Effect of flask closure method and post‐pressing time on the upper denture base adaptation

doi:10.1111/j.1741‐2358.2009.00307.x
Effect of flask closure method and post‐pressing time on the upper denture base adaptation Objectives: The purpose of this study was to evaluate the effect of flask‐closure methods, post‐pressing times and acrylic resins on denture base adaptation. Materials and methods: The resins were flasked using a hydraulic press and closed with the traditional clamp or RS system. Conventional heat‐cure resin was polymerised immediately or at 6 h post‐pressing at 74°C for 9 h. Rapid cycle heat‐cure resin was polymerised in boiling water for 20 min. After cooling, the bases were deflasked and the sets of cast‐base transversally sectioned in the regions distal to the canine, mesial to the first molar and in the posterior palatal zone. The adaptation was measured with an optical microscope (0.0005 mm) at five reference points for each section. Data were analysed using anova and Tukey’s test (α = 0.05). Results: Traditional clamp and immediate post‐pressing time improved base adaptation for conventional heat‐cure resin. Both post‐pressing times showed most accurate base adaptation for conventional heat‐cure resin when the traditional clamp was used. Immediate post‐pressing time improved base adaptation for conventional heat‐cure resin and the 6‐h delay in time was significant for the rapid cycle heat‐cure resin. Conclusions: Traditional clamp and immediate post‐pressing time improved base adaptation for conventional heat‐cure resin.     

Influence of different metal flask systems on tooth displacement in complete upper dentures

doi: 10.1111/j.1741‐2358.2010.00392.x Influence of different metal flask systems on tooth displacement in complete upper dentures Objective: To verify the occurrence of tooth displacement in dentures processed by moist hot‐polymerisation using traditional and experimental metal flask systems. Materials and methods: Waxed complete dentures were randomly assigned to three groups (n = 10), including traditional (TF) and experimental flasks (DF and HHF). Metal pins were placed at the incisal edge of maxillary central incisors (I), buccal cusp of first premolars (P) and mesiobuccal cusp of second molars (M). Transversal (I–I, P–P and M–M) and anteroposterior (LI–LM and RI–RM) distances were measured before and after denture processing using an optical microscope. The dentures were processed by hot water curing cycle (9 h/74°C). Collected data were analysed by anova , Paired Student’s t‐test and Holm–Sidak method (p < 0.05). Results: All measured distances demonstrated contraction after polymerisation, except for LI–LM in TF and RI–RM in DF and HHF. Statistically significant differences were found between the distances P–P for DF and HHF, and M–M for all groups. Comparison among flask systems revealed statistically significant difference in the P–P distance for the TF and HHF. Conclusion: Different flask systems did not cause variation in tooth displacement during denture processing, with the exception of P–P distances for the TF and HHF. There is no evidence that different metal flask systems would promote tooth displacement of clinical significance.     

Effect of different repair techniques on the accuracy of repositioning the fractured denture base

Objective: This study investigated the efficacy of different techniques for the union of fragments of a denture before repair and on the accuracy of the reposition. Materials and methods: For this study, 20 maxillary dentures made with Lucitone 550 heat‐cured resin were used. Points were determined with a scanner on the cusp of the teeth, as a measurement of the segments. After digitisation, each model was exported to the AUTOCAD R 14 program and two‐dimensional measurements of the distances between the marked points were made. After the initial analysis, the dentures were fractured into two segments using an impact test machine. For the repair, maxillary dentures were divided into two groups; in the first, the repair was carried out using Kerr’s sticky wax and in the second group, Super Bonder was used to join the fragments, with subsequent inclusion of DENTSPLY^® Repair Material resin. After the repair, the points of the maxillary dentures were measured again. The numerical values obtained were tabulated to compare the measurements before fracture and after the repair. For statistical analysis, analysis of variance was employed, using a single factor and double factor, followed by the Tukey test with a reliability of 95%. Results: The results demonstrated a statistically significant difference between the materials used to join the dentures for repair, where the dentures were joined with sticky wax presented a larger variation in the distances between the points. Conclusion: The variation in distances between the points is influenced by the agent of repair.     

