Contributionsof Arne Bjork by R TABZ.pptx

Contributionsof Arne Bjork
Orthodontics

1. Dr.Thabassum Parakkal ARNE BJORK CONTRIBUTIONS

2. Introduction. Achievements and awards Book of ‘The face in profile’. Variability and age changes in overjet and overbite Facial growth in man, studied with the aid of metallic implants. 2 CONTENTS

3. 3 Sutural growth of the upper face studied by the implant method. Growth in width of the maxilla studied by the implant method. Variations in the growth pattern of the human mandible: longitudinal radiographic study by the implant method. Prediction of mandibular growth rotation. Conclusion. References

4. E rik Arne Björk 4 22 nd December 1911 – 5 th February 1996

5. Introduction (1911-1996) 5 S wedish dentist; famous for his ‘ ’The Face in Profile Analysis ’’ which he published in 1947. He is also known to develop implant radiography.

6. 6 Practiced dentistry from 1937 – 1951 Professor and HOD of Department of orthodontics and craniofacial growth centre at the Royal College of Copenhagen for 30 years. Several awards for research in facial growth. Sample Footer Text

7. 7 Awards and recognitions Chairman of Orthodontic Department at Malmo, Sweden 1949-1950 Orthodontic Professor at Royal Dental College 1951-1981 Albert Ketcham  Memorial Award - 1973 Honorary membership in the World Federations of Orthodontists(WFO) 1980

8. BJORK’S ANALYSIS To assess anterior and posterior height relationship. To predict the direction of growth in the lower face. 1947 Articulare ( Ar ) .

9. This was published in his book “The face in profile”. 9

10. BJORK ANALYSIS Effects of variations of jaw growth and the relationship between facial form and occlusion. The profile analysis , is similar to Steiner analysis SN as the reference and SNA, SNB along with Go-Gn. 322 Swedish boys, 12 years of age. 281 adults 21 to 23 years of age. 90 different measurements .

11. N-S- Ar (saddle angle), S- Ar -Go (Articular Angle) to predict the growth change in the face Ar -go- Gn (gonial angle). Bjork felt that at the age of 11 years the length of the anterior cranial base (S-N) should be equal to mandibular body length (go-me) He stated that the ideal ratio of posterior cranial base length to ramus height is 3:4. This gives the basic skeletal evaluation and the incisor axis to A- Pog relates the denture to the skeletal base. 

12. 1. S-NA 7. S-gn 2. S- Ar 8. Na-Go 3. Ar -Go 9. Na-A 4. Go- Gn 10. Na-B 5. Na-Pog 11. A-Po 6. Occlusal Plane 12 long axis of the incisors The lines that are used are as follows. 

13. THE CRITERIA USED CRITERIA NORMAL VALUES 1. Saddle angle 123 o + 5 o 2. Articulare angle 143 o + 6 o 3. Gonial angle 130 o + 7 o 4. Sum of above 3 396 o 5. Ant. cranial base length 71 + 3 mm 6. Post.cranial base length 32 + 3 mm 7. Ramus height 44 + 5 mm S A G S

14. 8. Body length 71 + 5 mm 9. Mandibular body:anterior cranial 1 : 1 10. SNA 80 o 11. SNB 78 o 12. ANB 2 o 13. Anterior facial height:Posterior facial height 62-65% 14. Lower incisor to mandibular plane 90 + 3 15. Upper incisor to facial plane 5mm + 2 mm 16. Lower incisor to facial plane 2 mm + 2 mm

15. BJORK’S POLYGON In this analysis a polygon is used to assess the anterior and posterior facial height relationships and also to predict the direction of growth change in the lower face. Saddle angle (N.S Ar ), Articulare angle (S- Ar -Go), Gonial Angle ( Ar-Go_me ) and the length of the sides of the polygon.

16. It says, Anterior cranial base (S-N) = mandibular body length (Go-Me). The ideal ratio of the posterior cranial base length (S- Ar ) to the ramus height is 3:4.

17. If the sum total of the 3 angles, Saddle angle, Articular angle, Gonial angle exceeds 396, there would be tendency towards “clockwise” growth change in mandible. > 396 there would be a tendency of“counter clock-wise” growth change in the mandible.

18. Clockwise Change : Indicates that the anterior facial height is increasing more rapidly than posterior facial height and it could be associated with backward growth at the symphysis leading to anterior open bite tendency.  

19. Counter Clockwise Change: Indicate that the posterior face height is increasing more rapidly giving rise to forward growth of chin and anterior deep bite tendency.

