fracture does not adversely affect nasal respiration. Nasal function actually improved in 17 of the 20 subjects studied.

Adolescent↗
PubMed1988

Simultaneous superior repositioning of the maxilla and mandibular advancement. A report on stability.

Fifty-three patients who underwent simultaneous surgical superior repositioning of the maxilla and mandibular advancement were studied cephalometrically and clinically for at least 1 year after surgery (mean 2.4 years). The pattern of change for the maxilla and the percentage of patients who had 2 mm or more movement of landmarks were consistent with that observed following isolated superior repositioning of the maxilla. Although changes similar to those observed with isolated mandibular movement occurred, because the changes in the maxilla also affected the mandible, a greater percentage of patients experienced postsurgical movement of the mandible in this group than in those undergoing mandibular advancement alone. Clinically, satisfactory or better results were observed in 42 (79%) patients at their longest follow-up examination. The only significant variable associated with clinical outcome was the presence (presurgically) of an open bite (p less than 0.04) in 10 of 11 patients with poor clinical results. There was no statistically significant relationship between cephalometric stability and clinical outcome in this series of patients.

Adolescent↗
PubMed1988

Orthognathic surgery: a significant contribution to facial and dental esthetics.

Esthetic dentistry was once a specialty of the family dentist and the orthodontist. Today it is a field for the prosthodontist, periodontist, oral and maxillofacial surgeon, and others. When jawbones are malpositioned, unesthetic facial contours can result, and dental compensations occur that can be additionally unattractive. Orthodontic attempts to correct malocclusion or other disharmonies of the dentition in affected individuals without surgical intervention can cause tooth instability and result in less than satisfactory cosmetic results. The treatment of orthognathic surgeons is especially well suited for full-face esthetic appearance--the picture the patient views each day in the mirror.

Adolescent↗
PubMed1987

Stability following superior repositioning of the maxilla by LeFort I osteotomy.

Cephalometric data from 61 patients who had undergone superior repositioning of the maxilla via LeFort I osteotomy by means of the downfracture technique were analyzed to evaluate stability of skeletal and dental landmarks at various time intervals up to 1 year. None of these patients had concurrent mandibular ramus or body osteotomy except genioplasty and all had at least 2 mm intrusion at the maxillary incisor or molar. In approximately 20% of the patients, there was 2 mm (critical value) or more postsurgical movement of skeletal or dental landmarks. During the first 6 weeks postoperatively, the maxilla showed a strong tendency to move farther upward in the patients in whom it was not stable. The posterior maxilla was vertically stable in 90% of the patients, the anterior maxilla in 80%. Horizontally, skeletal landmarks were stable in 80%, but when changes occurred, there was a tendency for the anterior maxilla to move back when it had been advanced. After the first 6 weeks, the posterior maxilla was stable vertically in all patients, but in 20% anterior maxillary landmarks moved downward, opposite to the direction of movement during fixation. In 11 of the 15 patients who demonstrated vertical changes postsurgery, the movement from fixation release to 1 year follow-up was opposite and approximately equal to the initial change, so that the net movement after 1 year was less than 2 mm. Only 6.5% (four patients) demonstrated 2 mm or greater net vertical movement for any of the variables studied 1 year after surgical treatment. There was no indication that the amount of presurgical orthodontic movement of incisors, the presence of multiple segments at surgery, the age of the patient, the presence or absence of genioplasty, or the presence or absence of suspension wires was a risk factor for instability.

Adolescent↗
PubMed1987

The nasal airway following maxillary expansion.

There have been suggestions that maxillary expansion may be justified on the basis of airway considerations alone. The present study assessed the effects of rapid maxillary expansion and surgical expansion on nasal airway size to determine how useful these techniques are for breathing purposes. The results demonstrate that both procedures generally improve the nasal airway. However, approximately one third of the subjects in both groups did not achieve enough improvement to eliminate the probability of obligatory mouth breathing. These findings suggest that maxillary expansion for airway purposes alone is not justified.

Adolescent↗