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Dentofacial changes produced by a modified Milwaukee brace in Macaca mulatta: A roentgenographic and histologic study (M.S.D. thesis)
418
Reviews and abstracts
Am
J. Orthodontics Ajwill969
occurred. The results of the study bear out the findings reported by other authors concerning the effects of such injuries on the permanent teeth. Exarticulation of a deciduous tooth almost always resulted in damage to the corresponding permanent tooth. An intruded tooth usually re-erupted within 6 months, and the pulps of rc-erupted deciduous teeth were often oblitcratcd ; many such teeth interfered with the eruption of their successors and had to bc removed when normal resorption failed to occur. Damage to the permanent teeth after intrusion of the deciduous incisors was found in onIy one sixth to one fifth of the cases. It is evident from the results of this study that luxation in some cases promoted resorption of the deciduous tooth and, hence, premature shedding, but in most cases the teeth were either unaffected or obliterated. Deciduous teeth that had loosened either remained unaffected or the pulps were obliterated with the same frequency, and only a small number mere damaged so much that they had to bc extracted. Loosening of the deciduous tooth rarely had any effect on the permanent successor, and in the few cases in which it did the injury was not serious. Dentofacial William J. Am.
Development
in Children
With
Vitamin
D-Resistant
Rickets
E. Tracy and Robert A. Campbell Dent.
A. 76: 10.26-1091,
May,
1968
l?acial growth, eruption and calcification of the teeth, physical growth, and skeletal maturation were studied in six girls and three boys with vitamin Dresistant rickets. The children selected ranged in stature from below the third percentile to the tenth percentile for their chronologic age. Results show that when the children were considered as a group two maxillary measurements showed retardation, and all other maxillary and mandibular dimensions were normal. Among the individual children with retarded facial growth, the maxillary dimensions were retarded more frequently than the mandibular, and height and length of the face were retarded more than width. Stature was the most retarded of any dimension studied, followed by sitting height; maxillary growth was next, and mandibular growth was least affected. Dental eruption was normal. Skeletal age was found to be retarded. However, dental age was normal. Dentofacial Changes Produced Mulatta: A Roentgenographic Barry Samuel
Cutler
University
Washington,
of
Seattle,
by a Modified and Histologic
Milwaukee Brace in Macaca Study (M.S.D. thesis)
Wash.
This roentgenographic and histologic investigation was undertaken to study the pattern of dentofacial growth in three Macaca mulatta monkeys which, for periods ranging from 54 to 252 days, wore a modified version of the therapeutic Milwaukee brace. Tantalum implants were placed in the maxillas and mandibles of the animals, providing stable landmarks for the superpositioning of serial cephalometric
Volume Number
55 4
Reviews and abstracts
419
tracings. Tetracycline and Procion vital bone markers were administered. TWO monkeys were killed after 178 and 252 days in the brace. Decalcified and ground bone sections of the maxillary sutures, tuberosity region, posterior cranial vault, mandible, and temporomandibular joint were examined histologically and compared with control data. The following conclusions are based on the results of the cephalometric and histologic findings : 1. The modified Milwaukee brace produced a directional change in growth of the dentofacial complex in the Macaca mulatta similar to that seen in clinically treated scolicosis patients. This was manifest as an anterosuperior relocation of the maxilla and mandible relative to the cranial base registration and Frankfort horizontal plane. 2. A reduction of over-all facial height is attributed to an equal amount of intrusion and buccal tipping of both the maxillary and mandibular molars. Labial tipping of the incisor teeth is common to both arches but is more pronounced in the lower. 3. Inability to demonstrate conclusive growth disturbances in the sutures of the upper face suggests that an alteration in their growth direction, rather than compression at these areas, is responsible for the redirection of maxillary growth. 4. Growth at the tuberosity region is unaffected by the external pressure of the brace. 5. The normal tendency for appositional growth at the lower border of the mandible is subjugated by the external pressure of the chin pad. Normal growth of the mandibular body proceeded in those areas not subjected to this influence. 6. R,adiographic interpretation that condylar growth is retarded under the pressure influence of the brace was confirmed by histologic examination. All evidence indicated that interference in normal hypertrophic changes of the chondrocytes, necessary for the progression to endochondral ossification, is responsible for this growth disturbance. 7. The normal appearance of the articular tissues of the temporomandibular joint in the experimental monkeys suggests that pathologic changes are not initiated during Milwaukee brace therapy. 8. Comparison with studies on retardation of condylar growth indicates that the presence of a continuous restraining force applied to the condyle is of more consequence than the magnitude of the force. 9. Anterior cranial base growth was unaffected by the modified Milwaukee brace. However, the pressure of the occipital support pad against the posterior aspect of the calvarium resulted in a ventral relocation of the posterior cranial f 0558.
