Achieving Predictable Results with Space Maintainers for Children Using a Novel Alginate Alternative
Joel H. Berg, DDS, MS; Jenn-Yih Lin, DDS, MS
Space maintenance of the primary dentition is one of the most critical services provided in pediatric dentistry.1 In cases where a primary molar is lost prematurely prior to its normal exfoliation time, there may be considerable consequences if the space is not maintained. Upon premature loss or extraction of primary molars, where the permanent first molars have not yet erupted, there is a high likelihood that space will be lost, thereby creating difficult consequences. It is essential to maintain any open space in the primary molar region prior to the loss of any space.2 Therefore, in cases where a primary molar is lost prior to its normal exfoliation and eruption of the first permanent molars, space maintenance should be employed.
There are several types of space maintainers that can be used. If a primary first molar is lost prior to the eruption of the permanent first molar, a band-and-loop (BAL) space maintainer is indicated. A BAL will effectively maintain the space previously occupied by the primary first molar until eruption of the permanent first molar, whereupon the interarch occlusion is established. If the second primary molar is lost prior to the eruption of the permanent first molar, a distal shoe-type space maintainer should be considered. Upon eruption of the permanent first molars, if the second primary molar on either side is lost, a lower-lingual holding arch (LLHA) can be used if the 4 permanent incisors have erupted. The LLHA could also be used if the second primary molars are lost on both sides.
Using a Custom-Made Space Maintainer
Regardless of the type of space maintainer employed, one that is custom-made is preferred. The technique to fabricate a custom-made space maintainer requires that a stainless steel band be placed on the abutment tooth and an impression be made to capture the space. Ideally, as soon as the clinician knows that the primary first molar is to be extracted, it is best to fabricate the BAL in advance, then extract the primary molar and immediately seat the custom-fabricated BAL. By adhering to this protocol, there will be little risk of losing any space at all, which can occur even in a matter of days following the extraction of a primary molar.
The technique to achieve this requires the following steps. First, a band is seated on the abutment tooth, and an impression is made to capture the quadrant in question. The band is then removed and placed into the impression to replicate its appropriate anatomical place. The impression is poured in stone, whereupon the “tooth” to be extracted is removed from the model. The space maintainer is then fabricated in the space on the model where the to-be-extracted tooth is located. The finished space maintainer is then tried and cemented in the patient.
Importance of Impression Making
One of the most critical steps in this process is accurately capturing the space in the mouth where the space maintainer will be placed. Making an accurate impression is essential in order to obtain a well-fitting and passive space maintainer. Historically, alginate has been used for this purpose. Alginate is generally an effective material for making space maintainer impressions because it is relatively easy to use, fairly well-tolerated by patients, and relatively inexpensive.
However, alginate demonstrates several negative aspects as a space maintainer impression material. It must be poured immediately to avoid distortion.3 Whereas “wrapping” an alginate impression with a moist towel until it is poured can be effective when it is used for a study model impression, the subtle distortions that may result from delayed pouring can create a challenging situation when alginate is used as a space maintainer impression material. It is often the case in a busy pediatric practice that the space maintainer impression cannot be poured for several hours.
Therefore, an alginate alternative has recently been developed that alleviates these concerns. An addition silicone material (StatusBlue®, Zenith Dental Products, Englewood, NJ) has been developed for use in any situation where alginate would normally be used.4 This material maintains the necessary flow characteristics of alginate while demonstrating preferred thixotropic properties. Most importantly, once the impression is made and the material is set, it is stable at room temperature, without requiring any type of special storage conditions. An impression made with the newer addition silicone material could actually be sent to a laboratory without being poured and still retain its dimensional stability.5,6
Technique for Using an Addition Silicone Alginate Alternative
The following represents the detailed sequence of steps to fabricate a space maintainer using the addition silicone alginate alternative.
1. An orthodontic band is placed on the abutment tooth from which the BAL space maintainer will emanate (Figure 1). This is generally the second primary molar. The band must be carefully fitted and contoured to fit the tooth (Figure 2).
2. Afterwards, the impression is made. The alginate alternative material made of addition silicone (StatusBlue) is available in 2 delivery/mixing systems. The first dispensing method is a standard automix cbodyridge/gun system (Figure 3), similar to those available for many impression materials. Additionally, the material can be mixed in a dynamic mixing machine (Figure 4) that allows on-demand expression of the precise amount of material required for the impression. This is a preferred system in environments where many impressions are made per day. When the alginate alternative material is dispensed from the mixing machine, clinicians can use a multi-use cbodyridge that can produce as many as 12 to 14 full-arch impressions and 20 to 25 quadrants per 390-ml cbodyridge.
In order to use the dynamic mixer (MixStar, Zenith Dental Products), a disposable cbodyridge tip is placed on the mixing machine. Mixing is initiated by depressing a button on the device and is completed by releasing the button. The material can be placed directly into the tray prior to making the impression (Figure 5). The tray is then placed into the mouth (Figure 6), and the material allowed to set. The novel alginate alternative material sets very quickly, usually in about 90 seconds from the time of mixing.
4. The band is then removed from the tooth and placed into the impression to approximate its appropriate position on the tooth (Figure 9). The band should then be stabilized in the impression using a small drop of cyanoacrylate adhesive or a wire or “stick wax”.
5. The impression is then carefully poured in stone. This can be delayed for hours or days without the risk of syneresis, which is a problem with alginate.
6. Upon separation of the model, the tooth that will be extracted can simply be ground away with a laboratory rotary tool or knife.
The technique presented for using an addition silicone alginate alternative offers the practitioner for children an easy option to facilitate the fabrication of high-quality space maintainers. Space maintenance for children is one of the most valuable services practitioners can provide, and this technique can dramatically impact the practitioner’s ability to achieve successful results. By using the mixing machine component, one can also take advantage of additional opportunities to use the material for other indications, including study model impressions, other types of space maintainers, and general use.
1. Bijoor RR, Kohli K. Contemporary space maintenance for the pediatric patient. N Y State Dent J. 2005;71(2):32-5.
2. Terlaje RD, Donly KJ. Treatment planning for space maintenance in the primary and mixed dentition. ASDC J Dent Child. 2001;68(2): 109-14, 80.
3. Hiraguchi H, Nakagawa H, Wakashima M, et al. Effect of storage period of alginate impressions following spray with disinfectant solutions on the dimensional accuracy and deformation of stone models. Dent Mater J. 2005;24(1): 36-42.
4. Chen SY, Liang WM, Chen FN. Factors affecting the accuracy of elastometric impression materials. J Dent. 2004;32(8):603-9.
5. Peutzfeldt A, Asmussen E. Accuracy of alginate and elastomeric impression materials. Scand J Dent Res. 1989;97(4):375-9.
6. Craig RG, Urquiola NJ, Liu CC. Comparison of commercial elastomeric impression materials. Oper Dent. 1990;15(3):94-104.
About the Authors
Joel H. Berg, DDS, MS
Professor and Chair
Depbodyment of Pediatric Dentistry
University of Washington
Jenn-Yih Lin, DDS, MS
Assistant Clinical Professor
Depbodyment of Pediatric Dentistry
University of Washington