Purpose: Clinical success of implant prosthodontics is dependent in part upon the type of implant thread design. The selection of implant thread design plays an important role in the outcome of the treatment. This study was undertaken to evaluate the pattern of stress distribution using a finite element analysis; hence, the area which would be bearing maximum load for a given design would be arrived. Materials and Methods: Three implants with different thread designs, namely V-thread, buttress, and reverse buttress thread designs were considered and dimensions were standardized. The site considered was the mandibular molar region with cortical and trabecular bone assuming to be isotropic and homogeneous. The implant modeling was done with the CATIA software. Vertical loads of 100N were applied. The stresses were calculated as Von Mises stress criterion. Results: Maximum stresses were seen at the cortical bone and were transferred to the implant. Minimum Von Mises stresses were seen with reverse buttress thread design at the cortical bone. The stresses were observed least at the cancellous bone and maximum at the implant. Conclusion: Hence, within the limitations of this study the results obtained can be applied clinically for appropriate selection of implant thread design for a predictable success of implant therapy.

Influence of three different implant thread designs on stress distribution: A three-dimensional finite element analysis.

Purpose: The objective of this prospective randomized clinical trial (RCT) was to analyze and compare the clinical behavior of three types of prosthesis supported by single implants in the posterior region after three years of functional loading. Materials and methods: Seventy-five implants were divided into three groups according to the type of prosthetic restoration: screw-retained crown (group GS); cemented crown without finishing line (biologically oriented preparation technique) (group GBOPT); and conventional cemented crown with finishing line (group GCC). After three years in function, clinical parameters (presence of keratinized mucosa, probing depths, bleeding on probing, and radiographic bone loss) were compared between the three experimental groups. The possible correlation between soft tissue clinical parameters and bone loss was also analyzed. Results: Statistical analysis found significant differences in clinical parameters between the different types of crown, with the cemented restoration without finishing line (BOPT) presenting fewer complications and better peri-implant health outcomes including: significantly different KMW data (mm), with significant differences between groups GBOPT and GCC (p < 0.001, Kruskal–Wallis test), with GBOPT obtaining larger quantities of keratinized mucosa (KM); statistically significant differences in probing depth (PD) values between groups GBOPT and GCC (p = 0.010, Kruskal–Wallis test); significant differences in bleeding on probing (BOP) between groups GBOPT and GCC (p = 0.018, Chi2 test) in favor of GBOPT. Conclusions: Soft tissue behavior around implants is related to the type of prosthetic restoration used, with cemented prostheses with BOPT presenting better peri-implant soft tissue behavior.

https://www.mdpi.com/2077-0383/8/12/2223/pdf

Influence of Biologically Oriented Preparation Technique on Peri-Implant Tissues; Prospective Randomized Clinical Trial with Three-Year Follow-Up. Part II: Soft Tissues

Effect of different impactor designs on biomechanical behavior in the interface bone-implant: A comparative biomechanics study

Finite element analysis of post dental implant fixation in drilled mandible sites

Background Modifying the implant surface via enhancing the wettability (hydrophilicity) improves osseointegration, reducing the healing period. In this study, the authors aimed to evaluate the stability and survival rates of implants with a hydrophilic surface compared with those with a sandblasted, acid-etched surface. Types of Studies Reviewed The included studies (randomized controlled trials) were identified through searches of PubMed, ScienceDirect, and Cochrane Library databases without date of publication restrictions. Quality assessment was performed using the Cochrane Collaboration tool. For primary outcome, confidence intervals were set at 95%; weighted means across the studies were calculated using a fixed-effects model or risk ratios and their 95% confidence intervals for secondary outcome. Results The authors included 5 randomized controlled trials (246 dental implants) in the systematic review, which compared a hydrophilic with conventional sandblasted, acid-etched implant surface. The implant stability (primary outcome) was measured at baseline and 3, 6, and 8 weeks, and implant survival rates were measured as a secondary outcome. Overall, compared with the control groups, no clinically significant differences in implant stability or survival rates were identified for the hydrophilic surface groups. Conclusions and Practical Implications The results did not show any clinically significant effect of a hydrophilic surface on improving implant stability or survival rates. However, these findings must be analyzed carefully owing to the limitations of this review, such as the small samples size and some differences among the included studies.

