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Reply to Dr. Berg
20A Reader's forum
American Journal of Orthodontics and Dentofacial Orthopedics
Reply to Dr. Berg
First, I thank Prof. Berg for his generous comments regarding the case I presented in the April issue of the AJO/DO. I routinely use palatal arches with auxiliary springs in the treatment of palatally impacted maxillary canines and in a fair number of cases where maxillary canines are located buccally. The decision whether to use a palatal arch when the teeth are impacted in a buccal position depends on the crown tip location and the direction of force required for optimal tooth movement. In this case, a palatal arch with an auxiliary spring was positioned before surgery in case palatal force systems were required. As I explained in the case presentation, success depended on the absence of ankylosis and whether the maxillary canines could be moved past
the root apex of the maxillary lateral incisors. For this reason, I did not want to remove the deciduous canines before the maxillary canines had been brought down a certain distance. Consequently, because of the occlusion, it was not possible to pass an auxiliary spring across the arch. In this case, I decided to bond before surgery, because a buccal approach was likely. The surgeon could then pass the ligature from the lingual button through the flap and hook it over the arch wire, thus reducing the amount of pain associated with initial activation. If no brackets had been present at surgery, the surgeon would have had to fix this wire to either the lateral incisor or the first premolar. During initial activation, the wire from the button would be straightened out and consequently cut
through soft tissue, leading to patient discomfort. In my early days as an orthodontist, I did use a high labial arch with auxiliary springs in a certain number of cases with buccally impacted maxillary canines. However, I found that it was difficult to control such a high labial arch in some cases and abandoned this practice many years ago. Whenever a palatal arch with auxiliary spring can be used, I agree with Dr. Berg that initial harmonization of the impacted canines without bonded teeth is an advantage for the reason he mentions, and normally I postpone bonding in such cases to a time when the impacted tooth is near eruption.
Jan ~degaard Madlaveien 9 4008 Stavanger Norway
In favor of semirapid expansion I would like to congratulate Drs. Sandikgio-lu and Hazar I on their recent article. It is the first scientific presentation I have seen that compares slow, semirapid, and rapid expansion. Slow expansion is usually defined as approximately one third mm per week, semirapid as 1 mm per week, and rapid is approximately 3 mm per week. Although many firm opinions are expressed by clinicians to justify their preferred rate, there has been little firm evidence available. Critics of slow expansion dislike the pain, the tissue damage, and the box-shaped arch form that often results. I discussed these issues in 19772 when I first recommended a simirapid rate of 1 mm per week. Story 3 showed that rapid expansion was followed by poor tissue repair, as the capillary network can hardly keep up with the separation
of the suture. Many clinicians feel that in the long term, expansion relapses to an extent that renders it valueless, whereas others use it routinely in their practice. The relapse does seem highly variable, but several studies 4,5 have shown that the widening of the vault is stable and it is the alveolus that tends to relapse. This would suggest that it is advantageous to separate the suture. Sandik£io-lu and Hazar appear to have had some difficulties in gaining cooperation with the patients who wore the semirapid appliances that were removable. I note from their figures that although the patients were asked to open at 1 mm per week, the effective rate over the 5.5 months was less than a fifth of a millimeter per week. In my clinical experience, that is too slow to open the suture and is not really
semirapid. This study could possibly be misleading in this respect. My own research 6 suggests that semirapid expansion is very stable. I could perhaps offer the authors some advice in gaining an effective rate of 1 mm per week. First, insist that the patients wear the appliance while eating. This may be impossible to start with, but children will hardly notice it in their mouth within 10 days. Second, open one eighth of a turn each day, not one quarter every other day. The periodontal membrane is approximately an eighth of a millimeter thick and so an eighth of a turn, distributed between the two sides, will only reduce it by half, not crush it. Also it is easier to remember something you do every day. Third, check the amount of opening at each visit, because if the rate of opening slows much below 1 mm per week, the suture will not separate and most of the widening
