Soft lining to relieve soreness beneath dentures

Lased and sandblasted denture base surface preparations affecting resilient liner bonding

STATEMENT OF PROBLEM

Adhesive failure between the liner and the denture base creates an environment for potential bacterial growth and accelerated breakdown of the soft liner resulting in a deteriorating prosthesis.

PURPOSE

This study evaluated the effects of a specific sandblasted or lased preparation on the interfacial bonding of polymethyl methacrylate and silicone and polyethyl methacrylate resilient liners.

MATERIAL AND METHODS

Polymethyl methacrylate test specimens were fabricated and received one of three surface treatments: untreated (control), sandblasted (250 microns aluminum oxide particles), and lased (carbon dioxide). Polyethyl methacrylate and silicone resilient lining materials were applied to these surfaces and the peel strengths were determined with the American Society for Testing and Materials peelin-adhesion test.

RESULTS

Altering the polymethyl methacrylate surface by sandblasting significantly reduced the peel strengths for the polymethyl methacrylate/polyethyl methacrylate and polymethyl methacrylate/silicone specimens. Altering the polymethyl methacrylate surface by delivering carbon dioxide laser energy to form a grid pattern produced lower peel strengths that were statistically significant from the controls for the polymethyl methacrylate/polyethyl methacrylate specimens, but not so for the polymethyl methacrylate/silicone specimens. Untreated polymethyl methacrylate/polyethyl methacrylate peel strengths were significantly higher than polymethyl methacrylate/silicone.

CONCLUSIONS

Results of this study imply that mechanical surface preparation of denture bases before application of a resilient liner may not be warranted.

Observations on long-term use of a soft-lining material for mandibular complete dentures

There has been ample evidence for short-term clinical success of Molloplast-b soft-lining materials, but their use has been discouraged because of an assumed need for frequent replacement. This article presents observations on 22 patients who were provided with Molloplast-b soft-lining materials in their mandibular complete dentures for up to 9 years. Fifteen of the patients were still wearing soft-lined dentures; four had been provided with implant-supported overdentures and two had converted to hard-based dentures. In nine patients occlusal wear was a reason cited for the need to replace the complete dentures, indicating that the soft-lining material had outlasted the acrylic resin teeth.

Color stability of long-term soft denture liners

The use of resilient denture liners in complete denture construction has become increasingly popular for providing comfort for denture wearers. The primary disadvantage of these materials is that the physical and mechanical properties change rapidly with time in a service environment. The purpose of this study is to evaluate the color stability of five commercially available soft denture liners as a function of accelerated aging. Color measurements were made before aging with a colorimeter and data processor. The samples were then weathered for 100 hours in an accelerated aging chamber in the presence of a xenon ultraviolet visible-light source, an intermittent water spray at 110 degrees F, and 90% humidity. After aging, color measurements were made again and color differences (delta E) were calculated. Results were statistically tested with analysis of variance and Scheffé intervals were calculated at 0.96. It was concluded that accelerated aging can be used to evaluate color stability of soft denture liners.

Twenty-five years of clinical application of a heat-cured silicone rubber

The use of Molloplast-B silicone rubber for the past 25 years is reviewed. A variety of applications as well as techniques are described. The liner has shown to be acceptable to patients and has aided in their rehabilitation. This processed soft liner is still a viable alternative, even with today's trends in removable prosthodontic service.

Denture soft lining materials: clinical indications

The success or failure of a soft lining in a denture is dependent not only upon the physical properties of the material employed, but also on an understanding of the intended function of this group of products, and the physiological and biological properties of the resilient oral tissues upon which the denture rests. This paper identifies the clinical factors that must be reviewed in order to assess the need for and likely success of a denture soft lining material.

