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PubMedDate not supplied

Flexural strength at the proportional limit of a denture base material relined with four different denture reline materials.

This study evaluated the resistance to plastic deformation under a flexural load (PLf) of a denture base material relined with four different types of denture reline materials. A heat-processed poly(methyl methacrylate) denture base was relined with varying thicknesses of denture reline materials and subjected to a flexural load. The flexural load at the proportional limit (PLf) was recorded. The PLf of the bulk denture base and denture reline materials were also measured for comparison. All relined denture bases showed significantly lower PLf than the bulk denture base. Generally, the PLf of the reline-denture base composite progressively decreased with an increasing proportional thickness of the reline material.

Analysis of Variance↗
PubMed2004

Influence of loading positions of mandibular unilateral distal extension removable partial dentures on movements of abutment tooth and denture base.

PURPOSE: The aim of our study was to explore the effects of different loading positions on the movements of the abutment tooth and denture base of removable partial denture with unilaterally designed framework (RPD-U). MATERIALS AND METHODS: The experiment was carried out with a simulation model of a mandible without left molars. The movements of abutment tooth and denture base of the unilateral and bilateral designs were due to 30N vertical load on 12 loading positions determined with a strain gauge circuitry. The effects of loading positions on the movements of the abutment tooth and denture base were compared between two designs. RESULTS: During the loading on buccal, lingual positions, and the most disto-central position the movements of the abutment tooth and denture base of the unilateral design were significantly greater than those of the bilateral design (P < 0.01). During the loading on the three mesio-central positions the movements of the abutment tooth and denture base were equal between designs, and were significantly lower than during the loading on the other positions (P < 0.01). CONCLUSION: Ending the denture teeth at the mesial cusp of second molar and positioning the occlusal contacts over the ridge crest adequately stabilize the abutment tooth and denture base of RPD-U.

Acrylic Resins↗
PubMed1992

[Local compressibility of denture foundation--evaluation of denture foundation in relation to impression pressure].

The viscoelastic character of the denture foundation is different in each individual or site. The character of the mucosa and the appropriate impression procedure should be examined. However, few investigations concerning the relation between the compressibility of the denture foundation and the impression pressure have been reported. The purpose of this study was to discuss the objective evaluation of the denture foundation in relation to the impression pressure. In this report, the local compressibility of the denture foundation of 20 upper edentulous patients was measured with the 20 MHz B-Mode ultrasonic diagnostic equipment. The Compressible Index was defined to analyze the compressibility of the denture foundation quantitatively as against the impression pressure. The main results were as follows: 1. The compressible amount of the denture foundation against 100 gw/cm2 pressurization was an average of 0.32-0.61 mm. 2. The compressible rate of the denture foundation against 100 gw/cm2 pressurization was an average of 13.5-20.7%. 3. The Compressible Index was confirmed to represent the compressibility of the denture foundation accurately as against the impression pressure. 4. It was suggested that the Compressible Index was useful for the clinical simple evaluation of the denture foundation.

Aged↗
PubMed2004

Effects of short-term adaptation to new complete dentures on perception thresholds for interocclusal thickness in experienced and non-experienced denture wearers.

BACKGROUND: The ability of patients to discriminate thickness can change with time after the insertion of new complete dentures, and this adaptation may differ according to the experiences of the patients. If so, an education program to reinforce the oral functions may be needed. This study was to evaluate patients' ability to discriminate thickness by comparing experienced and non-experienced denture wearers after the insertion of new complete dentures. METHODS: Forty edentulous patients with a skeletal Class I jaw relationship without any temporomandibular disturbances were in the study. After insertion of new complete dentures, all patients were tested for discrimination threshold for interocclusal thickness. The thickness perception test was repeated on days 1, 7, and 30 after the insertion of new dentures. The discriminatory ability was assessed with steel and aluminium foils placed between the upper and lower central incisor teeth. The records included the duration of wearing dentures. The data were subjected to statistical analysis of two-way ANOVA, multiple comparison test and Student's t test. RESULTS: Discrimination of tactile ability significantly increased over 30 days in experienced denture wearers as compared with non-experienced patients (P < 0.001). The difference in thickness perception threshold was statistically significant between the two groups (P < 0.001). CONCLUSION: Adaptation and denture experience can affect thickness discrimination of complete denture wearers.

Aged↗
PubMed1991

Longitudinal study on forces transmitted from denture base to retainers of lower free-end saddle dentures with Aker's clasps.

The aim of this study was to make a longitudinal analysis of the forces transmitted from denture base to retainers of lower free-end saddle dentures with Aker's clasps using a newly developed transducer. The experimental apparatus consisted of two components, a metal framework and a denture base embedded with a force-detecting unit. This device was the transducer, which could detect changes in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured on several separate occasions from the insertion of new dentures to about 4 months afterwards. The result are summarized as follows: (i) the maximal mean value of vertical forces transmitted from denture base to retainers was decreased after 1 week of insertion of new dentures, then increased and reached a constant level (about 10N) 4-6 weeks after the insertion of new dentures; (ii) there were large differences in the maximal mean value of lateral forces between subjects.