20. Jarabak Skeleto Dental Cephalometric Analysis Jarabak introduced a new measurement by adopting and modifying the Bjork’s analysis The following is a description of the linear and angular measurements of the Jarabak Skeleto-Dental Analysis. The means of these angles is based on an average for Caucasian boys and girls at age 11 years

21. SKELETAL ANALYSIS SADDLE ANGLE:   This angle is formed by the junction of the N.S. line meeting with the a-S line at the center of the sella . The small “a” is the articulare . The mean of the saddle angle is 123 o + 5 o  

22. ARTICULARE ANGLE:  This is referred to as the joint angle and is an angle that can be changed by orthodontic treatment. It is the angle formed by the line from the S to “a” and the line from “a” to Go  The mean value for this angle is 143 o + 6 o .

23. GONIAL ANGLE: This angle is formed by the body of the mandible and the ascending ramus meeting at extended Go point. The mean value of this angle is 130 o + 7 o . Saddle angle (S), articular angle ( ar ) and gonial angle (go) and upper and lower gonial angles (Go 1 & Go 2 )

24. SUM TOTAL  This total is obtained by adding the saddle, articular and gonial angles. is 396 o The mean total of this skeletal angles. Any skeletal angle with the total of 403 o – 405 o or greater is a clockwise (posterior) grower. Any skeletal angle below 394 o is a counterclockwise (anterior) growing face.

25. ANTERIOR CRANIAL BASE: This is the S-N line measured linearly. According to Bjork the linear measurement for twelve year olds is 68.75 mm with a standard deviation of 2.97 The mean for this measurement established by Jarabak , is 71 mm – 3mm.

26. POSTERIOR CRANIAL BASE: This is the linear measurement from point S to point “a”. The mean for this line is 32 mm. This line is related to ramal height (a-Go) in a 3 : 4 ratio.

27. GONIAL ANGLE AND ITS PARTS: In order to estimate growth direction more accurately, we must go beyond accepting the gonial angle as a single factor of mandibular morphology. If the upper angle is large 58 o to 65 o the remaining growth increment will be sagittal.

28. In the facial structures if the upper half of the gonial angle is small (43 o to 48 o ) the remaining mandibular growth increment will be downward and backward. Growth in the ramus will make the lower face more prognathic. Jarabak’s upper and lower gonial angles

29. RAMUS HEIGHT: This linear measurement is from the articulare to the extended gonion angle. The Bjork sample height is 43.48 mm + 0.26mm. In the Jarabak sample the mean length is 44 mm. This measurement (44 mm) is related to the posterior Cranial Base Length (32 mm) in a 3 : 4 ratio. The ramus height increased in length with growth .

30. MANDIBULAR BODY LENGTH (CORPUS): the mandibular body length mean is 77mm. It is in a 1:1 ratio with anterior cranial base. This value is the same as the Bjork sample (73.58 mm + 0.31 mm).

31. SNA ANGLE:   The maxilla can be related to the cranium in one of three ways: Normal relation Maxilla posterior to normal Maxilla anterior to normal. he criteria which is used to determine which one of the three possibilities is present in the angle is described by two planes. Sella to nasion (SN) and Nasion to point A(NA). Jarabak mean for the SNA angle is 78 o

32. SNB ANGLE: The mandibular apical base is also related to the cranium in of the three ways; Normal raltion Mandible posteriorly related to cranium. Mandible anteriorly related to cranium.  The mandibular apical base is identified by the letter B. the angle between mandibular base and cranium is SNB. The Jarabak mean is 76 o to 78 o .

33. SN- gome ANGLE (ANTERIOR CRANIAL BASE AND MANDIBULAR BODY LENGTH)   The mean of this angle is formed by the extended junction of the SN line with GoMe line is 32 o

34. FACIAL DEPTH – N.Go :   This is a line measured from the nasion (N) to the extended gonion and is listed in millimetres .

35. FACIAL LENGTH ON ‘ Y AXIS:   t This is a line measured from the sella to a point at the lowest portion of the most prominent part of the pogonion.

36. Y AXIS TO SN:   This angle is formed by the junction of the facial length with anterior cranial base line (N-S). The mean range for this angle is 64 o to 68 o

37. POSTERIOR FACE HEIGHT (S-Go):   This is also known as the Jarabak axis and contributes along with anterior face height in forming the Face Height Ratio.  