The use of a soft denture liner for chronic residual ridge soreness

Chronic residual ridge soreness in patients with complete dentures can be caused by various factors. A differential diagnosis between physiologic or anatomic problems (or both) and functional deficiencies in the patient's present dentures must be made. The functional deficiencies can often be eliminated easily, whereas physiologic and anatomic problems may be more difficult to correct, especially in the geriatric patient. If the functional deficiencies in the patient's dentures have been corrected and surgical procedures are not a viable alternative, placement of a long-term resilient liner can often resolve the chronic residual ridge soreness that is present in denture patients. Properly placed and properly cared for silicone or silicone rubber resilient denture liners can provide comfort for over 70% of patients with chronic residual ridge soreness for 3 to 5 years and often longer.

A six-year retrospective study of Molloplast-B-lined dentures. Part II: Liner serviceability

A 6-year retrospective investigation was conducted into the serviceability of Molloplast-B-lined dentures with the following results: The Molloplast-B-lined denture is not a temporary expedient but can remain serviceable for a time competitive with that of conventional acrylic resin dentures. All the soft liners were still serviceable after 4 years and 83% after 6 years. The longevity of the soft liner is dependent on correct processing procedures and proper home care. The three liners judged as unserviceable exhibited excessive wrinkling, and all had been soaked in a bleach-type cleanser. The resilience of the liner is dependent on its thickness. The optimum thickness is approximately 3 mm. The resilience of the liner did not decrease with time. No noticeable wear of the soft liner was observed. Staining was present in about half the soft liners. Smoking was commonly associated with staining and odor of the soft liner.

A six-year retrospective study of Molloplast-B-lined dentures. Part I: Patient response

A 6-year retrospective investigation elicited patient response to wearing Molloplast-B-lined dentures with the following results: 1. For nearly all the patients wearing a Molloplast-B-lined denture, their ability to wear it comfortably outweighs its disadvantages. 2. Nearly all the patients (95.4%) would elect to have a new soft-lined denture should their present one need replacement. 3. Nearly all the patients (93%) thought that their soft-lined dentures were more comfortable than their previous conventional acrylic resin ones. 4. Molloplast-B-lined dentures offered comfort to a significant number of patients in this study who had had a history of chronic discomfort with the wearing of conventional acrylic resin dentures. 5. The presence of a retracted tongue habit is likely to decrease the patient's satisfaction with the dentures.

Clinical study of a heat-cured silicone soft lining material

Thirty-seven mandibular dentures lined with Molloplast B silicone material were examined after they had been worn for 2-8 weeks and 6, 18 and 30 months. The denture wearers were also examined and interviewed. The colour was found to have become lighter in 46% and turned yellow or brown in 51%; the denture base had worn through in 24% and there was a failure on bond in 22%; no hardening of the material was noted; 24% of the dentures had broken. An unusual taste was reported by 22% and smell by 14% of the denture wearers; mucosal soreness was noted in 14%; denture stomatitis developed in 48%; hygiene was poor in 61% and fungal growth was traced in 81% of the dentures; 73% of the patients were satisfied with the soft lining.

Mycotic growth and soft denture lining materials

Mycotic flora was studied from the dentures and denture bearing mucosae of 39 persons who wore soft-lined (Molloplast B) mandibular dentures and heat-cured acrylic resin maxillary dentures. Fungal growth was detected in 85% of the mandibular dentures and in 44% of the maxillary dentures (p less than 0.001). On the mandibular mucosa fungal growth was revealed in 74% and on the mucosa of the maxilla in 69%. In connection with inflamed mucosae fungal growth was always detected on the mandibular denture and on the mandibular mucosa in 93% as well as on the maxillary denture in 50% and on the maxillary mucosa in 75%. Considering the healthy mandibular mucosa fungus was found in 75% on the mandibular dentures and in 62% on the mucous membranes. In connection with healthy maxillary mucosae the corresponding figures were 42% and 68%. The specimens revealed 7 different yeasts and 2 moulds. The most common fungi were Candida albicans (86%), Torulopsis glabrata (31%), and C. tropicalis (14%). The uncured Molloplast material caused a definite inhibition of candida growth in vitro, while the cured material indicated no growth inhibition.