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Burstone analysis

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cephalometric analysis

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Burstone analysis

  1. 1. Department of orthodontics Surgical Orthodontic Treatment Planning: Profile Analysis and Mandibular Surgery FRANK W. WORMS, ROBERT J. ISAACSON and T. MICHAEL SPEIDEL The Angle Orthodontics Jan 1976, Vol. 46, No. 1 (January 1976) pp. 1-25
  2. 2. • Charles J. Burstone et al (1978) developed an analysis specially designed for patients requiring Orthognathic surgery. • They used the landmarks and the measurements that can be altered by common surgical procedures. • This analysis is also called as Cephalometrics for Orthognathic Surgery (COGS)
  3. 3. • COGS system describes the horizontal and vertical positions of the facial bones by the use of constant coordinate systems as follows: • Size of the bone are represented by direct linear measurements. • Shape of the bones are represented by the angular measurements.
  4. 4. Skeletal And Dental Analysis • ☺Landmarks • Sella (S) - The center of Pituitary Fossa • Nasion (N) – The most anterior point of the nasofrontal suture in the midsagittal plane • Anterior Nasal Spine (ANS) – The anterior most midsagittal point on the tip of sharp bony process of maxilla • Subspinale (A) – The deepest midsagittal point on the concavity between Anterior Nasal Spine and Prosthion • Supramentale (B) – The deepest point in mid sagittal plane on the concavity between infradentale and pogonion
  5. 5. • Pogonion (Pg) – Most anterior mid sagittal point on the contour of the chin • Gnathion (Gn) – Constructed by bisecting the Facial plane and tangent to lower border of mandible • Menton (Me) – Most inferior point on the inferior contour of the chin • Pterygomaxillary fissure (Ptm) – The most posterior point on the anterior contour of the maxillary tuberosity
  6. 6. • Posterior Nasal Spine (PNS) – The most posterior point on the contour of the palate. • Articulare (Ar) – The intersection of sphenoid and the posterior border of the condyle • Gonion (Go) – constructed by bisecting the posterior ramal plane and mandibular plane. • Mandibular Plane (MP) – It is the line joining Gonion and Gnathion • Nasal Floor (NF) – A plane constructed by joining ANS and PNS
  7. 7. Reference plane • The base line used for comparison of most of the data in this analysis is a constructed plane called as Horizontal Plane (HP) • Most measurements in this analysis will be made either parallel to or perpendicular to this Horizontal Plane. • It is constructed by drawing a line 7⁰ from SN, intersecting at N
  8. 8. ☺Parameters Cranial Base ☺Ar-Ptm (linear) ☺Ptm-N (linear) Horizontal Skeletal Profile ☺N-A-Pg (angle) ☺N-A (linear) ☺N-B (linear) ☺N-Pg (linear) Vertical Skeletal ☺N-ANS (linear) ☺ANS-Gn (linear) ☺PNS-N (linear) ☺MP-HP (linear Vertical Dental ☺Upper 1 – NF (linear) ☺Lower 1 – MP (linear) ☺Upper 6 – NF (linear) ☺Lower 6 – MP (linear) Maxilla and Mandible ☺PNS-ANS (linear) ☺Ar-Go (linear) ☺Go-Pg (linear) ☺B-PG (linear) ☺Ar-Go-Gn (angle) Dental ☺OP-HP (angle) ☺A-B parallel to OP (linear) ☺Upper 1 – NF (angle) ☺Lower 1 – MP (angle)
  9. 9. • Cranial Base Length ☺Cranial base length is measured by measuring the distance between Ar and N ☺It is measured parallel to HP ☺The measurement Ar to N is a relatively stable anatomical plane, however it can be changed by cranial surgery ☺Le Forte II and Le Forte III surgery changes position of N ☺Autorotation of Mandible changes position of Ar
  10. 10. ☺Two measurements are considered in Cranial Base length – Ar-Ptm and Ptm-N ☺Ar-Ptm is the distance between Ar and Ptm which is measured parallel to HP ☺Standard Value ☺MALES 37.1 ± 2.8 mm ☺FEMALES 32.8 ± 1.9 mm ☺Ar-Ptm indicates the position of mandible in relation to posterior surface of maxilla
  11. 11. • ☺Ptm-N is the distance between Ptm and N which is measured parallel to HP ☺Standard Value ☺MALES 52.8 ± 4.1 mm ☺FEMALES 50.9 ± 3 mm ☺Ptm-N indicates the position of posterior border of maxilla in relation to Nasion ☺If this value increases it indicates more posterior position of maxilla in relation to N and if it decreases it indicates anterior position of maxilla in relation to N
