Preparation of Toothpaste

PREPARATION OF TOOTHPASTE

The preparation of toothpastes may be carried out by using two methods which are as follows:

·                               Dry gum method.

·                               Wet gum method.

1.           Dry Gum Method:

In this method, all the solid components of the formulation like abrasive agent, binding agent etc., except the surfactants are mixed together in a dry mixer. The mixer may be an agitation mixer which consists of slow rotating blades.

The liquid components such as the humectants and water are gradually added to the dry mix.

The mixing process is carried out till a smooth paste is formed.

The remaining ingredients like the surfactants and the flavouring agents are added to the homogenous paste under vacuum.

2. Wet Gum Method:

In this method, all the liquid components are mixed together to form a liquid phase. The binding agent is then mixed with the liquid phase with uniform stirring in order form mucilage.

The solid ingredients excluding the surfactants are then gradually added to the mucilage with uniform mixing in an agitation mixer, in order to form a homogenous paste.

The remaining ingredients i.e., the surfactants, the flavoring agents, coloring agents are added under vacuum t the homogenous paste.

Based on the principle involved in the above methods, some acceptable techniques have been proposed for the manufacture of toothpaste which is as follow:

1.            Cold compression technique: The preparation of toothpaste using this technique can be carried out as follows.

Initially, the humectants such as sorbitol (70% w/v) or glycerine are taken in the bowl of the mixer.

The binding agent is then sprinkled over the humectant under agitation for uniform dispersion.

The liquid components such as water, sweetener and the preservatives are mixed to form a separate liquid phase and any therapeutic additives if necessary are also added to the liquid phase.

This liquid phase is then added to the humectant-binder mixture in the bowl and mixing is carried out for 5 minutes in order to remove the air from the thick gelatinous liquid phase.

The vacuum is stopped and the abrasive agents are added with constant mixing until they are completely dissolved.

The vacuum is reapplied and mixing is continued for at least 30 minutes.

The surfactants and the flavouring agents are dispersed separately in 5% humectant. This mixture is added to the vacuum at the end and 5 minutes of additional mixing is carried out.

Finally, it leads to the formation of an air free smooth paste.

2.           Multiple Liquid Phase technique: This method is suitable for formulations that make use of carboxy methyl cellulose (CMC) and magnesium aluminium silicate hinder combination. The preparation can be carried out as follows:

Initially, hot water is taken in a mixer bowl and magnesium aluminium silicate is added to it.

The humectants, the flavouring agent, the binding agent and the preservatives are mixed separately to form a separate liquid phase.

This solution is then added to the mixer and the final volume is made using the humectants.

Vacuum is introduced into bowl in order to remove the air from the liquid mixture. The vacuum is removed and the abrasive agents are added and the vacuum is again introduced in the mixed for 30 minutes.

Finally, the surfactants are added with constant inking for 5 minutes. The method is also suitable for the preparation of clear-gel dentifrices.

3.             Hot Liquid Phase Technique: The method preparation using this technique is as follows:

In this method, the abrasive agent, binding agent and preservatives are mixed separately in a dry mixer.

The humectant, sweeteners and water are mixed separately and this liquid phase is heated.

The hot solution is then slowly added to dry powder with constant mixing.

The resultant mass is then mixed under vacuum for 30 minutes.

Finally, the solutions of the flavouring agent and the surfactant are added and vacuum, mixing is carried out for 5 more minutes.

A clear and homogeneous paste is formed by this method.