38. ANTERIOR FACE HEIGHT ( N-Me):   This line is measured from nasion to the lower border of the mandible at menton .

39. POSTERIOR AND ANTERIOR FACE HEIGHT RATIO:   This ratio is indicated by percentage is determined by dividing the anterior face height (mm) into the posterior face height (mm). This will then give the direction the face will grow, either clockwise or counterclockwise. In this both the anterior and posterior facial heights are expressed in the form of a ratio as follows Anterior facial height x 100 Posterior facial height The mean range for clockwise growers is 54 to 58% or less. In the counterclockwise grower the mean range is 64 – 80%.

40. FACIAL PLANE (Sn-Po):   The mean angle of this plane is 81 o to 82 o . This compares favorably with Down’s value for an orthognathic face .

41. DENTAL ANALYSIS: OCCLUSAL PLANE TO BODY OF MANDIBLE (OCC. PL. TO GoMe ): This is measured at the junction of the occlusal plane line where it meets the Go-Me line to form an angle. The mean of this angle is 12 o

42. DENTAL CONVERGENCE OF MAXILLARY AND MANDIBULAR INCISORS (DENT. CONV. 1.1):   This angle is the junction of a line drawn through the long axis of the maxillary and mandibular incisors.   The mean of this angle is 133 o

43. MANDIBULAR INCISOR TO BODY OF MANDIBLE ( 1 to GO- Mr ):   A line is drawn through the long axis of the mandibular incisor tooth which meets the line of the body of mandible gives the angle of the forward or backward position of the incisors.

44. MAXILLARY INCISOR RELATED TO SN LINE (1 TO SN):   The mean angle of the junction of the long axis of the maxillary incisor where it meets the SN line is 102 o + 2 o .

45. MAXILLARY AND MANDUBULAR INCISORS TO FACIAL PLANE (N-Po):   The mean for the maxillary incisors to facial plane is 5 mm + 2 mm. The mean for the mandibular incisors to the facial plane is –2 mm to + 2mm.

46. FACIAL ESTHETIC LINE (RICKETTS): The Rickett’s facial esthetic line is used by Jarabak because of its simplicity, reliability and because it can be used at the chairside without depending on the cephalogram. Method : - Placing a straight edge on the tip of the nose and the tip of the chin in the midline, assuming the lips are not too forward, the relationship of the lips to the straight edge can be determined readily. The mean range, taken from a cephalogram, is –1 to 0.4 for the upper lip and 0 to +2 for the lower lip .

47. Jaw growth does not proceed in a linear, translatory fashion. He contended that the mandible becomes more prognathic with age, which is associated with a decrease in the angulation of the lower border as well as a decrease in the angle of convexity. 47

48. 1951 48

49. Aim To investigate the connection of development of the bite and its relation to facial growth in the individual . 49

50. Methods X-ray exposures of the facial profiles of a group of boys at the age of 12 and + equal no. of adults at 20 years Growth changes in the facial skeleton measured on lateral X-ray films of the head. 50

51. The three basic elements which determine the general shape of the cranium are the brain case, the cranial base and the facial skeleton , each one having its own distinct growth and development. 51

52. 52

53. 53

54. Individual cases deviate very considerably in almost every detail from these average growth changes. . . . 54

55. 55 The mean change and the range of variability has been noted for the different angles in the diagram.

56. Each case the slope of the forehead has increased. The saddle angle shows a tendency to increase. T he difference in basal prognathism may increase or decrease within a range of not less than 8 degrees. The difference in alveolar prognathism may increase or decrease in the same way, but to a lesser degree ; a range of 4 degrees. The incisors show an average tendency to an upright position during growth. 56

57. 1953 57

58. AIM 58 The changes in the bite of growing individual during the actual period of growth of the individual and its relation between growth and development of the dentition and of the facial skeleton and the cranial base.

59. Methods 2/1/20XX 59 The material of this study comprises two series of cephalometric x-ray films taken in a group of Swedish boys who were first examined at the age of 12 years, and then re-examined at the age of 20. group of 12-year-old boys comprised 322 who had been chosen at random Sample Footer Text

60. 2/1/20XX 60

61. 2/1/20XX 61 Sample Footer Text

62. 62 The variability in overjet is greater than in overbite, at the ages of both 12 and 20 years. The age changes for both overjet and overbite show pronounced individual differences, with regard to both direction and size. The age changes are greater for overbite than for overjet. The overjet generally changes with advancing age, so that the front teeth of the lower arch show a forward displacement in relation to those of the upper one.

