Biomedical subjects

T A Turvey

Publications and source records attributed to T A Turvey.

At least 19 recordsLinked to original sources

PubMed1992

Superior repositioning of the maxilla combined with mandibular advancement: mandibular RIF improves stability.

Postsurgical changes in 24 patients who had rigid internal fixation (RIF) of the mandible with screws after combined superior repositioning of the maxilla and mandibular advancement were compared with 53 patients who underwent the same surgery but who had intraosseous wire fixation, skeletal suspension wires, and 8 weeks of maxillomandibular fixation (MMF). During the first 8 weeks after surgery, the mean posterior relapse of the mandible was greater in the MMF group than in the RIF group (for example, -1.1 mm versus 0.15 mm at B point), and the percentage of patients with clinically significant vertical and horizontal changes was greater in the MMF group. By 1 year, there had been slight additional mean relapse in the MMF group (-1.5 mm net relapse at B point, with 42% of the patients showing 2 mm or more relapse). In the RIF group, the mandible was more likely to be repositioned forward than posteriorly (net mean change at B point, 0.7 mm forward; 33% had 2 mm or more forward movement). In the RIF group, all but one of the patients (96%) were judged to have an excellent clinical result; in the MMF group, the corresponding figure was 60%.

Adult↗

PubMed1992

Surgical-orthodontic correction of mandibular deficiency: five-year follow-up.

Changes in dental and skeletal relationships at 5 years postsurgery were evaluated in a group of 35 patients whose mandibular deficiency had been corrected by the same surgeon, using sagittal split osteotomy of the mandibular ramus. From 1 to 5 years postsurgery, there was a small (0.9-mm) but statistically significant mean decrease in mandibular length (condylion to point B). In six patients, the decrease in mandibular length was 2 to 4 mm, and in two it was more than 4 mm, but only one of these individuals had more than a 2-mm increase in overjet. There was no mean change in overjet, but three patients had a 2 to 4-mm increase. Of these, one had 3.2 mm shortening of the mandible, one had 1.4 mm shortening of the mandible, and one had no change in mandibular length but repositioning of the incisors. Most patients had a deep overbite initially, and there was a tendency for the bite to deepen between the first and fifth years postoperatively, more as a result of extrusion of incisors than of mandibular rotation. Remodeling of the gonial angle area, with vertical and/or horizontal repositioning of gonion, was noted in more than half the subjects. It appears that morphologic changes related to continued skeletal remodeling, often compensated for by small changes in mandibular posture or tooth positions, continue after 1 year postsurgery for many patients.

Adolescent↗

PubMed1991

The effect of orthognathic surgery on head posture.

Changes in resting head and neck posture were studied in 201 patients following five different orthognathic surgery procedures: (1) LeFort I osteotomy for superior repositioning (intrusion) of the maxilla (n = 45); (2) bilateral sagittal split ramus osteotomy for mandibular advancement (n = 78); (3) mandibular setback (n = 19); (4) combined maxillary intrusion and mandibular advancement (n = 46); (5) combined maxillary intrusion and mandibular setback (n = 13). Head and neck posture were measured on standardized serial cephalograms taken in natural head position prior to, immediately after, and 1 year after surgery for each subject. Immediately after surgery, there was flexion of the head as measured by the craniovertical and craniocervical angles in all of the groups except the mandibular setback group, which showed little change. By 1 year post-surgery, the mean craniovertical and craniocervical angles were approximately the same as before surgery in the groups with one-jaw surgery. Statistically significant head flexion at 1 year (P less than 0.05) was observed in the combined maxillary intrusion and mandibular advancement group, and with maxillary intrusion plus mandibular setback, there was a trend toward persistent flexion. Neck posture showed no significant short- or long-term changes in any of the surgical groups.

Adult↗

PubMed1991

Stability after surgical-orthodontic correction of skeletal Class III malocclusion. 2. Maxillary advancement.

Nearly half the patients with skeletal Class III malocclusion have maxillary deficiency as the major component of their problem, and modern surgical techniques allow maxillary osteotomy to correct the deformity. Changes at surgery and postsurgically were studied in 49 patients who underwent isolated surgical maxillary advancement. Thirty-one had wire osteosynthesis and maxillomandibular fixation, and 18 had rigid fixation with bone plates. In nearly half the patients, the maxilla was moved down as well as forward, indicating that the patient had both vertical and anteroposterior deficiency. In the anteroposterior plane, 80% of the patients had excellent stability at 1 year, while 20% had 2 to 4 mm of posterior movement of anterior maxillary landmarks. There was no difference in anteroposterior stability between wire/maxillomandibular fixation and rigid internal fixation groups. When the maxilla was moved down as well as forward, there was a strong tendency for relapse upward in both fixation groups. As a result, the chin frequently became more prominent from immediate postsurgery to 1-year followup, as upward movement of the maxilla allowed the mandible to rotate upward and forward.

Adult↗

PubMed1991

Surgical mandibular advancement in adolescents: postsurgical growth related to stability.

Ten of 12 adolescents treated with surgical mandibular advancement showed postsurgical mandibular growth, as indicated by an increase in the distance from condylion to pogonion. In all cases, the growth was expressed vertically relative to the cranial base, so that the chin did not come forward. None of the patients had significant increments of anterior maxillary growth postsurgically. Several patients had vertical maxillary growth, which was compensated by vertical mandibular growth, so that the anteroposterior position of the chin was maintained. Forward growth of the maxilla is minimal after the peak of the adolescent growth spurt, and results of mandibular advancement surgery can be acceptably stable after that time.

Adolescent↗

PubMed1991

Stability after surgical-orthodontic corrective of skeletal Class III malocclusion. 3. Combined maxillary and mandibular procedures.

Stability after combined Le Fort I and bilateral sagittal split osteotomies was reviewed in 51 patients with skeletal Class III malocclusion. Because vertical changes in the position of the maxilla affect both the vertical and anteroposterior positions of the mandible, the sample was subdivided by the direction of vertical movement of the maxilla at surgery. Excellent postsurgical stability was observed in the long-face Class III patients in whom upward and forward movement of the maxilla was combined with ramus osteotomy to prevent excessive forward rotation of the mandible. When the maxilla was moved forward and the mandible set back with minimal vertical change, moderate relapse tendencies were observed in both jaws, but most of the correction was maintained at 1 year. When the maxilla was moved down and forward while the mandible was set back, moderate vertical relapse of the maxilla and anteroposterior relapse of the mandible followed. Stability of the downward movement of the maxilla was, on average, better than that resulting from maxillary surgery alone.

Adult↗

PubMed1991

Lag screw versus position screw techniques for rigid internal fixation of sagittal osteotomies: a comparison of stability.

Both lag screw and position screw techniques have potential advantages and disadvantages when used for securing sagittal osteotomies of the mandible. This study evaluated 56 patients undergoing bilateral sagittal split osteotomies for mandibular advancements. Osteotomies were fixed with either a position screw or lag screw technique using 2-mm self-threading screws. Five cephalometric points and two angles were used to evaluate skeletal changes. There were no statistically significant differences in the postsurgical movement of point B or the mandibular incisor. There were slight statistically significant differences in the horizontal and vertical movements of gonion. Overall, similar postoperative stability existed in both groups. Gonion and gonial angle changes were detected cephalometrically but had no effect on the clinical outcome.

Adult↗

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↗