The Effect of Denture Adhesives on Denture Quality and Occlusal Force.

INTRODUCTION: Complete dentures (CDs) have been associated with substantial problems regarding edentulous patient's function. Denture adhesives seem to be useful adjuncts to improving retention and stability. METHODS: A clinical study was undertaken to investigate the effect of a denture adhesive (DA) on function in complete denture wearers along with the quality of their CDs. Thirty complete denture wearers participated in the study. The first phase of the experimental procedure comprised 3 groups of measurements performed at 3 distinct time points: the initial measurement (T1), a 2nd measurement after 15 days of DA daily application (T2), and a 3rd measurement following a 15-day washout period (T3). The second phase consisted of the follow-up measurements. The measurements included: recording of relative occlusal force (ROF), distribution of occlusal contacts (DOC) and center of force (COF) using the T-Scan 9.1 device and functional assessment of dentures using the FAD index. RESULTS: The DA use induced a statistically significant increase in ROF (p-value=0.003) and decrease in COF (p-value⟨0.001) and DOC (p-value=0.001). The overall FAD score significantly improved (p-value⟨0.001). CONCLUSIONS: The use of the DA improved the occlusal force, the distribution of occlusal contacts as well as the qualitative characteristics of CDs.

The influence of age on tooth supported fixed prosthetic restoration longevity. A systematic review.

OBJECTIVE: The purpose of this study was to investigate the possible influence of age on the longevity of tooth supported fixed prosthetic restorations, using a systematic review process. DATA SOURCES: To identify relevant papers an electronic search was made using various databases (MEDLINE via Pubmed, EMBASE, The Cochrane Register of RCTs, the database of abstracts of Reviews of Effects-DARE), augmented by hand searching of key prosthodontic journals (International Journal of Prosthodontics, Journal of Prosthetic Dentistry and Journal of Prosthodontics) and reference cross-check. STUDY SELECTION: Assessment and selection of studies identified were conducted in a two phase procedure, by two independent reviewers utilizing specific inclusion and exclusion criteria. The minimum mean follow-up time was set at 5 years. RESULTS: The initial database search yielded 513 relevant titles. After the subsequent filtering process, 22 articles were selected for full-text analysis, finally resulting in 11 studies that met the inclusion criteria. All studies were classified as category C according to the strength of evidence. Meta-analysis was not possible due to the non-uniformity of the data available. The final studies were presented with conflicting results. The majority of the final studies did not report a statistically significant effect of age on fixed prostheses survival, whilst only one study reported poorer prognosis for elderly patients, and two studies reported poorer prognosis for middle-aged patients. CONCLUSIONS: The results of this systematic review showed that increased age of patients should not be considered as a risk factor for the survival of fixed prostheses. Although the majority of studies did not show any effect of age on the survival of fixed prostheses, there was some evidence that middle-aged patients may present with higher failure rates.

Validation of communication between elderly denture wearers and dentists: a questionnaire on satisfaction with complete dentures using semi-structured interviews.

OBJECTIVES: To validate a semi-structured interview (SSI) for communication between complete denture wearers and dentists. DESIGN: A SSI using a questionnaire with eight questions on satisfaction with complete dentures (CD): covering function, aesthetics and comfort. The first seven questions used a five-point Likert scale and the last was dichotomous. Two dentists, carefully trained in the use of the structured questionnaire, administered the SSI. SETTING: A Greek Department of Prosthetic Dentistry. SUBJECTS: A consecutive sample of 78 CD wearers took part in the study. All subjects presented with complaints from their dentures. INTERVENTION: All participants and their dentures underwent clinical examination. RESULTS: The method showed good reliability, verified by the Cronbach alpha (0.86). Both dentists used the questionnaire produced very similar results. (Wilcoxon test 61-99%). Further, the association of the answers with respect to the five-point Likert scale was very high; all gamma coefficients were statistically significant except for pain and discomfort from the upper CD (CDU). CONCLUSIONS: This method of communication between patients and dentists is reliable and can be used to give good repeatability for qualitatively assessing satisfaction with CD. It can be valuable for clinical use and for extending the study of denture quality to establish outcome measures based on the subjective criteria of satisfaction.

Validation of indices for functional assessment of dentures.

