Surgical analysis1 /certified fixed orthodontic courses by Indian dental academy


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Surgical analysis1 /certified fixed orthodontic courses by Indian dental academy

  1. 1. SURGICAL ANALYSIS INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. INTRODUCTION     Cephalometric analysis is the common language for orthodontists & oral surgeon. Used in – Diagnosis of skeletal and soft tissue problems. Establishing proper tooth jaw relations. Determining the method & magnitude of surgical correction.
  4. 4.   Successful treatment of the orthognatic surgical patient is dependent on careful diagnosis. Cephalometric analysis can be an aid in diagnosis of skeletal and dental problems.
  5. 5. CEPHALOMETRICS FOR ORTHOGNATHIC SURGERY  Developed at the university of Connecticut, based on system developed at Indiana university by Charles J . Burstone.  Describes the horizontal & vertical position of facial bones by use of constant coordinate system.  Size of bones represented by direct linear measurements.  Shape of bones – angular measurements.  Sample – 16 females, 14 males.
  6. 6.       Following characteristics – 1 Chosen landmarks & measurements can be altered by various surgical procedure. 2 Includes all of facial bones & cranial base. 3 Critical facial skeleton components are examined. 4 Standards are available for variations in age & sex from 5 – 20 yrs. 5 Describes dental, skeletal & soft tissue variations.
  7. 7.       Landmarks used – Sella, Nasion. Articulare, PTM. Point A , B. Pogonion,Menton,Gnathion,Gonion ANS, PNS. Planes – Mandibular plane – From Me to Go. Nasal floor – From PNS – ANS.
  8. 8. MEASUREMENTS      CRANIAL BASE – Baseline for comparison of most data in this analysis is HORIZONTAL PLANE. Constructed plane , 7˚from SN line. Most measurements are made either parallel or perpendicular to horizontal plane. Length of cranial base – Parallel to HP from Ar – N. Should not be considered as absolute value, but a skeletal baseline to be correlated to other measurements.
  9. 9.
  10. 10.  Patient with large maxilla & mandible may have a normal appearance because of large cranial base.  Ar – N is a stable anatomical plane; it can be changed by cranial surgery that affects N, such as Lefort II & III osteotomies.
  11. 11.  Ar – Ptm determines the horizontal distance between the posterior asoects of mandible & maxilla.  Greater the distance between Ar- Ptm, more the mandible will lie posterior to maxilla, assuming all other facial dimensions are normal.
  12. 12. HORIZONTAL SKELETAL PROFILE  Angle of facial convexity : formed by line N – A and A-Pg.  Gives an indication of overall facial convexity, but not a specific diagnosis of which is at fault – maxilla or mandible.
  13. 13.      Positive angle – convex face. Negative angle – concave face. Clockwise angle is positive. Counterclockwise is negative. Next a perpendicular line from HP is dropped through nasion.
  14. 14.     Inferior anatomic point is horizontally measured in relation to sup. Structure , + - anterior to line. ̶ : posterior to line. Measure the horizontal position of point A & B is measured to this line. ( N-A, N-B).
  15. 15.    It describes the apical base of maxilla/mandible in relation to N. Surgeon has a quantitative assessment of A-P position of jaws and degree of horizontal dysplasia. Measurement & related measurements are imp. In planning of treatment of anterior horizontal advancement / reduction or total advancement / reduction.
  16. 16. N – Pg is measured in same manner. Indicates the prominence of chin. Any unusual small or large value must be compared with N – B & B – Pg., to determine if discrepancy is in alveolar process, the chin or mandible proper. Helps to determine if there is a horizontal genial hyperplasia / hypoplasia. 
  17. 17.  The measurements of horizontal skeletal profile represent facial convexity, horizontal relation of apical base A & B points, and chin as related to N.  After all the measurements are considered .the surgeon has a quantitative skeletal cephalometric facial description of horizontal anterior facial discrepancy.
