Idil Dikbas

Comparison of the fracture resistance of simulated immature permanent teeth using various canal filling materials and fiber posts

BACKGROUND   The purpose of this study was to compare the fracture resistances of immature teeth treated with MTA along with root canal obturation methods using AH Plus, MetaSEAL, MTA Fillapex sealers + lateral compaction technique, and Unicore quartz fiber posts. MATERIALS AND METHODS   Fifty single-rooted maxillary anterior teeth were divided into five groups. The crowns were dissected and root canals were enlarged. #6 Peeso reamers were allowed to protrude 1 mm. beyond the apex to simulate immature teeth. The apical 4-5 mm of each tooth was filled using Angelus white MTA. The remaining portions of canals were obturated as follows: Group 1: No backfilling (control), Group 2: AH Plus + gutta-percha, lateral compaction, Group 3: MetaSEAL + gutta-percha, lateral compaction, Group 4: MTA Fillapex + gutta-percha, lateral compaction, Group 5: UniCore Fiber posts luted using PermaFlo DC. The specimens were embedded into self-curing acrylic poured into identical cylinders which were mounted on a jig providing a 45° angle. A compressive load increasing at 1 mm min(-1) was applied and the maximum load at which fracture occurred was recorded. Statistical analysis was performed using Kruskal-Wallis and Dunns multiple tests. RESULTS   The highest fracture resistance was obtained with Group 5 (Fiber posts) whereas Group 4 (MTA Fillapex) yielded the lowest values. The mean fracture resistance value of Group 2 (AH Plus) was significantly higher than Group 4 (MTA Fillapex) (P = 0.001). The mean fracture value of Group 5 (Fiber posts) was significantly higher than Group 2 (AH Plus), Group 3 (MetaSEAL), and Group 4 (MTA Fillapex) (P = 0.02, 0.004, and 0.0001, respectively). CONCLUSION   Within the limitations of this study, UniCore quartz fiber posts provided the highest resistance. This methodology may specifically be advantageous for teeth with arrest of development at early stages, as these teeth are more susceptible to fracture owing to their excessively weak dentinal walls.

An overview of clinical studies on fiber post systems.

Intraradicular posts are useful adjuncts in the restoration of endodontically treated teeth. These systems have undergone a significant evolution in recent years, and fiber-reinforced systems have started to be incorporated into routine clinical care more frequently. Despite the high number of laboratory studies pertaining to the characteristics of fiber posts, clinical studies evaluating their general success rates are rather limited. Since clinical investigations are reliable means to achieve information about the general behavior pattern of materials or techniques, assessment of this data will be beneficial to have a better understanding of fiber-reinforced intraradicular post systems. The purpose of this paper was to make a summary of clinical studies regarding various fiber posts. A PubMed search was conducted and articles dating back to 1990 were retrieved. The paper provides an overview of clinical studies on fiber posts specifically in the last decade as well as commentary analysis.

Impact strength of denture polymethyl methacrylate reinforced with different forms of E-glass fibers

Abstract Objective. The purpose of this in vitro study was to determine the reinforcing effect of different forms and concentrations of E-glass fibers on impact strength of denture polymethyl methacrylate. Materials and method. A total of 91 rectangular specimens (84 specimens for test groups and seven for control group) of a heat-cured acrylic resin were fabricated. The test specimens were prepared by modifying the polymethyl methacrylate with the addition of different concentrations (2.5%, 3%, 4%, 5% by volume) of three types (chopped strand mat, woven and continuous unidirectional fibers) of E-glass fibers. The impact strength was evaluated using the Charpy method. Results. While the 5% continuous glass fiber added test group showed the highest mean impact strength, the lowest value belonged to the 2.5% woven glass fiber containing group. When the impact strength values of chopped strand mat and continuous unidirectional glass fiber added groups at all concentrations were compared with the control group, the differences were statistically significant. The impact strength values of the woven glass fiber added groups at all concentrations were higher than that of the control group. However, the difference was non-significant. Conclusion. The impact strength of PMMA was enhanced by including E-glass fibers, increasing parallel with the fiber concentration.

