RU2438617C1 - Method of size measurement of teeth, cusps and their internal and external slopes - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely orthopedic dentistry and orthodontics, as well as anthopometry, and aims at measurement of the vestibulo-oral sizes of crowns, crown prostheses and prepared and modelled crown stumps. Two parallel straight lines are drawn on a tooth contour through "key points": one - through a point marking a central sulcus on the tooth contour, another one - directly through two points which are either apexes, or mesial/distal crests of bearing and protective cusps. It is followed by the geometrical constructions of straight lines perpendicular to the first two straight lines and passing through "key points" or tangentially to the tooth contours. The segments found between the constructed perpendicular straight lines are measured. The vestibulo-oral sizes of teeth, bearing and protective cusps, internal and external inclinations are measured; intensity of a relief and macrostructural changes of an anatomic occlusal tooth surface. Then the measured parameters are correlated.

EFFECT: method allows providing higher accuracy of preparation, controlling the tooth sizes and the relief intensity ensured by measuring tooth components and by correlating the measured parameters.

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Description

The invention relates to medicine, in particular to orthopedic dentistry and orthodontics, as well as anthropometry, and can be used to measure the vestibulooral (cheek lingual, transverse) sizes of the crown parts of the teeth, prostheses of the crown parts of the teeth and stumps of the prepared and simulated crown parts of the teeth for artificial crowns .

Currently, the problem of measuring the vestibulooral size of the crown parts of the teeth is the most relevant both in prosthetics and in dental treatment.

There is a method for assessing the height of a clinical tooth crown (US Pat. RF 2301640, А61С 13/00, published June 27, 2007), in which the aesthetically optimal height of the upper lateral incisor is calculated by measuring the width of the iris of the eye and the height of the crown on a photograph of a patient upper side incisor.

A known method of preparation of the tooth (US Pat. RF 97120905, A61C 13/36, publ. 08/27/1999), including the measurement of mesiodistal and vestibular sizes of the necks of the tooth along the depth of the gingival fissure.

The disadvantage of these methods is that they measure only one parameter, so the application is limited to a specific task.

There is a method of measuring the size of the tubercles (Khera SC, Carpenter CW, Staley RN Anatomy of cusps of posterior teeth and their fracture potential. JPD 1990 Vo1.64 # 2 pp 139-47), by which the author makes a tooth cut, receiving a series of sections passing through the tops of the hillocks and mesial, central and distal fossae. The thickness of the sections is determined by the size and type of tooth and the location of the identified anatomical formations. Tooth cuts were photographed and parameters were measured (width of the buccal and lingual tubercles, height of the tubercles, etc.). In the course of the research, information was obtained for each cut.

A known method (Zubov A.A. Odontology. Methodology of anthropological research. M .: Nauka, 1968), when measuring the size of the teeth is carried out by a compass.

The closest, according to the authors, analogue (prototype) is the method of Marxkors D., Marxkors R. Preparation of teeth for fixing crowns. New in Dentistry, 2003, No. 2, pp. 4-46. The author determines the ratio of "tubercle-fossa" and takes measurements only in the fossa, and not along the entire length of the anatomical occlusal surface, which makes it impossible to fully control the size.

The main objective of the invention is to increase the accuracy of preparation and prosthetics and control the size of the teeth and the ratios of the parts of the teeth in the vestibulooral direction, the severity of the relief and macrostructural changes in the anatomical occlusal surface of the tooth, and thereby improve the quality of treatment of orthopedic patients.

The proposed method for measuring the size of teeth, tooth bumps and their internal and external slopes involves performing geometric constructions on the tooth contour, with two parallel lines being drawn through the “key points”: one through the point that marks the central groove on the tooth contour, and the other simultaneously through two points, which are the vertices or mesial / distal crests of the support and protective tubercles, then perform geometric constructions with straight lines perpendicular to the first two straight lines and passing through the "key e points ”or in relation to the contours of the tooth, and measure the segments located between the constructed perpendicular straight lines and characterizing the vestibulooral dimensions of the teeth, supporting and protective tubercles, internal and external slopes, as well as the severity of the relief and macrostructural changes in the anatomical occlusal surface of the tooth, and then calculate the ratios measured parameters.

