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Biomedical subjects

N H El-Mangoury

Publications and source records attributed to N H El-Mangoury.

12 recordsLinked to original sources
PubMed1996

Faciometrics: a new syntax for facial feature analysis.

A little neglect appears to exist in current cephalometric soft tissue analysis. Specifically, some areas of the facial integument are not accessible to cephalometric analysis. Further, no method of frontal cephalometric soft tissue analysis has been described. Faciometrics, a new cephalometric, nonradiographic system for facial feature analysis, may carry professional diagnostic capacity to another dimension by providing an evaluation for previously inaccessible facial areas and by supplying a beginning for frontal cephalometric soft tissue analysis. The reliability and the validity of the proposed system were tested on a random sample of 20 subjects. The system was found to be reliable and valid. A method for rapid checking of facial symmetry is also described, and some equations for facial proportions are presented as guidelines for good facial esthetics. The faciometric system is proposed as a complement to, rather than a replacement for, available soft tissue cephalometric analysis.

Algorithms↗
PubMed1991

Iatrogenic pulpal reactions to orthodontic extrusion.

A careful review of the literature reveals an absence of studies about the reactions of dental pulp to orthodontic extrusion. The purpose of the present research investigation is to study the pulpal reactions and the sequence of histologic events in human dental pulp after orthodontic extrusion. The sample consisted of 36 intact maxillary first premolars of young adult orthodontic subjects. The mean age of the subjects was 18 years. Eighteen maxillary first premolars were extruded, under controlled conditions with the aid of fixed edgewise orthodontic appliances, for either 1, 2, or 4 weeks. The contralateral maxillary first premolars were not extruded and were used as controls. Immediately after removal of the appliances, all the maxillary first premolars were extracted. The pulps were histologically examined in a double-blind experiment. The results obtained from this study indicate that certain characteristic pulpal reactions arise from orthodontic extrusion. These reactions involve circulatory disturbances with congested and dilated blood vessels, odontoblastic degeneration, vacuolization and edema of the pulp tissues, and (by the fourth week) manifestation of fibrotic changes. It is speculated that the vacuolization of the pulp tissues (which occurred after the application of extrusive orthodontic forces in young adult subjects) resulted from a prolapse of the pulp, made possible by the relatively wide apical foramina. However, the odontoblastic degeneration is most probably the result of a compromised blood supply. The authors believe that this study constitutes a building block for establishing a more complete biologic foundation for orthodontic tooth movement. Further studies are suggested to reach more definitive conclusions.

Adolescent↗
PubMed1990

Epidemiologic panorama of dental occlusion.

The purpose of this study was to explore the possible significant sex difference in occlusion, provide information about the occlusal variation among Egyptians, and present an epidemiologic panorama of dental occlusion among different ethnic world populations. The hypothesis was that the occlusal variation is not independent of sex. A sample of 501 female and male adult subjects was studied. Normal occlusion, Angle's classification of malocclusion, and the Dewey-Anderson modifications for typifications were recorded. Chi-square tests were used. The results obtained from this study indicate that a significant sex difference in occlusion exists for normal occlusion, Angle Class I, and Angle Class III. Further, considering an anterior crossbite as the sole indicator of an Angle Class III malocclusion is erroneous; an anterior crossbite may exist in other classes, and Angle Class III type 1 (edge-to-edge) is more prevalent than either Class III type 2 (normal anterior overbite) or type 3 (anterior crossbite). Although numerically different, occlusal variation follows a universal general distributional pattern for most world populations. Some speculations are presented for clinical implications and for research suggestions.

Adolescent↗
PubMed1987

Landmark identification in computerized posteroanterior cephalometrics.

A lack of cognition regarding the reliability of landmark identification in posteroanterior cephalometrics keeps the extracted data questionable. The present study was designed to analyze this problem for the purpose of providing certain insights. An interactive computer graphic package was developed. This package was called EA-PAX (Error Analysis of Postero-Anterior cephalometric X-ray films). A random sample of 40 clear posteroanterior cephalometric head plates was studied. The reliability of landmark identification was established. The skeletal landmarks seemed more reliable than the dental landmarks. The variation in the direction and magnitude of the error was determined for each landmark. Most landmarks had their own characteristic noncircular envelope of error. It is not the philosophy of the present authors to tell the orthodontists what to use. Rather, the philosophy is to be aware of the amount and direction of variation for a particular landmark. Taking this into consideration will enable the orthodontists to look on their cephalometric numbers with a mental awareness of the possible variations. Several clinical and research studies are suggested in the article.

Adolescent↗
PubMed1987

Mandibular anterior crowding and periodontal disease.

A short-term longitudinal study of the role of mandibular anterior crowding in inflammatory periodontal diseases. Crowded dentitions show more periodontal involvement, and the improvement after scaling disappears more rapidly.

Adult↗
PubMed1986

Influence of excision of the facial and inferior dental nerves on mandibular growth and development.

