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- 1. DOWN’S ANALYSIS RICKETT’S ANALYSIS & CEPHALOMETRIC SUPERIMPOSITION www.indiandentalacademy.com
- 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
- 3. DOWNS ANALYSIS DOWNS ANALYSIS WAS INTRODUCED BY W.B. DOWNS IN 1948. This analysis was one of the first to be introduced DOWNS SAMPLE The control material studied by downs was derived form 20 white subjects, who ranged in age from 12 to 17 years. All individuals possessed clinically excellent occlusions. www.indiandentalacademy.com
- 4. VARIOUS LANDMARKS USED IN DOWNS ANALYSIS Nasion Sella Porion Point A (Subspinale) Point B (Supramentale) Gnathion Pogonion Orbitale Bolton point - The highest point on the concavity behind the occipital condyles www.indiandentalacademy.com
- 5. VARIOUS PLANES USED IN THIS ANALYSIS Most important reference plane (FRANK FORT HORIZONTAL PLANE) OCCLUSAL PLANE N MANDIBULAR PLANE FACIAL PLANE Pog www.indiandentalacademy.com
- 6. Downs anaylsis describes the skeletal pattern and dental pattern Skeletal pattern Facial angle Angle of convexity A-B plane Mandibular plane angle Y (Growth) Axis Dental pattern Cant of occlusal plane Inter incisal angle Incisor occlusal plane angle Incisor mandibular plane angle Protrusion of maxillary incisors. www.indiandentalacademy.com
- 7. Downs Facial Types WB downs noted the position of the mandible could be used in determining the facial types. Downs four basic facial types Retrognathic facial type Orthognathic facial type www.indiandentalacademy.com Prognathic facial type True prognathism
- 8. FACIAL ANGLE This is the inferior inside angle in which the facial line (nasion-pogonion) intersects Frankfort horizontal plane. The mean reading for this angle is 87.8 degrees (SD, 3.6) range varies from 82 to 95 degrees. The facial angle is used to measure the degree of retrusion or protrusion of the lower jaw. www.indiandentalacademy.com N FH Plane Pog
- 9. ANGLE OF CONVEXITY The angle of convexity is formed by the intersection of line N-point A and point A-pogonion. This angle measures the degree of the maxillary basal arch at its anterior limit (point A) relative to the total facial profile (nasion-pogonion) This angle measures the convexity or concavity of skeletal profiles. The range extends from a minimal of – 8.5 degrees to a maximal of +10 degrees, with a mean reading of 0 degree. www.indiandentalacademy.com
- 10. A-B PLANE This angle is formed between a line connecting point A and point B and line Joining nasion to pogonion (facial plane) . The A-B plane is a measure of the relation of the anterior limit of the apical bases to each other relative to the facial plane. The readings extend from a maximal of 0 degree to a minimal of –9 degrees with a mean reading of –4.6 degrees. www.indiandentalacademy.com
- 11. MANDIBULAR PLANE PLANE Mandibular plane according to downs, is tangent to the gonial angle and the lowest point of the symphysis. The mandibular plane angle is established by relating the MP to the Frank fort horizontal plane. The range of readings extends from a minimal of 17 degrees to a maximal of 28 degrees with mean reading of 21.9 degrees. www.indiandentalacademy.com
- 12. Y – (GROWTH) AXIS The y-axis is measured as the acute angle formed by the intersection of a line from the sella turcica to gnathion with the Frankfort horizontal plane The y-axis indicates the degree of the downward, rearward, or forward position of the chin in relation to the upper face. The range extends from a minimal of 53 degrees to a maximal of 66 degrees with a mean reading of 59.4 degrees. www.indiandentalacademy.com
- 13. CANT OF OCCLUSAL PLANE Downs occlusal originally plane defined as that the line bisecting the overlapping cusps of the first molars and the incisal overbite The cant of the occlusal plane is a measure of the slope of the occlusal plane to the Frankfort horizontal . The minimal angular measurement is +1.5 degrees; the maximal +14 degrees; and the mean +9.3 www.indiandentalacademy.com
- 14. INTERINCISAL ANGLE The interincisal angle is established by passing a line through the incisal edge and the apex of the root of the maxillary and mandibular central incisors. The minimal angular reading is 130 degrees; the maximal 150 degrees; and the mean 135.4 degrees. This angle is decreased in class I bimaxillary protrusion and Class II div1 cases. Increased in Class II div 2 cases. www.indiandentalacademy.com
- 15. INCISOR – OCCLUSAL PLANE ANGLE The incisor – occlusal plane angle relates the lower incisors to their functioning surface at the occlusal plane . The inferior inside angle is read as a positive or negative deviation from a right angle. The positive angle increases as the teeth incline forward. The minimal angle is +3.5 degrees; the maximal +20 degrees; and the mean 14.5 degrees (SD, 3.5) www.indiandentalacademy.com