Comparative study of the fatigue strength of five acrylic denture resins

The aim of this in vitro study was to compare the fatigue resistance of three kinds of heat-polymerized acrylic resins (conventional heat-polymerized, rapid heat-polymerized, high impact acrylic resin), a kind of visible light-cured resin and a kind of self-cured acrylic resin. A total of 60 notched and un-notched specimens (65 mm x 10 mm x 3 mm) were fabricated, 12 from each material. The fatigue resistance was measured by applying repeated three-point bending deflection to the specimens. For statistical analysis, Kruskal-Wallis test followed by Dunns multiple comparison tests were used. The Kruskal-Wallis test revealed significant differences in the fatigue resistance among some groups (p<0.05). Conventional- and rapid-heat polymerized resins had lower fatigue resistance values than heat-polymerized high impact acrylic resin, but the differences were statistically non-significant according to Dunns test (p>0.05). High impact acrylic resin was also found to have significantly higher fatigue resistance value than that of self-cured resin and light-cured resin (p<0.05). Further, there was no statistically significant difference between the mean fatigue resistance value of visible light-cured resin and self-cured resin (p>0.05).

Fatigue resistance of acrylic resin denture base material reinforced with E‐glass fibres

OBJECTIVE The purpose of the study was to determine the effect of different forms and concentrations (2.5, 3, 4, 5% by volume) of glass fibres (chopped strand mat, continuous and woven) on fatigue resistance of acrylic denture base resin. MATERIAL AND METHODS The fatigue resistance was measured by applying repeated three-point bending deflection to the specimens, the cycle frequency of 1.05 g and magnitude of deflection of 2.0 mm. The number of loading cycles needed to cause a fracture in the test specimen was considered the fatigue resistance of the specimen. RESULTS The results of this study revealed that the addition of three different glass fibre forms at all concentrations to acrylic resin did not produce a statistically significant increase in the fatigue resistance (p ≥ 0.05). This study also revealed that there were significant differences (p < 0.05) between glass fibres forms used concerning the effects on the fatigue resistance. CONCLUSION This study showed that the woven glass fibres had a definite superiority over the chopped fibres and the continuous fibres in regard to the fatigue resistance of the acrylic denture base resin.

Radiological study on mandibular ramus asymmetry in young population

BACKGROUND The aim of this study was to estimate the prevalence of ramus asymmetries related to age and gender in a young population and the influence of growth spurt on ramus asymmetry. MATERIALS AND METHODS The study consisted of 776 panoramic radiographs of individuals aged 9 to 21 years (335 males and 441 females). Individuals were divided into two groups with respect of linear growth spurt as age 12 in females and age 14 in males. The first group consisted of females aged between 9 and 11 and males between 9 and 13. The second group consisted of females aged between 12 and 21 and males between 14 and 21. Bilateral ramus heights on each radiograph were measured. A panoramic software programme was used to measure the ramus heights. Quantitative data was tested by Students t test. Qualitative data was tested by χ2 test. The intraclass correlation coefficient was calculated for the magnitude error of the measurement. RESULTS The mean of ramus asymmetry was found to be 2.90% ± 2.58%. Significant differences between the right and left ramus height ratios were observed (p < 0.01). There was a high prevalence (10.8%) of ramus asymmetry, which did not correlate with the age and gender of the patients. CONCLUSIONS This study revealed a high prevalence of ramus asymmetry in 9-21- -year-old population. Within the limitations of this study, it can be concluded that ramus asymmetry should be carefully evaluated in all ages for the potential relation with temporomandibular dysfunctions and also for orthodontic anomalies.

Comparative study of impact strength of six acrylic denture resins

Abstract The aim of this in vitro study was to compare the impact strength of three kinds of heat polymerised acrylic resin: a microwave polymerised acrylic resin, a visible light cured resin and a self-cured acrylic resin. From a group of six different materials, a total of 60 specimens (75 × 10 × 3 mm) were fabricated, 10 from each material. The impact strength was evaluated using the Charpy method. The test was performed at room temperature in an impact testing machine (Zwick pendulum impact tester; Zwick GmbH & Co. KG, Ulm, Germany) of a capacity of 0–7·5 J scale; the specimens were fractured. For statistical analysis, Kruskal–Wallis test followed by Dunns multiple comparison test was used. The impact strength values exhibited statistically significant differences among acrylic resin groups (p=0·0001). High impact strength acrylic resin showed the highest mean impact strength value among the materials tested.