Abutment _HOT_
Seiko Aytch
A significant vertical space that is corrected with vertical ridge augmentation may necessitate selection of longer abutments, which would lead to an increased vertical cantilever. This study investigated the influence of different abutment collar heights on single-unit dental implant screw-loosening after cyclic loading. Fifteen implant-abutment assemblies each consisted of an internal hexagonal implant were randomly assigned to 3 groups: Group1, consisting of 5 abutments with 1.5 mm gingival height (GH); Group2, 5 abutments with 3.5 mm GH; and Group3, 5 abutments with 5.5 mm GH. Each specimen was mounted in transparent auto-polymerizing acrylic resin block, and the abutment screw was tightened to 35 Ncm with an electric torque wrench. After 5 minutes, initial torque loss (ITL) was recorded for all specimens. Metal crowns were fabricated with 45 occlusal surface and were placed on the abutments. A cyclic load of 75 N and frequency of 1 Hz were applied perpendicular to the long axis of each specimen. After 500 000 cycles, secondary torque loss (STL) was recorded. One-way ANOVA analysis was used to evaluate the effects of abutment collar height before and after cyclic loading. One-way ANOVA showed that ITL among the groups was not significantly different (P = .52), while STL was significantly different among the groups (P = .008). Post-hoc Tukey HSD tests showed that STL values were significantly different between the abutments with 1.5 mm GH (Group1) and with 5.5 mm GH (Group3) (P = .007). A paired comparison t-test showed that cyclic loading significantly influenced the STL in comparison with the ITL in each group. Within the limitations of this study, it can be concluded that increase in height of the abutment collar could adversely affect the torque loss of the abutment screw.
Objective: While the loosening of the abutment screw is one of the most common complications in implant-supported restorations, there is a lack of comprehensive literatures for mechanism of and factors associated with the loosening of the implant abutment screw. The review was to summarize the mechanism of and factors associated with the loosening of the implant abutment screw.
Overview: A total of 99 relevant articles were included in the literature review. The mechanism of the abutment screw loosening was explained. The factors contributed to abutment screw loosening were divided into five aspects and then expounded respectively.
Conclusions: The internal connection and abutments with anti-rotational and conical designs have better resistance to screw loosening. Cantilevers increase the risk of screw loosening. The effect of surface treatment of the abutment screw is unsure. Clinicians need to tighten the abutment screw to the recommended torque while avoiding repeated tightening and loosening, and increase the frequency of follow-ups to retighten the loosened screws in time.
Clinical significance: While the loosening of the abutment screw is one of the most common complications in implant-supported restorations, there is a lack of comprehensive literatures for mechanism of and factors associated with the loosening of the implant abutment screw. The review was to summarize the mechanism of and factors associated with the loosening of the implant abutment screw, so that clinicians may make better choices in clinical practice.
Attaching the abutment is a fairly quick service. Your dentist will make an incision in your gum tissue at the implant location to expose the implant. Then the abutment is attached. Your dentist may place the prosthesis at the same time. Or your dentist may wait until your gums have healed.
With a better fit and greater overall esthetics, custom titanium abutments are fast becoming the standard choice for dental implants and lab businesses. The AK-1 Abutment Kit for the DGSHAPE DWX-42W wet mill brings production of custom abutments in-house to make the process faster, more convenient, and more cost-effective.
Also known as ulnar impaction syndrome or ulnolunate abutment, ulnocarpal abutment (UCA) is a chronic degenerative condition related to repetitive loading from ulnar impaction. Affected structures include the membranous component of the triangular fibrocartilage (TFC), the ulnar head, the lunate, the triquetrum, and the lunotriquetral (LT) ligament. Predisposing factors include, but are not limited to, positive ulnar variance, malunion of the distal radius, premature closure of the distal radius, Essex-Lopresti fracture, and previous surgical resection of the radial head. Occasionally, UCA may occur in the absence of anatomic structural abnormalities, most commonly from daily activities that cause excessive ulnar carpal loading.
Ulnocarpal abutment (UCA) is a not uncommon cause of pain and limited motion at the ulnar side of the wrist. In patients with UCA, MRI provides accurate assessment of the stage of disease, and allows a specific diagnosis to be made in the majority of cases. The information provided by MRI is vital in determining the proper treatment approach in such patients.