- 16. INCISOR – MANDIBULAR PLANE ANGLE The incisor mandibular plane angle is formed by the intersection of the mandibular plane with a line passing through the incisal edge and the apex of the root of the mandibular central incisor The minimal angular reading is – 8.5 degrees; the maximal, +7 degrees; and the mean 1.4 degrees. www.indiandentalacademy.com
- 17. PROTRUSION OF MAXILLARY INCISORS The protrusion of the maxillary incisors is measured as the distance between the incisal edge of the maxillary central incisor to the line from point A-pogonion The distance is positive if the incisal edge is ahead of the point Apogonion line and indicates the amount of maxillary dental protrusion. The minimal reading is –1.0 mm; the maximal +5 mm, and the mean +2.7 www.indiandentalacademy.com mm
- 18. Parameter Minimal (degrees) Maximal (degrees) Mean (degrees) SD Skeletal pattern Facial angle 82 95 87.8 3.6 Angle of convexity -8.5 +10 0 5.1 A-B plane angle -9 0 -4.6 3.7 Mandibular plane 17 angle 28 21.9 3.2 Y- axis 66 59.4 3.8 53 Dental pattern Cant of occlusal plane +1.5 +14 +9.3 3.8 ⊥to 1 130 150.5 135.4 5.8 +20 +14.5 3.5 +7 +1.43 3.8 +2.7 mm 1.8 +3.5 ⊥ To occlusal plane 1 To mandibular -8.5 plane ⊥ To A-P plane -1.0 mm www.indiandentalacademy.com +5 mm
- 19. Vorhies and Adams, 1951 Polygonic interpretation of Downs analysis www.indiandentalacademy.com
- 20. RICKETT’S ANALYSIS This analysis was introduced by Robert Murray Ricketts in the year 1960 Material for this study was collected form 1000 white subjects in the age group of 3-44 yrs www.indiandentalacademy.com
- 21. Various land marks in this analysis A6 - point on the occlusal plane located perpendicular to the distal surface of the crown of the upper first molar. B6 - Point on the occlusal plane located PT CC perpendicular to distal surface of the crown of the lower first molar. C1 - Point on the condyle head in contact with and tangent to ramus plane. DT - Point on the anterior curve of the soft tissue chin tangent to the esthetic plane or E-line. CC - Point of intersection of the basion – nasion plane and the faical www.indiandentalacademy.com
- 22. Other land marks DC - Point in the center of the condyle neck along the Ba-N plane PT -Point at junction of the pterygomaxillary fissure and the foramen rotundum PT CC En - Point on the soft tissue nose tangent to the esthetic plane or E-line. Gn - Point at the intersection of the facial and the mandibular planes Go - Point at the intersection of the ramus and the mandibular planes. TI - Point of intersection of the occlusal and the facial planes www.indiandentalacademy.com
- 23. PM - Point at which the shape of the symphysis mentalis changes from convex to concave- also known as protuberance menti. Pog - Point on the bony symphysis tangent to the facial plane. PO - Intersection of the facial plane and the corpus axis. www.indiandentalacademy.com
- 24. LOCATION OF Xi POINT Xi - Point located at the centre of the ramus. Locate FH and draw PtV plane perpendicular to the FH plane Construct four planes tangent to points R-1, R-2, R-3 and R-4 on the borders of the ramus. The constructed planes form a rectangle enclosing the ramus Xi point is located in the center of the rectangle at the intersection of the diagonals. www.indiandentalacademy.com
- 25. REFERENCE PLANES USED Facial plane Mandibular plane Frank fort horizontal plane Basion - Nasion plane Ptv plane Denture plane www.indiandentalacademy.com Esthetic plane
- 26. LOCATION OF AXIS DC Facial axis Condylar axis Corpus axis www.indiandentalacademy.com
- 27. Various measurements used in this analysis To locate the position of chin Facial axis Facial angle Mandibular plane angle Convexity of the face Convexity at point A Position of upper & lower teeth Lower incisor to APog line Upper molar to Ptv plane Lower incisor to Apog plane Evaluate the facial profile Lower lip to E-plane www.indiandentalacademy.com
- 28. Facial Angle Facial axis FACIAL ANGLE (Depth) The angle formed between the facial plane (N-pog) and the frank fort horizontal plane. Mean values for 9 year old is 87o ± 3 and increases 1o every 3 years FACIAL AXIS The angle formed between the Basion -Nasion plane and the plane from foramen rotandum (PT) to gnathion. On the a average this angle is 90o ± 3.5 degrees and there is no age changes. www.indiandentalacademy.com
- 29. Go MANDIBULAR PLANE ANGLE Measures an angle formed by the mandibular plane (Gonion – Gnathion) with Frankfort horizontal plane On the average this angle is 26o at 9 yrs of age and decreases 1o every 3 years www.indiandentalacademy.com
- 30. Facial contour indicator Convexity at point A The convexity of the middle face is measured form (point A – N- pog). Normal value on the average is 2 mm at 9 years of age and decreases approximately 1mm every 3 years According to AJO 1960 Faces displaying 2mm convexity or concavity straight faces. Faces with 5 to 6 mm of convexity or concavity moderately convex or concave. If it is more than 10 mm or more severely convex or www.indiandentalacademy.com concave.