  18. 18. VERTICAL SKELETAL MEASUREMENTS.  Divided into – Anterior & Posterior components. Anterior component – a) Middle third face height (N-ANS). b) Lower third face height (ANS-Gn). Measured perpendicular to HP. 
  19. 19.    Posterior component – a) Posterior maxillary height is length of a perpendicular line from HP intersecting PNS. b) Divergence of mandible posteriorly is shown by MPHP angle.MP is formed by Go-Gn. It relates to posterior facial divergence with respect to anterior facial height.
  20. 20.  Vertical skeletal measurements of anterior & posterior components of face will help in diagnosis of anterior , posterior , or total vertical maxillary hyperplasia or hypoplasia, and clockwise or counterclockwise rotations of the maxilla & mandible.
  21. 21. MAXILLA AND MANDIBLE   Effective length of maxilla is distance from PNS-ANS. This distance along with measurements N- ANS, N – PNS gives a quantitative description of maxilla in skull complex.
  22. 22. MANDIBLE – 1) Ar-Go quantitates the length of mandibular ramus. 2) Go-Pg gives length of mandibular body. 3) Ar-Go-Gn angle gives relation between ramal plane & mandibular plane. 4) B-Pg describes the prominence of chin related to mandibular denture base. This can be related to N – Pg to assess prominence of chin to face. 
  23. 23.     These measurements are helpful in diagnosis of variations in ramus ht., that effect open bite/deep bite problems, increased /diminished mandibular body length, acute or obtuse Go angle that also contribute to skeletal open/closed bite. Assessment of chin prominence.
  24. 24. DENTAL MEASUREMENTS First thing done is to relate the teeth to each other through a common plane such as occlusal plane,or to a plane in each jaw , MP or NF plane.  Occlusal plane (OP) is drawn from buccal groove of both permanent 1st molars through a point 1mm apical of incisal edge of central incisors in respective arch.  If anterior open bite is present 2 OPs must be drawn and measured separately. Each OP is assessed as to its steepness or flatness. Vertical facial & dental heights should be considered to determine which OP should be corrected. 
  25. 25.  OP angle is angle between OP and HP.  INCREASED – Skeletal open bite, lip incompetence, increased facial height, retrognathia or increased MP angle.  DECREASED – Deep bite, decreased facial height, lip redundancy.
  26. 26.   Measurement AB – OP is done by dropping a perpendicular line to OP from points A & B, then measuring distance between two intersections. It gives relation of maxillary & mandibular apical base to OP.
  27. 27.   Angulation of maxillary incisor to NF and mandibular incisor to MP is measured. They determine the procumbency or recumbency of incisor & are vital in assessing the long term stability of the dentition.
  28. 28. VERTICAL DENTAL DYSPLASIA  Divided into – a) Anterior b) Posterior  Anterior – Anterior maxillary height is measured by dropping a perpendicular from incisal edge to NF. Anterior mandibular height – incisal edge to MP. These 2 measurements determine how far incisors have erupted in relation to NF and MP.  
  29. 29.  POSTERIOR – a) From maxillary 1st molar m-b cusp a perpendicular line is drawn to NF. b) Similar line from mandibular m-b cusp to MP. All these values should be related to ANS-Gn & MPHP to establish whether the origin of maxillary & mandibular discrepancies is skeletal,dental or both.
  30. 30.
  31. 31. Soft tissue analysis for orthognathic surgery    Treatment planning – Hard & Soft tissues. Although hard tissue analysis show the nature of existing skeletal discrepancy,it is incomplete in providing information concerning facial form & proportion of patient ,& in many instances may be misleading. Patients may appear more or less convex than indicated by their hard tissue because of differences in thickness of soft tissues.
  32. 32.      Lips – more protrusive / retrusive. In planning surgery on patients with vertical discrepancies, lip length is an important factor to be considered. Developed by Burstone in 1958. Means & standard deviation derived from 40 orthodontically untreated white adults (20 men, 20 women). Class I occlusion, Vertical facial proportions within normal limits.