This guidance document was developed as a special control guidance to support the reclassification of the root-form endosseous dental implant device into class II and the reclassification of the endosseous dental implant abutment device into class II. FDA is issuing this guidance in conjunction with a Federal Register notice announcing the final rule reclassifying these device types. Blade-form endosseous dental implants will remain in class III and are not within the scope of this guidance.
The endosseous dental implant abutment device is intended to be used with the root-form endosseous dental implant to aid in prosthetic rehabilitation. After the root-form endosseous dental implant is surgically placed and has healed, the endosseous dental implant abutment device is permanently attached to it in a second surgical procedure. The endosseous dental implant abutment extends above the gum, i.e., it is the transgingival component, which serves as the support for the artificial tooth or other prosthetic. However, if the endosseous dental implant includes an integral transgingival component, it does not need to be used with an abutment.
Following the effective date of the final rule reclassifying these devices, any firm submitting a 510(k) for a root-form endosseous dental implant device or endosseous dental implant abutment device will need to address the issues covered in this special control guidance. However, the firm need only show that its device meets the recommendations of the guidance or in some other way provides equivalent assurances of safety and effectiveness.
FDA believes that special controls, when combined with the general controls, will be sufficient to provide reasonable assurance of the safety and effectiveness of a root-form endosseous dental implant or endosseous dental implant abutment device. Thus, a manufacturer who intends to market a device of either of these generic types should (1) conform to the general controls of the Federal Food, Drug, and Cosmetic Act (the Act), including the premarket notification requirements described in 21 CFR 807, Subpart E, (2) address the specific risks to health associated with root-form endosseous dental implant or endosseous dental implant abutment devices identified in this guidance, and (3) obtain a substantial equivalence determination from FDA prior to marketing the device.
The general discussion above applies to any device subject to a special controls guidance document. The following is a specific discussion of how you should apply this special controls guidance document to a premarket notification submission for a root-form endosseous dental implant or an endosseous dental implant abutment device.
FDA identifies the generic endosseous dental implant abutment device, as announced in the final rule in the Federal Register reclassifying these devices issued concurrently with this guidance, in 21 CFR 872.3630, product code NHA, as follows:
An endosseous dental implant abutment device is a premanufactured prosthetic component directly connected to the endosseous dental implant and is intended for use as an aid in prosthetic rehabilitation.
FDA considers any accessory intended to be directly connected to an endosseous dental implant and placed in the mouth for more than 1 hour to be an abutment within the identification set forth in 21 CFR 872.3630. However, temporary accessories used with endosseous dental implants, i.e., accessories that contact tissue for less than 1 hour, are exempt from 510(k) requirements. 21 CFR 872.3980.
In submissions for root-form endosseous dental implants, we recommend that you provide the characteristics of the abutment connection for each type and size of implant in that submission. In submissions for endosseous dental implant abutments, we recommend that you provide the characteristics of the abutment connection for each type and size of abutment in that submission. In all submissions, these characteristics should include platform size and shape, and connection type.
In the tables below, FDA has identified the risks to health generally associated with the use of the root-form endosseous dental implant and endosseous dental implant abutment devices addressed in this document. The measures recommended to mitigate these identified risks are described in the sections of this guidance document as shown in the table below. You should also conduct a risk analysis, before submitting your 510(k), to identify any other risks specific to your device. The 510(k) should describe the risk analysis method. If you elect to use an alternative approach to address a particular risk identified in this guidance document, or have identified risks additional to those in the guidance, you should provide sufficient detail to support the approach you have used to address that risk.
Root-form endosseous dental implant and endosseous dental implant abutment devices include parts that have permanent contact with tissue/bone and blood. We recommend that you evaluate the biocompatibility of the materials in these parts as described in the International Standard Organization (ISO) standard ISO-10993, Biological Evaluation of Medical Devices Part 1: Evaluation and Testing. Generally, when it is more appropriate to test restorative materials and cements after curing, we recommend that you evaluate these materials as described in ISO 7405:1997 Dentistry - Preclinical Evaluation of Biocompatibility of Medical Devices Used in Dentistry - Test Methods for Dental Materials. We also recommend that you document the results in your design history file as a part of the Quality Systems Requirements (21 CFR 820.30).5 You should select tests appropriate for the duration and level of contact with your device. If identical materials are used in a predicate device with the same type and duration of patient contact, you may identify the predicate device in lieu of performing biocompatibility testing.
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