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# COGS analysis (Cephelometrics for orthognathic surgery) / fixed orthodontics courses india

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### COGS analysis (Cephelometrics for orthognathic surgery) / fixed orthodontics courses india

2. 2. contents • Introduction • Development of COGS analysis • Hard tissue analysis • A) landmarks • B ) analysis • Soft tissue analysis • A) landmarks • B ) analysis www.indiandentalacademy.com
3. 3. • Conclusion • References www.indiandentalacademy.com
4. 4. Introduction • The introduction of radiographic cephalometrics in 1934 by Hofrath in Germany and Broadbent in the United states provided both a research and a clinical tool for the study of malocclusion and underlying skeletal disproportions. • Any malocclusion is the result of an interaction between jaw position and the position the teeth assume as they erupt, which is affected by the jaw relationship. www.indiandentalacademy.com
5. 5. Cephalometric basics and errors Classification of cephalometric analysis Methodological method According to area of analysis Normative classification www.indiandentalacademy.com
6. 6. Cephalometric basics and errors Methodological Angular : Linear : Dimensional: downs Proportional: koski Orthogonal Proportional www.indiandentalacademy.com
7. 7. Angular analysis : Dimensional analysis: considers various angles in isolation,comparing them with average figures. Proportional anlaysis: comparison of various angles to establish significant relations between separate parts of the facial skeleton www.indiandentalacademy.com
8. 8. Cephalometric basics and errors Proportional linear analyses: based on relative rather than absolute values, measurements compared to each other than to norms www.indiandentalacademy.com
9. 9. Cephalometric basics and errors Normative Multinormative www.indiandentalacademy.com
10. 10. Mononormative : averages serve as norms for these. Can be arthimetic or geometric . They are suitable for group studies not for diagnostic purposes Multinormative : whole series of norms are used, along with age and sex consideration Correlative : they are used to assess individual variations of facial structure to establish their mutual relationship www.indiandentalacademy.com
11. 11. Cephalometric basics and errors Area of analysis Dentoskeletal Functional Soft tissue www.indiandentalacademy.com
12. 12. • A cephalometric analysis especially designed for the patient who requires maxillofacial surgery was developed to use landmarks and measurements that can be altered by common surgical procedures. • Because measurements are primarily linear, they may be readily applied to prediction overlays and study cast mountings and may serve as a basis for the evaluation of post treatment stability. www.indiandentalacademy.com
13. 13. • The successful treatment of the orthognathic surgical patient is dependant on careful diagnosis. • Cephalometric analysis can be an aid in the diagnosis of skeletal and dental problems and a tool for stimulating surgery and orthodontics by the use of acetate overlays. • The first step in the diagnosis of the orthognathic surgical patient is to determine the nature of dental and skeletal defects. www.indiandentalacademy.com
14. 14. • Patients who require orthognathic surgery usually have facial bones as well as tooth positions that must be modified by a combined orthodontic and surgical treatment. • For this reason, a specialized cephalometric appraisal system, called CEPHALOMETRICS FOR ORTHOGNATHIC SURGERY (COGS) was developed at The University of Connecticut. www.indiandentalacademy.com
15. 15. • The standards are based on a sample obtained from the child research council of The University of Colorado school of medicine through 16 females and 14 males. www.indiandentalacademy.com
16. 16. ADVANTAGES • The chosen landmarks and measurements can be altered by various surgical procedures. • The comprehensive appraisal includes all the facial bones and a cranial base reference. • Rectilinear measurements can be readily transferred to a study cast for mock surgery. www.indiandentalacademy.com
