WO2016055890A1

WO2016055890A1 - Method for determining and drawing the ideal individual shape of the six upper front teeth

Info

Publication number: WO2016055890A1
Application number: PCT/IB2015/057287
Authority: WO
Inventors: Aldo AMATO
Original assignee: Amato Aldo
Priority date: 2014-10-06
Filing date: 2015-09-22
Publication date: 2016-04-14

Abstract

The invention is a method for determining and drawing the ideal and customized shape of one or more of a patient's six upper front teeth. The method uses one or more images of the patient's face in a front view and at least one image of the front teeth in occlusion; furthermore, it uses parameters that can be obtained from the shape of the face as it is reproduced on said images to determine n points of reference, wherein the perimeter of the tooth is obtained by drawing an approximate curve joining said points.

Description

METHOD FOR DETERMINING AND DRAWING THE IDEAL INDIVIDUAL SHAPE OF THE SIX UPPER FRONT TEETH

DESCRIPTION

The present patent concerns teeth reconstruction methods, and in particular it concerns a new method for determining and drawing the ideal individual shape of the six upper front teeth.

Methods intended to reproduce the shape of teeth in conservative prosthetic or reconstruction rehabilitation have been the subject of studies by experts from all over the world for more than one hundred years now.

The need to transform the artistic intuition of dentists into an operating technique was already felt in the past century. At the end of the nineteenth century attention was focused on the criteria that could be adopted for the selection of the prosthetic teeth to be included in removable dental prostheses, in such a way as to match the characteristics of the patient's face and thus meet his/her expectations. This led to the development of the morphogenetic theories deriving from Darwin's studies on the concept of evolution, and of the theories based on the individual's psychological characteristics. Various methods were proposed, which were based on empirical concepts but were however accepted by the scientific community of the time.

The pioneer of research in this field was Williams J.L., who at the beginning of the twentieth century (1920), in his "A new classification of human toothforms", formulated a hypothesis according to which the shape of the teeth reflected the shape of the face rotated by 180°, that is, with the individual's forehead facing downwards.

That theory has been accepted by the scientific community up to our times, when it has been doubted by renowned authors due to lack of a scientific background. These authors, however, have not been able to find an alternative, and they have actually left to dentists and dental technicians the burden of finding the shape that best matches the patient's face. In the case of edentulous patients, templates are available, with which it is possible to statistically find the most suitable shapes for sets of 6 or 12 teeth, in three or four possible different sizes. It has been shown that this system is not sufficiently effective and does not allow the selection of the teeth to be customized, especially based on the patient's face. At present, the modelling of prosthetic teeth is carried out by the dental technician based on a few points of reference on a model made of plaster or a similar material, or in some cases, but not very frequently, through the examination of a photograph of the patient, which allows the characteristics of the face to be taken in consideration.

It should be underlined that dental technicians do not have a humanistic background, rather a technical background, do not know nor see the patients and therefore prepare the teeth just following the instructions provided by the dentists, which are limited to just a few basic elements including a schematic description of the shape of the face, which for example can be oval, square or triangular. These elements are intuitively identified by the dentist, which records them on the specifications in such a way that the dental technician can choose the prosthetic teeth based on these three standard shapes.

It can be easily understood how the empirical nature of the technique presently known and applied by almost all the dentists in most cases does not lead to the immediate and certain achievement of the desired aesthetic results.

The outcome depends almost completely on the artistic skills of the dental technician and the dentist; this usually involves the need for an endless series of aesthetic teeth fitting tests, adjustments, remakes, and sometimes the patient is not satisfied with the final results. Patent US8092220 concerns a method for reconstructing teeth according to which the shape and size of a tooth are determined based on the analysis of the patient's face.

According to the patent mentioned above, the shape of the human upper central incisor tooth corresponds to the shape of the overturned face. As already mentioned, this concept is based on empirical considerations that for this reason are not universally valid or applicable.

The lack of a recognized and reliable technique and the actual difficulties found by dentists and dental technicians when it comes to modelling prosthetic teeth in a harmonious manner so that they match the patient's features, the numerous failures in terms of aesthetic results, the endless aesthetic teeth fitting tests necessary before completing the prosthetic teeth have led the inventor to look for an alternative solution and develop the method that is the subject of the invention.

The present invention makes it possible to provide the drawing of the ideal teeth for the patient's face, in such a way as to comply with the criteria that can be defined as "perceived aesthetic standards". The present invention has the purpose to provide dentists and dental technicians with a simple and quick method that allows prosthetic teeth to be produced and manufactured also in the absence of reference points, with a natural shape and size, in harmony with the patient's face.

Differently from the methods presently known, such as the method that is the subject of the document mentioned above, the present invention, even though it makes reference to the geometric lines present in the patient's face, applies selected parameters that are properly synthesized in a single and original algorithmic method and make it possible to determine a series of ideal points for the production of a drawing reproducing, in particular, the six upper front teeth.

The majority of the aesthetic and statistical parameters of the face and teeth used in this method were never mentioned or used for this purpose.

