Patent Publication Number: US-6036492-A

Title: Collection of artificial front teeth

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is the U.S. national phase of International Application No. PCT/EP98/01859 filed Mar. 31, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The efforts that have been made to simulate as closely as possible the wide variety of shapes of the natural teeth have led to a situation where the collections of artificial front teeth available on the market comprise a very large number of individual tooth shapes. This not only complicates matters in terms of manufacture and storage, but also makes selection difficult because of the profusion of different types. The categories chosen for these collections are also unsatisfactory. These are, on the one hand, categories based on the Kretschmer constitutional type classification which proposes correspondences between the tooth shape and the athletic, pyknic and leptosomic constitutional types, and, on the other hand, the association with geometric figures such as triangle, rectangle, shovel shape, square, oval, which are only to be found with difficulty in the multiplicity of shapes of natural teeth. 
     SUMMARY OF THE INVENTION 
     The invention creates a classification of a collection of artificial teeth, linked to certain tooth dimensions, which can be easily measured, but are also easy to evaluate by the trained eye. 
     The collection of artificial front teeth according to the invention comprises, in each important size class, three groups of shapes which differ in terms of the relationships of the mesiodistal widths of their vestibular surfaces in the cervical, central and incisal thirds of their length. In a cervically accentuated group, the mesiodistal widths are approximately identical in all the thirds. That is to say they differ from one another by not more than 10%, preferably 5%. In a centrally accentuated group, the width of the tooth in the central third is greater than in the two other thirds, and in particular it is greater than the width in the cervical third at least by the factor 1.15, preferably 1.2. In an incisally accentuated group, the width in the incisal third is greater than in the two other thirds, and in particular greater than the width in the cervical third by the factor 1.18, preferably 1.24. 
     The front teeth are the incisors and canines. With respect to the width measurement according to the invention, the vestibular surfaces are delimited by their margins. These can be visualized without difficulty. The border lines forming the basis of the width measurement are defined by the lines of greatest curvature (smallest radius of curvature in the horizontal sectional plane). The width is not to be measured linearly, but following the curved surface, and in particular along that line which connects by the shortest distance two points, each situated at the same height, of the two border lines. 
     The thirds are determined by dividing by three the length of the vestibular surfaces between the cutting edge and the cervical margin of the enamel measured along their mid-line. In each third, measurement is carried out at the area of greatest width. This may coincide with a border line of the third. 
     The invention relates exclusively to artificial teeth in the real sense, i.e. mechanically produced front teeth which imitate fully anatomically the shapes of the human front teeth and are used as replacements in edentulous areas of the jaw in the context of prosthetic replacement by total or partial prostheses and implant superstructures. It does not relate to crowns. 
    
    
     BRIEF DESCRIPTION OF A THE DRAWING 
     The invention is explained in greater detail below with reference to the drawing, in which: 
     FIG. 1 shows the vestibular surface of a tooth, showing the measurement points and the dividing lines, and 
     FIGS. 2 to 4 show three different types of teeth. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1, representing an upper incisor, shows the tooth neck 1, the cemento-enamel limit 2 of the enamel, the cutting edge 3 and the vestibular margins 4 which are defined by the lines of in each case the smallest radius of curvature in planes running perpendicular to the tooth axis. The line 5 represents the mid-line of the vestibular surface thus delimited. Its length between the enamel margin 2 and the cutting edge 3 is divided into three equal sections, their limits 6, 7 being perpendicular to the tooth axis. They separate the cervical third F1 from the central third F2 and separate the latter from the incisal third F3. 
     The greatest mesiodistal width in each of these sections is determined. In the example shown (FIG. 1), this lies at the line 10 in the incisal third F3. The width is to be measured between its end points 10. The same applies to the central third, in which the greatest mesiodistal width is determined between the measurement points 9. In the cervical third F1, the measurement is carried out between the points 8. The greatest width measured in the cervical third is designated by the symbol &#34;c&#34;, that measured in the central third is designated by the symbol &#34;m&#34; and that measured in the incisal third is designated by the symbol &#34;i&#34;. 
     On measuring a large number of natural teeth, it was found that the criterion of width comparison in the three thirds afforded a particularly simple and clear standardization and a collection of artificial teeth which covers the necessary range of types with a comparatively small number of different tooth shapes, provided that the tooth groups representing these types are characterized and distinguished from each other as has been set out above and in the claims. 
     The group of cervically accentuated teeth is characterized by the fact that c, m and i are approximately identical or differ from one another by not more than 10%, preferably 5%. FIG. 2 shows an example. 
     The centrally accentuated group, which is represented by way of example in FIG. 3, is characterized by the fact that a sturdy body shape determines the appearance. It is therefore also referred to as body-accentuated. Its greatest mesiodistal width lies in the central third. This is greater than in the incisal third and considerably greater (namely at least by the factor 1.15, preferably 1.2) than the greatest width of the cervical third. 
     The incisally accentuated group, which is represented by FIG. 4, shows its greatest width in the incisal third. It is greater there than in the central third and considerably greater (namely at least by the factor 1.18, preferably 1.24) than in the cervical third. 
     This grouping in threes is found in the collection according to the invention for each critical size class, of which at least three are expediently provided, designated by I, M and S. Preferably, it is also provided in additional size classes; this is not absolutely necessary, however. 
     The following table shows, for the size class &#34;L&#34; (large), the corresponding widths in the different thirds. The letters &#34;C&#34;, &#34;B&#34; and &#34;I&#34; stand for the cervically accentuated, body-accentuated and incisally accentuated groups. In addition to the maximum mesiodistal spacings on the vestibular surface, the respective heights &#34;D&#34; of the vestibular surfaces are also indicated. 
     
