Effect of Two Different Ultrafast Curing Exposure Durations on the Surface Hardness of Bulk Fill Composite - An In-Vitro Study.

AIM: The aim of the present study is to assess the microhardness of resin-based composites (RBCs) cured with ultrafast curing mode at two different exposure durations. STUDY DESIGN: This is an experimental in-vitro study. Forty-five cylindrical composite specimens were prepared to a dimension of 5 mm height and 4 mm diameter. Curing was done using three different exposure modes and duration with dual mode LED curing light as follows: Group I: Ultrafast curing mode for 1 second at 2300 mW/cm2 (n = 15); Group II: Ultrafast curing mode for 3 second at 2300 mW/cm2 (n = 15) and Group III: Standard exposure mode for 20 second at 1000 mW/cm2 (n = 15). Vicker's microhardness measurement was done on both the curing and non-curing sides of the specimen using a motorised diamond-faced micro-indenter (Wilson Wolpwert, Germany) using a load of 50 gram and a dwell time of 30 second. STATISTICAL ANALYSIS: Kruskal Wallis ANOVA was used to test for difference between the three groups followed by Mann-Whitney U test for post-hoc analysis. RESULTS: The microhardness values of the composite cured with a conventional curing unit were significantly higher than the ultrafast cured specimens. CONCLUSION: Low-intensity conventional curing lights were found to perform better than the high-intensity ultrafast curing units.

Comparative evaluation of the degree of conversion of four different composites polymerized using ultrafast photopolymerization technique: An in vitro study.

CONTEXT: Lower degree of conversion (DC%) of monomer to polymer in a resin composite restoration could be a health hazard for the patient as well as it could affect the longevity of the restoration. AIMS: This study is aimed to compare and evaluate the DC% of four different composites polymerized using ultrafast photopolymerization. SETTINGS AND DESIGN: In-vitro study. MATERIALS AND METHODS: A total of 40 disc-shaped composite samples were used in the study. Twenty samples were prepared for each group using 2 mm height and 6 mm diameter Tygon tube as a matrix. All of the composites were cured using the Woodpecker i Led light-curing unit with an intensity of 2300-2500 mW/cm2 (TURBO mode). Samples in Group 1 were cured for 1 s and samples in Group 2 were cured for 3 s. Each group had 4 subgroups of five samples of the 4 resin composites tested. After photo-activation, the specimens were stored under dark dry conditions at room temperature for 24 h before testing. The DC% was measured using Fourier-transform infrared spectroscopy. STATISTICAL ANALYSIS USED: The DC% were analyzed using ANOVA, and Tukey HSD post hoc test using IBM SPSS 21 software. RESULTS: Among the experimental groups, Group 2 showed a higher DC% which ranges from 93.7% to 95.4% than Group 1 which ranges from 58.5% to 65.5%. There was a statistically significant difference in the DC% among the materials tested (P < 0.05). CONCLUSIONS: Within the limitations of the study, it was concluded that composites cured for 3 s showed a higher DC% which ranges from 93.7% to 95.4% than those cured for 1 s. The DC% also varied among the four different composites tested.

Structure bound guide to access cavity preparation for molar root canal treatment.

A good access cavity preparation is the gateway to success in endodontic treatment. This article presents occlusal landmarks that can be used as the boundary for the endodontic access at the occlusal surfaces of maxillary and mandibular molars. Further this article gives a structure or landmark guided three simple stages of preparation to reach the pulp chamber. This assures an ideal access cavity reducing the risk of dentin gouging and eliminating iatrogenic deleterious events. All canal orifices will be within this boundary and can often be located easily.

Evaluation of remaining dentin thickness around the prepared root canals and its influence on the temperature changes on the external root surfaces during different heated gutta-percha obturation techniques.

CONTEXT: Temperature rise on external root surface has a deleterious effect on the periodontium. AIMS: To compare and evaluate the temperature changes on the external root surfaces using three different heated gutta-percha obturation techniques and also to evaluate the effect of remaining dentin thickness (RDT) on the temperature rise during obturation. SETTINGS AND DESIGN: In vitro study with a customized temperature measurement setup. MATERIALS AND METHODS: Thirty decoronated human maxillary central incisors were cleaned and shaped using standardized method. RDT was measured using cone beam computed tomography. They were divided into three groups of 10 samples each. Group 1 was obturated by traditional warm vertical compaction, Group 2 using solid core obturation, and Group 3 by warm vertical compaction technique using GP heater in vibration mode. AH Plus sealer was used as cement sealer. During obturation, the temperature rise was measured using K-type thermocouples in the coronal, middle, and apical thirds. The highest temperature rise during the procedure was recorded. STATISTICAL ANALYSIS USED: Data were analyzed by one-way analysis of variance and post hoc Tukey's test. RESULTS: Traditional warm vertical compaction had the highest temperature change followed by warm vertical compaction using GP heater in vibration mode and solid core obturation. CONCLUSION: There was a temperature rise on external root surfaces in the three techniques evaluated. Solid core obturation technique showed the least temperature change. There was no significance in the effect of RDT on temperature rise during obturation.

