BURSTONE ANALYSIS : C.O.G.S ( HARD & SOFT TISSUE)

CEPHALOMETRICS FOR ORTHOGNATHIC SURGERY

1. PRESENTED BY – Dr. Firdosh Rozy BURSTONE HARD & SOFT TISSUE ANALYSIS

2. CONTENTS : Background history and philosophy The Analysis References HARD TISSUE ANALYSIS SOFT TISSUE ANALYSIS

3. CHARLES J. BURSTONE Charles J. Burstone   (April 4, 1928 February 11, 2015) He was an American  orthodontist  who was notable for his contributions to biomechanics and force-systems in the field of orthodontics. He wrote more than 200 articles in scientific fields. BACKGROUND HISTORY & PHILOSOPHY:

4. Harry L. Legan  Dr.  Legan  is an internationally recognized  orthodontic  expert on diagnosis and treatment planning, obstructive sleep apnea, orthognathic surgery, biomechanics, and distraction osteogenesis.

5. Charles J. Burstone et al (1978, 1980) 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) Burstone and Legan in their 1980 proposed a paper for constructed horizontal line. This line is drawn through  nasion  at an angle of 7 degrees to the SN line. They developed this line because of reliability issues with the SN line when one can easily place the Sella point up/down which can change the cephalometric measurements

6. Horizontal plane 7º to SN plane Burstone CJ et al Cephalometrics for orthognathic surgery, J Oral Surg . 1978 Apr ; 36(4):269-77. HORIZONTAL PLANE SUBSTITUTED S-N PLANE:

7. ANALYSIS (COGS) :

8. 1.

9. Ar – Ptm linear 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

10. Ptm – N linear 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.

11. 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 2.

12. N-A- Pog (Angle) 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

13. N-A (Linear) 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

14. N-B (Linear) 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

15. N- Pog (Linear) 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

16. 3. A Vertical skeletal discrepancy may reflect an anterior, posterior or complex dysplasia of the face .

17. N- ANS (Linear) 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

18. ANS - Gn(Linear) 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

19. PNS -N(Linear) 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

20. MP-HP(Angular) 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

21. 4.

22. U-1 to PP(Linear) 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. L–1 to MP(Linear) 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. U-6 to PP(Linear) 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. L-6 to MP(Linear) 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 respectively.

26. 5.

27. PNS-ANS 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

28. Ar-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

29. Go-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

30. B-Pg This measurement describes the prominence of chin in relation to mandibular apical base. It is obtained by measuring the distance b/w point B and a perpendicular to mandibular plane passing through Pg. Standard Value MALES 8.9 ± 1.7 mm FEMALES 7.2 ± 1.9 mm

31. Ar-Go-Gn 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.

32. 6.

33. 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 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.

34. A-B || to OP (Linear) 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.

35. U-1 to PP (Angul ar) 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.

36. L-1 to MP ( Angul ar) 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

37. SOFT TISSUE (COGS) :

38. LANDMARKS IN SOFT TISSUE (COGS) : Glabella (G) The most prominent point in the midsagittal plane of the forehead.

39. Columella point (Cm) The most anterior point on the columella (nasal septum) of the nose.

40. Subnasale ( Sn ) The point at which the columella merges with the upper lip in the midsagittal plane.

41. Labrale superius (Ls) A point indicating the mucocutaneous border of the upper lip

42. Stomion superius ( Stms ) The lower most point on the vermilion border of the upper lip.

43. Stomion inferius ( Stm i ) The upper most point on the vermilion border of the lower lip.

44. Labrale inferius (Li) A point indicating the mucocutaneous border of the lower lip.

45. Soft tissue Pogonion ( Pog ’) The most prominent or anterior point on the chin in midsagittal plane.

46. Soft tissue Menton (Me’) lowest point on the contour of the soft tissue chin.

47. Cervical Point (C) The innermost point between the submental area and neck.

48. Soft tissue Gnathion (Gn’) The constructed midpoint between soft tissue pogonion and soft tissue menton .

49. Sn -Gn-C Angle Sn -Gn/C-Gn FACIAL FORM

50. Facial Convexity Angle G- Sn -Pg 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)

51. MAXILLARY PROGNATHISM G- Sn Drop line perpendicular to horizontal plane from Glabella. Measure the distance from perpendicular line to Sn ( parallel to HP) Mean value: 6 ± 3 mm Describes the amount of maxillary excess/deficiency in anteroposterior dimension. +ve=maxillary prognathism. –ve=maxillary retrognathism.

52. MANDIBULAR PROGNATHISM G-Pg 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 indicate mandible is retrognathic .

53. VERTICAL HEIGHT RATIO G- Sn / Sn -M 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 ) 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.

54. LOWER FACE THROAT ANGLE Sn -Gn-C Angle Formed by the intersection of lines Sn -Gn & Gn-C . Mean value:100 ⁰ ± 7⁰ INFERENCE Obtuse lower face neck angle indicates that any procedures that reduce the prominence of chin should not be done.

55. LOWER VERTICAL HEIGHT DEPTH RATIO Sn -Gn/C-Gn 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.

56. LIP POSITION & FORM Sn-StmS / Sn-StmI StmS - U1 INTER- LABIALGAP

57. NASOLABIAL ANGLE Cm- Sn -Ls Angle 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 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.

58. UPPER LIP PROTUSION Ls to Sn -Pg (Linear) 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.

59. LOWER LIP PROTUSION Li to Sn -Pg linear 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.

60. MENTOLABIAL SULCUS DEPTH Si to Sn -Pg It is perpendicular distance between deepest point on the mentolabial sulcus to LiPg ’ line. Standard Value 4 ± 2 mm

61. VERTICAL LIP CHIN RATIO Sn-StmS/ Sn-StmI 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.

62. MAXILLARY INCISOR EXPOSURE StmS - U1 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.

63. INTER- LABIALGAP 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 .

64. HARD TISSUE

65. SOFT TISSUE

66. REFERENCES : Radiographic Cephalometry – Alexander Jacobson Charles J. Burstone, H. Legan et al –Ceph alometrics for orthognathic surgery, J Oral Surgery, 1978, vol 36; 269-277 Charles J. Burstone, H. Legan- Soft tissue cephalometric analysis for orthognathic surgery 1980, J Oral Surgery, 198, vol 38;744-750

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