  12. 12. Horizontal Skeletal Profile Analysis ☺A few simple measurements should be made on the skeletal profile to assess the amount of discrepancy in anteroposterior direction. ☺It is called as Horizontal Skeletal Profile analysis because all the measurements in this set of analysis are made parallel to HP
  13. 13. ANGLE OF SKELETAL CONVEXITY ☺It is the angle formed between N-A and A-Pg ☺Standard Value ☺MALES 3.9⁰ ± 6.4⁰ ☺FEMALES 2.6⁰ ± 5.1⁰ ☺A positive angle indicates convex profile while negative angle indicates concave profile
  14. 14. N Perpendicular to A, parallel to HP ☺A perpendicular to HP is dropped from N (N perpendicular) and horizontal distance parallel to HP is measured from point A ☺Standard Value ☺MALES 0 ± 3.7 mm ☺FEMALES -2 ±3.7 mm ☺This measurement describes the position of apical base of maxilla in relation to nasion
  15. 15. N Perpendicular to B, parallel to HP ☺It is obtained by measuring the distance between Point B and Nasion perpendicular (N perpendicular) ☺Standard Value ☺MALES -5.3 ± 6.7 mm ☺FEMALES -6.9± 4.3 mm ☺This measurement describes the position of apical base of mandible in relation to nasion
  16. 16. N Perpendicular to Pg, parallel to HP ☺It is obtained by measuring the distance between Pogonion and Nasion perpendicular (N perpendicular to HP) ☺Standard Value ☺MALES -4.3 ± 8.5 mm ☺FEMALES -6.5 ± 5.1 mm ☺This measurement describes the position of mandibular chin in relation to nasion
  17. 17. Vertical Skeletal Analysis ☺A Vertical skeletal discrepancy may reflect an anterior, posterior or complex dysplasia of the face ☺It is divided into two components ☺Anterior component ☺Posterior component
  18. 18. N-ANS perpendicular to HP ☺Distance between N and ANS measured perpendicular to HP gives us the Middle third facial height. ☺Standard Value ☺MALES 54.7 ± 3.2 mm ☺FEMALES 50 ± 2.4 mm ☺Any increase or decrease in this value indicates increased or decreased middle third facial height respectively
  19. 19. ANS-Gn perpendicular to HP ☺Distance between ANS and Gn measured perpendicular to HP gives us the Lower third facial height. ☺Standard Value ☺MALES 68.6 ± 3.8 mm ☺FEMALES 61.3 ± 3.3 mm ☺Any increase or decrease in this value indicates increased or decreased lower third facial height respectively
  20. 20. PNS-N, perpendicular to HP ☺Distance between PNS and HP gives us the posterior maxillary height. ☺Standard Value ☺MALES 53.9 ± 1.7 mm ☺FEMALES 50.6 ± 2.2 mm ☺Any increase or decrease in this value indicates increased or decreased posterior maxillary height respectively
  21. 21. MP – HP Angle ☺Mandibular plane angle in relation to Horizontal plane intersecting at Gn gives us posterior divergence of mandible ☺Standard Value ☺MALES 23⁰ ± 5.9⁰ ☺FEMALES 24.2⁰ ± 5⁰ ☺Any increase or decrease in value suggests increased or decreased posterior facial divergence
  22. 22. Upper 1 to platal plane ☺To obtain upper anterior dental height, perpendicular distance from incisal edge of upper incisor to palatal plane is measured ☺Standard Value ☺MALES 30.5 + 2.1 mm ☺FEMALES 27.5 + 1.7 mm ☺Any increase or decrease in this value indicates increased or decreased upper anterior dental height respectively
  23. 23. Lower 1 to MP ☺To obtain lower anterior dental height, perpendicular distance between incisal edge of lower incisor to MP is measured ☺Standard Value ☺MALES 45 ± 2.1 mm ☺FEMALES 40.8 ± 1.8 mm ☺Any increase or decrease in this value indicates increased or decreased lower anterior dental height respectively
  24. 24. Upper 6 to NF ☺To measure upper posterior dental height a perpendicular line is dropped from the tip of mesiobuccal cusp of upper first molar to palatal plane ☺Standard Value ☺MALES 26.2 ± 2.0 mm ☺FEMALES 23 ± 1.3 mm ☺Any increase or decrease in this value indicates increased or decreased upper posterior dental height respectively
  25. 25. Lower 6 to MP ☺To measure lower posterior dental height a perpendicular line is dropped from the mesiobuccal cusp of lower first molar to MP ☺Standard Value ☺MALES 35.8 + 2.6 mm ☺FEMALES 32.1 + 1.9 mm ☺Any increase or decrease in this value indicates increased or decreased lower posterior dental height respectivel
  26. 26. Maxilla and Mandible ANS to PNS ☺ANS and PNS are projected on HP ☺Distance between these two points on HP gives us total effective maxillary length ☺Standard Value ☺MALES 57.7 + 2.5 mm ☺FEMALES 52.6 + 3.5 mm