- 31. INDICATOR OF LOWER DENTURE POSITION Lower incisor to A-pog Dentureplane (A-Pog) plane The incisal tips of lower incisors are measured to A- Pog plane and position of lower anterior teeth determined. Indicates protrusion of lower anteriors Ideally the lower incisor is 1 mm ahead of A-Pog line. Lower incisor Inclinations The angle between the long axis of the lower incisor and the A- pog plane (1 to A-Po) is measured On the average this angle is 28 degrees Mean values for 9 years old is 22o±4 and there is no changes with age. www.indiandentalacademy.com
- 32. Upper molar to PtV Plane This measurement is the distance from the ptery goid vertical plane to the distal of upper molar. Mean value in a 9 year old patient is (age +3 mm) and 1 mm is added per year. Evaluation of the profile The distance between the lower lip and esthetic plane is an indication of soft tissue balance between the lips and profile. www.indiandentalacademy.com
- 33. CEPHALOMETRIC SUPER IMPOSITION www.indiandentalacademy.com
- 34. A CEPHALOMETRIC SUPERIMPOSITION IS AN ANALYSIS OF LATERAL CEPHALOGRAMS OF THE SAME PATIENT TAKEN AT DIFFERENT TIMES CEPHALOMETRIC SUPER IMPOSITIONS INVOLVE THE EVALUATION OF: ♦ Changes in the overall face ♦ Changes in the maxilla and its dentition ♦ Changes in the mandible and its dentition ♦ Amount and direction of condylar growth Mandibular rotation www.indiandentalacademy.com
- 35. TO PERFORM ACCURATE SUPER IMPOSITION Consecutive cepholograms should be taken under identical condition of magnification head position, and radiological exposure The tracing of the superimpositions must be accurate It is of great importance that exactly the same structures and their corresponding radiographic shadows be traced in the consecutive cepholograms One should have the thorough knowledge of anatomy of dentofacial & cranial structures as well as radiographic interpretation They have to be registered on stable reference areas in the face. www.indiandentalacademy.com
- 36. SUPERIMPOSITION OF THE Evaluates MAXILLA 1. Movement of maxillary teeth 2. Rotation of maxilla Two method for superimposing the maxillary structutres are recommended- the structural method and a modified best fit method. Structural Method : - Suggested by Bjork & Skieller in 1976. is recommended if the details of the zygomatic process of the maxilla are clearly identified in both cephalograms. Modified best fit method : - If the details of zygomatic process of maxilla are not identified in both cephalograms. www.indiandentalacademy.com
- 37. Structural method of superimposition of maxilla Pre treatment Tracing Post treatment Tracing Super imposition of pre & post treatment tracing On each cephologram, trace the contours of palate, maxillary 1st molar, central incisors, zygomatic process of maxilla, floor of the orbit N-S line and the construction line. www.indiandentalacademy.com
- 38. Modified best fit method Pre treatment Tracing Progress treatment tracing Super imposition of pre & progress treatment tracing On each cephologram trace the outline of the palate 1st permanent molars and central incisors. Following structures are in a best fit alignment. Contour of the oral part of the palate Contour of the nasal floor www.indiandentalacademy.com
- 39. MANDIBULAR SUPERIMPOSITIONS Evaluates Movement of the mandibular teeth Mandibular rotation Amount & direction of condylar growth Stable structures for superimposition on the mandible:According to Bjork and Skieller (1983). The anterior contour of the chin (area 1) The inner contour of the cortical plates at the inferior border of the symphysis. (area 2) Posteriorly, the contours of the mandibular canal (area 3) Lower contour of a mineralized molar germ. (area 4) before root www.indiandentalacademy.com formation.