Aged↗
PubMed1984

Oral hygiene, dental visits and age of denture for prevalence of denture stomatitis.

A representative sample of Finnish denture wearers (n = 3875) aged 30 or over were examined clinically and interviewed about their oral hygiene habits, use of dental services and possible prosthetic treatment during last visit to a dentist. Of these denture wearers, over 80% brushed their dentures at least once a day, and 16% visited a dentist at least once in 2 yr. For denture stomatitis the age-standardized risk ratio decreased with brushing frequency in women and increased in men. For frequency of dental visits the prevalence of denture stomatitis increased in both men and women when visits were made over 2-yr intervals. The prevalence of denture stomatitis was higher in the group with dentures over 1 yr old. It seems that the oral hygiene measures as they are generally carried out and regular dental visits are not effective enough methods in preventing denture stomatitis.

Adult↗
PubMed1997

Comparison of bond strengths of denture base resins to nickel-chromium-beryllium removable partial denture alloy.

PURPOSE: In vitro bond strengths of a traditional denture base resin (Lucitone 199) and three adhesive denture base resins (Meta-Dent, Meta-Fast with liner, and Meta-Fast without liner) to treated nickel-chromium-beryllium (Ni-Cr-Be) partial denture alloy were tested with four alloy surface pretreatments (sandblast, Met-etch, Rocatec with silane, and Rocatec without silane), with or without primer (Dentsply). The Lucitone 199 resin bonded to the nonprimed sandblasted group was the control group. The hypothesis was the use of alloy pretreatments and/or primer does not improve the bond strength of denture base resins to sandblasted Ni-Cr-Be partial denture alloy. MATERIAL AND METHODS: Primed and nonprimed bonded specimens were prepared and finished, stored in 37 degrees C distilled water for 24 hours, then debonded in tension on a testing machine. The bond strength was calculated in megapascals (MPa). Five specimens were prepared and tested for each experimental condition, both with and without primer, for a total of 160 specimens. RESULTS: For three-way analysis of variance, the main effects of resins and treatment were statistically significant (p < 0.05), but the main effect of primer was not statistically significantly (p > 0.05). Without primer, the control group had the lowest bond strength (0 MPa). The three adhesive resin groups produced significantly higher bond strengths than the Lucitone resin groups. For the treated groups, nearly all sandblasted groups produced significantly lower bond strength than the other three treated groups. Meta-Dent to Met-etch treated group had the highest bond strength (23.9 MPa). With primer, the bond strengths of the Lucitone resin groups were significantly higher than the nonprimed groups, and the Lucitone resin-primed Rocatec treated group had the highest bond strength (14.8 MPa). For the three adhesive denture base resins, nearly all primed treated groups had significantly lower bond strengths than nonprimed groups. CONCLUSIONS: Without primer, the Lucitone resin-sandblast treated group (control) had the lowest bond strength (0 MPa). The Meta-Dent denture base resin with the Met-etch treated group had the highest bond strength (23.9 MPa). With primer, the Lucitone resin-primed Rocatec-silane treated group had the highest bond strength (14.8 MPa). For the adhesive denture base resins, nearly all bond strengths of the primed treated groups were significantly lower than the values of the nonprimed groups.

Acid Etching, Dental↗
PubMed2003

Changes in surface roughness and colour stability of soft denture lining materials caused by denture cleansers.

Soft denture lining materials were immersed into solutions of denture cleansers for 8 h at room temperature, and immersed into distilled water for the remainder of the 24-h period at 37 degrees C. Surface roughness of the soft denture lining materials was measured by contact type surface roughness instrument. For the colour stability test, soft denture lining materials were immersed in the denture cleansers as described above for 180 days. Finally, the colour changes of each material were quantitatively measured by a photometrical instrument to obtain the colour differences between newly processed specimen and immersed specimens (P < 0.01). An autopolymerizing silicone material, Evatouch, exhibited severe changes in surface roughness by all denture cleanser, and the generic material GC Denture Relining showed the minimal changes. Severe colour changes were also observed with some liner and cleanser combinations (P < 0.01). Except for Evatouth, the four silicone soft liners were more stable in surface roughness and in colour change than the two acrylic soft liners. One autopolymerizing silicone (GC denture relining) and one heat curing silicone (Molloplast B) demonstrated the best stability.

Color↗
PubMed1982

Frequency of Candida albicans serotypes in patients with denture-induced stomatitis and in normal denture wearers.

A comparison has been made between the serotypes of oral Candida albicans taken from patients with denture-induced stomatitis and from a group of age and sex-matched controls. C albicans isolates were obtained from the fitting surface of the denture, the palatal mucosa supporting the denture, and the buccal mucosa. Twenty-nine of the 30 patients samples in the group affected by denture-induced stomatitis had only C albicans serotype A on their palatal mucosa and denture surface, while mixtures of serotypes were obtained from the buccal mucosa of these patients. Only one patient had serotype B isolates from the palatal mucosa and denture surface. In contrast, the control group had mixture of A and B serotypes from both the denture surface and the palatal mucosa, as well as from the buccal sites sampled. It would appear from these results that denture-induced stomatitis is associated with the proliferation of a single C albicans serotype, usually serotype A.