  27. 27. Ar to Go ☺Mandibular ramal length is the linear distance between Articulare and Gonion ☺Standard Value ☺MALES 52 ± 4.2 mm ☺FEMALES 46.8 ± 2.5 mm ☺Variation in Ramal length can be a causative factor for skeletal open bite or deep bite
  28. 28. Go to Pg ☺Mandibular body length is the linear distance between Gonion and Pogonion ☺Standard Value ☺MALES 83.7 ± 4.6 mm ☺FEMALES 74.3 ± 5.8 mm ☺increase in length denotes skeletal class III ☺decrease in length signifies skeletal class II
  29. 29. Ar-Go-Gn Angle (Gonial angle) ☺This measurment represents the relationship between the ramal plane and mandibular plane ☺Standard Value ☺MALES 119.1 ⁰ + 6.5 ⁰ ☺FEMALES 112⁰ + 6.9 ⁰ ☺Gonial angle also contributes to skeletal open bite or deep bite
  30. 30. Dental parameters OP-HP (Angle) ☺OP is Occlusal Plane constructed from buccal groove of first permanent molars through a point 1 mm apical to the incisal edge of the upper central incisors ☺When incisors are not in proper overbite relation, two OP are to be constructed, upper and lower and mean to be taken . ☺Standard Value ☺MALES 6.2 ⁰ ± 5.1 ⁰ ☺FEMALES 7.1 ⁰ ± 2.5 ⁰
  31. 31. ☺An increased OP-HP angle may be associated with skeletal open bite, lip incompetence and increased anterior facial height ☺An decreased OP-HP angle may be associated with skeletal deep bite, decreased anterior facial height and lip redundancy
  32. 32. A-B parallel to OP ☺ This distance is obtained by measuring the distance between projection of Point A and Point B on OP ☺Standard Value ☺MALES - 1.1 + 2.0 mm ☺FEMALES - 0.4 + 2.5 mm ☺This distance gives us relationship between maxillary and mandibular apical bases in relation to OP
  33. 33. Upper 1 to NF (Angle) ☺ This angle is constructed by intersecting a line passing through the tip of insical edge through the root tip of upper incisor and NF line ☺Standard Value ☺MALES 110 ± 4.70 ☺FEMALES 112.50 ± 5.30 ☺This angle gives us the inclination of upper incisors in relation to palatal plane (NF)
  34. 34. Lower 1 to MP (Angle) ☺ This angle is constructed by intersecting a line joining the incisal edge of lower incisor passing through its root tip and MP ☺Standard Value ☺MALES 95.9⁰ ± 5.2 ⁰ ☺FEMALES 95.9⁰ ± 5.7 ⁰ ☺This angle gives inclination of lower incisors in relation to MP
  35. 35. SOFT TISSUE ANALYSIS
  36. 36. Glabella (G) - The most prominent point in the midsagittal plane of the forehead
  37. 37. Columella point (Cm) – The most anterior point on the columella (nasal septum) of the nose
  38. 38. Subnasale (Sn) – The point at which the columella merges with the upper lip in the midsagittal plane
  39. 39. Labrale superius (Ls) - A point indicating the mucocutaneous border of the upper lip
  40. 40. Stomion superius (Stms)- The lower most point on the vermilion border of the upper lip
  41. 41. Stomion inferius (Stm i )- The upper most point on the vermilion border of the lower lip
  42. 42. Labrale inferius (Li) - A point indicating the mucocutaneous border of the lower lip
  43. 43. Soft tissue Pogonion (Pog’)- The most prominent or anterior point on the chin in midsagittal plane
  44. 44. Soft tissue Menton (Me’) – lowest point on the contour of the soft tissue chin
  45. 45. Cervical Point (C) – the innermost point between the submental area and neck
  46. 46. Soft tissue Gnathion (Gn’)- The constructed midpoint between soft tissue pogonion and soft tissue menton
  47. 47. G – Sn – Pg ( angle ) -Facial convexity / contour angle • Drop a line form Glabella ‘G’ to Subnasale ‘Sn’ and a line Sn to soft tissue pogonion ‘Pg’. • Mean value : 12 ± 4⁰ • increased +ve value - convex profile Increased -ve value - concave profile (class3 skeletal and dental relationship)
  48. 48. G - Sn - Maxillary prognathism • Drop line perpendicular to horizontal plane from Glabella. Measure the distance from perpendicular line to Sn ( parallel to HP) • Mean value: 6 ± 3 mm Inference • Describes the amount of maxillary excess/deficiency in anteroposterior dimension • +ve=maxillary prognathisum • –ve=maxillary retrognathisum
  49. 49. G - Pg - Mandibular prognathism • Drop a perpendicular line to HP from Glabella. Measure the position of the pogonion from this line parallel to HP. • Mean value: 0 +/- 4 • Increased –ve value indicated mandibal is retrognathic .