In vivo assessment of the effect of an adhesive for complete dentures on colonisation of Candida species

doi: 10.1111/j.1741‐2358.2009.00345.x
In vivo assessment of the effect of an adhesive for complete dentures on colonisation of Candida species Objective: Denture adhesives have long been recognised by denture wearers as a useful adjunct to denture retention and stability. The objective of the present study was to evaluate, in vivo, the effect of a denture adhesive on oral quantities of Candida species by determination of absolute counts of colony‐forming units (CFU) per ml of saliva of individuals who use this denture adhesive for a period of 14 days. Materials and methods: Twenty‐four individuals were randomised in two equal groups of 12 (test and control), with the individuals of the test group using the adhesive for 14 days. Samples of saliva were collected from all individuals on days 0 (initial), 7 and 14. Aliquots of saliva were diluted and plated in duplicate on Sabouraud dextrose agar with chloramphenicol and incubated for 37°C for 48 h, the CFU/ml were counted in the individuals of each group and the data of each group were compared at the different time periods and analysed statistically by the non‐parametric Mann‐Whitney U‐test (α ≤ 5%). Results: There were no statistically significant differences between the test and control groups during the test periods. Conclusion: Within of the limitations of this study, the data suggested that the denture adhesive tested did not significantly alter the oral microbiota during the 14‐day trial period.     

In vitro and clinical evaluation of specific dentifrices for complete denture hygiene

Objectives: To study the physical properties of two experimental dentifrices for complete denture hygiene, their effect on denture biofilm removal and antimicrobial properties by means of a clinical trial. Materials and methods: The experimental dentifrices comprised two compositions. One was based on the addition of 1% chloramine T (D1) and the other on the presence of 0.01% fluorosurfactant (D2). Measurements of density, pH, consistency, rheological features and abrasiveness were conducted. Sixty complete denture wearers were randomly assigned to three groups and were instructed to brush their dentures with a specific toothbrush: (1) Water (control); (2) D1; or (3) D2. Each method was used for 21 days. Denture biofilm was disclosed by a 1% neutral red solution and quantified by means of digital photos taken from the internal surface. Microbiological assessment was conducted to quantify Candida sp. and mutans streptococci. Data were evaluated by one‐way anova and Tukey HSD, or Kruskal–Wallis (α = 0.05). Results: Both dentifrices decreased biofilm coverage when compared with the control group. D1 was the most efficacious treatment to reduce mutans streptococci, whereas D2 showed an intermediate outcome (anova , p < 0.040). No treatment influenced Candida albicans or non‐albicans species (Kruskal–Wallis, p = 0.163 and 0.746, respectively). Conclusion: It can be concluded that brushing complete dentures with the experimental dentifrices tested could be effective for the removal of denture biofilm.     

Factors affecting the distribution and prevalence of oral mucosal lesions in complete denture wearers

Gerodontology 2010; doi: 10.1111/j.1741‐2358.2009.00351.x
Factors affecting the distribution and prevalence of oral mucosal lesions in complete denture wearers Objective: To determine the frequency of the oral lesions related to gender, age, the length of time of denture usage, education level and economic status. Methods: The 153 patients with old complete dentures (CD) were asked to participate in the investigation. The subjects (76 male and 77 female) were 37–85 years of age with a mean age of 61.8 ± 9.8 years. Education, economic status and age factors were estimated in subgroups. The data obtained were evaluated by one‐way anova , Mann–Whitney U‐test, Kruskal–Wallis test, Student’s t‐test and chi‐squared test. The level of statistical significance was set at p < 0.05. Results: The patients who had denture stomatitis and traumatic ulcers were statistically significantly older than the ones who did not have these lesions (p < 0.05). Based on the length of denture usage, patients who had a flabby ridge, fibrous inflammatory hyperplasia, traumatic ulcers (p < 0.01) and denture stomatitis (p < 0.05) were using their dentures statistically significantly longer than the ones who had healthy tissues. Conclusions: The CD wearers should be advised to visit their dentist regularly to prevent oral mucosal lesions due to the changing supporting tissues during the length of denture usage and to improve their quality of life.     

Elderly complete denture wearers: a social approach to tooth loss

doi: 10.1111/j.1741‐2358.2011.00550.x Elderly complete denture wearers: a social approach to tooth loss Objectives: To correlate emotional reactions to tooth loss with denture satisfaction attributes in elderly complete denture wearers. Background: Total tooth loss is a serious life event, and poor oral health has an impact on daily life. Edentulism treated by rehabilitation with dentures can have a positive effect on patients’ self‐image and social behaviour. Methods: A group of 80 edentulous subjects undergoing routine prosthetic care in a Greek Department of Prosthetic Dentistry were interviewed using two structured questionnaires. The first questionnaire explored reactions to tooth loss, whereas the second measured their subjective experience of complete dentures. The responses to both questionnaires were compared using the statistical package spss v.17. Results: The results showed significant correlation between aspects of tooth loss experience and complete denture satisfaction. Despite the fact that a substantial proportion of patients were satisfied with their complete dentures, some patients experienced increased social and psychological problems related to their edentulousness and the wearing of complete dentures. The aesthetic and functional aspects of complete dentures affected both patients’ social behaviour and self‐confidence. Conclusions: Total tooth loss was not only reflected in patient’s social behaviour and self‐image, but it had a complex and multifaceted impact on satisfaction from complete dentures.     

