Biomedical subjects

C A Trotman

Publications and source records attributed to C A Trotman.

At least 19 recordsLinked to original sources

PubMed2001

Design and effectiveness of a computer-based continuing education program for orthodontists.

The design of computer-based continuing education for health professionals is an important consideration for Internet delivery because the size of graphic files greatly affects the speed with which information is delivered. Orthodontists who had indicated an interest in computer-based continuing education were shown via CD-ROM either a dynamic version of a computer continuing education program (with transitions and animations to liven up the content) or a plain version (identical content except that the transitions and animations were omitted). The program provided new information about superelastic arch wires for the initial stage of orthodontic treatment. For both versions, over 90% of the viewers thought the program was well done and provided useful information. Six of the orthodontists who received the dynamic version felt that the animations were distracting rather than helpful; only one who received the plain version felt that it was lifeless. A follow-up questionnaire showed that two-thirds of those who viewed the program had subsequently reviewed the performance data for the initial wire they were using and 20% had changed it, so the computer program was effective in changing clinical behavior. Those who saw the plain version also were more likely to have changed their clinical procedures. For Internet delivery of information to highly motivated professionals, it appears that transitions and animations are not necessary and may be more likely to decrease than increase the effectiveness of the teaching material.

Adult↗

PubMed2001

Three dimensional analysis of facial movement in normal adults: influence of sex and facial shape.

The aim of this study was to quantify facial movements in a sample of normal adults and to investigate the influence of sex and facial shape on these movements. The study sample consisted of 50 healthy adult subjects, 25 males and 25 females (age: mean = 27.3 years; range = 23-39 years). A video-based tracking system was used to track small-diameter retroreflective markers positioned at specific facial sites. Subjects were instructed to make 7 maximum facial animations from rest, and the facial movements for each animation were characterized as the vectors of maximum displacement. Hotelling's T2 was used to test for significant sex differences in facial movements. In order to determine the effects of facial shape on facial movements, an index of facial shape was first calculated for each subject, and then a mixed-model ANOVA was used with facial shape (index), sex, and the interaction between facial shape and sex as fixed effects and subject as a random effect. The results demonstrated specific movement patterns for each animation. In general, males had larger movements than females and facial shape had a small but significant effect on facial movements. By comparing patient movements with the data from this large normative sample, the utility of this method to assess region-specific movement deficits was demonstrated.

Adult↗

PubMed2000

Three-dimensional nasolabial displacement during movement in repaired cleft lip and palate patients.

The objective of this study was two-fold: (1) to explore the suitability of a novel modified Procrustes fit method to adjust data for head motion during instructed facial movements, and (2) to compare the adjusted data among repaired unilateral (n = 4) and bilateral (n = 5) cleft lip and palate patients and noncleft control subjects (n = 50). Using a video-based tracking system, three-dimensional displacement of 14 well-defined nasolabial landmarks was measured during four set facial animations without controlling for head motion. The modified Procrustes fit method eliminated the contributions of head motion by matching the most stable landmarks of each video-recorded frame of the face during function to frames at rest. Its effectiveness was found to approximate that of a previous method (i.e., use of a maxillary occlusal splint to which stable dentition-based markers were attached). Data from both the unilateral and bilateral cleft lip and palate patients fell outside the normal range of maximum displacements and of asymmetry, and individual patients demonstrated greater right-versus-left asymmetry in maximum displacement than did individual noncleft subjects. It is concluded that the modified Procrustes fit method is fast, is easy to apply, and allows subjects to move the head naturally without the inconvenience of a splint while facial movement data are being collected. Results obtained using this method support the view that facial movements in cleft patients may be severely hampered and that assessment of facial animation should be strongly considered when contemplating surgical lip revisions.

Adolescent↗

PubMed1999

Maxillary growth in patients with clefts following secondary alveolar bone grafting.