  33. 33. Landmarks
  34. 34.
  35. 35.     Facial convexity – given by angle G – Sn – Pg’. Smaller value – Class III profile. Clockwise angle – Positive. Counterclockwise angle – Negative.
  36. 36.  Maxilla & mandibular are related to a line dropped from glabella perpendicular to HP.  Maxillary – Distance to subnasale from this line. Gives amount of maxillary excess or deficiency in A-P dimension. Anterior to line – Positive, Posterior - negative  
  37. 37.  This & other related A-P measurements are important in planning treatment for anterior maxillary advancement or reduction and for total alveolar or lefort I maxillary horizontal advancement or reduction.
  38. 38.   Mandible – distance from perpendicular line dropped from glabella to Pg’. Gives an indication of mandibular prognathism or retrognathism.
  39. 39. Lower face throat angle (Sn – Gn’ –C)    Formed by intersection of lines Sn-Gn’ & Gn’-C. Critical in planning treatment to correct A-P dysplasias. In case of obtuse angle, clinicians should not use procedure that reduce prominence of chin.
  40. 40.   Class III patients with short ,heavy throats & obtuse angle usually not have mandibular setbacks. Alternatives – maxillary advancement, mandibular subapical procedure, mandibular setback with advancement genioplasty, compromise tooth position.
  41. 41.    Lower face vertical height to depth ratio – Sn – Gn’/C – Gn’. Normally a little larger than 1. if becomes more, means patient has a short neck. Anterior projection of chin should not be reduced.
  42. 42.  Vertical – ratio of distances G – Sn & Sn – Me’ should be approx. 1.
  43. 43. Lip position     Nasolabial angle – between Cm-Sn-Ls. Important measurement in A-P maxillary dysplasias. Acute angle allow us to surgically retact maxilla or maxillary incisors or both. Obtuse angle – maxillary advancementor proclination of incisors.
  44. 44.  A-P lip position – line is drawn from Sn-Pg’ & amount of lip protrusion or retrusion is measure as perpendicular linear distance from this line to most prominent point of both lips.
  45. 45.    Labiomental sulcus – from depth of sulcus perpendicular to Li-Pg’ line. Sulcus of about 4mm provides pleasing lower lip to chin contour. Uprighting lower incisors,intruding maxillary incisors,chelioplasty can help in reducing a deep sulcus.
  46. 46.    Distance of upper lip to maxillary incisor (Stm – 1) is a key factor in determining vertical position of maxilla. Normal – 2mm of incisor display. Patients with vertical maxillary excess tend to show a large amount of upper incisor with lips in repose.
  47. 47.     Vertical maxillary deficiency – No incisor display with lips relaxed, edentulous look. Orthodontically extruding maxillary teeth or surgically positioning the maxilla inferiorly – preferable treatment in patients with short face. INTERLABIAL GAP – Approx. 3mm . Patients with maxillary excess have large interlabial gaps & lip incompetency.
  48. 48.  Raising maxilla – shortens facial height, allow patient to close lips without muscle strain.  Patient with maxillary deficiency – no interlabial gap, have lip redundancy with a rolling out of upper & lower lips.
  49. 49.  Lower third of face (Sn-Me’) – divided into thirds.  Length of upper lip (Snstm)is one third he total distance of sn-Me’.  Stm-Me’ is about two thirds.  Sn-stm/stm-Me’ is 1:2  When it becomes smaller than half vertical reduction genioplasty is considered.
  50. 50.
  51. 51. QUADRILATERAL ANALYSIS     Formulated by Di Paolo in 1962. It attempts to identify skeletal deviations, in size and position, in both the horizontal and the vertical dimensions, regardless of dentoalveolar relationships. It provides an individualized skeletal assessment of each patient. Proportional analysis which is based on theorems in Euclidean geometry. Sample – 245 subjects, mean age-12.6 yrs.
