THE EDITOR'S CORNER

There is almost universal agreement on the necessity for a space maintainer to keep the space of a prematurely lost deciduous second molar. There is a jurisdictional dispute within the profession over whose responsibility it is. This is due in some measure to the fact that the procedures used have been unrewarding in terms of success and unprofitable in terms of income derived. Most of the devices made of bands and wires have been too flimsy to remain in place for the long periods of time that may be needed. In addition, making a molar band for a six-year-old often results in so much festooning that the band has little retentive surface.

Due to their history, there is such a lack of confidence on the part of the profession in the various space maintainer devices, that most of the time nothing is done at the time of the extraction of the deciduous second molar. Before long, some of the space is lost. It then becomes a question of either maintaining the inadequate space; not maintaining an inadequate space, but treating the problem with orthodontic appliances later; or regaining the space and then maintaining it. None of these is satisfactory if the space could have been maintained in the first place.

What is needed is a better method of space maintenance and a clear definition of whose responsibility it should be. Space maintenance is not orthodontic treatment. It is a preventive measure to avoid orthodontic treatment; at least, to avoid orthodontic treatment for loss of space in that area. Therefore, it should clearly be in the province of the general dentist or pedodontist to maintain space. If it were so, I think a better space maintainer would quickly be evolved.

One possibility is a substantial 3-unit temporary fixed bridge with a pontic that is, wherever possible, hygienic. This feature allows some space under the pontic for cleansing and to permit the permanent successor to erupt. When the permanent successor begins to erupt, the bridge is removed and the mission has been accomplished.

The design of the abutments of such a bridge can present special problems. Placing crowns on the permanent first molar and deciduous first molar as abutments for the fixed bridge space maintainer may be alright as long as they do not open the bite too far. They could create or reinforce a tongue thrust problem in a mouth with an anterior open bite or one which has so little overbite that the addition of the crowns would create an open bite. With such a situation, the alternatives are to take your chances on the open bite; to use some other device for space maintenance; or to consider the possibility of preparing the occlusal surfaces of the deciduous and permanent first molars to accommodate the temporary crowns, if the maturation of the permanent first molars will permit it. The last alternative carries the unpalatable but not necessarily unthinkable necessity to provide a permanent crown restoration on the permanent first molar some time later.

Another consideration about the use of a temporary fixed bridge to replace the second deciduous molar is, what if the deciduous first molar loosens and is about to be lost before the permanent second bicuspid has begun to erupt? That is a second problem which does not negate the solution to the first one which was the premature loss of the second deciduous molar. The second problem is presumably going to exist over a shorter period of time and can probably be adequately handled with a fixed lingual arch.

With the possible exception of cases of congenitally missing second bicuspids, space maintenance is needed for premature loss of deciduous second molars including those in otherwise crowded arches which are obviously going to require the extraction of bicuspids. The mesial drift of a molar in such an arch means that some kind of space regaining will probably have to be accomplished plus the bicuspid extraction or the teeth are doomed to being too far forward and, if the drift was on one side, asymmetrical. If, of necessity, the upper arch is matched to the lower in such a situation, the error is compounded.