OBJECTIVE: This investigation evaluated the effects of secondary alveolar bone grafting on subsequent maxillary growth in cleft patients. DESIGN: This was a retrospective longitudinal cephalometric study. Nineteen patients who had received secondary alveolar bone grafts were matched to a control sample by sex, cleft, availability of longitudinal records, and presurgical cranial base dimensions and growth direction. All patients had at least two lateral cephalometric radiographs before surgery and two radiographs after surgery. SETTING: The records were obtained from the Longitudinal Growth Study of the Lancaster (Pennsylvania) Cleft Palate Clinic. INTERVENTIONS: All patients had received similar primary surgical procedures by the same surgeon, no orthopedics, and similar mixed-dentition orthodontics. Secondary alveolar bone grafting was the only surgical intervention different between the two groups. MAIN OUTCOME MEASURES: Six measures of maxillary sagittal and vertical growth were taken from 235 radiographs. Slopes of the regression lines for each growth dimension were compared between groups both pre- and postsurgically. RESULTS: There were no significant between-group differences in maxillary sagittal or vertical growth following the grafting procedure. Anterior maxillary vertical growth rates decreased in the grafted group when their pre- and postsurgical rates were compared. Several growth trends in the postsurgical period were found to be continuations of the rates documented presurgically and unrelated to the grafting procedure. CONCLUSIONS: When evaluated longitudinally, maxillary growth in patients having received secondary alveolar bone grafting did not differ from a group of matched controls.

Adolescent↗

PubMed1998

Measurement of facial soft tissue mobility in man.

OBJECTIVE: The assessment of facial mobility is a key element in the treatment of patients with facial motor deficits. In this study, we explored the utility of a three-dimensional tracking system in the measurement of facial movements. METHODS AND RESULTS: First, the three-dimensional movement of potentially stable facial soft-tissue, headcap, and dental landmarks was measured with respect to a fixed space frame. Based on the assumption that the dental landmarks are stable, their motion during a series of standardized facial animations was subtracted from that of the facial and headcap landmarks to estimate their movement within the face. This residual movement was used to determine which points are relatively stable (< or = 1.5 mm of movement) and which are not (> or = 1.5 mm of movement). Headcap landmarks were found to be suitable as references during smile, cheek puff, and lip purse animations, and during talking. In contrast, skin-based landmarks were unsuitable as references because of their considerable and highly variable movement during facial animation. Second, the facial movements of patients with obvious facial deformities were compared with those of matched controls to characterize the face validity of three-dimensional tracking. In all instances, pictures that appear to be characteristic of the various functional deficits emerged. CONCLUSIONS: Our results argue that tracking instrumentation is a potentially useful tool in the measurement of facial mobility.

Adolescent↗

PubMed1998

Sensitivity of a method for the analysis of facial mobility. I. Vector of displacement.

OBJECTIVE: (1) To determine which facial landmarks show the greatest movement during specific facial animations and (2) to determine the sensitivity of our instrument in using these landmarks to detect putatively abnormal facial movements. DESIGN: Movements of an array of skin-based landmarks on five healthy human subjects (2 men and 3 women; mean age, 27.6 years; range, 26 to 29 years) were observed during the execution of specific facial animations. To investigate the instrument sensitivity, we analyzed facial movements during maximal smile animations in six patients with different types of functional problems. In parallel, a panel was asked to view video recordings of the patients and to rate the degree of motor impairment. Comparisons were made between the panel scores and those of the measurement instrument. RESULTS: Specific regions of the face display movement that is representative of specific animations. During the smile animation, landmarks on the mid- and lower facial regions demonstrated the greatest movement. A similar pattern of movement was seen during the cheek puff animation, except that the infraorbital and chin regions demonstrated minimal movement. For the grimace and eye closure animations, the upper, mid-facial, and upper-lip regions exhibited the greatest movement. During eye opening, the upper and mid-facial regions, excluding the upper lip and cheek, moved the most, and during lip purse, markers on the mid- and lower face demonstrated the most movement. We used the smile-sensitive landmarks to evaluate individuals with functional impairment and found good agreement between instrument rankings based on the data from these landmarks and the panel rankings. CONCLUSION: The present method of three-dimensional tracking has the potential to detect and characterize a range of clinically significant functional deficits.

