American journal of orthodontics and oral surgery最新文献

• 1.

  1. At birth there is no occlusion between the gum pads.

• 2.

  2. (a) There is a suggestion that poor occlusion is more prevalent when anterior space falls into Classes B, C, or D. However, in some instances, good occlusion may develop regardless of anterior space at birth. (b) A change of morphology of the anterior space from symmetric to asymmetric is associated with poor occlusion.

• 3.

  3. The mandible was posterior to the maxilla at birth in 161 infants. The distance A ranged from 0 to 8 mm. with a mean value of 2. 6 millimeters.

• 4.

  4. From the group of forty-eight children there were three (20 per cent) with good occlusion and twelve (80 per cent) with poor occlusion when the dimension A varied from 4 to 8 millimeters. This suggests that this range of dimension is more likely to be associated with poor occlusion.

• 5.

  5. Twenty-two children out of a group of thirty-eight have widths of the jaws at birth outside of the range of an established norm. Seven (31 per cent) developed into good occlusion, while fifteen (68 per cent) developed into poor occlusion. This suggests that poor occlusion may be foreshadowed at birth in many instances.

• 6.

  6. Smooth, rhythmic curves of the widths of the dental arches from birth onward are associated with good occlusion.

• 7.

  7. Irregular curves with lack of rhythm are associated with poor occlusion.

• 8.

  8. Among the sixteen children with good occlusion, only six (37. 5 per cent) show a decrease in width, whereas among the twenty-two children with poor occlusion, thirteen (51 per cent) show a decrease in width. This suggests that decrease in width is more likely to be associated with poor occlusion.

• 9.

  9. (a) Four out of the five infants with a difference of less than 3 mm. between the widths of the maxillary and mandibular arches developed poor occlusion. (b) Five out of the six children with a difference of over 7 mm. between the widths of the dental arches, as seen by the last casts, have poor occlusion. (c) Three out of four children with a difference under 4 mm. have poor occlusion. This suggests that dimensional differences within the limits mentioned are associated with poor occlusion.

According to the hypothesis outlined, infection is an essential factor in periodontal disease which contributes largely to its clinical character; but infection is never more than one factor among several, and the others are accorded primary or determining importance. The infection is postulated as endogenous, as an overgrowth of certain resident parasites which, although harmless when in contact with healthy tissues, are enabled to proliferate, and in greater or less degree to invade the tissues, when these tissues are damaged by other causes. It seems probable that the inflammation, suppuration or ulceration of periodontal disease is contributed directly by infection. If the nature of this infection can be more precisely delineated and if, on the basis of such knowledge, the host factors that govern its course, including its tendency to be localized or invasive, can be defined, a long step will have been taken toward clarification of the etiology and pathogenesis of periodontal disease.

A method was presented for routine isolation and cultivation of certain of the oral spirochetes associated with lesions in cases of ulcerative stomatitis. The technique was based primarily upon the use of a-well for holding the spirochetel-containing inoculum in the confines of a highly nutritious medium of low agar concentration, which favors rapid multiplication and penetration of the medium by the spirochetes. Numerous strains of the smaller oral treponemes and three strains of Bor. vincenti were obtained by this method.

Agglutination studies were undertaken. Media and techniques were devised both for mass cultivation of organisms for intravenous inoculation of rabbits and for use as antigen in performing microscopic agglutination reactions. Strains of T. pallidunt and various strains of the oral spirochetes were shown to be highly antigenic. The agglutination titres of immune serums of rabbits when tested against homologous strains of spirochetes ranged between 1: 1,000 and 1: 1,000,000.