When implementing this method, measurements are made of the constituent elements of the teeth (tubercles, which are usually divided into vestibular and oral, buccal and lingual, supporting and protective, etc .; slopes of the hillocks, divided into internal and external, vestibular and oral, buccal and lingual and etc.), determine the severity of the relief and macrostructural changes in the anatomical occlusal surface of the tooth and calculate the ratio of the measured parameters. The control is performed on the contours of the studied objects on the planes presented in the form of a line. On the contours obtained by the intersection of the tooth with a plane passing in the vestibulooral direction, determine the "key points" (key landmarks), which produce geometric construction for measurements. The key landmarks are points that indicate the contours of the central groove of the tooth (the area of the prepared or modeled central groove) and the apex or mesial and distal ridges as the boundaries of the anatomical occlusal surface on the vestibular and oral tubercles (Fig. 1). Moreover, control is possible within the anatomical occlusal surface of the teeth and can be used to determine its parameters, parameters of dentures and the location of teeth and dentures in relation to opposite dentitions.

In the proposed method, geometric constructions are performed on the tooth contour. The contour of the tooth can be obtained, for example, using sections of a computer three-dimensional model of the tooth. In this way, you can create any number of sections, as a rule, 20 sections are enough to get the most complete picture. Straight lines are drawn through the “key points” located on the central furrow of the tooth and on the mesial and distal ridges or apices of the vestibular and oral tubercles. This makes it possible to obtain and measure the segments located between the constructed straight lines and characterizing the vestibulooral dimensions of the teeth (VORZ), supporting and protective tubercles (VOROB and VORZB), internal (VORVSOB and VORVSB) and external slopes (VORNSOB and VORNSZB), as well as the severity of macrostructures changes in the anatomical occlusal surface and calculate the ratio of the measured parameters (Fig.2, 3, 4, 5).

The use of the proposed method is of practical importance in solving research and diagnostic and clinical problems in orthopedic dentistry and orthodontics, as well as the odontometric method used in anthropology. In orthopedic dentistry, this method can be used to evaluate the prepared tooth stump, simulated tooth stump, simulated artificial crown and modeling adjustments in the manufacture of dentures.

Example 1. Measurement of the vestibulooral dimensions of the supporting and protective tubercles (VOROB and VORZB)

To obtain data on the location on the contours of tooth sections of the central sulcus, the key for odontopreparation of the occlusal surface of the landmark, the vestibulooral dimensions of OB and ST were measured using a three-dimensional computer model of the tooth. For measurements, constructions were carried out based on points that are represented on key contours of tooth sections by key landmarks for odontopreparation. These landmarks are shown in FIG. 2 by a point a corresponding to the top or crest of the supporting hillock at the cross-section, a point a 'corresponding to the top or crest of the protective hillock at the cross-section and a point b corresponding to the central groove of the tooth at the cross-section. Completed constructions: 1) line A through points a and a '; 2) line B, perpendicular to line A, through point b; 3) straight lines C and C 'perpendicular to straight line A and tangent to the contours of the external walls of the tooth or to the connection of the contours of the tooth and gums. The distance between lines B and C (segment W) is SPAR on the section. The distance between the lines B and C '(segment W') is VORZB on the section (figure 2). In the course of measurements on the constructions, the data were obtained:

1. W ₁ , W ₂ , W _{3 ...} W ₂₀ , mm - vestibulooral size OB in one section (BARB in one section).

2. w ' ₁ , w' ₂ , w ' _{3 ...} w' ₂₀ , mm - the vestibulooral size of the ST in one section (VORZB in one section).

3. n is the number of sections on one tooth (here always n = 20).

