Vertical Discrepancy Research Articles

Internal escape channel to improve the seating of full crowns with various marginal configurations: A follow-up study

The effectiveness of an internal escape channel in improving the marginal adaptation of full crowns with various marginal configuration was investigated. Full crowns with 90-degree shoulders had a vertical discrepancy comparable to those of crowns with accentuated finish lines. Although an internal escape channel significantly improved the seating of a full crown with a 90-degree shoulder and 45-degree bevel, its vertical discrepancy was much higher than those of crowns with an accentuated finish line or a 90-degree shoulder.

Comparison of two methods of profile prediction in surgical treatment of mandibular prognathism

Two methods for prediction of the soft tissue profile subsequent to oblique subcondylar osteotomy for correction of mandibular protrusion were evaluated. The first one included distalization of the mandible into an Angle Class I relationship. The amount of distalization and any vertical changes were transferred to the tracing, and the anticipated new profile was drawn. The second method was based on the profile means of a group of "normal" persons and was aimed at correction of both sagittal and vertical discrepancies. Fifty patients were studied. A double set of prediction tracings was made according to both methods; and the results were compared with the actual postoperative results and with a "normal" control group. Both methods were usable, as the predictions were considered satisfactory if they were within one standard deviation from the mean of the control group. The sagittal changes were somewhat exaggerated by both analyses. The vertical changes were much better expressed by the profile prediction. Such changes are difficult to create by the vertical subcondylar osteotomy. Consequently, the model prediction seems most suitable for planning profile changes in surgical techniques that include mobilization of one main mandibular fragment.

Effect of multiple axial grooves on the marginal adaptation of full cast-gold crowns

Twenty-seven crowns were fabricated on the standardized ivorine dies to determine the effect of multiple axial grooves. No grooves were placed on the control (group I). In groups II and III, respectively, two and four grooves were replaced. The mean value of the occlusal cement film thickness was used to appraise the vertical discrepancy (lack of seating) of the crown on the die. This value was obtained by averaging seven measurements of the occlusal cement film thickness taken at different areas. These measurements were recorded from the photomicrographs at x 100 magnification. There were significant differences between the control group and both test groups. Results of this study show that the presence of the grooves has an adverse effect on the seating of full cast-gold crowns.

Relationship of investing medium to occlusal changes and vertical opening during denture construction

Four groups of 20 dentures with nonanatomic teeth were processed using four different investing techniques. The incisal guide pin was measured and recorded before processing and again after processing and remounting of each denture on the articulator. The difference between the two readings indicated vertical changes during processing. The least vertical opening and a complete absence of occlusal changes occurred in the dentures invested in the plaster of paris core with an artificial stone cap. The following conclusions were made: (1) Vertical opening in denture processing can be minimized by investing in plaster of paris molds with a stone occlusal matrix. (2) Tooth movement is minimized by the use of this investment combination. (3) Inadequate investing procedures contribute to vertical opening and occlusal discrepancies. (4) Vertical opening of dentures processed by compression molding technique may be due to other factors. This can only be determined by further investigation.

The interplay of drifts and flicks in binocular fixation

A study of spontaneous human eye movements during monocular and binocular fixation was made in order to determine the corrective roles of flicks and drifts. It is found that both types of motions correct fixational errors although flicks are somewhat more active in this respect. Vergence error is a stimulus for correction by drifts but not by flicks, while binocular vertical discrepancy of the visual axes does not trigger corrective movements.

The effects on tooth position and maxillofacial vertical growth during treatment of scoliosis with the Milwaukee brace

We propose that malocclusions with predominantly vertical problems (open bite and deep bite) are challenging to treat because the skeletal and dentoalveolar components defining the vertical discrepancy are subject to a myriad of arrangements. Accordingly, the purpose of this paper is to relate how these variations must be factored into proper diagnosis, and demonstrate that individual characterization and not a “generic” phenotype for open bite and deep bite should be the basis for treatment planning. Variations include the coexistence of hyperdivergence (“high angle”) with deep rather than open bite. Specifically, the importance of component analysis is presented along with the nuances of classification of malocclusion in the vertical dimension. The state of current evidence is presented, including (on average) the constancy of the vertical growth pattern, the potential for a vertical problem to mask or worsen a sagittal dysmorphology, the possible contribution of environment and genetics in different extents to maxillary and mandibular problems, and the need to explore many unknown facts about the vertical dimension.