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This is a case report of a patient in mixed dentition with 2nd class malocclusion, and early loss of deciduous cuspid tooth. The harmful effects on the growth and development of normal occlusion are emphasized.
The oral breathing can change the functional connections during the development of the facial bones of the children. All this causes an abnormal growth of the facial bones and of the dental structures. This work developed a new discipline to remove this problem.
1. The dental pulp and periodontium have developmental connections. 2. Many of their functions intersect and are common to both tissues. 3. Their highly developed defence systems enable either to survive when the other has been destroyed.
A case of hemifacial microsomia is presented. The mandible, temporomandibular joint, zygomatic arch and temporal region were reconstructed by means of skull bone grafts when the patient was 6 years old, a relatively early age. This corrective surgery has effectively restored normal mandibular function, and in so doing may encourage more acceptable development of the affected facial structures.
The main problem of facial development in cleft palate consists of deficient anterior growth of the upper jaw. Roentgencephalometric data showed that the sagittal jaw relations deteriorated gradually from palate surgery up to adulthood. In spite of this adverse trend of growth, orthodontic therapy succeeded in improving the occlusion of incisors during prepubertal period. However during the pubertal growth spurt occurred an impairment of occlusion which was caused by the depletion of compensatory dentoalveolar mechanisms of the jaws due to the previous orthodontic treatment. An effective compensation of the gradual impairment of sagittal jaw relations can be attained with fixed appliances. These observations showed that the main problems of facial growth in clefts developed only after palate surgery and in particular during puberty. For favourable sagittal jaw relations and the configuration of the facial profile is of paramount importance the restoration of a positive overjet which exerts marked effects on the position of the mandible. On the other hand the configuration of the facial profile and the results of orthodontic therapy are affected by the rotation of the lower jaw and the amount of posterior displacement of the TM joint, which represent inborn growth patterns of the skull. The most favourable developmental situation represents the posterior displacement of the TM joint associated with neutral type of rotation. Therefore, it is of importance to predict the development of these characteristics.
Multimedia teaching tools in Medicine are still very rare. Their presentation on a CD-ROM format is part of the emerging technologies in Medical Informatics. The Multimedia material presented here on Dental and Skeletal Development is mostly a Database and a Tutorial. The Database, which contains more than 2000 hand/wrist radiographs, is mostly intended for Pediatricians, Endocrinologists, Forensic Dentists and Physicians, as well as for Orthodontists and Pedodontists. The material is the result of 20-year of Longitudinal Growth study of children in Montreal. In this Multimedia CD-ROM, the research results are used for Medical teaching purposes.
Forty-one patients with clinically diagnosed Class II, Division I malocclusions with midface prognathism were treated with Kloehn-type cervical headgear. All cases included both longitudinal series of lateral cephalometric radiographs and hand-wrist films taken before, during, and after treatment. Skeletal and dental changes were related to specific maturational periods and compared with their related chronologic age to evaluate optimum timing for maximum treatment response. As determined by this study, timing of cervical headgear treatment on the basis of skeletal maturation is a more statistically significant means of obtaining the maximum desirable orthopedic effect than chronologic age. More favorable results were demonstrated during maturational periods that were associated with a higher degree of incremental growth velocity.
Numerous experimental and clinical studies have shown an association between masticatory muscle function and craniofacial growth. The present series of studies focuses on the influence of masticatory muscle function on some basic mechanisms in craniofacial growth as well as on the effect of the functional capacity of the masseter muscle on the width of the maxillary dental arch in human subjects. The animal experimental model used to study the influence of masticatory muscle function was a non-invasive one that produced a decreased functional demand of the masticatory system in growing rats by feeding them a soft diet. The influence of reduced masticatory muscle function on the transversal dimensions of the premaxilla, maxilla (including the dental arch) and the calvaria was studied on dry skulls using a high precision non-contact measuring system. Moreover, a methodological study was carried out to study the influence of one preparation method on the dimensions of dry rat skulls, using axial contact radiographs. The effect of different functional demands on sutural dimensions and sutural bone apposition was studied on frontal undecalcified sections of the rat snout using automatic image analysis. For the quantification of sutural dimensions contact microradiographs were used, while for sutural bone apposition the bone level at certain time intervals was marked with calcein. In the clinical part of this thesis the relationship between maxillary dental arch width and masseter muscle thickness in humans was studied using ultrasonography. Masticatory muscle function was found to influence the transverse growth of the skull at areas under direct muscle influence as well as the dental arch width in regions with molars under eruption. The methodological study indicated that direct comparisons between measurements on fresh specimens and those on dry rat skulls are not permissible, since the dimensions of the dry rat skull are smaller than those of the original fresh specimens. The dimensions and morphology of the facial sutures as well as the sutural bone apposition were negatively affected by reduced masticatory function. The experimental findings of the present study might indicate some of the underlying mechanisms of the clinical findings, where subjects with thicker masseter muscles were found to have a broader maxillary dental arch.
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Moderate differences in the hardness of diet are related to significant differences in maxillary width and other measures of facial size. Probably even more important is a relationship to the coordination of growth of different parts of the dentofacial complex. Muscular stimulation mediated through occlusal function seems to play a significant role in the coordinated development of facial structures.
Cephalometric radiographs from a group of adults who had suffered nasal trauma during childhood were compared with random controls. Significant differences were found between mean measurements for the two groups, which indicated aberrations in the growth of the midface in patients from the study group. The vertical component of facial development was also altered, being increased in the study group.
Retinoic acid causes a range of embryonic defects, including craniofacial abnormalities, in both birds and mammals and is believed to have a number of roles in normal development. We have previously shown that the distribution of retinoic acid receptor-beta (RAR-beta) transcripts is spatially restricted within the neural-crest-derived upper beak primordia of the chick embryo. We have now used in situ hybridisation to trace the distribution of RAR-beta transcripts during the migration of cranial neural crest cells and during formation of these primordia. RAR-beta transcripts were present in a subset of migrating neural-crest-derived cells in the head of the stage 10 embryo. These cells were situated in pathways followed by cells that migrate from the neural crest overlying the posterior prosencephalic/anterior mesencephalic region of the developing brain. Cells containing RAR-beta transcripts accumulated around the developing eyes and in the regions of the ventral head from which the upper beak primordia later develop. We mapped the distribution of RAR-beta transcripts as the facial primordia were forming, with particular reference to the development of the maxillary primordia. We found that these form in a region of the ventral head that includes the boundary between regions of high and low levels of RAR-beta transcripts. The boundary between these two groups of cells persisted as the maxillary primordia developed.(ABSTRACT TRUNCATED AT 250 WORDS)
The influence of the masticatory muscle function on craniofacial growth has been recorded in a series of animal experimental and clinical studies. The common characteristic of these investigations is that the elevator muscles of the mandible influence the transversal and the vertical dimensions of the face. The increased loading of the jaws due to masticatory muscle hyperfunction may lead to increased sutural growth and bone apposition, resulting in turn in an increased transversal growth of the maxilla and broader bone bases for the dental arches. Furthermore, an increase in the function of the masticatory muscles is associated with anterior growth rotation pattern of the mandible and with well-developed angular, coronoid, and condylar processes.
The term sumangle (SA) according to Björk has been attributed in the literature to Jarabak. The term was not used by Björk in his original works. Because of the demonstrated relations the sumangle can be deducted from the simplified calculation SA = X + 360 degrees, whereby X is the angle between the reference lines NS-ML. Beside from this fact also the high unreliability of defining the necessary reference points makes the sumangle a questionable measurement of vertical skeletal development. Therefore other trigonometric parameters as for instance the Y-axis are preferable.