Comparative analysis of biofilm levels in complete upper and lower dentures after brushing associated with specific denture paste and neutral soap

Objectives: The objective of this study was to compare and correlate biofilm levels in complete upper and lower prosthesis after brushing, associated with specific paste and soap, by means of computerised methodology. Materials and methods: Forty‐five complete denture wearers were selected and instructed to brush their prostheses (Soft Oral B 40) three times a day for 3 weeks with water (Control), specific paste for complete dentures (Corega Brite) (Experiment 1) and neutral soap (Experiment 2). The study was based on a cross‐over model and a wash‐out period was not included. For biofilm quantification, the internal surfaces were dyed (neutral red 1%), photographed (Canon EOS Digital) and the disclosed biofilm was measured with the Image Tool 2.0 software. The products were assessed by means of a questionnaire regarding their hygiene properties and acceptance. Results: The variance analysis indicated that the lower prostheses exhibited a mean biofilm percentage, significantly higher than the upper prostheses and that brushing with paste (Experiment 1) was more effective than soap (Experiment 2) and, in turn, this was more effective than water (Control). There was a high biofilm correlation (Pearson correlation) between both prostheses. Both products were well accepted by the patients, but the most favoured one was the paste. Conclusions: This was effective in controlling the biofilm and can be used preventatively in the maintenance of oral health by wearers of complete dentures. This is important where the lower prosthesis can harbour microorganisms which may act as a reservoir for other areas of the mouth and thus enhance the importance of proper hygiene.     

Clinical and microbiological efficacy of three different treatment methods in the management of denture stomatitis

Gerodontology 2010; doi: 10.1111/j.1741‐2358.2009.00354.x
Clinical and microbiological efficacy of three different treatment methods in the management of denture stomatitis Objective: This study evaluated. the effect of mouthrinses and tissue conditioner on the clinical findings and microbial flora of 60 patients with Newton’s type II denture stomatitis (N2DS) Background: Denture stomatitis is a common problem in complete denture wearers. Materials and methods: Sixty patients with N2DS were included in this study and divided into three groups. Two groups of patients were instructed to rinse their mouth with the designated mouthrinses DioxiDent and Corsodyl twice daily for 1 min and to soak their dentures overnight in these solutions for 15 days. For the third group, tissue conditioner was placed in each of 20 patients’ existing maxillary dentures. Patients were evaluated both clinically and microbiologically at baseline and after 15 days. Palatal swabs and smears were taken from each patient before and after treatment and these samples were examined mycologically. The difference between Candida colonisation before and after treatment and the differences between pre‐treatment and post‐treatment clinical findings were assessed. Results: DioxiDent and Corsodyl showed an improvement in palatal inflammation and a decrease in Candida colonisation compared to Visco‐gel. Conclusions: The effectiveness of topical chlorine dioxide and chlorhexidine gluconate in the management of N2DS was demonstrated.     

Distribution of biofilm on internal and external surfaces of upper complete dentures: the effect of hygiene instruction

Objectives: The purpose of this study was to evaluate biofilm distribution over internal and external surfaces of upper complete dentures. It was also aimed at assessing the effect of oral hygiene instructions before and after home use of a disclosing solution. Materials and methods: The sample consisted of 29 complete denture wearers whose upper prostheses were evaluated. Surface biofilm was disclosed by means of a 1% neutral red solution and quantified with regard to internal and external surfaces. Oral hygiene information was provided on an individual basis. During the second stage, an amount of disclosing solution was given for domestic use. Results: Internal and external surfaces presented a similar amount of biofilm, which was concentrated over the area of the posterior teeth area, palatal rugae and the internal vestibular incline of the distobuccal flange. This pattern was maintained during the study. However, overall amounts were reduced following denture hygiene information. The use of disclosing solution by subjects at home resulted in a further reduction. Conclusions: It was concluded that biofilm deposits were similar over assessed surfaces, regardless of the type of procedure but irregular areas presented greater amounts. Oral health instruction was effective in reducing the biofilm, in particular when associated with home use of a disclosing agent.     

