Discussion

S-IgA has an important role in the defensive mechanism where it participates in the immune reaction and protection of the mucous membrane of the oral cavity. Furthermore, S-IgA concentration is related to the physiological status of the body and oral cavity. The decrease in the level of S-IgA was reported to be associated with the increased risk for oral pathology. On the other hand, the increase of S-IgA level had been correlated with low caries rate.

This study was planned to explore whether or not dentures reinforced with light cured resin impregnated E-glass fibres would affect the level of S-IgA in vivo compared to conventional acrylic resin dentures.

Only, healthy completely edentulous male patients with age ranging from 45 to 60 years participated in the study to exclude the possible effect of sex, age and general health status on the level of S-IgA.

To assess levels of S-IgA in saliva, unstimulated salivary samples were collected using passive drool method in the present study as it is simple, inexpensive, acceptable for the analysis and more tolerable to the patients. Furthermore, the procedure of salivary stimulation increased the salivary flow rate which in turn decreases the concentration of S-IgA.

In the present study, the measurement of the S-IgA levels was performed using ELISA technique as it is a highly accurate method to detect salivary biomarkers including S-IgA.

The use of light-cured resin impregnated E-glass fibres mesh was selected in the study as it eliminates the difficulties in the manipulation of E-glass fibres. Curing of the reinforcing mesh using a light curing unit is another advantage to be considered. Besides, it provides better fracture resistance as supported by previous studies.

The findings of the present study revealed that insertion of complete dentures caused a progressive continuous increase in the S-IgA levels till the end of the follow-up periods in both groups. These findings are by the previous study conducted by Corega et al., 2014, and Youness et all., 2015, who observed that insertion of orthodontic appliances increased the concentration of S-IgA. The apparent increase in the S-IgA could be attributed to two main reasons. The first reason could be due to hyper-salivation and the stress associated with the insertion of the new prostheses. The second could be attributed to the leaching of toxec compounds from an acrylic resin material as residual monomers and plasticizers which may initiate immunogenic response. However, the present finding is in disagreement with a previous study conducted by wessam et al., who reported that insertion of complete dentures made fo different denture base materials, resulted in the decrease of the level of S-IgA.

Although, the result also demonstrated an increase in S-IgA level in patients wearing reinforced denture bases compared to conventional dentures. The difference were not statistically significant.

Therefore, it could be proposed that denture acrylic resin material rather than E-glass reinforcement mesh may be the main cause for an increased level of S-IgA in both groups. Furthermore, the increase S-IgA level in reinforced dentures could be attributed to the impregnation process of glass fibres acrylic resin as reported by Sipahi et al., 2006. Who mentioned that this requires an increase in the ratio of monomer.

Within the limitation of the present study, it could be concluded that:

1. Insertion of complete dentures constructed from heat cured acrylic resin affects the level of salivary IgA which initiates the immune response.
2. Reinforcement of dentures with light cured resin impregnated E-glass fibres mesh showed no significant differences compared to heat cured acrylic resin. However, further clinical studies for a prolonged follow-up periods are required to detect the possible side effects such as allergic responses and systemic toxicity.
3. Laboratory investigations are also needed to assess all cytotoxicity.