63. 63 In two out of three children the change in overjet or overbite exceeds 1 mm. from 12 to 20 years. The overjet generally changes with advancing age, so that the front teeth of the lower arch show a forward displacement in relation to those of the upper one. Age changes in the overbite also show a certain relationship with the primary type of bite. Deep-bites show a greater tendency to open than normal overbites. whereas open bites show a tendency to close

64. 2/1/20XX 64 Age changes in the overbite also show a certain relationship with type of bite. Deep-bites show a greater tendency to open than normal overbites, whereas open-bites show a tendency to close. Sample Footer Text

65. 1955 2/1/20XX 65 Sample Footer Text

66. 66 The purpose of this investigation is to analyze the growth mechanism of the cranial base during the period of adolescence in Swedish boys. 243 individuals. Lateral cephalogram at 12 and 23 age. The cranial base is elongated ventrally by frontal apposition in the glabella region, without any appreciable longitudinal, sutural increment of the anterior cranial fossa.

67. Mandible 67 The rotation of the anterior cranial base and the brain case = rotation of the facial structure . The temporal bone, and hence the glenoid fossa, is displaced downward and forward or backward and upward as a result of the cranial base rotation and brings about changes in the mandibular position.

68. maxilla 68 The body of the maxilla increases in length toward the palatine bone and is lowered as a result of the growth which occurs between the palatine bone and the pterygoid processes.

69. 2/1/20XX 69 During the period of adolescence, the relation between the nasion- sella line and the deepest median contour of the anterior cranial fossa remains noticeably constant whereas tuberculum sellae and dorsum sellae appear to be raised in relation to the center of the sella . For this reason, the n-s line appears to be particularly suitable as a reference line during the adolescent period in man.

70. 1955 70

71. 2/1/20XX 71 To facilitate x-ray studies of the growth mechanism of the maxilla and mandible in Man. Different growth patterns. period of observation = two years . Sample Footer Text

72. 72 Metallic implants, three or four in each jaw serving as reference points. Vitallium pins , diameter of 0.62 mm and length of 2.0 mm. X-ray indicators (Vitallium pins) remain in position . The aid of which the x-ray plates may be orientated so that the growth pattern of each jaw can be analysed .

73. 2/1/20XX 73 Placed in the alveolar arch, level with the apical third of the roots The design and method of use

74. 74 Sample Footer Text A boy of harmonious facial structure and having normal dental occlusion .

75. maxilla 75 Sample Footer Text Growth occurs dorsally and that there is no frontal growth increment The longitudinal width of the condyle is confiined entirely to the condyle head, which is fully in accordance with present-day concept. mandible

76. 76 The bite is retruded position in the facial profile of the mandible in relation to the maxilla. Bite development appears to continue without any appreciable change in the occlusion. The eruption of teeth in the side segments of both jaws follows a mesial direction, probably due to pressure exerted by the erupting molars. The method has revealed information of interest, especially with regard to the vertical development of the face and the mode of eruption of the teeth.

77. 1963 2/1/20XX 77

78. 78 The method involving the insertion -of metallic implants (small pointed pins) under local anesthesia . chrome-cobalt alloy generated heat. Tantalum,more radio opaque 0.5x1.5mm

79. 2/1/20XX 79 Sample Footer Text

80. 80 Before pins are inserted Impression of form of mandible and position of dental germs obtained from profile radiographs Sample Footer Text

81. 2/1/20XX 81 Direction of condyle growth The direction of condylar growth was not necessarily linear, and, in many cases, there was a distinct curvature. Sample Footer Text

82. Conclusion. 2/1/20XX 82 45 Danish boys. The anterior aspect of the chin underwent no visible remodeling. Beneath the chin there was, in many cases, some periosteal growth, accentuated during adolescence. The direction of growth at the condyles in the sagittal plane varied widely, with an average direction slightly forward in relation to the posterior tangent to the ramus.

83. 83 Sample Footer Text 1966

84. 2/1/20XX 84 Sample Footer Text

85. 2/1/20XX 85 Sample Footer Text

86. 86 A pre-puberal minimum rate of sutural growth occurred at 11.5 years and a puberal maximum at about 14 years. These times correspond to those for the mandibular growth at the condyles but were a few months later than for the growth in body height. The sutural growth ceased at 17 years - that is, on an average about 2 years earlier than the condylar growth and growth in body height.

87. 87 1968

88. Insertion of the implants under local analgesia 88 Small pins of hard tantalum are hammered into the bone under local analgesia with a special pencil-shaped instrument in the tip of which the implant is placed