Preparation and modifying a new type of waxes

Aim: To prepare and modify different wax compositions in order to find out the most suitable formula that has almost the same properties of dental modeling wax used in dentistry. Materials and Methods: Three groups of waxes (220 samples) with different compositions regarding its origin (Al–Dora refinery waxes, natural bees wax–North of Iraq, and commercially available Iraqi waxes), additives such as starch, sodium–carboxyl methylcellulose (Na–CMC), rosin, or nylon, and coloring agents were prepared. The samples were tested for their melting range, 21 samples only had a melting range that nearly coincides with that of the dental waxes such as Major and Cavex. Results: The resultant 21 samples were tested for their softening, trimming, penetration, residue materials and solubility. Only 4 samples showed properties that are closely similar to that of Major and Cavex wax. The results of melting point ranged from 69–80C. Softening test showed that the samples which contain nylon, Na– CMC, or rosin were softened without adhering to the fingers. Trimming test showed that they were trimmed easily and clearly. Penetration test showed that, some samples had the similar measurements of Major and Cavex wax (0.6–0.9mm). Residue materials showed that all samples had no residue of wax materials on acrylic teeth after wax elimination procedure. All the prepared waxes were soluble in ether (acetone), and petroleum spirit (benzene). Conclusion: Six new modeling wax materials were prepared according to ADA specification No.24. Three of new wax materials consist of nylon (polystyrene 1.71–2.13%); the other two novel modeling waxes were fabricated by using additive materials (Na–CMC and rosin).


INTRODUCTION
The major components of dental waxes may be of minerals, plants, animals, and insects. Waxes may be divided into two categories: Natural waxes (plant, insect and animal waxes), and synthetic waxes. (1) Waxes are generally characterized by their thermal properties such as melting point and solid-solid transition temperature that is closely related to the softening temperature observed in practice. (2) Previously, two types of wax were formulated in Iraq, boxing wax (3) and inlay dental wax (4) from the waxes purchased from Al-Dora Refinery Center, and that available in the Iraqi market Another type of wax used in dentistry is modeling wax. It is used as a pattern material for the registration of jaw relationship, also for setting up of artificial teeth in the procedure for a full denture. (1) Modeling waxes used for clinical procedures should show little or no dimensional changes when they are heated to mouth temperature. (5,6) Few formulas are found in the literature for modeling wax. This wax may contain 70 to 80% paraffin-base waxes or commercial ceresin, with small quantities of other waxes, resins, and additives to develop the specific qualities desired in the wax. (7)(8)(9)(10)(11) Preparation and modifying a new type of waxes This research aimed to prepare wax, and test some of its properties to find the most suitable dental modeling wax formula in comparison with the commercial brands of modeling dental wax used in clinical prosthodontic applications, and to prepare other modeling wax using additive materials.

MATERIALS AND METHODS
The materials used to fabricate new modeling wax materials were listed in Tables (1) and (2).
There is no published information on the percentage, main composition, and additive materials of modeling wax with its properties. A pilot study was done to fabricate a novel Iraqi modeling wax material. Two hundred and twenty samples from three groups of waxes with different compositions regarding its origin (Al-Dora refinery waxes, natural bees wax, and commercially available Iraqi waxes), additives such as starch, sodium-carboxyl methylcellulose (Na-CMC), rosin, or nylon, were prepared. The samples were tested for their melting point. The results of the pilot study showed that 21 samples only had a melting point that nearly coincides with that of the dental waxes such as Major Prodtti Denta-ri SPA, Italy, and Cavex-Italy modeling wax. These tests were done first by mixing 85% of paraffin (hard and soft) wax and 15% additive material. Then novel modeling waxes were fabricated by fixing one percentage of material and change the other components gradually (1% of paraffin and 0.01% of additives). The resultant 21 samples were tested for their softening, trimming, penetration, residue materials and solubility. The experimental design of novel modeling wax was done according to the following groups: Group 1: The samples were fabricated from hard paraffin, soft paraffin, and bees wax (natural pure and impure-North of Iraq). These samples were compared with samples consist of additive materials [nylon (polystyrene), and ferrous oxide coloring agent]. Group 2: The samples were fabricated from commercially available wax materials, and pure bees wax. These samples were compared with samples consist of additive materials such as rosin, and coloring agent. (11,12) Group 3: The samples were fabricated from commercially available wax materials, pure beeswax, and additive materials either starch, or Na-CMC, or by adding 5-15% one brand of modeling wax (Major Prodtti Dentari SPA, Italy), and coloring agent.
The new modeling waxes were subjected to the following tests: The samples were prepared by the following general methods: The mixing of wax was done by mixing different percentages of paraffin wax, and other additives in shaking water bath unit (Kavo GmbH, West Germany) (Figure 1) at 45-50ºC for five minutes to obtain homogenous mixture liquid. Then the liquid mixture was poured in special mold according to the type of test and left to cool at room temperature (25 + 2 ºC).
Bees wax used in this study was a natural wax either pure or impure. Pure bees wax was prepared by adding natural impure wax to boiling water, and then cooling the water to 5ºC to take the pure wax that floats on the water surface. The addition of coloring agent (ferrous oxide) at 43ºC before melting point was done with mixing.

