- Email: [email protected]
What is a valid basis for superimposition?
18A Readers' Forum
tooth vitality, etc. The goal is to minimize the scar and to weigh the benefits of the treatment. In my 30 years of practice, my goal was to always have the upper incisors harmonize vertically with the patient's lip line and anterior posteriorly with their profile. The stability of a treated deep bite case also depends on upper incisor intrusion and root torque. In the finished case, the upper incisal edges should rest slightly on the lower lip with the lips closed and the inter-incisal angle should be such that the lower incisors have good contact with the cingulum of the upper incisors. Invariably, that required intrusion and torque to the upper incisors while treating the protrusive upper denture. These mechanics usually produced some blunting of the apexes of the incisors. Over the years, I found two factors that contributed to excessive root resorption: (I) jiggling the teeth enhanced by indecisive mechanics, light wires, or a tongue thrust habit; (2) having the incisors' roots proximate the lingual cortical plate. In maximum retraction cases, the best way to avoid lingual cortical plate contact is to intrude the incisors as their roots are being retracted. I remember in my younger days when certain members of our study club (including myself) were constantly trying to prove ourselves worthy of the title "Orthodontist." We were treating severe bimaxillary protrusion with "J" hook headgear in as little as 16 months. Trying our best to be academic about our efforts, we discussed the consequences of placing a pound of force on each canine tooth. The subject of undermining resorption would always come up until one day a fellow member (Dr Bill McKinley, a UT grad) spoke up saying, "What's wrong with undermining resorption?" meaning since we never saw any ill effects from it during long term retention, what was the big deal? After that statement, the subject was no longer discussed. Considering that our teeth are over-engineered for how we use them today, is a minimal blunting of the root apexes with careful mechanics worth the esthetics and stability achieved by placing the teeth in harmony with the face? Absolutely! Dr John "Jack" Hickham Hilton Head Island, SC
American Journal of Orthodontics and Dentofacial Orthopedics March 1999
What is a valid basis for superimposition? The differences of opinion between Buschang and Santos-Pinto and Coben (Am J Orthod Dentofacial Orthop 1998; 114:709-14) regarding superimposition has attracted considerable attention. Although it seems appropriate to discuss these differences, it is most regrettable that such discussions are necessary in a well-established specialty such as orthodontics. After 64 years of cephalometrics, such differences should not exist. These differences are strange reactions: one regards the article as a "quantum leap" and the other one criticizes the article severely. And they are both incorrect or inadequate! The work of Buschang and Santos-Pinto was not incorrect, only inadequate and therefore could not be considered a "quantum leap." The discussion failed to recognize the value of vertical growth of molars in determining the forward positioning of the chin. My opinion of Coben's contributions has been published in comprehensive detail in Articles 12 and 13 in the Schudy Chronicles. While I consider it basically incorrect, I highly respect Dr Coben and the sophisticated documentation he has done. My book published in 1998, in both English and French in the same volume, deals specifically with this subject, devoting 14 pages to it alone. Its approach to this subject is fundamentally different from that of either Buschang and Santos-Pinto or Coben. For those who may be interested, the book is entitled "A Discussion of New Orthodontic Concepts" and is published by Nelson & Meyer, Inc, 103, rue Villiers de l'Isle Adam, 75020 Paris, France; tel and fax, 33-1-43-61-06-36; e-mail, [email protected] Fred F. Schudy, DDS Houston, Tex
tooth vitality, etc. The goal is to minimize the scar and to weigh the benefits of the treatment. In my 30 years of practice, my goal was to always have the upper incisors harmonize vertically with the patient's lip line and anterior posteriorly with their profile. The stability of a treated deep bite case also depends on upper incisor intrusion and root torque. In the finished case, the upper incisal edges should rest slightly on the lower lip with the lips closed and the inter-incisal angle should be such that the lower incisors have good contact with the cingulum of the upper incisors. Invariably, that required intrusion and torque to the upper incisors while treating the protrusive upper denture. These mechanics usually produced some blunting of the apexes of the incisors. Over the years, I found two factors that contributed to excessive root resorption: (I) jiggling the teeth enhanced by indecisive mechanics, light wires, or a tongue thrust habit; (2) having the incisors' roots proximate the lingual cortical plate. In maximum retraction cases, the best way to avoid lingual cortical plate contact is to intrude the incisors as their roots are being retracted. I remember in my younger days when certain members of our study club (including myself) were constantly trying to prove ourselves worthy of the title "Orthodontist." We were treating severe bimaxillary protrusion with "J" hook headgear in as little as 16 months. Trying our best to be academic about our efforts, we discussed the consequences of placing a pound of force on each canine tooth. The subject of undermining resorption would always come up until one day a fellow member (Dr Bill McKinley, a UT grad) spoke up saying, "What's wrong with undermining resorption?" meaning since we never saw any ill effects from it during long term retention, what was the big deal? After that statement, the subject was no longer discussed. Considering that our teeth are over-engineered for how we use them today, is a minimal blunting of the root apexes with careful mechanics worth the esthetics and stability achieved by placing the teeth in harmony with the face? Absolutely! Dr John "Jack" Hickham Hilton Head Island, SC
American Journal of Orthodontics and Dentofacial Orthopedics March 1999
What is a valid basis for superimposition? The differences of opinion between Buschang and Santos-Pinto and Coben (Am J Orthod Dentofacial Orthop 1998; 114:709-14) regarding superimposition has attracted considerable attention. Although it seems appropriate to discuss these differences, it is most regrettable that such discussions are necessary in a well-established specialty such as orthodontics. After 64 years of cephalometrics, such differences should not exist. These differences are strange reactions: one regards the article as a "quantum leap" and the other one criticizes the article severely. And they are both incorrect or inadequate! The work of Buschang and Santos-Pinto was not incorrect, only inadequate and therefore could not be considered a "quantum leap." The discussion failed to recognize the value of vertical growth of molars in determining the forward positioning of the chin. My opinion of Coben's contributions has been published in comprehensive detail in Articles 12 and 13 in the Schudy Chronicles. While I consider it basically incorrect, I highly respect Dr Coben and the sophisticated documentation he has done. My book published in 1998, in both English and French in the same volume, deals specifically with this subject, devoting 14 pages to it alone. Its approach to this subject is fundamentally different from that of either Buschang and Santos-Pinto or Coben. For those who may be interested, the book is entitled "A Discussion of New Orthodontic Concepts" and is published by Nelson & Meyer, Inc, 103, rue Villiers de l'Isle Adam, 75020 Paris, France; tel and fax, 33-1-43-61-06-36; e-mail, [email protected] Fred F. Schudy, DDS Houston, Tex