The current study was conducted in the Department of Prosthodontics, SIBAR Institute of Dental Sciences, Guntur, Andhra Pradesh. The aim of the study was to evaluate the weight reduction of acrylic resin in the denture prosthesis via different materials. There were four groups, one control and three study groups and the sample size in each group was 10. To compare between the study and control groups it was necessary to standardize the samples. The accessory materials selected for study groups were bean balls, cellulose balls and polyacrylic fibers. Evaluation of the weight reduction using a denture is a cumbersome procedure. So, to get a uniform mold space for all the samples, table tennis balls were selected and flasked individually [Table/Fig-1]. After the flasking procedure the flask parts were separated and the table tennis balls were retrieved [Table/Fig-2].

[Table/Fig-1]:

Flasking of table tennis ball.

[Table/Fig-2]:

Mold space that was created after dewaxing.

Now, a uniform outer space was created and the next important task was to create a uniform inner mold space too. For that reason a glass marble of diameter smaller than that of table tennis ball was selected and duplicated by putty. In order to the created mold space by the glass marble, regular body poly vinyl siloxane material was injected and allowed to set [Table/Fig-3]. Later for the purpose of suspending the elastomeric ball and to create a uniform space equally, a 20 gauge wire was inserted through and through the elastomeric ball [Table/Fig-4,5].

[Table/Fig-3]:

Making of elastomeric ball by regular body for creating uniform inner mold space

[Table/Fig-4]:

Suspension of elastomeric ball by 20 gauge wire.

[Table/Fig-5]:

Uniform inner mold space created by suspended elastomeric ball.

In control group all the samples were completely solid and in study group all the samples were packed with the obtained mold space by elastomeric ball during trial closure with the three different study groups i.e. bean balls [Table/Fig-6], polyacrylic fibers [Table/Fig-7] and cellulose balls [Table/Fig-8]. After bench curing, the normal polymerization procedure was carried out. The processed balls were retrieved, finished and polished. Finally the weights of all the processed 40 acrylic balls were measured electronically [Table/Fig-9].

[Table/Fig-6]:

Packing of bean balls into the inner mold space.

[Table/Fig-7]:

Packing of polyacrylic fibers into the inner mold space.

[Table/Fig-8]:

Packing of cellulose balls into the inner mold space.

[Table/Fig-9]:

Measuring each sample weight by electronic weighing machine.

All the observations were tabulated [Table/Fig-10] and subjected to statistical analysis for their mean and standard deviation [Table/Fig-11] by paired t-test. The obtained means by the study groups were compared with the control group for amount of weight reduction in percentage by a formula given by Kobayashi K, Shimoda S, Nakagawa Y, Yamamoto A [15].

Here, Error denotes weight reduction; A denotes mean in study group; B denotes mean in control group.

The results of all the four groups that were elicited in [Table/Fig-10,11] were obtained by paired t-test and the values were found to be statistically significant (p-value was 0.0001). The means of all the groups were substituted accordingly in the above mentioned formula given by Kobayashi K, Shimoda S, Nakagawa Y, Yamamoto A [15]. From that formula %weight reduction of the study groups was calculated. Study group I i.e., bean balls group produced 31.3% weight reduction, whereas cellulose balls group produced 27.4% and polyacrylic fibers group produced 24.5%. Tabular and graphical representations of % weight reduction were elicited in [Table/Fig-12,13]. The reason for bean balls group to produce highest weight reduction among all the study groups was they occupy more volume and at the same time produce less weight to the prosthesis.

[Table/Fig-13]:

Graphical representation of the weight reduction (%) of study groups in comparison with control group.

Due to the developmental or acquired defects of the maxilla and in cases of increased ridge resorption, the maxillary rim length is increased, that in turn increases the weight of the maxillary denture. If conventional maxillary denture is constructed in such a situation then it would result in increased weight of the maxillary denture that may result into resorption of maxillary edentulous foundation at a higher rate. As said by O’Sullivan et al., heavy maxillary denture may further compound the poor denture-bearing ability of the tissues and lead to decreased retention and resistance [1]. However, reducing the weight of the maxillary prosthesis by making the maxillary denture hollow has been shown to be beneficial [16].

Hollowing the denture in denture weight reduction is not a recent concept. However, the problems associated in creating the hollowness remains the same till date. Kalavathy et al., stated that to increase the retention and stability of heavy prosthesis, many methods have been tried like utilizing the undercuts, modifying the impression technique, use of magnets and use of implants, etc., [17]. There were several materials that were tried to create hollowness as mentioned previously. However, each material has its own pros and cons, and at the end these materials have to be retrieved either by placing holes near the packed region or by altering the tissue surface of the denture, which was an unacceptable as well as a cumbersome procedure. Several methods were also proposed by different people like Fattore et al., [13] double flask technique, Holt [4] technique, Worley & Kniejski [14] technique, O’Sullivan et al., [1] clear matrix method. But, these procedures are a bit difficult and were technique sensitive.

The main reason behind hollowing the denture is to reduce the denture weight. If the same be achieved without retrieving the accessory material, that would put an end to these problems. That same thought had led us to propose this new technique of weight reduction. But to achieve the same the packed materials must be of lesser weight than the polymer and at the same time should occupy more volume. After a long research, we have finalized these materials i.e. bean balls, cellulose balls and polyacrylic fibers, these materials occupy more volume and also have lesser weight than acrylic polymer.

As we are leaving them in the prosthesis itself and at the same time were not creating any hollowness, we can’t justify the name hollow to this prosthesis. So, we came up with a new word called ‘Wispy’. Wispy is a synonym for feathery. This wispy prosthesis eliminates the above mentioned problems and is much handy for the operator and even more convenient in delivering the prosthesis with reduced weight. This wispy prosthesis is advantageous when compared with the previous ones because the main motto of reducing the prosthesis weight is being solved without creating any hollowness and at the same time has very minimal disadvantages like trial closure is must for packing the accessory materials, that too in speculated time. For that reason the operator should be as quick as possible.

So, we proudly say that this wispy prosthesis brings a revolutionary change in reducing the prosthesis weight as the cumbersome and laborious procedure of removing the packed material as seen in previous methods was not necessary.

During the packing procedure trial closure has to be done, for creating hollowness and to pack these accessory materials. The operator must be very quick enough to do the above mentioned steps in the speculated time.

The novel technique described in the article will eliminate the above mentioned problems as the packed material need not be retrieved and at the same time will reduce the weight of the prosthesis. In this short study, every study group has produced a significant reduction in denture weight but among all, the bean balls group produced the most. Using which material in prosthesis weight reduction entirely depends on the operator choice.