The data obtained made it possible to calculate the parameters characterizing the vestibulooral size of the teeth, the percentage of supporting and protective tubercles from VORZ, the ratio of ST and OB in the studied groups of teeth:

1. u _P1, u _{P2, P3 ...} w w _z20, mm - vestibulooralny tooth size in one section (Worth on one section)

_Z1 = w ₁ + w u _'1, u _s2 = w ₂ + w' ₂ ... _z20 w = w ₂₀ + w _'20

2. W _{% 1} , W _{% 2} , W _{% 3 ...} W _{% 20} ,% - percentage of SPAR from VORZ in one section (ANSWER in one section)

w _{% 1} = (w ₁ / w _z1 ) × 100%

3. W ' _{% 1} , W' _{% 2} , W ' _{% 3} ... W' _{% 20} ,% - percentage of SECS from SOP in one section (PVORBNPVG in one section)

w ' _{% 1} = w' ₁ / w ' _s1 × 100%

4. w _with - the ratio of the vestibulooral size of OB and SPARROW on one section (SWEAR on one section)

w _c = w / w; w _c = 1

5. W ' _s - the ratio of the vestibulooral size of BNPVG and VOROB in one section (SVORBNPVG in one section)

w ' _s = w' / w

6. W _W , mm - vestibulooral size of the tooth (VORZ)

W _H = Σ (u _P1, u _{P2, P3} ... w w _z20) / n

7. W, mm - vestibulooral size OB (SPARROW)

W = Σ (w ₁ , w ₂ , w ₃ .... w ₂₀ ) / n

8. W ', mm - vestibulooral size of the ST (VORZB)

W '= Σ (u' _1, u _'2, w' _3, ... m _'20) / n

9. W _% ,% - the percentage of vestibulo-oral size OB from VORZ (ANSWER)

W _% = Σ (w _{% 1} , w _{% 2} , w _{% 3 ...} w _{% 20} ) / n

10. W ' _% ,% - percentage of vestibulooral size of ST from VORZ (PVORZB)

W ' _% = Σ (w' _{% 1} , w ' _{% 2} , w' _{% 3 ...} w ' _{% 20} ) / n

11. W _C - the ratio of the vestibulooral size OB and SPARROW (SWEAT)

W _C = W / W; W _C = 1

12. W ' _S - the ratio of the vestibulooral size of ST and SPARROW (SVORZB)

W ' _C = W' / W

Example 2. Measurement of the vestibulooral dimensions of the inner slopes of the supporting and protective hillocks (VORVSOB and VORVSZB)

To obtain data on the location on the contours of tooth sections of the central sulcus and ridges or peaks of the supporting or protective tubercles relative to the central sulcus, which are key for odontopreparation of the occlusal surface of landmarks, we measured the vestibulooral dimensions of the internal slopes of the OB and ST using sections obtained by three-dimensional computer simulation. For measurements, constructions were carried out based on points that are represented on key contours of tooth sections by key landmarks for odontopreparation. These landmarks are shown in FIG. 3 by a point a corresponding to the top or crest of the supporting hillock at the cross-section, a point a 'corresponding to the top or crest of the protective hillock at the cross-section and a point b corresponding to the central groove of the tooth at the cross-section. To measure the vestibulooral dimensions of the internal slopes of OB and ST, the following sections are constructed at the sections: 1) line A through points a and a '; 2) line B, perpendicular to line A, through point b; 3) lines C and C 'perpendicular to line A through points a and a'. The distance between straight lines B and C (segment Шв) is VORVSOB on the section. The distance between lines B and C '(segment Шв') is VORVSZB on the section (figure 3). The constructions allowed us to obtain the following data:

1. suture ₁ , suture ₂ , suture ₃ ... suture ₂₀ , mm — vestibulooral size of the internal slopes of the support hillocks in one section (VORVSOB in one section).

2. seam ' ₁ , seam' ₂ , seam ' ₃ ... seam' ₂₀ , mm - vestibulooral size of the inner slopes of the protective hillocks in one section (VORVSZB in one section).