Report of occurrence and endodontic management of three-rooted maxillary first and second premolars in the same individual.

Anatomical variations should be kept in mind in clinical and carefully looked for in radiographic evaluation during endodontic treatment of maxillary premolars. These teeth have highly variable root canal morphology. Although three separate roots in the maxillary first premolars have been reported, it is a rarity to find both the first and second premolars possessing three separate roots. This case report describes the diagnosis and endodontic management of maxillary first and second premolars with three canals and three separate roots. Access cavity refinements were required for stress-free entry to the complex anatomy.

Evaluation of dental expertise with intra-oral peri-apical view radiographs for forensic identification.

BACKGROUND: Identification of a dead person is important in starting the investigation into the circumstances of death. In the absence of forensic odontologist, it is vital that general dentists are able to compare the ante mortem-post mortem (AM-PM) records and with their ability, correctly interpret the individuality of the person. AIMS: This study wascarried out to find out the accuracy with which undergraduate, graduate and post-graduate dentists can do this comparison, using the simulated AM-PM intra-oral peri-apical (IOPA) view radiographs. SETTING AND DESIGN: A total of 60 investigators of which 20 undergraduate students, 20 general dentists, 20 post-graduate dentists viewed 10 pairs of simulated AM and PM radiographs and recorded their findings. MATERIALS AND METHODS: Ten pairs of simulated AM-PM IOPA view radiographs were given to 60 dentists to investigate their discriminatory potential for dental identification purposes. The results were statistically analyzed. STATISTICAL ANALYSIS: χ(2) -test and Mann-Whitney U-test were carried out to compare the sensitivity, specificity and accuracy of the three types of examiners (UG, G, PG). RESULTS: The results showed sensitivity of 59.8%, specificity of 62.6%, accuracy of 61% for undergraduate students, sensitivity of 86.6%, specificity of 87.5%, accuracy of 87% for graduate doctors, sensitivity of 89.3%, specificity of 92.3% and accuracy of 90.5% for post-graduate doctors respectively. CONCLUSION: Inexperienced investigators in forensic identification showed fairly acceptable results, therefore, introduction of forensic odontology in an undergraduate course may help general dentists to provide better service, if required, in the absence of a forensic odontologist.

A study of composite restorations as a tool in forensic identification.

INTRODUCTION: Comparing ante-mortem and post-mortem dental data is a principal method of identification in forensic odontology. Radiographic images of amalgam have been used in dental forensics for identification due to their unique appearance. AIM: The aim of this study was to investigate whether radio-opaque composite restorations have a potential for identification in forensic odontology. MATERIALS AND METHODS: Thirty typodont mandibular first molar teeth were prepared with Class-II (proximo-occlusal) cavities and restored with a radio-opaque composite (Tetric N-Ceram). Two sets of standardized radiographs were taken from the 30 teeth, keeping the radiological parameters constant. One set of these 30 radiographs was named as SET 1. Ten randomly chosen radiographs from the other set and two other radiographs of Class-II composite restorations in typodont teeth constituted SET 2. Thirty dentally trained examiners were asked to match the 12 radiographic images of SET 2 with those of SET 1. RESULTS: The results show that 15 examiners were able to correctly match all the 12 images. Statistical analysis was done using kappa statistical test. CONCLUSION: This study shows that, if the post-mortem radiographs are accurate duplicates of ante-mortem radiographs of composite restorations, then the shape of the composite restoration is unique and can be used for identification.

Evaluation of working length determination methods: an in vivo / ex vivo study.

This comparative study was done to determine the accuracy in measuring the working length of root canal using tactile method, electronic apex locator and radiographic method, in vivo and comparing the lengths so measured to the actual working length, ex vivo, after extraction. Thirty single-rooted teeth scheduled for extraction were selected for the study. After obtaining the consent from patients, a preoperative radiograph was taken and access opening was done. Working length was determined by tactile method, by using Ingle's radiographic method and by using a Foramatron-IV digital apex locator. The teeth were then extracted and the actual working length was determined by placing an endodontic file in the root canal 0.5 mm short of the apex. The results indicated that among the three methods, the electronic apex locator showed the highest accuracy and the highest reliability for working length determination.