Prosthetic failures in dental implant therapy

Abstract

Both fixed and removable implant-supported prostheses are well-established methods for replacing missing teeth in partially or fully edentulous patients. Numerous systematic reviews have been performed in recent years to evaluate the survival and complication rates of implant-retained fixed dental prostheses and implant-retained overdentures, displaying high 5-year survival rates ranging from 97.1% for fixed dental prostheses to 95%-100% for implant-retained overdentures. However, the survival rates only represent the prostheses remaining in use for a defined follow-up time, and do not account for the potential prosthetic complications that may have arisen and influence the general success of the implant treatment. The most common technical complications of fixed implant-retained single crowns are crown fracture, fractures of ceramic implant abutments, and esthetic problems. The predominant technical complication at multiple-unit, implant-retained fixed dental prostheses is fracture/chipping of the veneering ceramic. Reported technical complications for implant-retained overdentures are overdenture fracture or chipping of the veneer materials, whereas mechanical complications include implant fracture, attachment failure, and attachment housing or insert complications. To reduce the risk of such failures, a comprehensive pretreatment diagnostic work-up is essential, including defining the prosthetic goal with the aid of a wax-up or set-up and the associated ideal, prosthetically oriented three-dimensional implant position. Furthermore, selection of the ideal type of prosthesis, including the respective implant components and materials, is important for clinical long-term treatment success.

Keywords: failure; implant restorations; mechanical; prosthetic complications; survival; technical.

FIGURE 1

Multiple chipping of the veneering ceramic at a zirconia‐based implant single crown

FIGURE 2

A and B, Clinical situation of a 24‐year‐old male patient with a failing left central incisor. The tooth lost vitality following an accident during the childhood of this patient. C and D, Replacement of the incisor by means of a bone‐level type of implant, with the aid of a guided surgery approach. E and F, Simultaneous guided bone regeneration to augment the volume of the ridge surrounding the implant with a xenograft and a collagen membrane (BioOss granules, BioGide membrane; Geistlich Pharma, Wolhusen, Switzerland). Submerged healing of the implant. G and H, Status after second stage surgery and insertion of a screw‐retained fixed implant provisional. Conditioning of the peri‐implant mucosa in a stepwise approach by application of a light‐curing resin (Tetric Flow, Ivoclar Vivadent, Schaan, Liechtenstein) to the submucosal part of the implant provisional, in order to receive a natural emergence profile of the implant restoration. I, Fixture‐level implant impression with a customized implant impression copying the submucosal part of the conditioned implant provisional for the final restoration. J, Fabrication and try‐in of the white zirconia abutment, foreseen for the support of a laboratory‐cemented glass‐ceramic crown, screw‐retained at delivery. K, Paleish, whitish discoloration of the peri‐implant mucosa at the implant in the left central incisor region. Status 30 min after insertion. L, Four‐year recall examination of the implant crown; note the still visible paleish appearance of the peri‐implant soft tissues, caused by the white zirconia substructure

FIGURE 3

A‐C, Three‐unit cemented, zirconia ceramic‐fixed implant‐supported FDP (iFDP) exhibiting several prosthetic complications at the same time: multiple chippings of the veneering ceramic occurring at the buccal cusps only a short time after the insertion of the restoration because of inadequate occlusal design (ie, a cusp‐to‐cusp relationship of the maxillary and mandibular reconstructions in maximal intercuspidation). After the removal of the iFDP for the repair, remnants of excess resin cements were detected, which were associated with the reported difficulty of removal of excess cement at multiple‐unit cemented iFDPs

FIGURE 4

Summary of different implant‐retained overdenture attachment types

FIGURE 5

Clinical presentation of a patient with a fractured cast bar. A, Failure occurred after 10 months of clinical service; B, appearance of the fractured bar from the buccal aspect; C, Scanning electron microscope image of the fracture surface; a cave‐like casting defect is indicated by arrows. The mode of failure was detected as brittle overload fracture

FIGURE 6

Extensive wear of locator attachment as a result of implant misalignment

FIGURE 7

Types of prosthetic reinforcements for IODs. IODs, implant‐retained overdentures; PEKK, polyetherketoneketone; PMMA, polymethylmetharcylate