The method described in this patent is unique and original, as it is different from the techniques known at present, easy to use and furthermore can be transformed in software for a dedicated IT application, thus further quickening calculations and its application procedure.

The new algorithm/method for calculating and drawing the individual shape of teeth can be used by an expert user, like for example a dentist, a dental technician or a doctor in general who must be able to transfer the algorithmic method to the required photographic images or to use software containing said algorithmic method.

The required photographic images are preferably the following:

• at least one photographic image of a front view of the patient's face, with closed mouth; • at least one photographic image of a front view of the dental arches in occlusion;

• at least one photographic image of a front view of the patient's face smiling with the teeth in occlusion.

Although this technique can be applied to any type of photograph, in any case it privileges the use of digital images and digital drawing tools. The creation of specific software through the application of the present invention can provide the expected result in real time.

The invention is a method for determining and drawing the ideal individual and customized shape of one or more of a patient's six upper front teeth, missing or however damaged, said method being characterized in that it comprises the following steps:

• use of one or more images of a front view of the patient's face and at least one image of the front teeth in occlusion;

• determination of at least one reference line or smile line that passes through the incisal edges of the upper central incisor teeth and through the cusps of the canine and bicuspid teeth, said reference line or smile line (1) being curved, with curvature substantially equal to that of the patient's lower lip, which tends to be convex upwards;

• determination of a rectangle for the tooth to be drawn, said rectangle having a predefined width/height proportion ratio;

• positioning of the base of the rectangle with its mid point on said reference line or smile line;

• determination of n points on the perimeter of said rectangle,

wherein said points are determined taking in consideration at least the following parameters that can be obtained from the face shape reproduced on said images:

front facial angle, obtained by setting the vertex at the level of the septal angle; facial inclination angle, constructed by measuring the angle between the tangent to the face in its lower portion and a vertical line;

straight line passing joining a pupil and a hypothetical interproximal contact point selected by the user; - tangent to the approximate curve of the contour of the lower mandibular half- face,

and wherein the perimeter of the tooth is obtained by drawing an approximate curve joining said points.

The characteristics of the new method are illustrated in greater detail in the following description, with reference to the attached drawings that are enclosed hereto by way of non-limiting example.

Figure 1 shows the three images (Ml, M2, M3) used in the new method, and in particular a photographic image of a front view of the face with closed mouth (Ml), a photographic image of a front view of the smiling face with the teeth in occlusion (M2), a photographic image of a front view of the dental arches in occlusion (M3).

Figure 2 shows the reference rectangle (R) used to draw the points (A, B, C, D, E, F, G, H) and the curve (K) delineating the right central incisor tooth (SI 1).

Figure 3 shows the reference rectangle (R) with the first two points (A, E).

Figure 4 shows the image (M3) of the dental arches in occlusion, the curves delineating the six upper front teeth (SI 1, S12, S13, S21, S22, S23) and the imaginary reference line or smile line (1).

Figure 5 shows the construction rectangle (R) with the three points (A, E, C).

Figures 6 and 7 show other steps of the construction process.

Figure 8 shows the front facial angle (AFF) drawn on the photographic image of a front view of the patient's face with closed mouth (Ml).

Figure 9 shows the facial inclination line (IF) and the facial inclination angle (AIF) drawn on the photographic image of the face, in front view, with closed mouth (Ml).

Figure 10 shows another step of the construction of the curve of the right upper central incisor tooth (SI 1).

Figures 11 and 12 show two images (M3) of the teeth in occlusion.

Figure 13 shows another step of the construction of the curve of the right upper central incisor tooth (Sl l). Figure 14 shows the straight line (PX) joining a pupil (P) and a hypothetical interproximal contact point (X) selected by the user, drawn on the photographic image of a front view of the patient's smiling face (M2).

Figure 15 shows a part of the photographic image of a front view of the face with closed mouth (Ml), with the approximate curve (J) of the contour of the lower mandibular half- face and the related translated tangent (GF).

Figure 16 shows the tangent to the approximate curve of the contour of the lower mandibular half-face (T), drawn on the photographic image of a front view of the smiling face (M2).

Figure 17 shows a further construction step of the curve of the right upper central incisor tooth (S 11).

Figure 18 shows the photographic image of a front view of the smiling face (M2), including the construction straight line (PX) that joins the pupil (P) and the interproximal point (X) between the upper central incisor teeth (SI 1, S21).

Figure 19 shows the photographic image of a front view of the smiling face (M2), including the construction straight line (MG) tangent to the approximate curve of the contour of the lower mandibular half-face.

Figures 20 and 21 show further steps of the construction of the shape of the right upper central incisor tooth (SI 1).

Figures 22a and 22b respectively show the image of a front view of the dental arches in occlusion (M3) and only the right upper central incisor tooth (SI 1).

Figures 23, 24, 25, 26, 27, 28 show the steps of construction of the right upper lateral incisor tooth (S12).