Reviews and abstracts
Am
J. Orthodontics Ajwill969
occurred. The results of the study bear out the findings reported by other authors concerning the effects of such injuries on the permanent teeth. Exarticulation of a deciduous tooth almost always resulted in damage to the corresponding permanent tooth. An intruded tooth usually re-erupted within 6 months, and the pulps of rc-erupted deciduous teeth were often oblitcratcd ; many such teeth interfered with the eruption of their successors and had to bc removed when normal resorption failed to occur. Damage to the permanent teeth after intrusion of the deciduous incisors was found in onIy one sixth to one fifth of the cases. It is evident from the results of this study that luxation in some cases promoted resorption of the deciduous tooth and, hence, premature shedding, but in most cases the teeth were either unaffected or obliterated. Deciduous teeth that had loosened either remained unaffected or the pulps were obliterated with the same frequency, and only a small number mere damaged so much that they had to bc extracted. Loosening of the deciduous tooth rarely had any effect on the permanent successor, and in the few cases in which it did the injury was not serious. Dentofacial William J. Am.
Development
in Children
With
Vitamin
D-Resistant
Rickets
E. Tracy and Robert A. Campbell Dent.
A. 76: 10.26-1091,
May,
1968
l?acial growth, eruption and calcification of the teeth, physical growth, and skeletal maturation were studied in six girls and three boys with vitamin Dresistant rickets. The children selected ranged in stature from below the third percentile to the tenth percentile for their chronologic age. Results show that when the children were considered as a group two maxillary measurements showed retardation, and all other maxillary and mandibular dimensions were normal. Among the individual children with retarded facial growth, the maxillary dimensions were retarded more frequently than the mandibular, and height and length of the face were retarded more than width. Stature was the most retarded of any dimension studied, followed by sitting height; maxillary growth was next, and mandibular growth was least affected. Dental eruption was normal. Skeletal age was found to be retarded. However, dental age was normal. Dentofacial Changes Produced Mulatta: A Roentgenographic Barry Samuel
Cutler
University
Washington,
of
Seattle,
by a Modified and Histologic
Milwaukee Brace in Macaca Study (M.S.D. thesis)
Wash.
This roentgenographic and histologic investigation was undertaken to study the pattern of dentofacial growth in three Macaca mulatta monkeys which, for periods ranging from 54 to 252 days, wore a modified version of the therapeutic Milwaukee brace. Tantalum implants were placed in the maxillas and mandibles of the animals, providing stable landmarks for the superpositioning of serial cephalometric
Volume Number
55 4
Reviews and abstracts
419
tracings. Tetracycline and Procion vital bone markers were administered. TWO monkeys were killed after 178 and 252 days in the brace. Decalcified and ground bone sections of the maxillary sutures, tuberosity region, posterior cranial vault, mandible, and temporomandibular joint were examined histologically and compared with control data. The following conclusions are based on the results of the cephalometric and histologic findings : 1. The modified Milwaukee brace produced a directional change in growth of the dentofacial complex in the Macaca mulatta similar to that seen in clinically treated scolicosis patients. This was manifest as an anterosuperior relocation of the maxilla and mandible relative to the cranial base registration and Frankfort horizontal plane. 2. A reduction of over-all facial height is attributed to an equal amount of intrusion and buccal tipping of both the maxillary and mandibular molars. Labial tipping of the incisor teeth is common to both arches but is more pronounced in the lower. 3. Inability to demonstrate conclusive growth disturbances in the sutures of the upper face suggests that an alteration in their growth direction, rather than compression at these areas, is responsible for the redirection of maxillary growth. 4. Growth at the tuberosity region is unaffected by the external pressure of the brace. 5. The normal tendency for appositional growth at the lower border of the mandible is subjugated by the external pressure of the chin pad. Normal growth of the mandibular body proceeded in those areas not subjected to this influence. 6. R,adiographic interpretation that condylar growth is retarded under the pressure influence of the brace was confirmed by histologic examination. All evidence indicated that interference in normal hypertrophic changes of the chondrocytes, necessary for the progression to endochondral ossification, is responsible for this growth disturbance. 7. The normal appearance of the articular tissues of the temporomandibular joint in the experimental monkeys suggests that pathologic changes are not initiated during Milwaukee brace therapy. 8. Comparison with studies on retardation of condylar growth indicates that the presence of a continuous restraining force applied to the condyle is of more consequence than the magnitude of the force. 9. Anterior cranial base growth was unaffected by the modified Milwaukee brace. However, the pressure of the occipital support pad against the posterior aspect of the calvarium resulted in a ventral relocation of the posterior cranial f 0558.