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C- Axis :
A growth vector for the Maxilla.
Stanley Braun :
Angle Orthod : 1999
www.indiandentalacademy.com
Introduction
•Cephalometric analysis is important in orthodontics because
it helps the clinician to understand the factors...
• “M” point - A geometrically defined point
within the maxillary complex, would permit
a description of the natural loci o...
C axis :
> A linear line from sella to M point.
> The purpose of this investigation was to study
the natural changes in po...
C-Axis
M-point
Angle θ
Angle α
www.indiandentalacademy.com
Materials and Methods :
• Lateral ceph 19 males & 20 females,
• Age group 7.4 to 18.75 years from Mooseheart growth
study,...
Results :
www.indiandentalacademy.com
Discussion :
Chronological growth along the C axis
Based on slope of linear regression formula. upto age 14.
C Axis in mal...
www.indiandentalacademy.com
Increases for both males and females throughout the
age studied.
It is relatively small.
For males - 3.980
Females - 2.250...
Conclusion
•C axis permits the quantification of complex maxillary growth in Cephalometric terms relative to
various crani...
• C axis however are related to gender up to age 14 in
males and females display average yearly growth
increments of 1.14m...
www.indiandentalacademy.com
∝ angle =
θ - Ǿ
www.indiandentalacademy.com
• Single point “M” cannot by itself summarized
the growth of the dento maxillary in the sagittal
plane
• However when asso...
www.indiandentalacademy.com
∀∝ angle tends to flatten the palatal plane
with respect to the C axis during growth
and development.
www.indiandentalacad...
• The C-axis incremental growth change & its
vector offer a means of quantifying
complex maxillary growth in the sagittal
...
The G axis ; A growth vector for the mandible: Stanley Braun
et al.
Angle Orthod : 2004
www.indiandentalacademy.com
Growth of the mandible :
> Expressed through the resorption & deposition at
periosteal & endosteal surfaces.
> Cartilage r...
It is noted that usefulness of the Y-axis has been
questioned because of extensive remodeling of the
external symphyseal ...
www.indiandentalacademy.com
• G Axis vector (Direction) is defined by the angle α which
G axis establishes relative to the sella-nasion.
∀ θ angle: It...
Methods & Materials :
> Serial lateral ceph of 24 males & 24 females.
> Age group 6 to 19.25 years without orthodontic
int...
Results :
www.indiandentalacademy.com
• G axis length increases in males 2.3mm / year.
• G Axis length increases in females 1.6mm/year.
• Growth velocities of G...
www.indiandentalacademy.com
• The low correlation coefficients of growth
vector axis angle for age range studied
shows little change in magnitude
• Sl...
www.indiandentalacademy.com
• Angular relationship of mandibular plane
to the “G” axis.
• Mean value increases 0.4º/year for males.
0.3º/year for fema...
From a clinical viewpoint, the mandibular plane angle is
commonly measured relative to S-N. This angle, herein
referred to...
Conclusion :
“G” Axis (S-G point) allows quantification of the complex mandibular growth process in
relation to various cr...
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C axis & g axis

