Vassiliki Anastassiadou

Association between functional tooth units and chewing ability in older adults: a systematic review.

OBJECTIVES To systematically review the current evidence on the relationship between dentition status and chewing ability in older adults, as the latter was subjectively perceived by questionnaires. BACKGROUND Tooth loss is associated with functional impairment regarding chewing ability, depending on the number and the location of the remaining teeth. METHODS A search of the English literature was undertaken using the appropriate electronic databases and keywords in order to answer the question of this review. Independent extraction of the related articles was carried out by two authors using predefined eligibility criteria. RESULTS Full-text analysis was performed for 51 articles of possible relevance. Finally, data were extracted from 18 studies, published in 20 articles that met the inclusion criteria. CONCLUSIONS Although there was a conflict between the studies relevant to the number of functional tooth units needed to maintain adequate oral function, it was revealed that chewing ability was closely related to the number and distribution of teeth remaining. Treatment plan should focus on the preservation of the strategic parts of the dental arch that are critical for adequate oral function. Long-term prospective studies, comprising well-defined criteria, clinical variables, methods and utilising comprehensive questionnaires, should be preferred to obtain a clearer picture on the association between masticatory ability and functional tooth units.

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.

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 students 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.

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.