Implant stability and survival rates of a hydrophilic versus a conventional sandblasted, acid-etched implant surface: Systematic review and meta-analysis

Background: As various implant geometries present different biomechanical behaviors, the purpose of this work was to study stress distribution around tapered and cylindrical threaded implant geometries using three-dimensional finite element stress analysis.     Methods : Seven implant models were constructed using the CAD system. After digitized models of mandibular section, the crowns were created. They were combined with implant models, which were previously imported into CATIA. The combined solid model was transferred to ABAQOUS to create a finite element meshed model which was later analyzed regarding the highest maximum and minimum principal stresses of bone. Results: For all models, the highest stresses of cortical bone were located at the crystal cortical bone around the implant. Threaded implants, triangular thread form and taper body form showed a higher peak of tensile and compressive stress than non-threaded implants, square thread form and straight body form, respectively. A taper implant with triangular threads, which is doubled in the cervical portion of the body, had a significantly lower peak of tensile and compressive stress in the cortical bone than straight/taper triangular or square threaded implant forms. Conclusion: For the investigation of bone implant interfacial stress, the non-bonded state should be studied too. Confirmative clinical and biological studies are required in order to benefit from the results of this study. Keywords : Dental implant, Elastic (young’s Modulus), Finite element analysis method, Stress, Strain, Modulus,.

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Developing a new dental implant design and comparing its biomechanical features with four designs.

Background: The associations between Helicobacter pylori and human papillomavirus (HPV) with head and neck squamous cell carcinomas (HNSCCs) are approved before. However, the association between demographic, clinicopathological, and histologic characteristics of HNSCC patients and molecular detection of HPV and H. pylori has not been enough investigated. Materials and Methods: In this cross-sectional study, 62 patients with HNSCC from January 2016 to February 2020 were entered the study. For H. pylori detection 16S ribosomal RNA and glmM genes and HPV detection, MY09 and MY11 genes were used. P < 0.05 is considered as significant level. Results: There were 34 patients with advanced-stage cancer (54.8%). Grade I patients (61.3%) had the highest frequency. There were 20 (32.25%) and 7 (11.29%) patients with positive H. pylori infection among tumor tissue and healthy tissue margins, respectively. Positive HPV infections were in 8 (12.90%) and 3 (4.83%) patients, respectively, in tumor tissue and healthy tissue margins (P = 0.01). There was a significant difference between histological grade and infection to HPV among HNSCC patients (P = 0.01), and most of the positive HPV cases had well-, moderate-, and poorly-differentiated tumors, respectively. Our study showed a significant increase in HPV infection in the advanced-stage group compared to the early-stage group (P = 0.05). Conclusion: Our study findings concluded a significant relationship between HPV infection in HNSCC patients with age, stage, and grade. In summary, our findings based on polymerase chain reaction analysis concluded remarkably a potential role of HPV infection and to some extent H. pylori infection into the contribution of HNSCC malignancies.

Tumor tissue Helicobacter pylori and human papillomavirus infection in head and neck squamous cell carcinoma patients and association with clinicopathological indices: A cross-sectional medical survey

Launching awake craniotomy technique in a resource-limited center: new insights into the patient experience, costs, long-term outcomes, and a narrative review of the literature.

Reza Jabar Zare

Papers

Developing a new dental implant design and comparing its biomechanical features with four designs.

Tumor tissue Helicobacter pylori and human papillomavirus infection in head and neck squamous cell carcinoma patients and association with clinicopathological indices: A cross-sectional medical survey

Launching awake craniotomy technique in a resource-limited center: new insights into the patient experience, costs, long-term outcomes, and a narrative review of the literature.