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Biomedical subjects

P M Sinclair

Publications and source records attributed to P M Sinclair.

At least 19 recordsLinked to original sources
PubMed2001

A comparative study of Caucasian and Japanese mandibular clinical arch forms.

The purpose of this study was to clarify morphological differences between Caucasian and Japanese mandibular clinical arch forms in Class I, II, and III malocclusions. The study included 60 Class I, 50 Class II, and 50 Class III cases from each ethnic group. The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth based on mandibular tooth thickness data. Four linear and 2 proportional measurements were taken. The dental arches were classified into square, ovoid, and tapered forms to determine and compare the frequency distributions between the 2 ethnic groups. The Caucasian population had a statistically significant decreased arch width and increased arch depth compared with the Japanese population. When the subjects were regrouped by arch form, no statistically significant difference in arch dimension was observed between the 2 ethnic groups in any of the arch form samples. Our results suggest that there is no single arch form specific to any of the Angle classifications or ethnic groups. It appears to be the frequency of a particular arch form that varies among Angle classifications or ethnic groups.

Adolescent↗
PubMed2001

Predicting and preventing root resorption: Part I. Diagnostic factors.

The purpose of this study was to determine whether it would be possible to identify pretreatment factors that will allow the clinician to predict the incidence, location, and severity of root resorption before the commencement of orthodontic treatment. The records of 868 patients who were treated with full, fixed edgewise appliances were obtained from 6 private offices; full-mouth periapical radiographs were used to accurately assess apical root resorption from first molar to first molar in both arches. The results showed that resorption occurs primarily in the maxillary anterior teeth, averaging over 1.4 mm. The worst resorption was seen in maxillary lateral incisors and in teeth with abnormal root shape (pipette, pointed, or dilacerated). Adult patients experienced more resorption than children did in the mandibular anterior segment only. Asian patients were found to experience significantly less root resorption than white or Hispanic patients. Increased overjet, but not overbite, was significantly associated with greater root resorption. There was no difference in either the incidence or severity of root resorption between male and female patients.

Adolescent↗
PubMed2001

Predicting and preventing root resorption: Part II. Treatment factors.

The main objective of this study was to determine which treatment factors are most clearly identified with external apical root resorption that is detectable on periapical radiographs at the end of orthodontic treatment. The records of 868 patients who completed fixed, edgewise treatment from experienced clinicians in private practice were examined. The horizontal and vertical displacement of the root apex of the maxillary central incisor was measured on cephalometric radiographs. Patients who underwent first premolar extraction therapy had more resorption than those patients who had no extractions or had only maxillary first premolars removed. Duration of treatment and the horizontal (but not vertical) displacement of the incisor apices were significantly associated with root resorption. No differences were found for slot size, archwire type, use of elastics, and types of expansion. However, there was considerable variation among the 6 offices that were surveyed; 1 office averaged nearly a full millimeter more of resorption per anterior tooth than the office with the least amount of root resorption. We conclude that the clinician should exercise caution with those patients in whom extraction therapy is planned for overjet correction that requires above average treatment time. Finally, each clinician should be aware that the root resorption seen in one practice may be different from the root resorption found in another practice.

Adolescent↗
PubMed2001

Preparing to practice and manage: A program for educating orthodontic residents in practice management.

The purpose of this article is to describe how the integration of practice management principles into orthodontic graduate programs can help young practitioners avoid many of the mistakes commonly made in developing an orthodontic practice and to provide guidelines and resources for starting off in the right direction. This article also describes how practice management education was integrated as one of the 4 principal components of contemporary orthodontic education at a California university. Specific goals, concepts, and components of a comprehensive practice management program are outlined. A structured practice management curriculum can provide opportunities for residents and alumni to learn some of the latest developments and techniques in orthodontic practice management.

Curriculum↗
PubMed1999

Accuracy of video imaging for predicting the soft tissue profile after mandibular set-back surgery.