The purpose of this study was to evaluate the role of the facial and inferior dental nerves on mandibular growth and development. A sample of 10 mongrel dogs was randomly divided into two equal groups. Avulsion of the right inferior dental nerve was carried out on the first group. Surgical cutting of the extracranial portion of the right facial nerve was performed on the second group. Sham operations were made for the left sides of the mandibles of all animals. The animals were killed 3 months later and their mandibles visually and radiographically examined. Measurements were recorded in a double-blind experimental design. The data were statistically analyzed. The results obtained from this study indicate that surgical cutting of the extracranial portion of the facial nerve resulted in unilateral facial paralysis of the muscles of expression. However, after the animals were killed, no significant statistical differences were found between the nerve-devoid and sham sides of the mandible for both the facial nerve group and the inferior dental nerve group. Nevertheless, for the inferior dental nerve group, visual and radiographic examinations revealed various morphologic differences at the angular process regions of the mandibles. The impact of neural deprivation on mandibular growth and development was thus determined.

Animals↗
PubMed1982

Deficient nasal bone growth in the X-linked hypophosphataemic (HYP) mouse and its implication in craniofacial growth.

Mice bearing the mutant Hyp gene are characterized by craniofacial abnormalities secondary to their metabolic bone disease. X-ray cephalograms were taken of 40 normal and 29 Hyp mice at 1, 2, 3 and 4 weeks of age in one group and at weeks 6, 9 and 12 in a second. Hyp mice exhibited shorter skulls, shorter mandibles antero-posteriorly and a compressed upper face height. Both the fronto-nasal and the premaxillo-maxillary sutures in the Hyp mice were deformed and failed to close by 12 weeks of age. The deficient linear growth of the nasal bone was the most important measured variable contributing to the overall difference in the skull morphology between Hyp and normal mice. Thus this animal model is promising for elucidating the regulatory mechanisms affecting craniofacial growth.

Animals↗
PubMed1981

Orthodontic cooperation.

The purpose of the present article was to provide a reasonably coherent picture of the concept as well as the prediction of the misunderstood phenomenon of orthodontic cooperation. A sample of seventy orthodontic patients was studied. A double-blind quasi-experimental research design was performed. Psychological instruments were used in order to measure achievement, affiliation, and attribution motivation. The following dependent variables were recorded: headgear wear, elastic wear, appliance maintenance, nonbroken appointments, oral hygiene, and plaque index. The raw data were analyzed by three different techniques. The results obtained from this study indicate that orthodontic cooperation is predictable through psychological testing. Specifically, high-need achievers cooperate better orthodontically than low-need affiliators, and internals cooperate better orthodontically than externals. Further, it was found that orthodontic cooperation does not involve a simple single general dimension of cooperation. Rather, orthodontic cooperation is composed of a more complex structure of two orthogonal constructs: Specific Orthodontics Construct of Cooperation (SOCC) and Perio-Orthodontic Construct of Cooperation (POCC). Because SOCC and POCC are orthogonal, a patient who is a good brusher does not have to be a good headgear wearer, and vice versa. The relative contribution of motivational psychology on each of the variables constituting orthodontic cooperation was determined. The implications for clinical applications were presented.

Achievement↗
PubMed1979

Orthodontic relapse in subjects with varying degrees of anteroposterior and vertical dysplasia.

Fifty seemingly well-treated orthodontic cases were studied by means of pretreatment, posttreatment, and postretention dental casts, lateral cephalograms, and other orthodontic records. The sample was restricted to cases exhibiting anteroposterior and/or vertical dysplasia as revealed by pretreatment dental casts. The sample was divided into a stable group and a relapse group. Each group contained twenty-five cases. A double-blind design was used. The raw data were analyzed by the stepwise discriminant analysis and by the multivariate analysis of variance. On the basis of the results obtained from this study, the following conclusions can be drawn: 1. In seemingly well-treated orthodontic cases, relapse or stability can neither be predicted nor judged from one set of records alone. 2. Relapse or stability of an orthodontic case can be predicted by comparing the posttreatment variables with the pretreatment variables. 3. Relapse or stability of an orthodontic case can be judged by comparing the postretention variables to the posttreatment variables. 4. The PP-GoGn angle and the mandibular intercanine width are the two most important variables associated with orthodontic relapse. 5. Changing the PP-GoGn angle, either by treatment or by growth, was associated with relapse. In other words, changes in the PP-GoGn angle tended to be unstable. This suggests that decreasing the PP-GoGn angle should be avoided. 6. In both the stable and the relapse groups, the mandibular intercanine width decreased postretention. This decrease was associated more with the relapse group than with the stable group. 7. The mandibular intercanine width tended to relapse toward its original pretreatment value. This suggests that, at the end of active treatment, the mandibular intercanine width should be maintained as originally presented. 8. There was no significant interaction between orthodontic relapse (or stability) and Angle Class I and II cases. 9. There was no significant interaction between relapse (or stability), of an orthodontic case, and the sex of the patient. 10. There was no significant interaction between orthodontic relapse (or stability) and whether or not extraction was included as a part of the mechanotherapy. Thus, the pretreatment deep overbite is not necessarily a contraindication to extraction.

Analysis of Variance↗