Adult↗

PubMed1998

Sensitivity of a method for the analysis of facial mobility. II. Interlandmark separation.

OBJECTIVE: This study demonstrates a method of quantifying facial movements based on distortions of the skin surface. DESIGN: Landmarks were identified on the faces of five healthy human subjects (2 men and 3 women; mean age, 27.6 years; range, 26 to 29 years), and the distortions were characterized by changes in the separation between 20 pairs of landmark distances during specific maximal facial animations: smile, lip purse, cheek puff, grimace, eye closure, and eye opening. Data were recorded with a video-based tracking system for a period of 3 seconds at a sampling rate of 60 Hz or frames per second. For each subject, we analyzed the change in the separation of 20 pairs of landmarks, of which the majority were bilaterally symmetrical and functionally active. RESULTS: Characteristic patterns of movement emerged for each animation. We found that smiling involved movements of the lateral orbital, circumoral, and chin regions; grimacing involved the inner orbital, lateral orbital, lateral nasal, and upper-lip regions; eye closure involved the inner orbital, lateral orbital, and, to a lesser degree, lateral nasal regions; eye opening involved the inner and lateral orbital regions; cheek puffing involved the cheek and lower-lip regions; and the lip purse animation involved the nasolabial, cheek, commissure, and lip regions. CONCLUSION: This measurement of distortion provided a quantitative estimate of facial movement, and this approach is especially applicable to patients with unilateral problems in which the patient can serve as his or her own control.

Adult↗

PubMed1997

Stability of bimaxillary osteotomy following surgical correction of class II skeletal deformities: a two-centre study.

This study compares the stability following bimaxillary osteotomy for correction of class II skeletal deformities between two groups of patients. One group (15 patients) were treated at Canniesburn Hospital, West of Scotland Regional Plastic and Maxillofacial Unit, UK. The other group (15 patients) were treated at Ann Arbor Michigan University Hospital, USA. All cases were treated by Le Fort I maxillary advancement/impaction and bilateral sagittal split advancement osteotomy. In all cases Le Fort I maxillary osteotomy was more stable than sagittal split advancement osteotomy. The maxilla stayed within 1 mm of its immediate postoperative position. The average mandibular advancement in Canniesburn cases was 6 mm and about 4 mm in Michigan cases. During surgery the condyles were displaced about 2 mm posteriorly in Canniesburn cases, but remain in their anatomic position in Michigan cases. At 6 months following surgery, Canniesburn patients showed a clockwise mandibular relapse. This increased both the mandibular plane angle and ramus angle by 2.7 degrees and 2.9 degrees respectively. The mandible settled posteriorly 1.7 mm and inferiorly 1.5 mm. In Michigan cases the mandible stayed within 1 mm of its immediate postoperative position. The difference in mandibular relapse between the two groups was statistically significant (P < 0.05). The differences in the stability between the two groups are investigated and the theories of mandibular relapse following sagittal split osteotomy are discussed.

Adult↗

PubMed1997

A retrospective comparison of frontal facial dimensions in alveolar-bone-grafted and nongrafted unilateral cleft lip and palate patients.

