Abstract:
A method for the reconstruction of missing, broken and/or abraded teeth by means of face analysis. In order to determine the shapes and sizes of the teeth, the face of a patient, for whom the teeth are intended, is measured by means of one or more image-type pictures. The respective tooth size and tooth shape is determined proportionally from the obtained values.

Description:
FIELD OF THE INVENTION 
     The invention relates to a method for reconstructing missing, broken and/or abraded teeth. 
     BACKGROUND OF THE INVENTION 
     Replacing natural teeth by producing false teeth from the originals of natural teeth and their use in dentures does not constitute a problem under normal circumstances. 
     However, the reconstruction of missing, broken and/or abraded teeth, that is to say of teeth for which the original tooth is no longer available or no longer completely available, is problematic. If no photo of the patient with a photo of the face existed “perchance”, in which, e.g. as a result of a smile, the teeth were visible, false teeth could with respect to their shape and size only be used on the basis of estimations and the available space in the mouth. 
     This also resulted in the risk of changing the appearance of the patient, in particular if a number of teeth of the upper jaw or even the entire upper jaw had to be replaced. 
     The present invention is therefore based on the object of providing a method by means of which replacement teeth can be produced even in the case of missing, broken and/or abraded teeth, which replacement teeth correspond as far as possible to the natural teeth in their shape and size. 
     SUMMARY OF THE INVENTION 
     According to the invention, this object is achieved by a method in which a reconstruction of missing, broken and/or abraded teeth is carried out by means of facial analysis, the face of a patient, for whom the teeth are provided, being measured by means of one or more image records in order to determine the shapes and sizes of the teeth, whereupon the respective tooth size and tooth shape is determined in proportion from the obtained values. 
     The inventor has discovered from lengthy and complex series of trials that shapes and sizes of teeth can be derived from certain features, shapes and dimensions of the face of the patient. This also holds when the teeth of the patient are already missing or are (partially) destroyed. This insight was used systematically by the inventor for reconstructing natural teeth. To this end, an image record, e.g. a photographic image, of the face of the patient was taken in the form of a frontal image. The face of the patient was measured on the basis of the produced photo, whereupon the obtained values subsequently allowed deduction of the corresponding proportion of the teeth sizes and teeth shapes. 
     A very advantageous method which approximates reality very closely can consist of determining the original width of the nasal base for reconstructing the spacing of the tips of the two canine teeth of the patient from one another, the determined value being provided as a corresponding proportion for determining the widths of the other teeth in proportional form. 
     This insight then makes it possible to determine the respective widths of the six most important teeth of dentures, namely the two front teeth, the two lateral incisors and the two canine teeth, in accordance with the original teeth. 
     The shapes and sizes of all other teeth can then be determined from further features of the face; for example, the contour of the face can produce the central front tooth, the ratio of the widths of the nasal base and nasal root, the diagonals of the lower end of the nose and the nasal wing the second incisor, and the profile of the cheek the canine tooth. 
     The inventor has also discovered that the respective side of a patient which is more strongly set-up can be identified from the face, along with the fact resulting from this that the dentures are in general more harmonic on the side which is more strongly set-up, whereas the teeth are less regular on the side which is less strongly set-up. 
     Therefore, according to the invention, the distance of the bipupil line to the corner of the mouth line is determined in order to reconstruct the side of the patient which is more strongly set-up, the side with a greater length being stipulated to be the harmonic side. 
     Taking this fact into account makes it possible to match the false teeth or dentures even more closely to the original teeth or original set of teeth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantageous developments and refinements result from the dependent claims and from the exemplary embodiment described in principle below on the basis of the drawing, in which: 
         FIG. 1  shows a frontal view of the face of a patient in a line illustration; 
         FIG. 2  shows two front teeth of the patient from the upper jaw; 
         FIG. 3  shows a further illustration of the face of the patient in accordance with  FIG. 1 ; 
         FIG. 4  shows the face of the patient with a reconstruction of one of the two lateral incisors; 
         FIG. 5  shows a view of the two front teeth and the two lateral incisors; 
         FIG. 6  shows the face of the patient with a reconstruction of a canine tooth; 
         FIG. 7  shows a view of the upper jaw with the front teeth, the two incisors, and the two canine teeth; and 
         FIG. 8  shows the face of the patient with the line passing through the center of both pupils and the line passing through the corners of the mouth. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For reasons of simplicity and for improved clarity, the face of the patient in the figures is illustrated in the form of a line illustration. In practice, an image of the patient with a closed mouth is produced in this context for reconstructing the teeth. The image can be effected arbitrarily, for example in digital form, as a result of which it is possible to illustrate different refinements and reconstructions of the teeth in connection with the photographic image. Likewise, image processing and transfer to a computer are possible in this manner. This makes it possible for the measures for measuring the face of the patient for tooth reconstruction, carried out subsequently, to also be carried out using a computer program with corresponding software. 
     The following exemplary embodiment describes the reconstruction of the two front teeth  1 , the two incisors  2  and the two canine teeth  3  of the upper jaw. In general, a reconstruction of the teeth of the upper jaw which is as true as possible is important for the facial shape of the patient. 
     In accordance with  FIG. 1 , the contours  4  of the face of the patient are determined. In this case the forehead of the patient, to be precise a transition  5  between the forehead and the cranial arch adjoining the latter, represents the top side of the front tooth  1  with the cutting edge. The chin  6  represents the dental neck. 
