Journal of Oral Implantology April 2014 - (Page 146)

RESEARCH The Effect of Different Implant-Abutment Connections on Screw Joint Stability Konstantinos X. Michalakis, DDS, PhD, MSc1,2* Pasquale (Lino) Calvani, DDS, MD, MSc1 Sinan Muftu, PhD3 Argiris Pissiotis, DMD, PhD, MS2 Hiroshi Hirayama, DDS, DMD, MS1 Dental implants with an internal connection have been designed to establish a better stress distribution when lateral external forces act on the prosthesis and minimize the forces transmitted to the fastening screw. In the present study, 10 externally and 10 internally hexed implants were tested with a compressive force applied with an Instron Universal machine. Four cycles of loading-unloading were applied to each specimen to achieve displacements of 0.5, 1, 2, and 2.5 mm. The mean loads for the first cycle were 256.70 N for the external connection and 256 N for the internal connection implants. The independent t test did not reveal any significant differences among the 2 tested groups (P ¼ .780). For the second cycle, the mean loads needed for a displacement of 1 mm were 818.19 N and 780.20 N for the external connection and the internal connection implants, respectively. The independent t test revealed significant differences among the 2 tested groups (P , .001). In the third cycle, the mean load values for a 2-mm displacement were 1394.10 N and 1225.00 N. The independent t test revealed significant differences among the 2 tested groups (P , .001). The mean loads for the fourth cycle were 1488.00 N for the external connection and 1029.00 N for the internal connection implants. These loads were required for a displacement of 2.5 mm. The independent t test revealed significant differences among the 2 tested groups (P , .001). The results of this in vitro study suggest that the internal connection design of the examined implant system could not prevent screw loosening during overloading. No implant or prosthesis failure was noticed in either group. Key Words: implantology, external-internal connection, compressive force INTRODUCTION D ental implants are successfully used for the prosthetic rehabilitation of both partial and complete edentulism. Their use constitutes a viable treatment modality. 1,2 Originally, dental implants featured an external hex at the prospective connection with the abutment, which 1 Division of Graduate and Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, Mass 2 Department of Removable Prosthodontics, Aristotle University of Thessaloniki, School of Dentistry, Thessaloniki, Greece 3 Northeastern University, Department of Mechanical and Industrial Engineering, Boston, Mass * Corresponding author, e-mail: kmichalakis@hotmail.com DOI: 10.1563/AAID-JOI-D-11-00032 146 Vol. XL /No. Two /2014 supports the prosthesis. The height of the walls of the hexagon is usually less than 1 mm. It has been claimed that because the short height, the walls of the hexagon cannot provide proper resistance for lateral forces acting on the prosthesis.3,4 Therefore, it has been assumed that the bending moments are transmitted to the fastening screw, which connects the prosthetic abutment with the implant. This hypothesis seems to be in accordance with data from prospective and retrospective clinical studies, which suggest that one of the most common complications found in implant-supported prostheses is screw loosening and/or fracture.5-7 Dental implants with an internal connection have been designed and manufactured to establish a better stress distribution when lateral external

Table of Contents for the Digital Edition of Journal of Oral Implantology April 2014

Consolidated Standards of Reporting Trials (CONSORT): Answering the Call for JOI’s Endorsement
Photoelastic Analysis of Stress Distribution With Different Implant Systems
Influence of Abutment Screw Design and Surface Coating on the Bending Flexural Strength of the Implant Set
Comparison of Implant-Abutment Interface Misfits After Casting and Soldering Procedures
Evaluation of Accuracy of Casts of Multiple Internal Connection Implant Prosthesis Obtained From Different Impression Materials and Techniques: An In Vitro Study
The Effect of Different Implant-Abutment Connections on Screw Joint Stability
Effects of pH and Elevated Glucose Levels on the Electrochemical Behavior of Dental Implants
Finite Element Analysis of Provisional Structures of Implant-Supported Complete Prostheses
Saliva Versus Peri-implant Inflammation: Quantification of IL-1b in Partially and Totally Edentulous Patients
Heat Generated During Seating of Dental Implant Fixtures
An Alternative Approach for Augmenting the Anterior Maxilla Using Autogenous Free Gingival Bone Graft for Implant Retained Prosthesis
Nasopalatine Duct Cyst, a Delayed Complication to Successful Dental Implant Placement: Diagnosis and Surgical Management
The Custom Endosteal Implant: Histology and Case Report of a Retrieved Maxillary Custom Osseous-Integrated Implant Nine Years in Service
Occlusal Concepts Application in Resolving Implant Prosthetic Failure: Case Report
Three-Year Follow-Up of a Single Immediate Implant Placed in an Infected Area: A New Approach for Harvesting Autogenous Symphysis Graft
Use of Stress Analysis Methods to Evaluate the Biomechanics of Oral Rehabilitation With Implants

Journal of Oral Implantology April 2014