Maxillary denture displacement during functional relining impression procedure with tissue conditioner

This research was carried out on eight completely edentulous patients to study the effect of functional relining impression technique with tissue conditioner on maxillary denture displacement regard different time of keeping the impression in the patient mouth. Centric occlusion was used to seat the maxillary denture for 3 minutes. The patients were asked to mould the periphery by cheeks and lips movement and functionally recorded the impression by asking him to swallow, suck and talk for 15, 30, 45 or 60 minutes. Denture displacement was measured in three co-ordinates with modified measurescope. The results of this study revealed that 15 minutes for functional relining by the tissue conditioner exhibited a significant increase in vertical maxillary denture displacement than that for 30, 45 and 60 minutes. On comparing maxillary denture displacement in the three coordinates after functional relining impressions at 30, 45, 60 min, it was found that no one superior to other. This study concluded that 30 minutes was the time selected for functional relining impression making with tissue conditioner material regard less denture displacement and less time consuming

Evaluation of marginal and internal adaptation of different composite resins and ormocer-based restorative material in class II cavity preparation

Objectives: The current project was undertaken to evaluate the adaptation of hybrid composite [Filtek Z 250], packable composite [Filtek P 60] and ormocer-based [Admira] restorative materials with or without flowable liner in class H cavity preparation with enamel and dentin margin before and after load cycling. Methods: This study was carried out on 240 extracted lower molars and divided into six main groups with 40 molars in each group according to the restorative systems used. Where group 1 restored with Filtek Z 250, group 2 Filtek Flow/Filtek Z 250, group 3 Filtek P 60, group 4 Filtek Flow/ Filtek P 60, group 5 Admira and group 6 Admira Flow/Admira. Each group was further subdivided into two subgroups according to the gingival margin location. In the first subgroup the gingival margin was located 1.0 mm above the cemento-enamel junction while in the second subgroup the gingival margin was located 1.0 mm below the CEJ. Respectively, each subgroup was subdivided again into two halves one half subjected to load cycling and the other half not subjected to load cycling. A mechanical loading machine was used to apply a cyclic load of 80-160 N at a 5 cycle/second, for 200.000 cycles following a sinasodal loading curve in a distilled water environment. The marginal and internal gap surface areas were measured on incidental light microscopy setup with an attached digital camera and dedicated computer to acquire digital photomicrographs of sectioned teeth. Statistical analysis was performed using ANOVA [P< 0.05] to determine the effect of restorative material type, location of gingival margin [enamel or dentin], using flowable liner and finally before or after load cycling on the marginal and internal adaptation of the restored samples. Post Hoc Multiple comparison test [P< 0.05] was performed to determine significant intra-group difference of gap surface area of the tested groups

Restults: The analysis of variance showed that the Admira Flow/Admira has the lowest gap surface area with all the tested groups. Also, the restored samples with Filtek Flow or Admira Flow as a liner showed less gap surface area than the restored samples without flowable liner. Enamel margins showed less gap surface area compared to dentin margins and there was no significant difference in marginal and internal ad-aptation between the samples before or after load cycling

Conclusions: Within the limitations of this study, the following conclusions can be drawn: [l]The ormocer-based restorative material [Admira] provides better marginal and internal adaptation than both universal hybrid composite resin [Filtek Z 250] and packable composite [Filtek P 60 ].[2] The quality of marginal and internal adaptation before and after load cycling proved to be influenced by the location of the cavity margins, the enamel margin achieves more adaptation than the dentin margin. [3] Flowable liner could be used to enhance the adaptation of both resin composites and ormocer-based restorative materials.and [4] Load cycling has no significant effect on the adaptation of the restorative materials used in this study