The purpose of this study was to compare the accuracy of two video-imaging programs for predicting the soft tissue outcomes of mandibular set-back surgery for patients with skeletal class III malocclusion. The sample consisted of 30 previously treated, nongrowing, white patients who had undergone isolated mandibular set-back surgery. An objective comparison was made of each program's cephalometric prediction using a customized analysis, as well as a subjective comparison of the predicted images as evaluated by a panel of six raters. The results showed that both programs produced similar cephalometric and video image predictions. The cephalometric visual treatment objective predictions were found to be most accurate in the horizontal plane; approximately 30% of cases showed errors greater than 2.0 mm, whereas in the vertical plane, the error rate was greater (50%). The resulting video image predictions were judged by the panel as being in the "fair" category. A particular problem was noted when significant vertical compression of the soft tissue images was required. Video imaging was suitable for patient education but not accurate enough for detailed diagnosis and treatment planning.

Adult↗
PubMed1998

Cephalometric effects of face mask/expansion therapy in Class III children: a comparison of three age groups.

The purpose of this investigation was to determine the skeletal, dental, and soft tissue effects of face mask/expansion therapy and to examine the effect of age on treatment response. Pretreatment and posttreatment cephalometric radiographs from 63 subjects (4 to 13 years) who had a Class III malocclusion were analyzed. Serial cephalometric tracings of 32 subjects with Class I occlusion made at 4, 6, 8, 10, 12, and 14 years were used as controls. Landmarks were digitized on each tracing and treatment effects were measured by using cranial base and maxillary superimposition techniques. Annual rate differences were compared with t tests for the combined treated group (N = 63) and between stratified treated groups (4 to 7 years N = 15, 7 to 10 years N = 32, 10 to 14 years N = 16). The treated group (N = 63) demonstrated significant (p < 0.001) hard and soft tissue changes that resulted from treatment. Skeletal change was primarily a result of anterior and vertical movement of the maxillae. Mandibular position was directed in a downward and backward vector. Orthodontic changes contributed to the correction, and soft tissue effects resulted in a more convex profile. Minimal significant differences were observed between age groups when comparing angular and linear measurements alone. However, when analyzing the algebraic sum of treatment effects (Johnston analysis), significantly (p < 0.01) greater differences were observed in apical base change (ABCH) and total molar correction (6/6) in the younger age groups. This study demonstrates that face mask/expansion therapy produces dentofacial changes that combine to improve the Class III malocclusion. Although early treatment may be most effective, face mask therapy can provide a viable option for older children as well.

Adolescent↗
PubMed1998

Multivariate prediction of skeletal Class II growth.

Prediction of craniofacial growth is one of the keys to successful orthodontic treatment and stability. Despite numerous attempts at growth forecasting, our ability to accurately predict growth is limited. The present study outlines a possible new approach to prediction of craniofacial growth that differs from any previous attempt because of both the methods used and type of patients studied. The purpose of this study is to create and test prediction equations for forecasting favorable or unfavorable patterns of growth in skeletal Class II preadolescents. The subjects for this study include 19 females and 12 males from the Bolton growth center in Cleveland, Ohio. The patients were all untreated orthodontically, had lateral cephalometric headfilms taken biannually from the ages of 6 through 18 and had a Class II skeletal relationship at age 8. Twenty-six skeletal and dental landmarks were identified and digitized, and 48 linear, angular, and proportional measurements were calculated. The subjects were divided into two groups based on anterior-posterior changes in the relationship between the maxilla and mandible. Eleven patients were in the favorable growth group, with an average improvement of 4.13 degrees in the ANB angle; 20 patients were in the unfavorable growth group with an average increase of 0.16 degrees in the ANB angle. The following prediction formula was created with Bayes theorem and assuming a multivariate Gaussian distribution: P(Good¿Fn) = ke (-(0.5)) ¿Fn - mu(ng)¿sigma(g)(-1)¿Fn - mu(ng)¿T. The equation's sensitivity and specificity was calculated from serial cephalometric data from ages 6, 8, 10, and 12. The results obtained with this equation indicate 82.2% sensitivity, 95% specificity with a overall positive predictive value of 91%. This corresponds to 17.8% of patients being incorrectly identified as Poor Growers and only 5% of our patients were incorrectly identified as Good Growers. We conclude that this prediction formula improves the ability to predict favorable or unfavorable patterns of growth in this sample of skeletal Class II preadolescents.

