Risk prevention and treatment of implant-supported central screw fracture / 口腔医学

@#In the complications of dental implant treatment, the mechanical complications, such as central screw breakage, are often complex and serious. This article analyzes factors that affect the loosening of the central screw. Understanding relevant risk factors can prompt doctors to take corresponding strategies to reduce the possibility of complications in clinical operations. After encountering broken cases, this paper also gives some ideas and methods of treatment, and finally summarizes clinical suggestions for preventing the central screw fracture.

Repairment of abutment and abutment screw fracture in implant prosthesis: A case report / 대한치과보철학회지

Dental implants are an effective and predictable treatment for restoration of missing teeth. However, as the use of implants increases, complications are also increasing. The mechanical complications are not only highly frequent, but also increasing as life span of an implant increases, thus, solutions should be prepared. In this report, we will present a case dealing with abutment fracture and abutment screw fracture which are the most common mechanical complication of the implant, focusing on preserving and reusing existing components by reconstructing only the damaged parts.

Comparison of implant component fractures in external and internal type: A 12-year retrospective study

PURPOSE: The aim of this study was to compare the fracture of implant component behavior of external and internal type of implants to suggest directions for successful implant treatment. MATERIALS AND METHODS: Data were collected from the clinical records of all patients who received WARANTEC implants at Seoul National University Dental Hospital from February 2002 to January 2014 for 12 years. Total number of implants was 1,289 and an average of 3.2 implants was installed per patient. Information about abutment connection type, implant locations, platform sizes was collected with presence of implant component fractures and their managements. SPSS statistics software (version 24.0, IBM) was used for the statistical analysis. RESULTS: Overall fracture was significantly more frequent in internal type. The most frequently fractured component was abutment in internal type implants, and screw fracture occurred most frequently in external type. Analyzing by fractured components, screw fracture was the most frequent in the maxillary anterior region and the most abutment fracture occurred in the maxillary posterior region and screw fractures occurred more frequently in NP (narrow platform) and abutment fractures occurred more frequently in RP (regular platform). CONCLUSION: In external type, screw fracture occurred most frequently, especially in the maxillary anterior region, and in internal type, abutment fracture occurred frequently in the posterior region. placement of an external type implant rather than an internal type is recommended for the posterior region where abutment fractures frequently occur.

Repeated Complication Following Atlantoaxial Fusion: A Case Report

A patients with atlantoaixial instability and osodontoideum underwent atlantoaixial fusion (Harms and Melcher technique) with demineralized bone matrix. But, unfortunately, the both pedicle screws in C2 were fractured within 9 weeks follow-up periods after several suspected episode of neck hyper-flexion. Fractured screws were not contact to occipital bone in several imaging studies, but it could irritate the occipital bone when neck extension because the relatively close distance between the occipital bone and C1 posterior arch. The patient underwent revision operation with translaminar screw fixation with autologus iliac bone graft. Postsurgical course were uneventful except donor site pain, but the bony fusion was not satisfied after 4 months follow-up. The patient re-underwent revision operation in other hospital. Continuous complication after atlantoaixial fusion is rare, but the clinical course could be unlucky to patients. Postoperative immobilization could be important to prevent the unintended clinical course of patients.

Application of finite element analysis to evaluate implant fractures / 대한치과보철학회지

Statement of problem. Higher fracture rates were reported for Branemark implants placed in the maxilla and for 3.75 mm diameter implants installed in the posterior region. Purpose. The purpose of this study was to investigate the fracture of a fixture by finite element analysis and to compare different diameter of fixtures according to the level of alveolar bone resorption. Material and Methods. The single implant and prosthesis was modeled in accordance with the geometric designs for the 3i implant systems. Models were processed by the software programs HyperMesh and ANSA. Three-dimensional finite element models were developed for; (1) a regular titanium implant 3.75 mm in diameter and 13 mm in length (2) a regular titanium implant 4.0 mm in diameter and 13 mm in length (3) a wide titanium implant 5.0 mm in diameter and 13 mm in length each with a cementation type abutment and titanium alloy screw. The abutment screws were subjected to a tightening torque of 30 Ncm. The amount of preload was hypothesized as 650 N, and round and flat type prostheses were 12 mm in diameter, 9 mm in height were loaded to 600 N. Four loading offset points (0, 2, 4, and 6 mm from the center of the implants) were evaluated. To evaluate fixture fracture by alveolar bone resorption, we investigated the stress distribution of the fixtures according to different alveolar bone loss levels (0, 1.5, 3.5, and 5.0 mm of alveolar bone loss). Using these 12 models (four degrees of bone loss and three implant diameters), the effects of loading offset, the effect of alveolar bone resorption and the size of fixtures were evaluated. The PAM-CRASH 2G simulation software was used for analysis of stress. The PAM-VIEW and HyperView programs were used for post processing. Results. The results from our experiment are as follows: 1. Preload maintains implant-abutment joint stability within a limited offset point against occlusal force. 2. Von Mises stress of the implant, abutment screw, abutment, and bone was decreased with increasing of the implant diameter. 3. With severe advancing of alveolar bone resorption, fracture of the 3.75 and the 4.0 mm diameter implant was possible. 4. With increasing of bending stress by loading offset, fracture of the abutment screw was possible.