An evaluation of virtually planned and 3D-printed stereolithographic surgical guides from CBCT and digital scans: An in vitro study.

STATEMENT OF PROBLEM: The process of manufacturing stereolithographic surgical guides for static computer-guided implant placement involves a series of steps. Errors can be incorporated in various forms and at various stages of manufacturing these guides. Errors introduced during this process have not been fully investigated. PURPOSE: The purpose of this in vitro study was to assess the errors introduced during the manufacture of stereolithographic surgical guides generated from cone beam computed tomography (CBCT) and digital scans by using a virtual implant planning software. MATERIAL AND METHODS: Ten stereolithographic surgical guides with the associated standard tessellation language (STL) files of their virtual design were used in this study. The STL files of the virtual design and the scans of the stereolithographic surgical guides were superimposed. Linear deviation at the center of the sleeve top and sleeve base and the angular deviation at the center of the sleeve were measured. RESULTS: The minimum and maximum linear deviation at the center of the sleeve top and the sleeve base was found to be 0 and 40 µm, with less linear deviation observed at the center of the sleeve top (mean ±standard deviation 18 ±7 µm) than at the center of the sleeve base (20 ±7 µm). The minimum and maximum angular deviation at the center of the sleeve was found to be 0 degrees and 5.9 degrees respectively, with a mean ± standard deviation of 1.36 ±0.74 degrees. CONCLUSIONS: Errors were found in the sleeve position between the virtual design and the stereolithographically manufactured surgical guide. This error may introduce errors in the final implant position.

A comparative evaluation of amount of gingival displacement produced by four different gingival displacement agents - An in vivo study.

AIM: The aim of this study was to compare and evaluate the efficacy of ViscoStat clear, Vasozine, and Racegel (with and without cord) with respect to the amount of lateral gingival displacement produced by them. SETTINGS AND DESIGN: Comparative - In vivo study. MATERIAL AND METHODS: Thirty consented volunteers were selected in the age group of 18-22 years. Maxillary right first premolar and lateral incisor and maxillary left central incisor and canine were selected for each individual. A composite resin standard reference point was made two millimeters below the gingival margin on the midsection of the labial surface of each tooth. By simple random sampling, the agents (ViscoStat clear, Vasozine, and Racegel with cord and Racegel without cord) were used for gingival displacement on each of the selected teeth. Pre- and postgingival displacement impressions were made with medium-body polyvinyl siloxane impression material. Three-millimeter thick buccolingual slice sections were obtained of the models and measured under a stereo microscope (×20 magnification), and the amount of displacement was calculated. STATISTICAL ANALYSIS USED: The Kruskal-Wallis test and the Mann-Whitney U-test were used for comparison between the amounts of gingival displacement produced by them. RESULTS: Mean displacement produced (in mm2) by Racegel with cord, tetrahydrozoline, ViscoStat clear, and Racegel is 0.2256, 0.2158, 0.2069, and 0.1414, respectively. CONCLUSIONS: The largest mean gingival displacement was produced by Racegel with cord (0.2256 mm2) and lowest by Racegel without cord (0.1414 mm2). There was no significant statistical difference in the amount of gingival displacement produced between the four agents.

Comparative evaluation of the depth of curve of Spee between individuals with normal dentition and individuals with occlusal wear using conventional and digital software analysis techniques: An in vivo study.

OBJECTIVES: The objective of this study is to evaluate and compare the depth of curve of Spee in normal dentitions and dentitions with occlusal wear using conventional and digital software techniques. MATERIALS AND METHODS: A total of 70 healthy human subjects were selected for this study in an age group of 20-50 years. Group A includes the stone models (dental casts) of 35 individuals with healthy (nonattrited) dentition. Group B includes stone models of 35 individuals with occlusal wear (generalized attrited) dentition. Two methods were used for measuring the curve of Spee, i.e., conventional method and three-dimensional digital analysis method. RESULTS: Depth of the curve of Spee between these two groups was statistically the same. The Digital software analysis (Method II) gives more accurate readings when compared with the Conventional (Method I) of measuring the depth of the curve of Spee. CONCLUSION: Depth of curve of Spee is maintained through the life. There is no statistical difference in depth of curve of Spee between the two groups and digital method give more accurate measurements.

A study comparing trial registry entries of randomized controlled trials with publications of their results in a high impact factor journal: The Journal of the American Medical Association.

PURPOSE: The International Committee of Medical Journal Editors mandates trial registration as a precondition for publication. Growing evidence indicates that information in registry may not correlate with eventual publication. The present study was carried out with the objective of comparing content of Randomized Controlled Trials (RCTs) published in one year in the Journal of the American Medical Association (JAMA), with the information contained in trial registries. METHODS: All RCTs published in JAMA in 2013 were included. 11 data set items were matched for content between registry entry and published RCT: Title, Primary and Secondary Objectives, Study type, Inclusion and Exclusion Criteria, Treatment Age Group, Follow up, Sample Size, Primary and Secondary Outcomes. A fully correct match was scored 2, partially correct 1 and incorrect 0. Thus, maximum possible score for each paper was number of items multiplied by 2, i.e., 22. RESULTS: The median [range] total score achieved by RCTs was 15. No RCT achieved a perfect score of 22. The largest proportion of RCTs reported secondary objectives, study type, treatment age group, follow up, sample size and primary outcomes fully correctly. However, only 13.5 %, 12 % and 13.5 % of RCTs were a perfect match with registry entries in terms of title, primary objective and secondary outcomes respectively. Almost three quarters did not match perfectly in selection criteria. CONCLUSION: There exist discrepancies between trial registration and published paper even in a high impact factor journal. Both authors and editors should adhere to CONSORT guidelines to ensure transparency of published research.

Osseoperception: An Implant Mediated Sensory Motor Control- A Review.

Osseointegration of dental implants has been researched extensively, covering various aspects such as bone apposition, biomechanics and microbiology etc however, physiologic integration of implants and the associated prosthesis in the body has received very little attention. This integration is due to the development of a special sensory ability, which is able to restore peripheral sensory feedback mechanism. The underlying mechanism of this so-called 'osseoperception' phenomenon remains a matter of debate. The following article reveals the histological, neurophysiologic and psychophysical aspects of osseoperception. A comprehensive research to provide scientific evidence of osseoperception was carried out using various online resources such as Pubmed, Google scholar etc to retrieve studies published between 1985 to 2014 using the following keywords: "osseoperception", "mechanoreceptors", "tactile sensibility". Published data suggests that a peripheral feedback pathway can be restored with osseointegrated implants. This implant-mediated sensory-motor control may have important clinical implications in the normal functioning of the implant supported prosthesis.