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Maximum mesiodistal spacing on the                                        
vestibular surface in mm                                                  
             F1  F2        F3    D                                        
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Upper jaw                                                                 
Tooth 11   CL      9.0   9.0     9.1 11.1                                 
Tooth 21   CL      8.3   8.3     8.3 11.0                                 
Tooth 11   BL      7.8   9.4     9.2 11.6                                 
Tooth 21   BL      7.2   9.2     8.2 11.7                                 
Tooth 11   IL      7.6   8.3     8.7 11.7                                 
Tooth 21   IL      7.0   8.0     9.0 11.6                                 
Tooth 12   CL      7.9   7.8     7.8 10.1                                 
Tooth 22   CL      7.7   7.8     7.8 10.0                                 
Tooth 12   BL      5.8   7.8     6.8 10.4                                 
Tooth 22   BL      5.6   7.2     7.0 10.3                                 
Tooth 12   IL      5.9   7.1     7.2 10.3                                 
Tooth 22   JL      5.8   7.2     7.5 10.4                                 
Tooth 13   CL      9.1   9.1     9.1 12.5                                 
Tooth 23   CL      9.8   9.7     9.6 12.3                                 
Tooth 13   BL      8.0   8.8     8.8 12.8                                 
Tooth 23   BL      7.8   9.4     9.2 12.0                                 
Tooth 13   IL      7.2   9.3     9.5 12.3                                 
Tooth 23   IL      7.5   9.4     9.5 12.0                                 
Lower jaw                                                                 
Tooth 31   CL      7.3   7.1     6.9 9.0                                  
Tooth 41   CL      6.9   6.9     6.8 8.8                                  
Tooth 31   BL      6.2   7.2     7.0 8.7                                  
Tooth 41   BL      5.6   7.0     6.2 8.8                                  
Tooth 31   IL      5.0   5.6     6.2 8.7                                  
Tooth 41   IL      5.1   5.9     6.4 8.9                                  
Tooth 32   CL      6.0   6.0     6.0 9.3                                  
Tooth 42   CL      6.8   6.8     6.8 9.0                                  
Tooth 42   BL      6.1   7.7     7.4 10.0                                 
Tooth 32   BL      5.9   7.5     7.3 9.7                                  
Tooth 32   IL      5.2   6.1     6.5 9.8                                  
Tooth 42   IL      5.1   6.3     6.5 9.9                                  
Tooth 33   CL      7.5   7.4     7.4 11.0                                 
Tooth 43   CL      8.0   7.7     7.5 10.7                                 
Tooth 33   BL      7.0   8.8     7.8 10.7                                 
Tooth 43   BL      7.0   8.6     8.0 10.4                                 
Tooth 33   IL      7.5   8.2     9.5 12.2                                 
Tooth 43   IL      7.5   9.0     9.3 12.5                                 
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     The following table gives a numerical example for an upper cervically accentuated incisor in three size classes: 
     
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Maximum mesiodistal spacing on the                                        
vestibular surface in mm                                                  
             F1  F2        F3    D                                        
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Tooth 21   CL      8.3   8.3     8.3 11.1                                 
Tooth 21   CM      8.0   7.9     7.9 10.6                                 
Tooth 21   CS      7.5   7.5     7.4 10.0                                 
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