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C axis & g axis

  1. 1. C- Axis : A growth vector for the Maxilla. Stanley Braun : Angle Orthod : 1999 www.indiandentalacademy.com
  2. 2. Introduction •Cephalometric analysis is important in orthodontics because it helps the clinician to understand the factors that may contribute to malocclusion . •Downward & forward migration often used in describing maxillary growth but imprecisely used. Nanda & Merill proposed “M” point constructed point representing the centre of largest circle that is tangent to the superior anterior & palatal surfaces of the maxilla in sagittal plane. www.indiandentalacademy.com
  3. 3. • “M” point - A geometrically defined point within the maxillary complex, would permit a description of the natural loci of this complex in relation to craniofacial structures during growth & development. www.indiandentalacademy.com
  4. 4. C axis : > A linear line from sella to M point. > The purpose of this investigation was to study the natural changes in position of M point in relation to anterior cranial base (S-N) using polar coordinates in combination with the palatal plane. Objective : It provides a quantitative description of the anterior & downward migration of the maxilla associated with growth. www.indiandentalacademy.com
  5. 5. C-Axis M-point Angle θ Angle α www.indiandentalacademy.com
  6. 6. Materials and Methods : • Lateral ceph 19 males & 20 females, • Age group 7.4 to 18.75 years from Mooseheart growth study, Chicago, illinois • no history of orthodontic intervention • “M” point determined on transparent template containing a no of circle whose diameter increased in 1mm increments. • The best fit circle was selected. www.indiandentalacademy.com
  7. 7. Results : www.indiandentalacademy.com
  8. 8. Discussion : Chronological growth along the C axis Based on slope of linear regression formula. upto age 14. C Axis in males increased at a rate of 1.14 mm /year. C axis in females increased at rate of 1.13mm/year Regression formula suggest growth along C axis tends to cease at age 16 years in females. In males increased through out the age of selected age group. www.indiandentalacademy.com
  9. 9. www.indiandentalacademy.com
  10. 10. Increases for both males and females throughout the age studied. It is relatively small. For males - 3.980 Females - 2.250 Linear regression formula suggests no statistically significant difference in growth axis angle. Growth axis angle (C axis - SN) V/s Chronological age. www.indiandentalacademy.com
  11. 11. Conclusion •C axis permits the quantification of complex maxillary growth in Cephalometric terms relative to various craniofacial structures in the sagittal plane. C axis angle is independent of gender within the chronological age studied. > www.indiandentalacademy.com
  12. 12. • C axis however are related to gender up to age 14 in males and females display average yearly growth increments of 1.14mm and 1.13 mm per year respectively . • After age 14 growth increments in females tends to diminish and cease at the age of 16 years. • In males growth along the C axis continues linearly throughout the age range studied. www.indiandentalacademy.com
  13. 13. www.indiandentalacademy.com
  14. 14. ∝ angle = θ - Ǿ www.indiandentalacademy.com
  15. 15. • Single point “M” cannot by itself summarized the growth of the dento maxillary in the sagittal plane • However when associated with the palatal plane the downward and forward migration is more accurately described than previously possible. www.indiandentalacademy.com
  16. 16. www.indiandentalacademy.com
  17. 17. ∀∝ angle tends to flatten the palatal plane with respect to the C axis during growth and development. www.indiandentalacademy.com
  18. 18. • The C-axis incremental growth change & its vector offer a means of quantifying complex maxillary growth in the sagittal plane via cephalometric measurements relative to & co-ordinated with other craniofacial structures www.indiandentalacademy.com
  19. 19. The G axis ; A growth vector for the mandible: Stanley Braun et al. Angle Orthod : 2004 www.indiandentalacademy.com
  20. 20. Growth of the mandible : > Expressed through the resorption & deposition at periosteal & endosteal surfaces. > Cartilage replacement by bone at the condyle & dental eruption accompanied by growth of alveolar bone. > Net result for this is the downward & forward displacement of the mandible. > This displacement quantified to a degree through the description of the Y-Axis (S-GN) Introduction : www.indiandentalacademy.com
  21. 21. It is noted that usefulness of the Y-axis has been questioned because of extensive remodeling of the external symphyseal area. > This study was undertaken to establish an improved descriptive growth axis for the mandible. > Length of the axis is determined by sella to G point > G point is defined as a point representing the center of the largest circle that is tangent to the internal inferior, anterior & posterior surfaces of the mandibular symphyseal region. www.indiandentalacademy.com
  22. 22. www.indiandentalacademy.com
  23. 23. • G Axis vector (Direction) is defined by the angle α which G axis establishes relative to the sella-nasion. ∀ θ angle: It is the angle between the mandibular plane to the S-G point. • Use of the three dimensions ∝, θ, & length of the G axis provides a quantitative description of the anterior & downward migration of the mandible related to growth & maturation. www.indiandentalacademy.com
  24. 24. Methods & Materials : > Serial lateral ceph of 24 males & 24 females. > Age group 6 to 19.25 years without orthodontic intervention. > ANB angle – 1 to 5o . > Ratio of N-ANS to ANS to GN 0.80 to 0.09 for males & 0.82 to0.09 for females. > G-point was established using specially designed transparent template containing a number of circles whose diameter increased in 1mm increments. > The best fit circle is selected www.indiandentalacademy.com
  25. 25. Results : www.indiandentalacademy.com
  26. 26. • G axis length increases in males 2.3mm / year. • G Axis length increases in females 1.6mm/year. • Growth velocities of G- axis length are determined by the slope of the mean linear regression formula. • Mean velocity of G - axis length increase for both genders is relatively constant within the age range studied. Discussion : www.indiandentalacademy.com
  27. 27. www.indiandentalacademy.com
  28. 28. • The low correlation coefficients of growth vector axis angle for age range studied shows little change in magnitude • Slope of both graphs are relatively shallow. www.indiandentalacademy.com
  29. 29. www.indiandentalacademy.com
  30. 30. • Angular relationship of mandibular plane to the “G” axis. • Mean value increases 0.4º/year for males. 0.3º/year for females. www.indiandentalacademy.com
  31. 31. From a clinical viewpoint, the mandibular plane angle is commonly measured relative to S-N. This angle, herein referred to as the angle ǿ, bears a geometric relationship to the angles α and θ. It is ǿ =(α – θ) www.indiandentalacademy.com
  32. 32. Conclusion : “G” Axis (S-G point) allows quantification of the complex mandibular growth process in relation to various craniofacial structures in Sagittal plane. www.indiandentalacademy.com

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