Presence and Origin of Titanium Particles in Peri-implant Tissues

Implant prostheses have complications that compromise peri-implant health and marginal bone. In addition to pathogenic bacterial biofilm, other determinants, such as implant surface deterioration, Ti particulates in peri-implant tissues, and functional stress have been reported as influencing peri-implant tissue stability. Aim: This thesis investigated the origin and presence of Ti particles in healthy and diseased peri-implant human tissues. Three trials evaluated the effect of acid-forming bacteria and mechanical instrumentation on Ti discs, and the effect of loading on implant surfaces on human participants. Methods: Four experiments involving a combination of in vitro and in vivo trials were performed. The first identified Ti particles in peri-implantitis tissues. Tissue specimens were analyzed under polarized light-microscopy (LM), scanning-electron-microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) analysis. In the second, a microbiological protocol incubated Ti discs achieving viable biofilm, which were investigated in-vitro for microbial-induced-corrosion. The third was an in-vitro trial evaluating topographic and composition changes by ultrasonic instrumentation on TI discs. Surface changes were evaluated using SEM, confocal-laser-scanning-microscopy (CLSM), and EDS. Rinsing solutions were evaluated using induced-coupled-plasma-mass-spectroscopy (ICPMS). The fourth experiment was a human trial on single implant crowns after five years. Exfoliative cytology samples from peri-implant mucosa and junctional epithelial, and control tooth mucosa sites were evaluated using LM, SEM and EDS. ICPMS was carried out on the exfoliative cytology microbrushes. Clinical peri-implant parameters were determined. Results: Firstly, the presence of Ti particles in peri-implantitis tissues was confirmed in 88% of the samples. Granular foreign material was scattered within the connective tissue and the epithelium layer. In most cases the inflammatory infiltrate contained a mixture of acute and chronic inflammatory cells. In the second experiment acid-forming bacterial colonisation of the disc surface was evident after 24 hours and maintained throughout the 7-day observation period. Although Ti isotopes should some variation in the inoculated growth media, ICPMS measurements were hindered due to the high concentrations of sodium (Na) and phosphorus (P) in the broth, this created backscattering during the analyses. The third experiment ultrasonic instrumentation of Ti discs demonstrated significant surface topographical alterations. ICPMS analysis of the rinsing solutions identified Ti and other metal traces. In the fourth experiment, the exfoliative internal and external cytology smears showed black scattered foreign material, which were also noted with SEM and EDS. More particles were identified at the level of the implant-abutment interface when compared to the external mucosal smears. The presence of these particles did not influence peri-implant health. Conclusions: Peri-implantitis biopsies exhibited Ti and other metal particles. The origin of these particles could be related to biomaterials used in oral implantology. Although a consistent viable acid-forming biofilm on Ti specimens has been devised, the measurement of Ti dissolution in the surrounding environment needs further investigation. Ultrasonic instrumentation of Ti surfaces caused topographic and compositional changes, which created Ti particulate. The effect of functional loading between implant components, created wear of Ti implant surfaces. Functional wear of implant components resulted in release of metal particles into the peri-implant milieu. The presence of these particles did not affect the peri-implant health

Presence and Origin of Titanium Particles in Peri-implant Tissues

Implant prostheses have complications that compromise peri-implant health and marginal bone. In addition to pathogenic bacterial biofilm, other determinants, such as implant surface deterioration, Ti particulates in peri-implant tissues, and functional stress have been reported as influencing peri-implant tissue stability. Aim: This thesis investigated the origin and presence of Ti particles in healthy and diseased peri-implant human tissues. Three trials evaluated the effect of acid-forming bacteria and mechanical instrumentation on Ti discs, and the effect of loading on implant surfaces on human participants. Methods: Four experiments involving a combination of in vitro and in vivo trials were performed. The first identified Ti particles in peri-implantitis tissues. Tissue specimens were analyzed under polarized light-microscopy (LM), scanning-electron-microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) analysis. In the second, a microbiological protocol incubated Ti discs achieving viable biofilm, which were investigated in-vitro for microbial-induced-corrosion. The third was an in-vitro trial evaluating topographic and composition changes by ultrasonic instrumentation on TI discs. Surface changes were evaluated using SEM, confocal-laser-scanning-microscopy (CLSM), and EDS. Rinsing solutions were evaluated using induced-coupled-plasma-mass-spectroscopy (ICPMS). The fourth experiment was a human trial on single implant crowns after five years. Exfoliative cytology samples from peri-implant mucosa and junctional epithelial, and control tooth mucosa sites were evaluated using LM, SEM and EDS. ICPMS was carried out on the exfoliative cytology microbrushes. Clinical peri-implant parameters were determined. Results: Firstly, the presence of Ti particles in peri-implantitis tissues was confirmed in 88% of the samples. Granular foreign material was scattered within the connective tissue and the epithelium layer. In most cases the inflammatory infiltrate contained a mixture of acute and chronic inflammatory cells. In the second experiment acid-forming bacterial colonisation of the disc surface was evident after 24 hours and maintained throughout the 7-day observation period. Although Ti isotopes should some variation in the inoculated growth media, ICPMS measurements were hindered due to the high concentrations of sodium (Na) and phosphorus (P) in the broth, this created backscattering during the analyses. The third experiment ultrasonic instrumentation of Ti discs demonstrated significant surface topographical alterations. ICPMS analysis of the rinsing solutions identified Ti and other metal traces. In the fourth experiment, the exfoliative internal and external cytology smears showed black scattered foreign material, which were also noted with SEM and EDS. More particles were identified at the level of the implant-abutment interface when compared to the external mucosal smears. The presence of these particles did not influence peri-implant health. Conclusions: Peri-implantitis biopsies exhibited Ti and other metal particles. The origin of these particles could be related to biomaterials used in oral implantology. Although a consistent viable acid-forming biofilm on Ti specimens has been devised, the measurement of Ti dissolution in the surrounding environment needs further investigation. Ultrasonic instrumentation of Ti surfaces caused topographic and compositional changes, which created Ti particulate. The effect of functional loading between implant components, created wear of Ti implant surfaces. Functional wear of implant components resulted in release of metal particles into the peri-implant milieu. The presence of these particles did not affect the peri-implant health

