A technique to retrieve fractured implant screws

An in vitro evaluation of 2 methods for retrieving fractured abutment screw fragments from the intaglio of 4 different implant systems

STATEMENT OF PROBLEM

When an abutment screw fractures, there is no standardized technique for retrieving it from the intaglio of the dental implant.

PURPOSE

The purpose of this in vitro study was to assess the relative efficacy of a commercially available screw fragment retrieval kit with a range of standard dental instruments in regard to success and retrieval time. In addition, the effects of other variables on the success rate of screw fragment retrieval and the retrieval time required were also investigated. Finally, the integrity of the intaglio screw channel of the dental implant was also assessed following retrieval.

MATERIAL AND METHODS

The abutment screws from 4 dental implant systems: Osseotite Certain, Ø4.1 mm (Zimmer Biomet); Osseotite External hexagonal connection micromini, Ø3.25 mm (Zimmer Biomet); Standard Plus Tissue Level, Ø4.8 mm (Institut Straumann AG); and Brånemark Mark III TiUnite, Ø4.1 mm (Nobel Biocare) had notches placed between the first and second coronal threads before being placed in their respective abutments, positioned in the dental implants (n=128), and tightened until the screws fractured. The dental implant specimens were placed in maxillary and mandibular casts at the lateral incisor and first molar sites on both sides. The casts were placed in mannequin heads on a dental chair and assigned to 2 experienced and 2 inexperienced operators who used 2 different retrieval kits to retrieve the screw fragments. Chisquared tests were used to determine the association between the success rate of screw fragment retrieval and the other factors recorded (α=.05), and a binary logistic regression was used to determine the association between the retrieval event and all of the independent variables. Regression models were developed to determine the factors effecting retrieval time.

RESULTS

An overall success rate of 88.3% was achieved for screw fragment retrieval. No statistically significant difference (P>.999) was found in the relative efficacy of the retrieval kits. Univariate analysis identified a statistically significant association (P<.01) in the success of abutment screw fragment retrieval between the Osseotite Certain and the Osseotite External hexagonal connection micromini implant systems. Gamma regression analysis identified significant differences between the time taken to retrieve the screw fragments and the type of dental implant (P<.001), (P<.01). The time taken to retrieve screw fragments in the maxillary arch was significantly longer than for the mandibular arch (P<.05).

CONCLUSIONS

The commercially available screw fragment retrieval kit and the standard dental instruments were equally effective in retrieving the screw fragments. Less time was required to retrieve screw fragments in the mandibular arch than the maxillary arch. The level of experience of the operator had no effect on the ability to successfully retrieve fractured abutment screws.

Management of perishing implants with abutment screw fracture - A systematic review

Aim:

To systematically review the reported techniques, for evaluating the risk and difficulty encountered in the management of fractured abutment screw in accordance with the location of fracture, and to develop a logical sequence in managing an implant abutment screw fracture.

Settings and Design:

Systematic review following PRISMA guidelines.

Materials and Methods:

A systematic search of the PubMed/MEDLINE database for articles published between January 2000 and March 2020 was performed by 2 independent reviewers. Case reports and case series that described the management of fractured implant abutment screw were included. Published articles were qualitatively analyzed employing CARE guidelines and were classified according to the location of screw fracture with respect to implant platform, risk of damage to the implant, and intervention for managing the fractured screw.

Statistical Analysis Used:

Qualitative analyisis.

Results:

A total of 28 articles were included in the review. Two of them explained the management of screw fracture at or above the implant platform and required only mild approach with low risk while the others explained the management of screw fracture below the level of implant platform. Among them, 6 were considered mild approach with low risk, 13 moderate approach with moderate risk, and 8 of them severe approach with high risk.

Conclusion:

Irrespective of the technique, any attempt to retrieve abutment screw fragment poses some risk to the implant which is varying from mild to severe. As the location of fracture is more gingival to the implant platform, difficulty of retrieval as well as risk to the implant increases. The proposed decisionmaking tree will be a useful tool in helping clinicians to manage abutment screw fracture.