AIMS: To validate an assessment of qualities of complete dentures that may relate to functional success. SUBJECTS: A consecutive sample of 131 complete denture wearers took part in the study. SETTING: a Greek department of prosthetic dentistry. INTERVENTION: All participants and their dentures underwent clinical examination. DESIGN: The Functional Assessment of Dentures (FAD) 10-item criteria' describing clinical factors of denture quality was used. The rationale for selecting these particular criteria was to include a range of clinical factors to produce an overall assessment of complete dentures. The 10-item scale was examined for Internal Consistency and Construct Validity providing a summated rating scale whose total score could be used as an index for the quality of dentures. RESULTS: Both intra- and inter-examiner agreement for all 10 dichotomous scale criteria were all good or very good; the intra-examiner Kappa values were 0.72 to 0.91 and the inter- examiner values were 0.72 to 0.99. Statistical analysis revealed that a 7-item summated rating scale could be constructed which has marginally better internal consistency (reliability) and Construct Validity with fewer questions. CONCLUSIONS: The FAD criteria' can be used to give good repeatability. The adjustments made to the original summation scale, if confirmed by new studies, would further increase the practical utility of a FAD index for general dentists. In due course with data from future studies, discrimination on weighting of items will be appropriate to relate the impact of denture quality on quality of life.

The development of a simple objective test of mastication suitable for older people, using chewing gums.

AIMS: To develop and assess a simple test for evaluating the mastication of visco-elastic foods and prosthodontic success subsequent to treatment of older people. METHOD: The weight lost from chewing gum during mastication tests and the saliva secreted is weighed. The percentage of the original gum weight that is chewed out in a defined number of strokes is termed the Masticatory Effectiveness (ME) MATERIAL: Five edentate and three dentate volunteers were selected to provide a range of dental states and age. Four commercially available chewing gums of different origins and perceived hardness were tested, one without sweetener acted as a control for salivary stimulation. INTERVENTION: Pre-weighed samples of each gum were chewed, each for defined numbers of strokes. The saliva secreted was collected and weighed. The chewed gum was desiccated and the total weight loss of sweeteners chewed out provided an objective measure of chewing performance. RESULTS: Weight loss showed large differences between gums, between subjects and the number of strokes. ME was significantly correlated with salivary secretion rates for two subjects. The interaction between subject and gum was statistically significant, established by an ANOVA model, the value of which is shown for multivariate studies. Differential success between gums of different thickness may provide evaluation of denture stability. CONCLUSIONS: Measuring the weight lost from gums during chewing provides a simple test of masticatory effectiveness of visco-elastic foods. This has particular value both in functional assessment of older people and in physiological research.

X-ray diffraction study of crystalline phases of calcium sulphate in alginate impression materials.

In the present study the crystalline phases of calcium sulphate present in various commercially available alginate impression materials were identified by means of x-ray diffraction. The diffractograms obtained indicated that the predominant crystalline phase in most materials was calcium sulphate dihydrate and confirmed the presence of calcium sulphate hemihydrate in some products.

Relationship between pH changes and dimensional stability in irreversible hydrocolloid impression material during setting.

This study investigated the relationship between pH changes and dimensional stability during setting of irreversible hydrocolloid impression materials. Twelve specimens of seven irreversible hydrocolloid materials were used; pH readings for 20 minutes and dimensional (mass and linear) measurements for a 24-hour period were taken after mixing. The study of the curves and the comparison between them in range and in variance, together with the application of the t test, showed that pH changes were strongly related to the linear and mass changes derived from the variety and the chemistry of the included components and their amounts.

The effect of pH changes at the impression-stone cast interface during setting.

It is of great clinical significance to obtain a cast that reflects the optimal reproducibility of the irreversible hydrocolloid materials. This study investigated whether pH changes that occur during setting (as a single sequence of the chemical reactions that lead to gelation and the formation of the impression) are related to the reproducibility of irreversible hydrocolloids. The results indicated that as the pH range was increased for materials with alkaline pH values, the reproducibility improved. The opposite effect was noticed in materials with acidic pH values. It was also demonstrated that when the pH curve was in the acidic range, it was closer to the neutral pH values, and the reproducibility of the irreversible hydrocolloid was better.

The relation between thermal and pH changes in alginate impression materials.

OBJECTIVES: The purpose of this study was to determine if pH changes are related to thermal changes during setting in alginate impression materials, and to investigate the possibility of establishing a mathematical model between thermal and pH changes. METHODS: Thermal and pH changes were recorded during the 20 min gelation period following the mixing of five commercial alginate materials. The data obtained were plotted and statistically analyzed using a student's T-test, multiplicative, linear and reciprocal analyses at a significance level of p<0.05. These analyses were used to determine the differences between various materials and to establish regression models between thermal and pH changes for each of the materials tested. RESULTS: For all samples, the pH values fell within the first minutes from the alkaline range into the neutral and even into the acidic range, while the initial sharp fall in temperature was followed by a subsequent gradual increase. Differences in the final gel structures of the alginate materials were shown to be related to the differences in thermal and pH changes during setting. This could be expected from their various chemical compositions such as the variety of components, the chemical forms of principal components and the proportion of each component. SIGNIFICANCE: This work contributes to the development of a mathematical model relating pH changes and thermal changes to form a basis for the correlation between chemical properties and characteristics in practical use.