A Methodological Study for the Analysis of Apatite‐Coated Dental Implants Retrieved From Humans

Abstract

The stability of thermally processed hydroxyapatite coatings for oral and orthopedic bioprostheses has been questioned. Information on the chemical changes, which occur with hydroxyapatite biomaterials post-implantation in humans, is lacking. The purpose of this investigation was to begin to examine post-implantation surface changes of hydroxyapatite-coated implants using scanning electron microscopy (SEM), x-ray microanalysis (EDAX), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD). Three retrieved dental implant specimens from humans following clinical failure due to peri-implantitis were examined. Unimplanted cylinders served as controls. Clinically, the retrieved specimens were all enveloped by a fibrous tissue capsule with bone present at the apical extent of the implant. SEM analysis showed that the retrieved surfaces were coated with both calcified and proteinaceous deposits. EDAX scans of the retrieved specimens demonstrated evidence of hydroxyapatite coating loss reflected by increasing titanium and aluminum signals. Other foreign ions such as sodium, chloride, sulfur, silica, and magnesium were detected. XRD of the control specimens showed that the samples were predominantly apatite; however, two peaks were detected in the diffraction pattern, which are not characteristic of hydroxyapatite, indicating that small amounts of one or more other crystalline phases were also present. The retrieved specimens showed slightly larger average crystal size relative to the control sample material, and the non-apatite lines were not present. FTIR evaluation of the retrieved specimens revealed the incorporation of carbonate and organic matrix on or into the hydroxyapatite. Narrowing of and increased detail in the phosphate peaks indicated an increase in average crystal size and/or perfection relative to the controls, as did the XRD results. Based on these results, we conclude that chemical changes may occur within the coating, with the incorporation of carbonate and concomitant reduction in hydroxyapatite coating thickness. Thermodynamic dissolution-reprecipitation of the coating itself and subsequent surface insult by bacterial and local inflammatory components may be involved with these changes.

Clinical Outcome of Hydroxyapatite Coated, Bioactive Glass Coated, and Machined Ti6Al4V Threaded Dental Implant in Human Jaws

“…4, A) indicated that local acidic environment was a reason for HAp coating resorption in abscessed osteotomy sites. 35 The almost intact BAG coating on failed implant at stage 1 (Fig. 3, G) demonstrated that BAG produces an alkaline medium around the implant through dissolution of alkali ions that might prevent early resorption of coating upon failure.…”

Bioactive-glass in periodontal surgery and implant dentistry

“…However, SHA-coated dental implants have been associated with some clinical complications and concerns have been raised about the loss of coatings integrity over time, producing a space between core metal and bone, with resultant marginal bone loss 54) , mechanical instability and high failure rates 55) . SHA coatings are reactive, with the potential to dissolve, release calcium phosphate particulates and lose structural integrity, particularly at the local acidic environment of abscessed osteotomy sites 56) . In-service delamination and exfoliation of the interposed SHA surface layer has been reported by several authors 57,58) , with the observation by some researchers that loose fragments were either surrounded by soft tissues, not by bone 54) , or were excreted from the body as a function of time 4) .…”

“…In-service delamination and exfoliation of the interposed SHA surface layer has been reported by several authors 57,58) , with the observation by some researchers that loose fragments were either surrounded by soft tissues, not by bone 54) , or were excreted from the body as a function of time 4) . Other evidence suggested that the breakdown and dissolution of the coating grain boundaries could elicit a phagocytic response by macrophages 57) or a foreign-body reaction 56) , resulting in greater resorption of bone. It has been established that the rate of surface reaction of B-G to body tissues is very fast (within hours) in comparison to SHA 25) and that calcium sodium phosphosilicates can develop a chemical bond with living bone that is stronger than either the bone or ceramic alone 2) .…”

Surgical laser use in implantology and endodontics

“…33,34 Meticulous attention must be given to curettage of granulation tissue; a laser wavelength that is non-injurious to bone (eg erbium group plus water) can be used to remove this tissue, although careful use of a diode laser, avoiding heat effects (a water spray can be used) and restricting its use to fragmentation and However, there is less evidence of benefi cial use where the implant is coated with a ceramic or hydroxyapatite; this may be mostly due to the micro-complex surface irregularities, which have been shown to harbour bacteria and foreign ions in a failing situation. 35,36 LASERS AND ENDODONTICS All current dental laser wavelengths have been used in a wide range of endodontic treatments, either to aid the preparation stages or obturation techniques of root canal therapy or to alleviate low-grade pulpal injury. 37,38 The areas of endodontics where laser use has been investigated include the following:…”