Figures 29, 30, 31, 32, 33 show the steps of construction of the upper canine tooth (S13). Figures 34 and 35 show a face on which the reference lines for the correction of the inclination of the teeth according to any possible asymmetry in the patient's face are drawn. DESCRIPTION OF THE METHOD

According to the new method, the calculation is started from the upper central incisor teeth (Sl l, S21), and continued with the upper lateral incisor teeth (S12, S22) and the upper canine teeth (SI 3, S23).

• Creation of a rectangle as follows:

the rectangle has known height (RH) and width (RL), obtained through other rules or other software, or arbitrarily introduced by the user at his/her own discretion, provided that they respect a predefined height/width proportion ratio.

The base of the rectangle (point E) is then positioned at the level of the smile line or imaginary harmonious line or reference line (1) drawn by the user, which passes through the incisal edges (S3) of the upper teeth (Sl l, S21) and the cusps (S4) of the canine (S13, S23) and bicuspid teeth. Said imaginary line (1) is a convex curve with approximately the same curvature as the lower lip when smiling (see Figure 4).

Right upper central incisor tooth (Sll), see Figures 5, 6.

The same method is applied to the corresponding left tooth (S21).

o A is at the centre of the upper side of the rectangle (R);

o the rectangle is high H11C and wide F11C, wherein RH is the height of the tooth and RF is the front width. Said data are determined arbitrarily or through data obtained from other known methods. For example, it is possible to arbitrarily set the RL/RH ratio so that it is included between 0.6 and 0.9;

o E is at the centre of the lower side of the rectangle (R);

o B is an arbitrary point.

The height of the crown = HI 1C* is defined as HCC.

C is on the mesial segment, at a distance HCC from the upper segment (Figure 5).

o G is on the distal segment at a statistical distance HI 1C (statistical data) from the upper segment;

• H is given by the intersection between the distal segment of the angle AFF, the straight line IF (angle AIF) and the straight line PSL parallel to the smile line (1) of the half-arch, previously calculated by the user (Figure 7). The angle AFF is calculated by transferring the patient's facial angle (Figure 8) on the rectangle that has been created, positioning the vertex in point A. First the facial inclination line (IF) is drawn, then the segment of angle AFF is intersected with it. Then the line parallel to the smile line (1) is drawn.

• Calculation of the front face angle (AFF) (Figure 8).

o Upper angle:

§ on the photograph of a front view of the face with closed lips

§ the vertex of the angle AS (septal angle) and the segments with vertex AS intersect the right and left gonion;

o the resulting angle AFF is equal to AS.

• Calculation of the facial inclination angle AIF (Figure 9).

o The angle AIF is constructed by measuring the angle between the tangent to the face (between zygion and gonion) and the vertical line (Figure 9).

• Calculation of points H and B (Figure 7).

o A straight line is drawn from point G, with angle AIF;

o the angle AFF with vertex A is drawn from point A;

o the point of intersection between the straight line from G and the distal side of the angle determines H;

o a straight line is drawn from point C, with angle AIF/2 (Figure 13);

o the point of intersection between the straight line from C and the mesial side of the angle determines point Bl corrected with other successive data (Figure 11).

• Adaptation of H and A to the smile line (1) (Figures 11 and 12).

o Construction of the simulated smile line (1);

o calculation of the inclination of this tangent (tangent to the smile line (1));

o drawing of a straight line with origin in point B and the same inclination as the tangent to the smile line (1);

o H is re-determined in HI through the intersection between the straight line passing through G with inclination AIF and the smile line (1) passing through Bl; o calculation of the vertical distance between HI and B 1 ;

o Al is determined by shifting A by Delta x (Δχ) distally on the upper segment (Figure 13);

o D is determined as follows: in the photographic image of the smiling face with closed teeth (M2), measurement of the inclination of the straight lines passing through the point of intersection between the vertical line joining the pupils (P) and the superciliary ridge (horizontal glabella) and the hypothetical point (X) of interproximal contact between the upper central incisor teeth (SI 1, S21) decided by the user (Figure 14).

§ Point D is obtained by translating the line MG to point G and making it intersect the lower segment of the rectangle.

• F and curve G-F (Figures 15, 16, 17, 18, 19).

o The operation is started from the contour of the lower half of the face;

o drawing of the curve (J) that approximates the contour of the lower mandibular half-face;

o calculation of the tangent to the circumference (tangent GF) (Figure 15), obtained by translating the straight line (MG) on the tooth;

o calculation (on the photograph of the smiling face) of the inclination of line GF and translation of the same line on the distal part of the reference rectangle;

o construction of a distal triangle as follows:

§ a vertex is point G

§ a vertex (F) is the point of intersection between the straight line passing through G with inclination equal to that of the tangent to the curve of the jaw (line G-F) and the lower segment of the rectangle

§ a vertex (Fl) is the point of intersection between the straight line passing through G with inclination equal to that of the straight line MG ( menton - point G);

o finally, construction of a parabola inside the resulting triangle. • Curve C-D.

o Determination of point Dl as the point of intersection between the straight line passing through C - and having the same inclination as the line PX that joins the vertical line passing through the left pupil and the horizontal line above the superciliary ridge - and the lower segment of the rectangle (R);

o the curve is obtained with a parabola passing through C and D, inscribed in triangle C, D, D1.

