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The use of osseointegratable titanium dental implants (TDI) has revolutionized clinical dental practice and has shown a high rate

Purpose There are rising concerns about titanium hypersensitivity reaction regarding dental endosseous implants. This review aims to summarize and compare the validity and reliability of the available dermatological and laboratory diagnostic tests regarding titanium hypersensitivity. The following PICO design was used: In Patients with titanium dental implants (P) does epicutaneous testing (ECT) (I), compared to lymphocyte transformation test (LTT) or Memory Lymphocyte Immunostimulation Assay (MELISA) (C) detect hypersensitivity reactions (O)? A literature search was performed including all studies dealing with this topic. Studies regarding orthopedic implants were excluded. Methods Three databases (MEDLINE PubMed, Cochrane Library, SciELO) were screened for suitable studies and an additional manual search was also performed. Literature regarding hypersensitivity reactions in orthopedic implants, hypersensitivity reactions regarding implants not related to dental or maxillofacial surgery, animal studies and in vitro studies were excluded. A quality assessment of all selected full-text articles was performed. Randomized, controlled trials were evaluated with the Cochrane Risk of Bias Tool I. Cohort studies were assessed according to the New Castle–Ottawa Scale and case series according to Moga et al. (Development of a quality appraisal tool for case series studies using a modified Delphi technique. 2012). Results 10 studies were included in the quantitative synthesis and available for the endpoint diagnostics of intolerance reactions to titanium dental implants: 2 clinical studies, 7 cohort studies and 1 case series. The potential for bias (internal validity) for these studies was overall rated as high. Conclusions The study of the available literature regarding ECT and MELISA or LTT in patients with suspected titanium hypersensitivity showed inconsistent results in terms of reliability and validity and thus, those tests should be regarded cautiously. There is strong evidence that titanium hypersensitivity in dental implants is associated with innate immunity: unspecific pro-inflammatory responses due to particle induced hyperreactivity of macrophages or toxicological responses especially towards nanoparticles rather than activation of the adaptive immune system. Therefore, tests detecting allergies do not seem expedient and inflammatory clinical signs should be regarded as leading parameters. Graphical Abstract

Background There is currently a lack of guidelines for clinicians regarding titanium hypersensitivity in implant dentistry. Diagnostic tests such as the epicutaneous test or the lymphocyte transformation test showed inconsistent results regarding reliability and validity and thus, evidence-based consensus recommendations regarding diagnostic and therapeutic options may be helpful in clinical decision-making. Therefore, the German S3 guideline on titanium hypersensitivity in implant dentistry was developed. Findings In the objectives, procedure, voting method and venue were defined and the consensus participants were invited. A systematic literature research was performed, and the overall quality of the evidence was rated according to the GRADE working group. Eight recommendations were formulated within the framework of a structured consensus conference under independent moderation and could be voted on with strong consensus (> 95% agreement). The formulated statements and recommendations were developed in small groups according to the guidelines of the Association of the Scientific Medical Societies in Germany (AWMF) and were discussed and agreed upon in the plenum. Conclusions For reasonable decision-making, a patient’s clinical symptoms should be regarded as leading parameters, which are usually expressed by a local inflammatory reaction with subsequent disturbed osseous integration. Allergy tests, such as the epicutaneous test or the lymphocyte transformation test are not helpful in titanium intolerance assessments, since these tests indicate T cell-mediated allergies, which are not observed in titanium intolerance reactions. Other metals and impurities that might be present in superstructures or alloys also need to be considered as the cause of an intolerance reaction and a trigger for contact sensitization. In the case of a suspected titanium particle-related, local immunologically induced inflammatory reaction with subsequent impaired osseous integration, dental ceramic implants can be considered as a therapeutic option. Graphical Abstract

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