3. n is the number of sections on one tooth (here always n = 20) *.

The data obtained made it possible to calculate the parameters characterizing the vestibulooral dimensions of the anatomical occlusal surface of the teeth, the percentage of the internal slopes of the supporting and protective tubercles from VORVSZ, the ratio of VZZB and VSS in the studied groups of teeth:

1. Swiss _{P1, s2} CHF, CHF CHF _P3 ... _z20, mm - inner tooth vestibulooralny size skates on one section (VORVSZ on one section)

_Z1 CHF = CHF + CHF _{1 '1, s2} = CHF + CHF ₂ CHF _2' ... _z20 CHF = CHF + CHF _{20 '20}

2. seam _{% 1} , seam _{% 2} , seam _{% 3} ... seam _{% 20} ,% - percentage of vestibulooral size of the internal slopes of the support hillock from VORVSZ in one section (PVORVSOB in one section)

seam _{% 1} = (seam ₁ / seam _z1 ) × 100%

3. seam ' _{% 1} , seam' _{% 2} , seam ' _{% 3} ... seam' _{% 20} ,% - percentage of vestibulooral size of the internal slopes of the protective hillock from VORVSZ in one section (PVORVSZB in one section)

seam ' _{% 1} = (seam' ₁ / seam ' _s1 ) × 100%

4. sv _c - the ratio of the vestibulooral size of the inner slopes of the supporting hillock and VORVSOB in one section (SVORVSOB in one section)

seam _s = seam / seam; seam _s = 1

5. seam ' _s - the ratio of the vestibulooral size of the inner slopes of the protective hillock and VORVSOB in one section (SVORVSZB in one section)

seam ' _s = seam' / seam

6. Shv _Z , mm - vestibulooral size of internal tooth slopes (VORVSZ)

IIIB _Z = Σ _(P1 CHF, CHF _{P2, P3} ... CHF CHF _z20) / n

The vestibulooral size of the internal tooth slopes means the same as the vestibulooral size of the anatomical occlusal surface of the tooth: VORVSZ = VORAOP

7. Joint, mm - vestibulooral size of the internal slopes of the supporting tooth hillock (VORVSOB)

BW = Σ (BW ₁ , BW ₂ , BW _{3 ...} BW ₂₀ ) / n

8. Shv ', mm - vestibulooral size of the internal slopes of the protective tooth hillock (VORVSZB)

IIIB '= Σ (Swiss' _1, Swiss _'2, CHF _"3 ... Swiss' ₂₀₎ / n

9. Шв _% ,% - the percentage of the vestibulooral size of the internal slopes of the support hillock from VORVSZ (PVORVSOB)

BW _% = Σ (BW _{% 1} , BW _{% 2} , BW _{% 3} ... BW _{% 20} ) / n

10. Шв ' _% ,% - percentage of vestibulooral size of the internal slopes of the protective hillock from VORVSZ (PVORVSZB)

Stitch ' _% = Σ (stitch' _{% 1} , stitch ' _{% 2} , stitch' _{% 3} ... stitch ' _{% 20} ) / n

11. Shv _With - the ratio of the vestibulooral size of the inner slopes of the support hillock and VORVSOB (SVORVSOB)

Шв _С = Шв / Шв; BW _C = 1

12. Shv ' _S - the ratio of the vestibulooral size of the inner slopes of the protective hillock and VORVSOB (SVORVSZB)

Шв ' _С = Шв' / Шв

Example 3. Measurement of the vestibulooral dimensions of the outer slopes of the supporting and protective hillocks (VORNSOB and VORNSZB)