17. 17. • Critical facial skeletal components are examined. • A systematized approach to measurement that can be computerized is used. www.indiandentalacademy.com
18. 18. • The COGS appraisal describes • Dental, • Skeletal • Soft tissue variations. www.indiandentalacademy.com
19. 19. LAND MARKS • SELLA (S) : Centre of pituitary fossa. • NASION (N) : Most anterior point of nasofrontal suture in the midsagittal plane. • ARTICULARE (Ar): Intersection of basisphenoid and posterior border of the condyle. www.indiandentalacademy.com
20. 20. • PTERYGOMAXILLARY FISSURE (PTM) : Most posterior point on the anterior contour of maxillary tuberosity. • SUB SPINALE (A) : Deepest point in midsagital plane between ANS and Prosthion. www.indiandentalacademy.com
21. 21. • POGONION (Pg) : Most anterior point in midsagittal plane of the contour of the chin. • SUPRAMENTALE (B) : Deepest point in the midsagittal plane between Infradentale and Pg. www.indiandentalacademy.com
22. 22. • ANS : Most anterior point of nasal floor. • MENTON (Me) : Lowest point of the contour of mandibular symphysis. www.indiandentalacademy.com
23. 23. • GNATHION (Gn) : Mid point between Pg and Me. • MANDIBULAR PLANE : Plane constructed (MP) from Me to the angle of Mandible (Go) • NASAL FLOOR (NF) : Plane constructed from PNS to ANS • GONION (Go) : Located by bisecting posterior ramal plane and MPA www.indiandentalacademy.com
24. 24. Plane of Reference ( H-P line ) • A constructed plane called Horizontal Plane which is surrogate Frankfort Horizontal plane constructed by drawing a line 70 from SN plane • Most measurements will be made from projections either parallel or perpendicular to the Horizontal Plane 7° www.indiandentalacademy.com
25. 25. Cranial Base 1.Ar-N:length of the cranial base (not an absolute value, proportional,so that can be correlated with mandibular,maxillary lengths) www.indiandentalacademy.com
26. 26. 2.Ar-PTM : measure horizontal distance b/t poterior aspects of mandible & maxilla.The greater the distance,the more the mandible will lie posteriorly to maxilla Males=37.1 +/- 2 mm Females = 32.8 +/- 1.9 mm 3. PTM –N : Males = 52.8 +/- 4.1 mm females= 50.9 +/- 3.0 mm www.indiandentalacademy.com
27. 27. HORIZONTAL SKELETAL PROFILE 1. N-A-Pog=angle of skeletal facial convexity - indication of overall facial convexity measurement doesn’t indicate if due to maxilla or mandible + angle-convex face - angle –concave face Mean : Males : 3.9 +/- 0.4 ° females: 2.6 +/- 5.1 ° www.indiandentalacademy.com
28. 28. 2.N-A : • A perpendicular from HP is dropped through N. The horizontal position of A is measured to this perpendicular line ( N-A). • This measurement describes the apical base of maxilla in relation to N and enables the clinician to determine if the anterior part of maxilla is protrusive or retrusive. • Useful in planning treatment of anterior maxillary horizontal advancement or reduction, and of total maxillary horizontal advancement or reductions. • M ean : males= 0.0 +/- 3.7mm ; females = -2.0 +/- 3.7 mm www.indiandentalacademy.com
29. 29. 3.N-B : • Also measured in a plane parallel to HP from the perpendicular line dropped from N. • This measurement describes the horizontal position of the apical base of mandible in relation to N. • Useful in planning the treatment of anterior mandibular horizontal advancement or reduction and the total mandibular horizontal advancement or reduction. www.indiandentalacademy.com
30. 30. • N- POG • Measured in the same manner as N- A and N-B and indicates the prominence of the chin. • This measurement helps to determine if there is a horizontal genial hyperplasia or hypoplasia. • Useful in the planning of treatment augmentation or reduction genioplasty, of anterior mandibular horizontal advancement or reduction, and of total mandibular horizontal advancement orwww.indiandentalacademy.com
32. 32. VERTICAL SKELETAL ANALYSIS • In this analysis all measurements are made perpendicular to HP. • Reflects the anterior, posterior or complex dysplasia of face.  N-ANS(Linear)  ANS-GN(Linear)  PNS-N(Linear)  MP-HP(Angle) www.indiandentalacademy.com
