The efficiency of root canal disinfection using a diode laser: in vitro study.

AIMS: The aim of this study is to verify the disinfection of diode laser, following chemo-mechanical procedures against Enterococcus fecalis. MATERIALS AND METHODS: Crowns of 30 extracted premolar teeth were sectioned at the cemento- enamel junction. The canals were shaped using step-back technique to K-file #40. The teeth were randomly assigned to three groups and placed into nutrient broth containing bacterial suspension of Enterococcus fecalis. Group A received no laser radiation. Specimens of group B and C were treated with diode laser (Sirona) with energy set at 1.5 and 3 W, respectively. After laser irradiation, the teeth were placed in vials, which contained 2 mL of the nutrient broth. The vials were incubated at 37°C for 24 h. Grown colonies were identified by standard methods. STATISTICAL ANALYSIS USED: Statistical analysis used was the nonparametric Kruskal-Wallis test, with comparison using the Bonferroni methods of means. RESULTS: Higher mean CFU/mL is recorded in Group A (without laser disinfection) followed by Group B (with 1.5 W laser disinfection) and Group C (with 3 W laser disinfection), respectively. The difference in CFU/mL between the three groups is found to be statistically significant ( P < 0.001). CONCLUSIONS: The results of this research show that the 980 nm diode laser can eliminate bacteria that has immigrated into dentin, thus being able to increase the success rate in endodontic therapy.

Incidence of apical root cracks and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths.

INTRODUCTION: The aim of this study was to compare the incidence of apical root cracks and dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. METHODS: Two hundred forty mandibular incisors were mounted in resin blocks with simulated periodontal ligaments, and the apex was exposed. The root canals were instrumented with rotary and hand files, namely K3, ProTaper, and nickel-titanium Flex K files to the major apical foramen (AF), short AF, or beyond AF. Digital images of the apical surface of every tooth were taken during the apical enlargement at each file change. Development of dentinal defects was determined by comparing these images with the baseline image. Multinomial logistic regression test was performed to identify influencing factors. RESULTS: Apical crack developed in 1 of 80 teeth (1.3%) with hand files and 31 of 160 teeth (19.4%) with rotary files. Apical dentinal detachment developed in 2 of 80 teeth (2.5%) with hand files and 35 of 160 teeth (21.9%) with rotary files. Instrumentation with rotary files terminated 2 mm short of AF and did not cause any cracks. Significantly less cracks and detachments occurred when instrumentation with rotary files was terminated short of AF, as compared with that terminated at or beyond AF (P < .05). The AF deviated from the anatomic apex in 128 of 240 teeth (53%). Significantly more apical dentinal detachments appeared in teeth with a deviated AF (P = .033). CONCLUSIONS: Rotary instruments caused more dentinal defects than hand instruments; instrumentation short of AF reduced the risk of dentinal defects.

Comparing microleakage and layering methods of silorane-based resin composite in class V cavities using confocal microscopy: An in vitro study.

AIMS: This in vitro study compared the effects of different layering techniques on the microleakage of silorane-based resin composite using confocal laser scanning microscope. MATERIALS AND METHODS: Forty caries free premolars extracted for orthodontic reasons were used. A class V cavity was prepared on the buccal surface in each of the premolars, with the gingival margin of the cavity being 1 mm above cementoenamel junction. The cavities were restored with a silorane-based resin composite (Filtek(™) P90 Silorane Low Shrink Restorative, 3M ESPE) using two different layering techniques - split incremental and oblique layering technique. All samples were subjected to 1000 thermal cycles of 5°C/55°C in water with a 30 second dwell time, and after the procedure, the teeth were immersed in 0.6% aqueous rhodamine dye for 48 hours. Sectioned samples were examined under a Confocal Fluorescence Imaging Microscope (Leica TCS-SP5, DM6000-CFS) at 10× magnification, and microleakage scores were analyzed statistically using paired "t" test and Mann-Whitney test. Width of interface between the tooth surface and resin composite was measured using a digital scale (Snagit digital scale). RESULTS: Microleakage was seen along the entire perimeter of restoration irrespective of the layering technique used. The microleakage score was same in both the groups. Statistical analysis of width of interface showed significant difference between the two layering techniques. The width was significantly less in split incremental technique, indicating less polymerization shrinkage. CONCLUSIONS: This in vitro study showed that the silorane-based resin composite shows microleakage irrespective of the layering technique used for class V cavities. However, this problem can be minimized significantly by using split incremental technique for restoration of class V lesions.

Survival rates of porcelain laminate restoration based on different incisal preparation designs: An analysis.

BACKGROUND: Veneer restorations provide a valid conservative alternative to complete coverage as they avoid aggressive dental preparation; thus, maintaining tooth structure. Initially, laminates were placed on the unprepared tooth surface. Although there is as yet no consensus as to whether or not teeth should be prepared for laminate veneers, currently, more conservative preparations have been advocated. Because of their esthetic appeal, biocompatibility and adherence to the physiology of minimal-invasive dentistry, porcelain laminate veneers have now become a restoration of choice. Currently, there is a lack of clinical consensus regarding the type of design preferred for laminates. Widely varying survival rates and methods for its estimation have been reported for porcelain veneers over approximately 2-10 years. Relatively few studies have been reported in the literature that use survival estimates, which allow for valid study comparisons between the types of preparation designs used. No survival analysis has been undertaken for the designs used. The purpose of this article is to attempt to review the survival rates of veneers based on different incisal preparation designs from both clinical and non-clinical studies. AIMS AND OBJECTIVES: The purpose of this study is to review both clinical and non-clinical studies to determine the survival rates of veneers based on different incisal preparation designs. A further objective of the study is to understand which is the most successful design in terms of preparation. MATERIALS AND METHODS: This study evaluated the existing literature - survival rates of veneers based on incisal preparation designs. The search strategy involved MEDLINE, BITTORRENT and other databases. STATISTICAL ANALYSIS: Data were tabulated. Because of variability in the follow-up period in different studies, the follow-up period was extrapolated to 10 years in common for all of them. Accordingly, the failure rate was then estimated and The weighted mean was computed. CONCLUSIONS: The study found that the window preparation was of the most conservative type. Incisal coverage was better than no incisal coverage and, in incisal coverage, two predictable designs - incisal overlap and butt were reported. In butt preparation, no long-term follow-up studies have been performed as yet. In general, incisal overlap was preferred for healthy normal tooth with sufficient thickness and incisal butt preparation was preferred for worn tooth and fractured teeth.

Nonsurgical endodontic treatment of type II dens invaginatus.

The endodontic treatment of teeth with dens invaginatus, characterized by an infolding of enamel and dentin, extending deep into the pulp cavity near the root apex, may be complicated and challenging. The complexity of the internal anatomy may create challenges for the complete removal of diseased pulpal tissue and the subsequent sealing of the canal system. Because of the bizarre root canal anatomy and widely open apex, a combination of nonsurgical and surgical endodontic treatment or extraction is the most common choice of therapy. This article describes case reports of nonsurgical endodontic treatment of Type II dens invaginatus associated with periradicular lesion.