To obtain data on the location on the contours of tooth sections of ridges or vertices of supporting or protective tubercles with respect to the external walls of the teeth, which are key for odontopreparation of the occlusal surface of landmarks, the vestibulooral dimensions of the external slopes of OB and ST were measured. To carry out measurements, constructions were carried out relying on points that are represented on key contours of tooth sections by key landmarks for odontopreparation. These landmarks are shown in Fig. 4 by a point a corresponding to the top or crest of a support hillock at a section, a point a 'corresponding to a top or crest of a protective hillock at a section, and a b point corresponding to a section of a central furrow of a tooth. To measure the vestibulooral dimensions of the external slopes of OB and ST on the sections, the following constructions should be performed (Fig. 4): 1) draw a straight line A through points a and a '; 2) draw line B, perpendicular to line A, through point b; 3) from the line A, lower the perpendiculars C and C 'through the points a and a'; 4) from the straight line A, lower the perpendiculars D and D 'with respect to the outer walls of the tooth (or, if the equator could not be determined, to the junction of the contours of the tooth and gums). The distance between lines D and C (segment Шн) is VORNSOB in the section, and the distance between lines D 'and С' (segment Шн ') is VORNSB in the section. Thus, VORNSB (segment Шн - distance between lines D and C) can be represented by the difference between VORB (segment Ш - distance between lines D and В) and VORVSB (segment Шв - distance between lines B and C).

The vestibulooral dimensions of the tubercles (III) and the vestibulooral dimensions of the inner slopes of the hillocks (III) were measured on the same sections obtained by three-dimensional computer modeling, and the values of these parameters were known after performing the measurements described in the two previous examples. Based on the measured values of W and W, the values were calculated:

1. vestibulooral size of the outer slope of the supporting hillock in one section: shn = sh-shv.

2. vestibulooral size of the outer slope of the protective hillock in one section: shn '= sh'-shv'.

The following data were calculated:

1. шн ₁ , шн ₂ , шн ₃ ... шн ₂₀ , mm - vestibulooral size of the NSOB in one section (VORNSOB in one section).

2. shn ' ₁ , shn' ₂ , shn ' ₃ ... shn' ₂₀ , mm - vestibulooral size of the NSC in one section (VORNSB in one section).

3. n is the number of sections on one tooth (here always n = 20, with rare exceptions, when scanning imperfections did not allow the necessary measurements).

The data obtained made it possible to calculate the parameters characterizing the vestibulooral dimensions of the external tooth slopes, the percentage of the external slopes of the supporting and protective tubercles from VORVSZ, the ratio of the NSC and the NSC in the studied tooth groups:

1. shek _{Z1, z2} shek, shek shek _P3 ... _z20, mm - outer tooth vestibulooralny size skates on one section (VORNSZ on one section)

_Z1 = shek shek shek ₁ + ₁ ', _s2 = shek shek shek ₂ + _2' ... shek shek _z20 = ₂₀ + shek _'20

2. Шн _{% 1} , Шн _{% 2} , Шн _{% 3} ... шн _{% 20} ,% - percentage of VORNSOB from VORNSZ in one section (PVORNSOB in one section)

bn _{% 1} = (bn ₁ / bn _z1 ) × 100%

3. shn ' _{% 1} , shn' _{% 2} , shn ' _{% 3} ... shn' _{% 20} ,% - percentage of VORNSZB from VORNSZ in one section (PVORNSB in one section)

chn ' _{% 1} = (chn' ₁ / chn ' _z1 ) × 100%

4. shek _with - the ratio vestibulooralnogo size and NSOB VORNSOB on one section (SVORNSOB on one section)

shn _s = (shn / shn); shn _s = 1

5. shn ' _s - the ratio of the vestibulooral size of the NSZB and VORNSOB in one section (SVORNSB in one section)

shn ' _s = (shn' / shn)

6. Шн _З , mm - vestibulooral size of external tooth slopes (VORNSZ)

ShN _Z = Σ _(P1 shek, shek _s2, ... _P3 shek shek _z20) / n

7. Шн, mm - vestibulooral size of NSOB (VORNSOB)

Шн = Σ (шн ₁ , шн ₂ , шн ₃ ... шн ₂₀ ) / n

8. Шн ', mm - vestibulooral size of the NSZB (VORNSZB)