33. 33. Helps in Diagnosis of: • anterior , posterior or total vertical maxillary hyperplasia or hypoplasia. • clockwise or counterclockwise rotations of maxilla and the mandible. www.indiandentalacademy.com
34. 34. N-ANS(LINEAR) • It signifies the middle third facial height. • Male – 54.7 +/- 3.2 • Female – 50 +/- 2.4 www.indiandentalacademy.com
35. 35. Measurements of N-ANS www.indiandentalacademy.com
36. 36. ANS-GN(LINEAR) • It signifies the lower third facial height. • Male – 68.6 +/- 3.8 • Female – 61.3 +/- 3.3 www.indiandentalacademy.com
37. 37. PNS-N(LINEAR) • It signifies the posterior maxillary height • Male – 53.9 +/- 1.7 • Female – 50.6 +/- 2.2 www.indiandentalacademy.com
38. 38. Measurements of PNS-N www.indiandentalacademy.com
39. 39. MP-HP(ANGLE) • It signifies the posterior divergence of mandible shown by MP angle. • The angle relates the posterior facial divergence with respect to anterior facial height • Male - 23o +/- 5.9o • Female – 24.2o +/- 5o www.indiandentalacademy.com
40. 40. Construction of MP-HP www.indiandentalacademy.com
42. 42. MAXILLA AND MANDIBLE ANALYSIS • This is analysed by following measures PNS – ANS AR – GO GO - PG AR-GO-GN B - PG www.indiandentalacademy.com
43. 43. PNS-ANS MEASUREMENTS • Denotes the total effective length of maxilla. • Male - 57.7 +/- 2.5 • Female – 52.6 +/- 3.5 www.indiandentalacademy.com
44. 44. Measurements of PNS-ANS www.indiandentalacademy.com
45. 45. Ar-Go linear) • Quantitates the length of mandibular ramus • Male - 52 +/- 4.2 • Female – 46.8 +/- 2.5 www.indiandentalacademy.com
46. 46. GO-PG(LINEAR) • Aids in establishing the length of mandibular body • Male – 83.7 +/- 4.6 • Female – 74.3 +/- 5.8 www.indiandentalacademy.com
47. 47. B-POG • This measurements denotes prominence of chin related to mandibular denture base • Male - 8.9 +/- 1.7 • Female – 7.2 +/- 1.9 www.indiandentalacademy.com
48. 48. AR-GO-GN(ANGLE) • This angle denotes relationship between ramal plane and MP. • Aids in diagnosis of skeletal open/closed bite problems. • Male – 119.1o +/- 6.5o Female – 122o +/- 6.9o www.indiandentalacademy.com
49. 49. Maxilla and Mandible www.indiandentalacademy.com
50. 50. VERTICAL DENTAL ANALYSIS • Measurements for this analysis UI perpendicular to NF LI perpendicular to MP U6 perpendicular to NF L6 perpendicular to MP www.indiandentalacademy.com
51. 51. UI TO NF • It denotes the anterior maxillary dental height. • Aids to evaluate the total vertical dimensions of premaxilla from approximate piriform aperture perpendicular to tip of maxillary incisor crown. • Signifance: indicates how far the incisor have erupted in relation to nasal floor. • Male - 30.5 +/- 2.1 • Female – 27.5 +/- 1.7 www.indiandentalacademy.com
52. 52. LI TO MP • This measures the anterior mandibular dental height. • Determines the total dmensions of anterior mandible from MP perpendicular to tip of mandibular incisor crown. • Signifance: denotes how far the incisor have erupted in relation to MP • Male - 45 +/- 2.1 • Female – 40.8 +/- 1.8 www.indiandentalacademy.com
53. 53. U6 TO NF • This measures the posterior maxillary dental height. • Aids to evaluate the posterior dental mandibular vertical height/molar eruption • Male - 26.2 +/- 2 • Female – 23 +/- 1.3 www.indiandentalacademy.com
54. 54. L6 TO MP • Measures the posterior mandibular dental height • Male - 35.8 +/- 2.6 • Female – 32.1 +/- 1.9 www.indiandentalacademy.com
55. 55. OP-HP(ANGLE) • OP denotes its steepeness/flatness • Increased angle: assess skeletal open bite, lip incompetence,increased facial height, retrognathia. • Decreased angle: assess deep bite, decreased facial height, lip redundancy. • Male - 6.2o +/- 5.1o • Female – 7.1o +/-2.5o www.indiandentalacademy.com
56. 56. IN CASE OF ANTERIOR OPEN BITE www.indiandentalacademy.com
57. 57. Measurements of OP-HP ANGLE www.indiandentalacademy.com
58. 58. A-B(LINEAR) • This linear measurements represents the relationship of maxillary and mandibular apical base to OP • Male - -1.1 +/- 2 • Female - -0.4 +/- 2.5 • Significance: if A-B distance is large with point B projected posteriorly to point A denotes class II occlusion and vice versa www.indiandentalacademy.com