Stress analysis of a complete maxillary denture under various drop impact conditions: a 3D finite element study

Complete maxillary dentures are one of the most economic and easy ways of treatment for edentulous patients and are still widely used. However, their survival rate is slightly above three years. It is presumed that the failure reasons are not only due to normal fatigue but also emerge from damage based on unavoidable improper usage. Failure types other than long-term fatigue, such as over-deforming, also influence the effective life span of dentures. A hypothesis is presumed, stating that the premature/unexpected failures may be initiated by impact on dentures, which can be related to dropping them on the ground or other effects such as biting crispy food. Thus, the behavior of a complete maxillary denture under impact loading due to drop on a rigid surface was investigated using the finite element method utilizing explicit time integration and a rate-sensitive elastoplastic material model of polymethylmethacrylate (PMMA). Local permanent deformations have been observed along with an emphasis on frenulum region of the denture, regardless of the point of impact. Contact stresses at the tooth–denture base were also investigated. The spread of energy within the structure via wave propagation is seen to play a critical role in this fact. Stress-wave propagation is also seen to be an important factor that decreases the denture's fatigue life.     

Comparison between complete denture and implant‐retained overdenture: effect of different mucosa thickness and resiliency on stress distribution

Background: The effect of different mucosa characteristics on stress distribution of complete dentures and overdentures remains unknown. Objective: The aim of this study was to evaluate the effect of different mucosa thickness and resiliency on the stress distribution of complete dentures and implant‐retained overdentures using a two‐dimensional finite element analysis. Material and methods: Representative models of the edentulous mandible were constructed on AutoCAD software according to the groups’ characteristics. In group CD, a model of the edentulous mandible supporting a complete denture was obtained while in group IO, a model of edentulous mandible supporting an overdenture over two unsplinted implants with an o’ ring system was constructed. In each group, mucosa assumed three characteristics of thickness (1, 3 and 5 mm) corresponding to the resiliencies hard, resilient and soft respectively. Evaluation was performed on Ansys software with 100N vertical load applied on central incisor teeth. The principal stress was used as analysis criteria. Results: Group IO showed higher stress values than group CD regardless of mucosal thickness and resiliency. Stress decreased at the supporting tissues in both groups as the thickness and resiliency of mucosa increased. In relation to the supporting tissues, cortical bone showed the highest stress values. Conclusion: It was concluded that the use of an attachment system increases stress values and the thickness and resiliency of mucosa influence more on these values.     

Examination of denture-cleaning methods based on the quantity of microorganisms adhering to a denture

doi: 10.1111/j.1741‐2358.2011.00461.x Examination of denture‐cleaning methods based on the quantity of microorganisms adhering to a denture Objectives: To investigate effective denture‐cleaning methods, we examined the relationships between the quantity of microorganisms adhering to dentures and the use of a denture brush and the frequency of use of a denture cleanser. Subjects and Methods: Denture plaque was collected from the mucosal surface of the examined dentures, which were 142 and 80 upper and lower complete dentures, respectively, worn by 96 outpatients (mean age: 71.9 years) of a university hospital and 41 nursing home residents (mean age: 84.8 years). The collected microorganisms were counted in terms of isolated representative colonies that were cultured and identified using standard methods. The use of a denture brush, the frequency of use, and the type and soaking time of denture cleansers as denture‐cleaning methods were surveyed. Results: The quantity of microorganisms was significantly lower in dentures of denture brush users than in those of non‐users in the outpatients (p < 0.01, Mann–Whitney U test). The quantity of microorganisms was significantly lower in the dentures of outpatients who used a denture cleanser daily or 3–4 times a week than in those who used one once or less per month and in the dentures of nursing home residents who used one daily than in those who used one at other frequencies (p < 0.05, Kruskal–Wallis test, followed by Dunn’s Multiple Comparison test). Conclusion: Within the limitations of this study, it was concluded that the use of a denture brush and daily use of denture cleanser should be recommended to complete dentures wearers as denture‐cleaning methods that effectively reduce the quantity of microorganisms adhering to dentures.     

Effects of home and office care denture reliners on maxillary complete dentures

doi:10.1111/j.1741‐2358.2009.00308.x
Effects of home and office care denture reliners on maxillary complete dentures Objectives: The aim of this study was to evaluate the effects of office (OR) and home (HR) care temporary denture reliners on satisfaction and functional outcomes in maxillary complete denture wearers. Methods: Thirty‐four maxillary edentulous patients received application of either OR or HR to their maxillary complete dentures. Patient’s ratings on satisfaction and functional aspects were measured on a 100‐mm visual analogue scale at 4 days post‐application. Associations between baseline ratings and improvement were also assessed. Results: There were no significant differences between the two groups in satisfaction ratings or in the functional outcomes. The OR group showed a significant improvement in mastication and retention, whereas the HR group exhibited a significant improvement in general satisfaction and mastication. Improvement was negatively associated with baseline ratings of speech, ease of cleaning, stability and retention in the OR groups and across all variables, except ease of cleaning, in the HR group. Conclusion: When used correctly, home care denture therapy can be as effective as office applied temporary liner in improving satisfaction with problematic maxillary dentures.     