Melting point: The mold used in this
test was a cylinder of 2cm in diameter, and 2.5 cm in length to determine the melting point. The melting point was measured according to a method reported by Vogel (13) using Electro thermal melting point apparatus (CE, VWR. International) (Figure 2).

Softening test:
The samples were softened to 40-45 ºC by the thermostatically controlled water bath unit (Kavo GmbH, West Germany) and tested by finger according to the ADA Specification No. 24 to determine the adherence of soft wax material.

Penetration test:
The samples were prepared with dimensions 10mm diameter, and 6 mm thickness (ADA Specification No. 24), and softened to 40-45 ºC by the thermostatically controlled water bath unit (Kavo GmbH, West Germany), and tested by a standard Vicat apparatus (Baustoff Pruf Toni Technik) at 25 ºC.

Residue material:
A silicone putty material (ORMASIL, Major Prodotti Dentari SPA, Italy) was used to prepare a special rubber mold with 5 mm diameter and 2.5 mm thickness that represents the usual thickness of denture base (ADA Specification No. 12). (14) The novel wax was melted in a thermostatically controlled water bath unit (Kavo GmbH, West Germany), and kept at a constant temperature of 60 ºC. The mold was adapted on a surveyor. The melting wax was poured into the mold and immediately a first premolar tooth was inserted in the softened wax.
Each tooth was mounted on the surveyor for easy insertion of the neck of the tooth in the softened wax, and left to cool at room temperature for 15 minutes to prepare the wax pattern.
Flasking was made in the conventional method: The flask was left on the bench for 2 hours at room temperature (23 + 2 ºC) after the final set of the plaster. The wax was removed from the mold by immersion of the metal flask in boiling water for 4 minutes. (15) Then the flask was removed from boiling water, carefully opened and flushed by application of boiling solution of synthetic household detergent (1 tablespoon to 1 pint of water), and then rinsed with clean boiling water.
Each neck of tooth was tested by visual examination, and by using a reflecting microscope ×30 magnification) to detect the presence of residue on the neck of the tooth according to ADA Specification No. 24. (14) 6. Solubility test: This test was done to determine the weight of the samples before and after immersion. One gram of each novel of modeling wax material was immersed in 10 ml of solvent [acetone (ether), chloroform, benzene, methanol, or tetrachlorocarbon] for 10 minutes at room temperature. Filtrations were done and weight of the remaining material was measured by Electronic balance (Mettler PM460, Germany). Descriptive and percentage statistical analysis tests were used in this study.

RESULTS AND DISCUSSION
On the basis of results from experimental preparation, the evaluation of dental composition of the prepared wax was studied. Twenty-one samples of 220 were selected to complete this study because the properties of these samples nearly coincide with the other brands of modeling wax. (9,14,16,17) This formulation is hard paraffin wax, soft paraffin wax, bees wax (pure and impure), and nylon (polystyrene) ( Table 3). Hard paraffin is a mixture of purified solid saturated hydrocarbons, generally obtained from crude paraffin waxes during the production of petroleum oils. (18,19) The other formulation showed nearly similar to the other brands of modeling wax consisting of commercial paraffin wax, bees wax, and rosin, or Na-CMC material (Table 4 and 5).    (Table 7). These results were agreed with other studies. (1,9) This is because modeling wax is largely a paraffin wax with some additions. The melting point was approximately 58 ºC and the transition temperature was approximately 50 ºC. Thus, all manipulation of modeling wax should be carried out above the latter temperature to minimize stress relief. (1,10)

Softening test:
The results of this study showed that wax samples containing additive materials (nylon, or (Na-CMC), or rosin) were softened without adhering to the fingers (Tables 6 and 7

CONCLUSION
Six recommended modeling wax material samples (no. 3, 5, 14, 17 and 18) were prepared. Three of them consisted of nylon (polystyrene 1.71-2.13%). The other two novel modeling waxes were fabricated by using additive materials (Na-CMC, and rosin) with the following properties according to ADA Specification No. 24: Melting point ranged between 63-75 ºC, which was similar to other brands of modeling wax (Major and Cavex Wax).
Softening, penetration, trimming, and residue material properties showed that 6 samples of the 220 had nearly the same properties of other brands of modeling wax materials. Solubility of the prepared materials showed the same results as the commercial products.