• Curve D-E-F.

o Construction of an approximate curve passing through the three points D, E, F.

• Upper parabola H-A-B (Figure 20).

o It is a parabola with vertex Al, passing through HI and B.

• Curve H-G.

o Drawing of the curve approximating the lower face countour;

o the arc of a circle determines the curve H-G.

• Curve B-C.

o The circumference with double radius compared to that determined for curve H- G is considered;

o the arc of circle between the two points determines the curve B-C.

• Drawing of the shape of the central incisor tooth (Sl l) or (S21) (Figure 19).

o Draw H-A-B;

o connect G-H and B-C;

o connect G-F and C-D;

o connect D-E-F.

An approximate connection curve is used (Figure 21). The method makes it possible to approximate the points using also a manual and not only a digital technique.

Calculation of the successive teeth

The calculation of the successive teeth is based on the central incisor teeth (Sl l, S21) as points of reference, and on already known points.

The angle AFF is equal to that used for the central incisor teeth (SI 1, S21), but it is reduced according to a perspective calculation based on the distance of the observer and the curvature of the dental arch.

As an alternative, it is possible to apply a statistical percentage of reduction of the angle

AFF for each tooth.

Calculation of the right upper lateral incisor tooth fS12)

The calculation for the left upper lateral incisor tooth (S22) is the same, in reverse:

o construction of the rectangle with known width, if this is available, or calculation of the width through the golden rules. The height is arbitrary or is obtained from available data. The vertical position of the rectangle with respect to the central incisor tooth is defined in relation to the position of point C, which remains fixed;

o point C is known, as it coincides with point G of the central incisor tooth (SI 1); o point A is arbitrary but is determined according to the height;

o point B is situated on line PSL that is parallel to the smile line (1).

S12

• Creation of a rectangle as follows: (Figure 22a, 22b).

o Construction of the rectangle with known height and width, if these are available, or calculation of the width through the application of the golden rules. The height is arbitrary or is obtained from available data. The vertical position of the rectangle with respect to the central incisor tooth is defined in relation to the position of point C, which remains fixed, and B that correspond to the right upper central incisor tooth (SI 1); o the rectangle is adj acent to the rectangle S 11 ;

o A is initially positioned at the centre of the upper segment of the rectangle;

o E is initially positioned at the centre of the lower segment of the rectangle;

o C is positioned on the mesial segment, at a distance HCC (h-13%) from the upper segment.

The rectangle is positioned vertically in such a way that point C of tooth S12 (S12.C) corresponds to point G of tooth Sl l (l l .G) (two crossed data 11G and HCC). Said correspondence of the points is approximate between the two data (weighted average). The correspondence of point C of S12 and G of SI 1 makes it possible to obtain the rectangle in which tooth S12 is inscribed.

o Point B is positioned at the height corresponding to point H of Sl l, while B.x is undetermined, for the moment (Figure 24).

• Determination of point G

o Point C is located at 30% of the measure of point hcc/2 of SI 1 or S21 (Figure 25).

• Calculation of the initial points H and B (Figures 26, 27, 28).

o Modification of the previous angle AFF according to a perspective ratio (AFF12)

(perspective depends on the shape of the dental arch);

o drawing of a straight line starting from point G with angle AIF;

o drawing of the angle AFF 12 with vertex A from point A;

o the point of intersection between the line starting from G and the distal side of the angle determines the initial H;

o drawing of a vertical line from point C with angle AIF;

o the point of intersection between the line starting from C and the horizontal plane passing through B, determined by point H of SI 1 (1 l .H), determines the initial B (Figure 26).

· Adaptation of H and A to the smile line (1).

o Consider the tangent to the smile line (1) previously calculated;

o consider the horizontal plane passing through B;

o consider the intersection between the horizontaal plane passing through B and the rectangle (mesial segment) (point B l);

o drawing of a line from point Bl having the same inclination as the tangent to the smile line (smile line passing through B l);

o FT is determined by the point of intersection between the line passing through G with inclination AIF and the smile line passing through Bl; o calculation of the vertical distance between the new H and Bl (Delta);

o A' is determined by shifting A distally by Delta, on the upper segment.

• Upper parabola H-A-B.

o Repetition of the same process as that carried out for the upper parabola of the S 11.

• Curve H-G and B-C.

o Repetition of the same process for the curve of the S 11.

• Mesial embrasure: point D and curve C-D.

o Transfer of the inclination of the straight line (ND) from the subnasal point to point C from the study photograph (Figure 18): a side of the resulting triangle is thus delineated;

o transfer of the inclination of the tangent to the j aw G-F calculated for the S 11 , where said line is inverted vertically and intersects point C;

o construction of a triangle as follows: a vertex is C; the two lines mentioned above are drawn from C and the two vertices lie on the lower segment of the rectangle;

o point D is the point nearest to E (based on the tangent G-F to the j aw); the other point is called Dl;

o the parabola is inscribed in triangle C-Dl-D.

