Background and Objectives: The etiopathogenesis of peri-implant diseases is not well understood. Although dental plaque biofilm related bacteria may be the major player, the longterm integrity of implant devices made from titanium alloys and its effect on peri-implant pathogenesis have been recently questioned. Our group previously reported the presence of titanium ion (Ti) within peri-implant and adjacent gingival crevicular fluid (PICF and GCF) not only at sites diagnosed with peri-implant diseases but also with peri-implant health. We also published on peri-implant tissue response to surgical trauma following implant placement surgery by studying PICF and adjacent GCF cytokine content. The current study aims to evaluate inflammatory response and possible Ti contamination during early phases of peri-implant wound healing following surgical placement of a dental implant fixture via two different surgical protocols (one versus two stage).
Materials and Methods: Patients scheduled to receive their first dental implant placement surgery at an edentulous site were recruited. Demographic information and clinical measurements of patient’s periodontal status were documented at initial visit. Saliva, GCF, PICF and gingival biopsy samples were collected prior to (saliva, GCF, PICF) and during (gingival biopsy) surgery, 1 week, 4 weeks (saliva, GCF, PICF) and at 4 months (saliva, GCF, PICF from all sites, gingival biopsy only from implant sites placed with two stage protocol) post-operatively. The GCF and PICF samples were analyzed for inflammatory mediator content using V- plex assays and GCF, PICF, saliva samples for titanium release using inductively coupled plasma-mass spectrometry [ICP-MS]. Gingival biopsies were processed for H&E and IHC staining to study inflammatory infiltrates and macrophage phenotypes. Multivariable regression analysis was conducted to investigate possible associations between cytokine content, Ti contamination and possible clinical determinants.
Results: Twenty-one periodontally healthy patients (aged 48 ± 3years; 16 female) with 21 newly placed implants were followed up to 4 months. Twenty implant sites (20 patients) were included in CF cytokine analysis, and 11 of these sites (11 patients) were paired with Ti analysis (CF and/or saliva). 10 (48%) sites were placed in pristine bone, and 12 implants (57%) were placed with two-stage protocol. Nine cases (43%) were replacement of a maxillary tooth with 5 cases (56%) replacing missing maxillary posterior tooth. Baseline Ti level was -9.578±11 ppb (ranging -90 to 22) and 0.09±0.05 ppb (ranging -0.1 to 0.54) in GCF and saliva, respectively. Approximately 2-fold increase was noted in adjacent GCF Ti levels for 4 months observation period while this was fluctuating in a time dependent manner from 7- to 57-fold in PICF (p>0.05; GCF and PICF Ti increase with time). Multivariable analysis of log transformed Ti levels revealed that PICF contains higher levels of Ti compared to adjacent GCF throughout the study (2.016; p=0.062). Saliva Ti level increases were negligeable following surgery(p>0.05; saliva Ti changes with time). Multivariable analysis revealed no association between surgical protocols (one vs two stage surgery) and crevicular fluid or saliva log transformation of the Ti levels (3.253, p=0.477; 1.749, p=0.217; respectively).
GCF IL-1β and IL-8 were expressed at high concentrations at baseline and stayed at high levels during healing. Although lower than GCF content, PICF IL-1β and IL-8 concentrations were high up to 4 months (p>0.05). IL-12 and IL-13 levels were similar in GCF and PICF. GCF IL-6 baseline concentration was low and presented an acute increase during the first week in both GCF and PICF (p<0.05). The decrease in PICF IL-6 concentration by 4 months was statistically significant compared to 1 week (p=0.005). Similarly, IL-10 concentration increased during the first 4 weeks and, then decreased to baseline levels for both GCF and PICF (p>0.05). IL-4 and INF-γ were expressed at higher concentrations in PICF compared to GCF and, this increase was time-dependent (p>0.05). A trend of increased IL-4 (both GCF and PICF) was noted with increasing Ti levels (GCF and PICF) and, IL-4, IL-10, and IL-12 with decreasing Ti levels (saliva) (p>0.05). Log transformation of IL-12, IL-1β and IL-8 was mostly negatively associated with two stage compared to one stage surgical protocol possibly representing less soft tissue inflammation with two stage approach (-0.652, p=0.03; -0.620, p=0.08; -0.748, p=0.09; respectively). Multivariable analysis of log transformation IL-4 concentration and log transformation of Ti levels in CF revealed a possible clinical association (1.299; p=0.099) while multivariable analysis of log transformation of IL-4, IL-10 and IL-12 concentrations with log transformation of saliva Ti levels presented a negative association (-1.029, p=0.04; -0.666, p=0.08; -0.793, p=0.042, respectively).
Conclusion: Within the limits of this study, PICF and adjacent GCF Ti contamination occur shortly following dental implant fixture placement and can be observed through osseointegration period. A negligeable increase in saliva Ti levels following surgery also exists up to 4 weeks post-surgery.
Surgical protocol, in turn, does not differentially affect Ti contamination. Among the cytokines locally released following implant placement surgery, IL-4 and IL-12 should be further investigated in relation to peri-implant host response to titanium device. This information, in turn, may help understand some of the inflammatory soft tissue responses and bone remodeling observed during early healing prior to mechanical loading.