- 40. Step – by – step approach for mandibular superimpositions Pre treatment Tracing Progress treatment tracing Super imposition of pre & progress treatment tracing On each cephologram trace the following The symphysis with inner cortical bone The inferior and posterior contour of the mandible The anterior contour of the ramus The most labially positioned lower incisor, and The first molar. www.indiandentalacademy.com
- 41. Evaluation of the overall changes in the face Nelson’s (1960) and Melsen (1974) identified certain stable structures for superimposition. 1. The anterior wall of sella turcica; 2. The contour of the cribiform plate of the ethmoid bone (lamina cribrosa); 3. Details in the trabecular system in the ethmoid cells; 4. The median border of the orbital roof; and 5. The plane of the sphenoid bone (planum sphenoidale) www.indiandentalacademy.com
- 42. What can we learn from cranial base superimpositions ? 1. Cranial base superimpositions provide an over all assessment of the growth and treatment changes of the facial structures. 2. Amount and direction of maxillary and mandibular growth or displacement 3. Changes in maxillary – mandibular relationships 4. Relative changes in the soft tissue (specifically the nose, lips, and chin) 5. Information on the overall displacement of the teeth. www.indiandentalacademy.com
- 43. RICKETTS SUPER IMPOSITION TECHNIQUE It is one of the most important superimposition technique used. Ricketts super imposition is used to differentiate the changes in normal growth and those due to treatment mechanics. This techniques involves five super imposition areas to evaluate 1. The chin 2. The maxilla 3. The teeth in the mandible 4. The teeth in the maxilla 5. The facial profile www.indiandentalacademy.com
- 44. Superimposition area 1 (Basion – Nasion at CC point (Evaluation area 1) Evaluates:- growth of the chin Position of upper molar In normal growth chin grows down the facial axis at 2.8mm per year Mean change = 0o SD± 3.3o/year www.indiandentalacademy.com
- 45. Super imposition area 2 (Basion – Nasion at Nasion) Evaluation area 2 Skeletal behaviour of maxilla Evaluates:- Any change in position Maxilla In normal growth:- Basion Nasion point A angle does not change Maxilla drops in a parallel fashion with point A straight down Nasion A line. Mean change = 0o SD± 2o/year www.indiandentalacademy.com
- 46. Super imposition area 3 (Corpus axis at PM) Evaluation area 3 & 4 Relation of mandibular teeth to mandible Evaluates:- Position of lower central incisors & lower molar www.indiandentalacademy.com
- 47. Super imposition area 4 (Palate at ANS) Evaluation area 5 & 6 Relation of maxillary teeth to maxilla Evaluates:- Any changes in the upper central incisors and upper molars www.indiandentalacademy.com
- 48. Super imposition area 5 (Esthetic plane at the crossing of the occlusal plane) Evaluation area 7 Evaluate the soft tissue profile www.indiandentalacademy.com
- 49. Other Super Imposition Methods to Evaluate over all changes in the face The broadbent triangle (Na-S-Bo) and its registration point R were among the first structures used for superimpositions to determine overall changes Sella – nasion line Broadbent triangle (Na-S-Bo) In this method two tracings on the Sella – nasion line with registration at sella www.indiandentalacademy.com
- 50. CONCLUSION Rickett’s, Down’s & Cephalometric superimposition are a valuable tool in treatment planning. These analysis help in orthodontic diagnosis by enabling the study of skeletal, dental and soft tissue structures of the cranio facial region. These analysis also classify the skeletal and dental abnormalities and establish the facial type. www.indiandentalacademy.com
- 51. BIBLIOGRAPHY Orthodontic cephalometry - By E. Athanasiou Radiographic cephalometry - By Alexander Jacobson Contemporary orthodontics - By R. Proffitt American journal of orthodontics, 1960 May (Ricketts) www.indiandentalacademy.com
- 52. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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