• Distal embrasure: point F and curve G-F (Figure 28).

o Transfer of the inclination of straight line MG (menton-point G);

o transfer of the inclination of the tangent G-F to the jaw calculated for the SI 1; o construction of a triangle as follows: a vertex is G; the two lines (GF, ND) mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o point F is the nearest to E (based on the tangent G-F to the j aw); the other point is called Fl;

o the parabola is inscribed in triangle G-Fl-D.

• Curve D-E-F.

o It is an approximate curve passing through the three points D, E, F. • The shape of the upper lateral incisor tooth S12 must be drawn as it has been drawn for the upper central incisor tooth S 11.

S13 iFisures 29. 30. 31. 32. 33)

• Construction of a triangle as follows:

· the rectangle height is H13C and its width is F13C (perspective correction); o it is adjacent to rectangle SI 2;

o it is positioned on the ideal smile line at the level of the canine cusp;

o E is positioned at the level of the smile line (Figure 29);

o C is positioned on the mesial segment, at the level of 12. G;

o point B is positioned at the level of point H of S12, B.x is undetermined for the moment.

• Determination of point G

o G is positioned at the distance 20% of HCC 11 from point B (Figure 30)

· Calculation of initial points H and B.

o Modification of the preceding angle AFF with perspective (AFF13) (the perspective depends on the shape of the dental arch);

o drawing of the vertical line from point G, inclined by an angle equal to AIF; o from point A, drawing of the angle AFF 13 with vertex A and two equal sides; o the point of intersection between the straight line drawn from G and the distal side of the angle determines the initial H;

o point G is in turn shifted along the line parallel to the smile line (weighted average);

o drawing of a straight line from point C with angle AIF;

o the point of intersection between the straight line drawn from C and the horizontal plane passing through B (determined by point H of S12) determines the initial B.

• Adaptation of H and A to the smile line.

o Consider the tangent to the smile line previously calculated; o consider the horizontal plane passing through B;

o consider the intersection of the horizontal plane passing through B with the rectangle (mesial segment) (point B l);

o drawing of a straight line having the same inclination as the tangent to the smile line (smile line through B 1) from point B 1 ;

o FT is determined by the intersection of the straight line passing through G with inclination AIF with the smile line passing through Bl;

o calculation of the vertical distance between the new H and Bl (Delta);

o A' is determined by shifting A by Delta distally on the upper segment.

· Upper parabola H-A-B (Figure 32).

o Repetition of the same process carried out for the upper parabola of the S 11.

• Curve H-G and B-C.

o Repetition of the same process carried out for the curve of the S 11.

• Mesial embrasure: point D and curve C-D (Figure 33).

o Consider the inclination of the subnasal line (ND) - point C;

o consider the inclination of the tangent GF to the j aw calculated for the S 11 (the line is inverted vertically);

o construction of a triangle as follows: a vertex is C; the two straight lines (ND, GF) mentioned above are drawn from point C and the two vertices are on the lower segment of the rectangle;

o point D is the nearest to E (based on the tangent G-F to the j aw); the other point is called Dl;

o the parabola is inscribed in triangle C-Dl-D.

• Distal embrasure: point F and curve G-F (Figure 33).

o Consider the inclination of the straight line MG (Menton - point G);

o drawing of a straight line with inclination equal to the inclination of the tangent

G-F to the j aw calculated for S 11 (without inverting the straight line);

o construction of a triangle as follows: a vertex is G; the two straight lines mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o the parabola is inscribed in triangle G-Fl-D.

• Curve D-E-F.

o It is an approximate curve passing through the three points D, E, F.

• The shape must be drawn as for the S 11.

In the case of asymmetrical faces, according to this method the inclination of the axis of one or more teeth is corrected, moving the zenith according to symmetry.

The procedure for the determination of the individual axial inclination for each upper front tooth (Sl l, S12, S13, S21, S22, S23) is as described below, with reference to Figures 34 and 35, considering the image of the smiling face (M2).

The following are defined:

1- Horizontal line passing through the glabella or above the superciliary ridge

2- Horizontal line passing through the lip commissures

3- Horizontal line passing through the pupils

4- Midline of the face

GC r - line joining the glabella point to the right commissure point, intersecting said horizontal line 3 passing through the pupils

GC 1 - line joining the glabella point to the left commissure point, intersecting said horizontal line 3 passing through the pupils

A r - point of intersection between said line GC r and said horizontal line 3 passing through the pupils

Al - point of intersection between the line GC 1 and the horizontal line 3 passing through the pupils.