  52. 52. QUADRILATERAL ANALYSIS OF LOWER FACE   Maxillary bony arch length measured, horizontally between two points projected onto the palatal plane. anterior limit - projecting a perpendicular from Pt A upward to the palatal plane (ANS-PNS), posterior limit - projecting a perpendicular from the most inferior portion of the PTM downward to the palatal plane.
  53. 53.     Mandibular bony arch length horizontally between two points projected onto the mandibular plane (GoGn). anterior limit - determined by projecting a perpendicular from Pt B downward to the mandibular plane (Go Gn), posterior limit - determined by projecting a perpendicular from point J downward to the mandibular plane (Go Gn).
  54. 54.     Point J - deepest point of the curvature formed at the junction of the anterior portion of the ramus and the corpus of the mandible. A line is drawn from articulare tangent to the most posterior point on the ramus. A parallel line is then drawn through the innermost point on the curvature of the anterior aspect of the ramus. At a point where the remaining alveolar crest contacts the last molar, a line is drawn parallel to the gonion-gnathion plane. The angle formed is then bisected, and point J is located where this line crosses the inner curvature of the mandible.
  55. 55.  Anterior lower facial height (ALFH) is measured, as vertical linear measurement from the projection of point A onto the palatal plane to the projection of point B onto the goniongnathion plane
  56. 56.  Posterior lower facial height (PLFH) is measured, from the projection of PTM onto the palatal plane to the projection of point J onto the goniongnathion plane
  57. 57.      These four measurements – maxillary bony base length, mandibular bony base length, anterior lower facial height, and posterior lower facial height form the basis for the quadrilateral analysis of the lower face.
  58. 58.    The quadrilateral analysis indicates that in a balanced facial pattern a 1:1 ratio exists between the maxillary bony base length (Max.Lth.) and the mandibular bony base length (Mand.Lth.); Average of the anterior lower facial height (ALFH) and posterior lower facial height (PLFH) equals these bony base lengths. Max.Lth. = Man Lth = ALFH + PLFH 2
  59. 59. Dental Analysis  Maxillary incisor position: determined by drawing a line through point A parallel to the anterior lower facial height (ALFH).  A perpendicular from this line to the most anterior point on the maxillary incisor should result in a measurement of 5 mm ± 1 mm.
  60. 60.  Mandibular incisor position - drawing the line through point B parallel to anterior lower facial height (ALFH).  The perpendicular distance to the most anterior point of the lower incisor is 2 mm ± 1 mm.
  61. 61.  Pogonion line - drawing a line tangent to pogonion, parallel to anterior lower facial height (ALFH).  The most anterior point of the mandibular incisor should be ± 2 mm to this line.  This measurement will indicate if the chin is excessive or deficient in size
  62. 62. Sagittal Ratio  Important in assessing the relative anteroposterior position of the maxillary and mandibular bony bases.  Skeletal malformations of the jaws may be either in the bony bases or located posteriorly. Therefore, pinpointing the area of the deformity will have a significant impact on whether or not certain surgical procedures are indicated. For example, if we are to perform a surgical correction of a mandibular prognathism, it would be necessary to determine whether we should reduce the bony base lengths (body ostectomy or sagittal split setback) or whether we should perform mandibular surgery posterior to the bony base area (vertical osteotomy, etc.). 
  63. 63.    The lines used to measure the bony base lengths in are extended posteriorly to point x, which is the sagittal angle When the anterior and posterior lower face heights are parallel and the maxillary and mandibular bony bases are equal, a proportional relation exists with sides A, B, C, and D of the similar isosceles triangles. The ratio of A to B and C to D is called the sagittal ratio.
  64. 64.  Any forward or retroposition of the bony base will cause unequal lengths of the posterior legs (lines A and C).  In balanced skeletal patterns the sagittal ratio in adolescents is 1.0:1.50 ± 0.05;  in adults it is 1.0:1.45 ± 0.05  sagittal angle is 23° ± 1°.
