BJORKS CEPHALOMETRIC ANALYSIS. ORTHODONTICS pptx

GOOD EVENING
BJORK’S ANALYSIS
HISTORY AND INTRO
Bjork conducted extensive studies on 322 Swedish boys, 12 years of age and 281 young adults 21 to 23 years of age and included almost 90 different measurements.
This analysis was done by Bjork to investigate the effects of variations of jaw growth and the relationship between facial form and occlusion.The profile analysis, is similar to Steiner analysis in that it uses the SN as the reference and SNA, SNB along with Go-Gn.
This was published in his book “The face in profile”.

Bjork used the angle N-S-Ar (saddle angle), S-Ar-Go (Articular Angle) and Ar-go-Gn (gonial angle) to predict the growth change in face.
“Purpose of this investigations is therefore to examine normal varitions and mechanisms of prognathism as well as relationship between facial build up and bite.”
2 parametres
Sagittal and vertical
Subdivided into dentoalveolar and jaw realtionship

Pr-n-ss=also known as maxillary alveolar prognathism
Value is 2 degree




CL/ML= angle (also known as Mandibular alveolar prognathism) - formed by the lines Id-Pog and go-Me
Value is 70 degree




ILi/ML angle (also known as Mandibular incisor inclination) - formed by the central axis of the lower medial incisor and the line Go-Me, characterizes the position of the lower medial incisor to the plane of the mandible
Value 94 degree



angle OLs/NL (also known as, Maxillary zone angle ) - formed by the lines SpP and OcP, characterizes the position of the closing plane to the palatal plane



angle OLi/ML ( Mandibular zone Angle) - formed by lines tGo-Me and OcP, characterizes the position of the closing plane to the mandibular plane

NL/ML[also known as vertical jaw relationship]=angle between palatal plane and go- me

ML/RL (also known as Jaw-/Gonial Angle) - formed by the lines Ar-tGo and tGo-Me, characterizes the angle of the lower jaw



CRANIAL BASE
Saddle angle [n-s-ar]
Between nasion sella and articulare
Mean Value is 123





Beta angle=angle formed between AB line and the perpendicular through pt A from apparent axis of the condyle
Conclusions
Basal prognathism increases at greater rate during growth period than alveolar prognathism

References
Face in profile article ,1947 by bjork
Biomedical and biosocial anthropology journal [official journal of international anthropology
THANK YOU

1. GOOD EVENING

2. BJORK’S ANALYSIS

3. HISTORY AND INTRO Bjork conducted extensive studies on 322 Swedish boys, 12 years of age and 281 young adults 21 to 23 years of age and included almost 90 different measurements. This analysis was done by Bjork to investigate the effects of variations of jaw growth and the relationship between facial form and occlusion.The profile analysis, is similar to Steiner analysis in that it uses the SN as the reference and SNA, SNB along with Go-Gn. This was published in his book “The face in profile”.

4. Bjork used the angle N-S- Ar (saddle angle), S- Ar -Go (Articular Angle) and Ar -go- Gn (gonial angle) to predict the growth change in face. “Purpose of this investigations is therefore to examine normal varitions and mechanisms of prognathism as well as relationship between facial build up and bite.”

5. 2 parametres Sagittal and vertical Subdivided into dentoalveolar and jaw realtionship

6. Pr -n-ss =also known as maxillary alveolar prognathism Value is 2 degree

7. CL/ML= angle (also known as Mandibular alveolar prognathism) - formed by the lines Id- Pog and go-Me Value is 70 degree

8. angle ILs/NL (also known as: Max1-SpP Angle, Maxillary incisor inclination) - formed by the central axis of the upper medial incisor and the line SpP , characterizes the position of the upper medial incisor to the palatal plane Value is 110 degree

9. ILi /ML angle (also known as Mandibular incisor inclination) - formed by the central axis of the lower medial incisor and the line Go- Me, characterizes the position of the lower medial incisor to the plane of the mandible Value 94 degree

10. angle OLs/NL (also known as, Maxillary zone angle ) - formed by the lines SpP and OcP , characterizes the position of the closing plane to the palatal plane

11. angle OLi /ML ( Mandibular zone Angle) - formed by lines tGo -Me and OcP , characterizes the position of the closing plane to the mandibular plane

12. NL/ML[ also known as vertical jaw relationship]=angle between palatal plane and go- me ML/RL (also known as Jaw-/Gonial Angle) - formed by the lines Ar-tGo and tGo -Me, characterizes the angle of the lower jaw

13. angle S-N-A (also known as Maxillary prognatism , SNA Angle) - formed by the lines S-N and N-A, characterizes the position of the upper jaw in the sagittal plane angle S-N-B (also known as Mandibular prognathism, SNB Angle) - formed by lines S-N and N-B, characterizes the position of the lower jaw in the sagittal plane

14. CRANIAL BASE Saddle angle [n-s- ar ] Between nasion sella and articulare Mean Value is 123

15. Beta angle=angle formed between AB line and the perpendicular through pt A from apparent axis of the condyle

16. Conclusions Basal prognathism increases at greater rate during growth period than alveolar prognathism

17. References Face in profile article ,1947 by bjork Biomedical and biosocial anthropology journal [official journal of international anthropology

18. THANK YOU