An Updated Review of Salivary pH Effects on Polymethyl Methacrylate (PMMA)-Based Removable Dental Prostheses

Abstract

Salivary pH is a neglected factor that may affect the performance of removable dental prostheses (RDP). This study aimed to review literature in reference to the role of salivary pH on the performance of RDP and materials used for their fabrication. From January 1990 until December 2021, a search was done on PubMed, Scopus, and Web of Science databases using removable dental prostheses, salivary pH, PMMA, Denture base, and physical properties as keywords. Articles that met the inclusion criteria (full-length articles have investigated the effect of salivary pH on RDP materials in vitro and in vivo) were included. Out of 433 articles, 8 articles that met the inclusion criteria were included. All studies used artificial saliva with different salivary pH ranging between 3 and 14. Two articles investigated the role of salivary pH on the cytotoxicity of denture base resins and soft liner. One article studied the durability and retention of attachments, one article analyzed the performance of PEEK materials, one article researched the fatigue resistance of a denture base, one article investigated the corrosion of RPD framework cast and milled Co–Cr, one article studied the strength and clasp retention and deformation of acetal and PEEK materials, and one evaluated changes in mass and surface morphology of CAD–CAM fiber-reinforced composites for the prosthetic framework. Different salivary pH affected all included materials in this review except PEEK materials. The most adverse effect was reported with alkaline and acidic; however, the acidic showed the most deterioration effect. Salivary pH has a role in the selection of material used for RDP fabrication.

The Use of Acrylate Polymers in Dentistry

“…Using microwave post-polymerization, the amount of residual monomer can be reduced by up to 25%, which is a consequence of the additional conversion of MMA into polymer, and the evaporation of monomer [ 86 , 87 , 88 ]. The amount of residual monomer in samples of cold-polymerized acrylates was lowered to a clinically acceptable level with the aforementioned post-polymerization methods [ 89 ]. Post-polymerization treatments led to an improvement in the mechanical (crush stress) and biological properties of cold-polymerized acrylates, which can be explained by the reduction of the amount of residual monomer [ 90 ].…”

The Effect of Aging on Artificial Saliva at Different pH Values on the Color Stability of New Generation Denture Base Materials

“…In the contact of the polymer with saliva, some liquid absorption and release of monomers occur. The affinity of PMMA material for water absorption is independent of color pigments and dyes, and discoloration occurs with the absorbed water [ 4 ]. The degradation of acrylic resin material is explained in two ways: enzymatic reactions of saliva and hydrolysis of resin-containing materials.…”

“…However, changes in the quantity and quality of saliva occur with aging. Approximately half of all adults have been reported to have symptoms of gastroesophageal reflux disease (GERD) at some point in their lives [ 4 ]. Diseases such as GERD increase the acidity of the saliva.…”

A randomized controlled trial assessing denture adhesive efficacy on denture retention across 13 hours

“…Many of these edentulous patients will receive complete dentures as the treatment of choice 4 . Denture performance, including bite force and chewing efficiency, can be impacted by numerous biological factors such as changes in supportive tissue, salivary flow, and salivary pH 5,6 …”

“…ciency, can be impacted by numerous biological factors such as changes in supportive tissue, salivary flow, and salivary pH. 5,6 Denture adhesives (DAs) are one treatment modality used to enhance the retention of dentures. Systematic reviews and meta-analyses have demonstrated that DAs can provide significantly improved retention and stability, as well as increased patient satisfaction and comfort.…”