American Journal of Orthodontics and Dentofacial Orthopedics
Reply to Dr. Berg
First, I thank Prof. Berg for his generous comments regarding the case I presented in the April issue of the AJO/DO. I routinely use palatal arches with auxiliary springs in the treatment of palatally impacted maxillary canines and in a fair number of cases where maxillary canines are located buccally. The decision whether to use a palatal arch when the teeth are impacted in a buccal position depends on the crown tip location and the direction of force required for optimal tooth movement. In this case, a palatal arch with an auxiliary spring was positioned before surgery in case palatal force systems were required. As I explained in the case presentation, success depended on the absence of ankylosis and whether the maxillary canines could be moved past
the root apex of the maxillary lateral incisors. For this reason, I did not want to remove the deciduous canines before the maxillary canines had been brought down a certain distance. Consequently, because of the occlusion, it was not possible to pass an auxiliary spring across the arch. In this case, I decided to bond before surgery, because a buccal approach was likely. The surgeon could then pass the ligature from the lingual button through the flap and hook it over the arch wire, thus reducing the amount of pain associated with initial activation. If no brackets had been present at surgery, the surgeon would have had to fix this wire to either the lateral incisor or the first premolar. During initial activation, the wire from the button would be straightened out and consequently cut
through soft tissue, leading to patient discomfort. In my early days as an orthodontist, I did use a high labial arch with auxiliary springs in a certain number of cases with buccally impacted maxillary canines. However, I found that it was difficult to control such a high labial arch in some cases and abandoned this practice many years ago. Whenever a palatal arch with auxiliary spring can be used, I agree with Dr. Berg that initial harmonization of the impacted canines without bonded teeth is an advantage for the reason he mentions, and normally I postpone bonding in such cases to a time when the impacted tooth is near eruption.
Jan ~degaard Madlaveien 9 4008 Stavanger Norway
In favor of semirapid expansion I would like to congratulate Drs. Sandikgio-lu and Hazar I on their recent article. It is the first scientific presentation I have seen that compares slow, semirapid, and rapid expansion. Slow expansion is usually defined as approximately one third mm per week, semirapid as 1 mm per week, and rapid is approximately 3 mm per week. Although many firm opinions are expressed by clinicians to justify their preferred rate, there has been little firm evidence available. Critics of slow expansion dislike the pain, the tissue damage, and the box-shaped arch form that often results. I discussed these issues in 19772 when I first recommended a simirapid rate of 1 mm per week. Story 3 showed that rapid expansion was followed by poor tissue repair, as the capillary network can hardly keep up with the separation
of the suture. Many clinicians feel that in the long term, expansion relapses to an extent that renders it valueless, whereas others use it routinely in their practice. The relapse does seem highly variable, but several studies 4,5 have shown that the widening of the vault is stable and it is the alveolus that tends to relapse. This would suggest that it is advantageous to separate the suture. Sandik£io-lu and Hazar appear to have had some difficulties in gaining cooperation with the patients who wore the semirapid appliances that were removable. I note from their figures that although the patients were asked to open at 1 mm per week, the effective rate over the 5.5 months was less than a fifth of a millimeter per week. In my clinical experience, that is too slow to open the suture and is not really
semirapid. This study could possibly be misleading in this respect. My own research 6 suggests that semirapid expansion is very stable. I could perhaps offer the authors some advice in gaining an effective rate of 1 mm per week. First, insist that the patients wear the appliance while eating. This may be impossible to start with, but children will hardly notice it in their mouth within 10 days. Second, open one eighth of a turn each day, not one quarter every other day. The periodontal membrane is approximately an eighth of a millimeter thick and so an eighth of a turn, distributed between the two sides, will only reduce it by half, not crush it. Also it is easier to remember something you do every day. Third, check the amount of opening at each visit, because if the rate of opening slows much below 1 mm per week, the suture will not separate and most of the widening