Adolescent↗
PubMed1998

Automatic computerized radiographic identification of cephalometric landmarks.

Computerized cephalometric analysis currently requires manual identification of landmark locations. This process is time-consuming and limited in accuracy. The purpose of this study was to develop and test a novel method for automatic computer identification of cephalometric landmarks. Spatial spectroscopy (SS) is a computerized method that identifies image structure on the basis of a convolution of the image with a set of filters followed by a decision method using statistical pattern recognition techniques. By this method, characteristic features are used to recognize anatomic structures. This study compared manual identification on a computer monitor and the SS automatic method for landmark identification on minimum resolution images (0.16 cm2 per pixel). Minimum resolution (defined as the lowest resolution at which a cephalometric structure could be identified) was used to reduce computational time and memory requirements during this development stage of the SS method. Fifteen landmarks were selected on a set of 14 test images. The results showed no statistical difference (p > 0.05) in mean landmark identification errors between manual identification on the computer display and automatic identification using SS. We conclude that SS shows potential for the automatic detection of landmarks, which is an important step in the development of a completely automatic cephalometric analysis.

Adolescent↗
PubMed1998

The role of computerized video imaging in predicting adult extraction treatment outcomes.

The purpose of this study was to evaluate the accuracy of computerized video imaging in predicting the soft tissue outcome of extracting four premolars in adults. The pretreatment and posttreatment cephalometric and facial photographic records of 31 previously treated, nongrowing patients were digitized and computer-generated cephalometric VTOs and video images were compared with the known outcomes. The results showed that both the VTOs and video images were accurate enough to be used for patient education and communication, as well as for diagnosis and treatment planning. While lay people found that the predicted video images adequately resembled the actual outcomes, orthodontists were more critical, particularly of the lower lip area where variable soft tissue responses to treatment were noted.

Adolescent↗
PubMed1997

The long-term stability of LeFort I maxillary downgrafts with rigid fixation to correct vertical maxillary deficiency.

This study evaluated the long-term stability of LeFort I maxillary downgrafts with rigid fixation in 28 patients with vertical maxillary deficiency. Preorthodontic, presurgical, immediate postsurgical, and an average of 16 months postsurgical cephalometric radiographs were evaluated. The results indicated that overall vertical maxillary stability after downgraft was good with 80% of the cases showing superior relapse of 2 mm or less. The mean amount of postoperative relapse represented 28% of the surgical downgraft. No correlation was found between the amount of the maxillary downgraft and the subsequent postsurgical vertical stability of the maxilla. No difference was found in the vertical stability of the maxilla comparing one-jaw and two-jaw procedures. It was also found that there was no difference in the vertical stability of the maxilla between single-segment and multiple-segment maxillary procedures, and also when comparing standard and high LeFort I osteotomy techniques. In addition, occlusal plane rotation of surgery, as well as the type of presurgical orthodontic movement, were both found to have no influence on postoperative stability of the maxilla.

Adolescent↗
PubMed1997

Predicting soft tissue changes in mandibular advancement surgery: a comparison of two video imaging systems.

The purpose of this study was to evaluate the accuracy of two video imaging systems, Prescription Portrait and Orthognathic Treatment Planner, in predicting the soft tissue profiles of 39 patients who underwent mandibular advancement surgery. Presurgical cephalograms and profile photographs were entered into a computer. Computerized cephalometric line and video image predictions were generated and compared with the actual postsurgical results. The results indicate that both programs were equally accurate clinically in their line drawing and video image predictions. In the line drawings, clinically acceptable accuracy was shown in approximately 80% of the upper lip and chin predictions and in less than 50% of the lower lip predictions. The video images produced by both programs received fair to good ratings from a panel of professional and lay judges. Orthodontists and surgeons rated all aspects of the images similarly, while lay people were most critical of the chin and submental areas and least critical in their overall evaluation.