With reference to the left side of the face, the following points are defined:

Bl - point of intersection of the vertical line starting from the caruncle at the medial canthus of the left eye with said horizontal line 3 passing through the pupils CI - point at the level of the medial iris of the left eye

D 1 - left pupil point

IM 21 - point situated on the ideal incisal edge of the left upper central incisor tooth (S21)

IM 22 - point situated on the ideal incisal edge of the left upper lateral incisor tooth (S22)

CP 23- point situated on the ideal cusp of the left upper canine tooth (S23)

CP 24 - point situated on the ideal vestibular cusp of the first right upper bicuspid tooth (S24)

AI 21 - joining line between said point Al and said point IM 21, which is angled, with generic inclination x, with respect to said vertical midline 4

AI 22 - joining line between said point Bl and said point IM 22, which is angled, with generic inclination x, with respect to said vertical midline 4

AP 23 - joining line between said point CI and said point CP 23, which is angled, with generic inclination x, with respect to said vertical midline 4

AP 24 - joining line between said point Dl and said point CP 24, which is angled, with generic inclination x, with respect to said vertical midline 4.

The procedure is identical and specular for the right side of the face.

The angle x is the individual axial inclination of each one of the front teeth of the upper jaw. In front view, the zenith of each ideal tooth must be contained within the line corresponding to the tooth.

Therefore, with reference to the above description and the attached drawings, the following claims are expressed.

Claims

1. Method for determining and drawing the ideal and customised shape of one or more of the six upper front teeth, existing or missing or genetically damaged, of a patient, characterized in that it comprises the following steps:

· use of one or more images of a front view of the patient's face and at least one image of the front teeth in occlusion (Ml, M2, M3);

• determination of at least one reference line or smile line (1) whose curvature is substantially equal to that of the patient's lower lip;

• determination of a rectangle (R) for the tooth (SI 1, S12, S13, S21, S22, S23) to be drawn, said rectangle (R) having a predefined width (RL)/ height (RH) proportion ratio;

• positioning of the base of the rectangle (R) on said reference line or smile line

(i);

• determination of n points (A, B, C, D, E, F, G, H) on the perimeter of said rectangle (R),

front facial angle (AFF), obtained by setting the vertex at the level of the septal angle;

- facial inclination angle (AIF), constructed by measuring the angle between the tangent to the face in its lower portion and a vertical line; straight line (PX) passing through a pupil and a hypothetical interproximal contact point (SI 1, S21) selected by the user;

- tangent (MG) to the approximate curve of the contour of the lower mandibular half-face,

2. Method according to claim 1, characterized in that said reference line (1) passes through the incisal edges (S3) of the upper central incisor teeth (Sl l, S21) and through the cusps (S4) of the canine teeth (S13, S23).

3. Method according to claim 1, characterized in that it can be applied when it is necessary to determine the shape of one or both of the upper central incisor teeth (Sl l, S21) and/or of one or both of the upper lateral incisor teeth (S12, S22) and/or of one or both of the upper canine teeth (S12, S23).

4. Method according to the preceding claims, characterized in that, once the shape of one of said upper central incisor teeth (Sl l) and/or of one of said upper lateral incisor teeth (SI 2) and/or of one of said upper canine teeth (SI 3) has been determined, the shape of one of said upper central incisor teeth (S21) and/or of one of said upper lateral incisor teeth (S22) and/or of one of said upper canine teeth (S23) is specular to the shape of the corresponding tooth in the opposite half arch.

5. Method according to the preceding claims, characterized in that it comprises the correction of the inclination of one or more of said upper front teeth (Sl l, S12, S13, S21, S22, S23), which is obtained by moving the zenith of said one or more teeth (Sl l, S12, S13, S21, S22, S23) according to any possible asymmetry in the patient's face.

6. Method according to the preceding claims, characterized in that it requires one or more of the following images:

· at least one photographic image of a front view of the face, with closed mouth

(Ml);

• at least one photographic image of a front view of the dental arches, in occlusion (M3);

• a photographic image of a front view of the face, smiling with the teeth in occlusion (M2).

7. Method according to the preceding claims, characterized in that it comprises the determination of the shape of at least one of the upper central incisor teeth (Sl l, S21), which is performed according to the following steps: • Positioning of the median point (E) of the base of the rectangle (R) at the level of said reference line (1).

o A is at the centre of the upper side of the rectangle (R);

o E is at the centre of the lower side of the rectangle (R);

o B is an arbitrary point on the mesial segment of the rectangle (R);

o C is on the mesial segment of the rectangle (R), at a distance HCC from the upper segment, wherein HCC is defined as the height of the clinical crown;

o G is on the distal segment of the rectangle (R), at a statistical distance from the upper segment;

o H is given by the intersection between the distal segment of the angle AFF, the straight line IF (angle AIF) and the straight line PSL parallel to said reference line (1); the angle AFF is calculated by transferring the patient's facial angle on the rectangle that has been created, positioning the apex in point A. First the facial inclination line (IF) is drawn, then the segment of angle AFF is intersected. Then the parallel line to said reference line (1) is drawn.