  65. 65. Angle of facial convexity  Measurement of the skeletal profile.  This angle is formed by the intersection of anterior lower facial height with anterior upper facial height and relates the quadrilateral to the upper face.(165 - 178˚)  It shows possible areas of skeletal discrepancies, such as posture of the lower facial complex, cranial base deflections, and bony base discrepancies.  The degree of facial convexity will vary, depending upon the skeletal type and the position of the quadrilateral pattern as it relates to the upper face.
  66. 66.
  67. 67. Facial Types  Type 1. This face has a normodivergent pattern showing a favorable vertical growth .  In the majority of Type 1 cases, the maxillary and mandibular basal arch lengths are equal and the average vertical height is equal to the arch length. This balance indicates a harmonious skeletal development of the lower face.  Malocclusions in this group are dentoalveolar in origin. Tooth size— arch length discrepancies or anterior or posterior position of the teeth on their respective denture bases account for the majority of problems.
  68. 68.       Type 2. This face is hypodivergent, predominantly horizontal growth pattern . There is a reduction in lower face height with an undesirable growth pattern, resulting in a skeletal deep-bite. In these patients the average vertical height is deficient when compared to the denture base lengths. 3 possibilities: (A) Maxillary and mandibular denture base lengths are comparable in size, (B) maxillary base length is larger than the mandibular base length, and (C) mandibular base length is larger than the maxillary base length. The significance is that anteroposterior skeletal malrelationships can exist in skeletal deep-bite patterns.
  69. 69.      Type 3. This face is hyperdivergent, predominantly vertical growth pattern . There is an increase in lower face height with an undesirable growth pattern, resulting in a skeletal open-bite. In these patients the average vertical height is excessive when compared to the denture base lengths. Posterior alveolar compensation may prevent a dental open-bite in some cases . These cases usually present with a deep curve of Spee and a lack of posterior alveolar development. Leveling mechanics in these patients will cause the underlying skeletal open-bite to be manifested dentally.
  70. 70. 3 possibilities: (A) Maxillary and mandibular denture base lengths are comparable in size, (B) maxillary base length is larger than the mandibular base length, and (C) mandibular base length is larger than the maxillary base length. The significance is that anteroposterior skeletal malrelationship can exist in skeletal open patterns.
  71. 71. SUMMARY   Because of the increase in the scope of surgical orthodontics, visual interpretation of cephalometric films has become obsolete. Surgical orthodontics requires reliable diagnostic methods that can differentially assess the location and degree of the skeletal dysplasias. The surgical analysis not only attempts to satisfy these objectives but also gives the clinician an individualized skeletal assessment.
  72. 72.  Proper incisal positioning prior to surgical intervention is essential if we are to achieve optimum denture base relationships. An undesirable position of the upper and/or lower incisor teeth will cause the surgeon to be misled during surgery, resulting in a less than desirable facial harmony.
  73. 73. REFERENCES     1 Burstone CJ, James RB, Legan H: Cephalometrics for orthognathic surgery.J Oral Surg 1979 (36);269-77. 2 Legan H, Burstone CJ: Soft tissue cephalometric analysis for orthognathic surgery.J Oral Surg 1980 (38);744-751. 3 Burstone CJ: Integumental Profile. AJO 1958 (44); 125. 4 Di Paolo RJ, Philip C, Maganzini A: The quadrilateral analysis: An individualized skeletal assessment. AJO 1983 (83),1;19-32.
  74. 74.     5 Albert Chinappi, Di Paolo RJ: A quadrilateral analysis of lower face skeletal patterns. AJO 1970 (58),4;341350. 6 Di Paolo RJ, Philip C, Maganzini A: The quadrilateral analysis: A differential diagnosis for surgical orthodontics. AJO 1984 (86) 6;470-482. 7 Athanasios E Athanasiou: Orthodontic Cephalometry. 1st edtn,1995.Mosby-Wolfe.Pg- 247, 253,267,268. 8 Di Paolo RJ, Markowitz JL:Cephalometric diagnosis using quadrilateral analysis. JCO 1970 (4); 30-35.
  75. 75. Thank you For more details please visit