Effects of Infection Control Barriers on Light Output from a Dental Light-Curing Unit Used in Various Positions

Light-curing units (LCUs) are often subject to clinician-determined factors such as infection control barriers (ICBs) and different positionings of the light tip that may reduce their radiant exposure. The objective of this study was to investigate the individual and cumulative effects of ICBs and LCU positioning on light output. One LCU was used, in combination with five different ICBs and five different distances and angles. ICBs were also tested when placed correctly to manufacturers’ guidelines, and with creases or seams obstructing the light tip. All variables were tested in isolation and in combination with other variables. Measurements were taken from a laboratory-grade spectrometer, giving values of radiant exposure, irradiance and spectral emission. All ICBs, angles and distances showed significant reductions in light output compared to the control (p < 0.001). With increasing angle and distance, the light output was decreased further, with the greatest reduction of 80.6% from the control seen at 40° and 8 mm with an incorrectly placed ICB. When used with an ICB, an increasing angle also showed a protective relationship on the light output. When ICBs are used or when an increase in distance/angle is unavoidable, clinicians should consider compensating for the loss in radiant exposure by increasing curing times

The use of laser therapy for dental implant surface decontamination: a narrative review of in vitro studies

The aim of this narrative review was to critically evaluate in vitro studies assessing the efficacy of lasers in the bacterial decontamination of titanium implant surfaces. The MEDLINE, Web of Knowledge and Embase electronic databases were used to search for articles relating to the use of lasers in the bacterial decontamination of titanium specimen surfaces using predetermined search statements. Clinical studies, case reports, case series, review articles and animal models were excluded. Study selection was carried out independently and then cross-checked by two authors through abstract viewing. Eighteen articles were selected for full-text analysis. Erbium-doped yttrium-aluminium-garnet lasers had a wide range of powers capable of inducing bacterial decontamination. While carbon dioxide and gallium-aluminium-arsenide diode lasers demonstrated the ability to produce bacterial decontamination, the bacterial sensitivity to each varied depending on the species involved. There is no concensus on the laser type or settings that are optimal for bacterial decontamination of titanium implant surfaces as studies employ various test specimens, contamination methodologies, irradiation settings and protocols, and outcome measures resulting in limited study comparability. More investigations are required to provide guidelines for the use of laser therapy in the decontamination of implant surfaces

Effect of a cordless retraction paste on titanium surface: a topographic, chemical and biocompatibility evaluation

Good exposure of the preparation margins and haemostasis in the sulcular gingiva are necessary for accurate impressions to produce precise restorations. The use of cordless retraction paste material in implant dentistry is a relatively novel application. However, few studies have been conducted on the use of retraction pastes and their possible interaction with implant surfaces. Recent literature has described remnants on titanium implant surfaces and expressed the need for an assessment of the biocompatibility of the exposed surface (Chang et al.). This in vitro study evaluated the effect of a cordless gingival retraction paste on sterile titanium disks. Surface chemistry was determined using energy-dispersive X-ray spectroscopy (EDS), and further investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). After exposure to retraction paste, surface chemistry alterations were identified. A fibroblast cell line (L929) was exposed to the disks and the live/dead viability/cytotoxicity assay was used to determine any effects on the proliferation and health of cells. The disks exposed to the retraction paste showed fewer dead cells compared to the unexposed disks. This was statistically significant

Effect of Air-Polishing on Titanium Surfaces, Biofilm Removal, and Biocompatibility: A Pilot Study

Purpose. The aims of this in vitro study were to evaluate morphological changes induced by glycine powder air-polishing on titanium surfaces, biofilm removal, and biocompatibility. Material and Methods. Titanium grade IV discs were allocated into two groups: (1) discs without biofilm and (2) discs for Streptococcus mutans biofilm formation. Discs in each group were further subdivided into (a) no treatment and (b) air-polishing treatment with glycine powder. Discs were characterized by scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS), and confocal microscopy. Bacterial biofilms were quantified using a crystal violet dye-binding assay. Biocompatibility was evaluated by measuring the coverage and viability of L929 fibroblast cells cultured on the discs. Results. Air-polishing increased the roughness of treated discs (P<0.05). EDS analysis did not show significant differences in the chemical composition of treated and nontreated discs. The amount of residual biofilm on treated discs was 8.6-fold lower than untreated controls (P<0.05). Coverage of treated discs by fibroblasts was half that of untreated discs (P<0.05) although both groups had the same cell viability. Conclusions. Air-polishing removed a significant amount of biofilm from titanium surfaces. The “polishing” was accompanied by increased surface roughness, but there were no changes in chemical and elemental compositions, nor the biocompatibility