16A Readers'forum American Journal of Orthodontics and Dentofacial Orthopedics August 1997

Treatment plan rationale questioned

In the December 1996 issue of the AJO/DO a case was presented by Drs. Ghosh and Nanda in which they treated a Class II, Division I with severe overjet by molar distalization.

In their plan of treatment, they reason that a nonextraction plan was developed because "a fuller, slightly protrusive profile is more desirable for black persons."

Although they achieved a beautiful result, I question their rationale. I as- sume the extraction approach would have indicated removal of the upper first bicuspids, maintaining the Class II molars, and bringing the anteriors back to a Class I cuspid relationship. Being that in both approaches the lower teeth should be maintained in their original position and the upper

anteriors are being moved back, is there any evidence that an extraction versus nonextraction approach to treatment for this type of patient would yield a different profile?

David. M. Schneeweiss, DDS, MSD Wesley Hills, N. Y.

Reply to Dr. Schneeweiss

Thank you [Editor] for sending the letter from Dr. Schneeweiss, who had a question about our case report in the December 1996 issue of the AJO/DO.

Dr. Schneeweiss questions the effect of nonextraction maxil lary molar distalization versus extraction of maxillary first premolars on the facial profile. For the patient pre- sented in the article, I would like to state outright that there is more than one treatment plan, some of which include nonext ract ion (molar distalization, functional appliances,

Class II elastics), extraction of max- illary first premolars only, and extrac- tion of maxillary first premolars and mandibular second premolars. Any of these, in the hands of a skilled cli- nician, would yield an acceptable re- sult. My personal preference for ex- traction of teeth in a growing indi- vidual with a Class II, Division 1 malocclus ion is maxi l lary f irst premolars and mandibular second premolars, resulting in Class I mo- lars and canines. In an adult, extrac- tion of maxillary first premolars only, which would result in Class I canines

and Class II molars, is a viable treat- ment option.

In the case presented, the point that we wished to make was that an extract ion-based approach with overretraction of anterior teeth could adversely affect the fuller lip profile that is more desirable for African- Americans.

Joydeep Ghosh, D.D.S., M.S. Assistant Professor

Department of Orthodontics Oklahoma City, Okla.

Another possible etiology for anterior open bite ?

It is commonly believed that the etiologies of anterior open bite are multifactorial, varied, and numerous. Many underlying causes for anterior open bite have been advanced in the literature. I would like to present here, a yet unrecognized etiology that I have identified during the past 23 years of observation in my private practice.

Commonly accepted beliefs: 1. Newly erupted teeth have large

pulp chambers and relatively less dentine than mature teeth. As the teeth mature, the dentinal layer thickens and the pulp chamber recedes, rendering the teeth less sensitive to extreme cold.

2. When a large amalgam resto- ration is placed for deep caries,

initially the tooth may be sensi- tive to cold. This sensitivity is gradually reduced as secondary dentine is formed below the floor of the restoration.

3. When air rushes over a wet ob- ject, evaporation reduces the temperature of that object.

4. The tongue will reflexively move to the sensitive tooth to protect it from extreme cold (sometimes experienced when eating ice cream or during high-speed suction and air-driven rotary in- strumentation).

5. Many open bites in early mixed dentition spontaneously close in the late mixed or permanent dentition.

The following are my clinical ob- servations:

When I debond lower incisors with a high-speed finishing burr and suction, some patients aggressively place their tongue against the lower incisors even at the risk of being cut by the burr. These patients frequently complain of cold sensitivity. If I place my thumb well behind the incisors to block the tongue, the tongue re- flex to reach the lingual surface of the lower incisors persists.

If I rest my thumb directly in con- tact with the lingual surface of the lower incisors the tongue not only stops coming forward but actually relaxes and retracts.

I would propose that when my thumb just holds the tongue back but does not make contact with the inci- sors, the teeth remain chilled by the air and high-speed suction. When I