Shek '= Σ (shek' _1, shek _'2, shek' ₃ ... shek _'20) / n

9. Shn _% ,% - the percentage of vestibulo-oral size of the NSOB from VORNSZ (PVORNSOB)

Шн _% = Σ (Шн _{% 1} , Шн _{% 2} , Шн _{% 3} ... шн _{% 20} ) / n

10. Шн ' _% ,% - percentage of vestibulo-oral size of the NSCZ from VORNSZ (PVORNSB)

Shn ' _% = Σ (shn' _{% 1} , shn ' _{% 2} , shn' _{% 3} ... shn ' _{% 20} ) / n

11. Шн _С - ratio of vestibulooral size of NSOB and VORNSOB (SVORNSOB)

Shn _C = Shn / Shn; Shn _C = 1

12. Shn ' _S - the ratio of the vestibulooral size of the NSZB and VORNSOB (SVORNSB)

Shn ' _S = Shn' / Shn

The obtained indicators allowed us to calculate:

1. SHN _% - the percentage of vestibulooral size of the NHA from VORZ (PVORNSZ)

ШН _% = (Шн _з / Ш _з ) × 100%

2. BW _% - the percentage of vestibulooral size of the SCZ from VORZ (PVORVSZ)

BW _% = (BW _h / W _h ) × 100%

Example 4. Evaluation of the relief and the severity of macrostructural changes in the anatomical occlusal surface of the tooth.

To numerically assess the relief and the severity of macrostructural changes in the anatomical occlusal surface on the contours of the teeth, the following constructions and measurements were carried out, based on geometric constructions based on “key landmarks” (Figs. 5, 6). The measurements were carried out using a three-dimensional computer model of the tooth (20 sections). The first measurement on the tooth contour is made between two straight lines (a and b), one of which (a) connects the projections of the vertices or mesial / distal ridges of the vestibular and oral tubercles on the tooth contour (points A and A '). Line b, parallel to line a, passes through the projection of the central groove on the tooth contour (point B). The distance between lines a and b is indicated by h. Index h is the depth of the anatomical occlusal surface in the section. The second measurement was made between lines c and d, perpendicular to lines a and b. Lines c and d pass through the projections of the vertices or mesial / distal ridges of the vestibular and oral tubercles on the tooth contour (points A and A '). The distance between lines c and d is indicated by l. The exponent l is the vestibulooral size of the anatomical occlusal surface.

The indicator of the severity of the relief and macrostructural changes in the occlusal surface on the tooth contour g is the higher, the greater the indicator h and the smaller the indicator l. Thus, the exponent g is proportional to the exponent h and inversely proportional to the exponent l and can be expressed by the formula: g = h / l.

The g indices obtained on separate contours were used to calculate the severity of the relief and macrostructural changes in the occlusal surface of the tooth (indicator G). Indicator G is the arithmetic mean of macrostructural changes in each of the 20 studied tooth contours. Thus: G = Σ (g ₁ , g ₂ , g ₃ ... g ₂₀ ) / 20. Index G is both an index of the severity of the relief of the anatomical occlusal surface (IVRAOP) and an index of macrostructural changes in the anatomical occlusal surface (IIIAOP).

Claims (1)

A method for measuring the size of teeth, tooth bumps and their internal and external slopes, characterized in that two parallel lines are drawn through the “key points” on the tooth contour: one through the point that marks the central groove on the tooth contour, and the other through two points simultaneously, which are the vertices or mesial / distal ridges of the support and protective tubercles, then perform geometric constructions straight, perpendicular to the first two straight lines and passing through the “key points” or tangent to the contours of the tooth and measuring m segments disposed between constructed perpendicular lines and dimensions characterizing vestibulooralnye teeth supporting and protective hillocks internal and external rays, as well as the severity of the relief and macro-anatomical changes in the occlusal surface of the tooth, and then calculated the ratio of the measured parameters.

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