  50. 50. G-Sn / Sn-Me - Vertical height ratio • (G-Sn / Sn-Me) 1:1 • Drop a perpendicular line to HP from Glabella, to this line drop a perpendicular line to Sn and M. Measure the distance from G-Sn and Sn – Me ( all perpendicular to HP ) INFERENCE • The ratio of middle 3rd to lower 3rd facial height measured perpendicular to HP. • Ratio less than 1 = denotes disproportionality and there is large lower 3rd face and vice versa. • Disadvantages • Further evaluation of lower 3rd of face is needed
  51. 51. Sn – Gn - C - Lower face throat angle • Formed by the intersection of lines Sn-Gn & Gn-C. • Mean value:100⁰ ± 7⁰ INFERENCE • Obtuse lower face neck angle indicates that any procedures that reduce the prominence of chin should not be done
  52. 52. ( Sn – Gn / C – GN ) - Lower vertical height depth ratio. • Drop a line from Sn to Gn and C to Gn . Measure the distance from Sn – Gn and C –Gn . • Mean value : 1.2 : 1 • If the ratio is more than 1 = short neck . • Useful in determining the feasibility of reducing / increasing the chin prominence
  53. 53. LIP POSITION AND FORM • Cm – Sn - Ls - NASOLABIAL ANGLE • Draw a line from Sn to Cm and drop a line from Sn to Ls. Measure the angle formed. • Mean value : 102⁰ ± 8⁰ • Important measurement in assessing the anteroposterior maxillary dysplasias
  54. 54. • ACUTE nasolabial angle = treated by retracting the maxilla / maxillary incisors / both. • OBTUSE nasolabial angle = suggests the degree of maxillary hypoplasia and indicates for maxillary advancement or orthodontic proclination of maxillary incisors.
  55. 55. Ls To Sn - Pg --- Upper lip protrusion. • Draw a line from Sn to soft tissue Pg the amount of lip Protrusion / Retrusion is measured with perpendicular linear distance from this line to the prominent point of the lip Standard value - 3±1mm • The abnormal values can be treated by retracting or protracting the incisors , surgically or orthodontically advancing or retracting the maxilla accordingly
  56. 56. • Li to Sn-Pg -- Denotes the amount of protrusion of lower lip. • Drop a line from Sn to Pg and the amount of lip protrusion / retrusion is measured with perpendicular linear distance from this line to the most prominent point of both lips . standard value - 2±1mm • By retracting / protracting the incisors surgically / orthodontically advancing or reducing the chin prominence , possible to achieve desired lower lip
  57. 57. • Mentolabial Sulcus Depth • It is perpendicular distance between deepest point on the mentolabial sulcus to Li- Pg’ line • Standard Value 4 ± 2 mm
  58. 58. is due to : 1. Flared lower incisors. 2. Extruded upper incisors impinging on lower lip. 3. Flaccid lip tone and abnormal morphology of the lip itself . 4. Prominence of the chin also contributes to deepened mento labial sulcus TREATMENT • Up righting the lower incisors. • Intruding the maxillary incisors. • Cheiloplasty to retract lower lip – helps in reducing the MLS. • Advancement genioplasty increases the deepening of MLS. • Reduction genioplasty decreases the excess MLS
  59. 59. • ( Sn – Stms / Stmi – Me ) -- Vertical Lip Chin Ratio • To assess lower third of face . • Mean values : ( 1 : 2 ) • Lower 3rd of the face ( Sn-Me ) can be divided into three parts : length of the upper lip ( distance from Sn to Stms ) should be approximately 1/3rd the total and distance from Stmi to Me should be 2/3rd. • If the ratio becomes less than the normal ( ½ ) -- vertical reduction genioplasty is recommended
  60. 60. • Maxillary Incisor Exposure • It is obtained by measuring the distance between tip of upper central incisor and Stms • Standard Value --- 2 ± 2 mm • Increased incisor exposure may be due to vertical maxillary excess or short upper lip • Decreased incisor exposure may be due to vertical maxillary deficiency or larger upper lip
  61. 61. Inter Labial Gap • It is the distance between Stms and Stmi • Standard Value - 2 ±2 mm • Patients with vertical maxillary excess tend to have large interlabial gap and lip incompetence • Patients with vertical maxillary deficiency tend to have no Inter labial gap and Lip redundancy
  62. 62. Thank you

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