Possibility of Making Crowns on Canines

The need for prosthetic care of injured canines is evident. Canine morphology provides for the possibility of preparation of the tooth crown and placement of an artificial crown on the abutment. The study presents an original approach to the preparation of the tooth crown, impression, crown testing and cementing

A facile route to a novel aza-crown ether incorporating three thiophene moieties

The preparation of the first of a novel type of large thiophene-containing aza-crown ether is reported. The macrocycle is synthesised by linking a 3,4-dialkoxythiophene moiety with two 3-hydroxythiophene units and ring closure is effected by reaction with piperazine via the Mannich reaction

STUDENTS’ PERCEPTION AND SATISFACTORY LEVEL FOR PREPARATION OF PORCELAIN FUSED TO METAL CROWN IN PRECLINICAL FIXED PROSTHODONTICS: PERSEPSI DAN TINGKAT KEPUASAN MAHASISWA TERHADAP PREPARASI MAHKOTA PORSELIN DI PREKLINIK PROSTODONTI CEKAT

Preclinical session is one way of training dental undergraduates to prepare teeth for restorations. The aims of the study were to evaluate students’ perception and satisfactory level in preparing tooth for porcelain fused to metal crown in preclinical fixed prosthodontics sessions. A total of 104 fourth year dental undergraduates students participated in this study. Lecture consisted of the diagrams of step-by-step procedure in preparing porcelain fused to metal crown on tooth 24. Video demonstration was also conducted. After they were satisfied with the preparation, they were asked to answer a series of multiple choice questions on their performance. Only 92 students completed the questionnaire. Majority of the students taught that their occlusal and axial reductions were about right. As for the margin, 50 students claimed that the margin was located on gingival margin while 88 students said that they prepared shoulder margin buccally and 4 students created chamfer margin buccally. Seventy four out of 92 students were slightly satisfied with their crown preparations. Twenty five students said that they were very competent and confident in doing crown preparation to patients. Almost all fourth year dental students could perform porcelain-fused-to-metal crown preparation with confidence. As conclusion, exposure to our teaching methods and aids appears to help them in preparing these tasks

Droplet Distribution in a University Dental Clinic Setting: The Importance of High-Volume Evacuation

The purpose of this study is to compare droplet distribution during a piezoelectric ultrasonic debridement procedure using either high-volume or slow-volume evacuation. Droplet distribution during a crown preparation with slow-volume evacuation is also examined. Fluorescein dye is added to the water reservoir and the procedures are performed by a single operator for 15 min on a dental manikin with artificial upper and lower teeth. Placement of filter paper squares (10 cm × 10 cm) in radiating lines away from the oral cavity of the dental manikin allows for visualization of droplet dispersion. Results show minimal difference in the spread of the droplets between the two evacuators during the debridement procedure; however, the slow-volume evacuator produces a higher concentration of droplets than the high-volume evacuator. An even higher concentration of droplets in the vicinity of the dental chair is observed during the crown preparation procedure. This study recommends the use of a high-volume evacuator where possible during professional debridement and crown preparation to reduce contamination around the dental chair from potentially pathogenic microorganisms

Comparison of two canal preparation techniques using Mtwo rotary instruments

INTRODUCTION: Root canal preparation is an important process in endodontic therapy. Nickel-titanium (NiTi) rotary file system can be used in single length technique (simultaneous technique) without early coronal enlargement, as well as in crown-down method. The purpose of this in vitro study was to compare single length with crown-down methods’ shaping ability using Mtwo NiTi files.MATERIALS & METHODS: Fifteen acrylic-resin blocks containing simulated canals were divided into two experimental groups. In group A, single length technique was used and in group B root canals were prepared by crown-down technique. Pre- and post-preparation canals were photographed in a standardized manner and were superimposed. The inner and outer walls of canal curvature were evaluated at three points (apical, middle and coronal) to determine the greatest change. The data was statistically analyzed using the Student t-test by Statistical Analysis System (SAS) software. RESULTS: Statistical analysis revealed that in group B, dentine was equally removed within the canal coronal to the curvature, whereas in group A, the inner wall was predominantly removed (P < 0.01). The two groups had no significant difference at the apical and middle points of the canal curvature.CONCLUSION: Our in vitro study revealed no significant difference between the single length method and crown-down technique using Mtwo for preparation of apical and middle portion of canal curvature.

Interdisciplinary Approach for Management of Iatrogenic Internal Root Resorption: A Case Report

For management of a symptomatic maxillary lateral incisor with dull pain on chewing, suppurative sinus tract, defective metal-ceramic crown and iatrogenic internal root resorption, an interdisciplinary approach was taken. Two-visit nonsurgical treatment with calcium-enriched mixture (CEM) cement, replacement of metal-ceramic crown with all-ceramic crown and corrective periodontal plastic surgery were included in the treatment plan. Six-month and one-year follow-ups revealed complete resolution of signs and symptoms and radiographic healing. This case report highlights the importance of adequate cooling during crown preparation to preserve the pulp vitality and prevent internal resorptive lesions and also the profound sealing ability and biocompatibility of CEM cement.Keywords: Calcium-Enriched Mixture; Interdisciplinary Treatment; Internal Root Resorptio

Two Acridone Units in One Crown Ether: Incorporating a Second Acridone

We present here a critical overview on the effects of the second heterocyclic subunit in a bisacridino-crown ether by the discussion of its role in modulating optochemical behavior and preference in molecular recognition. The preparation of a new bisacridono-crown ether is presented including synthetic difficulties, and its fluorescence properties and selectivity in formation of inclusion complexes with various cations are evaluated in the light of reported analogues

Synthesis of Bis(quinoxalino) Ligand for the Removal of Transition Metal Contamination

Transition metal contamination is a constant concern both in the environment and in chemical reaction mixtures. One proposed solution, is the use of peraza-crown macrocycles to selectively bind and remove transition metals. The aim of our project is to determine the novel synthesis of bis(quinoxalino) peraza-crown macrocycles for use as ligands to bind to transition metals. Our proposed molecules incorporate the rigid quinoxaline subunit into an aza-crown macrocycle which can improve binding properties. The synthesis route is novel and overcomes several limitations of the existing methods of aza-crown macrocycle preparation. We have designed the synthesis in such a way that it does not use a metal template and is general enough that new derivatives can be easily obtained