Grammons analysis and cogs
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Grammons analysis and cogs
- 2. Purpose • To find any frontal skeletal assymetry. • To study the frontal VTO • To evaluate tooth eruption with segmental TMJ splint therapy. • To evaluate improvements in facial or dental proportions. www.indiandentalacademy.com
- 3. Shortcomings • It is possible that all of the bones of the face may be overly large or small particularly in a population with skeletal deformities.Therefore clinician should mentally proportion his measurements comparing them with similar measurements form the standard. J. Oral Surg 1978 www.indiandentalacademy.com
- 5. Planes • Plane of reference is drawn from Crista Galli to the ANS to the chin and will be perpendicular to the Z plane. • Selected because it closely follows the visual plane formed between subnasale and midpoints between the eyes and eyebrows. Grummons article JCO 1987 www.indiandentalacademy.com
- 6. • The first horizontal plane connects the medial aspects of the zygomaticofrontal sutures. • The second horizontal plane connects the center of the zygomatic arches. • The third horizontal plane connects the jugal processes. • A fourth horizontal plane runs through the menton and is parallel to the first plane. Grummons article JCO 1987 www.indiandentalacademy.com
- 7. Zygomaticofrontal sutural plane Zygomatic arch plane Jugal plane Z plane through menton Mandibular morphology Volumetric comparison www.indiandentalacademy.com
- 8. Maxillo mandibular comparison of assymetry www.indiandentalacademy.com
- 10. Maxillo mandibular relations J perpendicular to 1st molar Ag to Ag ANS-Me www.indiandentalacademy.com
- 11. Frontal Vertical Proportion Analysis Upper facial ratio Lower facial ratio Maxillary ratio Total Maxillary ratio Mandibular ratio Total Mandibular ratio Maxillomandibular ratiowww.indiandentalacademy.com
- 12. Shortcomings • Difficulty in reproducing head posture. • Difficulty in identifying landmarks due to poor technique or superimposed structures. • Concern about radiation exposure. Grummons article JCO 1987 www.indiandentalacademy.com
- 13. Burstone's Hard Tissue Analysis (COGS) Burstone, Randal, Legan, Murphy & Norton (1978) www.indiandentalacademy.com
- 14. Purpose • To be able to analyse variation in facial bone as well as the dentition in relation to the jaws. • Analysis for patients requiring orthognathic surgery www.indiandentalacademy.com
- 15. Planes • Uses constructed true horizontal as a reference plane. • Occlusal plane is drawn form the buccal groove of both permanent molars through a point 1mm apical to the central incisors of each respective jaw base. • Mandibular plane is drawn from Go-Gn. • The nasal floor plane is the palatal plane. Burstone article J oral surg 1978 www.indiandentalacademy.com
- 16. Sample • Records of 16 female and 14 male subjects obtained from the Child research council of the University of Colorado school of medicine. • The mean measurement values closely correspond with those of other northern european populations. • It was a longitudinal sample selected to ensure consistent standards by age and rate of growth. • Standards and statistics are available for variations in age and sex from 5-20 years on the basis of developmental age. www.indiandentalacademy.com
- 17. Construction of horizontal plane Length of cranial base N-A-Pg angle N-A N-pog www.indiandentalacademy.com
- 18. Vertical Skeletal N-ANS ANS-Gn PNS-N Mandibular plane angle www.indiandentalacademy.com
- 19. Vertical Dental Measurements Lower molar to Mand. plane Lower incisor to Mand plane Upper molar to Nasal Floor Upper incisor to Nasal Floor www.indiandentalacademy.com
- 20. Maxillary and Mandibular measurements ANS-PNS Ar-Go Go-Pg Gonial Angle and Chin Prominence Ar-Go-Gn B-Pg www.indiandentalacademy.com
- 21. Dental Angular Measurements Upper Incisor – Nasal Floor angle Lower Incisor – Mandibular Plane Angle Horizontal to Occ. Plane angle www.indiandentalacademy.com
- 22. A-B parallel to Occ. plane www.indiandentalacademy.com
- 24. Shortcomings • Ceph measurements are based on a reference norm for caucasians not for other races. Proffit, White and Sarver text • SN plane unreliable. Sassouni article AJO 1955 • Fundamental errors in interpretation must occur if the details of malocclusion are related to outside craniometric reference lines. Schwarz article AJO 1961 www.indiandentalacademy.com
- 25. Shortcomings • It is possible that all of the bones of the face may be overly large or small particularly in a population with skeletal deformities.Therefore clinician should mentally proportion his measurements comparing them with similar measurements form the standard. J. Oral Surg 1978 www.indiandentalacademy.com