59. 59. U1 – NF(ANGLE) • Represents angulations of maxillary central incisors to NF • Male - 111o +/- 4.7o • Female – 112o +/- 5.3o • Signifance: aids to determine the procumbency/recumbency of incisor • Vitals in assessing long term stability pf dentition www.indiandentalacademy.com
60. 60. LI – MP(ANGLE) • Denotes angulation of mandibular incisors to MP • Male - 95.9o +/- 5.2o • Female – 95.9o +/-5.7o • Significance: determines the procumbency/recumbency of lower incisor. www.indiandentalacademy.com
62. 62. Soft tissue analysis www.indiandentalacademy.com
63. 63. TRACINGS AND LANDMARK www.indiandentalacademy.com
64. 64. FACIAL FORMS ANALYSIS This analysis describes overall horizontal soft tissue profile. The following analysis is used:  Facial convexity angle(G-Sn-Pg)  Maxillary prognathism(G-Sn)  Mandibular prognathism(G-Pg)  Vertical height ratio(G-Sn/Sn-Me)  Lower face throat angle(Sn-Gn-C)  Lower vertical height depth ratio(Sn-Gn/C-Gn) www.indiandentalacademy.com
65. 65. FACIAL CONTOUR ANGLE www.indiandentalacademy.com
66. 66. FACIAL CONTOUR ANGLE INFERENCE • Mean value 12o +/- 4o • +ve value indicates a convex profile • -ve value indicates concave profile www.indiandentalacademy.com
67. 67. MAXILLARY PROGNATHISM(G-Sn) • Describes the amount of maxillary excess/deficiency in AP • +ve - maxillary retrusion • -ve - maxillary procumbency • Mean value 6+/-3 www.indiandentalacademy.com
68. 68. MANDIBULAR PROGNATHISM(G-Pg) • Mean value 0 +/- 4 Inference : • Indicates mandibular prognathism/ retrognathism • Increase –ve value indicates mandibular deficiency www.indiandentalacademy.com
69. 69. Vertical Height Ratio (G-Sn/Sn- Me I HP) • In the vertical dimension, the anterior facial proportionality is assesed by taking the ratio of middle-third facial height to lower-third facial height measured perpendicular to HP. • The ratio must be approximately 1:1 www.indiandentalacademy.com
70. 70. • A ratio of less than one would connote a disproportionately larger lower third of the face. • A vertical maxillary excess, vertical macrogenia, or a combination of these deformities can be assesed. www.indiandentalacademy.com
71. 71. Lower Face-Throat Angle (Sn-Gn’-C) • It is formed by the intersection of the lines Sn-Gn’ and Gn’-C. • An application of this angle is critical in planning treatment to correct anteroposterior facial dysplasias. • Mean- 100+7 www.indiandentalacademy.com
72. 72. • Lower Vertical Height- Depth Ratio • Sn-Gn’/C-Gn’ • Is useful in determining the feasibility of reducing or increasing the prominence of chin. • Mean-1:2 www.indiandentalacademy.com
73. 73. • The ratio of the distances subnasale to gnathion and cervical point to gnathion is normally a little larger than 1. • In other words, if this ratio becomes much larger than 1, the patient has a relatively short neck, and the anterior projection of the chin should not be reduced. www.indiandentalacademy.com
74. 74. • An obtuse angle should warn the clinician not to use those procedures which will reduce the chin prominence. • Class III patients who have short, heavy throats and an obtuse lower face-throat angles should not have mandibular set backs. www.indiandentalacademy.com
75. 75. • Alternatives such as maxillary advancement, a mandibular subapical surgery, mandibular setback with advancement genioplasty. • Compromised tooth position can also be attempted. www.indiandentalacademy.com
76. 76. Lip Position and Form • Nasolabial Angle (Cm-Sn-Ls) • Is an important measurement in assessing anteroposterior maxillary dysplasias. • Although the angle takes into account the inclination of the nose, it is useful in evaluating the position of the upper lip. www.indiandentalacademy.com
77. 77. • Mean- 102+8 • An acute nasolabial angle will often alow us to surgically retract the maxilla or retract the maxillary incisors, or both. • An obtuse angle suggests a degree of maxillary hypoplasia and calls for a maxillary advancement or orthodontic proclination of maxillary incisors. www.indiandentalacademy.com