This retrospective study was undertaken to describe and compare frontal craniofacial dimensions in alveolar-bone-grafted and nongrafted complete unilateral cleft lip and palate (CUCLP) patients and in noncleft subjects with normal occlusions and good facial balance. Clinical data were obtained from the files of the Hospital for Sick Children, Toronto. Patients were eligible for inclusion if they had posteroanterior cephalograms (PA) taken at adulthood and no congenital anomalies other than CUCLP. A total of 86 adult Caucasian CULCP patients were studied, including 58 who had not received grafts, 28 who had received secondary alveolar bone grafts, and, for comparison, 60 noncleft Caucasian adults. The PA cephalometric radiographs were traced, digitized, and measured. Analysis of variance (ANOVA) was used to test for among-groups differences in the means of the ratios, proportions, and angular measures. Tukey-Kramer HSD procedure was used to conduct post-hoc pairwise comparisons following significant (p < or = 0.05) F-ratios from ANOVA. Sexual dimorphism was a common finding, with males demonstrating greater facial width. Despite primary surgical repairs, the anterior nasal spine in the nongrafted CUCLP patients was deviated to the noncleft side, and the alar base was depressed on the cleft side. The maxillary incisors close to the cleft site were irregularly inclined, and this irregularity was more severe in the nongrafted CUCLP patients. The long-term effects of secondary alveolar bone grafting on transverse craniofacial growth appears to be minimal and limited to the immediate area of the cleft.

Adolescent↗

PubMed1997

Association of lip posture and the dimensions of the tonsils and sagittal airway with facial morphology.

The specific contribution of enlarged tonsils or adenoids to craniofacial growth remains unknown, and there is no agreement in the literature as to the significance of lip posture. This study assessed the separate associations of lip posture, sagittal airway size, and tonsil size with selected cephalometric measures. Clinical and cephalometric data of 207 children who presented for evaluation of tonsil and/or adenoid problems were evaluated. Multiple linear regression was used to assess the linear relationship between each of the three parameters and the cephalometric dependent variables. Open lip posture, reduced sagittal airway, and large tonsils were each associated statistically with a characteristic but different skeletal configuration. This association was proportional. Specifically, a more open lip posture was associated with a more backwardly rotated face and larger lower facial height. Reduced sagittal airway size was associated with en bloc backward relocation of the maxilla and mandible. Because the sella-nasion dimension shortened proportionally, the SNA and SNB angles were not affected. Larger tonsils were associated with more forward relocation and rotation of the maxilla and mandible and increased SNA and SNB angles. Because each of the three parameters was associated proportionally with a different craniofacial morphology, it is concluded that lip posture, sagittal airway size, and tonsil size represent three different and unrelated phenomena with respect to their effects on craniofacial growth and form.

Adolescent↗

PubMed1997

Multiple linear regression as an analytical tool in cephalometric studies.

When the effect is studied of a factor like 'orthodontic therapy' on linear craniofacial growth, the concomitant consequence of age and gender on size cannot be ignored. The methodologically correct solution is division of the study group into smaller units, each of which is homogeneous with respect to age, gender, and therapy, and to compare these with matched controls. Yet, apart from matched controls being hard to find, this method of subdivision has the serious drawback that smaller groups decrease statistical power. A solution without the need to create sub-groups lies in the application of multiple linear regression analysis. It has been applied to biological data in other studies, but verification of the outcome has not been reported so far. Indeed, testing the mathematical assumptions underlying the regression model created unresolvable obstacles and, therefore, it was decided to perform verification by means of practical examples. Two separate tests for the applicability of the multiple linear regression method, on different data, with differing predictor sets, and with different control samples have been performed.

Adolescent↗

PubMed1996

A comparison of three-dimensional and two-dimensional analyses of facial motion.

The purpose of this study was to compare the amplitude of facial motion obtained using three-dimensional (3-D) and two-dimensional (2-D) methods. The amplitude of motion of fifteen facial landmarks during five maximal animations (smile, lip-purse, grimace, eye closure, and cheek-puff) was quantified in 3-D and 2-D using a video-based system. Results showed that the 3-D amplitudes were significantly larger than the 2-D amplitudes, especially for landmarks on the lower face during the smile animation. In the latter instance, the 2-D amplitudes underestimated the 3-D amplitudes by as much as 43%. The difference between 3-D and 2-D amplitudes was greater for 2-D amplitudes obtained from one camera rather than from multiple cameras. The results suggest that a 2-D analysis may not be adequate to assess facial motion during maximal animations, and that a 3-D analysis may be more appropriate for detecting clinical differences in facial function.

Adult↗

PubMed1996

Reliability of a three-dimensional method for measuring facial animation: a case report.

