Material and methods

Fourteen completely edentulous patients, in need of complete dentures, for the first time, were selected from the patients out clinic, Oral and dental medicine, Al Azhar University-Boys. The patient's age ranged from 45 to 60 years. The study protocol was approved by the Medical Research Ethics Committee (MREC: 18/081) of the National Research Centre. An informed written consent according was obtained from each participant before clinical procedures. All the participants were fulfilling the following inclusion criteria:

1. No previous denture experiences.
2. All of them were free of any systemic or local diseases that induce immune-competence reactions.
3. All were non-smokers.
4. They did not use any drugs that affect the oral mucosa.
5. They all were Angle Class I maxilla-mandibular relation.

Complete dentures construction

Patients were divided into two groups. In the first group (I) the acrylic resin (Across one, Dental & Medical Co, Egypt) complete maxillary and mandibular dentures without base reinforcement were delivered to the patients. The dentures were constructed following conventional procedures. In the second group (II), only the mandibular dentures were reinforced using a light cured resin impregnated with e-glass fibres meshwork (fibre force®, SYNCA, Canada). For the mandibular dentures, the reinforcement mesh was adjusted to the master cast with a 0.6 mm wax spacer.

On the waxed cast, four tissue stops were created using light-cured acrylic resin (SYNCA, Canada) supplied by the manufacturer. Then, the mesh was adapted to the cast using a vacuum unit (EZ VAC, SYNCA, Canada) and cured using the LED light curing unit (Dental Lab LED Light Cure Box, Taiwan) at 430 to 500 nm for 2 minutes. The cured meshwork was removed from the cast, flushed with boiling water stream to remove any was remnants and dried.

The lower dentures were processed using the conventional method as the first group except that before flash closure the meshwork was placed on the master cast then packing and curing was performed. Thus, the meshwork bonded chemically to the denture acrylic resin.

Immunologic evaluation

Salivary sample collection: The samples were collected at four different time intervals:

1. immediately before denture insertion (as control),
2. two hours after complete denture delivery
3. three days after complete denture delivery
4. 7 days after complete denture delivery.

Before collection of salivary samples, all patients were instructed not to ingest food or drinks (except water) at least for 60 minutes. The samples were collected between 10-11 AM to prevent any differences in the concentration of the saliva due to the circadian rhythm.

Ten millilitres of patient's saliva was collected in sterile plastic containers using passive drool technique. Then they were centrifuged at 3000 rpm for 15 minutes and the samples supernatant stored in a deep freezer at -20 degree and they were kept for analysis. The level of salivary IgA in the samples was assessed by using enzyme-linked immunosorbent assay (ELISA) (kit: Peritest, Robonik, India) and expressed as mg/dL.

Statistical analysis was performed using with SPSS 20^® (Statistical Package for Social Science) and Microsoft Excel 2010. Data were represented as means (M) and standard deviation (SD).

Comparison of data within each group was made using one-way ANOVA followed by Tukey's post-hoc test to evaluate the effect of time on the level of salivary IgA. Also, independent t-test was performed to detect the significance between both groups for each follow-up visit. The significant level was set at P ≤ 0.05.