Candidiasis, Oral↗
PubMed1997

An in vitro investigation of the abrasive qualities of a selection of denture-cleaning pastes on poly(methyl methacrylate) denture base material.

This study investigated the damage to poly(methyl methacrylate) (PMMA) denture base material caused by brushing with a range of denture-cleaning pastes using an electric, motor-driven, reciprocal-action toothbrushing machine. Plate specimens of PMMA were exposed to 5000, 10,000 and 20,000 brush strokes with four commercial and one recently developed denture-cleaning pastes. Products were applied as slurries in dilutions of 1:2, 1:3 and 1:5. Wear and roughness measurements were made using a surfometer. Results of a one-way analysis of variance showed that there was a statistically significant difference between each of the different denture-cleaning pastes at each given dilution for each number of wear cycles. For the denture-cleaning pastes, doubling the number of brush strokes in most cases, increased the depth of abrasion by a factor of two. A reduction in the Roughness Index and depth of wear was seen, again in most cases, with a dilution from 1:2, 1:3 and to 1:5. A recently developed paste (Blend-a-Dent Hygienic denture paste) bad a comparatively low wear and roughening effect on PMMA denture base material; however, further investigation of its stain-removal properties are necessary before it can be recommended as a suitable denture-cleaning paste.

Analysis of Variance↗
PubMed1998

Factors associated with the presence of denture related stomatitis in complete denture wearers: a preliminary investigation.

Various factors have been associated with the presence of denture related stomatitis. These include local factors such as continuous denture wear, trauma from dentures and poor denture hygiene Systemic factors, use of various pharmacological agents and smoking have also been implicated. This investigation involved history taking and examination of 250 patients attending Guy's Hospital for the construction of complete dentures. No association was found between systemic factors, use of pharmacological agents or smoking and the presence of denture related stomatitis. Night wear of complete dentures was found to be significantly associated with the prevalence of denture related stomatitis.

Chi-Square Distribution↗
PubMed1995

An investigation into the effect of denture fixatives in increasing incisal biting forces with maxillary complete dentures.

The effect of denture fixatives on incisal biting forces was investigated in five subjects wearing maxillary complete dentures. Forces required to displace new and old dentures with and without fixatives were measured up to six hours post-insertion using a force transducer. The results showed that incisal forces were greater with new dentures than with old dentures when only saliva was present. After the application of fixative to the old dentures, the difference from the new dentures without fixative became insignificant. It is concluded that the improvement in retention of complete dentures with the use of fixatives allowed patients to increase their incisal biting capability.

Adhesives↗
PubMed1996

Denture plaque distribution and the effectiveness of a perborate-containing denture cleanser.

Formation of plaque on the surfaces of dentures is a common problem among denture wearers. A study was conducted to determine the distribution of plaque on dentures. The plaque material was disclosed with a dye solution and measured with a modified Quigley-Hein scale. A photographic method was used to determine the distribution of plaque on the dentures of a group of complete-denture wearers. The effectiveness of a perborate soak-type cleanser was also measured by studying the precleaned and postcleaned states of the denture. Denture plaque was more evident on the fitting surfaces of the dentures than on areas of the flange, teeth, and palate. The use of the soak-type cleanser alone may not be completely effective for the control of heavy plaque.

Aged↗
PubMed1995

Adhesion of denture tooth porcelain to heat-polymerized denture resin.

Use of porcelain denture teeth may be desirable in many clinical situations, including implant-supported prostheses. However, lack of space because of frameworks often precludes the use of conventional retention by diatorics and pins. Adhesion of porcelain denture teeth to denture resin could also stiffen and possibly strengthen dentures and decrease stain ingress between porcelain teeth and resin denture bases. Unlike previous studies that investigated the bond between conventional feldspathic metal-ceramic porcelain and bis-GMA based composite resin, this study investigated adhesion of denture tooth porcelain to polymethyl methacrylate (PMMA). High-energy air abrasion, hydrofluoric acid etching, and the use of a general purpose bonding agent resulted in an improved bond strength of heat-cured denture PMMA bonded to denture tooth porcelain. Silane coating did not improve bond strengths, and conventional air abrasion was no more effective than polishing with 600-grit silicon carbide. Storage in water and artificial aging substantially decreased bond strengths. The strongest bond strengths were achieved by a high-energy-abrasion + etching + multi-purpose bonding-agent treatment, but a simpler etching + multiple-purpose bonding-agent treatment also produced reliable results. A laboratory technique was suggested. The role of surface treatment in the mechanism of adhesion was examined with scanning electron microscopy. High-energy abrasion produced a slightly more detailed initial topography than conventional air abrasion, but after etching, the high-energy topography became much more detailed. Surface topography alone did not account for all differences found.

Analysis of Variance↗