Impact of uraemia on the shear bond strength between composite resin and tooth structure: sem evaluation

Objectives: This study was aimed to investigate the influence of uraemia on enamel and dentin bond strength to resin composite using a total-etch adhesive system. The micromorphological appearance of resin-tooth interfaces was also investigated

Methods: The adhesive system and the composite resin used in this study were Excite and Tetric EvoCeram [lvoclar/ Vivadent] according to manufacturers' recommendations. Thirty six human molars were used for this study, 28 molar for shear bond test and 8 molars for micromorphological study. The teeth were divided into two groups, A and B, and then each group was subdivided into two subgroups. Teeth of group A were extracted from normal individuals while group B were extracted from uraemic patients. Enamel bonding sites were prepared in the buccal surfaces of subgroups A[1] and B[1] while dentin bonding sites were prepared in occlusal surfaces of subgroups A[2] and B[2] using 600 grits SiC abrasive paper. For shear bond test specimens were etched with 37% phosphoric acid gel and composite rods were bonded with the adhesive resin. Shear bond strengths were determined using a Universal Testing Machine at a cross-head speed of 2mm/min until failure occurred. Fracture modes were examined at 16x magnifications with stereomicroscope. The other 8 specimens were prepared with the adhesive resin only and examined with SEM

Results: Bond strengths to normal enamel were significantly higher compared to normal dentin, uraemic enamel and uraemic dentin. SEM observations revealed shallower etch pattern for uraemic enamel and poor infiltration of resin into dentinal tubules for uraemic dentin compared to normal specimens

Significane: Uraemia had impact on the bond strength of composite resin to tooth structure

Shear bond strength of ormocer- based esthetic restorative material to tooth structure using specific and non-specific adhesive systems

Objectives: The aim of this study was to evaluate the shear bond strength and failure pattern of ormocer- based restorative material bonded to tooth structure [enamel and dentin ] using ormocer-based adhesive to be compared with non-specific resin-based adhesives [3-fifth and 1-six generation adhesive resins]

Methods: Seventy non-carious human molars were prepared to obtain 35 molars with Hat buccal enamel surfaces and 35 molars with flat occlusal dentin surfaces. The following adhesive systems were applied to both the prepared enamel and dentin surfaces [1] Admira Bond, specific ormocer adhesive system, [2] Prime and Bond NT, [3] Excite, [4] AdheSE and [5] Prompt-L-Pop non-specific resin-based adhesive systems. Ormocer filling material [Admira ] was inserted in a teflon mold of 4mm in diameter and height onto the prepared tooth surface and cured with halogen light curing unit. The shear bond strength was measured using universal testing machine

Results: The greatest bond strength was recorded for the specific Admira Bond adhesive system and non-specific adhesive systems, total- etch [Prime and Bond NT and Excite]. Self-etching, non-specific adhesive systems [AdheSE and Prompt-L-Pop] recorded the lowest bond strength Values

Conclusion: Total etch, non-specific bonding agents can be used with Admira, ormocer-based filling material.e.g Prime and Bond NT and Excite

Marginal adaptation of class v cavities restored with nanofill, low-shrinkage composite resins and compomer restorations

Objectives: The purpose of this in vitro study was to evaluate marginal adaptations of nanofill and low-shrinkage composite resins and compomer restorations in class V cavities by quantitative marginal analysis and dye penetration

Methods: Forty recently extracted human molars were prepared with standardixcd class V cavities on the buccal and lingual surfaces with gingival margins located 1.0 mm. apical to cementum-enamel junction. The samples were randomly assigned into 4 groups of 10 samples [n=20 cavities]. Samples of group I were restored with Filtek Supreme, group 2 with InTen-S, group 3 with Tetric Ceram and group 4 with Compoglass F. After immediate finishing, the samples were thermocycled [500 x, 5° -55° C, 30 sec. dwell timed] and stored in distilled water until testing. The mean of measurements of 4 predetermined locations for each sample was taken using measurescope. The results were statistically analyzed using A NOVA and LSD tests. The same samples were immersed in 0.5% basic fuchsin solution for 24 hours. The restorations were then sectioned buccolingually and margins were evaluated for dye penetration using a 0-3 scale. Data were subjected to Chi-Square test for statistical analysis