Clinical retrospective study of dental implant removal: do patients who require implant removal desire implant prosthesis again?

Background

This study investigated the causes of dental implant removal due to complications, and examined whether patients who had dental implant removal desired re-implant prosthesis treatments.

Material and Methods

A retrospective case–control study was conducted on patients who had their dental implants removed. We investigated whether the removed dental implant was replaced with other implant prostheses. Age, sex, diabetes, smoking, implant site distribution, reason for implant removal, and blade and root-form implants were categorized as predictive variables. The outcome variable was desire for re-implantation or use of other prosthetic methods after implant removal. A logistic regression model was created to identify patient factors that could predict the re-implantation of dental prostheses after implant removal.

Results

A total of 215 dental implants were removed from 143 patients. The most common reason for implant removal was peri-implantitis that was identified in 165 implants. After implant removal, re-implantation was performed in 98 implants (45.6%). Bivariate analyses showed that age, diabetes, implant type, and reason for implant removal were associated with the desire for re-implanted prostheses. The multiple regression model revealed that age, implant type, and reason for implant removal were associated with an increased desire for re-implant prostheses after implant removal.

Conclusions

Re-implantation of prostheses after the removal of dental implants was desired by patients who were younger, had implants placed in the root form, and had implants removed due to prosthetic-related complications.

Key words:Dental implant removal, complications, implant prosthesis, retrospective study, re-implantation.

Alternative approach to salvaging an implant with a fractured screw fragment: A clinical report

Managing fractures of implant abutment screws is challenging because of the uncertainty associated with the removal of the fractured screw fragments. In case of unsuccessful retrieval of the fractured fragment with known techniques, removal and replacement of the implant becomes traumatic and financially burdensome to the patient. This clinical report describes a conservative solution for the management of nonretrievable fractured screws by reconnecting the prostheses to the existing implants by using cut screws. This alternative, cost-effective method obviates the need for surgery and has proved successful and satisfactory for patients.

Incidence of abutment screw failure of single or splinted implant prostheses: A review and update on current clinical status

Osseointegrated implants have been widely used for decades with high survival and success rates. However, mechanical complications continue to be reported in the literature, and their clinical management can be often very challenging for the clinician while there is no consensus on the ideal management. The aim of this manuscript was to review the risk factors of abutment screw complications, to identify the most recent incidence of screw failure in the clinical setting and report on the methodology used and the outcome of intervention. Clinical studies and reports were reviewed that reported on abutment screw looseness and/or fracture. A search of the electronic database PUBMED was conducted in November 2018, including manuscripts published in English from 2004 to 2018. Study selection: animal studies, narrative reviews, expert opinions and communications/letters were excluded. Further exclusion criteria included reports on occlusal prosthetic screws and fracture of abutments, and reports that did not provide adequate data. A total of 12 manuscripts were finally included that reported on single implant crowns or 2-unit implant fixed dental prosthesis. To conclude, the most current abutment screw loosening incidence ranges between 7% and 11%, while the abutment screw fracture incidence was found to be 0.6%. The majority reported on fracture of the screw body. Screw loosening or fracture was often located at the first molar restored area, while the maxillary central incisor area was also reported as an area that presented screw fracture. No single abutment screw failure management can be identified as the ideal treatment approach.

Failure Probability, Stress Distribution and Fracture Analysis of Experimental Screw for Micro Conical Abutment

The aim of this study was to evaluate the failure probability of two types of abutment screws after compressive load and to analyze the stress distribution with finite element method. Sixty (60) single-tooth implant restorations were assembled on titanium implants (e-fix, A.S. Technology - Titanium Fix). The groups were divided into Conventional screw (Screw neck 1.5 ø mm) and Experimental screw (Screw neck constricted with 1.2 ø mm). Specimens were subjected to single load to failure with compressive test according ISO 14801. The fractured specimens were subjected to stereomicroscopy for measurement of remaining screws inside the implant and characterization of fracture origin. Representative specimens were analyzed by scanning electronic microscopy. For finite element method (FEM), an identical 3D model of the two in vitro test groups were used with similar conditions (30º, 100 N load). The stress in the abutment screw was analyzed by von-Mises criteria. The results of strength means were 4132.5 ± 76 MPa and 4528.2 ± 127.2 for conventional and experimental groups, respectively. During microscopy, the mean (mm) of the remaining screw piece inside the implants were 0.97 ± 0.23 and 1.32 ± 0.12 for conventional and experimental groups, respectively. In FEM, the conventional group showed stress concentered in an unfavorable region (peak of 39.23 MPa), while the experimental group showed more stress areas but less concentration than the conventional group (36.6 MPa). In using the tested experimental geometry, the abutment screw can have its strength improved, and the origin of failure can be more favorable to clinical resolution.