Reliable methods of quantifying functional impairment of the craniofacial region are sorely lacking. The purpose of this study was to test the reliability of a three-dimensional method for assessing the functional repertoire of the face. Subjects were instructed to perform repeated sequences of five maximal facial animations. Facial motions were captured by three 60-Hz video cameras, and three-dimensional maximum motion amplitudes were calculated. Student's t-test and Pearson product-moment correlation coefficients were used to test for significant differences between repetitions. The results show moderate to excellent reliability of the amplitude of motion for the landmarks over all animations. For each specific animation, certain landmarks demonstrated excellent reliability of motion.

Adult↗

PubMed1996

Use of modern craniofacial techniques for comprehensive reconstruction of the acromegalic face.

The severe acromegalic patient poses a difficult reconstructive dilemma to the craniofacial surgeon. Significant facial deformities can include frontal bossing, prominent supraorbital ridges, malar flatness, maxillary hypoplasia, mandibular prognathism with class III malocclusion, and macrogenia. Reports on the correction of these deformities are rare. Prior publications describe long hospital stays, weeks of intermaxillary fixation, requirement for a tracheostomy, as well as the need for multiple, staged procedures and interdisciplinary teams. In an effort to extend the advances of modern craniofacial techniques to this group of patients, we performed an extensive reconstruction on a 28-year-old acromegalic patient using a one-stage procedure without the use of intermaxillary fixation and without the added morbidity of a tracheostomy. The procedure addressed the skeletal deformities of the upper face, the midface, and the lower face. The operation was performed by a single plastic surgery team and the patient was extubated in 36 hours and discharged in 6 days. We believe that the use of rigid fixation and the judicious application of modern craniofacial principles can allow a complex yet safe one-stage procedure to reconstruct the acromegalic face. Such an approach showed decreased perioperative morbidity and provided an excellent functional and aesthetic result.

Acromegaly↗

PubMed1996

Comparison of facial form in primary alveolar bone-grafted and nongrafted unilateral cleft lip and palate patients: intercenter retrospective study.

The purpose of this study was to describe and compare posttreatment craniofacial morphology in samples of complete unilateral cleft lip and palate (CUCLP) patients treated at two leading clinics: The Children's Memorial Hospital Cleft Palate Clinic, Chicago, Illinois, and the Lancaster Cleft Palate Clinic, Lancaster, Pennsylvania. These centers have well-defined treatment protocols that allow the long-term effects on craniofacial form of the following treatment regimes to be contrasted: (1) Chicago--primary alveolar bone grafting, with definitive lip repair at age 4 to 6 months and hard and soft palate repair at 6 to 12 months; and (2) Lancaster--definitive triangular-flap lip repair at 3 months of age, followed by staged surgeries of the hard and soft palates, both completed by 18 months of age, but without primary alveolar bone grafting. Although the Lancaster center now performs secondary alveolar bone grafting, the majority of the patients studied here were treated before this procedure became part of their protocol. Patients were eligible for inclusion if they had no other congenital anomalies and no previous orthodontic treatment. A sample of 43 (24 male, 19 female) CUCLP patients was obtained from the Chicago Center, each of which was then matched to a nongrafted Lancaster CUCLP patient. The matching criteria were age, sex, and sella-nasion distance (to control, at least in part, for size differences). Lateral cephalometric radiographs of these 86 CUCLP patients were traced, digitized, and analyzed. Additionally, all linear data were adjusted to a standard magnification of 8% because the cephalograms from each center featured different enlargements. The Chicago and Lancaster samples had mean posttreatment ages of 10.32 years (SD = 1.96) and 10.40 years (SD = 2.18), respectively. The grafted Chicago group had faces that were on average less maxillary protrusive compared with the nongrafted Lancaster sample; it appeared, however, that the mandible compensated for the maxillary position by downward and backward rotation. As a result, a similar maxillomandibular relationship was noted in both groups, although, in the Chicago group, the lower anterior facial height increased.