Analysis of Variance↗
PubMed1997

Predicting soft tissue changes in maxillary impaction surgery: a comparison of two video imaging systems.

The purpose of this retrospective study was to investigate the accuracy of two video imaging systems, Orthognathic Treatment Planner (OTP) and Prescription Portrait (Portrait), in predicting soft tissue profile changes after maxillary impaction surgery. Computer-generated line drawing predictions were compared with actual postsurgical profiles. Neither program was very accurate with vertical measures and lower lip contour. Portrait was more accurate at pronasale, inferior labial sulcus, and pogonion in the y-axis direction (P < 0.05). Video image predictions produced from the presurgical photographs were rated by orthodontists, surgeons, and lay people, who compared the predictions with the actual postsurgical photographs using a visual analog scale. Portrait's prediction images were scored higher than OTP's for five of eight areas. Orthodontists were most critical of the lips and the overall appearance. Lay people were most critical of the chin and submental areas.

Adult↗
PubMed1997

The accuracy of video imaging for mixed dentition and adolescent treatment.

The purpose of this study was to evaluate the accuracy of computerized video imaging in predicting the soft tissue outcome of growth modification treatment for skeletal Class II malocclusions. Pretreatment and posttreatment cephalometric and facial photographic records of 22 mixed dentition (8 to 10 years old) and 20 adolescent (12 to 14 years old) patients were digitized, and the known outcomes were compared with computer-generated VTOs and video images. The predicted video images were found to be reasonably accurate for the mixed dentition group, but unacceptable for the adolescent group. When graded by a panel of judges, orthodontists were far more critical of the findings than their lay counterparts. These results emphasize the potential of video imaging as a communication medium, rather than as a diagnostic tool for growing patients.

Adolescent↗
PubMed1997

Effects of static magnetic and pulsed electromagnetic fields on bone healing.

The purpose of the present study was to evaluate the healing pattern of an experimentally induced osteotomy in Hartley guinea pigs in the presence of static magnetic and pulsed electromagnetic fields. The sample consisted of 30 Hartley guinea pigs 2 weeks of age divided into 3 groups: pulsed electromagnetic, static magnetic, and control. An osteotomy was performed in the mandibular postgonial area in all groups under general anesthesia. During the experimental period of 9 days, the animals were kept in experiment cages 8 hours per day, the first two groups being in the presence of pulsed electromagnetic and static magnetic field, respectively. Based on histologic results, both static and pulsed electromagnetic fields seemed to accelerate the rate of bone repair when compared to the control group. The osteotomy sites in the control animals consisted of connective tissue, while new bone had filled the osteotomy areas in both magnetic field groups.

Animals↗
PubMed1995

The effects of samarium-cobalt magnets and pulsed electromagnetic fields on tooth movement.

The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the "lag" phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors.

Animals↗
PubMed1995

The accuracy of video imaging in orthognathic surgery.

Video imaging is an important emerging technology in planning orthognathic surgery and educating patients about the esthetic effects of treatment. The presurgical cephalograms of 56 patients, 41 with mandibular advancement alone and 15 with mandibular advancement plus genioplasty, were digitized, and the computer-generated soft tissue "line drawing" predictions were compared with the actual posttreatment cephalograms. Video images of the patients' presurgical lateral view were obtained, and two experienced clinicians compared the computer generated video image predictions with the actual posttreatment profile. Video images judged very good or excellent were considered acceptable for treatment planning; 60% to 83% met this criterion, depending on the profile area viewed. The percentage of acceptable images in the lower lip, labiomental fold, and chin area decreased with the addition of a genioplasty. The predicted and actual posttreatment soft tissue line drawings were quite similar for all areas except for the lower lip region, where statistically significant differences were noted, with the predicted lower lip more retrusive and thinner than the actual contours. For the lower lip and chin, a 2 mm or more discrepancy was observed in 20% of the patients. In all cases, the actual image was judged more esthetic than the predicted image, allaying fears of unrealistically optimistic computer generated predictions.

Adult↗