Class II, divison 1 Malocclusion Buck Teeth

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Buck Teeth (Class II division 1 malocclusion)

Dedicated to  Esther Lafair

Based on the Doctoral Dissertation thesis presented to the The Department of Physical Anthropology
University of Pennsylvania

"Find out the cause of this effect: Or, rather say, the cause of this defect; for this effect defective, comes by cause." --William Shakespeare

On the nature of Buck Teeth: Is this condition on average caused by an under-grown jaw?
(See the "ruler without numbers": how the jaws and teeth are analyzed)
 

Lateral Head ("Cephalometric") X-Ray of a patient with "buck teeth: (Its scientific name was first applied to it by the father of modern orthodontics-- Dr. Edward Angle as "Class II, division 1 Malocclusion"). It is also called "distal-occlusion", "retro-occlusion", retrognathia and simply overbite. It occurs in 25% of the population. Orthodontists diagnose and treat this problem quite often. The big diagnostic question is how to treat this problem. Is the lower jaw retruded/small/ under-grown/set backward? Or is the upper jaw protruded/large/over-grown/set forward? How the orthodontists decides which is which determines how he is going to treat this problem.

He based his classifications on the relative position of the maxillary first molar.[2] According to Angle, the mesiobuccal cusp (the front cusp) of the upper first molar should rest on the mesiobuccal groove (the middle) of the mandibular first molar. The teeth should all fit on a line of occlusion which is a smooth curve through the central fossae and cingulum of the upper canines, and through the buccal cusp and incisal edges of the mandible. Any variations from this resulted in malocclusion types. It is also possible to have different classes of malocclusion on left and right sides.

Class I: Neutrocclusion Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.

Class II: Distocclusion (retrognathism, overjet) In this situation, the upper molars front cusp) are placed NOT in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. Below see photo of this fairly common malocclusion:

Class II division 1 malocclusion
(Buck Teeth)

Class II Div 1 Overjet (Lip Procumbency)
YouTube animation showing correction from Class II to Class I (normal)

Actually the founding father of orthodontics (Edward Angle, Ca. 1904) strongly believed that when you had a buck-teeth like condition the problem was caused by the lower jaw being small (under-grown) or retruded (shifted backward in position--"retrognathic"). He thought the upper back teeth never shifted into a forward position. The data in my study (1971), the first computerized study of its kind, utilized (LARGE SAMPLES, GROUPED BY AGE AND SEX) indicated his belief was erroneous, and on average the lower jaw of the children with buck-teeth is most often identical in size and position to those children who do not have buck-teeth. In fact, it is the upper jaw and teeth that are forward in position. No other study of this magnitude has been done to dispute the findings of this study completed in 1971.

[CLICK HERE TO SEE THE CONTENTS OF THE PDF DOCUMENT]

CONTENTS OF DOCUMENT:

  1. Brief introduction: rationale, objective and results of the study
  2. Abstracts of Part I : Jaw-size, form and position at age 10, 12 and 14, and of Part II: Jaw-growth age 10-14 (American Journal of Orthodontics and DentoFacial Orthopedics)
  3. Title page of the dissertation thesis
  4. Schematic drawings of a normal skull, jaws and dentition; same for children with buck teeth
  5. The research  question/hypothesis: whether and how the jaws differ in children with buck teeth compared with children having normal jaws and dentition.
  6. The anatomical landmarks of the skull, jaws and teeth used to make the measurements
  7. The 188 points of the "mathematical model" used to describe the skull, jaws and teeth of each individual included in the study and from which were derived 52 linear and angular measurements
  8. A tracing of a patient's lateral head X-ray (see above). NOT SHOWN: the markings showing the 188 anatomical and "derived" landmarks (See tracing clik here)
  9. The  computer data cards resulting from "scanning" the tracings of the skull, jaws and teeth of each of the 600 children in the study
  10. A table showing the number of children, age and sex in each of the 6 sample comparisons of children with normal jaws and dentition and children having buck teeth
  11. The 52 linear and angular measurements made on every individual in the study
  12. The pictorial results of all 6 sample computer-generated comparisons of normal control groups compared with individuals having buck teeth
  13. An enlarged computer-generated averaged composite view of 43 normal12 year-old males overlaid on the averaged composite view of 70 children having buck teeth (the fourth comparison in the study). Each of the other 5 sample comparison showed similar results.
  14. Summary of the results and findings including Part II: Growth from 10-14
  15. A computer-generated actual-size view of 48 (forty-eight) 10 year old males overlaid on a computer generated composite of  45 (forty-five) 45 14 year-olds demonstrating the amount and direction of growth between ages 10 and 14 in males
  16. Enlarged graphic view of the amount and direction of growth of each major anatomic landmark in normal males and females compared with males and females having buck teeth at ages 10, 12 and 14
  17. The growth in millimeters in the "X" and "Y" directions of the major anatomic landmarks for normal males and females and the males and females with buck teeth
  18. Explanation of  the "Composite-Standard": a method using the "averaged" composite computer-generated (actual size) of a sample of same-sex and age children with normal jaws and teeth to identify jaw and dental deviations in children presenting with skeletal and dental deviations without having to make any actual linear and angular measurements
  19. Shown is the Composite-Standard for normal 12 year-old males; Standards were created for 10 and 14 year-old males and 10,12 and 14 year-old females.
June 11, 2011

Ted Rothstein   DDS   PhD  
Specialist in Cosmetic Orthodontics
and Dentofacial Orthopedics
Adults and Children
Specialist in Orthodontic Jaw Wiring

American Association of Orthodontists
Life-active Member
35 Remsen St., Bklyn, NY 11201
718 852 1551    Fx 718 852 1894
www.drted.com  
 drted35@aol.com