Comparison of the maximum hand-generated torque by professors and postgraduate dental students for tightening the abutment screws of dental implants

Background. Dental implants are utilized with an ever-increasing rate. One of the causes of abutment screw loosening has been identified as inadequate preload. The objective behind this study was to compare the maximum hand-generated torque for tightening abutment screws by professors and postgraduate dental students using a digital torquemeter with 0.1 N/cm precision.

Methods. In a laboratory study conducted in Dental Implant Department of Faculty of Dentistry, Tabriz University of Medical Sciences, the maximum hand-generated torque for tightening abutment screws by professors and postgraduate dental students was investigated, using a digital torquemeter with 0.1 N/cm precision.

Results. The participants consisted of 36 (41.9%) females and 50 (58.1%) males, totaling 86 participants, of whom 45 (46.87%) and 41 (53.13%) were university professors and postgraduate dental students, respectively. The mean age of the participants was 33.4±10.2 years with an age range of 25‒60 years; 50 (58.1%) participants were in the 25‒34-year, 23 (26.7%) in the 35‒47-year, and 13 (15.1%) in the 48‒60-year age range. The mean age of professors and postgraduate dental students was 41±8.3 and 25.1±3.3 years, respectively. The means of maximum torques generated by female and male professors were 14.3±3 and 20.8±4.2, respectively. The means of maximum torques generated by female and male postgraduate dental students were 14.7±3.4 and 18.7±4.3, respectively. Statistical analyses showed no significant differences between the mean maximum torques generated by professors and postgraduate dental students (P=0.051).

Conclusion. In the present study, the mean maximum torque generated by professors was higher than that generated by postgraduate dental students. However, the difference was not statistically significant. The mean maximum torque generated by male subjects was significantly higher. No interaction was seen between the studied groups and sex. However, there was a statistically significant difference between the mean maximum torques generated in different age ranges; i.e., the maximum torque generated in the 25‒34-year age range was lower than that in the other two age groups. Finally, the effect of age range on the mean maximum torque was similar in both groups.

An accessory technique for the intraoral removal of a fractured implant abutment screw

As the use of dental implants becomes more prevalent, mechanical complications become more common. When an implant abutment screw fractures, it can be difficult to retrieve the retained fragment. The purpose of this article is to describe a technique to remove the abutment screw fragments without damaging the implant body or its screw threads.

Ultrasonic Oscillations for Conservative Retrieval of a Rare Fracture of Implant Healing Abutment

Dental implants can be rendered useless because of complications related to implant components such as the fracture of abutment screw and prosthetic retaining screw. Removal of such fractured fragments is therefore deemed necessary for the sake of prosthetic restoration. This case report presents a rare incident of healing abutment fracture and details the stepwise and probably the most conservative clinical technique using ultrasonic oscillations for retrieval of fractured screw fragment without affecting the internal surface of the implant. The management was based on the fact that the screw, being an inclined plane, will unthread when subjected to continuous vibrations.

A technique for in vitro fit assessment of multi-unit screw-retained implant restorations: Application of a triple-scan protocol

Recent advances in industrial non-contact scanners offer unprecedented opportunities for quality assessment of dental restorations. The majority of investigations published to date are limited to local two-dimensional results. A triple-scan protocol for virtual fit assessment of multi-unit screw-retained implant restorations is presented in this technical report. The advantages for application in biomechanical research include detailed three-dimensional information on internal component congruence in implant superstructures to be used in mathematical models.