One of the commonest treatment options for replacing missing teeth is a root-form implant. Clinically, the key mechanical factor in achieving success is primary stability. This ex vivo study aims to evaluate whether osseodensification method will achieve good primary stability or the conventional drilling protocol. Fresh iliac bone of the sheep was selected similar to D3 and D4 bone densities. A total of 22 osteotomy sites were prepared in the bone sample, of which 11 were prepared by osseodensification method (test group) and other 11 by conventional undersized drilling (control group). Primary stability was measured using insertion torque (IT), resonance frequency analysis (RFA), and reverse torque values (RTVs) by measuring implant stability quotient (ISQ). The recorded data were statistically analyzed using Statistical Package for the Social Sciences (SPSS) Version 22.0. The differences between groups were compared using the Mann-Whitney U test and independent t-test. The Pearson correlation coefficient test was performed to measure the linear relationship between two variables. The statistical significance level was established at p<0.05. When the correlation among IT, RTV, and ISQ was measured, a statistically significant correlation between IT and RTV (p=0.001) and between IT and ISQ (p=0.0001) was observed. A statistically significant (p=0.014) correlation between RTV and ISQ was also found. Osteotomy prepared by osseodensification method showed higher IT, RTV, and ISQ values than the conventional undersized group.

The aim of the study was to assess the effect of implant placement depth on stress distribution in bone around a platform-switched and Morse taper dental implants placed at the equi-crestal and 1 mm and 2 mm sub-crestal levels in a D3 bone using the 3D finite element analysis. A mechanical model of a partially edentulous maxilla was generated from a computerized tomography (CT) scan of an edentulous patient, as it can give exact bony contours of cortical bone. Also, from accurate geometric measurements obtained from the manufacturer, 3D models of Morse taper and platform-switched implants were manually drawn. The implant and bone models were then superimposed to simulate implant insertion in bone. Three implant positioning levels such as the equi-crestal, 1 mm sub-crestal, and 2 mm sub-crestal models were created, and meshing was done to create the number of elements for distribution of applying loads. The elastic properties of cortical bone and implant, such as Young's modulus and Poisson's ratio (µ), were determined. A load (axial and oblique) of 200N that simulated masticatory force was applied. On comparing stresses within the bone around the equi-crestal and 1 mm and 2 mm sub-crestal implants, it was observed that the maximum stresses were seen within cortical bone around the equi-crestally placed implant (21.694), the least in the 2 mm sub-crestally placed implant (18.85), and intermediate stresses were seen within the 1 mm sub-crestally placed implant (18.876). Sub-crestal (1-2mm) placement of a Morse taper and a platform-switched implant is recommended for long-term success, as maximum von Mises stresses were found within cortical bone around the equi-crestal implant followed by the 1 mm sub-crestal implant and then the 2 mm sub-crestal implant.

Purpose: To analyze the stress distribution and the direction of force in external hexagonal implant with crown in three different angulations. Materials and Methods: A total of 60 samples of geometric models were used to analyze von Mises stress and direction of force with 0-, 5-, and 10-degree lingual tilt. Von Mises stress and force distribution were evaluated at nodes of hard bone, and finite element analysis was performed using ANSYS 12.1 software. For calculating stress distribution and force, we categorized and labeled the groups as Implant A1, Implant A2, and Implant A3, and Implant B1, Implant B2, and Implant B3 with 0-, 5-, and 10-degree lingual inclinations, respectively. Inter- and intra-group comparisons were performed using ANOVA test. A p-value of ≤0.05 was considered statistically significant. Results: In all the three models, overall maximum stress was found in implant model A3 on the implant surface (86.61), and minimum was found on model A1 in hard bone (26.21). In all the three models, the direction of force along three planes was maximum in DX (0.01025) and minimum along DZ (0.002) direction with model B1. Conclusion: Maximum von Mises stress and the direction of force in axial direction was found at the maximum with the implant of 10 degrees angulation. Thus, it was evident that tilting of an implant influences the stress concentration and force in external hex implants.

Pre-prosthetic implant radiographic imaging helps in the quantitative and qualitative analysis of the bone structure and also enables the evaluation of the relationship between critical structures and potential implant sites. The aim of the study was to define the reliability of utilizing the analysis of textures from the periapical radiographic images obtained through Radiovisiography (RVG) in order to better plan for dental implantations. A cross-sectional study was conducted using 50 intraoral periapical radiographs which were obtained through RVG performed prior to the placement of implants. The radiographs were segregated based on anatomical locations i.e. 12 for the anterior maxilla, nine for the posterior maxilla, seven for the anterior mandible, and 22 for the posterior mandible. Each of the radiographs was visually assessed by four experienced examiners, namely a Prosthodontist E1, Periodontist E2, Oral surgeon E3, and Oral radiologist E4, which was then compared to an experienced operator's tactile perception during a pilot drill for implant placement. As a reference, the Lekholm and Zarb classification was provided to all the examiners for them to qualitatively assess the bone structure in the radiographs. The examiners’ results were correlated with the assessment provided by the experienced operator. E1 and E4 successfully assessed 42% of the radiographs while E2 had the least success with only 26%. Of the 12 anterior maxillary radiographs, only eight were accurately assessed by E1. With respect to the posterior maxilla, all examiners correctly assessed four radiographs each. Of the seven anterior mandibular radiographs, except for E2, the rest correctly assessed three radiographs each. Of the 22 posterior mandibular radiographs, only nine were accurately assessed by E4. Intraoral periapical radiographs obtained through RVG did not meet the desired parameters for assessing the bone quality during the planning stage for implants.

Purpose: The purpose of this study was to evaluate the influence of water bath polymerization cycles on the color stability of unfilled polymethyl methacrylate (PMMA) teeth. Materials and methods: A total of 72 samples of unfilled PMMA were divided into two groups. Group 1 was subjected to a short curing cycle and group 2 to a long thermal curing cycle. Color measurements were done using a spectrophotometer and evaluated by the Commission Internationale de l’Eclairage (CIE) L*a*b* color system. Color difference (∆E) was calculated before and after thermal curing cycles and the data were statistically analyzed. Results: Group 2 teeth exhibited the highest ΔE values and color change to long curing cycle with significant difference between them. Conclusion: All the ΔE values were below 3.3, indicating that the color changes are not clinically perceptible.