Alginate base to evade lingual trimming of the mandibular cast

Pouring a lower dentulous impression, retrieving the cast and later trimming of the cast in lingual vestibular area has always been a nuisance to most of the dentists and orthodontists [Figure 1a and b]. This step can be simplified and later trimming of the cast in the lingual vestibular area can be avoided by incorporating a simple step after impression taking in routine clinical practice.

Figure 1.

(a and b) Lower impression and retrieved cast without lingual alginate base

After the impression is taken for the mandibular arch, it is washed thoroughly and examined for the presence of any voids and to ensure that the lingual flange of the impression is well-adapted to the impression tray. Now, one scoop of alginate impression material is mixed separately and is added to the tongue space area of the lower impression and molded with thumb and fingers to form a flat base. Care is taken to avoid any overflow of alginate material into the lingual flange of the impression and hence, it is better to add alginate slightly below the lingual border of impression. The impression is now poured with dental stone in a routine manner. Figure 1a and b, Figure 2a and b show the lower impression and the retrieved cast of the same patient without and with lingual alginate base respectively. The smooth lingual base of the lower cast can be very well-appreciated in Figure 2b. This simple step saves the time and efforts required to trim the excess of dental stone and shape the lingual vestibule area of the lower cast. Furthermore, it leads to increased strength of the lower dental cast, which reduces the chances of fracture of lower cast while retrieving it from the impression. The first author observed and used this procedure at Faculty of Dentistry, University of Sydney, Australia and found it useful.

Figure 2.

(a and b) Lower impression and retrieved cast with lingual alginate base