• Calculation of points H and B (Figure 7).

o A straight line is drawn from point G, with angle AIF;

o the angle AFF with vertex A is drawn from point A;

o the point of intersection between the line drawn from G and the distal side of the angle determines H;

o a straight line is drawn from point C, with angle AIF/2;

o the point of intersection between the line drawn from C and the mesial side of the angle determines point Bl, corrected with other successive data (Figure

11).

• Adaptation of H and A to said reference line (1).

o The inclination of the tangent to said reference line (1) is calculated;

o a straight line is drawn with origin in point Bl, having the same inclination as said tangent to said reference line (1);

o H is re-determined in HI through the intersection between the line passing through G with inclination AIF and said reference line (1) passing through B l ;

o the vertical distance between HI and B l is calculated;

o Al is determined by moving A by Delta x (Δχ) distally, on the upper segment;

o D is determined as follows: in the photographic image of the face smiling with closed teeth (M2), measurement of the inclinations of the lines passing through the point of intersection between the vertical line joining the pupils (P) and the superciliary ridge (horizontal glabella) and the hypothetical point (X) of interproximal contact between the upper central incisor teeth (S l l, S21) selected by the user.

§ Point D is obtained by translating the inclined line (MG), intersecting point G and the lower segment of the rectangle.

• F and curve G-F.

o The tangent to the circumference (tangent GF) is calculated, which is obtained by translating the line (MG) on the tooth;

o the inclination of the tangent GF is calculated on the photograph of the smiling face (M2), and the same inclination is transferred on the distal part of the reference rectangle;

o a distal triangle is then constructed, as follows:

§ a vertex is point G;

§ a vertex F is the point of intersection between the line passing through G with inclination equal to that of the tangent to the curve of the jaw (GF) and the lower segment of the rectangle;

§ a vertex Fl is the point of intersection between the line passing through G with inclination equal to that of line MG and the rectangle; o finally, a parabola is constructed inside the resulting triangle.

• Curve C-D.

o Point Dl is determined as the point of intersection between the straight

line passing through C - and having the same inclination as the line PX that joins the vertical line passing through the left pupil and the horizontal line above the superciliary ridge - and the lower segment of the rectangle (R);

o the curve is obtained with a parabola passing through C and D, inscribed in

triangle C, D, Dl .

• Curve D-E-F.

• Upper parabola H-A-B.

o It is a parabola with vertex in Al, passing through HI and B.

• Curve H-G.

o The curve is described which approximates the lower face contour;

o the arc of circumference determines curve H-G.

• Curve B-C.

o The circumference with double radius compared to that determined for curve H-G is considered;

o the arc of circumference between the two points determines curve B-C.

• The shape of the central incisor tooth (Sl l) or (S21) is drawn,

o Drawing of H-A-B;

o connection G-H and B-C;

o connection G-F and C-D;

o connection D-E-F.

8. Method according to claim 7, characterized in that it comprises the calculation of said lateral incisor teeth (S12, S22) and successively of said canine teeth (S13, S23) starting from said central incisor teeth (Sl l, S21), said calculation being made using the known points, and wherein the front facial angle (AFF) is the same as that used for the central incisor teeth (SI 1, S21), reduced compared to the front view by means of a perspective calculation based on the distance of the observer and the curvature of the arch and/or applying a statistical percentage for each tooth.

9. Method according to claim 8, characterized in that it comprises the determination of the shape of at least one of the upper lateral incisor teeth (S12, S22), which is performed according to the following steps:

o construction of the rectangle with known width, if this is available, or calculation of the width through the application of the golden rules. The height is arbitrary or obtained from available data. The vertical position of the rectangle with respect to the central incisor tooth (SI 1) is defined in relation to the position of point C that remains fixed and coincides with point G of the central incisor tooth (SI 1); o the rectangle is adj acent to the rectangle S 11 ;

o point A is arbitrary in relation to the height and is initially positioned at the centre of the upper segment of the rectangle;

o point B is situated on line PSL, which is parallel to the smile line (1);

o E is initally positioned at the centre of the lower segment of the rectangle; o C is positioned on the mesial segment, at a statistical distance from the upper segment;

o point B is positioned so that it is vertically aligned with point H of the central incisor tooth SI 1;

• Determination of point G

o point C is at 30% of the measure of point HCC/2 of the adjacent central incisor tooth (SI 1, S21);

• Calculation of initial points H and B

o Modification of the previous angle AFF with a perspective reduction (AFF 12) related to the shape of the dental arch; o starting from point G, with angle AIF, and drawing of a straight line;

o from point A, drawing of angle AFF 12 with vertex A;

o the point of intersection between the line starting from G and the distal side of the angle determines the initial point H;

o from point C, with angle AIF, drawing of a vertical straight line;

o the point of intersection between the line starting from C and the horizontal plane passing through B, determined from point H of the adjacent central incisor tooth (SI 1), determines the initial point B.

