A Comparative Evaluation of Vertical Marginal Gap for Vented and Precemented Cad-Cam Zirconium Copings on Angulated Abutments: An In vitro Study.

Objective: To evaluate vertical marginal gap after cementation of Zr (zirconium) copings with palatal vent, open vent, and precementation technique on angulated abutments resulting from cement entrapment between intaglio surface of copings and angulated abutments. Materials and Methods: Twenty-four angled abutments and 24 CAD-CAM Zr copings were assigned to three groups depending on the type of cementation technique, comprising eight copings with palatal vent, open vent, and no vent, respectively. Vertical marginal gaps between abutment shoulder and coping margin were evaluated at four points: buccal, palatal, mesial, and distal. The readings were statistically analyzed. Results: The average mean value of vertical marginal gap at all sites for Group A with palatal vent was 158.45, for Group B with open vent was 151.84, and for Group C using precementation technique was 163.58. A statistically non-significant difference was seen for values between all sites (P > 0.05) for all groups. Conclusion: The average vertical marginal gap for Group B was comparatively lower compared to Groups A and C.

A comparative evaluation of fracture resistance of tooth restoration complex restored with PEEK and lithium disilicate endocrowns.

PURPOSE: This in vitro study was conducted to compare the fracture resistance of tooth restoration complex restored with polyetheretherketone (PEEK) and lithium disilicate endocrowns. MATERIALS AND METHODS: A total of 46 extracted premolars were collected and treated endodontically. The teeth were mounted in cylindrical molds using autopolymerizing resin and were prepared for endocrown restoration. Specimens were divided into two groups (n = 23) to receive endocrowns made with two different materials (polyetheretherketone and lithium disilicate). All the specimens were subjected to thermal cycling. The fracture resistance test was carried out using a Universal Testing Machine. Fractographic analysis was carried out using stereomicroscope and scanning electron microscope after load test. The values obtained were subjected to statistical analysis. Intergroup comparison (two groups) was performed using a t-test. Comparison of frequencies of categories of variables with groups was performed using chi-square test. RESULTS: Fracture resistance tests showed a statistically significant difference in values between the two groups (p < 0.01). High fracture resistance values were seen with lithium disilicate endocrowns. Failure mode analysis showed that both groups exhibited mainly catastrophic failure. There were no significant differences in frequencies of the type of fracture between the groups. CONCLUSION: The fracture resistance of endocrowns fabricated with lithium disilicate material was found to be significantly higher than polyetheretherketone (PEEK) material. Hence, lithium disilicate material is superior for endocrowns.

Assessment of the factors influencing dental students to choose dentistry as a career: A cross-sectional survey.

OBJECTIVE: Career choice, one of the most important process in a student's life, has an influence on his/her future life. Hence, it is important to understand student's motives behind choosing a specific career. Hence, the study was designed with an aim to evaluate the factors influencing dental students to choose dentistry as career. METHODS: The present cross-sectional survey was conducted on 401 dental students from a dental institute. The data was collected using a structured questionnaire consisting of 13 reasons that possibly influenced students' decision to study dentistry. Data collected was analyzed using SPSS 20 software. RESULTS: Majority of the students participating were female (77.1%). Top four reasons to choose dentistry as a profession were to help poor people (95.5%), to earn prestige and respect (95.0%) followed by self-interest (94.7%) and study of human parts especially teeth (92.8%). Making money was the reason reported by 77.8% of the students. Other reasons reported were inspiration from other dentists (63.3%), did not get admission to medicine (MBBS) course (52.1%), and no doctor in family (51.9%). Family members in medical/dental profession was the least reported reason (36.9%). There were no significant differences among males and females for reported reasons except for one reason, that is, did not get admitted to medicine (MBBS) course (60.9% male and 48.9% female; P = 0.031). CONCLUSION: Students were mostly influenced by own interest and altruistic nature to opt for dental profession.

Effect of Time and Method of Drying on Bond Strength of Tray Adhesives with Vinyl Polysiloxanes.

AIM: To establish an effective combination of drying time and drying method of the tray adhesive so that maximum bond strength can be achieved between impression tray and impression material. MATERIALS AND METHODS: Cylindrical specimens of auto-polymerizing resin and addition silicone impression material were made. A total of 150 specimens were tested. They were divided into two groups Dentsply and GC. Each group was further divided into five subgroups: • Drying with compressed air for half the time as recommended by the manufacturer • Drying with air blower for half the time as recommended by the manufacturer • Open air drying as recommended by the manufacturer • Open air drying for 15 minutes • Open air drying for 1 hour The samples were tested for tensile bond strength using the universal testing machine. The results were subjected to statistical analysis. RESULT: Open air drying as recommended by the manufacturer was better than drying with a blower or compressed air. There was no significant difference between open-air drying for 5 minutes and open-air drying for 15 minutes or 1 hour. CONCLUSION: Open air drying as recommended by the manufacturer, i.e. 5min, showed good bond strength and drying for more than 5mins does not significantly increase bond strength. CLINICAL SIGNIFICANCE: Tray adhesive should not be dried with compressed air or air blower. Tray adhesive should be applied and kept to dry according to the manufacturer's recommended time.

Reinforcement of Aluminum Oxide Filler on the Flexural Strength of Different Types of Denture Base Resins: An In vitro Study.

INTRODUCTION: Acrylic resins have been used extensively for the fabrication of denture bases because of their aesthetic qualities, ease of manipulation and repairability. Flexural fatigue of the denture base has been shown to be a factor in the clinical failure of polymethyl methacrylate resin dentures. Also, the fracture can result from impact, fatigue or degradation of the base material. Hence, there is a need to increase the strength of denture base resins. AIM: To evaluate the effect of reinforcing alumina oxide filler on the flexural strength of different acrylic resins. MATERIALS AND METHODS: A total of 180 acrylic specimens were fabricated, which were divided into three groups self cure acrylic resin (SC), conventional heat cure resin (HC) and high strength heat cure resin (HI). Each group was divided into four subgroups i.e., control group and the specimens of the remaining three groups were reinforced with aluminum oxide (Al2O3) powder by 5%, 10% and 15% by weight. Specimens were stored in distilled water for one week; flexural strength was tested by universal testing machine. Results were analysed by one-way analysis of variance and post-hoc Tukey paired group comparison tests. RESULTS: Flexural strength of SC increased by 9%, 13% and 19%, Flexural strength of HC increased by 8%, 15% and 19% and that of HI increased by 21%, 26% and 29% compared to control group by adding 5%,10% and 15% of alumina filler (p-value <0.001). Addition of 15% of alumina powder to SC showed high flexure strength compared to control group of HC (p-value <0.001). Addition of 10% and 15% of alumina powder to HC showed high flexural strength compared to control group of HI (p-value <0.001). CONCLUSION: Addition of alumina to self cure acrylic resin, conventional heat cure acrylic resin and high strength heat cure acrylic resin increased the flexural strength. Increasing the flexural strength of the acrylic resin base material could lead to more clinical success.