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.

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.

A Comparative Evaluation of Shear Bond Strength Between Two Commercially Available Heat Cured Resilient Liners and Denture Base Resin with Different Surface Treatments.

BACKGROUND: Soft denture liners are widespread materials used in prosthetic dentistry. Their mechanical properties have to meet several key requirements such as adequate bond to denture base resins in order to provide right function of masticatory system and oral hygiene. AIM: To evaluate and compare the shear bond strength between two commercially available liners and polymethyl methacrylate (PMMA) denture base resin with different surface treatments. MATERIALS AND METHODS: The two soft denture liners - Luci-Sof (silicone based liner) and Super-Soft (acrylic based liner) and a polymethyl methacrylate denture base resin (Trevalon) were chosen for the study. A total of 80 samples were made, 40 each for each of the two materials under investigation. The 40 samples were further divided into four groups, containing 10 samples each. Group I: Consisted of an untreated surface of polymethyl methacrylate which acted as the control. Group II: The surface of polymethyl methacrylate surface was sandblasted. Group III: The polymethyl methacrylate surface was treated with monomer. Group IV: The lining material was processed with acrylic resin dough. The samples after thermocycling for 500 cycles with temperatures from 5° ± 1°C to 55° ± 1°C and a 60 sec dwell time were subjected to shear loading on universal testing machine at crosshead speed of 20mm/sec. A Scanning Electron Microscope and stereomicroscope analysis of the bond interface between the liner and the denture base was conducted for all the groups of the two materials under study. STATISTICAL ANALYSIS: Data was analyzed using independent samples t-test, analysis of variance (ANOVA) and Post-Hoc Analysis. A significance level of α = 0.05 was used for statistical analyses. RESULTS: The bond strength was significantly different between Super- Soft and Luci-Sof (p<0.05) for all surface treatments. The scanning electron microscopy observations showed that the application of surface treatments modified the surface of the denture base resin. CONCLUSIONS: Super-Soft exhibited significantly higher bond strength than Luci-Sof. It was observed that Super-Soft when packed with the pre-polymerized samples produced highest bond strength values among all the groups for both the materials under study. The lowest bond strength was achieved for pre-polymerized samples when packed with Luci-Sof.

An in-vitro evaluation of effect of EDTAC on root dentin with respect to time.

BACKGROUND: The present study was devised to evaluate the effects of 17% EDTAC on smear layer removal and on the dentin structure after irrigation with 1 minute and 10 minutes. MATERIALS & METHODS: One hundred extracted mandibular molars with two separate mesial canals were selected; mesiobuccal canal was instrumented to size 30 file with crown down technique. One half of each root (either mesial or distal) was randomly selected and prepared for scanning electron microscopic (SEM) evaluation that was then cut longitudinally into two equal segments. Using 10 ml of 17% EDTA solution, halves belonging to the same root were irrigated for 1 and 10 min, respectively. All specimens were subjected to irrigation with 10 ml of 5% NaOCl. Then all the specimens were prepared for SEM evaluation. RESULTS: The results showed that 1 min EDTA irrigation is effective in removing the smear layer. However a 10-min application of EDTA caused excessive peritubular and intertubular dentinal erosion. CONCLUSION: Therefore we suggest that this procedure should not be prolonged >1 min during endodontic treatment. How to cite the article: Darda S, Madria K, Jamenis R, Heda A, Khanna A, Sardar L. An in-vitro evaluation of effect of EDTAC on root dentin with respect to time. J Int Oral Health 2014;6(2):22-7.