• Adaptation of H and A to the reference line (1)

o Consider the tangent to said reference line (1);

o consider the horizontal plane passing through B;

o consider the intersection between the horizontal plane passing through B and the mesial segment of the rectangle (point B l);

o draw a line from point B 1 with the same inclination as that of the tangent to said reference line (1);

o HI is determined by the intersection of the line passing through G having the same inclination as the facial inclination angle (AIF) with said reference line (1) passing through Bl;

o calculation of the vertical distance between the new H and B 1 (Delta); o Al is determined by distally shifting A by delta, on the upper segment.

• Upper parabola H-A-B

o Repetition of the same process for the upper parabola of the central incisor tooth (Sl l).

• Curve H-G and B-C

o Repetition of the same process carried out for the curve of the central incisor tooth (Sl l).

• Mesial embrasure: point D and curve C-D

o Transfer of the inclination of the line ( D) between the subnasal point and point C from the photograph of the smiling face (M2): a side of the resulting triangle is thus defined;

o transfer of the inclination of the tangent to the jaw (GF) calculated for the central incisor tooth (SI 1), wherein said line (GF) is inverted vertically and intersects point C;

o construction of a triangle as follows: a vertex is C; the two lines ( D, GF) mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o point D is the nearest to E, based on the tangent to the jaw GF; the other point is Dl;

o the parabola is inscribed in triangle C-Dl-D.

• Distal embrasure: point F and curve G-F

o Transfer of the inclination of line MG;

o transfer of the inclination of the tangent to the jaw (GF) calculated for the central incisor tooth (SI 1);

o construction of a triangle as follows: a vertex is G; the two lines mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o point F is the nearest to E, based on the tangent to the jaw (GF); the other point is Fl;

o the parabola is inscribed in triangle G-Fl-D.

• Curve D-E-F

o It is an approximate curve passing through the three points D, E, F;

• the shape of the upper lateral incisor tooth S12 must be drawn as it has been drawn for the upper central incisor tooth S 11.

10. Method according to claim 9, characterized in that it comprises the determination of the shape of at least one of the upper canine teeth (S13, S23), which is carried out as follows: • Creation of a correct rectangle according to the perspective, adjacent to the rectangle of the adjacent lateral incisor tooth (S12, S22) and positioned on said reference line (1) at the level of the canine cusp (S4).

o A is initially positioned at the centre of the upper segment of the rectangle; o E is positioned at the level of said reference line (1);

o C is positioned on the mesial segment, at the level of point G of the adjacent lateral incisor tooth (S12);

o point B is positioned at the level of point H of the adjacent lateral incisor tooth (S 12).

• Determination of point G

o G is positioned at a statistical distance from point B.

• Calculation of initial points H and B.

o Modification of the previous front facial angle (AFF) according to the perspective ratio depending on the shape of the dental arch;

o from point G, drawing of the vertical line inclined according to the facial inclination angle (AIF);

o from point A, drawing of the equilateral front facial angle with vertex A; o the point of intersection between the line drawn from G and the distal side of the angle determines the initial H;

o in its turn, point G is shifted along the line parallel to said reference line

(i);

o drawing of a line from point C, according to the facial inclination angle (AIF);

o the point of intersection between the line drawn from C and the horizontal plane passing through B, determined by point H of the adjacent lateral incisor tooth (SI 2), determines the initial point B.

• Adaptation of H and A to said reference line (1).

o Consider the tangent to said reference line (1); o consider the horizontal plane passing through B;

o consider the intersection between the horizontal plane passing through B and the mesial segment of the rectangle, defining point Bl;

o drawing of a line from point B 1 with the same inclination as that of the tangent to said reference line (1);

o HI is determined by the intersection between the line passing through G with facial inclination (AIF) and the reference line (1) passing through Bl;

o calculation of the vertical distance between the new H and B 1 (Delta); o Al is determined by distally shifting A by delta on the upper segment.

• Upper parabola H-A-B.

o Repetition of the same process carried out for the upper parabola of the central incisor tooth (SI 1).

• Curve H-G and B-C.

• Mesial embrasure: point D and curve C-D.

o The inclination of the subnasal line (ND) - point C - is considered;

o the inclination of said tangent to the jaw (GF) inverted vertically is considered;

o construction of a triangle as follows: a vertex is C; the two lines mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o point D is the one nearest to E, based on the tangent to the j aw (GF); the other point is Dl;

o the parabola is inscribed in the triangle C-Dl-D.

• Distal embrasure: point F and curve G-F.

o The inclination of line GM is considered;

o drawing of a line having the same inclination as the tangent to the jaw (GF) calculated for the central incisor tooth SI 1 without inverting the line; o construction of a triangle as follows: a vertex is G; the two lines mentioned above are drawn from C and the two vertices are on the lower segment of the rectangle;

o point F is the one nearest to E, based on the tangent to the j aw (GF); the other point is Fl;

o the parabola is inscribed in triangle G-Fl-D.

• Curve D-E-F.

o It is an approximate curve passing through the three points D, E, F.

• The shape must be drawn as it has been drawn for the central incisor tooth (Sl l).