Alveolar Process↗

PubMed1995

Log-linear allometry of fetal craniofacial growth in Down's syndrome.

Trisomy 21 develops as a result of nondisjunction of two homologous chromosomes during either the first or second meiotic division. One of the more important consequences of these genetic alterations is the predictable, although variable disturbance in the architecture of the craniofacial region [1]. Postnatal craniofacial morphology has been extensively studied in Down's syndrome (DS). However, little information is available on human prenatal development of the head and face in such patients. The time at which changes in craniofacial phenotype first emerge in Down's syndrome fetuses and at which physical growth begins to diverge from normal is unknown. To explore these questions, we compared prenatal craniofacial growth in 50 Down's syndrome fetuses with that of 555 fetuses judged to be "typical for body weight and age" using the method of log-linear allometry [2].

Cephalometry↗

PubMed1995

Log-linear allometry of normal fetal craniofacial growth.

Normative data on human craniofacial growth during the fetal period and important to provide a broader perspective on normal morphogenesis as well as to serve as reference for analyzing craniofacial syndromes in which growth has gone awry. Over a 19-year period, the Teratology Unit at the University of Michigan Medical Center has collected data on 2,568 legally donated fetuses that have undergone necropsy examination at various gestational ages. From previous analyses, 609 of the total fetal population (25%) were designated as typical for age or body weight on the basis of normal morphology, absence of maceration, and general growth symmetry. Of the 609 fetuses reviewed, 54 were excluded secondary to incomplete data. The remaining 555 constitute the basis of this study. Seven craniofacial measurements were recorded, including head circumference (HC), brain weight, inner canthal and outer canthal distances, and distances from nasion to menton, outer canthus to tragus and auditory meatus to vertex. Statistical analysis was carried out using the single-factor allometric model of Sewall Wright. Size was estimated as the first unstandardized principal component of the logarithms of lengths and of cube roots of weights, and then allometry was expressed in the regressions of each log variable on size. Significant allometry was found as were significant differences in errors about the allometric relation, but no evidence for more than a single factor or of "nonlinearity" in the regression curves was noted. Although there were differences of specific allometric coefficients between the various measurements (i.e., the slope of the curve for IC was significantly smaller than the slope of the curve generated for HC), these specific growth rates remain in relatively strict proportion to one another from early in gestation (body weight, 54.2 gm) to later in gestation (body weight, 1,000 gm).

Cephalometry↗

PubMed1995

Cumulative operative procedures in patients aged 14 years and older with unilateral or bilateral cleft lip and palate.

Sixty-seven consecutive patients over the age of 14 with either unilateral (n = 38) cleft lip and palate or bilateral (n = 29) cleft lip and palate seen over a 15-month period at the University of Michigan Craniofacial Program were reviewed to determine the total number of surgical procedures performed over the course of treatment. The demographics of the two groups differed: There were 25 males and 13 females who were a mean age of 17 years and 9 months with unilateral cleft lip and palate and 23 males and 6 females who were a mean age of 18 years and 5 months with bilateral cleft lip and palate. Lip and palate repairs were carried out on all patients. Lip adhesions were performed in 29 and 62 percent; pharyngoplasties (either pharyngeal flap or modified Ortichochea) in 39 and 38 percent; alveolar bone grafts in 82 and 79 percent; Abbé flaps in 0 and 10 percent; and orthognathic surgery was done in 10.5 and 13.8 percent and recommended and/or done in 26 and 24 percent of patients with unilateral cleft lip and palate and bilateral cleft lip and palate, respectively. Lip revisions averaged 1.13 and 2.17 per patient and secondary nasal surgeries averaged 1.13 and 1.18 per patient in the unilateral cleft lip and palate and bilateral cleft lip and palate, respectively. All totaled, the average number of operations was 6.12 per patient (range 3 to 12) in the unilateral cleft lip and palate and 8.04 per patient (range 5 to 15) in the bilateral cleft lip and palate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