Effect of double flasking and investing methods on artificial teeth movement in complete dentures processing

doi: 10.1111/j.1741‐2358.2011.00494.x
Effect of double flasking and investing methods on artificial teeth movement in complete dentures processing Purpose: The aim of this study was to evaluate linear dimensional alterations of artificial teeth for complete dentures when using different investment and flasking techniques. Background: Dimensional changes in the vertical dimension may occur owing to changes in artificial teeth positioning caused by different investing and flasking techniques. Materials and methods: Thirty pairs of the complete dentures were manufactured and randomly divided into three groups (n = 10): (1) invested with type III stone in monomaxillary PVC flask; (2) invested with type III stone in bimaxillary PVC flask; and (3) invested with laboratory silicone in bimaxillary PVC flask. Dentures were polymerised by microwave, and 12 linear distances were measured before and after denture processing. Data were analysed by one‐way anova , considering manufacturing technique as the study factor. Tukey’s HSD was used as post hocanova (p = 0.05). Results: Most of the linear distances were comparable for all groups. All transversal maxillary and mandibular distances were higher for group 1 compared with groups 2 and 3 (p < 0.05), except the distance 3–6 for mandibular arch, in which no difference was found between groups (p < 0.05). Both maxillary diagonal distances were higher in group 1 (p < 0.05), and no differences were found among all groups for mandibular measurements. Conclusions: Double flasking technique independent on the investment material is shown to be the most effective method to reduce changes in artificial teeth positioning.     

Effect of pre-processing methods on bond strength between acrylic resin teeth and acrylic denture base resin

doi: 10.1111/j.1741‐2358.2011.00480.x
Effect of pre‐processing methods on bond strength between acrylic resin teeth and acrylic denture base resin Objectives: This study evaluated the effects of various pre‐processing methods on the bond strength between resin and denture teeth. Backgrounds: Debonding of acrylic resin teeth from denture base material is a problem for patients wearing complete dentures. Materials and Methods: Four experimental groups (n = 30) were investigated by subjecting tooth–resin bonding to tensile loading. Specimens were prepared and tested according to the methods of the International Standards Organization (ISO 22112:2005) using a special assembly. Four pre‐processing surface treatments of teeth were applied: (i) ST₁, no treatment applied (control); (ii) ST₂, wax solvent (Dewaks, Faber Kimya & Ilaç, Turkey); (iii) ST₃, boiling water followed by conditioning with methyl methacrylate (MMA) monomer (Meliodent, Bayer Dental, Germany); (iv) ST₄, boiling water followed by wax solvent agent and finally MMA monomer application. Bond strength test was performed using a universal testing machine. Results: All the strength values of the test groups were within clinically acceptable limits. The lowest values were from the ST₁ group and the highest values were in the ST₄ group. Conclusions: Wax elimination methods affected bonding strength. Application of wax solvent and MMA monomer to the ridge lap surfaces of the teeth gave the best results. In clinical practice, this application procedure may decrease the bonding failure of denture teeth.     

Assessment of changes in oral health‐related quality of life among patients with complete denture before and 1 month post‐insertion using Geriatric Oral Health Assessment Index

doi:10.1111/j.1741‐2358.2009.00323.x
Assessment of changes in oral health‐related quality of life among patients with complete denture before and 1 month post‐insertion using Geriatric Oral Health Assessment Index Objective: Geriatric Oral Health Assessment Index (GOHAI) is a 12‐item measure of “patient‐reported oral functional problems” intended for use in the assessment of the effectiveness of dental treatment. Design and Setting: As there is scanty literature available on GOHAI in the Indian population, the present study was undertaken to assess the changes in GOHAI before and 1 month after placement of dentures in completely edentulous patients reporting to a dental hospital at Indore, India. Measurements: The GOHAI questionnaire was completed by the examiner who interviewed the patients (n = 35) before placement of complete dentures and 1 month later. Mean, median values were calculated and the data were analysed using Wilcoxon signed‐rank test. Results: When overall mean was considered, the GOHAI scores increased from 27.48 to 30.19 (p = 0.002; highly significant). Conclusion: Patients reported improvement in functional changes after placement of complete dentures.