Results: Quantitative margin analysis showed significantly fewer marginal gaps for Filtek Supreme and InTen-S Composite resin restorations compared to Tetric Ceram and Compoglass F restorations. Dye penetration was significantly higher at the gingival margin for all groups compared to enamel margin

CONCLUSIONS: The best marginal adaptation in class V cavities was achieved with the use of nanofill composite resin [Filtek Supreme] and low-shrinkage composite resin [InTen-S] in comparison with microhybrid composite resin [Tetric Ceram] and compomer [Compoglass F]

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

Microleakage of different adhesive resin systems in class v composite restorations: effect of thermal cycling and load cycling

Objective: the aim of this study was to evaluate the microleakage of five different hydrophilic adhesive resin systems and the effect of thermal and load cycling on microleakage in class V composite restoration

Method and materials: Buccal and lingual class V cavities were prepared with enamel and dentin margins in 75 molar teeth and randomly divided into five groups of 15 molar each. Group 1 was bonded with Syntac Classic [three-bottle] adhesive, group 2 with Excite "one-bottle" fluoride-free adhesive, group 3 with Stae "one-bottle" fluoride containing adhesive, group 4 with AdheSE, two-step, self-etch adhesive and group 5 with Prompt-L-Pop, all-in-one, self-etch adhesive according to the manufacturer's instructions. All preparations were restored with Tetric Cer-am, microhybrid composite resin. From each group 5 molars [10 restorations] were immediately immersed in 0.5% basic fuchsin solution after finishing and kept there for 24 hours to examin microleakage. Other 5 molars of each group were thermocycled [5 - 55°C, 20s dwell time, 500 cycles] and then immersed in the dye solution. The remaining 5 molars of each group were subjected to occlusal load cycling [80-160 N, 5 cycles/sec. 200.000 cycles] prior to immersion in the dye solution. The specimens were sectioned vertically and buccolingually and microleakage was evaluated on a scale of 0 to 3.

Results: For the enamel margins, statistical analysis revealed that there was no significant difference between the tested materials but AdheSE provide the least marginal adaptation while the best results obtained with Syntac Classic. Statistical analysis revealed no significant difference among the groups in dentinal microleakage but AdheSE showed the best result. Both thermal and load cycling had no significant effect on microleakage among the groups either in enamel or dentinal microleakage but the thermocycled and load cycled specimens showed greatest micro-leakage

Conclusion: Among the five adhesive systems used in this study, Syntac Classic had the least microleakage in enamel; however, there was no statistically significant difference among the groups in enamel margins. AdheSE had the.least microleakage in dentin; however, there was no statistically significant difference among the groups on dentin margins. Both thermal and load cycling had no significant effect on microleakage among the groups.

Fracture resistance of prepared posterior teeth restored with new aesthetic restorative materials

The aim of this in vitro study was to compare the fracture resistance of premolar teeth restored with packable resin-based composite [Tetric Ceram HB], low-shrinkage composite [In Ten-S] and ormocer-based composite [Admira]. Fifty intact, non carious human maxillary premolars were divided into 5 groups of 10 teeth each and were mounted with their roots imbedded in onto polymerized acrylic. In the first group, the teeth were intact with no preparation. In the other groups, Class II MOD preparations were made with a water-cooled. high-speed hand piece. In group 2. The teeth were prepared but unrestored. In group 3, the carity preparations were restored with tetric ceram HB while in group 4 the preparations were restored with In Ten-S and In group 5, Admira was used for restoration of the cavity preparations. After the restorations, the samples were themocycled and tested individually in a universal testing machine, in which a 4.8 mm diameter steel ball was mounted in the cross head moving at 2 mm/min. Peak load to fracture [N] was measured for each samples. Means were calculated and analyzed with analysis of variance [P