     The width of the nasal base  7  of the patient is determined in order to determine the overall width of the front teeth  1 , the lateral incisors  2  and the canine teeth  3 . However, this is not effected on the basis of the image record, but directly on the face of the patient in order to obtain the original width. The original width of the nasal base  7  corresponds to the overall width of the six teeth, from canine tooth tip to canine tooth tip. Using this determined overall width and knowing the individual widths of the teeth with respect to one another, it is then possible to reconstruct the width of each tooth in combination with the subsequent determinations. 
     In accordance with  FIG. 2 , the shape obtained from the facial contours in  FIG. 1  is rotated through 180° for the two front teeth  1  of the upper jaw, so that the cutting edge points downward. The shape of the one front tooth obtained can be copied in a simple manner by mirroring in a vertical line  8 . Thus, a reconstruction of the second front tooth  1  is also obtained. 
     The reconstruction of the two lateral incisors  2  becomes clear from  FIGS. 2 to 6 . 
     In accordance with  FIG. 3 , the width of the nasal base  7  and the width of the nasal root  9  are measured on the basis of the image record (in this case the line drawing). At the same time, two diagonals  10  and  11  which define the lower end of the nose—the profile from the center of the nose via the two lateral nasal wings to be precise—are generated. The obtained and correspondingly lengthened diagonals  10  and  11  reproduce the profile of the cutting edges  12  of the front teeth  1 , the incisors  2 , and the canine teeth  3 . The transfer of the two diagonals  10  and  11  for the purposes of reconstructing these cutting edges is clear in particular from  FIGS. 5 and 7 . It was found that, for a more detailed and hence more precise transfer, it was more expedient if the image used to this end was larger than, preferably double the size of, the previously depicted photographic image used for the measurements. The diagonals  10 ′ and  11 ′ in this case pass through the intersections of the respective central lines of the teeth at the cutting edges. 
     The width of the incisor  2  is reconstructed in the following way: the value of the width of the nasal base  7  obtained from  FIG. 3  is divided by the value of the width of the nasal root  9 . At the same time, the overall width of the face, corresponding to line  13 , is determined in  FIG. 3 . The ratio of the result of the division (nasal base)/(nasal root) is used as divisor for the value of the overall width of the face in accordance with the image. The result obtained in this manner corresponds to the width of the incisor  2  to be reconstructed in relation to the front tooth  1 . 
     Example: the width of the nasal base in accordance with the photo is 20.5 mm, the width of the nasal root is 14 mm, and the overall width of the face in accordance with the photo is 52 mm. 
     Nasal base (20.5)/Nasal root (14)=1.46 
     Overall width of face (52)/1.46=35.6 
     This means that the ratio of widths of the front tooth  1  to the incisor  2  is 52:35.6. 
     The outer shape of the incisor  2  is fixed by the contour of the face from the second image (on the same side). The inner shape of the incisor  2  is matched freely. 
       FIG. 5  shows the frontal view of the two front teeth  1  with the two incisors  2 , mirroring being undertaken—if necessary—for copying in the vertical line  8 . 
       FIG. 6  clarifies the reconstruction of a canine tooth  3 . The outer shape  14  of the canine tooth  3  respectively facing the outside of the face corresponds to the profile of the shape of the left cheek in the case of the left canine tooth. Similarly, the profile of the outer shape of the right canine tooth corresponds to the profile of the shape of the right cheek, provided that the right canine tooth is not reconstructed in the vertical line  8  by mirroring the left canine tooth (see  FIG. 7 ). 
     The height or length of the canine tooth  3  is determined in the following manner: the diagonal  10  is displaced in a parallel fashion and applied as tangent  10 ″ to the central line of the front tooth  1  at the intersection with the cutting edge. Subsequently, the image record is “displaced” such that the tangent  10 ″ passes through the right eyebrow at the right canine tooth  3 . 
     In practice it was found that, compared to the illustrations in accordance with  FIGS. 1 and 3  used for the reconstruction, larger illustrations or images are advantageous for the profile of the outer shape  14  of the canine tooth  3 , just like the profile of the cutting edge  12 , in order to obtain higher accuracy of details. 
     Since the width of a canine tooth  3  is in general 80% of the width of an incisor  2  in a frontal view, it is also possible to reconstruct the width of the canine tooth  3 . 
     Since, in general, every human has a “strong” and a “weak” side, which is also mirrored in the human&#39;s set of teeth, this fact should also be taken into account during a reconstruction. 
       FIG. 8  clarifies the determination of the more strongly set-up side of the patient. To this end, a so-called bipupil line  15  is drawn between the two eyes and a corner of the mouth line  16  is drawn through the closed mouth of the patient. The two lines, that is to say the bipupil line  15  and the corner of the mouth line  16  are generally not precisely horizontal or parallel to one another. If the distances  17  and  18  on both sides of the nose are measured in the outer region of the face, it will be determined that in general one distance line is longer than the other. In the illustrated exemplary embodiment, the distance line  17  is slightly longer than the distance line  18 . This means, since it is the right-hand side of the patient in this case and hence the right-hand side of the dentures should be set-up more strongly. 
     Knowing these circumstances makes it possible to fix the right-hand side of the dentures as the harmonic side.