78. 78. • Anteroposterior Lip Position • Is evaluated by drawing a line from subnasale to soft tissue pogonion. • The amount of lip protrusion or retrusion is measured as a perpendicular linear distance from this line to the most prominent point of both lips. www.indiandentalacademy.com
79. 79. • Upper Lip Protrusion {Ls to (Sn-Pg’)} • Mean - 3+1mm • Lower Lip Protrusion {Li to (Sn-Pg’)} • Mean – 2+1mm • Retracting or protracting the incisors surgically or orthodontically or advancing or reducing the prominence of chin, or both, can achieve concordant lip position. www.indiandentalacademy.com
80. 80. Mento-Labial Sulcus { Sl to (Li-pg’)} • Measured from the depth of sulcus perpendicular to the Li- Pg’ line. • A sulcus of 4mm is average in providing a pleasing lower lip to chin contour. • Mean – 4+2mm www.indiandentalacademy.com
81. 81. • Factors that can affect the lower lip inclination and deepen the mentolabial sulcus. • Flared lower incisors. • Extruded upper incisors. • Flaccid lower lip tone. • Abnormal morphology of the lip. www.indiandentalacademy.com
82. 82. • To Reduce a deep Mentolabial Sulcus. • Upright the lower incisors. • Intrude the maxillary incisors. • Cheiloplasty to retract the lower lip. • Bony Chin. ( Can affect the depth of sulcus) • Advancement Genioplasty will deepen and Reduction Genioplasty will aid in reducing excessive sulcular depth. www.indiandentalacademy.com
83. 83. • Vertical Lip-Chin ratio. Sn-Stms/Stmi-Me’ (HP) • The lower third of the face (Sn- Me’) can be divided into thirds; the length of the upper lip, or Sn-Stms should be approximately one third the total. www.indiandentalacademy.com
84. 84. • The distance Stmi-me’ should be about two thirds. • In other words, the ratio should be 1:2. • When this ratio becomes smaller than one half, often a vertical reduction genioplasty should be considered. www.indiandentalacademy.com
85. 85. • Maxillary Incisor Exposure (Stms-1) • A Key factor in determining the vertical position of maxilla. • 2mm of maxillary incisor exposure with the lips at rest is desirable. • This will also correspond in general with a pleasing smile. www.indiandentalacademy.com
86. 86. • Patients with vertical maxillary excess tend to show a large amount of upper incisor with lips in repose. • The patients that show an excess exposure of tooth may just have a short upper lip also. So, Treatment approach should be accordingly planned. www.indiandentalacademy.com
87. 87. • Treatment modalities orthodontically is to establish a large curve of spee. • Conversely, patients with a long face that also have open bites may have an acceptable tooth-to-lip relationship but may need superior repositioning of the posterior portion of the maxilla. www.indiandentalacademy.com
88. 88. • Patients with vertical maxillary deficiency tend not to show maxillary teeth with lips relaxed and may have incisors at a level superior to the upper lip, giving an edentulous look. • Orthodontically, extruding the maxillary teeth or surgically positioning the maxilla inferiorly will be a useful treatment approach. www.indiandentalacademy.com
89. 89. • Interlabial Gap {Stms-stmi (HP)} • Vertical distance between the upper lip to the lower lip in repose, has been shown by Burstone to be fairly ideal at a range of from just lightly touching to approximately 3mm apart. • Mean – 2+2mm www.indiandentalacademy.com
90. 90. CONCLUSION • A thorough knowledge about Burstone analysis will definitely help the orthodontist and the maxillofacial surgeon in successfully treating orthognathic surgery patients and in establishing an esthetic, harmonious and stable relationship of the cranial base, jaws and teeth. www.indiandentalacademy.com
91. 91. References • RADIOGRAPHIC CEPHALOMETRY- ALEXANDER JACOBSON. • ORTHODONTIC CEPHALOMETRY- ATHANASIOS E. ATHANASIOU. • FACIAL AND DENTAL PLANNING FOR ORTHODONTISTS AND ORAL SURGEONS – ARNETTE – MCLAUGHLIN www.indiandentalacademy.com
92. 92. • Charles J Burstone , cephalometrics for orthognathic surgery ; Journal Of Oral Surgery vol36, April 1978. • Legan HL, Burstone CJ. Soft tissue cephalometric analysis for orhtognathic surgery. J Oral Surg 1980: 38 : 81-87. www.indiandentalacademy.com